diff --git a/codereview.cfg b/codereview.cfg
index 77a74f1..1f58fdb 100644
--- a/codereview.cfg
+++ b/codereview.cfg
@@ -1 +1,2 @@
-branch: master
+branch: dev.typeparams
+parent-branch: master
diff --git a/misc/cgo/errors/testdata/err2.go b/misc/cgo/errors/testdata/err2.go
index a90598f..aa94158 100644
--- a/misc/cgo/errors/testdata/err2.go
+++ b/misc/cgo/errors/testdata/err2.go
@@ -91,10 +91,18 @@
 
 	// issue 26745
 	_ = func(i int) int {
-		return C.i + 1 // ERROR HERE: 14
+		// typecheck reports at column 14 ('+'), but types2 reports at
+		// column 10 ('C').
+		// TODO(mdempsky): Investigate why, and see if types2 can be
+		// updated to match typecheck behavior.
+		return C.i + 1 // ERROR HERE: \b(10|14)\b
 	}
 	_ = func(i int) {
-		C.fi(i) // ERROR HERE: 7
+		// typecheck reports at column 7 ('('), but types2 reports at
+		// column 8 ('i'). The types2 position is more correct, but
+		// updating typecheck here is fundamentally challenging because of
+		// IR limitations.
+		C.fi(i) // ERROR HERE: \b(7|8)\b
 	}
 
 	C.fi = C.fi // ERROR HERE
diff --git a/src/cmd/compile/abi-internal.md b/src/cmd/compile/abi-internal.md
index 2bb4055..3619aea 100644
--- a/src/cmd/compile/abi-internal.md
+++ b/src/cmd/compile/abi-internal.md
@@ -505,6 +505,128 @@
 
 The x87 floating-point control word is not used by Go on amd64.
 
+### arm64 architecture
+
+The arm64 architecture uses R0 – R15 for integer arguments and results.
+
+It uses F0 – F15 for floating-point arguments and results.
+
+*Rationale*: 16 integer registers and 16 floating-point registers are
+more than enough for passing arguments and results for practically all
+functions (see Appendix). While there are more registers available,
+using more registers provides little benefit. Additionally, it will add
+overhead on code paths where the number of arguments are not statically
+known (e.g. reflect call), and will consume more stack space when there
+is only limited stack space available to fit in the nosplit limit.
+
+Registers R16 and R17 are permanent scratch registers. They are also
+used as scratch registers by the linker (Go linker and external
+linker) in trampolines.
+
+Register R18 is reserved and never used. It is reserved for the OS
+on some platforms (e.g. macOS).
+
+Registers R19 – R25 are permanent scratch registers. In addition,
+R27 is a permanent scratch register used by the assembler when
+expanding instructions.
+
+Floating-point registers F16 – F31 are also permanent scratch
+registers.
+
+Special-purpose registers are as follows:
+
+| Register | Call meaning | Return meaning | Body meaning |
+| --- | --- | --- | --- |
+| RSP | Stack pointer | Same | Same |
+| R30 | Link register | Same | Scratch (non-leaf functions) |
+| R29 | Frame pointer | Same | Same |
+| R28 | Current goroutine | Same | Same |
+| R27 | Scratch | Scratch | Scratch |
+| R26 | Closure context pointer | Scratch | Scratch |
+| R18 | Reserved (not used) | Same | Same |
+| ZR  | Zero value | Same | Same |
+
+*Rationale*: These register meanings are compatible with Go’s
+stack-based calling convention.
+
+*Rationale*: The link register, R30, holds the function return
+address at the function entry. For functions that have frames
+(including most non-leaf functions), R30 is saved to stack in the
+function prologue and restored in the epilogue. Within the function
+body, R30 can be used as a scratch register.
+
+*Implementation note*: Registers with fixed meaning at calls but not
+in function bodies must be initialized by "injected" calls such as
+signal-based panics.
+
+#### Stack layout
+
+The stack pointer, RSP, grows down and is always aligned to 16 bytes.
+
+*Rationale*: The arm64 architecture requires the stack pointer to be
+16-byte aligned.
+
+A function's stack frame, after the frame is created, is laid out as
+follows:
+
+    +------------------------------+
+    | ... locals ...               |
+    | ... outgoing arguments ...   |
+    | return PC                    | ← RSP points to
+    | frame pointer on entry       |
+    +------------------------------+ ↓ lower addresses
+
+The "return PC" is loaded to the link register, R30, as part of the
+arm64 `CALL` operation.
+
+On entry, a function subtracts from RSP to open its stack frame, and
+saves the values of R30 and R29 at the bottom of the frame.
+Specifically, R30 is saved at 0(RSP) and R29 is saved at -8(RSP),
+after RSP is updated.
+
+A leaf function that does not require any stack space may omit the
+saved R30 and R29.
+
+The Go ABI's use of R29 as a frame pointer register is compatible with
+arm64 architecture requirement so that Go can inter-operate with platform
+debuggers and profilers.
+
+This stack layout is used by both register-based (ABIInternal) and
+stack-based (ABI0) calling conventions.
+
+#### Flags
+
+The arithmetic status flags (NZCV) are treated like scratch registers
+and not preserved across calls.
+All other bits in PSTATE are system flags and are not modified by Go.
+
+The floating-point status register (FPSR) is treated like scratch
+registers and not preserved across calls.
+
+At calls, the floating-point control register (FPCR) bits are always
+set as follows:
+
+| Flag | Bit | Value | Meaning |
+| --- | --- | --- | --- |
+| DN  | 25 | 0 | Propagate NaN operands |
+| FZ  | 24 | 0 | Do not flush to zero |
+| RC  | 23/22 | 0 (RN) | Round to nearest, choose even if tied |
+| IDE | 15 | 0 | Denormal operations trap disabled |
+| IXE | 12 | 0 | Inexact trap disabled |
+| UFE | 11 | 0 | Underflow trap disabled |
+| OFE | 10 | 0 | Overflow trap disabled |
+| DZE | 9 | 0 | Divide-by-zero trap disabled |
+| IOE | 8 | 0 | Invalid operations trap disabled |
+| NEP | 2 | 0 | Scalar operations do not affect higher elements in vector registers |
+| AH  | 1 | 0 | No alternate handling of de-normal inputs |
+| FIZ | 0 | 0 | Do not zero de-normals |
+
+*Rationale*: Having a fixed FPCR control configuration allows Go
+functions to use floating-point and vector (SIMD) operations without
+modifying or saving the FPCR.
+Functions are allowed to modify it between calls (as long as they
+restore it), but as of this writing Go code never does.
+
 ## Future directions
 
 ### Spill path improvements
diff --git a/src/cmd/compile/internal/amd64/galign.go b/src/cmd/compile/internal/amd64/galign.go
index 2785aa0..ca44263 100644
--- a/src/cmd/compile/internal/amd64/galign.go
+++ b/src/cmd/compile/internal/amd64/galign.go
@@ -18,11 +18,10 @@
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock
-	arch.LoadRegResults = loadRegResults
+	arch.LoadRegResult = loadRegResult
 	arch.SpillArgReg = spillArgReg
 }
diff --git a/src/cmd/compile/internal/amd64/ggen.go b/src/cmd/compile/internal/amd64/ggen.go
index 1484ad5..b8dce81 100644
--- a/src/cmd/compile/internal/amd64/ggen.go
+++ b/src/cmd/compile/internal/amd64/ggen.go
@@ -57,7 +57,6 @@
 func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, state *uint32) *obj.Prog {
 	const (
 		r13 = 1 << iota // if R13 is already zeroed.
-		x15             // if X15 is already zeroed. Note: in new ABI, X15 is always zero.
 	)
 
 	if cnt == 0 {
@@ -85,11 +84,6 @@
 		}
 		p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_R13, 0, obj.TYPE_MEM, x86.REG_SP, off)
 	} else if !isPlan9 && cnt <= int64(8*types.RegSize) {
-		if !buildcfg.Experiment.RegabiG && *state&x15 == 0 {
-			p = pp.Append(p, x86.AXORPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_REG, x86.REG_X15, 0)
-			*state |= x15
-		}
-
 		for i := int64(0); i < cnt/16; i++ {
 			p = pp.Append(p, x86.AMOVUPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_SP, off+i*16)
 		}
@@ -98,10 +92,6 @@
 			p = pp.Append(p, x86.AMOVUPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_SP, off+cnt-int64(16))
 		}
 	} else if !isPlan9 && (cnt <= int64(128*types.RegSize)) {
-		if !buildcfg.Experiment.RegabiG && *state&x15 == 0 {
-			p = pp.Append(p, x86.AXORPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_REG, x86.REG_X15, 0)
-			*state |= x15
-		}
 		// Save DI to r12. With the amd64 Go register abi, DI can contain
 		// an incoming parameter, whereas R12 is always scratch.
 		p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_DI, 0, obj.TYPE_REG, x86.REG_R12, 0)
diff --git a/src/cmd/compile/internal/amd64/ssa.go b/src/cmd/compile/internal/amd64/ssa.go
index ca5f36e..30dba05 100644
--- a/src/cmd/compile/internal/amd64/ssa.go
+++ b/src/cmd/compile/internal/amd64/ssa.go
@@ -823,7 +823,7 @@
 		p.To.Reg = v.Args[0].Reg()
 		ssagen.AddAux2(&p.To, v, sc.Off64())
 	case ssa.OpAMD64MOVOstorezero:
-		if !buildcfg.Experiment.RegabiG || s.ABI != obj.ABIInternal {
+		if s.ABI != obj.ABIInternal {
 			// zero X15 manually
 			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
 		}
@@ -914,7 +914,7 @@
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = v.Reg()
 	case ssa.OpAMD64DUFFZERO:
-		if !buildcfg.Experiment.RegabiG || s.ABI != obj.ABIInternal {
+		if s.ABI != obj.ABIInternal {
 			// zero X15 manually
 			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
 		}
@@ -997,22 +997,26 @@
 		// Closure pointer is DX.
 		ssagen.CheckLoweredGetClosurePtr(v)
 	case ssa.OpAMD64LoweredGetG:
-		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABIInternal {
+		if s.ABI == obj.ABIInternal {
 			v.Fatalf("LoweredGetG should not appear in ABIInternal")
 		}
 		r := v.Reg()
 		getgFromTLS(s, r)
 	case ssa.OpAMD64CALLstatic:
-		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABI0 && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABIInternal {
+		if s.ABI == obj.ABI0 && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABIInternal {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
 		s.Call(v)
-		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABIInternal && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABI0 {
+		if s.ABI == obj.ABIInternal && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABI0 {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
@@ -1304,9 +1308,11 @@
 	case ssa.BlockRet:
 		s.Prog(obj.ARET)
 	case ssa.BlockRetJmp:
-		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABI0 && b.Aux.(*obj.LSym).ABI() == obj.ABIInternal {
+		if s.ABI == obj.ABI0 && b.Aux.(*obj.LSym).ABI() == obj.ABIInternal {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
@@ -1348,20 +1354,15 @@
 	}
 }
 
-func loadRegResults(s *ssagen.State, f *ssa.Func) {
-	for _, o := range f.OwnAux.ABIInfo().OutParams() {
-		n := o.Name.(*ir.Name)
-		rts, offs := o.RegisterTypesAndOffsets()
-		for i := range o.Registers {
-			p := s.Prog(loadByType(rts[i]))
-			p.From.Type = obj.TYPE_MEM
-			p.From.Name = obj.NAME_AUTO
-			p.From.Sym = n.Linksym()
-			p.From.Offset = n.FrameOffset() + offs[i]
-			p.To.Type = obj.TYPE_REG
-			p.To.Reg = ssa.ObjRegForAbiReg(o.Registers[i], f.Config)
-		}
-	}
+func loadRegResult(s *ssagen.State, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog {
+	p := s.Prog(loadByType(t))
+	p.From.Type = obj.TYPE_MEM
+	p.From.Name = obj.NAME_AUTO
+	p.From.Sym = n.Linksym()
+	p.From.Offset = n.FrameOffset() + off
+	p.To.Type = obj.TYPE_REG
+	p.To.Reg = reg
+	return p
 }
 
 func spillArgReg(pp *objw.Progs, p *obj.Prog, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog {
diff --git a/src/cmd/compile/internal/arm/galign.go b/src/cmd/compile/internal/arm/galign.go
index d685002..23e52ba 100644
--- a/src/cmd/compile/internal/arm/galign.go
+++ b/src/cmd/compile/internal/arm/galign.go
@@ -18,7 +18,6 @@
 	arch.SoftFloat = buildcfg.GOARM == 5
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/arm64/galign.go b/src/cmd/compile/internal/arm64/galign.go
index d3db37e..3ebd860de 100644
--- a/src/cmd/compile/internal/arm64/galign.go
+++ b/src/cmd/compile/internal/arm64/galign.go
@@ -18,9 +18,10 @@
 	arch.PadFrame = padframe
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock
+	arch.LoadRegResult = loadRegResult
+	arch.SpillArgReg = spillArgReg
 }
diff --git a/src/cmd/compile/internal/arm64/ssa.go b/src/cmd/compile/internal/arm64/ssa.go
index 0c997bc..c3319f9 100644
--- a/src/cmd/compile/internal/arm64/ssa.go
+++ b/src/cmd/compile/internal/arm64/ssa.go
@@ -10,6 +10,7 @@
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/logopt"
+	"cmd/compile/internal/objw"
 	"cmd/compile/internal/ssa"
 	"cmd/compile/internal/ssagen"
 	"cmd/compile/internal/types"
@@ -161,6 +162,18 @@
 		p.From.Type = obj.TYPE_REG
 		p.From.Reg = v.Args[0].Reg()
 		ssagen.AddrAuto(&p.To, v)
+	case ssa.OpArgIntReg, ssa.OpArgFloatReg:
+		// The assembler needs to wrap the entry safepoint/stack growth code with spill/unspill
+		// The loop only runs once.
+		for _, a := range v.Block.Func.RegArgs {
+			// Pass the spill/unspill information along to the assembler, offset by size of
+			// the saved LR slot.
+			addr := ssagen.SpillSlotAddr(a, arm64.REGSP, base.Ctxt.FixedFrameSize())
+			s.FuncInfo().AddSpill(
+				obj.RegSpill{Reg: a.Reg, Addr: addr, Unspill: loadByType(a.Type), Spill: storeByType(a.Type)})
+		}
+		v.Block.Func.RegArgs = nil
+		ssagen.CheckArgReg(v)
 	case ssa.OpARM64ADD,
 		ssa.OpARM64SUB,
 		ssa.OpARM64AND,
@@ -1101,8 +1114,34 @@
 		v.Fatalf("FlagConstant op should never make it to codegen %v", v.LongString())
 	case ssa.OpARM64InvertFlags:
 		v.Fatalf("InvertFlags should never make it to codegen %v", v.LongString())
-	case ssa.OpClobber, ssa.OpClobberReg:
-		// TODO: implement for clobberdead experiment. Nop is ok for now.
+	case ssa.OpClobber:
+		// MOVW	$0xdeaddead, REGTMP
+		// MOVW	REGTMP, (slot)
+		// MOVW	REGTMP, 4(slot)
+		p := s.Prog(arm64.AMOVW)
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = 0xdeaddead
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = arm64.REGTMP
+		p = s.Prog(arm64.AMOVW)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = arm64.REGTMP
+		p.To.Type = obj.TYPE_MEM
+		p.To.Reg = arm64.REGSP
+		ssagen.AddAux(&p.To, v)
+		p = s.Prog(arm64.AMOVW)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = arm64.REGTMP
+		p.To.Type = obj.TYPE_MEM
+		p.To.Reg = arm64.REGSP
+		ssagen.AddAux2(&p.To, v, v.AuxInt+4)
+	case ssa.OpClobberReg:
+		x := uint64(0xdeaddeaddeaddead)
+		p := s.Prog(arm64.AMOVD)
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = int64(x)
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = v.Reg()
 	default:
 		v.Fatalf("genValue not implemented: %s", v.LongString())
 	}
@@ -1266,3 +1305,22 @@
 		b.Fatalf("branch not implemented: %s", b.LongString())
 	}
 }
+
+func loadRegResult(s *ssagen.State, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog {
+	p := s.Prog(loadByType(t))
+	p.From.Type = obj.TYPE_MEM
+	p.From.Name = obj.NAME_AUTO
+	p.From.Sym = n.Linksym()
+	p.From.Offset = n.FrameOffset() + off
+	p.To.Type = obj.TYPE_REG
+	p.To.Reg = reg
+	return p
+}
+
+func spillArgReg(pp *objw.Progs, p *obj.Prog, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog {
+	p = pp.Append(p, storeByType(t), obj.TYPE_REG, reg, 0, obj.TYPE_MEM, 0, n.FrameOffset()+off)
+	p.To.Name = obj.NAME_PARAM
+	p.To.Sym = n.Linksym()
+	p.Pos = p.Pos.WithNotStmt()
+	return p
+}
diff --git a/src/cmd/compile/internal/base/bootstrap_false.go b/src/cmd/compile/internal/base/bootstrap_false.go
new file mode 100644
index 0000000..de86644
--- /dev/null
+++ b/src/cmd/compile/internal/base/bootstrap_false.go
@@ -0,0 +1,11 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !compiler_bootstrap
+
+package base
+
+// CompilerBootstrap reports whether the current compiler binary was
+// built with -tags=compiler_bootstrap.
+const CompilerBootstrap = false
diff --git a/src/cmd/compile/internal/base/bootstrap_true.go b/src/cmd/compile/internal/base/bootstrap_true.go
new file mode 100644
index 0000000..81a17e1
--- /dev/null
+++ b/src/cmd/compile/internal/base/bootstrap_true.go
@@ -0,0 +1,11 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build compiler_bootstrap
+
+package base
+
+// CompilerBootstrap reports whether the current compiler binary was
+// built with -tags=compiler_bootstrap.
+const CompilerBootstrap = true
diff --git a/src/cmd/compile/internal/base/debug.go b/src/cmd/compile/internal/base/debug.go
index 71712ab..e2245e1 100644
--- a/src/cmd/compile/internal/base/debug.go
+++ b/src/cmd/compile/internal/base/debug.go
@@ -44,8 +44,11 @@
 	Panic                int    `help:"show all compiler panics"`
 	Slice                int    `help:"print information about slice compilation"`
 	SoftFloat            int    `help:"force compiler to emit soft-float code"`
+	SyncFrames           int    `help:"how many writer stack frames to include at sync points in unified export data"`
 	TypeAssert           int    `help:"print information about type assertion inlining"`
 	TypecheckInl         int    `help:"eager typechecking of inline function bodies"`
+	Unified              int    `help:"enable unified IR construction"`
+	UnifiedQuirks        int    `help:"enable unified IR construction's quirks mode"`
 	WB                   int    `help:"print information about write barriers"`
 	ABIWrap              int    `help:"print information about ABI wrapper generation"`
 
diff --git a/src/cmd/compile/internal/base/flag.go b/src/cmd/compile/internal/base/flag.go
index 42c0c1b..b8b205f 100644
--- a/src/cmd/compile/internal/base/flag.go
+++ b/src/cmd/compile/internal/base/flag.go
@@ -159,7 +159,11 @@
 	Flag.LinkShared = &Ctxt.Flag_linkshared
 	Flag.Shared = &Ctxt.Flag_shared
 	Flag.WB = true
+
 	Debug.InlFuncsWithClosures = 1
+	if buildcfg.Experiment.Unified {
+		Debug.Unified = 1
+	}
 
 	Debug.Checkptr = -1 // so we can tell whether it is set explicitly
 
diff --git a/src/cmd/compile/internal/typecheck/mapfile_mmap.go b/src/cmd/compile/internal/base/mapfile_mmap.go
similarity index 93%
rename from src/cmd/compile/internal/typecheck/mapfile_mmap.go
rename to src/cmd/compile/internal/base/mapfile_mmap.go
index 298b385..c1616db 100644
--- a/src/cmd/compile/internal/typecheck/mapfile_mmap.go
+++ b/src/cmd/compile/internal/base/mapfile_mmap.go
@@ -5,7 +5,7 @@
 //go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd
 // +build darwin dragonfly freebsd linux netbsd openbsd
 
-package typecheck
+package base
 
 import (
 	"os"
@@ -19,7 +19,7 @@
 
 // mapFile returns length bytes from the file starting at the
 // specified offset as a string.
-func mapFile(f *os.File, offset, length int64) (string, error) {
+func MapFile(f *os.File, offset, length int64) (string, error) {
 	// POSIX mmap: "The implementation may require that off is a
 	// multiple of the page size."
 	x := offset & int64(os.Getpagesize()-1)
diff --git a/src/cmd/compile/internal/typecheck/mapfile_read.go b/src/cmd/compile/internal/base/mapfile_read.go
similarity index 85%
rename from src/cmd/compile/internal/typecheck/mapfile_read.go
rename to src/cmd/compile/internal/base/mapfile_read.go
index 9637ab9..01796a9 100644
--- a/src/cmd/compile/internal/typecheck/mapfile_read.go
+++ b/src/cmd/compile/internal/base/mapfile_read.go
@@ -5,14 +5,14 @@
 //go:build !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd
 // +build !darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd
 
-package typecheck
+package base
 
 import (
 	"io"
 	"os"
 )
 
-func mapFile(f *os.File, offset, length int64) (string, error) {
+func MapFile(f *os.File, offset, length int64) (string, error) {
 	buf := make([]byte, length)
 	_, err := io.ReadFull(io.NewSectionReader(f, offset, length), buf)
 	if err != nil {
diff --git a/src/cmd/compile/internal/base/print.go b/src/cmd/compile/internal/base/print.go
index b095fd7..4afe2eb 100644
--- a/src/cmd/compile/internal/base/print.go
+++ b/src/cmd/compile/internal/base/print.go
@@ -233,6 +233,27 @@
 	ErrorExit()
 }
 
+// Assert reports "assertion failed" with Fatalf, unless b is true.
+func Assert(b bool) {
+	if !b {
+		Fatalf("assertion failed")
+	}
+}
+
+// Assertf reports a fatal error with Fatalf, unless b is true.
+func Assertf(b bool, format string, args ...interface{}) {
+	if !b {
+		Fatalf(format, args...)
+	}
+}
+
+// AssertfAt reports a fatal error with FatalfAt, unless b is true.
+func AssertfAt(b bool, pos src.XPos, format string, args ...interface{}) {
+	if !b {
+		FatalfAt(pos, format, args...)
+	}
+}
+
 // hcrash crashes the compiler when -h is set, to find out where a message is generated.
 func hcrash() {
 	if Flag.LowerH != 0 {
diff --git a/src/cmd/compile/internal/escape/assign.go b/src/cmd/compile/internal/escape/assign.go
new file mode 100644
index 0000000..80697bf
--- /dev/null
+++ b/src/cmd/compile/internal/escape/assign.go
@@ -0,0 +1,120 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+)
+
+// addr evaluates an addressable expression n and returns a hole
+// that represents storing into the represented location.
+func (e *escape) addr(n ir.Node) hole {
+	if n == nil || ir.IsBlank(n) {
+		// Can happen in select case, range, maybe others.
+		return e.discardHole()
+	}
+
+	k := e.heapHole()
+
+	switch n.Op() {
+	default:
+		base.Fatalf("unexpected addr: %v", n)
+	case ir.ONAME:
+		n := n.(*ir.Name)
+		if n.Class == ir.PEXTERN {
+			break
+		}
+		k = e.oldLoc(n).asHole()
+	case ir.OLINKSYMOFFSET:
+		break
+	case ir.ODOT:
+		n := n.(*ir.SelectorExpr)
+		k = e.addr(n.X)
+	case ir.OINDEX:
+		n := n.(*ir.IndexExpr)
+		e.discard(n.Index)
+		if n.X.Type().IsArray() {
+			k = e.addr(n.X)
+		} else {
+			e.discard(n.X)
+		}
+	case ir.ODEREF, ir.ODOTPTR:
+		e.discard(n)
+	case ir.OINDEXMAP:
+		n := n.(*ir.IndexExpr)
+		e.discard(n.X)
+		e.assignHeap(n.Index, "key of map put", n)
+	}
+
+	return k
+}
+
+func (e *escape) addrs(l ir.Nodes) []hole {
+	var ks []hole
+	for _, n := range l {
+		ks = append(ks, e.addr(n))
+	}
+	return ks
+}
+
+func (e *escape) assignHeap(src ir.Node, why string, where ir.Node) {
+	e.expr(e.heapHole().note(where, why), src)
+}
+
+// assignList evaluates the assignment dsts... = srcs....
+func (e *escape) assignList(dsts, srcs []ir.Node, why string, where ir.Node) {
+	ks := e.addrs(dsts)
+	for i, k := range ks {
+		var src ir.Node
+		if i < len(srcs) {
+			src = srcs[i]
+		}
+
+		if dst := dsts[i]; dst != nil {
+			// Detect implicit conversion of uintptr to unsafe.Pointer when
+			// storing into reflect.{Slice,String}Header.
+			if dst.Op() == ir.ODOTPTR && ir.IsReflectHeaderDataField(dst) {
+				e.unsafeValue(e.heapHole().note(where, why), src)
+				continue
+			}
+
+			// Filter out some no-op assignments for escape analysis.
+			if src != nil && isSelfAssign(dst, src) {
+				if base.Flag.LowerM != 0 {
+					base.WarnfAt(where.Pos(), "%v ignoring self-assignment in %v", e.curfn, where)
+				}
+				k = e.discardHole()
+			}
+		}
+
+		e.expr(k.note(where, why), src)
+	}
+
+	e.reassigned(ks, where)
+}
+
+// reassigned marks the locations associated with the given holes as
+// reassigned, unless the location represents a variable declared and
+// assigned exactly once by where.
+func (e *escape) reassigned(ks []hole, where ir.Node) {
+	if as, ok := where.(*ir.AssignStmt); ok && as.Op() == ir.OAS && as.Y == nil {
+		if dst, ok := as.X.(*ir.Name); ok && dst.Op() == ir.ONAME && dst.Defn == nil {
+			// Zero-value assignment for variable declared without an
+			// explicit initial value. Assume this is its initialization
+			// statement.
+			return
+		}
+	}
+
+	for _, k := range ks {
+		loc := k.dst
+		// Variables declared by range statements are assigned on every iteration.
+		if n, ok := loc.n.(*ir.Name); ok && n.Defn == where && where.Op() != ir.ORANGE {
+			continue
+		}
+		loc.reassigned = true
+	}
+}
diff --git a/src/cmd/compile/internal/escape/call.go b/src/cmd/compile/internal/escape/call.go
new file mode 100644
index 0000000..9e5abed
--- /dev/null
+++ b/src/cmd/compile/internal/escape/call.go
@@ -0,0 +1,428 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/src"
+)
+
+// call evaluates a call expressions, including builtin calls. ks
+// should contain the holes representing where the function callee's
+// results flows.
+func (e *escape) call(ks []hole, call ir.Node) {
+	var init ir.Nodes
+	e.callCommon(ks, call, &init, nil)
+	if len(init) != 0 {
+		call.(*ir.CallExpr).PtrInit().Append(init...)
+	}
+}
+
+func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir.Func) {
+
+	// argumentPragma handles escape analysis of argument *argp to the
+	// given hole. If the function callee is known, pragma is the
+	// function's pragma flags; otherwise 0.
+	argumentFunc := func(fn *ir.Name, k hole, argp *ir.Node) {
+		e.rewriteArgument(argp, init, call, fn, wrapper)
+
+		e.expr(k.note(call, "call parameter"), *argp)
+	}
+
+	argument := func(k hole, argp *ir.Node) {
+		argumentFunc(nil, k, argp)
+	}
+
+	switch call.Op() {
+	default:
+		ir.Dump("esc", call)
+		base.Fatalf("unexpected call op: %v", call.Op())
+
+	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
+		call := call.(*ir.CallExpr)
+		typecheck.FixVariadicCall(call)
+		typecheck.FixMethodCall(call)
+
+		// Pick out the function callee, if statically known.
+		//
+		// TODO(mdempsky): Change fn from *ir.Name to *ir.Func, but some
+		// functions (e.g., runtime builtins, method wrappers, generated
+		// eq/hash functions) don't have it set. Investigate whether
+		// that's a concern.
+		var fn *ir.Name
+		switch call.Op() {
+		case ir.OCALLFUNC:
+			// If we have a direct call to a closure (not just one we were
+			// able to statically resolve with ir.StaticValue), mark it as
+			// such so batch.outlives can optimize the flow results.
+			if call.X.Op() == ir.OCLOSURE {
+				call.X.(*ir.ClosureExpr).Func.SetClosureCalled(true)
+			}
+
+			switch v := ir.StaticValue(call.X); v.Op() {
+			case ir.ONAME:
+				if v := v.(*ir.Name); v.Class == ir.PFUNC {
+					fn = v
+				}
+			case ir.OCLOSURE:
+				fn = v.(*ir.ClosureExpr).Func.Nname
+			case ir.OMETHEXPR:
+				fn = ir.MethodExprName(v)
+			}
+		case ir.OCALLMETH:
+			base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+		}
+
+		fntype := call.X.Type()
+		if fn != nil {
+			fntype = fn.Type()
+		}
+
+		if ks != nil && fn != nil && e.inMutualBatch(fn) {
+			for i, result := range fn.Type().Results().FieldSlice() {
+				e.expr(ks[i], ir.AsNode(result.Nname))
+			}
+		}
+
+		var recvp *ir.Node
+		if call.Op() == ir.OCALLFUNC {
+			// Evaluate callee function expression.
+			//
+			// Note: We use argument and not argumentFunc, because while
+			// call.X here may be an argument to runtime.{new,defer}proc,
+			// it's not an argument to fn itself.
+			argument(e.discardHole(), &call.X)
+		} else {
+			recvp = &call.X.(*ir.SelectorExpr).X
+		}
+
+		args := call.Args
+		if recv := fntype.Recv(); recv != nil {
+			if recvp == nil {
+				// Function call using method expression. Recevier argument is
+				// at the front of the regular arguments list.
+				recvp = &args[0]
+				args = args[1:]
+			}
+
+			argumentFunc(fn, e.tagHole(ks, fn, recv), recvp)
+		}
+
+		for i, param := range fntype.Params().FieldSlice() {
+			argumentFunc(fn, e.tagHole(ks, fn, param), &args[i])
+		}
+
+	case ir.OINLCALL:
+		call := call.(*ir.InlinedCallExpr)
+		e.stmts(call.Body)
+		for i, result := range call.ReturnVars {
+			k := e.discardHole()
+			if ks != nil {
+				k = ks[i]
+			}
+			e.expr(k, result)
+		}
+
+	case ir.OAPPEND:
+		call := call.(*ir.CallExpr)
+		args := call.Args
+
+		// Appendee slice may flow directly to the result, if
+		// it has enough capacity. Alternatively, a new heap
+		// slice might be allocated, and all slice elements
+		// might flow to heap.
+		appendeeK := ks[0]
+		if args[0].Type().Elem().HasPointers() {
+			appendeeK = e.teeHole(appendeeK, e.heapHole().deref(call, "appendee slice"))
+		}
+		argument(appendeeK, &args[0])
+
+		if call.IsDDD {
+			appendedK := e.discardHole()
+			if args[1].Type().IsSlice() && args[1].Type().Elem().HasPointers() {
+				appendedK = e.heapHole().deref(call, "appended slice...")
+			}
+			argument(appendedK, &args[1])
+		} else {
+			for i := 1; i < len(args); i++ {
+				argument(e.heapHole(), &args[i])
+			}
+		}
+
+	case ir.OCOPY:
+		call := call.(*ir.BinaryExpr)
+		argument(e.discardHole(), &call.X)
+
+		copiedK := e.discardHole()
+		if call.Y.Type().IsSlice() && call.Y.Type().Elem().HasPointers() {
+			copiedK = e.heapHole().deref(call, "copied slice")
+		}
+		argument(copiedK, &call.Y)
+
+	case ir.OPANIC:
+		call := call.(*ir.UnaryExpr)
+		argument(e.heapHole(), &call.X)
+
+	case ir.OCOMPLEX:
+		call := call.(*ir.BinaryExpr)
+		argument(e.discardHole(), &call.X)
+		argument(e.discardHole(), &call.Y)
+
+	case ir.ODELETE, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+		call := call.(*ir.CallExpr)
+		fixRecoverCall(call)
+		for i := range call.Args {
+			argument(e.discardHole(), &call.Args[i])
+		}
+
+	case ir.OLEN, ir.OCAP, ir.OREAL, ir.OIMAG, ir.OCLOSE:
+		call := call.(*ir.UnaryExpr)
+		argument(e.discardHole(), &call.X)
+
+	case ir.OUNSAFEADD, ir.OUNSAFESLICE:
+		call := call.(*ir.BinaryExpr)
+		argument(ks[0], &call.X)
+		argument(e.discardHole(), &call.Y)
+	}
+}
+
+// goDeferStmt analyzes a "go" or "defer" statement.
+//
+// In the process, it also normalizes the statement to always use a
+// simple function call with no arguments and no results. For example,
+// it rewrites:
+//
+//	defer f(x, y)
+//
+// into:
+//
+//	x1, y1 := x, y
+//	defer func() { f(x1, y1) }()
+func (e *escape) goDeferStmt(n *ir.GoDeferStmt) {
+	k := e.heapHole()
+	if n.Op() == ir.ODEFER && e.loopDepth == 1 {
+		// Top-level defer arguments don't escape to the heap,
+		// but they do need to last until they're invoked.
+		k = e.later(e.discardHole())
+
+		// force stack allocation of defer record, unless
+		// open-coded defers are used (see ssa.go)
+		n.SetEsc(ir.EscNever)
+	}
+
+	call := n.Call
+
+	init := n.PtrInit()
+	init.Append(ir.TakeInit(call)...)
+	e.stmts(*init)
+
+	// If the function is already a zero argument/result function call,
+	// just escape analyze it normally.
+	if call, ok := call.(*ir.CallExpr); ok && call.Op() == ir.OCALLFUNC {
+		if sig := call.X.Type(); sig.NumParams()+sig.NumResults() == 0 {
+			if clo, ok := call.X.(*ir.ClosureExpr); ok && n.Op() == ir.OGO {
+				clo.IsGoWrap = true
+			}
+			e.expr(k, call.X)
+			return
+		}
+	}
+
+	// Create a new no-argument function that we'll hand off to defer.
+	fn := ir.NewClosureFunc(n.Pos(), true)
+	fn.SetWrapper(true)
+	fn.Nname.SetType(types.NewSignature(types.LocalPkg, nil, nil, nil, nil))
+	fn.Body = []ir.Node{call}
+
+	clo := fn.OClosure
+	if n.Op() == ir.OGO {
+		clo.IsGoWrap = true
+	}
+
+	e.callCommon(nil, call, init, fn)
+	e.closures = append(e.closures, closure{e.spill(k, clo), clo})
+
+	// Create new top level call to closure.
+	n.Call = ir.NewCallExpr(call.Pos(), ir.OCALL, clo, nil)
+	ir.WithFunc(e.curfn, func() {
+		typecheck.Stmt(n.Call)
+	})
+}
+
+// rewriteArgument rewrites the argument *argp of the given call expression.
+// fn is the static callee function, if known.
+// wrapper is the go/defer wrapper function for call, if any.
+func (e *escape) rewriteArgument(argp *ir.Node, init *ir.Nodes, call ir.Node, fn *ir.Name, wrapper *ir.Func) {
+	var pragma ir.PragmaFlag
+	if fn != nil && fn.Func != nil {
+		pragma = fn.Func.Pragma
+	}
+
+	// unsafeUintptr rewrites "uintptr(ptr)" arguments to syscall-like
+	// functions, so that ptr is kept alive and/or escaped as
+	// appropriate. unsafeUintptr also reports whether it modified arg0.
+	unsafeUintptr := func(arg0 ir.Node) bool {
+		if pragma&(ir.UintptrKeepAlive|ir.UintptrEscapes) == 0 {
+			return false
+		}
+
+		// If the argument is really a pointer being converted to uintptr,
+		// arrange for the pointer to be kept alive until the call returns,
+		// by copying it into a temp and marking that temp
+		// still alive when we pop the temp stack.
+		if arg0.Op() != ir.OCONVNOP || !arg0.Type().IsUintptr() {
+			return false
+		}
+		arg := arg0.(*ir.ConvExpr)
+
+		if !arg.X.Type().IsUnsafePtr() {
+			return false
+		}
+
+		// Create and declare a new pointer-typed temp variable.
+		tmp := e.wrapExpr(arg.Pos(), &arg.X, init, call, wrapper)
+
+		if pragma&ir.UintptrEscapes != 0 {
+			e.flow(e.heapHole().note(arg, "//go:uintptrescapes"), e.oldLoc(tmp))
+		}
+
+		if pragma&ir.UintptrKeepAlive != 0 {
+			call := call.(*ir.CallExpr)
+
+			// SSA implements CallExpr.KeepAlive using OpVarLive, which
+			// doesn't support PAUTOHEAP variables. I tried changing it to
+			// use OpKeepAlive, but that ran into issues of its own.
+			// For now, the easy solution is to explicitly copy to (yet
+			// another) new temporary variable.
+			keep := tmp
+			if keep.Class == ir.PAUTOHEAP {
+				keep = e.copyExpr(arg.Pos(), tmp, call.PtrInit(), wrapper, false)
+			}
+
+			keep.SetAddrtaken(true) // ensure SSA keeps the tmp variable
+			call.KeepAlive = append(call.KeepAlive, keep)
+		}
+
+		return true
+	}
+
+	visit := func(pos src.XPos, argp *ir.Node) {
+		// Optimize a few common constant expressions. By leaving these
+		// untouched in the call expression, we let the wrapper handle
+		// evaluating them, rather than taking up closure context space.
+		switch arg := *argp; arg.Op() {
+		case ir.OLITERAL, ir.ONIL, ir.OMETHEXPR:
+			return
+		case ir.ONAME:
+			if arg.(*ir.Name).Class == ir.PFUNC {
+				return
+			}
+		}
+
+		if unsafeUintptr(*argp) {
+			return
+		}
+
+		if wrapper != nil {
+			e.wrapExpr(pos, argp, init, call, wrapper)
+		}
+	}
+
+	// Peel away any slice lits.
+	if arg := *argp; arg.Op() == ir.OSLICELIT {
+		list := arg.(*ir.CompLitExpr).List
+		for i := range list {
+			visit(arg.Pos(), &list[i])
+		}
+	} else {
+		visit(call.Pos(), argp)
+	}
+}
+
+// wrapExpr replaces *exprp with a temporary variable copy. If wrapper
+// is non-nil, the variable will be captured for use within that
+// function.
+func (e *escape) wrapExpr(pos src.XPos, exprp *ir.Node, init *ir.Nodes, call ir.Node, wrapper *ir.Func) *ir.Name {
+	tmp := e.copyExpr(pos, *exprp, init, e.curfn, true)
+
+	if wrapper != nil {
+		// Currently for "defer i.M()" if i is nil it panics at the point
+		// of defer statement, not when deferred function is called.  We
+		// need to do the nil check outside of the wrapper.
+		if call.Op() == ir.OCALLINTER && exprp == &call.(*ir.CallExpr).X.(*ir.SelectorExpr).X {
+			check := ir.NewUnaryExpr(pos, ir.OCHECKNIL, ir.NewUnaryExpr(pos, ir.OITAB, tmp))
+			init.Append(typecheck.Stmt(check))
+		}
+
+		e.oldLoc(tmp).captured = true
+
+		tmp = ir.NewClosureVar(pos, wrapper, tmp)
+	}
+
+	*exprp = tmp
+	return tmp
+}
+
+// copyExpr creates and returns a new temporary variable within fn;
+// appends statements to init to declare and initialize it to expr;
+// and escape analyzes the data flow if analyze is true.
+func (e *escape) copyExpr(pos src.XPos, expr ir.Node, init *ir.Nodes, fn *ir.Func, analyze bool) *ir.Name {
+	if ir.HasUniquePos(expr) {
+		pos = expr.Pos()
+	}
+
+	tmp := typecheck.TempAt(pos, fn, expr.Type())
+
+	stmts := []ir.Node{
+		ir.NewDecl(pos, ir.ODCL, tmp),
+		ir.NewAssignStmt(pos, tmp, expr),
+	}
+	typecheck.Stmts(stmts)
+	init.Append(stmts...)
+
+	if analyze {
+		e.newLoc(tmp, false)
+		e.stmts(stmts)
+	}
+
+	return tmp
+}
+
+// tagHole returns a hole for evaluating an argument passed to param.
+// ks should contain the holes representing where the function
+// callee's results flows. fn is the statically-known callee function,
+// if any.
+func (e *escape) tagHole(ks []hole, fn *ir.Name, param *types.Field) hole {
+	// If this is a dynamic call, we can't rely on param.Note.
+	if fn == nil {
+		return e.heapHole()
+	}
+
+	if e.inMutualBatch(fn) {
+		return e.addr(ir.AsNode(param.Nname))
+	}
+
+	// Call to previously tagged function.
+
+	var tagKs []hole
+
+	esc := parseLeaks(param.Note)
+	if x := esc.Heap(); x >= 0 {
+		tagKs = append(tagKs, e.heapHole().shift(x))
+	}
+
+	if ks != nil {
+		for i := 0; i < numEscResults; i++ {
+			if x := esc.Result(i); x >= 0 {
+				tagKs = append(tagKs, ks[i].shift(x))
+			}
+		}
+	}
+
+	return e.teeHole(tagKs...)
+}
diff --git a/src/cmd/compile/internal/escape/desugar.go b/src/cmd/compile/internal/escape/desugar.go
new file mode 100644
index 0000000..8b3cc25
--- /dev/null
+++ b/src/cmd/compile/internal/escape/desugar.go
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+)
+
+// TODO(mdempsky): Desugaring doesn't belong during escape analysis,
+// but for now it's the most convenient place for some rewrites.
+
+// fixRecoverCall rewrites an ORECOVER call into ORECOVERFP,
+// adding an explicit frame pointer argument.
+// If call is not an ORECOVER call, it's left unmodified.
+func fixRecoverCall(call *ir.CallExpr) {
+	if call.Op() != ir.ORECOVER {
+		return
+	}
+
+	pos := call.Pos()
+
+	// FP is equal to caller's SP plus FixedFrameSize().
+	var fp ir.Node = ir.NewCallExpr(pos, ir.OGETCALLERSP, nil, nil)
+	if off := base.Ctxt.FixedFrameSize(); off != 0 {
+		fp = ir.NewBinaryExpr(fp.Pos(), ir.OADD, fp, ir.NewInt(off))
+	}
+	// TODO(mdempsky): Replace *int32 with unsafe.Pointer, without upsetting checkptr.
+	fp = ir.NewConvExpr(pos, ir.OCONVNOP, types.NewPtr(types.Types[types.TINT32]), fp)
+
+	call.SetOp(ir.ORECOVERFP)
+	call.Args = []ir.Node{typecheck.Expr(fp)}
+}
diff --git a/src/cmd/compile/internal/escape/escape.go b/src/cmd/compile/internal/escape/escape.go
index cd56f07..61e0121 100644
--- a/src/cmd/compile/internal/escape/escape.go
+++ b/src/cmd/compile/internal/escape/escape.go
@@ -6,15 +6,11 @@
 
 import (
 	"fmt"
-	"math"
-	"strings"
 
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/logopt"
-	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
-	"cmd/internal/src"
 )
 
 // Escape analysis.
@@ -118,90 +114,8 @@
 	loopDepth int
 }
 
-// An location represents an abstract location that stores a Go
-// variable.
-type location struct {
-	n         ir.Node  // represented variable or expression, if any
-	curfn     *ir.Func // enclosing function
-	edges     []edge   // incoming edges
-	loopDepth int      // loopDepth at declaration
-
-	// resultIndex records the tuple index (starting at 1) for
-	// PPARAMOUT variables within their function's result type.
-	// For non-PPARAMOUT variables it's 0.
-	resultIndex int
-
-	// derefs and walkgen are used during walkOne to track the
-	// minimal dereferences from the walk root.
-	derefs  int // >= -1
-	walkgen uint32
-
-	// dst and dstEdgeindex track the next immediate assignment
-	// destination location during walkone, along with the index
-	// of the edge pointing back to this location.
-	dst        *location
-	dstEdgeIdx int
-
-	// queued is used by walkAll to track whether this location is
-	// in the walk queue.
-	queued bool
-
-	// escapes reports whether the represented variable's address
-	// escapes; that is, whether the variable must be heap
-	// allocated.
-	escapes bool
-
-	// transient reports whether the represented expression's
-	// address does not outlive the statement; that is, whether
-	// its storage can be immediately reused.
-	transient bool
-
-	// paramEsc records the represented parameter's leak set.
-	paramEsc leaks
-
-	captured   bool // has a closure captured this variable?
-	reassigned bool // has this variable been reassigned?
-	addrtaken  bool // has this variable's address been taken?
-}
-
-// An edge represents an assignment edge between two Go variables.
-type edge struct {
-	src    *location
-	derefs int // >= -1
-	notes  *note
-}
-
-// Fmt is called from node printing to print information about escape analysis results.
-func Fmt(n ir.Node) string {
-	text := ""
-	switch n.Esc() {
-	case ir.EscUnknown:
-		break
-
-	case ir.EscHeap:
-		text = "esc(h)"
-
-	case ir.EscNone:
-		text = "esc(no)"
-
-	case ir.EscNever:
-		text = "esc(N)"
-
-	default:
-		text = fmt.Sprintf("esc(%d)", n.Esc())
-	}
-
-	if n.Op() == ir.ONAME {
-		n := n.(*ir.Name)
-		if loc, ok := n.Opt.(*location); ok && loc.loopDepth != 0 {
-			if text != "" {
-				text += " "
-			}
-			text += fmt.Sprintf("ld(%d)", loc.loopDepth)
-		}
-	}
-
-	return text
+func Funcs(all []ir.Node) {
+	ir.VisitFuncsBottomUp(all, Batch)
 }
 
 // Batch performs escape analysis on a minimal batch of
@@ -269,8 +183,14 @@
 
 	// Allocate locations for local variables.
 	for _, n := range fn.Dcl {
-		if n.Op() == ir.ONAME {
-			e.newLoc(n, false)
+		e.newLoc(n, false)
+	}
+
+	// Also for hidden parameters (e.g., the ".this" parameter to a
+	// method value wrapper).
+	if fn.OClosure == nil {
+		for _, n := range fn.ClosureVars {
+			e.newLoc(n.Canonical(), false)
 		}
 	}
 
@@ -342,1316 +262,6 @@
 	}
 }
 
-// Below we implement the methods for walking the AST and recording
-// data flow edges. Note that because a sub-expression might have
-// side-effects, it's important to always visit the entire AST.
-//
-// For example, write either:
-//
-//     if x {
-//         e.discard(n.Left)
-//     } else {
-//         e.value(k, n.Left)
-//     }
-//
-// or
-//
-//     if x {
-//         k = e.discardHole()
-//     }
-//     e.value(k, n.Left)
-//
-// Do NOT write:
-//
-//    // BAD: possibly loses side-effects within n.Left
-//    if !x {
-//        e.value(k, n.Left)
-//    }
-
-// stmt evaluates a single Go statement.
-func (e *escape) stmt(n ir.Node) {
-	if n == nil {
-		return
-	}
-
-	lno := ir.SetPos(n)
-	defer func() {
-		base.Pos = lno
-	}()
-
-	if base.Flag.LowerM > 2 {
-		fmt.Printf("%v:[%d] %v stmt: %v\n", base.FmtPos(base.Pos), e.loopDepth, e.curfn, n)
-	}
-
-	e.stmts(n.Init())
-
-	switch n.Op() {
-	default:
-		base.Fatalf("unexpected stmt: %v", n)
-
-	case ir.ODCLCONST, ir.ODCLTYPE, ir.OFALL, ir.OINLMARK:
-		// nop
-
-	case ir.OBREAK, ir.OCONTINUE, ir.OGOTO:
-		// TODO(mdempsky): Handle dead code?
-
-	case ir.OBLOCK:
-		n := n.(*ir.BlockStmt)
-		e.stmts(n.List)
-
-	case ir.ODCL:
-		// Record loop depth at declaration.
-		n := n.(*ir.Decl)
-		if !ir.IsBlank(n.X) {
-			e.dcl(n.X)
-		}
-
-	case ir.OLABEL:
-		n := n.(*ir.LabelStmt)
-		switch e.labels[n.Label] {
-		case nonlooping:
-			if base.Flag.LowerM > 2 {
-				fmt.Printf("%v:%v non-looping label\n", base.FmtPos(base.Pos), n)
-			}
-		case looping:
-			if base.Flag.LowerM > 2 {
-				fmt.Printf("%v: %v looping label\n", base.FmtPos(base.Pos), n)
-			}
-			e.loopDepth++
-		default:
-			base.Fatalf("label missing tag")
-		}
-		delete(e.labels, n.Label)
-
-	case ir.OIF:
-		n := n.(*ir.IfStmt)
-		e.discard(n.Cond)
-		e.block(n.Body)
-		e.block(n.Else)
-
-	case ir.OFOR, ir.OFORUNTIL:
-		n := n.(*ir.ForStmt)
-		e.loopDepth++
-		e.discard(n.Cond)
-		e.stmt(n.Post)
-		e.block(n.Body)
-		e.loopDepth--
-
-	case ir.ORANGE:
-		// for Key, Value = range X { Body }
-		n := n.(*ir.RangeStmt)
-
-		// X is evaluated outside the loop.
-		tmp := e.newLoc(nil, false)
-		e.expr(tmp.asHole(), n.X)
-
-		e.loopDepth++
-		ks := e.addrs([]ir.Node{n.Key, n.Value})
-		if n.X.Type().IsArray() {
-			e.flow(ks[1].note(n, "range"), tmp)
-		} else {
-			e.flow(ks[1].deref(n, "range-deref"), tmp)
-		}
-		e.reassigned(ks, n)
-
-		e.block(n.Body)
-		e.loopDepth--
-
-	case ir.OSWITCH:
-		n := n.(*ir.SwitchStmt)
-
-		if guard, ok := n.Tag.(*ir.TypeSwitchGuard); ok {
-			var ks []hole
-			if guard.Tag != nil {
-				for _, cas := range n.Cases {
-					cv := cas.Var
-					k := e.dcl(cv) // type switch variables have no ODCL.
-					if cv.Type().HasPointers() {
-						ks = append(ks, k.dotType(cv.Type(), cas, "switch case"))
-					}
-				}
-			}
-			e.expr(e.teeHole(ks...), n.Tag.(*ir.TypeSwitchGuard).X)
-		} else {
-			e.discard(n.Tag)
-		}
-
-		for _, cas := range n.Cases {
-			e.discards(cas.List)
-			e.block(cas.Body)
-		}
-
-	case ir.OSELECT:
-		n := n.(*ir.SelectStmt)
-		for _, cas := range n.Cases {
-			e.stmt(cas.Comm)
-			e.block(cas.Body)
-		}
-	case ir.ORECV:
-		// TODO(mdempsky): Consider e.discard(n.Left).
-		n := n.(*ir.UnaryExpr)
-		e.exprSkipInit(e.discardHole(), n) // already visited n.Ninit
-	case ir.OSEND:
-		n := n.(*ir.SendStmt)
-		e.discard(n.Chan)
-		e.assignHeap(n.Value, "send", n)
-
-	case ir.OAS:
-		n := n.(*ir.AssignStmt)
-		e.assignList([]ir.Node{n.X}, []ir.Node{n.Y}, "assign", n)
-	case ir.OASOP:
-		n := n.(*ir.AssignOpStmt)
-		// TODO(mdempsky): Worry about OLSH/ORSH?
-		e.assignList([]ir.Node{n.X}, []ir.Node{n.Y}, "assign", n)
-	case ir.OAS2:
-		n := n.(*ir.AssignListStmt)
-		e.assignList(n.Lhs, n.Rhs, "assign-pair", n)
-
-	case ir.OAS2DOTTYPE: // v, ok = x.(type)
-		n := n.(*ir.AssignListStmt)
-		e.assignList(n.Lhs, n.Rhs, "assign-pair-dot-type", n)
-	case ir.OAS2MAPR: // v, ok = m[k]
-		n := n.(*ir.AssignListStmt)
-		e.assignList(n.Lhs, n.Rhs, "assign-pair-mapr", n)
-	case ir.OAS2RECV, ir.OSELRECV2: // v, ok = <-ch
-		n := n.(*ir.AssignListStmt)
-		e.assignList(n.Lhs, n.Rhs, "assign-pair-receive", n)
-
-	case ir.OAS2FUNC:
-		n := n.(*ir.AssignListStmt)
-		e.stmts(n.Rhs[0].Init())
-		ks := e.addrs(n.Lhs)
-		e.call(ks, n.Rhs[0], nil)
-		e.reassigned(ks, n)
-	case ir.ORETURN:
-		n := n.(*ir.ReturnStmt)
-		results := e.curfn.Type().Results().FieldSlice()
-		dsts := make([]ir.Node, len(results))
-		for i, res := range results {
-			dsts[i] = res.Nname.(*ir.Name)
-		}
-		e.assignList(dsts, n.Results, "return", n)
-	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER, ir.OCLOSE, ir.OCOPY, ir.ODELETE, ir.OPANIC, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
-		e.call(nil, n, nil)
-	case ir.OGO, ir.ODEFER:
-		n := n.(*ir.GoDeferStmt)
-		e.stmts(n.Call.Init())
-		e.call(nil, n.Call, n)
-
-	case ir.OTAILCALL:
-		// TODO(mdempsky): Treat like a normal call? esc.go used to just ignore it.
-	}
-}
-
-func (e *escape) stmts(l ir.Nodes) {
-	for _, n := range l {
-		e.stmt(n)
-	}
-}
-
-// block is like stmts, but preserves loopDepth.
-func (e *escape) block(l ir.Nodes) {
-	old := e.loopDepth
-	e.stmts(l)
-	e.loopDepth = old
-}
-
-// expr models evaluating an expression n and flowing the result into
-// hole k.
-func (e *escape) expr(k hole, n ir.Node) {
-	if n == nil {
-		return
-	}
-	e.stmts(n.Init())
-	e.exprSkipInit(k, n)
-}
-
-func (e *escape) exprSkipInit(k hole, n ir.Node) {
-	if n == nil {
-		return
-	}
-
-	lno := ir.SetPos(n)
-	defer func() {
-		base.Pos = lno
-	}()
-
-	uintptrEscapesHack := k.uintptrEscapesHack
-	k.uintptrEscapesHack = false
-
-	if uintptrEscapesHack && n.Op() == ir.OCONVNOP && n.(*ir.ConvExpr).X.Type().IsUnsafePtr() {
-		// nop
-	} else if k.derefs >= 0 && !n.Type().HasPointers() {
-		k.dst = &e.blankLoc
-	}
-
-	switch n.Op() {
-	default:
-		base.Fatalf("unexpected expr: %s %v", n.Op().String(), n)
-
-	case ir.OLITERAL, ir.ONIL, ir.OGETG, ir.OTYPE, ir.OMETHEXPR, ir.OLINKSYMOFFSET:
-		// nop
-
-	case ir.ONAME:
-		n := n.(*ir.Name)
-		if n.Class == ir.PFUNC || n.Class == ir.PEXTERN {
-			return
-		}
-		if n.IsClosureVar() && n.Defn == nil {
-			return // ".this" from method value wrapper
-		}
-		e.flow(k, e.oldLoc(n))
-
-	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT:
-		n := n.(*ir.UnaryExpr)
-		e.discard(n.X)
-	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.ODIV, ir.OMOD, ir.OLSH, ir.ORSH, ir.OAND, ir.OANDNOT, ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
-		n := n.(*ir.BinaryExpr)
-		e.discard(n.X)
-		e.discard(n.Y)
-	case ir.OANDAND, ir.OOROR:
-		n := n.(*ir.LogicalExpr)
-		e.discard(n.X)
-		e.discard(n.Y)
-	case ir.OADDR:
-		n := n.(*ir.AddrExpr)
-		e.expr(k.addr(n, "address-of"), n.X) // "address-of"
-	case ir.ODEREF:
-		n := n.(*ir.StarExpr)
-		e.expr(k.deref(n, "indirection"), n.X) // "indirection"
-	case ir.ODOT, ir.ODOTMETH, ir.ODOTINTER:
-		n := n.(*ir.SelectorExpr)
-		e.expr(k.note(n, "dot"), n.X)
-	case ir.ODOTPTR:
-		n := n.(*ir.SelectorExpr)
-		e.expr(k.deref(n, "dot of pointer"), n.X) // "dot of pointer"
-	case ir.ODOTTYPE, ir.ODOTTYPE2:
-		n := n.(*ir.TypeAssertExpr)
-		e.expr(k.dotType(n.Type(), n, "dot"), n.X)
-	case ir.OINDEX:
-		n := n.(*ir.IndexExpr)
-		if n.X.Type().IsArray() {
-			e.expr(k.note(n, "fixed-array-index-of"), n.X)
-		} else {
-			// TODO(mdempsky): Fix why reason text.
-			e.expr(k.deref(n, "dot of pointer"), n.X)
-		}
-		e.discard(n.Index)
-	case ir.OINDEXMAP:
-		n := n.(*ir.IndexExpr)
-		e.discard(n.X)
-		e.discard(n.Index)
-	case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR, ir.OSLICESTR:
-		n := n.(*ir.SliceExpr)
-		e.expr(k.note(n, "slice"), n.X)
-		e.discard(n.Low)
-		e.discard(n.High)
-		e.discard(n.Max)
-
-	case ir.OCONV, ir.OCONVNOP:
-		n := n.(*ir.ConvExpr)
-		if ir.ShouldCheckPtr(e.curfn, 2) && n.Type().IsUnsafePtr() && n.X.Type().IsPtr() {
-			// When -d=checkptr=2 is enabled, treat
-			// conversions to unsafe.Pointer as an
-			// escaping operation. This allows better
-			// runtime instrumentation, since we can more
-			// easily detect object boundaries on the heap
-			// than the stack.
-			e.assignHeap(n.X, "conversion to unsafe.Pointer", n)
-		} else if n.Type().IsUnsafePtr() && n.X.Type().IsUintptr() {
-			e.unsafeValue(k, n.X)
-		} else {
-			e.expr(k, n.X)
-		}
-	case ir.OCONVIFACE:
-		n := n.(*ir.ConvExpr)
-		if !n.X.Type().IsInterface() && !types.IsDirectIface(n.X.Type()) {
-			k = e.spill(k, n)
-		}
-		e.expr(k.note(n, "interface-converted"), n.X)
-	case ir.OSLICE2ARRPTR:
-		// the slice pointer flows directly to the result
-		n := n.(*ir.ConvExpr)
-		e.expr(k, n.X)
-	case ir.ORECV:
-		n := n.(*ir.UnaryExpr)
-		e.discard(n.X)
-
-	case ir.OCALLMETH, ir.OCALLFUNC, ir.OCALLINTER, ir.OLEN, ir.OCAP, ir.OCOMPLEX, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.OCOPY, ir.OUNSAFEADD, ir.OUNSAFESLICE:
-		e.call([]hole{k}, n, nil)
-
-	case ir.ONEW:
-		n := n.(*ir.UnaryExpr)
-		e.spill(k, n)
-
-	case ir.OMAKESLICE:
-		n := n.(*ir.MakeExpr)
-		e.spill(k, n)
-		e.discard(n.Len)
-		e.discard(n.Cap)
-	case ir.OMAKECHAN:
-		n := n.(*ir.MakeExpr)
-		e.discard(n.Len)
-	case ir.OMAKEMAP:
-		n := n.(*ir.MakeExpr)
-		e.spill(k, n)
-		e.discard(n.Len)
-
-	case ir.ORECOVER:
-		// nop
-
-	case ir.OCALLPART:
-		// Flow the receiver argument to both the closure and
-		// to the receiver parameter.
-
-		n := n.(*ir.SelectorExpr)
-		closureK := e.spill(k, n)
-
-		m := n.Selection
-
-		// We don't know how the method value will be called
-		// later, so conservatively assume the result
-		// parameters all flow to the heap.
-		//
-		// TODO(mdempsky): Change ks into a callback, so that
-		// we don't have to create this slice?
-		var ks []hole
-		for i := m.Type.NumResults(); i > 0; i-- {
-			ks = append(ks, e.heapHole())
-		}
-		name, _ := m.Nname.(*ir.Name)
-		paramK := e.tagHole(ks, name, m.Type.Recv())
-
-		e.expr(e.teeHole(paramK, closureK), n.X)
-
-	case ir.OPTRLIT:
-		n := n.(*ir.AddrExpr)
-		e.expr(e.spill(k, n), n.X)
-
-	case ir.OARRAYLIT:
-		n := n.(*ir.CompLitExpr)
-		for _, elt := range n.List {
-			if elt.Op() == ir.OKEY {
-				elt = elt.(*ir.KeyExpr).Value
-			}
-			e.expr(k.note(n, "array literal element"), elt)
-		}
-
-	case ir.OSLICELIT:
-		n := n.(*ir.CompLitExpr)
-		k = e.spill(k, n)
-		k.uintptrEscapesHack = uintptrEscapesHack // for ...uintptr parameters
-
-		for _, elt := range n.List {
-			if elt.Op() == ir.OKEY {
-				elt = elt.(*ir.KeyExpr).Value
-			}
-			e.expr(k.note(n, "slice-literal-element"), elt)
-		}
-
-	case ir.OSTRUCTLIT:
-		n := n.(*ir.CompLitExpr)
-		for _, elt := range n.List {
-			e.expr(k.note(n, "struct literal element"), elt.(*ir.StructKeyExpr).Value)
-		}
-
-	case ir.OMAPLIT:
-		n := n.(*ir.CompLitExpr)
-		e.spill(k, n)
-
-		// Map keys and values are always stored in the heap.
-		for _, elt := range n.List {
-			elt := elt.(*ir.KeyExpr)
-			e.assignHeap(elt.Key, "map literal key", n)
-			e.assignHeap(elt.Value, "map literal value", n)
-		}
-
-	case ir.OCLOSURE:
-		n := n.(*ir.ClosureExpr)
-		k = e.spill(k, n)
-		e.closures = append(e.closures, closure{k, n})
-
-		if fn := n.Func; fn.IsHiddenClosure() {
-			for _, cv := range fn.ClosureVars {
-				if loc := e.oldLoc(cv); !loc.captured {
-					loc.captured = true
-
-					// Ignore reassignments to the variable in straightline code
-					// preceding the first capture by a closure.
-					if loc.loopDepth == e.loopDepth {
-						loc.reassigned = false
-					}
-				}
-			}
-
-			for _, n := range fn.Dcl {
-				// Add locations for local variables of the
-				// closure, if needed, in case we're not including
-				// the closure func in the batch for escape
-				// analysis (happens for escape analysis called
-				// from reflectdata.methodWrapper)
-				if n.Op() == ir.ONAME && n.Opt == nil {
-					e.with(fn).newLoc(n, false)
-				}
-			}
-			e.walkFunc(fn)
-		}
-
-	case ir.ORUNES2STR, ir.OBYTES2STR, ir.OSTR2RUNES, ir.OSTR2BYTES, ir.ORUNESTR:
-		n := n.(*ir.ConvExpr)
-		e.spill(k, n)
-		e.discard(n.X)
-
-	case ir.OADDSTR:
-		n := n.(*ir.AddStringExpr)
-		e.spill(k, n)
-
-		// Arguments of OADDSTR never escape;
-		// runtime.concatstrings makes sure of that.
-		e.discards(n.List)
-	}
-}
-
-// unsafeValue evaluates a uintptr-typed arithmetic expression looking
-// for conversions from an unsafe.Pointer.
-func (e *escape) unsafeValue(k hole, n ir.Node) {
-	if n.Type().Kind() != types.TUINTPTR {
-		base.Fatalf("unexpected type %v for %v", n.Type(), n)
-	}
-	if k.addrtaken {
-		base.Fatalf("unexpected addrtaken")
-	}
-
-	e.stmts(n.Init())
-
-	switch n.Op() {
-	case ir.OCONV, ir.OCONVNOP:
-		n := n.(*ir.ConvExpr)
-		if n.X.Type().IsUnsafePtr() {
-			e.expr(k, n.X)
-		} else {
-			e.discard(n.X)
-		}
-	case ir.ODOTPTR:
-		n := n.(*ir.SelectorExpr)
-		if ir.IsReflectHeaderDataField(n) {
-			e.expr(k.deref(n, "reflect.Header.Data"), n.X)
-		} else {
-			e.discard(n.X)
-		}
-	case ir.OPLUS, ir.ONEG, ir.OBITNOT:
-		n := n.(*ir.UnaryExpr)
-		e.unsafeValue(k, n.X)
-	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.ODIV, ir.OMOD, ir.OAND, ir.OANDNOT:
-		n := n.(*ir.BinaryExpr)
-		e.unsafeValue(k, n.X)
-		e.unsafeValue(k, n.Y)
-	case ir.OLSH, ir.ORSH:
-		n := n.(*ir.BinaryExpr)
-		e.unsafeValue(k, n.X)
-		// RHS need not be uintptr-typed (#32959) and can't meaningfully
-		// flow pointers anyway.
-		e.discard(n.Y)
-	default:
-		e.exprSkipInit(e.discardHole(), n)
-	}
-}
-
-// discard evaluates an expression n for side-effects, but discards
-// its value.
-func (e *escape) discard(n ir.Node) {
-	e.expr(e.discardHole(), n)
-}
-
-func (e *escape) discards(l ir.Nodes) {
-	for _, n := range l {
-		e.discard(n)
-	}
-}
-
-// addr evaluates an addressable expression n and returns a hole
-// that represents storing into the represented location.
-func (e *escape) addr(n ir.Node) hole {
-	if n == nil || ir.IsBlank(n) {
-		// Can happen in select case, range, maybe others.
-		return e.discardHole()
-	}
-
-	k := e.heapHole()
-
-	switch n.Op() {
-	default:
-		base.Fatalf("unexpected addr: %v", n)
-	case ir.ONAME:
-		n := n.(*ir.Name)
-		if n.Class == ir.PEXTERN {
-			break
-		}
-		k = e.oldLoc(n).asHole()
-	case ir.OLINKSYMOFFSET:
-		break
-	case ir.ODOT:
-		n := n.(*ir.SelectorExpr)
-		k = e.addr(n.X)
-	case ir.OINDEX:
-		n := n.(*ir.IndexExpr)
-		e.discard(n.Index)
-		if n.X.Type().IsArray() {
-			k = e.addr(n.X)
-		} else {
-			e.discard(n.X)
-		}
-	case ir.ODEREF, ir.ODOTPTR:
-		e.discard(n)
-	case ir.OINDEXMAP:
-		n := n.(*ir.IndexExpr)
-		e.discard(n.X)
-		e.assignHeap(n.Index, "key of map put", n)
-	}
-
-	return k
-}
-
-func (e *escape) addrs(l ir.Nodes) []hole {
-	var ks []hole
-	for _, n := range l {
-		ks = append(ks, e.addr(n))
-	}
-	return ks
-}
-
-// reassigned marks the locations associated with the given holes as
-// reassigned, unless the location represents a variable declared and
-// assigned exactly once by where.
-func (e *escape) reassigned(ks []hole, where ir.Node) {
-	if as, ok := where.(*ir.AssignStmt); ok && as.Op() == ir.OAS && as.Y == nil {
-		if dst, ok := as.X.(*ir.Name); ok && dst.Op() == ir.ONAME && dst.Defn == nil {
-			// Zero-value assignment for variable declared without an
-			// explicit initial value. Assume this is its initialization
-			// statement.
-			return
-		}
-	}
-
-	for _, k := range ks {
-		loc := k.dst
-		// Variables declared by range statements are assigned on every iteration.
-		if n, ok := loc.n.(*ir.Name); ok && n.Defn == where && where.Op() != ir.ORANGE {
-			continue
-		}
-		loc.reassigned = true
-	}
-}
-
-// assignList evaluates the assignment dsts... = srcs....
-func (e *escape) assignList(dsts, srcs []ir.Node, why string, where ir.Node) {
-	ks := e.addrs(dsts)
-	for i, k := range ks {
-		var src ir.Node
-		if i < len(srcs) {
-			src = srcs[i]
-		}
-
-		if dst := dsts[i]; dst != nil {
-			// Detect implicit conversion of uintptr to unsafe.Pointer when
-			// storing into reflect.{Slice,String}Header.
-			if dst.Op() == ir.ODOTPTR && ir.IsReflectHeaderDataField(dst) {
-				e.unsafeValue(e.heapHole().note(where, why), src)
-				continue
-			}
-
-			// Filter out some no-op assignments for escape analysis.
-			if src != nil && isSelfAssign(dst, src) {
-				if base.Flag.LowerM != 0 {
-					base.WarnfAt(where.Pos(), "%v ignoring self-assignment in %v", e.curfn, where)
-				}
-				k = e.discardHole()
-			}
-		}
-
-		e.expr(k.note(where, why), src)
-	}
-
-	e.reassigned(ks, where)
-}
-
-func (e *escape) assignHeap(src ir.Node, why string, where ir.Node) {
-	e.expr(e.heapHole().note(where, why), src)
-}
-
-// call evaluates a call expressions, including builtin calls. ks
-// should contain the holes representing where the function callee's
-// results flows; where is the OGO/ODEFER context of the call, if any.
-func (e *escape) call(ks []hole, call, where ir.Node) {
-	topLevelDefer := where != nil && where.Op() == ir.ODEFER && e.loopDepth == 1
-	if topLevelDefer {
-		// force stack allocation of defer record, unless
-		// open-coded defers are used (see ssa.go)
-		where.SetEsc(ir.EscNever)
-	}
-
-	argument := func(k hole, arg ir.Node) {
-		if topLevelDefer {
-			// Top level defers arguments don't escape to
-			// heap, but they do need to last until end of
-			// function.
-			k = e.later(k)
-		} else if where != nil {
-			k = e.heapHole()
-		}
-
-		e.expr(k.note(call, "call parameter"), arg)
-	}
-
-	switch call.Op() {
-	default:
-		ir.Dump("esc", call)
-		base.Fatalf("unexpected call op: %v", call.Op())
-
-	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
-		call := call.(*ir.CallExpr)
-		typecheck.FixVariadicCall(call)
-
-		// Pick out the function callee, if statically known.
-		var fn *ir.Name
-		switch call.Op() {
-		case ir.OCALLFUNC:
-			switch v := ir.StaticValue(call.X); {
-			case v.Op() == ir.ONAME && v.(*ir.Name).Class == ir.PFUNC:
-				fn = v.(*ir.Name)
-			case v.Op() == ir.OCLOSURE:
-				fn = v.(*ir.ClosureExpr).Func.Nname
-			}
-		case ir.OCALLMETH:
-			fn = ir.MethodExprName(call.X)
-		}
-
-		fntype := call.X.Type()
-		if fn != nil {
-			fntype = fn.Type()
-		}
-
-		if ks != nil && fn != nil && e.inMutualBatch(fn) {
-			for i, result := range fn.Type().Results().FieldSlice() {
-				e.expr(ks[i], ir.AsNode(result.Nname))
-			}
-		}
-
-		if r := fntype.Recv(); r != nil {
-			argument(e.tagHole(ks, fn, r), call.X.(*ir.SelectorExpr).X)
-		} else {
-			// Evaluate callee function expression.
-			argument(e.discardHole(), call.X)
-		}
-
-		args := call.Args
-		for i, param := range fntype.Params().FieldSlice() {
-			argument(e.tagHole(ks, fn, param), args[i])
-		}
-
-	case ir.OAPPEND:
-		call := call.(*ir.CallExpr)
-		args := call.Args
-
-		// Appendee slice may flow directly to the result, if
-		// it has enough capacity. Alternatively, a new heap
-		// slice might be allocated, and all slice elements
-		// might flow to heap.
-		appendeeK := ks[0]
-		if args[0].Type().Elem().HasPointers() {
-			appendeeK = e.teeHole(appendeeK, e.heapHole().deref(call, "appendee slice"))
-		}
-		argument(appendeeK, args[0])
-
-		if call.IsDDD {
-			appendedK := e.discardHole()
-			if args[1].Type().IsSlice() && args[1].Type().Elem().HasPointers() {
-				appendedK = e.heapHole().deref(call, "appended slice...")
-			}
-			argument(appendedK, args[1])
-		} else {
-			for _, arg := range args[1:] {
-				argument(e.heapHole(), arg)
-			}
-		}
-
-	case ir.OCOPY:
-		call := call.(*ir.BinaryExpr)
-		argument(e.discardHole(), call.X)
-
-		copiedK := e.discardHole()
-		if call.Y.Type().IsSlice() && call.Y.Type().Elem().HasPointers() {
-			copiedK = e.heapHole().deref(call, "copied slice")
-		}
-		argument(copiedK, call.Y)
-
-	case ir.OPANIC:
-		call := call.(*ir.UnaryExpr)
-		argument(e.heapHole(), call.X)
-
-	case ir.OCOMPLEX:
-		call := call.(*ir.BinaryExpr)
-		argument(e.discardHole(), call.X)
-		argument(e.discardHole(), call.Y)
-	case ir.ODELETE, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
-		call := call.(*ir.CallExpr)
-		for _, arg := range call.Args {
-			argument(e.discardHole(), arg)
-		}
-	case ir.OLEN, ir.OCAP, ir.OREAL, ir.OIMAG, ir.OCLOSE:
-		call := call.(*ir.UnaryExpr)
-		argument(e.discardHole(), call.X)
-
-	case ir.OUNSAFEADD, ir.OUNSAFESLICE:
-		call := call.(*ir.BinaryExpr)
-		argument(ks[0], call.X)
-		argument(e.discardHole(), call.Y)
-	}
-}
-
-// tagHole returns a hole for evaluating an argument passed to param.
-// ks should contain the holes representing where the function
-// callee's results flows. fn is the statically-known callee function,
-// if any.
-func (e *escape) tagHole(ks []hole, fn *ir.Name, param *types.Field) hole {
-	// If this is a dynamic call, we can't rely on param.Note.
-	if fn == nil {
-		return e.heapHole()
-	}
-
-	if e.inMutualBatch(fn) {
-		return e.addr(ir.AsNode(param.Nname))
-	}
-
-	// Call to previously tagged function.
-
-	if param.Note == UintptrEscapesNote {
-		k := e.heapHole()
-		k.uintptrEscapesHack = true
-		return k
-	}
-
-	var tagKs []hole
-
-	esc := parseLeaks(param.Note)
-	if x := esc.Heap(); x >= 0 {
-		tagKs = append(tagKs, e.heapHole().shift(x))
-	}
-
-	if ks != nil {
-		for i := 0; i < numEscResults; i++ {
-			if x := esc.Result(i); x >= 0 {
-				tagKs = append(tagKs, ks[i].shift(x))
-			}
-		}
-	}
-
-	return e.teeHole(tagKs...)
-}
-
-// inMutualBatch reports whether function fn is in the batch of
-// mutually recursive functions being analyzed. When this is true,
-// fn has not yet been analyzed, so its parameters and results
-// should be incorporated directly into the flow graph instead of
-// relying on its escape analysis tagging.
-func (e *escape) inMutualBatch(fn *ir.Name) bool {
-	if fn.Defn != nil && fn.Defn.Esc() < escFuncTagged {
-		if fn.Defn.Esc() == escFuncUnknown {
-			base.Fatalf("graph inconsistency: %v", fn)
-		}
-		return true
-	}
-	return false
-}
-
-// An hole represents a context for evaluation a Go
-// expression. E.g., when evaluating p in "x = **p", we'd have a hole
-// with dst==x and derefs==2.
-type hole struct {
-	dst    *location
-	derefs int // >= -1
-	notes  *note
-
-	// addrtaken indicates whether this context is taking the address of
-	// the expression, independent of whether the address will actually
-	// be stored into a variable.
-	addrtaken bool
-
-	// uintptrEscapesHack indicates this context is evaluating an
-	// argument for a //go:uintptrescapes function.
-	uintptrEscapesHack bool
-}
-
-type note struct {
-	next  *note
-	where ir.Node
-	why   string
-}
-
-func (k hole) note(where ir.Node, why string) hole {
-	if where == nil || why == "" {
-		base.Fatalf("note: missing where/why")
-	}
-	if base.Flag.LowerM >= 2 || logopt.Enabled() {
-		k.notes = &note{
-			next:  k.notes,
-			where: where,
-			why:   why,
-		}
-	}
-	return k
-}
-
-func (k hole) shift(delta int) hole {
-	k.derefs += delta
-	if k.derefs < -1 {
-		base.Fatalf("derefs underflow: %v", k.derefs)
-	}
-	k.addrtaken = delta < 0
-	return k
-}
-
-func (k hole) deref(where ir.Node, why string) hole { return k.shift(1).note(where, why) }
-func (k hole) addr(where ir.Node, why string) hole  { return k.shift(-1).note(where, why) }
-
-func (k hole) dotType(t *types.Type, where ir.Node, why string) hole {
-	if !t.IsInterface() && !types.IsDirectIface(t) {
-		k = k.shift(1)
-	}
-	return k.note(where, why)
-}
-
-// teeHole returns a new hole that flows into each hole of ks,
-// similar to the Unix tee(1) command.
-func (e *escape) teeHole(ks ...hole) hole {
-	if len(ks) == 0 {
-		return e.discardHole()
-	}
-	if len(ks) == 1 {
-		return ks[0]
-	}
-	// TODO(mdempsky): Optimize if there's only one non-discard hole?
-
-	// Given holes "l1 = _", "l2 = **_", "l3 = *_", ..., create a
-	// new temporary location ltmp, wire it into place, and return
-	// a hole for "ltmp = _".
-	loc := e.newLoc(nil, true)
-	for _, k := range ks {
-		// N.B., "p = &q" and "p = &tmp; tmp = q" are not
-		// semantically equivalent. To combine holes like "l1
-		// = _" and "l2 = &_", we'd need to wire them as "l1 =
-		// *ltmp" and "l2 = ltmp" and return "ltmp = &_"
-		// instead.
-		if k.derefs < 0 {
-			base.Fatalf("teeHole: negative derefs")
-		}
-
-		e.flow(k, loc)
-	}
-	return loc.asHole()
-}
-
-func (e *escape) dcl(n *ir.Name) hole {
-	if n.Curfn != e.curfn || n.IsClosureVar() {
-		base.Fatalf("bad declaration of %v", n)
-	}
-	loc := e.oldLoc(n)
-	loc.loopDepth = e.loopDepth
-	return loc.asHole()
-}
-
-// spill allocates a new location associated with expression n, flows
-// its address to k, and returns a hole that flows values to it. It's
-// intended for use with most expressions that allocate storage.
-func (e *escape) spill(k hole, n ir.Node) hole {
-	loc := e.newLoc(n, true)
-	e.flow(k.addr(n, "spill"), loc)
-	return loc.asHole()
-}
-
-// later returns a new hole that flows into k, but some time later.
-// Its main effect is to prevent immediate reuse of temporary
-// variables introduced during Order.
-func (e *escape) later(k hole) hole {
-	loc := e.newLoc(nil, false)
-	e.flow(k, loc)
-	return loc.asHole()
-}
-
-func (e *escape) newLoc(n ir.Node, transient bool) *location {
-	if e.curfn == nil {
-		base.Fatalf("e.curfn isn't set")
-	}
-	if n != nil && n.Type() != nil && n.Type().NotInHeap() {
-		base.ErrorfAt(n.Pos(), "%v is incomplete (or unallocatable); stack allocation disallowed", n.Type())
-	}
-
-	if n != nil && n.Op() == ir.ONAME {
-		n = n.(*ir.Name).Canonical()
-	}
-	loc := &location{
-		n:         n,
-		curfn:     e.curfn,
-		loopDepth: e.loopDepth,
-		transient: transient,
-	}
-	e.allLocs = append(e.allLocs, loc)
-	if n != nil {
-		if n.Op() == ir.ONAME {
-			n := n.(*ir.Name)
-			if n.Curfn != e.curfn {
-				base.Fatalf("curfn mismatch: %v != %v for %v", n.Curfn, e.curfn, n)
-			}
-
-			if n.Opt != nil {
-				base.Fatalf("%v already has a location", n)
-			}
-			n.Opt = loc
-		}
-	}
-	return loc
-}
-
-func (b *batch) oldLoc(n *ir.Name) *location {
-	if n.Canonical().Opt == nil {
-		base.Fatalf("%v has no location", n)
-	}
-	return n.Canonical().Opt.(*location)
-}
-
-func (l *location) asHole() hole {
-	return hole{dst: l}
-}
-
-func (b *batch) flow(k hole, src *location) {
-	if k.addrtaken {
-		src.addrtaken = true
-	}
-
-	dst := k.dst
-	if dst == &b.blankLoc {
-		return
-	}
-	if dst == src && k.derefs >= 0 { // dst = dst, dst = *dst, ...
-		return
-	}
-	if dst.escapes && k.derefs < 0 { // dst = &src
-		if base.Flag.LowerM >= 2 || logopt.Enabled() {
-			pos := base.FmtPos(src.n.Pos())
-			if base.Flag.LowerM >= 2 {
-				fmt.Printf("%s: %v escapes to heap:\n", pos, src.n)
-			}
-			explanation := b.explainFlow(pos, dst, src, k.derefs, k.notes, []*logopt.LoggedOpt{})
-			if logopt.Enabled() {
-				var e_curfn *ir.Func // TODO(mdempsky): Fix.
-				logopt.LogOpt(src.n.Pos(), "escapes", "escape", ir.FuncName(e_curfn), fmt.Sprintf("%v escapes to heap", src.n), explanation)
-			}
-
-		}
-		src.escapes = true
-		return
-	}
-
-	// TODO(mdempsky): Deduplicate edges?
-	dst.edges = append(dst.edges, edge{src: src, derefs: k.derefs, notes: k.notes})
-}
-
-func (b *batch) heapHole() hole    { return b.heapLoc.asHole() }
-func (b *batch) discardHole() hole { return b.blankLoc.asHole() }
-
-// walkAll computes the minimal dereferences between all pairs of
-// locations.
-func (b *batch) walkAll() {
-	// We use a work queue to keep track of locations that we need
-	// to visit, and repeatedly walk until we reach a fixed point.
-	//
-	// We walk once from each location (including the heap), and
-	// then re-enqueue each location on its transition from
-	// transient->!transient and !escapes->escapes, which can each
-	// happen at most once. So we take Θ(len(e.allLocs)) walks.
-
-	// LIFO queue, has enough room for e.allLocs and e.heapLoc.
-	todo := make([]*location, 0, len(b.allLocs)+1)
-	enqueue := func(loc *location) {
-		if !loc.queued {
-			todo = append(todo, loc)
-			loc.queued = true
-		}
-	}
-
-	for _, loc := range b.allLocs {
-		enqueue(loc)
-	}
-	enqueue(&b.heapLoc)
-
-	var walkgen uint32
-	for len(todo) > 0 {
-		root := todo[len(todo)-1]
-		todo = todo[:len(todo)-1]
-		root.queued = false
-
-		walkgen++
-		b.walkOne(root, walkgen, enqueue)
-	}
-}
-
-// walkOne computes the minimal number of dereferences from root to
-// all other locations.
-func (b *batch) walkOne(root *location, walkgen uint32, enqueue func(*location)) {
-	// The data flow graph has negative edges (from addressing
-	// operations), so we use the Bellman-Ford algorithm. However,
-	// we don't have to worry about infinite negative cycles since
-	// we bound intermediate dereference counts to 0.
-
-	root.walkgen = walkgen
-	root.derefs = 0
-	root.dst = nil
-
-	todo := []*location{root} // LIFO queue
-	for len(todo) > 0 {
-		l := todo[len(todo)-1]
-		todo = todo[:len(todo)-1]
-
-		derefs := l.derefs
-
-		// If l.derefs < 0, then l's address flows to root.
-		addressOf := derefs < 0
-		if addressOf {
-			// For a flow path like "root = &l; l = x",
-			// l's address flows to root, but x's does
-			// not. We recognize this by lower bounding
-			// derefs at 0.
-			derefs = 0
-
-			// If l's address flows to a non-transient
-			// location, then l can't be transiently
-			// allocated.
-			if !root.transient && l.transient {
-				l.transient = false
-				enqueue(l)
-			}
-		}
-
-		if b.outlives(root, l) {
-			// l's value flows to root. If l is a function
-			// parameter and root is the heap or a
-			// corresponding result parameter, then record
-			// that value flow for tagging the function
-			// later.
-			if l.isName(ir.PPARAM) {
-				if (logopt.Enabled() || base.Flag.LowerM >= 2) && !l.escapes {
-					if base.Flag.LowerM >= 2 {
-						fmt.Printf("%s: parameter %v leaks to %s with derefs=%d:\n", base.FmtPos(l.n.Pos()), l.n, b.explainLoc(root), derefs)
-					}
-					explanation := b.explainPath(root, l)
-					if logopt.Enabled() {
-						var e_curfn *ir.Func // TODO(mdempsky): Fix.
-						logopt.LogOpt(l.n.Pos(), "leak", "escape", ir.FuncName(e_curfn),
-							fmt.Sprintf("parameter %v leaks to %s with derefs=%d", l.n, b.explainLoc(root), derefs), explanation)
-					}
-				}
-				l.leakTo(root, derefs)
-			}
-
-			// If l's address flows somewhere that
-			// outlives it, then l needs to be heap
-			// allocated.
-			if addressOf && !l.escapes {
-				if logopt.Enabled() || base.Flag.LowerM >= 2 {
-					if base.Flag.LowerM >= 2 {
-						fmt.Printf("%s: %v escapes to heap:\n", base.FmtPos(l.n.Pos()), l.n)
-					}
-					explanation := b.explainPath(root, l)
-					if logopt.Enabled() {
-						var e_curfn *ir.Func // TODO(mdempsky): Fix.
-						logopt.LogOpt(l.n.Pos(), "escape", "escape", ir.FuncName(e_curfn), fmt.Sprintf("%v escapes to heap", l.n), explanation)
-					}
-				}
-				l.escapes = true
-				enqueue(l)
-				continue
-			}
-		}
-
-		for i, edge := range l.edges {
-			if edge.src.escapes {
-				continue
-			}
-			d := derefs + edge.derefs
-			if edge.src.walkgen != walkgen || edge.src.derefs > d {
-				edge.src.walkgen = walkgen
-				edge.src.derefs = d
-				edge.src.dst = l
-				edge.src.dstEdgeIdx = i
-				todo = append(todo, edge.src)
-			}
-		}
-	}
-}
-
-// explainPath prints an explanation of how src flows to the walk root.
-func (b *batch) explainPath(root, src *location) []*logopt.LoggedOpt {
-	visited := make(map[*location]bool)
-	pos := base.FmtPos(src.n.Pos())
-	var explanation []*logopt.LoggedOpt
-	for {
-		// Prevent infinite loop.
-		if visited[src] {
-			if base.Flag.LowerM >= 2 {
-				fmt.Printf("%s:   warning: truncated explanation due to assignment cycle; see golang.org/issue/35518\n", pos)
-			}
-			break
-		}
-		visited[src] = true
-		dst := src.dst
-		edge := &dst.edges[src.dstEdgeIdx]
-		if edge.src != src {
-			base.Fatalf("path inconsistency: %v != %v", edge.src, src)
-		}
-
-		explanation = b.explainFlow(pos, dst, src, edge.derefs, edge.notes, explanation)
-
-		if dst == root {
-			break
-		}
-		src = dst
-	}
-
-	return explanation
-}
-
-func (b *batch) explainFlow(pos string, dst, srcloc *location, derefs int, notes *note, explanation []*logopt.LoggedOpt) []*logopt.LoggedOpt {
-	ops := "&"
-	if derefs >= 0 {
-		ops = strings.Repeat("*", derefs)
-	}
-	print := base.Flag.LowerM >= 2
-
-	flow := fmt.Sprintf("   flow: %s = %s%v:", b.explainLoc(dst), ops, b.explainLoc(srcloc))
-	if print {
-		fmt.Printf("%s:%s\n", pos, flow)
-	}
-	if logopt.Enabled() {
-		var epos src.XPos
-		if notes != nil {
-			epos = notes.where.Pos()
-		} else if srcloc != nil && srcloc.n != nil {
-			epos = srcloc.n.Pos()
-		}
-		var e_curfn *ir.Func // TODO(mdempsky): Fix.
-		explanation = append(explanation, logopt.NewLoggedOpt(epos, "escflow", "escape", ir.FuncName(e_curfn), flow))
-	}
-
-	for note := notes; note != nil; note = note.next {
-		if print {
-			fmt.Printf("%s:     from %v (%v) at %s\n", pos, note.where, note.why, base.FmtPos(note.where.Pos()))
-		}
-		if logopt.Enabled() {
-			var e_curfn *ir.Func // TODO(mdempsky): Fix.
-			explanation = append(explanation, logopt.NewLoggedOpt(note.where.Pos(), "escflow", "escape", ir.FuncName(e_curfn),
-				fmt.Sprintf("     from %v (%v)", note.where, note.why)))
-		}
-	}
-	return explanation
-}
-
-func (b *batch) explainLoc(l *location) string {
-	if l == &b.heapLoc {
-		return "{heap}"
-	}
-	if l.n == nil {
-		// TODO(mdempsky): Omit entirely.
-		return "{temp}"
-	}
-	if l.n.Op() == ir.ONAME {
-		return fmt.Sprintf("%v", l.n)
-	}
-	return fmt.Sprintf("{storage for %v}", l.n)
-}
-
-// outlives reports whether values stored in l may survive beyond
-// other's lifetime if stack allocated.
-func (b *batch) outlives(l, other *location) bool {
-	// The heap outlives everything.
-	if l.escapes {
-		return true
-	}
-
-	// We don't know what callers do with returned values, so
-	// pessimistically we need to assume they flow to the heap and
-	// outlive everything too.
-	if l.isName(ir.PPARAMOUT) {
-		// Exception: Directly called closures can return
-		// locations allocated outside of them without forcing
-		// them to the heap. For example:
-		//
-		//    var u int  // okay to stack allocate
-		//    *(func() *int { return &u }()) = 42
-		if containsClosure(other.curfn, l.curfn) && l.curfn.ClosureCalled() {
-			return false
-		}
-
-		return true
-	}
-
-	// If l and other are within the same function, then l
-	// outlives other if it was declared outside other's loop
-	// scope. For example:
-	//
-	//    var l *int
-	//    for {
-	//        l = new(int)
-	//    }
-	if l.curfn == other.curfn && l.loopDepth < other.loopDepth {
-		return true
-	}
-
-	// If other is declared within a child closure of where l is
-	// declared, then l outlives it. For example:
-	//
-	//    var l *int
-	//    func() {
-	//        l = new(int)
-	//    }
-	if containsClosure(l.curfn, other.curfn) {
-		return true
-	}
-
-	return false
-}
-
-// containsClosure reports whether c is a closure contained within f.
-func containsClosure(f, c *ir.Func) bool {
-	// Common case.
-	if f == c {
-		return false
-	}
-
-	// Closures within function Foo are named like "Foo.funcN..."
-	// TODO(mdempsky): Better way to recognize this.
-	fn := f.Sym().Name
-	cn := c.Sym().Name
-	return len(cn) > len(fn) && cn[:len(fn)] == fn && cn[len(fn)] == '.'
-}
-
-// leak records that parameter l leaks to sink.
-func (l *location) leakTo(sink *location, derefs int) {
-	// If sink is a result parameter that doesn't escape (#44614)
-	// and we can fit return bits into the escape analysis tag,
-	// then record as a result leak.
-	if !sink.escapes && sink.isName(ir.PPARAMOUT) && sink.curfn == l.curfn {
-		ri := sink.resultIndex - 1
-		if ri < numEscResults {
-			// Leak to result parameter.
-			l.paramEsc.AddResult(ri, derefs)
-			return
-		}
-	}
-
-	// Otherwise, record as heap leak.
-	l.paramEsc.AddHeap(derefs)
-}
-
 func (b *batch) finish(fns []*ir.Func) {
 	// Record parameter tags for package export data.
 	for _, fn := range fns {
@@ -1678,6 +288,11 @@
 
 		// Update n.Esc based on escape analysis results.
 
+		// Omit escape diagnostics for go/defer wrappers, at least for now.
+		// Historically, we haven't printed them, and test cases don't expect them.
+		// TODO(mdempsky): Update tests to expect this.
+		goDeferWrapper := n.Op() == ir.OCLOSURE && n.(*ir.ClosureExpr).Func.Wrapper()
+
 		if loc.escapes {
 			if n.Op() == ir.ONAME {
 				if base.Flag.CompilingRuntime {
@@ -1687,7 +302,7 @@
 					base.WarnfAt(n.Pos(), "moved to heap: %v", n)
 				}
 			} else {
-				if base.Flag.LowerM != 0 {
+				if base.Flag.LowerM != 0 && !goDeferWrapper {
 					base.WarnfAt(n.Pos(), "%v escapes to heap", n)
 				}
 				if logopt.Enabled() {
@@ -1697,7 +312,7 @@
 			}
 			n.SetEsc(ir.EscHeap)
 		} else {
-			if base.Flag.LowerM != 0 && n.Op() != ir.ONAME {
+			if base.Flag.LowerM != 0 && n.Op() != ir.ONAME && !goDeferWrapper {
 				base.WarnfAt(n.Pos(), "%v does not escape", n)
 			}
 			n.SetEsc(ir.EscNone)
@@ -1706,7 +321,7 @@
 				case ir.OCLOSURE:
 					n := n.(*ir.ClosureExpr)
 					n.SetTransient(true)
-				case ir.OCALLPART:
+				case ir.OMETHVALUE:
 					n := n.(*ir.SelectorExpr)
 					n.SetTransient(true)
 				case ir.OSLICELIT:
@@ -1718,107 +333,19 @@
 	}
 }
 
-func (l *location) isName(c ir.Class) bool {
-	return l.n != nil && l.n.Op() == ir.ONAME && l.n.(*ir.Name).Class == c
-}
-
-const numEscResults = 7
-
-// An leaks represents a set of assignment flows from a parameter
-// to the heap or to any of its function's (first numEscResults)
-// result parameters.
-type leaks [1 + numEscResults]uint8
-
-// Empty reports whether l is an empty set (i.e., no assignment flows).
-func (l leaks) Empty() bool { return l == leaks{} }
-
-// Heap returns the minimum deref count of any assignment flow from l
-// to the heap. If no such flows exist, Heap returns -1.
-func (l leaks) Heap() int { return l.get(0) }
-
-// Result returns the minimum deref count of any assignment flow from
-// l to its function's i'th result parameter. If no such flows exist,
-// Result returns -1.
-func (l leaks) Result(i int) int { return l.get(1 + i) }
-
-// AddHeap adds an assignment flow from l to the heap.
-func (l *leaks) AddHeap(derefs int) { l.add(0, derefs) }
-
-// AddResult adds an assignment flow from l to its function's i'th
-// result parameter.
-func (l *leaks) AddResult(i, derefs int) { l.add(1+i, derefs) }
-
-func (l *leaks) setResult(i, derefs int) { l.set(1+i, derefs) }
-
-func (l leaks) get(i int) int { return int(l[i]) - 1 }
-
-func (l *leaks) add(i, derefs int) {
-	if old := l.get(i); old < 0 || derefs < old {
-		l.set(i, derefs)
-	}
-}
-
-func (l *leaks) set(i, derefs int) {
-	v := derefs + 1
-	if v < 0 {
-		base.Fatalf("invalid derefs count: %v", derefs)
-	}
-	if v > math.MaxUint8 {
-		v = math.MaxUint8
-	}
-
-	l[i] = uint8(v)
-}
-
-// Optimize removes result flow paths that are equal in length or
-// longer than the shortest heap flow path.
-func (l *leaks) Optimize() {
-	// If we have a path to the heap, then there's no use in
-	// keeping equal or longer paths elsewhere.
-	if x := l.Heap(); x >= 0 {
-		for i := 0; i < numEscResults; i++ {
-			if l.Result(i) >= x {
-				l.setResult(i, -1)
-			}
+// inMutualBatch reports whether function fn is in the batch of
+// mutually recursive functions being analyzed. When this is true,
+// fn has not yet been analyzed, so its parameters and results
+// should be incorporated directly into the flow graph instead of
+// relying on its escape analysis tagging.
+func (e *escape) inMutualBatch(fn *ir.Name) bool {
+	if fn.Defn != nil && fn.Defn.Esc() < escFuncTagged {
+		if fn.Defn.Esc() == escFuncUnknown {
+			base.Fatalf("graph inconsistency: %v", fn)
 		}
+		return true
 	}
-}
-
-var leakTagCache = map[leaks]string{}
-
-// Encode converts l into a binary string for export data.
-func (l leaks) Encode() string {
-	if l.Heap() == 0 {
-		// Space optimization: empty string encodes more
-		// efficiently in export data.
-		return ""
-	}
-	if s, ok := leakTagCache[l]; ok {
-		return s
-	}
-
-	n := len(l)
-	for n > 0 && l[n-1] == 0 {
-		n--
-	}
-	s := "esc:" + string(l[:n])
-	leakTagCache[l] = s
-	return s
-}
-
-// parseLeaks parses a binary string representing a leaks
-func parseLeaks(s string) leaks {
-	var l leaks
-	if !strings.HasPrefix(s, "esc:") {
-		l.AddHeap(0)
-		return l
-	}
-	copy(l[:], s[4:])
-	return l
-}
-
-func Funcs(all []ir.Node) {
-	ir.VisitFuncsBottomUp(all, Batch)
+	return false
 }
 
 const (
@@ -1836,220 +363,6 @@
 	nonlooping
 )
 
-func isSliceSelfAssign(dst, src ir.Node) bool {
-	// Detect the following special case.
-	//
-	//	func (b *Buffer) Foo() {
-	//		n, m := ...
-	//		b.buf = b.buf[n:m]
-	//	}
-	//
-	// This assignment is a no-op for escape analysis,
-	// it does not store any new pointers into b that were not already there.
-	// However, without this special case b will escape, because we assign to OIND/ODOTPTR.
-	// Here we assume that the statement will not contain calls,
-	// that is, that order will move any calls to init.
-	// Otherwise base ONAME value could change between the moments
-	// when we evaluate it for dst and for src.
-
-	// dst is ONAME dereference.
-	var dstX ir.Node
-	switch dst.Op() {
-	default:
-		return false
-	case ir.ODEREF:
-		dst := dst.(*ir.StarExpr)
-		dstX = dst.X
-	case ir.ODOTPTR:
-		dst := dst.(*ir.SelectorExpr)
-		dstX = dst.X
-	}
-	if dstX.Op() != ir.ONAME {
-		return false
-	}
-	// src is a slice operation.
-	switch src.Op() {
-	case ir.OSLICE, ir.OSLICE3, ir.OSLICESTR:
-		// OK.
-	case ir.OSLICEARR, ir.OSLICE3ARR:
-		// Since arrays are embedded into containing object,
-		// slice of non-pointer array will introduce a new pointer into b that was not already there
-		// (pointer to b itself). After such assignment, if b contents escape,
-		// b escapes as well. If we ignore such OSLICEARR, we will conclude
-		// that b does not escape when b contents do.
-		//
-		// Pointer to an array is OK since it's not stored inside b directly.
-		// For slicing an array (not pointer to array), there is an implicit OADDR.
-		// We check that to determine non-pointer array slicing.
-		src := src.(*ir.SliceExpr)
-		if src.X.Op() == ir.OADDR {
-			return false
-		}
-	default:
-		return false
-	}
-	// slice is applied to ONAME dereference.
-	var baseX ir.Node
-	switch base := src.(*ir.SliceExpr).X; base.Op() {
-	default:
-		return false
-	case ir.ODEREF:
-		base := base.(*ir.StarExpr)
-		baseX = base.X
-	case ir.ODOTPTR:
-		base := base.(*ir.SelectorExpr)
-		baseX = base.X
-	}
-	if baseX.Op() != ir.ONAME {
-		return false
-	}
-	// dst and src reference the same base ONAME.
-	return dstX.(*ir.Name) == baseX.(*ir.Name)
-}
-
-// isSelfAssign reports whether assignment from src to dst can
-// be ignored by the escape analysis as it's effectively a self-assignment.
-func isSelfAssign(dst, src ir.Node) bool {
-	if isSliceSelfAssign(dst, src) {
-		return true
-	}
-
-	// Detect trivial assignments that assign back to the same object.
-	//
-	// It covers these cases:
-	//	val.x = val.y
-	//	val.x[i] = val.y[j]
-	//	val.x1.x2 = val.x1.y2
-	//	... etc
-	//
-	// These assignments do not change assigned object lifetime.
-
-	if dst == nil || src == nil || dst.Op() != src.Op() {
-		return false
-	}
-
-	// The expression prefix must be both "safe" and identical.
-	switch dst.Op() {
-	case ir.ODOT, ir.ODOTPTR:
-		// Safe trailing accessors that are permitted to differ.
-		dst := dst.(*ir.SelectorExpr)
-		src := src.(*ir.SelectorExpr)
-		return ir.SameSafeExpr(dst.X, src.X)
-	case ir.OINDEX:
-		dst := dst.(*ir.IndexExpr)
-		src := src.(*ir.IndexExpr)
-		if mayAffectMemory(dst.Index) || mayAffectMemory(src.Index) {
-			return false
-		}
-		return ir.SameSafeExpr(dst.X, src.X)
-	default:
-		return false
-	}
-}
-
-// mayAffectMemory reports whether evaluation of n may affect the program's
-// memory state. If the expression can't affect memory state, then it can be
-// safely ignored by the escape analysis.
-func mayAffectMemory(n ir.Node) bool {
-	// We may want to use a list of "memory safe" ops instead of generally
-	// "side-effect free", which would include all calls and other ops that can
-	// allocate or change global state. For now, it's safer to start with the latter.
-	//
-	// We're ignoring things like division by zero, index out of range,
-	// and nil pointer dereference here.
-
-	// TODO(rsc): It seems like it should be possible to replace this with
-	// an ir.Any looking for any op that's not the ones in the case statement.
-	// But that produces changes in the compiled output detected by buildall.
-	switch n.Op() {
-	case ir.ONAME, ir.OLITERAL, ir.ONIL:
-		return false
-
-	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.OLSH, ir.ORSH, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OMOD:
-		n := n.(*ir.BinaryExpr)
-		return mayAffectMemory(n.X) || mayAffectMemory(n.Y)
-
-	case ir.OINDEX:
-		n := n.(*ir.IndexExpr)
-		return mayAffectMemory(n.X) || mayAffectMemory(n.Index)
-
-	case ir.OCONVNOP, ir.OCONV:
-		n := n.(*ir.ConvExpr)
-		return mayAffectMemory(n.X)
-
-	case ir.OLEN, ir.OCAP, ir.ONOT, ir.OBITNOT, ir.OPLUS, ir.ONEG, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
-		n := n.(*ir.UnaryExpr)
-		return mayAffectMemory(n.X)
-
-	case ir.ODOT, ir.ODOTPTR:
-		n := n.(*ir.SelectorExpr)
-		return mayAffectMemory(n.X)
-
-	case ir.ODEREF:
-		n := n.(*ir.StarExpr)
-		return mayAffectMemory(n.X)
-
-	default:
-		return true
-	}
-}
-
-// HeapAllocReason returns the reason the given Node must be heap
-// allocated, or the empty string if it doesn't.
-func HeapAllocReason(n ir.Node) string {
-	if n == nil || n.Type() == nil {
-		return ""
-	}
-
-	// Parameters are always passed via the stack.
-	if n.Op() == ir.ONAME {
-		n := n.(*ir.Name)
-		if n.Class == ir.PPARAM || n.Class == ir.PPARAMOUT {
-			return ""
-		}
-	}
-
-	if n.Type().Width > ir.MaxStackVarSize {
-		return "too large for stack"
-	}
-
-	if (n.Op() == ir.ONEW || n.Op() == ir.OPTRLIT) && n.Type().Elem().Width > ir.MaxImplicitStackVarSize {
-		return "too large for stack"
-	}
-
-	if n.Op() == ir.OCLOSURE && typecheck.ClosureType(n.(*ir.ClosureExpr)).Size() > ir.MaxImplicitStackVarSize {
-		return "too large for stack"
-	}
-	if n.Op() == ir.OCALLPART && typecheck.PartialCallType(n.(*ir.SelectorExpr)).Size() > ir.MaxImplicitStackVarSize {
-		return "too large for stack"
-	}
-
-	if n.Op() == ir.OMAKESLICE {
-		n := n.(*ir.MakeExpr)
-		r := n.Cap
-		if r == nil {
-			r = n.Len
-		}
-		if !ir.IsSmallIntConst(r) {
-			return "non-constant size"
-		}
-		if t := n.Type(); t.Elem().Width != 0 && ir.Int64Val(r) > ir.MaxImplicitStackVarSize/t.Elem().Width {
-			return "too large for stack"
-		}
-	}
-
-	return ""
-}
-
-// This special tag is applied to uintptr variables
-// that we believe may hold unsafe.Pointers for
-// calls into assembly functions.
-const UnsafeUintptrNote = "unsafe-uintptr"
-
-// This special tag is applied to uintptr parameters of functions
-// marked go:uintptrescapes.
-const UintptrEscapesNote = "uintptr-escapes"
-
 func (b *batch) paramTag(fn *ir.Func, narg int, f *types.Field) string {
 	name := func() string {
 		if f.Sym != nil {
@@ -2058,6 +371,11 @@
 		return fmt.Sprintf("arg#%d", narg)
 	}
 
+	// Only report diagnostics for user code;
+	// not for wrappers generated around them.
+	// TODO(mdempsky): Generalize this.
+	diagnose := base.Flag.LowerM != 0 && !(fn.Wrapper() || fn.Dupok())
+
 	if len(fn.Body) == 0 {
 		// Assume that uintptr arguments must be held live across the call.
 		// This is most important for syscall.Syscall.
@@ -2065,11 +383,13 @@
 		// This really doesn't have much to do with escape analysis per se,
 		// but we are reusing the ability to annotate an individual function
 		// argument and pass those annotations along to importing code.
+		fn.Pragma |= ir.UintptrKeepAlive
+
 		if f.Type.IsUintptr() {
-			if base.Flag.LowerM != 0 {
+			if diagnose {
 				base.WarnfAt(f.Pos, "assuming %v is unsafe uintptr", name())
 			}
-			return UnsafeUintptrNote
+			return ""
 		}
 
 		if !f.Type.HasPointers() { // don't bother tagging for scalars
@@ -2081,11 +401,11 @@
 		// External functions are assumed unsafe, unless
 		// //go:noescape is given before the declaration.
 		if fn.Pragma&ir.Noescape != 0 {
-			if base.Flag.LowerM != 0 && f.Sym != nil {
+			if diagnose && f.Sym != nil {
 				base.WarnfAt(f.Pos, "%v does not escape", name())
 			}
 		} else {
-			if base.Flag.LowerM != 0 && f.Sym != nil {
+			if diagnose && f.Sym != nil {
 				base.WarnfAt(f.Pos, "leaking param: %v", name())
 			}
 			esc.AddHeap(0)
@@ -2095,18 +415,20 @@
 	}
 
 	if fn.Pragma&ir.UintptrEscapes != 0 {
+		fn.Pragma |= ir.UintptrKeepAlive
+
 		if f.Type.IsUintptr() {
-			if base.Flag.LowerM != 0 {
+			if diagnose {
 				base.WarnfAt(f.Pos, "marking %v as escaping uintptr", name())
 			}
-			return UintptrEscapesNote
+			return ""
 		}
 		if f.IsDDD() && f.Type.Elem().IsUintptr() {
 			// final argument is ...uintptr.
-			if base.Flag.LowerM != 0 {
+			if diagnose {
 				base.WarnfAt(f.Pos, "marking %v as escaping ...uintptr", name())
 			}
-			return UintptrEscapesNote
+			return ""
 		}
 	}
 
@@ -2125,7 +447,7 @@
 	esc := loc.paramEsc
 	esc.Optimize()
 
-	if base.Flag.LowerM != 0 && !loc.escapes {
+	if diagnose && !loc.escapes {
 		if esc.Empty() {
 			base.WarnfAt(f.Pos, "%v does not escape", name())
 		}
diff --git a/src/cmd/compile/internal/escape/expr.go b/src/cmd/compile/internal/escape/expr.go
new file mode 100644
index 0000000..62afb5b
--- /dev/null
+++ b/src/cmd/compile/internal/escape/expr.go
@@ -0,0 +1,335 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/types"
+)
+
+// expr models evaluating an expression n and flowing the result into
+// hole k.
+func (e *escape) expr(k hole, n ir.Node) {
+	if n == nil {
+		return
+	}
+	e.stmts(n.Init())
+	e.exprSkipInit(k, n)
+}
+
+func (e *escape) exprSkipInit(k hole, n ir.Node) {
+	if n == nil {
+		return
+	}
+
+	lno := ir.SetPos(n)
+	defer func() {
+		base.Pos = lno
+	}()
+
+	if k.derefs >= 0 && !n.Type().HasPointers() {
+		k.dst = &e.blankLoc
+	}
+
+	switch n.Op() {
+	default:
+		base.Fatalf("unexpected expr: %s %v", n.Op().String(), n)
+
+	case ir.OLITERAL, ir.ONIL, ir.OGETG, ir.OGETCALLERPC, ir.OGETCALLERSP, ir.OTYPE, ir.OMETHEXPR, ir.OLINKSYMOFFSET:
+		// nop
+
+	case ir.ONAME:
+		n := n.(*ir.Name)
+		if n.Class == ir.PFUNC || n.Class == ir.PEXTERN {
+			return
+		}
+		e.flow(k, e.oldLoc(n))
+
+	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT:
+		n := n.(*ir.UnaryExpr)
+		e.discard(n.X)
+	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.ODIV, ir.OMOD, ir.OLSH, ir.ORSH, ir.OAND, ir.OANDNOT, ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
+		n := n.(*ir.BinaryExpr)
+		e.discard(n.X)
+		e.discard(n.Y)
+	case ir.OANDAND, ir.OOROR:
+		n := n.(*ir.LogicalExpr)
+		e.discard(n.X)
+		e.discard(n.Y)
+	case ir.OADDR:
+		n := n.(*ir.AddrExpr)
+		e.expr(k.addr(n, "address-of"), n.X) // "address-of"
+	case ir.ODEREF:
+		n := n.(*ir.StarExpr)
+		e.expr(k.deref(n, "indirection"), n.X) // "indirection"
+	case ir.ODOT, ir.ODOTMETH, ir.ODOTINTER:
+		n := n.(*ir.SelectorExpr)
+		e.expr(k.note(n, "dot"), n.X)
+	case ir.ODOTPTR:
+		n := n.(*ir.SelectorExpr)
+		e.expr(k.deref(n, "dot of pointer"), n.X) // "dot of pointer"
+	case ir.ODOTTYPE, ir.ODOTTYPE2:
+		n := n.(*ir.TypeAssertExpr)
+		e.expr(k.dotType(n.Type(), n, "dot"), n.X)
+	case ir.ODYNAMICDOTTYPE, ir.ODYNAMICDOTTYPE2:
+		n := n.(*ir.DynamicTypeAssertExpr)
+		e.expr(k.dotType(n.Type(), n, "dot"), n.X)
+		// n.T doesn't need to be tracked; it always points to read-only storage.
+	case ir.OINDEX:
+		n := n.(*ir.IndexExpr)
+		if n.X.Type().IsArray() {
+			e.expr(k.note(n, "fixed-array-index-of"), n.X)
+		} else {
+			// TODO(mdempsky): Fix why reason text.
+			e.expr(k.deref(n, "dot of pointer"), n.X)
+		}
+		e.discard(n.Index)
+	case ir.OINDEXMAP:
+		n := n.(*ir.IndexExpr)
+		e.discard(n.X)
+		e.discard(n.Index)
+	case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR, ir.OSLICESTR:
+		n := n.(*ir.SliceExpr)
+		e.expr(k.note(n, "slice"), n.X)
+		e.discard(n.Low)
+		e.discard(n.High)
+		e.discard(n.Max)
+
+	case ir.OCONV, ir.OCONVNOP:
+		n := n.(*ir.ConvExpr)
+		if ir.ShouldCheckPtr(e.curfn, 2) && n.Type().IsUnsafePtr() && n.X.Type().IsPtr() {
+			// When -d=checkptr=2 is enabled, treat
+			// conversions to unsafe.Pointer as an
+			// escaping operation. This allows better
+			// runtime instrumentation, since we can more
+			// easily detect object boundaries on the heap
+			// than the stack.
+			e.assignHeap(n.X, "conversion to unsafe.Pointer", n)
+		} else if n.Type().IsUnsafePtr() && n.X.Type().IsUintptr() {
+			e.unsafeValue(k, n.X)
+		} else {
+			e.expr(k, n.X)
+		}
+	case ir.OCONVIFACE, ir.OCONVIDATA:
+		n := n.(*ir.ConvExpr)
+		if !n.X.Type().IsInterface() && !types.IsDirectIface(n.X.Type()) {
+			k = e.spill(k, n)
+		}
+		e.expr(k.note(n, "interface-converted"), n.X)
+	case ir.OEFACE:
+		n := n.(*ir.BinaryExpr)
+		// Note: n.X is not needed because it can never point to memory that might escape.
+		e.expr(k, n.Y)
+	case ir.OIDATA, ir.OSPTR:
+		n := n.(*ir.UnaryExpr)
+		e.expr(k, n.X)
+	case ir.OSLICE2ARRPTR:
+		// the slice pointer flows directly to the result
+		n := n.(*ir.ConvExpr)
+		e.expr(k, n.X)
+	case ir.ORECV:
+		n := n.(*ir.UnaryExpr)
+		e.discard(n.X)
+
+	case ir.OCALLMETH, ir.OCALLFUNC, ir.OCALLINTER, ir.OINLCALL, ir.OLEN, ir.OCAP, ir.OCOMPLEX, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.OCOPY, ir.ORECOVER, ir.OUNSAFEADD, ir.OUNSAFESLICE:
+		e.call([]hole{k}, n)
+
+	case ir.ONEW:
+		n := n.(*ir.UnaryExpr)
+		e.spill(k, n)
+
+	case ir.OMAKESLICE:
+		n := n.(*ir.MakeExpr)
+		e.spill(k, n)
+		e.discard(n.Len)
+		e.discard(n.Cap)
+	case ir.OMAKECHAN:
+		n := n.(*ir.MakeExpr)
+		e.discard(n.Len)
+	case ir.OMAKEMAP:
+		n := n.(*ir.MakeExpr)
+		e.spill(k, n)
+		e.discard(n.Len)
+
+	case ir.OMETHVALUE:
+		// Flow the receiver argument to both the closure and
+		// to the receiver parameter.
+
+		n := n.(*ir.SelectorExpr)
+		closureK := e.spill(k, n)
+
+		m := n.Selection
+
+		// We don't know how the method value will be called
+		// later, so conservatively assume the result
+		// parameters all flow to the heap.
+		//
+		// TODO(mdempsky): Change ks into a callback, so that
+		// we don't have to create this slice?
+		var ks []hole
+		for i := m.Type.NumResults(); i > 0; i-- {
+			ks = append(ks, e.heapHole())
+		}
+		name, _ := m.Nname.(*ir.Name)
+		paramK := e.tagHole(ks, name, m.Type.Recv())
+
+		e.expr(e.teeHole(paramK, closureK), n.X)
+
+	case ir.OPTRLIT:
+		n := n.(*ir.AddrExpr)
+		e.expr(e.spill(k, n), n.X)
+
+	case ir.OARRAYLIT:
+		n := n.(*ir.CompLitExpr)
+		for _, elt := range n.List {
+			if elt.Op() == ir.OKEY {
+				elt = elt.(*ir.KeyExpr).Value
+			}
+			e.expr(k.note(n, "array literal element"), elt)
+		}
+
+	case ir.OSLICELIT:
+		n := n.(*ir.CompLitExpr)
+		k = e.spill(k, n)
+
+		for _, elt := range n.List {
+			if elt.Op() == ir.OKEY {
+				elt = elt.(*ir.KeyExpr).Value
+			}
+			e.expr(k.note(n, "slice-literal-element"), elt)
+		}
+
+	case ir.OSTRUCTLIT:
+		n := n.(*ir.CompLitExpr)
+		for _, elt := range n.List {
+			e.expr(k.note(n, "struct literal element"), elt.(*ir.StructKeyExpr).Value)
+		}
+
+	case ir.OMAPLIT:
+		n := n.(*ir.CompLitExpr)
+		e.spill(k, n)
+
+		// Map keys and values are always stored in the heap.
+		for _, elt := range n.List {
+			elt := elt.(*ir.KeyExpr)
+			e.assignHeap(elt.Key, "map literal key", n)
+			e.assignHeap(elt.Value, "map literal value", n)
+		}
+
+	case ir.OCLOSURE:
+		n := n.(*ir.ClosureExpr)
+		k = e.spill(k, n)
+		e.closures = append(e.closures, closure{k, n})
+
+		if fn := n.Func; fn.IsHiddenClosure() {
+			for _, cv := range fn.ClosureVars {
+				if loc := e.oldLoc(cv); !loc.captured {
+					loc.captured = true
+
+					// Ignore reassignments to the variable in straightline code
+					// preceding the first capture by a closure.
+					if loc.loopDepth == e.loopDepth {
+						loc.reassigned = false
+					}
+				}
+			}
+
+			for _, n := range fn.Dcl {
+				// Add locations for local variables of the
+				// closure, if needed, in case we're not including
+				// the closure func in the batch for escape
+				// analysis (happens for escape analysis called
+				// from reflectdata.methodWrapper)
+				if n.Op() == ir.ONAME && n.Opt == nil {
+					e.with(fn).newLoc(n, false)
+				}
+			}
+			e.walkFunc(fn)
+		}
+
+	case ir.ORUNES2STR, ir.OBYTES2STR, ir.OSTR2RUNES, ir.OSTR2BYTES, ir.ORUNESTR:
+		n := n.(*ir.ConvExpr)
+		e.spill(k, n)
+		e.discard(n.X)
+
+	case ir.OADDSTR:
+		n := n.(*ir.AddStringExpr)
+		e.spill(k, n)
+
+		// Arguments of OADDSTR never escape;
+		// runtime.concatstrings makes sure of that.
+		e.discards(n.List)
+
+	case ir.ODYNAMICTYPE:
+		// Nothing to do - argument is a *runtime._type (+ maybe a *runtime.itab) pointing to static data section
+	}
+}
+
+// unsafeValue evaluates a uintptr-typed arithmetic expression looking
+// for conversions from an unsafe.Pointer.
+func (e *escape) unsafeValue(k hole, n ir.Node) {
+	if n.Type().Kind() != types.TUINTPTR {
+		base.Fatalf("unexpected type %v for %v", n.Type(), n)
+	}
+	if k.addrtaken {
+		base.Fatalf("unexpected addrtaken")
+	}
+
+	e.stmts(n.Init())
+
+	switch n.Op() {
+	case ir.OCONV, ir.OCONVNOP:
+		n := n.(*ir.ConvExpr)
+		if n.X.Type().IsUnsafePtr() {
+			e.expr(k, n.X)
+		} else {
+			e.discard(n.X)
+		}
+	case ir.ODOTPTR:
+		n := n.(*ir.SelectorExpr)
+		if ir.IsReflectHeaderDataField(n) {
+			e.expr(k.deref(n, "reflect.Header.Data"), n.X)
+		} else {
+			e.discard(n.X)
+		}
+	case ir.OPLUS, ir.ONEG, ir.OBITNOT:
+		n := n.(*ir.UnaryExpr)
+		e.unsafeValue(k, n.X)
+	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.ODIV, ir.OMOD, ir.OAND, ir.OANDNOT:
+		n := n.(*ir.BinaryExpr)
+		e.unsafeValue(k, n.X)
+		e.unsafeValue(k, n.Y)
+	case ir.OLSH, ir.ORSH:
+		n := n.(*ir.BinaryExpr)
+		e.unsafeValue(k, n.X)
+		// RHS need not be uintptr-typed (#32959) and can't meaningfully
+		// flow pointers anyway.
+		e.discard(n.Y)
+	default:
+		e.exprSkipInit(e.discardHole(), n)
+	}
+}
+
+// discard evaluates an expression n for side-effects, but discards
+// its value.
+func (e *escape) discard(n ir.Node) {
+	e.expr(e.discardHole(), n)
+}
+
+func (e *escape) discards(l ir.Nodes) {
+	for _, n := range l {
+		e.discard(n)
+	}
+}
+
+// spill allocates a new location associated with expression n, flows
+// its address to k, and returns a hole that flows values to it. It's
+// intended for use with most expressions that allocate storage.
+func (e *escape) spill(k hole, n ir.Node) hole {
+	loc := e.newLoc(n, true)
+	e.flow(k.addr(n, "spill"), loc)
+	return loc.asHole()
+}
diff --git a/src/cmd/compile/internal/escape/graph.go b/src/cmd/compile/internal/escape/graph.go
new file mode 100644
index 0000000..d3ae1da
--- /dev/null
+++ b/src/cmd/compile/internal/escape/graph.go
@@ -0,0 +1,324 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/logopt"
+	"cmd/compile/internal/types"
+	"fmt"
+)
+
+// Below we implement the methods for walking the AST and recording
+// data flow edges. Note that because a sub-expression might have
+// side-effects, it's important to always visit the entire AST.
+//
+// For example, write either:
+//
+//     if x {
+//         e.discard(n.Left)
+//     } else {
+//         e.value(k, n.Left)
+//     }
+//
+// or
+//
+//     if x {
+//         k = e.discardHole()
+//     }
+//     e.value(k, n.Left)
+//
+// Do NOT write:
+//
+//    // BAD: possibly loses side-effects within n.Left
+//    if !x {
+//        e.value(k, n.Left)
+//    }
+
+// An location represents an abstract location that stores a Go
+// variable.
+type location struct {
+	n         ir.Node  // represented variable or expression, if any
+	curfn     *ir.Func // enclosing function
+	edges     []edge   // incoming edges
+	loopDepth int      // loopDepth at declaration
+
+	// resultIndex records the tuple index (starting at 1) for
+	// PPARAMOUT variables within their function's result type.
+	// For non-PPARAMOUT variables it's 0.
+	resultIndex int
+
+	// derefs and walkgen are used during walkOne to track the
+	// minimal dereferences from the walk root.
+	derefs  int // >= -1
+	walkgen uint32
+
+	// dst and dstEdgeindex track the next immediate assignment
+	// destination location during walkone, along with the index
+	// of the edge pointing back to this location.
+	dst        *location
+	dstEdgeIdx int
+
+	// queued is used by walkAll to track whether this location is
+	// in the walk queue.
+	queued bool
+
+	// escapes reports whether the represented variable's address
+	// escapes; that is, whether the variable must be heap
+	// allocated.
+	escapes bool
+
+	// transient reports whether the represented expression's
+	// address does not outlive the statement; that is, whether
+	// its storage can be immediately reused.
+	transient bool
+
+	// paramEsc records the represented parameter's leak set.
+	paramEsc leaks
+
+	captured   bool // has a closure captured this variable?
+	reassigned bool // has this variable been reassigned?
+	addrtaken  bool // has this variable's address been taken?
+}
+
+// An edge represents an assignment edge between two Go variables.
+type edge struct {
+	src    *location
+	derefs int // >= -1
+	notes  *note
+}
+
+func (l *location) asHole() hole {
+	return hole{dst: l}
+}
+
+// leak records that parameter l leaks to sink.
+func (l *location) leakTo(sink *location, derefs int) {
+	// If sink is a result parameter that doesn't escape (#44614)
+	// and we can fit return bits into the escape analysis tag,
+	// then record as a result leak.
+	if !sink.escapes && sink.isName(ir.PPARAMOUT) && sink.curfn == l.curfn {
+		ri := sink.resultIndex - 1
+		if ri < numEscResults {
+			// Leak to result parameter.
+			l.paramEsc.AddResult(ri, derefs)
+			return
+		}
+	}
+
+	// Otherwise, record as heap leak.
+	l.paramEsc.AddHeap(derefs)
+}
+
+func (l *location) isName(c ir.Class) bool {
+	return l.n != nil && l.n.Op() == ir.ONAME && l.n.(*ir.Name).Class == c
+}
+
+// An hole represents a context for evaluation a Go
+// expression. E.g., when evaluating p in "x = **p", we'd have a hole
+// with dst==x and derefs==2.
+type hole struct {
+	dst    *location
+	derefs int // >= -1
+	notes  *note
+
+	// addrtaken indicates whether this context is taking the address of
+	// the expression, independent of whether the address will actually
+	// be stored into a variable.
+	addrtaken bool
+}
+
+type note struct {
+	next  *note
+	where ir.Node
+	why   string
+}
+
+func (k hole) note(where ir.Node, why string) hole {
+	if where == nil || why == "" {
+		base.Fatalf("note: missing where/why")
+	}
+	if base.Flag.LowerM >= 2 || logopt.Enabled() {
+		k.notes = &note{
+			next:  k.notes,
+			where: where,
+			why:   why,
+		}
+	}
+	return k
+}
+
+func (k hole) shift(delta int) hole {
+	k.derefs += delta
+	if k.derefs < -1 {
+		base.Fatalf("derefs underflow: %v", k.derefs)
+	}
+	k.addrtaken = delta < 0
+	return k
+}
+
+func (k hole) deref(where ir.Node, why string) hole { return k.shift(1).note(where, why) }
+func (k hole) addr(where ir.Node, why string) hole  { return k.shift(-1).note(where, why) }
+
+func (k hole) dotType(t *types.Type, where ir.Node, why string) hole {
+	if !t.IsInterface() && !types.IsDirectIface(t) {
+		k = k.shift(1)
+	}
+	return k.note(where, why)
+}
+
+func (b *batch) flow(k hole, src *location) {
+	if k.addrtaken {
+		src.addrtaken = true
+	}
+
+	dst := k.dst
+	if dst == &b.blankLoc {
+		return
+	}
+	if dst == src && k.derefs >= 0 { // dst = dst, dst = *dst, ...
+		return
+	}
+	if dst.escapes && k.derefs < 0 { // dst = &src
+		if base.Flag.LowerM >= 2 || logopt.Enabled() {
+			pos := base.FmtPos(src.n.Pos())
+			if base.Flag.LowerM >= 2 {
+				fmt.Printf("%s: %v escapes to heap:\n", pos, src.n)
+			}
+			explanation := b.explainFlow(pos, dst, src, k.derefs, k.notes, []*logopt.LoggedOpt{})
+			if logopt.Enabled() {
+				var e_curfn *ir.Func // TODO(mdempsky): Fix.
+				logopt.LogOpt(src.n.Pos(), "escapes", "escape", ir.FuncName(e_curfn), fmt.Sprintf("%v escapes to heap", src.n), explanation)
+			}
+
+		}
+		src.escapes = true
+		return
+	}
+
+	// TODO(mdempsky): Deduplicate edges?
+	dst.edges = append(dst.edges, edge{src: src, derefs: k.derefs, notes: k.notes})
+}
+
+func (b *batch) heapHole() hole    { return b.heapLoc.asHole() }
+func (b *batch) discardHole() hole { return b.blankLoc.asHole() }
+
+func (b *batch) oldLoc(n *ir.Name) *location {
+	if n.Canonical().Opt == nil {
+		base.Fatalf("%v has no location", n)
+	}
+	return n.Canonical().Opt.(*location)
+}
+
+func (e *escape) newLoc(n ir.Node, transient bool) *location {
+	if e.curfn == nil {
+		base.Fatalf("e.curfn isn't set")
+	}
+	if n != nil && n.Type() != nil && n.Type().NotInHeap() {
+		base.ErrorfAt(n.Pos(), "%v is incomplete (or unallocatable); stack allocation disallowed", n.Type())
+	}
+
+	if n != nil && n.Op() == ir.ONAME {
+		if canon := n.(*ir.Name).Canonical(); n != canon {
+			base.Fatalf("newLoc on non-canonical %v (canonical is %v)", n, canon)
+		}
+	}
+	loc := &location{
+		n:         n,
+		curfn:     e.curfn,
+		loopDepth: e.loopDepth,
+		transient: transient,
+	}
+	e.allLocs = append(e.allLocs, loc)
+	if n != nil {
+		if n.Op() == ir.ONAME {
+			n := n.(*ir.Name)
+			if n.Class == ir.PPARAM && n.Curfn == nil {
+				// ok; hidden parameter
+			} else if n.Curfn != e.curfn {
+				base.Fatalf("curfn mismatch: %v != %v for %v", n.Curfn, e.curfn, n)
+			}
+
+			if n.Opt != nil {
+				base.Fatalf("%v already has a location", n)
+			}
+			n.Opt = loc
+		}
+	}
+	return loc
+}
+
+// teeHole returns a new hole that flows into each hole of ks,
+// similar to the Unix tee(1) command.
+func (e *escape) teeHole(ks ...hole) hole {
+	if len(ks) == 0 {
+		return e.discardHole()
+	}
+	if len(ks) == 1 {
+		return ks[0]
+	}
+	// TODO(mdempsky): Optimize if there's only one non-discard hole?
+
+	// Given holes "l1 = _", "l2 = **_", "l3 = *_", ..., create a
+	// new temporary location ltmp, wire it into place, and return
+	// a hole for "ltmp = _".
+	loc := e.newLoc(nil, true)
+	for _, k := range ks {
+		// N.B., "p = &q" and "p = &tmp; tmp = q" are not
+		// semantically equivalent. To combine holes like "l1
+		// = _" and "l2 = &_", we'd need to wire them as "l1 =
+		// *ltmp" and "l2 = ltmp" and return "ltmp = &_"
+		// instead.
+		if k.derefs < 0 {
+			base.Fatalf("teeHole: negative derefs")
+		}
+
+		e.flow(k, loc)
+	}
+	return loc.asHole()
+}
+
+// later returns a new hole that flows into k, but some time later.
+// Its main effect is to prevent immediate reuse of temporary
+// variables introduced during Order.
+func (e *escape) later(k hole) hole {
+	loc := e.newLoc(nil, false)
+	e.flow(k, loc)
+	return loc.asHole()
+}
+
+// Fmt is called from node printing to print information about escape analysis results.
+func Fmt(n ir.Node) string {
+	text := ""
+	switch n.Esc() {
+	case ir.EscUnknown:
+		break
+
+	case ir.EscHeap:
+		text = "esc(h)"
+
+	case ir.EscNone:
+		text = "esc(no)"
+
+	case ir.EscNever:
+		text = "esc(N)"
+
+	default:
+		text = fmt.Sprintf("esc(%d)", n.Esc())
+	}
+
+	if n.Op() == ir.ONAME {
+		n := n.(*ir.Name)
+		if loc, ok := n.Opt.(*location); ok && loc.loopDepth != 0 {
+			if text != "" {
+				text += " "
+			}
+			text += fmt.Sprintf("ld(%d)", loc.loopDepth)
+		}
+	}
+
+	return text
+}
diff --git a/src/cmd/compile/internal/escape/leaks.go b/src/cmd/compile/internal/escape/leaks.go
new file mode 100644
index 0000000..4c848a5
--- /dev/null
+++ b/src/cmd/compile/internal/escape/leaks.go
@@ -0,0 +1,106 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"math"
+	"strings"
+)
+
+const numEscResults = 7
+
+// An leaks represents a set of assignment flows from a parameter
+// to the heap or to any of its function's (first numEscResults)
+// result parameters.
+type leaks [1 + numEscResults]uint8
+
+// Empty reports whether l is an empty set (i.e., no assignment flows).
+func (l leaks) Empty() bool { return l == leaks{} }
+
+// Heap returns the minimum deref count of any assignment flow from l
+// to the heap. If no such flows exist, Heap returns -1.
+func (l leaks) Heap() int { return l.get(0) }
+
+// Result returns the minimum deref count of any assignment flow from
+// l to its function's i'th result parameter. If no such flows exist,
+// Result returns -1.
+func (l leaks) Result(i int) int { return l.get(1 + i) }
+
+// AddHeap adds an assignment flow from l to the heap.
+func (l *leaks) AddHeap(derefs int) { l.add(0, derefs) }
+
+// AddResult adds an assignment flow from l to its function's i'th
+// result parameter.
+func (l *leaks) AddResult(i, derefs int) { l.add(1+i, derefs) }
+
+func (l *leaks) setResult(i, derefs int) { l.set(1+i, derefs) }
+
+func (l leaks) get(i int) int { return int(l[i]) - 1 }
+
+func (l *leaks) add(i, derefs int) {
+	if old := l.get(i); old < 0 || derefs < old {
+		l.set(i, derefs)
+	}
+}
+
+func (l *leaks) set(i, derefs int) {
+	v := derefs + 1
+	if v < 0 {
+		base.Fatalf("invalid derefs count: %v", derefs)
+	}
+	if v > math.MaxUint8 {
+		v = math.MaxUint8
+	}
+
+	l[i] = uint8(v)
+}
+
+// Optimize removes result flow paths that are equal in length or
+// longer than the shortest heap flow path.
+func (l *leaks) Optimize() {
+	// If we have a path to the heap, then there's no use in
+	// keeping equal or longer paths elsewhere.
+	if x := l.Heap(); x >= 0 {
+		for i := 0; i < numEscResults; i++ {
+			if l.Result(i) >= x {
+				l.setResult(i, -1)
+			}
+		}
+	}
+}
+
+var leakTagCache = map[leaks]string{}
+
+// Encode converts l into a binary string for export data.
+func (l leaks) Encode() string {
+	if l.Heap() == 0 {
+		// Space optimization: empty string encodes more
+		// efficiently in export data.
+		return ""
+	}
+	if s, ok := leakTagCache[l]; ok {
+		return s
+	}
+
+	n := len(l)
+	for n > 0 && l[n-1] == 0 {
+		n--
+	}
+	s := "esc:" + string(l[:n])
+	leakTagCache[l] = s
+	return s
+}
+
+// parseLeaks parses a binary string representing a leaks
+func parseLeaks(s string) leaks {
+	var l leaks
+	if !strings.HasPrefix(s, "esc:") {
+		l.AddHeap(0)
+		return l
+	}
+	copy(l[:], s[4:])
+	return l
+}
diff --git a/src/cmd/compile/internal/escape/solve.go b/src/cmd/compile/internal/escape/solve.go
new file mode 100644
index 0000000..77d6b27
--- /dev/null
+++ b/src/cmd/compile/internal/escape/solve.go
@@ -0,0 +1,289 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/logopt"
+	"cmd/internal/src"
+	"fmt"
+	"strings"
+)
+
+// walkAll computes the minimal dereferences between all pairs of
+// locations.
+func (b *batch) walkAll() {
+	// We use a work queue to keep track of locations that we need
+	// to visit, and repeatedly walk until we reach a fixed point.
+	//
+	// We walk once from each location (including the heap), and
+	// then re-enqueue each location on its transition from
+	// transient->!transient and !escapes->escapes, which can each
+	// happen at most once. So we take Θ(len(e.allLocs)) walks.
+
+	// LIFO queue, has enough room for e.allLocs and e.heapLoc.
+	todo := make([]*location, 0, len(b.allLocs)+1)
+	enqueue := func(loc *location) {
+		if !loc.queued {
+			todo = append(todo, loc)
+			loc.queued = true
+		}
+	}
+
+	for _, loc := range b.allLocs {
+		enqueue(loc)
+	}
+	enqueue(&b.heapLoc)
+
+	var walkgen uint32
+	for len(todo) > 0 {
+		root := todo[len(todo)-1]
+		todo = todo[:len(todo)-1]
+		root.queued = false
+
+		walkgen++
+		b.walkOne(root, walkgen, enqueue)
+	}
+}
+
+// walkOne computes the minimal number of dereferences from root to
+// all other locations.
+func (b *batch) walkOne(root *location, walkgen uint32, enqueue func(*location)) {
+	// The data flow graph has negative edges (from addressing
+	// operations), so we use the Bellman-Ford algorithm. However,
+	// we don't have to worry about infinite negative cycles since
+	// we bound intermediate dereference counts to 0.
+
+	root.walkgen = walkgen
+	root.derefs = 0
+	root.dst = nil
+
+	todo := []*location{root} // LIFO queue
+	for len(todo) > 0 {
+		l := todo[len(todo)-1]
+		todo = todo[:len(todo)-1]
+
+		derefs := l.derefs
+
+		// If l.derefs < 0, then l's address flows to root.
+		addressOf := derefs < 0
+		if addressOf {
+			// For a flow path like "root = &l; l = x",
+			// l's address flows to root, but x's does
+			// not. We recognize this by lower bounding
+			// derefs at 0.
+			derefs = 0
+
+			// If l's address flows to a non-transient
+			// location, then l can't be transiently
+			// allocated.
+			if !root.transient && l.transient {
+				l.transient = false
+				enqueue(l)
+			}
+		}
+
+		if b.outlives(root, l) {
+			// l's value flows to root. If l is a function
+			// parameter and root is the heap or a
+			// corresponding result parameter, then record
+			// that value flow for tagging the function
+			// later.
+			if l.isName(ir.PPARAM) {
+				if (logopt.Enabled() || base.Flag.LowerM >= 2) && !l.escapes {
+					if base.Flag.LowerM >= 2 {
+						fmt.Printf("%s: parameter %v leaks to %s with derefs=%d:\n", base.FmtPos(l.n.Pos()), l.n, b.explainLoc(root), derefs)
+					}
+					explanation := b.explainPath(root, l)
+					if logopt.Enabled() {
+						var e_curfn *ir.Func // TODO(mdempsky): Fix.
+						logopt.LogOpt(l.n.Pos(), "leak", "escape", ir.FuncName(e_curfn),
+							fmt.Sprintf("parameter %v leaks to %s with derefs=%d", l.n, b.explainLoc(root), derefs), explanation)
+					}
+				}
+				l.leakTo(root, derefs)
+			}
+
+			// If l's address flows somewhere that
+			// outlives it, then l needs to be heap
+			// allocated.
+			if addressOf && !l.escapes {
+				if logopt.Enabled() || base.Flag.LowerM >= 2 {
+					if base.Flag.LowerM >= 2 {
+						fmt.Printf("%s: %v escapes to heap:\n", base.FmtPos(l.n.Pos()), l.n)
+					}
+					explanation := b.explainPath(root, l)
+					if logopt.Enabled() {
+						var e_curfn *ir.Func // TODO(mdempsky): Fix.
+						logopt.LogOpt(l.n.Pos(), "escape", "escape", ir.FuncName(e_curfn), fmt.Sprintf("%v escapes to heap", l.n), explanation)
+					}
+				}
+				l.escapes = true
+				enqueue(l)
+				continue
+			}
+		}
+
+		for i, edge := range l.edges {
+			if edge.src.escapes {
+				continue
+			}
+			d := derefs + edge.derefs
+			if edge.src.walkgen != walkgen || edge.src.derefs > d {
+				edge.src.walkgen = walkgen
+				edge.src.derefs = d
+				edge.src.dst = l
+				edge.src.dstEdgeIdx = i
+				todo = append(todo, edge.src)
+			}
+		}
+	}
+}
+
+// explainPath prints an explanation of how src flows to the walk root.
+func (b *batch) explainPath(root, src *location) []*logopt.LoggedOpt {
+	visited := make(map[*location]bool)
+	pos := base.FmtPos(src.n.Pos())
+	var explanation []*logopt.LoggedOpt
+	for {
+		// Prevent infinite loop.
+		if visited[src] {
+			if base.Flag.LowerM >= 2 {
+				fmt.Printf("%s:   warning: truncated explanation due to assignment cycle; see golang.org/issue/35518\n", pos)
+			}
+			break
+		}
+		visited[src] = true
+		dst := src.dst
+		edge := &dst.edges[src.dstEdgeIdx]
+		if edge.src != src {
+			base.Fatalf("path inconsistency: %v != %v", edge.src, src)
+		}
+
+		explanation = b.explainFlow(pos, dst, src, edge.derefs, edge.notes, explanation)
+
+		if dst == root {
+			break
+		}
+		src = dst
+	}
+
+	return explanation
+}
+
+func (b *batch) explainFlow(pos string, dst, srcloc *location, derefs int, notes *note, explanation []*logopt.LoggedOpt) []*logopt.LoggedOpt {
+	ops := "&"
+	if derefs >= 0 {
+		ops = strings.Repeat("*", derefs)
+	}
+	print := base.Flag.LowerM >= 2
+
+	flow := fmt.Sprintf("   flow: %s = %s%v:", b.explainLoc(dst), ops, b.explainLoc(srcloc))
+	if print {
+		fmt.Printf("%s:%s\n", pos, flow)
+	}
+	if logopt.Enabled() {
+		var epos src.XPos
+		if notes != nil {
+			epos = notes.where.Pos()
+		} else if srcloc != nil && srcloc.n != nil {
+			epos = srcloc.n.Pos()
+		}
+		var e_curfn *ir.Func // TODO(mdempsky): Fix.
+		explanation = append(explanation, logopt.NewLoggedOpt(epos, "escflow", "escape", ir.FuncName(e_curfn), flow))
+	}
+
+	for note := notes; note != nil; note = note.next {
+		if print {
+			fmt.Printf("%s:     from %v (%v) at %s\n", pos, note.where, note.why, base.FmtPos(note.where.Pos()))
+		}
+		if logopt.Enabled() {
+			var e_curfn *ir.Func // TODO(mdempsky): Fix.
+			explanation = append(explanation, logopt.NewLoggedOpt(note.where.Pos(), "escflow", "escape", ir.FuncName(e_curfn),
+				fmt.Sprintf("     from %v (%v)", note.where, note.why)))
+		}
+	}
+	return explanation
+}
+
+func (b *batch) explainLoc(l *location) string {
+	if l == &b.heapLoc {
+		return "{heap}"
+	}
+	if l.n == nil {
+		// TODO(mdempsky): Omit entirely.
+		return "{temp}"
+	}
+	if l.n.Op() == ir.ONAME {
+		return fmt.Sprintf("%v", l.n)
+	}
+	return fmt.Sprintf("{storage for %v}", l.n)
+}
+
+// outlives reports whether values stored in l may survive beyond
+// other's lifetime if stack allocated.
+func (b *batch) outlives(l, other *location) bool {
+	// The heap outlives everything.
+	if l.escapes {
+		return true
+	}
+
+	// We don't know what callers do with returned values, so
+	// pessimistically we need to assume they flow to the heap and
+	// outlive everything too.
+	if l.isName(ir.PPARAMOUT) {
+		// Exception: Directly called closures can return
+		// locations allocated outside of them without forcing
+		// them to the heap. For example:
+		//
+		//    var u int  // okay to stack allocate
+		//    *(func() *int { return &u }()) = 42
+		if containsClosure(other.curfn, l.curfn) && l.curfn.ClosureCalled() {
+			return false
+		}
+
+		return true
+	}
+
+	// If l and other are within the same function, then l
+	// outlives other if it was declared outside other's loop
+	// scope. For example:
+	//
+	//    var l *int
+	//    for {
+	//        l = new(int)
+	//    }
+	if l.curfn == other.curfn && l.loopDepth < other.loopDepth {
+		return true
+	}
+
+	// If other is declared within a child closure of where l is
+	// declared, then l outlives it. For example:
+	//
+	//    var l *int
+	//    func() {
+	//        l = new(int)
+	//    }
+	if containsClosure(l.curfn, other.curfn) {
+		return true
+	}
+
+	return false
+}
+
+// containsClosure reports whether c is a closure contained within f.
+func containsClosure(f, c *ir.Func) bool {
+	// Common case.
+	if f == c {
+		return false
+	}
+
+	// Closures within function Foo are named like "Foo.funcN..."
+	// TODO(mdempsky): Better way to recognize this.
+	fn := f.Sym().Name
+	cn := c.Sym().Name
+	return len(cn) > len(fn) && cn[:len(fn)] == fn && cn[len(fn)] == '.'
+}
diff --git a/src/cmd/compile/internal/escape/stmt.go b/src/cmd/compile/internal/escape/stmt.go
new file mode 100644
index 0000000..c71848b
--- /dev/null
+++ b/src/cmd/compile/internal/escape/stmt.go
@@ -0,0 +1,207 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"fmt"
+)
+
+// stmt evaluates a single Go statement.
+func (e *escape) stmt(n ir.Node) {
+	if n == nil {
+		return
+	}
+
+	lno := ir.SetPos(n)
+	defer func() {
+		base.Pos = lno
+	}()
+
+	if base.Flag.LowerM > 2 {
+		fmt.Printf("%v:[%d] %v stmt: %v\n", base.FmtPos(base.Pos), e.loopDepth, e.curfn, n)
+	}
+
+	e.stmts(n.Init())
+
+	switch n.Op() {
+	default:
+		base.Fatalf("unexpected stmt: %v", n)
+
+	case ir.ODCLCONST, ir.ODCLTYPE, ir.OFALL, ir.OINLMARK:
+		// nop
+
+	case ir.OBREAK, ir.OCONTINUE, ir.OGOTO:
+		// TODO(mdempsky): Handle dead code?
+
+	case ir.OBLOCK:
+		n := n.(*ir.BlockStmt)
+		e.stmts(n.List)
+
+	case ir.ODCL:
+		// Record loop depth at declaration.
+		n := n.(*ir.Decl)
+		if !ir.IsBlank(n.X) {
+			e.dcl(n.X)
+		}
+
+	case ir.OLABEL:
+		n := n.(*ir.LabelStmt)
+		switch e.labels[n.Label] {
+		case nonlooping:
+			if base.Flag.LowerM > 2 {
+				fmt.Printf("%v:%v non-looping label\n", base.FmtPos(base.Pos), n)
+			}
+		case looping:
+			if base.Flag.LowerM > 2 {
+				fmt.Printf("%v: %v looping label\n", base.FmtPos(base.Pos), n)
+			}
+			e.loopDepth++
+		default:
+			base.Fatalf("label missing tag")
+		}
+		delete(e.labels, n.Label)
+
+	case ir.OIF:
+		n := n.(*ir.IfStmt)
+		e.discard(n.Cond)
+		e.block(n.Body)
+		e.block(n.Else)
+
+	case ir.OFOR, ir.OFORUNTIL:
+		n := n.(*ir.ForStmt)
+		e.loopDepth++
+		e.discard(n.Cond)
+		e.stmt(n.Post)
+		e.block(n.Body)
+		e.loopDepth--
+
+	case ir.ORANGE:
+		// for Key, Value = range X { Body }
+		n := n.(*ir.RangeStmt)
+
+		// X is evaluated outside the loop.
+		tmp := e.newLoc(nil, false)
+		e.expr(tmp.asHole(), n.X)
+
+		e.loopDepth++
+		ks := e.addrs([]ir.Node{n.Key, n.Value})
+		if n.X.Type().IsArray() {
+			e.flow(ks[1].note(n, "range"), tmp)
+		} else {
+			e.flow(ks[1].deref(n, "range-deref"), tmp)
+		}
+		e.reassigned(ks, n)
+
+		e.block(n.Body)
+		e.loopDepth--
+
+	case ir.OSWITCH:
+		n := n.(*ir.SwitchStmt)
+
+		if guard, ok := n.Tag.(*ir.TypeSwitchGuard); ok {
+			var ks []hole
+			if guard.Tag != nil {
+				for _, cas := range n.Cases {
+					cv := cas.Var
+					k := e.dcl(cv) // type switch variables have no ODCL.
+					if cv.Type().HasPointers() {
+						ks = append(ks, k.dotType(cv.Type(), cas, "switch case"))
+					}
+				}
+			}
+			e.expr(e.teeHole(ks...), n.Tag.(*ir.TypeSwitchGuard).X)
+		} else {
+			e.discard(n.Tag)
+		}
+
+		for _, cas := range n.Cases {
+			e.discards(cas.List)
+			e.block(cas.Body)
+		}
+
+	case ir.OSELECT:
+		n := n.(*ir.SelectStmt)
+		for _, cas := range n.Cases {
+			e.stmt(cas.Comm)
+			e.block(cas.Body)
+		}
+	case ir.ORECV:
+		// TODO(mdempsky): Consider e.discard(n.Left).
+		n := n.(*ir.UnaryExpr)
+		e.exprSkipInit(e.discardHole(), n) // already visited n.Ninit
+	case ir.OSEND:
+		n := n.(*ir.SendStmt)
+		e.discard(n.Chan)
+		e.assignHeap(n.Value, "send", n)
+
+	case ir.OAS:
+		n := n.(*ir.AssignStmt)
+		e.assignList([]ir.Node{n.X}, []ir.Node{n.Y}, "assign", n)
+	case ir.OASOP:
+		n := n.(*ir.AssignOpStmt)
+		// TODO(mdempsky): Worry about OLSH/ORSH?
+		e.assignList([]ir.Node{n.X}, []ir.Node{n.Y}, "assign", n)
+	case ir.OAS2:
+		n := n.(*ir.AssignListStmt)
+		e.assignList(n.Lhs, n.Rhs, "assign-pair", n)
+
+	case ir.OAS2DOTTYPE: // v, ok = x.(type)
+		n := n.(*ir.AssignListStmt)
+		e.assignList(n.Lhs, n.Rhs, "assign-pair-dot-type", n)
+	case ir.OAS2MAPR: // v, ok = m[k]
+		n := n.(*ir.AssignListStmt)
+		e.assignList(n.Lhs, n.Rhs, "assign-pair-mapr", n)
+	case ir.OAS2RECV, ir.OSELRECV2: // v, ok = <-ch
+		n := n.(*ir.AssignListStmt)
+		e.assignList(n.Lhs, n.Rhs, "assign-pair-receive", n)
+
+	case ir.OAS2FUNC:
+		n := n.(*ir.AssignListStmt)
+		e.stmts(n.Rhs[0].Init())
+		ks := e.addrs(n.Lhs)
+		e.call(ks, n.Rhs[0])
+		e.reassigned(ks, n)
+	case ir.ORETURN:
+		n := n.(*ir.ReturnStmt)
+		results := e.curfn.Type().Results().FieldSlice()
+		dsts := make([]ir.Node, len(results))
+		for i, res := range results {
+			dsts[i] = res.Nname.(*ir.Name)
+		}
+		e.assignList(dsts, n.Results, "return", n)
+	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER, ir.OINLCALL, ir.OCLOSE, ir.OCOPY, ir.ODELETE, ir.OPANIC, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+		e.call(nil, n)
+	case ir.OGO, ir.ODEFER:
+		n := n.(*ir.GoDeferStmt)
+		e.goDeferStmt(n)
+
+	case ir.OTAILCALL:
+		// TODO(mdempsky): Treat like a normal call? esc.go used to just ignore it.
+	}
+}
+
+func (e *escape) stmts(l ir.Nodes) {
+	for _, n := range l {
+		e.stmt(n)
+	}
+}
+
+// block is like stmts, but preserves loopDepth.
+func (e *escape) block(l ir.Nodes) {
+	old := e.loopDepth
+	e.stmts(l)
+	e.loopDepth = old
+}
+
+func (e *escape) dcl(n *ir.Name) hole {
+	if n.Curfn != e.curfn || n.IsClosureVar() {
+		base.Fatalf("bad declaration of %v", n)
+	}
+	loc := e.oldLoc(n)
+	loc.loopDepth = e.loopDepth
+	return loc.asHole()
+}
diff --git a/src/cmd/compile/internal/escape/utils.go b/src/cmd/compile/internal/escape/utils.go
new file mode 100644
index 0000000..5f462ef
--- /dev/null
+++ b/src/cmd/compile/internal/escape/utils.go
@@ -0,0 +1,215 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package escape
+
+import (
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+)
+
+func isSliceSelfAssign(dst, src ir.Node) bool {
+	// Detect the following special case.
+	//
+	//	func (b *Buffer) Foo() {
+	//		n, m := ...
+	//		b.buf = b.buf[n:m]
+	//	}
+	//
+	// This assignment is a no-op for escape analysis,
+	// it does not store any new pointers into b that were not already there.
+	// However, without this special case b will escape, because we assign to OIND/ODOTPTR.
+	// Here we assume that the statement will not contain calls,
+	// that is, that order will move any calls to init.
+	// Otherwise base ONAME value could change between the moments
+	// when we evaluate it for dst and for src.
+
+	// dst is ONAME dereference.
+	var dstX ir.Node
+	switch dst.Op() {
+	default:
+		return false
+	case ir.ODEREF:
+		dst := dst.(*ir.StarExpr)
+		dstX = dst.X
+	case ir.ODOTPTR:
+		dst := dst.(*ir.SelectorExpr)
+		dstX = dst.X
+	}
+	if dstX.Op() != ir.ONAME {
+		return false
+	}
+	// src is a slice operation.
+	switch src.Op() {
+	case ir.OSLICE, ir.OSLICE3, ir.OSLICESTR:
+		// OK.
+	case ir.OSLICEARR, ir.OSLICE3ARR:
+		// Since arrays are embedded into containing object,
+		// slice of non-pointer array will introduce a new pointer into b that was not already there
+		// (pointer to b itself). After such assignment, if b contents escape,
+		// b escapes as well. If we ignore such OSLICEARR, we will conclude
+		// that b does not escape when b contents do.
+		//
+		// Pointer to an array is OK since it's not stored inside b directly.
+		// For slicing an array (not pointer to array), there is an implicit OADDR.
+		// We check that to determine non-pointer array slicing.
+		src := src.(*ir.SliceExpr)
+		if src.X.Op() == ir.OADDR {
+			return false
+		}
+	default:
+		return false
+	}
+	// slice is applied to ONAME dereference.
+	var baseX ir.Node
+	switch base := src.(*ir.SliceExpr).X; base.Op() {
+	default:
+		return false
+	case ir.ODEREF:
+		base := base.(*ir.StarExpr)
+		baseX = base.X
+	case ir.ODOTPTR:
+		base := base.(*ir.SelectorExpr)
+		baseX = base.X
+	}
+	if baseX.Op() != ir.ONAME {
+		return false
+	}
+	// dst and src reference the same base ONAME.
+	return dstX.(*ir.Name) == baseX.(*ir.Name)
+}
+
+// isSelfAssign reports whether assignment from src to dst can
+// be ignored by the escape analysis as it's effectively a self-assignment.
+func isSelfAssign(dst, src ir.Node) bool {
+	if isSliceSelfAssign(dst, src) {
+		return true
+	}
+
+	// Detect trivial assignments that assign back to the same object.
+	//
+	// It covers these cases:
+	//	val.x = val.y
+	//	val.x[i] = val.y[j]
+	//	val.x1.x2 = val.x1.y2
+	//	... etc
+	//
+	// These assignments do not change assigned object lifetime.
+
+	if dst == nil || src == nil || dst.Op() != src.Op() {
+		return false
+	}
+
+	// The expression prefix must be both "safe" and identical.
+	switch dst.Op() {
+	case ir.ODOT, ir.ODOTPTR:
+		// Safe trailing accessors that are permitted to differ.
+		dst := dst.(*ir.SelectorExpr)
+		src := src.(*ir.SelectorExpr)
+		return ir.SameSafeExpr(dst.X, src.X)
+	case ir.OINDEX:
+		dst := dst.(*ir.IndexExpr)
+		src := src.(*ir.IndexExpr)
+		if mayAffectMemory(dst.Index) || mayAffectMemory(src.Index) {
+			return false
+		}
+		return ir.SameSafeExpr(dst.X, src.X)
+	default:
+		return false
+	}
+}
+
+// mayAffectMemory reports whether evaluation of n may affect the program's
+// memory state. If the expression can't affect memory state, then it can be
+// safely ignored by the escape analysis.
+func mayAffectMemory(n ir.Node) bool {
+	// We may want to use a list of "memory safe" ops instead of generally
+	// "side-effect free", which would include all calls and other ops that can
+	// allocate or change global state. For now, it's safer to start with the latter.
+	//
+	// We're ignoring things like division by zero, index out of range,
+	// and nil pointer dereference here.
+
+	// TODO(rsc): It seems like it should be possible to replace this with
+	// an ir.Any looking for any op that's not the ones in the case statement.
+	// But that produces changes in the compiled output detected by buildall.
+	switch n.Op() {
+	case ir.ONAME, ir.OLITERAL, ir.ONIL:
+		return false
+
+	case ir.OADD, ir.OSUB, ir.OOR, ir.OXOR, ir.OMUL, ir.OLSH, ir.ORSH, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OMOD:
+		n := n.(*ir.BinaryExpr)
+		return mayAffectMemory(n.X) || mayAffectMemory(n.Y)
+
+	case ir.OINDEX:
+		n := n.(*ir.IndexExpr)
+		return mayAffectMemory(n.X) || mayAffectMemory(n.Index)
+
+	case ir.OCONVNOP, ir.OCONV:
+		n := n.(*ir.ConvExpr)
+		return mayAffectMemory(n.X)
+
+	case ir.OLEN, ir.OCAP, ir.ONOT, ir.OBITNOT, ir.OPLUS, ir.ONEG, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
+		n := n.(*ir.UnaryExpr)
+		return mayAffectMemory(n.X)
+
+	case ir.ODOT, ir.ODOTPTR:
+		n := n.(*ir.SelectorExpr)
+		return mayAffectMemory(n.X)
+
+	case ir.ODEREF:
+		n := n.(*ir.StarExpr)
+		return mayAffectMemory(n.X)
+
+	default:
+		return true
+	}
+}
+
+// HeapAllocReason returns the reason the given Node must be heap
+// allocated, or the empty string if it doesn't.
+func HeapAllocReason(n ir.Node) string {
+	if n == nil || n.Type() == nil {
+		return ""
+	}
+
+	// Parameters are always passed via the stack.
+	if n.Op() == ir.ONAME {
+		n := n.(*ir.Name)
+		if n.Class == ir.PPARAM || n.Class == ir.PPARAMOUT {
+			return ""
+		}
+	}
+
+	if n.Type().Width > ir.MaxStackVarSize {
+		return "too large for stack"
+	}
+
+	if (n.Op() == ir.ONEW || n.Op() == ir.OPTRLIT) && n.Type().Elem().Width > ir.MaxImplicitStackVarSize {
+		return "too large for stack"
+	}
+
+	if n.Op() == ir.OCLOSURE && typecheck.ClosureType(n.(*ir.ClosureExpr)).Size() > ir.MaxImplicitStackVarSize {
+		return "too large for stack"
+	}
+	if n.Op() == ir.OMETHVALUE && typecheck.MethodValueType(n.(*ir.SelectorExpr)).Size() > ir.MaxImplicitStackVarSize {
+		return "too large for stack"
+	}
+
+	if n.Op() == ir.OMAKESLICE {
+		n := n.(*ir.MakeExpr)
+		r := n.Cap
+		if r == nil {
+			r = n.Len
+		}
+		if !ir.IsSmallIntConst(r) {
+			return "non-constant size"
+		}
+		if t := n.Type(); t.Elem().Width != 0 && ir.Int64Val(r) > ir.MaxImplicitStackVarSize/t.Elem().Width {
+			return "too large for stack"
+		}
+	}
+
+	return ""
+}
diff --git a/src/cmd/compile/internal/gc/export.go b/src/cmd/compile/internal/gc/export.go
index 2137f1d..9bf3c72 100644
--- a/src/cmd/compile/internal/gc/export.go
+++ b/src/cmd/compile/internal/gc/export.go
@@ -5,46 +5,16 @@
 package gc
 
 import (
+	"fmt"
+	"go/constant"
+
 	"cmd/compile/internal/base"
-	"cmd/compile/internal/inline"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
 	"cmd/internal/bio"
-	"fmt"
-	"go/constant"
 )
 
-func exportf(bout *bio.Writer, format string, args ...interface{}) {
-	fmt.Fprintf(bout, format, args...)
-	if base.Debug.Export != 0 {
-		fmt.Printf(format, args...)
-	}
-}
-
-func dumpexport(bout *bio.Writer) {
-	p := &exporter{marked: make(map[*types.Type]bool)}
-	for _, n := range typecheck.Target.Exports {
-		// Must catch it here rather than Export(), because the type can be
-		// not fully set (still TFORW) when Export() is called.
-		if n.Type() != nil && n.Type().HasTParam() {
-			base.Fatalf("Cannot (yet) export a generic type: %v", n)
-		}
-		p.markObject(n)
-	}
-
-	// The linker also looks for the $$ marker - use char after $$ to distinguish format.
-	exportf(bout, "\n$$B\n") // indicate binary export format
-	off := bout.Offset()
-	typecheck.WriteExports(bout.Writer)
-	size := bout.Offset() - off
-	exportf(bout, "\n$$\n")
-
-	if base.Debug.Export != 0 {
-		fmt.Printf("BenchmarkExportSize:%s 1 %d bytes\n", base.Ctxt.Pkgpath, size)
-	}
-}
-
 func dumpasmhdr() {
 	b, err := bio.Create(base.Flag.AsmHdr)
 	if err != nil {
@@ -79,83 +49,3 @@
 
 	b.Close()
 }
-
-type exporter struct {
-	marked map[*types.Type]bool // types already seen by markType
-}
-
-// markObject visits a reachable object.
-func (p *exporter) markObject(n ir.Node) {
-	if n.Op() == ir.ONAME {
-		n := n.(*ir.Name)
-		if n.Class == ir.PFUNC {
-			inline.Inline_Flood(n, typecheck.Export)
-		}
-	}
-
-	p.markType(n.Type())
-}
-
-// markType recursively visits types reachable from t to identify
-// functions whose inline bodies may be needed.
-func (p *exporter) markType(t *types.Type) {
-	if p.marked[t] {
-		return
-	}
-	p.marked[t] = true
-
-	// If this is a named type, mark all of its associated
-	// methods. Skip interface types because t.Methods contains
-	// only their unexpanded method set (i.e., exclusive of
-	// interface embeddings), and the switch statement below
-	// handles their full method set.
-	if t.Sym() != nil && t.Kind() != types.TINTER {
-		for _, m := range t.Methods().Slice() {
-			if types.IsExported(m.Sym.Name) {
-				p.markObject(ir.AsNode(m.Nname))
-			}
-		}
-	}
-
-	// Recursively mark any types that can be produced given a
-	// value of type t: dereferencing a pointer; indexing or
-	// iterating over an array, slice, or map; receiving from a
-	// channel; accessing a struct field or interface method; or
-	// calling a function.
-	//
-	// Notably, we don't mark function parameter types, because
-	// the user already needs some way to construct values of
-	// those types.
-	switch t.Kind() {
-	case types.TPTR, types.TARRAY, types.TSLICE:
-		p.markType(t.Elem())
-
-	case types.TCHAN:
-		if t.ChanDir().CanRecv() {
-			p.markType(t.Elem())
-		}
-
-	case types.TMAP:
-		p.markType(t.Key())
-		p.markType(t.Elem())
-
-	case types.TSTRUCT:
-		for _, f := range t.FieldSlice() {
-			if types.IsExported(f.Sym.Name) || f.Embedded != 0 {
-				p.markType(f.Type)
-			}
-		}
-
-	case types.TFUNC:
-		for _, f := range t.Results().FieldSlice() {
-			p.markType(f.Type)
-		}
-
-	case types.TINTER:
-		for _, f := range t.AllMethods().Slice() {
-			if types.IsExported(f.Sym.Name) {
-				p.markType(f.Type)
-			}
-		}
-	}
-}
diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index ce50cbb..6a373ce 100644
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -32,6 +32,7 @@
 	"log"
 	"os"
 	"runtime"
+	"sort"
 )
 
 func hidePanic() {
@@ -159,9 +160,6 @@
 		dwarf.EnableLogging(base.Debug.DwarfInl != 0)
 	}
 	if base.Debug.SoftFloat != 0 {
-		if buildcfg.Experiment.RegabiArgs {
-			log.Fatalf("softfloat mode with GOEXPERIMENT=regabiargs not implemented ")
-		}
 		ssagen.Arch.SoftFloat = true
 	}
 
@@ -181,23 +179,41 @@
 
 	typecheck.Target = new(ir.Package)
 
-	typecheck.NeedITab = func(t, iface *types.Type) { reflectdata.ITabAddr(t, iface) }
 	typecheck.NeedRuntimeType = reflectdata.NeedRuntimeType // TODO(rsc): TypeSym for lock?
 
 	base.AutogeneratedPos = makePos(src.NewFileBase("<autogenerated>", "<autogenerated>"), 1, 0)
 
 	typecheck.InitUniverse()
+	typecheck.InitRuntime()
 
 	// Parse and typecheck input.
 	noder.LoadPackage(flag.Args())
 
 	dwarfgen.RecordPackageName()
 
+	// Prepare for backend processing. This must happen before pkginit,
+	// because it generates itabs for initializing global variables.
+	ssagen.InitConfig()
+
 	// Build init task.
 	if initTask := pkginit.Task(); initTask != nil {
 		typecheck.Export(initTask)
 	}
 
+	// Stability quirk: sort top-level declarations, so we're not
+	// sensitive to the order that functions are added. In particular,
+	// the order that noder+typecheck add function closures is very
+	// subtle, and not important to reproduce.
+	//
+	// Note: This needs to happen after pkginit.Task, otherwise it risks
+	// changing the order in which top-level variables are initialized.
+	if base.Debug.UnifiedQuirks != 0 {
+		s := typecheck.Target.Decls
+		sort.SliceStable(s, func(i, j int) bool {
+			return s[i].Pos().Before(s[j].Pos())
+		})
+	}
+
 	// Eliminate some obviously dead code.
 	// Must happen after typechecking.
 	for _, n := range typecheck.Target.Decls {
@@ -252,6 +268,11 @@
 	base.Timer.Start("fe", "escapes")
 	escape.Funcs(typecheck.Target.Decls)
 
+	// TODO(mdempsky): This is a hack. We need a proper, global work
+	// queue for scheduling function compilation so components don't
+	// need to adjust their behavior depending on when they're called.
+	reflectdata.AfterGlobalEscapeAnalysis = true
+
 	// Collect information for go:nowritebarrierrec
 	// checking. This must happen before transforming closures during Walk
 	// We'll do the final check after write barriers are
@@ -260,17 +281,7 @@
 		ssagen.EnableNoWriteBarrierRecCheck()
 	}
 
-	// Prepare for SSA compilation.
-	// This must be before CompileITabs, because CompileITabs
-	// can trigger function compilation.
-	typecheck.InitRuntime()
-	ssagen.InitConfig()
-
-	// Just before compilation, compile itabs found on
-	// the right side of OCONVIFACE so that methods
-	// can be de-virtualized during compilation.
 	ir.CurFunc = nil
-	reflectdata.CompileITabs()
 
 	// Compile top level functions.
 	// Don't use range--walk can add functions to Target.Decls.
diff --git a/src/cmd/compile/internal/gc/obj.go b/src/cmd/compile/internal/gc/obj.go
index 474d718..c86bf5f 100644
--- a/src/cmd/compile/internal/gc/obj.go
+++ b/src/cmd/compile/internal/gc/obj.go
@@ -7,6 +7,7 @@
 import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
+	"cmd/compile/internal/noder"
 	"cmd/compile/internal/objw"
 	"cmd/compile/internal/reflectdata"
 	"cmd/compile/internal/staticdata"
@@ -103,7 +104,7 @@
 
 func dumpCompilerObj(bout *bio.Writer) {
 	printObjHeader(bout)
-	dumpexport(bout)
+	noder.WriteExports(bout)
 }
 
 func dumpdata() {
@@ -116,7 +117,7 @@
 	addsignats(typecheck.Target.Externs)
 	reflectdata.WriteRuntimeTypes()
 	reflectdata.WriteTabs()
-	numPTabs, numITabs := reflectdata.CountTabs()
+	numPTabs := reflectdata.CountPTabs()
 	reflectdata.WriteImportStrings()
 	reflectdata.WriteBasicTypes()
 	dumpembeds()
@@ -157,13 +158,10 @@
 	if numExports != len(typecheck.Target.Exports) {
 		base.Fatalf("Target.Exports changed after compile functions loop")
 	}
-	newNumPTabs, newNumITabs := reflectdata.CountTabs()
+	newNumPTabs := reflectdata.CountPTabs()
 	if newNumPTabs != numPTabs {
 		base.Fatalf("ptabs changed after compile functions loop")
 	}
-	if newNumITabs != numITabs {
-		base.Fatalf("itabs changed after compile functions loop")
-	}
 }
 
 func dumpLinkerObj(bout *bio.Writer) {
diff --git a/src/cmd/compile/internal/importer/exportdata.go b/src/cmd/compile/internal/importer/exportdata.go
index 3925a64..6a672be 100644
--- a/src/cmd/compile/internal/importer/exportdata.go
+++ b/src/cmd/compile/internal/importer/exportdata.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
diff --git a/src/cmd/compile/internal/importer/gcimporter.go b/src/cmd/compile/internal/importer/gcimporter.go
index feb18cf..ff40be6 100644
--- a/src/cmd/compile/internal/importer/gcimporter.go
+++ b/src/cmd/compile/internal/importer/gcimporter.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -156,7 +155,7 @@
 		// binary export format starts with a 'c', 'd', or 'v'
 		// (from "version"). Select appropriate importer.
 		if len(data) > 0 && data[0] == 'i' {
-			_, pkg, err = iImportData(packages, data[1:], id)
+			pkg, err = ImportData(packages, string(data[1:]), id)
 		} else {
 			err = fmt.Errorf("import %q: old binary export format no longer supported (recompile library)", path)
 		}
diff --git a/src/cmd/compile/internal/importer/gcimporter_test.go b/src/cmd/compile/internal/importer/gcimporter_test.go
index 7fb8fed..44c5e06 100644
--- a/src/cmd/compile/internal/importer/gcimporter_test.go
+++ b/src/cmd/compile/internal/importer/gcimporter_test.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -10,7 +9,6 @@
 	"cmd/compile/internal/types2"
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -64,7 +62,7 @@
 
 func testDir(t *testing.T, dir string, endTime time.Time) (nimports int) {
 	dirname := filepath.Join(runtime.GOROOT(), "pkg", runtime.GOOS+"_"+runtime.GOARCH, dir)
-	list, err := ioutil.ReadDir(dirname)
+	list, err := os.ReadDir(dirname)
 	if err != nil {
 		t.Fatalf("testDir(%s): %s", dirname, err)
 	}
@@ -92,7 +90,7 @@
 }
 
 func mktmpdir(t *testing.T) string {
-	tmpdir, err := ioutil.TempDir("", "gcimporter_test")
+	tmpdir, err := os.MkdirTemp("", "gcimporter_test")
 	if err != nil {
 		t.Fatal("mktmpdir:", err)
 	}
@@ -142,7 +140,7 @@
 	}
 
 	const dir = "./testdata/versions"
-	list, err := ioutil.ReadDir(dir)
+	list, err := os.ReadDir(dir)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -195,7 +193,7 @@
 
 		// create file with corrupted export data
 		// 1) read file
-		data, err := ioutil.ReadFile(filepath.Join(dir, name))
+		data, err := os.ReadFile(filepath.Join(dir, name))
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -212,7 +210,7 @@
 		// 4) write the file
 		pkgpath += "_corrupted"
 		filename := filepath.Join(corruptdir, pkgpath) + ".a"
-		ioutil.WriteFile(filename, data, 0666)
+		os.WriteFile(filename, data, 0666)
 
 		// test that importing the corrupted file results in an error
 		_, err = Import(make(map[string]*types2.Package), pkgpath, corruptdir, nil)
@@ -261,8 +259,7 @@
 	{"io.Reader", "type Reader interface{Read(p []byte) (n int, err error)}"},
 	{"io.ReadWriter", "type ReadWriter interface{Reader; Writer}"},
 	{"go/ast.Node", "type Node interface{End() go/token.Pos; Pos() go/token.Pos}"},
-	// go/types.Type has grown much larger - excluded for now
-	// {"go/types.Type", "type Type interface{String() string; Underlying() Type}"},
+	{"go/types.Type", "type Type interface{String() string; Underlying() Type}"},
 }
 
 func TestImportedTypes(t *testing.T) {
@@ -457,17 +454,17 @@
 		t.Fatal("go/types not found")
 	}
 
-	// look for go/types2.Object type
+	// look for go/types.Object type
 	obj := lookupObj(t, goTypesPkg.Scope(), "Object")
 	typ, ok := obj.Type().(*types2.Named)
 	if !ok {
-		t.Fatalf("go/types2.Object type is %v; wanted named type", typ)
+		t.Fatalf("go/types.Object type is %v; wanted named type", typ)
 	}
 
-	// lookup go/types2.Object.Pkg method
+	// lookup go/types.Object.Pkg method
 	m, index, indirect := types2.LookupFieldOrMethod(typ, false, nil, "Pkg")
 	if m == nil {
-		t.Fatalf("go/types2.Object.Pkg not found (index = %v, indirect = %v)", index, indirect)
+		t.Fatalf("go/types.Object.Pkg not found (index = %v, indirect = %v)", index, indirect)
 	}
 
 	// the method must belong to go/types
diff --git a/src/cmd/compile/internal/importer/iimport.go b/src/cmd/compile/internal/importer/iimport.go
index 8ab0b7b..a317dfc 100644
--- a/src/cmd/compile/internal/importer/iimport.go
+++ b/src/cmd/compile/internal/importer/iimport.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -9,7 +8,6 @@
 package importer
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"cmd/compile/internal/types2"
 	"encoding/binary"
@@ -19,10 +17,11 @@
 	"io"
 	"math/big"
 	"sort"
+	"strings"
 )
 
 type intReader struct {
-	*bytes.Reader
+	*strings.Reader
 	path string
 }
 
@@ -42,6 +41,21 @@
 	return i
 }
 
+// Keep this in sync with constants in iexport.go.
+const (
+	iexportVersionGo1_11 = 0
+	iexportVersionPosCol = 1
+	// TODO: before release, change this back to 2.
+	iexportVersionGenerics = iexportVersionPosCol
+
+	iexportVersionCurrent = iexportVersionGenerics
+)
+
+type ident struct {
+	pkg  string
+	name string
+}
+
 const predeclReserved = 32
 
 type itag uint64
@@ -57,6 +71,9 @@
 	signatureType
 	structType
 	interfaceType
+	typeParamType
+	instType
+	unionType
 )
 
 const io_SeekCurrent = 1 // io.SeekCurrent (not defined in Go 1.4)
@@ -65,8 +82,8 @@
 // and returns the number of bytes consumed and a reference to the package.
 // If the export data version is not recognized or the format is otherwise
 // compromised, an error is returned.
-func iImportData(imports map[string]*types2.Package, data []byte, path string) (_ int, pkg *types2.Package, err error) {
-	const currentVersion = 1
+func ImportData(imports map[string]*types2.Package, data, path string) (pkg *types2.Package, err error) {
+	const currentVersion = iexportVersionCurrent
 	version := int64(-1)
 	defer func() {
 		if e := recover(); e != nil {
@@ -78,13 +95,17 @@
 		}
 	}()
 
-	r := &intReader{bytes.NewReader(data), path}
+	r := &intReader{strings.NewReader(data), path}
 
 	version = int64(r.uint64())
 	switch version {
-	case currentVersion, 0:
+	case /* iexportVersionGenerics, */ iexportVersionPosCol, iexportVersionGo1_11:
 	default:
-		errorf("unknown iexport format version %d", version)
+		if version > iexportVersionGenerics {
+			errorf("unstable iexport format version %d, just rebuild compiler and std library", version)
+		} else {
+			errorf("unknown iexport format version %d", version)
+		}
 	}
 
 	sLen := int64(r.uint64())
@@ -96,16 +117,20 @@
 	r.Seek(sLen+dLen, io_SeekCurrent)
 
 	p := iimporter{
-		ipath:   path,
-		version: int(version),
+		exportVersion: version,
+		ipath:         path,
+		version:       int(version),
 
-		stringData:  stringData,
-		stringCache: make(map[uint64]string),
-		pkgCache:    make(map[uint64]*types2.Package),
+		stringData:   stringData,
+		pkgCache:     make(map[uint64]*types2.Package),
+		posBaseCache: make(map[uint64]*syntax.PosBase),
 
 		declData: declData,
 		pkgIndex: make(map[*types2.Package]map[string]uint64),
 		typCache: make(map[uint64]types2.Type),
+		// Separate map for typeparams, keyed by their package and unique
+		// name (name with subscript).
+		tparamIndex: make(map[ident]types2.Type),
 	}
 
 	for i, pt := range predeclared {
@@ -117,17 +142,22 @@
 		pkgPathOff := r.uint64()
 		pkgPath := p.stringAt(pkgPathOff)
 		pkgName := p.stringAt(r.uint64())
-		_ = r.uint64() // package height; unused by go/types
+		pkgHeight := int(r.uint64())
 
 		if pkgPath == "" {
 			pkgPath = path
 		}
 		pkg := imports[pkgPath]
 		if pkg == nil {
-			pkg = types2.NewPackage(pkgPath, pkgName)
+			pkg = types2.NewPackageHeight(pkgPath, pkgName, pkgHeight)
 			imports[pkgPath] = pkg
-		} else if pkg.Name() != pkgName {
-			errorf("conflicting names %s and %s for package %q", pkg.Name(), pkgName, path)
+		} else {
+			if pkg.Name() != pkgName {
+				errorf("conflicting names %s and %s for package %q", pkg.Name(), pkgName, path)
+			}
+			if pkg.Height() != pkgHeight {
+				errorf("conflicting heights %v and %v for package %q", pkg.Height(), pkgHeight, path)
+			}
 		}
 
 		p.pkgCache[pkgPathOff] = pkg
@@ -153,10 +183,6 @@
 		p.doDecl(localpkg, name)
 	}
 
-	for _, typ := range p.interfaceList {
-		typ.Complete()
-	}
-
 	// record all referenced packages as imports
 	list := append(([]*types2.Package)(nil), pkgList[1:]...)
 	sort.Sort(byPath(list))
@@ -165,21 +191,22 @@
 	// package was imported completely and without errors
 	localpkg.MarkComplete()
 
-	consumed, _ := r.Seek(0, io_SeekCurrent)
-	return int(consumed), localpkg, nil
+	return localpkg, nil
 }
 
 type iimporter struct {
-	ipath   string
-	version int
+	exportVersion int64
+	ipath         string
+	version       int
 
-	stringData  []byte
-	stringCache map[uint64]string
-	pkgCache    map[uint64]*types2.Package
+	stringData   string
+	pkgCache     map[uint64]*types2.Package
+	posBaseCache map[uint64]*syntax.PosBase
 
-	declData []byte
-	pkgIndex map[*types2.Package]map[string]uint64
-	typCache map[uint64]types2.Type
+	declData    string
+	pkgIndex    map[*types2.Package]map[string]uint64
+	typCache    map[uint64]types2.Type
+	tparamIndex map[ident]types2.Type
 
 	interfaceList []*types2.Interface
 }
@@ -199,24 +226,21 @@
 	// Reader.Reset is not available in Go 1.4.
 	// Use bytes.NewReader for now.
 	// r.declReader.Reset(p.declData[off:])
-	r.declReader = *bytes.NewReader(p.declData[off:])
+	r.declReader = *strings.NewReader(p.declData[off:])
 
 	r.obj(name)
 }
 
 func (p *iimporter) stringAt(off uint64) string {
-	if s, ok := p.stringCache[off]; ok {
-		return s
-	}
+	var x [binary.MaxVarintLen64]byte
+	n := copy(x[:], p.stringData[off:])
 
-	slen, n := binary.Uvarint(p.stringData[off:])
+	slen, n := binary.Uvarint(x[:n])
 	if n <= 0 {
 		errorf("varint failed")
 	}
 	spos := off + uint64(n)
-	s := string(p.stringData[spos : spos+slen])
-	p.stringCache[off] = s
-	return s
+	return p.stringData[spos : spos+slen]
 }
 
 func (p *iimporter) pkgAt(off uint64) *types2.Package {
@@ -228,6 +252,16 @@
 	return nil
 }
 
+func (p *iimporter) posBaseAt(off uint64) *syntax.PosBase {
+	if posBase, ok := p.posBaseCache[off]; ok {
+		return posBase
+	}
+	filename := p.stringAt(off)
+	posBase := syntax.NewFileBase(filename)
+	p.posBaseCache[off] = posBase
+	return posBase
+}
+
 func (p *iimporter) typAt(off uint64, base *types2.Named) types2.Type {
 	if t, ok := p.typCache[off]; ok && (base == nil || !isInterface(t)) {
 		return t
@@ -241,7 +275,7 @@
 	// Reader.Reset is not available in Go 1.4.
 	// Use bytes.NewReader for now.
 	// r.declReader.Reset(p.declData[off-predeclReserved:])
-	r.declReader = *bytes.NewReader(p.declData[off-predeclReserved:])
+	r.declReader = *strings.NewReader(p.declData[off-predeclReserved:])
 	t := r.doType(base)
 
 	if base == nil || !isInterface(t) {
@@ -251,12 +285,12 @@
 }
 
 type importReader struct {
-	p          *iimporter
-	declReader bytes.Reader
-	currPkg    *types2.Package
-	prevFile   string
-	prevLine   int64
-	prevColumn int64
+	p           *iimporter
+	declReader  strings.Reader
+	currPkg     *types2.Package
+	prevPosBase *syntax.PosBase
+	prevLine    int64
+	prevColumn  int64
 }
 
 func (r *importReader) obj(name string) {
@@ -274,16 +308,28 @@
 
 		r.declare(types2.NewConst(pos, r.currPkg, name, typ, val))
 
-	case 'F':
+	case 'F', 'G':
+		var tparams []*types2.TypeName
+		if tag == 'G' {
+			tparams = r.tparamList()
+		}
 		sig := r.signature(nil)
-
+		sig.SetTParams(tparams)
 		r.declare(types2.NewFunc(pos, r.currPkg, name, sig))
 
-	case 'T':
+	case 'T', 'U':
+		var tparams []*types2.TypeName
+		if tag == 'U' {
+			tparams = r.tparamList()
+		}
+
 		// Types can be recursive. We need to setup a stub
 		// declaration before recursing.
 		obj := types2.NewTypeName(pos, r.currPkg, name, nil)
 		named := types2.NewNamed(obj, nil, nil)
+		if tag == 'U' {
+			named.SetTParams(tparams)
+		}
 		r.declare(obj)
 
 		underlying := r.p.typAt(r.uint64(), named).Underlying()
@@ -296,10 +342,43 @@
 				recv := r.param()
 				msig := r.signature(recv)
 
+				// If the receiver has any targs, set those as the
+				// rparams of the method (since those are the
+				// typeparams being used in the method sig/body).
+				targs := baseType(msig.Recv().Type()).TArgs()
+				if len(targs) > 0 {
+					rparams := make([]*types2.TypeName, len(targs))
+					for i, targ := range targs {
+						rparams[i] = types2.AsTypeParam(targ).Obj()
+					}
+					msig.SetRParams(rparams)
+				}
+
 				named.AddMethod(types2.NewFunc(mpos, r.currPkg, mname, msig))
 			}
 		}
 
+	case 'P':
+		// We need to "declare" a typeparam in order to have a name that
+		// can be referenced recursively (if needed) in the type param's
+		// bound.
+		if r.p.exportVersion < iexportVersionGenerics {
+			errorf("unexpected type param type")
+		}
+		name0, sub := parseSubscript(name)
+		tn := types2.NewTypeName(pos, r.currPkg, name0, nil)
+		t := (*types2.Checker)(nil).NewTypeParam(tn, nil)
+		if sub == 0 {
+			errorf("missing subscript")
+		}
+		t.SetId(sub)
+		// To handle recursive references to the typeparam within its
+		// bound, save the partial type in tparamIndex before reading the bounds.
+		id := ident{r.currPkg.Name(), name}
+		r.p.tparamIndex[id] = t
+
+		t.SetConstraint(r.typ())
+
 	case 'V':
 		typ := r.typ()
 
@@ -439,12 +518,11 @@
 		r.posv0()
 	}
 
-	if r.prevFile == "" && r.prevLine == 0 && r.prevColumn == 0 {
+	if (r.prevPosBase == nil || r.prevPosBase.Filename() == "") && r.prevLine == 0 && r.prevColumn == 0 {
 		return syntax.Pos{}
 	}
-	// TODO(gri) fix this
-	// return r.p.fake.pos(r.prevFile, int(r.prevLine), int(r.prevColumn))
-	return syntax.Pos{}
+
+	return syntax.MakePos(r.prevPosBase, uint(r.prevLine), uint(r.prevColumn))
 }
 
 func (r *importReader) posv0() {
@@ -454,7 +532,7 @@
 	} else if l := r.int64(); l == -1 {
 		r.prevLine += deltaNewFile
 	} else {
-		r.prevFile = r.string()
+		r.prevPosBase = r.posBase()
 		r.prevLine = l
 	}
 }
@@ -466,7 +544,7 @@
 		delta = r.int64()
 		r.prevLine += delta >> 1
 		if delta&1 != 0 {
-			r.prevFile = r.string()
+			r.prevPosBase = r.posBase()
 		}
 	}
 }
@@ -480,8 +558,9 @@
 	return ok
 }
 
-func (r *importReader) pkg() *types2.Package { return r.p.pkgAt(r.uint64()) }
-func (r *importReader) string() string       { return r.p.stringAt(r.uint64()) }
+func (r *importReader) pkg() *types2.Package     { return r.p.pkgAt(r.uint64()) }
+func (r *importReader) string() string           { return r.p.stringAt(r.uint64()) }
+func (r *importReader) posBase() *syntax.PosBase { return r.p.posBaseAt(r.uint64()) }
 
 func (r *importReader) doType(base *types2.Named) types2.Type {
 	switch k := r.kind(); k {
@@ -554,6 +633,47 @@
 		typ := types2.NewInterfaceType(methods, embeddeds)
 		r.p.interfaceList = append(r.p.interfaceList, typ)
 		return typ
+
+	case typeParamType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			errorf("unexpected type param type")
+		}
+		pkg, name := r.qualifiedIdent()
+		id := ident{pkg.Name(), name}
+		if t, ok := r.p.tparamIndex[id]; ok {
+			// We're already in the process of importing this typeparam.
+			return t
+		}
+		// Otherwise, import the definition of the typeparam now.
+		r.p.doDecl(pkg, name)
+		return r.p.tparamIndex[id]
+
+	case instType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			errorf("unexpected instantiation type")
+		}
+		pos := r.pos()
+		len := r.uint64()
+		targs := make([]types2.Type, len)
+		for i := range targs {
+			targs[i] = r.typ()
+		}
+		baseType := r.typ()
+		// The imported instantiated type doesn't include any methods, so
+		// we must always use the methods of the base (orig) type.
+		var check *types2.Checker // TODO provide a non-nil *Checker
+		t := check.Instantiate(pos, baseType, targs, nil, false)
+		return t
+
+	case unionType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			errorf("unexpected instantiation type")
+		}
+		terms := make([]*types2.Term, r.uint64())
+		for i := range terms {
+			terms[i] = types2.NewTerm(r.bool(), r.typ())
+		}
+		return types2.NewUnion(terms)
 	}
 }
 
@@ -568,6 +688,19 @@
 	return types2.NewSignature(recv, params, results, variadic)
 }
 
+func (r *importReader) tparamList() []*types2.TypeName {
+	n := r.uint64()
+	if n == 0 {
+		return nil
+	}
+	xs := make([]*types2.TypeName, n)
+	for i := range xs {
+		typ := r.typ()
+		xs[i] = types2.AsTypeParam(typ).Obj()
+	}
+	return xs
+}
+
 func (r *importReader) paramList() *types2.Tuple {
 	xs := make([]*types2.Var, r.uint64())
 	for i := range xs {
@@ -610,3 +743,33 @@
 	}
 	return x
 }
+
+func baseType(typ types2.Type) *types2.Named {
+	// pointer receivers are never types2.Named types
+	if p, _ := typ.(*types2.Pointer); p != nil {
+		typ = p.Elem()
+	}
+	// receiver base types are always (possibly generic) types2.Named types
+	n, _ := typ.(*types2.Named)
+	return n
+}
+
+func parseSubscript(name string) (string, uint64) {
+	// Extract the subscript value from the type param name. We export
+	// and import the subscript value, so that all type params have
+	// unique names.
+	sub := uint64(0)
+	startsub := -1
+	for i, r := range name {
+		if '₀' <= r && r < '₀'+10 {
+			if startsub == -1 {
+				startsub = i
+			}
+			sub = sub*10 + uint64(r-'₀')
+		}
+	}
+	if startsub >= 0 {
+		name = name[:startsub]
+	}
+	return name, sub
+}
diff --git a/src/cmd/compile/internal/importer/support.go b/src/cmd/compile/internal/importer/support.go
index 40b9c7c..6ceb413 100644
--- a/src/cmd/compile/internal/importer/support.go
+++ b/src/cmd/compile/internal/importer/support.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -120,6 +119,9 @@
 
 	// used internally by gc; never used by this package or in .a files
 	anyType{},
+
+	// comparable
+	types2.Universe.Lookup("comparable").Type(),
 }
 
 type anyType struct{}
diff --git a/src/cmd/compile/internal/inline/inl.go b/src/cmd/compile/internal/inline/inl.go
index d6b4ced..45a533f 100644
--- a/src/cmd/compile/internal/inline/inl.go
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -179,6 +179,8 @@
 		Cost: inlineMaxBudget - visitor.budget,
 		Dcl:  pruneUnusedAutos(n.Defn.(*ir.Func).Dcl, &visitor),
 		Body: inlcopylist(fn.Body),
+
+		CanDelayResults: canDelayResults(fn),
 	}
 
 	if base.Flag.LowerM > 1 {
@@ -191,60 +193,36 @@
 	}
 }
 
-// Inline_Flood marks n's inline body for export and recursively ensures
-// all called functions are marked too.
-func Inline_Flood(n *ir.Name, exportsym func(*ir.Name)) {
-	if n == nil {
-		return
-	}
-	if n.Op() != ir.ONAME || n.Class != ir.PFUNC {
-		base.Fatalf("Inline_Flood: unexpected %v, %v, %v", n, n.Op(), n.Class)
-	}
-	fn := n.Func
-	if fn == nil {
-		base.Fatalf("Inline_Flood: missing Func on %v", n)
-	}
-	if fn.Inl == nil {
-		return
-	}
+// canDelayResults reports whether inlined calls to fn can delay
+// declaring the result parameter until the "return" statement.
+func canDelayResults(fn *ir.Func) bool {
+	// We can delay declaring+initializing result parameters if:
+	// (1) there's exactly one "return" statement in the inlined function;
+	// (2) it's not an empty return statement (#44355); and
+	// (3) the result parameters aren't named.
 
-	if fn.ExportInline() {
-		return
-	}
-	fn.SetExportInline(true)
-
-	typecheck.ImportedBody(fn)
-
-	var doFlood func(n ir.Node)
-	doFlood = func(n ir.Node) {
-		switch n.Op() {
-		case ir.OMETHEXPR, ir.ODOTMETH:
-			Inline_Flood(ir.MethodExprName(n), exportsym)
-
-		case ir.ONAME:
-			n := n.(*ir.Name)
-			switch n.Class {
-			case ir.PFUNC:
-				Inline_Flood(n, exportsym)
-				exportsym(n)
-			case ir.PEXTERN:
-				exportsym(n)
+	nreturns := 0
+	ir.VisitList(fn.Body, func(n ir.Node) {
+		if n, ok := n.(*ir.ReturnStmt); ok {
+			nreturns++
+			if len(n.Results) == 0 {
+				nreturns++ // empty return statement (case 2)
 			}
+		}
+	})
 
-		case ir.OCALLPART:
-			// Okay, because we don't yet inline indirect
-			// calls to method values.
-		case ir.OCLOSURE:
-			// VisitList doesn't visit closure bodies, so force a
-			// recursive call to VisitList on the body of the closure.
-			ir.VisitList(n.(*ir.ClosureExpr).Func.Body, doFlood)
+	if nreturns != 1 {
+		return false // not exactly one return statement (case 1)
+	}
+
+	// temporaries for return values.
+	for _, param := range fn.Type().Results().FieldSlice() {
+		if sym := types.OrigSym(param.Sym); sym != nil && !sym.IsBlank() {
+			return false // found a named result parameter (case 3)
 		}
 	}
 
-	// Recursively identify all referenced functions for
-	// reexport. We want to include even non-called functions,
-	// because after inlining they might be callable.
-	ir.VisitList(ir.Nodes(fn.Inl.Body), doFlood)
+	return true
 }
 
 // hairyVisitor visits a function body to determine its inlining
@@ -295,6 +273,19 @@
 				}
 			}
 		}
+		if n.X.Op() == ir.OMETHEXPR {
+			if meth := ir.MethodExprName(n.X); meth != nil {
+				fn := meth.Func
+				if fn != nil && types.IsRuntimePkg(fn.Sym().Pkg) && fn.Sym().Name == "heapBits.nextArena" {
+					// Special case: explicitly allow
+					// mid-stack inlining of
+					// runtime.heapBits.next even though
+					// it calls slow-path
+					// runtime.heapBits.nextArena.
+					break
+				}
+			}
+		}
 
 		if ir.IsIntrinsicCall(n) {
 			// Treat like any other node.
@@ -309,28 +300,8 @@
 		// Call cost for non-leaf inlining.
 		v.budget -= v.extraCallCost
 
-	// Call is okay if inlinable and we have the budget for the body.
 	case ir.OCALLMETH:
-		n := n.(*ir.CallExpr)
-		t := n.X.Type()
-		if t == nil {
-			base.Fatalf("no function type for [%p] %+v\n", n.X, n.X)
-		}
-		fn := ir.MethodExprName(n.X).Func
-		if types.IsRuntimePkg(fn.Sym().Pkg) && fn.Sym().Name == "heapBits.nextArena" {
-			// Special case: explicitly allow
-			// mid-stack inlining of
-			// runtime.heapBits.next even though
-			// it calls slow-path
-			// runtime.heapBits.nextArena.
-			break
-		}
-		if fn.Inl != nil {
-			v.budget -= fn.Inl.Cost
-			break
-		}
-		// Call cost for non-leaf inlining.
-		v.budget -= v.extraCallCost
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
 
 	// Things that are too hairy, irrespective of the budget
 	case ir.OCALL, ir.OCALLINTER:
@@ -445,7 +416,7 @@
 		// and don't charge for the OBLOCK itself. The ++ undoes the -- below.
 		v.budget++
 
-	case ir.OCALLPART, ir.OSLICELIT:
+	case ir.OMETHVALUE, ir.OSLICELIT:
 		v.budget-- // Hack for toolstash -cmp.
 
 	case ir.OMETHEXPR:
@@ -499,9 +470,6 @@
 			// x.Func.Body for iexport and local inlining.
 			oldfn := x.Func
 			newfn := ir.NewFunc(oldfn.Pos())
-			if oldfn.ClosureCalled() {
-				newfn.SetClosureCalled(true)
-			}
 			m.(*ir.ClosureExpr).Func = newfn
 			newfn.Nname = ir.NewNameAt(oldfn.Nname.Pos(), oldfn.Nname.Sym())
 			// XXX OK to share fn.Type() ??
@@ -544,37 +512,6 @@
 	ir.CurFunc = savefn
 }
 
-// Turn an OINLCALL into a statement.
-func inlconv2stmt(inlcall *ir.InlinedCallExpr) ir.Node {
-	n := ir.NewBlockStmt(inlcall.Pos(), nil)
-	n.List = inlcall.Init()
-	n.List.Append(inlcall.Body.Take()...)
-	return n
-}
-
-// Turn an OINLCALL into a single valued expression.
-// The result of inlconv2expr MUST be assigned back to n, e.g.
-// 	n.Left = inlconv2expr(n.Left)
-func inlconv2expr(n *ir.InlinedCallExpr) ir.Node {
-	r := n.ReturnVars[0]
-	return ir.InitExpr(append(n.Init(), n.Body...), r)
-}
-
-// Turn the rlist (with the return values) of the OINLCALL in
-// n into an expression list lumping the ninit and body
-// containing the inlined statements on the first list element so
-// order will be preserved. Used in return, oas2func and call
-// statements.
-func inlconv2list(n *ir.InlinedCallExpr) []ir.Node {
-	if n.Op() != ir.OINLCALL || len(n.ReturnVars) == 0 {
-		base.Fatalf("inlconv2list %+v\n", n)
-	}
-
-	s := n.ReturnVars
-	s[0] = ir.InitExpr(append(n.Init(), n.Body...), s[0])
-	return s
-}
-
 // inlnode recurses over the tree to find inlineable calls, which will
 // be turned into OINLCALLs by mkinlcall. When the recursion comes
 // back up will examine left, right, list, rlist, ninit, ntest, nincr,
@@ -597,7 +534,9 @@
 	case ir.ODEFER, ir.OGO:
 		n := n.(*ir.GoDeferStmt)
 		switch call := n.Call; call.Op() {
-		case ir.OCALLFUNC, ir.OCALLMETH:
+		case ir.OCALLMETH:
+			base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+		case ir.OCALLFUNC:
 			call := call.(*ir.CallExpr)
 			call.NoInline = true
 		}
@@ -607,11 +546,18 @@
 	case ir.OCLOSURE:
 		return n
 	case ir.OCALLMETH:
-		// Prevent inlining some reflect.Value methods when using checkptr,
-		// even when package reflect was compiled without it (#35073).
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+	case ir.OCALLFUNC:
 		n := n.(*ir.CallExpr)
-		if s := ir.MethodExprName(n.X).Sym(); base.Debug.Checkptr != 0 && types.IsReflectPkg(s.Pkg) && (s.Name == "Value.UnsafeAddr" || s.Name == "Value.Pointer") {
-			return n
+		if n.X.Op() == ir.OMETHEXPR {
+			// Prevent inlining some reflect.Value methods when using checkptr,
+			// even when package reflect was compiled without it (#35073).
+			if meth := ir.MethodExprName(n.X); meth != nil {
+				s := meth.Sym()
+				if base.Debug.Checkptr != 0 && types.IsReflectPkg(s.Pkg) && (s.Name == "Value.UnsafeAddr" || s.Name == "Value.Pointer") {
+					return n
+				}
+			}
 		}
 	}
 
@@ -619,31 +565,18 @@
 
 	ir.EditChildren(n, edit)
 
-	if as := n; as.Op() == ir.OAS2FUNC {
-		as := as.(*ir.AssignListStmt)
-		if as.Rhs[0].Op() == ir.OINLCALL {
-			as.Rhs = inlconv2list(as.Rhs[0].(*ir.InlinedCallExpr))
-			as.SetOp(ir.OAS2)
-			as.SetTypecheck(0)
-			n = typecheck.Stmt(as)
-		}
-	}
-
 	// with all the branches out of the way, it is now time to
 	// transmogrify this node itself unless inhibited by the
 	// switch at the top of this function.
 	switch n.Op() {
-	case ir.OCALLFUNC, ir.OCALLMETH:
-		n := n.(*ir.CallExpr)
-		if n.NoInline {
-			return n
-		}
-	}
+	case ir.OCALLMETH:
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
 
-	var call *ir.CallExpr
-	switch n.Op() {
 	case ir.OCALLFUNC:
-		call = n.(*ir.CallExpr)
+		call := n.(*ir.CallExpr)
+		if call.NoInline {
+			break
+		}
 		if base.Flag.LowerM > 3 {
 			fmt.Printf("%v:call to func %+v\n", ir.Line(n), call.X)
 		}
@@ -653,38 +586,10 @@
 		if fn := inlCallee(call.X); fn != nil && fn.Inl != nil {
 			n = mkinlcall(call, fn, maxCost, inlMap, edit)
 		}
-
-	case ir.OCALLMETH:
-		call = n.(*ir.CallExpr)
-		if base.Flag.LowerM > 3 {
-			fmt.Printf("%v:call to meth %v\n", ir.Line(n), call.X.(*ir.SelectorExpr).Sel)
-		}
-
-		// typecheck should have resolved ODOTMETH->type, whose nname points to the actual function.
-		if call.X.Type() == nil {
-			base.Fatalf("no function type for [%p] %+v\n", call.X, call.X)
-		}
-
-		n = mkinlcall(call, ir.MethodExprName(call.X).Func, maxCost, inlMap, edit)
 	}
 
 	base.Pos = lno
 
-	if n.Op() == ir.OINLCALL {
-		ic := n.(*ir.InlinedCallExpr)
-		switch call.Use {
-		default:
-			ir.Dump("call", call)
-			base.Fatalf("call missing use")
-		case ir.CallUseExpr:
-			n = inlconv2expr(ic)
-		case ir.CallUseStmt:
-			n = inlconv2stmt(ic)
-		case ir.CallUseList:
-			// leave for caller to convert
-		}
-	}
-
 	return n
 }
 
@@ -740,7 +645,12 @@
 // when producing output for debugging the compiler itself.
 var SSADumpInline = func(*ir.Func) {}
 
-// If n is a call node (OCALLFUNC or OCALLMETH), and fn is an ONAME node for a
+// NewInline allows the inliner implementation to be overridden.
+// If it returns nil, the legacy inliner will handle this call
+// instead.
+var NewInline = func(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr { return nil }
+
+// If n is a OCALLFUNC node, and fn is an ONAME node for a
 // function with an inlinable body, return an OINLCALL node that can replace n.
 // The returned node's Ninit has the parameter assignments, the Nbody is the
 // inlined function body, and (List, Rlist) contain the (input, output)
@@ -793,38 +703,90 @@
 	defer func() {
 		inlMap[fn] = false
 	}()
-	if base.Debug.TypecheckInl == 0 {
-		typecheck.ImportedBody(fn)
+
+	typecheck.FixVariadicCall(n)
+
+	parent := base.Ctxt.PosTable.Pos(n.Pos()).Base().InliningIndex()
+
+	sym := fn.Linksym()
+	inlIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
+
+	if base.Flag.GenDwarfInl > 0 {
+		if !sym.WasInlined() {
+			base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
+			sym.Set(obj.AttrWasInlined, true)
+		}
 	}
 
-	// We have a function node, and it has an inlineable body.
-	if base.Flag.LowerM > 1 {
-		fmt.Printf("%v: inlining call to %v %v { %v }\n", ir.Line(n), fn.Sym(), fn.Type(), ir.Nodes(fn.Inl.Body))
-	} else if base.Flag.LowerM != 0 {
+	if base.Flag.LowerM != 0 {
 		fmt.Printf("%v: inlining call to %v\n", ir.Line(n), fn)
 	}
 	if base.Flag.LowerM > 2 {
 		fmt.Printf("%v: Before inlining: %+v\n", ir.Line(n), n)
 	}
 
+	res := NewInline(n, fn, inlIndex)
+	if res == nil {
+		res = oldInline(n, fn, inlIndex)
+	}
+
+	// transitive inlining
+	// might be nice to do this before exporting the body,
+	// but can't emit the body with inlining expanded.
+	// instead we emit the things that the body needs
+	// and each use must redo the inlining.
+	// luckily these are small.
+	ir.EditChildren(res, edit)
+
+	if base.Flag.LowerM > 2 {
+		fmt.Printf("%v: After inlining %+v\n\n", ir.Line(res), res)
+	}
+
+	return res
+}
+
+// CalleeEffects appends any side effects from evaluating callee to init.
+func CalleeEffects(init *ir.Nodes, callee ir.Node) {
+	for {
+		switch callee.Op() {
+		case ir.ONAME, ir.OCLOSURE, ir.OMETHEXPR:
+			return // done
+
+		case ir.OCONVNOP:
+			conv := callee.(*ir.ConvExpr)
+			init.Append(ir.TakeInit(conv)...)
+			callee = conv.X
+
+		case ir.OINLCALL:
+			ic := callee.(*ir.InlinedCallExpr)
+			init.Append(ir.TakeInit(ic)...)
+			init.Append(ic.Body.Take()...)
+			callee = ic.SingleResult()
+
+		default:
+			base.FatalfAt(callee.Pos(), "unexpected callee expression: %v", callee)
+		}
+	}
+}
+
+// oldInline creates an InlinedCallExpr to replace the given call
+// expression. fn is the callee function to be inlined. inlIndex is
+// the inlining tree position index, for use with src.NewInliningBase
+// when rewriting positions.
+func oldInline(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
+	if base.Debug.TypecheckInl == 0 {
+		typecheck.ImportedBody(fn)
+	}
+
 	SSADumpInline(fn)
 
-	ninit := n.Init()
+	ninit := call.Init()
 
 	// For normal function calls, the function callee expression
-	// may contain side effects (e.g., added by addinit during
-	// inlconv2expr or inlconv2list). Make sure to preserve these,
+	// may contain side effects. Make sure to preserve these,
 	// if necessary (#42703).
-	if n.Op() == ir.OCALLFUNC {
-		callee := n.X
-		for callee.Op() == ir.OCONVNOP {
-			conv := callee.(*ir.ConvExpr)
-			ninit.Append(ir.TakeInit(conv)...)
-			callee = conv.X
-		}
-		if callee.Op() != ir.ONAME && callee.Op() != ir.OCLOSURE && callee.Op() != ir.OMETHEXPR {
-			base.Fatalf("unexpected callee expression: %v", callee)
-		}
+	if call.Op() == ir.OCALLFUNC {
+		CalleeEffects(&ninit, call.X)
 	}
 
 	// Make temp names to use instead of the originals.
@@ -854,25 +816,6 @@
 	}
 
 	// We can delay declaring+initializing result parameters if:
-	// (1) there's exactly one "return" statement in the inlined function;
-	// (2) it's not an empty return statement (#44355); and
-	// (3) the result parameters aren't named.
-	delayretvars := true
-
-	nreturns := 0
-	ir.VisitList(ir.Nodes(fn.Inl.Body), func(n ir.Node) {
-		if n, ok := n.(*ir.ReturnStmt); ok {
-			nreturns++
-			if len(n.Results) == 0 {
-				delayretvars = false // empty return statement (case 2)
-			}
-		}
-	})
-
-	if nreturns != 1 {
-		delayretvars = false // not exactly one return statement (case 1)
-	}
-
 	// temporaries for return values.
 	var retvars []ir.Node
 	for i, t := range fn.Type().Results().Fields().Slice() {
@@ -882,7 +825,6 @@
 			m = inlvar(n)
 			m = typecheck.Expr(m).(*ir.Name)
 			inlvars[n] = m
-			delayretvars = false // found a named result parameter (case 3)
 		} else {
 			// anonymous return values, synthesize names for use in assignment that replaces return
 			m = retvar(t, i)
@@ -905,61 +847,23 @@
 	// Assign arguments to the parameters' temp names.
 	as := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
 	as.Def = true
-	if n.Op() == ir.OCALLMETH {
-		sel := n.X.(*ir.SelectorExpr)
-		if sel.X == nil {
-			base.Fatalf("method call without receiver: %+v", n)
-		}
-		as.Rhs.Append(sel.X)
+	if call.Op() == ir.OCALLMETH {
+		base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
 	}
-	as.Rhs.Append(n.Args...)
-
-	// For non-dotted calls to variadic functions, we assign the
-	// variadic parameter's temp name separately.
-	var vas *ir.AssignStmt
+	as.Rhs.Append(call.Args...)
 
 	if recv := fn.Type().Recv(); recv != nil {
 		as.Lhs.Append(inlParam(recv, as, inlvars))
 	}
 	for _, param := range fn.Type().Params().Fields().Slice() {
-		// For ordinary parameters or variadic parameters in
-		// dotted calls, just add the variable to the
-		// assignment list, and we're done.
-		if !param.IsDDD() || n.IsDDD {
-			as.Lhs.Append(inlParam(param, as, inlvars))
-			continue
-		}
-
-		// Otherwise, we need to collect the remaining values
-		// to pass as a slice.
-
-		x := len(as.Lhs)
-		for len(as.Lhs) < len(as.Rhs) {
-			as.Lhs.Append(argvar(param.Type, len(as.Lhs)))
-		}
-		varargs := as.Lhs[x:]
-
-		vas = ir.NewAssignStmt(base.Pos, nil, nil)
-		vas.X = inlParam(param, vas, inlvars)
-		if len(varargs) == 0 {
-			vas.Y = typecheck.NodNil()
-			vas.Y.SetType(param.Type)
-		} else {
-			lit := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(param.Type), nil)
-			lit.List = varargs
-			vas.Y = lit
-		}
+		as.Lhs.Append(inlParam(param, as, inlvars))
 	}
 
 	if len(as.Rhs) != 0 {
 		ninit.Append(typecheck.Stmt(as))
 	}
 
-	if vas != nil {
-		ninit.Append(typecheck.Stmt(vas))
-	}
-
-	if !delayretvars {
+	if !fn.Inl.CanDelayResults {
 		// Zero the return parameters.
 		for _, n := range retvars {
 			ninit.Append(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
@@ -972,40 +876,21 @@
 
 	inlgen++
 
-	parent := -1
-	if b := base.Ctxt.PosTable.Pos(n.Pos()).Base(); b != nil {
-		parent = b.InliningIndex()
-	}
-
-	sym := fn.Linksym()
-	newIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
-
 	// Add an inline mark just before the inlined body.
 	// This mark is inline in the code so that it's a reasonable spot
 	// to put a breakpoint. Not sure if that's really necessary or not
 	// (in which case it could go at the end of the function instead).
 	// Note issue 28603.
-	inlMark := ir.NewInlineMarkStmt(base.Pos, types.BADWIDTH)
-	inlMark.SetPos(n.Pos().WithIsStmt())
-	inlMark.Index = int64(newIndex)
-	ninit.Append(inlMark)
-
-	if base.Flag.GenDwarfInl > 0 {
-		if !sym.WasInlined() {
-			base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
-			sym.Set(obj.AttrWasInlined, true)
-		}
-	}
+	ninit.Append(ir.NewInlineMarkStmt(call.Pos().WithIsStmt(), int64(inlIndex)))
 
 	subst := inlsubst{
-		retlabel:     retlabel,
-		retvars:      retvars,
-		delayretvars: delayretvars,
-		inlvars:      inlvars,
-		defnMarker:   ir.NilExpr{},
-		bases:        make(map[*src.PosBase]*src.PosBase),
-		newInlIndex:  newIndex,
-		fn:           fn,
+		retlabel:    retlabel,
+		retvars:     retvars,
+		inlvars:     inlvars,
+		defnMarker:  ir.NilExpr{},
+		bases:       make(map[*src.PosBase]*src.PosBase),
+		newInlIndex: inlIndex,
+		fn:          fn,
 	}
 	subst.edit = subst.node
 
@@ -1026,26 +911,11 @@
 
 	//dumplist("ninit post", ninit);
 
-	call := ir.NewInlinedCallExpr(base.Pos, nil, nil)
-	*call.PtrInit() = ninit
-	call.Body = body
-	call.ReturnVars = retvars
-	call.SetType(n.Type())
-	call.SetTypecheck(1)
-
-	// transitive inlining
-	// might be nice to do this before exporting the body,
-	// but can't emit the body with inlining expanded.
-	// instead we emit the things that the body needs
-	// and each use must redo the inlining.
-	// luckily these are small.
-	ir.EditChildren(call, edit)
-
-	if base.Flag.LowerM > 2 {
-		fmt.Printf("%v: After inlining %+v\n\n", ir.Line(call), call)
-	}
-
-	return call
+	res := ir.NewInlinedCallExpr(base.Pos, body, retvars)
+	res.SetInit(ninit)
+	res.SetType(call.Type())
+	res.SetTypecheck(1)
+	return res
 }
 
 // Every time we expand a function we generate a new set of tmpnames,
@@ -1058,8 +928,10 @@
 
 	n := typecheck.NewName(var_.Sym())
 	n.SetType(var_.Type())
+	n.SetTypecheck(1)
 	n.Class = ir.PAUTO
 	n.SetUsed(true)
+	n.SetAutoTemp(var_.AutoTemp())
 	n.Curfn = ir.CurFunc // the calling function, not the called one
 	n.SetAddrtaken(var_.Addrtaken())
 
@@ -1071,18 +943,7 @@
 func retvar(t *types.Field, i int) *ir.Name {
 	n := typecheck.NewName(typecheck.LookupNum("~R", i))
 	n.SetType(t.Type)
-	n.Class = ir.PAUTO
-	n.SetUsed(true)
-	n.Curfn = ir.CurFunc // the calling function, not the called one
-	ir.CurFunc.Dcl = append(ir.CurFunc.Dcl, n)
-	return n
-}
-
-// Synthesize a variable to store the inlined function's arguments
-// when they come from a multiple return call.
-func argvar(t *types.Type, i int) ir.Node {
-	n := typecheck.NewName(typecheck.LookupNum("~arg", i))
-	n.SetType(t.Elem())
+	n.SetTypecheck(1)
 	n.Class = ir.PAUTO
 	n.SetUsed(true)
 	n.Curfn = ir.CurFunc // the calling function, not the called one
@@ -1099,10 +960,6 @@
 	// Temporary result variables.
 	retvars []ir.Node
 
-	// Whether result variables should be initialized at the
-	// "return" statement.
-	delayretvars bool
-
 	inlvars map[*ir.Name]*ir.Name
 	// defnMarker is used to mark a Node for reassignment.
 	// inlsubst.clovar set this during creating new ONAME.
@@ -1157,17 +1014,21 @@
 // clovar creates a new ONAME node for a local variable or param of a closure
 // inside a function being inlined.
 func (subst *inlsubst) clovar(n *ir.Name) *ir.Name {
-	// TODO(danscales): want to get rid of this shallow copy, with code like the
-	// following, but it is hard to copy all the necessary flags in a maintainable way.
-	// m := ir.NewNameAt(n.Pos(), n.Sym())
-	// m.Class = n.Class
-	// m.SetType(n.Type())
-	// m.SetTypecheck(1)
-	//if n.IsClosureVar() {
-	//	m.SetIsClosureVar(true)
-	//}
-	m := &ir.Name{}
-	*m = *n
+	m := ir.NewNameAt(n.Pos(), n.Sym())
+	m.Class = n.Class
+	m.SetType(n.Type())
+	m.SetTypecheck(1)
+	if n.IsClosureVar() {
+		m.SetIsClosureVar(true)
+	}
+	if n.Addrtaken() {
+		m.SetAddrtaken(true)
+	}
+	if n.Used() {
+		m.SetUsed(true)
+	}
+	m.Defn = n.Defn
+
 	m.Curfn = subst.newclofn
 
 	switch defn := n.Defn.(type) {
@@ -1222,8 +1083,6 @@
 // closure does the necessary substitions for a ClosureExpr n and returns the new
 // closure node.
 func (subst *inlsubst) closure(n *ir.ClosureExpr) ir.Node {
-	m := ir.Copy(n)
-
 	// Prior to the subst edit, set a flag in the inlsubst to
 	// indicated that we don't want to update the source positions in
 	// the new closure. If we do this, it will appear that the closure
@@ -1231,29 +1090,16 @@
 	// issue #46234 for more details.
 	defer func(prev bool) { subst.noPosUpdate = prev }(subst.noPosUpdate)
 	subst.noPosUpdate = true
-	ir.EditChildren(m, subst.edit)
 
 	//fmt.Printf("Inlining func %v with closure into %v\n", subst.fn, ir.FuncName(ir.CurFunc))
 
-	// The following is similar to funcLit
 	oldfn := n.Func
-	newfn := ir.NewFunc(oldfn.Pos())
-	// These three lines are not strictly necessary, but just to be clear
-	// that new function needs to redo typechecking and inlinability.
-	newfn.SetTypecheck(0)
-	newfn.SetInlinabilityChecked(false)
-	newfn.Inl = nil
-	newfn.SetIsHiddenClosure(true)
-	newfn.Nname = ir.NewNameAt(n.Pos(), ir.BlankNode.Sym())
-	newfn.Nname.Func = newfn
+	newfn := ir.NewClosureFunc(oldfn.Pos(), true)
+
 	// Ntype can be nil for -G=3 mode.
 	if oldfn.Nname.Ntype != nil {
 		newfn.Nname.Ntype = subst.node(oldfn.Nname.Ntype).(ir.Ntype)
 	}
-	newfn.Nname.Defn = newfn
-
-	m.(*ir.ClosureExpr).Func = newfn
-	newfn.OClosure = m.(*ir.ClosureExpr)
 
 	if subst.newclofn != nil {
 		//fmt.Printf("Inlining a closure with a nested closure\n")
@@ -1303,13 +1149,9 @@
 
 	// Actually create the named function for the closure, now that
 	// the closure is inlined in a specific function.
-	m.SetTypecheck(0)
-	if oldfn.ClosureCalled() {
-		typecheck.Callee(m)
-	} else {
-		typecheck.Expr(m)
-	}
-	return m
+	newclo := newfn.OClosure
+	newclo.SetInit(subst.list(n.Init()))
+	return typecheck.Expr(newclo)
 }
 
 // node recursively copies a node from the saved pristine body of the
@@ -1391,7 +1233,7 @@
 			}
 			as.Rhs = subst.list(n.Results)
 
-			if subst.delayretvars {
+			if subst.fn.Inl.CanDelayResults {
 				for _, n := range as.Lhs {
 					as.PtrInit().Append(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
 					n.Name().Defn = as
diff --git a/src/cmd/compile/internal/ir/expr.go b/src/cmd/compile/internal/ir/expr.go
index f70645f..dc28483 100644
--- a/src/cmd/compile/internal/ir/expr.go
+++ b/src/cmd/compile/internal/ir/expr.go
@@ -142,28 +142,15 @@
 	}
 }
 
-// A CallUse records how the result of the call is used:
-type CallUse byte
-
-const (
-	_ CallUse = iota
-
-	CallUseExpr // single expression result is used
-	CallUseList // list of results are used
-	CallUseStmt // results not used - call is a statement
-)
-
 // A CallExpr is a function call X(Args).
 type CallExpr struct {
 	miniExpr
 	origNode
-	X               Node
-	Args            Nodes
-	KeepAlive       []*Name // vars to be kept alive until call returns
-	IsDDD           bool
-	Use             CallUse
-	NoInline        bool
-	PreserveClosure bool // disable directClosureCall for this call
+	X         Node
+	Args      Nodes
+	KeepAlive []*Name // vars to be kept alive until call returns
+	IsDDD     bool
+	NoInline  bool
 }
 
 func NewCallExpr(pos src.XPos, op Op, fun Node, args []Node) *CallExpr {
@@ -181,8 +168,12 @@
 	switch op {
 	default:
 		panic(n.no("SetOp " + op.String()))
-	case OCALL, OCALLFUNC, OCALLINTER, OCALLMETH,
-		OAPPEND, ODELETE, OGETG, OMAKE, OPRINT, OPRINTN, ORECOVER:
+	case OAPPEND,
+		OCALL, OCALLFUNC, OCALLINTER, OCALLMETH,
+		ODELETE,
+		OGETG, OGETCALLERPC, OGETCALLERSP,
+		OMAKE, OPRINT, OPRINTN,
+		ORECOVER, ORECOVERFP:
 		n.op = op
 	}
 }
@@ -192,8 +183,10 @@
 	miniExpr
 	Func     *Func `mknode:"-"`
 	Prealloc *Name
+	IsGoWrap bool // whether this is wrapper closure of a go statement
 }
 
+// Deprecated: Use NewClosureFunc instead.
 func NewClosureExpr(pos src.XPos, fn *Func) *ClosureExpr {
 	n := &ClosureExpr{Func: fn}
 	n.op = OCLOSURE
@@ -277,7 +270,7 @@
 	switch op {
 	default:
 		panic(n.no("SetOp " + op.String()))
-	case OCONV, OCONVIFACE, OCONVNOP, OBYTES2STR, OBYTES2STRTMP, ORUNES2STR, OSTR2BYTES, OSTR2BYTESTMP, OSTR2RUNES, ORUNESTR, OSLICE2ARRPTR:
+	case OCONV, OCONVIFACE, OCONVIDATA, OCONVNOP, OBYTES2STR, OBYTES2STRTMP, ORUNES2STR, OSTR2BYTES, OSTR2BYTESTMP, OSTR2RUNES, ORUNESTR, OSLICE2ARRPTR:
 		n.op = op
 	}
 }
@@ -323,26 +316,24 @@
 // A StructKeyExpr is an Field: Value composite literal key.
 type StructKeyExpr struct {
 	miniExpr
-	Field  *types.Sym
-	Value  Node
-	Offset int64
+	Field *types.Field
+	Value Node
 }
 
-func NewStructKeyExpr(pos src.XPos, field *types.Sym, value Node) *StructKeyExpr {
+func NewStructKeyExpr(pos src.XPos, field *types.Field, value Node) *StructKeyExpr {
 	n := &StructKeyExpr{Field: field, Value: value}
 	n.pos = pos
 	n.op = OSTRUCTKEY
-	n.Offset = types.BADWIDTH
 	return n
 }
 
-func (n *StructKeyExpr) Sym() *types.Sym { return n.Field }
+func (n *StructKeyExpr) Sym() *types.Sym { return n.Field.Sym }
 
 // An InlinedCallExpr is an inlined function call.
 type InlinedCallExpr struct {
 	miniExpr
 	Body       Nodes
-	ReturnVars Nodes
+	ReturnVars Nodes // must be side-effect free
 }
 
 func NewInlinedCallExpr(pos src.XPos, body, retvars []Node) *InlinedCallExpr {
@@ -354,6 +345,21 @@
 	return n
 }
 
+func (n *InlinedCallExpr) SingleResult() Node {
+	if have := len(n.ReturnVars); have != 1 {
+		base.FatalfAt(n.Pos(), "inlined call has %v results, expected 1", have)
+	}
+	if !n.Type().HasShape() && n.ReturnVars[0].Type().HasShape() {
+		// If the type of the call is not a shape, but the type of the return value
+		// is a shape, we need to do an implicit conversion, so the real type
+		// of n is maintained.
+		r := NewConvExpr(n.Pos(), OCONVNOP, n.Type(), n.ReturnVars[0])
+		r.SetTypecheck(1)
+		return r
+	}
+	return n.ReturnVars[0]
+}
+
 // A LogicalExpr is a expression X Op Y where Op is && or ||.
 // It is separate from BinaryExpr to make room for statements
 // that must be executed before Y but after X.
@@ -448,6 +454,20 @@
 	t.SetNod(n)
 }
 
+// A RawOrigExpr represents an arbitrary Go expression as a string value.
+// When printed in diagnostics, the string value is written out exactly as-is.
+type RawOrigExpr struct {
+	miniExpr
+	Raw string
+}
+
+func NewRawOrigExpr(pos src.XPos, op Op, raw string) *RawOrigExpr {
+	n := &RawOrigExpr{Raw: raw}
+	n.pos = pos
+	n.op = op
+	return n
+}
+
 // A ResultExpr represents a direct access to a result.
 type ResultExpr struct {
 	miniExpr
@@ -494,10 +514,15 @@
 // A SelectorExpr is a selector expression X.Sel.
 type SelectorExpr struct {
 	miniExpr
-	X         Node
-	Sel       *types.Sym
+	X Node
+	// Sel is the name of the field or method being selected, without (in the
+	// case of methods) any preceding type specifier. If the field/method is
+	// exported, than the Sym uses the local package regardless of the package
+	// of the containing type.
+	Sel *types.Sym
+	// The actual selected field - may not be filled in until typechecking.
 	Selection *types.Field
-	Prealloc  *Name // preallocated storage for OCALLPART, if any
+	Prealloc  *Name // preallocated storage for OMETHVALUE, if any
 }
 
 func NewSelectorExpr(pos src.XPos, op Op, x Node, sel *types.Sym) *SelectorExpr {
@@ -511,7 +536,7 @@
 	switch op {
 	default:
 		panic(n.no("SetOp " + op.String()))
-	case OXDOT, ODOT, ODOTPTR, ODOTMETH, ODOTINTER, OCALLPART, OMETHEXPR:
+	case OXDOT, ODOT, ODOTPTR, ODOTMETH, ODOTINTER, OMETHVALUE, OMETHEXPR:
 		n.op = op
 	}
 }
@@ -652,6 +677,38 @@
 	}
 }
 
+// A DynamicTypeAssertExpr asserts that X is of dynamic type T.
+type DynamicTypeAssertExpr struct {
+	miniExpr
+	X Node
+	// N = not an interface
+	// E = empty interface
+	// I = nonempty interface
+	// For E->N, T is a *runtime.type for N
+	// For I->N, T is a *runtime.itab for N+I
+	// For E->I, T is a *runtime.type for I
+	// For I->I, ditto
+	// For I->E, T is a *runtime.type for interface{} (unnecessary, but just to fill in the slot)
+	// For E->E, ditto
+	T Node
+}
+
+func NewDynamicTypeAssertExpr(pos src.XPos, op Op, x, t Node) *DynamicTypeAssertExpr {
+	n := &DynamicTypeAssertExpr{X: x, T: t}
+	n.pos = pos
+	n.op = op
+	return n
+}
+
+func (n *DynamicTypeAssertExpr) SetOp(op Op) {
+	switch op {
+	default:
+		panic(n.no("SetOp " + op.String()))
+	case ODYNAMICDOTTYPE, ODYNAMICDOTTYPE2:
+		n.op = op
+	}
+}
+
 // A UnaryExpr is a unary expression Op X,
 // or Op(X) for a builtin function that does not end up being a call.
 type UnaryExpr struct {
@@ -678,6 +735,11 @@
 	}
 }
 
+// Probably temporary: using Implicit() flag to mark generic function nodes that
+// are called to make getGfInfo analysis easier in one pre-order pass.
+func (n *InstExpr) Implicit() bool     { return n.flags&miniExprImplicit != 0 }
+func (n *InstExpr) SetImplicit(b bool) { n.flags.set(miniExprImplicit, b) }
+
 // An InstExpr is a generic function or type instantiation.
 type InstExpr struct {
 	miniExpr
@@ -773,6 +835,11 @@
 			continue
 		}
 
+		if n.Op() == OINLCALL {
+			n = n.(*InlinedCallExpr).SingleResult()
+			continue
+		}
+
 		n1 := staticValue1(n)
 		if n1 == nil {
 			return n
@@ -1071,7 +1138,7 @@
 // MethodExprFunc is like MethodExprName, but returns the types.Field instead.
 func MethodExprFunc(n Node) *types.Field {
 	switch n.Op() {
-	case ODOTMETH, OMETHEXPR, OCALLPART:
+	case ODOTMETH, OMETHEXPR, OMETHVALUE:
 		return n.(*SelectorExpr).Selection
 	}
 	base.Fatalf("unexpected node: %v (%v)", n, n.Op())
diff --git a/src/cmd/compile/internal/ir/fmt.go b/src/cmd/compile/internal/ir/fmt.go
index f2ae0f7..d19fe45 100644
--- a/src/cmd/compile/internal/ir/fmt.go
+++ b/src/cmd/compile/internal/ir/fmt.go
@@ -185,6 +185,7 @@
 	OCLOSE:         8,
 	OCOMPLIT:       8,
 	OCONVIFACE:     8,
+	OCONVIDATA:     8,
 	OCONVNOP:       8,
 	OCONV:          8,
 	OCOPY:          8,
@@ -237,7 +238,7 @@
 	ODOTTYPE:       8,
 	ODOT:           8,
 	OXDOT:          8,
-	OCALLPART:      8,
+	OMETHVALUE:     8,
 	OMETHEXPR:      8,
 	OPLUS:          7,
 	ONOT:           7,
@@ -546,7 +547,7 @@
 				n = nn.X
 				continue
 			}
-		case OCONV, OCONVNOP, OCONVIFACE:
+		case OCONV, OCONVNOP, OCONVIFACE, OCONVIDATA:
 			nn := nn.(*ConvExpr)
 			if nn.Implicit() {
 				n = nn.X
@@ -567,6 +568,11 @@
 		return
 	}
 
+	if n, ok := n.(*RawOrigExpr); ok {
+		fmt.Fprint(s, n.Raw)
+		return
+	}
+
 	switch n.Op() {
 	case OPAREN:
 		n := n.(*ParenExpr)
@@ -709,6 +715,10 @@
 				fmt.Fprintf(s, "... argument")
 				return
 			}
+			if typ := n.Type(); typ != nil {
+				fmt.Fprintf(s, "%v{%s}", typ, ellipsisIf(len(n.List) != 0))
+				return
+			}
 			if n.Ntype != nil {
 				fmt.Fprintf(s, "%v{%s}", n.Ntype, ellipsisIf(len(n.List) != 0))
 				return
@@ -752,7 +762,7 @@
 		n := n.(*StructKeyExpr)
 		fmt.Fprintf(s, "%v:%v", n.Field, n.Value)
 
-	case OXDOT, ODOT, ODOTPTR, ODOTINTER, ODOTMETH, OCALLPART, OMETHEXPR:
+	case OXDOT, ODOT, ODOTPTR, ODOTINTER, ODOTMETH, OMETHVALUE, OMETHEXPR:
 		n := n.(*SelectorExpr)
 		exprFmt(n.X, s, nprec)
 		if n.Sel == nil {
@@ -804,6 +814,7 @@
 
 	case OCONV,
 		OCONVIFACE,
+		OCONVIDATA,
 		OCONVNOP,
 		OBYTES2STR,
 		ORUNES2STR,
@@ -854,6 +865,15 @@
 		}
 		fmt.Fprintf(s, "(%.v)", n.Args)
 
+	case OINLCALL:
+		n := n.(*InlinedCallExpr)
+		// TODO(mdempsky): Print Init and/or Body?
+		if len(n.ReturnVars) == 1 {
+			fmt.Fprintf(s, "%v", n.ReturnVars[0])
+			return
+		}
+		fmt.Fprintf(s, "(.%v)", n.ReturnVars)
+
 	case OMAKEMAP, OMAKECHAN, OMAKESLICE:
 		n := n.(*MakeExpr)
 		if n.Cap != nil {
@@ -986,7 +1006,7 @@
 
 // Dump prints the message s followed by a debug dump of n.
 func Dump(s string, n Node) {
-	fmt.Printf("%s [%p]%+v\n", s, n, n)
+	fmt.Printf("%s%+v\n", s, n)
 }
 
 // DumpList prints the message s followed by a debug dump of each node in the list.
@@ -1114,16 +1134,21 @@
 	}
 
 	if n.Pos().IsKnown() {
-		pfx := ""
+		fmt.Fprint(w, " # ")
 		switch n.Pos().IsStmt() {
 		case src.PosNotStmt:
-			pfx = "_" // "-" would be confusing
+			fmt.Fprint(w, "_") // "-" would be confusing
 		case src.PosIsStmt:
-			pfx = "+"
+			fmt.Fprint(w, "+")
 		}
-		pos := base.Ctxt.PosTable.Pos(n.Pos())
-		file := filepath.Base(pos.Filename())
-		fmt.Fprintf(w, " # %s%s:%d", pfx, file, pos.Line())
+		for i, pos := range base.Ctxt.AllPos(n.Pos(), nil) {
+			if i > 0 {
+				fmt.Fprint(w, ",")
+			}
+			// TODO(mdempsky): Print line pragma details too.
+			file := filepath.Base(pos.Filename())
+			fmt.Fprintf(w, "%s:%d:%d", file, pos.Line(), pos.Col())
+		}
 	}
 }
 
diff --git a/src/cmd/compile/internal/ir/func.go b/src/cmd/compile/internal/ir/func.go
index 20fe965..269b6f1 100644
--- a/src/cmd/compile/internal/ir/func.go
+++ b/src/cmd/compile/internal/ir/func.go
@@ -9,6 +9,7 @@
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
 	"cmd/internal/src"
+	"fmt"
 )
 
 // A Func corresponds to a single function in a Go program
@@ -39,14 +40,14 @@
 // constructs a fresh node.
 //
 // A method value (t.M) is represented by ODOTMETH/ODOTINTER
-// when it is called directly and by OCALLPART otherwise.
+// when it is called directly and by OMETHVALUE otherwise.
 // These are like method expressions, except that for ODOTMETH/ODOTINTER,
 // the method name is stored in Sym instead of Right.
-// Each OCALLPART ends up being implemented as a new
+// Each OMETHVALUE ends up being implemented as a new
 // function, a bit like a closure, with its own ODCLFUNC.
-// The OCALLPART uses n.Func to record the linkage to
+// The OMETHVALUE uses n.Func to record the linkage to
 // the generated ODCLFUNC, but there is no
-// pointer from the Func back to the OCALLPART.
+// pointer from the Func back to the OMETHVALUE.
 type Func struct {
 	miniNode
 	Body Nodes
@@ -166,6 +167,11 @@
 	// another package is imported.
 	Dcl  []*Name
 	Body []Node
+
+	// CanDelayResults reports whether it's safe for the inliner to delay
+	// initializing the result parameters until immediately before the
+	// "return" statement.
+	CanDelayResults bool
 }
 
 // A Mark represents a scope boundary.
@@ -196,7 +202,7 @@
 	funcExportInline             // include inline body in export data
 	funcInstrumentBody           // add race/msan instrumentation during SSA construction
 	funcOpenCodedDeferDisallowed // can't do open-coded defers
-	funcClosureCalled            // closure is only immediately called
+	funcClosureCalled            // closure is only immediately called; used by escape analysis
 )
 
 type SymAndPos struct {
@@ -272,6 +278,17 @@
 
 var CurFunc *Func
 
+// WithFunc invokes do with CurFunc and base.Pos set to curfn and
+// curfn.Pos(), respectively, and then restores their previous values
+// before returning.
+func WithFunc(curfn *Func, do func()) {
+	oldfn, oldpos := CurFunc, base.Pos
+	defer func() { CurFunc, base.Pos = oldfn, oldpos }()
+
+	CurFunc, base.Pos = curfn, curfn.Pos()
+	do()
+}
+
 func FuncSymName(s *types.Sym) string {
 	return s.Name + "·f"
 }
@@ -279,7 +296,7 @@
 // MarkFunc marks a node as a function.
 func MarkFunc(n *Name) {
 	if n.Op() != ONAME || n.Class != Pxxx {
-		base.Fatalf("expected ONAME/Pxxx node, got %v", n)
+		base.FatalfAt(n.Pos(), "expected ONAME/Pxxx node, got %v (%v/%v)", n, n.Op(), n.Class)
 	}
 
 	n.Class = PFUNC
@@ -296,8 +313,8 @@
 			base.WarnfAt(clo.Pos(), "stack closure, captured vars = %v", clo.Func.ClosureVars)
 		}
 	}
-	if base.Flag.CompilingRuntime && clo.Esc() == EscHeap {
-		base.ErrorfAt(clo.Pos(), "heap-allocated closure, not allowed in runtime")
+	if base.Flag.CompilingRuntime && clo.Esc() == EscHeap && !clo.IsGoWrap {
+		base.ErrorfAt(clo.Pos(), "heap-allocated closure %s, not allowed in runtime", FuncName(clo.Func))
 	}
 }
 
@@ -306,3 +323,109 @@
 func IsTrivialClosure(clo *ClosureExpr) bool {
 	return len(clo.Func.ClosureVars) == 0
 }
+
+// globClosgen is like Func.Closgen, but for the global scope.
+var globClosgen int32
+
+// closureName generates a new unique name for a closure within outerfn.
+func closureName(outerfn *Func) *types.Sym {
+	pkg := types.LocalPkg
+	outer := "glob."
+	prefix := "func"
+	gen := &globClosgen
+
+	if outerfn != nil {
+		if outerfn.OClosure != nil {
+			prefix = ""
+		}
+
+		pkg = outerfn.Sym().Pkg
+		outer = FuncName(outerfn)
+
+		// There may be multiple functions named "_". In those
+		// cases, we can't use their individual Closgens as it
+		// would lead to name clashes.
+		if !IsBlank(outerfn.Nname) {
+			gen = &outerfn.Closgen
+		}
+	}
+
+	*gen++
+	return pkg.Lookup(fmt.Sprintf("%s.%s%d", outer, prefix, *gen))
+}
+
+// NewClosureFunc creates a new Func to represent a function literal.
+// If hidden is true, then the closure is marked hidden (i.e., as a
+// function literal contained within another function, rather than a
+// package-scope variable initialization expression).
+func NewClosureFunc(pos src.XPos, hidden bool) *Func {
+	fn := NewFunc(pos)
+	fn.SetIsHiddenClosure(hidden)
+
+	fn.Nname = NewNameAt(pos, BlankNode.Sym())
+	fn.Nname.Func = fn
+	fn.Nname.Defn = fn
+
+	fn.OClosure = NewClosureExpr(pos, fn)
+
+	return fn
+}
+
+// NameClosure generates a unique for the given function literal,
+// which must have appeared within outerfn.
+func NameClosure(clo *ClosureExpr, outerfn *Func) {
+	fn := clo.Func
+	if fn.IsHiddenClosure() != (outerfn != nil) {
+		base.FatalfAt(clo.Pos(), "closure naming inconsistency: hidden %v, but outer %v", fn.IsHiddenClosure(), outerfn)
+	}
+
+	name := fn.Nname
+	if !IsBlank(name) {
+		base.FatalfAt(clo.Pos(), "closure already named: %v", name)
+	}
+
+	name.SetSym(closureName(outerfn))
+	MarkFunc(name)
+}
+
+// UseClosure checks that the ginen function literal has been setup
+// correctly, and then returns it as an expression.
+// It must be called after clo.Func.ClosureVars has been set.
+func UseClosure(clo *ClosureExpr, pkg *Package) Node {
+	fn := clo.Func
+	name := fn.Nname
+
+	if IsBlank(name) {
+		base.FatalfAt(fn.Pos(), "unnamed closure func: %v", fn)
+	}
+	// Caution: clo.Typecheck() is still 0 when UseClosure is called by
+	// tcClosure.
+	if fn.Typecheck() != 1 || name.Typecheck() != 1 {
+		base.FatalfAt(fn.Pos(), "missed typecheck: %v", fn)
+	}
+	if clo.Type() == nil || name.Type() == nil {
+		base.FatalfAt(fn.Pos(), "missing types: %v", fn)
+	}
+	if !types.Identical(clo.Type(), name.Type()) {
+		base.FatalfAt(fn.Pos(), "mismatched types: %v", fn)
+	}
+
+	if base.Flag.W > 1 {
+		s := fmt.Sprintf("new closure func: %v", fn)
+		Dump(s, fn)
+	}
+
+	if pkg != nil {
+		pkg.Decls = append(pkg.Decls, fn)
+	}
+
+	if false && IsTrivialClosure(clo) {
+		// TODO(mdempsky): Investigate if we can/should optimize this
+		// case. walkClosure already handles it later, but it could be
+		// useful to recognize earlier (e.g., it might allow multiple
+		// inlined calls to a function to share a common trivial closure
+		// func, rather than cloning it for each inlined call).
+	}
+
+	return clo
+}
diff --git a/src/cmd/compile/internal/ir/name.go b/src/cmd/compile/internal/ir/name.go
index b6c68bc..a2eec05 100644
--- a/src/cmd/compile/internal/ir/name.go
+++ b/src/cmd/compile/internal/ir/name.go
@@ -358,39 +358,74 @@
 	return n.Canonical().flags&nameByval != 0
 }
 
+// NewClosureVar returns a new closure variable for fn to refer to
+// outer variable n.
+func NewClosureVar(pos src.XPos, fn *Func, n *Name) *Name {
+	c := NewNameAt(pos, n.Sym())
+	c.Curfn = fn
+	c.Class = PAUTOHEAP
+	c.SetIsClosureVar(true)
+	c.Defn = n.Canonical()
+	c.Outer = n
+
+	c.SetType(n.Type())
+	c.SetTypecheck(n.Typecheck())
+
+	fn.ClosureVars = append(fn.ClosureVars, c)
+
+	return c
+}
+
+// NewHiddenParam returns a new hidden parameter for fn with the given
+// name and type.
+func NewHiddenParam(pos src.XPos, fn *Func, sym *types.Sym, typ *types.Type) *Name {
+	if fn.OClosure != nil {
+		base.FatalfAt(fn.Pos(), "cannot add hidden parameters to closures")
+	}
+
+	fn.SetNeedctxt(true)
+
+	// Create a fake parameter, disassociated from any real function, to
+	// pretend to capture.
+	fake := NewNameAt(pos, sym)
+	fake.Class = PPARAM
+	fake.SetType(typ)
+	fake.SetByval(true)
+
+	return NewClosureVar(pos, fn, fake)
+}
+
 // CaptureName returns a Name suitable for referring to n from within function
 // fn or from the package block if fn is nil. If n is a free variable declared
-// within a function that encloses fn, then CaptureName returns a closure
-// variable that refers to n and adds it to fn.ClosureVars. Otherwise, it simply
-// returns n.
+// within a function that encloses fn, then CaptureName returns the closure
+// variable that refers to n within fn, creating it if necessary.
+// Otherwise, it simply returns n.
 func CaptureName(pos src.XPos, fn *Func, n *Name) *Name {
+	if n.Op() != ONAME || n.Curfn == nil {
+		return n // okay to use directly
+	}
 	if n.IsClosureVar() {
 		base.FatalfAt(pos, "misuse of CaptureName on closure variable: %v", n)
 	}
-	if n.Op() != ONAME || n.Curfn == nil || n.Curfn == fn {
-		return n // okay to use directly
+
+	c := n.Innermost
+	if c == nil {
+		c = n
 	}
+	if c.Curfn == fn {
+		return c
+	}
+
 	if fn == nil {
 		base.FatalfAt(pos, "package-block reference to %v, declared in %v", n, n.Curfn)
 	}
 
-	c := n.Innermost
-	if c != nil && c.Curfn == fn {
-		return c
-	}
-
 	// Do not have a closure var for the active closure yet; make one.
-	c = NewNameAt(pos, n.Sym())
-	c.Curfn = fn
-	c.Class = PAUTOHEAP
-	c.SetIsClosureVar(true)
-	c.Defn = n
+	c = NewClosureVar(pos, fn, c)
 
 	// Link into list of active closure variables.
 	// Popped from list in FinishCaptureNames.
-	c.Outer = n.Innermost
 	n.Innermost = c
-	fn.ClosureVars = append(fn.ClosureVars, c)
 
 	return c
 }
diff --git a/src/cmd/compile/internal/ir/node.go b/src/cmd/compile/internal/ir/node.go
index af559cc..f071cb7 100644
--- a/src/cmd/compile/internal/ir/node.go
+++ b/src/cmd/compile/internal/ir/node.go
@@ -159,7 +159,6 @@
 	OCALLFUNC  // X(Args) (function call f(args))
 	OCALLMETH  // X(Args) (direct method call x.Method(args))
 	OCALLINTER // X(Args) (interface method call x.Method(args))
-	OCALLPART  // X.Sel (method expression x.Method, not called)
 	OCAP       // cap(X)
 	OCLOSE     // close(X)
 	OCLOSURE   // func Type { Func.Closure.Body } (func literal)
@@ -171,6 +170,7 @@
 	OPTRLIT    // &X (X is composite literal)
 	OCONV      // Type(X) (type conversion)
 	OCONVIFACE // Type(X) (type conversion, to interface)
+	OCONVIDATA // Builds a data word to store X in an interface. Equivalent to IDATA(CONVIFACE(X)). Is an ir.ConvExpr.
 	OCONVNOP   // Type(X) (type conversion, no effect)
 	OCOPY      // copy(X, Y)
 	ODCL       // var X (declares X of type X.Type)
@@ -237,6 +237,7 @@
 	OSLICE3ARR   // X[Low : High : Max] (X is pointer to array)
 	OSLICEHEADER // sliceheader{Ptr, Len, Cap} (Ptr is unsafe.Pointer, Len is length, Cap is capacity)
 	ORECOVER     // recover()
+	ORECOVERFP   // recover(Args) w/ explicit FP argument
 	ORECV        // <-X
 	ORUNESTR     // Type(X) (Type is string, X is rune)
 	OSELRECV2    // like OAS2: Lhs = Rhs where len(Lhs)=2, len(Rhs)=1, Rhs[0].Op = ORECV (appears as .Var of OCASE)
@@ -249,14 +250,16 @@
 	OSIZEOF      // unsafe.Sizeof(X)
 	OUNSAFEADD   // unsafe.Add(X, Y)
 	OUNSAFESLICE // unsafe.Slice(X, Y)
-	OMETHEXPR    // method expression
+	OMETHEXPR    // X(Args) (method expression T.Method(args), first argument is the method receiver)
+	OMETHVALUE   // X.Sel   (method expression t.Method, not called)
 
 	// statements
 	OBLOCK // { List } (block of code)
 	OBREAK // break [Label]
 	// OCASE:  case List: Body (List==nil means default)
 	//   For OTYPESW, List is a OTYPE node for the specified type (or OLITERAL
-	//   for nil), and, if a type-switch variable is specified, Rlist is an
+	//   for nil) or an ODYNAMICTYPE indicating a runtime type for generics.
+	//   If a type-switch variable is specified, Var is an
 	//   ONAME for the version of the type-switch variable with the specified
 	//   type.
 	OCASE
@@ -317,9 +320,16 @@
 	OINLMARK       // start of an inlined body, with file/line of caller. Xoffset is an index into the inline tree.
 	OLINKSYMOFFSET // offset within a name
 
+	// opcodes for generics
+	ODYNAMICDOTTYPE  // x = i.(T) where T is a type parameter (or derived from a type parameter)
+	ODYNAMICDOTTYPE2 // x, ok = i.(T) where T is a type parameter (or derived from a type parameter)
+	ODYNAMICTYPE     // a type node for type switches (represents a dynamic target type for a type switch)
+
 	// arch-specific opcodes
-	OTAILCALL // tail call to another function
-	OGETG     // runtime.getg() (read g pointer)
+	OTAILCALL    // tail call to another function
+	OGETG        // runtime.getg() (read g pointer)
+	OGETCALLERPC // runtime.getcallerpc() (continuation PC in caller frame)
+	OGETCALLERSP // runtime.getcallersp() (stack pointer in caller frame)
 
 	OEND
 )
@@ -436,18 +446,19 @@
 	return res
 }
 
-type PragmaFlag int16
+type PragmaFlag uint16
 
 const (
 	// Func pragmas.
-	Nointerface    PragmaFlag = 1 << iota
-	Noescape                  // func parameters don't escape
-	Norace                    // func must not have race detector annotations
-	Nosplit                   // func should not execute on separate stack
-	Noinline                  // func should not be inlined
-	NoCheckPtr                // func should not be instrumented by checkptr
-	CgoUnsafeArgs             // treat a pointer to one arg as a pointer to them all
-	UintptrEscapes            // pointers converted to uintptr escape
+	Nointerface      PragmaFlag = 1 << iota
+	Noescape                    // func parameters don't escape
+	Norace                      // func must not have race detector annotations
+	Nosplit                     // func should not execute on separate stack
+	Noinline                    // func should not be inlined
+	NoCheckPtr                  // func should not be instrumented by checkptr
+	CgoUnsafeArgs               // treat a pointer to one arg as a pointer to them all
+	UintptrKeepAlive            // pointers converted to uintptr must be kept alive (compiler internal only)
+	UintptrEscapes              // pointers converted to uintptr escape
 
 	// Runtime-only func pragmas.
 	// See ../../../../runtime/README.md for detailed descriptions.
@@ -563,7 +574,7 @@
 	for {
 		switch nn := n; nn.Op() {
 		case OXDOT:
-			base.Fatalf("OXDOT in walk")
+			base.FatalfAt(n.Pos(), "OXDOT in walk: %v", n)
 		case ODOT:
 			nn := nn.(*SelectorExpr)
 			n = nn.X
diff --git a/src/cmd/compile/internal/ir/node_gen.go b/src/cmd/compile/internal/ir/node_gen.go
index 22855d7..aa41c03 100644
--- a/src/cmd/compile/internal/ir/node_gen.go
+++ b/src/cmd/compile/internal/ir/node_gen.go
@@ -463,6 +463,62 @@
 	}
 }
 
+func (n *DynamicType) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
+func (n *DynamicType) copy() Node {
+	c := *n
+	c.init = copyNodes(c.init)
+	return &c
+}
+func (n *DynamicType) doChildren(do func(Node) bool) bool {
+	if doNodes(n.init, do) {
+		return true
+	}
+	if n.X != nil && do(n.X) {
+		return true
+	}
+	if n.ITab != nil && do(n.ITab) {
+		return true
+	}
+	return false
+}
+func (n *DynamicType) editChildren(edit func(Node) Node) {
+	editNodes(n.init, edit)
+	if n.X != nil {
+		n.X = edit(n.X).(Node)
+	}
+	if n.ITab != nil {
+		n.ITab = edit(n.ITab).(Node)
+	}
+}
+
+func (n *DynamicTypeAssertExpr) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
+func (n *DynamicTypeAssertExpr) copy() Node {
+	c := *n
+	c.init = copyNodes(c.init)
+	return &c
+}
+func (n *DynamicTypeAssertExpr) doChildren(do func(Node) bool) bool {
+	if doNodes(n.init, do) {
+		return true
+	}
+	if n.X != nil && do(n.X) {
+		return true
+	}
+	if n.T != nil && do(n.T) {
+		return true
+	}
+	return false
+}
+func (n *DynamicTypeAssertExpr) editChildren(edit func(Node) Node) {
+	editNodes(n.init, edit)
+	if n.X != nil {
+		n.X = edit(n.X).(Node)
+	}
+	if n.T != nil {
+		n.T = edit(n.T).(Node)
+	}
+}
+
 func (n *ForStmt) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
 func (n *ForStmt) copy() Node {
 	c := *n
@@ -947,6 +1003,22 @@
 	}
 }
 
+func (n *RawOrigExpr) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
+func (n *RawOrigExpr) copy() Node {
+	c := *n
+	c.init = copyNodes(c.init)
+	return &c
+}
+func (n *RawOrigExpr) doChildren(do func(Node) bool) bool {
+	if doNodes(n.init, do) {
+		return true
+	}
+	return false
+}
+func (n *RawOrigExpr) editChildren(edit func(Node) Node) {
+	editNodes(n.init, edit)
+}
+
 func (n *ResultExpr) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
 func (n *ResultExpr) copy() Node {
 	c := *n
diff --git a/src/cmd/compile/internal/ir/op_string.go b/src/cmd/compile/internal/ir/op_string.go
index 405a0c6..b8cee71 100644
--- a/src/cmd/compile/internal/ir/op_string.go
+++ b/src/cmd/compile/internal/ir/op_string.go
@@ -41,18 +41,18 @@
 	_ = x[OCALLFUNC-30]
 	_ = x[OCALLMETH-31]
 	_ = x[OCALLINTER-32]
-	_ = x[OCALLPART-33]
-	_ = x[OCAP-34]
-	_ = x[OCLOSE-35]
-	_ = x[OCLOSURE-36]
-	_ = x[OCOMPLIT-37]
-	_ = x[OMAPLIT-38]
-	_ = x[OSTRUCTLIT-39]
-	_ = x[OARRAYLIT-40]
-	_ = x[OSLICELIT-41]
-	_ = x[OPTRLIT-42]
-	_ = x[OCONV-43]
-	_ = x[OCONVIFACE-44]
+	_ = x[OCAP-33]
+	_ = x[OCLOSE-34]
+	_ = x[OCLOSURE-35]
+	_ = x[OCOMPLIT-36]
+	_ = x[OMAPLIT-37]
+	_ = x[OSTRUCTLIT-38]
+	_ = x[OARRAYLIT-39]
+	_ = x[OSLICELIT-40]
+	_ = x[OPTRLIT-41]
+	_ = x[OCONV-42]
+	_ = x[OCONVIFACE-43]
+	_ = x[OCONVIDATA-44]
 	_ = x[OCONVNOP-45]
 	_ = x[OCOPY-46]
 	_ = x[ODCL-47]
@@ -109,65 +109,72 @@
 	_ = x[OSLICE3ARR-98]
 	_ = x[OSLICEHEADER-99]
 	_ = x[ORECOVER-100]
-	_ = x[ORECV-101]
-	_ = x[ORUNESTR-102]
-	_ = x[OSELRECV2-103]
-	_ = x[OIOTA-104]
-	_ = x[OREAL-105]
-	_ = x[OIMAG-106]
-	_ = x[OCOMPLEX-107]
-	_ = x[OALIGNOF-108]
-	_ = x[OOFFSETOF-109]
-	_ = x[OSIZEOF-110]
-	_ = x[OUNSAFEADD-111]
-	_ = x[OUNSAFESLICE-112]
-	_ = x[OMETHEXPR-113]
-	_ = x[OBLOCK-114]
-	_ = x[OBREAK-115]
-	_ = x[OCASE-116]
-	_ = x[OCONTINUE-117]
-	_ = x[ODEFER-118]
-	_ = x[OFALL-119]
-	_ = x[OFOR-120]
-	_ = x[OFORUNTIL-121]
-	_ = x[OGOTO-122]
-	_ = x[OIF-123]
-	_ = x[OLABEL-124]
-	_ = x[OGO-125]
-	_ = x[ORANGE-126]
-	_ = x[ORETURN-127]
-	_ = x[OSELECT-128]
-	_ = x[OSWITCH-129]
-	_ = x[OTYPESW-130]
-	_ = x[OFUNCINST-131]
-	_ = x[OTCHAN-132]
-	_ = x[OTMAP-133]
-	_ = x[OTSTRUCT-134]
-	_ = x[OTINTER-135]
-	_ = x[OTFUNC-136]
-	_ = x[OTARRAY-137]
-	_ = x[OTSLICE-138]
-	_ = x[OINLCALL-139]
-	_ = x[OEFACE-140]
-	_ = x[OITAB-141]
-	_ = x[OIDATA-142]
-	_ = x[OSPTR-143]
-	_ = x[OCFUNC-144]
-	_ = x[OCHECKNIL-145]
-	_ = x[OVARDEF-146]
-	_ = x[OVARKILL-147]
-	_ = x[OVARLIVE-148]
-	_ = x[ORESULT-149]
-	_ = x[OINLMARK-150]
-	_ = x[OLINKSYMOFFSET-151]
-	_ = x[OTAILCALL-152]
-	_ = x[OGETG-153]
-	_ = x[OEND-154]
+	_ = x[ORECOVERFP-101]
+	_ = x[ORECV-102]
+	_ = x[ORUNESTR-103]
+	_ = x[OSELRECV2-104]
+	_ = x[OIOTA-105]
+	_ = x[OREAL-106]
+	_ = x[OIMAG-107]
+	_ = x[OCOMPLEX-108]
+	_ = x[OALIGNOF-109]
+	_ = x[OOFFSETOF-110]
+	_ = x[OSIZEOF-111]
+	_ = x[OUNSAFEADD-112]
+	_ = x[OUNSAFESLICE-113]
+	_ = x[OMETHEXPR-114]
+	_ = x[OMETHVALUE-115]
+	_ = x[OBLOCK-116]
+	_ = x[OBREAK-117]
+	_ = x[OCASE-118]
+	_ = x[OCONTINUE-119]
+	_ = x[ODEFER-120]
+	_ = x[OFALL-121]
+	_ = x[OFOR-122]
+	_ = x[OFORUNTIL-123]
+	_ = x[OGOTO-124]
+	_ = x[OIF-125]
+	_ = x[OLABEL-126]
+	_ = x[OGO-127]
+	_ = x[ORANGE-128]
+	_ = x[ORETURN-129]
+	_ = x[OSELECT-130]
+	_ = x[OSWITCH-131]
+	_ = x[OTYPESW-132]
+	_ = x[OFUNCINST-133]
+	_ = x[OTCHAN-134]
+	_ = x[OTMAP-135]
+	_ = x[OTSTRUCT-136]
+	_ = x[OTINTER-137]
+	_ = x[OTFUNC-138]
+	_ = x[OTARRAY-139]
+	_ = x[OTSLICE-140]
+	_ = x[OINLCALL-141]
+	_ = x[OEFACE-142]
+	_ = x[OITAB-143]
+	_ = x[OIDATA-144]
+	_ = x[OSPTR-145]
+	_ = x[OCFUNC-146]
+	_ = x[OCHECKNIL-147]
+	_ = x[OVARDEF-148]
+	_ = x[OVARKILL-149]
+	_ = x[OVARLIVE-150]
+	_ = x[ORESULT-151]
+	_ = x[OINLMARK-152]
+	_ = x[OLINKSYMOFFSET-153]
+	_ = x[ODYNAMICDOTTYPE-154]
+	_ = x[ODYNAMICDOTTYPE2-155]
+	_ = x[ODYNAMICTYPE-156]
+	_ = x[OTAILCALL-157]
+	_ = x[OGETG-158]
+	_ = x[OGETCALLERPC-159]
+	_ = x[OGETCALLERSP-160]
+	_ = x[OEND-161]
 }
 
-const _Op_name = "XXXNAMENONAMETYPEPACKLITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESSLICE2ARRPTRASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCALLPARTCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVNOPCOPYDCLDCLFUNCDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECVRUNESTRSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFUNSAFEADDUNSAFESLICEMETHEXPRBLOCKBREAKCASECONTINUEDEFERFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWFUNCINSTTCHANTMAPTSTRUCTTINTERTFUNCTARRAYTSLICEINLCALLEFACEITABIDATASPTRCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKLINKSYMOFFSETTAILCALLGETGEND"
+const _Op_name = "XXXNAMENONAMETYPEPACKLITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESSLICE2ARRPTRASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVIDATACONVNOPCOPYDCLDCLFUNCDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECOVERFPRECVRUNESTRSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFUNSAFEADDUNSAFESLICEMETHEXPRMETHVALUEBLOCKBREAKCASECONTINUEDEFERFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWFUNCINSTTCHANTMAPTSTRUCTTINTERTFUNCTARRAYTSLICEINLCALLEFACEITABIDATASPTRCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKLINKSYMOFFSETDYNAMICDOTTYPEDYNAMICDOTTYPE2DYNAMICTYPETAILCALLGETGGETCALLERPCGETCALLERSPEND"
 
-var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 37, 39, 42, 48, 52, 58, 64, 73, 85, 94, 103, 115, 124, 136, 138, 141, 151, 158, 165, 172, 176, 180, 188, 196, 205, 213, 216, 221, 228, 235, 241, 250, 258, 266, 272, 276, 285, 292, 296, 299, 306, 314, 321, 327, 330, 336, 343, 351, 355, 362, 370, 372, 374, 376, 378, 380, 382, 387, 392, 400, 403, 412, 415, 419, 427, 434, 443, 456, 459, 462, 465, 468, 471, 474, 480, 483, 486, 492, 496, 499, 503, 508, 513, 519, 524, 528, 533, 541, 549, 555, 564, 575, 582, 586, 593, 601, 605, 609, 613, 620, 627, 635, 641, 650, 661, 669, 674, 679, 683, 691, 696, 700, 703, 711, 715, 717, 722, 724, 729, 735, 741, 747, 753, 761, 766, 770, 777, 783, 788, 794, 800, 807, 812, 816, 821, 825, 830, 838, 844, 851, 858, 864, 871, 884, 892, 896, 899}
+var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 37, 39, 42, 48, 52, 58, 64, 73, 85, 94, 103, 115, 124, 136, 138, 141, 151, 158, 165, 172, 176, 180, 188, 196, 205, 208, 213, 220, 227, 233, 242, 250, 258, 264, 268, 277, 286, 293, 297, 300, 307, 315, 322, 328, 331, 337, 344, 352, 356, 363, 371, 373, 375, 377, 379, 381, 383, 388, 393, 401, 404, 413, 416, 420, 428, 435, 444, 457, 460, 463, 466, 469, 472, 475, 481, 484, 487, 493, 497, 500, 504, 509, 514, 520, 525, 529, 534, 542, 550, 556, 565, 576, 583, 592, 596, 603, 611, 615, 619, 623, 630, 637, 645, 651, 660, 671, 679, 688, 693, 698, 702, 710, 715, 719, 722, 730, 734, 736, 741, 743, 748, 754, 760, 766, 772, 780, 785, 789, 796, 802, 807, 813, 819, 826, 831, 835, 840, 844, 849, 857, 863, 870, 877, 883, 890, 903, 917, 932, 943, 951, 955, 966, 977, 980}
 
 func (i Op) String() string {
 	if i >= Op(len(_Op_index)-1) {
diff --git a/src/cmd/compile/internal/ir/package.go b/src/cmd/compile/internal/ir/package.go
index e4b93d1..3896e2b 100644
--- a/src/cmd/compile/internal/ir/package.go
+++ b/src/cmd/compile/internal/ir/package.go
@@ -32,7 +32,4 @@
 
 	// Exported (or re-exported) symbols.
 	Exports []*Name
-
-	// Map from function names of stencils to already-created stencils.
-	Stencils map[*types.Sym]*Func
 }
diff --git a/src/cmd/compile/internal/ir/scc.go b/src/cmd/compile/internal/ir/scc.go
index 83c6074..2cfceaa 100644
--- a/src/cmd/compile/internal/ir/scc.go
+++ b/src/cmd/compile/internal/ir/scc.go
@@ -90,7 +90,7 @@
 			if n := n.(*Name); n.Class == PFUNC {
 				do(n.Defn)
 			}
-		case ODOTMETH, OCALLPART, OMETHEXPR:
+		case ODOTMETH, OMETHVALUE, OMETHEXPR:
 			if fn := MethodExprName(n); fn != nil {
 				do(fn.Defn)
 			}
diff --git a/src/cmd/compile/internal/ir/type.go b/src/cmd/compile/internal/ir/type.go
index a903ea8..63dd673 100644
--- a/src/cmd/compile/internal/ir/type.go
+++ b/src/cmd/compile/internal/ir/type.go
@@ -300,11 +300,36 @@
 
 // TypeNode returns the Node representing the type t.
 func TypeNode(t *types.Type) Ntype {
+	return TypeNodeAt(src.NoXPos, t)
+}
+
+// TypeNodeAt is like TypeNode, but allows specifying the position
+// information if a new OTYPE needs to be constructed.
+//
+// Deprecated: Use TypeNode instead. For typical use, the position for
+// an anonymous OTYPE node should not matter. However, TypeNodeAt is
+// available for use with toolstash -cmp to refactor existing code
+// that is sensitive to OTYPE position.
+func TypeNodeAt(pos src.XPos, t *types.Type) Ntype {
 	if n := t.Obj(); n != nil {
 		if n.Type() != t {
 			base.Fatalf("type skew: %v has type %v, but expected %v", n, n.Type(), t)
 		}
 		return n.(Ntype)
 	}
-	return newTypeNode(src.NoXPos, t)
+	return newTypeNode(pos, t)
+}
+
+// A DynamicType represents the target type in a type switch.
+type DynamicType struct {
+	miniExpr
+	X    Node // a *runtime._type for the targeted type
+	ITab Node // for type switches from nonempty interfaces to non-interfaces, this is the itab for that pair.
+}
+
+func NewDynamicType(pos src.XPos, x Node) *DynamicType {
+	n := &DynamicType{X: x}
+	n.pos = pos
+	n.op = ODYNAMICTYPE
+	return n
 }
diff --git a/src/cmd/compile/internal/ir/val.go b/src/cmd/compile/internal/ir/val.go
index 03c320e..bfe7d2b 100644
--- a/src/cmd/compile/internal/ir/val.go
+++ b/src/cmd/compile/internal/ir/val.go
@@ -66,7 +66,7 @@
 
 func AssertValidTypeForConst(t *types.Type, v constant.Value) {
 	if !ValidTypeForConst(t, v) {
-		base.Fatalf("%v does not represent %v", t, v)
+		base.Fatalf("%v (%v) does not represent %v (%v)", t, t.Kind(), v, v.Kind())
 	}
 }
 
diff --git a/src/cmd/compile/internal/liveness/plive.go b/src/cmd/compile/internal/liveness/plive.go
index f5c2ef7..2705eac 100644
--- a/src/cmd/compile/internal/liveness/plive.go
+++ b/src/cmd/compile/internal/liveness/plive.go
@@ -1082,6 +1082,10 @@
 	if base.Flag.Live == 0 || ir.FuncName(lv.fn) == "init" || strings.HasPrefix(ir.FuncName(lv.fn), ".") {
 		return
 	}
+	if lv.fn.Wrapper() || lv.fn.Dupok() {
+		// Skip reporting liveness information for compiler-generated wrappers.
+		return
+	}
 	if !(v == nil || v.Op.IsCall()) {
 		// Historically we only printed this information at
 		// calls. Keep doing so.
diff --git a/src/cmd/compile/internal/logopt/logopt_test.go b/src/cmd/compile/internal/logopt/logopt_test.go
index 7197617..902cbc8 100644
--- a/src/cmd/compile/internal/logopt/logopt_test.go
+++ b/src/cmd/compile/internal/logopt/logopt_test.go
@@ -209,7 +209,7 @@
 		want(t, slogged, `{"range":{"start":{"line":11,"character":6},"end":{"line":11,"character":6}},"severity":3,"code":"isInBounds","source":"go compiler","message":""}`)
 		want(t, slogged, `{"range":{"start":{"line":7,"character":6},"end":{"line":7,"character":6}},"severity":3,"code":"canInlineFunction","source":"go compiler","message":"cost: 35"}`)
 		// escape analysis explanation
-		want(t, slogged, `{"range":{"start":{"line":7,"character":13},"end":{"line":7,"character":13}},"severity":3,"code":"leak","source":"go compiler","message":"parameter z leaks to ~r2 with derefs=0",`+
+		want(t, slogged, `{"range":{"start":{"line":7,"character":13},"end":{"line":7,"character":13}},"severity":3,"code":"leak","source":"go compiler","message":"parameter z leaks to ~r0 with derefs=0",`+
 			`"relatedInformation":[`+
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow:    flow: y = z:"},`+
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow:      from y := z (assign-pair)"},`+
@@ -220,8 +220,8 @@
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow:      from \u0026y.b (address-of)"},`+
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":4,"character":9},"end":{"line":4,"character":9}}},"message":"inlineLoc"},`+
 			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":13},"end":{"line":9,"character":13}}},"message":"escflow:      from ~R0 = \u0026y.b (assign-pair)"},`+
-			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow:    flow: ~r2 = ~R0:"},`+
-			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow:      from return (*int)(~R0) (return)"}]}`)
+			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow:    flow: ~r0 = ~R0:"},`+
+			`{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":9,"character":3},"end":{"line":9,"character":3}}},"message":"escflow:      from return ~R0 (return)"}]}`)
 	})
 }
 
diff --git a/src/cmd/compile/internal/mips/galign.go b/src/cmd/compile/internal/mips/galign.go
index f892923..4e68970 100644
--- a/src/cmd/compile/internal/mips/galign.go
+++ b/src/cmd/compile/internal/mips/galign.go
@@ -21,7 +21,6 @@
 	arch.SoftFloat = (buildcfg.GOMIPS == "softfloat")
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock
diff --git a/src/cmd/compile/internal/mips64/galign.go b/src/cmd/compile/internal/mips64/galign.go
index af81366..412bc71 100644
--- a/src/cmd/compile/internal/mips64/galign.go
+++ b/src/cmd/compile/internal/mips64/galign.go
@@ -21,7 +21,6 @@
 	arch.SoftFloat = buildcfg.GOMIPS64 == "softfloat"
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/noder/codes.go b/src/cmd/compile/internal/noder/codes.go
new file mode 100644
index 0000000..f8cb772
--- /dev/null
+++ b/src/cmd/compile/internal/noder/codes.go
@@ -0,0 +1,124 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+type code interface {
+	marker() syncMarker
+	value() int
+}
+
+type codeVal int
+
+func (c codeVal) marker() syncMarker { return syncVal }
+func (c codeVal) value() int         { return int(c) }
+
+const (
+	valBool codeVal = iota
+	valString
+	valInt64
+	valBigInt
+	valBigRat
+	valBigFloat
+)
+
+type codeType int
+
+func (c codeType) marker() syncMarker { return syncType }
+func (c codeType) value() int         { return int(c) }
+
+const (
+	typeBasic codeType = iota
+	typeNamed
+	typePointer
+	typeSlice
+	typeArray
+	typeChan
+	typeMap
+	typeSignature
+	typeStruct
+	typeInterface
+	typeUnion
+	typeTypeParam
+)
+
+type codeObj int
+
+func (c codeObj) marker() syncMarker { return syncCodeObj }
+func (c codeObj) value() int         { return int(c) }
+
+const (
+	objAlias codeObj = iota
+	objConst
+	objType
+	objFunc
+	objVar
+	objStub
+)
+
+type codeStmt int
+
+func (c codeStmt) marker() syncMarker { return syncStmt1 }
+func (c codeStmt) value() int         { return int(c) }
+
+const (
+	stmtEnd codeStmt = iota
+	stmtLabel
+	stmtBlock
+	stmtExpr
+	stmtSend
+	stmtAssign
+	stmtAssignOp
+	stmtIncDec
+	stmtBranch
+	stmtCall
+	stmtReturn
+	stmtIf
+	stmtFor
+	stmtSwitch
+	stmtSelect
+
+	// TODO(mdempsky): Remove after we don't care about toolstash -cmp.
+	stmtTypeDeclHack
+)
+
+type codeExpr int
+
+func (c codeExpr) marker() syncMarker { return syncExpr }
+func (c codeExpr) value() int         { return int(c) }
+
+// TODO(mdempsky): Split expr into addr, for lvalues.
+const (
+	exprNone codeExpr = iota
+	exprConst
+	exprType  // type expression
+	exprLocal // local variable
+	exprName  // global variable or function
+	exprBlank
+	exprCompLit
+	exprFuncLit
+	exprSelector
+	exprIndex
+	exprSlice
+	exprAssert
+	exprUnaryOp
+	exprBinaryOp
+	exprCall
+	exprConvert
+)
+
+type codeDecl int
+
+func (c codeDecl) marker() syncMarker { return syncDecl }
+func (c codeDecl) value() int         { return int(c) }
+
+const (
+	declEnd codeDecl = iota
+	declFunc
+	declMethod
+	declVar
+	declOther
+)
diff --git a/src/cmd/compile/internal/noder/decl.go b/src/cmd/compile/internal/noder/decl.go
index 4ca2eb4..429c8a1 100644
--- a/src/cmd/compile/internal/noder/decl.go
+++ b/src/cmd/compile/internal/noder/decl.go
@@ -41,20 +41,27 @@
 }
 
 func (g *irgen) importDecl(p *noder, decl *syntax.ImportDecl) {
-	// TODO(mdempsky): Merge with gcimports so we don't have to import
-	// packages twice.
-
 	g.pragmaFlags(decl.Pragma, 0)
 
-	ipkg := importfile(decl)
-	if ipkg == ir.Pkgs.Unsafe {
+	// Get the imported package's path, as resolved already by types2
+	// and gcimporter. This is the same path as would be computed by
+	// parseImportPath.
+	switch pkgNameOf(g.info, decl).Imported().Path() {
+	case "unsafe":
 		p.importedUnsafe = true
-	}
-	if ipkg.Path == "embed" {
+	case "embed":
 		p.importedEmbed = true
 	}
 }
 
+// pkgNameOf returns the PkgName associated with the given ImportDecl.
+func pkgNameOf(info *types2.Info, decl *syntax.ImportDecl) *types2.PkgName {
+	if name := decl.LocalPkgName; name != nil {
+		return info.Defs[name].(*types2.PkgName)
+	}
+	return info.Implicits[decl].(*types2.PkgName)
+}
+
 func (g *irgen) constDecl(out *ir.Nodes, decl *syntax.ConstDecl) {
 	g.pragmaFlags(decl.Pragma, 0)
 
@@ -95,7 +102,21 @@
 		g.target.Inits = append(g.target.Inits, fn)
 	}
 
+	if fn.Type().HasTParam() {
+		g.topFuncIsGeneric = true
+	}
 	g.funcBody(fn, decl.Recv, decl.Type, decl.Body)
+	g.topFuncIsGeneric = false
+	if fn.Type().HasTParam() && fn.Body != nil {
+		// Set pointers to the dcls/body of a generic function/method in
+		// the Inl struct, so it is marked for export, is available for
+		// stenciling, and works with Inline_Flood().
+		fn.Inl = &ir.Inline{
+			Cost: 1,
+			Dcl:  fn.Dcl,
+			Body: fn.Body,
+		}
+	}
 
 	out.Append(fn)
 }
@@ -104,13 +125,7 @@
 	if decl.Alias {
 		name, _ := g.def(decl.Name)
 		g.pragmaFlags(decl.Pragma, 0)
-
-		// TODO(mdempsky): This matches how typecheckdef marks aliases for
-		// export, but this won't generalize to exporting function-scoped
-		// type aliases. We should maybe just use n.Alias() instead.
-		if ir.CurFunc == nil {
-			name.Sym().Def = ir.TypeNode(name.Type())
-		}
+		assert(name.Alias()) // should be set by irgen.obj
 
 		out.Append(ir.NewDecl(g.pos(decl), ir.ODCLTYPE, name))
 		return
@@ -154,11 +169,15 @@
 	// [mdempsky: Subtleties like these are why I always vehemently
 	// object to new type pragmas.]
 	ntyp.SetUnderlying(g.typeExpr(decl.Type))
-	if len(decl.TParamList) > 0 {
-		// Set HasTParam if there are any tparams, even if no tparams are
-		// used in the type itself (e.g., if it is an empty struct, or no
-		// fields in the struct use the tparam).
-		ntyp.SetHasTParam(true)
+
+	tparams := otyp.(*types2.Named).TParams()
+	if n := tparams.Len(); n > 0 {
+		rparams := make([]*types.Type, n)
+		for i := range rparams {
+			rparams[i] = g.typ(tparams.At(i).Type())
+		}
+		// This will set hasTParam flag if any rparams are not concrete types.
+		ntyp.SetRParams(rparams)
 	}
 	types.ResumeCheckSize()
 
diff --git a/src/cmd/compile/internal/noder/decoder.go b/src/cmd/compile/internal/noder/decoder.go
new file mode 100644
index 0000000..3dc61c6
--- /dev/null
+++ b/src/cmd/compile/internal/noder/decoder.go
@@ -0,0 +1,301 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"math/big"
+	"os"
+	"runtime"
+	"strings"
+
+	"cmd/compile/internal/base"
+)
+
+type pkgDecoder struct {
+	pkgPath string
+
+	elemEndsEnds [numRelocs]uint32
+	elemEnds     []uint32
+	elemData     string
+}
+
+func newPkgDecoder(pkgPath, input string) pkgDecoder {
+	pr := pkgDecoder{
+		pkgPath: pkgPath,
+	}
+
+	// TODO(mdempsky): Implement direct indexing of input string to
+	// avoid copying the position information.
+
+	r := strings.NewReader(input)
+
+	assert(binary.Read(r, binary.LittleEndian, pr.elemEndsEnds[:]) == nil)
+
+	pr.elemEnds = make([]uint32, pr.elemEndsEnds[len(pr.elemEndsEnds)-1])
+	assert(binary.Read(r, binary.LittleEndian, pr.elemEnds[:]) == nil)
+
+	pos, err := r.Seek(0, os.SEEK_CUR)
+	assert(err == nil)
+
+	pr.elemData = input[pos:]
+	assert(len(pr.elemData) == int(pr.elemEnds[len(pr.elemEnds)-1]))
+
+	return pr
+}
+
+func (pr *pkgDecoder) numElems(k reloc) int {
+	count := int(pr.elemEndsEnds[k])
+	if k > 0 {
+		count -= int(pr.elemEndsEnds[k-1])
+	}
+	return count
+}
+
+func (pr *pkgDecoder) totalElems() int {
+	return len(pr.elemEnds)
+}
+
+func (pr *pkgDecoder) absIdx(k reloc, idx int) int {
+	absIdx := idx
+	if k > 0 {
+		absIdx += int(pr.elemEndsEnds[k-1])
+	}
+	if absIdx >= int(pr.elemEndsEnds[k]) {
+		base.Fatalf("%v:%v is out of bounds; %v", k, idx, pr.elemEndsEnds)
+	}
+	return absIdx
+}
+
+func (pr *pkgDecoder) dataIdx(k reloc, idx int) string {
+	absIdx := pr.absIdx(k, idx)
+
+	var start uint32
+	if absIdx > 0 {
+		start = pr.elemEnds[absIdx-1]
+	}
+	end := pr.elemEnds[absIdx]
+
+	return pr.elemData[start:end]
+}
+
+func (pr *pkgDecoder) stringIdx(idx int) string {
+	return pr.dataIdx(relocString, idx)
+}
+
+func (pr *pkgDecoder) newDecoder(k reloc, idx int, marker syncMarker) decoder {
+	r := pr.newDecoderRaw(k, idx)
+	r.sync(marker)
+	return r
+}
+
+func (pr *pkgDecoder) newDecoderRaw(k reloc, idx int) decoder {
+	r := decoder{
+		common: pr,
+		k:      k,
+		idx:    idx,
+	}
+
+	// TODO(mdempsky) r.data.Reset(...) after #44505 is resolved.
+	r.data = *strings.NewReader(pr.dataIdx(k, idx))
+
+	r.sync(syncRelocs)
+	r.relocs = make([]relocEnt, r.len())
+	for i := range r.relocs {
+		r.sync(syncReloc)
+		r.relocs[i] = relocEnt{reloc(r.len()), r.len()}
+	}
+
+	return r
+}
+
+type decoder struct {
+	common *pkgDecoder
+
+	relocs []relocEnt
+	data   strings.Reader
+
+	k   reloc
+	idx int
+}
+
+func (r *decoder) checkErr(err error) {
+	if err != nil {
+		base.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func (r *decoder) rawUvarint() uint64 {
+	x, err := binary.ReadUvarint(&r.data)
+	r.checkErr(err)
+	return x
+}
+
+func (r *decoder) rawVarint() int64 {
+	ux := r.rawUvarint()
+
+	// Zig-zag decode.
+	x := int64(ux >> 1)
+	if ux&1 != 0 {
+		x = ^x
+	}
+	return x
+}
+
+func (r *decoder) rawReloc(k reloc, idx int) int {
+	e := r.relocs[idx]
+	assert(e.kind == k)
+	return e.idx
+}
+
+func (r *decoder) sync(mWant syncMarker) {
+	if !enableSync {
+		return
+	}
+
+	pos, _ := r.data.Seek(0, os.SEEK_CUR) // TODO(mdempsky): io.SeekCurrent after #44505 is resolved
+	mHave := syncMarker(r.rawUvarint())
+	writerPCs := make([]int, r.rawUvarint())
+	for i := range writerPCs {
+		writerPCs[i] = int(r.rawUvarint())
+	}
+
+	if mHave == mWant {
+		return
+	}
+
+	// There's some tension here between printing:
+	//
+	// (1) full file paths that tools can recognize (e.g., so emacs
+	//     hyperlinks the "file:line" text for easy navigation), or
+	//
+	// (2) short file paths that are easier for humans to read (e.g., by
+	//     omitting redundant or irrelevant details, so it's easier to
+	//     focus on the useful bits that remain).
+	//
+	// The current formatting favors the former, as it seems more
+	// helpful in practice. But perhaps the formatting could be improved
+	// to better address both concerns. For example, use relative file
+	// paths if they would be shorter, or rewrite file paths to contain
+	// "$GOROOT" (like objabi.AbsFile does) if tools can be taught how
+	// to reliably expand that again.
+
+	fmt.Printf("export data desync: package %q, section %v, index %v, offset %v\n", r.common.pkgPath, r.k, r.idx, pos)
+
+	fmt.Printf("\nfound %v, written at:\n", mHave)
+	if len(writerPCs) == 0 {
+		fmt.Printf("\t[stack trace unavailable; recompile package %q with -d=syncframes]\n", r.common.pkgPath)
+	}
+	for _, pc := range writerPCs {
+		fmt.Printf("\t%s\n", r.common.stringIdx(r.rawReloc(relocString, pc)))
+	}
+
+	fmt.Printf("\nexpected %v, reading at:\n", mWant)
+	var readerPCs [32]uintptr // TODO(mdempsky): Dynamically size?
+	n := runtime.Callers(2, readerPCs[:])
+	for _, pc := range fmtFrames(readerPCs[:n]...) {
+		fmt.Printf("\t%s\n", pc)
+	}
+
+	// We already printed a stack trace for the reader, so now we can
+	// simply exit. Printing a second one with panic or base.Fatalf
+	// would just be noise.
+	os.Exit(1)
+}
+
+func (r *decoder) bool() bool {
+	r.sync(syncBool)
+	x, err := r.data.ReadByte()
+	r.checkErr(err)
+	assert(x < 2)
+	return x != 0
+}
+
+func (r *decoder) int64() int64 {
+	r.sync(syncInt64)
+	return r.rawVarint()
+}
+
+func (r *decoder) uint64() uint64 {
+	r.sync(syncUint64)
+	return r.rawUvarint()
+}
+
+func (r *decoder) len() int   { x := r.uint64(); v := int(x); assert(uint64(v) == x); return v }
+func (r *decoder) int() int   { x := r.int64(); v := int(x); assert(int64(v) == x); return v }
+func (r *decoder) uint() uint { x := r.uint64(); v := uint(x); assert(uint64(v) == x); return v }
+
+func (r *decoder) code(mark syncMarker) int {
+	r.sync(mark)
+	return r.len()
+}
+
+func (r *decoder) reloc(k reloc) int {
+	r.sync(syncUseReloc)
+	return r.rawReloc(k, r.len())
+}
+
+func (r *decoder) string() string {
+	r.sync(syncString)
+	return r.common.stringIdx(r.reloc(relocString))
+}
+
+func (r *decoder) strings() []string {
+	res := make([]string, r.len())
+	for i := range res {
+		res[i] = r.string()
+	}
+	return res
+}
+
+func (r *decoder) rawValue() constant.Value {
+	isComplex := r.bool()
+	val := r.scalar()
+	if isComplex {
+		val = constant.BinaryOp(val, token.ADD, constant.MakeImag(r.scalar()))
+	}
+	return val
+}
+
+func (r *decoder) scalar() constant.Value {
+	switch tag := codeVal(r.code(syncVal)); tag {
+	default:
+		panic(fmt.Sprintf("unexpected scalar tag: %v", tag))
+
+	case valBool:
+		return constant.MakeBool(r.bool())
+	case valString:
+		return constant.MakeString(r.string())
+	case valInt64:
+		return constant.MakeInt64(r.int64())
+	case valBigInt:
+		return constant.Make(r.bigInt())
+	case valBigRat:
+		num := r.bigInt()
+		denom := r.bigInt()
+		return constant.Make(new(big.Rat).SetFrac(num, denom))
+	case valBigFloat:
+		return constant.Make(r.bigFloat())
+	}
+}
+
+func (r *decoder) bigInt() *big.Int {
+	v := new(big.Int).SetBytes([]byte(r.string()))
+	if r.bool() {
+		v.Neg(v)
+	}
+	return v
+}
+
+func (r *decoder) bigFloat() *big.Float {
+	v := new(big.Float).SetPrec(512)
+	assert(v.UnmarshalText([]byte(r.string())) == nil)
+	return v
+}
diff --git a/src/cmd/compile/internal/noder/encoder.go b/src/cmd/compile/internal/noder/encoder.go
new file mode 100644
index 0000000..d8ab0f6
--- /dev/null
+++ b/src/cmd/compile/internal/noder/encoder.go
@@ -0,0 +1,284 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"io"
+	"math/big"
+	"runtime"
+
+	"cmd/compile/internal/base"
+)
+
+type pkgEncoder struct {
+	elems [numRelocs][]string
+
+	stringsIdx map[string]int
+}
+
+func newPkgEncoder() pkgEncoder {
+	return pkgEncoder{
+		stringsIdx: make(map[string]int),
+	}
+}
+
+func (pw *pkgEncoder) dump(out io.Writer) {
+	writeUint32 := func(x uint32) {
+		assert(binary.Write(out, binary.LittleEndian, x) == nil)
+	}
+
+	var sum uint32
+	for _, elems := range &pw.elems {
+		sum += uint32(len(elems))
+		writeUint32(sum)
+	}
+
+	sum = 0
+	for _, elems := range &pw.elems {
+		for _, elem := range elems {
+			sum += uint32(len(elem))
+			writeUint32(sum)
+		}
+	}
+
+	for _, elems := range &pw.elems {
+		for _, elem := range elems {
+			_, err := io.WriteString(out, elem)
+			assert(err == nil)
+		}
+	}
+}
+
+func (pw *pkgEncoder) stringIdx(s string) int {
+	if idx, ok := pw.stringsIdx[s]; ok {
+		assert(pw.elems[relocString][idx] == s)
+		return idx
+	}
+
+	idx := len(pw.elems[relocString])
+	pw.elems[relocString] = append(pw.elems[relocString], s)
+	pw.stringsIdx[s] = idx
+	return idx
+}
+
+func (pw *pkgEncoder) newEncoder(k reloc, marker syncMarker) encoder {
+	e := pw.newEncoderRaw(k)
+	e.sync(marker)
+	return e
+}
+
+func (pw *pkgEncoder) newEncoderRaw(k reloc) encoder {
+	idx := len(pw.elems[k])
+	pw.elems[k] = append(pw.elems[k], "") // placeholder
+
+	return encoder{
+		p:   pw,
+		k:   k,
+		idx: idx,
+	}
+}
+
+// Encoders
+
+type encoder struct {
+	p *pkgEncoder
+
+	relocs []relocEnt
+	data   bytes.Buffer
+
+	encodingRelocHeader bool
+
+	k   reloc
+	idx int
+}
+
+func (w *encoder) flush() int {
+	var sb bytes.Buffer // TODO(mdempsky): strings.Builder after #44505 is resolved
+
+	// Backup the data so we write the relocations at the front.
+	var tmp bytes.Buffer
+	io.Copy(&tmp, &w.data)
+
+	// TODO(mdempsky): Consider writing these out separately so they're
+	// easier to strip, along with function bodies, so that we can prune
+	// down to just the data that's relevant to go/types.
+	if w.encodingRelocHeader {
+		base.Fatalf("encodingRelocHeader already true; recursive flush?")
+	}
+	w.encodingRelocHeader = true
+	w.sync(syncRelocs)
+	w.len(len(w.relocs))
+	for _, rent := range w.relocs {
+		w.sync(syncReloc)
+		w.len(int(rent.kind))
+		w.len(rent.idx)
+	}
+
+	io.Copy(&sb, &w.data)
+	io.Copy(&sb, &tmp)
+	w.p.elems[w.k][w.idx] = sb.String()
+
+	return w.idx
+}
+
+func (w *encoder) checkErr(err error) {
+	if err != nil {
+		base.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func (w *encoder) rawUvarint(x uint64) {
+	var buf [binary.MaxVarintLen64]byte
+	n := binary.PutUvarint(buf[:], x)
+	_, err := w.data.Write(buf[:n])
+	w.checkErr(err)
+}
+
+func (w *encoder) rawVarint(x int64) {
+	// Zig-zag encode.
+	ux := uint64(x) << 1
+	if x < 0 {
+		ux = ^ux
+	}
+
+	w.rawUvarint(ux)
+}
+
+func (w *encoder) rawReloc(r reloc, idx int) int {
+	// TODO(mdempsky): Use map for lookup.
+	for i, rent := range w.relocs {
+		if rent.kind == r && rent.idx == idx {
+			return i
+		}
+	}
+
+	i := len(w.relocs)
+	w.relocs = append(w.relocs, relocEnt{r, idx})
+	return i
+}
+
+func (w *encoder) sync(m syncMarker) {
+	if !enableSync {
+		return
+	}
+
+	// Writing out stack frame string references requires working
+	// relocations, but writing out the relocations themselves involves
+	// sync markers. To prevent infinite recursion, we simply trim the
+	// stack frame for sync markers within the relocation header.
+	var frames []string
+	if !w.encodingRelocHeader && base.Debug.SyncFrames > 0 {
+		pcs := make([]uintptr, base.Debug.SyncFrames)
+		n := runtime.Callers(2, pcs)
+		frames = fmtFrames(pcs[:n]...)
+	}
+
+	// TODO(mdempsky): Save space by writing out stack frames as a
+	// linked list so we can share common stack frames.
+	w.rawUvarint(uint64(m))
+	w.rawUvarint(uint64(len(frames)))
+	for _, frame := range frames {
+		w.rawUvarint(uint64(w.rawReloc(relocString, w.p.stringIdx(frame))))
+	}
+}
+
+func (w *encoder) bool(b bool) bool {
+	w.sync(syncBool)
+	var x byte
+	if b {
+		x = 1
+	}
+	err := w.data.WriteByte(x)
+	w.checkErr(err)
+	return b
+}
+
+func (w *encoder) int64(x int64) {
+	w.sync(syncInt64)
+	w.rawVarint(x)
+}
+
+func (w *encoder) uint64(x uint64) {
+	w.sync(syncUint64)
+	w.rawUvarint(x)
+}
+
+func (w *encoder) len(x int)   { assert(x >= 0); w.uint64(uint64(x)) }
+func (w *encoder) int(x int)   { w.int64(int64(x)) }
+func (w *encoder) uint(x uint) { w.uint64(uint64(x)) }
+
+func (w *encoder) reloc(r reloc, idx int) {
+	w.sync(syncUseReloc)
+	w.len(w.rawReloc(r, idx))
+}
+
+func (w *encoder) code(c code) {
+	w.sync(c.marker())
+	w.len(c.value())
+}
+
+func (w *encoder) string(s string) {
+	w.sync(syncString)
+	w.reloc(relocString, w.p.stringIdx(s))
+}
+
+func (w *encoder) strings(ss []string) {
+	w.len(len(ss))
+	for _, s := range ss {
+		w.string(s)
+	}
+}
+
+func (w *encoder) rawValue(val constant.Value) {
+	if w.bool(val.Kind() == constant.Complex) {
+		w.scalar(constant.Real(val))
+		w.scalar(constant.Imag(val))
+	} else {
+		w.scalar(val)
+	}
+}
+
+func (w *encoder) scalar(val constant.Value) {
+	switch v := constant.Val(val).(type) {
+	default:
+		panic(fmt.Sprintf("unhandled %v (%v)", val, val.Kind()))
+	case bool:
+		w.code(valBool)
+		w.bool(v)
+	case string:
+		w.code(valString)
+		w.string(v)
+	case int64:
+		w.code(valInt64)
+		w.int64(v)
+	case *big.Int:
+		w.code(valBigInt)
+		w.bigInt(v)
+	case *big.Rat:
+		w.code(valBigRat)
+		w.bigInt(v.Num())
+		w.bigInt(v.Denom())
+	case *big.Float:
+		w.code(valBigFloat)
+		w.bigFloat(v)
+	}
+}
+
+func (w *encoder) bigInt(v *big.Int) {
+	b := v.Bytes()
+	w.string(string(b)) // TODO: More efficient encoding.
+	w.bool(v.Sign() < 0)
+}
+
+func (w *encoder) bigFloat(v *big.Float) {
+	b := v.Append(nil, 'p', -1)
+	w.string(string(b)) // TODO: More efficient encoding.
+}
diff --git a/src/cmd/compile/internal/noder/export.go b/src/cmd/compile/internal/noder/export.go
new file mode 100644
index 0000000..1a296e2
--- /dev/null
+++ b/src/cmd/compile/internal/noder/export.go
@@ -0,0 +1,65 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/typecheck"
+	"cmd/internal/bio"
+)
+
+// writeNewExportFunc is a hook that can be added to append extra
+// export data after the normal export data section. It allows
+// experimenting with new export data format designs without requiring
+// immediate support in the go/internal or x/tools importers.
+var writeNewExportFunc func(out io.Writer)
+
+func WriteExports(out *bio.Writer) {
+	// When unified IR exports are enable, we simply append it to the
+	// end of the normal export data (with compiler extensions
+	// disabled), and write an extra header giving its size.
+	//
+	// If the compiler sees this header, it knows to read the new data
+	// instead; meanwhile the go/types importers will silently ignore it
+	// and continue processing the old export instead.
+	//
+	// This allows us to experiment with changes to the new export data
+	// format without needing to update the go/internal/gcimporter or
+	// (worse) x/tools/go/gcexportdata.
+
+	useNewExport := writeNewExportFunc != nil
+
+	var old, new bytes.Buffer
+
+	typecheck.WriteExports(&old, !useNewExport)
+
+	if useNewExport {
+		writeNewExportFunc(&new)
+	}
+
+	oldLen := old.Len()
+	newLen := new.Len()
+
+	if useNewExport {
+		fmt.Fprintf(out, "\nnewexportsize %v\n", newLen)
+	}
+
+	// The linker also looks for the $$ marker - use char after $$ to distinguish format.
+	out.WriteString("\n$$B\n") // indicate binary export format
+	io.Copy(out, &old)
+	out.WriteString("\n$$\n")
+	io.Copy(out, &new)
+
+	if base.Debug.Export != 0 {
+		fmt.Printf("BenchmarkExportSize:%s 1 %d bytes\n", base.Ctxt.Pkgpath, oldLen)
+		if useNewExport {
+			fmt.Printf("BenchmarkNewExportSize:%s 1 %d bytes\n", base.Ctxt.Pkgpath, newLen)
+		}
+	}
+}
diff --git a/src/cmd/compile/internal/noder/expr.go b/src/cmd/compile/internal/noder/expr.go
index c7695ed..3e3c352 100644
--- a/src/cmd/compile/internal/noder/expr.go
+++ b/src/cmd/compile/internal/noder/expr.go
@@ -5,6 +5,8 @@
 package noder
 
 import (
+	"fmt"
+
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/syntax"
@@ -15,6 +17,8 @@
 )
 
 func (g *irgen) expr(expr syntax.Expr) ir.Node {
+	expr = unparen(expr) // skip parens; unneeded after parse+typecheck
+
 	if expr == nil {
 		return nil
 	}
@@ -67,14 +71,16 @@
 
 	// Constant expression.
 	if tv.Value != nil {
-		return Const(g.pos(expr), g.typ(typ), tv.Value)
+		typ := g.typ(typ)
+		value := FixValue(typ, tv.Value)
+		return OrigConst(g.pos(expr), typ, value, constExprOp(expr), syntax.String(expr))
 	}
 
 	n := g.expr0(typ, expr)
 	if n.Typecheck() != 1 && n.Typecheck() != 3 {
 		base.FatalfAt(g.pos(expr), "missed typecheck: %+v", n)
 	}
-	if !g.match(n.Type(), typ, tv.HasOk()) {
+	if n.Op() != ir.OFUNCINST && !g.match(n.Type(), typ, tv.HasOk()) {
 		base.FatalfAt(g.pos(expr), "expected %L to have type %v", n, typ)
 	}
 	return n
@@ -82,6 +88,11 @@
 
 func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
 	pos := g.pos(expr)
+	assert(pos.IsKnown())
+
+	// Set base.Pos for transformation code that still uses base.Pos, rather than
+	// the pos of the node being converted.
+	base.Pos = pos
 
 	switch expr := expr.(type) {
 	case *syntax.Name:
@@ -105,23 +116,30 @@
 		// The key for the Inferred map is the CallExpr (if inferring
 		// types required the function arguments) or the IndexExpr below
 		// (if types could be inferred without the function arguments).
-		if inferred, ok := g.info.Inferred[expr]; ok && len(inferred.Targs) > 0 {
+		if inferred, ok := g.info.Inferred[expr]; ok && len(inferred.TArgs) > 0 {
 			// This is the case where inferring types required the
 			// types of the function arguments.
-			targs := make([]ir.Node, len(inferred.Targs))
-			for i, targ := range inferred.Targs {
+			targs := make([]ir.Node, len(inferred.TArgs))
+			for i, targ := range inferred.TArgs {
 				targs[i] = ir.TypeNode(g.typ(targ))
 			}
 			if fun.Op() == ir.OFUNCINST {
 				// Replace explicit type args with the full list that
-				// includes the additional inferred type args
+				// includes the additional inferred type args.
+				// Substitute the type args for the type params in
+				// the generic function's type.
 				fun.(*ir.InstExpr).Targs = targs
+				newt := g.substType(fun.Type(), fun.Type().TParams(), targs)
+				typed(newt, fun)
 			} else {
-				// Create a function instantiation here, given
-				// there are only inferred type args (e.g.
-				// min(5,6), where min is a generic function)
+				// Create a function instantiation here, given there
+				// are only inferred type args (e.g. min(5,6), where
+				// min is a generic function). Substitute the type
+				// args for the type params in the generic function's
+				// type.
 				inst := ir.NewInstExpr(pos, ir.OFUNCINST, fun, targs)
-				typed(fun.Type(), inst)
+				newt := g.substType(fun.Type(), fun.Type().TParams(), targs)
+				typed(newt, inst)
 				fun = inst
 			}
 
@@ -131,12 +149,12 @@
 	case *syntax.IndexExpr:
 		var targs []ir.Node
 
-		if inferred, ok := g.info.Inferred[expr]; ok && len(inferred.Targs) > 0 {
+		if inferred, ok := g.info.Inferred[expr]; ok && len(inferred.TArgs) > 0 {
 			// This is the partial type inference case where the types
 			// can be inferred from other type arguments without using
 			// the types of the function arguments.
-			targs = make([]ir.Node, len(inferred.Targs))
-			for i, targ := range inferred.Targs {
+			targs = make([]ir.Node, len(inferred.TArgs))
+			for i, targ := range inferred.TArgs {
 				targs[i] = ir.TypeNode(g.typ(targ))
 			}
 		} else if _, ok := expr.Index.(*syntax.ListExpr); ok {
@@ -158,12 +176,16 @@
 			panic("Incorrect argument for generic func instantiation")
 		}
 		n := ir.NewInstExpr(pos, ir.OFUNCINST, x, targs)
-		typed(g.typ(typ), n)
+		newt := g.typ(typ)
+		// Substitute the type args for the type params in the uninstantiated
+		// function's type. If there aren't enough type args, then the rest
+		// will be inferred at the call node, so don't try the substitution yet.
+		if x.Type().TParams().NumFields() == len(targs) {
+			newt = g.substType(g.typ(typ), x.Type().TParams(), targs)
+		}
+		typed(newt, n)
 		return n
 
-	case *syntax.ParenExpr:
-		return g.expr(expr.X) // skip parens; unneeded after parse+typecheck
-
 	case *syntax.SelectorExpr:
 		// Qualified identifier.
 		if name, ok := expr.X.(*syntax.Name); ok {
@@ -193,7 +215,29 @@
 	}
 }
 
-// selectorExpr resolves the choice of ODOT, ODOTPTR, OCALLPART (eventually
+// substType does a normal type substition, but tparams is in the form of a field
+// list, and targs is in terms of a slice of type nodes. substType records any newly
+// instantiated types into g.instTypeList.
+func (g *irgen) substType(typ *types.Type, tparams *types.Type, targs []ir.Node) *types.Type {
+	fields := tparams.FieldSlice()
+	tparams1 := make([]*types.Type, len(fields))
+	for i, f := range fields {
+		tparams1[i] = f.Type
+	}
+	targs1 := make([]*types.Type, len(targs))
+	for i, n := range targs {
+		targs1[i] = n.Type()
+	}
+	ts := typecheck.Tsubster{
+		Tparams: tparams1,
+		Targs:   targs1,
+	}
+	newt := ts.Typ(typ)
+	g.instTypeList = append(g.instTypeList, ts.InstTypeList...)
+	return newt
+}
+
+// selectorExpr resolves the choice of ODOT, ODOTPTR, OMETHVALUE (eventually
 // ODOTMETH & ODOTINTER), and OMETHEXPR and deals with embedded fields here rather
 // than in typecheck.go.
 func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.SelectorExpr) ir.Node {
@@ -203,6 +247,44 @@
 		// only be fully transformed once it has an instantiated type.
 		n := ir.NewSelectorExpr(pos, ir.OXDOT, x, typecheck.Lookup(expr.Sel.Value))
 		typed(g.typ(typ), n)
+
+		// Fill in n.Selection for a generic method reference or a bound
+		// interface method, even though we won't use it directly, since it
+		// is useful for analysis. Specifically do not fill in for fields or
+		// other interfaces methods (method call on an interface value), so
+		// n.Selection being non-nil means a method reference for a generic
+		// type or a method reference due to a bound.
+		obj2 := g.info.Selections[expr].Obj()
+		sig := types2.AsSignature(obj2.Type())
+		if sig == nil || sig.Recv() == nil {
+			return n
+		}
+		index := g.info.Selections[expr].Index()
+		last := index[len(index)-1]
+		// recvType is the receiver of the method being called.  Because of the
+		// way methods are imported, g.obj(obj2) doesn't work across
+		// packages, so we have to lookup the method via the receiver type.
+		recvType := deref2(sig.Recv().Type())
+		if types2.AsInterface(recvType.Underlying()) != nil {
+			fieldType := n.X.Type()
+			for _, ix := range index[:len(index)-1] {
+				fieldType = fieldType.Field(ix).Type
+			}
+			if fieldType.Kind() == types.TTYPEPARAM {
+				n.Selection = fieldType.Bound().AllMethods().Index(last)
+				//fmt.Printf(">>>>> %v: Bound call %v\n", base.FmtPos(pos), n.Sel)
+			} else {
+				assert(fieldType.Kind() == types.TINTER)
+				//fmt.Printf(">>>>> %v: Interface call %v\n", base.FmtPos(pos), n.Sel)
+			}
+			return n
+		}
+
+		recvObj := types2.AsNamed(recvType).Obj()
+		recv := g.pkg(recvObj.Pkg()).Lookup(recvObj.Name()).Def
+		n.Selection = recv.Type().Methods().Index(last)
+		//fmt.Printf(">>>>> %v: Method call %v\n", base.FmtPos(pos), n.Sel)
+
 		return n
 	}
 
@@ -259,14 +341,18 @@
 			if wantPtr {
 				recvType2Base = types2.AsPointer(recvType2).Elem()
 			}
-			if len(types2.AsNamed(recvType2Base).TParams()) > 0 {
+			if types2.AsNamed(recvType2Base).TParams().Len() > 0 {
 				// recvType2 is the original generic type that is
 				// instantiated for this method call.
 				// selinfo.Recv() is the instantiated type
 				recvType2 = recvType2Base
-				// method is the generic method associated with the gen type
-				method := g.obj(types2.AsNamed(recvType2).Method(last))
-				n = ir.NewSelectorExpr(pos, ir.OCALLPART, x, method.Sym())
+				recvTypeSym := g.pkg(method2.Pkg()).Lookup(recvType2.(*types2.Named).Obj().Name())
+				recvType := recvTypeSym.Def.(*ir.Name).Type()
+				// method is the generic method associated with
+				// the base generic type. The instantiated type may not
+				// have method bodies filled in, if it was imported.
+				method := recvType.Methods().Index(last).Nname.(*ir.Name)
+				n = ir.NewSelectorExpr(pos, ir.OMETHVALUE, x, typecheck.Lookup(expr.Sel.Value))
 				n.(*ir.SelectorExpr).Selection = types.NewField(pos, method.Sym(), method.Type())
 				n.(*ir.SelectorExpr).Selection.Nname = method
 				typed(method.Type(), n)
@@ -301,10 +387,7 @@
 
 // getTargs gets the targs associated with the receiver of a selected method
 func getTargs(selinfo *types2.Selection) []types2.Type {
-	r := selinfo.Recv()
-	if p := types2.AsPointer(r); p != nil {
-		r = p.Elem()
-	}
+	r := deref2(selinfo.Recv())
 	n := types2.AsNamed(r)
 	if n == nil {
 		base.Fatalf("Incorrect type for selinfo %v", selinfo)
@@ -313,13 +396,17 @@
 }
 
 func (g *irgen) exprList(expr syntax.Expr) []ir.Node {
+	return g.exprs(unpackListExpr(expr))
+}
+
+func unpackListExpr(expr syntax.Expr) []syntax.Expr {
 	switch expr := expr.(type) {
 	case nil:
 		return nil
 	case *syntax.ListExpr:
-		return g.exprs(expr.ElemList)
+		return expr.ElemList
 	default:
-		return []ir.Node{g.expr(expr)}
+		return []syntax.Expr{expr}
 	}
 }
 
@@ -344,11 +431,13 @@
 	for i, elem := range lit.ElemList {
 		switch elem := elem.(type) {
 		case *syntax.KeyValueExpr:
+			var key ir.Node
 			if isStruct {
-				exprs[i] = ir.NewStructKeyExpr(g.pos(elem), g.name(elem.Key.(*syntax.Name)), g.expr(elem.Value))
+				key = ir.NewIdent(g.pos(elem.Key), g.name(elem.Key.(*syntax.Name)))
 			} else {
-				exprs[i] = ir.NewKeyExpr(g.pos(elem), g.expr(elem.Key), g.expr(elem.Value))
+				key = g.expr(elem.Key)
 			}
+			exprs[i] = ir.NewKeyExpr(g.pos(elem), key, g.expr(elem.Value))
 		default:
 			exprs[i] = g.expr(elem)
 		}
@@ -360,19 +449,13 @@
 }
 
 func (g *irgen) funcLit(typ2 types2.Type, expr *syntax.FuncLit) ir.Node {
-	fn := ir.NewFunc(g.pos(expr))
-	fn.SetIsHiddenClosure(ir.CurFunc != nil)
+	fn := ir.NewClosureFunc(g.pos(expr), ir.CurFunc != nil)
+	ir.NameClosure(fn.OClosure, ir.CurFunc)
 
-	fn.Nname = ir.NewNameAt(g.pos(expr), typecheck.ClosureName(ir.CurFunc))
-	ir.MarkFunc(fn.Nname)
 	typ := g.typ(typ2)
-	fn.Nname.Func = fn
-	fn.Nname.Defn = fn
 	typed(typ, fn.Nname)
-	fn.SetTypecheck(1)
-
-	fn.OClosure = ir.NewClosureExpr(g.pos(expr), fn)
 	typed(typ, fn.OClosure)
+	fn.SetTypecheck(1)
 
 	g.funcBody(fn, nil, expr.Type, expr.Body)
 
@@ -386,9 +469,14 @@
 		cv.SetWalkdef(1)
 	}
 
-	g.target.Decls = append(g.target.Decls, fn)
-
-	return fn.OClosure
+	if g.topFuncIsGeneric {
+		// Don't add any closure inside a generic function/method to the
+		// g.target.Decls list, even though it may not be generic itself.
+		// See issue #47514.
+		return ir.UseClosure(fn.OClosure, nil)
+	} else {
+		return ir.UseClosure(fn.OClosure, g.target)
+	}
 }
 
 func (g *irgen) typeExpr(typ syntax.Expr) *types.Type {
@@ -398,3 +486,35 @@
 	}
 	return n.Type()
 }
+
+// constExprOp returns an ir.Op that represents the outermost
+// operation of the given constant expression. It's intended for use
+// with ir.RawOrigExpr.
+func constExprOp(expr syntax.Expr) ir.Op {
+	switch expr := expr.(type) {
+	default:
+		panic(fmt.Sprintf("%s: unexpected expression: %T", expr.Pos(), expr))
+
+	case *syntax.BasicLit:
+		return ir.OLITERAL
+	case *syntax.Name, *syntax.SelectorExpr:
+		return ir.ONAME
+	case *syntax.CallExpr:
+		return ir.OCALL
+	case *syntax.Operation:
+		if expr.Y == nil {
+			return unOps[expr.Op]
+		}
+		return binOps[expr.Op]
+	}
+}
+
+func unparen(expr syntax.Expr) syntax.Expr {
+	for {
+		paren, ok := expr.(*syntax.ParenExpr)
+		if !ok {
+			return expr
+		}
+		expr = paren.X
+	}
+}
diff --git a/src/cmd/compile/internal/noder/frames_go1.go b/src/cmd/compile/internal/noder/frames_go1.go
new file mode 100644
index 0000000..2958efd
--- /dev/null
+++ b/src/cmd/compile/internal/noder/frames_go1.go
@@ -0,0 +1,20 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !go1.7
+
+// TODO(mdempsky): Remove after #44505 is resolved
+
+package noder
+
+import "runtime"
+
+func walkFrames(pcs []uintptr, visit frameVisitor) {
+	for _, pc := range pcs {
+		fn := runtime.FuncForPC(pc)
+		file, line := fn.FileLine(pc)
+
+		visit(file, line, fn.Name(), pc-fn.Entry())
+	}
+}
diff --git a/src/cmd/compile/internal/noder/frames_go17.go b/src/cmd/compile/internal/noder/frames_go17.go
new file mode 100644
index 0000000..273217e
--- /dev/null
+++ b/src/cmd/compile/internal/noder/frames_go17.go
@@ -0,0 +1,24 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.7
+
+package noder
+
+import "runtime"
+
+func walkFrames(pcs []uintptr, visit frameVisitor) {
+	if len(pcs) == 0 {
+		return
+	}
+
+	frames := runtime.CallersFrames(pcs)
+	for {
+		frame, more := frames.Next()
+		visit(frame.File, frame.Line, frame.Function, frame.PC-frame.Entry)
+		if !more {
+			return
+		}
+	}
+}
diff --git a/src/cmd/compile/internal/noder/helpers.go b/src/cmd/compile/internal/noder/helpers.go
index 9da0e49..b9dbd03 100644
--- a/src/cmd/compile/internal/noder/helpers.go
+++ b/src/cmd/compile/internal/noder/helpers.go
@@ -43,6 +43,32 @@
 	return typed(typ, ir.NewBasicLit(pos, val))
 }
 
+func OrigConst(pos src.XPos, typ *types.Type, val constant.Value, op ir.Op, raw string) ir.Node {
+	orig := ir.NewRawOrigExpr(pos, op, raw)
+	return ir.NewConstExpr(val, typed(typ, orig))
+}
+
+// FixValue returns val after converting and truncating it as
+// appropriate for typ.
+func FixValue(typ *types.Type, val constant.Value) constant.Value {
+	assert(typ.Kind() != types.TFORW)
+	switch {
+	case typ.IsInteger():
+		val = constant.ToInt(val)
+	case typ.IsFloat():
+		val = constant.ToFloat(val)
+	case typ.IsComplex():
+		val = constant.ToComplex(val)
+	}
+	if !typ.IsUntyped() {
+		val = typecheck.DefaultLit(ir.NewBasicLit(src.NoXPos, val), typ).Val()
+	}
+	if !typ.IsTypeParam() {
+		ir.AssertValidTypeForConst(typ, val)
+	}
+	return val
+}
+
 func Nil(pos src.XPos, typ *types.Type) ir.Node {
 	return typed(typ, ir.NewNilExpr(pos))
 }
@@ -87,15 +113,15 @@
 func Call(pos src.XPos, typ *types.Type, fun ir.Node, args []ir.Node, dots bool) ir.Node {
 	n := ir.NewCallExpr(pos, ir.OCALL, fun, args)
 	n.IsDDD = dots
-	// n.Use will be changed to ir.CallUseStmt in g.stmt() if this call is
-	// just a statement (any return values are ignored).
-	n.Use = ir.CallUseExpr
 
 	if fun.Op() == ir.OTYPE {
 		// Actually a type conversion, not a function call.
-		if fun.Type().HasTParam() || args[0].Type().HasTParam() {
-			// For type params, don't typecheck until we actually know
-			// the type.
+		if !fun.Type().IsInterface() &&
+			(fun.Type().HasTParam() || args[0].Type().HasTParam()) {
+			// For type params, we can transform if fun.Type() is known
+			// to be an interface (in which case a CONVIFACE node will be
+			// inserted). Otherwise, don't typecheck until we actually
+			// know the type.
 			return typed(typ, n)
 		}
 		typed(typ, n)
@@ -103,22 +129,17 @@
 	}
 
 	if fun, ok := fun.(*ir.Name); ok && fun.BuiltinOp != 0 {
-		// For Builtin ops, we currently stay with using the old
-		// typechecker to transform the call to a more specific expression
-		// and possibly use more specific ops. However, for a bunch of the
-		// ops, we delay doing the old typechecker if any of the args have
-		// type params, for a variety of reasons:
+		// For most Builtin ops, we delay doing transformBuiltin if any of the
+		// args have type params, for a variety of reasons:
 		//
-		// OMAKE: hard to choose specific ops OMAKESLICE, etc. until arg type is known
-		// OREAL/OIMAG: can't determine type float32/float64 until arg type know
-		// OLEN/OCAP: old typechecker will complain if arg is not obviously a slice/array.
-		// OAPPEND: old typechecker will complain if arg is not obviously slice, etc.
-		//
-		// We will eventually break out the transforming functionality
-		// needed for builtin's, and call it here or during stenciling, as
-		// appropriate.
+		// OMAKE: transformMake can't choose specific ops OMAKESLICE, etc.
+		//    until arg type is known
+		// OREAL/OIMAG: transformRealImag can't determine type float32/float64
+		//    until arg type known
+		// OAPPEND: transformAppend requires that the arg is a slice
+		// ODELETE: transformDelete requires that the arg is a map
 		switch fun.BuiltinOp {
-		case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OLEN, ir.OCAP, ir.OAPPEND:
+		case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.ODELETE:
 			hasTParam := false
 			for _, arg := range args {
 				if arg.Type().HasTParam() {
@@ -137,10 +158,8 @@
 
 	// Add information, now that we know that fun is actually being called.
 	switch fun := fun.(type) {
-	case *ir.ClosureExpr:
-		fun.Func.SetClosureCalled(true)
 	case *ir.SelectorExpr:
-		if fun.Op() == ir.OCALLPART {
+		if fun.Op() == ir.OMETHVALUE {
 			op := ir.ODOTMETH
 			if fun.X.Type().IsInterface() {
 				op = ir.ODOTINTER
@@ -152,46 +171,52 @@
 		}
 	}
 
-	if fun.Type().HasTParam() {
-		// If the fun arg is or has a type param, don't do any extra
+	if fun.Type().HasTParam() || fun.Op() == ir.OXDOT || fun.Op() == ir.OFUNCINST {
+		// If the fun arg is or has a type param, we can't do all the
 		// transformations, since we may not have needed properties yet
-		// (e.g. number of return values, etc). The type param is probably
-		// described by a structural constraint that requires it to be a
-		// certain function type, etc., but we don't want to analyze that.
+		// (e.g. number of return values, etc). The same applies if a fun
+		// which is an XDOT could not be transformed yet because of a generic
+		// type in the X of the selector expression.
+		//
+		// A function instantiation (even if fully concrete) shouldn't be
+		// transformed yet, because we need to add the dictionary during the
+		// transformation.
+		//
+		// However, if we have a function type (even though it is
+		// parameterized), then we can add in any needed CONVIFACE nodes via
+		// typecheckaste(). We need to call transformArgs() to deal first
+		// with the f(g(()) case where g returns multiple return values. We
+		// can't do anything if fun is a type param (which is probably
+		// described by a structural constraint)
+		if fun.Type().Kind() == types.TFUNC {
+			transformArgs(n)
+			typecheckaste(ir.OCALL, fun, n.IsDDD, fun.Type().Params(), n.Args, true)
+		}
 		return typed(typ, n)
 	}
 
-	if fun.Op() == ir.OXDOT {
-		if !fun.(*ir.SelectorExpr).X.Type().HasTParam() {
-			base.FatalfAt(pos, "Expecting type param receiver in %v", fun)
-		}
-		// For methods called in a generic function, don't do any extra
-		// transformations. We will do those later when we create the
-		// instantiated function and have the correct receiver type.
-		typed(typ, n)
-		return n
-	}
-	if fun.Op() != ir.OFUNCINST {
-		// If no type params, do the normal call transformations. This
-		// will convert OCALL to OCALLFUNC.
-		typed(typ, n)
-		transformCall(n)
-		return n
-	}
-
-	// Leave the op as OCALL, which indicates the call still needs typechecking.
+	// If no type params, do the normal call transformations. This
+	// will convert OCALL to OCALLFUNC.
 	typed(typ, n)
+	transformCall(n)
 	return n
 }
 
 func Compare(pos src.XPos, typ *types.Type, op ir.Op, x, y ir.Node) ir.Node {
 	n := ir.NewBinaryExpr(pos, op, x, y)
 	if x.Type().HasTParam() || y.Type().HasTParam() {
-		// Delay transformCompare() if either arg has a type param, since
-		// it needs to know the exact types to decide on any needed conversions.
-		n.SetType(typ)
-		n.SetTypecheck(3)
-		return n
+		xIsInt := x.Type().IsInterface()
+		yIsInt := y.Type().IsInterface()
+		if !(xIsInt && !yIsInt || !xIsInt && yIsInt) {
+			// If either arg is a type param, then we can still do the
+			// transformCompare() if we know that one arg is an interface
+			// and the other is not. Otherwise, we delay
+			// transformCompare(), since it needs to know the exact types
+			// to decide on any needed conversions.
+			n.SetType(typ)
+			n.SetTypecheck(3)
+			return n
+		}
 	}
 	typed(typ, n)
 	transformCompare(n)
@@ -225,7 +250,7 @@
 
 	// Method value.
 	typ := typecheck.NewMethodType(method.Type, nil)
-	return dot(pos, typ, ir.OCALLPART, x, method)
+	return dot(pos, typ, ir.OMETHVALUE, x, method)
 }
 
 // MethodExpr returns a OMETHEXPR node with the indicated index into the methods
@@ -321,5 +346,15 @@
 
 func IncDec(pos src.XPos, op ir.Op, x ir.Node) *ir.AssignOpStmt {
 	assert(x.Type() != nil)
-	return ir.NewAssignOpStmt(pos, op, x, typecheck.DefaultLit(ir.NewBasicLit(pos, one), x.Type()))
+	bl := ir.NewBasicLit(pos, one)
+	if x.Type().HasTParam() {
+		// If the operand is generic, then types2 will have proved it must be
+		// a type that fits with increment/decrement, so just set the type of
+		// "one" to n.Type(). This works even for types that are eventually
+		// float or complex.
+		typed(x.Type(), bl)
+	} else {
+		bl = typecheck.DefaultLit(bl, x.Type())
+	}
+	return ir.NewAssignOpStmt(pos, op, x, bl)
 }
diff --git a/src/cmd/compile/internal/noder/import.go b/src/cmd/compile/internal/noder/import.go
index 701e900..48f0e48 100644
--- a/src/cmd/compile/internal/noder/import.go
+++ b/src/cmd/compile/internal/noder/import.go
@@ -8,7 +8,6 @@
 	"errors"
 	"fmt"
 	"internal/buildcfg"
-	"io"
 	"os"
 	pathpkg "path"
 	"runtime"
@@ -32,8 +31,24 @@
 	"cmd/internal/src"
 )
 
-// Temporary import helper to get type2-based type-checking going.
+// haveLegacyImports records whether we've imported any packages
+// without a new export data section. This is useful for experimenting
+// with new export data format designs, when you need to support
+// existing tests that manually compile files with inconsistent
+// compiler flags.
+var haveLegacyImports = false
+
+// newReadImportFunc is an extension hook for experimenting with new
+// export data formats. If a new export data payload was written out
+// for an imported package by overloading writeNewExportFunc, then
+// that payload will be mapped into memory and passed to
+// newReadImportFunc.
+var newReadImportFunc = func(data string, pkg1 *types.Pkg, check *types2.Checker, packages map[string]*types2.Package) (pkg2 *types2.Package, err error) {
+	panic("unexpected new export data payload")
+}
+
 type gcimports struct {
+	check    *types2.Checker
 	packages map[string]*types2.Package
 }
 
@@ -46,13 +61,8 @@
 		panic("mode must be 0")
 	}
 
-	path, err := resolveImportPath(path)
-	if err != nil {
-		return nil, err
-	}
-
-	lookup := func(path string) (io.ReadCloser, error) { return openPackage(path) }
-	return importer.Import(m.packages, path, srcDir, lookup)
+	_, pkg, err := readImportFile(path, typecheck.Target, m.check, m.packages)
+	return pkg, err
 }
 
 func isDriveLetter(b byte) bool {
@@ -175,160 +185,242 @@
 	return path, nil
 }
 
-// TODO(mdempsky): Return an error instead.
 func importfile(decl *syntax.ImportDecl) *types.Pkg {
-	if decl.Path.Kind != syntax.StringLit {
-		base.Errorf("import path must be a string")
-		return nil
-	}
-
-	path, err := strconv.Unquote(decl.Path.Value)
-	if err != nil {
-		base.Errorf("import path must be a string")
-		return nil
-	}
-
-	if err := checkImportPath(path, false); err != nil {
-		base.Errorf("%s", err.Error())
-		return nil
-	}
-
-	path, err = resolveImportPath(path)
+	path, err := parseImportPath(decl.Path)
 	if err != nil {
 		base.Errorf("%s", err)
 		return nil
 	}
 
-	importpkg := types.NewPkg(path, "")
-	if importpkg.Direct {
-		return importpkg // already fully loaded
+	pkg, _, err := readImportFile(path, typecheck.Target, nil, nil)
+	if err != nil {
+		base.Errorf("%s", err)
+		return nil
 	}
-	importpkg.Direct = true
-	typecheck.Target.Imports = append(typecheck.Target.Imports, importpkg)
+
+	if pkg != ir.Pkgs.Unsafe && pkg.Height >= myheight {
+		myheight = pkg.Height + 1
+	}
+	return pkg
+}
+
+func parseImportPath(pathLit *syntax.BasicLit) (string, error) {
+	if pathLit.Kind != syntax.StringLit {
+		return "", errors.New("import path must be a string")
+	}
+
+	path, err := strconv.Unquote(pathLit.Value)
+	if err != nil {
+		return "", errors.New("import path must be a string")
+	}
+
+	if err := checkImportPath(path, false); err != nil {
+		return "", err
+	}
+
+	return path, err
+}
+
+// readImportFile reads the import file for the given package path and
+// returns its types.Pkg representation. If packages is non-nil, the
+// types2.Package representation is also returned.
+func readImportFile(path string, target *ir.Package, check *types2.Checker, packages map[string]*types2.Package) (pkg1 *types.Pkg, pkg2 *types2.Package, err error) {
+	path, err = resolveImportPath(path)
+	if err != nil {
+		return
+	}
 
 	if path == "unsafe" {
-		return importpkg // initialized with universe
+		pkg1, pkg2 = ir.Pkgs.Unsafe, types2.Unsafe
+
+		// TODO(mdempsky): Investigate if this actually matters. Why would
+		// the linker or runtime care whether a package imported unsafe?
+		if !pkg1.Direct {
+			pkg1.Direct = true
+			target.Imports = append(target.Imports, pkg1)
+		}
+
+		return
 	}
 
+	pkg1 = types.NewPkg(path, "")
+	if packages != nil {
+		pkg2 = packages[path]
+		assert(pkg1.Direct == (pkg2 != nil && pkg2.Complete()))
+	}
+
+	if pkg1.Direct {
+		return
+	}
+	pkg1.Direct = true
+	target.Imports = append(target.Imports, pkg1)
+
 	f, err := openPackage(path)
 	if err != nil {
-		base.Errorf("could not import %q: %v", path, err)
-		base.ErrorExit()
+		return
 	}
-	imp := bio.NewReader(f)
-	defer imp.Close()
-	file := f.Name()
+	defer f.Close()
 
-	// check object header
-	p, err := imp.ReadString('\n')
+	r, end, newsize, err := findExportData(f)
 	if err != nil {
-		base.Errorf("import %s: reading input: %v", file, err)
-		base.ErrorExit()
+		return
 	}
 
-	if p == "!<arch>\n" { // package archive
-		// package export block should be first
-		sz := archive.ReadHeader(imp.Reader, "__.PKGDEF")
-		if sz <= 0 {
-			base.Errorf("import %s: not a package file", file)
-			base.ErrorExit()
-		}
-		p, err = imp.ReadString('\n')
+	if base.Debug.Export != 0 {
+		fmt.Printf("importing %s (%s)\n", path, f.Name())
+	}
+
+	if newsize != 0 {
+		// We have unified IR data. Map it, and feed to the importers.
+		end -= newsize
+		var data string
+		data, err = base.MapFile(r.File(), end, newsize)
 		if err != nil {
-			base.Errorf("import %s: reading input: %v", file, err)
-			base.ErrorExit()
+			return
 		}
-	}
 
-	if !strings.HasPrefix(p, "go object ") {
-		base.Errorf("import %s: not a go object file: %s", file, p)
-		base.ErrorExit()
-	}
-	q := objabi.HeaderString()
-	if p != q {
-		base.Errorf("import %s: object is [%s] expected [%s]", file, p, q)
-		base.ErrorExit()
-	}
+		pkg2, err = newReadImportFunc(data, pkg1, check, packages)
+	} else {
+		// We only have old data. Oh well, fall back to the legacy importers.
+		haveLegacyImports = true
 
-	// process header lines
-	for {
-		p, err = imp.ReadString('\n')
+		var c byte
+		switch c, err = r.ReadByte(); {
+		case err != nil:
+			return
+
+		case c != 'i':
+			// Indexed format is distinguished by an 'i' byte,
+			// whereas previous export formats started with 'c', 'd', or 'v'.
+			err = fmt.Errorf("unexpected package format byte: %v", c)
+			return
+		}
+
+		pos := r.Offset()
+
+		// Map string (and data) section into memory as a single large
+		// string. This reduces heap fragmentation and allows
+		// returning individual substrings very efficiently.
+		var data string
+		data, err = base.MapFile(r.File(), pos, end-pos)
 		if err != nil {
-			base.Errorf("import %s: reading input: %v", file, err)
-			base.ErrorExit()
+			return
 		}
-		if p == "\n" {
-			break // header ends with blank line
-		}
-	}
 
-	// Expect $$B\n to signal binary import format.
+		typecheck.ReadImports(pkg1, data)
 
-	// look for $$
-	var c byte
-	for {
-		c, err = imp.ReadByte()
-		if err != nil {
-			break
-		}
-		if c == '$' {
-			c, err = imp.ReadByte()
-			if c == '$' || err != nil {
-				break
+		if packages != nil {
+			pkg2, err = importer.ImportData(packages, data, path)
+			if err != nil {
+				return
 			}
 		}
 	}
 
-	// get character after $$
-	if err == nil {
-		c, _ = imp.ReadByte()
+	err = addFingerprint(path, f, end)
+	return
+}
+
+// findExportData returns a *bio.Reader positioned at the start of the
+// binary export data section, and a file offset for where to stop
+// reading.
+func findExportData(f *os.File) (r *bio.Reader, end, newsize int64, err error) {
+	r = bio.NewReader(f)
+
+	// check object header
+	line, err := r.ReadString('\n')
+	if err != nil {
+		return
 	}
 
-	var fingerprint goobj.FingerprintType
-	switch c {
-	case '\n':
-		base.Errorf("cannot import %s: old export format no longer supported (recompile library)", path)
-		return nil
-
-	case 'B':
-		if base.Debug.Export != 0 {
-			fmt.Printf("importing %s (%s)\n", path, file)
+	if line == "!<arch>\n" { // package archive
+		// package export block should be first
+		sz := int64(archive.ReadHeader(r.Reader, "__.PKGDEF"))
+		if sz <= 0 {
+			err = errors.New("not a package file")
+			return
 		}
-		imp.ReadByte() // skip \n after $$B
-
-		c, err = imp.ReadByte()
+		end = r.Offset() + sz
+		line, err = r.ReadString('\n')
 		if err != nil {
-			base.Errorf("import %s: reading input: %v", file, err)
-			base.ErrorExit()
+			return
 		}
-
-		// Indexed format is distinguished by an 'i' byte,
-		// whereas previous export formats started with 'c', 'd', or 'v'.
-		if c != 'i' {
-			base.Errorf("import %s: unexpected package format byte: %v", file, c)
-			base.ErrorExit()
+	} else {
+		// Not an archive; provide end of file instead.
+		// TODO(mdempsky): I don't think this happens anymore.
+		var fi os.FileInfo
+		fi, err = f.Stat()
+		if err != nil {
+			return
 		}
-		fingerprint = typecheck.ReadImports(importpkg, imp)
-
-	default:
-		base.Errorf("no import in %q", path)
-		base.ErrorExit()
+		end = fi.Size()
 	}
 
+	if !strings.HasPrefix(line, "go object ") {
+		err = fmt.Errorf("not a go object file: %s", line)
+		return
+	}
+	if expect := objabi.HeaderString(); line != expect {
+		err = fmt.Errorf("object is [%s] expected [%s]", line, expect)
+		return
+	}
+
+	// process header lines
+	for !strings.HasPrefix(line, "$$") {
+		if strings.HasPrefix(line, "newexportsize ") {
+			fields := strings.Fields(line)
+			newsize, err = strconv.ParseInt(fields[1], 10, 64)
+			if err != nil {
+				return
+			}
+		}
+
+		line, err = r.ReadString('\n')
+		if err != nil {
+			return
+		}
+	}
+
+	// Expect $$B\n to signal binary import format.
+	if line != "$$B\n" {
+		err = errors.New("old export format no longer supported (recompile library)")
+		return
+	}
+
+	return
+}
+
+// addFingerprint reads the linker fingerprint included at the end of
+// the exportdata.
+func addFingerprint(path string, f *os.File, end int64) error {
+	const eom = "\n$$\n"
+	var fingerprint goobj.FingerprintType
+
+	var buf [len(fingerprint) + len(eom)]byte
+	if _, err := f.ReadAt(buf[:], end-int64(len(buf))); err != nil {
+		return err
+	}
+
+	// Caller should have given us the end position of the export data,
+	// which should end with the "\n$$\n" marker. As a consistency check
+	// to make sure we're reading at the right offset, make sure we
+	// found the marker.
+	if s := string(buf[len(fingerprint):]); s != eom {
+		return fmt.Errorf("expected $$ marker, but found %q", s)
+	}
+
+	copy(fingerprint[:], buf[:])
+
 	// assume files move (get installed) so don't record the full path
 	if base.Flag.Cfg.PackageFile != nil {
 		// If using a packageFile map, assume path_ can be recorded directly.
 		base.Ctxt.AddImport(path, fingerprint)
 	} else {
 		// For file "/Users/foo/go/pkg/darwin_amd64/math.a" record "math.a".
+		file := f.Name()
 		base.Ctxt.AddImport(file[len(file)-len(path)-len(".a"):], fingerprint)
 	}
-
-	if importpkg.Height >= myheight {
-		myheight = importpkg.Height + 1
-	}
-
-	return importpkg
+	return nil
 }
 
 // The linker uses the magic symbol prefixes "go." and "type."
@@ -431,7 +523,7 @@
 			s.Def = nil
 			continue
 		}
-		if types.IsDotAlias(s) {
+		if s.Def != nil && s.Def.Sym() != s {
 			// throw away top-level name left over
 			// from previous import . "x"
 			// We'll report errors after type checking in CheckDotImports.
diff --git a/src/cmd/compile/internal/noder/irgen.go b/src/cmd/compile/internal/noder/irgen.go
index 3e0d328..7bc8a6b 100644
--- a/src/cmd/compile/internal/noder/irgen.go
+++ b/src/cmd/compile/internal/noder/irgen.go
@@ -18,9 +18,9 @@
 	"cmd/internal/src"
 )
 
-// check2 type checks a Go package using types2, and then generates IR
-// using the results.
-func check2(noders []*noder) {
+// checkFiles configures and runs the types2 checker on the given
+// parsed source files and then returns the result.
+func checkFiles(noders []*noder) (posMap, *types2.Package, *types2.Info) {
 	if base.SyntaxErrors() != 0 {
 		base.ErrorExit()
 	}
@@ -34,20 +34,22 @@
 	}
 
 	// typechecking
+	importer := gcimports{
+		packages: make(map[string]*types2.Package),
+	}
 	conf := types2.Config{
 		GoVersion:             base.Flag.Lang,
 		IgnoreLabels:          true, // parser already checked via syntax.CheckBranches mode
 		CompilerErrorMessages: true, // use error strings matching existing compiler errors
+		AllowTypeLists:        true, // remove this line once all tests use type set syntax
 		Error: func(err error) {
 			terr := err.(types2.Error)
 			base.ErrorfAt(m.makeXPos(terr.Pos), "%s", terr.Msg)
 		},
-		Importer: &gcimports{
-			packages: make(map[string]*types2.Package),
-		},
-		Sizes: &gcSizes{},
+		Importer: &importer,
+		Sizes:    &gcSizes{},
 	}
-	info := types2.Info{
+	info := &types2.Info{
 		Types:      make(map[syntax.Expr]types2.TypeAndValue),
 		Defs:       make(map[*syntax.Name]types2.Object),
 		Uses:       make(map[*syntax.Name]types2.Object),
@@ -57,12 +59,24 @@
 		Inferred:   make(map[syntax.Expr]types2.Inferred),
 		// expand as needed
 	}
-	pkg, err := conf.Check(base.Ctxt.Pkgpath, files, &info)
-	files = nil
+
+	pkg := types2.NewPackage(base.Ctxt.Pkgpath, "")
+	importer.check = types2.NewChecker(&conf, pkg, info)
+	err := importer.check.Files(files)
+
 	base.ExitIfErrors()
 	if err != nil {
 		base.FatalfAt(src.NoXPos, "conf.Check error: %v", err)
 	}
+
+	return m, pkg, info
+}
+
+// check2 type checks a Go package using types2, and then generates IR
+// using the results.
+func check2(noders []*noder) {
+	m, pkg, info := checkFiles(noders)
+
 	if base.Flag.G < 2 {
 		os.Exit(0)
 	}
@@ -70,7 +84,7 @@
 	g := irgen{
 		target: typecheck.Target,
 		self:   pkg,
-		info:   &info,
+		info:   info,
 		posMap: m,
 		objs:   make(map[types2.Object]*ir.Name),
 		typs:   make(map[types2.Type]*types.Type),
@@ -82,6 +96,41 @@
 	}
 }
 
+// gfInfo is information gathered on a generic function.
+type gfInfo struct {
+	tparams      []*types.Type
+	derivedTypes []*types.Type
+	// Nodes in generic function that requires a subdictionary. Includes
+	// method and function calls (OCALL), function values (OFUNCINST), method
+	// values/expressions (OXDOT).
+	subDictCalls []ir.Node
+	// Nodes in generic functions that are a conversion from a typeparam/derived
+	// type to a specific interface.
+	itabConvs []ir.Node
+	// For type switches on nonempty interfaces, a map from OTYPE entries of
+	// HasTParam type, to the interface type we're switching from.
+	// TODO: what if the type we're switching from is a shape type?
+	type2switchType map[ir.Node]*types.Type
+}
+
+// instInfo is information gathered on an gcshape (or fully concrete)
+// instantiation of a function.
+type instInfo struct {
+	fun       *ir.Func // The instantiated function (with body)
+	dictParam *ir.Name // The node inside fun that refers to the dictionary param
+
+	gf     *ir.Name // The associated generic function
+	gfInfo *gfInfo
+
+	startSubDict  int // Start of dict entries for subdictionaries
+	startItabConv int // Start of dict entries for itab conversions
+	dictLen       int // Total number of entries in dictionary
+
+	// Map from nodes in instantiated fun (OCALL, OCALLMETHOD, OFUNCINST, and
+	// OMETHEXPR) to the associated dictionary entry for a sub-dictionary
+	dictEntryMap map[ir.Node]int
+}
+
 type irgen struct {
 	target *ir.Package
 	self   *types2.Package
@@ -94,10 +143,38 @@
 
 	// Fully-instantiated generic types whose methods should be instantiated
 	instTypeList []*types.Type
+
+	dnum int // for generating unique dictionary variables
+
+	// Map from generic function to information about its type params, derived
+	// types, and subdictionaries.
+	gfInfoMap map[*types.Sym]*gfInfo
+
+	// Map from a name of function that been instantiated to information about
+	// its instantiated function, associated generic function/method, and the
+	// mapping from IR nodes to dictionary entries.
+	instInfoMap map[*types.Sym]*instInfo
+
+	// dictionary syms which we need to finish, by writing out any itabconv
+	// entries.
+	dictSymsToFinalize []*delayInfo
+
+	// True when we are compiling a top-level generic function or method. Use to
+	// avoid adding closures of generic functions/methods to the target.Decls
+	// list.
+	topFuncIsGeneric bool
+}
+
+type delayInfo struct {
+	gf    *ir.Name
+	targs []*types.Type
+	sym   *types.Sym
+	off   int
 }
 
 func (g *irgen) generate(noders []*noder) {
 	types.LocalPkg.Name = g.self.Name()
+	types.LocalPkg.Height = g.self.Height()
 	typecheck.TypecheckAllowed = true
 
 	// Prevent size calculations until we set the underlying type
@@ -132,7 +209,6 @@
 			}
 		}
 	}
-	types.LocalPkg.Height = myheight
 
 	// 2. Process all package-block type declarations. As with imports,
 	// we need to make sure all types are properly instantiated before
@@ -167,6 +243,10 @@
 		}
 	}
 
+	// Check for unusual case where noder2 encounters a type error that types2
+	// doesn't check for (e.g. notinheap incompatibility).
+	base.ExitIfErrors()
+
 	typecheck.DeclareUniverse()
 
 	for _, p := range noders {
@@ -175,7 +255,7 @@
 
 		// Double check for any type-checking inconsistencies. This can be
 		// removed once we're confident in IR generation results.
-		syntax.Walk(p.file, func(n syntax.Node) bool {
+		syntax.Crawl(p.file, func(n syntax.Node) bool {
 			g.validate(n)
 			return false
 		})
@@ -184,9 +264,9 @@
 	// Create any needed stencils of generic functions
 	g.stencil()
 
-	// For now, remove all generic functions from g.target.Decl, since they
-	// have been used for stenciling, but don't compile. TODO: We will
-	// eventually export any exportable generic functions.
+	// Remove all generic functions from g.target.Decl, since they have been
+	// used for stenciling, but don't compile. Generic functions will already
+	// have been marked for export as appropriate.
 	j := 0
 	for i, decl := range g.target.Decls {
 		if decl.Op() != ir.ODCLFUNC || !decl.Type().HasTParam() {
diff --git a/src/cmd/compile/internal/noder/linker.go b/src/cmd/compile/internal/noder/linker.go
new file mode 100644
index 0000000..2bc7f7c
--- /dev/null
+++ b/src/cmd/compile/internal/noder/linker.go
@@ -0,0 +1,296 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"io"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/reflectdata"
+	"cmd/compile/internal/types"
+	"cmd/internal/goobj"
+	"cmd/internal/obj"
+)
+
+// This file implements the unified IR linker, which combines the
+// local package's stub data with imported package data to produce a
+// complete export data file. It also rewrites the compiler's
+// extension data sections based on the results of compilation (e.g.,
+// the function inlining cost and linker symbol index assignments).
+//
+// TODO(mdempsky): Using the name "linker" here is confusing, because
+// readers are likely to mistake references to it for cmd/link. But
+// there's a shortage of good names for "something that combines
+// multiple parts into a cohesive whole"... e.g., "assembler" and
+// "compiler" are also already taken.
+
+type linker struct {
+	pw pkgEncoder
+
+	pkgs  map[string]int
+	decls map[*types.Sym]int
+}
+
+func (l *linker) relocAll(pr *pkgReader, relocs []relocEnt) []relocEnt {
+	res := make([]relocEnt, len(relocs))
+	for i, rent := range relocs {
+		rent.idx = l.relocIdx(pr, rent.kind, rent.idx)
+		res[i] = rent
+	}
+	return res
+}
+
+func (l *linker) relocIdx(pr *pkgReader, k reloc, idx int) int {
+	assert(pr != nil)
+
+	absIdx := pr.absIdx(k, idx)
+
+	if newidx := pr.newindex[absIdx]; newidx != 0 {
+		return ^newidx
+	}
+
+	var newidx int
+	switch k {
+	case relocString:
+		newidx = l.relocString(pr, idx)
+	case relocPkg:
+		newidx = l.relocPkg(pr, idx)
+	case relocObj:
+		newidx = l.relocObj(pr, idx)
+
+	default:
+		// Generic relocations.
+		//
+		// TODO(mdempsky): Deduplicate more sections? In fact, I think
+		// every section could be deduplicated. This would also be easier
+		// if we do external relocations.
+
+		w := l.pw.newEncoderRaw(k)
+		l.relocCommon(pr, &w, k, idx)
+		newidx = w.idx
+	}
+
+	pr.newindex[absIdx] = ^newidx
+
+	return newidx
+}
+
+func (l *linker) relocString(pr *pkgReader, idx int) int {
+	return l.pw.stringIdx(pr.stringIdx(idx))
+}
+
+func (l *linker) relocPkg(pr *pkgReader, idx int) int {
+	path := pr.peekPkgPath(idx)
+
+	if newidx, ok := l.pkgs[path]; ok {
+		return newidx
+	}
+
+	r := pr.newDecoder(relocPkg, idx, syncPkgDef)
+	w := l.pw.newEncoder(relocPkg, syncPkgDef)
+	l.pkgs[path] = w.idx
+
+	// TODO(mdempsky): We end up leaving an empty string reference here
+	// from when the package was originally written as "". Probably not
+	// a big deal, but a little annoying. Maybe relocating
+	// cross-references in place is the way to go after all.
+	w.relocs = l.relocAll(pr, r.relocs)
+
+	_ = r.string() // original path
+	w.string(path)
+
+	io.Copy(&w.data, &r.data)
+
+	return w.flush()
+}
+
+func (l *linker) relocObj(pr *pkgReader, idx int) int {
+	path, name, tag := pr.peekObj(idx)
+	sym := types.NewPkg(path, "").Lookup(name)
+
+	if newidx, ok := l.decls[sym]; ok {
+		return newidx
+	}
+
+	if tag == objStub && path != "builtin" && path != "unsafe" {
+		pri, ok := objReader[sym]
+		if !ok {
+			base.Fatalf("missing reader for %q.%v", path, name)
+		}
+		assert(ok)
+
+		pr = pri.pr
+		idx = pri.idx
+
+		path2, name2, tag2 := pr.peekObj(idx)
+		sym2 := types.NewPkg(path2, "").Lookup(name2)
+		assert(sym == sym2)
+		assert(tag2 != objStub)
+	}
+
+	w := l.pw.newEncoderRaw(relocObj)
+	wext := l.pw.newEncoderRaw(relocObjExt)
+	wname := l.pw.newEncoderRaw(relocName)
+	wdict := l.pw.newEncoderRaw(relocObjDict)
+
+	l.decls[sym] = w.idx
+	assert(wext.idx == w.idx)
+	assert(wname.idx == w.idx)
+	assert(wdict.idx == w.idx)
+
+	l.relocCommon(pr, &w, relocObj, idx)
+	l.relocCommon(pr, &wname, relocName, idx)
+	l.relocCommon(pr, &wdict, relocObjDict, idx)
+
+	var obj *ir.Name
+	if path == "" {
+		var ok bool
+		obj, ok = sym.Def.(*ir.Name)
+
+		// Generic types and functions and declared constraint types won't
+		// have definitions.
+		// For now, just generically copy their extension data.
+		// TODO(mdempsky): Restore assertion.
+		if !ok && false {
+			base.Fatalf("missing definition for %v", sym)
+		}
+	}
+
+	if obj != nil {
+		wext.sync(syncObject1)
+		switch tag {
+		case objFunc:
+			l.relocFuncExt(&wext, obj)
+		case objType:
+			l.relocTypeExt(&wext, obj)
+		case objVar:
+			l.relocVarExt(&wext, obj)
+		}
+		wext.flush()
+	} else {
+		l.relocCommon(pr, &wext, relocObjExt, idx)
+	}
+
+	return w.idx
+}
+
+func (l *linker) relocCommon(pr *pkgReader, w *encoder, k reloc, idx int) {
+	r := pr.newDecoderRaw(k, idx)
+	w.relocs = l.relocAll(pr, r.relocs)
+	io.Copy(&w.data, &r.data)
+	w.flush()
+}
+
+func (l *linker) pragmaFlag(w *encoder, pragma ir.PragmaFlag) {
+	w.sync(syncPragma)
+	w.int(int(pragma))
+}
+
+func (l *linker) relocFuncExt(w *encoder, name *ir.Name) {
+	w.sync(syncFuncExt)
+
+	l.pragmaFlag(w, name.Func.Pragma)
+	l.linkname(w, name)
+
+	// Relocated extension data.
+	w.bool(true)
+
+	// Record definition ABI so cross-ABI calls can be direct.
+	// This is important for the performance of calling some
+	// common functions implemented in assembly (e.g., bytealg).
+	w.uint64(uint64(name.Func.ABI))
+
+	// Escape analysis.
+	for _, fs := range &types.RecvsParams {
+		for _, f := range fs(name.Type()).FieldSlice() {
+			w.string(f.Note)
+		}
+	}
+
+	if inl := name.Func.Inl; w.bool(inl != nil) {
+		w.len(int(inl.Cost))
+		w.bool(inl.CanDelayResults)
+
+		pri, ok := bodyReader[name.Func]
+		assert(ok)
+		w.reloc(relocBody, l.relocIdx(pri.pr, relocBody, pri.idx))
+	}
+
+	w.sync(syncEOF)
+}
+
+func (l *linker) relocTypeExt(w *encoder, name *ir.Name) {
+	w.sync(syncTypeExt)
+
+	typ := name.Type()
+
+	l.pragmaFlag(w, name.Pragma())
+
+	// For type T, export the index of type descriptor symbols of T and *T.
+	l.lsymIdx(w, "", reflectdata.TypeLinksym(typ))
+	l.lsymIdx(w, "", reflectdata.TypeLinksym(typ.PtrTo()))
+
+	if typ.Kind() != types.TINTER {
+		for _, method := range typ.Methods().Slice() {
+			l.relocFuncExt(w, method.Nname.(*ir.Name))
+		}
+	}
+}
+
+func (l *linker) relocVarExt(w *encoder, name *ir.Name) {
+	w.sync(syncVarExt)
+	l.linkname(w, name)
+}
+
+func (l *linker) linkname(w *encoder, name *ir.Name) {
+	w.sync(syncLinkname)
+
+	linkname := name.Sym().Linkname
+	if !l.lsymIdx(w, linkname, name.Linksym()) {
+		w.string(linkname)
+	}
+}
+
+func (l *linker) lsymIdx(w *encoder, linkname string, lsym *obj.LSym) bool {
+	if lsym.PkgIdx > goobj.PkgIdxSelf || (lsym.PkgIdx == goobj.PkgIdxInvalid && !lsym.Indexed()) || linkname != "" {
+		w.int64(-1)
+		return false
+	}
+
+	// For a defined symbol, export its index.
+	// For re-exporting an imported symbol, pass its index through.
+	w.int64(int64(lsym.SymIdx))
+	return true
+}
+
+// @@@ Helpers
+
+// TODO(mdempsky): These should probably be removed. I think they're a
+// smell that the export data format is not yet quite right.
+
+func (pr *pkgDecoder) peekPkgPath(idx int) string {
+	r := pr.newDecoder(relocPkg, idx, syncPkgDef)
+	path := r.string()
+	if path == "" {
+		path = pr.pkgPath
+	}
+	return path
+}
+
+func (pr *pkgDecoder) peekObj(idx int) (string, string, codeObj) {
+	r := pr.newDecoder(relocName, idx, syncObject1)
+	r.sync(syncSym)
+	r.sync(syncPkg)
+	path := pr.peekPkgPath(r.reloc(relocPkg))
+	name := r.string()
+	assert(name != "")
+
+	tag := codeObj(r.code(syncCodeObj))
+
+	return path, name, tag
+}
diff --git a/src/cmd/compile/internal/noder/noder.go b/src/cmd/compile/internal/noder/noder.go
index 5fcad09..6a2aacd 100644
--- a/src/cmd/compile/internal/noder/noder.go
+++ b/src/cmd/compile/internal/noder/noder.go
@@ -5,9 +5,11 @@
 package noder
 
 import (
+	"errors"
 	"fmt"
 	"go/constant"
 	"go/token"
+	"internal/buildcfg"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -29,8 +31,11 @@
 func LoadPackage(filenames []string) {
 	base.Timer.Start("fe", "parse")
 
+	// -G=3 and unified expect generics syntax, but -G=0 does not.
+	supportsGenerics := base.Flag.G != 0 || buildcfg.Experiment.Unified
+
 	mode := syntax.CheckBranches
-	if base.Flag.G != 0 {
+	if supportsGenerics && types.AllowsGoVersion(types.LocalPkg, 1, 18) {
 		mode |= syntax.AllowGenerics
 	}
 
@@ -75,6 +80,11 @@
 	}
 	base.Timer.AddEvent(int64(lines), "lines")
 
+	if base.Debug.Unified != 0 {
+		unified(noders)
+		return
+	}
+
 	if base.Flag.G != 0 {
 		// Use types2 to type-check and possibly generate IR.
 		check2(noders)
@@ -109,25 +119,35 @@
 	//   We also defer type alias declarations until phase 2
 	//   to avoid cycles like #18640.
 	//   TODO(gri) Remove this again once we have a fix for #25838.
-
-	// Don't use range--typecheck can add closures to Target.Decls.
-	base.Timer.Start("fe", "typecheck", "top1")
-	for i := 0; i < len(typecheck.Target.Decls); i++ {
-		n := typecheck.Target.Decls[i]
-		if op := n.Op(); op != ir.ODCL && op != ir.OAS && op != ir.OAS2 && (op != ir.ODCLTYPE || !n.(*ir.Decl).X.Alias()) {
-			typecheck.Target.Decls[i] = typecheck.Stmt(n)
-		}
-	}
-
+	//
 	// Phase 2: Variable assignments.
 	//   To check interface assignments, depends on phase 1.
 
 	// Don't use range--typecheck can add closures to Target.Decls.
-	base.Timer.Start("fe", "typecheck", "top2")
-	for i := 0; i < len(typecheck.Target.Decls); i++ {
-		n := typecheck.Target.Decls[i]
-		if op := n.Op(); op == ir.ODCL || op == ir.OAS || op == ir.OAS2 || op == ir.ODCLTYPE && n.(*ir.Decl).X.Alias() {
-			typecheck.Target.Decls[i] = typecheck.Stmt(n)
+	for phase, name := range []string{"top1", "top2"} {
+		base.Timer.Start("fe", "typecheck", name)
+		for i := 0; i < len(typecheck.Target.Decls); i++ {
+			n := typecheck.Target.Decls[i]
+			op := n.Op()
+
+			// Closure function declarations are typechecked as part of the
+			// closure expression.
+			if fn, ok := n.(*ir.Func); ok && fn.OClosure != nil {
+				continue
+			}
+
+			// We don't actually add ir.ODCL nodes to Target.Decls. Make sure of that.
+			if op == ir.ODCL {
+				base.FatalfAt(n.Pos(), "unexpected top declaration: %v", op)
+			}
+
+			// Identify declarations that should be deferred to the second
+			// iteration.
+			late := op == ir.OAS || op == ir.OAS2 || op == ir.ODCLTYPE && n.(*ir.Decl).X.Alias()
+
+			if late == (phase == 1) {
+				typecheck.Target.Decls[i] = typecheck.Stmt(n)
+			}
 		}
 	}
 
@@ -136,16 +156,15 @@
 	base.Timer.Start("fe", "typecheck", "func")
 	var fcount int64
 	for i := 0; i < len(typecheck.Target.Decls); i++ {
-		n := typecheck.Target.Decls[i]
-		if n.Op() == ir.ODCLFUNC {
+		if fn, ok := typecheck.Target.Decls[i].(*ir.Func); ok {
 			if base.Flag.W > 1 {
-				s := fmt.Sprintf("\nbefore typecheck %v", n)
-				ir.Dump(s, n)
+				s := fmt.Sprintf("\nbefore typecheck %v", fn)
+				ir.Dump(s, fn)
 			}
-			typecheck.FuncBody(n.(*ir.Func))
+			typecheck.FuncBody(fn)
 			if base.Flag.W > 1 {
-				s := fmt.Sprintf("\nafter typecheck %v", n)
-				ir.Dump(s, n)
+				s := fmt.Sprintf("\nafter typecheck %v", fn)
+				ir.Dump(s, fn)
 			}
 			fcount++
 		}
@@ -449,7 +468,7 @@
 type constState struct {
 	group  *syntax.Group
 	typ    ir.Ntype
-	values []ir.Node
+	values syntax.Expr
 	iota   int64
 }
 
@@ -467,16 +486,15 @@
 	names := p.declNames(ir.OLITERAL, decl.NameList)
 	typ := p.typeExprOrNil(decl.Type)
 
-	var values []ir.Node
 	if decl.Values != nil {
-		values = p.exprList(decl.Values)
-		cs.typ, cs.values = typ, values
+		cs.typ, cs.values = typ, decl.Values
 	} else {
 		if typ != nil {
 			base.Errorf("const declaration cannot have type without expression")
 		}
-		typ, values = cs.typ, cs.values
+		typ = cs.typ
 	}
+	values := p.exprList(cs.values)
 
 	nn := make([]ir.Node, 0, len(names))
 	for i, n := range names {
@@ -484,10 +502,16 @@
 			base.Errorf("missing value in const declaration")
 			break
 		}
+
 		v := values[i]
 		if decl.Values == nil {
-			v = ir.DeepCopy(n.Pos(), v)
+			ir.Visit(v, func(v ir.Node) {
+				if ir.HasUniquePos(v) {
+					v.SetPos(n.Pos())
+				}
+			})
 		}
+
 		typecheck.Declare(n, typecheck.DeclContext)
 
 		n.Ntype = typ
@@ -625,6 +649,9 @@
 	for i, param := range params {
 		p.setlineno(param)
 		nodes = append(nodes, p.param(param, dddOk, i+1 == len(params)))
+		if i > 0 && params[i].Type == params[i-1].Type {
+			nodes[i].Ntype = nodes[i-1].Ntype
+		}
 	}
 	return nodes
 }
@@ -914,6 +941,9 @@
 		} else {
 			n = ir.NewField(p.pos(field), p.name(field.Name), p.typeExpr(field.Type), nil)
 		}
+		if i > 0 && expr.FieldList[i].Type == expr.FieldList[i-1].Type {
+			n.Ntype = l[i-1].Ntype
+		}
 		if i < len(expr.TagList) && expr.TagList[i] != nil {
 			n.Note = constant.StringVal(p.basicLit(expr.TagList[i]))
 		}
@@ -977,6 +1007,8 @@
 }
 
 func (p *noder) embedded(typ syntax.Expr) *ir.Field {
+	pos := p.pos(syntax.StartPos(typ))
+
 	op, isStar := typ.(*syntax.Operation)
 	if isStar {
 		if op.Op != syntax.Mul || op.Y != nil {
@@ -986,11 +1018,11 @@
 	}
 
 	sym := p.packname(typ)
-	n := ir.NewField(p.pos(typ), typecheck.Lookup(sym.Name), importName(sym).(ir.Ntype), nil)
+	n := ir.NewField(pos, typecheck.Lookup(sym.Name), importName(sym).(ir.Ntype), nil)
 	n.Embedded = true
 
 	if isStar {
-		n.Ntype = ir.NewStarExpr(p.pos(op), n.Ntype)
+		n.Ntype = ir.NewStarExpr(pos, n.Ntype)
 	}
 	return n
 }
@@ -1780,24 +1812,14 @@
 }
 
 func (p *noder) funcLit(expr *syntax.FuncLit) ir.Node {
-	xtype := p.typeExpr(expr.Type)
-
-	fn := ir.NewFunc(p.pos(expr))
-	fn.SetIsHiddenClosure(ir.CurFunc != nil)
-
-	fn.Nname = ir.NewNameAt(p.pos(expr), ir.BlankNode.Sym()) // filled in by tcClosure
-	fn.Nname.Func = fn
-	fn.Nname.Ntype = xtype
-	fn.Nname.Defn = fn
-
-	clo := ir.NewClosureExpr(p.pos(expr), fn)
-	fn.OClosure = clo
+	fn := ir.NewClosureFunc(p.pos(expr), ir.CurFunc != nil)
+	fn.Nname.Ntype = p.typeExpr(expr.Type)
 
 	p.funcBody(fn, expr.Body)
 
 	ir.FinishCaptureNames(base.Pos, ir.CurFunc, fn)
 
-	return clo
+	return fn.OClosure
 }
 
 // A function named init is a special case.
@@ -1841,33 +1863,14 @@
 }
 
 func varEmbed(makeXPos func(syntax.Pos) src.XPos, name *ir.Name, decl *syntax.VarDecl, pragma *pragmas, haveEmbed bool) {
-	if pragma.Embeds == nil {
-		return
-	}
-
 	pragmaEmbeds := pragma.Embeds
 	pragma.Embeds = nil
-	pos := makeXPos(pragmaEmbeds[0].Pos)
+	if len(pragmaEmbeds) == 0 {
+		return
+	}
 
-	if !haveEmbed {
-		base.ErrorfAt(pos, "go:embed only allowed in Go files that import \"embed\"")
-		return
-	}
-	if len(decl.NameList) > 1 {
-		base.ErrorfAt(pos, "go:embed cannot apply to multiple vars")
-		return
-	}
-	if decl.Values != nil {
-		base.ErrorfAt(pos, "go:embed cannot apply to var with initializer")
-		return
-	}
-	if decl.Type == nil {
-		// Should not happen, since Values == nil now.
-		base.ErrorfAt(pos, "go:embed cannot apply to var without type")
-		return
-	}
-	if typecheck.DeclContext != ir.PEXTERN {
-		base.ErrorfAt(pos, "go:embed cannot apply to var inside func")
+	if err := checkEmbed(decl, haveEmbed, typecheck.DeclContext != ir.PEXTERN); err != nil {
+		base.ErrorfAt(makeXPos(pragmaEmbeds[0].Pos), "%s", err)
 		return
 	}
 
@@ -1878,3 +1881,24 @@
 	typecheck.Target.Embeds = append(typecheck.Target.Embeds, name)
 	name.Embed = &embeds
 }
+
+func checkEmbed(decl *syntax.VarDecl, haveEmbed, withinFunc bool) error {
+	switch {
+	case !haveEmbed:
+		return errors.New("go:embed only allowed in Go files that import \"embed\"")
+	case len(decl.NameList) > 1:
+		return errors.New("go:embed cannot apply to multiple vars")
+	case decl.Values != nil:
+		return errors.New("go:embed cannot apply to var with initializer")
+	case decl.Type == nil:
+		// Should not happen, since Values == nil now.
+		return errors.New("go:embed cannot apply to var without type")
+	case withinFunc:
+		return errors.New("go:embed cannot apply to var inside func")
+	case !types.AllowsGoVersion(types.LocalPkg, 1, 16):
+		return fmt.Errorf("go:embed requires go1.16 or later (-lang was set to %s; check go.mod)", base.Flag.Lang)
+
+	default:
+		return nil
+	}
+}
diff --git a/src/cmd/compile/internal/noder/object.go b/src/cmd/compile/internal/noder/object.go
index 82cce1a..40c0b9c 100644
--- a/src/cmd/compile/internal/noder/object.go
+++ b/src/cmd/compile/internal/noder/object.go
@@ -29,7 +29,7 @@
 	if !ok {
 		base.FatalfAt(g.pos(name), "unknown name %v", name)
 	}
-	obj := ir.CaptureName(g.pos(obj2), ir.CurFunc, g.obj(obj2))
+	obj := ir.CaptureName(g.pos(name), ir.CurFunc, g.obj(obj2))
 	if obj.Defn != nil && obj.Defn.Op() == ir.ONAME {
 		// If CaptureName created a closure variable, then transfer the
 		// type of the captured name to the new closure variable.
@@ -49,6 +49,11 @@
 	// For imported objects, we use iimport directly instead of mapping
 	// the types2 representation.
 	if obj.Pkg() != g.self {
+		if sig, ok := obj.Type().(*types2.Signature); ok && sig.Recv() != nil {
+			// We can't import a method by name - must import the type
+			// and access the method from it.
+			base.FatalfAt(g.pos(obj), "tried to import a method directly")
+		}
 		sym := g.sym(obj)
 		if sym.Def != nil {
 			return sym.Def.(*ir.Name)
@@ -101,25 +106,28 @@
 	case *types2.TypeName:
 		if obj.IsAlias() {
 			name = g.objCommon(pos, ir.OTYPE, g.sym(obj), class, g.typ(obj.Type()))
+			name.SetAlias(true)
 		} else {
 			name = ir.NewDeclNameAt(pos, ir.OTYPE, g.sym(obj))
 			g.objFinish(name, class, types.NewNamed(name))
 		}
 
 	case *types2.Var:
-		var sym *types.Sym
-		if class == ir.PPARAMOUT {
+		sym := g.sym(obj)
+		if class == ir.PPARAMOUT && (sym == nil || sym.IsBlank()) {
 			// Backend needs names for result parameters,
 			// even if they're anonymous or blank.
-			switch obj.Name() {
-			case "":
-				sym = typecheck.LookupNum("~r", len(ir.CurFunc.Dcl)) // 'r' for "result"
-			case "_":
-				sym = typecheck.LookupNum("~b", len(ir.CurFunc.Dcl)) // 'b' for "blank"
+			nresults := 0
+			for _, n := range ir.CurFunc.Dcl {
+				if n.Class == ir.PPARAMOUT {
+					nresults++
+				}
 			}
-		}
-		if sym == nil {
-			sym = g.sym(obj)
+			if sym == nil {
+				sym = typecheck.LookupNum("~r", nresults) // 'r' for "result"
+			} else {
+				sym = typecheck.LookupNum("~b", nresults) // 'b' for "blank"
+			}
 		}
 		name = g.objCommon(pos, ir.ONAME, sym, class, g.typ(obj.Type()))
 
@@ -164,9 +172,8 @@
 			break // methods are exported with their receiver type
 		}
 		if types.IsExported(sym.Name) {
-			if name.Class == ir.PFUNC && name.Type().NumTParams() > 0 {
-				base.FatalfAt(name.Pos(), "Cannot export a generic function (yet): %v", name)
-			}
+			// Generic functions can be marked for export here, even
+			// though they will not be compiled until instantiated.
 			typecheck.Export(name)
 		}
 		if base.Flag.AsmHdr != "" && !name.Sym().Asm() {
diff --git a/src/cmd/compile/internal/noder/quirks.go b/src/cmd/compile/internal/noder/quirks.go
new file mode 100644
index 0000000..914c5d2
--- /dev/null
+++ b/src/cmd/compile/internal/noder/quirks.go
@@ -0,0 +1,450 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"fmt"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/types2"
+	"cmd/internal/src"
+)
+
+// This file defines helper functions useful for satisfying toolstash
+// -cmp when compared against the legacy frontend behavior, but can be
+// removed after that's no longer a concern.
+
+// quirksMode controls whether behavior specific to satisfying
+// toolstash -cmp is used.
+func quirksMode() bool {
+	return base.Debug.UnifiedQuirks != 0
+}
+
+// posBasesOf returns all of the position bases in the source files,
+// as seen in a straightforward traversal.
+//
+// This is necessary to ensure position bases (and thus file names)
+// get registered in the same order as noder would visit them.
+func posBasesOf(noders []*noder) []*syntax.PosBase {
+	seen := make(map[*syntax.PosBase]bool)
+	var bases []*syntax.PosBase
+
+	for _, p := range noders {
+		syntax.Crawl(p.file, func(n syntax.Node) bool {
+			if b := n.Pos().Base(); !seen[b] {
+				bases = append(bases, b)
+				seen[b] = true
+			}
+			return false
+		})
+	}
+
+	return bases
+}
+
+// importedObjsOf returns the imported objects (i.e., referenced
+// objects not declared by curpkg) from the parsed source files, in
+// the order that typecheck used to load their definitions.
+//
+// This is needed because loading the definitions for imported objects
+// can also add file names.
+func importedObjsOf(curpkg *types2.Package, info *types2.Info, noders []*noder) []types2.Object {
+	// This code is complex because it matches the precise order that
+	// typecheck recursively and repeatedly traverses the IR. It's meant
+	// to be thrown away eventually anyway.
+
+	seen := make(map[types2.Object]bool)
+	var objs []types2.Object
+
+	var phase int
+
+	decls := make(map[types2.Object]syntax.Decl)
+	assoc := func(decl syntax.Decl, names ...*syntax.Name) {
+		for _, name := range names {
+			obj, ok := info.Defs[name]
+			assert(ok)
+			decls[obj] = decl
+		}
+	}
+
+	for _, p := range noders {
+		syntax.Crawl(p.file, func(n syntax.Node) bool {
+			switch n := n.(type) {
+			case *syntax.ConstDecl:
+				assoc(n, n.NameList...)
+			case *syntax.FuncDecl:
+				assoc(n, n.Name)
+			case *syntax.TypeDecl:
+				assoc(n, n.Name)
+			case *syntax.VarDecl:
+				assoc(n, n.NameList...)
+			case *syntax.BlockStmt:
+				return true
+			}
+			return false
+		})
+	}
+
+	var visited map[syntax.Decl]bool
+
+	var resolveDecl func(n syntax.Decl)
+	var resolveNode func(n syntax.Node, top bool)
+
+	resolveDecl = func(n syntax.Decl) {
+		if visited[n] {
+			return
+		}
+		visited[n] = true
+
+		switch n := n.(type) {
+		case *syntax.ConstDecl:
+			resolveNode(n.Type, true)
+			resolveNode(n.Values, true)
+
+		case *syntax.FuncDecl:
+			if n.Recv != nil {
+				resolveNode(n.Recv, true)
+			}
+			resolveNode(n.Type, true)
+
+		case *syntax.TypeDecl:
+			resolveNode(n.Type, true)
+
+		case *syntax.VarDecl:
+			if n.Type != nil {
+				resolveNode(n.Type, true)
+			} else {
+				resolveNode(n.Values, true)
+			}
+		}
+	}
+
+	resolveObj := func(pos syntax.Pos, obj types2.Object) {
+		switch obj.Pkg() {
+		case nil:
+			// builtin; nothing to do
+
+		case curpkg:
+			if decl, ok := decls[obj]; ok {
+				resolveDecl(decl)
+			}
+
+		default:
+			if obj.Parent() == obj.Pkg().Scope() && !seen[obj] {
+				seen[obj] = true
+				objs = append(objs, obj)
+			}
+		}
+	}
+
+	checkdefat := func(pos syntax.Pos, n *syntax.Name) {
+		if n.Value == "_" {
+			return
+		}
+		obj, ok := info.Uses[n]
+		if !ok {
+			obj, ok = info.Defs[n]
+			if !ok {
+				return
+			}
+		}
+		if obj == nil {
+			return
+		}
+		resolveObj(pos, obj)
+	}
+	checkdef := func(n *syntax.Name) { checkdefat(n.Pos(), n) }
+
+	var later []syntax.Node
+
+	resolveNode = func(n syntax.Node, top bool) {
+		if n == nil {
+			return
+		}
+		syntax.Crawl(n, func(n syntax.Node) bool {
+			switch n := n.(type) {
+			case *syntax.Name:
+				checkdef(n)
+
+			case *syntax.SelectorExpr:
+				if name, ok := n.X.(*syntax.Name); ok {
+					if _, isPkg := info.Uses[name].(*types2.PkgName); isPkg {
+						checkdefat(n.X.Pos(), n.Sel)
+						return true
+					}
+				}
+
+			case *syntax.AssignStmt:
+				resolveNode(n.Rhs, top)
+				resolveNode(n.Lhs, top)
+				return true
+
+			case *syntax.VarDecl:
+				resolveNode(n.Values, top)
+
+			case *syntax.FuncLit:
+				if top {
+					resolveNode(n.Type, top)
+					later = append(later, n.Body)
+					return true
+				}
+
+			case *syntax.BlockStmt:
+				if phase >= 3 {
+					for _, stmt := range n.List {
+						resolveNode(stmt, false)
+					}
+				}
+				return true
+			}
+
+			return false
+		})
+	}
+
+	for phase = 1; phase <= 5; phase++ {
+		visited = map[syntax.Decl]bool{}
+
+		for _, p := range noders {
+			for _, decl := range p.file.DeclList {
+				switch decl := decl.(type) {
+				case *syntax.ConstDecl:
+					resolveDecl(decl)
+
+				case *syntax.FuncDecl:
+					resolveDecl(decl)
+					if phase >= 3 && decl.Body != nil {
+						resolveNode(decl.Body, true)
+					}
+
+				case *syntax.TypeDecl:
+					if !decl.Alias || phase >= 2 {
+						resolveDecl(decl)
+					}
+
+				case *syntax.VarDecl:
+					if phase >= 2 {
+						resolveNode(decl.Values, true)
+						resolveDecl(decl)
+					}
+				}
+			}
+
+			if phase >= 5 {
+				syntax.Crawl(p.file, func(n syntax.Node) bool {
+					if name, ok := n.(*syntax.Name); ok {
+						if obj, ok := info.Uses[name]; ok {
+							resolveObj(name.Pos(), obj)
+						}
+					}
+					return false
+				})
+			}
+		}
+
+		for i := 0; i < len(later); i++ {
+			resolveNode(later[i], true)
+		}
+		later = nil
+	}
+
+	return objs
+}
+
+// typeExprEndPos returns the position that noder would leave base.Pos
+// after parsing the given type expression.
+func typeExprEndPos(expr0 syntax.Expr) syntax.Pos {
+	for {
+		switch expr := expr0.(type) {
+		case *syntax.Name:
+			return expr.Pos()
+		case *syntax.SelectorExpr:
+			return expr.X.Pos()
+
+		case *syntax.ParenExpr:
+			expr0 = expr.X
+
+		case *syntax.Operation:
+			assert(expr.Op == syntax.Mul)
+			assert(expr.Y == nil)
+			expr0 = expr.X
+
+		case *syntax.ArrayType:
+			expr0 = expr.Elem
+		case *syntax.ChanType:
+			expr0 = expr.Elem
+		case *syntax.DotsType:
+			expr0 = expr.Elem
+		case *syntax.MapType:
+			expr0 = expr.Value
+		case *syntax.SliceType:
+			expr0 = expr.Elem
+
+		case *syntax.StructType:
+			return expr.Pos()
+
+		case *syntax.InterfaceType:
+			expr0 = lastFieldType(expr.MethodList)
+			if expr0 == nil {
+				return expr.Pos()
+			}
+
+		case *syntax.FuncType:
+			expr0 = lastFieldType(expr.ResultList)
+			if expr0 == nil {
+				expr0 = lastFieldType(expr.ParamList)
+				if expr0 == nil {
+					return expr.Pos()
+				}
+			}
+
+		case *syntax.IndexExpr: // explicit type instantiation
+			targs := unpackListExpr(expr.Index)
+			expr0 = targs[len(targs)-1]
+
+		default:
+			panic(fmt.Sprintf("%s: unexpected type expression %v", expr.Pos(), syntax.String(expr)))
+		}
+	}
+}
+
+func lastFieldType(fields []*syntax.Field) syntax.Expr {
+	if len(fields) == 0 {
+		return nil
+	}
+	return fields[len(fields)-1].Type
+}
+
+// sumPos returns the position that noder.sum would produce for
+// constant expression x.
+func sumPos(x syntax.Expr) syntax.Pos {
+	orig := x
+	for {
+		switch x1 := x.(type) {
+		case *syntax.BasicLit:
+			assert(x1.Kind == syntax.StringLit)
+			return x1.Pos()
+		case *syntax.Operation:
+			assert(x1.Op == syntax.Add && x1.Y != nil)
+			if r, ok := x1.Y.(*syntax.BasicLit); ok {
+				assert(r.Kind == syntax.StringLit)
+				x = x1.X
+				continue
+			}
+		}
+		return orig.Pos()
+	}
+}
+
+// funcParamsEndPos returns the value of base.Pos left by noder after
+// processing a function signature.
+func funcParamsEndPos(fn *ir.Func) src.XPos {
+	sig := fn.Nname.Type()
+
+	fields := sig.Results().FieldSlice()
+	if len(fields) == 0 {
+		fields = sig.Params().FieldSlice()
+		if len(fields) == 0 {
+			fields = sig.Recvs().FieldSlice()
+			if len(fields) == 0 {
+				if fn.OClosure != nil {
+					return fn.Nname.Ntype.Pos()
+				}
+				return fn.Pos()
+			}
+		}
+	}
+
+	return fields[len(fields)-1].Pos
+}
+
+type dupTypes struct {
+	origs map[types2.Type]types2.Type
+}
+
+func (d *dupTypes) orig(t types2.Type) types2.Type {
+	if orig, ok := d.origs[t]; ok {
+		return orig
+	}
+	return t
+}
+
+func (d *dupTypes) add(t, orig types2.Type) {
+	if t == orig {
+		return
+	}
+
+	if d.origs == nil {
+		d.origs = make(map[types2.Type]types2.Type)
+	}
+	assert(d.origs[t] == nil)
+	d.origs[t] = orig
+
+	switch t := t.(type) {
+	case *types2.Pointer:
+		orig := orig.(*types2.Pointer)
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Slice:
+		orig := orig.(*types2.Slice)
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Map:
+		orig := orig.(*types2.Map)
+		d.add(t.Key(), orig.Key())
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Array:
+		orig := orig.(*types2.Array)
+		assert(t.Len() == orig.Len())
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Chan:
+		orig := orig.(*types2.Chan)
+		assert(t.Dir() == orig.Dir())
+		d.add(t.Elem(), orig.Elem())
+
+	case *types2.Struct:
+		orig := orig.(*types2.Struct)
+		assert(t.NumFields() == orig.NumFields())
+		for i := 0; i < t.NumFields(); i++ {
+			d.add(t.Field(i).Type(), orig.Field(i).Type())
+		}
+
+	case *types2.Interface:
+		orig := orig.(*types2.Interface)
+		assert(t.NumExplicitMethods() == orig.NumExplicitMethods())
+		assert(t.NumEmbeddeds() == orig.NumEmbeddeds())
+		for i := 0; i < t.NumExplicitMethods(); i++ {
+			d.add(t.ExplicitMethod(i).Type(), orig.ExplicitMethod(i).Type())
+		}
+		for i := 0; i < t.NumEmbeddeds(); i++ {
+			d.add(t.EmbeddedType(i), orig.EmbeddedType(i))
+		}
+
+	case *types2.Signature:
+		orig := orig.(*types2.Signature)
+		assert((t.Recv() == nil) == (orig.Recv() == nil))
+		if t.Recv() != nil {
+			d.add(t.Recv().Type(), orig.Recv().Type())
+		}
+		d.add(t.Params(), orig.Params())
+		d.add(t.Results(), orig.Results())
+
+	case *types2.Tuple:
+		orig := orig.(*types2.Tuple)
+		assert(t.Len() == orig.Len())
+		for i := 0; i < t.Len(); i++ {
+			d.add(t.At(i).Type(), orig.At(i).Type())
+		}
+
+	default:
+		assert(types2.Identical(t, orig))
+	}
+}
diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
new file mode 100644
index 0000000..5481812
--- /dev/null
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -0,0 +1,2390 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"bytes"
+	"fmt"
+	"go/constant"
+	"strings"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/deadcode"
+	"cmd/compile/internal/dwarfgen"
+	"cmd/compile/internal/inline"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/reflectdata"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/obj"
+	"cmd/internal/src"
+)
+
+// TODO(mdempsky): Suppress duplicate type/const errors that can arise
+// during typecheck due to naive type substitution (e.g., see #42758).
+// I anticipate these will be handled as a consequence of adding
+// dictionaries support, so it's probably not important to focus on
+// this until after that's done.
+
+type pkgReader struct {
+	pkgDecoder
+
+	posBases []*src.PosBase
+	pkgs     []*types.Pkg
+	typs     []*types.Type
+
+	// offset for rewriting the given index into the output,
+	// but bitwise inverted so we can detect if we're missing the entry or not.
+	newindex []int
+}
+
+func newPkgReader(pr pkgDecoder) *pkgReader {
+	return &pkgReader{
+		pkgDecoder: pr,
+
+		posBases: make([]*src.PosBase, pr.numElems(relocPosBase)),
+		pkgs:     make([]*types.Pkg, pr.numElems(relocPkg)),
+		typs:     make([]*types.Type, pr.numElems(relocType)),
+
+		newindex: make([]int, pr.totalElems()),
+	}
+}
+
+type pkgReaderIndex struct {
+	pr   *pkgReader
+	idx  int
+	dict *readerDict
+}
+
+func (pri pkgReaderIndex) asReader(k reloc, marker syncMarker) *reader {
+	r := pri.pr.newReader(k, pri.idx, marker)
+	r.dict = pri.dict
+	return r
+}
+
+func (pr *pkgReader) newReader(k reloc, idx int, marker syncMarker) *reader {
+	return &reader{
+		decoder: pr.newDecoder(k, idx, marker),
+		p:       pr,
+	}
+}
+
+type reader struct {
+	decoder
+
+	p *pkgReader
+
+	ext *reader
+
+	dict *readerDict
+
+	// TODO(mdempsky): The state below is all specific to reading
+	// function bodies. It probably makes sense to split it out
+	// separately so that it doesn't take up space in every reader
+	// instance.
+
+	curfn       *ir.Func
+	locals      []*ir.Name
+	closureVars []*ir.Name
+
+	funarghack bool
+
+	// scopeVars is a stack tracking the number of variables declared in
+	// the current function at the moment each open scope was opened.
+	scopeVars         []int
+	marker            dwarfgen.ScopeMarker
+	lastCloseScopePos src.XPos
+
+	// === details for handling inline body expansion ===
+
+	// If we're reading in a function body because of inlining, this is
+	// the call that we're inlining for.
+	inlCaller    *ir.Func
+	inlCall      *ir.CallExpr
+	inlFunc      *ir.Func
+	inlTreeIndex int
+	inlPosBases  map[*src.PosBase]*src.PosBase
+
+	delayResults bool
+
+	// Label to return to.
+	retlabel *types.Sym
+
+	inlvars, retvars ir.Nodes
+}
+
+type readerDict struct {
+	// targs holds the implicit and explicit type arguments in use for
+	// reading the current object. For example:
+	//
+	//	func F[T any]() {
+	//		type X[U any] struct { t T; u U }
+	//		var _ X[string]
+	//	}
+	//
+	//	var _ = F[int]
+	//
+	// While instantiating F[int], we need to in turn instantiate
+	// X[string]. [int] and [string] are explicit type arguments for F
+	// and X, respectively; but [int] is also the implicit type
+	// arguments for X.
+	//
+	// (As an analogy to function literals, explicits are the function
+	// literal's formal parameters, while implicits are variables
+	// captured by the function literal.)
+	targs []*types.Type
+
+	// implicits counts how many of types within targs are implicit type
+	// arguments; the rest are explicit.
+	implicits int
+
+	derived      []derivedInfo // reloc index of the derived type's descriptor
+	derivedTypes []*types.Type // slice of previously computed derived types
+
+	funcs    []objInfo
+	funcsObj []ir.Node
+}
+
+func (r *reader) setType(n ir.Node, typ *types.Type) {
+	n.SetType(typ)
+	n.SetTypecheck(1)
+
+	if name, ok := n.(*ir.Name); ok {
+		name.SetWalkdef(1)
+		name.Ntype = ir.TypeNode(name.Type())
+	}
+}
+
+func (r *reader) setValue(name *ir.Name, val constant.Value) {
+	name.SetVal(val)
+	name.Defn = nil
+}
+
+// @@@ Positions
+
+func (r *reader) pos() src.XPos {
+	return base.Ctxt.PosTable.XPos(r.pos0())
+}
+
+func (r *reader) pos0() src.Pos {
+	r.sync(syncPos)
+	if !r.bool() {
+		return src.NoPos
+	}
+
+	posBase := r.posBase()
+	line := r.uint()
+	col := r.uint()
+	return src.MakePos(posBase, line, col)
+}
+
+func (r *reader) posBase() *src.PosBase {
+	return r.inlPosBase(r.p.posBaseIdx(r.reloc(relocPosBase)))
+}
+
+func (pr *pkgReader) posBaseIdx(idx int) *src.PosBase {
+	if b := pr.posBases[idx]; b != nil {
+		return b
+	}
+
+	r := pr.newReader(relocPosBase, idx, syncPosBase)
+	var b *src.PosBase
+
+	fn := r.string()
+	absfn := r.string()
+
+	if r.bool() {
+		b = src.NewFileBase(fn, absfn)
+	} else {
+		pos := r.pos0()
+		line := r.uint()
+		col := r.uint()
+		b = src.NewLinePragmaBase(pos, fn, absfn, line, col)
+	}
+
+	pr.posBases[idx] = b
+	return b
+}
+
+func (r *reader) inlPosBase(oldBase *src.PosBase) *src.PosBase {
+	if r.inlCall == nil {
+		return oldBase
+	}
+
+	if newBase, ok := r.inlPosBases[oldBase]; ok {
+		return newBase
+	}
+
+	newBase := src.NewInliningBase(oldBase, r.inlTreeIndex)
+	r.inlPosBases[oldBase] = newBase
+	return newBase
+}
+
+func (r *reader) updatePos(xpos src.XPos) src.XPos {
+	pos := base.Ctxt.PosTable.Pos(xpos)
+	pos.SetBase(r.inlPosBase(pos.Base()))
+	return base.Ctxt.PosTable.XPos(pos)
+}
+
+func (r *reader) origPos(xpos src.XPos) src.XPos {
+	if r.inlCall == nil {
+		return xpos
+	}
+
+	pos := base.Ctxt.PosTable.Pos(xpos)
+	for old, new := range r.inlPosBases {
+		if pos.Base() == new {
+			pos.SetBase(old)
+			return base.Ctxt.PosTable.XPos(pos)
+		}
+	}
+
+	base.FatalfAt(xpos, "pos base missing from inlPosBases")
+	panic("unreachable")
+}
+
+// @@@ Packages
+
+func (r *reader) pkg() *types.Pkg {
+	r.sync(syncPkg)
+	return r.p.pkgIdx(r.reloc(relocPkg))
+}
+
+func (pr *pkgReader) pkgIdx(idx int) *types.Pkg {
+	if pkg := pr.pkgs[idx]; pkg != nil {
+		return pkg
+	}
+
+	pkg := pr.newReader(relocPkg, idx, syncPkgDef).doPkg()
+	pr.pkgs[idx] = pkg
+	return pkg
+}
+
+func (r *reader) doPkg() *types.Pkg {
+	path := r.string()
+	if path == "builtin" {
+		return types.BuiltinPkg
+	}
+	if path == "" {
+		path = r.p.pkgPath
+	}
+
+	name := r.string()
+	height := r.len()
+
+	pkg := types.NewPkg(path, "")
+
+	if pkg.Name == "" {
+		pkg.Name = name
+	} else {
+		assert(pkg.Name == name)
+	}
+
+	if pkg.Height == 0 {
+		pkg.Height = height
+	} else {
+		assert(pkg.Height == height)
+	}
+
+	return pkg
+}
+
+// @@@ Types
+
+func (r *reader) typ() *types.Type {
+	return r.p.typIdx(r.typInfo(), r.dict)
+}
+
+func (r *reader) typInfo() typeInfo {
+	r.sync(syncType)
+	if r.bool() {
+		return typeInfo{idx: r.len(), derived: true}
+	}
+	return typeInfo{idx: r.reloc(relocType), derived: false}
+}
+
+func (pr *pkgReader) typIdx(info typeInfo, dict *readerDict) *types.Type {
+	idx := info.idx
+	var where **types.Type
+	if info.derived {
+		where = &dict.derivedTypes[idx]
+		idx = dict.derived[idx].idx
+	} else {
+		where = &pr.typs[idx]
+	}
+
+	if typ := *where; typ != nil {
+		return typ
+	}
+
+	r := pr.newReader(relocType, idx, syncTypeIdx)
+	r.dict = dict
+
+	typ := r.doTyp()
+	assert(typ != nil)
+
+	// For recursive type declarations involving interfaces and aliases,
+	// above r.doTyp() call may have already set pr.typs[idx], so just
+	// double check and return the type.
+	//
+	// Example:
+	//
+	//     type F = func(I)
+	//
+	//     type I interface {
+	//         m(F)
+	//     }
+	//
+	// The writer writes data types in following index order:
+	//
+	//     0: func(I)
+	//     1: I
+	//     2: interface{m(func(I))}
+	//
+	// The reader resolves it in following index order:
+	//
+	//     0 -> 1 -> 2 -> 0 -> 1
+	//
+	// and can divide in logically 2 steps:
+	//
+	//  - 0 -> 1     : first time the reader reach type I,
+	//                 it creates new named type with symbol I.
+	//
+	//  - 2 -> 0 -> 1: the reader ends up reaching symbol I again,
+	//                 now the symbol I was setup in above step, so
+	//                 the reader just return the named type.
+	//
+	// Now, the functions called return, the pr.typs looks like below:
+	//
+	//  - 0 -> 1 -> 2 -> 0 : [<T> I <T>]
+	//  - 0 -> 1 -> 2      : [func(I) I <T>]
+	//  - 0 -> 1           : [func(I) I interface { "".m(func("".I)) }]
+	//
+	// The idx 1, corresponding with type I was resolved successfully
+	// after r.doTyp() call.
+
+	if prev := *where; prev != nil {
+		return prev
+	}
+
+	*where = typ
+
+	if !typ.IsUntyped() {
+		types.CheckSize(typ)
+	}
+
+	return typ
+}
+
+func (r *reader) doTyp() *types.Type {
+	switch tag := codeType(r.code(syncType)); tag {
+	default:
+		panic(fmt.Sprintf("unexpected type: %v", tag))
+
+	case typeBasic:
+		return *basics[r.len()]
+
+	case typeNamed:
+		obj := r.obj()
+		assert(obj.Op() == ir.OTYPE)
+		return obj.Type()
+
+	case typeTypeParam:
+		return r.dict.targs[r.len()]
+
+	case typeArray:
+		len := int64(r.uint64())
+		return types.NewArray(r.typ(), len)
+	case typeChan:
+		dir := dirs[r.len()]
+		return types.NewChan(r.typ(), dir)
+	case typeMap:
+		return types.NewMap(r.typ(), r.typ())
+	case typePointer:
+		return types.NewPtr(r.typ())
+	case typeSignature:
+		return r.signature(types.LocalPkg, nil)
+	case typeSlice:
+		return types.NewSlice(r.typ())
+	case typeStruct:
+		return r.structType()
+	case typeInterface:
+		return r.interfaceType()
+	}
+}
+
+func (r *reader) interfaceType() *types.Type {
+	tpkg := types.LocalPkg // TODO(mdempsky): Remove after iexport is gone.
+
+	nmethods, nembeddeds := r.len(), r.len()
+
+	fields := make([]*types.Field, nmethods+nembeddeds)
+	methods, embeddeds := fields[:nmethods], fields[nmethods:]
+
+	for i := range methods {
+		pos := r.pos()
+		pkg, sym := r.selector()
+		tpkg = pkg
+		mtyp := r.signature(pkg, typecheck.FakeRecv())
+		methods[i] = types.NewField(pos, sym, mtyp)
+	}
+	for i := range embeddeds {
+		embeddeds[i] = types.NewField(src.NoXPos, nil, r.typ())
+	}
+
+	if len(fields) == 0 {
+		return types.Types[types.TINTER] // empty interface
+	}
+	return r.needWrapper(types.NewInterface(tpkg, fields))
+}
+
+func (r *reader) structType() *types.Type {
+	tpkg := types.LocalPkg // TODO(mdempsky): Remove after iexport is gone.
+	fields := make([]*types.Field, r.len())
+	for i := range fields {
+		pos := r.pos()
+		pkg, sym := r.selector()
+		tpkg = pkg
+		ftyp := r.typ()
+		tag := r.string()
+		embedded := r.bool()
+
+		f := types.NewField(pos, sym, ftyp)
+		f.Note = tag
+		if embedded {
+			f.Embedded = 1
+		}
+		fields[i] = f
+	}
+	return r.needWrapper(types.NewStruct(tpkg, fields))
+}
+
+func (r *reader) signature(tpkg *types.Pkg, recv *types.Field) *types.Type {
+	r.sync(syncSignature)
+
+	params := r.params(&tpkg)
+	results := r.params(&tpkg)
+	if r.bool() { // variadic
+		params[len(params)-1].SetIsDDD(true)
+	}
+
+	return types.NewSignature(tpkg, recv, nil, params, results)
+}
+
+func (r *reader) params(tpkg **types.Pkg) []*types.Field {
+	r.sync(syncParams)
+	fields := make([]*types.Field, r.len())
+	for i := range fields {
+		*tpkg, fields[i] = r.param()
+	}
+	return fields
+}
+
+func (r *reader) param() (*types.Pkg, *types.Field) {
+	r.sync(syncParam)
+
+	pos := r.pos()
+	pkg, sym := r.localIdent()
+	typ := r.typ()
+
+	return pkg, types.NewField(pos, sym, typ)
+}
+
+// @@@ Objects
+
+var objReader = map[*types.Sym]pkgReaderIndex{}
+
+func (r *reader) obj() ir.Node {
+	r.sync(syncObject)
+
+	if r.bool() {
+		idx := r.len()
+		obj := r.dict.funcsObj[idx]
+		if obj == nil {
+			fn := r.dict.funcs[idx]
+			targs := make([]*types.Type, len(fn.explicits))
+			for i, targ := range fn.explicits {
+				targs[i] = r.p.typIdx(targ, r.dict)
+			}
+
+			obj = r.p.objIdx(fn.idx, nil, targs)
+			assert(r.dict.funcsObj[idx] == nil)
+			r.dict.funcsObj[idx] = obj
+		}
+		return obj
+	}
+
+	idx := r.reloc(relocObj)
+
+	explicits := make([]*types.Type, r.len())
+	for i := range explicits {
+		explicits[i] = r.typ()
+	}
+
+	var implicits []*types.Type
+	if r.dict != nil {
+		implicits = r.dict.targs
+	}
+
+	return r.p.objIdx(idx, implicits, explicits)
+}
+
+func (pr *pkgReader) objIdx(idx int, implicits, explicits []*types.Type) ir.Node {
+	rname := pr.newReader(relocName, idx, syncObject1)
+	_, sym := rname.qualifiedIdent()
+	tag := codeObj(rname.code(syncCodeObj))
+
+	if tag == objStub {
+		assert(!sym.IsBlank())
+		switch sym.Pkg {
+		case types.BuiltinPkg, ir.Pkgs.Unsafe:
+			return sym.Def.(ir.Node)
+		}
+		if pri, ok := objReader[sym]; ok {
+			return pri.pr.objIdx(pri.idx, nil, explicits)
+		}
+		if haveLegacyImports {
+			assert(len(explicits) == 0)
+			return typecheck.Resolve(ir.NewIdent(src.NoXPos, sym))
+		}
+		base.Fatalf("unresolved stub: %v", sym)
+	}
+
+	dict := pr.objDictIdx(sym, idx, implicits, explicits)
+
+	r := pr.newReader(relocObj, idx, syncObject1)
+	r.ext = pr.newReader(relocObjExt, idx, syncObject1)
+
+	r.dict = dict
+	r.ext.dict = dict
+
+	sym = r.mangle(sym)
+	if !sym.IsBlank() && sym.Def != nil {
+		return sym.Def.(*ir.Name)
+	}
+
+	do := func(op ir.Op, hasTParams bool) *ir.Name {
+		pos := r.pos()
+		if hasTParams {
+			r.typeParamNames()
+		}
+
+		name := ir.NewDeclNameAt(pos, op, sym)
+		name.Class = ir.PEXTERN // may be overridden later
+		if !sym.IsBlank() {
+			if sym.Def != nil {
+				base.FatalfAt(name.Pos(), "already have a definition for %v", name)
+			}
+			assert(sym.Def == nil)
+			sym.Def = name
+		}
+		return name
+	}
+
+	switch tag {
+	default:
+		panic("unexpected object")
+
+	case objAlias:
+		name := do(ir.OTYPE, false)
+		r.setType(name, r.typ())
+		name.SetAlias(true)
+		return name
+
+	case objConst:
+		name := do(ir.OLITERAL, false)
+		typ, val := r.value()
+		r.setType(name, typ)
+		r.setValue(name, val)
+		return name
+
+	case objFunc:
+		if sym.Name == "init" {
+			sym = renameinit()
+		}
+		name := do(ir.ONAME, true)
+		r.setType(name, r.signature(sym.Pkg, nil))
+
+		name.Func = ir.NewFunc(r.pos())
+		name.Func.Nname = name
+
+		r.ext.funcExt(name)
+		return name
+
+	case objType:
+		name := do(ir.OTYPE, true)
+		typ := types.NewNamed(name)
+		r.setType(name, typ)
+
+		// Important: We need to do this before SetUnderlying.
+		r.ext.typeExt(name)
+
+		// We need to defer CheckSize until we've called SetUnderlying to
+		// handle recursive types.
+		types.DeferCheckSize()
+		typ.SetUnderlying(r.typ())
+		types.ResumeCheckSize()
+
+		methods := make([]*types.Field, r.len())
+		for i := range methods {
+			methods[i] = r.method()
+		}
+		if len(methods) != 0 {
+			typ.Methods().Set(methods)
+		}
+
+		if !typ.IsPtr() {
+			r.needWrapper(typ)
+		}
+
+		return name
+
+	case objVar:
+		name := do(ir.ONAME, false)
+		r.setType(name, r.typ())
+		r.ext.varExt(name)
+		return name
+	}
+}
+
+func (r *reader) mangle(sym *types.Sym) *types.Sym {
+	if !r.hasTypeParams() {
+		return sym
+	}
+
+	var buf bytes.Buffer
+	buf.WriteString(sym.Name)
+	buf.WriteByte('[')
+	for i, targ := range r.dict.targs {
+		if i > 0 {
+			if i == r.dict.implicits {
+				buf.WriteByte(';')
+			} else {
+				buf.WriteByte(',')
+			}
+		}
+		buf.WriteString(targ.LinkString())
+	}
+	buf.WriteByte(']')
+	return sym.Pkg.Lookup(buf.String())
+}
+
+func (pr *pkgReader) objDictIdx(sym *types.Sym, idx int, implicits, explicits []*types.Type) *readerDict {
+	r := pr.newReader(relocObjDict, idx, syncObject1)
+
+	var dict readerDict
+
+	nimplicits := r.len()
+	nexplicits := r.len()
+
+	if nimplicits > len(implicits) || nexplicits != len(explicits) {
+		base.Fatalf("%v has %v+%v params, but instantiated with %v+%v args", sym, nimplicits, nexplicits, len(implicits), len(explicits))
+	}
+
+	dict.targs = append(implicits[:nimplicits:nimplicits], explicits...)
+	dict.implicits = nimplicits
+
+	// For stenciling, we can just skip over the type parameters.
+	for range dict.targs[dict.implicits:] {
+		// Skip past bounds without actually evaluating them.
+		r.sync(syncType)
+		if r.bool() {
+			r.len()
+		} else {
+			r.reloc(relocType)
+		}
+	}
+
+	dict.derived = make([]derivedInfo, r.len())
+	dict.derivedTypes = make([]*types.Type, len(dict.derived))
+	for i := range dict.derived {
+		dict.derived[i] = derivedInfo{r.reloc(relocType), r.bool()}
+	}
+
+	dict.funcs = make([]objInfo, r.len())
+	dict.funcsObj = make([]ir.Node, len(dict.funcs))
+	for i := range dict.funcs {
+		objIdx := r.reloc(relocObj)
+		targs := make([]typeInfo, r.len())
+		for j := range targs {
+			targs[j] = r.typInfo()
+		}
+		dict.funcs[i] = objInfo{idx: objIdx, explicits: targs}
+	}
+
+	return &dict
+}
+
+func (r *reader) typeParamNames() {
+	r.sync(syncTypeParamNames)
+
+	for range r.dict.targs[r.dict.implicits:] {
+		r.pos()
+		r.localIdent()
+	}
+}
+
+func (r *reader) value() (*types.Type, constant.Value) {
+	r.sync(syncValue)
+	typ := r.typ()
+	return typ, FixValue(typ, r.rawValue())
+}
+
+func (r *reader) method() *types.Field {
+	r.sync(syncMethod)
+	pos := r.pos()
+	pkg, sym := r.selector()
+	r.typeParamNames()
+	_, recv := r.param()
+	typ := r.signature(pkg, recv)
+
+	fnsym := sym
+	fnsym = ir.MethodSym(recv.Type, fnsym)
+	name := ir.NewNameAt(pos, fnsym)
+	r.setType(name, typ)
+
+	name.Func = ir.NewFunc(r.pos())
+	name.Func.Nname = name
+
+	r.ext.funcExt(name)
+
+	meth := types.NewField(name.Func.Pos(), sym, typ)
+	meth.Nname = name
+	meth.SetNointerface(name.Func.Pragma&ir.Nointerface != 0)
+
+	return meth
+}
+
+func (r *reader) qualifiedIdent() (pkg *types.Pkg, sym *types.Sym) {
+	r.sync(syncSym)
+	pkg = r.pkg()
+	if name := r.string(); name != "" {
+		sym = pkg.Lookup(name)
+	}
+	return
+}
+
+func (r *reader) localIdent() (pkg *types.Pkg, sym *types.Sym) {
+	r.sync(syncLocalIdent)
+	pkg = r.pkg()
+	if name := r.string(); name != "" {
+		sym = pkg.Lookup(name)
+	}
+	return
+}
+
+func (r *reader) selector() (origPkg *types.Pkg, sym *types.Sym) {
+	r.sync(syncSelector)
+	origPkg = r.pkg()
+	name := r.string()
+	pkg := origPkg
+	if types.IsExported(name) {
+		pkg = types.LocalPkg
+	}
+	sym = pkg.Lookup(name)
+	return
+}
+
+func (r *reader) hasTypeParams() bool {
+	return r.dict.hasTypeParams()
+}
+
+func (dict *readerDict) hasTypeParams() bool {
+	return dict != nil && len(dict.targs) != 0
+}
+
+// @@@ Compiler extensions
+
+func (r *reader) funcExt(name *ir.Name) {
+	r.sync(syncFuncExt)
+
+	name.Class = 0 // so MarkFunc doesn't complain
+	ir.MarkFunc(name)
+
+	fn := name.Func
+
+	// XXX: Workaround because linker doesn't know how to copy Pos.
+	if !fn.Pos().IsKnown() {
+		fn.SetPos(name.Pos())
+	}
+
+	// Normally, we only compile local functions, which saves redundant compilation work.
+	// n.Defn is not nil for local functions, and is nil for imported function. But for
+	// generic functions, we might have an instantiation that no other package has seen before.
+	// So we need to be conservative and compile it again.
+	//
+	// That's why name.Defn is set here, so ir.VisitFuncsBottomUp can analyze function.
+	// TODO(mdempsky,cuonglm): find a cleaner way to handle this.
+	if name.Sym().Pkg == types.LocalPkg || r.hasTypeParams() {
+		name.Defn = fn
+	}
+
+	fn.Pragma = r.pragmaFlag()
+	r.linkname(name)
+
+	typecheck.Func(fn)
+
+	if r.bool() {
+		fn.ABI = obj.ABI(r.uint64())
+
+		// Escape analysis.
+		for _, fs := range &types.RecvsParams {
+			for _, f := range fs(name.Type()).FieldSlice() {
+				f.Note = r.string()
+			}
+		}
+
+		if r.bool() {
+			fn.Inl = &ir.Inline{
+				Cost:            int32(r.len()),
+				CanDelayResults: r.bool(),
+			}
+			r.addBody(name.Func)
+		}
+	} else {
+		r.addBody(name.Func)
+	}
+	r.sync(syncEOF)
+}
+
+func (r *reader) typeExt(name *ir.Name) {
+	r.sync(syncTypeExt)
+
+	typ := name.Type()
+
+	if r.hasTypeParams() {
+		// Set "RParams" (really type arguments here, not parameters) so
+		// this type is treated as "fully instantiated". This ensures the
+		// type descriptor is written out as DUPOK and method wrappers are
+		// generated even for imported types.
+		var targs []*types.Type
+		targs = append(targs, r.dict.targs...)
+		typ.SetRParams(targs)
+	}
+
+	name.SetPragma(r.pragmaFlag())
+	if name.Pragma()&ir.NotInHeap != 0 {
+		typ.SetNotInHeap(true)
+	}
+
+	typecheck.SetBaseTypeIndex(typ, r.int64(), r.int64())
+}
+
+func (r *reader) varExt(name *ir.Name) {
+	r.sync(syncVarExt)
+	r.linkname(name)
+}
+
+func (r *reader) linkname(name *ir.Name) {
+	assert(name.Op() == ir.ONAME)
+	r.sync(syncLinkname)
+
+	if idx := r.int64(); idx >= 0 {
+		lsym := name.Linksym()
+		lsym.SymIdx = int32(idx)
+		lsym.Set(obj.AttrIndexed, true)
+	} else {
+		name.Sym().Linkname = r.string()
+	}
+}
+
+func (r *reader) pragmaFlag() ir.PragmaFlag {
+	r.sync(syncPragma)
+	return ir.PragmaFlag(r.int())
+}
+
+// @@@ Function bodies
+
+// bodyReader tracks where the serialized IR for a function's body can
+// be found.
+var bodyReader = map[*ir.Func]pkgReaderIndex{}
+
+// todoBodies holds the list of function bodies that still need to be
+// constructed.
+var todoBodies []*ir.Func
+
+func (r *reader) addBody(fn *ir.Func) {
+	pri := pkgReaderIndex{r.p, r.reloc(relocBody), r.dict}
+	bodyReader[fn] = pri
+
+	if r.curfn == nil {
+		todoBodies = append(todoBodies, fn)
+		return
+	}
+
+	pri.funcBody(fn)
+}
+
+func (pri pkgReaderIndex) funcBody(fn *ir.Func) {
+	r := pri.asReader(relocBody, syncFuncBody)
+	r.funcBody(fn)
+}
+
+func (r *reader) funcBody(fn *ir.Func) {
+	r.curfn = fn
+	r.closureVars = fn.ClosureVars
+
+	ir.WithFunc(fn, func() {
+		r.funcargs(fn)
+
+		if !r.bool() {
+			return
+		}
+
+		body := r.stmts()
+		if body == nil {
+			pos := src.NoXPos
+			if quirksMode() {
+				pos = funcParamsEndPos(fn)
+			}
+			body = []ir.Node{typecheck.Stmt(ir.NewBlockStmt(pos, nil))}
+		}
+		fn.Body = body
+		fn.Endlineno = r.pos()
+	})
+
+	r.marker.WriteTo(fn)
+}
+
+func (r *reader) funcargs(fn *ir.Func) {
+	sig := fn.Nname.Type()
+
+	if recv := sig.Recv(); recv != nil {
+		r.funcarg(recv, recv.Sym, ir.PPARAM)
+	}
+	for _, param := range sig.Params().FieldSlice() {
+		r.funcarg(param, param.Sym, ir.PPARAM)
+	}
+
+	for i, param := range sig.Results().FieldSlice() {
+		sym := types.OrigSym(param.Sym)
+
+		if sym == nil || sym.IsBlank() {
+			prefix := "~r"
+			if r.inlCall != nil {
+				prefix = "~R"
+			} else if sym != nil {
+				prefix = "~b"
+			}
+			sym = typecheck.LookupNum(prefix, i)
+		}
+
+		r.funcarg(param, sym, ir.PPARAMOUT)
+	}
+}
+
+func (r *reader) funcarg(param *types.Field, sym *types.Sym, ctxt ir.Class) {
+	if sym == nil {
+		assert(ctxt == ir.PPARAM)
+		if r.inlCall != nil {
+			r.inlvars.Append(ir.BlankNode)
+		}
+		return
+	}
+
+	name := ir.NewNameAt(r.updatePos(param.Pos), sym)
+	r.setType(name, param.Type)
+	r.addLocal(name, ctxt)
+
+	if r.inlCall == nil {
+		if !r.funarghack {
+			param.Sym = sym
+			param.Nname = name
+		}
+	} else {
+		if ctxt == ir.PPARAMOUT {
+			r.retvars.Append(name)
+		} else {
+			r.inlvars.Append(name)
+		}
+	}
+}
+
+func (r *reader) addLocal(name *ir.Name, ctxt ir.Class) {
+	assert(ctxt == ir.PAUTO || ctxt == ir.PPARAM || ctxt == ir.PPARAMOUT)
+
+	r.sync(syncAddLocal)
+	if enableSync {
+		want := r.int()
+		if have := len(r.locals); have != want {
+			base.FatalfAt(name.Pos(), "locals table has desynced")
+		}
+	}
+
+	name.SetUsed(true)
+	r.locals = append(r.locals, name)
+
+	// TODO(mdempsky): Move earlier.
+	if ir.IsBlank(name) {
+		return
+	}
+
+	if r.inlCall != nil {
+		if ctxt == ir.PAUTO {
+			name.SetInlLocal(true)
+		} else {
+			name.SetInlFormal(true)
+			ctxt = ir.PAUTO
+		}
+
+		// TODO(mdempsky): Rethink this hack.
+		if strings.HasPrefix(name.Sym().Name, "~") || base.Flag.GenDwarfInl == 0 {
+			name.SetPos(r.inlCall.Pos())
+			name.SetInlFormal(false)
+			name.SetInlLocal(false)
+		}
+	}
+
+	name.Class = ctxt
+	name.Curfn = r.curfn
+
+	r.curfn.Dcl = append(r.curfn.Dcl, name)
+
+	if ctxt == ir.PAUTO {
+		name.SetFrameOffset(0)
+	}
+}
+
+func (r *reader) useLocal() *ir.Name {
+	r.sync(syncUseObjLocal)
+	if r.bool() {
+		return r.locals[r.len()]
+	}
+	return r.closureVars[r.len()]
+}
+
+func (r *reader) openScope() {
+	r.sync(syncOpenScope)
+	pos := r.pos()
+
+	if base.Flag.Dwarf {
+		r.scopeVars = append(r.scopeVars, len(r.curfn.Dcl))
+		r.marker.Push(pos)
+	}
+}
+
+func (r *reader) closeScope() {
+	r.sync(syncCloseScope)
+	r.lastCloseScopePos = r.pos()
+
+	r.closeAnotherScope()
+}
+
+// closeAnotherScope is like closeScope, but it reuses the same mark
+// position as the last closeScope call. This is useful for "for" and
+// "if" statements, as their implicit blocks always end at the same
+// position as an explicit block.
+func (r *reader) closeAnotherScope() {
+	r.sync(syncCloseAnotherScope)
+
+	if base.Flag.Dwarf {
+		scopeVars := r.scopeVars[len(r.scopeVars)-1]
+		r.scopeVars = r.scopeVars[:len(r.scopeVars)-1]
+
+		// Quirkish: noder decides which scopes to keep before
+		// typechecking, whereas incremental typechecking during IR
+		// construction can result in new autotemps being allocated. To
+		// produce identical output, we ignore autotemps here for the
+		// purpose of deciding whether to retract the scope.
+		//
+		// This is important for net/http/fcgi, because it contains:
+		//
+		//	var body io.ReadCloser
+		//	if len(content) > 0 {
+		//		body, req.pw = io.Pipe()
+		//	} else { … }
+		//
+		// Notably, io.Pipe is inlinable, and inlining it introduces a ~R0
+		// variable at the call site.
+		//
+		// Noder does not preserve the scope where the io.Pipe() call
+		// resides, because it doesn't contain any declared variables in
+		// source. So the ~R0 variable ends up being assigned to the
+		// enclosing scope instead.
+		//
+		// However, typechecking this assignment also introduces
+		// autotemps, because io.Pipe's results need conversion before
+		// they can be assigned to their respective destination variables.
+		//
+		// TODO(mdempsky): We should probably just keep all scopes, and
+		// let dwarfgen take care of pruning them instead.
+		retract := true
+		for _, n := range r.curfn.Dcl[scopeVars:] {
+			if !n.AutoTemp() {
+				retract = false
+				break
+			}
+		}
+
+		if retract {
+			// no variables were declared in this scope, so we can retract it.
+			r.marker.Unpush()
+		} else {
+			r.marker.Pop(r.lastCloseScopePos)
+		}
+	}
+}
+
+// @@@ Statements
+
+func (r *reader) stmt() ir.Node {
+	switch stmts := r.stmts(); len(stmts) {
+	case 0:
+		return nil
+	case 1:
+		return stmts[0]
+	default:
+		return ir.NewBlockStmt(stmts[0].Pos(), stmts)
+	}
+}
+
+func (r *reader) stmts() []ir.Node {
+	assert(ir.CurFunc == r.curfn)
+	var res ir.Nodes
+
+	r.sync(syncStmts)
+	for {
+		tag := codeStmt(r.code(syncStmt1))
+		if tag == stmtEnd {
+			r.sync(syncStmtsEnd)
+			return res
+		}
+
+		if n := r.stmt1(tag, &res); n != nil {
+			res.Append(typecheck.Stmt(n))
+		}
+	}
+}
+
+func (r *reader) stmt1(tag codeStmt, out *ir.Nodes) ir.Node {
+	var label *types.Sym
+	if n := len(*out); n > 0 {
+		if ls, ok := (*out)[n-1].(*ir.LabelStmt); ok {
+			label = ls.Label
+		}
+	}
+
+	switch tag {
+	default:
+		panic("unexpected statement")
+
+	case stmtAssign:
+		pos := r.pos()
+
+		// TODO(mdempsky): After quirks mode is gone, swap these
+		// statements so we visit LHS before RHS again.
+		rhs := r.exprList()
+		names, lhs := r.assignList()
+
+		if len(rhs) == 0 {
+			for _, name := range names {
+				as := ir.NewAssignStmt(pos, name, nil)
+				as.PtrInit().Append(ir.NewDecl(pos, ir.ODCL, name))
+				out.Append(typecheck.Stmt(as))
+			}
+			return nil
+		}
+
+		if len(lhs) == 1 && len(rhs) == 1 {
+			n := ir.NewAssignStmt(pos, lhs[0], rhs[0])
+			n.Def = r.initDefn(n, names)
+			return n
+		}
+
+		n := ir.NewAssignListStmt(pos, ir.OAS2, lhs, rhs)
+		n.Def = r.initDefn(n, names)
+		return n
+
+	case stmtAssignOp:
+		op := r.op()
+		lhs := r.expr()
+		pos := r.pos()
+		rhs := r.expr()
+		return ir.NewAssignOpStmt(pos, op, lhs, rhs)
+
+	case stmtIncDec:
+		op := r.op()
+		lhs := r.expr()
+		pos := r.pos()
+		n := ir.NewAssignOpStmt(pos, op, lhs, ir.NewBasicLit(pos, one))
+		n.IncDec = true
+		return n
+
+	case stmtBlock:
+		out.Append(r.blockStmt()...)
+		return nil
+
+	case stmtBranch:
+		pos := r.pos()
+		op := r.op()
+		sym := r.optLabel()
+		return ir.NewBranchStmt(pos, op, sym)
+
+	case stmtCall:
+		pos := r.pos()
+		op := r.op()
+		call := r.expr()
+		return ir.NewGoDeferStmt(pos, op, call)
+
+	case stmtExpr:
+		return r.expr()
+
+	case stmtFor:
+		return r.forStmt(label)
+
+	case stmtIf:
+		return r.ifStmt()
+
+	case stmtLabel:
+		pos := r.pos()
+		sym := r.label()
+		return ir.NewLabelStmt(pos, sym)
+
+	case stmtReturn:
+		pos := r.pos()
+		results := r.exprList()
+		return ir.NewReturnStmt(pos, results)
+
+	case stmtSelect:
+		return r.selectStmt(label)
+
+	case stmtSend:
+		pos := r.pos()
+		ch := r.expr()
+		value := r.expr()
+		return ir.NewSendStmt(pos, ch, value)
+
+	case stmtSwitch:
+		return r.switchStmt(label)
+
+	case stmtTypeDeclHack:
+		// fake "type _ = int" declaration to prevent inlining in quirks mode.
+		assert(quirksMode())
+
+		name := ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, ir.BlankNode.Sym())
+		name.SetAlias(true)
+		r.setType(name, types.Types[types.TINT])
+
+		n := ir.NewDecl(src.NoXPos, ir.ODCLTYPE, name)
+		n.SetTypecheck(1)
+		return n
+	}
+}
+
+func (r *reader) assignList() ([]*ir.Name, []ir.Node) {
+	lhs := make([]ir.Node, r.len())
+	var names []*ir.Name
+
+	for i := range lhs {
+		if r.bool() {
+			pos := r.pos()
+			_, sym := r.localIdent()
+			typ := r.typ()
+
+			name := ir.NewNameAt(pos, sym)
+			lhs[i] = name
+			names = append(names, name)
+			r.setType(name, typ)
+			r.addLocal(name, ir.PAUTO)
+			continue
+		}
+
+		lhs[i] = r.expr()
+	}
+
+	return names, lhs
+}
+
+func (r *reader) blockStmt() []ir.Node {
+	r.sync(syncBlockStmt)
+	r.openScope()
+	stmts := r.stmts()
+	r.closeScope()
+	return stmts
+}
+
+func (r *reader) forStmt(label *types.Sym) ir.Node {
+	r.sync(syncForStmt)
+
+	r.openScope()
+
+	if r.bool() {
+		pos := r.pos()
+
+		// TODO(mdempsky): After quirks mode is gone, swap these
+		// statements so we read LHS before X again.
+		x := r.expr()
+		names, lhs := r.assignList()
+
+		body := r.blockStmt()
+		r.closeAnotherScope()
+
+		rang := ir.NewRangeStmt(pos, nil, nil, x, body)
+		if len(lhs) >= 1 {
+			rang.Key = lhs[0]
+			if len(lhs) >= 2 {
+				rang.Value = lhs[1]
+			}
+		}
+		rang.Def = r.initDefn(rang, names)
+		rang.Label = label
+		return rang
+	}
+
+	pos := r.pos()
+	init := r.stmt()
+	cond := r.expr()
+	post := r.stmt()
+	body := r.blockStmt()
+	r.closeAnotherScope()
+
+	stmt := ir.NewForStmt(pos, init, cond, post, body)
+	stmt.Label = label
+	return stmt
+}
+
+func (r *reader) ifStmt() ir.Node {
+	r.sync(syncIfStmt)
+	r.openScope()
+	pos := r.pos()
+	init := r.stmts()
+	cond := r.expr()
+	then := r.blockStmt()
+	els := r.stmts()
+	n := ir.NewIfStmt(pos, cond, then, els)
+	n.SetInit(init)
+	r.closeAnotherScope()
+	return n
+}
+
+func (r *reader) selectStmt(label *types.Sym) ir.Node {
+	r.sync(syncSelectStmt)
+
+	pos := r.pos()
+	clauses := make([]*ir.CommClause, r.len())
+	for i := range clauses {
+		if i > 0 {
+			r.closeScope()
+		}
+		r.openScope()
+
+		pos := r.pos()
+		comm := r.stmt()
+		body := r.stmts()
+
+		clauses[i] = ir.NewCommStmt(pos, comm, body)
+	}
+	if len(clauses) > 0 {
+		r.closeScope()
+	}
+	n := ir.NewSelectStmt(pos, clauses)
+	n.Label = label
+	return n
+}
+
+func (r *reader) switchStmt(label *types.Sym) ir.Node {
+	r.sync(syncSwitchStmt)
+
+	r.openScope()
+	pos := r.pos()
+	init := r.stmt()
+
+	var tag ir.Node
+	if r.bool() {
+		pos := r.pos()
+		var ident *ir.Ident
+		if r.bool() {
+			pos := r.pos()
+			sym := typecheck.Lookup(r.string())
+			ident = ir.NewIdent(pos, sym)
+		}
+		x := r.expr()
+		tag = ir.NewTypeSwitchGuard(pos, ident, x)
+	} else {
+		tag = r.expr()
+	}
+
+	tswitch, ok := tag.(*ir.TypeSwitchGuard)
+	if ok && tswitch.Tag == nil {
+		tswitch = nil
+	}
+
+	clauses := make([]*ir.CaseClause, r.len())
+	for i := range clauses {
+		if i > 0 {
+			r.closeScope()
+		}
+		r.openScope()
+
+		pos := r.pos()
+		cases := r.exprList()
+
+		clause := ir.NewCaseStmt(pos, cases, nil)
+		if tswitch != nil {
+			pos := r.pos()
+			typ := r.typ()
+
+			name := ir.NewNameAt(pos, tswitch.Tag.Sym())
+			r.setType(name, typ)
+			r.addLocal(name, ir.PAUTO)
+			clause.Var = name
+			name.Defn = tswitch
+		}
+
+		clause.Body = r.stmts()
+		clauses[i] = clause
+	}
+	if len(clauses) > 0 {
+		r.closeScope()
+	}
+	r.closeScope()
+
+	n := ir.NewSwitchStmt(pos, tag, clauses)
+	n.Label = label
+	if init != nil {
+		n.SetInit([]ir.Node{init})
+	}
+	return n
+}
+
+func (r *reader) label() *types.Sym {
+	r.sync(syncLabel)
+	name := r.string()
+	if r.inlCall != nil {
+		name = fmt.Sprintf("~%s·%d", name, inlgen)
+	}
+	return typecheck.Lookup(name)
+}
+
+func (r *reader) optLabel() *types.Sym {
+	r.sync(syncOptLabel)
+	if r.bool() {
+		return r.label()
+	}
+	return nil
+}
+
+// initDefn marks the given names as declared by defn and populates
+// its Init field with ODCL nodes. It then reports whether any names
+// were so declared, which can be used to initialize defn.Def.
+func (r *reader) initDefn(defn ir.InitNode, names []*ir.Name) bool {
+	if len(names) == 0 {
+		return false
+	}
+
+	init := make([]ir.Node, len(names))
+	for i, name := range names {
+		name.Defn = defn
+		init[i] = ir.NewDecl(name.Pos(), ir.ODCL, name)
+	}
+	defn.SetInit(init)
+	return true
+}
+
+// @@@ Expressions
+
+// expr reads and returns a typechecked expression.
+func (r *reader) expr() (res ir.Node) {
+	defer func() {
+		if res != nil && res.Typecheck() == 0 {
+			base.FatalfAt(res.Pos(), "%v missed typecheck", res)
+		}
+	}()
+
+	switch tag := codeExpr(r.code(syncExpr)); tag {
+	default:
+		panic("unhandled expression")
+
+	case exprNone:
+		return nil
+
+	case exprBlank:
+		// blank only allowed in LHS of assignments
+		// TODO(mdempsky): Handle directly in assignList instead?
+		return typecheck.AssignExpr(ir.BlankNode)
+
+	case exprLocal:
+		return typecheck.Expr(r.useLocal())
+
+	case exprName:
+		// Callee instead of Expr allows builtins
+		// TODO(mdempsky): Handle builtins directly in exprCall, like method calls?
+		return typecheck.Callee(r.obj())
+
+	case exprType:
+		// TODO(mdempsky): ir.TypeNode should probably return a typecheck'd node.
+		n := ir.TypeNode(r.typ())
+		n.SetTypecheck(1)
+		return n
+
+	case exprConst:
+		pos := r.pos()
+		typ, val := r.value()
+		op := r.op()
+		orig := r.string()
+		return typecheck.Expr(OrigConst(pos, typ, val, op, orig))
+
+	case exprCompLit:
+		return r.compLit()
+
+	case exprFuncLit:
+		return r.funcLit()
+
+	case exprSelector:
+		x := r.expr()
+		pos := r.pos()
+		_, sym := r.selector()
+		return typecheck.Expr(ir.NewSelectorExpr(pos, ir.OXDOT, x, sym))
+
+	case exprIndex:
+		x := r.expr()
+		pos := r.pos()
+		index := r.expr()
+		return typecheck.Expr(ir.NewIndexExpr(pos, x, index))
+
+	case exprSlice:
+		x := r.expr()
+		pos := r.pos()
+		var index [3]ir.Node
+		for i := range index {
+			index[i] = r.expr()
+		}
+		op := ir.OSLICE
+		if index[2] != nil {
+			op = ir.OSLICE3
+		}
+		return typecheck.Expr(ir.NewSliceExpr(pos, op, x, index[0], index[1], index[2]))
+
+	case exprAssert:
+		x := r.expr()
+		pos := r.pos()
+		typ := r.expr().(ir.Ntype)
+		return typecheck.Expr(ir.NewTypeAssertExpr(pos, x, typ))
+
+	case exprUnaryOp:
+		op := r.op()
+		pos := r.pos()
+		x := r.expr()
+
+		switch op {
+		case ir.OADDR:
+			return typecheck.Expr(typecheck.NodAddrAt(pos, x))
+		case ir.ODEREF:
+			return typecheck.Expr(ir.NewStarExpr(pos, x))
+		}
+		return typecheck.Expr(ir.NewUnaryExpr(pos, op, x))
+
+	case exprBinaryOp:
+		op := r.op()
+		x := r.expr()
+		pos := r.pos()
+		y := r.expr()
+
+		switch op {
+		case ir.OANDAND, ir.OOROR:
+			return typecheck.Expr(ir.NewLogicalExpr(pos, op, x, y))
+		}
+		return typecheck.Expr(ir.NewBinaryExpr(pos, op, x, y))
+
+	case exprCall:
+		fun := r.expr()
+		if r.bool() { // method call
+			pos := r.pos()
+			_, sym := r.selector()
+			fun = typecheck.Callee(ir.NewSelectorExpr(pos, ir.OXDOT, fun, sym))
+		}
+		pos := r.pos()
+		args := r.exprs()
+		dots := r.bool()
+		return typecheck.Call(pos, fun, args, dots)
+
+	case exprConvert:
+		typ := r.typ()
+		pos := r.pos()
+		x := r.expr()
+		return typecheck.Expr(ir.NewConvExpr(pos, ir.OCONV, typ, x))
+	}
+}
+
+func (r *reader) compLit() ir.Node {
+	r.sync(syncCompLit)
+	pos := r.pos()
+	typ0 := r.typ()
+
+	typ := typ0
+	if typ.IsPtr() {
+		typ = typ.Elem()
+	}
+	if typ.Kind() == types.TFORW {
+		base.FatalfAt(pos, "unresolved composite literal type: %v", typ)
+	}
+	isStruct := typ.Kind() == types.TSTRUCT
+
+	elems := make([]ir.Node, r.len())
+	for i := range elems {
+		elemp := &elems[i]
+
+		if isStruct {
+			sk := ir.NewStructKeyExpr(r.pos(), typ.Field(r.len()), nil)
+			*elemp, elemp = sk, &sk.Value
+		} else if r.bool() {
+			kv := ir.NewKeyExpr(r.pos(), r.expr(), nil)
+			*elemp, elemp = kv, &kv.Value
+		}
+
+		*elemp = wrapName(r.pos(), r.expr())
+	}
+
+	lit := typecheck.Expr(ir.NewCompLitExpr(pos, ir.OCOMPLIT, ir.TypeNode(typ), elems))
+	if typ0.IsPtr() {
+		lit = typecheck.Expr(typecheck.NodAddrAt(pos, lit))
+		lit.SetType(typ0)
+	}
+	return lit
+}
+
+func wrapName(pos src.XPos, x ir.Node) ir.Node {
+	// These nodes do not carry line numbers.
+	// Introduce a wrapper node to give them the correct line.
+	switch ir.Orig(x).Op() {
+	case ir.OTYPE, ir.OLITERAL:
+		if x.Sym() == nil {
+			break
+		}
+		fallthrough
+	case ir.ONAME, ir.ONONAME, ir.OPACK, ir.ONIL:
+		p := ir.NewParenExpr(pos, x)
+		p.SetImplicit(true)
+		return p
+	}
+	return x
+}
+
+func (r *reader) funcLit() ir.Node {
+	r.sync(syncFuncLit)
+
+	pos := r.pos()
+	typPos := r.pos()
+	xtype2 := r.signature(types.LocalPkg, nil)
+
+	opos := pos
+	if quirksMode() {
+		opos = r.origPos(pos)
+	}
+
+	fn := ir.NewClosureFunc(opos, r.curfn != nil)
+	clo := fn.OClosure
+	ir.NameClosure(clo, r.curfn)
+
+	r.setType(fn.Nname, xtype2)
+	if quirksMode() {
+		fn.Nname.Ntype = ir.TypeNodeAt(typPos, xtype2)
+	}
+	typecheck.Func(fn)
+	r.setType(clo, fn.Type())
+
+	fn.ClosureVars = make([]*ir.Name, 0, r.len())
+	for len(fn.ClosureVars) < cap(fn.ClosureVars) {
+		ir.NewClosureVar(r.pos(), fn, r.useLocal())
+	}
+
+	r.addBody(fn)
+
+	// TODO(mdempsky): Remove hard-coding of typecheck.Target.
+	return ir.UseClosure(clo, typecheck.Target)
+}
+
+func (r *reader) exprList() []ir.Node {
+	r.sync(syncExprList)
+	return r.exprs()
+}
+
+func (r *reader) exprs() []ir.Node {
+	r.sync(syncExprs)
+	nodes := make([]ir.Node, r.len())
+	if len(nodes) == 0 {
+		return nil // TODO(mdempsky): Unclear if this matters.
+	}
+	for i := range nodes {
+		nodes[i] = r.expr()
+	}
+	return nodes
+}
+
+func (r *reader) op() ir.Op {
+	r.sync(syncOp)
+	return ir.Op(r.len())
+}
+
+// @@@ Package initialization
+
+func (r *reader) pkgInit(self *types.Pkg, target *ir.Package) {
+	if quirksMode() {
+		for i, n := 0, r.len(); i < n; i++ {
+			// Eagerly register position bases, so their filenames are
+			// assigned stable indices.
+			posBase := r.posBase()
+			_ = base.Ctxt.PosTable.XPos(src.MakePos(posBase, 0, 0))
+		}
+
+		for i, n := 0, r.len(); i < n; i++ {
+			// Eagerly resolve imported objects, so any filenames registered
+			// in the process are assigned stable indices too.
+			_, sym := r.qualifiedIdent()
+			typecheck.Resolve(ir.NewIdent(src.NoXPos, sym))
+			assert(sym.Def != nil)
+		}
+	}
+
+	cgoPragmas := make([][]string, r.len())
+	for i := range cgoPragmas {
+		cgoPragmas[i] = r.strings()
+	}
+	target.CgoPragmas = cgoPragmas
+
+	r.pkgDecls(target)
+
+	r.sync(syncEOF)
+}
+
+func (r *reader) pkgDecls(target *ir.Package) {
+	r.sync(syncDecls)
+	for {
+		switch code := codeDecl(r.code(syncDecl)); code {
+		default:
+			panic(fmt.Sprintf("unhandled decl: %v", code))
+
+		case declEnd:
+			return
+
+		case declFunc:
+			names := r.pkgObjs(target)
+			assert(len(names) == 1)
+			target.Decls = append(target.Decls, names[0].Func)
+
+		case declMethod:
+			typ := r.typ()
+			_, sym := r.selector()
+
+			method := typecheck.Lookdot1(nil, sym, typ, typ.Methods(), 0)
+			target.Decls = append(target.Decls, method.Nname.(*ir.Name).Func)
+
+		case declVar:
+			pos := r.pos()
+			names := r.pkgObjs(target)
+			values := r.exprList()
+
+			if len(names) > 1 && len(values) == 1 {
+				as := ir.NewAssignListStmt(pos, ir.OAS2, nil, values)
+				for _, name := range names {
+					as.Lhs.Append(name)
+					name.Defn = as
+				}
+				target.Decls = append(target.Decls, as)
+			} else {
+				for i, name := range names {
+					as := ir.NewAssignStmt(pos, name, nil)
+					if i < len(values) {
+						as.Y = values[i]
+					}
+					name.Defn = as
+					target.Decls = append(target.Decls, as)
+				}
+			}
+
+			if n := r.len(); n > 0 {
+				assert(len(names) == 1)
+				embeds := make([]ir.Embed, n)
+				for i := range embeds {
+					embeds[i] = ir.Embed{Pos: r.pos(), Patterns: r.strings()}
+				}
+				names[0].Embed = &embeds
+				target.Embeds = append(target.Embeds, names[0])
+			}
+
+		case declOther:
+			r.pkgObjs(target)
+		}
+	}
+}
+
+func (r *reader) pkgObjs(target *ir.Package) []*ir.Name {
+	r.sync(syncDeclNames)
+	nodes := make([]*ir.Name, r.len())
+	for i := range nodes {
+		r.sync(syncDeclName)
+
+		name := r.obj().(*ir.Name)
+		nodes[i] = name
+
+		sym := name.Sym()
+		if sym.IsBlank() {
+			continue
+		}
+
+		switch name.Class {
+		default:
+			base.FatalfAt(name.Pos(), "unexpected class: %v", name.Class)
+
+		case ir.PEXTERN:
+			target.Externs = append(target.Externs, name)
+
+		case ir.PFUNC:
+			assert(name.Type().Recv() == nil)
+
+			// TODO(mdempsky): Cleaner way to recognize init?
+			if strings.HasPrefix(sym.Name, "init.") {
+				target.Inits = append(target.Inits, name.Func)
+			}
+		}
+
+		if types.IsExported(sym.Name) {
+			assert(!sym.OnExportList())
+			target.Exports = append(target.Exports, name)
+			sym.SetOnExportList(true)
+		}
+
+		if base.Flag.AsmHdr != "" {
+			assert(!sym.Asm())
+			target.Asms = append(target.Asms, name)
+			sym.SetAsm(true)
+		}
+	}
+
+	return nodes
+}
+
+// @@@ Inlining
+
+var inlgen = 0
+
+func InlineCall(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
+	// TODO(mdempsky): Turn callerfn into an explicit parameter.
+	callerfn := ir.CurFunc
+
+	pri, ok := bodyReader[fn]
+	if !ok {
+		// Assume it's an imported function or something that we don't
+		// have access to in quirks mode.
+		if haveLegacyImports {
+			return nil
+		}
+
+		base.FatalfAt(call.Pos(), "missing function body for call to %v", fn)
+	}
+
+	if fn.Inl.Body == nil {
+		expandInline(fn, pri)
+	}
+
+	r := pri.asReader(relocBody, syncFuncBody)
+
+	// TODO(mdempsky): This still feels clumsy. Can we do better?
+	tmpfn := ir.NewFunc(fn.Pos())
+	tmpfn.Nname = ir.NewNameAt(fn.Nname.Pos(), callerfn.Sym())
+	tmpfn.Closgen = callerfn.Closgen
+	defer func() { callerfn.Closgen = tmpfn.Closgen }()
+
+	r.setType(tmpfn.Nname, fn.Type())
+	r.curfn = tmpfn
+
+	r.inlCaller = callerfn
+	r.inlCall = call
+	r.inlFunc = fn
+	r.inlTreeIndex = inlIndex
+	r.inlPosBases = make(map[*src.PosBase]*src.PosBase)
+
+	r.closureVars = make([]*ir.Name, len(r.inlFunc.ClosureVars))
+	for i, cv := range r.inlFunc.ClosureVars {
+		r.closureVars[i] = cv.Outer
+	}
+
+	r.funcargs(fn)
+
+	assert(r.bool()) // have body
+	r.delayResults = fn.Inl.CanDelayResults
+
+	r.retlabel = typecheck.AutoLabel(".i")
+	inlgen++
+
+	init := ir.TakeInit(call)
+
+	// For normal function calls, the function callee expression
+	// may contain side effects. Make sure to preserve these,
+	// if necessary (#42703).
+	if call.Op() == ir.OCALLFUNC {
+		inline.CalleeEffects(&init, call.X)
+	}
+
+	var args ir.Nodes
+	if call.Op() == ir.OCALLMETH {
+		base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+	}
+	args.Append(call.Args...)
+
+	// Create assignment to declare and initialize inlvars.
+	as2 := ir.NewAssignListStmt(call.Pos(), ir.OAS2, r.inlvars, args)
+	as2.Def = true
+	var as2init ir.Nodes
+	for _, name := range r.inlvars {
+		if ir.IsBlank(name) {
+			continue
+		}
+		// TODO(mdempsky): Use inlined position of name.Pos() instead?
+		name := name.(*ir.Name)
+		as2init.Append(ir.NewDecl(call.Pos(), ir.ODCL, name))
+		name.Defn = as2
+	}
+	as2.SetInit(as2init)
+	init.Append(typecheck.Stmt(as2))
+
+	if !r.delayResults {
+		// If not delaying retvars, declare and zero initialize the
+		// result variables now.
+		for _, name := range r.retvars {
+			// TODO(mdempsky): Use inlined position of name.Pos() instead?
+			name := name.(*ir.Name)
+			init.Append(ir.NewDecl(call.Pos(), ir.ODCL, name))
+			ras := ir.NewAssignStmt(call.Pos(), name, nil)
+			init.Append(typecheck.Stmt(ras))
+		}
+	}
+
+	// Add an inline mark just before the inlined body.
+	// This mark is inline in the code so that it's a reasonable spot
+	// to put a breakpoint. Not sure if that's really necessary or not
+	// (in which case it could go at the end of the function instead).
+	// Note issue 28603.
+	init.Append(ir.NewInlineMarkStmt(call.Pos().WithIsStmt(), int64(r.inlTreeIndex)))
+
+	nparams := len(r.curfn.Dcl)
+
+	ir.WithFunc(r.curfn, func() {
+		r.curfn.Body = r.stmts()
+		r.curfn.Endlineno = r.pos()
+
+		deadcode.Func(r.curfn)
+
+		// Replace any "return" statements within the function body.
+		var edit func(ir.Node) ir.Node
+		edit = func(n ir.Node) ir.Node {
+			if ret, ok := n.(*ir.ReturnStmt); ok {
+				n = typecheck.Stmt(r.inlReturn(ret))
+			}
+			ir.EditChildren(n, edit)
+			return n
+		}
+		edit(r.curfn)
+	})
+
+	body := ir.Nodes(r.curfn.Body)
+
+	// Quirk: If deadcode elimination turned a non-empty function into
+	// an empty one, we need to set the position for the empty block
+	// left behind to the the inlined position for src.NoXPos, so that
+	// an empty string gets added into the DWARF file name listing at
+	// the appropriate index.
+	if quirksMode() && len(body) == 1 {
+		if block, ok := body[0].(*ir.BlockStmt); ok && len(block.List) == 0 {
+			block.SetPos(r.updatePos(src.NoXPos))
+		}
+	}
+
+	// Quirkish: We need to eagerly prune variables added during
+	// inlining, but removed by deadcode.FuncBody above. Unused
+	// variables will get removed during stack frame layout anyway, but
+	// len(fn.Dcl) ends up influencing things like autotmp naming.
+
+	used := usedLocals(body)
+
+	for i, name := range r.curfn.Dcl {
+		if i < nparams || used.Has(name) {
+			name.Curfn = callerfn
+			callerfn.Dcl = append(callerfn.Dcl, name)
+
+			// Quirkish. TODO(mdempsky): Document why.
+			if name.AutoTemp() {
+				name.SetEsc(ir.EscUnknown)
+
+				if base.Flag.GenDwarfInl != 0 {
+					name.SetInlLocal(true)
+				} else {
+					name.SetPos(r.inlCall.Pos())
+				}
+			}
+		}
+	}
+
+	body.Append(ir.NewLabelStmt(call.Pos(), r.retlabel))
+
+	res := ir.NewInlinedCallExpr(call.Pos(), body, append([]ir.Node(nil), r.retvars...))
+	res.SetInit(init)
+	res.SetType(call.Type())
+	res.SetTypecheck(1)
+
+	// Inlining shouldn't add any functions to todoBodies.
+	assert(len(todoBodies) == 0)
+
+	return res
+}
+
+// inlReturn returns a statement that can substitute for the given
+// return statement when inlining.
+func (r *reader) inlReturn(ret *ir.ReturnStmt) *ir.BlockStmt {
+	pos := r.inlCall.Pos()
+
+	block := ir.TakeInit(ret)
+
+	if results := ret.Results; len(results) != 0 {
+		assert(len(r.retvars) == len(results))
+
+		as2 := ir.NewAssignListStmt(pos, ir.OAS2, append([]ir.Node(nil), r.retvars...), ret.Results)
+
+		if r.delayResults {
+			for _, name := range r.retvars {
+				// TODO(mdempsky): Use inlined position of name.Pos() instead?
+				name := name.(*ir.Name)
+				block.Append(ir.NewDecl(pos, ir.ODCL, name))
+				name.Defn = as2
+			}
+		}
+
+		block.Append(as2)
+	}
+
+	block.Append(ir.NewBranchStmt(pos, ir.OGOTO, r.retlabel))
+	return ir.NewBlockStmt(pos, block)
+}
+
+// expandInline reads in an extra copy of IR to populate
+// fn.Inl.{Dcl,Body}.
+func expandInline(fn *ir.Func, pri pkgReaderIndex) {
+	// TODO(mdempsky): Remove this function. It's currently needed by
+	// dwarfgen/dwarf.go:preInliningDcls, which requires fn.Inl.Dcl to
+	// create abstract function DIEs. But we should be able to provide it
+	// with the same information some other way.
+
+	fndcls := len(fn.Dcl)
+	topdcls := len(typecheck.Target.Decls)
+
+	tmpfn := ir.NewFunc(fn.Pos())
+	tmpfn.Nname = ir.NewNameAt(fn.Nname.Pos(), fn.Sym())
+	tmpfn.ClosureVars = fn.ClosureVars
+
+	{
+		r := pri.asReader(relocBody, syncFuncBody)
+		r.setType(tmpfn.Nname, fn.Type())
+
+		// Don't change parameter's Sym/Nname fields.
+		r.funarghack = true
+
+		r.funcBody(tmpfn)
+
+		ir.WithFunc(tmpfn, func() {
+			deadcode.Func(tmpfn)
+		})
+	}
+
+	used := usedLocals(tmpfn.Body)
+
+	for _, name := range tmpfn.Dcl {
+		if name.Class != ir.PAUTO || used.Has(name) {
+			name.Curfn = fn
+			fn.Inl.Dcl = append(fn.Inl.Dcl, name)
+		}
+	}
+	fn.Inl.Body = tmpfn.Body
+
+	// Double check that we didn't change fn.Dcl by accident.
+	assert(fndcls == len(fn.Dcl))
+
+	// typecheck.Stmts may have added function literals to
+	// typecheck.Target.Decls. Remove them again so we don't risk trying
+	// to compile them multiple times.
+	typecheck.Target.Decls = typecheck.Target.Decls[:topdcls]
+}
+
+// usedLocals returns a set of local variables that are used within body.
+func usedLocals(body []ir.Node) ir.NameSet {
+	var used ir.NameSet
+	ir.VisitList(body, func(n ir.Node) {
+		if n, ok := n.(*ir.Name); ok && n.Op() == ir.ONAME && n.Class == ir.PAUTO {
+			used.Add(n)
+		}
+	})
+	return used
+}
+
+// @@@ Method wrappers
+
+// needWrapperTypes lists types for which we may need to generate
+// method wrappers.
+var needWrapperTypes []*types.Type
+
+// haveWrapperTypes lists types for which we know we already have
+// method wrappers, because we found the type in an imported package.
+var haveWrapperTypes []*types.Type
+
+func (r *reader) needWrapper(typ *types.Type) *types.Type {
+	if typ.IsPtr() {
+		base.Fatalf("bad pointer type: %v", typ)
+	}
+
+	// If a type was found in an imported package, then we can assume
+	// that package (or one of its transitive dependencies) already
+	// generated method wrappers for it.
+	//
+	// Exception: If we're instantiating an imported generic type or
+	// function, we might be instantiating it with type arguments not
+	// previously seen before.
+	//
+	// TODO(mdempsky): Distinguish when a generic function or type was
+	// instantiated in an imported package so that we can add types to
+	// haveWrapperTypes instead.
+	if r.p != localPkgReader && !r.hasTypeParams() {
+		haveWrapperTypes = append(haveWrapperTypes, typ)
+	} else {
+		needWrapperTypes = append(needWrapperTypes, typ)
+	}
+
+	return typ
+}
+
+func (r *reader) wrapTypes(target *ir.Package) {
+	// always generate a wrapper for error.Error (#29304)
+	r.needWrapper(types.ErrorType)
+
+	seen := make(map[string]*types.Type)
+	addType := func(typ *types.Type) bool {
+		if typ.Sym() != nil {
+			return true
+		}
+
+		key := typ.LinkString()
+		if prev := seen[key]; prev != nil {
+			if !types.Identical(typ, prev) {
+				base.Fatalf("collision: types %v and %v have short string %q", typ, prev, key)
+			}
+			return false
+		}
+
+		seen[key] = typ
+		return true
+	}
+
+	for _, typ := range haveWrapperTypes {
+		addType(typ)
+	}
+	haveWrapperTypes = nil
+
+	for _, typ := range needWrapperTypes {
+		if addType(typ) {
+			r.wrapType(typ, target)
+		}
+	}
+	needWrapperTypes = nil
+}
+
+func (r *reader) wrapType(typ *types.Type, target *ir.Package) {
+	if !typ.IsInterface() {
+		typecheck.CalcMethods(typ)
+	}
+	for _, meth := range typ.AllMethods().Slice() {
+		if meth.Sym.IsBlank() || !meth.IsMethod() {
+			base.FatalfAt(meth.Pos, "invalid method: %v", meth)
+		}
+
+		r.methodValueWrapper(typ, meth, target)
+
+		r.methodWrapper(0, typ, meth, target)
+
+		// For non-interface types, we also want *T wrappers.
+		if !typ.IsInterface() {
+			r.methodWrapper(1, typ, meth, target)
+
+			// For not-in-heap types, *T is a scalar, not pointer shaped,
+			// so the interface wrappers use **T.
+			if typ.NotInHeap() {
+				r.methodWrapper(2, typ, meth, target)
+			}
+		}
+	}
+}
+
+func (r *reader) methodWrapper(derefs int, tbase *types.Type, method *types.Field, target *ir.Package) {
+	wrapper := tbase
+	for i := 0; i < derefs; i++ {
+		wrapper = types.NewPtr(wrapper)
+	}
+
+	sym := ir.MethodSym(wrapper, method.Sym)
+	assert(!sym.Siggen())
+	sym.SetSiggen(true)
+
+	wrappee := method.Type.Recv().Type
+	if types.Identical(wrapper, wrappee) ||
+		!types.IsMethodApplicable(wrapper, method) ||
+		!reflectdata.NeedEmit(tbase) {
+		return
+	}
+
+	// TODO(mdempsky): Use method.Pos instead?
+	pos := base.AutogeneratedPos
+
+	fn := r.newWrapperFunc(pos, sym, wrapper, method)
+
+	var recv ir.Node = fn.Nname.Type().Recv().Nname.(*ir.Name)
+
+	// For simple *T wrappers around T methods, panicwrap produces a
+	// nicer panic message.
+	if wrapper.IsPtr() && types.Identical(wrapper.Elem(), wrappee) {
+		cond := ir.NewBinaryExpr(pos, ir.OEQ, recv, types.BuiltinPkg.Lookup("nil").Def.(ir.Node))
+		then := []ir.Node{ir.NewCallExpr(pos, ir.OCALL, typecheck.LookupRuntime("panicwrap"), nil)}
+		fn.Body.Append(ir.NewIfStmt(pos, cond, then, nil))
+	}
+
+	// typecheck will add one implicit deref, if necessary,
+	// but not-in-heap types require more for their **T wrappers.
+	for i := 1; i < derefs; i++ {
+		recv = Implicit(ir.NewStarExpr(pos, recv))
+	}
+
+	addTailCall(pos, fn, recv, method)
+
+	r.finishWrapperFunc(fn, target)
+}
+
+func (r *reader) methodValueWrapper(tbase *types.Type, method *types.Field, target *ir.Package) {
+	recvType := tbase
+	if !tbase.IsInterface() {
+		recvType = method.Type.Recv().Type
+		if !types.Identical(tbase, types.ReceiverBaseType(recvType)) {
+			return
+		}
+	}
+
+	sym := ir.MethodSymSuffix(recvType, method.Sym, "-fm")
+	assert(!sym.Uniq())
+	sym.SetUniq(true)
+
+	// TODO(mdempsky): Use method.Pos instead?
+	pos := base.AutogeneratedPos
+
+	fn := r.newWrapperFunc(pos, sym, nil, method)
+	sym.Def = fn.Nname
+
+	// Declare and initialize variable holding receiver.
+	recv := ir.NewHiddenParam(pos, fn, typecheck.Lookup(".this"), recvType)
+
+	if !reflectdata.NeedEmit(tbase) {
+		typecheck.Func(fn)
+		return
+	}
+
+	addTailCall(pos, fn, recv, method)
+
+	r.finishWrapperFunc(fn, target)
+}
+
+func (r *reader) newWrapperFunc(pos src.XPos, sym *types.Sym, wrapper *types.Type, method *types.Field) *ir.Func {
+	fn := ir.NewFunc(pos)
+	fn.SetDupok(true) // TODO(mdempsky): Leave unset for local, non-generic wrappers?
+
+	name := ir.NewNameAt(pos, sym)
+	ir.MarkFunc(name)
+	name.Func = fn
+	name.Defn = fn
+	fn.Nname = name
+
+	sig := newWrapperType(wrapper, method)
+	r.setType(name, sig)
+
+	// TODO(mdempsky): De-duplicate with similar logic in funcargs.
+	defParams := func(class ir.Class, params *types.Type) {
+		for _, param := range params.FieldSlice() {
+			name := ir.NewNameAt(param.Pos, param.Sym)
+			name.Class = class
+			r.setType(name, param.Type)
+
+			name.Curfn = fn
+			fn.Dcl = append(fn.Dcl, name)
+
+			param.Nname = name
+		}
+	}
+
+	defParams(ir.PPARAM, sig.Recvs())
+	defParams(ir.PPARAM, sig.Params())
+	defParams(ir.PPARAMOUT, sig.Results())
+
+	return fn
+}
+
+func (r *reader) finishWrapperFunc(fn *ir.Func, target *ir.Package) {
+	typecheck.Func(fn)
+
+	ir.WithFunc(fn, func() {
+		typecheck.Stmts(fn.Body)
+	})
+
+	target.Decls = append(target.Decls, fn)
+}
+
+// newWrapperType returns a copy of the given signature type, but with
+// the receiver parameter type substituted with recvType.
+// If recvType is nil, newWrapperType returns a signature
+// without a receiver parameter.
+func newWrapperType(recvType *types.Type, method *types.Field) *types.Type {
+	clone := func(params []*types.Field) []*types.Field {
+		res := make([]*types.Field, len(params))
+		for i, param := range params {
+			sym := param.Sym
+			if sym == nil || sym.Name == "_" {
+				sym = typecheck.LookupNum(".anon", i)
+			}
+			res[i] = types.NewField(param.Pos, sym, param.Type)
+			res[i].SetIsDDD(param.IsDDD())
+		}
+		return res
+	}
+
+	sig := method.Type
+
+	var recv *types.Field
+	if recvType != nil {
+		recv = types.NewField(sig.Recv().Pos, typecheck.Lookup(".this"), recvType)
+	}
+	params := clone(sig.Params().FieldSlice())
+	results := clone(sig.Results().FieldSlice())
+
+	return types.NewSignature(types.NoPkg, recv, nil, params, results)
+}
+
+func addTailCall(pos src.XPos, fn *ir.Func, recv ir.Node, method *types.Field) {
+	sig := fn.Nname.Type()
+	args := make([]ir.Node, sig.NumParams())
+	for i, param := range sig.Params().FieldSlice() {
+		args[i] = param.Nname.(*ir.Name)
+	}
+
+	// TODO(mdempsky): Support creating OTAILCALL, when possible. See reflectdata.methodWrapper.
+	// Not urgent though, because tail calls are currently incompatible with regabi anyway.
+
+	fn.SetWrapper(true) // TODO(mdempsky): Leave unset for tail calls?
+
+	dot := ir.NewSelectorExpr(pos, ir.OXDOT, recv, method.Sym)
+	call := typecheck.Call(pos, dot, args, method.Type.IsVariadic()).(*ir.CallExpr)
+
+	if method.Type.NumResults() == 0 {
+		fn.Body.Append(call)
+		return
+	}
+
+	ret := ir.NewReturnStmt(pos, nil)
+	ret.Results = []ir.Node{call}
+	fn.Body.Append(ret)
+}
diff --git a/src/cmd/compile/internal/noder/reader2.go b/src/cmd/compile/internal/noder/reader2.go
new file mode 100644
index 0000000..5637196
--- /dev/null
+++ b/src/cmd/compile/internal/noder/reader2.go
@@ -0,0 +1,510 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"go/constant"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/types2"
+	"cmd/internal/src"
+)
+
+type pkgReader2 struct {
+	pkgDecoder
+
+	check   *types2.Checker
+	imports map[string]*types2.Package
+
+	posBases []*syntax.PosBase
+	pkgs     []*types2.Package
+	typs     []types2.Type
+}
+
+func readPackage2(check *types2.Checker, imports map[string]*types2.Package, input pkgDecoder) *types2.Package {
+	pr := pkgReader2{
+		pkgDecoder: input,
+
+		check:   check,
+		imports: imports,
+
+		posBases: make([]*syntax.PosBase, input.numElems(relocPosBase)),
+		pkgs:     make([]*types2.Package, input.numElems(relocPkg)),
+		typs:     make([]types2.Type, input.numElems(relocType)),
+	}
+
+	r := pr.newReader(relocMeta, publicRootIdx, syncPublic)
+	pkg := r.pkg()
+	r.bool() // has init
+
+	for i, n := 0, r.len(); i < n; i++ {
+		r.obj()
+	}
+
+	r.sync(syncEOF)
+
+	pkg.MarkComplete()
+	return pkg
+}
+
+type reader2 struct {
+	decoder
+
+	p *pkgReader2
+
+	dict *reader2Dict
+}
+
+type reader2Dict struct {
+	bounds []typeInfo
+
+	tparams []*types2.TypeParam
+
+	derived      []derivedInfo
+	derivedTypes []types2.Type
+}
+
+type reader2TypeBound struct {
+	derived  bool
+	boundIdx int
+}
+
+func (pr *pkgReader2) newReader(k reloc, idx int, marker syncMarker) *reader2 {
+	return &reader2{
+		decoder: pr.newDecoder(k, idx, marker),
+		p:       pr,
+	}
+}
+
+// @@@ Positions
+
+func (r *reader2) pos() syntax.Pos {
+	r.sync(syncPos)
+	if !r.bool() {
+		return syntax.Pos{}
+	}
+
+	// TODO(mdempsky): Delta encoding.
+	posBase := r.posBase()
+	line := r.uint()
+	col := r.uint()
+	return syntax.MakePos(posBase, line, col)
+}
+
+func (r *reader2) posBase() *syntax.PosBase {
+	return r.p.posBaseIdx(r.reloc(relocPosBase))
+}
+
+func (pr *pkgReader2) posBaseIdx(idx int) *syntax.PosBase {
+	if b := pr.posBases[idx]; b != nil {
+		return b
+	}
+
+	r := pr.newReader(relocPosBase, idx, syncPosBase)
+	var b *syntax.PosBase
+
+	filename := r.string()
+	_ = r.string() // absolute file name
+
+	if r.bool() {
+		b = syntax.NewFileBase(filename)
+	} else {
+		pos := r.pos()
+		line := r.uint()
+		col := r.uint()
+		b = syntax.NewLineBase(pos, filename, line, col)
+	}
+
+	pr.posBases[idx] = b
+	return b
+}
+
+// @@@ Packages
+
+func (r *reader2) pkg() *types2.Package {
+	r.sync(syncPkg)
+	return r.p.pkgIdx(r.reloc(relocPkg))
+}
+
+func (pr *pkgReader2) pkgIdx(idx int) *types2.Package {
+	// TODO(mdempsky): Consider using some non-nil pointer to indicate
+	// the universe scope, so we don't need to keep re-reading it.
+	if pkg := pr.pkgs[idx]; pkg != nil {
+		return pkg
+	}
+
+	pkg := pr.newReader(relocPkg, idx, syncPkgDef).doPkg()
+	pr.pkgs[idx] = pkg
+	return pkg
+}
+
+func (r *reader2) doPkg() *types2.Package {
+	path := r.string()
+	if path == "builtin" {
+		return nil // universe
+	}
+	if path == "" {
+		path = r.p.pkgPath
+	}
+
+	if pkg := r.p.imports[path]; pkg != nil {
+		return pkg
+	}
+
+	name := r.string()
+	height := r.len()
+
+	pkg := types2.NewPackageHeight(path, name, height)
+	r.p.imports[path] = pkg
+
+	// TODO(mdempsky): The list of imported packages is important for
+	// go/types, but we could probably skip populating it for types2.
+	imports := make([]*types2.Package, r.len())
+	for i := range imports {
+		imports[i] = r.pkg()
+	}
+	pkg.SetImports(imports)
+
+	return pkg
+}
+
+// @@@ Types
+
+func (r *reader2) typ() types2.Type {
+	return r.p.typIdx(r.typInfo(), r.dict)
+}
+
+func (r *reader2) typInfo() typeInfo {
+	r.sync(syncType)
+	if r.bool() {
+		return typeInfo{idx: r.len(), derived: true}
+	}
+	return typeInfo{idx: r.reloc(relocType), derived: false}
+}
+
+func (pr *pkgReader2) typIdx(info typeInfo, dict *reader2Dict) types2.Type {
+	idx := info.idx
+	var where *types2.Type
+	if info.derived {
+		where = &dict.derivedTypes[idx]
+		idx = dict.derived[idx].idx
+	} else {
+		where = &pr.typs[idx]
+	}
+
+	if typ := *where; typ != nil {
+		return typ
+	}
+
+	r := pr.newReader(relocType, idx, syncTypeIdx)
+	r.dict = dict
+
+	typ := r.doTyp()
+	assert(typ != nil)
+
+	// See comment in pkgReader.typIdx explaining how this happens.
+	if prev := *where; prev != nil {
+		return prev
+	}
+
+	*where = typ
+	return typ
+}
+
+func (r *reader2) doTyp() (res types2.Type) {
+	switch tag := codeType(r.code(syncType)); tag {
+	default:
+		base.FatalfAt(src.NoXPos, "unhandled type tag: %v", tag)
+		panic("unreachable")
+
+	case typeBasic:
+		return types2.Typ[r.len()]
+
+	case typeNamed:
+		obj, targs := r.obj()
+		name := obj.(*types2.TypeName)
+		if len(targs) != 0 {
+			return r.p.check.InstantiateLazy(syntax.Pos{}, name.Type(), targs, nil, false)
+		}
+		return name.Type()
+
+	case typeTypeParam:
+		return r.dict.tparams[r.len()]
+
+	case typeArray:
+		len := int64(r.uint64())
+		return types2.NewArray(r.typ(), len)
+	case typeChan:
+		dir := types2.ChanDir(r.len())
+		return types2.NewChan(dir, r.typ())
+	case typeMap:
+		return types2.NewMap(r.typ(), r.typ())
+	case typePointer:
+		return types2.NewPointer(r.typ())
+	case typeSignature:
+		return r.signature(nil)
+	case typeSlice:
+		return types2.NewSlice(r.typ())
+	case typeStruct:
+		return r.structType()
+	case typeInterface:
+		return r.interfaceType()
+	case typeUnion:
+		return r.unionType()
+	}
+}
+
+func (r *reader2) structType() *types2.Struct {
+	fields := make([]*types2.Var, r.len())
+	var tags []string
+	for i := range fields {
+		pos := r.pos()
+		pkg, name := r.selector()
+		ftyp := r.typ()
+		tag := r.string()
+		embedded := r.bool()
+
+		fields[i] = types2.NewField(pos, pkg, name, ftyp, embedded)
+		if tag != "" {
+			for len(tags) < i {
+				tags = append(tags, "")
+			}
+			tags = append(tags, tag)
+		}
+	}
+	return types2.NewStruct(fields, tags)
+}
+
+func (r *reader2) unionType() *types2.Union {
+	terms := make([]*types2.Term, r.len())
+	for i := range terms {
+		terms[i] = types2.NewTerm(r.bool(), r.typ())
+	}
+	return types2.NewUnion(terms)
+}
+
+func (r *reader2) interfaceType() *types2.Interface {
+	methods := make([]*types2.Func, r.len())
+	embeddeds := make([]types2.Type, r.len())
+
+	for i := range methods {
+		pos := r.pos()
+		pkg, name := r.selector()
+		mtyp := r.signature(nil)
+		methods[i] = types2.NewFunc(pos, pkg, name, mtyp)
+	}
+
+	for i := range embeddeds {
+		embeddeds[i] = r.typ()
+	}
+
+	return types2.NewInterfaceType(methods, embeddeds)
+}
+
+func (r *reader2) signature(recv *types2.Var) *types2.Signature {
+	r.sync(syncSignature)
+
+	params := r.params()
+	results := r.params()
+	variadic := r.bool()
+
+	return types2.NewSignature(recv, params, results, variadic)
+}
+
+func (r *reader2) params() *types2.Tuple {
+	r.sync(syncParams)
+	params := make([]*types2.Var, r.len())
+	for i := range params {
+		params[i] = r.param()
+	}
+	return types2.NewTuple(params...)
+}
+
+func (r *reader2) param() *types2.Var {
+	r.sync(syncParam)
+
+	pos := r.pos()
+	pkg, name := r.localIdent()
+	typ := r.typ()
+
+	return types2.NewParam(pos, pkg, name, typ)
+}
+
+// @@@ Objects
+
+func (r *reader2) obj() (types2.Object, []types2.Type) {
+	r.sync(syncObject)
+
+	assert(!r.bool())
+
+	pkg, name := r.p.objIdx(r.reloc(relocObj))
+	obj := pkg.Scope().Lookup(name)
+
+	targs := make([]types2.Type, r.len())
+	for i := range targs {
+		targs[i] = r.typ()
+	}
+
+	return obj, targs
+}
+
+func (pr *pkgReader2) objIdx(idx int) (*types2.Package, string) {
+	rname := pr.newReader(relocName, idx, syncObject1)
+
+	objPkg, objName := rname.qualifiedIdent()
+	assert(objName != "")
+
+	tag := codeObj(rname.code(syncCodeObj))
+
+	if tag == objStub {
+		assert(objPkg == nil)
+		return objPkg, objName
+	}
+
+	dict := pr.objDictIdx(idx)
+
+	r := pr.newReader(relocObj, idx, syncObject1)
+	r.dict = dict
+
+	objPkg.Scope().InsertLazy(objName, func() types2.Object {
+		switch tag {
+		default:
+			panic("weird")
+
+		case objAlias:
+			pos := r.pos()
+			typ := r.typ()
+			return types2.NewTypeName(pos, objPkg, objName, typ)
+
+		case objConst:
+			pos := r.pos()
+			typ, val := r.value()
+			return types2.NewConst(pos, objPkg, objName, typ, val)
+
+		case objFunc:
+			pos := r.pos()
+			tparams := r.typeParamNames()
+			sig := r.signature(nil)
+			sig.SetTParams(tparams)
+			return types2.NewFunc(pos, objPkg, objName, sig)
+
+		case objType:
+			pos := r.pos()
+
+			return types2.NewTypeNameLazy(pos, objPkg, objName, func(named *types2.Named) (tparams []*types2.TypeName, underlying types2.Type, methods []*types2.Func) {
+				tparams = r.typeParamNames()
+
+				// TODO(mdempsky): Rewrite receiver types to underlying is an
+				// Interface? The go/types importer does this (I think because
+				// unit tests expected that), but cmd/compile doesn't care
+				// about it, so maybe we can avoid worrying about that here.
+				underlying = r.typ().Underlying()
+
+				methods = make([]*types2.Func, r.len())
+				for i := range methods {
+					methods[i] = r.method()
+				}
+
+				return
+			})
+
+		case objVar:
+			pos := r.pos()
+			typ := r.typ()
+			return types2.NewVar(pos, objPkg, objName, typ)
+		}
+	})
+
+	return objPkg, objName
+}
+
+func (r *reader2) value() (types2.Type, constant.Value) {
+	r.sync(syncValue)
+	return r.typ(), r.rawValue()
+}
+
+func (pr *pkgReader2) objDictIdx(idx int) *reader2Dict {
+	r := pr.newReader(relocObjDict, idx, syncObject1)
+
+	var dict reader2Dict
+
+	if implicits := r.len(); implicits != 0 {
+		base.Fatalf("unexpected object with %v implicit type parameter(s)", implicits)
+	}
+
+	dict.bounds = make([]typeInfo, r.len())
+	for i := range dict.bounds {
+		dict.bounds[i] = r.typInfo()
+	}
+
+	dict.derived = make([]derivedInfo, r.len())
+	dict.derivedTypes = make([]types2.Type, len(dict.derived))
+	for i := range dict.derived {
+		dict.derived[i] = derivedInfo{r.reloc(relocType), r.bool()}
+	}
+
+	// function references follow, but reader2 doesn't need those
+
+	return &dict
+}
+
+func (r *reader2) typeParamNames() []*types2.TypeName {
+	r.sync(syncTypeParamNames)
+
+	// Note: This code assumes it only processes objects without
+	// implement type parameters. This is currently fine, because
+	// reader2 is only used to read in exported declarations, which are
+	// always package scoped.
+
+	if len(r.dict.bounds) == 0 {
+		return nil
+	}
+
+	// Careful: Type parameter lists may have cycles. To allow for this,
+	// we construct the type parameter list in two passes: first we
+	// create all the TypeNames and TypeParams, then we construct and
+	// set the bound type.
+
+	names := make([]*types2.TypeName, len(r.dict.bounds))
+	r.dict.tparams = make([]*types2.TypeParam, len(r.dict.bounds))
+	for i := range r.dict.bounds {
+		pos := r.pos()
+		pkg, name := r.localIdent()
+
+		names[i] = types2.NewTypeName(pos, pkg, name, nil)
+		r.dict.tparams[i] = r.p.check.NewTypeParam(names[i], nil)
+	}
+
+	for i, bound := range r.dict.bounds {
+		r.dict.tparams[i].SetConstraint(r.p.typIdx(bound, r.dict))
+	}
+
+	return names
+}
+
+func (r *reader2) method() *types2.Func {
+	r.sync(syncMethod)
+	pos := r.pos()
+	pkg, name := r.selector()
+
+	rparams := r.typeParamNames()
+	sig := r.signature(r.param())
+	sig.SetRParams(rparams)
+
+	_ = r.pos() // TODO(mdempsky): Remove; this is a hacker for linker.go.
+	return types2.NewFunc(pos, pkg, name, sig)
+}
+
+func (r *reader2) qualifiedIdent() (*types2.Package, string) { return r.ident(syncSym) }
+func (r *reader2) localIdent() (*types2.Package, string)     { return r.ident(syncLocalIdent) }
+func (r *reader2) selector() (*types2.Package, string)       { return r.ident(syncSelector) }
+
+func (r *reader2) ident(marker syncMarker) (*types2.Package, string) {
+	r.sync(marker)
+	return r.pkg(), r.string()
+}
diff --git a/src/cmd/compile/internal/noder/reloc.go b/src/cmd/compile/internal/noder/reloc.go
new file mode 100644
index 0000000..669a618
--- /dev/null
+++ b/src/cmd/compile/internal/noder/reloc.go
@@ -0,0 +1,42 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+// A reloc indicates a particular section within a unified IR export.
+//
+// TODO(mdempsky): Rename to "section" or something similar?
+type reloc int
+
+// A relocEnt (relocation entry) is an entry in an atom's local
+// reference table.
+//
+// TODO(mdempsky): Rename this too.
+type relocEnt struct {
+	kind reloc
+	idx  int
+}
+
+// Reserved indices within the meta relocation section.
+const (
+	publicRootIdx  = 0
+	privateRootIdx = 1
+)
+
+const (
+	relocString reloc = iota
+	relocMeta
+	relocPosBase
+	relocPkg
+	relocName
+	relocType
+	relocObj
+	relocObjExt
+	relocObjDict
+	relocBody
+
+	numRelocs = iota
+)
diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
index 3ebc8df..6736f12 100644
--- a/src/cmd/compile/internal/noder/stencil.go
+++ b/src/cmd/compile/internal/noder/stencil.go
@@ -8,21 +8,32 @@
 package noder
 
 import (
-	"bytes"
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
+	"cmd/compile/internal/objw"
+	"cmd/compile/internal/reflectdata"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
+	"cmd/internal/obj"
 	"cmd/internal/src"
 	"fmt"
-	"strings"
+	"go/constant"
 )
 
-// For catching problems as we add more features
-// TODO(danscales): remove assertions or replace with base.FatalfAt()
+// Enable extra consistency checks.
+const doubleCheck = true
+
 func assert(p bool) {
-	if !p {
-		panic("assertion failed")
+	base.Assert(p)
+}
+
+// Temporary - for outputting information on derived types, dictionaries, sub-dictionaries.
+// Turn off when running tests.
+var infoPrintMode = false
+
+func infoPrint(format string, a ...interface{}) {
+	if infoPrintMode {
+		fmt.Printf(format, a...)
 	}
 }
 
@@ -32,7 +43,8 @@
 // encountered already or new ones that are encountered during the stenciling
 // process.
 func (g *irgen) stencil() {
-	g.target.Stencils = make(map[*types.Sym]*ir.Func)
+	g.instInfoMap = make(map[*types.Sym]*instInfo)
+	g.gfInfoMap = make(map[*types.Sym]*gfInfo)
 
 	// Instantiate the methods of instantiated generic types that we have seen so far.
 	g.instantiateMethods()
@@ -72,56 +84,138 @@
 		// instantiated function if it hasn't been created yet, and change
 		// to calling that function directly.
 		modified := false
-		foundFuncInst := false
+		closureRequired := false
+		// declInfo will be non-nil exactly if we are scanning an instantiated function
+		declInfo := g.instInfoMap[decl.Sym()]
+
 		ir.Visit(decl, func(n ir.Node) {
 			if n.Op() == ir.OFUNCINST {
-				// We found a function instantiation that is not
-				// immediately called.
-				foundFuncInst = true
+				// generic F, not immediately called
+				closureRequired = true
 			}
-			if n.Op() != ir.OCALL || n.(*ir.CallExpr).X.Op() != ir.OFUNCINST {
-				return
+			if (n.Op() == ir.OMETHEXPR || n.Op() == ir.OMETHVALUE) && len(deref(n.(*ir.SelectorExpr).X.Type()).RParams()) > 0 && !types.IsInterfaceMethod(n.(*ir.SelectorExpr).Selection.Type) {
+				// T.M or x.M, where T or x is generic, but not immediately
+				// called. Not necessary if the method selected is
+				// actually for an embedded interface field.
+				closureRequired = true
 			}
-			// We have found a function call using a generic function
-			// instantiation.
-			call := n.(*ir.CallExpr)
-			inst := call.X.(*ir.InstExpr)
-			st := g.getInstantiationForNode(inst)
-			// Replace the OFUNCINST with a direct reference to the
-			// new stenciled function
-			call.X = st.Nname
-			if inst.X.Op() == ir.OCALLPART {
-				// When we create an instantiation of a method
-				// call, we make it a function. So, move the
-				// receiver to be the first arg of the function
-				// call.
-				withRecv := make([]ir.Node, len(call.Args)+1)
-				dot := inst.X.(*ir.SelectorExpr)
-				withRecv[0] = dot.X
-				copy(withRecv[1:], call.Args)
-				call.Args = withRecv
+			if n.Op() == ir.OCALL && n.(*ir.CallExpr).X.Op() == ir.OFUNCINST {
+				// We have found a function call using a generic function
+				// instantiation.
+				call := n.(*ir.CallExpr)
+				inst := call.X.(*ir.InstExpr)
+				nameNode, isMeth := g.getInstNameNode(inst)
+				targs := typecheck.TypesOf(inst.Targs)
+				st := g.getInstantiation(nameNode, targs, isMeth)
+				dictValue, usingSubdict := g.getDictOrSubdict(declInfo, n, nameNode, targs, isMeth)
+				if infoPrintMode {
+					dictkind := "Main dictionary"
+					if usingSubdict {
+						dictkind = "Sub-dictionary"
+					}
+					if inst.X.Op() == ir.OMETHVALUE {
+						fmt.Printf("%s in %v at generic method call: %v - %v\n", dictkind, decl, inst.X, call)
+					} else {
+						fmt.Printf("%s in %v at generic function call: %v - %v\n", dictkind, decl, inst.X, call)
+					}
+				}
+
+				// Transform the Call now, which changes OCALL to
+				// OCALLFUNC and does typecheckaste/assignconvfn. Do
+				// it before installing the instantiation, so we are
+				// checking against non-shape param types in
+				// typecheckaste.
+				transformCall(call)
+
+				// Replace the OFUNCINST with a direct reference to the
+				// new stenciled function
+				call.X = st.Nname
+				if inst.X.Op() == ir.OMETHVALUE {
+					// When we create an instantiation of a method
+					// call, we make it a function. So, move the
+					// receiver to be the first arg of the function
+					// call.
+					call.Args.Prepend(inst.X.(*ir.SelectorExpr).X)
+				}
+
+				// Add dictionary to argument list.
+				call.Args.Prepend(dictValue)
+				modified = true
 			}
-			// Transform the Call now, which changes OCALL
-			// to OCALLFUNC and does typecheckaste/assignconvfn.
-			transformCall(call)
-			modified = true
+			if n.Op() == ir.OCALLMETH && n.(*ir.CallExpr).X.Op() == ir.ODOTMETH && len(deref(n.(*ir.CallExpr).X.Type().Recv().Type).RParams()) > 0 {
+				// Method call on a generic type, which was instantiated by stenciling.
+				// Method calls on explicitly instantiated types will have an OFUNCINST
+				// and are handled above.
+				call := n.(*ir.CallExpr)
+				meth := call.X.(*ir.SelectorExpr)
+				targs := deref(meth.Type().Recv().Type).RParams()
+
+				t := meth.X.Type()
+				baseSym := deref(t).OrigSym
+				baseType := baseSym.Def.(*ir.Name).Type()
+				var gf *ir.Name
+				for _, m := range baseType.Methods().Slice() {
+					if meth.Sel == m.Sym {
+						gf = m.Nname.(*ir.Name)
+						break
+					}
+				}
+
+				// Transform the Call now, which changes OCALL
+				// to OCALLFUNC and does typecheckaste/assignconvfn.
+				transformCall(call)
+
+				st := g.getInstantiation(gf, targs, true)
+				dictValue, usingSubdict := g.getDictOrSubdict(declInfo, n, gf, targs, true)
+				// We have to be using a subdictionary, since this is
+				// a generic method call.
+				assert(usingSubdict)
+
+				// Transform to a function call, by appending the
+				// dictionary and the receiver to the args.
+				call.SetOp(ir.OCALLFUNC)
+				call.X = st.Nname
+				call.Args.Prepend(dictValue, meth.X)
+				modified = true
+			}
 		})
 
-		// If we found an OFUNCINST without a corresponding call in the
-		// above decl, then traverse the nodes of decl again (with
+		// If we found a reference to a generic instantiation that wasn't an
+		// immediate call, then traverse the nodes of decl again (with
 		// EditChildren rather than Visit), where we actually change the
-		// OFUNCINST node to an ONAME for the instantiated function.
+		// reference to the instantiation to a closure that captures the
+		// dictionary, then does a direct call.
 		// EditChildren is more expensive than Visit, so we only do this
-		// in the infrequent case of an OFUNCINSt without a corresponding
+		// in the infrequent case of an OFUNCINST without a corresponding
 		// call.
-		if foundFuncInst {
+		if closureRequired {
+			modified = true
 			var edit func(ir.Node) ir.Node
+			var outer *ir.Func
+			if f, ok := decl.(*ir.Func); ok {
+				outer = f
+			}
 			edit = func(x ir.Node) ir.Node {
 				if x.Op() == ir.OFUNCINST {
-					st := g.getInstantiationForNode(x.(*ir.InstExpr))
-					return st.Nname
+					child := x.(*ir.InstExpr).X
+					if child.Op() == ir.OMETHEXPR || child.Op() == ir.OMETHVALUE {
+						// Call EditChildren on child (x.X),
+						// not x, so that we don't do
+						// buildClosure() on the
+						// METHEXPR/METHVALUE nodes as well.
+						ir.EditChildren(child, edit)
+						return g.buildClosure(outer, x)
+					}
 				}
 				ir.EditChildren(x, edit)
+				switch {
+				case x.Op() == ir.OFUNCINST:
+					return g.buildClosure(outer, x)
+				case (x.Op() == ir.OMETHEXPR || x.Op() == ir.OMETHVALUE) &&
+					len(deref(x.(*ir.SelectorExpr).X.Type()).RParams()) > 0 &&
+					!types.IsInterfaceMethod(x.(*ir.SelectorExpr).Selection.Type):
+					return g.buildClosure(outer, x)
+				}
 				return x
 			}
 			edit(decl)
@@ -137,104 +231,384 @@
 		g.instantiateMethods()
 	}
 
+	g.finalizeSyms()
 }
 
-// instantiateMethods instantiates all the methods of all fully-instantiated
-// generic types that have been added to g.instTypeList.
+// buildClosure makes a closure to implement x, a OFUNCINST or OMETHEXPR
+// of generic type. outer is the containing function (or nil if closure is
+// in a global assignment instead of a function).
+func (g *irgen) buildClosure(outer *ir.Func, x ir.Node) ir.Node {
+	pos := x.Pos()
+	var target *ir.Func   // target instantiated function/method
+	var dictValue ir.Node // dictionary to use
+	var rcvrValue ir.Node // receiver, if a method value
+	typ := x.Type()       // type of the closure
+	var outerInfo *instInfo
+	if outer != nil {
+		outerInfo = g.instInfoMap[outer.Sym()]
+	}
+	usingSubdict := false
+	valueMethod := false
+	if x.Op() == ir.OFUNCINST {
+		inst := x.(*ir.InstExpr)
+
+		// Type arguments we're instantiating with.
+		targs := typecheck.TypesOf(inst.Targs)
+
+		// Find the generic function/method.
+		var gf *ir.Name
+		if inst.X.Op() == ir.ONAME {
+			// Instantiating a generic function call.
+			gf = inst.X.(*ir.Name)
+		} else if inst.X.Op() == ir.OMETHVALUE {
+			// Instantiating a method value x.M.
+			se := inst.X.(*ir.SelectorExpr)
+			rcvrValue = se.X
+			gf = se.Selection.Nname.(*ir.Name)
+		} else {
+			panic("unhandled")
+		}
+
+		// target is the instantiated function we're trying to call.
+		// For functions, the target expects a dictionary as its first argument.
+		// For method values, the target expects a dictionary and the receiver
+		// as its first two arguments.
+		// dictValue is the value to use for the dictionary argument.
+		target = g.getInstantiation(gf, targs, rcvrValue != nil)
+		dictValue, usingSubdict = g.getDictOrSubdict(outerInfo, x, gf, targs, rcvrValue != nil)
+		if infoPrintMode {
+			dictkind := "Main dictionary"
+			if usingSubdict {
+				dictkind = "Sub-dictionary"
+			}
+			if rcvrValue == nil {
+				fmt.Printf("%s in %v for generic function value %v\n", dictkind, outer, inst.X)
+			} else {
+				fmt.Printf("%s in %v for generic method value %v\n", dictkind, outer, inst.X)
+			}
+		}
+	} else { // ir.OMETHEXPR or ir.METHVALUE
+		// Method expression T.M where T is a generic type.
+		se := x.(*ir.SelectorExpr)
+		targs := deref(se.X.Type()).RParams()
+		if len(targs) == 0 {
+			panic("bad")
+		}
+		if x.Op() == ir.OMETHVALUE {
+			rcvrValue = se.X
+		}
+
+		// se.X.Type() is the top-level type of the method expression. To
+		// correctly handle method expressions involving embedded fields,
+		// look up the generic method below using the type of the receiver
+		// of se.Selection, since that will be the type that actually has
+		// the method.
+		recv := deref(se.Selection.Type.Recv().Type)
+		baseType := recv.OrigSym.Def.Type()
+		var gf *ir.Name
+		for _, m := range baseType.Methods().Slice() {
+			if se.Sel == m.Sym {
+				gf = m.Nname.(*ir.Name)
+				break
+			}
+		}
+		if !gf.Type().Recv().Type.IsPtr() {
+			// Remember if value method, so we can detect (*T).M case.
+			valueMethod = true
+		}
+		target = g.getInstantiation(gf, targs, true)
+		dictValue, usingSubdict = g.getDictOrSubdict(outerInfo, x, gf, targs, true)
+		if infoPrintMode {
+			dictkind := "Main dictionary"
+			if usingSubdict {
+				dictkind = "Sub-dictionary"
+			}
+			fmt.Printf("%s in %v for method expression %v\n", dictkind, outer, x)
+		}
+	}
+
+	// Build a closure to implement a function instantiation.
+	//
+	//   func f[T any] (int, int) (int, int) { ...whatever... }
+	//
+	// Then any reference to f[int] not directly called gets rewritten to
+	//
+	//   .dictN := ... dictionary to use ...
+	//   func(a0, a1 int) (r0, r1 int) {
+	//     return .inst.f[int](.dictN, a0, a1)
+	//   }
+	//
+	// Similarly for method expressions,
+	//
+	//   type g[T any] ....
+	//   func (rcvr g[T]) f(a0, a1 int) (r0, r1 int) { ... }
+	//
+	// Any reference to g[int].f not directly called gets rewritten to
+	//
+	//   .dictN := ... dictionary to use ...
+	//   func(rcvr g[int], a0, a1 int) (r0, r1 int) {
+	//     return .inst.g[int].f(.dictN, rcvr, a0, a1)
+	//   }
+	//
+	// Also method values
+	//
+	//   var x g[int]
+	//
+	// Any reference to x.f not directly called gets rewritten to
+	//
+	//   .dictN := ... dictionary to use ...
+	//   x2 := x
+	//   func(a0, a1 int) (r0, r1 int) {
+	//     return .inst.g[int].f(.dictN, x2, a0, a1)
+	//   }
+
+	// Make a new internal function.
+	fn, formalParams, formalResults := startClosure(pos, outer, typ)
+
+	// This is the dictionary we want to use.
+	// It may be a constant, or it may be a dictionary acquired from the outer function's dictionary.
+	// For the latter, dictVar is a variable in the outer function's scope, set to the subdictionary
+	// read from the outer function's dictionary.
+	var dictVar *ir.Name
+	var dictAssign *ir.AssignStmt
+	if outer != nil {
+		// Note: for now this is a compile-time constant, so we don't really need a closure
+		// to capture it (a wrapper function would work just as well). But eventually it
+		// will be a read of a subdictionary from the parent dictionary.
+		dictVar = ir.NewNameAt(pos, typecheck.LookupNum(".dict", g.dnum))
+		g.dnum++
+		dictVar.Class = ir.PAUTO
+		typed(types.Types[types.TUINTPTR], dictVar)
+		dictVar.Curfn = outer
+		dictAssign = ir.NewAssignStmt(pos, dictVar, dictValue)
+		dictAssign.SetTypecheck(1)
+		dictVar.Defn = dictAssign
+		outer.Dcl = append(outer.Dcl, dictVar)
+	}
+	// assign the receiver to a temporary.
+	var rcvrVar *ir.Name
+	var rcvrAssign ir.Node
+	if rcvrValue != nil {
+		rcvrVar = ir.NewNameAt(pos, typecheck.LookupNum(".rcvr", g.dnum))
+		g.dnum++
+		rcvrVar.Class = ir.PAUTO
+		typed(rcvrValue.Type(), rcvrVar)
+		rcvrVar.Curfn = outer
+		rcvrAssign = ir.NewAssignStmt(pos, rcvrVar, rcvrValue)
+		rcvrAssign.SetTypecheck(1)
+		rcvrVar.Defn = rcvrAssign
+		outer.Dcl = append(outer.Dcl, rcvrVar)
+	}
+
+	// Build body of closure. This involves just calling the wrapped function directly
+	// with the additional dictionary argument.
+
+	// First, figure out the dictionary argument.
+	var dict2Var ir.Node
+	if usingSubdict {
+		// Capture sub-dictionary calculated in the outer function
+		dict2Var = ir.CaptureName(pos, fn, dictVar)
+		typed(types.Types[types.TUINTPTR], dict2Var)
+	} else {
+		// Static dictionary, so can be used directly in the closure
+		dict2Var = dictValue
+	}
+	// Also capture the receiver variable.
+	var rcvr2Var *ir.Name
+	if rcvrValue != nil {
+		rcvr2Var = ir.CaptureName(pos, fn, rcvrVar)
+	}
+
+	// Build arguments to call inside the closure.
+	var args []ir.Node
+
+	// First the dictionary argument.
+	args = append(args, dict2Var)
+	// Then the receiver.
+	if rcvrValue != nil {
+		args = append(args, rcvr2Var)
+	}
+	// Then all the other arguments (including receiver for method expressions).
+	for i := 0; i < typ.NumParams(); i++ {
+		if x.Op() == ir.OMETHEXPR && i == 0 {
+			// If we are doing a method expression, we need to
+			// explicitly traverse any embedded fields in the receiver
+			// argument in order to call the method instantiation.
+			arg0 := formalParams[0].Nname.(ir.Node)
+			arg0 = typecheck.AddImplicitDots(ir.NewSelectorExpr(base.Pos, ir.OXDOT, arg0, x.(*ir.SelectorExpr).Sel)).X
+			if valueMethod && arg0.Type().IsPtr() {
+				// For handling the (*T).M case: if we have a pointer
+				// receiver after following all the embedded fields,
+				// but it's a value method, add a star operator.
+				arg0 = ir.NewStarExpr(arg0.Pos(), arg0)
+			}
+			args = append(args, arg0)
+		} else {
+			args = append(args, formalParams[i].Nname.(*ir.Name))
+		}
+	}
+
+	// Build call itself.
+	var innerCall ir.Node = ir.NewCallExpr(pos, ir.OCALL, target.Nname, args)
+	if len(formalResults) > 0 {
+		innerCall = ir.NewReturnStmt(pos, []ir.Node{innerCall})
+	}
+	// Finish building body of closure.
+	ir.CurFunc = fn
+	// TODO: set types directly here instead of using typecheck.Stmt
+	typecheck.Stmt(innerCall)
+	ir.CurFunc = nil
+	fn.Body = []ir.Node{innerCall}
+
+	// We're all done with the captured dictionary (and receiver, for method values).
+	ir.FinishCaptureNames(pos, outer, fn)
+
+	// Make a closure referencing our new internal function.
+	c := ir.UseClosure(fn.OClosure, g.target)
+	var init []ir.Node
+	if outer != nil {
+		init = append(init, dictAssign)
+	}
+	if rcvrValue != nil {
+		init = append(init, rcvrAssign)
+	}
+	return ir.InitExpr(init, c)
+}
+
+// instantiateMethods instantiates all the methods (and associated dictionaries) of
+// all fully-instantiated generic types that have been added to g.instTypeList.
 func (g *irgen) instantiateMethods() {
 	for i := 0; i < len(g.instTypeList); i++ {
 		typ := g.instTypeList[i]
-		// Get the base generic type by looking up the symbol of the
-		// generic (uninstantiated) name.
-		baseSym := typ.Sym().Pkg.Lookup(genericTypeName(typ.Sym()))
+		assert(!typ.HasShape())
+		// Mark runtime type as needed, since this ensures that the
+		// compiler puts out the needed DWARF symbols, when this
+		// instantiated type has a different package from the local
+		// package.
+		typecheck.NeedRuntimeType(typ)
+		// Lookup the method on the base generic type, since methods may
+		// not be set on imported instantiated types.
+		baseSym := typ.OrigSym
 		baseType := baseSym.Def.(*ir.Name).Type()
-		for j, m := range typ.Methods().Slice() {
-			name := m.Nname.(*ir.Name)
-			targs := make([]ir.Node, len(typ.RParams()))
-			for k, targ := range typ.RParams() {
-				targs[k] = ir.TypeNode(targ)
-			}
+		for j, _ := range typ.Methods().Slice() {
 			baseNname := baseType.Methods().Slice()[j].Nname.(*ir.Name)
-			name.Func = g.getInstantiation(baseNname, targs, true)
+			// Eagerly generate the instantiations and dictionaries that implement these methods.
+			// We don't use the instantiations here, just generate them (and any
+			// further instantiations those generate, etc.).
+			// Note that we don't set the Func for any methods on instantiated
+			// types. Their signatures don't match so that would be confusing.
+			// Direct method calls go directly to the instantiations, implemented above.
+			// Indirect method calls use wrappers generated in reflectcall. Those wrappers
+			// will use these instantiations if they are needed (for interface tables or reflection).
+			_ = g.getInstantiation(baseNname, typ.RParams(), true)
+			_ = g.getDictionarySym(baseNname, typ.RParams(), true)
 		}
 	}
 	g.instTypeList = nil
 
 }
 
-// genericSym returns the name of the base generic type for the type named by
-// sym. It simply returns the name obtained by removing everything after the
-// first bracket ("[").
-func genericTypeName(sym *types.Sym) string {
-	return sym.Name[0:strings.Index(sym.Name, "[")]
-}
-
-// getInstantiationForNode returns the function/method instantiation for a
-// InstExpr node inst.
-func (g *irgen) getInstantiationForNode(inst *ir.InstExpr) *ir.Func {
+// getInstNameNode returns the name node for the method or function being instantiated, and a bool which is true if a method is being instantiated.
+func (g *irgen) getInstNameNode(inst *ir.InstExpr) (*ir.Name, bool) {
 	if meth, ok := inst.X.(*ir.SelectorExpr); ok {
-		return g.getInstantiation(meth.Selection.Nname.(*ir.Name), inst.Targs, true)
+		return meth.Selection.Nname.(*ir.Name), true
 	} else {
-		return g.getInstantiation(inst.X.(*ir.Name), inst.Targs, false)
+		return inst.X.(*ir.Name), false
 	}
 }
 
-// getInstantiation gets the instantiantion of the function or method nameNode
-// with the type arguments targs. If the instantiated function is not already
+// getDictOrSubdict returns, for a method/function call or reference (node n) in an
+// instantiation (described by instInfo), a node which is accessing a sub-dictionary
+// or main/static dictionary, as needed, and also returns a boolean indicating if a
+// sub-dictionary was accessed. nameNode is the particular function or method being
+// called/referenced, and targs are the type arguments.
+func (g *irgen) getDictOrSubdict(declInfo *instInfo, n ir.Node, nameNode *ir.Name, targs []*types.Type, isMeth bool) (ir.Node, bool) {
+	var dict ir.Node
+	usingSubdict := false
+	if declInfo != nil {
+		// Get the dictionary arg via sub-dictionary reference
+		entry, ok := declInfo.dictEntryMap[n]
+		// If the entry is not found, it may be that this node did not have
+		// any type args that depend on type params, so we need a main
+		// dictionary, not a sub-dictionary.
+		if ok {
+			dict = getDictionaryEntry(n.Pos(), declInfo.dictParam, entry, declInfo.dictLen)
+			usingSubdict = true
+		}
+	}
+	if !usingSubdict {
+		dict = g.getDictionaryValue(nameNode, targs, isMeth)
+	}
+	return dict, usingSubdict
+}
+
+// checkFetchBody checks if a generic body can be fetched, but hasn't been loaded
+// yet. If so, it imports the body.
+func checkFetchBody(nameNode *ir.Name) {
+	if nameNode.Func.Body == nil && nameNode.Func.Inl != nil {
+		// If there is no body yet but Func.Inl exists, then we can can
+		// import the whole generic body.
+		assert(nameNode.Func.Inl.Cost == 1 && nameNode.Sym().Pkg != types.LocalPkg)
+		typecheck.ImportBody(nameNode.Func)
+		assert(nameNode.Func.Inl.Body != nil)
+		nameNode.Func.Body = nameNode.Func.Inl.Body
+		nameNode.Func.Dcl = nameNode.Func.Inl.Dcl
+	}
+}
+
+// getInstantiation gets the instantiantion and dictionary of the function or method nameNode
+// with the type arguments shapes. If the instantiated function is not already
 // cached, then it calls genericSubst to create the new instantiation.
-func (g *irgen) getInstantiation(nameNode *ir.Name, targs []ir.Node, isMeth bool) *ir.Func {
-	sym := makeInstName(nameNode.Sym(), targs, isMeth)
-	st := g.target.Stencils[sym]
-	if st == nil {
+func (g *irgen) getInstantiation(nameNode *ir.Name, shapes []*types.Type, isMeth bool) *ir.Func {
+	checkFetchBody(nameNode)
+
+	// Convert any non-shape type arguments to their shape, so we can reduce the
+	// number of instantiations we have to generate. You can actually have a mix
+	// of shape and non-shape arguments, because of inferred or explicitly
+	// specified concrete type args.
+	var s1 []*types.Type
+	for i, t := range shapes {
+		if !t.HasShape() {
+			if s1 == nil {
+				s1 = make([]*types.Type, len(shapes))
+				copy(s1[0:i], shapes[0:i])
+			}
+			s1[i] = typecheck.Shapify(t)
+		} else if s1 != nil {
+			s1[i] = shapes[i]
+		}
+	}
+	if s1 != nil {
+		shapes = s1
+	}
+
+	sym := typecheck.MakeInstName(nameNode.Sym(), shapes, isMeth)
+	info := g.instInfoMap[sym]
+	if info == nil {
 		// If instantiation doesn't exist yet, create it and add
 		// to the list of decls.
-		st = g.genericSubst(sym, nameNode, targs, isMeth)
-		g.target.Stencils[sym] = st
+		gfInfo := g.getGfInfo(nameNode)
+		info = &instInfo{
+			gf:            nameNode,
+			gfInfo:        gfInfo,
+			startSubDict:  len(shapes) + len(gfInfo.derivedTypes),
+			startItabConv: len(shapes) + len(gfInfo.derivedTypes) + len(gfInfo.subDictCalls),
+			dictLen:       len(shapes) + len(gfInfo.derivedTypes) + len(gfInfo.subDictCalls) + len(gfInfo.itabConvs),
+			dictEntryMap:  make(map[ir.Node]int),
+		}
+		// genericSubst fills in info.dictParam and info.dictEntryMap.
+		st := g.genericSubst(sym, nameNode, shapes, isMeth, info)
+		info.fun = st
+		g.instInfoMap[sym] = info
+		// This ensures that the linker drops duplicates of this instantiation.
+		// All just works!
+		st.SetDupok(true)
 		g.target.Decls = append(g.target.Decls, st)
 		if base.Flag.W > 1 {
 			ir.Dump(fmt.Sprintf("\nstenciled %v", st), st)
 		}
 	}
-	return st
-}
-
-// makeInstName makes the unique name for a stenciled generic function or method,
-// based on the name of the function fy=nsym and the targs. It replaces any
-// existing bracket type list in the name. makeInstName asserts that fnsym has
-// brackets in its name if and only if hasBrackets is true.
-// TODO(danscales): remove the assertions and the hasBrackets argument later.
-//
-// Names of declared generic functions have no brackets originally, so hasBrackets
-// should be false. Names of generic methods already have brackets, since the new
-// type parameter is specified in the generic type of the receiver (e.g. func
-// (func (v *value[T]).set(...) { ... } has the original name (*value[T]).set.
-//
-// The standard naming is something like: 'genFn[int,bool]' for functions and
-// '(*genType[int,bool]).methodName' for methods
-func makeInstName(fnsym *types.Sym, targs []ir.Node, hasBrackets bool) *types.Sym {
-	b := bytes.NewBufferString("")
-	name := fnsym.Name
-	i := strings.Index(name, "[")
-	assert(hasBrackets == (i >= 0))
-	if i >= 0 {
-		b.WriteString(name[0:i])
-	} else {
-		b.WriteString(name)
-	}
-	b.WriteString("[")
-	for i, targ := range targs {
-		if i > 0 {
-			b.WriteString(",")
-		}
-		b.WriteString(targ.Type().String())
-	}
-	b.WriteString("]")
-	if i >= 0 {
-		i2 := strings.Index(name[i:], "]")
-		assert(i2 >= 0)
-		b.WriteString(name[i+i2+1:])
-	}
-	return typecheck.Lookup(b.String())
+	return info.fun
 }
 
 // Struct containing info needed for doing the substitution as we create the
@@ -243,32 +617,30 @@
 	g        *irgen
 	isMethod bool     // If a method is being instantiated
 	newf     *ir.Func // Func node for the new stenciled function
-	tparams  []*types.Field
-	targs    []ir.Node
-	// The substitution map from name nodes in the generic function to the
-	// name nodes in the new stenciled function.
-	vars map[*ir.Name]*ir.Name
+	ts       typecheck.Tsubster
+	info     *instInfo // Place to put extra info in the instantiation
 }
 
 // genericSubst returns a new function with name newsym. The function is an
 // instantiation of a generic function or method specified by namedNode with type
-// args targs. For a method with a generic receiver, it returns an instantiated
-// function type where the receiver becomes the first parameter. Otherwise the
-// instantiated method would still need to be transformed by later compiler
-// phases.
-func (g *irgen) genericSubst(newsym *types.Sym, nameNode *ir.Name, targs []ir.Node, isMethod bool) *ir.Func {
-	var tparams []*types.Field
+// args shapes. For a method with a generic receiver, it returns an instantiated
+// function type where the receiver becomes the first parameter. For either a generic
+// method or function, a dictionary parameter is the added as the very first
+// parameter. genericSubst fills in info.dictParam and info.dictEntryMap.
+func (g *irgen) genericSubst(newsym *types.Sym, nameNode *ir.Name, shapes []*types.Type, isMethod bool, info *instInfo) *ir.Func {
+	var tparams []*types.Type
 	if isMethod {
 		// Get the type params from the method receiver (after skipping
 		// over any pointer)
 		recvType := nameNode.Type().Recv().Type
 		recvType = deref(recvType)
-		tparams = make([]*types.Field, len(recvType.RParams()))
-		for i, rparam := range recvType.RParams() {
-			tparams[i] = types.NewField(src.NoXPos, nil, rparam)
-		}
+		tparams = recvType.RParams()
 	} else {
-		tparams = nameNode.Type().TParams().Fields().Slice()
+		fields := nameNode.Type().TParams().Fields().Slice()
+		tparams = make([]*types.Type, len(fields))
+		for i, f := range fields {
+			tparams[i] = f.Type
+		}
 	}
 	gf := nameNode.Func
 	// Pos of the instantiated function is same as the generic function
@@ -283,78 +655,214 @@
 	// depend on ir.CurFunc being set.
 	ir.CurFunc = newf
 
-	assert(len(tparams) == len(targs))
+	assert(len(tparams) == len(shapes))
 
 	subst := &subster{
 		g:        g,
 		isMethod: isMethod,
 		newf:     newf,
-		tparams:  tparams,
-		targs:    targs,
-		vars:     make(map[*ir.Name]*ir.Name),
+		info:     info,
+		ts: typecheck.Tsubster{
+			Tparams: tparams,
+			Targs:   shapes,
+			Vars:    make(map[*ir.Name]*ir.Name),
+		},
 	}
 
-	newf.Dcl = make([]*ir.Name, len(gf.Dcl))
-	for i, n := range gf.Dcl {
-		newf.Dcl[i] = subst.node(n).(*ir.Name)
-	}
+	newf.Dcl = make([]*ir.Name, 0, len(gf.Dcl)+1)
 
-	// Ugly: we have to insert the Name nodes of the parameters/results into
+	// Create the needed dictionary param
+	dictionarySym := newsym.Pkg.Lookup(".dict")
+	dictionaryType := types.Types[types.TUINTPTR]
+	dictionaryName := ir.NewNameAt(gf.Pos(), dictionarySym)
+	typed(dictionaryType, dictionaryName)
+	dictionaryName.Class = ir.PPARAM
+	dictionaryName.Curfn = newf
+	newf.Dcl = append(newf.Dcl, dictionaryName)
+	for _, n := range gf.Dcl {
+		if n.Sym().Name == ".dict" {
+			panic("already has dictionary")
+		}
+		newf.Dcl = append(newf.Dcl, subst.localvar(n))
+	}
+	dictionaryArg := types.NewField(gf.Pos(), dictionarySym, dictionaryType)
+	dictionaryArg.Nname = dictionaryName
+	info.dictParam = dictionaryName
+
+	// We add the dictionary as the first parameter in the function signature.
+	// We also transform a method type to the corresponding function type
+	// (make the receiver be the next parameter after the dictionary).
+	oldt := nameNode.Type()
+	var args []*types.Field
+	args = append(args, dictionaryArg)
+	args = append(args, oldt.Recvs().FieldSlice()...)
+	args = append(args, oldt.Params().FieldSlice()...)
+
+	// Replace the types in the function signature via subst.fields.
+	// Ugly: also, we have to insert the Name nodes of the parameters/results into
 	// the function type. The current function type has no Nname fields set,
 	// because it came via conversion from the types2 type.
-	oldt := nameNode.Type()
-	// We also transform a generic method type to the corresponding
-	// instantiated function type where the receiver is the first parameter.
 	newt := types.NewSignature(oldt.Pkg(), nil, nil,
-		subst.fields(ir.PPARAM, append(oldt.Recvs().FieldSlice(), oldt.Params().FieldSlice()...), newf.Dcl),
+		subst.fields(ir.PPARAM, args, newf.Dcl),
 		subst.fields(ir.PPARAMOUT, oldt.Results().FieldSlice(), newf.Dcl))
 
-	newf.Nname.SetType(newt)
+	typed(newt, newf.Nname)
 	ir.MarkFunc(newf.Nname)
 	newf.SetTypecheck(1)
-	newf.Nname.SetTypecheck(1)
 
 	// Make sure name/type of newf is set before substituting the body.
 	newf.Body = subst.list(gf.Body)
+
+	// Add code to check that the dictionary is correct.
+	// TODO: must be adjusted to deal with shapes, but will go away soon when we move
+	// to many->1 shape to concrete mapping.
+	// newf.Body.Prepend(subst.checkDictionary(dictionaryName, shapes)...)
+
 	ir.CurFunc = savef
+	// Add any new, fully instantiated types seen during the substitution to
+	// g.instTypeList.
+	g.instTypeList = append(g.instTypeList, subst.ts.InstTypeList...)
+
+	if doubleCheck {
+		okConvs := map[ir.Node]bool{}
+		ir.Visit(newf, func(n ir.Node) {
+			if n.Op() == ir.OIDATA {
+				// IDATA(OCONVIFACE(x)) is ok, as we don't use the type of x.
+				// TODO: use some other op besides OCONVIFACE. ONEW might work
+				// (with appropriate direct vs. indirect interface cases).
+				okConvs[n.(*ir.UnaryExpr).X] = true
+			}
+			if n.Op() == ir.OCONVIFACE && !okConvs[n] {
+				c := n.(*ir.ConvExpr)
+				if c.X.Type().HasShape() {
+					ir.Dump("BAD FUNCTION", newf)
+					ir.Dump("BAD CONVERSION", c)
+					base.Fatalf("converting shape type to interface")
+				}
+			}
+		})
+	}
 
 	return newf
 }
 
-// node is like DeepCopy(), but creates distinct ONAME nodes, and also descends
-// into closures. It substitutes type arguments for type parameters in all the new
-// nodes.
+// localvar creates a new name node for the specified local variable and enters it
+// in subst.vars. It substitutes type arguments for type parameters in the type of
+// name as needed.
+func (subst *subster) localvar(name *ir.Name) *ir.Name {
+	m := ir.NewNameAt(name.Pos(), name.Sym())
+	if name.IsClosureVar() {
+		m.SetIsClosureVar(true)
+	}
+	m.SetType(subst.ts.Typ(name.Type()))
+	m.BuiltinOp = name.BuiltinOp
+	m.Curfn = subst.newf
+	m.Class = name.Class
+	assert(name.Class != ir.PEXTERN && name.Class != ir.PFUNC)
+	m.Func = name.Func
+	subst.ts.Vars[name] = m
+	m.SetTypecheck(1)
+	return m
+}
+
+// checkDictionary returns code that does runtime consistency checks
+// between the dictionary and the types it should contain.
+func (subst *subster) checkDictionary(name *ir.Name, targs []*types.Type) (code []ir.Node) {
+	if false {
+		return // checking turned off
+	}
+	// TODO: when moving to GCshape, this test will become harder. Call into
+	// runtime to check the expected shape is correct?
+	pos := name.Pos()
+	// Convert dictionary to *[N]uintptr
+	d := ir.NewConvExpr(pos, ir.OCONVNOP, types.Types[types.TUNSAFEPTR], name)
+	d.SetTypecheck(1)
+	d = ir.NewConvExpr(pos, ir.OCONVNOP, types.NewArray(types.Types[types.TUINTPTR], int64(len(targs))).PtrTo(), d)
+	d.SetTypecheck(1)
+	types.CheckSize(d.Type().Elem())
+
+	// Check that each type entry in the dictionary is correct.
+	for i, t := range targs {
+		if t.HasShape() {
+			// Check the concrete type, not the shape type.
+			base.Fatalf("shape type in dictionary %s %+v\n", name.Sym().Name, t)
+		}
+		want := reflectdata.TypePtr(t)
+		typed(types.Types[types.TUINTPTR], want)
+		deref := ir.NewStarExpr(pos, d)
+		typed(d.Type().Elem(), deref)
+		idx := ir.NewConstExpr(constant.MakeUint64(uint64(i)), name) // TODO: what to set orig to?
+		typed(types.Types[types.TUINTPTR], idx)
+		got := ir.NewIndexExpr(pos, deref, idx)
+		typed(types.Types[types.TUINTPTR], got)
+		cond := ir.NewBinaryExpr(pos, ir.ONE, want, got)
+		typed(types.Types[types.TBOOL], cond)
+		panicArg := ir.NewNilExpr(pos)
+		typed(types.NewInterface(types.LocalPkg, nil), panicArg)
+		then := ir.NewUnaryExpr(pos, ir.OPANIC, panicArg)
+		then.SetTypecheck(1)
+		x := ir.NewIfStmt(pos, cond, []ir.Node{then}, nil)
+		x.SetTypecheck(1)
+		code = append(code, x)
+	}
+	return
+}
+
+// getDictionaryEntry gets the i'th entry in the dictionary dict.
+func getDictionaryEntry(pos src.XPos, dict *ir.Name, i int, size int) ir.Node {
+	// Convert dictionary to *[N]uintptr
+	// All entries in the dictionary are pointers. They all point to static data, though, so we
+	// treat them as uintptrs so the GC doesn't need to keep track of them.
+	d := ir.NewConvExpr(pos, ir.OCONVNOP, types.Types[types.TUNSAFEPTR], dict)
+	d.SetTypecheck(1)
+	d = ir.NewConvExpr(pos, ir.OCONVNOP, types.NewArray(types.Types[types.TUINTPTR], int64(size)).PtrTo(), d)
+	d.SetTypecheck(1)
+	types.CheckSize(d.Type().Elem())
+
+	// Load entry i out of the dictionary.
+	deref := ir.NewStarExpr(pos, d)
+	typed(d.Type().Elem(), deref)
+	idx := ir.NewConstExpr(constant.MakeUint64(uint64(i)), dict) // TODO: what to set orig to?
+	typed(types.Types[types.TUINTPTR], idx)
+	r := ir.NewIndexExpr(pos, deref, idx)
+	typed(types.Types[types.TUINTPTR], r)
+	return r
+}
+
+// getDictionaryType returns a *runtime._type from the dictionary entry i (which
+// refers to a type param or a derived type that uses type params). It uses the
+// specified dictionary dictParam, rather than the one in info.dictParam.
+func getDictionaryType(info *instInfo, dictParam *ir.Name, pos src.XPos, i int) ir.Node {
+	if i < 0 || i >= info.startSubDict {
+		base.Fatalf(fmt.Sprintf("bad dict index %d", i))
+	}
+
+	r := getDictionaryEntry(pos, info.dictParam, i, info.startSubDict)
+	// change type of retrieved dictionary entry to *byte, which is the
+	// standard typing of a *runtime._type in the compiler
+	typed(types.Types[types.TUINT8].PtrTo(), r)
+	return r
+}
+
+// node is like DeepCopy(), but substitutes ONAME nodes based on subst.ts.vars, and
+// also descends into closures. It substitutes type arguments for type parameters
+// in all the new nodes.
 func (subst *subster) node(n ir.Node) ir.Node {
 	// Use closure to capture all state needed by the ir.EditChildren argument.
 	var edit func(ir.Node) ir.Node
 	edit = func(x ir.Node) ir.Node {
 		switch x.Op() {
 		case ir.OTYPE:
-			return ir.TypeNode(subst.typ(x.Type()))
+			return ir.TypeNode(subst.ts.Typ(x.Type()))
 
 		case ir.ONAME:
-			name := x.(*ir.Name)
-			if v := subst.vars[name]; v != nil {
+			if v := subst.ts.Vars[x.(*ir.Name)]; v != nil {
 				return v
 			}
-			m := ir.NewNameAt(name.Pos(), name.Sym())
-			if name.IsClosureVar() {
-				m.SetIsClosureVar(true)
-			}
-			t := x.Type()
-			if t == nil {
-				assert(name.BuiltinOp != 0)
-			} else {
-				newt := subst.typ(t)
-				m.SetType(newt)
-			}
-			m.BuiltinOp = name.BuiltinOp
-			m.Curfn = subst.newf
-			m.Class = name.Class
-			m.Func = name.Func
-			subst.vars[name] = m
-			m.SetTypecheck(1)
-			return m
+			return x
+		case ir.ONONAME:
+			// This handles the identifier in a type switch guard
+			fallthrough
 		case ir.OLITERAL, ir.ONIL:
 			if x.Sym() != nil {
 				return x
@@ -369,55 +877,66 @@
 				// an error.
 				_, isCallExpr := m.(*ir.CallExpr)
 				_, isStructKeyExpr := m.(*ir.StructKeyExpr)
-				if !isCallExpr && !isStructKeyExpr && x.Op() != ir.OPANIC &&
+				_, isKeyExpr := m.(*ir.KeyExpr)
+				if !isCallExpr && !isStructKeyExpr && !isKeyExpr && x.Op() != ir.OPANIC &&
 					x.Op() != ir.OCLOSE {
 					base.Fatalf(fmt.Sprintf("Nil type for %v", x))
 				}
 			} else if x.Op() != ir.OCLOSURE {
-				m.SetType(subst.typ(x.Type()))
+				m.SetType(subst.ts.Typ(x.Type()))
 			}
 		}
+
+		for i, de := range subst.info.gfInfo.subDictCalls {
+			if de == x {
+				// Remember the dictionary entry associated with this
+				// node in the instantiated function
+				// TODO: make sure this remains correct with respect to the
+				// transformations below.
+				subst.info.dictEntryMap[m] = subst.info.startSubDict + i
+				break
+			}
+		}
+
 		ir.EditChildren(m, edit)
 
-		if x.Typecheck() == 3 {
-			// These are nodes whose transforms were delayed until
-			// their instantiated type was known.
-			m.SetTypecheck(1)
-			if typecheck.IsCmp(x.Op()) {
-				transformCompare(m.(*ir.BinaryExpr))
-			} else {
-				switch x.Op() {
-				case ir.OSLICE, ir.OSLICE3:
-					transformSlice(m.(*ir.SliceExpr))
+		m.SetTypecheck(1)
+		if typecheck.IsCmp(x.Op()) {
+			transformCompare(m.(*ir.BinaryExpr))
+		} else {
+			switch x.Op() {
+			case ir.OSLICE, ir.OSLICE3:
+				transformSlice(m.(*ir.SliceExpr))
 
-				case ir.OADD:
-					m = transformAdd(m.(*ir.BinaryExpr))
+			case ir.OADD:
+				m = transformAdd(m.(*ir.BinaryExpr))
 
-				case ir.OINDEX:
-					transformIndex(m.(*ir.IndexExpr))
+			case ir.OINDEX:
+				transformIndex(m.(*ir.IndexExpr))
 
-				case ir.OAS2:
-					as2 := m.(*ir.AssignListStmt)
-					transformAssign(as2, as2.Lhs, as2.Rhs)
+			case ir.OAS2:
+				as2 := m.(*ir.AssignListStmt)
+				transformAssign(as2, as2.Lhs, as2.Rhs)
 
-				case ir.OAS:
-					as := m.(*ir.AssignStmt)
+			case ir.OAS:
+				as := m.(*ir.AssignStmt)
+				if as.Y != nil {
+					// transformAssign doesn't handle the case
+					// of zeroing assignment of a dcl (rhs[0] is nil).
 					lhs, rhs := []ir.Node{as.X}, []ir.Node{as.Y}
 					transformAssign(as, lhs, rhs)
-
-				case ir.OASOP:
-					as := m.(*ir.AssignOpStmt)
-					transformCheckAssign(as, as.X)
-
-				case ir.ORETURN:
-					transformReturn(m.(*ir.ReturnStmt))
-
-				case ir.OSEND:
-					transformSend(m.(*ir.SendStmt))
-
-				default:
-					base.Fatalf("Unexpected node with Typecheck() == 3")
 				}
+
+			case ir.OASOP:
+				as := m.(*ir.AssignOpStmt)
+				transformCheckAssign(as, as.X)
+
+			case ir.ORETURN:
+				transformReturn(m.(*ir.ReturnStmt))
+
+			case ir.OSEND:
+				transformSend(m.(*ir.SendStmt))
+
 			}
 		}
 
@@ -445,11 +964,40 @@
 			// instantiated receiver type. We need to do this now,
 			// since the access/selection to the method for the real
 			// type is very different from the selection for the type
-			// param. m will be transformed to an OCALLPART node. It
+			// param. m will be transformed to an OMETHVALUE node. It
 			// will be transformed to an ODOTMETH or ODOTINTER node if
 			// we find in the OCALL case below that the method value
 			// is actually called.
-			transformDot(m.(*ir.SelectorExpr), false)
+			mse := m.(*ir.SelectorExpr)
+			if src := mse.X.Type(); src.IsShape() {
+				// The only dot on a shape type value are methods.
+				if mse.X.Op() == ir.OTYPE {
+					// Method expression T.M
+					m = subst.g.buildClosure2(subst, m, x)
+					// No need for transformDot - buildClosure2 has already
+					// transformed to OCALLINTER/ODOTINTER.
+				} else {
+					// Implement x.M as a conversion-to-bound-interface
+					//  1) convert x to the bound interface
+					//  2) call M on that interface
+					gsrc := x.(*ir.SelectorExpr).X.Type()
+					bound := gsrc.Bound()
+					dst := bound
+					if dst.HasTParam() {
+						dst = subst.ts.Typ(dst)
+					}
+					if src.IsInterface() {
+						// If type arg is an interface (unusual case),
+						// we do a type assert to the type bound.
+						mse.X = assertToBound(subst.info, subst.info.dictParam, m.Pos(), mse.X, bound, dst)
+					} else {
+						mse.X = convertUsingDictionary(subst.info, subst.info.dictParam, m.Pos(), mse.X, x, dst, gsrc)
+					}
+					transformDot(mse, false)
+				}
+			} else {
+				transformDot(mse, false)
+			}
 			m.SetTypecheck(1)
 
 		case ir.OCALL:
@@ -458,9 +1006,11 @@
 			case ir.OTYPE:
 				// Transform the conversion, now that we know the
 				// type argument.
-				m = transformConvCall(m.(*ir.CallExpr))
+				m = transformConvCall(call)
+				// CONVIFACE transformation was already done in node2
+				assert(m.Op() != ir.OCONVIFACE)
 
-			case ir.OCALLPART:
+			case ir.OMETHVALUE, ir.OMETHEXPR:
 				// Redo the transformation of OXDOT, now that we
 				// know the method value is being called. Then
 				// transform the call.
@@ -479,7 +1029,7 @@
 				name := call.X.Name()
 				if name.BuiltinOp != ir.OXXX {
 					switch name.BuiltinOp {
-					case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OLEN, ir.OCAP, ir.OAPPEND:
+					case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.ODELETE:
 						// Transform these builtins now that we
 						// know the type of the args.
 						m = transformBuiltin(call)
@@ -506,41 +1056,127 @@
 			}
 
 		case ir.OCLOSURE:
+			// We're going to create a new closure from scratch, so clear m
+			// to avoid using the ir.Copy by accident until we reassign it.
+			m = nil
+
 			x := x.(*ir.ClosureExpr)
 			// Need to duplicate x.Func.Nname, x.Func.Dcl, x.Func.ClosureVars, and
 			// x.Func.Body.
 			oldfn := x.Func
-			newfn := ir.NewFunc(oldfn.Pos())
-			if oldfn.ClosureCalled() {
-				newfn.SetClosureCalled(true)
-			}
-			newfn.SetIsHiddenClosure(true)
-			m.(*ir.ClosureExpr).Func = newfn
-			// Closure name can already have brackets, if it derives
-			// from a generic method
-			newsym := makeInstName(oldfn.Nname.Sym(), subst.targs, subst.isMethod)
-			newfn.Nname = ir.NewNameAt(oldfn.Nname.Pos(), newsym)
-			newfn.Nname.Func = newfn
-			newfn.Nname.Defn = newfn
-			ir.MarkFunc(newfn.Nname)
-			newfn.OClosure = m.(*ir.ClosureExpr)
+			newfn := ir.NewClosureFunc(oldfn.Pos(), subst.newf != nil)
+			ir.NameClosure(newfn.OClosure, subst.newf)
 
 			saveNewf := subst.newf
 			ir.CurFunc = newfn
 			subst.newf = newfn
 			newfn.Dcl = subst.namelist(oldfn.Dcl)
-			newfn.ClosureVars = subst.namelist(oldfn.ClosureVars)
 
-			typed(subst.typ(oldfn.Nname.Type()), newfn.Nname)
-			typed(newfn.Nname.Type(), m)
+			// Make a closure variable for the dictionary of the
+			// containing function.
+			cdict := ir.CaptureName(oldfn.Pos(), newfn, subst.info.dictParam)
+			typed(types.Types[types.TUINTPTR], cdict)
+			ir.FinishCaptureNames(oldfn.Pos(), saveNewf, newfn)
+			newfn.ClosureVars = append(newfn.ClosureVars, subst.namelist(oldfn.ClosureVars)...)
+
+			// Create inst info for the instantiated closure. The dict
+			// param is the closure variable for the dictionary of the
+			// outer function. Since the dictionary is shared, use the
+			// same entries for startSubDict, dictLen, dictEntryMap.
+			cinfo := &instInfo{
+				fun:           newfn,
+				dictParam:     cdict,
+				gf:            subst.info.gf,
+				gfInfo:        subst.info.gfInfo,
+				startSubDict:  subst.info.startSubDict,
+				startItabConv: subst.info.startItabConv,
+				dictLen:       subst.info.dictLen,
+				dictEntryMap:  subst.info.dictEntryMap,
+			}
+			subst.g.instInfoMap[newfn.Nname.Sym()] = cinfo
+
+			typed(subst.ts.Typ(oldfn.Nname.Type()), newfn.Nname)
+			typed(newfn.Nname.Type(), newfn.OClosure)
 			newfn.SetTypecheck(1)
 
+			outerinfo := subst.info
+			subst.info = cinfo
 			// Make sure type of closure function is set before doing body.
 			newfn.Body = subst.list(oldfn.Body)
+			subst.info = outerinfo
 			subst.newf = saveNewf
 			ir.CurFunc = saveNewf
 
-			subst.g.target.Decls = append(subst.g.target.Decls, newfn)
+			m = ir.UseClosure(newfn.OClosure, subst.g.target)
+			m.(*ir.ClosureExpr).SetInit(subst.list(x.Init()))
+
+		case ir.OCONVIFACE:
+			x := x.(*ir.ConvExpr)
+			// Note: x's argument is still typed as a type parameter.
+			// m's argument now has an instantiated type.
+			if x.X.Type().HasTParam() {
+				m = convertUsingDictionary(subst.info, subst.info.dictParam, m.Pos(), m.(*ir.ConvExpr).X, x, m.Type(), x.X.Type())
+			}
+		case ir.ODOTTYPE, ir.ODOTTYPE2:
+			dt := m.(*ir.TypeAssertExpr)
+			var rt ir.Node
+			if dt.Type().IsInterface() || dt.X.Type().IsEmptyInterface() {
+				ix := findDictType(subst.info, x.Type())
+				assert(ix >= 0)
+				rt = getDictionaryType(subst.info, subst.info.dictParam, dt.Pos(), ix)
+			} else {
+				// nonempty interface to noninterface. Need an itab.
+				ix := -1
+				for i, ic := range subst.info.gfInfo.itabConvs {
+					if ic == x {
+						ix = subst.info.startItabConv + i
+						break
+					}
+				}
+				assert(ix >= 0)
+				rt = getDictionaryEntry(dt.Pos(), subst.info.dictParam, ix, subst.info.dictLen)
+			}
+			op := ir.ODYNAMICDOTTYPE
+			if x.Op() == ir.ODOTTYPE2 {
+				op = ir.ODYNAMICDOTTYPE2
+			}
+			m = ir.NewDynamicTypeAssertExpr(dt.Pos(), op, dt.X, rt)
+			m.SetType(dt.Type())
+			m.SetTypecheck(1)
+		case ir.OCASE:
+			if _, ok := x.(*ir.CommClause); ok {
+				// This is not a type switch. TODO: Should we use an OSWITCH case here instead of OCASE?
+				break
+			}
+			x := x.(*ir.CaseClause)
+			m := m.(*ir.CaseClause)
+			for i, c := range x.List {
+				if c.Op() == ir.OTYPE && c.Type().HasTParam() {
+					// Use a *runtime._type for the dynamic type.
+					ix := findDictType(subst.info, c.Type())
+					assert(ix >= 0)
+					dt := ir.NewDynamicType(c.Pos(), getDictionaryEntry(c.Pos(), subst.info.dictParam, ix, subst.info.dictLen))
+
+					// For type switch from nonempty interfaces to non-interfaces, we need an itab as well.
+					if !m.List[i].Type().IsInterface() {
+						if _, ok := subst.info.gfInfo.type2switchType[c]; ok {
+							// Type switch from nonempty interface. We need a *runtime.itab
+							// for the dynamic type.
+							ix := -1
+							for i, ic := range subst.info.gfInfo.itabConvs {
+								if ic == c {
+									ix = subst.info.startItabConv + i
+									break
+								}
+							}
+							assert(ix >= 0)
+							dt.ITab = getDictionaryEntry(c.Pos(), subst.info.dictParam, ix, subst.info.dictLen)
+						}
+					}
+					typed(m.List[i].Type(), dt)
+					m.List[i] = dt
+				}
+			}
 		}
 		return m
 	}
@@ -548,10 +1184,73 @@
 	return edit(n)
 }
 
+// findDictType looks for type t in the typeparams or derived types in the generic
+// function info.gfInfo. This will indicate the dictionary entry with the
+// correct concrete type for the associated instantiated function.
+func findDictType(info *instInfo, t *types.Type) int {
+	for i, dt := range info.gfInfo.tparams {
+		if dt == t {
+			return i
+		}
+	}
+	for i, dt := range info.gfInfo.derivedTypes {
+		if types.Identical(dt, t) {
+			return i + len(info.gfInfo.tparams)
+		}
+	}
+	return -1
+}
+
+// convertUsingDictionary converts value v from instantiated type src to an interface
+// type dst, by returning a new set of nodes that make use of a dictionary entry. src
+// is the generic (not shape) type, and gn is the original generic node of the
+// CONVIFACE node or XDOT node (for a bound method call) that is causing the
+// conversion.
+func convertUsingDictionary(info *instInfo, dictParam *ir.Name, pos src.XPos, v ir.Node, gn ir.Node, dst, src *types.Type) ir.Node {
+	assert(src.HasTParam())
+	assert(dst.IsInterface())
+
+	var rt ir.Node
+	if !dst.IsEmptyInterface() {
+		// We should have an itab entry in the dictionary. Using this itab
+		// will be more efficient than converting to an empty interface first
+		// and then type asserting to dst.
+		ix := -1
+		for i, ic := range info.gfInfo.itabConvs {
+			if ic == gn {
+				ix = info.startItabConv + i
+				break
+			}
+		}
+		assert(ix >= 0)
+		rt = getDictionaryEntry(pos, dictParam, ix, info.dictLen)
+	} else {
+		ix := findDictType(info, src)
+		assert(ix >= 0)
+		// Load the actual runtime._type of the type parameter from the dictionary.
+		rt = getDictionaryType(info, dictParam, pos, ix)
+	}
+
+	// Figure out what the data field of the interface will be.
+	var data ir.Node
+	if v.Type().IsInterface() {
+		data = ir.NewUnaryExpr(pos, ir.OIDATA, v)
+	} else {
+		data = ir.NewConvExpr(pos, ir.OCONVIDATA, nil, v)
+	}
+	typed(types.Types[types.TUNSAFEPTR], data)
+
+	// Build an interface from the type and data parts.
+	var i ir.Node = ir.NewBinaryExpr(pos, ir.OEFACE, rt, data)
+	typed(dst, i)
+	return i
+
+}
+
 func (subst *subster) namelist(l []*ir.Name) []*ir.Name {
 	s := make([]*ir.Name, len(l))
 	for i, n := range l {
-		s[i] = subst.node(n).(*ir.Name)
+		s[i] = subst.localvar(n)
 		if n.Defn != nil {
 			s[i].Defn = subst.node(n.Defn)
 		}
@@ -570,302 +1269,6 @@
 	return s
 }
 
-// tstruct substitutes type params in types of the fields of a structure type. For
-// each field, if Nname is set, tstruct also translates the Nname using
-// subst.vars, if Nname is in subst.vars. To always force the creation of a new
-// (top-level) struct, regardless of whether anything changed with the types or
-// names of the struct's fields, set force to true.
-func (subst *subster) tstruct(t *types.Type, force bool) *types.Type {
-	if t.NumFields() == 0 {
-		if t.HasTParam() {
-			// For an empty struct, we need to return a new type,
-			// since it may now be fully instantiated (HasTParam
-			// becomes false).
-			return types.NewStruct(t.Pkg(), nil)
-		}
-		return t
-	}
-	var newfields []*types.Field
-	if force {
-		newfields = make([]*types.Field, t.NumFields())
-	}
-	for i, f := range t.Fields().Slice() {
-		t2 := subst.typ(f.Type)
-		if (t2 != f.Type || f.Nname != nil) && newfields == nil {
-			newfields = make([]*types.Field, t.NumFields())
-			for j := 0; j < i; j++ {
-				newfields[j] = t.Field(j)
-			}
-		}
-		if newfields != nil {
-			// TODO(danscales): make sure this works for the field
-			// names of embedded types (which should keep the name of
-			// the type param, not the instantiated type).
-			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
-			if f.Nname != nil {
-				// f.Nname may not be in subst.vars[] if this is
-				// a function name or a function instantiation type
-				// that we are translating
-				v := subst.vars[f.Nname.(*ir.Name)]
-				// Be careful not to put a nil var into Nname,
-				// since Nname is an interface, so it would be a
-				// non-nil interface.
-				if v != nil {
-					newfields[i].Nname = v
-				}
-			}
-		}
-	}
-	if newfields != nil {
-		return types.NewStruct(t.Pkg(), newfields)
-	}
-	return t
-
-}
-
-// tinter substitutes type params in types of the methods of an interface type.
-func (subst *subster) tinter(t *types.Type) *types.Type {
-	if t.Methods().Len() == 0 {
-		return t
-	}
-	var newfields []*types.Field
-	for i, f := range t.Methods().Slice() {
-		t2 := subst.typ(f.Type)
-		if (t2 != f.Type || f.Nname != nil) && newfields == nil {
-			newfields = make([]*types.Field, t.Methods().Len())
-			for j := 0; j < i; j++ {
-				newfields[j] = t.Methods().Index(j)
-			}
-		}
-		if newfields != nil {
-			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
-		}
-	}
-	if newfields != nil {
-		return types.NewInterface(t.Pkg(), newfields)
-	}
-	return t
-}
-
-// instTypeName creates a name for an instantiated type, based on the name of the
-// generic type and the type args
-func instTypeName(name string, targs []*types.Type) string {
-	b := bytes.NewBufferString(name)
-	b.WriteByte('[')
-	for i, targ := range targs {
-		if i > 0 {
-			b.WriteByte(',')
-		}
-		b.WriteString(targ.String())
-	}
-	b.WriteByte(']')
-	return b.String()
-}
-
-// typ computes the type obtained by substituting any type parameter in t with the
-// corresponding type argument in subst. If t contains no type parameters, the
-// result is t; otherwise the result is a new type. It deals with recursive types
-// by using TFORW types and finding partially or fully created types via sym.Def.
-func (subst *subster) typ(t *types.Type) *types.Type {
-	if !t.HasTParam() && t.Kind() != types.TFUNC {
-		// Note: function types need to be copied regardless, as the
-		// types of closures may contain declarations that need
-		// to be copied. See #45738.
-		return t
-	}
-
-	if t.Kind() == types.TTYPEPARAM {
-		for i, tp := range subst.tparams {
-			if tp.Type == t {
-				return subst.targs[i].Type()
-			}
-		}
-		// If t is a simple typeparam T, then t has the name/symbol 'T'
-		// and t.Underlying() == t.
-		//
-		// However, consider the type definition: 'type P[T any] T'. We
-		// might use this definition so we can have a variant of type T
-		// that we can add new methods to. Suppose t is a reference to
-		// P[T]. t has the name 'P[T]', but its kind is TTYPEPARAM,
-		// because P[T] is defined as T. If we look at t.Underlying(), it
-		// is different, because the name of t.Underlying() is 'T' rather
-		// than 'P[T]'. But the kind of t.Underlying() is also TTYPEPARAM.
-		// In this case, we do the needed recursive substitution in the
-		// case statement below.
-		if t.Underlying() == t {
-			// t is a simple typeparam that didn't match anything in tparam
-			return t
-		}
-		// t is a more complex typeparam (e.g. P[T], as above, whose
-		// definition is just T).
-		assert(t.Sym() != nil)
-	}
-
-	var newsym *types.Sym
-	var neededTargs []*types.Type
-	var forw *types.Type
-
-	if t.Sym() != nil {
-		// Translate the type params for this type according to
-		// the tparam/targs mapping from subst.
-		neededTargs = make([]*types.Type, len(t.RParams()))
-		for i, rparam := range t.RParams() {
-			neededTargs[i] = subst.typ(rparam)
-		}
-		// For a named (defined) type, we have to change the name of the
-		// type as well. We do this first, so we can look up if we've
-		// already seen this type during this substitution or other
-		// definitions/substitutions.
-		genName := genericTypeName(t.Sym())
-		newsym = t.Sym().Pkg.Lookup(instTypeName(genName, neededTargs))
-		if newsym.Def != nil {
-			// We've already created this instantiated defined type.
-			return newsym.Def.Type()
-		}
-
-		// In order to deal with recursive generic types, create a TFORW
-		// type initially and set the Def field of its sym, so it can be
-		// found if this type appears recursively within the type.
-		forw = newIncompleteNamedType(t.Pos(), newsym)
-		//println("Creating new type by sub", newsym.Name, forw.HasTParam())
-		forw.SetRParams(neededTargs)
-	}
-
-	var newt *types.Type
-
-	switch t.Kind() {
-	case types.TTYPEPARAM:
-		if t.Sym() == newsym {
-			// The substitution did not change the type.
-			return t
-		}
-		// Substitute the underlying typeparam (e.g. T in P[T], see
-		// the example describing type P[T] above).
-		newt = subst.typ(t.Underlying())
-		assert(newt != t)
-
-	case types.TARRAY:
-		elem := t.Elem()
-		newelem := subst.typ(elem)
-		if newelem != elem {
-			newt = types.NewArray(newelem, t.NumElem())
-		}
-
-	case types.TPTR:
-		elem := t.Elem()
-		newelem := subst.typ(elem)
-		if newelem != elem {
-			newt = types.NewPtr(newelem)
-		}
-
-	case types.TSLICE:
-		elem := t.Elem()
-		newelem := subst.typ(elem)
-		if newelem != elem {
-			newt = types.NewSlice(newelem)
-		}
-
-	case types.TSTRUCT:
-		newt = subst.tstruct(t, false)
-		if newt == t {
-			newt = nil
-		}
-
-	case types.TFUNC:
-		newrecvs := subst.tstruct(t.Recvs(), false)
-		newparams := subst.tstruct(t.Params(), false)
-		newresults := subst.tstruct(t.Results(), false)
-		if newrecvs != t.Recvs() || newparams != t.Params() || newresults != t.Results() {
-			// If any types have changed, then the all the fields of
-			// of recv, params, and results must be copied, because they have
-			// offset fields that are dependent, and so must have an
-			// independent copy for each new signature.
-			var newrecv *types.Field
-			if newrecvs.NumFields() > 0 {
-				if newrecvs == t.Recvs() {
-					newrecvs = subst.tstruct(t.Recvs(), true)
-				}
-				newrecv = newrecvs.Field(0)
-			}
-			if newparams == t.Params() {
-				newparams = subst.tstruct(t.Params(), true)
-			}
-			if newresults == t.Results() {
-				newresults = subst.tstruct(t.Results(), true)
-			}
-			newt = types.NewSignature(t.Pkg(), newrecv, t.TParams().FieldSlice(), newparams.FieldSlice(), newresults.FieldSlice())
-		}
-
-	case types.TINTER:
-		newt = subst.tinter(t)
-		if newt == t {
-			newt = nil
-		}
-
-	case types.TMAP:
-		newkey := subst.typ(t.Key())
-		newval := subst.typ(t.Elem())
-		if newkey != t.Key() || newval != t.Elem() {
-			newt = types.NewMap(newkey, newval)
-		}
-
-	case types.TCHAN:
-		elem := t.Elem()
-		newelem := subst.typ(elem)
-		if newelem != elem {
-			newt = types.NewChan(newelem, t.ChanDir())
-			if !newt.HasTParam() {
-				// TODO(danscales): not sure why I have to do this
-				// only for channels.....
-				types.CheckSize(newt)
-			}
-		}
-	}
-	if newt == nil {
-		// Even though there were typeparams in the type, there may be no
-		// change if this is a function type for a function call (which will
-		// have its own tparams/targs in the function instantiation).
-		return t
-	}
-
-	if t.Sym() == nil {
-		// Not a named type, so there was no forwarding type and there are
-		// no methods to substitute.
-		assert(t.Methods().Len() == 0)
-		return newt
-	}
-
-	forw.SetUnderlying(newt)
-	newt = forw
-
-	if t.Kind() != types.TINTER && t.Methods().Len() > 0 {
-		// Fill in the method info for the new type.
-		var newfields []*types.Field
-		newfields = make([]*types.Field, t.Methods().Len())
-		for i, f := range t.Methods().Slice() {
-			t2 := subst.typ(f.Type)
-			oldsym := f.Nname.Sym()
-			newsym := makeInstName(oldsym, subst.targs, true)
-			var nname *ir.Name
-			if newsym.Def != nil {
-				nname = newsym.Def.(*ir.Name)
-			} else {
-				nname = ir.NewNameAt(f.Pos, newsym)
-				nname.SetType(t2)
-				newsym.Def = nname
-			}
-			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
-			newfields[i].Nname = nname
-		}
-		newt.Methods().Set(newfields)
-		if !newt.HasTParam() {
-			// Generate all the methods for a new fully-instantiated type.
-			subst.g.instTypeList = append(subst.g.instTypeList, newt)
-		}
-	}
-	return newt
-}
-
 // fields sets the Nname field for the Field nodes inside a type signature, based
 // on the corresponding in/out parameters in dcl. It depends on the in and out
 // parameters being in order in dcl.
@@ -885,12 +1288,15 @@
 	newfields := make([]*types.Field, len(oldfields))
 	for j := range oldfields {
 		newfields[j] = oldfields[j].Copy()
-		newfields[j].Type = subst.typ(oldfields[j].Type)
-		// A param field will be missing from dcl if its name is
+		newfields[j].Type = subst.ts.Typ(oldfields[j].Type)
+		// A PPARAM field will be missing from dcl if its name is
 		// unspecified or specified as "_". So, we compare the dcl sym
-		// with the field sym. If they don't match, this dcl (if there is
-		// one left) must apply to a later field.
-		if i < len(dcl) && dcl[i].Sym() == oldfields[j].Sym {
+		// with the field sym (or sym of the field's Nname node). (Unnamed
+		// results still have a name like ~r2 in their Nname node.) If
+		// they don't match, this dcl (if there is one left) must apply to
+		// a later field.
+		if i < len(dcl) && (dcl[i].Sym() == oldfields[j].Sym ||
+			(oldfields[j].Nname != nil && dcl[i].Sym() == oldfields[j].Nname.Sym())) {
 			newfields[j].Nname = dcl[i]
 			i++
 		}
@@ -898,7 +1304,7 @@
 	return newfields
 }
 
-// defer does a single defer of type t, if it is a pointer type.
+// deref does a single deref of type t, if it is a pointer type.
 func deref(t *types.Type) *types.Type {
 	if t.IsPtr() {
 		return t.Elem()
@@ -906,12 +1312,658 @@
 	return t
 }
 
-// newIncompleteNamedType returns a TFORW type t with name specified by sym, such
-// that t.nod and sym.Def are set correctly.
-func newIncompleteNamedType(pos src.XPos, sym *types.Sym) *types.Type {
-	name := ir.NewDeclNameAt(pos, ir.OTYPE, sym)
-	forw := types.NewNamed(name)
-	name.SetType(forw)
-	sym.Def = name
-	return forw
+// markTypeUsed marks type t as used in order to help avoid dead-code elimination of
+// needed methods.
+func markTypeUsed(t *types.Type, lsym *obj.LSym) {
+	if t.IsInterface() {
+		// Mark all the methods of the interface as used.
+		// TODO: we should really only mark the interface methods
+		// that are actually called in the application.
+		for i, _ := range t.AllMethods().Slice() {
+			reflectdata.MarkUsedIfaceMethodIndex(lsym, t, i)
+		}
+	} else {
+		// TODO: This is somewhat overkill, we really only need it
+		// for types that are put into interfaces.
+		reflectdata.MarkTypeUsedInInterface(t, lsym)
+	}
+}
+
+// getDictionarySym returns the dictionary for the named generic function gf, which
+// is instantiated with the type arguments targs.
+func (g *irgen) getDictionarySym(gf *ir.Name, targs []*types.Type, isMeth bool) *types.Sym {
+	if len(targs) == 0 {
+		base.Fatalf("%s should have type arguments", gf.Sym().Name)
+	}
+
+	// Enforce that only concrete types can make it to here.
+	for _, t := range targs {
+		if t.HasShape() {
+			panic(fmt.Sprintf("shape %+v in dictionary for %s", t, gf.Sym().Name))
+		}
+	}
+
+	// Get a symbol representing the dictionary.
+	sym := typecheck.MakeDictName(gf.Sym(), targs, isMeth)
+
+	// Initialize the dictionary, if we haven't yet already.
+	lsym := sym.Linksym()
+	if len(lsym.P) > 0 {
+		// We already started creating this dictionary and its lsym.
+		return sym
+	}
+
+	info := g.getGfInfo(gf)
+
+	infoPrint("=== Creating dictionary %v\n", sym.Name)
+	off := 0
+	// Emit an entry for each targ (concrete type or gcshape).
+	for _, t := range targs {
+		infoPrint(" * %v\n", t)
+		s := reflectdata.TypeLinksym(t)
+		off = objw.SymPtr(lsym, off, s, 0)
+		markTypeUsed(t, lsym)
+	}
+	subst := typecheck.Tsubster{
+		Tparams: info.tparams,
+		Targs:   targs,
+	}
+	// Emit an entry for each derived type (after substituting targs)
+	for _, t := range info.derivedTypes {
+		ts := subst.Typ(t)
+		infoPrint(" - %v\n", ts)
+		s := reflectdata.TypeLinksym(ts)
+		off = objw.SymPtr(lsym, off, s, 0)
+		markTypeUsed(ts, lsym)
+	}
+	// Emit an entry for each subdictionary (after substituting targs)
+	for _, n := range info.subDictCalls {
+		var sym *types.Sym
+		switch n.Op() {
+		case ir.OCALL:
+			call := n.(*ir.CallExpr)
+			if call.X.Op() == ir.OXDOT {
+				var nameNode *ir.Name
+				se := call.X.(*ir.SelectorExpr)
+				if types.IsInterfaceMethod(se.Selection.Type) {
+					// This is a method call enabled by a type bound.
+					tmpse := ir.NewSelectorExpr(base.Pos, ir.OXDOT, se.X, se.Sel)
+					tmpse = typecheck.AddImplicitDots(tmpse)
+					tparam := tmpse.X.Type()
+					assert(tparam.IsTypeParam())
+					recvType := targs[tparam.Index()]
+					if recvType.IsInterface() || len(recvType.RParams()) == 0 {
+						// No sub-dictionary entry is
+						// actually needed, since the
+						// type arg is not an
+						// instantiated type that
+						// will have generic methods.
+						break
+					}
+					// This is a method call for an
+					// instantiated type, so we need a
+					// sub-dictionary.
+					targs := recvType.RParams()
+					genRecvType := recvType.OrigSym.Def.Type()
+					nameNode = typecheck.Lookdot1(call.X, se.Sel, genRecvType, genRecvType.Methods(), 1).Nname.(*ir.Name)
+					sym = g.getDictionarySym(nameNode, targs, true)
+				} else {
+					// This is the case of a normal
+					// method call on a generic type.
+					nameNode = call.X.(*ir.SelectorExpr).Selection.Nname.(*ir.Name)
+					subtargs := deref(call.X.(*ir.SelectorExpr).X.Type()).RParams()
+					s2targs := make([]*types.Type, len(subtargs))
+					for i, t := range subtargs {
+						s2targs[i] = subst.Typ(t)
+					}
+					sym = g.getDictionarySym(nameNode, s2targs, true)
+				}
+			} else {
+				inst := call.X.(*ir.InstExpr)
+				var nameNode *ir.Name
+				var meth *ir.SelectorExpr
+				var isMeth bool
+				if meth, isMeth = inst.X.(*ir.SelectorExpr); isMeth {
+					nameNode = meth.Selection.Nname.(*ir.Name)
+				} else {
+					nameNode = inst.X.(*ir.Name)
+				}
+				subtargs := typecheck.TypesOf(inst.Targs)
+				for i, t := range subtargs {
+					subtargs[i] = subst.Typ(t)
+				}
+				sym = g.getDictionarySym(nameNode, subtargs, isMeth)
+			}
+
+		case ir.OFUNCINST:
+			inst := n.(*ir.InstExpr)
+			nameNode := inst.X.(*ir.Name)
+			subtargs := typecheck.TypesOf(inst.Targs)
+			for i, t := range subtargs {
+				subtargs[i] = subst.Typ(t)
+			}
+			sym = g.getDictionarySym(nameNode, subtargs, false)
+
+		case ir.OXDOT:
+			selExpr := n.(*ir.SelectorExpr)
+			subtargs := deref(selExpr.X.Type()).RParams()
+			s2targs := make([]*types.Type, len(subtargs))
+			for i, t := range subtargs {
+				s2targs[i] = subst.Typ(t)
+			}
+			nameNode := selExpr.Selection.Nname.(*ir.Name)
+			sym = g.getDictionarySym(nameNode, s2targs, true)
+
+		default:
+			assert(false)
+		}
+
+		if sym == nil {
+			// Unused sub-dictionary entry, just emit 0.
+			off = objw.Uintptr(lsym, off, 0)
+			infoPrint(" - Unused subdict entry\n")
+		} else {
+			off = objw.SymPtr(lsym, off, sym.Linksym(), 0)
+			infoPrint(" - Subdict %v\n", sym.Name)
+		}
+	}
+
+	delay := &delayInfo{
+		gf:    gf,
+		targs: targs,
+		sym:   sym,
+		off:   off,
+	}
+	g.dictSymsToFinalize = append(g.dictSymsToFinalize, delay)
+	g.instTypeList = append(g.instTypeList, subst.InstTypeList...)
+	return sym
+}
+
+// finalizeSyms finishes up all dictionaries on g.dictSymsToFinalize, by writing out
+// any needed LSyms for itabs. The itab lsyms create wrappers which need various
+// dictionaries and method instantiations to be complete, so, to avoid recursive
+// dependencies, we finalize the itab lsyms only after all dictionaries syms and
+// instantiations have been created.
+func (g *irgen) finalizeSyms() {
+	for _, d := range g.dictSymsToFinalize {
+		infoPrint("=== Finalizing dictionary %s\n", d.sym.Name)
+
+		lsym := d.sym.Linksym()
+		info := g.getGfInfo(d.gf)
+
+		subst := typecheck.Tsubster{
+			Tparams: info.tparams,
+			Targs:   d.targs,
+		}
+
+		// Emit an entry for each itab
+		for _, n := range info.itabConvs {
+			var srctype, dsttype *types.Type
+			switch n.Op() {
+			case ir.OXDOT:
+				se := n.(*ir.SelectorExpr)
+				srctype = subst.Typ(se.X.Type())
+				dsttype = subst.Typ(se.X.Type().Bound())
+				found := false
+				for i, m := range dsttype.AllMethods().Slice() {
+					if se.Sel == m.Sym {
+						// Mark that this method se.Sel is
+						// used for the dsttype interface, so
+						// it won't get deadcoded.
+						reflectdata.MarkUsedIfaceMethodIndex(lsym, dsttype, i)
+						found = true
+						break
+					}
+				}
+				assert(found)
+			case ir.ODOTTYPE, ir.ODOTTYPE2:
+				srctype = subst.Typ(n.(*ir.TypeAssertExpr).Type())
+				dsttype = subst.Typ(n.(*ir.TypeAssertExpr).X.Type())
+			case ir.OCONVIFACE:
+				srctype = subst.Typ(n.(*ir.ConvExpr).X.Type())
+				dsttype = subst.Typ(n.Type())
+			case ir.OTYPE:
+				srctype = subst.Typ(n.Type())
+				dsttype = subst.Typ(info.type2switchType[n])
+			default:
+				base.Fatalf("itab entry with unknown op %s", n.Op())
+			}
+			if srctype.IsInterface() {
+				// No itab is wanted if src type is an interface. We
+				// will use a type assert instead.
+				d.off = objw.Uintptr(lsym, d.off, 0)
+				infoPrint(" + Unused itab entry for %v\n", srctype)
+			} else {
+				itabLsym := reflectdata.ITabLsym(srctype, dsttype)
+				d.off = objw.SymPtr(lsym, d.off, itabLsym, 0)
+				infoPrint(" + Itab for (%v,%v)\n", srctype, dsttype)
+			}
+		}
+
+		objw.Global(lsym, int32(d.off), obj.DUPOK|obj.RODATA)
+		infoPrint("=== Finalized dictionary %s\n", d.sym.Name)
+
+		g.instTypeList = append(g.instTypeList, subst.InstTypeList...)
+	}
+	g.dictSymsToFinalize = nil
+}
+
+func (g *irgen) getDictionaryValue(gf *ir.Name, targs []*types.Type, isMeth bool) ir.Node {
+	sym := g.getDictionarySym(gf, targs, isMeth)
+
+	// Make a node referencing the dictionary symbol.
+	n := typecheck.NewName(sym)
+	n.SetType(types.Types[types.TUINTPTR]) // should probably be [...]uintptr, but doesn't really matter
+	n.SetTypecheck(1)
+	n.Class = ir.PEXTERN
+	sym.Def = n
+
+	// Return the address of the dictionary.
+	np := typecheck.NodAddr(n)
+	// Note: treat dictionary pointers as uintptrs, so they aren't pointers
+	// with respect to GC. That saves on stack scanning work, write barriers, etc.
+	// We can get away with it because dictionaries are global variables.
+	// TODO: use a cast, or is typing directly ok?
+	np.SetType(types.Types[types.TUINTPTR])
+	np.SetTypecheck(1)
+	return np
+}
+
+// hasTParamNodes returns true if the type of any node in targs has a typeparam.
+func hasTParamNodes(targs []ir.Node) bool {
+	for _, n := range targs {
+		if n.Type().HasTParam() {
+			return true
+		}
+	}
+	return false
+}
+
+// hasTParamNodes returns true if any type in targs has a typeparam.
+func hasTParamTypes(targs []*types.Type) bool {
+	for _, t := range targs {
+		if t.HasTParam() {
+			return true
+		}
+	}
+	return false
+}
+
+// getGfInfo get information for a generic function - type params, derived generic
+// types, and subdictionaries.
+func (g *irgen) getGfInfo(gn *ir.Name) *gfInfo {
+	infop := g.gfInfoMap[gn.Sym()]
+	if infop != nil {
+		return infop
+	}
+
+	checkFetchBody(gn)
+	var info gfInfo
+	gf := gn.Func
+	recv := gf.Type().Recv()
+	if recv != nil {
+		info.tparams = deref(recv.Type).RParams()
+	} else {
+		tparams := gn.Type().TParams().FieldSlice()
+		info.tparams = make([]*types.Type, len(tparams))
+		for i, f := range tparams {
+			info.tparams[i] = f.Type
+		}
+	}
+
+	for _, t := range info.tparams {
+		b := t.Bound()
+		if b.HasTParam() {
+			// If a type bound is parameterized (unusual case), then we
+			// may need its derived type to do a type assert when doing a
+			// bound call for a type arg that is an interface.
+			addType(&info, nil, b)
+		}
+	}
+
+	for _, n := range gf.Dcl {
+		addType(&info, n, n.Type())
+	}
+
+	if infoPrintMode {
+		fmt.Printf(">>> GfInfo for %v\n", gn)
+		for _, t := range info.tparams {
+			fmt.Printf("  Typeparam %v\n", t)
+		}
+	}
+
+	var visitFunc func(ir.Node)
+	visitFunc = func(n ir.Node) {
+		if n.Op() == ir.OFUNCINST && !n.(*ir.InstExpr).Implicit() {
+			if hasTParamNodes(n.(*ir.InstExpr).Targs) {
+				infoPrint("  Closure&subdictionary required at generic function value %v\n", n.(*ir.InstExpr).X)
+				info.subDictCalls = append(info.subDictCalls, n)
+			}
+		} else if n.Op() == ir.OXDOT && !n.(*ir.SelectorExpr).Implicit() &&
+			n.(*ir.SelectorExpr).Selection != nil &&
+			len(deref(n.(*ir.SelectorExpr).X.Type()).RParams()) > 0 {
+			if hasTParamTypes(deref(n.(*ir.SelectorExpr).X.Type()).RParams()) {
+				if n.(*ir.SelectorExpr).X.Op() == ir.OTYPE {
+					infoPrint("  Closure&subdictionary required at generic meth expr %v\n", n)
+				} else {
+					infoPrint("  Closure&subdictionary required at generic meth value %v\n", n)
+				}
+				info.subDictCalls = append(info.subDictCalls, n)
+			}
+		}
+		if n.Op() == ir.OCALL && n.(*ir.CallExpr).X.Op() == ir.OFUNCINST {
+			n.(*ir.CallExpr).X.(*ir.InstExpr).SetImplicit(true)
+			if hasTParamNodes(n.(*ir.CallExpr).X.(*ir.InstExpr).Targs) {
+				infoPrint("  Subdictionary at generic function/method call: %v - %v\n", n.(*ir.CallExpr).X.(*ir.InstExpr).X, n)
+				info.subDictCalls = append(info.subDictCalls, n)
+			}
+		}
+		if n.Op() == ir.OCALL && n.(*ir.CallExpr).X.Op() == ir.OXDOT &&
+			n.(*ir.CallExpr).X.(*ir.SelectorExpr).Selection != nil &&
+			len(deref(n.(*ir.CallExpr).X.(*ir.SelectorExpr).X.Type()).RParams()) > 0 {
+			n.(*ir.CallExpr).X.(*ir.SelectorExpr).SetImplicit(true)
+			if hasTParamTypes(deref(n.(*ir.CallExpr).X.(*ir.SelectorExpr).X.Type()).RParams()) {
+				infoPrint("  Subdictionary at generic method call: %v\n", n)
+				info.subDictCalls = append(info.subDictCalls, n)
+			}
+		}
+		if n.Op() == ir.OCALL && n.(*ir.CallExpr).X.Op() == ir.OXDOT &&
+			n.(*ir.CallExpr).X.(*ir.SelectorExpr).Selection != nil &&
+			deref(n.(*ir.CallExpr).X.(*ir.SelectorExpr).X.Type()).IsTypeParam() {
+			n.(*ir.CallExpr).X.(*ir.SelectorExpr).SetImplicit(true)
+			infoPrint("  Optional subdictionary at generic bound call: %v\n", n)
+			info.subDictCalls = append(info.subDictCalls, n)
+		}
+		if n.Op() == ir.OCONVIFACE && n.Type().IsInterface() &&
+			!n.Type().IsEmptyInterface() &&
+			n.(*ir.ConvExpr).X.Type().HasTParam() {
+			infoPrint("  Itab for interface conv: %v\n", n)
+			info.itabConvs = append(info.itabConvs, n)
+		}
+		if n.Op() == ir.OXDOT && n.(*ir.SelectorExpr).X.Type().IsTypeParam() {
+			infoPrint("  Itab for bound call: %v\n", n)
+			info.itabConvs = append(info.itabConvs, n)
+		}
+		if (n.Op() == ir.ODOTTYPE || n.Op() == ir.ODOTTYPE2) && !n.(*ir.TypeAssertExpr).Type().IsInterface() && !n.(*ir.TypeAssertExpr).X.Type().IsEmptyInterface() {
+			infoPrint("  Itab for dot type: %v\n", n)
+			info.itabConvs = append(info.itabConvs, n)
+		}
+		if n.Op() == ir.OCLOSURE {
+			// Visit the closure body and add all relevant entries to the
+			// dictionary of the outer function (closure will just use
+			// the dictionary of the outer function).
+			for _, n1 := range n.(*ir.ClosureExpr).Func.Body {
+				ir.Visit(n1, visitFunc)
+			}
+		}
+		if n.Op() == ir.OSWITCH && n.(*ir.SwitchStmt).Tag != nil && n.(*ir.SwitchStmt).Tag.Op() == ir.OTYPESW && !n.(*ir.SwitchStmt).Tag.(*ir.TypeSwitchGuard).X.Type().IsEmptyInterface() {
+			for _, cc := range n.(*ir.SwitchStmt).Cases {
+				for _, c := range cc.List {
+					if c.Op() == ir.OTYPE && c.Type().HasTParam() {
+						// Type switch from a non-empty interface - might need an itab.
+						infoPrint("  Itab for type switch: %v\n", c)
+						info.itabConvs = append(info.itabConvs, c)
+						if info.type2switchType == nil {
+							info.type2switchType = map[ir.Node]*types.Type{}
+						}
+						info.type2switchType[c] = n.(*ir.SwitchStmt).Tag.(*ir.TypeSwitchGuard).X.Type()
+					}
+				}
+			}
+		}
+		addType(&info, n, n.Type())
+	}
+
+	for _, stmt := range gf.Body {
+		ir.Visit(stmt, visitFunc)
+	}
+	if infoPrintMode {
+		for _, t := range info.derivedTypes {
+			fmt.Printf("  Derived type %v\n", t)
+		}
+		fmt.Printf(">>> Done Gfinfo\n")
+	}
+	g.gfInfoMap[gn.Sym()] = &info
+	return &info
+}
+
+// addType adds t to info.derivedTypes if it is parameterized type (which is not
+// just a simple type param) that is different from any existing type on
+// info.derivedTypes.
+func addType(info *gfInfo, n ir.Node, t *types.Type) {
+	if t == nil || !t.HasTParam() {
+		return
+	}
+	if t.IsTypeParam() && t.Underlying() == t {
+		return
+	}
+	if t.Kind() == types.TFUNC && n != nil &&
+		(t.Recv() != nil ||
+			n.Op() == ir.ONAME && n.Name().Class == ir.PFUNC) {
+		// Don't use the type of a named generic function or method,
+		// since that is parameterized by other typeparams.
+		// (They all come from arguments of a FUNCINST node.)
+		return
+	}
+	if doubleCheck && !parameterizedBy(t, info.tparams) {
+		base.Fatalf("adding type with invalid parameters %+v", t)
+	}
+	if t.Kind() == types.TSTRUCT && t.IsFuncArgStruct() {
+		// Multiple return values are not a relevant new type (?).
+		return
+	}
+	// Ignore a derived type we've already added.
+	for _, et := range info.derivedTypes {
+		if types.Identical(t, et) {
+			return
+		}
+	}
+	info.derivedTypes = append(info.derivedTypes, t)
+}
+
+// parameterizedBy returns true if t is parameterized by (at most) params.
+func parameterizedBy(t *types.Type, params []*types.Type) bool {
+	return parameterizedBy1(t, params, map[*types.Type]bool{})
+}
+func parameterizedBy1(t *types.Type, params []*types.Type, visited map[*types.Type]bool) bool {
+	if visited[t] {
+		return true
+	}
+	visited[t] = true
+
+	if t.Sym() != nil && len(t.RParams()) > 0 {
+		// This defined type is instantiated. Check the instantiating types.
+		for _, r := range t.RParams() {
+			if !parameterizedBy1(r, params, visited) {
+				return false
+			}
+		}
+		return true
+	}
+	switch t.Kind() {
+	case types.TTYPEPARAM:
+		// Check if t is one of the allowed parameters in scope.
+		for _, p := range params {
+			if p == t {
+				return true
+			}
+		}
+		// Couldn't find t in the list of allowed parameters.
+		return false
+
+	case types.TARRAY, types.TPTR, types.TSLICE, types.TCHAN:
+		return parameterizedBy1(t.Elem(), params, visited)
+
+	case types.TMAP:
+		return parameterizedBy1(t.Key(), params, visited) && parameterizedBy1(t.Elem(), params, visited)
+
+	case types.TFUNC:
+		return parameterizedBy1(t.TParams(), params, visited) && parameterizedBy1(t.Recvs(), params, visited) && parameterizedBy1(t.Params(), params, visited) && parameterizedBy1(t.Results(), params, visited)
+
+	case types.TSTRUCT:
+		for _, f := range t.Fields().Slice() {
+			if !parameterizedBy1(f.Type, params, visited) {
+				return false
+			}
+		}
+		return true
+
+	case types.TINTER:
+		for _, f := range t.Methods().Slice() {
+			if !parameterizedBy1(f.Type, params, visited) {
+				return false
+			}
+		}
+		return true
+
+	case types.TINT, types.TINT8, types.TINT16, types.TINT32, types.TINT64,
+		types.TUINT, types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64,
+		types.TUINTPTR, types.TBOOL, types.TSTRING, types.TFLOAT32, types.TFLOAT64, types.TCOMPLEX64, types.TCOMPLEX128:
+		return true
+
+	case types.TUNION:
+		for i := 0; i < t.NumTerms(); i++ {
+			tt, _ := t.Term(i)
+			if !parameterizedBy1(tt, params, visited) {
+				return false
+			}
+		}
+		return true
+
+	default:
+		base.Fatalf("bad type kind %+v", t)
+		return true
+	}
+}
+
+// startClosures starts creation of a closure that has the function type typ. It
+// creates all the formal params and results according to the type typ. On return,
+// the body and closure variables of the closure must still be filled in, and
+// ir.UseClosure() called.
+func startClosure(pos src.XPos, outer *ir.Func, typ *types.Type) (*ir.Func, []*types.Field, []*types.Field) {
+	// Make a new internal function.
+	fn := ir.NewClosureFunc(pos, outer != nil)
+	ir.NameClosure(fn.OClosure, outer)
+
+	// Build formal argument and return lists.
+	var formalParams []*types.Field  // arguments of closure
+	var formalResults []*types.Field // returns of closure
+	for i := 0; i < typ.NumParams(); i++ {
+		t := typ.Params().Field(i).Type
+		arg := ir.NewNameAt(pos, typecheck.LookupNum("a", i))
+		arg.Class = ir.PPARAM
+		typed(t, arg)
+		arg.Curfn = fn
+		fn.Dcl = append(fn.Dcl, arg)
+		f := types.NewField(pos, arg.Sym(), t)
+		f.Nname = arg
+		formalParams = append(formalParams, f)
+	}
+	for i := 0; i < typ.NumResults(); i++ {
+		t := typ.Results().Field(i).Type
+		result := ir.NewNameAt(pos, typecheck.LookupNum("r", i)) // TODO: names not needed?
+		result.Class = ir.PPARAMOUT
+		typed(t, result)
+		result.Curfn = fn
+		fn.Dcl = append(fn.Dcl, result)
+		f := types.NewField(pos, result.Sym(), t)
+		f.Nname = result
+		formalResults = append(formalResults, f)
+	}
+
+	// Build an internal function with the right signature.
+	closureType := types.NewSignature(typ.Pkg(), nil, nil, formalParams, formalResults)
+	typed(closureType, fn.Nname)
+	typed(typ, fn.OClosure)
+	fn.SetTypecheck(1)
+	return fn, formalParams, formalResults
+
+}
+
+// assertToBound returns a new node that converts a node rcvr with interface type to
+// the 'dst' interface type.  bound is the unsubstituted form of dst.
+func assertToBound(info *instInfo, dictVar *ir.Name, pos src.XPos, rcvr ir.Node, bound, dst *types.Type) ir.Node {
+	if bound.HasTParam() {
+		ix := findDictType(info, bound)
+		assert(ix >= 0)
+		rt := getDictionaryType(info, dictVar, pos, ix)
+		rcvr = ir.NewDynamicTypeAssertExpr(pos, ir.ODYNAMICDOTTYPE, rcvr, rt)
+		typed(dst, rcvr)
+	} else {
+		rcvr = ir.NewTypeAssertExpr(pos, rcvr, nil)
+		typed(bound, rcvr)
+	}
+	return rcvr
+}
+
+// buildClosure2 makes a closure to implement a method expression m (generic form x)
+// which has a shape type as receiver. If the receiver is exactly a shape (i.e. from
+// a typeparam), then the body of the closure converts m.X (the receiver) to the
+// interface bound type, and makes an interface call with the remaining arguments.
+//
+// The returned closure is fully substituted and has already had any needed
+// transformations done.
+func (g *irgen) buildClosure2(subst *subster, m, x ir.Node) ir.Node {
+	outer := subst.newf
+	info := subst.info
+	pos := m.Pos()
+	typ := m.Type() // type of the closure
+
+	fn, formalParams, formalResults := startClosure(pos, outer, typ)
+
+	// Capture dictionary calculated in the outer function
+	dictVar := ir.CaptureName(pos, fn, info.dictParam)
+	typed(types.Types[types.TUINTPTR], dictVar)
+
+	// Build arguments to call inside the closure.
+	var args []ir.Node
+	for i := 0; i < typ.NumParams(); i++ {
+		args = append(args, formalParams[i].Nname.(*ir.Name))
+	}
+
+	// Build call itself. This involves converting the first argument to the
+	// bound type (an interface) using the dictionary, and then making an
+	// interface call with the remaining arguments.
+	var innerCall ir.Node
+	rcvr := args[0]
+	args = args[1:]
+	assert(m.(*ir.SelectorExpr).X.Type().IsShape())
+	gsrc := x.(*ir.SelectorExpr).X.Type()
+	bound := gsrc.Bound()
+	dst := bound
+	if dst.HasTParam() {
+		dst = subst.ts.Typ(bound)
+	}
+	if m.(*ir.SelectorExpr).X.Type().IsInterface() {
+		// If type arg is an interface (unusual case), we do a type assert to
+		// the type bound.
+		rcvr = assertToBound(info, dictVar, pos, rcvr, bound, dst)
+	} else {
+		rcvr = convertUsingDictionary(info, dictVar, pos, rcvr, x, dst, gsrc)
+	}
+	dot := ir.NewSelectorExpr(pos, ir.ODOTINTER, rcvr, x.(*ir.SelectorExpr).Sel)
+	dot.Selection = typecheck.Lookdot1(dot, dot.Sel, dot.X.Type(), dot.X.Type().AllMethods(), 1)
+
+	// Do a type substitution on the generic bound, in case it is parameterized.
+	typed(subst.ts.Typ(x.(*ir.SelectorExpr).Selection.Type), dot)
+	innerCall = ir.NewCallExpr(pos, ir.OCALLINTER, dot, args)
+	t := m.Type()
+	if t.NumResults() == 0 {
+		innerCall.SetTypecheck(1)
+	} else if t.NumResults() == 1 {
+		typed(t.Results().Field(0).Type, innerCall)
+	} else {
+		typed(t.Results(), innerCall)
+	}
+	if len(formalResults) > 0 {
+		innerCall = ir.NewReturnStmt(pos, []ir.Node{innerCall})
+		innerCall.SetTypecheck(1)
+	}
+	fn.Body = []ir.Node{innerCall}
+
+	// We're all done with the captured dictionary
+	ir.FinishCaptureNames(pos, outer, fn)
+
+	// Do final checks on closure and return it.
+	return ir.UseClosure(fn.OClosure, g.target)
 }
diff --git a/src/cmd/compile/internal/noder/stmt.go b/src/cmd/compile/internal/noder/stmt.go
index 32a1483..1949f56 100644
--- a/src/cmd/compile/internal/noder/stmt.go
+++ b/src/cmd/compile/internal/noder/stmt.go
@@ -35,11 +35,7 @@
 	case *syntax.BlockStmt:
 		return ir.NewBlockStmt(g.pos(stmt), g.blockStmt(stmt))
 	case *syntax.ExprStmt:
-		x := g.expr(stmt.X)
-		if call, ok := x.(*ir.CallExpr); ok {
-			call.Use = ir.CallUseStmt
-		}
-		return x
+		return g.expr(stmt.X)
 	case *syntax.SendStmt:
 		n := ir.NewSendStmt(g.pos(stmt), g.expr(stmt.Chan), g.expr(stmt.Value))
 		if n.Chan.Type().HasTParam() || n.Value.Type().HasTParam() {
@@ -61,7 +57,10 @@
 			if stmt.Rhs == nil {
 				n = IncDec(g.pos(stmt), op, g.expr(stmt.Lhs))
 			} else {
-				n = ir.NewAssignOpStmt(g.pos(stmt), op, g.expr(stmt.Lhs), g.expr(stmt.Rhs))
+				// Eval rhs before lhs, for compatibility with noder1
+				rhs := g.expr(stmt.Rhs)
+				lhs := g.expr(stmt.Lhs)
+				n = ir.NewAssignOpStmt(g.pos(stmt), op, lhs, rhs)
 			}
 			if n.X.Typecheck() == 3 {
 				n.SetTypecheck(3)
@@ -72,8 +71,9 @@
 			return n
 		}
 
-		names, lhs := g.assignList(stmt.Lhs, stmt.Op == syntax.Def)
+		// Eval rhs before lhs, for compatibility with noder1
 		rhs := g.exprList(stmt.Rhs)
+		names, lhs := g.assignList(stmt.Lhs, stmt.Op == syntax.Def)
 
 		// We must delay transforming the assign statement if any of the
 		// lhs or rhs nodes are also delayed, since transformAssign needs
@@ -128,6 +128,12 @@
 			if e.Type().HasTParam() {
 				// Delay transforming the return statement if any of the
 				// return values have a type param.
+				if !ir.HasNamedResults(ir.CurFunc) {
+					transformArgs(n)
+					// But add CONVIFACE nodes where needed if
+					// any of the return values have interface type.
+					typecheckaste(ir.ORETURN, nil, false, ir.CurFunc.Type().Results(), n.Results, true)
+				}
 				n.SetTypecheck(3)
 				return n
 			}
@@ -266,6 +272,12 @@
 		key, value := unpackTwo(lhs)
 		n := ir.NewRangeStmt(g.pos(r), key, value, g.expr(r.X), g.blockStmt(stmt.Body))
 		n.Def = initDefn(n, names)
+		if key != nil {
+			transformCheckAssign(n, key)
+		}
+		if value != nil {
+			transformCheckAssign(n, value)
+		}
 		return n
 	}
 
diff --git a/src/cmd/compile/internal/noder/sync.go b/src/cmd/compile/internal/noder/sync.go
new file mode 100644
index 0000000..7af558f
--- /dev/null
+++ b/src/cmd/compile/internal/noder/sync.go
@@ -0,0 +1,187 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"fmt"
+	"strings"
+)
+
+// enableSync controls whether sync markers are written into unified
+// IR's export data format and also whether they're expected when
+// reading them back in. They're inessential to the correct
+// functioning of unified IR, but are helpful during development to
+// detect mistakes.
+//
+// When sync is enabled, writer stack frames will also be included in
+// the export data. Currently, a fixed number of frames are included,
+// controlled by -d=syncframes (default 0).
+const enableSync = true
+
+// fmtFrames formats a backtrace for reporting reader/writer desyncs.
+func fmtFrames(pcs ...uintptr) []string {
+	res := make([]string, 0, len(pcs))
+	walkFrames(pcs, func(file string, line int, name string, offset uintptr) {
+		// Trim package from function name. It's just redundant noise.
+		name = strings.TrimPrefix(name, "cmd/compile/internal/noder.")
+
+		res = append(res, fmt.Sprintf("%s:%v: %s +0x%v", file, line, name, offset))
+	})
+	return res
+}
+
+type frameVisitor func(file string, line int, name string, offset uintptr)
+
+// syncMarker is an enum type that represents markers that may be
+// written to export data to ensure the reader and writer stay
+// synchronized.
+type syncMarker int
+
+//go:generate stringer -type=syncMarker -trimprefix=sync
+
+// TODO(mdempsky): Cleanup unneeded sync markers.
+
+// TODO(mdempsky): Split these markers into public/stable markers, and
+// private ones. Also, trim unused ones.
+const (
+	_ syncMarker = iota
+	syncNode
+	syncBool
+	syncInt64
+	syncUint64
+	syncString
+	syncPos
+	syncPkg
+	syncSym
+	syncSelector
+	syncKind
+	syncType
+	syncTypePkg
+	syncSignature
+	syncParam
+	syncOp
+	syncObject
+	syncExpr
+	syncStmt
+	syncDecl
+	syncConstDecl
+	syncFuncDecl
+	syncTypeDecl
+	syncVarDecl
+	syncPragma
+	syncValue
+	syncEOF
+	syncMethod
+	syncFuncBody
+	syncUse
+	syncUseObj
+	syncObjectIdx
+	syncTypeIdx
+	syncBOF
+	syncEntry
+	syncOpenScope
+	syncCloseScope
+	syncGlobal
+	syncLocal
+	syncDefine
+	syncDefLocal
+	syncUseLocal
+	syncDefGlobal
+	syncUseGlobal
+	syncTypeParams
+	syncUseLabel
+	syncDefLabel
+	syncFuncLit
+	syncCommonFunc
+	syncBodyRef
+	syncLinksymExt
+	syncHack
+	syncSetlineno
+	syncName
+	syncImportDecl
+	syncDeclNames
+	syncDeclName
+	syncExprList
+	syncExprs
+	syncWrapname
+	syncTypeExpr
+	syncTypeExprOrNil
+	syncChanDir
+	syncParams
+	syncCloseAnotherScope
+	syncSum
+	syncUnOp
+	syncBinOp
+	syncStructType
+	syncInterfaceType
+	syncPackname
+	syncEmbedded
+	syncStmts
+	syncStmtsFall
+	syncStmtFall
+	syncBlockStmt
+	syncIfStmt
+	syncForStmt
+	syncSwitchStmt
+	syncRangeStmt
+	syncCaseClause
+	syncCommClause
+	syncSelectStmt
+	syncDecls
+	syncLabeledStmt
+	syncCompLit
+
+	sync1
+	sync2
+	sync3
+	sync4
+
+	syncN
+	syncDefImplicit
+	syncUseName
+	syncUseObjLocal
+	syncAddLocal
+	syncBothSignature
+	syncSetUnderlying
+	syncLinkname
+	syncStmt1
+	syncStmtsEnd
+	syncDeclare
+	syncTopDecls
+	syncTopConstDecl
+	syncTopFuncDecl
+	syncTopTypeDecl
+	syncTopVarDecl
+	syncObject1
+	syncAddBody
+	syncLabel
+	syncFuncExt
+	syncMethExt
+	syncOptLabel
+	syncScalar
+	syncStmtDecls
+	syncDeclLocal
+	syncObjLocal
+	syncObjLocal1
+	syncDeclareLocal
+	syncPublic
+	syncPrivate
+	syncRelocs
+	syncReloc
+	syncUseReloc
+	syncVarExt
+	syncPkgDef
+	syncTypeExt
+	syncVal
+	syncCodeObj
+	syncPosBase
+	syncLocalIdent
+	syncTypeParamNames
+	syncTypeParamBounds
+	syncImplicitTypes
+	syncObjectName
+)
diff --git a/src/cmd/compile/internal/noder/syncmarker_string.go b/src/cmd/compile/internal/noder/syncmarker_string.go
new file mode 100644
index 0000000..14747b7c
--- /dev/null
+++ b/src/cmd/compile/internal/noder/syncmarker_string.go
@@ -0,0 +1,155 @@
+// Code generated by "stringer -type=syncMarker -trimprefix=sync"; DO NOT EDIT.
+
+package noder
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[syncNode-1]
+	_ = x[syncBool-2]
+	_ = x[syncInt64-3]
+	_ = x[syncUint64-4]
+	_ = x[syncString-5]
+	_ = x[syncPos-6]
+	_ = x[syncPkg-7]
+	_ = x[syncSym-8]
+	_ = x[syncSelector-9]
+	_ = x[syncKind-10]
+	_ = x[syncType-11]
+	_ = x[syncTypePkg-12]
+	_ = x[syncSignature-13]
+	_ = x[syncParam-14]
+	_ = x[syncOp-15]
+	_ = x[syncObject-16]
+	_ = x[syncExpr-17]
+	_ = x[syncStmt-18]
+	_ = x[syncDecl-19]
+	_ = x[syncConstDecl-20]
+	_ = x[syncFuncDecl-21]
+	_ = x[syncTypeDecl-22]
+	_ = x[syncVarDecl-23]
+	_ = x[syncPragma-24]
+	_ = x[syncValue-25]
+	_ = x[syncEOF-26]
+	_ = x[syncMethod-27]
+	_ = x[syncFuncBody-28]
+	_ = x[syncUse-29]
+	_ = x[syncUseObj-30]
+	_ = x[syncObjectIdx-31]
+	_ = x[syncTypeIdx-32]
+	_ = x[syncBOF-33]
+	_ = x[syncEntry-34]
+	_ = x[syncOpenScope-35]
+	_ = x[syncCloseScope-36]
+	_ = x[syncGlobal-37]
+	_ = x[syncLocal-38]
+	_ = x[syncDefine-39]
+	_ = x[syncDefLocal-40]
+	_ = x[syncUseLocal-41]
+	_ = x[syncDefGlobal-42]
+	_ = x[syncUseGlobal-43]
+	_ = x[syncTypeParams-44]
+	_ = x[syncUseLabel-45]
+	_ = x[syncDefLabel-46]
+	_ = x[syncFuncLit-47]
+	_ = x[syncCommonFunc-48]
+	_ = x[syncBodyRef-49]
+	_ = x[syncLinksymExt-50]
+	_ = x[syncHack-51]
+	_ = x[syncSetlineno-52]
+	_ = x[syncName-53]
+	_ = x[syncImportDecl-54]
+	_ = x[syncDeclNames-55]
+	_ = x[syncDeclName-56]
+	_ = x[syncExprList-57]
+	_ = x[syncExprs-58]
+	_ = x[syncWrapname-59]
+	_ = x[syncTypeExpr-60]
+	_ = x[syncTypeExprOrNil-61]
+	_ = x[syncChanDir-62]
+	_ = x[syncParams-63]
+	_ = x[syncCloseAnotherScope-64]
+	_ = x[syncSum-65]
+	_ = x[syncUnOp-66]
+	_ = x[syncBinOp-67]
+	_ = x[syncStructType-68]
+	_ = x[syncInterfaceType-69]
+	_ = x[syncPackname-70]
+	_ = x[syncEmbedded-71]
+	_ = x[syncStmts-72]
+	_ = x[syncStmtsFall-73]
+	_ = x[syncStmtFall-74]
+	_ = x[syncBlockStmt-75]
+	_ = x[syncIfStmt-76]
+	_ = x[syncForStmt-77]
+	_ = x[syncSwitchStmt-78]
+	_ = x[syncRangeStmt-79]
+	_ = x[syncCaseClause-80]
+	_ = x[syncCommClause-81]
+	_ = x[syncSelectStmt-82]
+	_ = x[syncDecls-83]
+	_ = x[syncLabeledStmt-84]
+	_ = x[syncCompLit-85]
+	_ = x[sync1-86]
+	_ = x[sync2-87]
+	_ = x[sync3-88]
+	_ = x[sync4-89]
+	_ = x[syncN-90]
+	_ = x[syncDefImplicit-91]
+	_ = x[syncUseName-92]
+	_ = x[syncUseObjLocal-93]
+	_ = x[syncAddLocal-94]
+	_ = x[syncBothSignature-95]
+	_ = x[syncSetUnderlying-96]
+	_ = x[syncLinkname-97]
+	_ = x[syncStmt1-98]
+	_ = x[syncStmtsEnd-99]
+	_ = x[syncDeclare-100]
+	_ = x[syncTopDecls-101]
+	_ = x[syncTopConstDecl-102]
+	_ = x[syncTopFuncDecl-103]
+	_ = x[syncTopTypeDecl-104]
+	_ = x[syncTopVarDecl-105]
+	_ = x[syncObject1-106]
+	_ = x[syncAddBody-107]
+	_ = x[syncLabel-108]
+	_ = x[syncFuncExt-109]
+	_ = x[syncMethExt-110]
+	_ = x[syncOptLabel-111]
+	_ = x[syncScalar-112]
+	_ = x[syncStmtDecls-113]
+	_ = x[syncDeclLocal-114]
+	_ = x[syncObjLocal-115]
+	_ = x[syncObjLocal1-116]
+	_ = x[syncDeclareLocal-117]
+	_ = x[syncPublic-118]
+	_ = x[syncPrivate-119]
+	_ = x[syncRelocs-120]
+	_ = x[syncReloc-121]
+	_ = x[syncUseReloc-122]
+	_ = x[syncVarExt-123]
+	_ = x[syncPkgDef-124]
+	_ = x[syncTypeExt-125]
+	_ = x[syncVal-126]
+	_ = x[syncCodeObj-127]
+	_ = x[syncPosBase-128]
+	_ = x[syncLocalIdent-129]
+	_ = x[syncTypeParamNames-130]
+	_ = x[syncTypeParamBounds-131]
+	_ = x[syncImplicitTypes-132]
+}
+
+const _syncMarker_name = "NodeBoolInt64Uint64StringPosPkgSymSelectorKindTypeTypePkgSignatureParamOpObjectExprStmtDeclConstDeclFuncDeclTypeDeclVarDeclPragmaValueEOFMethodFuncBodyUseUseObjObjectIdxTypeIdxBOFEntryOpenScopeCloseScopeGlobalLocalDefineDefLocalUseLocalDefGlobalUseGlobalTypeParamsUseLabelDefLabelFuncLitCommonFuncBodyRefLinksymExtHackSetlinenoNameImportDeclDeclNamesDeclNameExprListExprsWrapnameTypeExprTypeExprOrNilChanDirParamsCloseAnotherScopeSumUnOpBinOpStructTypeInterfaceTypePacknameEmbeddedStmtsStmtsFallStmtFallBlockStmtIfStmtForStmtSwitchStmtRangeStmtCaseClauseCommClauseSelectStmtDeclsLabeledStmtCompLit1234NDefImplicitUseNameUseObjLocalAddLocalBothSignatureSetUnderlyingLinknameStmt1StmtsEndDeclareTopDeclsTopConstDeclTopFuncDeclTopTypeDeclTopVarDeclObject1AddBodyLabelFuncExtMethExtOptLabelScalarStmtDeclsDeclLocalObjLocalObjLocal1DeclareLocalPublicPrivateRelocsRelocUseRelocVarExtPkgDefTypeExtValCodeObjPosBaseLocalIdentTypeParamNamesTypeParamBoundsImplicitTypes"
+
+var _syncMarker_index = [...]uint16{0, 4, 8, 13, 19, 25, 28, 31, 34, 42, 46, 50, 57, 66, 71, 73, 79, 83, 87, 91, 100, 108, 116, 123, 129, 134, 137, 143, 151, 154, 160, 169, 176, 179, 184, 193, 203, 209, 214, 220, 228, 236, 245, 254, 264, 272, 280, 287, 297, 304, 314, 318, 327, 331, 341, 350, 358, 366, 371, 379, 387, 400, 407, 413, 430, 433, 437, 442, 452, 465, 473, 481, 486, 495, 503, 512, 518, 525, 535, 544, 554, 564, 574, 579, 590, 597, 598, 599, 600, 601, 602, 613, 620, 631, 639, 652, 665, 673, 678, 686, 693, 701, 713, 724, 735, 745, 752, 759, 764, 771, 778, 786, 792, 801, 810, 818, 827, 839, 845, 852, 858, 863, 871, 877, 883, 890, 893, 900, 907, 917, 931, 946, 959}
+
+func (i syncMarker) String() string {
+	i -= 1
+	if i < 0 || i >= syncMarker(len(_syncMarker_index)-1) {
+		return "syncMarker(" + strconv.FormatInt(int64(i+1), 10) + ")"
+	}
+	return _syncMarker_name[_syncMarker_index[i]:_syncMarker_index[i+1]]
+}
diff --git a/src/cmd/compile/internal/noder/transform.go b/src/cmd/compile/internal/noder/transform.go
index 2859089..e1eeb8e 100644
--- a/src/cmd/compile/internal/noder/transform.go
+++ b/src/cmd/compile/internal/noder/transform.go
@@ -85,7 +85,15 @@
 // etc.  Corresponds to typecheck.tcConv.
 func transformConv(n *ir.ConvExpr) ir.Node {
 	t := n.X.Type()
-	op, _ := typecheck.Convertop(n.X.Op() == ir.OLITERAL, t, n.Type())
+	op, why := typecheck.Convertop(n.X.Op() == ir.OLITERAL, t, n.Type())
+	if op == ir.OXXX {
+		// types2 currently ignores pragmas, so a 'notinheap' mismatch is the
+		// one type-related error that it does not catch. This error will be
+		// caught here by Convertop (see two checks near beginning of
+		// Convertop) and reported at the end of noding.
+		base.ErrorfAt(n.Pos(), "cannot convert %L to type %v%s", n.X, n.Type(), why)
+		return n
+	}
 	n.SetOp(op)
 	switch n.Op() {
 	case ir.OCONVNOP:
@@ -122,7 +130,8 @@
 }
 
 // transformCall transforms a normal function/method call. Corresponds to last half
-// (non-conversion, non-builtin part) of typecheck.tcCall.
+// (non-conversion, non-builtin part) of typecheck.tcCall. This code should work even
+// in the case of OCALL/OFUNCINST.
 func transformCall(n *ir.CallExpr) {
 	// n.Type() can be nil for calls with no return value
 	assert(n.Typecheck() == 1)
@@ -148,10 +157,11 @@
 		n.SetOp(ir.OCALLFUNC)
 	}
 
-	typecheckaste(ir.OCALL, n.X, n.IsDDD, t.Params(), n.Args)
+	typecheckaste(ir.OCALL, n.X, n.IsDDD, t.Params(), n.Args, false)
+	if l.Op() == ir.ODOTMETH && len(deref(n.X.Type().Recv().Type).RParams()) == 0 {
+		typecheck.FixMethodCall(n)
+	}
 	if t.NumResults() == 1 {
-		n.SetType(l.Type().Results().Field(0).Type)
-
 		if n.Op() == ir.OCALLFUNC && n.X.Op() == ir.ONAME {
 			if sym := n.X.(*ir.Name).Sym(); types.IsRuntimePkg(sym.Pkg) && sym.Name == "getg" {
 				// Emit code for runtime.getg() directly instead of calling function.
@@ -185,7 +195,7 @@
 			aop, _ := typecheck.Assignop(lt, rt)
 			if aop != ir.OXXX {
 				types.CalcSize(lt)
-				if rt.IsInterface() == lt.IsInterface() || lt.Width >= 1<<16 {
+				if lt.HasTParam() || rt.IsInterface() == lt.IsInterface() || lt.Width >= 1<<16 {
 					l = ir.NewConvExpr(base.Pos, aop, rt, l)
 					l.SetTypecheck(1)
 				}
@@ -198,7 +208,7 @@
 			aop, _ := typecheck.Assignop(rt, lt)
 			if aop != ir.OXXX {
 				types.CalcSize(rt)
-				if rt.IsInterface() == lt.IsInterface() || rt.Width >= 1<<16 {
+				if rt.HasTParam() || rt.IsInterface() == lt.IsInterface() || rt.Width >= 1<<16 {
 					r = ir.NewConvExpr(base.Pos, aop, lt, r)
 					r.SetTypecheck(1)
 				}
@@ -303,6 +313,10 @@
 			r := r.(*ir.TypeAssertExpr)
 			stmt.SetOp(ir.OAS2DOTTYPE)
 			r.SetOp(ir.ODOTTYPE2)
+		case ir.ODYNAMICDOTTYPE:
+			r := r.(*ir.DynamicTypeAssertExpr)
+			stmt.SetOp(ir.OAS2DOTTYPE)
+			r.SetOp(ir.ODYNAMICDOTTYPE2)
 		default:
 			break assignOK
 		}
@@ -323,11 +337,22 @@
 		stmt := stmt.(*ir.AssignListStmt)
 		stmt.SetOp(ir.OAS2FUNC)
 		r := rhs[0].(*ir.CallExpr)
-		r.Use = ir.CallUseList
 		rtyp := r.Type()
 
+		mismatched := false
+		failed := false
 		for i := range lhs {
-			checkLHS(i, rtyp.Field(i).Type)
+			result := rtyp.Field(i).Type
+			checkLHS(i, result)
+
+			if lhs[i].Type() == nil || result == nil {
+				failed = true
+			} else if lhs[i] != ir.BlankNode && !types.Identical(lhs[i].Type(), result) {
+				mismatched = true
+			}
+		}
+		if mismatched && !failed {
+			typecheck.RewriteMultiValueCall(stmt, r)
 		}
 		return
 	}
@@ -340,12 +365,12 @@
 	}
 }
 
-// Corresponds to typecheck.typecheckargs.
+// Corresponds to typecheck.typecheckargs.  Really just deals with multi-value calls.
 func transformArgs(n ir.InitNode) {
 	var list []ir.Node
 	switch n := n.(type) {
 	default:
-		base.Fatalf("typecheckargs %+v", n.Op())
+		base.Fatalf("transformArgs %+v", n.Op())
 	case *ir.CallExpr:
 		list = n.Args
 		if n.IsDDD {
@@ -363,46 +388,13 @@
 		return
 	}
 
-	// Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
-
 	// Save n as n.Orig for fmt.go.
 	if ir.Orig(n) == n {
 		n.(ir.OrigNode).SetOrig(ir.SepCopy(n))
 	}
 
-	as := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
-	as.Rhs.Append(list...)
-
-	// If we're outside of function context, then this call will
-	// be executed during the generated init function. However,
-	// init.go hasn't yet created it. Instead, associate the
-	// temporary variables with  InitTodoFunc for now, and init.go
-	// will reassociate them later when it's appropriate.
-	static := ir.CurFunc == nil
-	if static {
-		ir.CurFunc = typecheck.InitTodoFunc
-	}
-	list = nil
-	for _, f := range t.FieldSlice() {
-		t := typecheck.Temp(f.Type)
-		as.PtrInit().Append(ir.NewDecl(base.Pos, ir.ODCL, t))
-		as.Lhs.Append(t)
-		list = append(list, t)
-	}
-	if static {
-		ir.CurFunc = nil
-	}
-
-	switch n := n.(type) {
-	case *ir.CallExpr:
-		n.Args = list
-	case *ir.ReturnStmt:
-		n.Results = list
-	}
-
-	transformAssign(as, as.Lhs, as.Rhs)
-	as.SetTypecheck(1)
-	n.PtrInit().Append(as)
+	// Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
+	typecheck.RewriteMultiValueCall(n, list[0])
 }
 
 // assignconvfn converts node n for assignment to type t. Corresponds to
@@ -416,7 +408,10 @@
 		return n
 	}
 
-	op, _ := typecheck.Assignop(n.Type(), t)
+	op, why := typecheck.Assignop(n.Type(), t)
+	if op == ir.OXXX {
+		base.Fatalf("found illegal assignment %+v -> %+v; %s", n.Type(), t, why)
+	}
 
 	r := ir.NewConvExpr(base.Pos, op, t, n)
 	r.SetTypecheck(1)
@@ -424,8 +419,11 @@
 	return r
 }
 
-// Corresponds to typecheck.typecheckaste.
-func typecheckaste(op ir.Op, call ir.Node, isddd bool, tstruct *types.Type, nl ir.Nodes) {
+// Corresponds to typecheck.typecheckaste, but we add an extra flag convifaceOnly
+// only. If convifaceOnly is true, we only do interface conversion. We use this to do
+// early insertion of CONVIFACE nodes during noder2, when the function or args may
+// have typeparams.
+func typecheckaste(op ir.Op, call ir.Node, isddd bool, tstruct *types.Type, nl ir.Nodes, convifaceOnly bool) {
 	var t *types.Type
 	var i int
 
@@ -444,7 +442,7 @@
 			if isddd {
 				n = nl[i]
 				ir.SetPos(n)
-				if n.Type() != nil {
+				if n.Type() != nil && (!convifaceOnly || t.IsInterface()) {
 					nl[i] = assignconvfn(n, t)
 				}
 				return
@@ -454,7 +452,7 @@
 			for ; i < len(nl); i++ {
 				n = nl[i]
 				ir.SetPos(n)
-				if n.Type() != nil {
+				if n.Type() != nil && (!convifaceOnly || t.IsInterface()) {
 					nl[i] = assignconvfn(n, t.Elem())
 				}
 			}
@@ -463,7 +461,7 @@
 
 		n = nl[i]
 		ir.SetPos(n)
-		if n.Type() != nil {
+		if n.Type() != nil && (!convifaceOnly || t.IsInterface()) {
 			nl[i] = assignconvfn(n, t)
 		}
 		i++
@@ -485,7 +483,7 @@
 		return
 	}
 
-	typecheckaste(ir.ORETURN, nil, false, ir.CurFunc.Type().Results(), nl)
+	typecheckaste(ir.ORETURN, nil, false, ir.CurFunc.Type().Results(), nl, false)
 }
 
 // transformSelect transforms a select node, creating an assignment list as needed
@@ -537,13 +535,31 @@
 }
 
 // transformDot transforms an OXDOT (or ODOT) or ODOT, ODOTPTR, ODOTMETH,
-// ODOTINTER, or OCALLPART, as appropriate. It adds in extra nodes as needed to
+// ODOTINTER, or OMETHVALUE, as appropriate. It adds in extra nodes as needed to
 // access embedded fields. Corresponds to typecheck.tcDot.
 func transformDot(n *ir.SelectorExpr, isCall bool) ir.Node {
 	assert(n.Type() != nil && n.Typecheck() == 1)
 	if n.Op() == ir.OXDOT {
 		n = typecheck.AddImplicitDots(n)
 		n.SetOp(ir.ODOT)
+
+		// Set the Selection field and typecheck flag for any new ODOT nodes
+		// added by AddImplicitDots(), and also transform to ODOTPTR if
+		// needed. Equivalent to 'n.X = typecheck(n.X, ctxExpr|ctxType)' in
+		// tcDot.
+		for n1 := n; n1.X.Op() == ir.ODOT; {
+			n1 = n1.X.(*ir.SelectorExpr)
+			if !n1.Implicit() {
+				break
+			}
+			t1 := n1.X.Type()
+			if t1.IsPtr() && !t1.Elem().IsInterface() {
+				t1 = t1.Elem()
+				n1.SetOp(ir.ODOTPTR)
+			}
+			typecheck.Lookdot(n1, t1, 0)
+			n1.SetTypecheck(1)
+		}
 	}
 
 	t := n.X.Type()
@@ -561,8 +577,13 @@
 	assert(f != nil)
 
 	if (n.Op() == ir.ODOTINTER || n.Op() == ir.ODOTMETH) && !isCall {
-		n.SetOp(ir.OCALLPART)
-		n.SetType(typecheck.MethodValueWrapper(n).Type())
+		n.SetOp(ir.OMETHVALUE)
+		if len(n.X.Type().RParams()) > 0 || n.X.Type().IsPtr() && len(n.X.Type().Elem().RParams()) > 0 {
+			// TODO: MethodValueWrapper needed for generics?
+			// Or did we successfully desugar all that at stencil time?
+			return n
+		}
+		n.SetType(typecheck.NewMethodType(n.Type(), nil))
 	}
 	return n
 }
@@ -594,7 +615,11 @@
 
 	s := n.Sel
 	m := typecheck.Lookdot1(n, s, t, ms, 0)
-	assert(m != nil)
+	if !t.HasShape() {
+		// It's OK to not find the method if t is instantiated by shape types,
+		// because we will use the methods on the generic type anyway.
+		assert(m != nil)
+	}
 
 	n.SetOp(ir.OMETHEXPR)
 	n.Selection = m
@@ -911,9 +936,7 @@
 
 				f := t.Field(i)
 				n1 = assignconvfn(n1, f.Type)
-				sk := ir.NewStructKeyExpr(base.Pos, f.Sym, n1)
-				sk.Offset = f.Offset
-				ls[i] = sk
+				ls[i] = ir.NewStructKeyExpr(base.Pos, f, n1)
 			}
 			assert(len(ls) >= t.NumFields())
 		} else {
@@ -922,33 +945,26 @@
 			for i, l := range ls {
 				ir.SetPos(l)
 
-				if l.Op() == ir.OKEY {
-					kv := l.(*ir.KeyExpr)
-					key := kv.Key
+				kv := l.(*ir.KeyExpr)
+				key := kv.Key
 
-					// Sym might have resolved to name in other top-level
-					// package, because of import dot. Redirect to correct sym
-					// before we do the lookup.
-					s := key.Sym()
-					if id, ok := key.(*ir.Ident); ok && typecheck.DotImportRefs[id] != nil {
-						s = typecheck.Lookup(s.Name)
-					}
-
-					// An OXDOT uses the Sym field to hold
-					// the field to the right of the dot,
-					// so s will be non-nil, but an OXDOT
-					// is never a valid struct literal key.
-					assert(!(s == nil || s.Pkg != types.LocalPkg || key.Op() == ir.OXDOT || s.IsBlank()))
-
-					l = ir.NewStructKeyExpr(l.Pos(), s, kv.Value)
-					ls[i] = l
+				// Sym might have resolved to name in other top-level
+				// package, because of import dot. Redirect to correct sym
+				// before we do the lookup.
+				s := key.Sym()
+				if id, ok := key.(*ir.Ident); ok && typecheck.DotImportRefs[id] != nil {
+					s = typecheck.Lookup(s.Name)
 				}
 
-				assert(l.Op() == ir.OSTRUCTKEY)
-				l := l.(*ir.StructKeyExpr)
+				// An OXDOT uses the Sym field to hold
+				// the field to the right of the dot,
+				// so s will be non-nil, but an OXDOT
+				// is never a valid struct literal key.
+				assert(!(s == nil || s.Pkg != types.LocalPkg || key.Op() == ir.OXDOT || s.IsBlank()))
 
-				f := typecheck.Lookdot1(nil, l.Field, t, t.Fields(), 0)
-				l.Offset = f.Offset
+				f := typecheck.Lookdot1(nil, s, t, t.Fields(), 0)
+				l := ir.NewStructKeyExpr(l.Pos(), f, kv.Value)
+				ls[i] = l
 
 				l.Value = assignconvfn(l.Value, f.Type)
 			}
diff --git a/src/cmd/compile/internal/noder/types.go b/src/cmd/compile/internal/noder/types.go
index 8680559..8d596e5 100644
--- a/src/cmd/compile/internal/noder/types.go
+++ b/src/cmd/compile/internal/noder/types.go
@@ -39,6 +39,11 @@
 	// recursive types have been fully constructed before we call CheckSize.
 	if res != nil && !res.IsUntyped() && !res.IsFuncArgStruct() && !res.HasTParam() {
 		types.CheckSize(res)
+		if res.IsPtr() {
+			// Pointers always have their size set, even though their element
+			// may not have its size set.
+			types.CheckSize(res.Elem())
+		}
 	}
 	return res
 }
@@ -68,8 +73,10 @@
 		if i > 0 {
 			b.WriteByte(',')
 		}
+		// Include package names for all types, including typeparams, to
+		// make sure type arguments are uniquely specified.
 		tname := types2.TypeString(targ,
-			func(*types2.Package) string { return "" })
+			func(pkg *types2.Package) string { return pkg.Name() })
 		if strings.Index(tname, ", ") >= 0 {
 			// types2.TypeString puts spaces after a comma in a type
 			// list, but we don't want spaces in our actual type names
@@ -89,50 +96,49 @@
 	case *types2.Basic:
 		return g.basic(typ)
 	case *types2.Named:
-		if typ.TParams() != nil {
+		// If tparams is set, but targs is not, typ is a base generic
+		// type. typ is appearing as part of the source type of an alias,
+		// since that is the only use of a generic type that doesn't
+		// involve instantiation. We just translate the named type in the
+		// normal way below using g.obj().
+		if typ.TParams() != nil && typ.TArgs() != nil {
 			// typ is an instantiation of a defined (named) generic type.
 			// This instantiation should also be a defined (named) type.
 			// types2 gives us the substituted type in t.Underlying()
 			// The substituted type may or may not still have type
 			// params. We might, for example, be substituting one type
 			// param for another type param.
-
-			if typ.TArgs() == nil {
-				base.Fatalf("In typ0, Targs should be set if TParams is set")
-			}
-
-			// When converted to types.Type, typ must have a name,
-			// based on the names of the type arguments. We need a
-			// name to deal with recursive generic types (and it also
-			// looks better when printing types).
+			//
+			// When converted to types.Type, typ has a unique name,
+			// based on the names of the type arguments.
 			instName := instTypeName2(typ.Obj().Name(), typ.TArgs())
 			s := g.pkg(typ.Obj().Pkg()).Lookup(instName)
 			if s.Def != nil {
-				// We have already encountered this instantiation,
-				// so use the type we previously created, since there
+				// We have already encountered this instantiation.
+				// Use the type we previously created, since there
 				// must be exactly one instance of a defined type.
 				return s.Def.Type()
 			}
 
 			// Create a forwarding type first and put it in the g.typs
-			// map, in order to deal with recursive generic types.
-			// Fully set up the extra ntyp information (Def, RParams,
-			// which may set HasTParam) before translating the
-			// underlying type itself, so we handle recursion
-			// correctly, including via method signatures.
-			ntyp := newIncompleteNamedType(g.pos(typ.Obj().Pos()), s)
+			// map, in order to deal with recursive generic types
+			// (including via method signatures).. Set up the extra
+			// ntyp information (Def, RParams, which may set
+			// HasTParam) before translating the underlying type
+			// itself, so we handle recursion correctly.
+			ntyp := typecheck.NewIncompleteNamedType(g.pos(typ.Obj().Pos()), s)
 			g.typs[typ] = ntyp
 
 			// If ntyp still has type params, then we must be
 			// referencing something like 'value[T2]', as when
-			// specifying the generic receiver of a method,
-			// where value was defined as "type value[T any]
-			// ...". Save the type args, which will now be the
-			// new type  of the current type.
+			// specifying the generic receiver of a method, where
+			// value was defined as "type value[T any] ...". Save the
+			// type args, which will now be the new typeparams of the
+			// current type.
 			//
 			// If ntyp does not have type params, we are saving the
-			// concrete types used to instantiate this type. We'll use
-			// these when instantiating the methods of the
+			// non-generic types used to instantiate this type. We'll
+			// use these when instantiating the methods of the
 			// instantiated type.
 			rparams := make([]*types.Type, len(typ.TArgs()))
 			for i, targ := range typ.TArgs() {
@@ -143,6 +149,8 @@
 
 			ntyp.SetUnderlying(g.typ1(typ.Underlying()))
 			g.fillinMethods(typ, ntyp)
+			// Save the symbol for the base generic type.
+			ntyp.OrigSym = g.pkg(typ.Obj().Pkg()).Lookup(typ.Obj().Name())
 			return ntyp
 		}
 		obj := g.obj(typ.Obj())
@@ -183,12 +191,9 @@
 		for i := range embeddeds {
 			// TODO(mdempsky): Get embedding position.
 			e := typ.EmbeddedType(i)
-			if t := types2.AsInterface(e); t != nil && t.IsComparable() {
-				// Ignore predefined type 'comparable', since it
-				// doesn't resolve and it doesn't have any
-				// relevant methods.
-				continue
-			}
+
+			// With Go 1.18, an embedded element can be any type, not
+			// just an interface.
 			embeddeds[j] = types.NewField(src.NoXPos, nil, g.typ1(e))
 			j++
 		}
@@ -204,20 +209,39 @@
 		return types.NewInterface(g.tpkg(typ), append(embeddeds, methods...))
 
 	case *types2.TypeParam:
-		tp := types.NewTypeParam(g.tpkg(typ))
 		// Save the name of the type parameter in the sym of the type.
 		// Include the types2 subscript in the sym name
-		sym := g.pkg(typ.Obj().Pkg()).Lookup(types2.TypeString(typ, func(*types2.Package) string { return "" }))
-		tp.SetSym(sym)
+		pkg := g.tpkg(typ)
+		sym := pkg.Lookup(types2.TypeString(typ, func(*types2.Package) string { return "" }))
+		if sym.Def != nil {
+			// Make sure we use the same type param type for the same
+			// name, whether it is created during types1-import or
+			// this types2-to-types1 translation.
+			return sym.Def.Type()
+		}
+		tp := types.NewTypeParam(sym, typ.Index())
+		nname := ir.NewDeclNameAt(g.pos(typ.Obj().Pos()), ir.OTYPE, sym)
+		sym.Def = nname
+		nname.SetType(tp)
+		tp.SetNod(nname)
 		// Set g.typs[typ] in case the bound methods reference typ.
 		g.typs[typ] = tp
 
-		// TODO(danscales): we don't currently need to use the bounds
-		// anywhere, so eventually we can probably remove.
-		bound := g.typ1(typ.Bound())
-		*tp.Methods() = *bound.Methods()
+		bound := g.typ1(typ.Constraint())
+		tp.SetBound(bound)
 		return tp
 
+	case *types2.Union:
+		nt := typ.Len()
+		tlist := make([]*types.Type, nt)
+		tildes := make([]bool, nt)
+		for i := range tlist {
+			t := typ.Term(i)
+			tlist[i] = g.typ1(t.Type())
+			tildes[i] = t.Tilde()
+		}
+		return types.NewUnion(tlist, tildes)
+
 	case *types2.Tuple:
 		// Tuples are used for the type of a function call (i.e. the
 		// return value of the function).
@@ -243,19 +267,23 @@
 // and for actually generating the methods for instantiated types.
 func (g *irgen) fillinMethods(typ *types2.Named, ntyp *types.Type) {
 	if typ.NumMethods() != 0 {
-		targs := make([]ir.Node, len(typ.TArgs()))
+		targs := make([]*types.Type, len(typ.TArgs()))
 		for i, targ := range typ.TArgs() {
-			targs[i] = ir.TypeNode(g.typ1(targ))
+			targs[i] = g.typ1(targ)
 		}
 
 		methods := make([]*types.Field, typ.NumMethods())
 		for i := range methods {
 			m := typ.Method(i)
-			meth := g.obj(m)
-			recvType := types2.AsSignature(m.Type()).Recv().Type()
-			ptr := types2.AsPointer(recvType)
-			if ptr != nil {
-				recvType = ptr.Elem()
+			recvType := deref2(types2.AsSignature(m.Type()).Recv().Type())
+			var meth *ir.Name
+			if m.Pkg() != g.self {
+				// Imported methods cannot be loaded by name (what
+				// g.obj() does) - they must be loaded via their
+				// type.
+				meth = g.obj(recvType.(*types2.Named).Obj()).Type().Methods().Index(i).Nname.(*ir.Name)
+			} else {
+				meth = g.obj(m)
 			}
 			if recvType != types2.Type(typ) {
 				// Unfortunately, meth is the type of the method of the
@@ -276,18 +304,21 @@
 				} else {
 					meth2 = ir.NewNameAt(meth.Pos(), newsym)
 					rparams := types2.AsSignature(m.Type()).RParams()
-					tparams := make([]*types.Field, len(rparams))
-					for i, rparam := range rparams {
-						tparams[i] = types.NewField(src.NoXPos, nil, g.typ1(rparam.Type()))
+					tparams := make([]*types.Type, rparams.Len())
+					for i := range tparams {
+						tparams[i] = g.typ1(rparams.At(i).Type())
 					}
 					assert(len(tparams) == len(targs))
-					subst := &subster{
-						g:       g,
-						tparams: tparams,
-						targs:   targs,
+					ts := typecheck.Tsubster{
+						Tparams: tparams,
+						Targs:   targs,
 					}
 					// Do the substitution of the type
-					meth2.SetType(subst.typ(meth.Type()))
+					meth2.SetType(ts.Typ(meth.Type()))
+					// Add any new fully instantiated types
+					// seen during the substitution to
+					// g.instTypeList.
+					g.instTypeList = append(g.instTypeList, ts.InstTypeList...)
 					newsym.Def = meth2
 				}
 				meth = meth2
@@ -296,7 +327,7 @@
 			methods[i].Nname = meth
 		}
 		ntyp.Methods().Set(methods)
-		if !ntyp.HasTParam() {
+		if !ntyp.HasTParam() && !ntyp.HasShape() {
 			// Generate all the methods for a new fully-instantiated type.
 			g.instTypeList = append(g.instTypeList, ntyp)
 		}
@@ -305,9 +336,9 @@
 
 func (g *irgen) signature(recv *types.Field, sig *types2.Signature) *types.Type {
 	tparams2 := sig.TParams()
-	tparams := make([]*types.Field, len(tparams2))
+	tparams := make([]*types.Field, tparams2.Len())
 	for i := range tparams {
-		tp := tparams2[i]
+		tp := tparams2.At(i)
 		tparams[i] = types.NewField(g.pos(tp), g.sym(tp), g.typ1(tp.Type()))
 	}
 
@@ -346,7 +377,7 @@
 	return pkg.Lookup(name)
 }
 
-// tpkg returns the package that a function, interface, or struct type
+// tpkg returns the package that a function, interface, struct, or typeparam type
 // expression appeared in.
 //
 // Caveat: For the degenerate types "func()", "interface{}", and
@@ -356,36 +387,39 @@
 // particular types is because go/types does *not* report it for
 // them. So in practice this limitation is probably moot.
 func (g *irgen) tpkg(typ types2.Type) *types.Pkg {
-	anyObj := func() types2.Object {
-		switch typ := typ.(type) {
-		case *types2.Signature:
-			if recv := typ.Recv(); recv != nil {
-				return recv
-			}
-			if params := typ.Params(); params.Len() > 0 {
-				return params.At(0)
-			}
-			if results := typ.Results(); results.Len() > 0 {
-				return results.At(0)
-			}
-		case *types2.Struct:
-			if typ.NumFields() > 0 {
-				return typ.Field(0)
-			}
-		case *types2.Interface:
-			if typ.NumExplicitMethods() > 0 {
-				return typ.ExplicitMethod(0)
-			}
-		}
-		return nil
-	}
-
-	if obj := anyObj(); obj != nil {
+	if obj := anyObj(typ); obj != nil {
 		return g.pkg(obj.Pkg())
 	}
 	return types.LocalPkg
 }
 
+// anyObj returns some object accessible from typ, if any.
+func anyObj(typ types2.Type) types2.Object {
+	switch typ := typ.(type) {
+	case *types2.Signature:
+		if recv := typ.Recv(); recv != nil {
+			return recv
+		}
+		if params := typ.Params(); params.Len() > 0 {
+			return params.At(0)
+		}
+		if results := typ.Results(); results.Len() > 0 {
+			return results.At(0)
+		}
+	case *types2.Struct:
+		if typ.NumFields() > 0 {
+			return typ.Field(0)
+		}
+	case *types2.Interface:
+		if typ.NumExplicitMethods() > 0 {
+			return typ.ExplicitMethod(0)
+		}
+	case *types2.TypeParam:
+		return typ.Obj()
+	}
+	return nil
+}
+
 func (g *irgen) basic(typ *types2.Basic) *types.Type {
 	switch typ.Name() {
 	case "byte":
@@ -430,3 +464,11 @@
 	types2.SendOnly: types.Csend,
 	types2.RecvOnly: types.Crecv,
 }
+
+// deref2 does a single deref of types2 type t, if it is a pointer type.
+func deref2(t types2.Type) types2.Type {
+	if ptr := types2.AsPointer(t); ptr != nil {
+		t = ptr.Elem()
+	}
+	return t
+}
diff --git a/src/cmd/compile/internal/noder/unified.go b/src/cmd/compile/internal/noder/unified.go
new file mode 100644
index 0000000..9f80ca0
--- /dev/null
+++ b/src/cmd/compile/internal/noder/unified.go
@@ -0,0 +1,340 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"bytes"
+	"fmt"
+	"internal/goversion"
+	"io"
+	"runtime"
+	"sort"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/inline"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/compile/internal/types2"
+	"cmd/internal/src"
+)
+
+// localPkgReader holds the package reader used for reading the local
+// package. It exists so the unified IR linker can refer back to it
+// later.
+var localPkgReader *pkgReader
+
+// unified construct the local package's IR from syntax's AST.
+//
+// The pipeline contains 2 steps:
+//
+// (1) Generate package export data "stub".
+//
+// (2) Generate package IR from package export data.
+//
+// The package data "stub" at step (1) contains everything from the local package,
+// but nothing that have been imported. When we're actually writing out export data
+// to the output files (see writeNewExport function), we run the "linker", which does
+// a few things:
+//
+// + Updates compiler extensions data (e.g., inlining cost, escape analysis results).
+//
+// + Handles re-exporting any transitive dependencies.
+//
+// + Prunes out any unnecessary details (e.g., non-inlineable functions, because any
+//   downstream importers only care about inlinable functions).
+//
+// The source files are typechecked twice, once before writing export data
+// using types2 checker, once after read export data using gc/typecheck.
+// This duplication of work will go away once we always use types2 checker,
+// we can remove the gc/typecheck pass. The reason it is still here:
+//
+// + It reduces engineering costs in maintaining a fork of typecheck
+//   (e.g., no need to backport fixes like CL 327651).
+//
+// + It makes it easier to pass toolstash -cmp.
+//
+// + Historically, we would always re-run the typechecker after import, even though
+//   we know the imported data is valid. It's not ideal, but also not causing any
+//   problem either.
+//
+// + There's still transformation that being done during gc/typecheck, like rewriting
+//   multi-valued function call, or transform ir.OINDEX -> ir.OINDEXMAP.
+//
+// Using syntax+types2 tree, which already has a complete representation of generics,
+// the unified IR has the full typed AST for doing introspection during step (1).
+// In other words, we have all necessary information to build the generic IR form
+// (see writer.captureVars for an example).
+func unified(noders []*noder) {
+	inline.NewInline = InlineCall
+
+	if !quirksMode() {
+		writeNewExportFunc = writeNewExport
+	} else if base.Flag.G != 0 {
+		base.Errorf("cannot use -G and -d=quirksmode together")
+	}
+
+	newReadImportFunc = func(data string, pkg1 *types.Pkg, check *types2.Checker, packages map[string]*types2.Package) (pkg2 *types2.Package, err error) {
+		pr := newPkgDecoder(pkg1.Path, data)
+
+		// Read package descriptors for both types2 and compiler backend.
+		readPackage(newPkgReader(pr), pkg1)
+		pkg2 = readPackage2(check, packages, pr)
+		return
+	}
+
+	data := writePkgStub(noders)
+
+	// We already passed base.Flag.Lang to types2 to handle validating
+	// the user's source code. Bump it up now to the current version and
+	// re-parse, so typecheck doesn't complain if we construct IR that
+	// utilizes newer Go features.
+	base.Flag.Lang = fmt.Sprintf("go1.%d", goversion.Version)
+	types.ParseLangFlag()
+
+	assert(types.LocalPkg.Path == "")
+	types.LocalPkg.Height = 0 // reset so pkgReader.pkgIdx doesn't complain
+	target := typecheck.Target
+
+	typecheck.TypecheckAllowed = true
+
+	localPkgReader = newPkgReader(newPkgDecoder(types.LocalPkg.Path, data))
+	readPackage(localPkgReader, types.LocalPkg)
+
+	r := localPkgReader.newReader(relocMeta, privateRootIdx, syncPrivate)
+	r.ext = r
+	r.pkgInit(types.LocalPkg, target)
+
+	// Type-check any top-level assignments. We ignore non-assignments
+	// here because other declarations are typechecked as they're
+	// constructed.
+	for i, ndecls := 0, len(target.Decls); i < ndecls; i++ {
+		switch n := target.Decls[i]; n.Op() {
+		case ir.OAS, ir.OAS2:
+			target.Decls[i] = typecheck.Stmt(n)
+		}
+	}
+
+	// Don't use range--bodyIdx can add closures to todoBodies.
+	for len(todoBodies) > 0 {
+		// The order we expand bodies doesn't matter, so pop from the end
+		// to reduce todoBodies reallocations if it grows further.
+		fn := todoBodies[len(todoBodies)-1]
+		todoBodies = todoBodies[:len(todoBodies)-1]
+
+		pri, ok := bodyReader[fn]
+		assert(ok)
+		pri.funcBody(fn)
+
+		// Instantiated generic function: add to Decls for typechecking
+		// and compilation.
+		if fn.OClosure == nil && len(pri.dict.targs) != 0 {
+			target.Decls = append(target.Decls, fn)
+		}
+	}
+	todoBodies = nil
+
+	if !quirksMode() {
+		// TODO(mdempsky): Investigate generating wrappers in quirks mode too.
+		r.wrapTypes(target)
+	}
+
+	// Check that nothing snuck past typechecking.
+	for _, n := range target.Decls {
+		if n.Typecheck() == 0 {
+			base.FatalfAt(n.Pos(), "missed typecheck: %v", n)
+		}
+
+		// For functions, check that at least their first statement (if
+		// any) was typechecked too.
+		if fn, ok := n.(*ir.Func); ok && len(fn.Body) != 0 {
+			if stmt := fn.Body[0]; stmt.Typecheck() == 0 {
+				base.FatalfAt(stmt.Pos(), "missed typecheck: %v", stmt)
+			}
+		}
+	}
+
+	base.ExitIfErrors() // just in case
+}
+
+// writePkgStub type checks the given parsed source files,
+// writes an export data package stub representing them,
+// and returns the result.
+func writePkgStub(noders []*noder) string {
+	m, pkg, info := checkFiles(noders)
+
+	pw := newPkgWriter(m, pkg, info)
+
+	pw.collectDecls(noders)
+
+	publicRootWriter := pw.newWriter(relocMeta, syncPublic)
+	privateRootWriter := pw.newWriter(relocMeta, syncPrivate)
+
+	assert(publicRootWriter.idx == publicRootIdx)
+	assert(privateRootWriter.idx == privateRootIdx)
+
+	{
+		w := publicRootWriter
+		w.pkg(pkg)
+		w.bool(false) // has init; XXX
+
+		scope := pkg.Scope()
+		names := scope.Names()
+		w.len(len(names))
+		for _, name := range scope.Names() {
+			w.obj(scope.Lookup(name), nil)
+		}
+
+		w.sync(syncEOF)
+		w.flush()
+	}
+
+	{
+		w := privateRootWriter
+		w.ext = w
+		w.pkgInit(noders)
+		w.flush()
+	}
+
+	var sb bytes.Buffer // TODO(mdempsky): strings.Builder after #44505 is resolved
+	pw.dump(&sb)
+
+	// At this point, we're done with types2. Make sure the package is
+	// garbage collected.
+	freePackage(pkg)
+
+	return sb.String()
+}
+
+// freePackage ensures the given package is garbage collected.
+func freePackage(pkg *types2.Package) {
+	// The GC test below relies on a precise GC that runs finalizers as
+	// soon as objects are unreachable. Our implementation provides
+	// this, but other/older implementations may not (e.g., Go 1.4 does
+	// not because of #22350). To avoid imposing unnecessary
+	// restrictions on the GOROOT_BOOTSTRAP toolchain, we skip the test
+	// during bootstrapping.
+	if base.CompilerBootstrap {
+		return
+	}
+
+	// Set a finalizer on pkg so we can detect if/when it's collected.
+	done := make(chan struct{})
+	runtime.SetFinalizer(pkg, func(*types2.Package) { close(done) })
+
+	// Important: objects involved in cycles are not finalized, so zero
+	// out pkg to break its cycles and allow the finalizer to run.
+	*pkg = types2.Package{}
+
+	// It typically takes just 1 or 2 cycles to release pkg, but it
+	// doesn't hurt to try a few more times.
+	for i := 0; i < 10; i++ {
+		select {
+		case <-done:
+			return
+		default:
+			runtime.GC()
+		}
+	}
+
+	base.Fatalf("package never finalized")
+}
+
+func readPackage(pr *pkgReader, importpkg *types.Pkg) {
+	r := pr.newReader(relocMeta, publicRootIdx, syncPublic)
+
+	pkg := r.pkg()
+	assert(pkg == importpkg)
+
+	if r.bool() {
+		sym := pkg.Lookup(".inittask")
+		task := ir.NewNameAt(src.NoXPos, sym)
+		task.Class = ir.PEXTERN
+		sym.Def = task
+	}
+
+	for i, n := 0, r.len(); i < n; i++ {
+		r.sync(syncObject)
+		assert(!r.bool())
+		idx := r.reloc(relocObj)
+		assert(r.len() == 0)
+
+		path, name, code := r.p.peekObj(idx)
+		if code != objStub {
+			objReader[types.NewPkg(path, "").Lookup(name)] = pkgReaderIndex{pr, idx, nil}
+		}
+	}
+}
+
+func writeNewExport(out io.Writer) {
+	l := linker{
+		pw: newPkgEncoder(),
+
+		pkgs:  make(map[string]int),
+		decls: make(map[*types.Sym]int),
+	}
+
+	publicRootWriter := l.pw.newEncoder(relocMeta, syncPublic)
+	assert(publicRootWriter.idx == publicRootIdx)
+
+	var selfPkgIdx int
+
+	{
+		pr := localPkgReader
+		r := pr.newDecoder(relocMeta, publicRootIdx, syncPublic)
+
+		r.sync(syncPkg)
+		selfPkgIdx = l.relocIdx(pr, relocPkg, r.reloc(relocPkg))
+
+		r.bool() // has init
+
+		for i, n := 0, r.len(); i < n; i++ {
+			r.sync(syncObject)
+			assert(!r.bool())
+			idx := r.reloc(relocObj)
+			assert(r.len() == 0)
+
+			xpath, xname, xtag := pr.peekObj(idx)
+			assert(xpath == pr.pkgPath)
+			assert(xtag != objStub)
+
+			if types.IsExported(xname) {
+				l.relocIdx(pr, relocObj, idx)
+			}
+		}
+
+		r.sync(syncEOF)
+	}
+
+	{
+		var idxs []int
+		for _, idx := range l.decls {
+			idxs = append(idxs, idx)
+		}
+		sort.Ints(idxs)
+
+		w := publicRootWriter
+
+		w.sync(syncPkg)
+		w.reloc(relocPkg, selfPkgIdx)
+
+		w.bool(typecheck.Lookup(".inittask").Def != nil)
+
+		w.len(len(idxs))
+		for _, idx := range idxs {
+			w.sync(syncObject)
+			w.bool(false)
+			w.reloc(relocObj, idx)
+			w.len(0)
+		}
+
+		w.sync(syncEOF)
+		w.flush()
+	}
+
+	l.pw.dump(out)
+}
diff --git a/src/cmd/compile/internal/noder/unified_test.go b/src/cmd/compile/internal/noder/unified_test.go
new file mode 100644
index 0000000..96cc66f
--- /dev/null
+++ b/src/cmd/compile/internal/noder/unified_test.go
@@ -0,0 +1,153 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder_test
+
+import (
+	"encoding/json"
+	"flag"
+	exec "internal/execabs"
+	"os"
+	"reflect"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+var (
+	flagPkgs     = flag.String("pkgs", "std", "list of packages to compare (ignored in -short mode)")
+	flagAll      = flag.Bool("all", false, "enable testing of all GOOS/GOARCH targets")
+	flagParallel = flag.Bool("parallel", false, "test GOOS/GOARCH targets in parallel")
+)
+
+// TestUnifiedCompare implements a test similar to running:
+//
+//	$ go build -toolexec="toolstash -cmp" std
+//
+// The -pkgs flag controls the list of packages tested.
+//
+// By default, only the native GOOS/GOARCH target is enabled. The -all
+// flag enables testing of non-native targets. The -parallel flag
+// additionally enables testing of targets in parallel.
+//
+// Caution: Testing all targets is very resource intensive! On an IBM
+// P920 (dual Intel Xeon Gold 6154 CPUs; 36 cores, 192GB RAM), testing
+// all targets in parallel takes about 5 minutes. Using the 'go test'
+// command's -run flag for subtest matching is recommended for less
+// powerful machines.
+func TestUnifiedCompare(t *testing.T) {
+	targets, err := exec.Command("go", "tool", "dist", "list").Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, target := range strings.Fields(string(targets)) {
+		t.Run(target, func(t *testing.T) {
+			parts := strings.Split(target, "/")
+			goos, goarch := parts[0], parts[1]
+
+			if !(*flagAll || goos == runtime.GOOS && goarch == runtime.GOARCH) {
+				t.Skip("skipping non-native target (use -all to enable)")
+			}
+			if *flagParallel {
+				t.Parallel()
+			}
+
+			pkgs1 := loadPackages(t, goos, goarch, "-d=unified=0 -d=inlfuncswithclosures=0 -d=unifiedquirks=1 -G=0")
+			pkgs2 := loadPackages(t, goos, goarch, "-d=unified=1 -d=inlfuncswithclosures=0 -d=unifiedquirks=1 -G=0")
+
+			if len(pkgs1) != len(pkgs2) {
+				t.Fatalf("length mismatch: %v != %v", len(pkgs1), len(pkgs2))
+			}
+
+			for i := range pkgs1 {
+				pkg1 := pkgs1[i]
+				pkg2 := pkgs2[i]
+
+				path := pkg1.ImportPath
+				if path != pkg2.ImportPath {
+					t.Fatalf("mismatched paths: %q != %q", path, pkg2.ImportPath)
+				}
+
+				// Packages that don't have any source files (e.g., packages
+				// unsafe, embed/internal/embedtest, and cmd/internal/moddeps).
+				if pkg1.Export == "" && pkg2.Export == "" {
+					continue
+				}
+
+				if pkg1.BuildID == pkg2.BuildID {
+					t.Errorf("package %q: build IDs unexpectedly matched", path)
+				}
+
+				// Unlike toolstash -cmp, we're comparing the same compiler
+				// binary against itself, just with different flags. So we
+				// don't need to worry about skipping over mismatched version
+				// strings, but we do need to account for differing build IDs.
+				//
+				// Fortunately, build IDs are cryptographic 256-bit hashes,
+				// and cmd/go provides us with them up front. So we can just
+				// use them as delimeters to split the files, and then check
+				// that the substrings are all equal.
+				file1 := strings.Split(readFile(t, pkg1.Export), pkg1.BuildID)
+				file2 := strings.Split(readFile(t, pkg2.Export), pkg2.BuildID)
+				if !reflect.DeepEqual(file1, file2) {
+					t.Errorf("package %q: compile output differs", path)
+				}
+			}
+		})
+	}
+}
+
+type pkg struct {
+	ImportPath string
+	Export     string
+	BuildID    string
+	Incomplete bool
+}
+
+func loadPackages(t *testing.T, goos, goarch, gcflags string) []pkg {
+	args := []string{"list", "-e", "-export", "-json", "-gcflags=all=" + gcflags, "--"}
+	if testing.Short() {
+		t.Log("short testing mode; only testing package runtime")
+		args = append(args, "runtime")
+	} else {
+		args = append(args, strings.Fields(*flagPkgs)...)
+	}
+
+	cmd := exec.Command("go", args...)
+	cmd.Env = append(os.Environ(), "GOOS="+goos, "GOARCH="+goarch)
+	cmd.Stderr = os.Stderr
+	t.Logf("running %v", cmd)
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := cmd.Start(); err != nil {
+		t.Fatal(err)
+	}
+
+	var res []pkg
+	for dec := json.NewDecoder(stdout); dec.More(); {
+		var pkg pkg
+		if err := dec.Decode(&pkg); err != nil {
+			t.Fatal(err)
+		}
+		if pkg.Incomplete {
+			t.Fatalf("incomplete package: %q", pkg.ImportPath)
+		}
+		res = append(res, pkg)
+	}
+	if err := cmd.Wait(); err != nil {
+		t.Fatal(err)
+	}
+	return res
+}
+
+func readFile(t *testing.T, name string) string {
+	buf, err := os.ReadFile(name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(buf)
+}
diff --git a/src/cmd/compile/internal/noder/validate.go b/src/cmd/compile/internal/noder/validate.go
index b926222..68a059b 100644
--- a/src/cmd/compile/internal/noder/validate.go
+++ b/src/cmd/compile/internal/noder/validate.go
@@ -55,7 +55,15 @@
 	case *syntax.CallExpr:
 		tv := g.info.Types[n.Fun]
 		if tv.IsBuiltin() {
-			switch builtin := n.Fun.(type) {
+			fun := n.Fun
+			for {
+				builtin, ok := fun.(*syntax.ParenExpr)
+				if !ok {
+					break
+				}
+				fun = builtin.X
+			}
+			switch builtin := fun.(type) {
 			case *syntax.Name:
 				g.validateBuiltin(builtin.Value, n)
 			case *syntax.SelectorExpr:
diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
new file mode 100644
index 0000000..b5028e7
--- /dev/null
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -0,0 +1,1885 @@
+// UNREVIEWED
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"fmt"
+	"go/constant"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/types2"
+)
+
+type pkgWriter struct {
+	pkgEncoder
+
+	m      posMap
+	curpkg *types2.Package
+	info   *types2.Info
+
+	posBasesIdx map[*syntax.PosBase]int
+	pkgsIdx     map[*types2.Package]int
+	typsIdx     map[types2.Type]int
+	globalsIdx  map[types2.Object]int
+
+	funDecls map[*types2.Func]*syntax.FuncDecl
+	typDecls map[*types2.TypeName]typeDeclGen
+
+	linknames  map[types2.Object]string
+	cgoPragmas [][]string
+
+	dups dupTypes
+}
+
+func newPkgWriter(m posMap, pkg *types2.Package, info *types2.Info) *pkgWriter {
+	return &pkgWriter{
+		pkgEncoder: newPkgEncoder(),
+
+		m:      m,
+		curpkg: pkg,
+		info:   info,
+
+		pkgsIdx:    make(map[*types2.Package]int),
+		globalsIdx: make(map[types2.Object]int),
+		typsIdx:    make(map[types2.Type]int),
+
+		posBasesIdx: make(map[*syntax.PosBase]int),
+
+		funDecls: make(map[*types2.Func]*syntax.FuncDecl),
+		typDecls: make(map[*types2.TypeName]typeDeclGen),
+
+		linknames: make(map[types2.Object]string),
+	}
+}
+
+func (pw *pkgWriter) errorf(p poser, msg string, args ...interface{}) {
+	base.ErrorfAt(pw.m.pos(p), msg, args...)
+}
+
+func (pw *pkgWriter) fatalf(p poser, msg string, args ...interface{}) {
+	base.FatalfAt(pw.m.pos(p), msg, args...)
+}
+
+func (pw *pkgWriter) unexpected(what string, p poser) {
+	pw.fatalf(p, "unexpected %s: %v (%T)", what, p, p)
+}
+
+type writer struct {
+	p *pkgWriter
+
+	encoder
+
+	// For writing out object descriptions, ext points to the extension
+	// writer for where we can write the compiler's private extension
+	// details for the object.
+	//
+	// TODO(mdempsky): This is a little hacky, but works easiest with
+	// the way things are currently.
+	ext *writer
+
+	// TODO(mdempsky): We should be able to prune localsIdx whenever a
+	// scope closes, and then maybe we can just use the same map for
+	// storing the TypeParams too (as their TypeName instead).
+
+	// variables declared within this function
+	localsIdx map[*types2.Var]int
+
+	closureVars    []posObj
+	closureVarsIdx map[*types2.Var]int
+
+	dict    *writerDict
+	derived bool
+}
+
+// A writerDict tracks types and objects that are used by a declaration.
+type writerDict struct {
+	implicits []*types2.TypeName
+
+	// derived is a slice of type indices for computing derived types
+	// (i.e., types that depend on the declaration's type parameters).
+	derived []derivedInfo
+
+	// derivedIdx maps a Type to its corresponding index within the
+	// derived slice, if present.
+	derivedIdx map[types2.Type]int
+
+	// funcs lists references to generic functions that were
+	// instantiated with derived types (i.e., that require
+	// sub-dictionaries when called at run time).
+	funcs []objInfo
+}
+
+type derivedInfo struct {
+	idx    int
+	needed bool
+}
+
+type typeInfo struct {
+	idx     int
+	derived bool
+}
+
+type objInfo struct {
+	idx       int        // index for the generic function declaration
+	explicits []typeInfo // info for the type arguments
+}
+
+func (info objInfo) anyDerived() bool {
+	for _, explicit := range info.explicits {
+		if explicit.derived {
+			return true
+		}
+	}
+	return false
+}
+
+func (info objInfo) equals(other objInfo) bool {
+	if info.idx != other.idx {
+		return false
+	}
+	assert(len(info.explicits) == len(other.explicits))
+	for i, targ := range info.explicits {
+		if targ != other.explicits[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func (pw *pkgWriter) newWriter(k reloc, marker syncMarker) *writer {
+	return &writer{
+		encoder: pw.newEncoder(k, marker),
+		p:       pw,
+	}
+}
+
+// @@@ Positions
+
+func (w *writer) pos(p poser) {
+	w.sync(syncPos)
+	pos := p.Pos()
+
+	// TODO(mdempsky): Track down the remaining cases here and fix them.
+	if !w.bool(pos.IsKnown()) {
+		return
+	}
+
+	// TODO(mdempsky): Delta encoding. Also, if there's a b-side, update
+	// its position base too (but not vice versa!).
+	w.posBase(pos.Base())
+	w.uint(pos.Line())
+	w.uint(pos.Col())
+}
+
+func (w *writer) posBase(b *syntax.PosBase) {
+	w.reloc(relocPosBase, w.p.posBaseIdx(b))
+}
+
+func (pw *pkgWriter) posBaseIdx(b *syntax.PosBase) int {
+	if idx, ok := pw.posBasesIdx[b]; ok {
+		return idx
+	}
+
+	w := pw.newWriter(relocPosBase, syncPosBase)
+	w.p.posBasesIdx[b] = w.idx
+
+	// TODO(mdempsky): What exactly does "fileh" do anyway? Is writing
+	// out both of these strings really the right thing to do here?
+	fn := b.Filename()
+	w.string(fn)
+	w.string(fileh(fn))
+
+	if !w.bool(b.IsFileBase()) {
+		w.pos(b)
+		w.uint(b.Line())
+		w.uint(b.Col())
+	}
+
+	return w.flush()
+}
+
+// @@@ Packages
+
+func (w *writer) pkg(pkg *types2.Package) {
+	w.sync(syncPkg)
+	w.reloc(relocPkg, w.p.pkgIdx(pkg))
+}
+
+func (pw *pkgWriter) pkgIdx(pkg *types2.Package) int {
+	if idx, ok := pw.pkgsIdx[pkg]; ok {
+		return idx
+	}
+
+	w := pw.newWriter(relocPkg, syncPkgDef)
+	pw.pkgsIdx[pkg] = w.idx
+
+	if pkg == nil {
+		w.string("builtin")
+	} else {
+		var path string
+		if pkg != w.p.curpkg {
+			path = pkg.Path()
+		}
+		w.string(path)
+		w.string(pkg.Name())
+		w.len(pkg.Height())
+
+		w.len(len(pkg.Imports()))
+		for _, imp := range pkg.Imports() {
+			w.pkg(imp)
+		}
+	}
+
+	return w.flush()
+}
+
+// @@@ Types
+
+func (w *writer) typ(typ types2.Type) {
+	w.typInfo(w.p.typIdx(typ, w.dict))
+}
+
+func (w *writer) typInfo(info typeInfo) {
+	w.sync(syncType)
+	if w.bool(info.derived) {
+		w.len(info.idx)
+		w.derived = true
+	} else {
+		w.reloc(relocType, info.idx)
+	}
+}
+
+// typIdx returns the index where the export data description of type
+// can be read back in. If no such index exists yet, it's created.
+//
+// typIdx also reports whether typ is a derived type; that is, whether
+// its identity depends on type parameters.
+func (pw *pkgWriter) typIdx(typ types2.Type, dict *writerDict) typeInfo {
+	if quirksMode() {
+		typ = pw.dups.orig(typ)
+	}
+
+	if idx, ok := pw.typsIdx[typ]; ok {
+		return typeInfo{idx: idx, derived: false}
+	}
+	if dict != nil {
+		if idx, ok := dict.derivedIdx[typ]; ok {
+			return typeInfo{idx: idx, derived: true}
+		}
+	}
+
+	w := pw.newWriter(relocType, syncTypeIdx)
+	w.dict = dict
+
+	switch typ := typ.(type) {
+	default:
+		base.Fatalf("unexpected type: %v (%T)", typ, typ)
+
+	case *types2.Basic:
+		switch kind := typ.Kind(); {
+		case kind == types2.Invalid:
+			base.Fatalf("unexpected types2.Invalid")
+
+		case types2.Typ[kind] == typ:
+			w.code(typeBasic)
+			w.len(int(kind))
+
+		default:
+			// Handle "byte" and "rune" as references to their TypeName.
+			obj := types2.Universe.Lookup(typ.Name())
+			assert(obj.Type() == typ)
+
+			w.code(typeNamed)
+			w.obj(obj, nil)
+		}
+
+	case *types2.Named:
+		// Type aliases can refer to uninstantiated generic types, so we
+		// might see len(TParams) != 0 && len(TArgs) == 0 here.
+		// TODO(mdempsky): Revisit after #46477 is resolved.
+		assert(typ.TParams().Len() == len(typ.TArgs()) || len(typ.TArgs()) == 0)
+
+		// TODO(mdempsky): Why do we need to loop here?
+		orig := typ
+		for orig.TArgs() != nil {
+			orig = orig.Orig()
+		}
+
+		w.code(typeNamed)
+		w.obj(orig.Obj(), typ.TArgs())
+
+	case *types2.TypeParam:
+		index := func() int {
+			for idx, name := range w.dict.implicits {
+				if name.Type().(*types2.TypeParam) == typ {
+					return idx
+				}
+			}
+
+			return len(w.dict.implicits) + typ.Index()
+		}()
+
+		w.derived = true
+		w.code(typeTypeParam)
+		w.len(index)
+
+	case *types2.Array:
+		w.code(typeArray)
+		w.uint64(uint64(typ.Len()))
+		w.typ(typ.Elem())
+
+	case *types2.Chan:
+		w.code(typeChan)
+		w.len(int(typ.Dir()))
+		w.typ(typ.Elem())
+
+	case *types2.Map:
+		w.code(typeMap)
+		w.typ(typ.Key())
+		w.typ(typ.Elem())
+
+	case *types2.Pointer:
+		w.code(typePointer)
+		w.typ(typ.Elem())
+
+	case *types2.Signature:
+		assert(typ.TParams() == nil)
+		w.code(typeSignature)
+		w.signature(typ)
+
+	case *types2.Slice:
+		w.code(typeSlice)
+		w.typ(typ.Elem())
+
+	case *types2.Struct:
+		w.code(typeStruct)
+		w.structType(typ)
+
+	case *types2.Interface:
+		w.code(typeInterface)
+		w.interfaceType(typ)
+
+	case *types2.Union:
+		w.code(typeUnion)
+		w.unionType(typ)
+	}
+
+	if w.derived {
+		idx := len(dict.derived)
+		dict.derived = append(dict.derived, derivedInfo{idx: w.flush()})
+		dict.derivedIdx[typ] = idx
+		return typeInfo{idx: idx, derived: true}
+	}
+
+	pw.typsIdx[typ] = w.idx
+	return typeInfo{idx: w.flush(), derived: false}
+}
+
+func (w *writer) structType(typ *types2.Struct) {
+	w.len(typ.NumFields())
+	for i := 0; i < typ.NumFields(); i++ {
+		f := typ.Field(i)
+		w.pos(f)
+		w.selector(f)
+		w.typ(f.Type())
+		w.string(typ.Tag(i))
+		w.bool(f.Embedded())
+	}
+}
+
+func (w *writer) unionType(typ *types2.Union) {
+	w.len(typ.Len())
+	for i := 0; i < typ.Len(); i++ {
+		t := typ.Term(i)
+		w.bool(t.Tilde())
+		w.typ(t.Type())
+	}
+}
+
+func (w *writer) interfaceType(typ *types2.Interface) {
+	w.len(typ.NumExplicitMethods())
+	w.len(typ.NumEmbeddeds())
+
+	for i := 0; i < typ.NumExplicitMethods(); i++ {
+		m := typ.ExplicitMethod(i)
+		sig := m.Type().(*types2.Signature)
+		assert(sig.TParams() == nil)
+
+		w.pos(m)
+		w.selector(m)
+		w.signature(sig)
+	}
+
+	for i := 0; i < typ.NumEmbeddeds(); i++ {
+		w.typ(typ.EmbeddedType(i))
+	}
+}
+
+func (w *writer) signature(sig *types2.Signature) {
+	w.sync(syncSignature)
+	w.params(sig.Params())
+	w.params(sig.Results())
+	w.bool(sig.Variadic())
+}
+
+func (w *writer) params(typ *types2.Tuple) {
+	w.sync(syncParams)
+	w.len(typ.Len())
+	for i := 0; i < typ.Len(); i++ {
+		w.param(typ.At(i))
+	}
+}
+
+func (w *writer) param(param *types2.Var) {
+	w.sync(syncParam)
+	w.pos(param)
+	w.localIdent(param)
+	w.typ(param.Type())
+}
+
+// @@@ Objects
+
+func (w *writer) obj(obj types2.Object, explicits []types2.Type) {
+	explicitInfos := make([]typeInfo, len(explicits))
+	for i, explicit := range explicits {
+		explicitInfos[i] = w.p.typIdx(explicit, w.dict)
+	}
+	info := objInfo{idx: w.p.objIdx(obj), explicits: explicitInfos}
+
+	if _, ok := obj.(*types2.Func); ok && info.anyDerived() {
+		idx := -1
+		for i, prev := range w.dict.funcs {
+			if prev.equals(info) {
+				idx = i
+			}
+		}
+		if idx < 0 {
+			idx = len(w.dict.funcs)
+			w.dict.funcs = append(w.dict.funcs, info)
+		}
+
+		// TODO(mdempsky): Push up into expr; this shouldn't appear
+		// outside of expression context.
+		w.sync(syncObject)
+		w.bool(true)
+		w.len(idx)
+		return
+	}
+
+	// TODO(mdempsky): Push up into typIdx; this shouldn't be needed
+	// except while writing out types.
+	if isDefinedType(obj) && obj.Pkg() == w.p.curpkg {
+		decl, ok := w.p.typDecls[obj.(*types2.TypeName)]
+		assert(ok)
+		if len(decl.implicits) != 0 {
+			w.derived = true
+		}
+	}
+
+	w.sync(syncObject)
+	w.bool(false)
+	w.reloc(relocObj, info.idx)
+
+	w.len(len(info.explicits))
+	for _, info := range info.explicits {
+		w.typInfo(info)
+	}
+}
+
+func (pw *pkgWriter) objIdx(obj types2.Object) int {
+	if idx, ok := pw.globalsIdx[obj]; ok {
+		return idx
+	}
+
+	dict := &writerDict{
+		derivedIdx: make(map[types2.Type]int),
+	}
+
+	if isDefinedType(obj) && obj.Pkg() == pw.curpkg {
+		decl, ok := pw.typDecls[obj.(*types2.TypeName)]
+		assert(ok)
+		dict.implicits = decl.implicits
+	}
+
+	w := pw.newWriter(relocObj, syncObject1)
+	w.ext = pw.newWriter(relocObjExt, syncObject1)
+	wname := pw.newWriter(relocName, syncObject1)
+	wdict := pw.newWriter(relocObjDict, syncObject1)
+
+	pw.globalsIdx[obj] = w.idx // break cycles
+	assert(w.ext.idx == w.idx)
+	assert(wname.idx == w.idx)
+	assert(wdict.idx == w.idx)
+
+	w.dict = dict
+	w.ext.dict = dict
+
+	code := w.doObj(obj)
+	w.flush()
+	w.ext.flush()
+
+	wname.qualifiedIdent(obj)
+	wname.code(code)
+	wname.flush()
+
+	wdict.objDict(obj, w.dict)
+	wdict.flush()
+
+	return w.idx
+}
+
+func (w *writer) doObj(obj types2.Object) codeObj {
+	if obj.Pkg() != w.p.curpkg {
+		return objStub
+	}
+
+	switch obj := obj.(type) {
+	default:
+		w.p.unexpected("object", obj)
+		panic("unreachable")
+
+	case *types2.Const:
+		w.pos(obj)
+		w.value(obj.Type(), obj.Val())
+		return objConst
+
+	case *types2.Func:
+		decl, ok := w.p.funDecls[obj]
+		assert(ok)
+		sig := obj.Type().(*types2.Signature)
+
+		w.pos(obj)
+		w.typeParamNames(sig.TParams())
+		w.signature(sig)
+		w.pos(decl)
+		w.ext.funcExt(obj)
+		return objFunc
+
+	case *types2.TypeName:
+		decl, ok := w.p.typDecls[obj]
+		assert(ok)
+
+		if obj.IsAlias() {
+			w.pos(obj)
+			w.typ(obj.Type())
+			return objAlias
+		}
+
+		named := obj.Type().(*types2.Named)
+		assert(named.TArgs() == nil)
+
+		w.pos(obj)
+		w.typeParamNames(named.TParams())
+		w.ext.typeExt(obj)
+		w.typExpr(decl.Type)
+
+		w.len(named.NumMethods())
+		for i := 0; i < named.NumMethods(); i++ {
+			w.method(named.Method(i))
+		}
+
+		return objType
+
+	case *types2.Var:
+		w.pos(obj)
+		w.typ(obj.Type())
+		w.ext.varExt(obj)
+		return objVar
+	}
+}
+
+// typExpr writes the type represented by the given expression.
+func (w *writer) typExpr(expr syntax.Expr) {
+	tv, ok := w.p.info.Types[expr]
+	assert(ok)
+	assert(tv.IsType())
+	w.typ(tv.Type)
+}
+
+func (w *writer) value(typ types2.Type, val constant.Value) {
+	w.sync(syncValue)
+	w.typ(typ)
+	w.rawValue(val)
+}
+
+// objDict writes the dictionary needed for reading the given object.
+func (w *writer) objDict(obj types2.Object, dict *writerDict) {
+	// TODO(mdempsky): Split objDict into multiple entries? reader.go
+	// doesn't care about the type parameter bounds, and reader2.go
+	// doesn't care about referenced functions.
+
+	w.dict = dict // TODO(mdempsky): This is a bit sketchy.
+
+	w.len(len(dict.implicits))
+
+	tparams := objTypeParams(obj)
+	ntparams := tparams.Len()
+	w.len(ntparams)
+	for i := 0; i < ntparams; i++ {
+		w.typ(tparams.At(i).Type().(*types2.TypeParam).Constraint())
+	}
+
+	nderived := len(dict.derived)
+	w.len(nderived)
+	for _, typ := range dict.derived {
+		w.reloc(relocType, typ.idx)
+		w.bool(typ.needed)
+	}
+
+	nfuncs := len(dict.funcs)
+	w.len(nfuncs)
+	for _, fn := range dict.funcs {
+		w.reloc(relocObj, fn.idx)
+		w.len(len(fn.explicits))
+		for _, targ := range fn.explicits {
+			w.typInfo(targ)
+		}
+	}
+
+	assert(len(dict.derived) == nderived)
+	assert(len(dict.funcs) == nfuncs)
+}
+
+func (w *writer) typeParamNames(tparams *types2.TypeParams) {
+	w.sync(syncTypeParamNames)
+
+	ntparams := tparams.Len()
+	for i := 0; i < ntparams; i++ {
+		tparam := tparams.At(i)
+		w.pos(tparam)
+		w.localIdent(tparam)
+	}
+}
+
+func (w *writer) method(meth *types2.Func) {
+	decl, ok := w.p.funDecls[meth]
+	assert(ok)
+	sig := meth.Type().(*types2.Signature)
+
+	w.sync(syncMethod)
+	w.pos(meth)
+	w.selector(meth)
+	w.typeParamNames(sig.RParams())
+	w.param(sig.Recv())
+	w.signature(sig)
+
+	w.pos(decl) // XXX: Hack to workaround linker limitations.
+	w.ext.funcExt(meth)
+}
+
+// qualifiedIdent writes out the name of an object declared at package
+// scope. (For now, it's also used to refer to local defined types.)
+func (w *writer) qualifiedIdent(obj types2.Object) {
+	w.sync(syncSym)
+
+	name := obj.Name()
+	if isDefinedType(obj) && obj.Pkg() == w.p.curpkg {
+		decl, ok := w.p.typDecls[obj.(*types2.TypeName)]
+		assert(ok)
+		if decl.gen != 0 {
+			// TODO(mdempsky): Find a better solution than embedding middle
+			// dot in the symbol name; this is terrible.
+			name = fmt.Sprintf("%s·%v", name, decl.gen)
+		}
+	}
+
+	w.pkg(obj.Pkg())
+	w.string(name)
+}
+
+// TODO(mdempsky): We should be able to omit pkg from both localIdent
+// and selector, because they should always be known from context.
+// However, past frustrations with this optimization in iexport make
+// me a little nervous to try it again.
+
+// localIdent writes the name of a locally declared object (i.e.,
+// objects that can only be accessed by name, within the context of a
+// particular function).
+func (w *writer) localIdent(obj types2.Object) {
+	assert(!isGlobal(obj))
+	w.sync(syncLocalIdent)
+	w.pkg(obj.Pkg())
+	w.string(obj.Name())
+}
+
+// selector writes the name of a field or method (i.e., objects that
+// can only be accessed using selector expressions).
+func (w *writer) selector(obj types2.Object) {
+	w.sync(syncSelector)
+	w.pkg(obj.Pkg())
+	w.string(obj.Name())
+}
+
+// @@@ Compiler extensions
+
+func (w *writer) funcExt(obj *types2.Func) {
+	decl, ok := w.p.funDecls[obj]
+	assert(ok)
+
+	// TODO(mdempsky): Extend these pragma validation flags to account
+	// for generics. E.g., linkname probably doesn't make sense at
+	// least.
+
+	pragma := asPragmaFlag(decl.Pragma)
+	if pragma&ir.Systemstack != 0 && pragma&ir.Nosplit != 0 {
+		w.p.errorf(decl, "go:nosplit and go:systemstack cannot be combined")
+	}
+
+	if decl.Body != nil {
+		if pragma&ir.Noescape != 0 {
+			w.p.errorf(decl, "can only use //go:noescape with external func implementations")
+		}
+	} else {
+		if base.Flag.Complete || decl.Name.Value == "init" {
+			// Linknamed functions are allowed to have no body. Hopefully
+			// the linkname target has a body. See issue 23311.
+			if _, ok := w.p.linknames[obj]; !ok {
+				w.p.errorf(decl, "missing function body")
+			}
+		}
+	}
+
+	sig, block := obj.Type().(*types2.Signature), decl.Body
+	body, closureVars := w.p.bodyIdx(w.p.curpkg, sig, block, w.dict)
+	assert(len(closureVars) == 0)
+
+	w.sync(syncFuncExt)
+	w.pragmaFlag(pragma)
+	w.linkname(obj)
+	w.bool(false) // stub extension
+	w.reloc(relocBody, body)
+	w.sync(syncEOF)
+}
+
+func (w *writer) typeExt(obj *types2.TypeName) {
+	decl, ok := w.p.typDecls[obj]
+	assert(ok)
+
+	w.sync(syncTypeExt)
+
+	w.pragmaFlag(asPragmaFlag(decl.Pragma))
+
+	// No LSym.SymIdx info yet.
+	w.int64(-1)
+	w.int64(-1)
+}
+
+func (w *writer) varExt(obj *types2.Var) {
+	w.sync(syncVarExt)
+	w.linkname(obj)
+}
+
+func (w *writer) linkname(obj types2.Object) {
+	w.sync(syncLinkname)
+	w.int64(-1)
+	w.string(w.p.linknames[obj])
+}
+
+func (w *writer) pragmaFlag(p ir.PragmaFlag) {
+	w.sync(syncPragma)
+	w.int(int(p))
+}
+
+// @@@ Function bodies
+
+func (pw *pkgWriter) bodyIdx(pkg *types2.Package, sig *types2.Signature, block *syntax.BlockStmt, dict *writerDict) (idx int, closureVars []posObj) {
+	w := pw.newWriter(relocBody, syncFuncBody)
+	w.dict = dict
+
+	w.funcargs(sig)
+	if w.bool(block != nil) {
+		w.stmts(block.List)
+		w.pos(block.Rbrace)
+	}
+
+	return w.flush(), w.closureVars
+}
+
+func (w *writer) funcargs(sig *types2.Signature) {
+	do := func(params *types2.Tuple, result bool) {
+		for i := 0; i < params.Len(); i++ {
+			w.funcarg(params.At(i), result)
+		}
+	}
+
+	if recv := sig.Recv(); recv != nil {
+		w.funcarg(recv, false)
+	}
+	do(sig.Params(), false)
+	do(sig.Results(), true)
+}
+
+func (w *writer) funcarg(param *types2.Var, result bool) {
+	if param.Name() != "" || result {
+		w.addLocal(param)
+	}
+}
+
+func (w *writer) addLocal(obj *types2.Var) {
+	w.sync(syncAddLocal)
+	idx := len(w.localsIdx)
+	if enableSync {
+		w.int(idx)
+	}
+	if w.localsIdx == nil {
+		w.localsIdx = make(map[*types2.Var]int)
+	}
+	w.localsIdx[obj] = idx
+}
+
+func (w *writer) useLocal(pos syntax.Pos, obj *types2.Var) {
+	w.sync(syncUseObjLocal)
+
+	if idx, ok := w.localsIdx[obj]; w.bool(ok) {
+		w.len(idx)
+		return
+	}
+
+	idx, ok := w.closureVarsIdx[obj]
+	if !ok {
+		if w.closureVarsIdx == nil {
+			w.closureVarsIdx = make(map[*types2.Var]int)
+		}
+		idx = len(w.closureVars)
+		w.closureVars = append(w.closureVars, posObj{pos, obj})
+		w.closureVarsIdx[obj] = idx
+	}
+	w.len(idx)
+}
+
+func (w *writer) openScope(pos syntax.Pos) {
+	w.sync(syncOpenScope)
+	w.pos(pos)
+}
+
+func (w *writer) closeScope(pos syntax.Pos) {
+	w.sync(syncCloseScope)
+	w.pos(pos)
+	w.closeAnotherScope()
+}
+
+func (w *writer) closeAnotherScope() {
+	w.sync(syncCloseAnotherScope)
+}
+
+// @@@ Statements
+
+func (w *writer) stmt(stmt syntax.Stmt) {
+	var stmts []syntax.Stmt
+	if stmt != nil {
+		stmts = []syntax.Stmt{stmt}
+	}
+	w.stmts(stmts)
+}
+
+func (w *writer) stmts(stmts []syntax.Stmt) {
+	w.sync(syncStmts)
+	for _, stmt := range stmts {
+		w.stmt1(stmt)
+	}
+	w.code(stmtEnd)
+	w.sync(syncStmtsEnd)
+}
+
+func (w *writer) stmt1(stmt syntax.Stmt) {
+	switch stmt := stmt.(type) {
+	default:
+		w.p.unexpected("statement", stmt)
+
+	case nil, *syntax.EmptyStmt:
+		return
+
+	case *syntax.AssignStmt:
+		switch {
+		case stmt.Rhs == nil:
+			w.code(stmtIncDec)
+			w.op(binOps[stmt.Op])
+			w.expr(stmt.Lhs)
+			w.pos(stmt)
+
+		case stmt.Op != 0 && stmt.Op != syntax.Def:
+			w.code(stmtAssignOp)
+			w.op(binOps[stmt.Op])
+			w.expr(stmt.Lhs)
+			w.pos(stmt)
+			w.expr(stmt.Rhs)
+
+		default:
+			w.code(stmtAssign)
+			w.pos(stmt)
+			w.exprList(stmt.Rhs)
+			w.assignList(stmt.Lhs)
+		}
+
+	case *syntax.BlockStmt:
+		w.code(stmtBlock)
+		w.blockStmt(stmt)
+
+	case *syntax.BranchStmt:
+		w.code(stmtBranch)
+		w.pos(stmt)
+		w.op(branchOps[stmt.Tok])
+		w.optLabel(stmt.Label)
+
+	case *syntax.CallStmt:
+		w.code(stmtCall)
+		w.pos(stmt)
+		w.op(callOps[stmt.Tok])
+		w.expr(stmt.Call)
+
+	case *syntax.DeclStmt:
+		for _, decl := range stmt.DeclList {
+			w.declStmt(decl)
+		}
+
+	case *syntax.ExprStmt:
+		w.code(stmtExpr)
+		w.expr(stmt.X)
+
+	case *syntax.ForStmt:
+		w.code(stmtFor)
+		w.forStmt(stmt)
+
+	case *syntax.IfStmt:
+		w.code(stmtIf)
+		w.ifStmt(stmt)
+
+	case *syntax.LabeledStmt:
+		w.code(stmtLabel)
+		w.pos(stmt)
+		w.label(stmt.Label)
+		w.stmt1(stmt.Stmt)
+
+	case *syntax.ReturnStmt:
+		w.code(stmtReturn)
+		w.pos(stmt)
+		w.exprList(stmt.Results)
+
+	case *syntax.SelectStmt:
+		w.code(stmtSelect)
+		w.selectStmt(stmt)
+
+	case *syntax.SendStmt:
+		w.code(stmtSend)
+		w.pos(stmt)
+		w.expr(stmt.Chan)
+		w.expr(stmt.Value)
+
+	case *syntax.SwitchStmt:
+		w.code(stmtSwitch)
+		w.switchStmt(stmt)
+	}
+}
+
+func (w *writer) assignList(expr syntax.Expr) {
+	exprs := unpackListExpr(expr)
+	w.len(len(exprs))
+
+	for _, expr := range exprs {
+		if name, ok := expr.(*syntax.Name); ok && name.Value != "_" {
+			if obj, ok := w.p.info.Defs[name]; ok {
+				obj := obj.(*types2.Var)
+
+				w.bool(true)
+				w.pos(obj)
+				w.localIdent(obj)
+				w.typ(obj.Type())
+
+				// TODO(mdempsky): Minimize locals index size by deferring
+				// this until the variables actually come into scope.
+				w.addLocal(obj)
+				continue
+			}
+		}
+
+		w.bool(false)
+		w.expr(expr)
+	}
+}
+
+func (w *writer) declStmt(decl syntax.Decl) {
+	switch decl := decl.(type) {
+	default:
+		w.p.unexpected("declaration", decl)
+
+	case *syntax.ConstDecl:
+
+	case *syntax.TypeDecl:
+		// Quirk: The legacy inliner doesn't support inlining functions
+		// with type declarations. Unified IR doesn't have any need to
+		// write out type declarations explicitly (they're always looked
+		// up via global index tables instead), so we just write out a
+		// marker so the reader knows to synthesize a fake declaration to
+		// prevent inlining.
+		if quirksMode() {
+			w.code(stmtTypeDeclHack)
+		}
+
+	case *syntax.VarDecl:
+		values := unpackListExpr(decl.Values)
+
+		// Quirk: When N variables are declared with N initialization
+		// values, we need to decompose that into N interleaved
+		// declarations+initializations, because it leads to different
+		// (albeit semantically equivalent) code generation.
+		if quirksMode() && len(decl.NameList) == len(values) {
+			for i, name := range decl.NameList {
+				w.code(stmtAssign)
+				w.pos(decl)
+				w.exprList(values[i])
+				w.assignList(name)
+			}
+			break
+		}
+
+		w.code(stmtAssign)
+		w.pos(decl)
+		w.exprList(decl.Values)
+		w.assignList(namesAsExpr(decl.NameList))
+	}
+}
+
+func (w *writer) blockStmt(stmt *syntax.BlockStmt) {
+	w.sync(syncBlockStmt)
+	w.openScope(stmt.Pos())
+	w.stmts(stmt.List)
+	w.closeScope(stmt.Rbrace)
+}
+
+func (w *writer) forStmt(stmt *syntax.ForStmt) {
+	w.sync(syncForStmt)
+	w.openScope(stmt.Pos())
+
+	if rang, ok := stmt.Init.(*syntax.RangeClause); w.bool(ok) {
+		w.pos(rang)
+		w.expr(rang.X)
+		w.assignList(rang.Lhs)
+	} else {
+		w.pos(stmt)
+		w.stmt(stmt.Init)
+		w.expr(stmt.Cond)
+		w.stmt(stmt.Post)
+	}
+
+	w.blockStmt(stmt.Body)
+	w.closeAnotherScope()
+}
+
+func (w *writer) ifStmt(stmt *syntax.IfStmt) {
+	w.sync(syncIfStmt)
+	w.openScope(stmt.Pos())
+	w.pos(stmt)
+	w.stmt(stmt.Init)
+	w.expr(stmt.Cond)
+	w.blockStmt(stmt.Then)
+	w.stmt(stmt.Else)
+	w.closeAnotherScope()
+}
+
+func (w *writer) selectStmt(stmt *syntax.SelectStmt) {
+	w.sync(syncSelectStmt)
+
+	w.pos(stmt)
+	w.len(len(stmt.Body))
+	for i, clause := range stmt.Body {
+		if i > 0 {
+			w.closeScope(clause.Pos())
+		}
+		w.openScope(clause.Pos())
+
+		w.pos(clause)
+		w.stmt(clause.Comm)
+		w.stmts(clause.Body)
+	}
+	if len(stmt.Body) > 0 {
+		w.closeScope(stmt.Rbrace)
+	}
+}
+
+func (w *writer) switchStmt(stmt *syntax.SwitchStmt) {
+	w.sync(syncSwitchStmt)
+
+	w.openScope(stmt.Pos())
+	w.pos(stmt)
+	w.stmt(stmt.Init)
+
+	if guard, ok := stmt.Tag.(*syntax.TypeSwitchGuard); w.bool(ok) {
+		w.pos(guard)
+		if tag := guard.Lhs; w.bool(tag != nil) {
+			w.pos(tag)
+			w.string(tag.Value)
+		}
+		w.expr(guard.X)
+	} else {
+		w.expr(stmt.Tag)
+	}
+
+	w.len(len(stmt.Body))
+	for i, clause := range stmt.Body {
+		if i > 0 {
+			w.closeScope(clause.Pos())
+		}
+		w.openScope(clause.Pos())
+
+		w.pos(clause)
+		w.exprList(clause.Cases)
+
+		if obj, ok := w.p.info.Implicits[clause]; ok {
+			// TODO(mdempsky): These pos details are quirkish, but also
+			// necessary so the variable's position is correct for DWARF
+			// scope assignment later. It would probably be better for us to
+			// instead just set the variable's DWARF scoping info earlier so
+			// we can give it the correct position information.
+			pos := clause.Pos()
+			if typs := unpackListExpr(clause.Cases); len(typs) != 0 {
+				pos = typeExprEndPos(typs[len(typs)-1])
+			}
+			w.pos(pos)
+
+			obj := obj.(*types2.Var)
+			w.typ(obj.Type())
+			w.addLocal(obj)
+		}
+
+		w.stmts(clause.Body)
+	}
+	if len(stmt.Body) > 0 {
+		w.closeScope(stmt.Rbrace)
+	}
+
+	w.closeScope(stmt.Rbrace)
+}
+
+func (w *writer) label(label *syntax.Name) {
+	w.sync(syncLabel)
+
+	// TODO(mdempsky): Replace label strings with dense indices.
+	w.string(label.Value)
+}
+
+func (w *writer) optLabel(label *syntax.Name) {
+	w.sync(syncOptLabel)
+	if w.bool(label != nil) {
+		w.label(label)
+	}
+}
+
+// @@@ Expressions
+
+func (w *writer) expr(expr syntax.Expr) {
+	expr = unparen(expr) // skip parens; unneeded after typecheck
+
+	obj, targs := lookupObj(w.p.info, expr)
+
+	if tv, ok := w.p.info.Types[expr]; ok {
+		// TODO(mdempsky): Be more judicious about which types are marked as "needed".
+		w.needType(tv.Type)
+
+		if tv.IsType() {
+			w.code(exprType)
+			w.typ(tv.Type)
+			return
+		}
+
+		if tv.Value != nil {
+			pos := expr.Pos()
+			if quirksMode() {
+				if obj != nil {
+					// Quirk: IR (and thus iexport) doesn't track position
+					// information for uses of declared objects.
+					pos = syntax.Pos{}
+				} else if tv.Value.Kind() == constant.String {
+					// Quirk: noder.sum picks a particular position for certain
+					// string concatenations.
+					pos = sumPos(expr)
+				}
+			}
+
+			w.code(exprConst)
+			w.pos(pos)
+			w.value(tv.Type, tv.Value)
+
+			// TODO(mdempsky): These details are only important for backend
+			// diagnostics. Explore writing them out separately.
+			w.op(constExprOp(expr))
+			w.string(syntax.String(expr))
+			return
+		}
+	}
+
+	if obj != nil {
+		if isGlobal(obj) {
+			w.code(exprName)
+			w.obj(obj, targs)
+			return
+		}
+
+		obj := obj.(*types2.Var)
+		assert(len(targs) == 0)
+
+		w.code(exprLocal)
+		w.useLocal(expr.Pos(), obj)
+		return
+	}
+
+	switch expr := expr.(type) {
+	default:
+		w.p.unexpected("expression", expr)
+
+	case nil: // absent slice index, for condition, or switch tag
+		w.code(exprNone)
+
+	case *syntax.Name:
+		assert(expr.Value == "_")
+		w.code(exprBlank)
+
+	case *syntax.CompositeLit:
+		w.code(exprCompLit)
+		w.compLit(expr)
+
+	case *syntax.FuncLit:
+		w.code(exprFuncLit)
+		w.funcLit(expr)
+
+	case *syntax.SelectorExpr:
+		sel, ok := w.p.info.Selections[expr]
+		assert(ok)
+
+		w.code(exprSelector)
+		w.expr(expr.X)
+		w.pos(expr)
+		w.selector(sel.Obj())
+
+	case *syntax.IndexExpr:
+		tv, ok := w.p.info.Types[expr.Index]
+		assert(ok && tv.IsValue())
+
+		w.code(exprIndex)
+		w.expr(expr.X)
+		w.pos(expr)
+		w.expr(expr.Index)
+
+	case *syntax.SliceExpr:
+		w.code(exprSlice)
+		w.expr(expr.X)
+		w.pos(expr)
+		for _, n := range &expr.Index {
+			w.expr(n)
+		}
+
+	case *syntax.AssertExpr:
+		w.code(exprAssert)
+		w.expr(expr.X)
+		w.pos(expr)
+		w.expr(expr.Type)
+
+	case *syntax.Operation:
+		if expr.Y == nil {
+			w.code(exprUnaryOp)
+			w.op(unOps[expr.Op])
+			w.pos(expr)
+			w.expr(expr.X)
+			break
+		}
+
+		w.code(exprBinaryOp)
+		w.op(binOps[expr.Op])
+		w.expr(expr.X)
+		w.pos(expr)
+		w.expr(expr.Y)
+
+	case *syntax.CallExpr:
+		tv, ok := w.p.info.Types[expr.Fun]
+		assert(ok)
+		if tv.IsType() {
+			assert(len(expr.ArgList) == 1)
+			assert(!expr.HasDots)
+
+			w.code(exprConvert)
+			w.typ(tv.Type)
+			w.pos(expr)
+			w.expr(expr.ArgList[0])
+			break
+		}
+
+		writeFunExpr := func() {
+			if selector, ok := unparen(expr.Fun).(*syntax.SelectorExpr); ok {
+				if sel, ok := w.p.info.Selections[selector]; ok && sel.Kind() == types2.MethodVal {
+					w.expr(selector.X)
+					w.bool(true) // method call
+					w.pos(selector)
+					w.selector(sel.Obj())
+					return
+				}
+			}
+
+			if inf, ok := w.p.info.Inferred[expr]; ok {
+				obj, _ := lookupObj(w.p.info, expr.Fun)
+				assert(obj != nil)
+
+				// As if w.expr(expr.Fun), but using inf.TArgs instead.
+				w.code(exprName)
+				w.obj(obj, inf.TArgs)
+			} else {
+				w.expr(expr.Fun)
+			}
+			w.bool(false) // not a method call (i.e., normal function call)
+		}
+
+		w.code(exprCall)
+		writeFunExpr()
+		w.pos(expr)
+		w.exprs(expr.ArgList)
+		w.bool(expr.HasDots)
+	}
+}
+
+func (w *writer) compLit(lit *syntax.CompositeLit) {
+	tv, ok := w.p.info.Types[lit]
+	assert(ok)
+
+	w.sync(syncCompLit)
+	w.pos(lit)
+	w.typ(tv.Type)
+
+	typ := tv.Type
+	if ptr, ok := typ.Underlying().(*types2.Pointer); ok {
+		typ = ptr.Elem()
+	}
+	str, isStruct := typ.Underlying().(*types2.Struct)
+
+	w.len(len(lit.ElemList))
+	for i, elem := range lit.ElemList {
+		if isStruct {
+			if kv, ok := elem.(*syntax.KeyValueExpr); ok {
+				// use position of expr.Key rather than of elem (which has position of ':')
+				w.pos(kv.Key)
+				w.len(fieldIndex(w.p.info, str, kv.Key.(*syntax.Name)))
+				elem = kv.Value
+			} else {
+				w.pos(elem)
+				w.len(i)
+			}
+		} else {
+			if kv, ok := elem.(*syntax.KeyValueExpr); w.bool(ok) {
+				// use position of expr.Key rather than of elem (which has position of ':')
+				w.pos(kv.Key)
+				w.expr(kv.Key)
+				elem = kv.Value
+			}
+		}
+		w.pos(elem)
+		w.expr(elem)
+	}
+}
+
+func (w *writer) funcLit(expr *syntax.FuncLit) {
+	tv, ok := w.p.info.Types[expr]
+	assert(ok)
+	sig := tv.Type.(*types2.Signature)
+
+	body, closureVars := w.p.bodyIdx(w.p.curpkg, sig, expr.Body, w.dict)
+
+	w.sync(syncFuncLit)
+	w.pos(expr)
+	w.pos(expr.Type) // for QuirksMode
+	w.signature(sig)
+
+	w.len(len(closureVars))
+	for _, cv := range closureVars {
+		w.pos(cv.pos)
+		if quirksMode() {
+			cv.pos = expr.Body.Rbrace
+		}
+		w.useLocal(cv.pos, cv.obj)
+	}
+
+	w.reloc(relocBody, body)
+}
+
+type posObj struct {
+	pos syntax.Pos
+	obj *types2.Var
+}
+
+func (w *writer) exprList(expr syntax.Expr) {
+	w.sync(syncExprList)
+	w.exprs(unpackListExpr(expr))
+}
+
+func (w *writer) exprs(exprs []syntax.Expr) {
+	if len(exprs) == 0 {
+		assert(exprs == nil)
+	}
+
+	w.sync(syncExprs)
+	w.len(len(exprs))
+	for _, expr := range exprs {
+		w.expr(expr)
+	}
+}
+
+func (w *writer) op(op ir.Op) {
+	// TODO(mdempsky): Remove in favor of explicit codes? Would make
+	// export data more stable against internal refactorings, but low
+	// priority at the moment.
+	assert(op != 0)
+	w.sync(syncOp)
+	w.len(int(op))
+}
+
+func (w *writer) needType(typ types2.Type) {
+	// Decompose tuple into component element types.
+	if typ, ok := typ.(*types2.Tuple); ok {
+		for i := 0; i < typ.Len(); i++ {
+			w.needType(typ.At(i).Type())
+		}
+		return
+	}
+
+	if info := w.p.typIdx(typ, w.dict); info.derived {
+		w.dict.derived[info.idx].needed = true
+	}
+}
+
+// @@@ Package initialization
+
+// Caution: This code is still clumsy, because toolstash -cmp is
+// particularly sensitive to it.
+
+type typeDeclGen struct {
+	*syntax.TypeDecl
+	gen int
+
+	// Implicit type parameters in scope at this type declaration.
+	implicits []*types2.TypeName
+}
+
+type fileImports struct {
+	importedEmbed, importedUnsafe bool
+}
+
+type declCollector struct {
+	pw         *pkgWriter
+	typegen    *int
+	file       *fileImports
+	withinFunc bool
+	implicits  []*types2.TypeName
+}
+
+func (c *declCollector) withTParams(obj types2.Object) *declCollector {
+	tparams := objTypeParams(obj)
+	n := tparams.Len()
+	if n == 0 {
+		return c
+	}
+
+	copy := *c
+	copy.implicits = copy.implicits[:len(copy.implicits):len(copy.implicits)]
+	for i := 0; i < n; i++ {
+		copy.implicits = append(copy.implicits, tparams.At(i))
+	}
+	return &copy
+}
+
+func (c *declCollector) Visit(n syntax.Node) syntax.Visitor {
+	pw := c.pw
+
+	switch n := n.(type) {
+	case *syntax.File:
+		pw.checkPragmas(n.Pragma, ir.GoBuildPragma, false)
+
+	case *syntax.ImportDecl:
+		pw.checkPragmas(n.Pragma, 0, false)
+
+		switch pkgNameOf(pw.info, n).Imported().Path() {
+		case "embed":
+			c.file.importedEmbed = true
+		case "unsafe":
+			c.file.importedUnsafe = true
+		}
+
+	case *syntax.ConstDecl:
+		pw.checkPragmas(n.Pragma, 0, false)
+
+	case *syntax.FuncDecl:
+		pw.checkPragmas(n.Pragma, funcPragmas, false)
+
+		obj := pw.info.Defs[n.Name].(*types2.Func)
+		pw.funDecls[obj] = n
+
+		return c.withTParams(obj)
+
+	case *syntax.TypeDecl:
+		obj := pw.info.Defs[n.Name].(*types2.TypeName)
+		d := typeDeclGen{TypeDecl: n, implicits: c.implicits}
+
+		if n.Alias {
+			pw.checkPragmas(n.Pragma, 0, false)
+		} else {
+			pw.checkPragmas(n.Pragma, typePragmas, false)
+
+			// Assign a unique ID to function-scoped defined types.
+			if c.withinFunc {
+				*c.typegen++
+				d.gen = *c.typegen
+			}
+		}
+
+		pw.typDecls[obj] = d
+
+		// TODO(mdempsky): Omit? Not strictly necessary; only matters for
+		// type declarations within function literals within parameterized
+		// type declarations, but types2 the function literals will be
+		// constant folded away.
+		return c.withTParams(obj)
+
+	case *syntax.VarDecl:
+		pw.checkPragmas(n.Pragma, 0, true)
+
+		if p, ok := n.Pragma.(*pragmas); ok && len(p.Embeds) > 0 {
+			if err := checkEmbed(n, c.file.importedEmbed, c.withinFunc); err != nil {
+				pw.errorf(p.Embeds[0].Pos, "%s", err)
+			}
+		}
+
+		// Workaround for #46208. For variable declarations that
+		// declare multiple variables and have an explicit type
+		// expression, the type expression is evaluated multiple
+		// times. This affects toolstash -cmp, because iexport is
+		// sensitive to *types.Type pointer identity.
+		if quirksMode() && n.Type != nil {
+			tv, ok := pw.info.Types[n.Type]
+			assert(ok)
+			assert(tv.IsType())
+			for _, name := range n.NameList {
+				obj := pw.info.Defs[name].(*types2.Var)
+				pw.dups.add(obj.Type(), tv.Type)
+			}
+		}
+
+	case *syntax.BlockStmt:
+		if !c.withinFunc {
+			copy := *c
+			copy.withinFunc = true
+			return &copy
+		}
+	}
+
+	return c
+}
+
+func (pw *pkgWriter) collectDecls(noders []*noder) {
+	var typegen int
+	for _, p := range noders {
+		var file fileImports
+
+		syntax.Walk(p.file, &declCollector{
+			pw:      pw,
+			typegen: &typegen,
+			file:    &file,
+		})
+
+		pw.cgoPragmas = append(pw.cgoPragmas, p.pragcgobuf...)
+
+		for _, l := range p.linknames {
+			if !file.importedUnsafe {
+				pw.errorf(l.pos, "//go:linkname only allowed in Go files that import \"unsafe\"")
+				continue
+			}
+
+			switch obj := pw.curpkg.Scope().Lookup(l.local).(type) {
+			case *types2.Func, *types2.Var:
+				if _, ok := pw.linknames[obj]; !ok {
+					pw.linknames[obj] = l.remote
+				} else {
+					pw.errorf(l.pos, "duplicate //go:linkname for %s", l.local)
+				}
+
+			default:
+				// TODO(mdempsky): Enable after #42938 is fixed.
+				if false {
+					pw.errorf(l.pos, "//go:linkname must refer to declared function or variable")
+				}
+			}
+		}
+	}
+}
+
+func (pw *pkgWriter) checkPragmas(p syntax.Pragma, allowed ir.PragmaFlag, embedOK bool) {
+	if p == nil {
+		return
+	}
+	pragma := p.(*pragmas)
+
+	for _, pos := range pragma.Pos {
+		if pos.Flag&^allowed != 0 {
+			pw.errorf(pos.Pos, "misplaced compiler directive")
+		}
+	}
+
+	if !embedOK {
+		for _, e := range pragma.Embeds {
+			pw.errorf(e.Pos, "misplaced go:embed directive")
+		}
+	}
+}
+
+func (w *writer) pkgInit(noders []*noder) {
+	if quirksMode() {
+		posBases := posBasesOf(noders)
+		w.len(len(posBases))
+		for _, posBase := range posBases {
+			w.posBase(posBase)
+		}
+
+		objs := importedObjsOf(w.p.curpkg, w.p.info, noders)
+		w.len(len(objs))
+		for _, obj := range objs {
+			w.qualifiedIdent(obj)
+		}
+	}
+
+	w.len(len(w.p.cgoPragmas))
+	for _, cgoPragma := range w.p.cgoPragmas {
+		w.strings(cgoPragma)
+	}
+
+	w.sync(syncDecls)
+	for _, p := range noders {
+		for _, decl := range p.file.DeclList {
+			w.pkgDecl(decl)
+		}
+	}
+	w.code(declEnd)
+
+	w.sync(syncEOF)
+}
+
+func (w *writer) pkgDecl(decl syntax.Decl) {
+	switch decl := decl.(type) {
+	default:
+		w.p.unexpected("declaration", decl)
+
+	case *syntax.ImportDecl:
+
+	case *syntax.ConstDecl:
+		w.code(declOther)
+		w.pkgObjs(decl.NameList...)
+
+	case *syntax.FuncDecl:
+		if decl.Name.Value == "_" {
+			break // skip blank functions
+		}
+
+		obj := w.p.info.Defs[decl.Name].(*types2.Func)
+		sig := obj.Type().(*types2.Signature)
+
+		if sig.RParams() != nil || sig.TParams() != nil {
+			break // skip generic functions
+		}
+
+		if recv := sig.Recv(); recv != nil {
+			w.code(declMethod)
+			w.typ(recvBase(recv))
+			w.selector(obj)
+			break
+		}
+
+		w.code(declFunc)
+		w.pkgObjs(decl.Name)
+
+	case *syntax.TypeDecl:
+		if len(decl.TParamList) != 0 {
+			break // skip generic type decls
+		}
+
+		if decl.Name.Value == "_" {
+			break // skip blank type decls
+		}
+
+		name := w.p.info.Defs[decl.Name].(*types2.TypeName)
+		// Skip type declarations for interfaces that are only usable as
+		// type parameter bounds.
+		if iface, ok := name.Type().Underlying().(*types2.Interface); ok && iface.IsConstraint() {
+			break
+		}
+
+		// Skip aliases to uninstantiated generic types.
+		// TODO(mdempsky): Revisit after #46477 is resolved.
+		if name.IsAlias() {
+			named, ok := name.Type().(*types2.Named)
+			if ok && named.TParams().Len() != 0 && len(named.TArgs()) == 0 {
+				break
+			}
+		}
+
+		w.code(declOther)
+		w.pkgObjs(decl.Name)
+
+	case *syntax.VarDecl:
+		w.code(declVar)
+		w.pos(decl)
+		w.pkgObjs(decl.NameList...)
+		w.exprList(decl.Values)
+
+		var embeds []pragmaEmbed
+		if p, ok := decl.Pragma.(*pragmas); ok {
+			embeds = p.Embeds
+		}
+		w.len(len(embeds))
+		for _, embed := range embeds {
+			w.pos(embed.Pos)
+			w.strings(embed.Patterns)
+		}
+	}
+}
+
+func (w *writer) pkgObjs(names ...*syntax.Name) {
+	w.sync(syncDeclNames)
+	w.len(len(names))
+
+	for _, name := range names {
+		obj, ok := w.p.info.Defs[name]
+		assert(ok)
+
+		w.sync(syncDeclName)
+		w.obj(obj, nil)
+	}
+}
+
+// @@@ Helpers
+
+// isDefinedType reports whether obj is a defined type.
+func isDefinedType(obj types2.Object) bool {
+	if obj, ok := obj.(*types2.TypeName); ok {
+		return !obj.IsAlias()
+	}
+	return false
+}
+
+// isGlobal reports whether obj was declared at package scope.
+//
+// Caveat: blank objects are not declared.
+func isGlobal(obj types2.Object) bool {
+	return obj.Parent() == obj.Pkg().Scope()
+}
+
+// lookupObj returns the object that expr refers to, if any. If expr
+// is an explicit instantiation of a generic object, then the type
+// arguments are returned as well.
+func lookupObj(info *types2.Info, expr syntax.Expr) (obj types2.Object, targs []types2.Type) {
+	if index, ok := expr.(*syntax.IndexExpr); ok {
+		if inf, ok := info.Inferred[index]; ok {
+			targs = inf.TArgs
+		} else {
+			args := unpackListExpr(index.Index)
+
+			if len(args) == 1 {
+				tv, ok := info.Types[args[0]]
+				assert(ok)
+				if tv.IsValue() {
+					return // normal index expression
+				}
+			}
+
+			targs = make([]types2.Type, len(args))
+			for i, arg := range args {
+				tv, ok := info.Types[arg]
+				assert(ok)
+				assert(tv.IsType())
+				targs[i] = tv.Type
+			}
+		}
+
+		expr = index.X
+	}
+
+	// Strip package qualifier, if present.
+	if sel, ok := expr.(*syntax.SelectorExpr); ok {
+		if !isPkgQual(info, sel) {
+			return // normal selector expression
+		}
+		expr = sel.Sel
+	}
+
+	if name, ok := expr.(*syntax.Name); ok {
+		obj, _ = info.Uses[name]
+	}
+	return
+}
+
+// isPkgQual reports whether the given selector expression is a
+// package-qualified identifier.
+func isPkgQual(info *types2.Info, sel *syntax.SelectorExpr) bool {
+	if name, ok := sel.X.(*syntax.Name); ok {
+		_, isPkgName := info.Uses[name].(*types2.PkgName)
+		return isPkgName
+	}
+	return false
+}
+
+// recvBase returns the base type for the given receiver parameter.
+func recvBase(recv *types2.Var) *types2.Named {
+	typ := recv.Type()
+	if ptr, ok := typ.(*types2.Pointer); ok {
+		typ = ptr.Elem()
+	}
+	return typ.(*types2.Named)
+}
+
+// namesAsExpr returns a list of names as a syntax.Expr.
+func namesAsExpr(names []*syntax.Name) syntax.Expr {
+	if len(names) == 1 {
+		return names[0]
+	}
+
+	exprs := make([]syntax.Expr, len(names))
+	for i, name := range names {
+		exprs[i] = name
+	}
+	return &syntax.ListExpr{ElemList: exprs}
+}
+
+// fieldIndex returns the index of the struct field named by key.
+func fieldIndex(info *types2.Info, str *types2.Struct, key *syntax.Name) int {
+	field := info.Uses[key].(*types2.Var)
+
+	for i := 0; i < str.NumFields(); i++ {
+		if str.Field(i) == field {
+			return i
+		}
+	}
+
+	panic(fmt.Sprintf("%s: %v is not a field of %v", key.Pos(), field, str))
+}
+
+// objTypeParams returns the type parameters on the given object.
+func objTypeParams(obj types2.Object) *types2.TypeParams {
+	switch obj := obj.(type) {
+	case *types2.Func:
+		sig := obj.Type().(*types2.Signature)
+		if sig.Recv() != nil {
+			return sig.RParams()
+		}
+		return sig.TParams()
+	case *types2.TypeName:
+		if !obj.IsAlias() {
+			return obj.Type().(*types2.Named).TParams()
+		}
+	}
+	return nil
+}
+
+func asPragmaFlag(p syntax.Pragma) ir.PragmaFlag {
+	if p == nil {
+		return 0
+	}
+	return p.(*pragmas).Flag
+}
diff --git a/src/cmd/compile/internal/pkginit/initorder.go b/src/cmd/compile/internal/pkginit/initorder.go
index 97d6962..0aad63a 100644
--- a/src/cmd/compile/internal/pkginit/initorder.go
+++ b/src/cmd/compile/internal/pkginit/initorder.go
@@ -304,7 +304,7 @@
 		n := n.(*ir.ClosureExpr)
 		d.inspectList(n.Func.Body)
 
-	case ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
+	case ir.ODOTMETH, ir.OMETHVALUE, ir.OMETHEXPR:
 		d.foundDep(ir.MethodExprName(n))
 	}
 }
diff --git a/src/cmd/compile/internal/ppc64/galign.go b/src/cmd/compile/internal/ppc64/galign.go
index 590290f..bff3e38 100644
--- a/src/cmd/compile/internal/ppc64/galign.go
+++ b/src/cmd/compile/internal/ppc64/galign.go
@@ -20,7 +20,6 @@
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnopdefer
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/ppc64/ggen.go b/src/cmd/compile/internal/ppc64/ggen.go
index c76962c..3ae6422 100644
--- a/src/cmd/compile/internal/ppc64/ggen.go
+++ b/src/cmd/compile/internal/ppc64/ggen.go
@@ -53,30 +53,3 @@
 	p.To.Reg = ppc64.REG_R0
 	return p
 }
-
-func ginsnopdefer(pp *objw.Progs) *obj.Prog {
-	// On PPC64 two nops are required in the defer case.
-	//
-	// (see gc/cgen.go, gc/plive.go -- copy of comment below)
-	//
-	// On ppc64, when compiling Go into position
-	// independent code on ppc64le we insert an
-	// instruction to reload the TOC pointer from the
-	// stack as well. See the long comment near
-	// jmpdefer in runtime/asm_ppc64.s for why.
-	// If the MOVD is not needed, insert a hardware NOP
-	// so that the same number of instructions are used
-	// on ppc64 in both shared and non-shared modes.
-
-	ginsnop(pp)
-	if base.Ctxt.Flag_shared {
-		p := pp.Prog(ppc64.AMOVD)
-		p.From.Type = obj.TYPE_MEM
-		p.From.Offset = 24
-		p.From.Reg = ppc64.REGSP
-		p.To.Type = obj.TYPE_REG
-		p.To.Reg = ppc64.REG_R2
-		return p
-	}
-	return ginsnop(pp)
-}
diff --git a/src/cmd/compile/internal/reflectdata/alg.go b/src/cmd/compile/internal/reflectdata/alg.go
index 0707e0b..36ad389 100644
--- a/src/cmd/compile/internal/reflectdata/alg.go
+++ b/src/cmd/compile/internal/reflectdata/alg.go
@@ -679,8 +679,7 @@
 
 	fn := typecheck.LookupRuntime("memequal")
 	fn = typecheck.SubstArgTypes(fn, types.Types[types.TUINT8], types.Types[types.TUINT8])
-	call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, []ir.Node{sptr, tptr, ir.Copy(slen)})
-	typecheck.Call(call)
+	call := typecheck.Call(base.Pos, fn, []ir.Node{sptr, tptr, ir.Copy(slen)}, false).(*ir.CallExpr)
 
 	cmp := ir.NewBinaryExpr(base.Pos, ir.OEQ, slen, tlen)
 	cmp = typecheck.Expr(cmp).(*ir.BinaryExpr)
@@ -716,8 +715,7 @@
 	sdata.SetTypecheck(1)
 	tdata.SetTypecheck(1)
 
-	call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, []ir.Node{stab, sdata, tdata})
-	typecheck.Call(call)
+	call := typecheck.Call(base.Pos, fn, []ir.Node{stab, sdata, tdata}, false).(*ir.CallExpr)
 
 	cmp := ir.NewBinaryExpr(base.Pos, ir.OEQ, stab, ttab)
 	cmp = typecheck.Expr(cmp).(*ir.BinaryExpr)
diff --git a/src/cmd/compile/internal/reflectdata/reflect.go b/src/cmd/compile/internal/reflectdata/reflect.go
index eb9a8a6..b04e4d6 100644
--- a/src/cmd/compile/internal/reflectdata/reflect.go
+++ b/src/cmd/compile/internal/reflectdata/reflect.go
@@ -28,23 +28,13 @@
 	"cmd/internal/src"
 )
 
-type itabEntry struct {
-	t, itype *types.Type
-	lsym     *obj.LSym // symbol of the itab itself
-
-	// symbols of each method in
-	// the itab, sorted by byte offset;
-	// filled in by CompileITabs
-	entries []*obj.LSym
-}
-
 type ptabEntry struct {
 	s *types.Sym
 	t *types.Type
 }
 
-func CountTabs() (numPTabs, numITabs int) {
-	return len(ptabs), len(itabs)
+func CountPTabs() int {
+	return len(ptabs)
 }
 
 // runtime interface and reflection data structures
@@ -56,7 +46,6 @@
 	gcsymmu  sync.Mutex // protects gcsymset and gcsymslice
 	gcsymset = make(map[*types.Type]struct{})
 
-	itabs []itabEntry
 	ptabs []*ir.Name
 )
 
@@ -313,6 +302,10 @@
 // methods returns the methods of the non-interface type t, sorted by name.
 // Generates stub functions as needed.
 func methods(t *types.Type) []*typeSig {
+	if t.HasShape() {
+		// Shape types have no methods.
+		return nil
+	}
 	// method type
 	mt := types.ReceiverBaseType(t)
 
@@ -321,13 +314,6 @@
 	}
 	typecheck.CalcMethods(mt)
 
-	// type stored in interface word
-	it := t
-
-	if !types.IsDirectIface(it) {
-		it = types.NewPtr(t)
-	}
-
 	// make list of methods for t,
 	// generating code if necessary.
 	var ms []*typeSig
@@ -355,8 +341,8 @@
 
 		sig := &typeSig{
 			name:  f.Sym,
-			isym:  methodWrapper(it, f),
-			tsym:  methodWrapper(t, f),
+			isym:  methodWrapper(t, f, true),
+			tsym:  methodWrapper(t, f, false),
 			type_: typecheck.NewMethodType(f.Type, t),
 			mtype: typecheck.NewMethodType(f.Type, nil),
 		}
@@ -394,7 +380,7 @@
 		// IfaceType.Method is not in the reflect data.
 		// Generate the method body, so that compiled
 		// code can refer to it.
-		methodWrapper(t, f)
+		methodWrapper(t, f, false)
 	}
 
 	return methods
@@ -735,7 +721,7 @@
 	}
 
 	exported := false
-	p := t.LongString()
+	p := t.NameString()
 	// If we're writing out type T,
 	// we are very likely to write out type *T as well.
 	// Use the string "*T"[1:] for "T", so that the two
@@ -799,11 +785,11 @@
 // TrackSym returns the symbol for tracking use of field/method f, assumed
 // to be a member of struct/interface type t.
 func TrackSym(t *types.Type, f *types.Field) *obj.LSym {
-	return base.PkgLinksym("go.track", t.ShortString()+"."+f.Sym.Name, obj.ABI0)
+	return base.PkgLinksym("go.track", t.LinkString()+"."+f.Sym.Name, obj.ABI0)
 }
 
 func TypeSymPrefix(prefix string, t *types.Type) *types.Sym {
-	p := prefix + "." + t.ShortString()
+	p := prefix + "." + t.LinkString()
 	s := types.TypeSymLookup(p)
 
 	// This function is for looking up type-related generated functions
@@ -848,16 +834,28 @@
 	return typecheck.Expr(typecheck.NodAddr(n)).(*ir.AddrExpr)
 }
 
-func ITabAddr(t, itype *types.Type) *ir.AddrExpr {
-	if t == nil || (t.IsPtr() && t.Elem() == nil) || t.IsUntyped() || !itype.IsInterface() || itype.IsEmptyInterface() {
-		base.Fatalf("ITabAddr(%v, %v)", t, itype)
-	}
-	s, existed := ir.Pkgs.Itab.LookupOK(t.ShortString() + "," + itype.ShortString())
+// ITabLsym returns the LSym representing the itab for concreate type typ
+// implementing interface iface.
+func ITabLsym(typ, iface *types.Type) *obj.LSym {
+	s, existed := ir.Pkgs.Itab.LookupOK(typ.LinkString() + "," + iface.LinkString())
+	lsym := s.Linksym()
+
 	if !existed {
-		itabs = append(itabs, itabEntry{t: t, itype: itype, lsym: s.Linksym()})
+		writeITab(lsym, typ, iface)
+	}
+	return lsym
+}
+
+// ITabAddr returns an expression representing a pointer to the itab
+// for concrete type typ implementing interface iface.
+func ITabAddr(typ, iface *types.Type) *ir.AddrExpr {
+	s, existed := ir.Pkgs.Itab.LookupOK(typ.LinkString() + "," + iface.LinkString())
+	lsym := s.Linksym()
+
+	if !existed {
+		writeITab(lsym, typ, iface)
 	}
 
-	lsym := s.Linksym()
 	n := ir.NewLinksymExpr(base.Pos, lsym, types.Types[types.TUINT8])
 	return typecheck.Expr(typecheck.NodAddr(n)).(*ir.AddrExpr)
 }
@@ -945,25 +943,27 @@
 	if t.IsPtr() && t.Sym() == nil && t.Elem().Sym() != nil {
 		tbase = t.Elem()
 	}
+	if tbase.Kind() == types.TFORW {
+		base.Fatalf("unresolved defined type: %v", tbase)
+	}
+
 	dupok := 0
-	if tbase.Sym() == nil {
+	if tbase.Sym() == nil || tbase.HasShape() { // TODO(mdempsky): Probably need DUPOK for instantiated types too.
 		dupok = obj.DUPOK
 	}
 
-	if base.Ctxt.Pkgpath != "runtime" || (tbase != types.Types[tbase.Kind()] && tbase != types.ByteType && tbase != types.RuneType && tbase != types.ErrorType) { // int, float, etc
-		// named types from other files are defined only by those files
-		if tbase.Sym() != nil && tbase.Sym().Pkg != types.LocalPkg {
-			if i := typecheck.BaseTypeIndex(t); i >= 0 {
-				lsym.Pkg = tbase.Sym().Pkg.Prefix
-				lsym.SymIdx = int32(i)
-				lsym.Set(obj.AttrIndexed, true)
-			}
-			return lsym
+	if !NeedEmit(tbase) {
+		if i := typecheck.BaseTypeIndex(t); i >= 0 {
+			lsym.Pkg = tbase.Sym().Pkg.Prefix
+			lsym.SymIdx = int32(i)
+			lsym.Set(obj.AttrIndexed, true)
 		}
-		// TODO(mdempsky): Investigate whether this can happen.
-		if tbase.Kind() == types.TFORW {
-			return lsym
-		}
+
+		// TODO(mdempsky): Investigate whether this still happens.
+		// If we know we don't need to emit code for a type,
+		// we should have a link-symbol index for it.
+		// See also TODO in NeedEmit.
+		return lsym
 	}
 
 	ot := 0
@@ -1226,88 +1226,11 @@
 	return int64(commonSize()+4*types.PtrSize+uncommonSize(ityp)) + i*8
 }
 
-// for each itabEntry, gather the methods on
-// the concrete type that implement the interface
-func CompileITabs() {
-	for i := range itabs {
-		tab := &itabs[i]
-		methods := genfun(tab.t, tab.itype)
-		if len(methods) == 0 {
-			continue
-		}
-		tab.entries = methods
-	}
-}
-
-// for the given concrete type and interface
-// type, return the (sorted) set of methods
-// on the concrete type that implement the interface
-func genfun(t, it *types.Type) []*obj.LSym {
-	if t == nil || it == nil {
-		return nil
-	}
-	sigs := imethods(it)
-	methods := methods(t)
-	out := make([]*obj.LSym, 0, len(sigs))
-	// TODO(mdempsky): Short circuit before calling methods(t)?
-	// See discussion on CL 105039.
-	if len(sigs) == 0 {
-		return nil
-	}
-
-	// both sigs and methods are sorted by name,
-	// so we can find the intersect in a single pass
-	for _, m := range methods {
-		if m.name == sigs[0].name {
-			out = append(out, m.isym)
-			sigs = sigs[1:]
-			if len(sigs) == 0 {
-				break
-			}
-		}
-	}
-
-	if len(sigs) != 0 {
-		base.Fatalf("incomplete itab")
-	}
-
-	return out
-}
-
-// ITabSym uses the information gathered in
-// CompileITabs to de-virtualize interface methods.
-// Since this is called by the SSA backend, it shouldn't
-// generate additional Nodes, Syms, etc.
-func ITabSym(it *obj.LSym, offset int64) *obj.LSym {
-	var syms []*obj.LSym
-	if it == nil {
-		return nil
-	}
-
-	for i := range itabs {
-		e := &itabs[i]
-		if e.lsym == it {
-			syms = e.entries
-			break
-		}
-	}
-	if syms == nil {
-		return nil
-	}
-
-	// keep this arithmetic in sync with *itab layout
-	methodnum := int((offset - 2*int64(types.PtrSize) - 8) / int64(types.PtrSize))
-	if methodnum >= len(syms) {
-		return nil
-	}
-	return syms[methodnum]
-}
-
 // NeedRuntimeType ensures that a runtime type descriptor is emitted for t.
 func NeedRuntimeType(t *types.Type) {
 	if t.HasTParam() {
-		// Generic types don't have a runtime type descriptor (but will
-		// have a dictionary)
+		// Generic types don't really exist at run-time and have no runtime
+		// type descriptor.  But we do write out shape types.
 		return
 	}
 	if _, ok := signatset[t]; !ok {
@@ -1349,29 +1272,66 @@
 	}
 }
 
-func WriteTabs() {
-	// process itabs
-	for _, i := range itabs {
-		// dump empty itab symbol into i.sym
-		// type itab struct {
-		//   inter  *interfacetype
-		//   _type  *_type
-		//   hash   uint32
-		//   _      [4]byte
-		//   fun    [1]uintptr // variable sized
-		// }
-		o := objw.SymPtr(i.lsym, 0, writeType(i.itype), 0)
-		o = objw.SymPtr(i.lsym, o, writeType(i.t), 0)
-		o = objw.Uint32(i.lsym, o, types.TypeHash(i.t)) // copy of type hash
-		o += 4                                          // skip unused field
-		for _, fn := range genfun(i.t, i.itype) {
-			o = objw.SymPtrWeak(i.lsym, o, fn, 0) // method pointer for each method
-		}
-		// Nothing writes static itabs, so they are read only.
-		objw.Global(i.lsym, int32(o), int16(obj.DUPOK|obj.RODATA))
-		i.lsym.Set(obj.AttrContentAddressable, true)
+// writeITab writes the itab for concrete type typ implementing
+// interface iface.
+func writeITab(lsym *obj.LSym, typ, iface *types.Type) {
+	// TODO(mdempsky): Fix methodWrapper, geneq, and genhash (and maybe
+	// others) to stop clobbering these.
+	oldpos, oldfn := base.Pos, ir.CurFunc
+	defer func() { base.Pos, ir.CurFunc = oldpos, oldfn }()
+
+	if typ == nil || (typ.IsPtr() && typ.Elem() == nil) || typ.IsUntyped() || iface == nil || !iface.IsInterface() || iface.IsEmptyInterface() {
+		base.Fatalf("writeITab(%v, %v)", typ, iface)
 	}
 
+	sigs := iface.AllMethods().Slice()
+	entries := make([]*obj.LSym, 0, len(sigs))
+
+	// both sigs and methods are sorted by name,
+	// so we can find the intersection in a single pass
+	for _, m := range methods(typ) {
+		if m.name == sigs[0].Sym {
+			entries = append(entries, m.isym)
+			if m.isym == nil {
+				panic("NO ISYM")
+			}
+			sigs = sigs[1:]
+			if len(sigs) == 0 {
+				break
+			}
+		}
+		if sigs[0].Sym.Name == "==" {
+			sigs = sigs[1:]
+			if len(sigs) == 0 {
+				break
+			}
+		}
+	}
+	if len(sigs) != 0 {
+		base.Fatalf("incomplete itab")
+	}
+
+	// dump empty itab symbol into i.sym
+	// type itab struct {
+	//   inter  *interfacetype
+	//   _type  *_type
+	//   hash   uint32
+	//   _      [4]byte
+	//   fun    [1]uintptr // variable sized
+	// }
+	o := objw.SymPtr(lsym, 0, writeType(iface), 0)
+	o = objw.SymPtr(lsym, o, writeType(typ), 0)
+	o = objw.Uint32(lsym, o, types.TypeHash(typ)) // copy of type hash
+	o += 4                                        // skip unused field
+	for _, fn := range entries {
+		o = objw.SymPtrWeak(lsym, o, fn, 0) // method pointer for each method
+	}
+	// Nothing writes static itabs, so they are read only.
+	objw.Global(lsym, int32(o), int16(obj.DUPOK|obj.RODATA))
+	lsym.Set(obj.AttrContentAddressable, true)
+}
+
+func WriteTabs() {
 	// process ptabs
 	if types.LocalPkg.Name == "main" && len(ptabs) > 0 {
 		ot := 0
@@ -1453,7 +1413,7 @@
 
 type typeAndStr struct {
 	t       *types.Type
-	short   string
+	short   string // "short" here means NameString
 	regular string
 }
 
@@ -1466,8 +1426,13 @@
 	}
 	// When the only difference between the types is whether
 	// they refer to byte or uint8, such as **byte vs **uint8,
-	// the types' ShortStrings can be identical.
+	// the types' NameStrings can be identical.
 	// To preserve deterministic sort ordering, sort these by String().
+	//
+	// TODO(mdempsky): This all seems suspect. Using LinkString would
+	// avoid naming collisions, and there shouldn't be a reason to care
+	// about "byte" vs "uint8": they share the same runtime type
+	// descriptor anyway.
 	if a[i].regular != a[j].regular {
 		return a[i].regular < a[j].regular
 	}
@@ -1741,6 +1706,49 @@
 	}
 }
 
+// NeedEmit reports whether typ is a type that we need to emit code
+// for (e.g., runtime type descriptors, method wrappers).
+func NeedEmit(typ *types.Type) bool {
+	// TODO(mdempsky): Export data should keep track of which anonymous
+	// and instantiated types were emitted, so at least downstream
+	// packages can skip re-emitting them.
+	//
+	// Perhaps we can just generalize the linker-symbol indexing to
+	// track the index of arbitrary types, not just defined types, and
+	// use its presence to detect this. The same idea would work for
+	// instantiated generic functions too.
+
+	switch sym := typ.Sym(); {
+	case sym == nil:
+		// Anonymous type; possibly never seen before or ever again.
+		// Need to emit to be safe (however, see TODO above).
+		return true
+
+	case sym.Pkg == types.LocalPkg:
+		// Local defined type; our responsibility.
+		return true
+
+	case base.Ctxt.Pkgpath == "runtime" && (sym.Pkg == types.BuiltinPkg || sym.Pkg == ir.Pkgs.Unsafe):
+		// Package runtime is responsible for including code for builtin
+		// types (predeclared and package unsafe).
+		return true
+
+	case typ.IsFullyInstantiated():
+		// Instantiated type; possibly instantiated with unique type arguments.
+		// Need to emit to be safe (however, see TODO above).
+		return true
+
+	case typ.HasShape():
+		// Shape type; need to emit even though it lives in the .shape package.
+		// TODO: make sure the linker deduplicates them (see dupok in writeType above).
+		return true
+
+	default:
+		// Should have been emitted by an imported package.
+		return false
+	}
+}
+
 // Generate a wrapper function to convert from
 // a receiver of type T to a receiver of type U.
 // That is,
@@ -1761,7 +1769,45 @@
 //
 //	rcvr - U
 //	method - M func (t T)(), a TFIELD type struct
-func methodWrapper(rcvr *types.Type, method *types.Field) *obj.LSym {
+//
+// Also wraps methods on instantiated generic types for use in itab entries.
+// For an instantiated generic type G[int], we generate wrappers like:
+// G[int] pointer shaped:
+//	func (x G[int]) f(arg) {
+//		.inst.G[int].f(dictionary, x, arg)
+// 	}
+// G[int] not pointer shaped:
+//	func (x *G[int]) f(arg) {
+//		.inst.G[int].f(dictionary, *x, arg)
+// 	}
+// These wrappers are always fully stenciled.
+func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSym {
+	orig := rcvr
+	if forItab && !types.IsDirectIface(rcvr) {
+		rcvr = rcvr.PtrTo()
+	}
+
+	generic := false
+	// We don't need a dictionary if we are reaching a method (possibly via an
+	// embedded field) which is an interface method.
+	if !types.IsInterfaceMethod(method.Type) {
+		rcvr1 := rcvr
+		if rcvr1.IsPtr() {
+			rcvr1 = rcvr.Elem()
+		}
+		if len(rcvr1.RParams()) > 0 {
+			// If rcvr has rparams, remember method as generic, which
+			// means we need to add a dictionary to the wrapper.
+			generic = true
+			targs := rcvr1.RParams()
+			for _, t := range targs {
+				if t.HasShape() {
+					base.Fatalf("method on type instantiated with shapes targ:%+v rcvr:%+v", t, rcvr)
+				}
+			}
+		}
+	}
+
 	newnam := ir.MethodSym(rcvr, method.Sym)
 	lsym := newnam.Linksym()
 	if newnam.Siggen() {
@@ -1769,19 +1815,18 @@
 	}
 	newnam.SetSiggen(true)
 
-	if types.Identical(rcvr, method.Type.Recv().Type) {
+	// Except in quirks mode, unified IR creates its own wrappers.
+	if base.Debug.Unified != 0 && base.Debug.UnifiedQuirks == 0 {
 		return lsym
 	}
 
-	// Only generate (*T).M wrappers for T.M in T's own package.
-	if rcvr.IsPtr() && rcvr.Elem() == method.Type.Recv().Type &&
-		rcvr.Elem().Sym() != nil && rcvr.Elem().Sym().Pkg != types.LocalPkg {
+	// For generic methods, we need to generate the wrapper even if the receiver
+	// types are identical, because we want to add the dictionary.
+	if !generic && types.Identical(rcvr, method.Type.Recv().Type) {
 		return lsym
 	}
 
-	// Only generate I.M wrappers for I in I's own package
-	// but keep doing it for error.Error (was issue #29304).
-	if rcvr.IsInterface() && rcvr.Sym() != nil && rcvr.Sym().Pkg != types.LocalPkg && rcvr != types.ErrorType {
+	if !NeedEmit(rcvr) || rcvr.IsPtr() && !NeedEmit(rcvr.Elem()) {
 		return lsym
 	}
 
@@ -1802,9 +1847,10 @@
 	nthis := ir.AsNode(tfn.Type().Recv().Nname)
 
 	methodrcvr := method.Type.Recv().Type
+	indirect := rcvr.IsPtr() && rcvr.Elem() == methodrcvr
 
 	// generate nil pointer check for better error
-	if rcvr.IsPtr() && rcvr.Elem() == methodrcvr {
+	if indirect {
 		// generating wrapper from *T to T.
 		n := ir.NewIfStmt(base.Pos, nil, nil, nil)
 		n.Cond = ir.NewBinaryExpr(base.Pos, ir.OEQ, nthis, typecheck.NodNil())
@@ -1814,7 +1860,6 @@
 	}
 
 	dot := typecheck.AddImplicitDots(ir.NewSelectorExpr(base.Pos, ir.OXDOT, nthis, method.Sym))
-
 	// generate call
 	// It's not possible to use a tail call when dynamic linking on ppc64le. The
 	// bad scenario is when a local call is made to the wrapper: the wrapper will
@@ -1826,7 +1871,7 @@
 	// Disable tailcall for RegabiArgs for now. The IR does not connect the
 	// arguments with the OTAILCALL node, and the arguments are not marshaled
 	// correctly.
-	if !base.Flag.Cfg.Instrumenting && rcvr.IsPtr() && methodrcvr.IsPtr() && method.Embedded != 0 && !types.IsInterfaceMethod(method.Type) && !(base.Ctxt.Arch.Name == "ppc64le" && base.Ctxt.Flag_dynlink) && !buildcfg.Experiment.RegabiArgs {
+	if !base.Flag.Cfg.Instrumenting && rcvr.IsPtr() && methodrcvr.IsPtr() && method.Embedded != 0 && !types.IsInterfaceMethod(method.Type) && !(base.Ctxt.Arch.Name == "ppc64le" && base.Ctxt.Flag_dynlink) && !buildcfg.Experiment.RegabiArgs && !generic {
 		// generate tail call: adjust pointer receiver and jump to embedded method.
 		left := dot.X // skip final .M
 		if !left.Type().IsPtr() {
@@ -1837,8 +1882,72 @@
 		fn.Body.Append(ir.NewTailCallStmt(base.Pos, method.Nname.(*ir.Name)))
 	} else {
 		fn.SetWrapper(true) // ignore frame for panic+recover matching
-		call := ir.NewCallExpr(base.Pos, ir.OCALL, dot, nil)
-		call.Args = ir.ParamNames(tfn.Type())
+		var call *ir.CallExpr
+
+		if generic && dot.X != nthis {
+			// TODO: for now, we don't try to generate dictionary wrappers for
+			// any methods involving embedded fields, because we're not
+			// generating the needed dictionaries in instantiateMethods.
+			generic = false
+		}
+
+		if generic {
+			var args []ir.Node
+			var targs []*types.Type
+			if rcvr.IsPtr() {
+				targs = rcvr.Elem().RParams()
+			} else {
+				targs = rcvr.RParams()
+			}
+			if strings.HasPrefix(ir.MethodSym(orig, method.Sym).Name, ".inst.") {
+				fmt.Printf("%s\n", ir.MethodSym(orig, method.Sym).Name)
+				panic("multiple .inst.")
+			}
+			// The wrapper for an auto-generated pointer/non-pointer
+			// receiver method should share the same dictionary as the
+			// corresponding original (user-written) method.
+			baseOrig := orig
+			if baseOrig.IsPtr() && !method.Type.Recv().Type.IsPtr() {
+				baseOrig = baseOrig.Elem()
+			} else if !baseOrig.IsPtr() && method.Type.Recv().Type.IsPtr() {
+				baseOrig = types.NewPtr(baseOrig)
+			}
+			args = append(args, getDictionary(ir.MethodSym(baseOrig, method.Sym), targs))
+			if indirect {
+				args = append(args, ir.NewStarExpr(base.Pos, dot.X))
+			} else if methodrcvr.IsPtr() && methodrcvr.Elem() == dot.X.Type() {
+				// Case where method call is via a non-pointer
+				// embedded field with a pointer method.
+				args = append(args, typecheck.NodAddrAt(base.Pos, dot.X))
+			} else {
+				args = append(args, dot.X)
+			}
+			args = append(args, ir.ParamNames(tfn.Type())...)
+
+			// Target method uses shaped names.
+			targs2 := make([]*types.Type, len(targs))
+			for i, t := range targs {
+				targs2[i] = typecheck.Shapify(t)
+			}
+			targs = targs2
+
+			sym := typecheck.MakeInstName(ir.MethodSym(methodrcvr, method.Sym), targs, true)
+			if sym.Def == nil {
+				// Currently we make sure that we have all the instantiations
+				// we need by generating them all in ../noder/stencil.go:instantiateMethods
+				// TODO: maybe there's a better, more incremental way to generate
+				// only the instantiations we need?
+				base.Fatalf("instantiation %s not found", sym.Name)
+			}
+			target := ir.AsNode(sym.Def)
+			call = ir.NewCallExpr(base.Pos, ir.OCALL, target, args)
+			// Fill-in the generic method node that was not filled in
+			// in instantiateMethod.
+			method.Nname = fn.Nname
+		} else {
+			call = ir.NewCallExpr(base.Pos, ir.OCALL, dot, nil)
+			call.Args = ir.ParamNames(tfn.Type())
+		}
 		call.IsDDD = tfn.Type().IsVariadic()
 		if method.Type.NumResults() > 0 {
 			ret := ir.NewReturnStmt(base.Pos, nil)
@@ -1858,13 +1967,10 @@
 	ir.CurFunc = fn
 	typecheck.Stmts(fn.Body)
 
-	// Inline calls within (*T).M wrappers. This is safe because we only
-	// generate those wrappers within the same compilation unit as (T).M.
-	// TODO(mdempsky): Investigate why we can't enable this more generally.
-	if rcvr.IsPtr() && rcvr.Elem() == method.Type.Recv().Type && rcvr.Elem().Sym() != nil {
+	if AfterGlobalEscapeAnalysis {
 		inline.InlineCalls(fn)
+		escape.Batch([]*ir.Func{fn}, false)
 	}
-	escape.Batch([]*ir.Func{fn}, false)
 
 	ir.CurFunc = nil
 	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
@@ -1872,11 +1978,21 @@
 	return lsym
 }
 
+// AfterGlobalEscapeAnalysis tracks whether package gc has already
+// performed the main, global escape analysis pass. If so,
+// methodWrapper takes responsibility for escape analyzing any
+// generated wrappers.
+var AfterGlobalEscapeAnalysis bool
+
 var ZeroSize int64
 
 // MarkTypeUsedInInterface marks that type t is converted to an interface.
 // This information is used in the linker in dead method elimination.
 func MarkTypeUsedInInterface(t *types.Type, from *obj.LSym) {
+	if t.HasShape() {
+		// Shape types shouldn't be put in interfaces, so we shouldn't ever get here.
+		base.Fatalf("shape types have no methods %+v", t)
+	}
 	tsym := TypeLinksym(t)
 	// Emit a marker relocation. The linker will know the type is converted
 	// to an interface if "from" is reachable.
@@ -1897,9 +2013,55 @@
 	tsym := TypeLinksym(ityp)
 	r := obj.Addrel(ir.CurFunc.LSym)
 	r.Sym = tsym
-	// dot.Xoffset is the method index * PtrSize (the offset of code pointer
+	// dot.Offset() is the method index * PtrSize (the offset of code pointer
 	// in itab).
 	midx := dot.Offset() / int64(types.PtrSize)
 	r.Add = InterfaceMethodOffset(ityp, midx)
 	r.Type = objabi.R_USEIFACEMETHOD
 }
+
+// MarkUsedIfaceMethodIndex marks that that method number ix (in the AllMethods list)
+// of interface type ityp is used, and should be attached to lsym.
+func MarkUsedIfaceMethodIndex(lsym *obj.LSym, ityp *types.Type, ix int) {
+	tsym := TypeLinksym(ityp)
+	r := obj.Addrel(lsym)
+	r.Sym = tsym
+	r.Add = InterfaceMethodOffset(ityp, int64(ix))
+	r.Type = objabi.R_USEIFACEMETHOD
+}
+
+// getDictionary returns the dictionary for the given named generic function
+// or method, with the given type arguments.
+func getDictionary(gf *types.Sym, targs []*types.Type) ir.Node {
+	if len(targs) == 0 {
+		base.Fatalf("%s should have type arguments", gf.Name)
+	}
+	for _, t := range targs {
+		if t.HasShape() {
+			base.Fatalf("dictionary for %s should only use concrete types: %+v", gf.Name, t)
+		}
+	}
+
+	sym := typecheck.MakeDictName(gf, targs, true)
+
+	// Initialize the dictionary, if we haven't yet already.
+	if lsym := sym.Linksym(); len(lsym.P) == 0 {
+		base.Fatalf("Dictionary should have already been generated: %s.%s", sym.Pkg.Path, sym.Name)
+	}
+
+	// Make a node referencing the dictionary symbol.
+	n := typecheck.NewName(sym)
+	n.SetType(types.Types[types.TUINTPTR]) // should probably be [...]uintptr, but doesn't really matter
+	n.SetTypecheck(1)
+	n.Class = ir.PEXTERN
+	sym.Def = n
+
+	// Return the address of the dictionary.
+	np := typecheck.NodAddr(n)
+	// Note: treat dictionary pointers as uintptrs, so they aren't pointers
+	// with respect to GC. That saves on stack scanning work, write barriers, etc.
+	// We can get away with it because dictionaries are global variables.
+	np.SetType(types.Types[types.TUINTPTR])
+	np.SetTypecheck(1)
+	return np
+}
diff --git a/src/cmd/compile/internal/riscv64/galign.go b/src/cmd/compile/internal/riscv64/galign.go
index 338248a..846ed8f 100644
--- a/src/cmd/compile/internal/riscv64/galign.go
+++ b/src/cmd/compile/internal/riscv64/galign.go
@@ -16,7 +16,6 @@
 	arch.MAXWIDTH = 1 << 50
 
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 	arch.ZeroRange = zeroRange
 
 	arch.SSAMarkMoves = ssaMarkMoves
diff --git a/src/cmd/compile/internal/s390x/galign.go b/src/cmd/compile/internal/s390x/galign.go
index b004a2d..d880834 100644
--- a/src/cmd/compile/internal/s390x/galign.go
+++ b/src/cmd/compile/internal/s390x/galign.go
@@ -16,7 +16,6 @@
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/ssa/config.go b/src/cmd/compile/internal/ssa/config.go
index a8393a1..32e3a08 100644
--- a/src/cmd/compile/internal/ssa/config.go
+++ b/src/cmd/compile/internal/ssa/config.go
@@ -149,12 +149,6 @@
 	// for the parts of that compound type.
 	SplitSlot(parent *LocalSlot, suffix string, offset int64, t *types.Type) LocalSlot
 
-	// DerefItab dereferences an itab function
-	// entry, given the symbol of the itab and
-	// the byte offset of the function pointer.
-	// It may return nil.
-	DerefItab(sym *obj.LSym, offset int64) *obj.LSym
-
 	// Line returns a string describing the given position.
 	Line(src.XPos) string
 
@@ -177,7 +171,7 @@
 }
 
 // NewConfig returns a new configuration object for the given architecture.
-func NewConfig(arch string, types Types, ctxt *obj.Link, optimize bool) *Config {
+func NewConfig(arch string, types Types, ctxt *obj.Link, optimize, softfloat bool) *Config {
 	c := &Config{arch: arch, Types: types}
 	c.useAvg = true
 	c.useHmul = true
@@ -196,7 +190,7 @@
 		c.floatParamRegs = paramFloatRegAMD64
 		c.FPReg = framepointerRegAMD64
 		c.LinkReg = linkRegAMD64
-		c.hasGReg = buildcfg.Experiment.RegabiG
+		c.hasGReg = true
 	case "386":
 		c.PtrSize = 4
 		c.RegSize = 4
@@ -228,6 +222,8 @@
 		c.registers = registersARM64[:]
 		c.gpRegMask = gpRegMaskARM64
 		c.fpRegMask = fpRegMaskARM64
+		c.intParamRegs = paramIntRegARM64
+		c.floatParamRegs = paramFloatRegARM64
 		c.FPReg = framepointerRegARM64
 		c.LinkReg = linkRegARM64
 		c.hasGReg = true
@@ -324,6 +320,10 @@
 	c.optimize = optimize
 	c.useSSE = true
 	c.UseFMA = true
+	c.SoftFloat = softfloat
+	if softfloat {
+		c.floatParamRegs = nil // no FP registers in softfloat mode
+	}
 
 	c.ABI0 = abi.NewABIConfig(0, 0, ctxt.FixedFrameSize())
 	c.ABI1 = abi.NewABIConfig(len(c.intParamRegs), len(c.floatParamRegs), ctxt.FixedFrameSize())
diff --git a/src/cmd/compile/internal/ssa/expand_calls.go b/src/cmd/compile/internal/ssa/expand_calls.go
index 7e973ab..a8c6c26 100644
--- a/src/cmd/compile/internal/ssa/expand_calls.go
+++ b/src/cmd/compile/internal/ssa/expand_calls.go
@@ -215,7 +215,7 @@
 		return false
 	}
 	return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice() ||
-		t.Size() > x.regSize && t.IsInteger()
+		(t.Size() > x.regSize && (t.IsInteger() || (x.f.Config.SoftFloat && t.IsFloat())))
 }
 
 // offsetFrom creates an offset from a pointer, simplifying chained offsets and offsets from SP
@@ -380,6 +380,12 @@
 		// The OpLoad was created to load the single field of the IData
 		// This case removes that StructSelect.
 		if leafType != selector.Type {
+			if x.f.Config.SoftFloat && selector.Type.IsFloat() {
+				if x.debug {
+					x.Printf("---OpLoad, break\n")
+				}
+				break // softfloat pass will take care of that
+			}
 			x.f.Fatalf("Unexpected Load as selector, leaf=%s, selector=%s\n", leaf.LongString(), selector.LongString())
 		}
 		leaf.copyOf(selector)
@@ -525,11 +531,11 @@
 
 	case OpComplexReal:
 		ls := x.rewriteSelect(leaf, selector.Args[0], offset, regOffset)
-		locs = x.splitSlots(ls, ".real", 0, leafType)
+		locs = x.splitSlots(ls, ".real", 0, selector.Type)
 
 	case OpComplexImag:
-		ls := x.rewriteSelect(leaf, selector.Args[0], offset+leafType.Width, regOffset+RO_complex_imag) // result is FloatNN, width of result is offset of imaginary part.
-		locs = x.splitSlots(ls, ".imag", leafType.Width, leafType)
+		ls := x.rewriteSelect(leaf, selector.Args[0], offset+selector.Type.Width, regOffset+RO_complex_imag) // result is FloatNN, width of result is offset of imaginary part.
+		locs = x.splitSlots(ls, ".imag", selector.Type.Width, selector.Type)
 
 	case OpStringLen, OpSliceLen:
 		ls := x.rewriteSelect(leaf, selector.Args[0], offset+x.ptrSize, regOffset+RO_slice_len)
diff --git a/src/cmd/compile/internal/ssa/export_test.go b/src/cmd/compile/internal/ssa/export_test.go
index 8ed8a0c..6d3c0f3 100644
--- a/src/cmd/compile/internal/ssa/export_test.go
+++ b/src/cmd/compile/internal/ssa/export_test.go
@@ -39,7 +39,7 @@
 		tb.Fatal("testTypes is 64-bit only")
 	}
 	c := &Conf{
-		config: NewConfig(arch, testTypes, ctxt, true),
+		config: NewConfig(arch, testTypes, ctxt, true, false),
 		tb:     tb,
 	}
 	return c
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules
index 4cd0073..45c0238 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules
@@ -460,7 +460,7 @@
 (IsInBounds idx len) => (SETB (CMPQ idx len))
 (IsSliceInBounds idx len) => (SETBE (CMPQ idx len))
 (NilCheck ...) => (LoweredNilCheck ...)
-(GetG mem) && !(buildcfg.Experiment.RegabiG && v.Block.Func.OwnAux.Fn.ABI() == obj.ABIInternal) => (LoweredGetG mem) // only lower in old ABI. in new ABI we have a G register.
+(GetG mem) && v.Block.Func.OwnAux.Fn.ABI() != obj.ABIInternal => (LoweredGetG mem) // only lower in old ABI. in new ABI we have a G register.
 (GetClosurePtr ...) => (LoweredGetClosurePtr ...)
 (GetCallerPC ...) => (LoweredGetCallerPC ...)
 (GetCallerSP ...) => (LoweredGetCallerSP ...)
diff --git a/src/cmd/compile/internal/ssa/gen/ARM64.rules b/src/cmd/compile/internal/ssa/gen/ARM64.rules
index 62699f2..530e48b 100644
--- a/src/cmd/compile/internal/ssa/gen/ARM64.rules
+++ b/src/cmd/compile/internal/ssa/gen/ARM64.rules
@@ -2868,3 +2868,12 @@
 	&& isInlinableMemmove(dst, src, sz, config)
 	&& clobber(s1, s2, s3, call)
 	=> (Move [sz] dst src mem)
+
+// Match post-lowering calls, register version.
+(SelectN [0] call:(CALLstatic {sym} dst src (MOVDconst [sz]) mem))
+	&& sz >= 0
+	&& isSameCall(sym, "runtime.memmove")
+	&& call.Uses == 1
+	&& isInlinableMemmove(dst, src, sz, config)
+	&& clobber(call)
+	=> (Move [sz] dst src mem)
diff --git a/src/cmd/compile/internal/ssa/gen/ARM64Ops.go b/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
index 18a5666..5de0b5f 100644
--- a/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
@@ -482,9 +482,9 @@
 		{name: "CSETM", argLength: 1, reg: readflags, asm: "CSETM", aux: "CCop"}, // auxint(flags) ? -1 : 0
 
 		// function calls
-		{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true},                                               // call static function aux.(*obj.LSym).  arg0=mem, auxint=argsize, returns mem
-		{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R26"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure.  arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
-		{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true},                         // call fn by pointer.  arg0=codeptr, arg1=mem, auxint=argsize, returns mem
+		{name: "CALLstatic", argLength: -1, reg: regInfo{clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true},                                               // call static function aux.(*obj.LSym).  last arg=mem, auxint=argsize, returns mem
+		{name: "CALLclosure", argLength: -1, reg: regInfo{inputs: []regMask{gpsp, buildReg("R26"), 0}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true}, // call function via closure.  arg0=codeptr, arg1=closure, last arg=mem, auxint=argsize, returns mem
+		{name: "CALLinter", argLength: -1, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "CallOff", clobberFlags: true, call: true},                         // call fn by pointer.  arg0=codeptr, last arg=mem, auxint=argsize, returns mem
 
 		// pseudo-ops
 		{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true, faultOnNilArg0: true}, // panic if arg0 is nil.  arg1=mem.
@@ -759,15 +759,17 @@
 	}
 
 	archs = append(archs, arch{
-		name:            "ARM64",
-		pkg:             "cmd/internal/obj/arm64",
-		genfile:         "../../arm64/ssa.go",
-		ops:             ops,
-		blocks:          blocks,
-		regnames:        regNamesARM64,
-		gpregmask:       gp,
-		fpregmask:       fp,
-		framepointerreg: -1, // not used
-		linkreg:         int8(num["R30"]),
+		name:               "ARM64",
+		pkg:                "cmd/internal/obj/arm64",
+		genfile:            "../../arm64/ssa.go",
+		ops:                ops,
+		blocks:             blocks,
+		regnames:           regNamesARM64,
+		ParamIntRegNames:   "R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15",
+		ParamFloatRegNames: "F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15",
+		gpregmask:          gp,
+		fpregmask:          fp,
+		framepointerreg:    -1, // not used
+		linkreg:            int8(num["R30"]),
 	})
 }
diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index 1c37fbe..df15c2e 100644
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -20664,7 +20664,7 @@
 	{
 		name:         "CALLstatic",
 		auxType:      auxCallOff,
-		argLen:       1,
+		argLen:       -1,
 		clobberFlags: true,
 		call:         true,
 		reg: regInfo{
@@ -20674,7 +20674,7 @@
 	{
 		name:         "CALLclosure",
 		auxType:      auxCallOff,
-		argLen:       3,
+		argLen:       -1,
 		clobberFlags: true,
 		call:         true,
 		reg: regInfo{
@@ -20688,7 +20688,7 @@
 	{
 		name:         "CALLinter",
 		auxType:      auxCallOff,
-		argLen:       2,
+		argLen:       -1,
 		clobberFlags: true,
 		call:         true,
 		reg: regInfo{
@@ -36400,8 +36400,8 @@
 	{62, arm64.REG_F31, -1, "F31"},
 	{63, 0, -1, "SB"},
 }
-var paramIntRegARM64 = []int8(nil)
-var paramFloatRegARM64 = []int8(nil)
+var paramIntRegARM64 = []int8{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
+var paramFloatRegARM64 = []int8{31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46}
 var gpRegMaskARM64 = regMask(670826495)
 var fpRegMaskARM64 = regMask(9223372034707292160)
 var specialRegMaskARM64 = regMask(0)
diff --git a/src/cmd/compile/internal/ssa/rewrite.go b/src/cmd/compile/internal/ssa/rewrite.go
index 375c4d5..115d563 100644
--- a/src/cmd/compile/internal/ssa/rewrite.go
+++ b/src/cmd/compile/internal/ssa/rewrite.go
@@ -745,27 +745,21 @@
 	return uint64(a)+uint64(b) < uint64(a)
 }
 
-// de-virtualize an InterCall
-// 'sym' is the symbol for the itab
-func devirt(v *Value, aux Aux, sym Sym, offset int64) *AuxCall {
-	f := v.Block.Func
-	n, ok := sym.(*obj.LSym)
-	if !ok {
+// loadLSymOffset simulates reading a word at an offset into a
+// read-only symbol's runtime memory. If it would read a pointer to
+// another symbol, that symbol is returned. Otherwise, it returns nil.
+func loadLSymOffset(lsym *obj.LSym, offset int64) *obj.LSym {
+	if lsym.Type != objabi.SRODATA {
 		return nil
 	}
-	lsym := f.fe.DerefItab(n, offset)
-	if f.pass.debug > 0 {
-		if lsym != nil {
-			f.Warnl(v.Pos, "de-virtualizing call")
-		} else {
-			f.Warnl(v.Pos, "couldn't de-virtualize call")
+
+	for _, r := range lsym.R {
+		if int64(r.Off) == offset && r.Type&^objabi.R_WEAK == objabi.R_ADDR && r.Add == 0 {
+			return r.Sym
 		}
 	}
-	if lsym == nil {
-		return nil
-	}
-	va := aux.(*AuxCall)
-	return StaticAuxCall(lsym, va.abiInfo)
+
+	return nil
 }
 
 // de-virtualize an InterLECall
@@ -776,18 +770,14 @@
 		return nil
 	}
 
-	f := v.Block.Func
-	lsym := f.fe.DerefItab(n, offset)
-	if f.pass.debug > 0 {
+	lsym := loadLSymOffset(n, offset)
+	if f := v.Block.Func; f.pass.debug > 0 {
 		if lsym != nil {
 			f.Warnl(v.Pos, "de-virtualizing call")
 		} else {
 			f.Warnl(v.Pos, "couldn't de-virtualize call")
 		}
 	}
-	if lsym == nil {
-		return nil
-	}
 	return lsym
 }
 
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index 5045ba7..89d32c0 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -3,7 +3,6 @@
 
 package ssa
 
-import "internal/buildcfg"
 import "math"
 import "cmd/internal/obj"
 import "cmd/compile/internal/types"
@@ -29339,11 +29338,11 @@
 func rewriteValueAMD64_OpGetG(v *Value) bool {
 	v_0 := v.Args[0]
 	// match: (GetG mem)
-	// cond: !(buildcfg.Experiment.RegabiG && v.Block.Func.OwnAux.Fn.ABI() == obj.ABIInternal)
+	// cond: v.Block.Func.OwnAux.Fn.ABI() != obj.ABIInternal
 	// result: (LoweredGetG mem)
 	for {
 		mem := v_0
-		if !(!(buildcfg.Experiment.RegabiG && v.Block.Func.OwnAux.Fn.ABI() == obj.ABIInternal)) {
+		if !(v.Block.Func.OwnAux.Fn.ABI() != obj.ABIInternal) {
 			break
 		}
 		v.reset(OpAMD64LoweredGetG)
diff --git a/src/cmd/compile/internal/ssa/rewriteARM64.go b/src/cmd/compile/internal/ssa/rewriteARM64.go
index 3cdc4d3..f7840c5 100644
--- a/src/cmd/compile/internal/ssa/rewriteARM64.go
+++ b/src/cmd/compile/internal/ssa/rewriteARM64.go
@@ -25997,7 +25997,7 @@
 			break
 		}
 		call := v_0
-		if call.Op != OpARM64CALLstatic {
+		if call.Op != OpARM64CALLstatic || len(call.Args) != 1 {
 			break
 		}
 		sym := auxToCall(call.Aux)
@@ -26031,6 +26031,34 @@
 		v.AddArg3(dst, src, mem)
 		return true
 	}
+	// match: (SelectN [0] call:(CALLstatic {sym} dst src (MOVDconst [sz]) mem))
+	// cond: sz >= 0 && isSameCall(sym, "runtime.memmove") && call.Uses == 1 && isInlinableMemmove(dst, src, sz, config) && clobber(call)
+	// result: (Move [sz] dst src mem)
+	for {
+		if auxIntToInt64(v.AuxInt) != 0 {
+			break
+		}
+		call := v_0
+		if call.Op != OpARM64CALLstatic || len(call.Args) != 4 {
+			break
+		}
+		sym := auxToCall(call.Aux)
+		mem := call.Args[3]
+		dst := call.Args[0]
+		src := call.Args[1]
+		call_2 := call.Args[2]
+		if call_2.Op != OpARM64MOVDconst {
+			break
+		}
+		sz := auxIntToInt64(call_2.AuxInt)
+		if !(sz >= 0 && isSameCall(sym, "runtime.memmove") && call.Uses == 1 && isInlinableMemmove(dst, src, sz, config) && clobber(call)) {
+			break
+		}
+		v.reset(OpMove)
+		v.AuxInt = int64ToAuxInt(sz)
+		v.AddArg3(dst, src, mem)
+		return true
+	}
 	return false
 }
 func rewriteValueARM64_OpSlicemask(v *Value) bool {
diff --git a/src/cmd/compile/internal/ssa/schedule.go b/src/cmd/compile/internal/ssa/schedule.go
index 4e3e5e7..c5130b2 100644
--- a/src/cmd/compile/internal/ssa/schedule.go
+++ b/src/cmd/compile/internal/ssa/schedule.go
@@ -220,7 +220,7 @@
 			// unless they are phi values (which must be first).
 			// OpArg also goes first -- if it is stack it register allocates
 			// to a LoadReg, if it is register it is from the beginning anyway.
-			if c.Op == OpPhi || c.Op == OpArg {
+			if score[c.ID] == ScorePhi || score[c.ID] == ScoreArg {
 				continue
 			}
 			score[c.ID] = ScoreControl
diff --git a/src/cmd/compile/internal/ssa/softfloat.go b/src/cmd/compile/internal/ssa/softfloat.go
index a8a8f83..351f824 100644
--- a/src/cmd/compile/internal/ssa/softfloat.go
+++ b/src/cmd/compile/internal/ssa/softfloat.go
@@ -63,6 +63,7 @@
 					v.Aux = f.Config.Types.UInt32
 				case 8:
 					v.Aux = f.Config.Types.UInt64
+					newInt64 = true
 				default:
 					v.Fatalf("bad float type with size %d", size)
 				}
diff --git a/src/cmd/compile/internal/ssagen/abi.go b/src/cmd/compile/internal/ssagen/abi.go
index e460ada..6d8c53e 100644
--- a/src/cmd/compile/internal/ssagen/abi.go
+++ b/src/cmd/compile/internal/ssagen/abi.go
@@ -152,6 +152,9 @@
 		// Apply definitions.
 		defABI, hasDefABI := s.defs[symName]
 		if hasDefABI {
+			if len(fn.Body) != 0 {
+				base.ErrorfAt(fn.Pos(), "%v defined in both Go and assembly", fn)
+			}
 			fn.ABI = defABI
 		}
 
diff --git a/src/cmd/compile/internal/ssagen/arch.go b/src/cmd/compile/internal/ssagen/arch.go
index 7215f42..483e45c 100644
--- a/src/cmd/compile/internal/ssagen/arch.go
+++ b/src/cmd/compile/internal/ssagen/arch.go
@@ -29,8 +29,7 @@
 	// at function entry, and it is ok to clobber registers.
 	ZeroRange func(*objw.Progs, *obj.Prog, int64, int64, *uint32) *obj.Prog
 
-	Ginsnop      func(*objw.Progs) *obj.Prog
-	Ginsnopdefer func(*objw.Progs) *obj.Prog // special ginsnop for deferreturn
+	Ginsnop func(*objw.Progs) *obj.Prog
 
 	// SSAMarkMoves marks any MOVXconst ops that need to avoid clobbering flags.
 	SSAMarkMoves func(*State, *ssa.Block)
@@ -42,10 +41,10 @@
 	// for all values in the block before SSAGenBlock.
 	SSAGenBlock func(s *State, b, next *ssa.Block)
 
-	// LoadRegResults emits instructions that loads register-assigned results
-	// into registers. They are already in memory (PPARAMOUT nodes).
-	// Used in open-coded defer return path.
-	LoadRegResults func(s *State, f *ssa.Func)
+	// LoadRegResult emits instructions that loads register-assigned result
+	// at n+off (n is PPARAMOUT) to register reg. The result is already in
+	// memory. Used in open-coded defer return path.
+	LoadRegResult func(s *State, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog
 
 	// SpillArgReg emits instructions that spill reg to n+off.
 	SpillArgReg func(pp *objw.Progs, p *obj.Prog, f *ssa.Func, t *types.Type, reg int16, n *ir.Name, off int64) *obj.Prog
diff --git a/src/cmd/compile/internal/ssagen/pgen.go b/src/cmd/compile/internal/ssagen/pgen.go
index 6256753..93157bf 100644
--- a/src/cmd/compile/internal/ssagen/pgen.go
+++ b/src/cmd/compile/internal/ssagen/pgen.go
@@ -114,7 +114,10 @@
 		}
 	}
 
-	sort.Sort(byStackVar(fn.Dcl))
+	// Use sort.Stable instead of sort.Sort so stack layout (and thus
+	// compiler output) is less sensitive to frontend changes that
+	// introduce or remove unused variables.
+	sort.Stable(byStackVar(fn.Dcl))
 
 	// Reassign stack offsets of the locals that are used.
 	lastHasPtr := false
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index dfa7600..b0f2585 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -87,8 +87,7 @@
 	_ = types.NewPtr(types.Types[types.TINT64])                             // *int64
 	_ = types.NewPtr(types.ErrorType)                                       // *error
 	types.NewPtrCacheEnabled = false
-	ssaConfig = ssa.NewConfig(base.Ctxt.Arch.Name, *types_, base.Ctxt, base.Flag.N == 0)
-	ssaConfig.SoftFloat = Arch.SoftFloat
+	ssaConfig = ssa.NewConfig(base.Ctxt.Arch.Name, *types_, base.Ctxt, base.Flag.N == 0, Arch.SoftFloat)
 	ssaConfig.Race = base.Flag.Race
 	ssaCaches = make([]ssa.Cache, base.Flag.LowerC)
 
@@ -279,18 +278,6 @@
 	return np > 0 && strings.Contains(ft.Params.FieldType(np-1).String(), magicLastTypeName)
 }
 
-// getParam returns the Field of ith param of node n (which is a
-// function/method/interface call), where the receiver of a method call is
-// considered as the 0th parameter. This does not include the receiver of an
-// interface call.
-func getParam(n *ir.CallExpr, i int) *types.Field {
-	t := n.X.Type()
-	if n.Op() == ir.OCALLMETH {
-		base.Fatalf("OCALLMETH missed by walkCall")
-	}
-	return t.Params().Field(i)
-}
-
 // dvarint writes a varint v to the funcdata in symbol x and returns the new offset
 func dvarint(x *obj.LSym, off int, v int64) int {
 	if v < 0 || v > 1e9 {
@@ -324,66 +311,21 @@
 // for stack variables are specified as the number of bytes below varp (pointer to the
 // top of the local variables) for their starting address. The format is:
 //
-//  - Max total argument size among all the defers
 //  - Offset of the deferBits variable
 //  - Number of defers in the function
 //  - Information about each defer call, in reverse order of appearance in the function:
-//    - Total argument size of the call
 //    - Offset of the closure value to call
-//    - Number of arguments (including interface receiver or method receiver as first arg)
-//    - Information about each argument
-//      - Offset of the stored defer argument in this function's frame
-//      - Size of the argument
-//      - Offset of where argument should be placed in the args frame when making call
 func (s *state) emitOpenDeferInfo() {
 	x := base.Ctxt.Lookup(s.curfn.LSym.Name + ".opendefer")
 	s.curfn.LSym.Func().OpenCodedDeferInfo = x
 	off := 0
-
-	// Compute maxargsize (max size of arguments for all defers)
-	// first, so we can output it first to the funcdata
-	var maxargsize int64
-	for i := len(s.openDefers) - 1; i >= 0; i-- {
-		r := s.openDefers[i]
-		argsize := r.n.X.Type().ArgWidth() // TODO register args: but maybe use of abi0 will make this easy
-		if argsize > maxargsize {
-			maxargsize = argsize
-		}
-	}
-	off = dvarint(x, off, maxargsize)
 	off = dvarint(x, off, -s.deferBitsTemp.FrameOffset())
 	off = dvarint(x, off, int64(len(s.openDefers)))
 
 	// Write in reverse-order, for ease of running in that order at runtime
 	for i := len(s.openDefers) - 1; i >= 0; i-- {
 		r := s.openDefers[i]
-		off = dvarint(x, off, r.n.X.Type().ArgWidth())
 		off = dvarint(x, off, -r.closureNode.FrameOffset())
-		numArgs := len(r.argNodes)
-		if r.rcvrNode != nil {
-			// If there's an interface receiver, treat/place it as the first
-			// arg. (If there is a method receiver, it's already included as
-			// first arg in r.argNodes.)
-			numArgs++
-		}
-		off = dvarint(x, off, int64(numArgs))
-		argAdjust := 0 // presence of receiver offsets the parameter count.
-		if r.rcvrNode != nil {
-			off = dvarint(x, off, -okOffset(r.rcvrNode.FrameOffset()))
-			off = dvarint(x, off, s.config.PtrSize)
-			off = dvarint(x, off, 0) // This is okay because defer records use ABI0 (for now)
-			argAdjust++
-		}
-
-		// TODO(register args) assume abi0 for this?
-		ab := s.f.ABI0
-		pri := ab.ABIAnalyzeFuncType(r.n.X.Type().FuncType())
-		for j, arg := range r.argNodes {
-			f := getParam(r.n, j)
-			off = dvarint(x, off, -okOffset(arg.FrameOffset()))
-			off = dvarint(x, off, f.Type.Size())
-			off = dvarint(x, off, okOffset(pri.InParam(j+argAdjust).FrameOffset(pri)))
-		}
 	}
 }
 
@@ -580,7 +522,7 @@
 	}
 
 	// Populate closure variables.
-	if !fn.ClosureCalled() {
+	if fn.Needctxt() {
 		clo := s.entryNewValue0(ssa.OpGetClosurePtr, s.f.Config.Types.BytePtr)
 		offset := int64(types.PtrSize) // PtrSize to skip past function entry PC field
 		for _, n := range fn.ClosureVars {
@@ -650,7 +592,6 @@
 	// it mimics the behavior of the former ABI (everything stored) and because it's not 100%
 	// clear if naming conventions are respected in autogenerated code.
 	// TODO figure out exactly what's unused, don't spill it. Make liveness fine-grained, also.
-	// TODO non-amd64 architectures have link registers etc that may require adjustment here.
 	for _, p := range params.InParams() {
 		typs, offs := p.RegisterTypesAndOffsets()
 		for i, t := range typs {
@@ -865,16 +806,6 @@
 	// function, method, or interface call, to store a closure that panic
 	// processing can use for this defer.
 	closureNode *ir.Name
-	// If defer call is interface call, the address of the argtmp where the
-	// receiver is stored
-	rcvr *ssa.Value
-	// The node representing the argtmp where the receiver is stored
-	rcvrNode *ir.Name
-	// The addresses of the argtmps where the evaluated arguments of the defer
-	// function call are stored.
-	argVals []*ssa.Value
-	// The nodes representing the argtmps where the args of the defer are stored
-	argNodes []*ir.Name
 }
 
 type state struct {
@@ -1491,7 +1422,12 @@
 
 	case ir.OAS2DOTTYPE:
 		n := n.(*ir.AssignListStmt)
-		res, resok := s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
+		var res, resok *ssa.Value
+		if n.Rhs[0].Op() == ir.ODOTTYPE2 {
+			res, resok = s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
+		} else {
+			res, resok = s.dynamicDottype(n.Rhs[0].(*ir.DynamicTypeAssertExpr), true)
+		}
 		deref := false
 		if !TypeOK(n.Rhs[0].Type()) {
 			if res.Op != ssa.OpLoad {
@@ -2748,6 +2684,11 @@
 		res, _ := s.dottype(n, false)
 		return res
 
+	case ir.ODYNAMICDOTTYPE:
+		n := n.(*ir.DynamicTypeAssertExpr)
+		res, _ := s.dynamicDottype(n, false)
+		return res
+
 	// binary ops
 	case ir.OLT, ir.OEQ, ir.ONE, ir.OLE, ir.OGE, ir.OGT:
 		n := n.(*ir.BinaryExpr)
@@ -3183,7 +3124,7 @@
 		}
 		fallthrough
 
-	case ir.OCALLINTER, ir.OCALLMETH:
+	case ir.OCALLINTER:
 		n := n.(*ir.CallExpr)
 		return s.callResult(n, callNormal)
 
@@ -3191,6 +3132,14 @@
 		n := n.(*ir.CallExpr)
 		return s.newValue1(ssa.OpGetG, n.Type(), s.mem())
 
+	case ir.OGETCALLERPC:
+		n := n.(*ir.CallExpr)
+		return s.newValue0(ssa.OpGetCallerPC, n.Type())
+
+	case ir.OGETCALLERSP:
+		n := n.(*ir.CallExpr)
+		return s.newValue0(ssa.OpGetCallerSP, n.Type())
+
 	case ir.OAPPEND:
 		return s.append(n.(*ir.CallExpr), false)
 
@@ -3703,6 +3652,16 @@
 // TODO: do not emit sfcall if operation can be optimized to constant in later
 // opt phase
 func (s *state) sfcall(op ssa.Op, args ...*ssa.Value) (*ssa.Value, bool) {
+	f2i := func(t *types.Type) *types.Type {
+		switch t.Kind() {
+		case types.TFLOAT32:
+			return types.Types[types.TUINT32]
+		case types.TFLOAT64:
+			return types.Types[types.TUINT64]
+		}
+		return t
+	}
+
 	if callDef, ok := softFloatOps[op]; ok {
 		switch op {
 		case ssa.OpLess32F,
@@ -3715,7 +3674,19 @@
 			args[1] = s.newValue1(s.ssaOp(ir.ONEG, types.Types[callDef.rtype]), args[1].Type, args[1])
 		}
 
-		result := s.rtcall(callDef.rtfn, true, []*types.Type{types.Types[callDef.rtype]}, args...)[0]
+		// runtime functions take uints for floats and returns uints.
+		// Convert to uints so we use the right calling convention.
+		for i, a := range args {
+			if a.Type.IsFloat() {
+				args[i] = s.newValue1(ssa.OpCopy, f2i(a.Type), a)
+			}
+		}
+
+		rt := types.Types[callDef.rtype]
+		result := s.rtcall(callDef.rtfn, true, []*types.Type{f2i(rt)}, args...)[0]
+		if rt.IsFloat() {
+			result = s.newValue1(ssa.OpCopy, rt, result)
+		}
 		if op == ssa.OpNeq32F || op == ssa.OpNeq64F {
 			result = s.newValue1(ssa.OpNot, result.Type, result)
 		}
@@ -4687,17 +4658,14 @@
 	return args
 }
 
-// openDeferRecord adds code to evaluate and store the args for an open-code defer
+// openDeferRecord adds code to evaluate and store the function for an open-code defer
 // call, and records info about the defer, so we can generate proper code on the
 // exit paths. n is the sub-node of the defer node that is the actual function
-// call. We will also record funcdata information on where the args are stored
+// call. We will also record funcdata information on where the function is stored
 // (as well as the deferBits variable), and this will enable us to run the proper
 // defer calls during panics.
 func (s *state) openDeferRecord(n *ir.CallExpr) {
-	var args []*ssa.Value
-	var argNodes []*ir.Name
-
-	if buildcfg.Experiment.RegabiDefer && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
+	if len(n.Args) != 0 || n.Op() != ir.OCALLFUNC || n.X.Type().NumResults() != 0 {
 		s.Fatalf("defer call with arguments or results: %v", n)
 	}
 
@@ -4705,48 +4673,20 @@
 		n: n,
 	}
 	fn := n.X
-	if n.Op() == ir.OCALLFUNC {
-		// We must always store the function value in a stack slot for the
-		// runtime panic code to use. But in the defer exit code, we will
-		// call the function directly if it is a static function.
-		closureVal := s.expr(fn)
-		closure := s.openDeferSave(nil, fn.Type(), closureVal)
-		opendefer.closureNode = closure.Aux.(*ir.Name)
-		if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
-			opendefer.closure = closure
-		}
-	} else if n.Op() == ir.OCALLMETH {
-		base.Fatalf("OCALLMETH missed by walkCall")
-	} else {
-		if fn.Op() != ir.ODOTINTER {
-			base.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op())
-		}
-		fn := fn.(*ir.SelectorExpr)
-		closure, rcvr := s.getClosureAndRcvr(fn)
-		opendefer.closure = s.openDeferSave(nil, closure.Type, closure)
-		// Important to get the receiver type correct, so it is recognized
-		// as a pointer for GC purposes.
-		opendefer.rcvr = s.openDeferSave(nil, fn.Type().Recv().Type, rcvr)
-		opendefer.closureNode = opendefer.closure.Aux.(*ir.Name)
-		opendefer.rcvrNode = opendefer.rcvr.Aux.(*ir.Name)
+	// We must always store the function value in a stack slot for the
+	// runtime panic code to use. But in the defer exit code, we will
+	// call the function directly if it is a static function.
+	closureVal := s.expr(fn)
+	closure := s.openDeferSave(fn.Type(), closureVal)
+	opendefer.closureNode = closure.Aux.(*ir.Name)
+	if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
+		opendefer.closure = closure
 	}
-	for _, argn := range n.Args {
-		var v *ssa.Value
-		if TypeOK(argn.Type()) {
-			v = s.openDeferSave(nil, argn.Type(), s.expr(argn))
-		} else {
-			v = s.openDeferSave(argn, argn.Type(), nil)
-		}
-		args = append(args, v)
-		argNodes = append(argNodes, v.Aux.(*ir.Name))
-	}
-	opendefer.argVals = args
-	opendefer.argNodes = argNodes
 	index := len(s.openDefers)
 	s.openDefers = append(s.openDefers, opendefer)
 
 	// Update deferBits only after evaluation and storage to stack of
-	// args/receiver/interface is successful.
+	// the function is successful.
 	bitvalue := s.constInt8(types.Types[types.TUINT8], 1<<uint(index))
 	newDeferBits := s.newValue2(ssa.OpOr8, types.Types[types.TUINT8], s.variable(deferBitsVar, types.Types[types.TUINT8]), bitvalue)
 	s.vars[deferBitsVar] = newDeferBits
@@ -4755,57 +4695,47 @@
 
 // openDeferSave generates SSA nodes to store a value (with type t) for an
 // open-coded defer at an explicit autotmp location on the stack, so it can be
-// reloaded and used for the appropriate call on exit. If type t is SSAable, then
-// val must be non-nil (and n should be nil) and val is the value to be stored. If
-// type t is non-SSAable, then n must be non-nil (and val should be nil) and n is
-// evaluated (via s.addr() below) to get the value that is to be stored. The
-// function returns an SSA value representing a pointer to the autotmp location.
-func (s *state) openDeferSave(n ir.Node, t *types.Type, val *ssa.Value) *ssa.Value {
-	canSSA := TypeOK(t)
-	var pos src.XPos
-	if canSSA {
-		pos = val.Pos
-	} else {
-		pos = n.Pos()
+// reloaded and used for the appropriate call on exit. Type t must be a function type
+// (therefore SSAable). val is the value to be stored. The function returns an SSA
+// value representing a pointer to the autotmp location.
+func (s *state) openDeferSave(t *types.Type, val *ssa.Value) *ssa.Value {
+	if !TypeOK(t) {
+		s.Fatalf("openDeferSave of non-SSA-able type %v val=%v", t, val)
 	}
-	argTemp := typecheck.TempAt(pos.WithNotStmt(), s.curfn, t)
-	argTemp.SetOpenDeferSlot(true)
-	var addrArgTemp *ssa.Value
-	// Use OpVarLive to make sure stack slots for the args, etc. are not
-	// removed by dead-store elimination
+	if !t.HasPointers() {
+		s.Fatalf("openDeferSave of pointerless type %v val=%v", t, val)
+	}
+	pos := val.Pos
+	temp := typecheck.TempAt(pos.WithNotStmt(), s.curfn, t)
+	temp.SetOpenDeferSlot(true)
+	var addrTemp *ssa.Value
+	// Use OpVarLive to make sure stack slot for the closure is not removed by
+	// dead-store elimination
 	if s.curBlock.ID != s.f.Entry.ID {
-		// Force the argtmp storing this defer function/receiver/arg to be
-		// declared in the entry block, so that it will be live for the
-		// defer exit code (which will actually access it only if the
-		// associated defer call has been activated).
-		s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssa.OpVarDef, types.TypeMem, argTemp, s.defvars[s.f.Entry.ID][memVar])
-		s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssa.OpVarLive, types.TypeMem, argTemp, s.defvars[s.f.Entry.ID][memVar])
-		addrArgTemp = s.f.Entry.NewValue2A(src.NoXPos, ssa.OpLocalAddr, types.NewPtr(argTemp.Type()), argTemp, s.sp, s.defvars[s.f.Entry.ID][memVar])
+		// Force the tmp storing this defer function to be declared in the entry
+		// block, so that it will be live for the defer exit code (which will
+		// actually access it only if the associated defer call has been activated).
+		s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssa.OpVarDef, types.TypeMem, temp, s.defvars[s.f.Entry.ID][memVar])
+		s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssa.OpVarLive, types.TypeMem, temp, s.defvars[s.f.Entry.ID][memVar])
+		addrTemp = s.f.Entry.NewValue2A(src.NoXPos, ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.defvars[s.f.Entry.ID][memVar])
 	} else {
 		// Special case if we're still in the entry block. We can't use
 		// the above code, since s.defvars[s.f.Entry.ID] isn't defined
 		// until we end the entry block with s.endBlock().
-		s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, argTemp, s.mem(), false)
-		s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, argTemp, s.mem(), false)
-		addrArgTemp = s.newValue2Apos(ssa.OpLocalAddr, types.NewPtr(argTemp.Type()), argTemp, s.sp, s.mem(), false)
+		s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, temp, s.mem(), false)
+		s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, temp, s.mem(), false)
+		addrTemp = s.newValue2Apos(ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.mem(), false)
 	}
-	if t.HasPointers() {
-		// Since we may use this argTemp during exit depending on the
-		// deferBits, we must define it unconditionally on entry.
-		// Therefore, we must make sure it is zeroed out in the entry
-		// block if it contains pointers, else GC may wrongly follow an
-		// uninitialized pointer value.
-		argTemp.SetNeedzero(true)
-	}
-	if !canSSA {
-		a := s.addr(n)
-		s.move(t, addrArgTemp, a)
-		return addrArgTemp
-	}
+	// Since we may use this temp during exit depending on the
+	// deferBits, we must define it unconditionally on entry.
+	// Therefore, we must make sure it is zeroed out in the entry
+	// block if it contains pointers, else GC may wrongly follow an
+	// uninitialized pointer value.
+	temp.SetNeedzero(true)
 	// We are storing to the stack, hence we can avoid the full checks in
 	// storeType() (no write barrier) and do a simple store().
-	s.store(t, addrArgTemp, val)
-	return addrArgTemp
+	s.store(t, addrTemp, val)
+	return addrTemp
 }
 
 // openDeferExit generates SSA for processing all the open coded defers at exit.
@@ -4849,45 +4779,26 @@
 		s.vars[deferBitsVar] = maskedval
 
 		// Generate code to call the function call of the defer, using the
-		// closure/receiver/args that were stored in argtmps at the point
-		// of the defer statement.
+		// closure that were stored in argtmps at the point of the defer
+		// statement.
 		fn := r.n.X
 		stksize := fn.Type().ArgWidth()
-		var ACArgs []*types.Type
-		var ACResults []*types.Type
 		var callArgs []*ssa.Value
-		if r.rcvr != nil {
-			// rcvr in case of OCALLINTER
-			v := s.load(r.rcvr.Type.Elem(), r.rcvr)
-			ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
-			callArgs = append(callArgs, v)
-		}
-		for j, argAddrVal := range r.argVals {
-			f := getParam(r.n, j)
-			ACArgs = append(ACArgs, f.Type)
-			var a *ssa.Value
-			if !TypeOK(f.Type) {
-				a = s.newValue2(ssa.OpDereference, f.Type, argAddrVal, s.mem())
-			} else {
-				a = s.load(f.Type, argAddrVal)
-			}
-			callArgs = append(callArgs, a)
-		}
 		var call *ssa.Value
 		if r.closure != nil {
 			v := s.load(r.closure.Type.Elem(), r.closure)
 			s.maybeNilCheckClosure(v, callDefer)
 			codeptr := s.rawLoad(types.Types[types.TUINTPTR], v)
-			aux := ssa.ClosureAuxCall(s.f.ABIDefault.ABIAnalyzeTypes(nil, ACArgs, ACResults))
+			aux := ssa.ClosureAuxCall(s.f.ABIDefault.ABIAnalyzeTypes(nil, nil, nil))
 			call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, v)
 		} else {
-			aux := ssa.StaticAuxCall(fn.(*ir.Name).Linksym(), s.f.ABIDefault.ABIAnalyzeTypes(nil, ACArgs, ACResults))
+			aux := ssa.StaticAuxCall(fn.(*ir.Name).Linksym(), s.f.ABIDefault.ABIAnalyzeTypes(nil, nil, nil))
 			call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
 		}
 		callArgs = append(callArgs, s.mem())
 		call.AddArgs(callArgs...)
 		call.AuxInt = stksize
-		s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(ACResults)), call)
+		s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, 0, call)
 		// Make sure that the stack slots with pointers are kept live
 		// through the call (which is a pre-emption point). Also, we will
 		// use the first call of the last defer exit to compute liveness
@@ -4895,16 +4806,6 @@
 		if r.closureNode != nil {
 			s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, r.closureNode, s.mem(), false)
 		}
-		if r.rcvrNode != nil {
-			if r.rcvrNode.Type().HasPointers() {
-				s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, r.rcvrNode, s.mem(), false)
-			}
-		}
-		for _, argNode := range r.argNodes {
-			if argNode.Type().HasPointers() {
-				s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, argNode, s.mem(), false)
-			}
-		}
 
 		s.endBlock()
 		s.startBlock(bEnd)
@@ -4952,7 +4853,7 @@
 		}
 	}
 
-	if buildcfg.Experiment.RegabiDefer && k != callNormal && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
+	if k != callNormal && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
 		s.Fatalf("go/defer call with arguments: %v", n)
 	}
 
@@ -4986,8 +4887,6 @@
 			// not the point of defer statement.
 			s.maybeNilCheckClosure(closure, k)
 		}
-	case ir.OCALLMETH:
-		base.Fatalf("OCALLMETH missed by walkCall")
 	case ir.OCALLINTER:
 		if fn.Op() != ir.ODOTINTER {
 			s.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op())
@@ -5023,55 +4922,31 @@
 	var call *ssa.Value
 	if k == callDeferStack {
 		// Make a defer struct d on the stack.
-		t := deferstruct(stksize)
+		if stksize != 0 {
+			s.Fatalf("deferprocStack with non-zero stack size %d: %v", stksize, n)
+		}
+
+		t := deferstruct()
 		d := typecheck.TempAt(n.Pos(), s.curfn, t)
 
 		s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, d, s.mem())
 		addr := s.addr(d)
 
-		// Must match reflect.go:deferstruct and src/runtime/runtime2.go:_defer.
-		// 0: siz
-		s.store(types.Types[types.TUINT32],
-			s.newValue1I(ssa.OpOffPtr, types.Types[types.TUINT32].PtrTo(), t.FieldOff(0), addr),
-			s.constInt32(types.Types[types.TUINT32], int32(stksize)))
-		// 1: started, set in deferprocStack
-		// 2: heap, set in deferprocStack
-		// 3: openDefer
-		// 4: sp, set in deferprocStack
-		// 5: pc, set in deferprocStack
-		// 6: fn
+		// Must match deferstruct() below and src/runtime/runtime2.go:_defer.
+		// 0: started, set in deferprocStack
+		// 1: heap, set in deferprocStack
+		// 2: openDefer
+		// 3: sp, set in deferprocStack
+		// 4: pc, set in deferprocStack
+		// 5: fn
 		s.store(closure.Type,
-			s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(6), addr),
+			s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(5), addr),
 			closure)
-		// 7: panic, set in deferprocStack
-		// 8: link, set in deferprocStack
-		// 9: framepc
-		// 10: varp
-		// 11: fd
-
-		// Then, store all the arguments of the defer call.
-		ft := fn.Type()
-		off := t.FieldOff(12) // TODO register args: be sure this isn't a hardcoded param stack offset.
-		args := n.Args
-		i0 := 0
-
-		// Set receiver (for interface calls). Always a pointer.
-		if rcvr != nil {
-			p := s.newValue1I(ssa.OpOffPtr, ft.Recv().Type.PtrTo(), off, addr)
-			s.store(types.Types[types.TUINTPTR], p, rcvr)
-			i0 = 1
-		}
-		// Set receiver (for method calls).
-		if n.Op() == ir.OCALLMETH {
-			base.Fatalf("OCALLMETH missed by walkCall")
-		}
-		// Set other args.
-		// This code is only used when RegabiDefer is not enabled, and arguments are always
-		// passed on stack.
-		for i, f := range ft.Params().Fields().Slice() {
-			s.storeArgWithBase(args[0], f.Type, addr, off+params.InParam(i+i0).FrameOffset(params))
-			args = args[1:]
-		}
+		// 6: panic, set in deferprocStack
+		// 7: link, set in deferprocStack
+		// 8: fd
+		// 9: varp
+		// 10: framepc
 
 		// Call runtime.deferprocStack with pointer to _defer record.
 		ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
@@ -5079,26 +4954,18 @@
 		callArgs = append(callArgs, addr, s.mem())
 		call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
 		call.AddArgs(callArgs...)
-		if stksize < int64(types.PtrSize) {
-			// We need room for both the call to deferprocStack and the call to
-			// the deferred function.
-			stksize = int64(types.PtrSize)
-		}
-		call.AuxInt = stksize
+		call.AuxInt = int64(types.PtrSize) // deferprocStack takes a *_defer arg
 	} else {
 		// Store arguments to stack, including defer/go arguments and receiver for method calls.
 		// These are written in SP-offset order.
 		argStart := base.Ctxt.FixedFrameSize()
 		// Defer/go args.
 		if k != callNormal {
-			// Write argsize and closure (args to newproc/deferproc).
-			argsize := s.constInt32(types.Types[types.TUINT32], int32(stksize))
-			ACArgs = append(ACArgs, types.Types[types.TUINT32]) // not argExtra
-			callArgs = append(callArgs, argsize)
-			ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
+			// Write closure (arg to newproc/deferproc).
+			ACArgs = append(ACArgs, types.Types[types.TUINTPTR]) // not argExtra
 			callArgs = append(callArgs, closure)
-			stksize += 2 * int64(types.PtrSize)
-			argStart += 2 * int64(types.PtrSize)
+			stksize += int64(types.PtrSize)
+			argStart += int64(types.PtrSize)
 		}
 
 		// Set receiver (for interface calls).
@@ -5109,9 +4976,6 @@
 		// Write args.
 		t := n.X.Type()
 		args := n.Args
-		if n.Op() == ir.OCALLMETH {
-			base.Fatalf("OCALLMETH missed by walkCall")
-		}
 
 		for _, p := range params.InParams() { // includes receiver for interface calls
 			ACArgs = append(ACArgs, p.Type)
@@ -5314,9 +5178,13 @@
 	case ir.OCALLFUNC, ir.OCALLINTER:
 		n := n.(*ir.CallExpr)
 		return s.callAddr(n, callNormal)
-	case ir.ODOTTYPE:
-		n := n.(*ir.TypeAssertExpr)
-		v, _ := s.dottype(n, false)
+	case ir.ODOTTYPE, ir.ODYNAMICDOTTYPE:
+		var v *ssa.Value
+		if n.Op() == ir.ODOTTYPE {
+			v, _ = s.dottype(n.(*ir.TypeAssertExpr), false)
+		} else {
+			v, _ = s.dynamicDottype(n.(*ir.DynamicTypeAssertExpr), false)
+		}
 		if v.Op != ssa.OpLoad {
 			s.Fatalf("dottype of non-load")
 		}
@@ -6210,14 +6078,38 @@
 func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
 	iface := s.expr(n.X)              // input interface
 	target := s.reflectType(n.Type()) // target type
-	byteptr := s.f.Config.Types.BytePtr
+	var targetItab *ssa.Value
+	if n.Itab != nil {
+		targetItab = s.expr(n.Itab)
+	}
+	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, target, targetItab, commaok)
+}
 
-	if n.Type().IsInterface() {
-		if n.Type().IsEmptyInterface() {
+func (s *state) dynamicDottype(n *ir.DynamicTypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
+	iface := s.expr(n.X)
+	target := s.expr(n.T)
+	var itab *ssa.Value
+	if !n.X.Type().IsEmptyInterface() && !n.Type().IsInterface() {
+		byteptr := s.f.Config.Types.BytePtr
+		itab = target
+		target = s.load(byteptr, s.newValue1I(ssa.OpOffPtr, byteptr, int64(types.PtrSize), itab)) // itab.typ
+	}
+	return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, target, itab, commaok)
+}
+
+// dottype1 implements a x.(T) operation. iface is the argument (x), dst is the type we're asserting to (T)
+// and src is the type we're asserting from.
+// target is the *runtime._type of dst.
+// If src is a nonempty interface and dst is not an interface, targetItab is an itab representing (dst, src). Otherwise it is nil.
+// commaok is true if the caller wants a boolean success value. Otherwise, the generated code panics if the conversion fails.
+func (s *state) dottype1(pos src.XPos, src, dst *types.Type, iface, target, targetItab *ssa.Value, commaok bool) (res, resok *ssa.Value) {
+	byteptr := s.f.Config.Types.BytePtr
+	if dst.IsInterface() {
+		if dst.IsEmptyInterface() {
 			// Converting to an empty interface.
 			// Input could be an empty or nonempty interface.
 			if base.Debug.TypeAssert > 0 {
-				base.WarnfAt(n.Pos(), "type assertion inlined")
+				base.WarnfAt(pos, "type assertion inlined")
 			}
 
 			// Get itab/type field from input.
@@ -6225,7 +6117,7 @@
 			// Conversion succeeds iff that field is not nil.
 			cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))
 
-			if n.X.Type().IsEmptyInterface() && commaok {
+			if src.IsEmptyInterface() && commaok {
 				// Converting empty interface to empty interface with ,ok is just a nil check.
 				return iface, cond
 			}
@@ -6247,7 +6139,7 @@
 
 				// On success, return (perhaps modified) input interface.
 				s.startBlock(bOk)
-				if n.X.Type().IsEmptyInterface() {
+				if src.IsEmptyInterface() {
 					res = iface // Use input interface unchanged.
 					return
 				}
@@ -6255,7 +6147,7 @@
 				off := s.newValue1I(ssa.OpOffPtr, byteptr, int64(types.PtrSize), itab)
 				typ := s.load(byteptr, off)
 				idata := s.newValue1(ssa.OpIData, byteptr, iface)
-				res = s.newValue2(ssa.OpIMake, n.Type(), typ, idata)
+				res = s.newValue2(ssa.OpIMake, dst, typ, idata)
 				return
 			}
 
@@ -6277,62 +6169,62 @@
 			bFail.AddEdgeTo(bEnd)
 			s.startBlock(bEnd)
 			idata := s.newValue1(ssa.OpIData, byteptr, iface)
-			res = s.newValue2(ssa.OpIMake, n.Type(), s.variable(typVar, byteptr), idata)
+			res = s.newValue2(ssa.OpIMake, dst, s.variable(typVar, byteptr), idata)
 			resok = cond
 			delete(s.vars, typVar)
 			return
 		}
 		// converting to a nonempty interface needs a runtime call.
 		if base.Debug.TypeAssert > 0 {
-			base.WarnfAt(n.Pos(), "type assertion not inlined")
+			base.WarnfAt(pos, "type assertion not inlined")
 		}
 		if !commaok {
 			fn := ir.Syms.AssertI2I
-			if n.X.Type().IsEmptyInterface() {
+			if src.IsEmptyInterface() {
 				fn = ir.Syms.AssertE2I
 			}
 			data := s.newValue1(ssa.OpIData, types.Types[types.TUNSAFEPTR], iface)
 			tab := s.newValue1(ssa.OpITab, byteptr, iface)
 			tab = s.rtcall(fn, true, []*types.Type{byteptr}, target, tab)[0]
-			return s.newValue2(ssa.OpIMake, n.Type(), tab, data), nil
+			return s.newValue2(ssa.OpIMake, dst, tab, data), nil
 		}
 		fn := ir.Syms.AssertI2I2
-		if n.X.Type().IsEmptyInterface() {
+		if src.IsEmptyInterface() {
 			fn = ir.Syms.AssertE2I2
 		}
-		res = s.rtcall(fn, true, []*types.Type{n.Type()}, target, iface)[0]
-		resok = s.newValue2(ssa.OpNeqInter, types.Types[types.TBOOL], res, s.constInterface(n.Type()))
+		res = s.rtcall(fn, true, []*types.Type{dst}, target, iface)[0]
+		resok = s.newValue2(ssa.OpNeqInter, types.Types[types.TBOOL], res, s.constInterface(dst))
 		return
 	}
 
 	if base.Debug.TypeAssert > 0 {
-		base.WarnfAt(n.Pos(), "type assertion inlined")
+		base.WarnfAt(pos, "type assertion inlined")
 	}
 
 	// Converting to a concrete type.
-	direct := types.IsDirectIface(n.Type())
+	direct := types.IsDirectIface(dst)
 	itab := s.newValue1(ssa.OpITab, byteptr, iface) // type word of interface
 	if base.Debug.TypeAssert > 0 {
-		base.WarnfAt(n.Pos(), "type assertion inlined")
+		base.WarnfAt(pos, "type assertion inlined")
 	}
-	var targetITab *ssa.Value
-	if n.X.Type().IsEmptyInterface() {
+	var wantedFirstWord *ssa.Value
+	if src.IsEmptyInterface() {
 		// Looking for pointer to target type.
-		targetITab = target
+		wantedFirstWord = target
 	} else {
 		// Looking for pointer to itab for target type and source interface.
-		targetITab = s.expr(n.Itab)
+		wantedFirstWord = targetItab
 	}
 
 	var tmp ir.Node     // temporary for use with large types
 	var addr *ssa.Value // address of tmp
-	if commaok && !TypeOK(n.Type()) {
+	if commaok && !TypeOK(dst) {
 		// unSSAable type, use temporary.
 		// TODO: get rid of some of these temporaries.
-		tmp, addr = s.temp(n.Pos(), n.Type())
+		tmp, addr = s.temp(pos, dst)
 	}
 
-	cond := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], itab, targetITab)
+	cond := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], itab, wantedFirstWord)
 	b := s.endBlock()
 	b.Kind = ssa.BlockIf
 	b.SetControl(cond)
@@ -6346,8 +6238,8 @@
 	if !commaok {
 		// on failure, panic by calling panicdottype
 		s.startBlock(bFail)
-		taddr := s.reflectType(n.X.Type())
-		if n.X.Type().IsEmptyInterface() {
+		taddr := s.reflectType(src)
+		if src.IsEmptyInterface() {
 			s.rtcall(ir.Syms.PanicdottypeE, false, nil, itab, target, taddr)
 		} else {
 			s.rtcall(ir.Syms.PanicdottypeI, false, nil, itab, target, taddr)
@@ -6356,10 +6248,10 @@
 		// on success, return data from interface
 		s.startBlock(bOk)
 		if direct {
-			return s.newValue1(ssa.OpIData, n.Type(), iface), nil
+			return s.newValue1(ssa.OpIData, dst, iface), nil
 		}
-		p := s.newValue1(ssa.OpIData, types.NewPtr(n.Type()), iface)
-		return s.load(n.Type(), p), nil
+		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
+		return s.load(dst, p), nil
 	}
 
 	// commaok is the more complicated case because we have
@@ -6373,14 +6265,14 @@
 	s.startBlock(bOk)
 	if tmp == nil {
 		if direct {
-			s.vars[valVar] = s.newValue1(ssa.OpIData, n.Type(), iface)
+			s.vars[valVar] = s.newValue1(ssa.OpIData, dst, iface)
 		} else {
-			p := s.newValue1(ssa.OpIData, types.NewPtr(n.Type()), iface)
-			s.vars[valVar] = s.load(n.Type(), p)
+			p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
+			s.vars[valVar] = s.load(dst, p)
 		}
 	} else {
-		p := s.newValue1(ssa.OpIData, types.NewPtr(n.Type()), iface)
-		s.move(n.Type(), addr, p)
+		p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
+		s.move(dst, addr, p)
 	}
 	s.vars[okVar] = s.constBool(true)
 	s.endBlock()
@@ -6389,9 +6281,9 @@
 	// type assertion failed
 	s.startBlock(bFail)
 	if tmp == nil {
-		s.vars[valVar] = s.zeroVal(n.Type())
+		s.vars[valVar] = s.zeroVal(dst)
 	} else {
-		s.zero(n.Type(), addr)
+		s.zero(dst, addr)
 	}
 	s.vars[okVar] = s.constBool(false)
 	s.endBlock()
@@ -6400,10 +6292,10 @@
 	// merge point
 	s.startBlock(bEnd)
 	if tmp == nil {
-		res = s.variable(valVar, n.Type())
+		res = s.variable(valVar, dst)
 		delete(s.vars, valVar)
 	} else {
-		res = s.load(n.Type(), addr)
+		res = s.load(dst, addr)
 		s.vars[memVar] = s.newValue1A(ssa.OpVarKill, types.TypeMem, tmp.(*ir.Name), s.mem())
 	}
 	resok = s.variable(okVar, types.Types[types.TBOOL])
@@ -6921,8 +6813,12 @@
 		// recovers a panic, it will return to caller with right results.
 		// The results are already in memory, because they are not SSA'd
 		// when the function has defers (see canSSAName).
-		if f.OwnAux.ABIInfo().OutRegistersUsed() != 0 {
-			Arch.LoadRegResults(&s, f)
+		for _, o := range f.OwnAux.ABIInfo().OutParams() {
+			n := o.Name.(*ir.Name)
+			rts, offs := o.RegisterTypesAndOffsets()
+			for i := range o.Registers {
+				Arch.LoadRegResult(&s, f, rts[i], ssa.ObjRegForAbiReg(o.Registers[i], f.Config), n, offs[i])
+			}
 		}
 
 		pp.Prog(obj.ARET)
@@ -7460,18 +7356,6 @@
 
 	call, ok := v.Aux.(*ssa.AuxCall)
 
-	if ok && call.Fn == ir.Syms.Deferreturn {
-		// Deferred calls will appear to be returning to
-		// the CALL deferreturn(SB) that we are about to emit.
-		// However, the stack trace code will show the line
-		// of the instruction byte before the return PC.
-		// To avoid that being an unrelated instruction,
-		// insert an actual hardware NOP that will have the right line number.
-		// This is different from obj.ANOP, which is a virtual no-op
-		// that doesn't make it into the instruction stream.
-		Arch.Ginsnopdefer(s.pp)
-	}
-
 	if ok {
 		// Record call graph information for nowritebarrierrec
 		// analysis.
@@ -7542,10 +7426,6 @@
 	return typecheck.TempAt(pos, e.curfn, t) // Note: adds new auto to e.curfn.Func.Dcl list
 }
 
-func (e *ssafn) DerefItab(it *obj.LSym, offset int64) *obj.LSym {
-	return reflectdata.ITabSym(it, offset)
-}
-
 // SplitSlot returns a slot representing the data of parent starting at offset.
 func (e *ssafn) SplitSlot(parent *ssa.LocalSlot, suffix string, offset int64, t *types.Type) ssa.LocalSlot {
 	node := parent.N
@@ -7676,9 +7556,8 @@
 	return b
 }
 
-// deferstruct makes a runtime._defer structure, with additional space for
-// stksize bytes of args.
-func deferstruct(stksize int64) *types.Type {
+// deferstruct makes a runtime._defer structure.
+func deferstruct() *types.Type {
 	makefield := func(name string, typ *types.Type) *types.Field {
 		// Unlike the global makefield function, this one needs to set Pkg
 		// because these types might be compared (in SSA CSE sorting).
@@ -7686,13 +7565,9 @@
 		sym := &types.Sym{Name: name, Pkg: types.LocalPkg}
 		return types.NewField(src.NoXPos, sym, typ)
 	}
-	argtype := types.NewArray(types.Types[types.TUINT8], stksize)
-	argtype.Width = stksize
-	argtype.Align = 1
 	// These fields must match the ones in runtime/runtime2.go:_defer and
-	// cmd/compile/internal/gc/ssa.go:(*state).call.
+	// (*state).call above.
 	fields := []*types.Field{
-		makefield("siz", types.Types[types.TUINT32]),
 		makefield("started", types.Types[types.TBOOL]),
 		makefield("heap", types.Types[types.TBOOL]),
 		makefield("openDefer", types.Types[types.TBOOL]),
@@ -7704,10 +7579,9 @@
 		makefield("fn", types.Types[types.TUINTPTR]),
 		makefield("_panic", types.Types[types.TUINTPTR]),
 		makefield("link", types.Types[types.TUINTPTR]),
-		makefield("framepc", types.Types[types.TUINTPTR]),
-		makefield("varp", types.Types[types.TUINTPTR]),
 		makefield("fd", types.Types[types.TUINTPTR]),
-		makefield("args", argtype),
+		makefield("varp", types.Types[types.TUINTPTR]),
+		makefield("framepc", types.Types[types.TUINTPTR]),
 	}
 
 	// build struct holding the above fields
diff --git a/src/cmd/compile/internal/staticdata/embed.go b/src/cmd/compile/internal/staticdata/embed.go
index 8936c4f..0730d34 100644
--- a/src/cmd/compile/internal/staticdata/embed.go
+++ b/src/cmd/compile/internal/staticdata/embed.go
@@ -108,13 +108,6 @@
 	// TODO(mdempsky): User errors should be reported by the frontend.
 
 	commentPos := (*v.Embed)[0].Pos
-	if !types.AllowsGoVersion(types.LocalPkg, 1, 16) {
-		prevPos := base.Pos
-		base.Pos = commentPos
-		base.ErrorfVers("go1.16", "go:embed")
-		base.Pos = prevPos
-		return
-	}
 	if base.Flag.Cfg.Embed.Patterns == nil {
 		base.ErrorfAt(commentPos, "invalid go:embed: build system did not supply embed configuration")
 		return
diff --git a/src/cmd/compile/internal/staticinit/sched.go b/src/cmd/compile/internal/staticinit/sched.go
index 0c97b6d..9329a46 100644
--- a/src/cmd/compile/internal/staticinit/sched.go
+++ b/src/cmd/compile/internal/staticinit/sched.go
@@ -403,10 +403,10 @@
 				base.Fatalf("initplan structlit")
 			}
 			a := a.(*ir.StructKeyExpr)
-			if a.Field.IsBlank() {
+			if a.Sym().IsBlank() {
 				continue
 			}
-			s.addvalue(p, a.Offset, a.Value)
+			s.addvalue(p, a.Field.Offset, a.Value)
 		}
 
 	case ir.OMAPLIT:
diff --git a/src/cmd/compile/internal/syntax/parser.go b/src/cmd/compile/internal/syntax/parser.go
index e7b8840..acffd84 100644
--- a/src/cmd/compile/internal/syntax/parser.go
+++ b/src/cmd/compile/internal/syntax/parser.go
@@ -604,7 +604,7 @@
 			} else {
 				// x is the array length expression
 				if debug && x == nil {
-					panic("internal error: nil expression")
+					panic("length expression is nil")
 				}
 				d.Type = p.arrayType(pos, x)
 			}
@@ -1100,7 +1100,7 @@
 					complit_ok = true
 				}
 			case *IndexExpr:
-				if p.xnest >= 0 {
+				if p.xnest >= 0 && !isValue(t) {
 					// x is possibly a composite literal type
 					complit_ok = true
 				}
@@ -1127,6 +1127,21 @@
 	return x
 }
 
+// isValue reports whether x syntactically must be a value (and not a type) expression.
+func isValue(x Expr) bool {
+	switch x := x.(type) {
+	case *BasicLit, *CompositeLit, *FuncLit, *SliceExpr, *AssertExpr, *TypeSwitchGuard, *CallExpr:
+		return true
+	case *Operation:
+		return x.Op != Mul || x.Y != nil // *T may be a type
+	case *ParenExpr:
+		return isValue(x.X)
+	case *IndexExpr:
+		return isValue(x.X) || isValue(x.Index)
+	}
+	return false
+}
+
 // Element = Expression | LiteralValue .
 func (p *parser) bare_complitexpr() Expr {
 	if trace {
@@ -1443,6 +1458,18 @@
 				}
 				return false
 			}
+
+		default:
+			if p.mode&AllowGenerics != 0 {
+				pos := p.pos()
+				if t := p.typeOrNil(); t != nil {
+					f := new(Field)
+					f.pos = pos
+					f.Type = t
+					typ.MethodList = append(typ.MethodList, p.embeddedElem(f))
+					return false
+				}
+			}
 		}
 
 		if p.mode&AllowGenerics != 0 {
diff --git a/src/cmd/compile/internal/syntax/positions.go b/src/cmd/compile/internal/syntax/positions.go
index b00f86c..9359655 100644
--- a/src/cmd/compile/internal/syntax/positions.go
+++ b/src/cmd/compile/internal/syntax/positions.go
@@ -12,7 +12,7 @@
 	for m := n; ; {
 		switch n := m.(type) {
 		case nil:
-			panic("internal error: nil")
+			panic("nil node")
 
 		// packages
 		case *File:
@@ -124,7 +124,7 @@
 	for m := n; ; {
 		switch n := m.(type) {
 		case nil:
-			panic("internal error: nil")
+			panic("nil node")
 
 		// packages
 		case *File:
diff --git a/src/cmd/compile/internal/syntax/testdata/go2/linalg.go2 b/src/cmd/compile/internal/syntax/testdata/go2/linalg.go2
index 0d27603..822d028 100644
--- a/src/cmd/compile/internal/syntax/testdata/go2/linalg.go2
+++ b/src/cmd/compile/internal/syntax/testdata/go2/linalg.go2
@@ -9,10 +9,10 @@
 // Numeric is type bound that matches any numeric type.
 // It would likely be in a constraints package in the standard library.
 type Numeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		complex64, complex128
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		float32 | ~float64 |
+		complex64 | ~complex128
 }
 
 func DotProduct[T Numeric](s1, s2 []T) T {
@@ -42,14 +42,14 @@
 
 // OrderedNumeric is a type bound that matches numeric types that support the < operator.
 type OrderedNumeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		float32 | ~float64
 }
 
 // Complex is a type bound that matches the two complex types, which do not have a < operator.
 type Complex interface {
-	type complex64, complex128
+	~complex64 | ~complex128
 }
 
 // OrderedAbs is a helper type that defines an Abs method for
diff --git a/src/cmd/compile/internal/syntax/testdata/go2/smoketest.go2 b/src/cmd/compile/internal/syntax/testdata/go2/smoketest.go2
index e5cfba0..42efb42 100644
--- a/src/cmd/compile/internal/syntax/testdata/go2/smoketest.go2
+++ b/src/cmd/compile/internal/syntax/testdata/go2/smoketest.go2
@@ -46,12 +46,12 @@
 // interfaces
 type _ interface{
 	m()
-	type int
+	~int
 }
 
 type _ interface{
-	type int, float, string
-	type complex128
+	~int | ~float | ~string
+	~complex128
 	underlying(underlying underlying) underlying
 }
 
diff --git a/src/cmd/compile/internal/syntax/testdata/go2/typeinst2.go2 b/src/cmd/compile/internal/syntax/testdata/go2/typeinst2.go2
index 6e2104a..f3deb70 100644
--- a/src/cmd/compile/internal/syntax/testdata/go2/typeinst2.go2
+++ b/src/cmd/compile/internal/syntax/testdata/go2/typeinst2.go2
@@ -175,12 +175,12 @@
 // Interface type lists can contain any type, incl. *Named types.
 // Verify that we use the underlying type to compute the operational type.
 type MyInt int
-func add1[T interface{type MyInt}](x T) T {
+func add1[T interface{ ~MyInt }](x T) T {
 	return x + 1
 }
 
 type MyString string
-func double[T interface{type MyInt, MyString}](x T) T {
+func double[T interface{ ~MyInt | ~MyString }](x T) T {
 	return x + x
 }
 
@@ -189,15 +189,15 @@
 // type lists.
 
 type E0 interface {
-	type int, bool, string
+	~int | ~bool | ~string
 }
 
 type E1 interface {
-	type int, float64, string
+	~int | ~float64 | ~string
 }
 
 type E2 interface {
-	type float64
+	~float64
 }
 
 type I0 interface {
diff --git a/src/cmd/compile/internal/syntax/testdata/go2/typeparams.go2 b/src/cmd/compile/internal/syntax/testdata/go2/typeparams.go2
index f78037f..111f7c1 100644
--- a/src/cmd/compile/internal/syntax/testdata/go2/typeparams.go2
+++ b/src/cmd/compile/internal/syntax/testdata/go2/typeparams.go2
@@ -48,22 +48,22 @@
 
 type F[A, B any] func(A, B) (B, A)
 
-func min[T interface{ type int }](x, y T) T {
+func min[T interface{ ~int }](x, y T) T {
         if x < y {
                 return x
         }
         return y
 }
 
-func _[T interface{type int, float32}](x, y T) bool { return x < y }
+func _[T interface{ ~int | ~float32 }](x, y T) bool { return x < y }
 func _[T any](x, y T) bool { return x /* ERROR cannot compare */ < y }
-func _[T interface{type int, float32, bool}](x, y T) bool { return x /* ERROR cannot compare */ < y }
+func _[T interface{ ~int | ~float32 | ~bool }](x, y T) bool { return x /* ERROR cannot compare */ < y }
 
 func _[T C1[T]](x, y T) bool { return x /* ERROR cannot compare */ < y }
 func _[T C2[T]](x, y T) bool { return x < y }
 
 type C1[T any] interface{}
-type C2[T any] interface{ type int, float32 }
+type C2[T any] interface{ ~int | ~float32 }
 
 func new[T any]() *T {
         var x T
@@ -91,40 +91,40 @@
 // indexing
 
 func _[T any] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type int }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type string }] (x T, i int) { _ = x[i] }
-func _[T interface{ type []int }] (x T, i int) { _ = x[i] }
-func _[T interface{ type [10]int, *[20]int, map[string]int }] (x T, i int) { _ = x[i] }
-func _[T interface{ type string, []byte }] (x T, i int) { _ = x[i] }
-func _[T interface{ type []int, [1]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type string, []rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~int }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~string }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[]int }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[10]int | ~*[20]int | ~map[string]int }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~string | ~[]byte }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[]int | ~[1]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~string | ~[]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
 
 // slicing
 // TODO(gri) implement this
 
-func _[T interface{ type string }] (x T, i, j, k int) { _ = x /* ERROR invalid operation */ [i:j:k] }
+func _[T interface{ ~string }] (x T, i, j, k int) { _ = x /* ERROR invalid operation */ [i:j:k] }
 
 // len/cap built-ins
 
 func _[T any](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string, []byte, int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string }](x T) { _ = len(x) }
-func _[T interface{ type [10]int }](x T) { _ = len(x) }
-func _[T interface{ type []byte }](x T) { _ = len(x) }
-func _[T interface{ type map[int]int }](x T) { _ = len(x) }
-func _[T interface{ type chan int }](x T) { _ = len(x) }
-func _[T interface{ type string, []byte, chan int }](x T) { _ = len(x) }
+func _[T interface{ ~int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string | ~[]byte | ~int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string }](x T) { _ = len(x) }
+func _[T interface{ ~[10]int }](x T) { _ = len(x) }
+func _[T interface{ ~[]byte }](x T) { _ = len(x) }
+func _[T interface{ ~map[int]int }](x T) { _ = len(x) }
+func _[T interface{ ~chan int }](x T) { _ = len(x) }
+func _[T interface{ ~string | ~[]byte | ~chan int }](x T) { _ = len(x) }
 
 func _[T any](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string, []byte, int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type [10]int }](x T) { _ = cap(x) }
-func _[T interface{ type []byte }](x T) { _ = cap(x) }
-func _[T interface{ type map[int]int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type chan int }](x T) { _ = cap(x) }
-func _[T interface{ type []byte, chan int }](x T) { _ = cap(x) }
+func _[T interface{ ~int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string | ~[]byte | ~int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~[10]int }](x T) { _ = cap(x) }
+func _[T interface{ ~[]byte }](x T) { _ = cap(x) }
+func _[T interface{ ~map[int]int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~chan int }](x T) { _ = cap(x) }
+func _[T interface{ ~[]byte | ~chan int }](x T) { _ = cap(x) }
 
 // range iteration
 
@@ -132,7 +132,7 @@
         for range x /* ERROR cannot range */ {}
 }
 
-func _[T interface{ type string, []string }](x T) {
+func _[T interface{ ~string | ~[]string }](x T) {
         for range x {}
         for i := range x { _ = i }
         for i, _ := range x { _ = i }
@@ -144,23 +144,23 @@
 }
 
 
-func _[T interface{ type string, []rune, map[int]rune }](x T) {
+func _[T interface{ ~string | ~[]rune | ~map[int]rune }](x T) {
         for _, e := range x { _ = e }
         for i, e := range x { _ = i; _ = e }
 }
 
-func _[T interface{ type string, []rune, map[string]rune }](x T) {
+func _[T interface{ ~string | ~[]rune | ~map[string]rune }](x T) {
         for _, e := range x { _ = e }
         for i, e := range x /* ERROR must have the same key type */ { _ = e }
 }
 
-func _[T interface{ type string, chan int }](x T) {
+func _[T interface{ ~string | ~chan int }](x T) {
         for range x {}
         for i := range x { _ = i }
         for i, _ := range x { _ = i } // TODO(gri) should get an error here: channels only return one value
 }
 
-func _[T interface{ type string, chan<-int }](x T) {
+func _[T interface{ ~string | ~chan<-int }](x T) {
         for i := range x /* ERROR send-only channel */ { _ = i }
 }
 
@@ -388,7 +388,7 @@
 	}
 }
 
-func _[T interface{type int}](x T) {
+func _[T interface{ ~int }](x T) {
 	_ = x /* ERROR not an interface */ .(int)
 	switch x /* ERROR not an interface */ .(type) {
 	}
diff --git a/src/cmd/compile/internal/syntax/testdata/interface.go2 b/src/cmd/compile/internal/syntax/testdata/interface.go2
index a817327..b399d75 100644
--- a/src/cmd/compile/internal/syntax/testdata/interface.go2
+++ b/src/cmd/compile/internal/syntax/testdata/interface.go2
@@ -25,7 +25,6 @@
 	~int | ~string
 }
 
-
 type _ interface {
 	m()
 	~int
@@ -34,3 +33,48 @@
 	~int | ~string
 	type bool, int, float64
 }
+
+type _ interface {
+	int
+	[]byte
+	[10]int
+	struct{}
+	*int
+	func()
+	interface{}
+	map[string]int
+	chan T
+	chan<- T
+	<-chan T
+	T[int]
+}
+
+type _ interface {
+	int | string
+	[]byte | string
+	[10]int | string
+	struct{} | string
+	*int | string
+	func() | string
+	interface{} | string
+	map[string]int | string
+	chan T | string
+	chan<- T | string
+	<-chan T | string
+	T[int] | string
+}
+
+type _ interface {
+	~int | string
+	~[]byte | string
+	~[10]int | string
+	~struct{} | string
+	~*int | string
+	~func() | string
+	~interface{} | string
+	~map[string]int | string
+	~chan T | string
+	~chan<- T | string
+	~<-chan T | string
+	~T[int] | string
+}
diff --git a/src/cmd/compile/internal/syntax/testdata/issue46558.src b/src/cmd/compile/internal/syntax/testdata/issue46558.src
new file mode 100644
index 0000000..a22b600
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/testdata/issue46558.src
@@ -0,0 +1,14 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func F(s string) {
+	switch s[0] {
+	case 'a':
+		case s[2] { // ERROR unexpected {
+		case 'b':
+		}
+	}
+} // ERROR non-declaration statement
diff --git a/src/cmd/compile/internal/syntax/walk.go b/src/cmd/compile/internal/syntax/walk.go
index c26e97a..b025844 100644
--- a/src/cmd/compile/internal/syntax/walk.go
+++ b/src/cmd/compile/internal/syntax/walk.go
@@ -8,31 +8,73 @@
 
 import "fmt"
 
-// Walk traverses a syntax in pre-order: It starts by calling f(root);
-// root must not be nil. If f returns false (== "continue"), Walk calls
+// Inspect traverses an AST in pre-order: It starts by calling
+// f(node); node must not be nil. If f returns true, Inspect invokes f
+// recursively for each of the non-nil children of node, followed by a
+// call of f(nil).
+//
+// See Walk for caveats about shared nodes.
+func Inspect(root Node, f func(Node) bool) {
+	Walk(root, inspector(f))
+}
+
+type inspector func(Node) bool
+
+func (v inspector) Visit(node Node) Visitor {
+	if v(node) {
+		return v
+	}
+	return nil
+}
+
+// Crawl traverses a syntax in pre-order: It starts by calling f(root);
+// root must not be nil. If f returns false (== "continue"), Crawl calls
 // f recursively for each of the non-nil children of that node; if f
-// returns true (== "stop"), Walk does not traverse the respective node's
+// returns true (== "stop"), Crawl does not traverse the respective node's
 // children.
+//
+// See Walk for caveats about shared nodes.
+//
+// Deprecated: Use Inspect instead.
+func Crawl(root Node, f func(Node) bool) {
+	Inspect(root, func(node Node) bool {
+		return node != nil && !f(node)
+	})
+}
+
+// Walk traverses an AST in pre-order: It starts by calling
+// v.Visit(node); node must not be nil. If the visitor w returned by
+// v.Visit(node) is not nil, Walk is invoked recursively with visitor
+// w for each of the non-nil children of node, followed by a call of
+// w.Visit(nil).
+//
 // Some nodes may be shared among multiple parent nodes (e.g., types in
 // field lists such as type T in "a, b, c T"). Such shared nodes are
 // walked multiple times.
 // TODO(gri) Revisit this design. It may make sense to walk those nodes
 //           only once. A place where this matters is types2.TestResolveIdents.
-func Walk(root Node, f func(Node) bool) {
-	w := walker{f}
-	w.node(root)
+func Walk(root Node, v Visitor) {
+	walker{v}.node(root)
+}
+
+// A Visitor's Visit method is invoked for each node encountered by Walk.
+// If the result visitor w is not nil, Walk visits each of the children
+// of node with the visitor w, followed by a call of w.Visit(nil).
+type Visitor interface {
+	Visit(node Node) (w Visitor)
 }
 
 type walker struct {
-	f func(Node) bool
+	v Visitor
 }
 
-func (w *walker) node(n Node) {
+func (w walker) node(n Node) {
 	if n == nil {
-		panic("invalid syntax tree: nil node")
+		panic("nil node")
 	}
 
-	if w.f(n) {
+	w.v = w.v.Visit(n)
+	if w.v == nil {
 		return
 	}
 
@@ -285,33 +327,35 @@
 	default:
 		panic(fmt.Sprintf("internal error: unknown node type %T", n))
 	}
+
+	w.v.Visit(nil)
 }
 
-func (w *walker) declList(list []Decl) {
+func (w walker) declList(list []Decl) {
 	for _, n := range list {
 		w.node(n)
 	}
 }
 
-func (w *walker) exprList(list []Expr) {
+func (w walker) exprList(list []Expr) {
 	for _, n := range list {
 		w.node(n)
 	}
 }
 
-func (w *walker) stmtList(list []Stmt) {
+func (w walker) stmtList(list []Stmt) {
 	for _, n := range list {
 		w.node(n)
 	}
 }
 
-func (w *walker) nameList(list []*Name) {
+func (w walker) nameList(list []*Name) {
 	for _, n := range list {
 		w.node(n)
 	}
 }
 
-func (w *walker) fieldList(list []*Field) {
+func (w walker) fieldList(list []*Field) {
 	for _, n := range list {
 		w.node(n)
 	}
diff --git a/src/cmd/compile/internal/test/abiutils_test.go b/src/cmd/compile/internal/test/abiutils_test.go
index b752c48..839546b 100644
--- a/src/cmd/compile/internal/test/abiutils_test.go
+++ b/src/cmd/compile/internal/test/abiutils_test.go
@@ -33,6 +33,8 @@
 	base.Ctxt.DiagFunc = base.Errorf
 	base.Ctxt.DiagFlush = base.FlushErrors
 	base.Ctxt.Bso = bufio.NewWriter(os.Stdout)
+	types.LocalPkg = types.NewPkg("", "local")
+	types.LocalPkg.Prefix = `""`
 	types.PtrSize = ssagen.Arch.LinkArch.PtrSize
 	types.RegSize = ssagen.Arch.LinkArch.RegSize
 	typecheck.InitUniverse()
@@ -309,8 +311,8 @@
 	ei := types.Types[types.TINTER] // interface{}
 	pei := types.NewPtr(ei)         // *interface{}
 	fldt := mkFuncType(types.FakeRecvType(), []*types.Type{},
-		[]*types.Type{types.UntypedString})
-	field := types.NewField(src.NoXPos, nil, fldt)
+		[]*types.Type{types.Types[types.TSTRING]})
+	field := types.NewField(src.NoXPos, typecheck.Lookup("F"), fldt)
 	nei := types.NewInterface(types.LocalPkg, []*types.Field{field})
 	i16 := types.Types[types.TINT16]
 	tb := types.Types[types.TBOOL]
@@ -322,12 +324,12 @@
         IN 0: R{ I0 I1 I2 } spilloffset: 0 typ: struct { int16; int16; bool }
         IN 1: R{ I3 I4 } spilloffset: 8 typ: interface {}
         IN 2: R{ I5 I6 } spilloffset: 24 typ: interface {}
-        IN 3: R{ I7 I8 } spilloffset: 40 typ: interface { () untyped string }
+        IN 3: R{ I7 I8 } spilloffset: 40 typ: interface { F() string }
         IN 4: R{ } offset: 0 typ: *interface {}
-        IN 5: R{ } offset: 8 typ: interface { () untyped string }
+        IN 5: R{ } offset: 8 typ: interface { F() string }
         IN 6: R{ } offset: 24 typ: int16
         OUT 0: R{ I0 I1 } spilloffset: -1 typ: interface {}
-        OUT 1: R{ I2 I3 } spilloffset: -1 typ: interface { () untyped string }
+        OUT 1: R{ I2 I3 } spilloffset: -1 typ: interface { F() string }
         OUT 2: R{ I4 } spilloffset: -1 typ: *interface {}
         offsetToSpillArea: 32 spillAreaSize: 56
 `)
diff --git a/src/cmd/compile/internal/test/inl_test.go b/src/cmd/compile/internal/test/inl_test.go
index 6f10003..bbdbe0c 100644
--- a/src/cmd/compile/internal/test/inl_test.go
+++ b/src/cmd/compile/internal/test/inl_test.go
@@ -42,13 +42,10 @@
 			"bucketMask",
 			"bucketShift",
 			"chanbuf",
-			"deferArgs",
-			"deferclass",
 			"evacuated",
 			"fastlog2",
 			"fastrand",
 			"float64bits",
-			"funcPC",
 			"getArgInfoFast",
 			"getm",
 			"getMCache",
@@ -65,7 +62,6 @@
 			"subtract1",
 			"subtractb",
 			"tophash",
-			"totaldefersize",
 			"(*bmap).keys",
 			"(*bmap).overflow",
 			"(*waitq).enqueue",
diff --git a/src/cmd/compile/internal/typecheck/bexport.go b/src/cmd/compile/internal/typecheck/bexport.go
index 4a84bb1..cc7f91f9 100644
--- a/src/cmd/compile/internal/typecheck/bexport.go
+++ b/src/cmd/compile/internal/typecheck/bexport.go
@@ -96,6 +96,9 @@
 
 			// any type, for builtin export data
 			types.Types[types.TANY],
+
+			// comparable
+			types.ComparableType,
 		}
 	}
 	return predecl
diff --git a/src/cmd/compile/internal/typecheck/builtin.go b/src/cmd/compile/internal/typecheck/builtin.go
index 833b17b..3f177d9 100644
--- a/src/cmd/compile/internal/typecheck/builtin.go
+++ b/src/cmd/compile/internal/typecheck/builtin.go
@@ -71,137 +71,135 @@
 	{"slicecopy", funcTag, 54},
 	{"decoderune", funcTag, 55},
 	{"countrunes", funcTag, 56},
-	{"convI2I", funcTag, 57},
-	{"convT16", funcTag, 59},
-	{"convT32", funcTag, 61},
-	{"convT64", funcTag, 62},
-	{"convTstring", funcTag, 63},
-	{"convTslice", funcTag, 66},
-	{"convT2E", funcTag, 67},
-	{"convT2Enoptr", funcTag, 67},
-	{"convT2I", funcTag, 67},
-	{"convT2Inoptr", funcTag, 67},
-	{"assertE2I", funcTag, 68},
-	{"assertE2I2", funcTag, 57},
-	{"assertI2I", funcTag, 68},
-	{"assertI2I2", funcTag, 57},
-	{"panicdottypeE", funcTag, 69},
-	{"panicdottypeI", funcTag, 69},
-	{"panicnildottype", funcTag, 70},
-	{"ifaceeq", funcTag, 72},
-	{"efaceeq", funcTag, 72},
-	{"fastrand", funcTag, 73},
-	{"makemap64", funcTag, 75},
-	{"makemap", funcTag, 76},
-	{"makemap_small", funcTag, 77},
-	{"mapaccess1", funcTag, 78},
-	{"mapaccess1_fast32", funcTag, 79},
-	{"mapaccess1_fast64", funcTag, 80},
-	{"mapaccess1_faststr", funcTag, 81},
-	{"mapaccess1_fat", funcTag, 82},
-	{"mapaccess2", funcTag, 83},
-	{"mapaccess2_fast32", funcTag, 84},
-	{"mapaccess2_fast64", funcTag, 85},
-	{"mapaccess2_faststr", funcTag, 86},
-	{"mapaccess2_fat", funcTag, 87},
-	{"mapassign", funcTag, 78},
-	{"mapassign_fast32", funcTag, 79},
-	{"mapassign_fast32ptr", funcTag, 88},
-	{"mapassign_fast64", funcTag, 80},
-	{"mapassign_fast64ptr", funcTag, 88},
-	{"mapassign_faststr", funcTag, 81},
-	{"mapiterinit", funcTag, 89},
-	{"mapdelete", funcTag, 89},
-	{"mapdelete_fast32", funcTag, 90},
-	{"mapdelete_fast64", funcTag, 91},
-	{"mapdelete_faststr", funcTag, 92},
-	{"mapiternext", funcTag, 93},
-	{"mapclear", funcTag, 94},
-	{"makechan64", funcTag, 96},
-	{"makechan", funcTag, 97},
-	{"chanrecv1", funcTag, 99},
-	{"chanrecv2", funcTag, 100},
-	{"chansend1", funcTag, 102},
+	{"convI2I", funcTag, 58},
+	{"convT", funcTag, 59},
+	{"convTnoptr", funcTag, 59},
+	{"convT16", funcTag, 61},
+	{"convT32", funcTag, 63},
+	{"convT64", funcTag, 64},
+	{"convTstring", funcTag, 65},
+	{"convTslice", funcTag, 68},
+	{"assertE2I", funcTag, 69},
+	{"assertE2I2", funcTag, 70},
+	{"assertI2I", funcTag, 69},
+	{"assertI2I2", funcTag, 70},
+	{"panicdottypeE", funcTag, 71},
+	{"panicdottypeI", funcTag, 71},
+	{"panicnildottype", funcTag, 72},
+	{"ifaceeq", funcTag, 73},
+	{"efaceeq", funcTag, 73},
+	{"fastrand", funcTag, 74},
+	{"makemap64", funcTag, 76},
+	{"makemap", funcTag, 77},
+	{"makemap_small", funcTag, 78},
+	{"mapaccess1", funcTag, 79},
+	{"mapaccess1_fast32", funcTag, 80},
+	{"mapaccess1_fast64", funcTag, 81},
+	{"mapaccess1_faststr", funcTag, 82},
+	{"mapaccess1_fat", funcTag, 83},
+	{"mapaccess2", funcTag, 84},
+	{"mapaccess2_fast32", funcTag, 85},
+	{"mapaccess2_fast64", funcTag, 86},
+	{"mapaccess2_faststr", funcTag, 87},
+	{"mapaccess2_fat", funcTag, 88},
+	{"mapassign", funcTag, 79},
+	{"mapassign_fast32", funcTag, 80},
+	{"mapassign_fast32ptr", funcTag, 89},
+	{"mapassign_fast64", funcTag, 81},
+	{"mapassign_fast64ptr", funcTag, 89},
+	{"mapassign_faststr", funcTag, 82},
+	{"mapiterinit", funcTag, 90},
+	{"mapdelete", funcTag, 90},
+	{"mapdelete_fast32", funcTag, 91},
+	{"mapdelete_fast64", funcTag, 92},
+	{"mapdelete_faststr", funcTag, 93},
+	{"mapiternext", funcTag, 94},
+	{"mapclear", funcTag, 95},
+	{"makechan64", funcTag, 97},
+	{"makechan", funcTag, 98},
+	{"chanrecv1", funcTag, 100},
+	{"chanrecv2", funcTag, 101},
+	{"chansend1", funcTag, 103},
 	{"closechan", funcTag, 30},
-	{"writeBarrier", varTag, 104},
-	{"typedmemmove", funcTag, 105},
-	{"typedmemclr", funcTag, 106},
-	{"typedslicecopy", funcTag, 107},
-	{"selectnbsend", funcTag, 108},
-	{"selectnbrecv", funcTag, 109},
-	{"selectsetpc", funcTag, 110},
-	{"selectgo", funcTag, 111},
+	{"writeBarrier", varTag, 105},
+	{"typedmemmove", funcTag, 106},
+	{"typedmemclr", funcTag, 107},
+	{"typedslicecopy", funcTag, 108},
+	{"selectnbsend", funcTag, 109},
+	{"selectnbrecv", funcTag, 110},
+	{"selectsetpc", funcTag, 111},
+	{"selectgo", funcTag, 112},
 	{"block", funcTag, 9},
-	{"makeslice", funcTag, 112},
-	{"makeslice64", funcTag, 113},
-	{"makeslicecopy", funcTag, 114},
-	{"growslice", funcTag, 116},
-	{"unsafeslice", funcTag, 117},
-	{"unsafeslice64", funcTag, 118},
-	{"unsafeslicecheckptr", funcTag, 118},
-	{"memmove", funcTag, 119},
-	{"memclrNoHeapPointers", funcTag, 120},
-	{"memclrHasPointers", funcTag, 120},
-	{"memequal", funcTag, 121},
-	{"memequal0", funcTag, 122},
-	{"memequal8", funcTag, 122},
-	{"memequal16", funcTag, 122},
-	{"memequal32", funcTag, 122},
-	{"memequal64", funcTag, 122},
-	{"memequal128", funcTag, 122},
-	{"f32equal", funcTag, 123},
-	{"f64equal", funcTag, 123},
-	{"c64equal", funcTag, 123},
-	{"c128equal", funcTag, 123},
-	{"strequal", funcTag, 123},
-	{"interequal", funcTag, 123},
-	{"nilinterequal", funcTag, 123},
-	{"memhash", funcTag, 124},
-	{"memhash0", funcTag, 125},
-	{"memhash8", funcTag, 125},
-	{"memhash16", funcTag, 125},
-	{"memhash32", funcTag, 125},
-	{"memhash64", funcTag, 125},
-	{"memhash128", funcTag, 125},
-	{"f32hash", funcTag, 125},
-	{"f64hash", funcTag, 125},
-	{"c64hash", funcTag, 125},
-	{"c128hash", funcTag, 125},
-	{"strhash", funcTag, 125},
-	{"interhash", funcTag, 125},
-	{"nilinterhash", funcTag, 125},
-	{"int64div", funcTag, 126},
-	{"uint64div", funcTag, 127},
-	{"int64mod", funcTag, 126},
-	{"uint64mod", funcTag, 127},
-	{"float64toint64", funcTag, 128},
-	{"float64touint64", funcTag, 129},
-	{"float64touint32", funcTag, 130},
-	{"int64tofloat64", funcTag, 131},
-	{"uint64tofloat64", funcTag, 132},
-	{"uint32tofloat64", funcTag, 133},
-	{"complex128div", funcTag, 134},
-	{"getcallerpc", funcTag, 135},
-	{"getcallersp", funcTag, 135},
+	{"makeslice", funcTag, 113},
+	{"makeslice64", funcTag, 114},
+	{"makeslicecopy", funcTag, 115},
+	{"growslice", funcTag, 117},
+	{"unsafeslice", funcTag, 118},
+	{"unsafeslice64", funcTag, 119},
+	{"unsafeslicecheckptr", funcTag, 119},
+	{"memmove", funcTag, 120},
+	{"memclrNoHeapPointers", funcTag, 121},
+	{"memclrHasPointers", funcTag, 121},
+	{"memequal", funcTag, 122},
+	{"memequal0", funcTag, 123},
+	{"memequal8", funcTag, 123},
+	{"memequal16", funcTag, 123},
+	{"memequal32", funcTag, 123},
+	{"memequal64", funcTag, 123},
+	{"memequal128", funcTag, 123},
+	{"f32equal", funcTag, 124},
+	{"f64equal", funcTag, 124},
+	{"c64equal", funcTag, 124},
+	{"c128equal", funcTag, 124},
+	{"strequal", funcTag, 124},
+	{"interequal", funcTag, 124},
+	{"nilinterequal", funcTag, 124},
+	{"memhash", funcTag, 125},
+	{"memhash0", funcTag, 126},
+	{"memhash8", funcTag, 126},
+	{"memhash16", funcTag, 126},
+	{"memhash32", funcTag, 126},
+	{"memhash64", funcTag, 126},
+	{"memhash128", funcTag, 126},
+	{"f32hash", funcTag, 126},
+	{"f64hash", funcTag, 126},
+	{"c64hash", funcTag, 126},
+	{"c128hash", funcTag, 126},
+	{"strhash", funcTag, 126},
+	{"interhash", funcTag, 126},
+	{"nilinterhash", funcTag, 126},
+	{"int64div", funcTag, 127},
+	{"uint64div", funcTag, 128},
+	{"int64mod", funcTag, 127},
+	{"uint64mod", funcTag, 128},
+	{"float64toint64", funcTag, 129},
+	{"float64touint64", funcTag, 130},
+	{"float64touint32", funcTag, 131},
+	{"int64tofloat64", funcTag, 132},
+	{"uint64tofloat64", funcTag, 133},
+	{"uint32tofloat64", funcTag, 134},
+	{"complex128div", funcTag, 135},
+	{"getcallerpc", funcTag, 136},
+	{"getcallersp", funcTag, 136},
 	{"racefuncenter", funcTag, 31},
 	{"racefuncexit", funcTag, 9},
 	{"raceread", funcTag, 31},
 	{"racewrite", funcTag, 31},
-	{"racereadrange", funcTag, 136},
-	{"racewriterange", funcTag, 136},
-	{"msanread", funcTag, 136},
-	{"msanwrite", funcTag, 136},
-	{"msanmove", funcTag, 137},
-	{"checkptrAlignment", funcTag, 138},
-	{"checkptrArithmetic", funcTag, 140},
-	{"libfuzzerTraceCmp1", funcTag, 141},
-	{"libfuzzerTraceCmp2", funcTag, 142},
-	{"libfuzzerTraceCmp4", funcTag, 143},
-	{"libfuzzerTraceCmp8", funcTag, 144},
-	{"libfuzzerTraceConstCmp1", funcTag, 141},
-	{"libfuzzerTraceConstCmp2", funcTag, 142},
-	{"libfuzzerTraceConstCmp4", funcTag, 143},
-	{"libfuzzerTraceConstCmp8", funcTag, 144},
+	{"racereadrange", funcTag, 137},
+	{"racewriterange", funcTag, 137},
+	{"msanread", funcTag, 137},
+	{"msanwrite", funcTag, 137},
+	{"msanmove", funcTag, 138},
+	{"checkptrAlignment", funcTag, 139},
+	{"checkptrArithmetic", funcTag, 141},
+	{"libfuzzerTraceCmp1", funcTag, 142},
+	{"libfuzzerTraceCmp2", funcTag, 143},
+	{"libfuzzerTraceCmp4", funcTag, 144},
+	{"libfuzzerTraceCmp8", funcTag, 145},
+	{"libfuzzerTraceConstCmp1", funcTag, 142},
+	{"libfuzzerTraceConstCmp2", funcTag, 143},
+	{"libfuzzerTraceConstCmp4", funcTag, 144},
+	{"libfuzzerTraceConstCmp8", funcTag, 145},
 	{"x86HasPOPCNT", varTag, 6},
 	{"x86HasSSE41", varTag, 6},
 	{"x86HasFMA", varTag, 6},
@@ -224,7 +222,7 @@
 }
 
 func runtimeTypes() []*types.Type {
-	var typs [145]*types.Type
+	var typs [146]*types.Type
 	typs[0] = types.ByteType
 	typs[1] = types.NewPtr(typs[0])
 	typs[2] = types.Types[types.TANY]
@@ -282,93 +280,94 @@
 	typs[54] = newSig(params(typs[3], typs[15], typs[3], typs[15], typs[5]), params(typs[15]))
 	typs[55] = newSig(params(typs[28], typs[15]), params(typs[46], typs[15]))
 	typs[56] = newSig(params(typs[28]), params(typs[15]))
-	typs[57] = newSig(params(typs[1], typs[2]), params(typs[2]))
-	typs[58] = types.Types[types.TUINT16]
-	typs[59] = newSig(params(typs[58]), params(typs[7]))
-	typs[60] = types.Types[types.TUINT32]
+	typs[57] = types.NewPtr(typs[5])
+	typs[58] = newSig(params(typs[1], typs[57]), params(typs[57]))
+	typs[59] = newSig(params(typs[1], typs[3]), params(typs[7]))
+	typs[60] = types.Types[types.TUINT16]
 	typs[61] = newSig(params(typs[60]), params(typs[7]))
-	typs[62] = newSig(params(typs[24]), params(typs[7]))
-	typs[63] = newSig(params(typs[28]), params(typs[7]))
-	typs[64] = types.Types[types.TUINT8]
-	typs[65] = types.NewSlice(typs[64])
-	typs[66] = newSig(params(typs[65]), params(typs[7]))
-	typs[67] = newSig(params(typs[1], typs[3]), params(typs[2]))
-	typs[68] = newSig(params(typs[1], typs[1]), params(typs[1]))
-	typs[69] = newSig(params(typs[1], typs[1], typs[1]), nil)
-	typs[70] = newSig(params(typs[1]), nil)
-	typs[71] = types.NewPtr(typs[5])
-	typs[72] = newSig(params(typs[71], typs[7], typs[7]), params(typs[6]))
-	typs[73] = newSig(nil, params(typs[60]))
-	typs[74] = types.NewMap(typs[2], typs[2])
-	typs[75] = newSig(params(typs[1], typs[22], typs[3]), params(typs[74]))
-	typs[76] = newSig(params(typs[1], typs[15], typs[3]), params(typs[74]))
-	typs[77] = newSig(nil, params(typs[74]))
-	typs[78] = newSig(params(typs[1], typs[74], typs[3]), params(typs[3]))
-	typs[79] = newSig(params(typs[1], typs[74], typs[60]), params(typs[3]))
-	typs[80] = newSig(params(typs[1], typs[74], typs[24]), params(typs[3]))
-	typs[81] = newSig(params(typs[1], typs[74], typs[28]), params(typs[3]))
-	typs[82] = newSig(params(typs[1], typs[74], typs[3], typs[1]), params(typs[3]))
-	typs[83] = newSig(params(typs[1], typs[74], typs[3]), params(typs[3], typs[6]))
-	typs[84] = newSig(params(typs[1], typs[74], typs[60]), params(typs[3], typs[6]))
-	typs[85] = newSig(params(typs[1], typs[74], typs[24]), params(typs[3], typs[6]))
-	typs[86] = newSig(params(typs[1], typs[74], typs[28]), params(typs[3], typs[6]))
-	typs[87] = newSig(params(typs[1], typs[74], typs[3], typs[1]), params(typs[3], typs[6]))
-	typs[88] = newSig(params(typs[1], typs[74], typs[7]), params(typs[3]))
-	typs[89] = newSig(params(typs[1], typs[74], typs[3]), nil)
-	typs[90] = newSig(params(typs[1], typs[74], typs[60]), nil)
-	typs[91] = newSig(params(typs[1], typs[74], typs[24]), nil)
-	typs[92] = newSig(params(typs[1], typs[74], typs[28]), nil)
-	typs[93] = newSig(params(typs[3]), nil)
-	typs[94] = newSig(params(typs[1], typs[74]), nil)
-	typs[95] = types.NewChan(typs[2], types.Cboth)
-	typs[96] = newSig(params(typs[1], typs[22]), params(typs[95]))
-	typs[97] = newSig(params(typs[1], typs[15]), params(typs[95]))
-	typs[98] = types.NewChan(typs[2], types.Crecv)
-	typs[99] = newSig(params(typs[98], typs[3]), nil)
-	typs[100] = newSig(params(typs[98], typs[3]), params(typs[6]))
-	typs[101] = types.NewChan(typs[2], types.Csend)
-	typs[102] = newSig(params(typs[101], typs[3]), nil)
-	typs[103] = types.NewArray(typs[0], 3)
-	typs[104] = types.NewStruct(types.NoPkg, []*types.Field{types.NewField(src.NoXPos, Lookup("enabled"), typs[6]), types.NewField(src.NoXPos, Lookup("pad"), typs[103]), types.NewField(src.NoXPos, Lookup("needed"), typs[6]), types.NewField(src.NoXPos, Lookup("cgo"), typs[6]), types.NewField(src.NoXPos, Lookup("alignme"), typs[24])})
-	typs[105] = newSig(params(typs[1], typs[3], typs[3]), nil)
-	typs[106] = newSig(params(typs[1], typs[3]), nil)
-	typs[107] = newSig(params(typs[1], typs[3], typs[15], typs[3], typs[15]), params(typs[15]))
-	typs[108] = newSig(params(typs[101], typs[3]), params(typs[6]))
-	typs[109] = newSig(params(typs[3], typs[98]), params(typs[6], typs[6]))
-	typs[110] = newSig(params(typs[71]), nil)
-	typs[111] = newSig(params(typs[1], typs[1], typs[71], typs[15], typs[15], typs[6]), params(typs[15], typs[6]))
-	typs[112] = newSig(params(typs[1], typs[15], typs[15]), params(typs[7]))
-	typs[113] = newSig(params(typs[1], typs[22], typs[22]), params(typs[7]))
-	typs[114] = newSig(params(typs[1], typs[15], typs[15], typs[7]), params(typs[7]))
-	typs[115] = types.NewSlice(typs[2])
-	typs[116] = newSig(params(typs[1], typs[115], typs[15]), params(typs[115]))
-	typs[117] = newSig(params(typs[1], typs[7], typs[15]), nil)
-	typs[118] = newSig(params(typs[1], typs[7], typs[22]), nil)
-	typs[119] = newSig(params(typs[3], typs[3], typs[5]), nil)
-	typs[120] = newSig(params(typs[7], typs[5]), nil)
-	typs[121] = newSig(params(typs[3], typs[3], typs[5]), params(typs[6]))
-	typs[122] = newSig(params(typs[3], typs[3]), params(typs[6]))
-	typs[123] = newSig(params(typs[7], typs[7]), params(typs[6]))
-	typs[124] = newSig(params(typs[7], typs[5], typs[5]), params(typs[5]))
-	typs[125] = newSig(params(typs[7], typs[5]), params(typs[5]))
-	typs[126] = newSig(params(typs[22], typs[22]), params(typs[22]))
-	typs[127] = newSig(params(typs[24], typs[24]), params(typs[24]))
-	typs[128] = newSig(params(typs[20]), params(typs[22]))
-	typs[129] = newSig(params(typs[20]), params(typs[24]))
-	typs[130] = newSig(params(typs[20]), params(typs[60]))
-	typs[131] = newSig(params(typs[22]), params(typs[20]))
-	typs[132] = newSig(params(typs[24]), params(typs[20]))
-	typs[133] = newSig(params(typs[60]), params(typs[20]))
-	typs[134] = newSig(params(typs[26], typs[26]), params(typs[26]))
-	typs[135] = newSig(nil, params(typs[5]))
-	typs[136] = newSig(params(typs[5], typs[5]), nil)
-	typs[137] = newSig(params(typs[5], typs[5], typs[5]), nil)
-	typs[138] = newSig(params(typs[7], typs[1], typs[5]), nil)
-	typs[139] = types.NewSlice(typs[7])
-	typs[140] = newSig(params(typs[7], typs[139]), nil)
-	typs[141] = newSig(params(typs[64], typs[64]), nil)
-	typs[142] = newSig(params(typs[58], typs[58]), nil)
+	typs[62] = types.Types[types.TUINT32]
+	typs[63] = newSig(params(typs[62]), params(typs[7]))
+	typs[64] = newSig(params(typs[24]), params(typs[7]))
+	typs[65] = newSig(params(typs[28]), params(typs[7]))
+	typs[66] = types.Types[types.TUINT8]
+	typs[67] = types.NewSlice(typs[66])
+	typs[68] = newSig(params(typs[67]), params(typs[7]))
+	typs[69] = newSig(params(typs[1], typs[1]), params(typs[1]))
+	typs[70] = newSig(params(typs[1], typs[2]), params(typs[2]))
+	typs[71] = newSig(params(typs[1], typs[1], typs[1]), nil)
+	typs[72] = newSig(params(typs[1]), nil)
+	typs[73] = newSig(params(typs[57], typs[7], typs[7]), params(typs[6]))
+	typs[74] = newSig(nil, params(typs[62]))
+	typs[75] = types.NewMap(typs[2], typs[2])
+	typs[76] = newSig(params(typs[1], typs[22], typs[3]), params(typs[75]))
+	typs[77] = newSig(params(typs[1], typs[15], typs[3]), params(typs[75]))
+	typs[78] = newSig(nil, params(typs[75]))
+	typs[79] = newSig(params(typs[1], typs[75], typs[3]), params(typs[3]))
+	typs[80] = newSig(params(typs[1], typs[75], typs[62]), params(typs[3]))
+	typs[81] = newSig(params(typs[1], typs[75], typs[24]), params(typs[3]))
+	typs[82] = newSig(params(typs[1], typs[75], typs[28]), params(typs[3]))
+	typs[83] = newSig(params(typs[1], typs[75], typs[3], typs[1]), params(typs[3]))
+	typs[84] = newSig(params(typs[1], typs[75], typs[3]), params(typs[3], typs[6]))
+	typs[85] = newSig(params(typs[1], typs[75], typs[62]), params(typs[3], typs[6]))
+	typs[86] = newSig(params(typs[1], typs[75], typs[24]), params(typs[3], typs[6]))
+	typs[87] = newSig(params(typs[1], typs[75], typs[28]), params(typs[3], typs[6]))
+	typs[88] = newSig(params(typs[1], typs[75], typs[3], typs[1]), params(typs[3], typs[6]))
+	typs[89] = newSig(params(typs[1], typs[75], typs[7]), params(typs[3]))
+	typs[90] = newSig(params(typs[1], typs[75], typs[3]), nil)
+	typs[91] = newSig(params(typs[1], typs[75], typs[62]), nil)
+	typs[92] = newSig(params(typs[1], typs[75], typs[24]), nil)
+	typs[93] = newSig(params(typs[1], typs[75], typs[28]), nil)
+	typs[94] = newSig(params(typs[3]), nil)
+	typs[95] = newSig(params(typs[1], typs[75]), nil)
+	typs[96] = types.NewChan(typs[2], types.Cboth)
+	typs[97] = newSig(params(typs[1], typs[22]), params(typs[96]))
+	typs[98] = newSig(params(typs[1], typs[15]), params(typs[96]))
+	typs[99] = types.NewChan(typs[2], types.Crecv)
+	typs[100] = newSig(params(typs[99], typs[3]), nil)
+	typs[101] = newSig(params(typs[99], typs[3]), params(typs[6]))
+	typs[102] = types.NewChan(typs[2], types.Csend)
+	typs[103] = newSig(params(typs[102], typs[3]), nil)
+	typs[104] = types.NewArray(typs[0], 3)
+	typs[105] = types.NewStruct(types.NoPkg, []*types.Field{types.NewField(src.NoXPos, Lookup("enabled"), typs[6]), types.NewField(src.NoXPos, Lookup("pad"), typs[104]), types.NewField(src.NoXPos, Lookup("needed"), typs[6]), types.NewField(src.NoXPos, Lookup("cgo"), typs[6]), types.NewField(src.NoXPos, Lookup("alignme"), typs[24])})
+	typs[106] = newSig(params(typs[1], typs[3], typs[3]), nil)
+	typs[107] = newSig(params(typs[1], typs[3]), nil)
+	typs[108] = newSig(params(typs[1], typs[3], typs[15], typs[3], typs[15]), params(typs[15]))
+	typs[109] = newSig(params(typs[102], typs[3]), params(typs[6]))
+	typs[110] = newSig(params(typs[3], typs[99]), params(typs[6], typs[6]))
+	typs[111] = newSig(params(typs[57]), nil)
+	typs[112] = newSig(params(typs[1], typs[1], typs[57], typs[15], typs[15], typs[6]), params(typs[15], typs[6]))
+	typs[113] = newSig(params(typs[1], typs[15], typs[15]), params(typs[7]))
+	typs[114] = newSig(params(typs[1], typs[22], typs[22]), params(typs[7]))
+	typs[115] = newSig(params(typs[1], typs[15], typs[15], typs[7]), params(typs[7]))
+	typs[116] = types.NewSlice(typs[2])
+	typs[117] = newSig(params(typs[1], typs[116], typs[15]), params(typs[116]))
+	typs[118] = newSig(params(typs[1], typs[7], typs[15]), nil)
+	typs[119] = newSig(params(typs[1], typs[7], typs[22]), nil)
+	typs[120] = newSig(params(typs[3], typs[3], typs[5]), nil)
+	typs[121] = newSig(params(typs[7], typs[5]), nil)
+	typs[122] = newSig(params(typs[3], typs[3], typs[5]), params(typs[6]))
+	typs[123] = newSig(params(typs[3], typs[3]), params(typs[6]))
+	typs[124] = newSig(params(typs[7], typs[7]), params(typs[6]))
+	typs[125] = newSig(params(typs[7], typs[5], typs[5]), params(typs[5]))
+	typs[126] = newSig(params(typs[7], typs[5]), params(typs[5]))
+	typs[127] = newSig(params(typs[22], typs[22]), params(typs[22]))
+	typs[128] = newSig(params(typs[24], typs[24]), params(typs[24]))
+	typs[129] = newSig(params(typs[20]), params(typs[22]))
+	typs[130] = newSig(params(typs[20]), params(typs[24]))
+	typs[131] = newSig(params(typs[20]), params(typs[62]))
+	typs[132] = newSig(params(typs[22]), params(typs[20]))
+	typs[133] = newSig(params(typs[24]), params(typs[20]))
+	typs[134] = newSig(params(typs[62]), params(typs[20]))
+	typs[135] = newSig(params(typs[26], typs[26]), params(typs[26]))
+	typs[136] = newSig(nil, params(typs[5]))
+	typs[137] = newSig(params(typs[5], typs[5]), nil)
+	typs[138] = newSig(params(typs[5], typs[5], typs[5]), nil)
+	typs[139] = newSig(params(typs[7], typs[1], typs[5]), nil)
+	typs[140] = types.NewSlice(typs[7])
+	typs[141] = newSig(params(typs[7], typs[140]), nil)
+	typs[142] = newSig(params(typs[66], typs[66]), nil)
 	typs[143] = newSig(params(typs[60], typs[60]), nil)
-	typs[144] = newSig(params(typs[24], typs[24]), nil)
+	typs[144] = newSig(params(typs[62], typs[62]), nil)
+	typs[145] = newSig(params(typs[24], typs[24]), nil)
 	return typs[:]
 }
diff --git a/src/cmd/compile/internal/typecheck/builtin/runtime.go b/src/cmd/compile/internal/typecheck/builtin/runtime.go
index 2b29ea3..605b904 100644
--- a/src/cmd/compile/internal/typecheck/builtin/runtime.go
+++ b/src/cmd/compile/internal/typecheck/builtin/runtime.go
@@ -84,10 +84,15 @@
 func countrunes(string) int
 
 // Non-empty-interface to non-empty-interface conversion.
-func convI2I(typ *byte, elem any) (ret any)
+func convI2I(typ *byte, itab *uintptr) (ret *uintptr)
 
-// Specialized type-to-interface conversion.
-// These return only a data pointer.
+// Convert non-interface type to the data word of a (empty or nonempty) interface.
+func convT(typ *byte, elem *any) unsafe.Pointer
+
+// Same as convT, for types with no pointers in them.
+func convTnoptr(typ *byte, elem *any) unsafe.Pointer
+
+// Specialized versions of convT for specific types.
 // These functions take concrete types in the runtime. But they may
 // be used for a wider range of types, which have the same memory
 // layout as the parameter type. The compiler converts the
@@ -99,14 +104,6 @@
 func convTstring(val string) unsafe.Pointer
 func convTslice(val []uint8) unsafe.Pointer
 
-// Type to empty-interface conversion.
-func convT2E(typ *byte, elem *any) (ret any)
-func convT2Enoptr(typ *byte, elem *any) (ret any)
-
-// Type to non-empty-interface conversion.
-func convT2I(tab *byte, elem *any) (ret any)
-func convT2Inoptr(tab *byte, elem *any) (ret any)
-
 // interface type assertions x.(T)
 func assertE2I(inter *byte, typ *byte) *byte
 func assertE2I2(inter *byte, eface any) (ret any)
diff --git a/src/cmd/compile/internal/typecheck/const.go b/src/cmd/compile/internal/typecheck/const.go
index 761b043..f8150d2 100644
--- a/src/cmd/compile/internal/typecheck/const.go
+++ b/src/cmd/compile/internal/typecheck/const.go
@@ -901,7 +901,7 @@
 		switch tsel.Op() {
 		case ir.ODOT, ir.ODOTPTR:
 			break
-		case ir.OCALLPART:
+		case ir.OMETHVALUE:
 			base.Errorf("invalid expression %v: argument is a method value", n)
 			return 0
 		default:
diff --git a/src/cmd/compile/internal/typecheck/crawler.go b/src/cmd/compile/internal/typecheck/crawler.go
new file mode 100644
index 0000000..9a348b9
--- /dev/null
+++ b/src/cmd/compile/internal/typecheck/crawler.go
@@ -0,0 +1,231 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typecheck
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/types"
+)
+
+// crawlExports crawls the type/object graph rooted at the given list
+// of exported objects. Any functions that are found to be potentially
+// callable by importers are marked with ExportInline so that
+// iexport.go knows to re-export their inline body.
+func crawlExports(exports []*ir.Name) {
+	p := crawler{
+		marked:   make(map[*types.Type]bool),
+		embedded: make(map[*types.Type]bool),
+	}
+	for _, n := range exports {
+		p.markObject(n)
+	}
+}
+
+type crawler struct {
+	marked   map[*types.Type]bool // types already seen by markType
+	embedded map[*types.Type]bool // types already seen by markEmbed
+}
+
+// markObject visits a reachable object.
+func (p *crawler) markObject(n *ir.Name) {
+	if n.Op() == ir.ONAME && n.Class == ir.PFUNC {
+		p.markInlBody(n)
+	}
+
+	// If a declared type name is reachable, users can embed it in their
+	// own types, which makes even its unexported methods reachable.
+	if n.Op() == ir.OTYPE {
+		p.markEmbed(n.Type())
+	}
+
+	p.markType(n.Type())
+}
+
+// markType recursively visits types reachable from t to identify
+// functions whose inline bodies may be needed.
+func (p *crawler) markType(t *types.Type) {
+	if t.IsInstantiatedGeneric() {
+		// Re-instantiated types don't add anything new, so don't follow them.
+		return
+	}
+	if p.marked[t] {
+		return
+	}
+	p.marked[t] = true
+
+	// If this is a defined type, mark all of its associated
+	// methods. Skip interface types because t.Methods contains
+	// only their unexpanded method set (i.e., exclusive of
+	// interface embeddings), and the switch statement below
+	// handles their full method set.
+	if t.Sym() != nil && t.Kind() != types.TINTER {
+		for _, m := range t.Methods().Slice() {
+			if types.IsExported(m.Sym.Name) {
+				p.markObject(m.Nname.(*ir.Name))
+			}
+		}
+	}
+
+	// Recursively mark any types that can be produced given a
+	// value of type t: dereferencing a pointer; indexing or
+	// iterating over an array, slice, or map; receiving from a
+	// channel; accessing a struct field or interface method; or
+	// calling a function.
+	//
+	// Notably, we don't mark function parameter types, because
+	// the user already needs some way to construct values of
+	// those types.
+	switch t.Kind() {
+	case types.TPTR, types.TARRAY, types.TSLICE:
+		p.markType(t.Elem())
+
+	case types.TCHAN:
+		if t.ChanDir().CanRecv() {
+			p.markType(t.Elem())
+		}
+
+	case types.TMAP:
+		p.markType(t.Key())
+		p.markType(t.Elem())
+
+	case types.TSTRUCT:
+		for _, f := range t.FieldSlice() {
+			if types.IsExported(f.Sym.Name) || f.Embedded != 0 {
+				p.markType(f.Type)
+			}
+		}
+
+	case types.TFUNC:
+		for _, f := range t.Results().FieldSlice() {
+			p.markType(f.Type)
+		}
+
+	case types.TINTER:
+		// TODO(danscales) - will have to deal with the types in interface
+		// elements here when implemented in types2 and represented in types1.
+		for _, f := range t.AllMethods().Slice() {
+			if types.IsExported(f.Sym.Name) {
+				p.markType(f.Type)
+			}
+		}
+
+	case types.TTYPEPARAM:
+		// No other type that needs to be followed.
+	}
+}
+
+// markEmbed is similar to markType, but handles finding methods that
+// need to be re-exported because t can be embedded in user code
+// (possibly transitively).
+func (p *crawler) markEmbed(t *types.Type) {
+	if t.IsPtr() {
+		// Defined pointer type; not allowed to embed anyway.
+		if t.Sym() != nil {
+			return
+		}
+		t = t.Elem()
+	}
+
+	if t.IsInstantiatedGeneric() {
+		// Re-instantiated types don't add anything new, so don't follow them.
+		return
+	}
+
+	if p.embedded[t] {
+		return
+	}
+	p.embedded[t] = true
+
+	// If t is a defined type, then re-export all of its methods. Unlike
+	// in markType, we include even unexported methods here, because we
+	// still need to generate wrappers for them, even if the user can't
+	// refer to them directly.
+	if t.Sym() != nil && t.Kind() != types.TINTER {
+		for _, m := range t.Methods().Slice() {
+			p.markObject(m.Nname.(*ir.Name))
+		}
+	}
+
+	// If t is a struct, recursively visit its embedded fields.
+	if t.IsStruct() {
+		for _, f := range t.FieldSlice() {
+			if f.Embedded != 0 {
+				p.markEmbed(f.Type)
+			}
+		}
+	}
+}
+
+// markInlBody marks n's inline body for export and recursively
+// ensures all called functions are marked too.
+func (p *crawler) markInlBody(n *ir.Name) {
+	if n == nil {
+		return
+	}
+	if n.Op() != ir.ONAME || n.Class != ir.PFUNC {
+		base.Fatalf("markInlBody: unexpected %v, %v, %v", n, n.Op(), n.Class)
+	}
+	fn := n.Func
+	if fn == nil {
+		base.Fatalf("markInlBody: missing Func on %v", n)
+	}
+	if fn.Inl == nil {
+		return
+	}
+
+	if fn.ExportInline() {
+		return
+	}
+	fn.SetExportInline(true)
+
+	ImportedBody(fn)
+
+	var doFlood func(n ir.Node)
+	doFlood = func(n ir.Node) {
+		switch n.Op() {
+		case ir.OMETHEXPR, ir.ODOTMETH:
+			p.markInlBody(ir.MethodExprName(n))
+
+		case ir.ONAME:
+			n := n.(*ir.Name)
+			switch n.Class {
+			case ir.PFUNC:
+				p.markInlBody(n)
+				Export(n)
+			case ir.PEXTERN:
+				Export(n)
+			}
+			p.checkGenericType(n.Type())
+		case ir.OTYPE:
+			p.checkGenericType(n.Type())
+		case ir.OMETHVALUE:
+			// Okay, because we don't yet inline indirect
+			// calls to method values.
+		case ir.OCLOSURE:
+			// VisitList doesn't visit closure bodies, so force a
+			// recursive call to VisitList on the body of the closure.
+			ir.VisitList(n.(*ir.ClosureExpr).Func.Body, doFlood)
+		}
+	}
+
+	// Recursively identify all referenced functions for
+	// reexport. We want to include even non-called functions,
+	// because after inlining they might be callable.
+	ir.VisitList(fn.Inl.Body, doFlood)
+}
+
+// checkGenerictype ensures that we call markType() on any base generic type that
+// is written to the export file (even if not explicitly marked
+// for export), so its methods will be available for inlining if needed.
+func (p *crawler) checkGenericType(t *types.Type) {
+	if t != nil && t.HasTParam() {
+		if t.OrigSym != nil {
+			// Convert to the base generic type.
+			t = t.OrigSym.Def.Type()
+		}
+		p.markType(t)
+	}
+}
diff --git a/src/cmd/compile/internal/typecheck/dcl.go b/src/cmd/compile/internal/typecheck/dcl.go
index 5b771e3..11e20f0 100644
--- a/src/cmd/compile/internal/typecheck/dcl.go
+++ b/src/cmd/compile/internal/typecheck/dcl.go
@@ -6,7 +6,7 @@
 
 import (
 	"fmt"
-	"strconv"
+	"sync"
 
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
@@ -363,12 +363,10 @@
 	}
 
 	// declare the out arguments.
-	gen := len(nt.Params)
-	for _, n := range nt.Results {
+	for i, n := range nt.Results {
 		if n.Sym == nil {
 			// Name so that escape analysis can track it. ~r stands for 'result'.
-			n.Sym = LookupNum("~r", gen)
-			gen++
+			n.Sym = LookupNum("~r", i)
 		}
 		if n.Sym.IsBlank() {
 			// Give it a name so we can assign to it during return. ~b stands for 'blank'.
@@ -377,8 +375,7 @@
 			//	func g() int
 			// f is allowed to use a plain 'return' with no arguments, while g is not.
 			// So the two cases must be distinguished.
-			n.Sym = LookupNum("~b", gen)
-			gen++
+			n.Sym = LookupNum("~b", i)
 		}
 
 		funcarg(n, ir.PPARAMOUT)
@@ -431,6 +428,7 @@
 	n := ir.NewNameAt(pos, s)
 	s.Def = n
 	n.SetType(t)
+	n.SetTypecheck(1)
 	n.Class = ir.PAUTO
 	n.SetEsc(ir.EscNever)
 	n.Curfn = curfn
@@ -443,15 +441,39 @@
 	return n
 }
 
+var (
+	autotmpnamesmu sync.Mutex
+	autotmpnames   []string
+)
+
 // autotmpname returns the name for an autotmp variable numbered n.
 func autotmpname(n int) string {
-	// Give each tmp a different name so that they can be registerized.
-	// Add a preceding . to avoid clashing with legal names.
-	const prefix = ".autotmp_"
-	// Start with a buffer big enough to hold a large n.
-	b := []byte(prefix + "      ")[:len(prefix)]
-	b = strconv.AppendInt(b, int64(n), 10)
-	return types.InternString(b)
+	autotmpnamesmu.Lock()
+	defer autotmpnamesmu.Unlock()
+
+	// Grow autotmpnames, if needed.
+	if n >= len(autotmpnames) {
+		autotmpnames = append(autotmpnames, make([]string, n+1-len(autotmpnames))...)
+		autotmpnames = autotmpnames[:cap(autotmpnames)]
+	}
+
+	s := autotmpnames[n]
+	if s == "" {
+		// Give each tmp a different name so that they can be registerized.
+		// Add a preceding . to avoid clashing with legal names.
+		prefix := ".autotmp_%d"
+
+		// In quirks mode, pad out the number to stabilize variable
+		// sorting. This ensures autotmps 8 and 9 sort the same way even
+		// if they get renumbered to 9 and 10, respectively.
+		if base.Debug.UnifiedQuirks != 0 {
+			prefix = ".autotmp_%06d"
+		}
+
+		s = fmt.Sprintf(prefix, n)
+		autotmpnames[n] = s
+	}
+	return s
 }
 
 // f is method type, with receiver.
diff --git a/src/cmd/compile/internal/typecheck/export.go b/src/cmd/compile/internal/typecheck/export.go
index 63d0a1e..30726d4 100644
--- a/src/cmd/compile/internal/typecheck/export.go
+++ b/src/cmd/compile/internal/typecheck/export.go
@@ -15,22 +15,22 @@
 
 // importalias declares symbol s as an imported type alias with type t.
 // ipkg is the package being imported
-func importalias(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
-	return importobj(ipkg, pos, s, ir.OTYPE, ir.PEXTERN, t)
+func importalias(pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
+	return importobj(pos, s, ir.OTYPE, ir.PEXTERN, t)
 }
 
 // importconst declares symbol s as an imported constant with type t and value val.
 // ipkg is the package being imported
-func importconst(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type, val constant.Value) *ir.Name {
-	n := importobj(ipkg, pos, s, ir.OLITERAL, ir.PEXTERN, t)
+func importconst(pos src.XPos, s *types.Sym, t *types.Type, val constant.Value) *ir.Name {
+	n := importobj(pos, s, ir.OLITERAL, ir.PEXTERN, t)
 	n.SetVal(val)
 	return n
 }
 
 // importfunc declares symbol s as an imported function with type t.
 // ipkg is the package being imported
-func importfunc(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
-	n := importobj(ipkg, pos, s, ir.ONAME, ir.PFUNC, t)
+func importfunc(pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
+	n := importobj(pos, s, ir.ONAME, ir.PFUNC, t)
 	n.Func = ir.NewFunc(pos)
 	n.Func.Nname = n
 	return n
@@ -38,8 +38,8 @@
 
 // importobj declares symbol s as an imported object representable by op.
 // ipkg is the package being imported
-func importobj(ipkg *types.Pkg, pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Class, t *types.Type) *ir.Name {
-	n := importsym(ipkg, pos, s, op, ctxt)
+func importobj(pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Class, t *types.Type) *ir.Name {
+	n := importsym(pos, s, op, ctxt)
 	n.SetType(t)
 	if ctxt == ir.PFUNC {
 		n.Sym().SetFunc(true)
@@ -47,7 +47,7 @@
 	return n
 }
 
-func importsym(ipkg *types.Pkg, pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Class) *ir.Name {
+func importsym(pos src.XPos, s *types.Sym, op ir.Op, ctxt ir.Class) *ir.Name {
 	if n := s.PkgDef(); n != nil {
 		base.Fatalf("importsym of symbol that already exists: %v", n)
 	}
@@ -61,14 +61,14 @@
 // importtype returns the named type declared by symbol s.
 // If no such type has been declared yet, a forward declaration is returned.
 // ipkg is the package being imported
-func importtype(ipkg *types.Pkg, pos src.XPos, s *types.Sym) *ir.Name {
-	n := importsym(ipkg, pos, s, ir.OTYPE, ir.PEXTERN)
+func importtype(pos src.XPos, s *types.Sym) *ir.Name {
+	n := importsym(pos, s, ir.OTYPE, ir.PEXTERN)
 	n.SetType(types.NewNamed(n))
 	return n
 }
 
 // importvar declares symbol s as an imported variable with type t.
 // ipkg is the package being imported
-func importvar(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
-	return importobj(ipkg, pos, s, ir.ONAME, ir.PEXTERN, t)
+func importvar(pos src.XPos, s *types.Sym, t *types.Type) *ir.Name {
+	return importobj(pos, s, ir.ONAME, ir.PEXTERN, t)
 }
diff --git a/src/cmd/compile/internal/typecheck/expr.go b/src/cmd/compile/internal/typecheck/expr.go
index 24d141e..7e974df 100644
--- a/src/cmd/compile/internal/typecheck/expr.go
+++ b/src/cmd/compile/internal/typecheck/expr.go
@@ -311,14 +311,23 @@
 
 				f := t.Field(i)
 				s := f.Sym
-				if s != nil && !types.IsExported(s.Name) && s.Pkg != types.LocalPkg {
-					base.Errorf("implicit assignment of unexported field '%s' in %v literal", s.Name, t)
+
+				// Do the test for assigning to unexported fields.
+				// But if this is an instantiated function, then
+				// the function has already been typechecked. In
+				// that case, don't do the test, since it can fail
+				// for the closure structs created in
+				// walkClosure(), because the instantiated
+				// function is compiled as if in the source
+				// package of the generic function.
+				if !(ir.CurFunc != nil && strings.Index(ir.CurFunc.Nname.Sym().Name, "[") >= 0) {
+					if s != nil && !types.IsExported(s.Name) && s.Pkg != types.LocalPkg {
+						base.Errorf("implicit assignment of unexported field '%s' in %v literal", s.Name, t)
+					}
 				}
 				// No pushtype allowed here. Must name fields for that.
 				n1 = AssignConv(n1, f.Type, "field value")
-				sk := ir.NewStructKeyExpr(base.Pos, f.Sym, n1)
-				sk.Offset = f.Offset
-				ls[i] = sk
+				ls[i] = ir.NewStructKeyExpr(base.Pos, f, n1)
 			}
 			if len(ls) < t.NumFields() {
 				base.Errorf("too few values in %v", n)
@@ -328,77 +337,33 @@
 
 			// keyed list
 			ls := n.List
-			for i, l := range ls {
-				ir.SetPos(l)
+			for i, n := range ls {
+				ir.SetPos(n)
 
-				if l.Op() == ir.OKEY {
-					kv := l.(*ir.KeyExpr)
-					key := kv.Key
-
-					// Sym might have resolved to name in other top-level
-					// package, because of import dot. Redirect to correct sym
-					// before we do the lookup.
-					s := key.Sym()
-					if id, ok := key.(*ir.Ident); ok && DotImportRefs[id] != nil {
-						s = Lookup(s.Name)
-					}
-
-					// An OXDOT uses the Sym field to hold
-					// the field to the right of the dot,
-					// so s will be non-nil, but an OXDOT
-					// is never a valid struct literal key.
-					if s == nil || s.Pkg != types.LocalPkg || key.Op() == ir.OXDOT || s.IsBlank() {
-						base.Errorf("invalid field name %v in struct initializer", key)
-						continue
-					}
-
-					l = ir.NewStructKeyExpr(l.Pos(), s, kv.Value)
-					ls[i] = l
-				}
-
-				if l.Op() != ir.OSTRUCTKEY {
-					if !errored {
-						base.Errorf("mixture of field:value and value initializers")
-						errored = true
-					}
-					ls[i] = Expr(ls[i])
-					continue
-				}
-				l := l.(*ir.StructKeyExpr)
-
-				f := Lookdot1(nil, l.Field, t, t.Fields(), 0)
-				if f == nil {
-					if ci := Lookdot1(nil, l.Field, t, t.Fields(), 2); ci != nil { // Case-insensitive lookup.
-						if visible(ci.Sym) {
-							base.Errorf("unknown field '%v' in struct literal of type %v (but does have %v)", l.Field, t, ci.Sym)
-						} else if nonexported(l.Field) && l.Field.Name == ci.Sym.Name { // Ensure exactness before the suggestion.
-							base.Errorf("cannot refer to unexported field '%v' in struct literal of type %v", l.Field, t)
-						} else {
-							base.Errorf("unknown field '%v' in struct literal of type %v", l.Field, t)
+				sk, ok := n.(*ir.StructKeyExpr)
+				if !ok {
+					kv, ok := n.(*ir.KeyExpr)
+					if !ok {
+						if !errored {
+							base.Errorf("mixture of field:value and value initializers")
+							errored = true
 						}
+						ls[i] = Expr(n)
 						continue
 					}
-					var f *types.Field
-					p, _ := dotpath(l.Field, t, &f, true)
-					if p == nil || f.IsMethod() {
-						base.Errorf("unknown field '%v' in struct literal of type %v", l.Field, t)
+
+					sk = tcStructLitKey(t, kv)
+					if sk == nil {
 						continue
 					}
-					// dotpath returns the parent embedded types in reverse order.
-					var ep []string
-					for ei := len(p) - 1; ei >= 0; ei-- {
-						ep = append(ep, p[ei].field.Sym.Name)
-					}
-					ep = append(ep, l.Field.Name)
-					base.Errorf("cannot use promoted field %v in struct literal of type %v", strings.Join(ep, "."), t)
-					continue
+
+					fielddup(sk.Sym().Name, hash)
 				}
-				fielddup(f.Sym.Name, hash)
-				l.Offset = f.Offset
 
 				// No pushtype allowed here. Tried and rejected.
-				l.Value = Expr(l.Value)
-				l.Value = AssignConv(l.Value, f.Type, "field value")
+				sk.Value = Expr(sk.Value)
+				sk.Value = AssignConv(sk.Value, sk.Field.Type, "field value")
+				ls[i] = sk
 			}
 		}
 
@@ -409,6 +374,60 @@
 	return n
 }
 
+// tcStructLitKey typechecks an OKEY node that appeared within a
+// struct literal.
+func tcStructLitKey(typ *types.Type, kv *ir.KeyExpr) *ir.StructKeyExpr {
+	key := kv.Key
+
+	// Sym might have resolved to name in other top-level
+	// package, because of import dot. Redirect to correct sym
+	// before we do the lookup.
+	sym := key.Sym()
+	if id, ok := key.(*ir.Ident); ok && DotImportRefs[id] != nil {
+		sym = Lookup(sym.Name)
+	}
+
+	// An OXDOT uses the Sym field to hold
+	// the field to the right of the dot,
+	// so s will be non-nil, but an OXDOT
+	// is never a valid struct literal key.
+	if sym == nil || sym.Pkg != types.LocalPkg || key.Op() == ir.OXDOT || sym.IsBlank() {
+		base.Errorf("invalid field name %v in struct initializer", key)
+		return nil
+	}
+
+	if f := Lookdot1(nil, sym, typ, typ.Fields(), 0); f != nil {
+		return ir.NewStructKeyExpr(kv.Pos(), f, kv.Value)
+	}
+
+	if ci := Lookdot1(nil, sym, typ, typ.Fields(), 2); ci != nil { // Case-insensitive lookup.
+		if visible(ci.Sym) {
+			base.Errorf("unknown field '%v' in struct literal of type %v (but does have %v)", sym, typ, ci.Sym)
+		} else if nonexported(sym) && sym.Name == ci.Sym.Name { // Ensure exactness before the suggestion.
+			base.Errorf("cannot refer to unexported field '%v' in struct literal of type %v", sym, typ)
+		} else {
+			base.Errorf("unknown field '%v' in struct literal of type %v", sym, typ)
+		}
+		return nil
+	}
+
+	var f *types.Field
+	p, _ := dotpath(sym, typ, &f, true)
+	if p == nil || f.IsMethod() {
+		base.Errorf("unknown field '%v' in struct literal of type %v", sym, typ)
+		return nil
+	}
+
+	// dotpath returns the parent embedded types in reverse order.
+	var ep []string
+	for ei := len(p) - 1; ei >= 0; ei-- {
+		ep = append(ep, p[ei].field.Sym.Name)
+	}
+	ep = append(ep, sym.Name)
+	base.Errorf("cannot use promoted field %v in struct literal of type %v", strings.Join(ep, "."), typ)
+	return nil
+}
+
 // tcConv typechecks an OCONV node.
 func tcConv(n *ir.ConvExpr) ir.Node {
 	types.CheckSize(n.Type()) // ensure width is calculated for backend
@@ -522,8 +541,8 @@
 	}
 
 	if (n.Op() == ir.ODOTINTER || n.Op() == ir.ODOTMETH) && top&ctxCallee == 0 {
-		n.SetOp(ir.OCALLPART)
-		n.SetType(MethodValueWrapper(n).Type())
+		n.SetOp(ir.OMETHVALUE)
+		n.SetType(NewMethodType(n.Type(), nil))
 	}
 	return n
 }
diff --git a/src/cmd/compile/internal/typecheck/func.go b/src/cmd/compile/internal/typecheck/func.go
index fbcc784..7dec65c 100644
--- a/src/cmd/compile/internal/typecheck/func.go
+++ b/src/cmd/compile/internal/typecheck/func.go
@@ -8,28 +8,29 @@
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/types"
+	"cmd/internal/src"
 
 	"fmt"
 	"go/constant"
 	"go/token"
 )
 
-// package all the arguments that match a ... T parameter into a []T.
-func MakeDotArgs(typ *types.Type, args []ir.Node) ir.Node {
+// MakeDotArgs package all the arguments that match a ... T parameter into a []T.
+func MakeDotArgs(pos src.XPos, typ *types.Type, args []ir.Node) ir.Node {
 	var n ir.Node
 	if len(args) == 0 {
-		n = NodNil()
+		n = ir.NewNilExpr(pos)
 		n.SetType(typ)
 	} else {
-		lit := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ), nil)
-		lit.List.Append(args...)
+		args = append([]ir.Node(nil), args...)
+		lit := ir.NewCompLitExpr(pos, ir.OCOMPLIT, ir.TypeNode(typ), args)
 		lit.SetImplicit(true)
 		n = lit
 	}
 
 	n = Expr(n)
 	if n.Type() == nil {
-		base.Fatalf("mkdotargslice: typecheck failed")
+		base.FatalfAt(pos, "mkdotargslice: typecheck failed")
 	}
 	return n
 }
@@ -47,7 +48,7 @@
 
 	args := call.Args
 	extra := args[vi:]
-	slice := MakeDotArgs(vt, extra)
+	slice := MakeDotArgs(call.Pos(), vt, extra)
 	for i := range extra {
 		extra[i] = nil // allow GC
 	}
@@ -56,6 +57,25 @@
 	call.IsDDD = true
 }
 
+// FixMethodCall rewrites a method call t.M(...) into a function call T.M(t, ...).
+func FixMethodCall(call *ir.CallExpr) {
+	if call.X.Op() != ir.ODOTMETH {
+		return
+	}
+
+	dot := call.X.(*ir.SelectorExpr)
+
+	fn := Expr(ir.NewSelectorExpr(dot.Pos(), ir.OXDOT, ir.TypeNode(dot.X.Type()), dot.Selection.Sym))
+
+	args := make([]ir.Node, 1+len(call.Args))
+	args[0] = dot.X
+	copy(args[1:], call.Args)
+
+	call.SetOp(ir.OCALLFUNC)
+	call.X = fn
+	call.Args = args
+}
+
 // ClosureType returns the struct type used to hold all the information
 // needed in the closure for clo (clo must be a OCLOSURE node).
 // The address of a variable of the returned type can be cast to a func.
@@ -73,8 +93,25 @@
 	// The information appears in the binary in the form of type descriptors;
 	// the struct is unnamed so that closures in multiple packages with the
 	// same struct type can share the descriptor.
+
+	// Make sure the .F field is in the same package as the rest of the
+	// fields. This deals with closures in instantiated functions, which are
+	// compiled as if from the source package of the generic function.
+	var pkg *types.Pkg
+	if len(clo.Func.ClosureVars) == 0 {
+		pkg = types.LocalPkg
+	} else {
+		for _, v := range clo.Func.ClosureVars {
+			if pkg == nil {
+				pkg = v.Sym().Pkg
+			} else if pkg != v.Sym().Pkg {
+				base.Fatalf("Closure variables from multiple packages")
+			}
+		}
+	}
+
 	fields := []*types.Field{
-		types.NewField(base.Pos, Lookup(".F"), types.Types[types.TUINTPTR]),
+		types.NewField(base.Pos, pkg.Lookup(".F"), types.Types[types.TUINTPTR]),
 	}
 	for _, v := range clo.Func.ClosureVars {
 		typ := v.Type()
@@ -88,10 +125,10 @@
 	return typ
 }
 
-// PartialCallType returns the struct type used to hold all the information
-// needed in the closure for n (n must be a OCALLPART node).
-// The address of a variable of the returned type can be cast to a func.
-func PartialCallType(n *ir.SelectorExpr) *types.Type {
+// MethodValueType returns the struct type used to hold all the information
+// needed in the closure for a OMETHVALUE node. The address of a variable of
+// the returned type can be cast to a func.
+func MethodValueType(n *ir.SelectorExpr) *types.Type {
 	t := types.NewStruct(types.NoPkg, []*types.Field{
 		types.NewField(base.Pos, Lookup("F"), types.Types[types.TUINTPTR]),
 		types.NewField(base.Pos, Lookup("R"), n.X.Type()),
@@ -181,153 +218,38 @@
 	return fn.Sym().Pkg
 }
 
-// ClosureName generates a new unique name for a closure within
-// outerfunc.
-func ClosureName(outerfunc *ir.Func) *types.Sym {
-	outer := "glob."
-	prefix := "func"
-	gen := &globClosgen
-
-	if outerfunc != nil {
-		if outerfunc.OClosure != nil {
-			prefix = ""
-		}
-
-		outer = ir.FuncName(outerfunc)
-
-		// There may be multiple functions named "_". In those
-		// cases, we can't use their individual Closgens as it
-		// would lead to name clashes.
-		if !ir.IsBlank(outerfunc.Nname) {
-			gen = &outerfunc.Closgen
-		}
-	}
-
-	*gen++
-	return Lookup(fmt.Sprintf("%s.%s%d", outer, prefix, *gen))
-}
-
-// globClosgen is like Func.Closgen, but for the global scope.
-var globClosgen int32
-
-// MethodValueWrapper returns the DCLFUNC node representing the
-// wrapper function (*-fm) needed for the given method value. If the
-// wrapper function hasn't already been created yet, it's created and
-// added to Target.Decls.
-//
-// TODO(mdempsky): Move into walk. This isn't part of type checking.
-func MethodValueWrapper(dot *ir.SelectorExpr) *ir.Func {
-	if dot.Op() != ir.OCALLPART {
-		base.Fatalf("MethodValueWrapper: unexpected %v (%v)", dot, dot.Op())
-	}
-
-	t0 := dot.Type()
-	meth := dot.Sel
-	rcvrtype := dot.X.Type()
-	sym := ir.MethodSymSuffix(rcvrtype, meth, "-fm")
-
-	if sym.Uniq() {
-		return sym.Def.(*ir.Func)
-	}
-	sym.SetUniq(true)
-
-	savecurfn := ir.CurFunc
-	saveLineNo := base.Pos
-	ir.CurFunc = nil
-
-	// Set line number equal to the line number where the method is declared.
-	if pos := dot.Selection.Pos; pos.IsKnown() {
-		base.Pos = pos
-	}
-	// Note: !dot.Selection.Pos.IsKnown() happens for method expressions where
-	// the method is implicitly declared. The Error method of the
-	// built-in error type is one such method.  We leave the line
-	// number at the use of the method expression in this
-	// case. See issue 29389.
-
-	tfn := ir.NewFuncType(base.Pos, nil,
-		NewFuncParams(t0.Params(), true),
-		NewFuncParams(t0.Results(), false))
-
-	fn := DeclFunc(sym, tfn)
-	fn.SetDupok(true)
-	fn.SetNeedctxt(true)
-	fn.SetWrapper(true)
-
-	// Declare and initialize variable holding receiver.
-	ptr := ir.NewNameAt(base.Pos, Lookup(".this"))
-	ptr.Class = ir.PAUTOHEAP
-	ptr.SetType(rcvrtype)
-	ptr.Curfn = fn
-	ptr.SetIsClosureVar(true)
-	ptr.SetByval(true)
-	fn.ClosureVars = append(fn.ClosureVars, ptr)
-
-	call := ir.NewCallExpr(base.Pos, ir.OCALL, ir.NewSelectorExpr(base.Pos, ir.OXDOT, ptr, meth), nil)
-	call.Args = ir.ParamNames(tfn.Type())
-	call.IsDDD = tfn.Type().IsVariadic()
-
-	var body ir.Node = call
-	if t0.NumResults() != 0 {
-		ret := ir.NewReturnStmt(base.Pos, nil)
-		ret.Results = []ir.Node{call}
-		body = ret
-	}
-
-	fn.Body = []ir.Node{body}
-	FinishFuncBody()
-
-	Func(fn)
-	// Need to typecheck the body of the just-generated wrapper.
-	// typecheckslice() requires that Curfn is set when processing an ORETURN.
-	ir.CurFunc = fn
-	Stmts(fn.Body)
-	sym.Def = fn
-	Target.Decls = append(Target.Decls, fn)
-	ir.CurFunc = savecurfn
-	base.Pos = saveLineNo
-
-	return fn
-}
-
 // tcClosure typechecks an OCLOSURE node. It also creates the named
 // function associated with the closure.
 // TODO: This creation of the named function should probably really be done in a
 // separate pass from type-checking.
-func tcClosure(clo *ir.ClosureExpr, top int) {
+func tcClosure(clo *ir.ClosureExpr, top int) ir.Node {
 	fn := clo.Func
+
+	// We used to allow IR builders to typecheck the underlying Func
+	// themselves, but that led to too much variety and inconsistency
+	// around who's responsible for naming the function, typechecking
+	// it, or adding it to Target.Decls.
+	//
+	// It's now all or nothing. Callers are still allowed to do these
+	// themselves, but then they assume responsibility for all of them.
+	if fn.Typecheck() == 1 {
+		base.FatalfAt(fn.Pos(), "underlying closure func already typechecked: %v", fn)
+	}
+
 	// Set current associated iota value, so iota can be used inside
 	// function in ConstSpec, see issue #22344
 	if x := getIotaValue(); x >= 0 {
 		fn.Iota = x
 	}
 
-	fn.SetClosureCalled(top&ctxCallee != 0)
-
-	// Do not typecheck fn twice, otherwise, we will end up pushing
-	// fn to Target.Decls multiple times, causing InitLSym called twice.
-	// See #30709
-	if fn.Typecheck() == 1 {
-		clo.SetType(fn.Type())
-		return
-	}
-
-	// Don't give a name and add to Target.Decls if we are typechecking an inlined
-	// body in ImportedBody(), since we only want to create the named function
-	// when the closure is actually inlined (and then we force a typecheck
-	// explicitly in (*inlsubst).node()).
-	if !inTypeCheckInl {
-		fn.Nname.SetSym(ClosureName(ir.CurFunc))
-		ir.MarkFunc(fn.Nname)
-	}
+	ir.NameClosure(clo, ir.CurFunc)
 	Func(fn)
-	clo.SetType(fn.Type())
 
 	// Type check the body now, but only if we're inside a function.
 	// At top level (in a variable initialization: curfn==nil) we're not
 	// ready to type check code yet; we'll check it later, because the
 	// underlying closure function we create is added to Target.Decls.
-	if ir.CurFunc != nil && clo.Type() != nil {
+	if ir.CurFunc != nil {
 		oldfn := ir.CurFunc
 		ir.CurFunc = fn
 		Stmts(fn.Body)
@@ -353,14 +275,17 @@
 	}
 	fn.ClosureVars = fn.ClosureVars[:out]
 
-	if base.Flag.W > 1 {
-		s := fmt.Sprintf("New closure func: %s", ir.FuncName(fn))
-		ir.Dump(s, fn)
+	clo.SetType(fn.Type())
+
+	target := Target
+	if inTypeCheckInl {
+		// We're typechecking an imported function, so it's not actually
+		// part of Target. Skip adding it to Target.Decls so we don't
+		// compile it again.
+		target = nil
 	}
-	if !inTypeCheckInl {
-		// Add function to Target.Decls once only when we give it a name
-		Target.Decls = append(Target.Decls, fn)
-	}
+
+	return ir.UseClosure(clo, target)
 }
 
 // type check function definition
@@ -390,10 +315,6 @@
 
 // tcCall typechecks an OCALL node.
 func tcCall(n *ir.CallExpr, top int) ir.Node {
-	n.Use = ir.CallUseExpr
-	if top == ctxStmt {
-		n.Use = ir.CallUseStmt
-	}
 	Stmts(n.Init()) // imported rewritten f(g()) calls (#30907)
 	n.X = typecheck(n.X, ctxExpr|ctxType|ctxCallee)
 	if n.X.Diag() {
@@ -509,6 +430,7 @@
 	}
 
 	typecheckaste(ir.OCALL, n.X, n.IsDDD, t.Params(), n.Args, func() string { return fmt.Sprintf("argument to %v", n.X) })
+	FixMethodCall(n)
 	if t.NumResults() == 0 {
 		return n
 	}
@@ -979,6 +901,21 @@
 	return n
 }
 
+// tcRecoverFP typechecks an ORECOVERFP node.
+func tcRecoverFP(n *ir.CallExpr) ir.Node {
+	if len(n.Args) != 1 {
+		base.FatalfAt(n.Pos(), "wrong number of arguments: %v", n)
+	}
+
+	n.Args[0] = Expr(n.Args[0])
+	if !n.Args[0].Type().IsPtrShaped() {
+		base.FatalfAt(n.Pos(), "%L is not pointer shaped", n.Args[0])
+	}
+
+	n.SetType(types.Types[types.TINTER])
+	return n
+}
+
 // tcUnsafeAdd typechecks an OUNSAFEADD node.
 func tcUnsafeAdd(n *ir.BinaryExpr) *ir.BinaryExpr {
 	if !types.AllowsGoVersion(curpkg(), 1, 17) {
diff --git a/src/cmd/compile/internal/typecheck/iexport.go b/src/cmd/compile/internal/typecheck/iexport.go
index 64d68ef..75b4931 100644
--- a/src/cmd/compile/internal/typecheck/iexport.go
+++ b/src/cmd/compile/internal/typecheck/iexport.go
@@ -173,6 +173,8 @@
 //     }
 //
 //
+//  TODO(danscales): fill in doc for 'type TypeParamType' and 'type InstType'
+//
 //     type Signature struct {
 //         Params   []Param
 //         Results  []Param
@@ -202,7 +204,6 @@
 package typecheck
 
 import (
-	"bufio"
 	"bytes"
 	"crypto/md5"
 	"encoding/binary"
@@ -221,9 +222,18 @@
 )
 
 // Current indexed export format version. Increase with each format change.
-// 1: added column details to Pos
 // 0: Go1.11 encoding
-const iexportVersion = 1
+// 1: added column details to Pos
+// 2: added information for generic function/types (currently unstable)
+const (
+	iexportVersionGo1_11 = 0
+	iexportVersionPosCol = 1
+	// TODO: before release, change this back to 2.  Kept at previous version
+	// for now (for testing).
+	iexportVersionGenerics = iexportVersionPosCol
+
+	iexportVersionCurrent = iexportVersionGenerics
+)
 
 // predeclReserved is the number of type offsets reserved for types
 // implicitly declared in the universe block.
@@ -244,6 +254,9 @@
 	signatureType
 	structType
 	interfaceType
+	typeParamType
+	instType
+	unionType
 )
 
 const (
@@ -251,13 +264,22 @@
 	magic = 0x6742937dc293105
 )
 
-func WriteExports(out *bufio.Writer) {
+// WriteExports writes the indexed export format to out. If extensions
+// is true, then the compiler-only extensions are included.
+func WriteExports(out io.Writer, extensions bool) {
+	if extensions {
+		// If we're exporting inline bodies, invoke the crawler to mark
+		// which bodies to include.
+		crawlExports(Target.Exports)
+	}
+
 	p := iexporter{
 		allPkgs:     map[*types.Pkg]bool{},
 		stringIndex: map[string]uint64{},
 		declIndex:   map[*types.Sym]uint64{},
 		inlineIndex: map[*types.Sym]uint64{},
 		typIndex:    map[*types.Type]uint64{},
+		extensions:  extensions,
 	}
 
 	for i, pt := range predeclared() {
@@ -293,7 +315,7 @@
 	// Assemble header.
 	var hdr intWriter
 	hdr.WriteByte('i')
-	hdr.uint64(iexportVersion)
+	hdr.uint64(iexportVersionCurrent)
 	hdr.uint64(uint64(p.strings.Len()))
 	hdr.uint64(dataLen)
 
@@ -379,6 +401,8 @@
 	declIndex   map[*types.Sym]uint64
 	inlineIndex map[*types.Sym]uint64
 	typIndex    map[*types.Type]uint64
+
+	extensions bool
 }
 
 // stringOff returns the offset of s within the string section.
@@ -449,7 +473,9 @@
 			w.tag('V')
 			w.pos(n.Pos())
 			w.typ(n.Type())
-			w.varExt(n)
+			if w.p.extensions {
+				w.varExt(n)
+			}
 
 		case ir.PFUNC:
 			if ir.IsMethod(n) {
@@ -457,10 +483,25 @@
 			}
 
 			// Function.
-			w.tag('F')
+			if n.Type().TParams().NumFields() == 0 {
+				w.tag('F')
+			} else {
+				w.tag('G')
+			}
 			w.pos(n.Pos())
+			// The tparam list of the function type is the
+			// declaration of the type params. So, write out the type
+			// params right now. Then those type params will be
+			// referenced via their type offset (via typOff) in all
+			// other places in the signature and function that they
+			// are used.
+			if n.Type().TParams().NumFields() > 0 {
+				w.tparamList(n.Type().TParams().FieldSlice())
+			}
 			w.signature(n.Type())
-			w.funcExt(n)
+			if w.p.extensions {
+				w.funcExt(n)
+			}
 
 		default:
 			base.Fatalf("unexpected class: %v, %v", n, n.Class)
@@ -476,10 +517,25 @@
 		w.tag('C')
 		w.pos(n.Pos())
 		w.value(n.Type(), n.Val())
-		w.constExt(n)
+		if w.p.extensions {
+			w.constExt(n)
+		}
 
 	case ir.OTYPE:
-		if types.IsDotAlias(n.Sym()) {
+		if n.Type().IsTypeParam() && n.Type().Underlying() == n.Type() {
+			// Even though it has local scope, a typeparam requires a
+			// declaration via its package and unique name, because it
+			// may be referenced within its type bound during its own
+			// definition.
+			w.tag('P')
+			// A typeparam has a name, and has a type bound rather
+			// than an underlying type.
+			w.pos(n.Pos())
+			w.typ(n.Type().Bound())
+			break
+		}
+
+		if n.Alias() {
 			// Alias.
 			w.tag('A')
 			w.pos(n.Pos())
@@ -488,9 +544,18 @@
 		}
 
 		// Defined type.
-		w.tag('T')
+		if len(n.Type().RParams()) == 0 {
+			w.tag('T')
+		} else {
+			w.tag('U')
+		}
 		w.pos(n.Pos())
 
+		if len(n.Type().RParams()) > 0 {
+			// Export type parameters, if any, needed for this type
+			w.typeList(n.Type().RParams())
+		}
+
 		underlying := n.Type().Underlying()
 		if underlying == types.ErrorType.Underlying() {
 			// For "type T error", use error as the
@@ -505,22 +570,29 @@
 
 		t := n.Type()
 		if t.IsInterface() {
-			w.typeExt(t)
+			if w.p.extensions {
+				w.typeExt(t)
+			}
 			break
 		}
 
-		ms := t.Methods()
-		w.uint64(uint64(ms.Len()))
-		for _, m := range ms.Slice() {
+		// Sort methods, for consistency with types2.
+		methods := append([]*types.Field(nil), t.Methods().Slice()...)
+		sort.Sort(types.MethodsByName(methods))
+
+		w.uint64(uint64(len(methods)))
+		for _, m := range methods {
 			w.pos(m.Pos)
 			w.selector(m.Sym)
 			w.param(m.Type.Recv())
 			w.signature(m.Type)
 		}
 
-		w.typeExt(t)
-		for _, m := range ms.Slice() {
-			w.methExt(m)
+		if w.p.extensions {
+			w.typeExt(t)
+			for _, m := range methods {
+				w.methExt(m)
+			}
 		}
 
 	default:
@@ -803,8 +875,46 @@
 }
 
 func (w *exportWriter) doTyp(t *types.Type) {
-	if t.Sym() != nil {
-		if t.Sym().Pkg == types.BuiltinPkg || t.Sym().Pkg == ir.Pkgs.Unsafe {
+	s := t.Sym()
+	if s != nil && t.OrigSym != nil {
+		assert(base.Flag.G > 0)
+		// This is an instantiated type - could be a re-instantiation like
+		// Value[T2] or a full instantiation like Value[int].
+		if strings.Index(s.Name, "[") < 0 {
+			base.Fatalf("incorrect name for instantiated type")
+		}
+		w.startType(instType)
+		w.pos(t.Pos())
+		// Export the type arguments for the instantiated type. The
+		// instantiated type could be in a method header (e.g. "func (v
+		// *Value[T2]) set (...) { ... }"), so the type args are "new"
+		// typeparams. Or the instantiated type could be in a
+		// function/method body, so the type args are either concrete
+		// types or existing typeparams from the function/method header.
+		w.typeList(t.RParams())
+		// Export a reference to the base type.
+		baseType := t.OrigSym.Def.(*ir.Name).Type()
+		w.typ(baseType)
+		return
+	}
+
+	// The 't.Underlying() == t' check is to confirm this is a base typeparam
+	// type, rather than a defined type with typeparam underlying type, like:
+	// type orderedAbs[T any] T
+	if t.IsTypeParam() && t.Underlying() == t {
+		assert(base.Flag.G > 0)
+		if s.Pkg == types.BuiltinPkg || s.Pkg == ir.Pkgs.Unsafe {
+			base.Fatalf("builtin type missing from typIndex: %v", t)
+		}
+		// Write out the first use of a type param as a qualified ident.
+		// This will force a "declaration" of the type param.
+		w.startType(typeParamType)
+		w.qualifiedIdent(t.Obj().(*ir.Name))
+		return
+	}
+
+	if s != nil {
+		if s.Pkg == types.BuiltinPkg || s.Pkg == ir.Pkgs.Unsafe {
 			base.Fatalf("builtin type missing from typIndex: %v", t)
 		}
 
@@ -865,6 +975,12 @@
 			}
 		}
 
+		// Sort methods and embedded types, for consistency with types2.
+		// Note: embedded types may be anonymous, and types2 sorts them
+		// with sort.Stable too.
+		sort.Sort(types.MethodsByName(methods))
+		sort.Stable(types.EmbeddedsByName(embeddeds))
+
 		w.startType(interfaceType)
 		w.setPkg(t.Pkg(), true)
 
@@ -881,6 +997,19 @@
 			w.signature(f.Type)
 		}
 
+	case types.TUNION:
+		assert(base.Flag.G > 0)
+		// TODO(danscales): possibly put out the tilde bools in more
+		// compact form.
+		w.startType(unionType)
+		nt := t.NumTerms()
+		w.uint64(uint64(nt))
+		for i := 0; i < nt; i++ {
+			typ, tilde := t.Term(i)
+			w.bool(tilde)
+			w.typ(typ)
+		}
+
 	default:
 		base.Fatalf("unexpected type: %v", t)
 	}
@@ -906,6 +1035,23 @@
 	}
 }
 
+func (w *exportWriter) typeList(ts []*types.Type) {
+	w.uint64(uint64(len(ts)))
+	for _, rparam := range ts {
+		w.typ(rparam)
+	}
+}
+
+func (w *exportWriter) tparamList(fs []*types.Field) {
+	w.uint64(uint64(len(fs)))
+	for _, f := range fs {
+		if !f.Type.IsTypeParam() {
+			base.Fatalf("unexpected non-typeparam")
+		}
+		w.typ(f.Type)
+	}
+}
+
 func (w *exportWriter) paramList(fs []*types.Field) {
 	w.uint64(uint64(len(fs)))
 	for _, f := range fs {
@@ -948,26 +1094,50 @@
 }
 
 func (w *exportWriter) value(typ *types.Type, v constant.Value) {
-	ir.AssertValidTypeForConst(typ, v)
 	w.typ(typ)
+	var kind constant.Kind
+	var valType *types.Type
 
-	// Each type has only one admissible constant representation,
-	// so we could type switch directly on v.U here. However,
-	// switching on the type increases symmetry with import logic
-	// and provides a useful consistency check.
+	if typ.IsTypeParam() {
+		// A constant will have a TYPEPARAM type if it appears in a place
+		// where it must match that typeparam type (e.g. in a binary
+		// operation with a variable of that typeparam type). If so, then
+		// we must write out its actual constant kind as well, so its
+		// constant val can be read in properly during import.
+		kind = v.Kind()
+		w.int64(int64(kind))
 
-	switch constTypeOf(typ) {
+		switch kind {
+		case constant.Int:
+			valType = types.Types[types.TINT64]
+		case constant.Float:
+			valType = types.Types[types.TFLOAT64]
+		case constant.Complex:
+			valType = types.Types[types.TCOMPLEX128]
+		}
+	} else {
+		ir.AssertValidTypeForConst(typ, v)
+		kind = constTypeOf(typ)
+		valType = typ
+	}
+
+	// Each type has only one admissible constant representation, so we could
+	// type switch directly on v.Kind() here. However, switching on the type
+	// (in the non-typeparam case) increases symmetry with import logic and
+	// provides a useful consistency check.
+
+	switch kind {
 	case constant.Bool:
 		w.bool(constant.BoolVal(v))
 	case constant.String:
 		w.string(constant.StringVal(v))
 	case constant.Int:
-		w.mpint(v, typ)
+		w.mpint(v, valType)
 	case constant.Float:
-		w.mpfloat(v, typ)
+		w.mpfloat(v, valType)
 	case constant.Complex:
-		w.mpfloat(constant.Real(v), typ)
-		w.mpfloat(constant.Imag(v), typ)
+		w.mpfloat(constant.Real(v), valType)
+		w.mpfloat(constant.Imag(v), valType)
 	}
 }
 
@@ -1185,10 +1355,14 @@
 		}
 	}
 
-	// Inline body.
+	// Write out inline body or body of a generic function/method.
+	if n.Type().HasTParam() && n.Func.Body != nil && n.Func.Inl == nil {
+		base.FatalfAt(n.Pos(), "generic function is not marked inlineable")
+	}
 	if n.Func.Inl != nil {
 		w.uint64(1 + uint64(n.Func.Inl.Cost))
-		if n.Func.ExportInline() {
+		w.bool(n.Func.Inl.CanDelayResults)
+		if n.Func.ExportInline() || n.Type().HasTParam() {
 			w.p.doInline(n)
 		}
 
@@ -1432,7 +1606,12 @@
 	w.uint64(uint64(len(cases)))
 	for _, cas := range cases {
 		w.pos(cas.Pos())
-		w.node(cas.Comm)
+		defaultCase := cas.Comm == nil
+		w.bool(defaultCase)
+		if !defaultCase {
+			// Only call w.node for non-default cause (cas.Comm is non-nil)
+			w.node(cas.Comm)
+		}
 		w.stmtList(cas.Body)
 	}
 }
@@ -1460,7 +1639,9 @@
 	// (somewhat closely following the structure of exprfmt in fmt.go)
 	case ir.ONIL:
 		n := n.(*ir.NilExpr)
-		if !n.Type().HasNil() {
+		// If n is a typeparam, it will have already been checked
+		// for proper use by the types2 typechecker.
+		if !n.Type().IsTypeParam() && !n.Type().HasNil() {
 			base.Fatalf("unexpected type for nil: %v", n.Type())
 		}
 		w.op(ir.ONIL)
@@ -1469,7 +1650,11 @@
 
 	case ir.OLITERAL:
 		w.op(ir.OLITERAL)
-		w.pos(n.Pos())
+		if ir.HasUniquePos(n) {
+			w.pos(n.Pos())
+		} else {
+			w.pos(src.NoXPos)
+		}
 		w.value(n.Type(), n.Val())
 
 	case ir.ONAME:
@@ -1488,6 +1673,16 @@
 		// We don't need a type here, as the type will be provided at the
 		// declaration of n.
 		w.op(ir.ONAME)
+
+		// This handles the case where we haven't yet transformed a call
+		// to a builtin, so we must write out the builtin as a name in the
+		// builtin package.
+		isBuiltin := n.BuiltinOp != ir.OXXX
+		w.bool(isBuiltin)
+		if isBuiltin {
+			w.string(n.Sym().Name)
+			break
+		}
 		w.localName(n)
 
 	// case OPACK, ONONAME:
@@ -1585,12 +1780,11 @@
 	// case OSTRUCTKEY:
 	//	unreachable - handled in case OSTRUCTLIT by elemList
 
-	case ir.OXDOT, ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
+	case ir.OXDOT, ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OMETHVALUE, ir.OMETHEXPR:
 		n := n.(*ir.SelectorExpr)
 		if go117ExportTypes {
-			if n.Op() == ir.OXDOT {
-				base.Fatalf("shouldn't encounter XDOT  in new exporter")
-			}
+			// For go117ExportTypes, we usually see all ops except
+			// OXDOT, but we can see OXDOT for generic functions.
 			w.op(n.Op())
 		} else {
 			w.op(ir.OXDOT)
@@ -1600,11 +1794,16 @@
 		w.exoticSelector(n.Sel)
 		if go117ExportTypes {
 			w.exoticType(n.Type())
-			if n.Op() == ir.ODOT || n.Op() == ir.ODOTPTR || n.Op() == ir.ODOTINTER {
+			if n.Op() == ir.OXDOT {
+				// n.Selection for method references will be
+				// reconstructed during import.
+				w.bool(n.Selection != nil)
+			} else if n.Op() == ir.ODOT || n.Op() == ir.ODOTPTR || n.Op() == ir.ODOTINTER {
 				w.exoticField(n.Selection)
 			}
-			// n.Selection is not required for OMETHEXPR, ODOTMETH, and OCALLPART. It will
-			// be reconstructed during import.
+			// n.Selection is not required for OMETHEXPR, ODOTMETH, and OMETHVALUE. It will
+			// be reconstructed during import.  n.Selection is computed during
+			// transformDot() for OXDOT.
 		}
 
 	case ir.ODOTTYPE, ir.ODOTTYPE2:
@@ -1629,7 +1828,7 @@
 		w.expr(n.X)
 		w.expr(n.Index)
 		if go117ExportTypes {
-			w.typ(n.Type())
+			w.exoticType(n.Type())
 			if n.Op() == ir.OINDEXMAP {
 				w.bool(n.Assigned)
 			}
@@ -1677,7 +1876,7 @@
 			w.op(ir.OEND)
 		}
 
-	case ir.OCONV, ir.OCONVIFACE, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
+	case ir.OCONV, ir.OCONVIFACE, ir.OCONVIDATA, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
 		n := n.(*ir.ConvExpr)
 		if go117ExportTypes {
 			w.op(n.Op())
@@ -1732,7 +1931,6 @@
 		w.bool(n.IsDDD)
 		if go117ExportTypes {
 			w.exoticType(n.Type())
-			w.uint64(uint64(n.Use))
 		}
 
 	case ir.OMAKEMAP, ir.OMAKECHAN, ir.OMAKESLICE:
@@ -1759,8 +1957,16 @@
 			w.op(ir.OEND)
 		}
 
+	case ir.OLINKSYMOFFSET:
+		n := n.(*ir.LinksymOffsetExpr)
+		w.op(ir.OLINKSYMOFFSET)
+		w.pos(n.Pos())
+		w.string(n.Linksym.Name)
+		w.uint64(uint64(n.Offset_))
+		w.typ(n.Type())
+
 	// unary expressions
-	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV:
+	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV, ir.OIDATA:
 		n := n.(*ir.UnaryExpr)
 		w.op(n.Op())
 		w.pos(n.Pos())
@@ -1796,7 +2002,7 @@
 
 	// binary expressions
 	case ir.OADD, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OEQ, ir.OGE, ir.OGT, ir.OLE, ir.OLT,
-		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR:
+		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR, ir.OEFACE:
 		n := n.(*ir.BinaryExpr)
 		w.op(n.Op())
 		w.pos(n.Pos())
@@ -1829,6 +2035,26 @@
 		// if exporting, DCLCONST should just be removed as its usage
 		// has already been replaced with literals
 
+	case ir.OFUNCINST:
+		n := n.(*ir.InstExpr)
+		w.op(ir.OFUNCINST)
+		w.pos(n.Pos())
+		w.expr(n.X)
+		w.uint64(uint64(len(n.Targs)))
+		for _, targ := range n.Targs {
+			w.typ(targ.Type())
+		}
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
+
+	case ir.OSELRECV2:
+		n := n.(*ir.AssignListStmt)
+		w.op(ir.OSELRECV2)
+		w.pos(n.Pos())
+		w.exprList(n.Lhs)
+		w.exprList(n.Rhs)
+
 	default:
 		base.Fatalf("cannot export %v (%d) node\n"+
 			"\t==> please file an issue and assign to gri@", n.Op(), int(n.Op()))
@@ -1864,11 +2090,8 @@
 	for _, n := range list {
 		n := n.(*ir.StructKeyExpr)
 		w.pos(n.Pos())
-		w.selector(n.Field)
+		w.exoticField(n.Field)
 		w.expr(n.Value)
-		if go117ExportTypes {
-			w.uint64(uint64(n.Offset))
-		}
 	}
 }
 
@@ -1902,8 +2125,15 @@
 		return
 	}
 
-	// TODO(mdempsky): Fix autotmp hack.
-	if i := strings.LastIndex(name, "."); i >= 0 && !strings.HasPrefix(name, ".autotmp_") {
+	// The name of autotmp variables isn't important; they just need to
+	// be unique. To stabilize the export data, simply write out "$" as
+	// a marker and let the importer generate its own unique name.
+	if strings.HasPrefix(name, ".autotmp_") {
+		w.string("$autotmp")
+		return
+	}
+
+	if i := strings.LastIndex(name, "."); i >= 0 && !strings.HasPrefix(name, ".dict") { // TODO: just use autotmp names for dictionaries?
 		base.Fatalf("unexpected dot in identifier: %v", name)
 	}
 
diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 37f5a7b..2e3fdbc 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -8,10 +8,10 @@
 package typecheck
 
 import (
+	"bytes"
 	"encoding/binary"
 	"fmt"
 	"go/constant"
-	"io"
 	"math/big"
 	"os"
 	"strings"
@@ -19,8 +19,6 @@
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/types"
-	"cmd/internal/bio"
-	"cmd/internal/goobj"
 	"cmd/internal/obj"
 	"cmd/internal/src"
 )
@@ -94,7 +92,7 @@
 }
 
 type intReader struct {
-	*bio.Reader
+	*strings.Reader
 	pkg *types.Pkg
 }
 
@@ -116,33 +114,34 @@
 	return i
 }
 
-func ReadImports(pkg *types.Pkg, in *bio.Reader) (fingerprint goobj.FingerprintType) {
-	ird := &intReader{in, pkg}
+func ReadImports(pkg *types.Pkg, data string) {
+	ird := &intReader{strings.NewReader(data), pkg}
 
 	version := ird.uint64()
-	if version != iexportVersion {
-		base.Errorf("import %q: unknown export format version %d", pkg.Path, version)
+	switch version {
+	case /* iexportVersionGenerics, */ iexportVersionPosCol, iexportVersionGo1_11:
+	default:
+		if version > iexportVersionGenerics {
+			base.Errorf("import %q: unstable export format version %d, just recompile", pkg.Path, version)
+		} else {
+			base.Errorf("import %q: unknown export format version %d", pkg.Path, version)
+		}
 		base.ErrorExit()
 	}
 
-	sLen := ird.uint64()
-	dLen := ird.uint64()
+	sLen := int64(ird.uint64())
+	dLen := int64(ird.uint64())
 
-	// Map string (and data) section into memory as a single large
-	// string. This reduces heap fragmentation and allows
-	// returning individual substrings very efficiently.
-	data, err := mapFile(in.File(), in.Offset(), int64(sLen+dLen))
-	if err != nil {
-		base.Errorf("import %q: mapping input: %v", pkg.Path, err)
-		base.ErrorExit()
-	}
-	stringData := data[:sLen]
-	declData := data[sLen:]
-
-	in.MustSeek(int64(sLen+dLen), os.SEEK_CUR)
+	// TODO(mdempsky): Replace os.SEEK_CUR with io.SeekCurrent after
+	// #44505 is fixed.
+	whence, _ := ird.Seek(0, os.SEEK_CUR)
+	stringData := data[whence : whence+sLen]
+	declData := data[whence+sLen : whence+sLen+dLen]
+	ird.Seek(sLen+dLen, os.SEEK_CUR)
 
 	p := &iimporter{
-		ipkg: pkg,
+		exportVersion: version,
+		ipkg:          pkg,
 
 		pkgCache:     map[uint64]*types.Pkg{},
 		posBaseCache: map[uint64]*src.PosBase{},
@@ -200,18 +199,11 @@
 			}
 		}
 	}
-
-	// Fingerprint.
-	_, err = io.ReadFull(in, fingerprint[:])
-	if err != nil {
-		base.Errorf("import %s: error reading fingerprint", pkg.Path)
-		base.ErrorExit()
-	}
-	return fingerprint
 }
 
 type iimporter struct {
-	ipkg *types.Pkg
+	exportVersion uint64
+	ipkg          *types.Pkg
 
 	pkgCache     map[uint64]*types.Pkg
 	posBaseCache map[uint64]*src.PosBase
@@ -273,6 +265,7 @@
 	// Slice of all dcls for function, including any interior closures
 	allDcls        []*ir.Name
 	allClosureVars []*ir.Name
+	autotmpgen     int
 }
 
 func (p *iimporter) newReader(off uint64, pkg *types.Pkg) *importReader {
@@ -302,37 +295,53 @@
 	case 'A':
 		typ := r.typ()
 
-		return importalias(r.p.ipkg, pos, sym, typ)
+		return importalias(pos, sym, typ)
 
 	case 'C':
 		typ := r.typ()
 		val := r.value(typ)
 
-		n := importconst(r.p.ipkg, pos, sym, typ, val)
+		n := importconst(pos, sym, typ, val)
 		r.constExt(n)
 		return n
 
-	case 'F':
-		typ := r.signature(nil)
+	case 'F', 'G':
+		var tparams []*types.Field
+		if tag == 'G' {
+			tparams = r.tparamList()
+		}
+		typ := r.signature(nil, tparams)
 
-		n := importfunc(r.p.ipkg, pos, sym, typ)
+		n := importfunc(pos, sym, typ)
 		r.funcExt(n)
 		return n
 
-	case 'T':
+	case 'T', 'U':
+		var rparams []*types.Type
+		if tag == 'U' {
+			rparams = r.typeList()
+		}
+
 		// Types can be recursive. We need to setup a stub
 		// declaration before recursing.
-		n := importtype(r.p.ipkg, pos, sym)
+		n := importtype(pos, sym)
 		t := n.Type()
+		if tag == 'U' {
+			t.SetRParams(rparams)
+		}
 
 		// We also need to defer width calculations until
 		// after the underlying type has been assigned.
 		types.DeferCheckSize()
+		deferDoInst()
 		underlying := r.typ()
 		t.SetUnderlying(underlying)
-		types.ResumeCheckSize()
 
 		if underlying.IsInterface() {
+			// Finish up all type instantiations and CheckSize calls
+			// now that a top-level type is fully constructed.
+			resumeDoInst()
+			types.ResumeCheckSize()
 			r.typeExt(t)
 			return n
 		}
@@ -342,7 +351,7 @@
 			mpos := r.pos()
 			msym := r.selector()
 			recv := r.param()
-			mtyp := r.signature(recv)
+			mtyp := r.signature(recv, nil)
 
 			// MethodSym already marked m.Sym as a function.
 			m := ir.NewNameAt(mpos, ir.MethodSym(recv.Type, msym))
@@ -358,16 +367,43 @@
 		}
 		t.Methods().Set(ms)
 
+		// Finish up all instantiations and CheckSize calls now
+		// that a top-level type is fully constructed.
+		resumeDoInst()
+		types.ResumeCheckSize()
+
 		r.typeExt(t)
 		for _, m := range ms {
 			r.methExt(m)
 		}
 		return n
 
+	case 'P':
+		if r.p.exportVersion < iexportVersionGenerics {
+			base.Fatalf("unexpected type param type")
+		}
+		if sym.Def != nil {
+			// Make sure we use the same type param type for the same
+			// name, whether it is created during types1-import or
+			// this types2-to-types1 translation.
+			return sym.Def.(*ir.Name)
+		}
+		// The typeparam index is set at the point where the containing type
+		// param list is imported.
+		t := types.NewTypeParam(sym, 0)
+		// Nname needed to save the pos.
+		nname := ir.NewDeclNameAt(pos, ir.OTYPE, sym)
+		sym.Def = nname
+		nname.SetType(t)
+		t.SetNod(nname)
+
+		t.SetBound(r.typ())
+		return nname
+
 	case 'V':
 		typ := r.typ()
 
-		n := importvar(r.p.ipkg, pos, sym, typ)
+		n := importvar(pos, sym, typ)
 		r.varExt(n)
 		return n
 
@@ -377,27 +413,47 @@
 	}
 }
 
-func (p *importReader) value(typ *types.Type) constant.Value {
-	switch constTypeOf(typ) {
+func (r *importReader) value(typ *types.Type) constant.Value {
+	var kind constant.Kind
+	var valType *types.Type
+
+	if typ.IsTypeParam() {
+		// If a constant had a typeparam type, then we wrote out its
+		// actual constant kind as well.
+		kind = constant.Kind(r.int64())
+		switch kind {
+		case constant.Int:
+			valType = types.Types[types.TINT64]
+		case constant.Float:
+			valType = types.Types[types.TFLOAT64]
+		case constant.Complex:
+			valType = types.Types[types.TCOMPLEX128]
+		}
+	} else {
+		kind = constTypeOf(typ)
+		valType = typ
+	}
+
+	switch kind {
 	case constant.Bool:
-		return constant.MakeBool(p.bool())
+		return constant.MakeBool(r.bool())
 	case constant.String:
-		return constant.MakeString(p.string())
+		return constant.MakeString(r.string())
 	case constant.Int:
 		var i big.Int
-		p.mpint(&i, typ)
+		r.mpint(&i, valType)
 		return constant.Make(&i)
 	case constant.Float:
-		return p.float(typ)
+		return r.float(valType)
 	case constant.Complex:
-		return makeComplex(p.float(typ), p.float(typ))
+		return makeComplex(r.float(valType), r.float(valType))
 	}
 
 	base.Fatalf("unexpected value type: %v", typ)
 	panic("unreachable")
 }
 
-func (p *importReader) mpint(x *big.Int, typ *types.Type) {
+func (r *importReader) mpint(x *big.Int, typ *types.Type) {
 	signed, maxBytes := intSize(typ)
 
 	maxSmall := 256 - maxBytes
@@ -408,7 +464,7 @@
 		maxSmall = 256
 	}
 
-	n, _ := p.ReadByte()
+	n, _ := r.ReadByte()
 	if uint(n) < maxSmall {
 		v := int64(n)
 		if signed {
@@ -429,30 +485,30 @@
 		base.Fatalf("weird decoding: %v, %v => %v", n, signed, v)
 	}
 	b := make([]byte, v)
-	p.Read(b)
+	r.Read(b)
 	x.SetBytes(b)
 	if signed && n&1 != 0 {
 		x.Neg(x)
 	}
 }
 
-func (p *importReader) float(typ *types.Type) constant.Value {
+func (r *importReader) float(typ *types.Type) constant.Value {
 	var mant big.Int
-	p.mpint(&mant, typ)
+	r.mpint(&mant, typ)
 	var f big.Float
 	f.SetInt(&mant)
 	if f.Sign() != 0 {
-		f.SetMantExp(&f, int(p.int64()))
+		f.SetMantExp(&f, int(r.int64()))
 	}
 	return constant.Make(&f)
 }
 
-func (p *importReader) mprat(orig constant.Value) constant.Value {
-	if !p.bool() {
+func (r *importReader) mprat(orig constant.Value) constant.Value {
+	if !r.bool() {
 		return orig
 	}
 	var rat big.Rat
-	rat.SetString(p.string())
+	rat.SetString(r.string())
 	return constant.Make(&rat)
 }
 
@@ -462,8 +518,15 @@
 		return nil
 	}
 	pkg := r.currPkg
-	if selector && types.IsExported(name) {
-		pkg = types.LocalPkg
+	if selector {
+		if types.IsExported(name) {
+			pkg = types.LocalPkg
+		}
+	} else {
+		if name == "$autotmp" {
+			name = autotmpname(r.autotmpgen)
+			r.autotmpgen++
+		}
 	}
 	return pkg.Lookup(name)
 }
@@ -503,7 +566,14 @@
 }
 
 func (r *importReader) typ() *types.Type {
-	return r.p.typAt(r.uint64())
+	// If this is a top-level type call, defer type instantiations until the
+	// type is fully constructed.
+	types.DeferCheckSize()
+	deferDoInst()
+	t := r.p.typAt(r.uint64())
+	resumeDoInst()
+	types.ResumeCheckSize()
+	return t
 }
 
 func (r *importReader) exoticType() *types.Type {
@@ -641,7 +711,13 @@
 		// are pushed to compile queue, then draining from the queue for compiling.
 		// During this process, the size calculation is disabled, so it is not safe for
 		// calculating size during SSA generation anymore. See issue #44732.
-		types.CheckSize(t)
+		//
+		// No need to calc sizes for re-instantiated generic types, and
+		// they are not necessarily resolved until the top-level type is
+		// defined (because of recursive types).
+		if t.OrigSym == nil || !t.HasTParam() {
+			types.CheckSize(t)
+		}
 		p.typCache[off] = t
 	}
 	return t
@@ -680,7 +756,7 @@
 
 	case signatureType:
 		r.setPkg()
-		return r.signature(nil)
+		return r.signature(nil, nil)
 
 	case structType:
 		r.setPkg()
@@ -718,16 +794,64 @@
 		for i := range methods {
 			pos := r.pos()
 			sym := r.selector()
-			typ := r.signature(fakeRecvField())
+			typ := r.signature(fakeRecvField(), nil)
 
 			methods[i] = types.NewField(pos, sym, typ)
 		}
 
+		if len(embeddeds)+len(methods) == 0 {
+			return types.Types[types.TINTER]
+		}
+
 		t := types.NewInterface(r.currPkg, append(embeddeds, methods...))
 
 		// Ensure we expand the interface in the frontend (#25055).
 		types.CheckSize(t)
 		return t
+
+	case typeParamType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			base.Fatalf("unexpected type param type")
+		}
+		// Similar to code for defined types, since we "declared"
+		// typeparams to deal with recursion (typeparam is used within its
+		// own type bound).
+		ident := r.qualifiedIdent()
+		if ident.Sym().Def != nil {
+			return ident.Sym().Def.(*ir.Name).Type()
+		}
+		n := expandDecl(ident)
+		if n.Op() != ir.OTYPE {
+			base.Fatalf("expected OTYPE, got %v: %v, %v", n.Op(), n.Sym(), n)
+		}
+		return n.Type()
+
+	case instType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			base.Fatalf("unexpected instantiation type")
+		}
+		pos := r.pos()
+		len := r.uint64()
+		targs := make([]*types.Type, len)
+		for i := range targs {
+			targs[i] = r.typ()
+		}
+		baseType := r.typ()
+		t := Instantiate(pos, baseType, targs)
+		return t
+
+	case unionType:
+		if r.p.exportVersion < iexportVersionGenerics {
+			base.Fatalf("unexpected instantiation type")
+		}
+		nt := int(r.uint64())
+		terms := make([]*types.Type, nt)
+		tildes := make([]bool, nt)
+		for i := range terms {
+			tildes[i] = r.bool()
+			terms[i] = r.typ()
+		}
+		return types.NewUnion(terms, tildes)
 	}
 }
 
@@ -735,13 +859,42 @@
 	return itag(r.uint64())
 }
 
-func (r *importReader) signature(recv *types.Field) *types.Type {
+func (r *importReader) signature(recv *types.Field, tparams []*types.Field) *types.Type {
 	params := r.paramList()
 	results := r.paramList()
 	if n := len(params); n > 0 {
 		params[n-1].SetIsDDD(r.bool())
 	}
-	return types.NewSignature(r.currPkg, recv, nil, params, results)
+	return types.NewSignature(r.currPkg, recv, tparams, params, results)
+}
+
+func (r *importReader) typeList() []*types.Type {
+	n := r.uint64()
+	if n == 0 {
+		return nil
+	}
+	ts := make([]*types.Type, n)
+	for i := range ts {
+		ts[i] = r.typ()
+		if ts[i].IsTypeParam() {
+			ts[i].SetIndex(i)
+		}
+	}
+	return ts
+}
+
+func (r *importReader) tparamList() []*types.Field {
+	n := r.uint64()
+	if n == 0 {
+		return nil
+	}
+	fs := make([]*types.Field, n)
+	for i := range fs {
+		typ := r.typ()
+		typ.SetIndex(i)
+		fs[i] = types.NewField(typ.Pos(), typ.Sym(), typ)
+	}
+	return fs
 }
 
 func (r *importReader) paramList() []*types.Field {
@@ -809,7 +962,9 @@
 
 	n.Func.ABI = obj.ABI(r.uint64())
 
-	n.SetPragma(ir.PragmaFlag(r.uint64()))
+	// Make sure //go:noinline pragma is imported (so stenciled functions have
+	// same noinline status as the corresponding generic function.)
+	n.Func.Pragma = ir.PragmaFlag(r.uint64())
 
 	// Escape analysis.
 	for _, fs := range &types.RecvsParams {
@@ -821,7 +976,8 @@
 	// Inline body.
 	if u := r.uint64(); u > 0 {
 		n.Func.Inl = &ir.Inline{
-			Cost: int32(u - 1),
+			Cost:            int32(u - 1),
+			CanDelayResults: r.bool(),
 		}
 		n.Func.Endlineno = r.pos()
 	}
@@ -852,7 +1008,13 @@
 
 func (r *importReader) typeExt(t *types.Type) {
 	t.SetNotInHeap(r.bool())
-	i, pi := r.int64(), r.int64()
+	SetBaseTypeIndex(t, r.int64(), r.int64())
+}
+
+func SetBaseTypeIndex(t *types.Type, i, pi int64) {
+	if t.Obj() == nil {
+		base.Fatalf("SetBaseTypeIndex on non-defined type %v", t)
+	}
 	if i != -1 && pi != -1 {
 		typeSymIdx[t] = [2]int64{i, pi}
 	}
@@ -860,6 +1022,7 @@
 
 // Map imported type T to the index of type descriptor symbols of T and *T,
 // so we can use index to reference the symbol.
+// TODO(mdempsky): Store this information directly in the Type's Name.
 var typeSymIdx = make(map[*types.Type][2]int64)
 
 func BaseTypeIndex(t *types.Type) int64 {
@@ -936,6 +1099,10 @@
 	fn.Inl.Body = body
 
 	r.curfn = outerfn
+	if base.Flag.W >= 3 {
+		fmt.Printf("Imported for %v", fn)
+		ir.DumpList("", fn.Inl.Body)
+	}
 }
 
 func (r *importReader) readNames(fn *ir.Func) []*ir.Name {
@@ -1032,7 +1199,13 @@
 func (r *importReader) commList() []*ir.CommClause {
 	cases := make([]*ir.CommClause, r.uint64())
 	for i := range cases {
-		cases[i] = ir.NewCommStmt(r.pos(), r.node(), r.stmtList())
+		pos := r.pos()
+		defaultCase := r.bool()
+		var comm ir.Node
+		if !defaultCase {
+			comm = r.node()
+		}
+		cases[i] = ir.NewCommStmt(pos, comm, r.stmtList())
 	}
 	return cases
 }
@@ -1095,6 +1268,10 @@
 		return n
 
 	case ir.ONAME:
+		isBuiltin := r.bool()
+		if isBuiltin {
+			return types.BuiltinPkg.Lookup(r.string()).Def.(*ir.Name)
+		}
 		return r.localName()
 
 	// case OPACK, ONONAME:
@@ -1117,28 +1294,18 @@
 	case ir.OCLOSURE:
 		//println("Importing CLOSURE")
 		pos := r.pos()
-		typ := r.signature(nil)
+		typ := r.signature(nil, nil)
 
 		// All the remaining code below is similar to (*noder).funcLit(), but
 		// with Dcls and ClosureVars lists already set up
-		fn := ir.NewFunc(pos)
-		fn.SetIsHiddenClosure(true)
-		fn.Nname = ir.NewNameAt(pos, ir.BlankNode.Sym())
-		fn.Nname.Func = fn
-		fn.Nname.Ntype = ir.TypeNode(typ)
-		fn.Nname.Defn = fn
+		fn := ir.NewClosureFunc(pos, true)
 		fn.Nname.SetType(typ)
 
 		cvars := make([]*ir.Name, r.int64())
 		for i := range cvars {
 			cvars[i] = ir.CaptureName(r.pos(), fn, r.localName().Canonical())
-			if go117ExportTypes {
-				if cvars[i].Type() != nil || cvars[i].Defn == nil {
-					base.Fatalf("bad import of closure variable")
-				}
-				// Closure variable should have Defn set, which is its captured
-				// variable, and it gets the same type as the captured variable.
-				cvars[i].SetType(cvars[i].Defn.Type())
+			if go117ExportTypes && cvars[i].Defn == nil {
+				base.Fatalf("bad import of closure variable")
 			}
 		}
 		fn.ClosureVars = cvars
@@ -1159,12 +1326,10 @@
 
 		ir.FinishCaptureNames(pos, r.curfn, fn)
 
-		clo := ir.NewClosureExpr(pos, fn)
-		fn.OClosure = clo
+		clo := fn.OClosure
 		if go117ExportTypes {
 			clo.SetType(typ)
 		}
-
 		return clo
 
 	case ir.OSTRUCTLIT:
@@ -1202,35 +1367,54 @@
 	// case OSTRUCTKEY:
 	//	unreachable - handled in case OSTRUCTLIT by elemList
 
-	case ir.OXDOT:
-		// see parser.new_dotname
-		if go117ExportTypes {
-			base.Fatalf("shouldn't encounter XDOT in new importer")
-		}
-		return ir.NewSelectorExpr(r.pos(), ir.OXDOT, r.expr(), r.exoticSelector())
-
-	case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
-		if !go117ExportTypes {
-			// unreachable - mapped to case OXDOT by exporter
+	case ir.OXDOT, ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OMETHVALUE, ir.OMETHEXPR:
+		// For !go117ExportTypes,  we should only see OXDOT.
+		// For go117ExportTypes, we usually see all the other ops, but can see
+		// OXDOT for generic functions.
+		if op != ir.OXDOT && !go117ExportTypes {
 			goto error
 		}
 		pos := r.pos()
 		expr := r.expr()
 		sel := r.exoticSelector()
 		n := ir.NewSelectorExpr(pos, op, expr, sel)
-		n.SetType(r.exoticType())
-		switch op {
-		case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER:
-			n.Selection = r.exoticField()
-		case ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
-			// These require a Lookup to link to the correct declaration.
-			rcvrType := expr.Type()
-			typ := n.Type()
-			n.Selection = Lookdot(n, rcvrType, 1)
-			if op == ir.OCALLPART || op == ir.OMETHEXPR {
-				// Lookdot clobbers the opcode and type, undo that.
-				n.SetOp(op)
-				n.SetType(typ)
+		if go117ExportTypes {
+			n.SetType(r.exoticType())
+			switch op {
+			case ir.OXDOT:
+				hasSelection := r.bool()
+				// We reconstruct n.Selection for method calls on
+				// generic types and method calls due to type param
+				// bounds.  Otherwise, n.Selection is nil.
+				if hasSelection {
+					n1 := ir.NewSelectorExpr(pos, op, expr, sel)
+					AddImplicitDots(n1)
+					var m *types.Field
+					if n1.X.Type().IsTypeParam() {
+						genType := n1.X.Type().Bound()
+						m = Lookdot1(n1, sel, genType, genType.AllMethods(), 1)
+					} else {
+						genType := types.ReceiverBaseType(n1.X.Type())
+						if genType.IsInstantiatedGeneric() {
+							genType = genType.OrigSym.Def.Type()
+						}
+						m = Lookdot1(n1, sel, genType, genType.Methods(), 1)
+					}
+					assert(m != nil)
+					n.Selection = m
+				}
+			case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER:
+				n.Selection = r.exoticField()
+			case ir.ODOTMETH, ir.OMETHVALUE, ir.OMETHEXPR:
+				// These require a Lookup to link to the correct declaration.
+				rcvrType := expr.Type()
+				typ := n.Type()
+				n.Selection = Lookdot(n, rcvrType, 1)
+				if op == ir.OMETHVALUE || op == ir.OMETHEXPR {
+					// Lookdot clobbers the opcode and type, undo that.
+					n.SetOp(op)
+					n.SetType(typ)
+				}
 			}
 		}
 		return n
@@ -1247,7 +1431,7 @@
 		n := ir.NewIndexExpr(r.pos(), r.expr(), r.expr())
 		if go117ExportTypes {
 			n.SetOp(op)
-			n.SetType(r.typ())
+			n.SetType(r.exoticType())
 			if op == ir.OINDEXMAP {
 				n.Assigned = r.bool()
 			}
@@ -1267,7 +1451,7 @@
 		}
 		return n
 
-	case ir.OCONV, ir.OCONVIFACE, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
+	case ir.OCONV, ir.OCONVIFACE, ir.OCONVIDATA, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
 		if !go117ExportTypes && op != ir.OCONV {
 			// 	unreachable - mapped to OCONV case by exporter
 			goto error
@@ -1318,7 +1502,6 @@
 		n.IsDDD = r.bool()
 		if go117ExportTypes {
 			n.SetType(r.exoticType())
-			n.Use = ir.CallUse(r.uint64())
 		}
 		return n
 
@@ -1343,8 +1526,15 @@
 		n.Args.Append(r.exprList()...)
 		return n
 
+	case ir.OLINKSYMOFFSET:
+		pos := r.pos()
+		name := r.string()
+		off := r.uint64()
+		typ := r.typ()
+		return ir.NewLinksymOffsetExpr(pos, Lookup(name).Linksym(), int64(off), typ)
+
 	// unary expressions
-	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV:
+	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV, ir.OIDATA:
 		n := ir.NewUnaryExpr(r.pos(), op, r.expr())
 		if go117ExportTypes {
 			n.SetType(r.typ())
@@ -1368,7 +1558,7 @@
 
 	// binary expressions
 	case ir.OADD, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OEQ, ir.OGE, ir.OGT, ir.OLE, ir.OLT,
-		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR:
+		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR, ir.OEFACE:
 		n := ir.NewBinaryExpr(r.pos(), op, r.expr(), r.expr())
 		if go117ExportTypes {
 			n.SetType(r.typ())
@@ -1496,6 +1686,26 @@
 	case ir.OEND:
 		return nil
 
+	case ir.OFUNCINST:
+		pos := r.pos()
+		x := r.expr()
+		ntargs := r.uint64()
+		var targs []ir.Node
+		if ntargs > 0 {
+			targs = make([]ir.Node, ntargs)
+			for i := range targs {
+				targs[i] = ir.TypeNode(r.typ())
+			}
+		}
+		n := ir.NewInstExpr(pos, ir.OFUNCINST, x, targs)
+		if go117ExportTypes {
+			n.SetType(r.typ())
+		}
+		return n
+
+	case ir.OSELRECV2:
+		return ir.NewAssignListStmt(r.pos(), ir.OSELRECV2, r.exprList(), r.exprList())
+
 	default:
 		base.Fatalf("cannot import %v (%d) node\n"+
 			"\t==> please file an issue and assign to gri@", op, int(op))
@@ -1517,11 +1727,7 @@
 func (r *importReader) fieldList() []ir.Node {
 	list := make([]ir.Node, r.uint64())
 	for i := range list {
-		x := ir.NewStructKeyExpr(r.pos(), r.selector(), r.expr())
-		if go117ExportTypes {
-			x.Offset = int64(r.uint64())
-		}
-		list[i] = x
+		list[i] = ir.NewStructKeyExpr(r.pos(), r.exoticField(), r.expr())
 	}
 	return list
 }
@@ -1544,3 +1750,146 @@
 	}
 	return ir.NewCallExpr(pos, ir.OCALL, ir.NewIdent(base.Pos, types.BuiltinPkg.Lookup(ir.OpNames[op])), nil)
 }
+
+// InstTypeName creates a name for an instantiated type, based on the name of the
+// generic type and the type args.
+func InstTypeName(name string, targs []*types.Type) string {
+	b := bytes.NewBufferString(name)
+	b.WriteByte('[')
+	for i, targ := range targs {
+		if i > 0 {
+			b.WriteByte(',')
+		}
+		// WriteString() does not include the package name for the local
+		// package, but we want it to make sure type arguments (including
+		// type params) are uniquely specified.
+		if targ.Sym() != nil && targ.Sym().Pkg == types.LocalPkg {
+			b.WriteString(targ.Sym().Pkg.Name)
+			b.WriteByte('.')
+		}
+		// types1 uses "interface {" and types2 uses "interface{" - convert
+		// to consistent types2 format.
+		tstring := targ.String()
+		tstring = strings.Replace(tstring, "interface {", "interface{", -1)
+		b.WriteString(tstring)
+	}
+	b.WriteByte(']')
+	return b.String()
+}
+
+// NewIncompleteNamedType returns a TFORW type t with name specified by sym, such
+// that t.nod and sym.Def are set correctly.
+func NewIncompleteNamedType(pos src.XPos, sym *types.Sym) *types.Type {
+	name := ir.NewDeclNameAt(pos, ir.OTYPE, sym)
+	forw := types.NewNamed(name)
+	name.SetType(forw)
+	sym.Def = name
+	return forw
+}
+
+// Instantiate creates a new named type which is the instantiation of the base
+// named generic type, with the specified type args.
+func Instantiate(pos src.XPos, baseType *types.Type, targs []*types.Type) *types.Type {
+	baseSym := baseType.Sym()
+	if strings.Index(baseSym.Name, "[") >= 0 {
+		base.Fatalf("arg to Instantiate is not a base generic type")
+	}
+	name := InstTypeName(baseSym.Name, targs)
+	instSym := baseSym.Pkg.Lookup(name)
+	if instSym.Def != nil {
+		// May match existing type from previous import or
+		// types2-to-types1 conversion, or from in-progress instantiation
+		// in the current type import stack.
+		return instSym.Def.Type()
+	}
+
+	t := NewIncompleteNamedType(baseType.Pos(), instSym)
+	t.SetRParams(targs)
+	t.OrigSym = baseSym
+
+	// baseType may still be TFORW or its methods may not be fully filled in
+	// (since we are in the middle of importing it). So, delay call to
+	// substInstType until we get back up to the top of the current top-most
+	// type import.
+	deferredInstStack = append(deferredInstStack, t)
+
+	return t
+}
+
+var deferredInstStack []*types.Type
+var deferInst int
+
+// deferDoInst defers substitution on instantiated types until we are at the
+// top-most defined type, so the base types are fully defined.
+func deferDoInst() {
+	deferInst++
+}
+
+func resumeDoInst() {
+	if deferInst == 1 {
+		for len(deferredInstStack) > 0 {
+			t := deferredInstStack[0]
+			deferredInstStack = deferredInstStack[1:]
+			substInstType(t, t.OrigSym.Def.(*ir.Name).Type(), t.RParams())
+		}
+	}
+	deferInst--
+}
+
+// doInst creates a new instantiation type (which will be added to
+// deferredInstStack for completion later) for an incomplete type encountered
+// during a type substitution for an instantiation. This is needed for
+// instantiations of mutually recursive types.
+func doInst(t *types.Type) *types.Type {
+	return Instantiate(t.Pos(), t.OrigSym.Def.(*ir.Name).Type(), t.RParams())
+}
+
+// substInstType completes the instantiation of a generic type by doing a
+// substitution on the underlying type itself and any methods. t is the
+// instantiation being created, baseType is the base generic type, and targs are
+// the type arguments that baseType is being instantiated with.
+func substInstType(t *types.Type, baseType *types.Type, targs []*types.Type) {
+	subst := Tsubster{
+		Tparams:       baseType.RParams(),
+		Targs:         targs,
+		SubstForwFunc: doInst,
+	}
+	t.SetUnderlying(subst.Typ(baseType.Underlying()))
+
+	newfields := make([]*types.Field, baseType.Methods().Len())
+	for i, f := range baseType.Methods().Slice() {
+		if !f.IsMethod() || types.IsInterfaceMethod(f.Type) {
+			// Do a normal substitution if this is a non-method (which
+			// means this must be an interface used as a constraint) or
+			// an interface method.
+			t2 := subst.Typ(f.Type)
+			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+			continue
+		}
+		recvType := f.Type.Recv().Type
+		if recvType.IsPtr() {
+			recvType = recvType.Elem()
+		}
+		// Substitute in the method using the type params used in the
+		// method (not the type params in the definition of the generic type).
+		msubst := Tsubster{
+			Tparams:       recvType.RParams(),
+			Targs:         targs,
+			SubstForwFunc: doInst,
+		}
+		t2 := msubst.Typ(f.Type)
+		oldsym := f.Nname.Sym()
+		newsym := MakeInstName(oldsym, targs, true)
+		var nname *ir.Name
+		if newsym.Def != nil {
+			nname = newsym.Def.(*ir.Name)
+		} else {
+			nname = ir.NewNameAt(f.Pos, newsym)
+			nname.SetType(t2)
+			newsym.Def = nname
+		}
+		newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+		newfields[i].Nname = nname
+	}
+	t.Methods().Set(newfields)
+}
diff --git a/src/cmd/compile/internal/typecheck/stmt.go b/src/cmd/compile/internal/typecheck/stmt.go
index 922a01b..c322d49 100644
--- a/src/cmd/compile/internal/typecheck/stmt.go
+++ b/src/cmd/compile/internal/typecheck/stmt.go
@@ -172,6 +172,10 @@
 			r := r.(*ir.TypeAssertExpr)
 			stmt.SetOp(ir.OAS2DOTTYPE)
 			r.SetOp(ir.ODOTTYPE2)
+		case ir.ODYNAMICDOTTYPE:
+			r := r.(*ir.DynamicTypeAssertExpr)
+			stmt.SetOp(ir.OAS2DOTTYPE)
+			r.SetOp(ir.ODYNAMICDOTTYPE2)
 		default:
 			break assignOK
 		}
@@ -201,7 +205,6 @@
 		stmt := stmt.(*ir.AssignListStmt)
 		stmt.SetOp(ir.OAS2FUNC)
 		r := rhs[0].(*ir.CallExpr)
-		r.Use = ir.CallUseList
 		rtyp := r.Type()
 
 		mismatched := false
@@ -217,7 +220,7 @@
 			}
 		}
 		if mismatched && !failed {
-			rewriteMultiValueCall(stmt, r)
+			RewriteMultiValueCall(stmt, r)
 		}
 		return
 	}
@@ -237,6 +240,15 @@
 	return "s"
 }
 
+// tcCheckNil typechecks an OCHECKNIL node.
+func tcCheckNil(n *ir.UnaryExpr) ir.Node {
+	n.X = Expr(n.X)
+	if !n.X.Type().IsPtrShaped() {
+		base.FatalfAt(n.Pos(), "%L is not pointer shaped", n.X)
+	}
+	return n
+}
+
 // tcFor typechecks an OFOR node.
 func tcFor(n *ir.ForStmt) ir.Node {
 	Stmts(n.Init())
@@ -653,29 +665,18 @@
 }
 
 type typeSet struct {
-	m map[string][]typeSetEntry
-}
-
-type typeSetEntry struct {
-	pos src.XPos
-	typ *types.Type
+	m map[string]src.XPos
 }
 
 func (s *typeSet) add(pos src.XPos, typ *types.Type) {
 	if s.m == nil {
-		s.m = make(map[string][]typeSetEntry)
+		s.m = make(map[string]src.XPos)
 	}
 
-	// LongString does not uniquely identify types, so we need to
-	// disambiguate collisions with types.Identical.
-	// TODO(mdempsky): Add a method that *is* unique.
-	ls := typ.LongString()
-	prevs := s.m[ls]
-	for _, prev := range prevs {
-		if types.Identical(typ, prev.typ) {
-			base.ErrorfAt(pos, "duplicate case %v in type switch\n\tprevious case at %s", typ, base.FmtPos(prev.pos))
-			return
-		}
+	ls := typ.LinkString()
+	if prev, ok := s.m[ls]; ok {
+		base.ErrorfAt(pos, "duplicate case %v in type switch\n\tprevious case at %s", typ, base.FmtPos(prev))
+		return
 	}
-	s.m[ls] = append(prevs, typeSetEntry{pos, typ})
+	s.m[ls] = pos
 }
diff --git a/src/cmd/compile/internal/typecheck/subr.go b/src/cmd/compile/internal/typecheck/subr.go
index 9ee7a94..e86c4c6 100644
--- a/src/cmd/compile/internal/typecheck/subr.go
+++ b/src/cmd/compile/internal/typecheck/subr.go
@@ -5,6 +5,7 @@
 package typecheck
 
 import (
+	"bytes"
 	"fmt"
 	"sort"
 	"strconv"
@@ -352,9 +353,10 @@
 		return ir.OCONVNOP, ""
 	}
 
-	// 2. src and dst have identical underlying types
-	// and either src or dst is not a named type or
-	// both are empty interface types.
+	// 2. src and dst have identical underlying types and
+	//   a. either src or dst is not a named type, or
+	//   b. both are empty interface types, or
+	//   c. at least one is a gcshape type.
 	// For assignable but different non-empty interface types,
 	// we want to recompute the itab. Recomputing the itab ensures
 	// that itabs are unique (thus an interface with a compile-time
@@ -371,21 +373,24 @@
 			// which need to have their itab updated.
 			return ir.OCONVNOP, ""
 		}
+		if src.IsShape() || dst.IsShape() {
+			// Conversion between a shape type and one of the types
+			// it represents also needs no conversion.
+			return ir.OCONVNOP, ""
+		}
 	}
 
 	// 3. dst is an interface type and src implements dst.
 	if dst.IsInterface() && src.Kind() != types.TNIL {
 		var missing, have *types.Field
 		var ptr int
+		if src.IsShape() {
+			// Shape types implement things they have already
+			// been typechecked to implement, even if they
+			// don't have the methods for them.
+			return ir.OCONVIFACE, ""
+		}
 		if implements(src, dst, &missing, &have, &ptr) {
-			// Call NeedITab/ITabAddr so that (src, dst)
-			// gets added to itabs early, which allows
-			// us to de-virtualize calls through this
-			// type/interface pair later. See CompileITabs in reflect.go
-			if types.IsDirectIface(src) && !dst.IsEmptyInterface() {
-				NeedITab(src, dst)
-			}
-
 			return ir.OCONVIFACE, ""
 		}
 
@@ -722,13 +727,23 @@
 	return m, followptr
 }
 
+// implements reports whether t implements the interface iface. t can be
+// an interface, a type parameter, or a concrete type. If implements returns
+// false, it stores a method of iface that is not implemented in *m. If the
+// method name matches but the type is wrong, it additionally stores the type
+// of the method (on t) in *samename.
 func implements(t, iface *types.Type, m, samename **types.Field, ptr *int) bool {
 	t0 := t
 	if t == nil {
 		return false
 	}
 
-	if t.IsInterface() {
+	if t.IsInterface() || t.IsTypeParam() {
+		if t.IsTypeParam() {
+			// A typeparam satisfies an interface if its type bound
+			// has all the methods of that interface.
+			t = t.Bound()
+		}
 		i := 0
 		tms := t.AllMethods().Slice()
 		for _, im := range iface.AllMethods().Slice() {
@@ -874,3 +889,515 @@
 type symlink struct {
 	field *types.Field
 }
+
+// TypesOf converts a list of nodes to a list
+// of types of those nodes.
+func TypesOf(x []ir.Node) []*types.Type {
+	r := make([]*types.Type, len(x))
+	for i, n := range x {
+		r[i] = n.Type()
+	}
+	return r
+}
+
+// makeGenericName returns the name of the generic function instantiated
+// with the given types.
+// name is the name of the generic function or method.
+func makeGenericName(name string, targs []*types.Type, hasBrackets bool) string {
+	b := bytes.NewBufferString("")
+
+	// Determine if the type args are concrete types or new typeparams.
+	hasTParam := false
+	for _, targ := range targs {
+		if hasTParam {
+			assert(targ.HasTParam() || targ.HasShape())
+		} else if targ.HasTParam() || targ.HasShape() {
+			hasTParam = true
+		}
+	}
+
+	// Marker to distinguish generic instantiations from fully stenciled wrapper functions.
+	// Once we move to GC shape implementations, this prefix will not be necessary as the
+	// GC shape naming will distinguish them.
+	// e.g. f[8bytenonpointer] vs. f[int].
+	// For now, we use .inst.f[int] vs. f[int].
+	if !hasTParam {
+		b.WriteString(".inst.")
+	}
+
+	i := strings.Index(name, "[")
+	assert(hasBrackets == (i >= 0))
+	if i >= 0 {
+		b.WriteString(name[0:i])
+	} else {
+		b.WriteString(name)
+	}
+	b.WriteString("[")
+	for i, targ := range targs {
+		if i > 0 {
+			b.WriteString(",")
+		}
+		// WriteString() does not include the package name for the local
+		// package, but we want it for uniqueness.
+		if targ.Sym() != nil && targ.Sym().Pkg == types.LocalPkg {
+			b.WriteString(targ.Sym().Pkg.Name)
+			b.WriteByte('.')
+		}
+		// types1 uses "interface {" and types2 uses "interface{" - convert
+		// to consistent types2 format.
+		tstring := targ.String()
+		tstring = strings.Replace(tstring, "interface {", "interface{", -1)
+		b.WriteString(tstring)
+	}
+	b.WriteString("]")
+	if i >= 0 {
+		i2 := strings.LastIndex(name[i:], "]")
+		assert(i2 >= 0)
+		b.WriteString(name[i+i2+1:])
+	}
+	if strings.HasPrefix(b.String(), ".inst..inst.") {
+		panic(fmt.Sprintf("multiple .inst. prefix in %s", b.String()))
+	}
+	return b.String()
+}
+
+// MakeInstName makes the unique name for a stenciled generic function or method,
+// based on the name of the function fnsym and the targs. It replaces any
+// existing bracket type list in the name. makeInstName asserts that fnsym has
+// brackets in its name if and only if hasBrackets is true.
+//
+// Names of declared generic functions have no brackets originally, so hasBrackets
+// should be false. Names of generic methods already have brackets, since the new
+// type parameter is specified in the generic type of the receiver (e.g. func
+// (func (v *value[T]).set(...) { ... } has the original name (*value[T]).set.
+//
+// The standard naming is something like: 'genFn[int,bool]' for functions and
+// '(*genType[int,bool]).methodName' for methods
+func MakeInstName(gf *types.Sym, targs []*types.Type, hasBrackets bool) *types.Sym {
+	return gf.Pkg.Lookup(makeGenericName(gf.Name, targs, hasBrackets))
+}
+
+func MakeDictName(gf *types.Sym, targs []*types.Type, hasBrackets bool) *types.Sym {
+	for _, targ := range targs {
+		if targ.HasTParam() {
+			fmt.Printf("FUNCTION %s\n", gf.Name)
+			for _, targ := range targs {
+				fmt.Printf("  PARAM %+v\n", targ)
+			}
+			panic("dictionary should always have concrete type args")
+		}
+	}
+	name := makeGenericName(gf.Name, targs, hasBrackets)
+	name = ".dict." + name[6:]
+	return gf.Pkg.Lookup(name)
+}
+
+func assert(p bool) {
+	base.Assert(p)
+}
+
+// General type substituter, for replacing typeparams with type args.
+type Tsubster struct {
+	Tparams []*types.Type
+	Targs   []*types.Type
+	// If non-nil, the substitution map from name nodes in the generic function to the
+	// name nodes in the new stenciled function.
+	Vars map[*ir.Name]*ir.Name
+	// New fully-instantiated generic types whose methods should be instantiated.
+	InstTypeList []*types.Type
+	// If non-nil, function to substitute an incomplete (TFORW) type.
+	SubstForwFunc func(*types.Type) *types.Type
+}
+
+// Typ computes the type obtained by substituting any type parameter in t with the
+// corresponding type argument in subst. If t contains no type parameters, the
+// result is t; otherwise the result is a new type. It deals with recursive types
+// by using TFORW types and finding partially or fully created types via sym.Def.
+func (ts *Tsubster) Typ(t *types.Type) *types.Type {
+	if !t.HasTParam() && !t.HasShape() && t.Kind() != types.TFUNC {
+		// Note: function types need to be copied regardless, as the
+		// types of closures may contain declarations that need
+		// to be copied. See #45738.
+		return t
+	}
+
+	if t.IsTypeParam() || t.IsShape() {
+		for i, tp := range ts.Tparams {
+			if tp == t {
+				return ts.Targs[i]
+			}
+		}
+		// If t is a simple typeparam T, then t has the name/symbol 'T'
+		// and t.Underlying() == t.
+		//
+		// However, consider the type definition: 'type P[T any] T'. We
+		// might use this definition so we can have a variant of type T
+		// that we can add new methods to. Suppose t is a reference to
+		// P[T]. t has the name 'P[T]', but its kind is TTYPEPARAM,
+		// because P[T] is defined as T. If we look at t.Underlying(), it
+		// is different, because the name of t.Underlying() is 'T' rather
+		// than 'P[T]'. But the kind of t.Underlying() is also TTYPEPARAM.
+		// In this case, we do the needed recursive substitution in the
+		// case statement below.
+		if t.Underlying() == t {
+			// t is a simple typeparam that didn't match anything in tparam
+			return t
+		}
+		// t is a more complex typeparam (e.g. P[T], as above, whose
+		// definition is just T).
+		assert(t.Sym() != nil)
+	}
+
+	var newsym *types.Sym
+	var neededTargs []*types.Type
+	var targsChanged bool
+	var forw *types.Type
+
+	if t.Sym() != nil {
+		// Translate the type params for this type according to
+		// the tparam/targs mapping from subst.
+		neededTargs = make([]*types.Type, len(t.RParams()))
+		for i, rparam := range t.RParams() {
+			neededTargs[i] = ts.Typ(rparam)
+			if !types.Identical(neededTargs[i], rparam) {
+				targsChanged = true
+			}
+		}
+		// For a named (defined) type, we have to change the name of the
+		// type as well. We do this first, so we can look up if we've
+		// already seen this type during this substitution or other
+		// definitions/substitutions.
+		genName := genericTypeName(t.Sym())
+		newsym = t.Sym().Pkg.Lookup(InstTypeName(genName, neededTargs))
+		if newsym.Def != nil {
+			// We've already created this instantiated defined type.
+			return newsym.Def.Type()
+		}
+
+		// In order to deal with recursive generic types, create a TFORW
+		// type initially and set the Def field of its sym, so it can be
+		// found if this type appears recursively within the type.
+		forw = NewIncompleteNamedType(t.Pos(), newsym)
+		//println("Creating new type by sub", newsym.Name, forw.HasTParam())
+		forw.SetRParams(neededTargs)
+		// Copy the OrigSym from the re-instantiated type (which is the sym of
+		// the base generic type).
+		assert(t.OrigSym != nil)
+		forw.OrigSym = t.OrigSym
+	}
+
+	var newt *types.Type
+
+	switch t.Kind() {
+	case types.TTYPEPARAM:
+		if t.Sym() == newsym && !targsChanged {
+			// The substitution did not change the type.
+			return t
+		}
+		// Substitute the underlying typeparam (e.g. T in P[T], see
+		// the example describing type P[T] above).
+		newt = ts.Typ(t.Underlying())
+		assert(newt != t)
+
+	case types.TARRAY:
+		elem := t.Elem()
+		newelem := ts.Typ(elem)
+		if newelem != elem || targsChanged {
+			newt = types.NewArray(newelem, t.NumElem())
+		}
+
+	case types.TPTR:
+		elem := t.Elem()
+		newelem := ts.Typ(elem)
+		if newelem != elem || targsChanged {
+			newt = types.NewPtr(newelem)
+		}
+
+	case types.TSLICE:
+		elem := t.Elem()
+		newelem := ts.Typ(elem)
+		if newelem != elem || targsChanged {
+			newt = types.NewSlice(newelem)
+		}
+
+	case types.TSTRUCT:
+		newt = ts.tstruct(t, targsChanged)
+		if newt == t {
+			newt = nil
+		}
+
+	case types.TFUNC:
+		newrecvs := ts.tstruct(t.Recvs(), false)
+		newparams := ts.tstruct(t.Params(), false)
+		newresults := ts.tstruct(t.Results(), false)
+		// Translate the tparams of a signature.
+		newtparams := ts.tstruct(t.TParams(), false)
+		if newrecvs != t.Recvs() || newparams != t.Params() ||
+			newresults != t.Results() || newtparams != t.TParams() || targsChanged {
+			// If any types have changed, then the all the fields of
+			// of recv, params, and results must be copied, because they have
+			// offset fields that are dependent, and so must have an
+			// independent copy for each new signature.
+			var newrecv *types.Field
+			if newrecvs.NumFields() > 0 {
+				if newrecvs == t.Recvs() {
+					newrecvs = ts.tstruct(t.Recvs(), true)
+				}
+				newrecv = newrecvs.Field(0)
+			}
+			if newparams == t.Params() {
+				newparams = ts.tstruct(t.Params(), true)
+			}
+			if newresults == t.Results() {
+				newresults = ts.tstruct(t.Results(), true)
+			}
+			var tparamfields []*types.Field
+			if newtparams.HasTParam() {
+				tparamfields = newtparams.FieldSlice()
+			} else {
+				// Completely remove the tparams from the resulting
+				// signature, if the tparams are now concrete types.
+				tparamfields = nil
+			}
+			newt = types.NewSignature(t.Pkg(), newrecv, tparamfields,
+				newparams.FieldSlice(), newresults.FieldSlice())
+		}
+
+	case types.TINTER:
+		newt = ts.tinter(t)
+		if newt == t && !targsChanged {
+			newt = nil
+		}
+
+	case types.TMAP:
+		newkey := ts.Typ(t.Key())
+		newval := ts.Typ(t.Elem())
+		if newkey != t.Key() || newval != t.Elem() || targsChanged {
+			newt = types.NewMap(newkey, newval)
+		}
+
+	case types.TCHAN:
+		elem := t.Elem()
+		newelem := ts.Typ(elem)
+		if newelem != elem || targsChanged {
+			newt = types.NewChan(newelem, t.ChanDir())
+			if !newt.HasTParam() {
+				// TODO(danscales): not sure why I have to do this
+				// only for channels.....
+				types.CheckSize(newt)
+			}
+		}
+	case types.TFORW:
+		if ts.SubstForwFunc != nil {
+			newt = ts.SubstForwFunc(t)
+		} else {
+			assert(false)
+		}
+	case types.TINT, types.TINT8, types.TINT16, types.TINT32, types.TINT64,
+		types.TUINT, types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64,
+		types.TUINTPTR, types.TBOOL, types.TSTRING, types.TFLOAT32, types.TFLOAT64, types.TCOMPLEX64, types.TCOMPLEX128:
+		newt = t.Underlying()
+	case types.TUNION:
+		nt := t.NumTerms()
+		newterms := make([]*types.Type, nt)
+		tildes := make([]bool, nt)
+		changed := false
+		for i := 0; i < nt; i++ {
+			term, tilde := t.Term(i)
+			tildes[i] = tilde
+			newterms[i] = ts.Typ(term)
+			if newterms[i] != term {
+				changed = true
+			}
+		}
+		if changed {
+			newt = types.NewUnion(newterms, tildes)
+		}
+	default:
+		panic(fmt.Sprintf("Bad type in (*TSubster).Typ: %v", t.Kind()))
+	}
+	if newt == nil {
+		// Even though there were typeparams in the type, there may be no
+		// change if this is a function type for a function call (which will
+		// have its own tparams/targs in the function instantiation).
+		return t
+	}
+
+	if t.Sym() == nil && t.Kind() != types.TINTER {
+		// Not a named type or interface type, so there was no forwarding type
+		// and there are no methods to substitute.
+		assert(t.Methods().Len() == 0)
+		return newt
+	}
+
+	if forw != nil {
+		forw.SetUnderlying(newt)
+		newt = forw
+	}
+
+	if t.Kind() != types.TINTER && t.Methods().Len() > 0 {
+		// Fill in the method info for the new type.
+		var newfields []*types.Field
+		newfields = make([]*types.Field, t.Methods().Len())
+		for i, f := range t.Methods().Slice() {
+			t2 := ts.Typ(f.Type)
+			oldsym := f.Nname.Sym()
+			newsym := MakeInstName(oldsym, ts.Targs, true)
+			var nname *ir.Name
+			if newsym.Def != nil {
+				nname = newsym.Def.(*ir.Name)
+			} else {
+				nname = ir.NewNameAt(f.Pos, newsym)
+				nname.SetType(t2)
+				newsym.Def = nname
+			}
+			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+			newfields[i].Nname = nname
+		}
+		newt.Methods().Set(newfields)
+		if !newt.HasTParam() && !newt.HasShape() {
+			// Generate all the methods for a new fully-instantiated type.
+			ts.InstTypeList = append(ts.InstTypeList, newt)
+		}
+	}
+	return newt
+}
+
+// tstruct substitutes type params in types of the fields of a structure type. For
+// each field, tstruct copies the Nname, and translates it if Nname is in
+// ts.vars. To always force the creation of a new (top-level) struct,
+// regardless of whether anything changed with the types or names of the struct's
+// fields, set force to true.
+func (ts *Tsubster) tstruct(t *types.Type, force bool) *types.Type {
+	if t.NumFields() == 0 {
+		if t.HasTParam() {
+			// For an empty struct, we need to return a new type,
+			// since it may now be fully instantiated (HasTParam
+			// becomes false).
+			return types.NewStruct(t.Pkg(), nil)
+		}
+		return t
+	}
+	var newfields []*types.Field
+	if force {
+		newfields = make([]*types.Field, t.NumFields())
+	}
+	for i, f := range t.Fields().Slice() {
+		t2 := ts.Typ(f.Type)
+		if (t2 != f.Type || f.Nname != nil) && newfields == nil {
+			newfields = make([]*types.Field, t.NumFields())
+			for j := 0; j < i; j++ {
+				newfields[j] = t.Field(j)
+			}
+		}
+		if newfields != nil {
+			// TODO(danscales): make sure this works for the field
+			// names of embedded types (which should keep the name of
+			// the type param, not the instantiated type).
+			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+			newfields[i].Embedded = f.Embedded
+			if f.IsDDD() {
+				newfields[i].SetIsDDD(true)
+			}
+			if f.Nointerface() {
+				newfields[i].SetNointerface(true)
+			}
+			if f.Nname != nil && ts.Vars != nil {
+				v := ts.Vars[f.Nname.(*ir.Name)]
+				if v != nil {
+					// This is the case where we are
+					// translating the type of the function we
+					// are substituting, so its dcls are in
+					// the subst.ts.vars table, and we want to
+					// change to reference the new dcl.
+					newfields[i].Nname = v
+				} else {
+					// This is the case where we are
+					// translating the type of a function
+					// reference inside the function we are
+					// substituting, so we leave the Nname
+					// value as is.
+					newfields[i].Nname = f.Nname
+				}
+			}
+		}
+	}
+	if newfields != nil {
+		return types.NewStruct(t.Pkg(), newfields)
+	}
+	return t
+
+}
+
+// tinter substitutes type params in types of the methods of an interface type.
+func (ts *Tsubster) tinter(t *types.Type) *types.Type {
+	if t.Methods().Len() == 0 {
+		return t
+	}
+	var newfields []*types.Field
+	for i, f := range t.Methods().Slice() {
+		t2 := ts.Typ(f.Type)
+		if (t2 != f.Type || f.Nname != nil) && newfields == nil {
+			newfields = make([]*types.Field, t.Methods().Len())
+			for j := 0; j < i; j++ {
+				newfields[j] = t.Methods().Index(j)
+			}
+		}
+		if newfields != nil {
+			newfields[i] = types.NewField(f.Pos, f.Sym, t2)
+		}
+	}
+	if newfields != nil {
+		return types.NewInterface(t.Pkg(), newfields)
+	}
+	return t
+}
+
+// genericSym returns the name of the base generic type for the type named by
+// sym. It simply returns the name obtained by removing everything after the
+// first bracket ("[").
+func genericTypeName(sym *types.Sym) string {
+	return sym.Name[0:strings.Index(sym.Name, "[")]
+}
+
+// Shapify takes a concrete type and returns a GCshape type that can
+// be used in place of the input type and still generate identical code.
+// No methods are added - all methods calls directly on a shape should
+// be done by converting to an interface using the dictionary.
+//
+// TODO: this could take the generic function and base its decisions
+// on how that generic function uses this type argument. For instance,
+// if it doesn't use it as a function argument/return value, then
+// we don't need to distinguish int64 and float64 (because they only
+// differ in how they get passed as arguments). For now, we only
+// unify two different types if they are identical in every possible way.
+func Shapify(t *types.Type) *types.Type {
+	assert(!t.HasShape())
+	// Map all types with the same underlying type to the same shape.
+	u := t.Underlying()
+
+	// All pointers have the same shape.
+	// TODO: Make unsafe.Pointer the same shape as normal pointers.
+	if u.Kind() == types.TPTR {
+		u = types.Types[types.TUINT8].PtrTo()
+	}
+
+	if s := shaped[u]; s != nil {
+		return s
+	}
+
+	sym := shapePkg.Lookup(u.LinkString())
+	name := ir.NewDeclNameAt(u.Pos(), ir.OTYPE, sym)
+	s := types.NewNamed(name)
+	s.SetUnderlying(u)
+	s.SetIsShape(true)
+	s.SetHasShape(true)
+	name.SetType(s)
+	name.SetTypecheck(1)
+	shaped[u] = s
+	return s
+}
+
+var shaped = map[*types.Type]*types.Type{}
+
+var shapePkg = types.NewPkg(".shape", ".shape")
diff --git a/src/cmd/compile/internal/typecheck/syms.go b/src/cmd/compile/internal/typecheck/syms.go
index f29af82..ed3aaec 100644
--- a/src/cmd/compile/internal/typecheck/syms.go
+++ b/src/cmd/compile/internal/typecheck/syms.go
@@ -75,9 +75,9 @@
 		typ := typs[d.typ]
 		switch d.tag {
 		case funcTag:
-			importfunc(ir.Pkgs.Runtime, src.NoXPos, sym, typ)
+			importfunc(src.NoXPos, sym, typ)
 		case varTag:
-			importvar(ir.Pkgs.Runtime, src.NoXPos, sym, typ)
+			importvar(src.NoXPos, sym, typ)
 		default:
 			base.Fatalf("unhandled declaration tag %v", d.tag)
 		}
diff --git a/src/cmd/compile/internal/typecheck/typecheck.go b/src/cmd/compile/internal/typecheck/typecheck.go
index 359f662..db1b11c 100644
--- a/src/cmd/compile/internal/typecheck/typecheck.go
+++ b/src/cmd/compile/internal/typecheck/typecheck.go
@@ -13,6 +13,7 @@
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/types"
+	"cmd/internal/src"
 )
 
 // Function collecting autotmps generated during typechecking,
@@ -24,7 +25,6 @@
 var TypecheckAllowed bool
 
 var (
-	NeedITab        = func(t, itype *types.Type) {}
 	NeedRuntimeType = func(*types.Type) {}
 )
 
@@ -35,18 +35,10 @@
 func Exprs(exprs []ir.Node) { typecheckslice(exprs, ctxExpr) }
 func Stmts(stmts []ir.Node) { typecheckslice(stmts, ctxStmt) }
 
-func Call(call *ir.CallExpr) {
-	t := call.X.Type()
-	if t == nil {
-		panic("misuse of Call")
-	}
-	ctx := ctxStmt
-	if t.NumResults() > 0 {
-		ctx = ctxExpr | ctxMultiOK
-	}
-	if typecheck(call, ctx) != call {
-		panic("bad typecheck")
-	}
+func Call(pos src.XPos, callee ir.Node, args []ir.Node, dots bool) ir.Node {
+	call := ir.NewCallExpr(pos, ir.OCALL, callee, args)
+	call.IsDDD = dots
+	return typecheck(call, ctxStmt|ctxExpr)
 }
 
 func Callee(n ir.Node) ir.Node {
@@ -59,8 +51,8 @@
 	Stmts(n.Body)
 	CheckUnused(n)
 	CheckReturn(n)
-	if base.Errors() > errorsBefore {
-		n.Body = nil // type errors; do not compile
+	if ir.IsBlank(n.Nname) || base.Errors() > errorsBefore {
+		n.Body = nil // blank function or type errors; do not compile
 	}
 }
 
@@ -777,6 +769,10 @@
 		n := n.(*ir.CallExpr)
 		return tcRecover(n)
 
+	case ir.ORECOVERFP:
+		n := n.(*ir.CallExpr)
+		return tcRecoverFP(n)
+
 	case ir.OUNSAFEADD:
 		n := n.(*ir.BinaryExpr)
 		return tcUnsafeAdd(n)
@@ -787,11 +783,7 @@
 
 	case ir.OCLOSURE:
 		n := n.(*ir.ClosureExpr)
-		tcClosure(n, top)
-		if n.Type() == nil {
-			return n
-		}
-		return n
+		return tcClosure(n, top)
 
 	case ir.OITAB:
 		n := n.(*ir.UnaryExpr)
@@ -814,6 +806,14 @@
 		n.SetType(types.Types[types.TUINTPTR])
 		return n
 
+	case ir.OGETCALLERPC, ir.OGETCALLERSP:
+		n := n.(*ir.CallExpr)
+		if len(n.Args) != 0 {
+			base.FatalfAt(n.Pos(), "unexpected arguments: %v", n)
+		}
+		n.SetType(types.Types[types.TUINTPTR])
+		return n
+
 	case ir.OCONVNOP:
 		n := n.(*ir.ConvExpr)
 		n.X = Expr(n.X)
@@ -881,6 +881,10 @@
 		n := n.(*ir.TailCallStmt)
 		return n
 
+	case ir.OCHECKNIL:
+		n := n.(*ir.UnaryExpr)
+		return tcCheckNil(n)
+
 	case ir.OSELECT:
 		tcSelect(n.(*ir.SelectStmt))
 		return n
@@ -951,12 +955,12 @@
 	}
 
 	// Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
-	rewriteMultiValueCall(n, list[0])
+	RewriteMultiValueCall(n, list[0])
 }
 
-// rewriteMultiValueCall rewrites multi-valued f() to use temporaries,
+// RewriteMultiValueCall rewrites multi-valued f() to use temporaries,
 // so the backend wouldn't need to worry about tuple-valued expressions.
-func rewriteMultiValueCall(n ir.InitNode, call ir.Node) {
+func RewriteMultiValueCall(n ir.InitNode, call ir.Node) {
 	// If we're outside of function context, then this call will
 	// be executed during the generated init function. However,
 	// init.go hasn't yet created it. Instead, associate the
@@ -1913,11 +1917,6 @@
 					n.SetDiag(true)
 					goto ret
 				}
-				// For package-level type aliases, set n.Sym.Def so we can identify
-				// it as a type alias during export. See also #31959.
-				if n.Curfn == nil {
-					n.Sym().Def = n.Ntype
-				}
 			}
 			break
 		}
diff --git a/src/cmd/compile/internal/typecheck/universe.go b/src/cmd/compile/internal/typecheck/universe.go
index de185ab..54f3c89 100644
--- a/src/cmd/compile/internal/typecheck/universe.go
+++ b/src/cmd/compile/internal/typecheck/universe.go
@@ -158,6 +158,15 @@
 	s.Def = n
 	types.CalcSize(types.ErrorType)
 
+	// comparable type (interface)
+	s = types.BuiltinPkg.Lookup("comparable")
+	n = ir.NewDeclNameAt(src.NoXPos, ir.OTYPE, s)
+	types.ComparableType = types.NewNamed(n)
+	types.ComparableType.SetUnderlying(makeComparableInterface())
+	n.SetType(types.ComparableType)
+	s.Def = n
+	types.CalcSize(types.ComparableType)
+
 	types.Types[types.TUNSAFEPTR] = defBasic(types.TUNSAFEPTR, ir.Pkgs.Unsafe, "Pointer")
 
 	// simple aliases
@@ -338,6 +347,12 @@
 	return types.NewInterface(types.NoPkg, []*types.Field{method})
 }
 
+func makeComparableInterface() *types.Type {
+	sig := types.NewSignature(types.NoPkg, fakeRecvField(), nil, nil, nil)
+	method := types.NewField(src.NoXPos, Lookup("=="), sig)
+	return types.NewInterface(types.NoPkg, []*types.Field{method})
+}
+
 // DeclareUniverse makes the universe block visible within the current package.
 func DeclareUniverse() {
 	// Operationally, this is similar to a dot import of builtinpkg, except
diff --git a/src/cmd/compile/internal/types/fmt.go b/src/cmd/compile/internal/types/fmt.go
index 8b98895..0824f6d 100644
--- a/src/cmd/compile/internal/types/fmt.go
+++ b/src/cmd/compile/internal/types/fmt.go
@@ -239,17 +239,37 @@
 	return tconv(t, 0, fmtGo)
 }
 
-// ShortString generates a short description of t.
-// It is used in autogenerated method names, reflection,
-// and itab names.
-func (t *Type) ShortString() string {
+// LinkString returns an unexpanded string description of t, suitable
+// for use in link symbols. "Unexpanded" here means that the
+// description uses `"".` to qualify identifiers from the current
+// package, and "expansion" refers to the renaming step performed by
+// the linker to replace these qualifiers with proper `path/to/pkg.`
+// qualifiers.
+//
+// After expansion, the description corresponds to type identity. That
+// is, for any pair of types t1 and t2, Identical(t1, t2) and
+// expand(t1.LinkString()) == expand(t2.LinkString()) report the same
+// value.
+//
+// Within a single compilation unit, LinkString always returns the
+// same unexpanded description for identical types. Thus it's safe to
+// use as a map key to implement a type-identity-keyed map. However,
+// make sure all LinkString calls used for this purpose happen within
+// the same compile process; the string keys are not stable across
+// multiple processes.
+func (t *Type) LinkString() string {
 	return tconv(t, 0, fmtTypeID)
 }
 
-// LongString generates a complete description of t.
-// It is useful for reflection,
-// or when a unique fingerprint or hash of a type is required.
-func (t *Type) LongString() string {
+// NameString generates a user-readable, mostly unique string
+// description of t. NameString always returns the same description
+// for identical types, even across compilation units.
+//
+// NameString qualifies identifiers by package name, so it has
+// collisions when different packages share the same names and
+// identifiers. It also does not distinguish function-scope defined
+// types from package-scoped defined types or from each other.
+func (t *Type) NameString() string {
 	return tconv(t, 0, fmtTypeIDName)
 }
 
@@ -316,31 +336,34 @@
 
 	// Unless the 'L' flag was specified, if the type has a name, just print that name.
 	if verb != 'L' && t.Sym() != nil && t != Types[t.Kind()] {
-		switch mode {
-		case fmtTypeID, fmtTypeIDName:
-			if verb == 'S' {
-				if t.Vargen != 0 {
-					sconv2(b, t.Sym(), 'S', mode)
-					fmt.Fprintf(b, "·%d", t.Vargen)
-					return
-				}
-				sconv2(b, t.Sym(), 'S', mode)
-				return
-			}
-
-			if mode == fmtTypeIDName {
-				sconv2(b, t.Sym(), 'v', fmtTypeIDName)
-				return
-			}
-
-			if t.Sym().Pkg == LocalPkg && t.Vargen != 0 {
-				sconv2(b, t.Sym(), 'v', mode)
-				fmt.Fprintf(b, "·%d", t.Vargen)
-				return
-			}
+		// Default to 'v' if verb is invalid.
+		if verb != 'S' {
+			verb = 'v'
 		}
 
-		sconv2(b, t.Sym(), 'v', mode)
+		// In unified IR, function-scope defined types will have a ·N
+		// suffix embedded directly in their Name. Trim this off for
+		// non-fmtTypeID modes.
+		sym := t.Sym()
+		if mode != fmtTypeID {
+			i := len(sym.Name)
+			for i > 0 && sym.Name[i-1] >= '0' && sym.Name[i-1] <= '9' {
+				i--
+			}
+			const dot = "·"
+			if i >= len(dot) && sym.Name[i-len(dot):i] == dot {
+				sym = &Sym{Pkg: sym.Pkg, Name: sym.Name[:i-len(dot)]}
+			}
+		}
+		sconv2(b, sym, verb, mode)
+
+		// TODO(mdempsky): Investigate including Vargen in fmtTypeIDName
+		// output too. It seems like it should, but that mode is currently
+		// used in string representation used by reflection, which is
+		// user-visible and doesn't expect this.
+		if mode == fmtTypeID && t.Vargen != 0 {
+			fmt.Fprintf(b, "·%d", t.Vargen)
+		}
 		return
 	}
 
@@ -567,6 +590,18 @@
 			b.WriteString(fmt.Sprintf("%p", t))
 		}
 
+	case TUNION:
+		for i := 0; i < t.NumTerms(); i++ {
+			if i > 0 {
+				b.WriteString("|")
+			}
+			elem, tilde := t.Term(i)
+			if tilde {
+				b.WriteString("~")
+			}
+			tconv2(b, elem, 0, mode, visited)
+		}
+
 	case Txxx:
 		b.WriteString("Txxx")
 
@@ -671,7 +706,7 @@
 
 // TypeHash computes a hash value for type t to use in type switch statements.
 func TypeHash(t *Type) uint32 {
-	p := t.LongString()
+	p := t.NameString()
 
 	// Using MD5 is overkill, but reduces accidental collisions.
 	h := md5.Sum([]byte(p))
diff --git a/src/cmd/compile/internal/types/identity.go b/src/cmd/compile/internal/types/identity.go
index dde9f51..dc39acc 100644
--- a/src/cmd/compile/internal/types/identity.go
+++ b/src/cmd/compile/internal/types/identity.go
@@ -29,6 +29,14 @@
 		return false
 	}
 	if t1.sym != nil || t2.sym != nil {
+		if t1.HasShape() || t2.HasShape() {
+			switch t1.kind {
+			case TINT8, TUINT8, TINT16, TUINT16, TINT32, TUINT32, TINT64, TUINT64, TINT, TUINT, TUINTPTR, TCOMPLEX64, TCOMPLEX128, TFLOAT32, TFLOAT64, TBOOL, TSTRING, TPTR, TUNSAFEPTR:
+				return true
+			}
+			// fall through to unnamed type comparison for complex types.
+			goto cont
+		}
 		// Special case: we keep byte/uint8 and rune/int32
 		// separate for error messages. Treat them as equal.
 		switch t1.kind {
@@ -40,6 +48,7 @@
 			return false
 		}
 	}
+cont:
 
 	// Any cyclic type must go through a named type, and if one is
 	// named, it is only identical to the other if they are the
diff --git a/src/cmd/compile/internal/types/kind_string.go b/src/cmd/compile/internal/types/kind_string.go
index ae24a58..3e6a8bc 100644
--- a/src/cmd/compile/internal/types/kind_string.go
+++ b/src/cmd/compile/internal/types/kind_string.go
@@ -38,20 +38,21 @@
 	_ = x[TSTRING-27]
 	_ = x[TUNSAFEPTR-28]
 	_ = x[TTYPEPARAM-29]
-	_ = x[TIDEAL-30]
-	_ = x[TNIL-31]
-	_ = x[TBLANK-32]
-	_ = x[TFUNCARGS-33]
-	_ = x[TCHANARGS-34]
-	_ = x[TSSA-35]
-	_ = x[TTUPLE-36]
-	_ = x[TRESULTS-37]
-	_ = x[NTYPE-38]
+	_ = x[TUNION-30]
+	_ = x[TIDEAL-31]
+	_ = x[TNIL-32]
+	_ = x[TBLANK-33]
+	_ = x[TFUNCARGS-34]
+	_ = x[TCHANARGS-35]
+	_ = x[TSSA-36]
+	_ = x[TTUPLE-37]
+	_ = x[TRESULTS-38]
+	_ = x[NTYPE-39]
 }
 
-const _Kind_name = "xxxINT8UINT8INT16UINT16INT32UINT32INT64UINT64INTUINTUINTPTRCOMPLEX64COMPLEX128FLOAT32FLOAT64BOOLPTRFUNCSLICEARRAYSTRUCTCHANMAPINTERFORWANYSTRINGUNSAFEPTRTYPEPARAMIDEALNILBLANKFUNCARGSCHANARGSSSATUPLERESULTSNTYPE"
+const _Kind_name = "xxxINT8UINT8INT16UINT16INT32UINT32INT64UINT64INTUINTUINTPTRCOMPLEX64COMPLEX128FLOAT32FLOAT64BOOLPTRFUNCSLICEARRAYSTRUCTCHANMAPINTERFORWANYSTRINGUNSAFEPTRTYPEPARAMUNIONIDEALNILBLANKFUNCARGSCHANARGSSSATUPLERESULTSNTYPE"
 
-var _Kind_index = [...]uint8{0, 3, 7, 12, 17, 23, 28, 34, 39, 45, 48, 52, 59, 68, 78, 85, 92, 96, 99, 103, 108, 113, 119, 123, 126, 131, 135, 138, 144, 153, 162, 167, 170, 175, 183, 191, 194, 199, 206, 211}
+var _Kind_index = [...]uint8{0, 3, 7, 12, 17, 23, 28, 34, 39, 45, 48, 52, 59, 68, 78, 85, 92, 96, 99, 103, 108, 113, 119, 123, 126, 131, 135, 138, 144, 153, 162, 167, 172, 175, 180, 188, 196, 199, 204, 211, 216}
 
 func (i Kind) String() string {
 	if i >= Kind(len(_Kind_index)-1) {
diff --git a/src/cmd/compile/internal/types/pkg.go b/src/cmd/compile/internal/types/pkg.go
index a6d2e20..f63a357 100644
--- a/src/cmd/compile/internal/types/pkg.go
+++ b/src/cmd/compile/internal/types/pkg.go
@@ -137,7 +137,3 @@
 	f()
 	pkgMap = saved
 }
-
-func IsDotAlias(sym *Sym) bool {
-	return sym.Def != nil && sym.Def.Sym() != sym
-}
diff --git a/src/cmd/compile/internal/types/size.go b/src/cmd/compile/internal/types/size.go
index f0e695a..89391ad 100644
--- a/src/cmd/compile/internal/types/size.go
+++ b/src/cmd/compile/internal/types/size.go
@@ -90,6 +90,26 @@
 		methods = append(methods, m)
 	}
 
+	{
+		methods := t.Methods().Slice()
+		sort.SliceStable(methods, func(i, j int) bool {
+			mi, mj := methods[i], methods[j]
+
+			// Sort embedded types by type name (if any).
+			if mi.Sym == nil && mj.Sym == nil {
+				return mi.Type.Sym().Less(mj.Type.Sym())
+			}
+
+			// Sort methods before embedded types.
+			if mi.Sym == nil || mj.Sym == nil {
+				return mi.Sym != nil
+			}
+
+			// Sort methods by symbol name.
+			return mi.Sym.Less(mj.Sym)
+		})
+	}
+
 	for _, m := range t.Methods().Slice() {
 		if m.Sym == nil {
 			continue
@@ -104,8 +124,17 @@
 			continue
 		}
 
+		if m.Type.IsUnion() {
+			continue
+		}
+
+		// In 1.18, embedded types can be anything. In Go 1.17, we disallow
+		// embedding anything other than interfaces.
 		if !m.Type.IsInterface() {
-			base.ErrorfAt(m.Pos, "interface contains embedded non-interface %v", m.Type)
+			if AllowsGoVersion(t.Pkg(), 1, 18) {
+				continue
+			}
+			base.ErrorfAt(m.Pos, "interface contains embedded non-interface, non-union %v", m.Type)
 			m.SetBroke(true)
 			t.SetBroke(true)
 			// Add to fields so that error messages
@@ -120,10 +149,15 @@
 		// (including broken ones, if any) and add to t's
 		// method set.
 		for _, t1 := range m.Type.AllMethods().Slice() {
-			// Use m.Pos rather than t1.Pos to preserve embedding position.
 			f := NewField(m.Pos, t1.Sym, t1.Type)
 			addMethod(f, false)
+
+			// Clear position after typechecking, for consistency with types2.
+			f.Pos = src.NoXPos
 		}
+
+		// Clear position after typechecking, for consistency with types2.
+		m.Pos = src.NoXPos
 	}
 
 	sort.Sort(MethodsByName(methods))
@@ -405,6 +439,12 @@
 		t.Align = uint8(PtrSize)
 		expandiface(t)
 
+	case TUNION:
+		// Always part of an interface for now, so size/align don't matter.
+		// Pretend a union is represented like an interface.
+		w = 2 * int64(PtrSize)
+		t.Align = uint8(PtrSize)
+
 	case TCHAN: // implemented as pointer
 		w = int64(PtrSize)
 
diff --git a/src/cmd/compile/internal/types/sizeof_test.go b/src/cmd/compile/internal/types/sizeof_test.go
index 7028938..7349e52 100644
--- a/src/cmd/compile/internal/types/sizeof_test.go
+++ b/src/cmd/compile/internal/types/sizeof_test.go
@@ -21,7 +21,7 @@
 		_64bit uintptr     // size on 64bit platforms
 	}{
 		{Sym{}, 44, 72},
-		{Type{}, 60, 104},
+		{Type{}, 64, 112},
 		{Map{}, 20, 40},
 		{Forward{}, 20, 32},
 		{Func{}, 28, 48},
diff --git a/src/cmd/compile/internal/types/sort.go b/src/cmd/compile/internal/types/sort.go
index dc59b06..765c070 100644
--- a/src/cmd/compile/internal/types/sort.go
+++ b/src/cmd/compile/internal/types/sort.go
@@ -4,11 +4,16 @@
 
 package types
 
-// MethodsByName sorts methods by symbol.
+// MethodsByName sorts methods by name.
 type MethodsByName []*Field
 
-func (x MethodsByName) Len() int { return len(x) }
-
-func (x MethodsByName) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
-
+func (x MethodsByName) Len() int           { return len(x) }
+func (x MethodsByName) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
 func (x MethodsByName) Less(i, j int) bool { return x[i].Sym.Less(x[j].Sym) }
+
+// EmbeddedsByName sorts embedded types by name.
+type EmbeddedsByName []*Field
+
+func (x EmbeddedsByName) Len() int           { return len(x) }
+func (x EmbeddedsByName) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
+func (x EmbeddedsByName) Less(i, j int) bool { return x[i].Type.Sym().Less(x[j].Type.Sym()) }
diff --git a/src/cmd/compile/internal/types/sym.go b/src/cmd/compile/internal/types/sym.go
index 534cf7e..fb642f5 100644
--- a/src/cmd/compile/internal/types/sym.go
+++ b/src/cmd/compile/internal/types/sym.go
@@ -110,6 +110,14 @@
 		return false
 	}
 
+	// Nil before non-nil.
+	if a == nil {
+		return true
+	}
+	if b == nil {
+		return false
+	}
+
 	// Exported symbols before non-exported.
 	ea := IsExported(a.Name)
 	eb := IsExported(b.Name)
diff --git a/src/cmd/compile/internal/types/type.go b/src/cmd/compile/internal/types/type.go
index 1a9aa69..875b0ba 100644
--- a/src/cmd/compile/internal/types/type.go
+++ b/src/cmd/compile/internal/types/type.go
@@ -8,6 +8,7 @@
 	"cmd/compile/internal/base"
 	"cmd/internal/src"
 	"fmt"
+	"strings"
 	"sync"
 )
 
@@ -73,6 +74,7 @@
 	TSTRING
 	TUNSAFEPTR
 	TTYPEPARAM
+	TUNION
 
 	// pseudo-types for literals
 	TIDEAL // untyped numeric constants
@@ -121,6 +123,8 @@
 
 	// Predeclared error interface type.
 	ErrorType *Type
+	// Predeclared comparable interface type.
+	ComparableType *Type
 
 	// Types to represent untyped string and boolean constants.
 	UntypedString = New(TSTRING)
@@ -151,7 +155,7 @@
 	// TARRAY: *Array
 	// TSLICE: Slice
 	// TSSA: string
-	// TTYPEPARAM:  *Interface (though we may not need to store/use the Interface info)
+	// TTYPEPARAM:  *Typeparam
 	Extra interface{}
 
 	// Width is the width of this Type in bytes.
@@ -182,12 +186,19 @@
 	flags bitset8
 
 	// For defined (named) generic types, a pointer to the list of type params
-	// (in order) of this type that need to be instantiated. For
-	// fully-instantiated generic types, this is the targs used to instantiate
-	// them (which are used when generating the corresponding instantiated
-	// methods). rparams is only set for named types that are generic or are
-	// fully-instantiated from a generic type, and is otherwise set to nil.
+	// (in order) of this type that need to be instantiated. For instantiated
+	// generic types, this is the targs used to instantiate them. These targs
+	// may be typeparams (for re-instantiated types such as Value[T2]) or
+	// concrete types (for fully instantiated types such as Value[int]).
+	// rparams is only set for named types that are generic or are fully
+	// instantiated from a generic type, and is otherwise set to nil.
+	// TODO(danscales): choose a better name.
 	rparams *[]*Type
+
+	// For an instantiated generic type, the symbol for the base generic type.
+	// This backpointer is useful, because the base type is the type that has
+	// the method bodies.
+	OrigSym *Sym
 }
 
 func (*Type) CanBeAnSSAAux() {}
@@ -199,6 +210,8 @@
 	typeDeferwidth             // width computation has been deferred and type is on deferredTypeStack
 	typeRecur
 	typeHasTParam // there is a typeparam somewhere in the type (generic function or type)
+	typeIsShape   // represents a set of closely related types, for generics
+	typeHasShape  // there is a shape somewhere in the type
 )
 
 func (t *Type) NotInHeap() bool  { return t.flags&typeNotInHeap != 0 }
@@ -207,13 +220,21 @@
 func (t *Type) Deferwidth() bool { return t.flags&typeDeferwidth != 0 }
 func (t *Type) Recur() bool      { return t.flags&typeRecur != 0 }
 func (t *Type) HasTParam() bool  { return t.flags&typeHasTParam != 0 }
+func (t *Type) IsShape() bool    { return t.flags&typeIsShape != 0 }
+func (t *Type) HasShape() bool   { return t.flags&typeHasShape != 0 }
 
 func (t *Type) SetNotInHeap(b bool)  { t.flags.set(typeNotInHeap, b) }
 func (t *Type) SetBroke(b bool)      { t.flags.set(typeBroke, b) }
 func (t *Type) SetNoalg(b bool)      { t.flags.set(typeNoalg, b) }
 func (t *Type) SetDeferwidth(b bool) { t.flags.set(typeDeferwidth, b) }
 func (t *Type) SetRecur(b bool)      { t.flags.set(typeRecur, b) }
-func (t *Type) SetHasTParam(b bool)  { t.flags.set(typeHasTParam, b) }
+
+// Generic types should never have alg functions.
+func (t *Type) SetHasTParam(b bool) { t.flags.set(typeHasTParam, b); t.flags.set(typeNoalg, b) }
+
+// Should always do SetHasShape(true) when doing SeIsShape(true).
+func (t *Type) SetIsShape(b bool)  { t.flags.set(typeIsShape, b) }
+func (t *Type) SetHasShape(b bool) { t.flags.set(typeHasShape, b) }
 
 // Kind returns the kind of type t.
 func (t *Type) Kind() Kind { return t.kind }
@@ -255,9 +276,6 @@
 		base.Fatalf("Setting nil or zero-length rparams")
 	}
 	t.rparams = &rparams
-	if t.HasTParam() {
-		return
-	}
 	// HasTParam should be set if any rparam is or has a type param. This is
 	// to handle the case of a generic type which doesn't reference any of its
 	// type params (e.g. most commonly, an empty struct).
@@ -266,9 +284,33 @@
 			t.SetHasTParam(true)
 			break
 		}
+		if rparam.HasShape() {
+			t.SetHasShape(true)
+			break
+		}
 	}
 }
 
+// IsBaseGeneric returns true if t is a generic type (not reinstantiated with
+// another type params or fully instantiated.
+func (t *Type) IsBaseGeneric() bool {
+	return len(t.RParams()) > 0 && strings.Index(t.Sym().Name, "[") < 0
+}
+
+// IsInstantiatedGeneric returns t if t ia generic type that has been
+// reinstantiated with new typeparams (i.e. is not fully instantiated).
+func (t *Type) IsInstantiatedGeneric() bool {
+	return len(t.RParams()) > 0 && strings.Index(t.Sym().Name, "[") >= 0 &&
+		t.HasTParam()
+}
+
+// IsFullyInstantiated reports whether t is a fully instantiated generic type; i.e. an
+// instantiated generic type where all type arguments are non-generic or fully
+// instantiated generic types.
+func (t *Type) IsFullyInstantiated() bool {
+	return len(t.RParams()) > 0 && !t.HasTParam()
+}
+
 // NoPkg is a nil *Pkg value for clarity.
 // It's intended for use when constructing types that aren't exported
 // and thus don't need to be associated with any package.
@@ -377,6 +419,18 @@
 	pkg *Pkg
 }
 
+// Typeparam contains Type fields specific to typeparam types.
+type Typeparam struct {
+	index int // type parameter index in source order, starting at 0
+	bound *Type
+}
+
+// Union contains Type fields specific to union types.
+type Union struct {
+	terms  []*Type
+	tildes []bool // whether terms[i] is of form ~T
+}
+
 // Ptr contains Type fields specific to pointer types.
 type Ptr struct {
 	Elem *Type // element type
@@ -558,7 +612,9 @@
 	case TRESULTS:
 		t.Extra = new(Results)
 	case TTYPEPARAM:
-		t.Extra = new(Interface)
+		t.Extra = new(Typeparam)
+	case TUNION:
+		t.Extra = new(Union)
 	}
 	return t
 }
@@ -574,6 +630,9 @@
 	if elem.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if elem.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -592,6 +651,9 @@
 	if elem.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if elem.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -604,6 +666,9 @@
 	if elem.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if elem.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -614,6 +679,9 @@
 	if t1.HasTParam() || t2.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if t1.HasShape() || t2.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -645,6 +713,9 @@
 	if k.HasTParam() || v.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if k.HasShape() || v.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -669,6 +740,9 @@
 			// when this entry was cached.
 			t.SetHasTParam(true)
 		}
+		if elem.HasShape() {
+			t.SetHasShape(true)
+		}
 		return t
 	}
 
@@ -682,6 +756,9 @@
 	if elem.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if elem.HasShape() {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -825,6 +902,8 @@
 	case TARRAY:
 		x := *t.Extra.(*Array)
 		nt.Extra = &x
+	case TTYPEPARAM:
+		base.Fatalf("typeparam types cannot be copied")
 	case TTUPLE, TSSA, TRESULTS:
 		base.Fatalf("ssa types cannot be copied")
 	}
@@ -925,7 +1004,7 @@
 	return t.Extra.(FuncArgs).T
 }
 
-// IsFuncArgStruct reports whether t is a struct representing function parameters.
+// IsFuncArgStruct reports whether t is a struct representing function parameters or results.
 func (t *Type) IsFuncArgStruct() bool {
 	return t.kind == TSTRUCT && t.Extra.(*Struct).Funarg != FunargNone
 }
@@ -1436,6 +1515,14 @@
 	return t.kind == TINTER
 }
 
+func (t *Type) IsUnion() bool {
+	return t.kind == TUNION
+}
+
+func (t *Type) IsTypeParam() bool {
+	return t.kind == TTYPEPARAM
+}
+
 // IsEmptyInterface reports whether t is an empty interface type.
 func (t *Type) IsEmptyInterface() bool {
 	return t.IsInterface() && t.AllMethods().Len() == 0
@@ -1708,6 +1795,9 @@
 	if underlying.HasTParam() {
 		t.SetHasTParam(true)
 	}
+	if underlying.HasShape() {
+		t.SetHasShape(true)
+	}
 
 	// spec: "The declared type does not inherit any methods bound
 	// to the existing type, but the method set of an interface
@@ -1739,6 +1829,15 @@
 	return false
 }
 
+func fieldsHasShape(fields []*Field) bool {
+	for _, f := range fields {
+		if f.Type != nil && f.Type.HasShape() {
+			return true
+		}
+	}
+	return false
+}
+
 // NewBasic returns a new basic type of the given kind.
 func NewBasic(kind Kind, obj Object) *Type {
 	t := New(kind)
@@ -1758,6 +1857,10 @@
 			t.SetHasTParam(true)
 			break
 		}
+		if f.Type != nil && f.Type.HasShape() {
+			t.SetHasShape(true)
+			break
+		}
 	}
 	if anyBroke(methods) {
 		t.SetBroke(true)
@@ -1766,14 +1869,75 @@
 	return t
 }
 
-// NewTypeParam returns a new type param.
-func NewTypeParam(pkg *Pkg) *Type {
+// NewTypeParam returns a new type param with the specified sym (package and name)
+// and specified index within the typeparam list.
+func NewTypeParam(sym *Sym, index int) *Type {
 	t := New(TTYPEPARAM)
-	t.Extra.(*Interface).pkg = pkg
+	t.sym = sym
+	t.Extra.(*Typeparam).index = index
 	t.SetHasTParam(true)
 	return t
 }
 
+// Index returns the index of the type param within its param list.
+func (t *Type) Index() int {
+	t.wantEtype(TTYPEPARAM)
+	return t.Extra.(*Typeparam).index
+}
+
+// SetIndex sets the index of the type param within its param list.
+func (t *Type) SetIndex(i int) {
+	t.wantEtype(TTYPEPARAM)
+	t.Extra.(*Typeparam).index = i
+}
+
+// SetBound sets the bound of a typeparam.
+func (t *Type) SetBound(bound *Type) {
+	t.wantEtype(TTYPEPARAM)
+	t.Extra.(*Typeparam).bound = bound
+}
+
+// Bound returns the bound of a typeparam.
+func (t *Type) Bound() *Type {
+	t.wantEtype(TTYPEPARAM)
+	return t.Extra.(*Typeparam).bound
+}
+
+// NewUnion returns a new union with the specified set of terms (types). If
+// tildes[i] is true, then terms[i] represents ~T, rather than just T.
+func NewUnion(terms []*Type, tildes []bool) *Type {
+	t := New(TUNION)
+	if len(terms) != len(tildes) {
+		base.Fatalf("Mismatched terms and tildes for NewUnion")
+	}
+	t.Extra.(*Union).terms = terms
+	t.Extra.(*Union).tildes = tildes
+	nt := len(terms)
+	for i := 0; i < nt; i++ {
+		if terms[i].HasTParam() {
+			t.SetHasTParam(true)
+		}
+		if terms[i].HasShape() {
+			t.SetHasShape(true)
+		}
+	}
+	return t
+}
+
+// NumTerms returns the number of terms in a union type.
+func (t *Type) NumTerms() int {
+	t.wantEtype(TUNION)
+	return len(t.Extra.(*Union).terms)
+}
+
+// Term returns ith term of a union type as (term, tilde). If tilde is true, term
+// represents ~T, rather than just T.
+func (t *Type) Term(i int) (*Type, bool) {
+	t.wantEtype(TUNION)
+	u := t.Extra.(*Union)
+	return u.terms[i], u.tildes[i]
+}
+
 const BOGUS_FUNARG_OFFSET = -1000000000
 
 func unzeroFieldOffsets(f []*Field) {
@@ -1817,6 +1981,9 @@
 		fieldsHasTParam(results) {
 		t.SetHasTParam(true)
 	}
+	if fieldsHasShape(recvs) || fieldsHasShape(params) || fieldsHasShape(results) {
+		t.SetHasShape(true)
+	}
 
 	return t
 }
@@ -1832,6 +1999,9 @@
 	if fieldsHasTParam(fields) {
 		t.SetHasTParam(true)
 	}
+	if fieldsHasShape(fields) {
+		t.SetHasShape(true)
+	}
 	return t
 }
 
@@ -2028,7 +2198,7 @@
 }
 
 func TypeSymName(t *Type) string {
-	name := t.ShortString()
+	name := t.LinkString()
 	// Use a separate symbol name for Noalg types for #17752.
 	if TypeHasNoAlg(t) {
 		name = "noalg." + name
diff --git a/src/cmd/compile/internal/types2/api.go b/src/cmd/compile/internal/types2/api.go
index 2939dcc..ae4fb6a 100644
--- a/src/cmd/compile/internal/types2/api.go
+++ b/src/cmd/compile/internal/types2/api.go
@@ -125,6 +125,12 @@
 	// TODO(gri) Consolidate error messages and remove this flag.
 	CompilerErrorMessages bool
 
+	// If AllowTypeLists is set, the type list syntax is permitted
+	// in an interface in addition to the type set syntax.
+	// TODO(gri) Remove once type lists are no longer supported by
+	//           the parser.
+	AllowTypeLists bool
+
 	// If go115UsesCgo is set, the type checker expects the
 	// _cgo_gotypes.go file generated by running cmd/cgo to be
 	// provided as a package source file. Qualified identifiers
@@ -355,7 +361,7 @@
 // Inferred reports the inferred type arguments and signature
 // for a parameterized function call that uses type inference.
 type Inferred struct {
-	Targs []Type
+	TArgs []Type
 	Sig   *Signature
 }
 
@@ -424,11 +430,11 @@
 // Identical reports whether x and y are identical types.
 // Receivers of Signature types are ignored.
 func Identical(x, y Type) bool {
-	return (*Checker)(nil).identical(x, y)
+	return identical(x, y, true, nil)
 }
 
 // IdenticalIgnoreTags reports whether x and y are identical types if tags are ignored.
 // Receivers of Signature types are ignored.
 func IdenticalIgnoreTags(x, y Type) bool {
-	return (*Checker)(nil).identicalIgnoreTags(x, y)
+	return identical(x, y, false, nil)
 }
diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index 873390c..d884495 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -329,27 +329,26 @@
 		{brokenPkg + `x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string]invalid type`},
 
 		// parameterized functions
-		{genericPkg + `p0; func f[T any](T); var _ = f[int]`, `f`, `func[T₁ interface{}](T₁)`},
-		{genericPkg + `p1; func f[T any](T); var _ = f[int]`, `f[int]`, `func(int)`},
-		{genericPkg + `p2; func f[T any](T); func _() { f(42) }`, `f`, `func[T₁ interface{}](T₁)`},
-		{genericPkg + `p3; func f[T any](T); func _() { f(42) }`, `f(42)`, `()`},
+		{genericPkg + `p0; func f[T any](T) {}; var _ = f[int]`, `f`, `func[generic_p0.T₁ interface{}](generic_p0.T₁)`},
+		{genericPkg + `p1; func f[T any](T) {}; var _ = f[int]`, `f[int]`, `func(int)`},
+		{genericPkg + `p2; func f[T any](T) {}; func _() { f(42) }`, `f`, `func[generic_p2.T₁ interface{}](generic_p2.T₁)`},
+		{genericPkg + `p3; func f[T any](T) {}; func _() { f(42) }`, `f(42)`, `()`},
 
 		// type parameters
 		{genericPkg + `t0; type t[] int; var _ t`, `t`, `generic_t0.t`}, // t[] is a syntax error that is ignored in this test in favor of t
-		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[P₁ interface{}]`},
-		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[P₁ interface{}]`},
-		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[P₁, Q₂ interface{}]`},
-		{brokenPkg + `t4; type t[P, Q interface{ m() }] int; var _ t[int, int]`, `t`, `broken_t4.t[P₁, Q₂ interface{m()}]`},
+		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[generic_t1.P₁ interface{}]`},
+		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[generic_t2.P₁ interface{}]`},
+		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[generic_t3.P₁, generic_t3.Q₂ interface{}]`},
+		{brokenPkg + `t4; type t[P, Q interface{ m() }] int; var _ t[int, int]`, `t`, `broken_t4.t[broken_t4.P₁, broken_t4.Q₂ interface{m()}]`},
 
 		// instantiated types must be sanitized
 		{genericPkg + `g0; type t[P any] int; var x struct{ f t[int] }; var _ = x.f`, `x.f`, `generic_g0.t[int]`},
 
 		// issue 45096
-		{genericPkg + `issue45096; func _[T interface{ type int8, int16, int32  }](x T) { _ = x < 0 }`, `0`, `T₁`},
+		{genericPkg + `issue45096; func _[T interface{ ~int8 | ~int16 | ~int32 }](x T) { _ = x < 0 }`, `0`, `generic_issue45096.T₁`},
 	}
 
 	for _, test := range tests {
-		ResetId() // avoid renumbering of type parameter ids when adding tests
 		info := Info{Types: make(map[syntax.Expr]TypeAndValue)}
 		var name string
 		if strings.HasPrefix(test.src, brokenPkg) {
@@ -390,60 +389,60 @@
 		targs []string
 		sig   string
 	}{
-		{genericPkg + `p0; func f[T any](T); func _() { f(42) }`,
+		{genericPkg + `p0; func f[T any](T) {}; func _() { f(42) }`,
 			`f`,
 			[]string{`int`},
 			`func(int)`,
 		},
-		{genericPkg + `p1; func f[T any](T) T; func _() { f('@') }`,
+		{genericPkg + `p1; func f[T any](T) T { panic(0) }; func _() { f('@') }`,
 			`f`,
 			[]string{`rune`},
 			`func(rune) rune`,
 		},
-		{genericPkg + `p2; func f[T any](...T) T; func _() { f(0i) }`,
+		{genericPkg + `p2; func f[T any](...T) T { panic(0) }; func _() { f(0i) }`,
 			`f`,
 			[]string{`complex128`},
 			`func(...complex128) complex128`,
 		},
-		{genericPkg + `p3; func f[A, B, C any](A, *B, []C); func _() { f(1.2, new(string), []byte{}) }`,
+		{genericPkg + `p3; func f[A, B, C any](A, *B, []C) {}; func _() { f(1.2, new(string), []byte{}) }`,
 			`f`,
 			[]string{`float64`, `string`, `byte`},
 			`func(float64, *string, []byte)`,
 		},
-		{genericPkg + `p4; func f[A, B any](A, *B, ...[]B); func _() { f(1.2, new(byte)) }`,
+		{genericPkg + `p4; func f[A, B any](A, *B, ...[]B) {}; func _() { f(1.2, new(byte)) }`,
 			`f`,
 			[]string{`float64`, `byte`},
 			`func(float64, *byte, ...[]byte)`,
 		},
 
 		// we don't know how to translate these but we can type-check them
-		{genericPkg + `q0; type T struct{}; func (T) m[P any](P); func _(x T) { x.m(42) }`,
+		{genericPkg + `q0; type T struct{}; func (T) m[P any](P) {}; func _(x T) { x.m(42) }`,
 			`x.m`,
 			[]string{`int`},
 			`func(int)`,
 		},
-		{genericPkg + `q1; type T struct{}; func (T) m[P any](P) P; func _(x T) { x.m(42) }`,
+		{genericPkg + `q1; type T struct{}; func (T) m[P any](P) P { panic(0) }; func _(x T) { x.m(42) }`,
 			`x.m`,
 			[]string{`int`},
 			`func(int) int`,
 		},
-		{genericPkg + `q2; type T struct{}; func (T) m[P any](...P) P; func _(x T) { x.m(42) }`,
+		{genericPkg + `q2; type T struct{}; func (T) m[P any](...P) P { panic(0) }; func _(x T) { x.m(42) }`,
 			`x.m`,
 			[]string{`int`},
 			`func(...int) int`,
 		},
-		{genericPkg + `q3; type T struct{}; func (T) m[A, B, C any](A, *B, []C); func _(x T) { x.m(1.2, new(string), []byte{}) }`,
+		{genericPkg + `q3; type T struct{}; func (T) m[A, B, C any](A, *B, []C) {}; func _(x T) { x.m(1.2, new(string), []byte{}) }`,
 			`x.m`,
 			[]string{`float64`, `string`, `byte`},
 			`func(float64, *string, []byte)`,
 		},
-		{genericPkg + `q4; type T struct{}; func (T) m[A, B any](A, *B, ...[]B); func _(x T) { x.m(1.2, new(byte)) }`,
+		{genericPkg + `q4; type T struct{}; func (T) m[A, B any](A, *B, ...[]B) {}; func _(x T) { x.m(1.2, new(byte)) }`,
 			`x.m`,
 			[]string{`float64`, `byte`},
 			`func(float64, *byte, ...[]byte)`,
 		},
 
-		{genericPkg + `r0; type T[P any] struct{}; func (_ T[P]) m[Q any](Q); func _[P any](x T[P]) { x.m(42) }`,
+		{genericPkg + `r0; type T[P any] struct{}; func (_ T[P]) m[Q any](Q) {}; func _[P any](x T[P]) { x.m(42) }`,
 			`x.m`,
 			[]string{`int`},
 			`func(int)`,
@@ -455,38 +454,38 @@
 		// 	`func(float64)`,
 		// },
 
-		{genericPkg + `s1; func f[T any, P interface{type *T}](x T); func _(x string) { f(x) }`,
+		{genericPkg + `s1; func f[T any, P interface{~*T}](x T) {}; func _(x string) { f(x) }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func(x string)`,
 		},
-		{genericPkg + `s2; func f[T any, P interface{type *T}](x []T); func _(x []int) { f(x) }`,
+		{genericPkg + `s2; func f[T any, P interface{~*T}](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `*int`},
 			`func(x []int)`,
 		},
-		{genericPkg + `s3; type C[T any] interface{type chan<- T}; func f[T any, P C[T]](x []T); func _(x []int) { f(x) }`,
+		{genericPkg + `s3; type C[T any] interface{~chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `chan<- int`},
 			`func(x []int)`,
 		},
-		{genericPkg + `s4; type C[T any] interface{type chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T); func _(x []int) { f(x) }`,
+		{genericPkg + `s4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func(x []int)`,
 		},
 
-		{genericPkg + `t1; func f[T any, P interface{type *T}]() T; func _() { _ = f[string] }`,
+		{genericPkg + `t1; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = f[string] }`,
 			`f`,
 			[]string{`string`, `*string`},
 			`func() string`,
 		},
-		{genericPkg + `t2; type C[T any] interface{type chan<- T}; func f[T any, P C[T]]() []T; func _() { _ = f[int] }`,
+		{genericPkg + `t2; type C[T any] interface{~chan<- T}; func f[T any, P C[T]]() []T { return nil }; func _() { _ = f[int] }`,
 			`f`,
 			[]string{`int`, `chan<- int`},
 			`func() []int`,
 		},
-		{genericPkg + `t3; type C[T any] interface{type chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T; func _() { _ = f[int] }`,
+		{genericPkg + `t3; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
 			`f`,
 			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
 			`func() []int`,
@@ -515,7 +514,7 @@
 				panic(fmt.Sprintf("unexpected call expression type %T", call))
 			}
 			if syntax.String(fun) == test.fun {
-				targs = inf.Targs
+				targs = inf.TArgs
 				sig = inf.Sig
 				break
 			}
@@ -1568,6 +1567,14 @@
 	}
 }
 
+var nopos syntax.Pos
+
+// newDefined creates a new defined type named T with the given underlying type.
+func newDefined(underlying Type) *Named {
+	tname := NewTypeName(nopos, nil, "T", nil)
+	return NewNamed(tname, underlying, nil)
+}
+
 func TestConvertibleTo(t *testing.T) {
 	for _, test := range []struct {
 		v, t Type
@@ -1847,3 +1854,28 @@
 		}
 	}
 }
+
+func TestInstantiate(t *testing.T) {
+	// eventually we like more tests but this is a start
+	const src = genericPkg + "p; type T[P any] *T[P]"
+	pkg, err := pkgFor(".", src, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// type T should have one type parameter
+	T := pkg.Scope().Lookup("T").Type().(*Named)
+	if n := T.TParams().Len(); n != 1 {
+		t.Fatalf("expected 1 type parameter; found %d", n)
+	}
+
+	// instantiation should succeed (no endless recursion)
+	// even with a nil *Checker
+	var check *Checker
+	res := check.Instantiate(nopos, T, []Type{Typ[Int]}, nil, false)
+
+	// instantiated type should point to itself
+	if res.Underlying().(*Pointer).Elem() != res {
+		t.Fatalf("unexpected result type: %s", res)
+	}
+}
diff --git a/src/cmd/compile/internal/types2/array.go b/src/cmd/compile/internal/types2/array.go
new file mode 100644
index 0000000..502d49b
--- /dev/null
+++ b/src/cmd/compile/internal/types2/array.go
@@ -0,0 +1,25 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// An Array represents an array type.
+type Array struct {
+	len  int64
+	elem Type
+}
+
+// NewArray returns a new array type for the given element type and length.
+// A negative length indicates an unknown length.
+func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} }
+
+// Len returns the length of array a.
+// A negative result indicates an unknown length.
+func (a *Array) Len() int64 { return a.len }
+
+// Elem returns element type of array a.
+func (a *Array) Elem() Type { return a.elem }
+
+func (a *Array) Underlying() Type { return a }
+func (a *Array) String() string   { return TypeString(a, nil) }
diff --git a/src/cmd/compile/internal/types2/assignments.go b/src/cmd/compile/internal/types2/assignments.go
index 583118c..6184fc2 100644
--- a/src/cmd/compile/internal/types2/assignments.go
+++ b/src/cmd/compile/internal/types2/assignments.go
@@ -68,7 +68,7 @@
 	// x.typ is typed
 
 	// A generic (non-instantiated) function value cannot be assigned to a variable.
-	if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
+	if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
 		check.errorf(x, "cannot use generic function %s without instantiation in %s", x, context)
 	}
 
diff --git a/src/cmd/compile/internal/types2/basic.go b/src/cmd/compile/internal/types2/basic.go
new file mode 100644
index 0000000..2fd973c
--- /dev/null
+++ b/src/cmd/compile/internal/types2/basic.go
@@ -0,0 +1,82 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// BasicKind describes the kind of basic type.
+type BasicKind int
+
+const (
+	Invalid BasicKind = iota // type is invalid
+
+	// predeclared types
+	Bool
+	Int
+	Int8
+	Int16
+	Int32
+	Int64
+	Uint
+	Uint8
+	Uint16
+	Uint32
+	Uint64
+	Uintptr
+	Float32
+	Float64
+	Complex64
+	Complex128
+	String
+	UnsafePointer
+
+	// types for untyped values
+	UntypedBool
+	UntypedInt
+	UntypedRune
+	UntypedFloat
+	UntypedComplex
+	UntypedString
+	UntypedNil
+
+	// aliases
+	Byte = Uint8
+	Rune = Int32
+)
+
+// BasicInfo is a set of flags describing properties of a basic type.
+type BasicInfo int
+
+// Properties of basic types.
+const (
+	IsBoolean BasicInfo = 1 << iota
+	IsInteger
+	IsUnsigned
+	IsFloat
+	IsComplex
+	IsString
+	IsUntyped
+
+	IsOrdered   = IsInteger | IsFloat | IsString
+	IsNumeric   = IsInteger | IsFloat | IsComplex
+	IsConstType = IsBoolean | IsNumeric | IsString
+)
+
+// A Basic represents a basic type.
+type Basic struct {
+	kind BasicKind
+	info BasicInfo
+	name string
+}
+
+// Kind returns the kind of basic type b.
+func (b *Basic) Kind() BasicKind { return b.kind }
+
+// Info returns information about properties of basic type b.
+func (b *Basic) Info() BasicInfo { return b.info }
+
+// Name returns the name of basic type b.
+func (b *Basic) Name() string { return b.name }
+
+func (b *Basic) Underlying() Type { return b }
+func (b *Basic) String() string   { return TypeString(b, nil) }
diff --git a/src/cmd/compile/internal/types2/builtins.go b/src/cmd/compile/internal/types2/builtins.go
index f90e06f..da2dcf5 100644
--- a/src/cmd/compile/internal/types2/builtins.go
+++ b/src/cmd/compile/internal/types2/builtins.go
@@ -46,7 +46,7 @@
 	default:
 		// make argument getter
 		xlist, _ := check.exprList(call.ArgList, false)
-		arg = func(x *operand, i int) { *x = *xlist[i]; x.typ = expand(x.typ) }
+		arg = func(x *operand, i int) { *x = *xlist[i] }
 		nargs = len(xlist)
 		// evaluate first argument, if present
 		if nargs > 0 {
@@ -144,7 +144,7 @@
 		mode := invalid
 		var typ Type
 		var val constant.Value
-		switch typ = implicitArrayDeref(optype(x.typ)); t := typ.(type) {
+		switch typ = arrayPtrDeref(under(x.typ)); t := typ.(type) {
 		case *Basic:
 			if isString(t) && id == _Len {
 				if x.mode == constant_ {
@@ -178,9 +178,9 @@
 				mode = value
 			}
 
-		case *Sum:
-			if t.is(func(t Type) bool {
-				switch t := under(t).(type) {
+		case *TypeParam:
+			if t.underIs(func(t Type) bool {
+				switch t := arrayPtrDeref(t).(type) {
 				case *Basic:
 					if isString(t) && id == _Len {
 						return true
@@ -212,19 +212,23 @@
 
 	case _Close:
 		// close(c)
-		c := asChan(x.typ)
-		if c == nil {
-			check.errorf(x, invalidArg+"%s is not a channel", x)
+		if !underIs(x.typ, func(u Type) bool {
+			uch, _ := u.(*Chan)
+			if uch == nil {
+				check.errorf(x, invalidOp+"cannot close non-channel %s", x)
+				return false
+			}
+			if uch.dir == RecvOnly {
+				check.errorf(x, invalidOp+"cannot close receive-only channel %s", x)
+				return false
+			}
+			return true
+		}) {
 			return
 		}
-		if c.dir == RecvOnly {
-			check.errorf(x, invalidArg+"%s must not be a receive-only channel", x)
-			return
-		}
-
 		x.mode = novalue
 		if check.Types != nil {
-			check.recordBuiltinType(call.Fun, makeSig(nil, c))
+			check.recordBuiltinType(call.Fun, makeSig(nil, x.typ))
 		}
 
 	case _Complex:
@@ -281,7 +285,7 @@
 		}
 
 		// both argument types must be identical
-		if !check.identical(x.typ, y.typ) {
+		if !Identical(x.typ, y.typ) {
 			check.errorf(x, invalidOp+"%v (mismatched types %s and %s)", call, x.typ, y.typ)
 			return
 		}
@@ -332,13 +336,15 @@
 			return
 		}
 		var src Type
-		switch t := optype(y.typ).(type) {
+		switch t := under(y.typ).(type) {
 		case *Basic:
 			if isString(y.typ) {
 				src = universeByte
 			}
 		case *Slice:
 			src = t.elem
+		case *TypeParam:
+			check.error(x, "copy on generic operands not yet implemented")
 		}
 
 		if dst == nil || src == nil {
@@ -346,7 +352,7 @@
 			return
 		}
 
-		if !check.identical(dst, src) {
+		if !Identical(dst, src) {
 			check.errorf(x, invalidArg+"arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
 			return
 		}
@@ -358,25 +364,40 @@
 		x.typ = Typ[Int]
 
 	case _Delete:
-		// delete(m, k)
-		m := asMap(x.typ)
-		if m == nil {
-			check.errorf(x, invalidArg+"%s is not a map", x)
+		// delete(map_, key)
+		// map_ must be a map type or a type parameter describing map types.
+		// The key cannot be a type parameter for now.
+		map_ := x.typ
+		var key Type
+		if !underIs(map_, func(u Type) bool {
+			map_, _ := u.(*Map)
+			if map_ == nil {
+				check.errorf(x, invalidArg+"%s is not a map", x)
+				return false
+			}
+			if key != nil && !Identical(map_.key, key) {
+				check.errorf(x, invalidArg+"maps of %s must have identical key types", x)
+				return false
+			}
+			key = map_.key
+			return true
+		}) {
 			return
 		}
+
 		arg(x, 1) // k
 		if x.mode == invalid {
 			return
 		}
 
-		check.assignment(x, m.key, "argument to delete")
+		check.assignment(x, key, "argument to delete")
 		if x.mode == invalid {
 			return
 		}
 
 		x.mode = novalue
 		if check.Types != nil {
-			check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
+			check.recordBuiltinType(call.Fun, makeSig(nil, map_, key))
 		}
 
 	case _Imag, _Real:
@@ -451,39 +472,21 @@
 			return
 		}
 
-		min, max := -1, 10
-		var valid func(t Type) bool
-		valid = func(t Type) bool {
-			var m int
-			switch t := optype(t).(type) {
-			case *Slice:
-				m = 2
-			case *Map, *Chan:
-				m = 1
-			case *Sum:
-				return t.is(valid)
-			default:
-				return false
-			}
-			if m > min {
-				min = m
-			}
-			if m+1 < max {
-				max = m + 1
-			}
-			return true
-		}
-
-		if !valid(T) {
+		var min int // minimum number of arguments
+		switch optype(T).(type) {
+		case *Slice:
+			min = 2
+		case *Map, *Chan:
+			min = 1
+		case *top:
+			check.errorf(arg0, invalidArg+"cannot make %s; type parameter has no structural type", arg0)
+			return
+		default:
 			check.errorf(arg0, invalidArg+"cannot make %s; type must be slice, map, or channel", arg0)
 			return
 		}
-		if nargs < min || max < nargs {
-			if min == max {
-				check.errorf(call, "%v expects %d arguments; found %d", call, min, nargs)
-			} else {
-				check.errorf(call, "%v expects %d or %d arguments; found %d", call, min, max, nargs)
-			}
+		if nargs < min || min+1 < nargs {
+			check.errorf(call, invalidOp+"%v expects %d or %d arguments; found %d", call, min, min+1, nargs)
 			return
 		}
 
@@ -603,19 +606,22 @@
 
 	case _Alignof:
 		// unsafe.Alignof(x T) uintptr
-		if asTypeParam(x.typ) != nil {
-			check.errorf(call, invalidOp+"unsafe.Alignof undefined for %s", x)
-			return
-		}
 		check.assignment(x, nil, "argument to unsafe.Alignof")
 		if x.mode == invalid {
 			return
 		}
 
-		x.mode = constant_
-		x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+		if hasVarSize(x.typ) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], x.typ))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Offsetof:
 		// unsafe.Offsetof(x T) uintptr, where x must be a selector
@@ -635,7 +641,7 @@
 
 		base := derefStructPtr(x.typ)
 		sel := selx.Sel.Value
-		obj, index, indirect := check.lookupFieldOrMethod(base, false, check.pkg, sel)
+		obj, index, indirect := LookupFieldOrMethod(base, false, check.pkg, sel)
 		switch obj.(type) {
 		case nil:
 			check.errorf(x, invalidArg+"%s has no single field %s", base, sel)
@@ -653,30 +659,43 @@
 			return
 		}
 
-		// TODO(gri) Should we pass x.typ instead of base (and indirect report if derefStructPtr indirected)?
+		// TODO(gri) Should we pass x.typ instead of base (and have indirect report if derefStructPtr indirected)?
 		check.recordSelection(selx, FieldVal, base, obj, index, false)
 
-		offs := check.conf.offsetof(base, index)
-		x.mode = constant_
-		x.val = constant.MakeInt64(offs)
+		// The field offset is considered a variable even if the field is declared before
+		// the part of the struct which is variable-sized. This makes both the rules
+		// simpler and also permits (or at least doesn't prevent) a compiler from re-
+		// arranging struct fields if it wanted to.
+		if hasVarSize(base) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], obj.Type()))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.offsetof(base, index))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Sizeof:
 		// unsafe.Sizeof(x T) uintptr
-		if asTypeParam(x.typ) != nil {
-			check.errorf(call, invalidOp+"unsafe.Sizeof undefined for %s", x)
-			return
-		}
 		check.assignment(x, nil, "argument to unsafe.Sizeof")
 		if x.mode == invalid {
 			return
 		}
 
-		x.mode = constant_
-		x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+		if hasVarSize(x.typ) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], x.typ))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Slice:
 		// unsafe.Slice(ptr *T, len IntegerType) []T
@@ -748,6 +767,25 @@
 	return true
 }
 
+// hasVarSize reports if the size of type t is variable due to type parameters.
+func hasVarSize(t Type) bool {
+	switch t := under(t).(type) {
+	case *Array:
+		return hasVarSize(t.elem)
+	case *Struct:
+		for _, f := range t.fields {
+			if hasVarSize(f.typ) {
+				return true
+			}
+		}
+	case *TypeParam:
+		return true
+	case *Named, *Union, *top:
+		unreachable()
+	}
+	return false
+}
+
 // applyTypeFunc applies f to x. If x is a type parameter,
 // the result is a type parameter constrained by an new
 // interface bound. The type bounds for that interface
@@ -759,10 +797,10 @@
 	if tp := asTypeParam(x); tp != nil {
 		// Test if t satisfies the requirements for the argument
 		// type and collect possible result types at the same time.
-		var rtypes []Type
-		if !tp.Bound().is(func(x Type) bool {
-			if r := f(x); r != nil {
-				rtypes = append(rtypes, r)
+		var terms []*Term
+		if !tp.iface().typeSet().is(func(t *term) bool {
+			if r := f(t.typ); r != nil {
+				terms = append(terms, NewTerm(t.tilde, r))
 				return true
 			}
 			return false
@@ -775,11 +813,12 @@
 		//           uses of real() where the result is used to
 		//           define type and initialize a variable?
 
-		// construct a suitable new type parameter
-		tpar := NewTypeName(nopos, nil /* = Universe pkg */, "<type parameter>", nil)
-		ptyp := check.NewTypeParam(tpar, 0, &emptyInterface) // assigns type to tpar as a side-effect
-		tsum := NewSum(rtypes)
-		ptyp.bound = &Interface{types: tsum, allMethods: markComplete, allTypes: tsum}
+		// Construct a suitable new type parameter for the sum type. The
+		// type param is placed in the current package so export/import
+		// works as expected.
+		tpar := NewTypeName(nopos, check.pkg, "<type parameter>", nil)
+		ptyp := check.NewTypeParam(tpar, NewInterfaceType(nil, []Type{NewUnion(terms)})) // assigns type to tpar as a side-effect
+		ptyp.index = tp.index
 
 		return ptyp
 	}
@@ -803,10 +842,9 @@
 	return &Signature{params: params, results: result}
 }
 
-// implicitArrayDeref returns A if typ is of the form *A and A is an array;
+// arrayPtrDeref returns A if typ is of the form *A and A is an array;
 // otherwise it returns typ.
-//
-func implicitArrayDeref(typ Type) Type {
+func arrayPtrDeref(typ Type) Type {
 	if p, ok := typ.(*Pointer); ok {
 		if a := asArray(p.base); a != nil {
 			return a
diff --git a/src/cmd/compile/internal/types2/builtins_test.go b/src/cmd/compile/internal/types2/builtins_test.go
index 82c786b..52dbba1 100644
--- a/src/cmd/compile/internal/types2/builtins_test.go
+++ b/src/cmd/compile/internal/types2/builtins_test.go
@@ -7,6 +7,7 @@
 import (
 	"cmd/compile/internal/syntax"
 	"fmt"
+	"strings"
 	"testing"
 
 	. "cmd/compile/internal/types2"
@@ -111,12 +112,15 @@
 
 	{"Alignof", `_ = unsafe.Alignof(0)`, `invalid type`},                 // constant
 	{"Alignof", `var x struct{}; _ = unsafe.Alignof(x)`, `invalid type`}, // constant
+	{"Alignof", `var x P; _ = unsafe.Alignof(x)`, `func(p.P₁) uintptr`},
 
 	{"Offsetof", `var x struct{f bool}; _ = unsafe.Offsetof(x.f)`, `invalid type`},           // constant
 	{"Offsetof", `var x struct{_ int; f bool}; _ = unsafe.Offsetof((&x).f)`, `invalid type`}, // constant
+	{"Offsetof", `var x struct{_ int; f P}; _ = unsafe.Offsetof((&x).f)`, `func(p.P₁) uintptr`},
 
 	{"Sizeof", `_ = unsafe.Sizeof(0)`, `invalid type`},                 // constant
 	{"Sizeof", `var x struct{}; _ = unsafe.Sizeof(x)`, `invalid type`}, // constant
+	{"Sizeof", `var x P; _ = unsafe.Sizeof(x)`, `func(p.P₁) uintptr`},
 
 	{"Slice", `var p *int; _ = unsafe.Slice(p, 1)`, `func(*int, int) []int`},
 	{"Slice", `var p *byte; var n uintptr; _ = unsafe.Slice(p, n)`, `func(*byte, uintptr) []byte`},
@@ -149,9 +153,14 @@
 	}
 }
 
+func parseGenericSrc(path, src string) (*syntax.File, error) {
+	errh := func(error) {} // dummy error handler so that parsing continues in presence of errors
+	return syntax.Parse(syntax.NewFileBase(path), strings.NewReader(src), errh, nil, syntax.AllowGenerics)
+}
+
 func testBuiltinSignature(t *testing.T, name, src0, want string) {
-	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _() { %s }`, src0)
-	f, err := parseSrc("", src)
+	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _[P any]() { %s }`, src0)
+	f, err := parseGenericSrc("", src)
 	if err != nil {
 		t.Errorf("%s: %s", src0, err)
 		return
diff --git a/src/cmd/compile/internal/types2/call.go b/src/cmd/compile/internal/types2/call.go
index 6d14934..049d80d 100644
--- a/src/cmd/compile/internal/types2/call.go
+++ b/src/cmd/compile/internal/types2/call.go
@@ -26,7 +26,7 @@
 
 	// check number of type arguments (got) vs number of type parameters (want)
 	sig := x.typ.(*Signature)
-	got, want := len(targs), len(sig.tparams)
+	got, want := len(targs), sig.TParams().Len()
 	if !useConstraintTypeInference && got != want || got > want {
 		check.errorf(xlist[got-1], "got %d type arguments but want %d", got, want)
 		x.mode = invalid
@@ -37,7 +37,7 @@
 	// if we don't have enough type arguments, try type inference
 	inferred := false
 	if got < want {
-		targs = check.infer(inst.Pos(), sig.tparams, targs, nil, nil, true)
+		targs = check.infer(inst.Pos(), sig.TParams().list(), targs, nil, nil, true)
 		if targs == nil {
 			// error was already reported
 			x.mode = invalid
@@ -56,8 +56,8 @@
 	}
 
 	// instantiate function signature
-	res := check.instantiate(x.Pos(), sig, targs, poslist).(*Signature)
-	assert(res.tparams == nil) // signature is not generic anymore
+	res := check.Instantiate(x.Pos(), sig, targs, poslist, true).(*Signature)
+	assert(res.TParams().Len() == 0) // signature is not generic anymore
 	if inferred {
 		check.recordInferred(inst, targs, res)
 	}
@@ -99,7 +99,6 @@
 			check.expr(x, call.ArgList[0])
 			if x.mode != invalid {
 				if t := asInterface(T); t != nil {
-					check.completeInterface(nopos, t)
 					if t.IsConstraint() {
 						check.errorf(call, "cannot use interface %s in conversion (contains type list or is comparable)", T)
 						break
@@ -156,7 +155,7 @@
 		assert(len(targs) == len(xlist))
 
 		// check number of type arguments (got) vs number of type parameters (want)
-		got, want := len(targs), len(sig.tparams)
+		got, want := len(targs), sig.TParams().Len()
 		if got > want {
 			check.errorf(xlist[want], "got %d type arguments but want %d", got, want)
 			check.use(call.ArgList...)
@@ -190,7 +189,7 @@
 
 	// if type inference failed, a parametrized result must be invalidated
 	// (operands cannot have a parametrized type)
-	if x.mode == value && len(sig.tparams) > 0 && isParameterized(sig.tparams, x.typ) {
+	if x.mode == value && sig.TParams().Len() > 0 && isParameterized(sig.TParams().list(), x.typ) {
 		x.mode = invalid
 	}
 
@@ -318,24 +317,24 @@
 	}
 
 	// infer type arguments and instantiate signature if necessary
-	if len(sig.tparams) > 0 {
+	if sig.TParams().Len() > 0 {
 		// TODO(gri) provide position information for targs so we can feed
 		//           it to the instantiate call for better error reporting
-		targs = check.infer(call.Pos(), sig.tparams, targs, sigParams, args, true)
+		targs := check.infer(call.Pos(), sig.TParams().list(), targs, sigParams, args, true)
 		if targs == nil {
 			return // error already reported
 		}
 
 		// compute result signature
-		rsig = check.instantiate(call.Pos(), sig, targs, nil).(*Signature)
-		assert(rsig.tparams == nil) // signature is not generic anymore
+		rsig = check.Instantiate(call.Pos(), sig, targs, nil, true).(*Signature)
+		assert(rsig.TParams().Len() == 0) // signature is not generic anymore
 		check.recordInferred(call, targs, rsig)
 
 		// Optimization: Only if the parameter list was adjusted do we
 		// need to compute it from the adjusted list; otherwise we can
 		// simply use the result signature's parameter list.
 		if adjusted {
-			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.tparams, targs)).(*Tuple)
+			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.TParams().list(), targs)).(*Tuple)
 		} else {
 			sigParams = rsig.params
 		}
@@ -468,7 +467,7 @@
 
 	check.instantiatedOperand(x)
 
-	obj, index, indirect = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
+	obj, index, indirect = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
 	if obj == nil {
 		switch {
 		case index != nil:
@@ -480,11 +479,10 @@
 			var why string
 			if tpar := asTypeParam(x.typ); tpar != nil {
 				// Type parameter bounds don't specify fields, so don't mention "field".
-				switch obj := tpar.Bound().obj.(type) {
-				case nil:
+				if tname := tpar.iface().obj; tname != nil {
+					why = check.sprintf("interface %s has no method %s", tname.name, sel)
+				} else {
 					why = check.sprintf("type bound for %s has no method %s", x.typ, sel)
-				case *TypeName:
-					why = check.sprintf("interface %s has no method %s", obj.name, sel)
 				}
 			} else {
 				why = check.sprintf("type %s has no field or method %s", x.typ, sel)
@@ -498,7 +496,7 @@
 				} else {
 					changeCase = string(unicode.ToUpper(r)) + sel[1:]
 				}
-				if obj, _, _ = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
+				if obj, _, _ = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
 					why += ", but does have " + changeCase
 				}
 			}
@@ -518,7 +516,7 @@
 		// the signature accordingly.
 		// TODO(gri) factor this code out
 		sig := m.typ.(*Signature)
-		if len(sig.rparams) > 0 {
+		if sig.RParams().Len() > 0 {
 			// For inference to work, we must use the receiver type
 			// matching the receiver in the actual method declaration.
 			// If the method is embedded, the matching receiver is the
@@ -547,7 +545,7 @@
 			// the receiver type arguments here, the receiver must be be otherwise invalid
 			// and an error has been reported elsewhere.
 			arg := operand{mode: variable, expr: x.expr, typ: recv}
-			targs := check.infer(m.pos, sig.rparams, nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
+			targs := check.infer(m.pos, sig.RParams().list(), nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
 			//check.dump("### inferred targs = %s", targs)
 			if targs == nil {
 				// We may reach here if there were other errors (see issue #40056).
@@ -557,7 +555,7 @@
 			// (If we modify m, some tests will fail; possibly because the m is in use.)
 			// TODO(gri) investigate and provide a correct explanation here
 			copy := *m
-			copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.rparams, targs))
+			copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.RParams().list(), targs))
 			obj = &copy
 		}
 		// TODO(gri) we also need to do substitution for parameterized interface methods
@@ -576,17 +574,37 @@
 
 		check.recordSelection(e, MethodExpr, x.typ, m, index, indirect)
 
-		// the receiver type becomes the type of the first function
-		// argument of the method expression's function type
-		var params []*Var
 		sig := m.typ.(*Signature)
+		if sig.recv == nil {
+			check.error(e, "illegal cycle in method declaration")
+			goto Error
+		}
+
+		// The receiver type becomes the type of the first function
+		// argument of the method expression's function type.
+		var params []*Var
 		if sig.params != nil {
 			params = sig.params.vars
 		}
+		// Be consistent about named/unnamed parameters. This is not needed
+		// for type-checking, but the newly constructed signature may appear
+		// in an error message and then have mixed named/unnamed parameters.
+		// (An alternative would be to not print parameter names in errors,
+		// but it's useful to see them; this is cheap and method expressions
+		// are rare.)
+		name := ""
+		if len(params) > 0 && params[0].name != "" {
+			// name needed
+			name = sig.recv.name
+			if name == "" {
+				name = "_"
+			}
+		}
+		params = append([]*Var{NewVar(sig.recv.pos, sig.recv.pkg, name, x.typ)}, params...)
 		x.mode = value
 		x.typ = &Signature{
 			tparams:  sig.tparams,
-			params:   NewTuple(append([]*Var{NewVar(nopos, check.pkg, "_", x.typ)}, params...)...),
+			params:   NewTuple(params...),
 			results:  sig.results,
 			variadic: sig.variadic,
 		}
diff --git a/src/cmd/compile/internal/types2/chan.go b/src/cmd/compile/internal/types2/chan.go
new file mode 100644
index 0000000..77650df
--- /dev/null
+++ b/src/cmd/compile/internal/types2/chan.go
@@ -0,0 +1,35 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Chan represents a channel type.
+type Chan struct {
+	dir  ChanDir
+	elem Type
+}
+
+// A ChanDir value indicates a channel direction.
+type ChanDir int
+
+// The direction of a channel is indicated by one of these constants.
+const (
+	SendRecv ChanDir = iota
+	SendOnly
+	RecvOnly
+)
+
+// NewChan returns a new channel type for the given direction and element type.
+func NewChan(dir ChanDir, elem Type) *Chan {
+	return &Chan{dir: dir, elem: elem}
+}
+
+// Dir returns the direction of channel c.
+func (c *Chan) Dir() ChanDir { return c.dir }
+
+// Elem returns the element type of channel c.
+func (c *Chan) Elem() Type { return c.elem }
+
+func (c *Chan) Underlying() Type { return c }
+func (c *Chan) String() string   { return TypeString(c, nil) }
diff --git a/src/cmd/compile/internal/types2/check.go b/src/cmd/compile/internal/types2/check.go
index 8d6cd1e..6bc965c 100644
--- a/src/cmd/compile/internal/types2/check.go
+++ b/src/cmd/compile/internal/types2/check.go
@@ -71,7 +71,7 @@
 // A dotImportKey describes a dot-imported object in the given scope.
 type dotImportKey struct {
 	scope *Scope
-	obj   Object
+	name  string
 }
 
 // A Checker maintains the state of the type checker.
@@ -82,11 +82,11 @@
 	conf *Config
 	pkg  *Package
 	*Info
-	version version                     // accepted language version
-	objMap  map[Object]*declInfo        // maps package-level objects and (non-interface) methods to declaration info
-	impMap  map[importKey]*Package      // maps (import path, source directory) to (complete or fake) package
-	posMap  map[*Interface][]syntax.Pos // maps interface types to lists of embedded interface positions
-	typMap  map[string]*Named           // maps an instantiated named type hash to a *Named type
+	version version                // accepted language version
+	nextID  uint64                 // unique Id for type parameters (first valid Id is 1)
+	objMap  map[Object]*declInfo   // maps package-level objects and (non-interface) methods to declaration info
+	impMap  map[importKey]*Package // maps (import path, source directory) to (complete or fake) package
+	typMap  map[string]*Named      // maps an instantiated named type hash to a *Named type
 
 	// pkgPathMap maps package names to the set of distinct import paths we've
 	// seen for that name, anywhere in the import graph. It is used for
@@ -188,7 +188,6 @@
 		version: version,
 		objMap:  make(map[Object]*declInfo),
 		impMap:  make(map[importKey]*Package),
-		posMap:  make(map[*Interface][]syntax.Pos),
 		typMap:  make(map[string]*Named),
 	}
 }
@@ -283,11 +282,6 @@
 	print("== recordUntyped ==")
 	check.recordUntyped()
 
-	if check.Info != nil {
-		print("== sanitizeInfo ==")
-		sanitizeInfo(check.Info)
-	}
-
 	check.pkg.complete = true
 
 	// no longer needed - release memory
diff --git a/src/cmd/compile/internal/types2/conversions.go b/src/cmd/compile/internal/types2/conversions.go
index 30201e2..6c26a4c 100644
--- a/src/cmd/compile/internal/types2/conversions.go
+++ b/src/cmd/compile/internal/types2/conversions.go
@@ -93,7 +93,7 @@
 	V := x.typ
 	Vu := under(V)
 	Tu := under(T)
-	if check.identicalIgnoreTags(Vu, Tu) {
+	if IdenticalIgnoreTags(Vu, Tu) {
 		return true
 	}
 
@@ -101,7 +101,7 @@
 	// have identical underlying types if tags are ignored"
 	if V, ok := V.(*Pointer); ok {
 		if T, ok := T.(*Pointer); ok {
-			if check.identicalIgnoreTags(under(V.base), under(T.base)) {
+			if IdenticalIgnoreTags(under(V.base), under(T.base)) {
 				return true
 			}
 		}
@@ -142,7 +142,7 @@
 	if s := asSlice(V); s != nil {
 		if p := asPointer(T); p != nil {
 			if a := asArray(p.Elem()); a != nil {
-				if check.identical(s.Elem(), a.Elem()) {
+				if Identical(s.Elem(), a.Elem()) {
 					if check == nil || check.allowVersion(check.pkg, 1, 17) {
 						return true
 					}
diff --git a/src/cmd/compile/internal/types2/decl.go b/src/cmd/compile/internal/types2/decl.go
index 1333e4c..bfccbc5 100644
--- a/src/cmd/compile/internal/types2/decl.go
+++ b/src/cmd/compile/internal/types2/decl.go
@@ -317,6 +317,8 @@
 		}
 
 	case *Named:
+		t.expand()
+
 		// don't touch the type if it is from a different package or the Universe scope
 		// (doing so would lead to a race condition - was issue #35049)
 		if t.obj.pkg != check.pkg {
@@ -338,7 +340,7 @@
 			// cycle detected
 			for i, tn := range path {
 				if t.obj.pkg != check.pkg {
-					panic("internal error: type cycle via package-external type")
+					panic("type cycle via package-external type")
 				}
 				if tn == t.obj {
 					check.cycleError(path[i:])
@@ -346,12 +348,9 @@
 					return t.info
 				}
 			}
-			panic("internal error: cycle start not found")
+			panic("cycle start not found")
 		}
 		return t.info
-
-	case *instance:
-		return check.validType(t.expand(), path)
 	}
 
 	return valid
@@ -515,75 +514,6 @@
 	check.initVars(lhs, []syntax.Expr{init}, nopos)
 }
 
-// under returns the expanded underlying type of n0; possibly by following
-// forward chains of named types. If an underlying type is found, resolve
-// the chain by setting the underlying type for each defined type in the
-// chain before returning it. If no underlying type is found or a cycle
-// is detected, the result is Typ[Invalid]. If a cycle is detected and
-// n0.check != nil, the cycle is reported.
-func (n0 *Named) under() Type {
-	u := n0.underlying
-	if u == nil {
-		return Typ[Invalid]
-	}
-
-	// If the underlying type of a defined type is not a defined
-	// type, then that is the desired underlying type.
-	n := asNamed(u)
-	if n == nil {
-		return u // common case
-	}
-
-	// Otherwise, follow the forward chain.
-	seen := map[*Named]int{n0: 0}
-	path := []Object{n0.obj}
-	for {
-		u = n.underlying
-		if u == nil {
-			u = Typ[Invalid]
-			break
-		}
-		n1 := asNamed(u)
-		if n1 == nil {
-			break // end of chain
-		}
-
-		seen[n] = len(seen)
-		path = append(path, n.obj)
-		n = n1
-
-		if i, ok := seen[n]; ok {
-			// cycle
-			// TODO(gri) revert this to a method on Checker. Having a possibly
-			// nil Checker on Named and TypeParam is too subtle.
-			if n0.check != nil {
-				n0.check.cycleError(path[i:])
-			}
-			u = Typ[Invalid]
-			break
-		}
-	}
-
-	for n := range seen {
-		// We should never have to update the underlying type of an imported type;
-		// those underlying types should have been resolved during the import.
-		// Also, doing so would lead to a race condition (was issue #31749).
-		// Do this check always, not just in debug more (it's cheap).
-		if n0.check != nil && n.obj.pkg != n0.check.pkg {
-			panic("internal error: imported type with unresolved underlying type")
-		}
-		n.underlying = u
-	}
-
-	return u
-}
-
-func (n *Named) setUnderlying(typ Type) {
-	if n != nil {
-		n.underlying = typ
-	}
-}
-
 func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named) {
 	assert(obj.typ == nil)
 
@@ -599,8 +529,8 @@
 		alias = false
 	}
 
+	// alias declaration
 	if alias {
-		// type alias declaration
 		if !check.allowVersion(check.pkg, 1, 9) {
 			if check.conf.CompilerErrorMessages {
 				check.error(tdecl, "type aliases only supported as of -lang=go1.9")
@@ -611,111 +541,94 @@
 
 		obj.typ = Typ[Invalid]
 		obj.typ = check.anyType(tdecl.Type)
-
-	} else {
-		// defined type declaration
-
-		named := check.newNamed(obj, nil, nil, nil, nil)
-		def.setUnderlying(named)
-
-		if tdecl.TParamList != nil {
-			check.openScope(tdecl, "type parameters")
-			defer check.closeScope()
-			named.tparams = check.collectTypeParams(tdecl.TParamList)
-		}
-
-		// determine underlying type of named
-		named.fromRHS = check.definedType(tdecl.Type, named)
-
-		// The underlying type of named may be itself a named type that is
-		// incomplete:
-		//
-		//	type (
-		//		A B
-		//		B *C
-		//		C A
-		//	)
-		//
-		// The type of C is the (named) type of A which is incomplete,
-		// and which has as its underlying type the named type B.
-		// Determine the (final, unnamed) underlying type by resolving
-		// any forward chain.
-		// TODO(gri) Investigate if we can just use named.fromRHS here
-		//           and rely on lazy computation of the underlying type.
-		named.underlying = under(named)
-	}
-
-}
-
-func (check *Checker) collectTypeParams(list []*syntax.Field) (tparams []*TypeName) {
-	// Type parameter lists should not be empty. The parser will
-	// complain but we still may get an incorrect AST: ignore it.
-	if len(list) == 0 {
 		return
 	}
 
-	// Declare type parameters up-front, with empty interface as type bound.
+	// type definition or generic type declaration
+	named := check.newNamed(obj, nil, nil, nil, nil)
+	def.setUnderlying(named)
+
+	if tdecl.TParamList != nil {
+		check.openScope(tdecl, "type parameters")
+		defer check.closeScope()
+		named.tparams = check.collectTypeParams(tdecl.TParamList)
+	}
+
+	// determine underlying type of named
+	named.fromRHS = check.definedType(tdecl.Type, named)
+	assert(named.fromRHS != nil)
+	// The underlying type of named may be itself a named type that is
+	// incomplete:
+	//
+	//	type (
+	//		A B
+	//		B *C
+	//		C A
+	//	)
+	//
+	// The type of C is the (named) type of A which is incomplete,
+	// and which has as its underlying type the named type B.
+	// Determine the (final, unnamed) underlying type by resolving
+	// any forward chain.
+	// TODO(gri) Investigate if we can just use named.fromRHS here
+	//           and rely on lazy computation of the underlying type.
+	named.underlying = under(named)
+
+	// If the RHS is a type parameter, it must be from this type declaration.
+	if tpar, _ := named.underlying.(*TypeParam); tpar != nil && tparamIndex(named.TParams().list(), tpar) < 0 {
+		check.errorf(tdecl.Type, "cannot use function type parameter %s as RHS in type declaration", tpar)
+		named.underlying = Typ[Invalid]
+	}
+}
+
+func (check *Checker) collectTypeParams(list []*syntax.Field) *TypeParams {
+	tparams := make([]*TypeName, len(list))
+
+	// Declare type parameters up-front.
 	// The scope of type parameters starts at the beginning of the type parameter
-	// list (so we can have mutually recursive parameterized interfaces).
-	for _, f := range list {
-		tparams = check.declareTypeParam(tparams, f.Name)
+	// list (so we can have mutually recursive parameterized type bounds).
+	for i, f := range list {
+		tparams[i] = check.declareTypeParam(f.Name)
 	}
 
 	var bound Type
-	for i, j := 0, 0; i < len(list); i = j {
-		f := list[i]
-
-		// determine the range of type parameters list[i:j] with identical type bound
-		// (declared as in (type a, b, c B))
-		j = i + 1
-		for j < len(list) && list[j].Type == f.Type {
-			j++
+	for i, f := range list {
+		// Optimization: Re-use the previous type bound if it hasn't changed.
+		// This also preserves the grouped output of type parameter lists
+		// when printing type strings.
+		if i == 0 || f.Type != list[i-1].Type {
+			bound = check.boundType(f.Type)
 		}
-
-		// this should never be the case, but be careful
-		if f.Type == nil {
-			continue
-		}
-
-		// The predeclared identifier "any" is visible only as a constraint
-		// in a type parameter list. Look for it before general constraint
-		// resolution.
-		if tident, _ := unparen(f.Type).(*syntax.Name); tident != nil && tident.Value == "any" && check.lookup("any") == nil {
-			bound = universeAny
-		} else {
-			bound = check.typ(f.Type)
-		}
-
-		// type bound must be an interface
-		// TODO(gri) We should delay the interface check because
-		//           we may not have a complete interface yet:
-		//           type C(type T C) interface {}
-		//           (issue #39724).
-		if _, ok := under(bound).(*Interface); ok {
-			// set the type bounds
-			for i < j {
-				tparams[i].typ.(*TypeParam).bound = bound
-				i++
-			}
-		} else if bound != Typ[Invalid] {
-			check.errorf(f.Type, "%s is not an interface", bound)
-		}
+		tparams[i].typ.(*TypeParam).bound = bound
 	}
 
-	return
+	return bindTParams(tparams)
 }
 
-func (check *Checker) declareTypeParam(tparams []*TypeName, name *syntax.Name) []*TypeName {
+func (check *Checker) declareTypeParam(name *syntax.Name) *TypeName {
 	tpar := NewTypeName(name.Pos(), check.pkg, name.Value, nil)
-	check.NewTypeParam(tpar, len(tparams), &emptyInterface) // assigns type to tpar as a side-effect
+	check.NewTypeParam(tpar, nil)                           // assigns type to tpar as a side-effect
 	check.declare(check.scope, name, tpar, check.scope.pos) // TODO(gri) check scope position
-	tparams = append(tparams, tpar)
+	return tpar
+}
 
-	if check.conf.Trace {
-		check.trace(name.Pos(), "type param = %v", tparams[len(tparams)-1])
+// boundType type-checks the type expression e and returns its type, or Typ[Invalid].
+// The type must be an interface, including the predeclared type "any".
+func (check *Checker) boundType(e syntax.Expr) Type {
+	// The predeclared identifier "any" is visible only as a type bound in a type parameter list.
+	// If we allow "any" for general use, this if-statement can be removed (issue #33232).
+	if name, _ := unparen(e).(*syntax.Name); name != nil && name.Value == "any" && check.lookup("any") == universeAny {
+		return universeAny.Type()
 	}
 
-	return tparams
+	bound := check.typ(e)
+	check.later(func() {
+		u := under(bound)
+		if _, ok := u.(*Interface); !ok && u != Typ[Invalid] {
+			check.errorf(e, "%s is not an interface", bound)
+		}
+	})
+	return bound
 }
 
 func (check *Checker) collectMethods(obj *TypeName) {
@@ -737,7 +650,7 @@
 	// and field names must be distinct."
 	base := asNamed(obj.typ) // shouldn't fail but be conservative
 	if base != nil {
-		if t, _ := base.underlying.(*Struct); t != nil {
+		if t, _ := base.Underlying().(*Struct); t != nil {
 			for _, fld := range t.fields {
 				if fld.name != "_" {
 					assert(mset.insert(fld) == nil)
@@ -779,6 +692,7 @@
 		}
 
 		if base != nil {
+			base.load() // TODO(mdempsky): Probably unnecessary.
 			base.methods = append(base.methods, m)
 		}
 	}
@@ -805,6 +719,10 @@
 	check.funcType(sig, fdecl.Recv, fdecl.TParamList, fdecl.Type)
 	obj.color_ = saved
 
+	if len(fdecl.TParamList) > 0 && fdecl.Body == nil {
+		check.softErrorf(fdecl, "parameterized function is missing function body")
+	}
+
 	// function body must be type-checked after global declarations
 	// (functions implemented elsewhere have no body)
 	if !check.conf.IgnoreFuncBodies && fdecl.Body != nil {
diff --git a/src/cmd/compile/internal/types2/errorcalls_test.go b/src/cmd/compile/internal/types2/errorcalls_test.go
index 28bb33a..80b05f9 100644
--- a/src/cmd/compile/internal/types2/errorcalls_test.go
+++ b/src/cmd/compile/internal/types2/errorcalls_test.go
@@ -18,7 +18,7 @@
 	}
 
 	for _, file := range files {
-		syntax.Walk(file, func(n syntax.Node) bool {
+		syntax.Crawl(file, func(n syntax.Node) bool {
 			call, _ := n.(*syntax.CallExpr)
 			if call == nil {
 				return false
diff --git a/src/cmd/compile/internal/types2/errors.go b/src/cmd/compile/internal/types2/errors.go
index af4ecb2..a682732 100644
--- a/src/cmd/compile/internal/types2/errors.go
+++ b/src/cmd/compile/internal/types2/errors.go
@@ -88,7 +88,7 @@
 		case nil:
 			arg = "<nil>"
 		case operand:
-			panic("internal error: should always pass *operand")
+			panic("got operand instead of *operand")
 		case *operand:
 			arg = operandString(a, qf)
 		case syntax.Pos:
@@ -111,7 +111,7 @@
 		if check.pkgPathMap == nil {
 			check.pkgPathMap = make(map[string]map[string]bool)
 			check.seenPkgMap = make(map[*Package]bool)
-			check.markImports(pkg)
+			check.markImports(check.pkg)
 		}
 		// If the same package name was used by multiple packages, display the full path.
 		if len(check.pkgPathMap[pkg.name]) > 1 {
@@ -148,7 +148,7 @@
 
 func (check *Checker) report(err *error_) {
 	if err.empty() {
-		panic("internal error: reporting no error")
+		panic("no error to report")
 	}
 	check.err(err.pos(), err.msg(check.qualifier), err.soft)
 }
diff --git a/src/cmd/compile/internal/types2/expr.go b/src/cmd/compile/internal/types2/expr.go
index 23b7965..3c2b10c 100644
--- a/src/cmd/compile/internal/types2/expr.go
+++ b/src/cmd/compile/internal/types2/expr.go
@@ -157,6 +157,14 @@
 	syntax.Shl: "shift",
 }
 
+func underIs(typ Type, f func(Type) bool) bool {
+	u := under(typ)
+	if tpar, _ := u.(*TypeParam); tpar != nil {
+		return tpar.underIs(f)
+	}
+	return f(u)
+}
+
 func (check *Checker) unary(x *operand, e *syntax.Operation) {
 	check.expr(x, e.X)
 	if x.mode == invalid {
@@ -177,19 +185,29 @@
 		return
 
 	case syntax.Recv:
-		typ := asChan(x.typ)
-		if typ == nil {
-			check.errorf(x, invalidOp+"cannot receive from non-channel %s", x)
-			x.mode = invalid
-			return
-		}
-		if typ.dir == SendOnly {
-			check.errorf(x, invalidOp+"cannot receive from send-only channel %s", x)
+		var elem Type
+		if !underIs(x.typ, func(u Type) bool {
+			ch, _ := u.(*Chan)
+			if ch == nil {
+				check.errorf(x, invalidOp+"cannot receive from non-channel %s", x)
+				return false
+			}
+			if ch.dir == SendOnly {
+				check.errorf(x, invalidOp+"cannot receive from send-only channel %s", x)
+				return false
+			}
+			if elem != nil && !Identical(ch.elem, elem) {
+				check.errorf(x, invalidOp+"channels of %s must have the same element type", x)
+				return false
+			}
+			elem = ch.elem
+			return true
+		}) {
 			x.mode = invalid
 			return
 		}
 		x.mode = commaok
-		x.typ = typ.elem
+		x.typ = elem
 		check.hasCallOrRecv = true
 		return
 	}
@@ -664,7 +682,6 @@
 // If x is a constant operand, the returned constant.Value will be the
 // representation of x in this context.
 func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, constant.Value, errorCode) {
-	target = expand(target)
 	if x.mode == invalid || isTyped(x.typ) || target == Typ[Invalid] {
 		return x.typ, nil, 0
 	}
@@ -691,7 +708,7 @@
 		return nil, nil, _InvalidUntypedConversion
 	}
 
-	switch t := optype(target).(type) {
+	switch t := under(target).(type) {
 	case *Basic:
 		if x.mode == constant_ {
 			v, code := check.representation(x, t)
@@ -723,8 +740,8 @@
 		default:
 			return nil, nil, _InvalidUntypedConversion
 		}
-	case *Sum:
-		ok := t.is(func(t Type) bool {
+	case *TypeParam:
+		ok := t.underIs(func(t Type) bool {
 			target, _, _ := check.implicitTypeAndValue(x, t)
 			return target != nil
 		})
@@ -735,7 +752,6 @@
 		// Update operand types to the default type rather than the target
 		// (interface) type: values must have concrete dynamic types.
 		// Untyped nil was handled upfront.
-		check.completeInterface(nopos, t)
 		if !t.Empty() {
 			return nil, nil, _InvalidUntypedConversion // cannot assign untyped values to non-empty interfaces
 		}
@@ -972,14 +988,28 @@
 		return
 	}
 
-	check.convertUntyped(x, y.typ)
-	if x.mode == invalid {
-		return
+	canMix := func(x, y *operand) bool {
+		if IsInterface(x.typ) || IsInterface(y.typ) {
+			return true
+		}
+		if isBoolean(x.typ) != isBoolean(y.typ) {
+			return false
+		}
+		if isString(x.typ) != isString(y.typ) {
+			return false
+		}
+		return true
 	}
-	check.convertUntyped(&y, x.typ)
-	if y.mode == invalid {
-		x.mode = invalid
-		return
+	if canMix(x, &y) {
+		check.convertUntyped(x, y.typ)
+		if x.mode == invalid {
+			return
+		}
+		check.convertUntyped(&y, x.typ)
+		if y.mode == invalid {
+			x.mode = invalid
+			return
+		}
 	}
 
 	if isComparison(op) {
@@ -987,7 +1017,7 @@
 		return
 	}
 
-	if !check.identical(x.typ, y.typ) {
+	if !Identical(x.typ, y.typ) {
 		// only report an error if we have valid types
 		// (otherwise we had an error reported elsewhere already)
 		if x.typ != Typ[Invalid] && y.typ != Typ[Invalid] {
@@ -1184,7 +1214,7 @@
 			goto Error
 		}
 
-		switch utyp := optype(base).(type) {
+		switch utyp := under(base).(type) {
 		case *Struct:
 			if len(e.ElemList) == 0 {
 				break
@@ -1316,7 +1346,7 @@
 					xkey := keyVal(x.val)
 					if asInterface(utyp.key) != nil {
 						for _, vtyp := range visited[xkey] {
-							if check.identical(vtyp, x.typ) {
+							if Identical(vtyp, x.typ) {
 								duplicate = true
 								break
 							}
@@ -1448,13 +1478,24 @@
 				case typexpr:
 					x.typ = &Pointer{base: x.typ}
 				default:
-					if typ := asPointer(x.typ); typ != nil {
-						x.mode = variable
-						x.typ = typ.base
-					} else {
-						check.errorf(x, invalidOp+"cannot indirect %s", x)
+					var base Type
+					if !underIs(x.typ, func(u Type) bool {
+						p, _ := u.(*Pointer)
+						if p == nil {
+							check.errorf(x, invalidOp+"cannot indirect %s", x)
+							return false
+						}
+						if base != nil && !Identical(p.base, base) {
+							check.errorf(x, invalidOp+"pointers of %s must have identical base types", x)
+							return false
+						}
+						base = p.base
+						return true
+					}) {
 						goto Error
 					}
+					x.mode = variable
+					x.typ = base
 				}
 				break
 			}
@@ -1537,7 +1578,7 @@
 	}
 	var msg string
 	if wrongType != nil {
-		if check.identical(method.typ, wrongType.typ) {
+		if Identical(method.typ, wrongType.typ) {
 			msg = fmt.Sprintf("missing method %s (%s has pointer receiver)", method.name, method.name)
 		} else {
 			msg = fmt.Sprintf("wrong type for method %s (have %s, want %s)", method.name, wrongType.typ, method.typ)
diff --git a/src/cmd/compile/internal/types2/index.go b/src/cmd/compile/internal/types2/index.go
index c94017a..e8755a1 100644
--- a/src/cmd/compile/internal/types2/index.go
+++ b/src/cmd/compile/internal/types2/index.go
@@ -32,7 +32,7 @@
 		return false
 
 	case value:
-		if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
+		if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
 			// function instantiation
 			return true
 		}
@@ -41,7 +41,7 @@
 	// ordinary index expression
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch typ := optype(x.typ).(type) {
+	switch typ := under(x.typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			valid = true
@@ -80,7 +80,7 @@
 		index := check.singleIndex(e)
 		if index == nil {
 			x.mode = invalid
-			return
+			return false
 		}
 		var key operand
 		check.expr(&key, index)
@@ -89,87 +89,80 @@
 		x.mode = mapindex
 		x.typ = typ.elem
 		x.expr = e
-		return
+		return false
 
-	case *Sum:
-		// A sum type can be indexed if all of the sum's types
-		// support indexing and have the same index and element
-		// type. Special rules apply for maps in the sum type.
-		var tkey, telem Type // key is for map types only
-		nmaps := 0           // number of map types in sum type
-		if typ.is(func(t Type) bool {
-			var e Type
-			switch t := under(t).(type) {
+	case *TypeParam:
+		// TODO(gri) report detailed failure cause for better error messages
+		var tkey, telem Type // tkey != nil if we have maps
+		if typ.underIs(func(u Type) bool {
+			var key, elem Type
+			alen := int64(-1) // valid if >= 0
+			switch t := u.(type) {
 			case *Basic:
-				if isString(t) {
-					e = universeByte
-				}
-			case *Array:
-				e = t.elem
-			case *Pointer:
-				if t := asArray(t.base); t != nil {
-					e = t.elem
-				}
-			case *Slice:
-				e = t.elem
-			case *Map:
-				// If there are multiple maps in the sum type,
-				// they must have identical key types.
-				// TODO(gri) We may be able to relax this rule
-				// but it becomes complicated very quickly.
-				if tkey != nil && !Identical(t.key, tkey) {
+				if !isString(t) {
 					return false
 				}
-				tkey = t.key
-				e = t.elem
-				nmaps++
-			case *TypeParam:
-				check.errorf(x, "type of %s contains a type parameter - cannot index (implementation restriction)", x)
-			case *instance:
-				panic("unimplemented")
-			}
-			if e == nil || telem != nil && !Identical(e, telem) {
+				elem = universeByte
+			case *Array:
+				elem = t.elem
+				alen = t.len
+			case *Pointer:
+				a, _ := under(t.base).(*Array)
+				if a == nil {
+					return false
+				}
+				elem = a.elem
+				alen = a.len
+			case *Slice:
+				elem = t.elem
+			case *Map:
+				key = t.key
+				elem = t.elem
+			default:
 				return false
 			}
-			telem = e
+			assert(elem != nil)
+			if telem == nil {
+				// first type
+				tkey, telem = key, elem
+				length = alen
+			} else {
+				// all map keys must be identical (incl. all nil)
+				if !Identical(key, tkey) {
+					return false
+				}
+				// all element types must be identical
+				if !Identical(elem, telem) {
+					return false
+				}
+				tkey, telem = key, elem
+				// track the minimal length for arrays
+				if alen >= 0 && alen < length {
+					length = alen
+				}
+			}
 			return true
 		}) {
-			// If there are maps, the index expression must be assignable
-			// to the map key type (as for simple map index expressions).
-			if nmaps > 0 {
+			// For maps, the index expression must be assignable to the map key type.
+			if tkey != nil {
 				index := check.singleIndex(e)
 				if index == nil {
 					x.mode = invalid
-					return
+					return false
 				}
 				var key operand
 				check.expr(&key, index)
 				check.assignment(&key, tkey, "map index")
 				// ok to continue even if indexing failed - map element type is known
-
-				// If there are only maps, we are done.
-				if nmaps == len(typ.types) {
-					x.mode = mapindex
-					x.typ = telem
-					x.expr = e
-					return
-				}
-
-				// Otherwise we have mix of maps and other types. For
-				// now we require that the map key be an integer type.
-				// TODO(gri) This is probably not good enough.
-				valid = isInteger(tkey)
-				// avoid 2nd indexing error if indexing failed above
-				if !valid && key.mode == invalid {
-					x.mode = invalid
-					return
-				}
-				x.mode = value // map index expressions are not addressable
-			} else {
-				// no maps
-				valid = true
-				x.mode = variable
+				x.mode = mapindex
+				x.typ = telem
+				x.expr = e
+				return false
 			}
+
+			// no maps
+			valid = true
+			x.mode = variable
 			x.typ = telem
 		}
 	}
@@ -177,13 +170,13 @@
 	if !valid {
 		check.errorf(x, invalidOp+"cannot index %s", x)
 		x.mode = invalid
-		return
+		return false
 	}
 
 	index := check.singleIndex(e)
 	if index == nil {
 		x.mode = invalid
-		return
+		return false
 	}
 
 	// In pathological (invalid) cases (e.g.: type T1 [][[]T1{}[0][0]]T0)
@@ -206,7 +199,7 @@
 
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch typ := optype(x.typ).(type) {
+	switch typ := under(x.typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			if e.Full {
@@ -246,7 +239,7 @@
 		valid = true
 		// x.typ doesn't change
 
-	case *Sum, *TypeParam:
+	case *TypeParam:
 		check.error(x, "generic slice expressions not yet implemented")
 		x.mode = invalid
 		return
diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index f37d7f6..ff4bb3e 100644
--- a/src/cmd/compile/internal/types2/infer.go
+++ b/src/cmd/compile/internal/types2/infer.go
@@ -83,7 +83,7 @@
 
 	// Substitute type arguments for their respective type parameters in params,
 	// if any. Note that nil targs entries are ignored by check.subst.
-	// TODO(gri) Can we avoid this (we're setting known type argumemts below,
+	// TODO(gri) Can we avoid this (we're setting known type arguments below,
 	//           but that doesn't impact the isParameterized check for now).
 	if params.Len() > 0 {
 		smap := makeSubstMap(tparams, targs)
@@ -94,7 +94,7 @@
 	// Unify parameter and argument types for generic parameters with typed arguments
 	// and collect the indices of generic parameters with untyped arguments.
 	// Terminology: generic parameter = function parameter with a type-parameterized type
-	u := newUnifier(check, false)
+	u := newUnifier(false)
 	u.x.init(tparams)
 
 	// Set the type arguments which we know already.
@@ -280,7 +280,7 @@
 	}()
 
 	switch t := typ.(type) {
-	case nil, *Basic: // TODO(gri) should nil be handled here?
+	case nil, *top, *Basic: // TODO(gri) should nil be handled here?
 		break
 
 	case *Array:
@@ -307,9 +307,6 @@
 			}
 		}
 
-	case *Sum:
-		return w.isParameterizedList(t.types)
-
 	case *Signature:
 		// t.tparams may not be nil if we are looking at a signature
 		// of a generic function type (or an interface method) that is
@@ -321,24 +318,15 @@
 		return w.isParameterized(t.params) || w.isParameterized(t.results)
 
 	case *Interface:
-		if t.allMethods != nil {
-			// interface is complete - quick test
-			for _, m := range t.allMethods {
-				if w.isParameterized(m.typ) {
-					return true
-				}
+		tset := t.typeSet()
+		for _, m := range tset.methods {
+			if w.isParameterized(m.typ) {
+				return true
 			}
-			return w.isParameterizedList(unpack(t.allTypes))
 		}
-
-		return t.iterate(func(t *Interface) bool {
-			for _, m := range t.methods {
-				if w.isParameterized(m.typ) {
-					return true
-				}
-			}
-			return w.isParameterizedList(unpack(t.types))
-		}, nil)
+		return tset.is(func(t *term) bool {
+			return w.isParameterized(t.typ)
+		})
 
 	case *Map:
 		return w.isParameterized(t.key) || w.isParameterized(t.elem)
@@ -347,15 +335,12 @@
 		return w.isParameterized(t.elem)
 
 	case *Named:
-		return w.isParameterizedList(t.targs)
+		return w.isParameterizedTypeList(t.targs)
 
 	case *TypeParam:
 		// t must be one of w.tparams
 		return t.index < len(w.tparams) && w.tparams[t.index].typ == t
 
-	case *instance:
-		return w.isParameterizedList(t.targs)
-
 	default:
 		unreachable()
 	}
@@ -363,7 +348,7 @@
 	return false
 }
 
-func (w *tpWalker) isParameterizedList(list []Type) bool {
+func (w *tpWalker) isParameterizedTypeList(list []Type) bool {
 	for _, t := range list {
 		if w.isParameterized(t) {
 			return true
@@ -385,7 +370,7 @@
 
 	// Setup bidirectional unification between those structural bounds
 	// and the corresponding type arguments (which may be nil!).
-	u := newUnifier(check, false)
+	u := newUnifier(false)
 	u.x.init(tparams)
 	u.y = u.x // type parameters between LHS and RHS of unification are identical
 
@@ -399,7 +384,7 @@
 	// Unify type parameters with their structural constraints, if any.
 	for _, tpar := range tparams {
 		typ := tpar.typ.(*TypeParam)
-		sbound := check.structuralType(typ.bound)
+		sbound := typ.structuralType()
 		if sbound != nil {
 			if !u.unify(typ, sbound) {
 				if report {
@@ -412,8 +397,8 @@
 
 	// u.x.types() now contains the incoming type arguments plus any additional type
 	// arguments for which there were structural constraints. The newly inferred non-
-	// nil entries may still contain references to other type parameters. For instance,
-	// for [A any, B interface{type []C}, C interface{type *A}], if A == int
+	// nil entries may still contain references to other type parameters.
+	// For instance, for [A any, B interface{ []C }, C interface{ *A }], if A == int
 	// was given, unification produced the type list [int, []C, *A]. We eliminate the
 	// remaining type parameters by substituting the type parameters in this type list
 	// until nothing changes anymore.
@@ -472,16 +457,3 @@
 
 	return
 }
-
-// structuralType returns the structural type of a constraint, if any.
-func (check *Checker) structuralType(constraint Type) Type {
-	if iface, _ := under(constraint).(*Interface); iface != nil {
-		check.completeInterface(nopos, iface)
-		types := unpack(iface.allTypes)
-		if len(types) == 1 {
-			return types[0]
-		}
-		return nil
-	}
-	return constraint
-}
diff --git a/src/cmd/compile/internal/types2/instantiate.go b/src/cmd/compile/internal/types2/instantiate.go
index 0df52e8..0bb4ac9 100644
--- a/src/cmd/compile/internal/types2/instantiate.go
+++ b/src/cmd/compile/internal/types2/instantiate.go
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// This file implements instantiation of generic types
+// through substitution of type parameters by type arguments.
+
 package types2
 
 import (
@@ -9,23 +12,26 @@
 	"fmt"
 )
 
-// Instantiate instantiates the type typ with the given type arguments.
-// typ must be a *Named or a *Signature type, it must be generic, and
-// its number of type parameters must match the number of provided type
-// arguments. The result is a new, instantiated (not generic) type of
-// the same kind (either a *Named or a *Signature). The type arguments
-// are not checked against the constraints of the type parameters.
+// Instantiate instantiates the type typ with the given type arguments
+// targs. To check type constraint satisfaction, verify must be set.
+// pos and posList correspond to the instantiation and type argument
+// positions respectively; posList may be nil or shorter than the number
+// of type arguments provided.
+// typ must be a *Named or a *Signature type, and its number of type
+// parameters must match the number of provided type arguments.
+// The receiver (check) may be nil if and only if verify is not set.
+// The result is a new, instantiated (not generic) type of the same kind
+// (either a *Named or a *Signature).
 // Any methods attached to a *Named are simply copied; they are not
 // instantiated.
-func Instantiate(pos syntax.Pos, typ Type, targs []Type) (res Type) {
-	// TODO(gri) This code is basically identical to the prolog
-	//           in Checker.instantiate. Factor.
+func (check *Checker) Instantiate(pos syntax.Pos, typ Type, targs []Type, posList []syntax.Pos, verify bool) (res Type) {
+	// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
 	var tparams []*TypeName
 	switch t := typ.(type) {
 	case *Named:
-		tparams = t.tparams
+		tparams = t.TParams().list()
 	case *Signature:
-		tparams = t.tparams
+		tparams = t.TParams().list()
 		defer func() {
 			// If we had an unexpected failure somewhere don't panic below when
 			// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
@@ -44,20 +50,194 @@
 			// anymore; we need to set tparams to nil.
 			res.(*Signature).tparams = nil
 		}()
-
 	default:
+		// only types and functions can be generic
 		panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
 	}
 
+	inst := check.instantiate(pos, typ, tparams, targs, posList)
+	if verify && len(tparams) == len(targs) {
+		check.verify(pos, tparams, targs, posList)
+	}
+	return inst
+}
+
+func (check *Checker) instantiate(pos syntax.Pos, typ Type, tparams []*TypeName, targs []Type, posList []syntax.Pos) (res Type) {
 	// the number of supplied types must match the number of type parameters
 	if len(targs) != len(tparams) {
+		// TODO(gri) provide better error message
+		if check != nil {
+			check.errorf(pos, "got %d arguments but %d type parameters", len(targs), len(tparams))
+			return Typ[Invalid]
+		}
 		panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, len(targs), len(tparams)))
 	}
 
+	if check != nil && check.conf.Trace {
+		check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
+		check.indent++
+		defer func() {
+			check.indent--
+			var under Type
+			if res != nil {
+				// Calling under() here may lead to endless instantiations.
+				// Test case: type T[P any] T[P]
+				// TODO(gri) investigate if that's a bug or to be expected.
+				under = res.Underlying()
+			}
+			check.trace(pos, "=> %s (under = %s)", res, under)
+		}()
+	}
+
+	assert(len(posList) <= len(targs))
+
 	if len(tparams) == 0 {
 		return typ // nothing to do (minor optimization)
 	}
 
+	return check.subst(pos, typ, makeSubstMap(tparams, targs))
+}
+
+// InstantiateLazy is like Instantiate, but avoids actually
+// instantiating the type until needed. typ must be a *Named
+// type.
+func (check *Checker) InstantiateLazy(pos syntax.Pos, typ Type, targs []Type, posList []syntax.Pos, verify bool) Type {
+	// Don't use asNamed here: we don't want to expand the base during lazy
+	// instantiation.
+	base := typ.(*Named)
+	if base == nil {
+		panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
+	}
+
+	if verify && base.TParams().Len() == len(targs) {
+		check.later(func() {
+			check.verify(pos, base.tparams.list(), targs, posList)
+		})
+	}
+
+	h := instantiatedHash(base, targs)
+	if check != nil {
+		// typ may already have been instantiated with identical type arguments. In
+		// that case, re-use the existing instance.
+		if named := check.typMap[h]; named != nil {
+			return named
+		}
+	}
+
+	tname := NewTypeName(pos, base.obj.pkg, base.obj.name, nil)
+	named := check.newNamed(tname, base, nil, nil, nil) // methods and tparams are set when named is loaded
+	named.targs = targs
+	named.instance = &instance{pos, posList}
+	if check != nil {
+		check.typMap[h] = named
+	}
+
+	return named
+}
+
+func (check *Checker) verify(pos syntax.Pos, tparams []*TypeName, targs []Type, posList []syntax.Pos) {
+	if check == nil {
+		panic("cannot have nil Checker if verifying constraints")
+	}
+
 	smap := makeSubstMap(tparams, targs)
-	return (*Checker)(nil).subst(pos, typ, smap)
+	for i, tname := range tparams {
+		// best position for error reporting
+		pos := pos
+		if i < len(posList) {
+			pos = posList[i]
+		}
+
+		// stop checking bounds after the first failure
+		if !check.satisfies(pos, targs[i], tname.typ.(*TypeParam), smap) {
+			break
+		}
+	}
+}
+
+// satisfies reports whether the type argument targ satisfies the constraint of type parameter
+// parameter tpar (after any of its type parameters have been substituted through smap).
+// A suitable error is reported if the result is false.
+// TODO(gri) This should be a method of interfaces or type sets.
+func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap *substMap) bool {
+	iface := tpar.iface()
+	if iface.Empty() {
+		return true // no type bound
+	}
+
+	// The type parameter bound is parameterized with the same type parameters
+	// as the instantiated type; before we can use it for bounds checking we
+	// need to instantiate it with the type arguments with which we instantiate
+	// the parameterized type.
+	iface = check.subst(pos, iface, smap).(*Interface)
+
+	// if iface is comparable, targ must be comparable
+	// TODO(gri) the error messages needs to be better, here
+	if iface.IsComparable() && !Comparable(targ) {
+		if tpar := asTypeParam(targ); tpar != nil && tpar.iface().typeSet().IsAll() {
+			check.softErrorf(pos, "%s has no constraints", targ)
+			return false
+		}
+		check.softErrorf(pos, "%s does not satisfy comparable", targ)
+		return false
+	}
+
+	// targ must implement iface (methods)
+	// - check only if we have methods
+	if iface.NumMethods() > 0 {
+		// If the type argument is a pointer to a type parameter, the type argument's
+		// method set is empty.
+		// TODO(gri) is this what we want? (spec question)
+		if base, isPtr := deref(targ); isPtr && asTypeParam(base) != nil {
+			check.errorf(pos, "%s has no methods", targ)
+			return false
+		}
+		if m, wrong := check.missingMethod(targ, iface, true); m != nil {
+			// TODO(gri) needs to print updated name to avoid major confusion in error message!
+			//           (print warning for now)
+			// Old warning:
+			// check.softErrorf(pos, "%s does not satisfy %s (warning: name not updated) = %s (missing method %s)", targ, tpar.bound, iface, m)
+			if wrong != nil {
+				// TODO(gri) This can still report uninstantiated types which makes the error message
+				//           more difficult to read then necessary.
+				check.softErrorf(pos,
+					"%s does not satisfy %s: wrong method signature\n\tgot  %s\n\twant %s",
+					targ, tpar.bound, wrong, m,
+				)
+			} else {
+				check.softErrorf(pos, "%s does not satisfy %s (missing method %s)", targ, tpar.bound, m.name)
+			}
+			return false
+		}
+	}
+
+	// targ's underlying type must also be one of the interface types listed, if any
+	if !iface.typeSet().hasTerms() {
+		return true // nothing to do
+	}
+
+	// If targ is itself a type parameter, each of its possible types, but at least one, must be in the
+	// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
+	if targ := asTypeParam(targ); targ != nil {
+		targBound := targ.iface()
+		if !targBound.typeSet().hasTerms() {
+			check.softErrorf(pos, "%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
+			return false
+		}
+		if !targBound.typeSet().subsetOf(iface.typeSet()) {
+			// TODO(gri) need better error message
+			check.softErrorf(pos, "%s does not satisfy %s", targ, tpar.bound)
+			return false
+		}
+		return true
+	}
+
+	// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
+	if !iface.typeSet().includes(targ) {
+		// TODO(gri) better error message
+		check.softErrorf(pos, "%s does not satisfy %s", targ, tpar.bound)
+		return false
+	}
+
+	return true
 }
diff --git a/src/cmd/compile/internal/types2/interface.go b/src/cmd/compile/internal/types2/interface.go
new file mode 100644
index 0000000..2617f74
--- /dev/null
+++ b/src/cmd/compile/internal/types2/interface.go
@@ -0,0 +1,226 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "cmd/compile/internal/syntax"
+
+// ----------------------------------------------------------------------------
+// API
+
+// An Interface represents an interface type.
+type Interface struct {
+	obj       *TypeName     // corresponding declared object; or nil (for better error messages)
+	methods   []*Func       // ordered list of explicitly declared methods
+	embeddeds []Type        // ordered list of explicitly embedded elements
+	embedPos  *[]syntax.Pos // positions of embedded elements; or nil (for error messages) - use pointer to save space
+	complete  bool          // indicates that all fields (except for tset) are set up
+
+	tset *TypeSet // type set described by this interface, computed lazily
+}
+
+// typeSet returns the type set for interface t.
+func (t *Interface) typeSet() *TypeSet { return computeInterfaceTypeSet(nil, nopos, t) }
+
+// emptyInterface represents the empty interface
+var emptyInterface = Interface{complete: true, tset: &topTypeSet}
+
+// NewInterface returns a new interface for the given methods and embedded types.
+// NewInterface takes ownership of the provided methods and may modify their types
+// by setting missing receivers.
+//
+// Deprecated: Use NewInterfaceType instead which allows arbitrary embedded types.
+func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
+	tnames := make([]Type, len(embeddeds))
+	for i, t := range embeddeds {
+		tnames[i] = t
+	}
+	return NewInterfaceType(methods, tnames)
+}
+
+// NewInterfaceType returns a new interface for the given methods and embedded types.
+// NewInterfaceType takes ownership of the provided methods and may modify their types
+// by setting missing receivers.
+func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
+	if len(methods) == 0 && len(embeddeds) == 0 {
+		return &emptyInterface
+	}
+
+	// set method receivers if necessary
+	typ := new(Interface)
+	for _, m := range methods {
+		if sig := m.typ.(*Signature); sig.recv == nil {
+			sig.recv = NewVar(m.pos, m.pkg, "", typ)
+		}
+	}
+
+	// sort for API stability
+	sortMethods(methods)
+
+	typ.methods = methods
+	typ.embeddeds = embeddeds
+	typ.complete = true
+
+	return typ
+}
+
+// NumExplicitMethods returns the number of explicitly declared methods of interface t.
+func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
+
+// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
+
+// NumEmbeddeds returns the number of embedded types in interface t.
+func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
+
+// Embedded returns the i'th embedded defined (*Named) type of interface t for 0 <= i < t.NumEmbeddeds().
+// The result is nil if the i'th embedded type is not a defined type.
+//
+// Deprecated: Use EmbeddedType which is not restricted to defined (*Named) types.
+func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named); return tname }
+
+// EmbeddedType returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
+func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
+
+// NumMethods returns the total number of methods of interface t.
+func (t *Interface) NumMethods() int { return t.typeSet().NumMethods() }
+
+// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) Method(i int) *Func { return t.typeSet().Method(i) }
+
+// Empty reports whether t is the empty interface.
+func (t *Interface) Empty() bool { return t.typeSet().IsAll() }
+
+// IsComparable reports whether each type in interface t's type set is comparable.
+func (t *Interface) IsComparable() bool { return t.typeSet().IsComparable() }
+
+// IsConstraint reports whether interface t is not just a method set.
+func (t *Interface) IsConstraint() bool { return !t.typeSet().IsMethodSet() }
+
+func (t *Interface) Underlying() Type { return t }
+func (t *Interface) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (check *Checker) interfaceType(ityp *Interface, iface *syntax.InterfaceType, def *Named) {
+	var tlist []syntax.Expr // types collected from all type lists
+	var tname *syntax.Name  // most recent "type" name
+
+	addEmbedded := func(pos syntax.Pos, typ Type) {
+		ityp.embeddeds = append(ityp.embeddeds, typ)
+		if ityp.embedPos == nil {
+			ityp.embedPos = new([]syntax.Pos)
+		}
+		*ityp.embedPos = append(*ityp.embedPos, pos)
+	}
+
+	for _, f := range iface.MethodList {
+		if f.Name == nil {
+			// We have an embedded type; possibly a union of types.
+			addEmbedded(posFor(f.Type), parseUnion(check, flattenUnion(nil, f.Type)))
+			continue
+		}
+		// f.Name != nil
+
+		// We have a method with name f.Name, or a type of a type list (f.Name.Value == "type").
+		name := f.Name.Value
+		if name == "_" {
+			if check.conf.CompilerErrorMessages {
+				check.error(f.Name, "methods must have a unique non-blank name")
+			} else {
+				check.error(f.Name, "invalid method name _")
+			}
+			continue // ignore
+		}
+
+		// TODO(gri) Remove type list handling once the parser doesn't accept type lists anymore.
+		if name == "type" {
+			// Report an error for the first type list per interface
+			// if we don't allow type lists, but continue.
+			if !check.conf.AllowTypeLists && tlist == nil {
+				check.softErrorf(f.Name, "use generalized embedding syntax instead of a type list")
+			}
+			// For now, collect all type list entries as if it
+			// were a single union, where each union element is
+			// of the form ~T.
+			op := new(syntax.Operation)
+			// We should also set the position (but there is no setter);
+			// we don't care because this code will eventually go away.
+			op.Op = syntax.Tilde
+			op.X = f.Type
+			tlist = append(tlist, op)
+			// Report an error if we have multiple type lists in an
+			// interface, but only if they are permitted in the first place.
+			if check.conf.AllowTypeLists && tname != nil && tname != f.Name {
+				check.error(f.Name, "cannot have multiple type lists in an interface")
+			}
+			tname = f.Name
+			continue
+		}
+
+		typ := check.typ(f.Type)
+		sig, _ := typ.(*Signature)
+		if sig == nil {
+			if typ != Typ[Invalid] {
+				check.errorf(f.Type, invalidAST+"%s is not a method signature", typ)
+			}
+			continue // ignore
+		}
+
+		// Always type-check method type parameters but complain if they are not enabled.
+		// (This extra check is needed here because interface method signatures don't have
+		// a receiver specification.)
+		if sig.tparams != nil && !acceptMethodTypeParams {
+			check.error(f.Type, "methods cannot have type parameters")
+		}
+
+		// use named receiver type if available (for better error messages)
+		var recvTyp Type = ityp
+		if def != nil {
+			recvTyp = def
+		}
+		sig.recv = NewVar(f.Name.Pos(), check.pkg, "", recvTyp)
+
+		m := NewFunc(f.Name.Pos(), check.pkg, name, sig)
+		check.recordDef(f.Name, m)
+		ityp.methods = append(ityp.methods, m)
+	}
+
+	// If we saw a type list, add it like an embedded union.
+	if tlist != nil {
+		// Types T in a type list are added as ~T expressions but we don't
+		// have the position of the '~'. Use the first type position instead.
+		addEmbedded(tlist[0].(*syntax.Operation).X.Pos(), parseUnion(check, tlist))
+	}
+
+	// All methods and embedded elements for this interface are collected;
+	// i.e., this interface is may be used in a type set computation.
+	ityp.complete = true
+
+	if len(ityp.methods) == 0 && len(ityp.embeddeds) == 0 {
+		// empty interface
+		ityp.tset = &topTypeSet
+		return
+	}
+
+	// sort for API stability
+	// (don't sort embeddeds: they must correspond to *embedPos entries)
+	sortMethods(ityp.methods)
+
+	// Compute type set with a non-nil *Checker as soon as possible
+	// to report any errors. Subsequent uses of type sets will use
+	// this computed type set and won't need to pass in a *Checker.
+	check.later(func() { computeInterfaceTypeSet(check, iface.Pos(), ityp) })
+}
+
+func flattenUnion(list []syntax.Expr, x syntax.Expr) []syntax.Expr {
+	if o, _ := x.(*syntax.Operation); o != nil && o.Op == syntax.Or {
+		list = flattenUnion(list, o.X)
+		x = o.Y
+	}
+	return append(list, x)
+}
diff --git a/src/cmd/compile/internal/types2/issues_test.go b/src/cmd/compile/internal/types2/issues_test.go
index e716a48..9890b79 100644
--- a/src/cmd/compile/internal/types2/issues_test.go
+++ b/src/cmd/compile/internal/types2/issues_test.go
@@ -321,7 +321,7 @@
 			}
 		}
 
-		syntax.Walk(f, func(n syntax.Node) bool {
+		syntax.Crawl(f, func(n syntax.Node) bool {
 			if decl, _ := n.(*syntax.TypeDecl); decl != nil {
 				if tv, ok := info.Types[decl.Type]; ok && decl.Name.Value == "T" {
 					want := strings.Count(src, ";") + 1
@@ -402,8 +402,9 @@
 	// create type interface { error }
 	et := Universe.Lookup("error").Type()
 	it := NewInterfaceType(nil, []Type{et})
-	it.Complete()
 	// verify that after completing the interface, the embedded method remains unchanged
+	// (interfaces are "completed" lazily now, so the completion happens implicitly when
+	// accessing Method(0))
 	want := et.Underlying().(*Interface).Method(0)
 	got := it.Method(0)
 	if got != want {
diff --git a/src/cmd/compile/internal/types2/labels.go b/src/cmd/compile/internal/types2/labels.go
index d320698..6f02e2f 100644
--- a/src/cmd/compile/internal/types2/labels.go
+++ b/src/cmd/compile/internal/types2/labels.go
@@ -32,7 +32,8 @@
 	}
 
 	// spec: "It is illegal to define a label that is never used."
-	for _, obj := range all.elems {
+	for name, obj := range all.elems {
+		obj = resolve(name, obj)
 		if lbl := obj.(*Label); !lbl.used {
 			check.softErrorf(lbl.pos, "label %s declared but not used", lbl.name)
 		}
diff --git a/src/cmd/compile/internal/types2/lookup.go b/src/cmd/compile/internal/types2/lookup.go
index 7829950..0363008 100644
--- a/src/cmd/compile/internal/types2/lookup.go
+++ b/src/cmd/compile/internal/types2/lookup.go
@@ -6,6 +6,11 @@
 
 package types2
 
+// Internal use of LookupFieldOrMethod: If the obj result is a method
+// associated with a concrete (non-interface) type, the method's signature
+// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
+// the method's type.
+
 // LookupFieldOrMethod looks up a field or method with given package and name
 // in T and returns the corresponding *Var or *Func, an index sequence, and a
 // bool indicating if there were any pointer indirections on the path to the
@@ -33,19 +38,6 @@
 //	the method's formal receiver base type, nor was the receiver addressable.
 //
 func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
-	return (*Checker)(nil).lookupFieldOrMethod(T, addressable, pkg, name)
-}
-
-// Internal use of Checker.lookupFieldOrMethod: If the obj result is a method
-// associated with a concrete (non-interface) type, the method's signature
-// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
-// the method's type.
-// TODO(gri) Now that we provide the *Checker, we can probably remove this
-// caveat by calling Checker.objDecl from lookupFieldOrMethod. Investigate.
-
-// lookupFieldOrMethod is like the external version but completes interfaces
-// as necessary.
-func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// Methods cannot be associated to a named pointer type
 	// (spec: "The type denoted by T is called the receiver base type;
 	// it must not be a pointer or interface type and it must be declared
@@ -54,8 +46,8 @@
 	// pointer type but discard the result if it is a method since we would
 	// not have found it for T (see also issue 8590).
 	if t := asNamed(T); t != nil {
-		if p, _ := t.underlying.(*Pointer); p != nil {
-			obj, index, indirect = check.rawLookupFieldOrMethod(p, false, pkg, name)
+		if p, _ := t.Underlying().(*Pointer); p != nil {
+			obj, index, indirect = lookupFieldOrMethod(p, false, pkg, name)
 			if _, ok := obj.(*Func); ok {
 				return nil, nil, false
 			}
@@ -63,7 +55,7 @@
 		}
 	}
 
-	return check.rawLookupFieldOrMethod(T, addressable, pkg, name)
+	return lookupFieldOrMethod(T, addressable, pkg, name)
 }
 
 // TODO(gri) The named type consolidation and seen maps below must be
@@ -71,10 +63,9 @@
 //           types always have only one representation (even when imported
 //           indirectly via different packages.)
 
-// rawLookupFieldOrMethod should only be called by lookupFieldOrMethod and missingMethod.
-func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
+// lookupFieldOrMethod should only be called by LookupFieldOrMethod and missingMethod.
+func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// WARNING: The code in this function is extremely subtle - do not modify casually!
-	//          This function and NewMethodSet should be kept in sync.
 
 	if name == "_" {
 		return // blank fields/methods are never found
@@ -82,10 +73,12 @@
 
 	typ, isPtr := deref(T)
 
-	// *typ where typ is an interface has no methods.
-	// Be cautious: typ may be nil (issue 39634, crash #3).
-	if typ == nil || isPtr && IsInterface(typ) {
-		return
+	// *typ where typ is an interface or type parameter has no methods.
+	switch under(typ).(type) {
+	case *Interface, *TypeParam:
+		if isPtr {
+			return
+		}
 	}
 
 	// Start with typ as single entry at shallowest depth.
@@ -126,6 +119,7 @@
 				seen[named] = true
 
 				// look for a matching attached method
+				named.load()
 				if i, m := lookupMethod(named.methods, pkg, name); m != nil {
 					// potential match
 					// caution: method may not have a proper signature yet
@@ -181,9 +175,7 @@
 
 			case *Interface:
 				// look for a matching method
-				// TODO(gri) t.allMethods is sorted - use binary search
-				check.completeInterface(nopos, t)
-				if i, m := lookupMethod(t.allMethods, pkg, name); m != nil {
+				if i, m := t.typeSet().LookupMethod(pkg, name); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -194,7 +186,7 @@
 				}
 
 			case *TypeParam:
-				if i, m := lookupMethod(t.Bound().allMethods, pkg, name); m != nil {
+				if i, m := t.iface().typeSet().LookupMethod(pkg, name); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -229,7 +221,7 @@
 			return
 		}
 
-		current = check.consolidateMultiples(next)
+		current = consolidateMultiples(next)
 	}
 
 	return nil, nil, false // not found
@@ -246,7 +238,7 @@
 // consolidateMultiples collects multiple list entries with the same type
 // into a single entry marked as containing multiples. The result is the
 // consolidated list.
-func (check *Checker) consolidateMultiples(list []embeddedType) []embeddedType {
+func consolidateMultiples(list []embeddedType) []embeddedType {
 	if len(list) <= 1 {
 		return list // at most one entry - nothing to do
 	}
@@ -254,7 +246,7 @@
 	n := 0                     // number of entries w/ unique type
 	prev := make(map[Type]int) // index at which type was previously seen
 	for _, e := range list {
-		if i, found := check.lookupType(prev, e.typ); found {
+		if i, found := lookupType(prev, e.typ); found {
 			list[i].multiples = true
 			// ignore this entry
 		} else {
@@ -266,14 +258,14 @@
 	return list[:n]
 }
 
-func (check *Checker) lookupType(m map[Type]int, typ Type) (int, bool) {
+func lookupType(m map[Type]int, typ Type) (int, bool) {
 	// fast path: maybe the types are equal
 	if i, found := m[typ]; found {
 		return i, true
 	}
 
 	for t, i := range m {
-		if check.identical(t, typ) {
+		if Identical(t, typ) {
 			return i, true
 		}
 	}
@@ -306,22 +298,18 @@
 // To improve error messages, also report the wrong signature
 // when the method exists on *V instead of V.
 func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method, wrongType *Func) {
-	check.completeInterface(nopos, T)
-
 	// fast path for common case
 	if T.Empty() {
 		return
 	}
 
 	if ityp := asInterface(V); ityp != nil {
-		check.completeInterface(nopos, ityp)
-		// TODO(gri) allMethods is sorted - can do this more efficiently
-		for _, m := range T.allMethods {
-			_, f := lookupMethod(ityp.allMethods, m.pkg, m.name)
+		// TODO(gri) the methods are sorted - could do this more efficiently
+		for _, m := range T.typeSet().methods {
+			_, f := ityp.typeSet().LookupMethod(m.pkg, m.name)
 
 			if f == nil {
-				// if m is the magic method == we're ok (interfaces are comparable)
-				if m.name == "==" || !static {
+				if !static {
 					continue
 				}
 				return m, f
@@ -330,17 +318,20 @@
 			// both methods must have the same number of type parameters
 			ftyp := f.typ.(*Signature)
 			mtyp := m.typ.(*Signature)
-			if len(ftyp.tparams) != len(mtyp.tparams) {
+			if ftyp.TParams().Len() != mtyp.TParams().Len() {
 				return m, f
 			}
+			if !acceptMethodTypeParams && ftyp.TParams().Len() > 0 {
+				panic("method with type parameters")
+			}
 
 			// If the methods have type parameters we don't care whether they
 			// are the same or not, as long as they match up. Use unification
 			// to see if they can be made to match.
 			// TODO(gri) is this always correct? what about type bounds?
 			// (Alternative is to rename/subst type parameters and compare.)
-			u := newUnifier(check, true)
-			u.x.init(ftyp.tparams)
+			u := newUnifier(true)
+			u.x.init(ftyp.TParams().list())
 			if !u.unify(ftyp, mtyp) {
 				return m, f
 			}
@@ -352,14 +343,14 @@
 	// A concrete type implements T if it implements all methods of T.
 	Vd, _ := deref(V)
 	Vn := asNamed(Vd)
-	for _, m := range T.allMethods {
+	for _, m := range T.typeSet().methods {
 		// TODO(gri) should this be calling lookupFieldOrMethod instead (and why not)?
-		obj, _, _ := check.rawLookupFieldOrMethod(V, false, m.pkg, m.name)
+		obj, _, _ := lookupFieldOrMethod(V, false, m.pkg, m.name)
 
 		// Check if *V implements this method of T.
 		if obj == nil {
 			ptr := NewPointer(V)
-			obj, _, _ = check.rawLookupFieldOrMethod(ptr, false, m.pkg, m.name)
+			obj, _, _ = lookupFieldOrMethod(ptr, false, m.pkg, m.name)
 			if obj != nil {
 				return m, obj.(*Func)
 			}
@@ -368,10 +359,6 @@
 		// we must have a method (not a field of matching function type)
 		f, _ := obj.(*Func)
 		if f == nil {
-			// if m is the magic method == and V is comparable, we're ok
-			if m.name == "==" && Comparable(V) {
-				continue
-			}
 			return m, nil
 		}
 
@@ -383,9 +370,12 @@
 		// both methods must have the same number of type parameters
 		ftyp := f.typ.(*Signature)
 		mtyp := m.typ.(*Signature)
-		if len(ftyp.tparams) != len(mtyp.tparams) {
+		if ftyp.TParams().Len() != mtyp.TParams().Len() {
 			return m, f
 		}
+		if !acceptMethodTypeParams && ftyp.TParams().Len() > 0 {
+			panic("method with type parameters")
+		}
 
 		// If V is a (instantiated) generic type, its methods are still
 		// parameterized using the original (declaration) receiver type
@@ -394,17 +384,17 @@
 		// In order to compare the signatures, substitute the receiver
 		// type parameters of ftyp with V's instantiation type arguments.
 		// This lazily instantiates the signature of method f.
-		if Vn != nil && len(Vn.tparams) > 0 {
+		if Vn != nil && Vn.TParams().Len() > 0 {
 			// Be careful: The number of type arguments may not match
 			// the number of receiver parameters. If so, an error was
 			// reported earlier but the length discrepancy is still
 			// here. Exit early in this case to prevent an assertion
 			// failure in makeSubstMap.
 			// TODO(gri) Can we avoid this check by fixing the lengths?
-			if len(ftyp.rparams) != len(Vn.targs) {
+			if len(ftyp.RParams().list()) != len(Vn.targs) {
 				return
 			}
-			ftyp = check.subst(nopos, ftyp, makeSubstMap(ftyp.rparams, Vn.targs)).(*Signature)
+			ftyp = check.subst(nopos, ftyp, makeSubstMap(ftyp.RParams().list(), Vn.targs)).(*Signature)
 		}
 
 		// If the methods have type parameters we don't care whether they
@@ -412,8 +402,21 @@
 		// to see if they can be made to match.
 		// TODO(gri) is this always correct? what about type bounds?
 		// (Alternative is to rename/subst type parameters and compare.)
-		u := newUnifier(check, true)
-		u.x.init(ftyp.tparams)
+		u := newUnifier(true)
+		if ftyp.TParams().Len() > 0 {
+			// We reach here only if we accept method type parameters.
+			// In this case, unification must consider any receiver
+			// and method type parameters as "free" type parameters.
+			assert(acceptMethodTypeParams)
+			// We don't have a test case for this at the moment since
+			// we can't parse method type parameters. Keeping the
+			// unimplemented call so that we test this code if we
+			// enable method type parameters.
+			unimplemented()
+			u.x.init(append(ftyp.RParams().list(), ftyp.TParams().list()...))
+		} else {
+			u.x.init(ftyp.RParams().list())
+		}
 		if !u.unify(ftyp, mtyp) {
 			return m, f
 		}
diff --git a/src/cmd/compile/internal/types2/map.go b/src/cmd/compile/internal/types2/map.go
new file mode 100644
index 0000000..0d3464c
--- /dev/null
+++ b/src/cmd/compile/internal/types2/map.go
@@ -0,0 +1,24 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Map represents a map type.
+type Map struct {
+	key, elem Type
+}
+
+// NewMap returns a new map for the given key and element types.
+func NewMap(key, elem Type) *Map {
+	return &Map{key: key, elem: elem}
+}
+
+// Key returns the key type of map m.
+func (m *Map) Key() Type { return m.key }
+
+// Elem returns the element type of map m.
+func (m *Map) Elem() Type { return m.elem }
+
+func (t *Map) Underlying() Type { return t }
+func (t *Map) String() string   { return TypeString(t, nil) }
diff --git a/src/cmd/compile/internal/types2/named.go b/src/cmd/compile/internal/types2/named.go
new file mode 100644
index 0000000..adf3eb3
--- /dev/null
+++ b/src/cmd/compile/internal/types2/named.go
@@ -0,0 +1,278 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"cmd/compile/internal/syntax"
+	"sync"
+)
+
+// TODO(gri) Clean up Named struct below; specifically the fromRHS field (can we use underlying?).
+
+// A Named represents a named (defined) type.
+type Named struct {
+	check      *Checker
+	info       typeInfo    // for cycle detection
+	obj        *TypeName   // corresponding declared object
+	orig       *Named      // original, uninstantiated type
+	fromRHS    Type        // type (on RHS of declaration) this *Named type is derived from (for cycle reporting)
+	underlying Type        // possibly a *Named during setup; never a *Named once set up completely
+	instance   *instance   // position information for lazy instantiation, or nil
+	tparams    *TypeParams // type parameters, or nil
+	targs      []Type      // type arguments (after instantiation), or nil
+	methods    []*Func     // methods declared for this type (not the method set of this type); signatures are type-checked lazily
+
+	resolve func(*Named) ([]*TypeName, Type, []*Func)
+	once    sync.Once
+}
+
+// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
+// If the given type name obj doesn't have a type yet, its type is set to the returned named type.
+// The underlying type must not be a *Named.
+func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
+	if _, ok := underlying.(*Named); ok {
+		panic("underlying type must not be *Named")
+	}
+	return (*Checker)(nil).newNamed(obj, nil, underlying, nil, methods)
+}
+
+func (t *Named) load() *Named {
+	// If t is an instantiated type, it derives its methods and tparams from its
+	// base type. Since we expect type parameters and methods to be set after a
+	// call to load, we must load the base and copy here.
+	//
+	// underlying is set when t is expanded.
+	//
+	// By convention, a type instance is loaded iff its tparams are set.
+	if len(t.targs) > 0 && t.tparams == nil {
+		t.orig.load()
+		t.tparams = t.orig.tparams
+		t.methods = t.orig.methods
+	}
+	if t.resolve == nil {
+		return t
+	}
+
+	t.once.Do(func() {
+		// TODO(mdempsky): Since we're passing t to resolve anyway
+		// (necessary because types2 expects the receiver type for methods
+		// on defined interface types to be the Named rather than the
+		// underlying Interface), maybe it should just handle calling
+		// SetTParams, SetUnderlying, and AddMethod instead?  Those
+		// methods would need to support reentrant calls though.  It would
+		// also make the API more future-proof towards further extensions
+		// (like SetTParams).
+
+		tparams, underlying, methods := t.resolve(t)
+
+		switch underlying.(type) {
+		case nil, *Named:
+			panic("invalid underlying type")
+		}
+
+		t.tparams = bindTParams(tparams)
+		t.underlying = underlying
+		t.methods = methods
+	})
+	return t
+}
+
+// newNamed is like NewNamed but with a *Checker receiver and additional orig argument.
+func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams *TypeParams, methods []*Func) *Named {
+	typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods}
+	if typ.orig == nil {
+		typ.orig = typ
+	}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	// Ensure that typ is always expanded, at which point the check field can be
+	// nilled out.
+	//
+	// Note that currently we cannot nil out check inside typ.under(), because
+	// it's possible that typ is expanded multiple times.
+	//
+	// TODO(gri): clean this up so that under is the only function mutating
+	//            named types.
+	if check != nil {
+		check.later(func() {
+			switch typ.under().(type) {
+			case *Named:
+				panic("unexpanded underlying type")
+			}
+			typ.check = nil
+		})
+	}
+	return typ
+}
+
+// Obj returns the type name for the named type t.
+func (t *Named) Obj() *TypeName { return t.obj }
+
+// Orig returns the original generic type an instantiated type is derived from.
+// If t is not an instantiated type, the result is t.
+func (t *Named) Orig() *Named { return t.orig }
+
+// TODO(gri) Come up with a better representation and API to distinguish
+//           between parameterized instantiated and non-instantiated types.
+
+// TParams returns the type parameters of the named type t, or nil.
+// The result is non-nil for an (originally) parameterized type even if it is instantiated.
+func (t *Named) TParams() *TypeParams { return t.load().tparams }
+
+// SetTParams sets the type parameters of the named type t.
+func (t *Named) SetTParams(tparams []*TypeName) { t.load().tparams = bindTParams(tparams) }
+
+// TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated.
+func (t *Named) TArgs() []Type { return t.targs }
+
+// NumMethods returns the number of explicit methods whose receiver is named type t.
+func (t *Named) NumMethods() int { return len(t.load().methods) }
+
+// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
+func (t *Named) Method(i int) *Func { return t.load().methods[i] }
+
+// SetUnderlying sets the underlying type and marks t as complete.
+func (t *Named) SetUnderlying(underlying Type) {
+	if underlying == nil {
+		panic("underlying type must not be nil")
+	}
+	if _, ok := underlying.(*Named); ok {
+		panic("underlying type must not be *Named")
+	}
+	t.load().underlying = underlying
+}
+
+// AddMethod adds method m unless it is already in the method list.
+func (t *Named) AddMethod(m *Func) {
+	t.load()
+	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
+		t.methods = append(t.methods, m)
+	}
+}
+
+func (t *Named) Underlying() Type { return t.load().underlying }
+func (t *Named) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// under returns the expanded underlying type of n0; possibly by following
+// forward chains of named types. If an underlying type is found, resolve
+// the chain by setting the underlying type for each defined type in the
+// chain before returning it. If no underlying type is found or a cycle
+// is detected, the result is Typ[Invalid]. If a cycle is detected and
+// n0.check != nil, the cycle is reported.
+func (n0 *Named) under() Type {
+	n0.expand()
+
+	u := n0.Underlying()
+
+	if u == Typ[Invalid] {
+		return u
+	}
+
+	// If the underlying type of a defined type is not a defined
+	// (incl. instance) type, then that is the desired underlying
+	// type.
+	switch u.(type) {
+	case nil:
+		return Typ[Invalid]
+	default:
+		// common case
+		return u
+	case *Named:
+		// handled below
+	}
+
+	if n0.check == nil {
+		panic("Named.check == nil but type is incomplete")
+	}
+
+	// Invariant: after this point n0 as well as any named types in its
+	// underlying chain should be set up when this function exits.
+	check := n0.check
+
+	// If we can't expand u at this point, it is invalid.
+	n := asNamed(u)
+	if n == nil {
+		n0.underlying = Typ[Invalid]
+		return n0.underlying
+	}
+
+	// Otherwise, follow the forward chain.
+	seen := map[*Named]int{n0: 0}
+	path := []Object{n0.obj}
+	for {
+		u = n.Underlying()
+		if u == nil {
+			u = Typ[Invalid]
+			break
+		}
+		var n1 *Named
+		switch u1 := u.(type) {
+		case *Named:
+			u1.expand()
+			n1 = u1
+		}
+		if n1 == nil {
+			break // end of chain
+		}
+
+		seen[n] = len(seen)
+		path = append(path, n.obj)
+		n = n1
+
+		if i, ok := seen[n]; ok {
+			// cycle
+			check.cycleError(path[i:])
+			u = Typ[Invalid]
+			break
+		}
+	}
+
+	for n := range seen {
+		// We should never have to update the underlying type of an imported type;
+		// those underlying types should have been resolved during the import.
+		// Also, doing so would lead to a race condition (was issue #31749).
+		// Do this check always, not just in debug mode (it's cheap).
+		if n.obj.pkg != check.pkg {
+			panic("imported type with unresolved underlying type")
+		}
+		n.underlying = u
+	}
+
+	return u
+}
+
+func (n *Named) setUnderlying(typ Type) {
+	if n != nil {
+		n.underlying = typ
+	}
+}
+
+// instance holds position information for use in lazy instantiation.
+//
+// TODO(rfindley): come up with a better name for this type, now that its usage
+// has changed.
+type instance struct {
+	pos     syntax.Pos   // position of type instantiation; for error reporting only
+	posList []syntax.Pos // position of each targ; for error reporting only
+}
+
+// expand ensures that the underlying type of n is instantiated.
+// The underlying type will be Typ[Invalid] if there was an error.
+func (n *Named) expand() {
+	if n.instance != nil {
+		// n must be loaded before instantiation, in order to have accurate
+		// tparams. This is done implicitly by the call to n.TParams, but making it
+		// explicit is harmless: load is idempotent.
+		n.load()
+		inst := n.check.instantiate(n.instance.pos, n.orig.underlying, n.TParams().list(), n.targs, n.instance.posList)
+		n.underlying = inst
+		n.fromRHS = inst
+		n.instance = nil
+	}
+}
diff --git a/src/cmd/compile/internal/types2/object.go b/src/cmd/compile/internal/types2/object.go
index 844bc34..8263cca 100644
--- a/src/cmd/compile/internal/types2/object.go
+++ b/src/cmd/compile/internal/types2/object.go
@@ -186,6 +186,45 @@
 	return pkg.path == obj.pkg.path
 }
 
+// less reports whether object a is ordered before object b.
+//
+// Objects are ordered nil before non-nil, exported before
+// non-exported, then by name, and finally (for non-exported
+// functions) by package height and path.
+func (a *object) less(b *object) bool {
+	if a == b {
+		return false
+	}
+
+	// Nil before non-nil.
+	if a == nil {
+		return true
+	}
+	if b == nil {
+		return false
+	}
+
+	// Exported functions before non-exported.
+	ea := isExported(a.name)
+	eb := isExported(b.name)
+	if ea != eb {
+		return ea
+	}
+
+	// Order by name and then (for non-exported names) by package.
+	if a.name != b.name {
+		return a.name < b.name
+	}
+	if !ea {
+		if a.pkg.height != b.pkg.height {
+			return a.pkg.height < b.pkg.height
+		}
+		return a.pkg.path < b.pkg.path
+	}
+
+	return false
+}
+
 // A PkgName represents an imported Go package.
 // PkgNames don't have a type.
 type PkgName struct {
@@ -237,6 +276,14 @@
 	return &TypeName{object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}}
 }
 
+// NewTypeNameLazy returns a new defined type like NewTypeName, but it
+// lazily calls resolve to finish constructing the Named object.
+func NewTypeNameLazy(pos syntax.Pos, pkg *Package, name string, resolve func(named *Named) (tparams []*TypeName, underlying Type, methods []*Func)) *TypeName {
+	obj := NewTypeName(pos, pkg, name, nil)
+	NewNamed(obj, nil, nil).resolve = resolve
+	return obj
+}
+
 // IsAlias reports whether obj is an alias name for a type.
 func (obj *TypeName) IsAlias() bool {
 	switch t := obj.typ.(type) {
@@ -329,36 +376,6 @@
 // Scope returns the scope of the function's body block.
 func (obj *Func) Scope() *Scope { return obj.typ.(*Signature).scope }
 
-// Less reports whether function a is ordered before function b.
-//
-// Functions are ordered exported before non-exported, then by name,
-// and finally (for non-exported functions) by package path.
-//
-// TODO(gri) The compiler also sorts by package height before package
-//           path for non-exported names.
-func (a *Func) less(b *Func) bool {
-	if a == b {
-		return false
-	}
-
-	// Exported functions before non-exported.
-	ea := isExported(a.name)
-	eb := isExported(b.name)
-	if ea != eb {
-		return ea
-	}
-
-	// Order by name and then (for non-exported names) by package.
-	if a.name != b.name {
-		return a.name < b.name
-	}
-	if !ea {
-		return a.pkg.path < b.pkg.path
-	}
-
-	return false
-}
-
 func (*Func) isDependency() {} // a function may be a dependency of an initialization expression
 
 // A Label represents a declared label.
@@ -458,6 +475,9 @@
 		if _, ok := typ.(*Basic); ok {
 			return
 		}
+		if named, _ := typ.(*Named); named != nil && named.TParams().Len() > 0 {
+			writeTParamList(buf, named.TParams().list(), qf, nil)
+		}
 		if tname.IsAlias() {
 			buf.WriteString(" =")
 		} else {
diff --git a/src/cmd/compile/internal/types2/object_test.go b/src/cmd/compile/internal/types2/object_test.go
index 7f63c79..a86733a 100644
--- a/src/cmd/compile/internal/types2/object_test.go
+++ b/src/cmd/compile/internal/types2/object_test.go
@@ -25,7 +25,7 @@
 	check(Unsafe.Scope().Lookup("Pointer").(*TypeName), false)
 	for _, name := range Universe.Names() {
 		if obj, _ := Universe.Lookup(name).(*TypeName); obj != nil {
-			check(obj, name == "byte" || name == "rune")
+			check(obj, name == "any" || name == "byte" || name == "rune")
 		}
 	}
 
diff --git a/src/cmd/compile/internal/types2/operand.go b/src/cmd/compile/internal/types2/operand.go
index 455d8b5..8336451 100644
--- a/src/cmd/compile/internal/types2/operand.go
+++ b/src/cmd/compile/internal/types2/operand.go
@@ -176,16 +176,20 @@
 	if hasType {
 		if x.typ != Typ[Invalid] {
 			var intro string
-			switch {
-			case isGeneric(x.typ):
-				intro = " of generic type "
-			case asTypeParam(x.typ) != nil:
-				intro = " of type parameter type "
-			default:
+			var tpar *TypeParam
+			if isGeneric(x.typ) {
+				intro = " of parameterized type "
+			} else if tpar = asTypeParam(x.typ); tpar != nil {
+				intro = " of type parameter "
+			} else {
 				intro = " of type "
 			}
 			buf.WriteString(intro)
 			WriteType(&buf, x.typ, qf)
+			if tpar != nil {
+				buf.WriteString(" constrained by ")
+				WriteType(&buf, tpar.bound, qf) // do not compute interface type sets here
+			}
 		} else {
 			buf.WriteString(" with invalid type")
 		}
@@ -248,20 +252,35 @@
 
 	V := x.typ
 
+	const debugAssignableTo = false
+	if debugAssignableTo && check != nil {
+		check.dump("V = %s", V)
+		check.dump("T = %s", T)
+	}
+
 	// x's type is identical to T
-	if check.identical(V, T) {
+	if Identical(V, T) {
 		return true, 0
 	}
 
 	Vu := optype(V)
 	Tu := optype(T)
 
+	if debugAssignableTo && check != nil {
+		check.dump("Vu = %s", Vu)
+		check.dump("Tu = %s", Tu)
+	}
+
 	// x is an untyped value representable by a value of type T.
 	if isUntyped(Vu) {
-		if t, ok := Tu.(*Sum); ok {
-			return t.is(func(t Type) bool {
+		if t, ok := Tu.(*TypeParam); ok {
+			return t.is(func(t *term) bool {
 				// TODO(gri) this could probably be more efficient
-				ok, _ := x.assignableTo(check, t, reason)
+				if t.tilde {
+					// TODO(gri) We need to check assignability
+					//           for the underlying type of x.
+				}
+				ok, _ := x.assignableTo(check, t.typ, reason)
 				return ok
 			}), _IncompatibleAssign
 		}
@@ -272,7 +291,7 @@
 
 	// x's type V and T have identical underlying types
 	// and at least one of V or T is not a named type
-	if check.identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
+	if Identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
 		return true, 0
 	}
 
@@ -281,7 +300,7 @@
 		if m, wrongType := check.missingMethod(V, Ti, true); m != nil /* Implements(V, Ti) */ {
 			if reason != nil {
 				if wrongType != nil {
-					if check.identical(m.typ, wrongType.typ) {
+					if Identical(m.typ, wrongType.typ) {
 						*reason = fmt.Sprintf("missing method %s (%s has pointer receiver)", m.name, m.name)
 					} else {
 						*reason = fmt.Sprintf("wrong type for method %s (have %s, want %s)", m.Name(), wrongType.typ, m.typ)
@@ -300,7 +319,7 @@
 	// type, x's type V and T have identical element types,
 	// and at least one of V or T is not a named type
 	if Vc, ok := Vu.(*Chan); ok && Vc.dir == SendRecv {
-		if Tc, ok := Tu.(*Chan); ok && check.identical(Vc.elem, Tc.elem) {
+		if Tc, ok := Tu.(*Chan); ok && Identical(Vc.elem, Tc.elem) {
 			return !isNamed(V) || !isNamed(T), _InvalidChanAssign
 		}
 	}
diff --git a/src/cmd/compile/internal/types2/package.go b/src/cmd/compile/internal/types2/package.go
index 31b1e71..8044e7e 100644
--- a/src/cmd/compile/internal/types2/package.go
+++ b/src/cmd/compile/internal/types2/package.go
@@ -13,8 +13,9 @@
 	path     string
 	name     string
 	scope    *Scope
-	complete bool
 	imports  []*Package
+	height   int
+	complete bool
 	fake     bool // scope lookup errors are silently dropped if package is fake (internal use only)
 	cgo      bool // uses of this package will be rewritten into uses of declarations from _cgo_gotypes.go
 }
@@ -22,8 +23,14 @@
 // NewPackage returns a new Package for the given package path and name.
 // The package is not complete and contains no explicit imports.
 func NewPackage(path, name string) *Package {
+	return NewPackageHeight(path, name, 0)
+}
+
+// NewPackageHeight is like NewPackage, but allows specifying the
+// package's height.
+func NewPackageHeight(path, name string, height int) *Package {
 	scope := NewScope(Universe, nopos, nopos, fmt.Sprintf("package %q", path))
-	return &Package{path: path, name: name, scope: scope}
+	return &Package{path: path, name: name, scope: scope, height: height}
 }
 
 // Path returns the package path.
@@ -32,13 +39,22 @@
 // Name returns the package name.
 func (pkg *Package) Name() string { return pkg.name }
 
+// Height returns the package height.
+func (pkg *Package) Height() int { return pkg.height }
+
 // SetName sets the package name.
 func (pkg *Package) SetName(name string) { pkg.name = name }
 
 // Scope returns the (complete or incomplete) package scope
 // holding the objects declared at package level (TypeNames,
 // Consts, Vars, and Funcs).
-func (pkg *Package) Scope() *Scope { return pkg.scope }
+// For a nil pkg receiver, Scope returns the Universe scope.
+func (pkg *Package) Scope() *Scope {
+	if pkg != nil {
+		return pkg.scope
+	}
+	return Universe
+}
 
 // A package is complete if its scope contains (at least) all
 // exported objects; otherwise it is incomplete.
diff --git a/src/cmd/compile/internal/types2/pointer.go b/src/cmd/compile/internal/types2/pointer.go
new file mode 100644
index 0000000..63055fc6
--- /dev/null
+++ b/src/cmd/compile/internal/types2/pointer.go
@@ -0,0 +1,19 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Pointer represents a pointer type.
+type Pointer struct {
+	base Type // element type
+}
+
+// NewPointer returns a new pointer type for the given element (base) type.
+func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
+
+// Elem returns the element type for the given pointer p.
+func (p *Pointer) Elem() Type { return p.base }
+
+func (p *Pointer) Underlying() Type { return p }
+func (p *Pointer) String() string   { return TypeString(p, nil) }
diff --git a/src/cmd/compile/internal/types2/predicates.go b/src/cmd/compile/internal/types2/predicates.go
index ae186a0..1541b3f 100644
--- a/src/cmd/compile/internal/types2/predicates.go
+++ b/src/cmd/compile/internal/types2/predicates.go
@@ -10,7 +10,7 @@
 // isNamed may be called with types that are not fully set up.
 func isNamed(typ Type) bool {
 	switch typ.(type) {
-	case *Basic, *Named, *TypeParam, *instance:
+	case *Basic, *Named, *TypeParam:
 		return true
 	}
 	return false
@@ -21,15 +21,15 @@
 func isGeneric(typ Type) bool {
 	// A parameterized type is only instantiated if it doesn't have an instantiation already.
 	named, _ := typ.(*Named)
-	return named != nil && named.obj != nil && named.tparams != nil && named.targs == nil
+	return named != nil && named.obj != nil && named.targs == nil && named.TParams() != nil
 }
 
 func is(typ Type, what BasicInfo) bool {
-	switch t := optype(typ).(type) {
+	switch t := under(typ).(type) {
 	case *Basic:
 		return t.info&what != 0
-	case *Sum:
-		return t.is(func(typ Type) bool { return is(typ, what) })
+	case *TypeParam:
+		return t.underIs(func(t Type) bool { return is(t, what) })
 	}
 	return false
 }
@@ -56,10 +56,7 @@
 // are not fully set up.
 func isTyped(typ Type) bool {
 	// isTyped is called with types that are not fully
-	// set up. Must not call Basic()!
-	// A *Named or *instance type is always typed, so
-	// we only need to check if we have a true *Basic
-	// type.
+	// set up. Must not call asBasic()!
 	t, _ := typ.(*Basic)
 	return t == nil || t.info&IsUntyped == 0
 }
@@ -96,19 +93,7 @@
 	}
 	seen[T] = true
 
-	// If T is a type parameter not constrained by any type
-	// list (i.e., it's underlying type is the top type),
-	// T is comparable if it has the == method. Otherwise,
-	// the underlying type "wins". For instance
-	//
-	//     interface{ comparable; type []byte }
-	//
-	// is not comparable because []byte is not comparable.
-	if t := asTypeParam(T); t != nil && optype(t) == theTop {
-		return t.Bound().IsComparable()
-	}
-
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Basic:
 		// assume invalid types to be comparable
 		// to avoid follow-up errors
@@ -124,42 +109,25 @@
 		return true
 	case *Array:
 		return comparable(t.elem, seen)
-	case *Sum:
-		pred := func(t Type) bool {
-			return comparable(t, seen)
-		}
-		return t.is(pred)
 	case *TypeParam:
-		return t.Bound().IsComparable()
+		return t.iface().IsComparable()
 	}
 	return false
 }
 
 // hasNil reports whether a type includes the nil value.
 func hasNil(typ Type) bool {
-	switch t := optype(typ).(type) {
+	switch t := under(typ).(type) {
 	case *Basic:
 		return t.kind == UnsafePointer
 	case *Slice, *Pointer, *Signature, *Interface, *Map, *Chan:
 		return true
-	case *Sum:
-		return t.is(hasNil)
+	case *TypeParam:
+		return t.underIs(hasNil)
 	}
 	return false
 }
 
-// identical reports whether x and y are identical types.
-// Receivers of Signature types are ignored.
-func (check *Checker) identical(x, y Type) bool {
-	return check.identical0(x, y, true, nil)
-}
-
-// identicalIgnoreTags reports whether x and y are identical types if tags are ignored.
-// Receivers of Signature types are ignored.
-func (check *Checker) identicalIgnoreTags(x, y Type) bool {
-	return check.identical0(x, y, false, nil)
-}
-
 // An ifacePair is a node in a stack of interface type pairs compared for identity.
 type ifacePair struct {
 	x, y *Interface
@@ -171,11 +139,7 @@
 }
 
 // For changes to this code the corresponding changes should be made to unifier.nify.
-func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
-	// types must be expanded for comparison
-	x = expandf(x)
-	y = expandf(y)
-
+func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
 	if x == y {
 		return true
 	}
@@ -195,13 +159,13 @@
 		if y, ok := y.(*Array); ok {
 			// If one or both array lengths are unknown (< 0) due to some error,
 			// assume they are the same to avoid spurious follow-on errors.
-			return (x.len < 0 || y.len < 0 || x.len == y.len) && check.identical0(x.elem, y.elem, cmpTags, p)
+			return (x.len < 0 || y.len < 0 || x.len == y.len) && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Slice:
 		// Two slice types are identical if they have identical element types.
 		if y, ok := y.(*Slice); ok {
-			return check.identical0(x.elem, y.elem, cmpTags, p)
+			return identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Struct:
@@ -216,7 +180,7 @@
 					if f.embedded != g.embedded ||
 						cmpTags && x.Tag(i) != y.Tag(i) ||
 						!f.sameId(g.pkg, g.name) ||
-						!check.identical0(f.typ, g.typ, cmpTags, p) {
+						!identical(f.typ, g.typ, cmpTags, p) {
 						return false
 					}
 				}
@@ -227,7 +191,7 @@
 	case *Pointer:
 		// Two pointer types are identical if they have identical base types.
 		if y, ok := y.(*Pointer); ok {
-			return check.identical0(x.base, y.base, cmpTags, p)
+			return identical(x.base, y.base, cmpTags, p)
 		}
 
 	case *Tuple:
@@ -238,7 +202,7 @@
 				if x != nil {
 					for i, v := range x.vars {
 						w := y.vars[i]
-						if !check.identical0(v.typ, w.typ, cmpTags, p) {
+						if !identical(v.typ, w.typ, cmpTags, p) {
 							return false
 						}
 					}
@@ -256,49 +220,27 @@
 		// parameter names.
 		if y, ok := y.(*Signature); ok {
 			return x.variadic == y.variadic &&
-				check.identicalTParams(x.tparams, y.tparams, cmpTags, p) &&
-				check.identical0(x.params, y.params, cmpTags, p) &&
-				check.identical0(x.results, y.results, cmpTags, p)
-		}
-
-	case *Sum:
-		// Two sum types are identical if they contain the same types.
-		// (Sum types always consist of at least two types. Also, the
-		// the set (list) of types in a sum type consists of unique
-		// types - each type appears exactly once. Thus, two sum types
-		// must contain the same number of types to have chance of
-		// being equal.
-		if y, ok := y.(*Sum); ok && len(x.types) == len(y.types) {
-			// Every type in x.types must be in y.types.
-			// Quadratic algorithm, but probably good enough for now.
-			// TODO(gri) we need a fast quick type ID/hash for all types.
-		L:
-			for _, x := range x.types {
-				for _, y := range y.types {
-					if Identical(x, y) {
-						continue L // x is in y.types
-					}
-				}
-				return false // x is not in y.types
-			}
-			return true
+				identicalTParams(x.TParams().list(), y.TParams().list(), cmpTags, p) &&
+				identical(x.params, y.params, cmpTags, p) &&
+				identical(x.results, y.results, cmpTags, p)
 		}
 
 	case *Interface:
+		// Two interface types are identical if they describe the same type sets.
+		// With the existing implementation restriction, this simplifies to:
+		//
 		// Two interface types are identical if they have the same set of methods with
-		// the same names and identical function types. Lower-case method names from
-		// different packages are always different. The order of the methods is irrelevant.
+		// the same names and identical function types, and if any type restrictions
+		// are the same. Lower-case method names from different packages are always
+		// different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			// If identical0 is called (indirectly) via an external API entry point
-			// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
-			// that case, interfaces are expected to be complete and lazy completion
-			// here is not needed.
-			if check != nil {
-				check.completeInterface(nopos, x)
-				check.completeInterface(nopos, y)
+			xset := x.typeSet()
+			yset := y.typeSet()
+			if !xset.terms.equal(yset.terms) {
+				return false
 			}
-			a := x.allMethods
-			b := y.allMethods
+			a := xset.methods
+			b := yset.methods
 			if len(a) == len(b) {
 				// Interface types are the only types where cycles can occur
 				// that are not "terminated" via named types; and such cycles
@@ -335,7 +277,7 @@
 				}
 				for i, f := range a {
 					g := b[i]
-					if f.Id() != g.Id() || !check.identical0(f.typ, g.typ, cmpTags, q) {
+					if f.Id() != g.Id() || !identical(f.typ, g.typ, cmpTags, q) {
 						return false
 					}
 				}
@@ -346,20 +288,22 @@
 	case *Map:
 		// Two map types are identical if they have identical key and value types.
 		if y, ok := y.(*Map); ok {
-			return check.identical0(x.key, y.key, cmpTags, p) && check.identical0(x.elem, y.elem, cmpTags, p)
+			return identical(x.key, y.key, cmpTags, p) && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Chan:
 		// Two channel types are identical if they have identical value types
 		// and the same direction.
 		if y, ok := y.(*Chan); ok {
-			return x.dir == y.dir && check.identical0(x.elem, y.elem, cmpTags, p)
+			return x.dir == y.dir && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Named:
 		// Two named types are identical if their type names originate
 		// in the same type declaration.
 		if y, ok := y.(*Named); ok {
+			x.expand()
+			y.expand()
 			// TODO(gri) Why is x == y not sufficient? And if it is,
 			//           we can just return false here because x == y
 			//           is caught in the very beginning of this function.
@@ -369,13 +313,9 @@
 	case *TypeParam:
 		// nothing to do (x and y being equal is caught in the very beginning of this function)
 
-	// case *instance:
-	//	unreachable since types are expanded
-
-	case *bottom, *top:
-		// Either both types are theBottom, or both are theTop in which
-		// case the initial x == y check will have caught them. Otherwise
-		// they are not identical.
+	case *top:
+		// Either both types are theTop in which case the initial x == y check
+		// will have caught them. Otherwise they are not identical.
 
 	case nil:
 		// avoid a crash in case of nil type
@@ -387,13 +327,13 @@
 	return false
 }
 
-func (check *Checker) identicalTParams(x, y []*TypeName, cmpTags bool, p *ifacePair) bool {
+func identicalTParams(x, y []*TypeName, cmpTags bool, p *ifacePair) bool {
 	if len(x) != len(y) {
 		return false
 	}
 	for i, x := range x {
 		y := y[i]
-		if !check.identical0(x.typ.(*TypeParam).bound, y.typ.(*TypeParam).bound, cmpTags, p) {
+		if !identical(x.typ.(*TypeParam).bound, y.typ.(*TypeParam).bound, cmpTags, p) {
 			return false
 		}
 	}
diff --git a/src/cmd/compile/internal/types2/resolver.go b/src/cmd/compile/internal/types2/resolver.go
index fa30650..018a20c 100644
--- a/src/cmd/compile/internal/types2/resolver.go
+++ b/src/cmd/compile/internal/types2/resolver.go
@@ -196,6 +196,7 @@
 // methods with receiver base type names.
 func (check *Checker) collectObjects() {
 	pkg := check.pkg
+	pkg.height = 0
 
 	// pkgImports is the set of packages already imported by any package file seen
 	// so far. Used to avoid duplicate entries in pkg.imports. Allocate and populate
@@ -253,6 +254,15 @@
 					continue
 				}
 
+				if imp == Unsafe {
+					// typecheck ignores imports of package unsafe for
+					// calculating height.
+					// TODO(mdempsky): Revisit this. This seems fine, but I
+					// don't remember explicitly considering this case.
+				} else if h := imp.height + 1; h > pkg.height {
+					pkg.height = h
+				}
+
 				// local name overrides imported package name
 				name := imp.name
 				if s.LocalPkgName != nil {
@@ -265,7 +275,7 @@
 				}
 
 				if name == "init" {
-					check.error(s.LocalPkgName, "cannot import package as init - init must be a func")
+					check.error(s, "cannot import package as init - init must be a func")
 					continue
 				}
 
@@ -298,22 +308,26 @@
 						check.dotImportMap = make(map[dotImportKey]*PkgName)
 					}
 					// merge imported scope with file scope
-					for _, obj := range imp.scope.elems {
+					for name, obj := range imp.scope.elems {
+						// Note: Avoid eager resolve(name, obj) here, so we only
+						// resolve dot-imported objects as needed.
+
 						// A package scope may contain non-exported objects,
 						// do not import them!
-						if obj.Exported() {
+						if isExported(name) {
 							// declare dot-imported object
 							// (Do not use check.declare because it modifies the object
 							// via Object.setScopePos, which leads to a race condition;
 							// the object may be imported into more than one file scope
 							// concurrently. See issue #32154.)
-							if alt := fileScope.Insert(obj); alt != nil {
+							if alt := fileScope.Lookup(name); alt != nil {
 								var err error_
-								err.errorf(s.LocalPkgName, "%s redeclared in this block", obj.Name())
+								err.errorf(s.LocalPkgName, "%s redeclared in this block", alt.Name())
 								err.recordAltDecl(alt)
 								check.report(&err)
 							} else {
-								check.dotImportMap[dotImportKey{fileScope, obj}] = pkgName
+								fileScope.insert(name, obj)
+								check.dotImportMap[dotImportKey{fileScope, name}] = pkgName
 							}
 						}
 					}
@@ -459,8 +473,9 @@
 
 	// verify that objects in package and file scopes have different names
 	for _, scope := range fileScopes {
-		for _, obj := range scope.elems {
-			if alt := pkg.scope.Lookup(obj.Name()); alt != nil {
+		for name, obj := range scope.elems {
+			if alt := pkg.scope.Lookup(name); alt != nil {
+				obj = resolve(name, obj)
 				var err error_
 				if pkg, ok := obj.(*PkgName); ok {
 					err.errorf(alt, "%s already declared through import of %s", alt.Name(), pkg.Imported())
diff --git a/src/cmd/compile/internal/types2/resolver_test.go b/src/cmd/compile/internal/types2/resolver_test.go
index aee435ff..a02abce 100644
--- a/src/cmd/compile/internal/types2/resolver_test.go
+++ b/src/cmd/compile/internal/types2/resolver_test.go
@@ -143,7 +143,7 @@
 
 	// check that qualified identifiers are resolved
 	for _, f := range files {
-		syntax.Walk(f, func(n syntax.Node) bool {
+		syntax.Crawl(f, func(n syntax.Node) bool {
 			if s, ok := n.(*syntax.SelectorExpr); ok {
 				if x, ok := s.X.(*syntax.Name); ok {
 					obj := uses[x]
@@ -177,7 +177,7 @@
 	foundDefs := make(map[*syntax.Name]bool)
 	var both []string
 	for _, f := range files {
-		syntax.Walk(f, func(n syntax.Node) bool {
+		syntax.Crawl(f, func(n syntax.Node) bool {
 			if x, ok := n.(*syntax.Name); ok {
 				var objects int
 				if _, found := uses[x]; found {
diff --git a/src/cmd/compile/internal/types2/sanitize.go b/src/cmd/compile/internal/types2/sanitize.go
deleted file mode 100644
index 64a2ded..0000000
--- a/src/cmd/compile/internal/types2/sanitize.go
+++ /dev/null
@@ -1,202 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package types2
-
-// sanitizeInfo walks the types contained in info to ensure that all instances
-// are expanded.
-//
-// This includes some objects that may be shared across concurrent
-// type-checking passes (such as those in the universe scope), so we are
-// careful here not to write types that are already sanitized. This avoids a
-// data race as any shared types should already be sanitized.
-func sanitizeInfo(info *Info) {
-	var s sanitizer = make(map[Type]Type)
-
-	// Note: Some map entries are not references.
-	// If modified, they must be assigned back.
-
-	for e, tv := range info.Types {
-		if typ := s.typ(tv.Type); typ != tv.Type {
-			tv.Type = typ
-			info.Types[e] = tv
-		}
-	}
-
-	for e, inf := range info.Inferred {
-		changed := false
-		for i, targ := range inf.Targs {
-			if typ := s.typ(targ); typ != targ {
-				inf.Targs[i] = typ
-				changed = true
-			}
-		}
-		if typ := s.typ(inf.Sig); typ != inf.Sig {
-			inf.Sig = typ.(*Signature)
-			changed = true
-		}
-		if changed {
-			info.Inferred[e] = inf
-		}
-	}
-
-	for _, obj := range info.Defs {
-		if obj != nil {
-			if typ := s.typ(obj.Type()); typ != obj.Type() {
-				obj.setType(typ)
-			}
-		}
-	}
-
-	for _, obj := range info.Uses {
-		if obj != nil {
-			if typ := s.typ(obj.Type()); typ != obj.Type() {
-				obj.setType(typ)
-			}
-		}
-	}
-
-	// TODO(gri) sanitize as needed
-	// - info.Implicits
-	// - info.Selections
-	// - info.Scopes
-	// - info.InitOrder
-}
-
-type sanitizer map[Type]Type
-
-func (s sanitizer) typ(typ Type) Type {
-	if typ == nil {
-		return nil
-	}
-
-	if t, found := s[typ]; found {
-		return t
-	}
-	s[typ] = typ
-
-	switch t := typ.(type) {
-	case *Basic, *bottom, *top:
-		// nothing to do
-
-	case *Array:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Slice:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Struct:
-		s.varList(t.fields)
-
-	case *Pointer:
-		if base := s.typ(t.base); base != t.base {
-			t.base = base
-		}
-
-	case *Tuple:
-		s.tuple(t)
-
-	case *Signature:
-		s.var_(t.recv)
-		s.tuple(t.params)
-		s.tuple(t.results)
-
-	case *Sum:
-		s.typeList(t.types)
-
-	case *Interface:
-		s.funcList(t.methods)
-		if types := s.typ(t.types); types != t.types {
-			t.types = types
-		}
-		s.typeList(t.embeddeds)
-		s.funcList(t.allMethods)
-		if allTypes := s.typ(t.allTypes); allTypes != t.allTypes {
-			t.allTypes = allTypes
-		}
-
-	case *Map:
-		if key := s.typ(t.key); key != t.key {
-			t.key = key
-		}
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Chan:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Named:
-		if orig := s.typ(t.fromRHS); orig != t.fromRHS {
-			t.fromRHS = orig
-		}
-		if under := s.typ(t.underlying); under != t.underlying {
-			t.underlying = under
-		}
-		s.typeList(t.targs)
-		s.funcList(t.methods)
-
-	case *TypeParam:
-		if bound := s.typ(t.bound); bound != t.bound {
-			t.bound = bound
-		}
-
-	case *instance:
-		typ = t.expand()
-		s[t] = typ
-
-	default:
-		panic("unimplemented")
-	}
-
-	return typ
-}
-
-func (s sanitizer) var_(v *Var) {
-	if v != nil {
-		if typ := s.typ(v.typ); typ != v.typ {
-			v.typ = typ
-		}
-	}
-}
-
-func (s sanitizer) varList(list []*Var) {
-	for _, v := range list {
-		s.var_(v)
-	}
-}
-
-func (s sanitizer) tuple(t *Tuple) {
-	if t != nil {
-		s.varList(t.vars)
-	}
-}
-
-func (s sanitizer) func_(f *Func) {
-	if f != nil {
-		if typ := s.typ(f.typ); typ != f.typ {
-			f.typ = typ
-		}
-	}
-}
-
-func (s sanitizer) funcList(list []*Func) {
-	for _, f := range list {
-		s.func_(f)
-	}
-}
-
-func (s sanitizer) typeList(list []Type) {
-	for i, t := range list {
-		if typ := s.typ(t); typ != t {
-			list[i] = typ
-		}
-	}
-}
diff --git a/src/cmd/compile/internal/types2/scope.go b/src/cmd/compile/internal/types2/scope.go
index ade0a79..095875d9 100644
--- a/src/cmd/compile/internal/types2/scope.go
+++ b/src/cmd/compile/internal/types2/scope.go
@@ -13,6 +13,7 @@
 	"io"
 	"sort"
 	"strings"
+	"sync"
 )
 
 // A Scope maintains a set of objects and links to its containing
@@ -22,6 +23,7 @@
 type Scope struct {
 	parent   *Scope
 	children []*Scope
+	number   int               // parent.children[number-1] is this scope; 0 if there is no parent
 	elems    map[string]Object // lazily allocated
 	pos, end syntax.Pos        // scope extent; may be invalid
 	comment  string            // for debugging only
@@ -31,10 +33,11 @@
 // NewScope returns a new, empty scope contained in the given parent
 // scope, if any. The comment is for debugging only.
 func NewScope(parent *Scope, pos, end syntax.Pos, comment string) *Scope {
-	s := &Scope{parent, nil, nil, pos, end, comment, false}
+	s := &Scope{parent, nil, 0, nil, pos, end, comment, false}
 	// don't add children to Universe scope!
 	if parent != nil && parent != Universe {
 		parent.children = append(parent.children, s)
+		s.number = len(parent.children)
 	}
 	return s
 }
@@ -66,7 +69,7 @@
 // Lookup returns the object in scope s with the given name if such an
 // object exists; otherwise the result is nil.
 func (s *Scope) Lookup(name string) Object {
-	return s.elems[name]
+	return resolve(name, s.elems[name])
 }
 
 // LookupParent follows the parent chain of scopes starting with s until
@@ -81,7 +84,7 @@
 // whose scope is the scope of the package that exported them.
 func (s *Scope) LookupParent(name string, pos syntax.Pos) (*Scope, Object) {
 	for ; s != nil; s = s.parent {
-		if obj := s.elems[name]; obj != nil && (!pos.IsKnown() || obj.scopePos().Cmp(pos) <= 0) {
+		if obj := s.Lookup(name); obj != nil && (!pos.IsKnown() || obj.scopePos().Cmp(pos) <= 0) {
 			return s, obj
 		}
 	}
@@ -95,19 +98,38 @@
 // if not already set, and returns nil.
 func (s *Scope) Insert(obj Object) Object {
 	name := obj.Name()
-	if alt := s.elems[name]; alt != nil {
+	if alt := s.Lookup(name); alt != nil {
 		return alt
 	}
-	if s.elems == nil {
-		s.elems = make(map[string]Object)
-	}
-	s.elems[name] = obj
+	s.insert(name, obj)
 	if obj.Parent() == nil {
 		obj.setParent(s)
 	}
 	return nil
 }
 
+// InsertLazy is like Insert, but allows deferring construction of the
+// inserted object until it's accessed with Lookup. The Object
+// returned by resolve must have the same name as given to InsertLazy.
+// If s already contains an alternative object with the same name,
+// InsertLazy leaves s unchanged and returns false. Otherwise it
+// records the binding and returns true. The object's parent scope
+// will be set to s after resolve is called.
+func (s *Scope) InsertLazy(name string, resolve func() Object) bool {
+	if s.elems[name] != nil {
+		return false
+	}
+	s.insert(name, &lazyObject{parent: s, resolve: resolve})
+	return true
+}
+
+func (s *Scope) insert(name string, obj Object) {
+	if s.elems == nil {
+		s.elems = make(map[string]Object)
+	}
+	s.elems[name] = obj
+}
+
 // Squash merges s with its parent scope p by adding all
 // objects of s to p, adding all children of s to the
 // children of p, and removing s from p's children.
@@ -117,7 +139,8 @@
 func (s *Scope) Squash(err func(obj, alt Object)) {
 	p := s.parent
 	assert(p != nil)
-	for _, obj := range s.elems {
+	for name, obj := range s.elems {
+		obj = resolve(name, obj)
 		obj.setParent(nil)
 		if alt := p.Insert(obj); alt != nil {
 			err(obj, alt)
@@ -196,7 +219,7 @@
 
 	indn1 := indn + ind
 	for _, name := range s.Names() {
-		fmt.Fprintf(w, "%s%s\n", indn1, s.elems[name])
+		fmt.Fprintf(w, "%s%s\n", indn1, s.Lookup(name))
 	}
 
 	if recurse {
@@ -214,3 +237,57 @@
 	s.WriteTo(&buf, 0, false)
 	return buf.String()
 }
+
+// A lazyObject represents an imported Object that has not been fully
+// resolved yet by its importer.
+type lazyObject struct {
+	parent  *Scope
+	resolve func() Object
+	obj     Object
+	once    sync.Once
+}
+
+// resolve returns the Object represented by obj, resolving lazy
+// objects as appropriate.
+func resolve(name string, obj Object) Object {
+	if lazy, ok := obj.(*lazyObject); ok {
+		lazy.once.Do(func() {
+			obj := lazy.resolve()
+
+			if _, ok := obj.(*lazyObject); ok {
+				panic("recursive lazy object")
+			}
+			if obj.Name() != name {
+				panic("lazy object has unexpected name")
+			}
+
+			if obj.Parent() == nil {
+				obj.setParent(lazy.parent)
+			}
+			lazy.obj = obj
+		})
+
+		obj = lazy.obj
+	}
+	return obj
+}
+
+// stub implementations so *lazyObject implements Object and we can
+// store them directly into Scope.elems.
+func (*lazyObject) Parent() *Scope                        { panic("unreachable") }
+func (*lazyObject) Pos() syntax.Pos                       { panic("unreachable") }
+func (*lazyObject) Pkg() *Package                         { panic("unreachable") }
+func (*lazyObject) Name() string                          { panic("unreachable") }
+func (*lazyObject) Type() Type                            { panic("unreachable") }
+func (*lazyObject) Exported() bool                        { panic("unreachable") }
+func (*lazyObject) Id() string                            { panic("unreachable") }
+func (*lazyObject) String() string                        { panic("unreachable") }
+func (*lazyObject) order() uint32                         { panic("unreachable") }
+func (*lazyObject) color() color                          { panic("unreachable") }
+func (*lazyObject) setType(Type)                          { panic("unreachable") }
+func (*lazyObject) setOrder(uint32)                       { panic("unreachable") }
+func (*lazyObject) setColor(color color)                  { panic("unreachable") }
+func (*lazyObject) setParent(*Scope)                      { panic("unreachable") }
+func (*lazyObject) sameId(pkg *Package, name string) bool { panic("unreachable") }
+func (*lazyObject) scopePos() syntax.Pos                  { panic("unreachable") }
+func (*lazyObject) setScopePos(pos syntax.Pos)            { panic("unreachable") }
diff --git a/src/cmd/compile/internal/types2/signature.go b/src/cmd/compile/internal/types2/signature.go
new file mode 100644
index 0000000..48b11b2
--- /dev/null
+++ b/src/cmd/compile/internal/types2/signature.go
@@ -0,0 +1,393 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"cmd/compile/internal/syntax"
+	"fmt"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Signature represents a (non-builtin) function or method type.
+// The receiver is ignored when comparing signatures for identity.
+type Signature struct {
+	// We need to keep the scope in Signature (rather than passing it around
+	// and store it in the Func Object) because when type-checking a function
+	// literal we call the general type checker which returns a general Type.
+	// We then unpack the *Signature and use the scope for the literal body.
+	rparams  *TypeParams // receiver type parameters from left to right, or nil
+	tparams  *TypeParams // type parameters from left to right, or nil
+	scope    *Scope      // function scope, present for package-local signatures
+	recv     *Var        // nil if not a method
+	params   *Tuple      // (incoming) parameters from left to right; or nil
+	results  *Tuple      // (outgoing) results from left to right; or nil
+	variadic bool        // true if the last parameter's type is of the form ...T (or string, for append built-in only)
+}
+
+// NewSignature returns a new function type for the given receiver, parameters,
+// and results, either of which may be nil. If variadic is set, the function
+// is variadic, it must have at least one parameter, and the last parameter
+// must be of unnamed slice type.
+func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
+	if variadic {
+		n := params.Len()
+		if n == 0 {
+			panic("variadic function must have at least one parameter")
+		}
+		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
+			panic("variadic parameter must be of unnamed slice type")
+		}
+	}
+	return &Signature{recv: recv, params: params, results: results, variadic: variadic}
+}
+
+// Recv returns the receiver of signature s (if a method), or nil if a
+// function. It is ignored when comparing signatures for identity.
+//
+// For an abstract method, Recv returns the enclosing interface either
+// as a *Named or an *Interface. Due to embedding, an interface may
+// contain methods whose receiver type is a different interface.
+func (s *Signature) Recv() *Var { return s.recv }
+
+// TParams returns the type parameters of signature s, or nil.
+func (s *Signature) TParams() *TypeParams { return s.tparams }
+
+// SetTParams sets the type parameters of signature s.
+func (s *Signature) SetTParams(tparams []*TypeName) { s.tparams = bindTParams(tparams) }
+
+// RParams returns the receiver type parameters of signature s, or nil.
+func (s *Signature) RParams() *TypeParams { return s.rparams }
+
+// SetRParams sets the receiver type params of signature s.
+func (s *Signature) SetRParams(rparams []*TypeName) { s.rparams = bindTParams(rparams) }
+
+// Params returns the parameters of signature s, or nil.
+func (s *Signature) Params() *Tuple { return s.params }
+
+// Results returns the results of signature s, or nil.
+func (s *Signature) Results() *Tuple { return s.results }
+
+// Variadic reports whether the signature s is variadic.
+func (s *Signature) Variadic() bool { return s.variadic }
+
+func (s *Signature) Underlying() Type { return s }
+func (s *Signature) String() string   { return TypeString(s, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// Disabled by default, but enabled when running tests (via types_test.go).
+var acceptMethodTypeParams bool
+
+// funcType type-checks a function or method type.
+func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []*syntax.Field, ftyp *syntax.FuncType) {
+	check.openScope(ftyp, "function")
+	check.scope.isFunc = true
+	check.recordScope(ftyp, check.scope)
+	sig.scope = check.scope
+	defer check.closeScope()
+
+	var recvTyp syntax.Expr // rewritten receiver type; valid if != nil
+	if recvPar != nil {
+		// collect generic receiver type parameters, if any
+		// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
+		// - the receiver specification acts as local declaration for its type parameters, which may be blank
+		_, rname, rparams := check.unpackRecv(recvPar.Type, true)
+		if len(rparams) > 0 {
+			// Blank identifiers don't get declared and regular type-checking of the instantiated
+			// parameterized receiver type expression fails in Checker.collectParams of receiver.
+			// Identify blank type parameters and substitute each with a unique new identifier named
+			// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
+			// name.
+			var smap map[*syntax.Name]*syntax.Name // substitution map from "_" to "!n" identifiers
+			for i, p := range rparams {
+				if p.Value == "_" {
+					new := *p
+					new.Value = fmt.Sprintf("%d_", i)
+					rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
+					if smap == nil {
+						smap = make(map[*syntax.Name]*syntax.Name)
+					}
+					smap[p] = &new
+				}
+			}
+			if smap != nil {
+				// blank identifiers were found => use rewritten receiver type
+				recvTyp = isubst(recvPar.Type, smap)
+			}
+			rlist := make([]*TypeName, len(rparams))
+			for i, rparam := range rparams {
+				rlist[i] = check.declareTypeParam(rparam)
+			}
+			sig.rparams = bindTParams(rlist)
+			// determine receiver type to get its type parameters
+			// and the respective type parameter bounds
+			var recvTParams []*TypeName
+			if rname != nil {
+				// recv should be a Named type (otherwise an error is reported elsewhere)
+				// Also: Don't report an error via genericType since it will be reported
+				//       again when we type-check the signature.
+				// TODO(gri) maybe the receiver should be marked as invalid instead?
+				if recv := asNamed(check.genericType(rname, false)); recv != nil {
+					recvTParams = recv.TParams().list()
+				}
+			}
+			// provide type parameter bounds
+			// - only do this if we have the right number (otherwise an error is reported elsewhere)
+			if sig.RParams().Len() == len(recvTParams) {
+				// We have a list of *TypeNames but we need a list of Types.
+				list := make([]Type, sig.RParams().Len())
+				for i, t := range sig.RParams().list() {
+					list[i] = t.typ
+				}
+				smap := makeSubstMap(recvTParams, list)
+				for i, tname := range sig.RParams().list() {
+					bound := recvTParams[i].typ.(*TypeParam).bound
+					// bound is (possibly) parameterized in the context of the
+					// receiver type declaration. Substitute parameters for the
+					// current context.
+					// TODO(gri) should we assume now that bounds always exist?
+					//           (no bound == empty interface)
+					if bound != nil {
+						bound = check.subst(tname.pos, bound, smap)
+						tname.typ.(*TypeParam).bound = bound
+					}
+				}
+			}
+		}
+	}
+
+	if tparams != nil {
+		sig.tparams = check.collectTypeParams(tparams)
+		// Always type-check method type parameters but complain if they are not enabled.
+		// (A separate check is needed when type-checking interface method signatures because
+		// they don't have a receiver specification.)
+		if recvPar != nil && !acceptMethodTypeParams {
+			check.error(ftyp, "methods cannot have type parameters")
+		}
+	}
+
+	// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
+	// declarations and then squash that scope into the parent scope (and report any redeclarations at
+	// that time).
+	scope := NewScope(check.scope, nopos, nopos, "function body (temp. scope)")
+	var recvList []*Var // TODO(gri) remove the need for making a list here
+	if recvPar != nil {
+		recvList, _ = check.collectParams(scope, []*syntax.Field{recvPar}, recvTyp, false) // use rewritten receiver type, if any
+	}
+	params, variadic := check.collectParams(scope, ftyp.ParamList, nil, true)
+	results, _ := check.collectParams(scope, ftyp.ResultList, nil, false)
+	scope.Squash(func(obj, alt Object) {
+		var err error_
+		err.errorf(obj, "%s redeclared in this block", obj.Name())
+		err.recordAltDecl(alt)
+		check.report(&err)
+	})
+
+	if recvPar != nil {
+		// recv parameter list present (may be empty)
+		// spec: "The receiver is specified via an extra parameter section preceding the
+		// method name. That parameter section must declare a single parameter, the receiver."
+		var recv *Var
+		switch len(recvList) {
+		case 0:
+			// error reported by resolver
+			recv = NewParam(nopos, nil, "", Typ[Invalid]) // ignore recv below
+		default:
+			// more than one receiver
+			check.error(recvList[len(recvList)-1].Pos(), "method must have exactly one receiver")
+			fallthrough // continue with first receiver
+		case 1:
+			recv = recvList[0]
+		}
+
+		// TODO(gri) We should delay rtyp expansion to when we actually need the
+		//           receiver; thus all checks here should be delayed to later.
+		rtyp, _ := deref(recv.typ)
+
+		// spec: "The receiver type must be of the form T or *T where T is a type name."
+		// (ignore invalid types - error was reported before)
+		if rtyp != Typ[Invalid] {
+			var err string
+			switch T := rtyp.(type) {
+			case *Named:
+				T.expand()
+				// spec: "The type denoted by T is called the receiver base type; it must not
+				// be a pointer or interface type and it must be declared in the same package
+				// as the method."
+				if T.obj.pkg != check.pkg {
+					err = "type not defined in this package"
+					if check.conf.CompilerErrorMessages {
+						check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
+						err = ""
+					}
+				} else {
+					// The underlying type of a receiver base type can be a type parameter;
+					// e.g. for methods with a generic receiver T[P] with type T[P any] P.
+					underIs(T, func(u Type) bool {
+						switch u := u.(type) {
+						case *Basic:
+							// unsafe.Pointer is treated like a regular pointer
+							if u.kind == UnsafePointer {
+								err = "unsafe.Pointer"
+								return false
+							}
+						case *Pointer, *Interface:
+							err = "pointer or interface type"
+							return false
+						}
+						return true
+					})
+				}
+			case *Basic:
+				err = "basic or unnamed type"
+				if check.conf.CompilerErrorMessages {
+					check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
+					err = ""
+				}
+			default:
+				check.errorf(recv.pos, "invalid receiver type %s", recv.typ)
+			}
+			if err != "" {
+				check.errorf(recv.pos, "invalid receiver type %s (%s)", recv.typ, err)
+				// ok to continue
+			}
+		}
+		sig.recv = recv
+	}
+
+	sig.params = NewTuple(params...)
+	sig.results = NewTuple(results...)
+	sig.variadic = variadic
+}
+
+// collectParams declares the parameters of list in scope and returns the corresponding
+// variable list. If type0 != nil, it is used instead of the first type in list.
+func (check *Checker) collectParams(scope *Scope, list []*syntax.Field, type0 syntax.Expr, variadicOk bool) (params []*Var, variadic bool) {
+	if list == nil {
+		return
+	}
+
+	var named, anonymous bool
+
+	var typ Type
+	var prev syntax.Expr
+	for i, field := range list {
+		ftype := field.Type
+		// type-check type of grouped fields only once
+		if ftype != prev {
+			prev = ftype
+			if i == 0 && type0 != nil {
+				ftype = type0
+			}
+			if t, _ := ftype.(*syntax.DotsType); t != nil {
+				ftype = t.Elem
+				if variadicOk && i == len(list)-1 {
+					variadic = true
+				} else {
+					check.softErrorf(t, "can only use ... with final parameter in list")
+					// ignore ... and continue
+				}
+			}
+			typ = check.varType(ftype)
+		}
+		// The parser ensures that f.Tag is nil and we don't
+		// care if a constructed AST contains a non-nil tag.
+		if field.Name != nil {
+			// named parameter
+			name := field.Name.Value
+			if name == "" {
+				check.error(field.Name, invalidAST+"anonymous parameter")
+				// ok to continue
+			}
+			par := NewParam(field.Name.Pos(), check.pkg, name, typ)
+			check.declare(scope, field.Name, par, scope.pos)
+			params = append(params, par)
+			named = true
+		} else {
+			// anonymous parameter
+			par := NewParam(field.Pos(), check.pkg, "", typ)
+			check.recordImplicit(field, par)
+			params = append(params, par)
+			anonymous = true
+		}
+	}
+
+	if named && anonymous {
+		check.error(list[0], invalidAST+"list contains both named and anonymous parameters")
+		// ok to continue
+	}
+
+	// For a variadic function, change the last parameter's type from T to []T.
+	// Since we type-checked T rather than ...T, we also need to retro-actively
+	// record the type for ...T.
+	if variadic {
+		last := params[len(params)-1]
+		last.typ = &Slice{elem: last.typ}
+		check.recordTypeAndValue(list[len(list)-1].Type, typexpr, last.typ, nil)
+	}
+
+	return
+}
+
+// isubst returns an x with identifiers substituted per the substitution map smap.
+// isubst only handles the case of (valid) method receiver type expressions correctly.
+func isubst(x syntax.Expr, smap map[*syntax.Name]*syntax.Name) syntax.Expr {
+	switch n := x.(type) {
+	case *syntax.Name:
+		if alt := smap[n]; alt != nil {
+			return alt
+		}
+	// case *syntax.StarExpr:
+	// 	X := isubst(n.X, smap)
+	// 	if X != n.X {
+	// 		new := *n
+	// 		new.X = X
+	// 		return &new
+	// 	}
+	case *syntax.Operation:
+		if n.Op == syntax.Mul && n.Y == nil {
+			X := isubst(n.X, smap)
+			if X != n.X {
+				new := *n
+				new.X = X
+				return &new
+			}
+		}
+	case *syntax.IndexExpr:
+		Index := isubst(n.Index, smap)
+		if Index != n.Index {
+			new := *n
+			new.Index = Index
+			return &new
+		}
+	case *syntax.ListExpr:
+		var elems []syntax.Expr
+		for i, elem := range n.ElemList {
+			new := isubst(elem, smap)
+			if new != elem {
+				if elems == nil {
+					elems = make([]syntax.Expr, len(n.ElemList))
+					copy(elems, n.ElemList)
+				}
+				elems[i] = new
+			}
+		}
+		if elems != nil {
+			new := *n
+			new.ElemList = elems
+			return &new
+		}
+	case *syntax.ParenExpr:
+		return isubst(n.X, smap) // no need to keep parentheses
+	default:
+		// Other receiver type expressions are invalid.
+		// It's fine to ignore those here as they will
+		// be checked elsewhere.
+	}
+	return x
+}
diff --git a/src/cmd/compile/internal/types2/sizeof_test.go b/src/cmd/compile/internal/types2/sizeof_test.go
index 236feb0..d2f5325 100644
--- a/src/cmd/compile/internal/types2/sizeof_test.go
+++ b/src/cmd/compile/internal/types2/sizeof_test.go
@@ -26,15 +26,14 @@
 		{Struct{}, 24, 48},
 		{Pointer{}, 8, 16},
 		{Tuple{}, 12, 24},
-		{Signature{}, 44, 88},
-		{Sum{}, 12, 24},
-		{Interface{}, 60, 120},
+		{Signature{}, 28, 56},
+		{Union{}, 16, 32},
+		{Interface{}, 40, 80},
 		{Map{}, 16, 32},
 		{Chan{}, 12, 24},
-		{Named{}, 68, 136},
+		{Named{}, 80, 152},
 		{TypeParam{}, 28, 48},
-		{instance{}, 52, 96},
-		{bottom{}, 0, 0},
+		{term{}, 12, 24},
 		{top{}, 0, 0},
 
 		// Objects
@@ -48,8 +47,9 @@
 		{Nil{}, 56, 88},
 
 		// Misc
-		{Scope{}, 56, 96},
+		{Scope{}, 60, 104},
 		{Package{}, 40, 80},
+		{TypeSet{}, 28, 56},
 	}
 
 	for _, test := range tests {
diff --git a/src/cmd/compile/internal/types2/sizes.go b/src/cmd/compile/internal/types2/sizes.go
index aa0fbf4..6a3d19d 100644
--- a/src/cmd/compile/internal/types2/sizes.go
+++ b/src/cmd/compile/internal/types2/sizes.go
@@ -48,7 +48,7 @@
 func (s *StdSizes) Alignof(T Type) int64 {
 	// For arrays and structs, alignment is defined in terms
 	// of alignment of the elements and fields, respectively.
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Array:
 		// spec: "For a variable x of array type: unsafe.Alignof(x)
 		// is the same as unsafe.Alignof(x[0]), but at least 1."
@@ -73,6 +73,8 @@
 		if t.Info()&IsString != 0 {
 			return s.WordSize
 		}
+	case *TypeParam, *Union:
+		unreachable()
 	}
 	a := s.Sizeof(T) // may be 0
 	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
@@ -118,7 +120,7 @@
 }
 
 func (s *StdSizes) Sizeof(T Type) int64 {
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Basic:
 		assert(isTyped(T))
 		k := t.kind
@@ -148,10 +150,10 @@
 		}
 		offsets := s.Offsetsof(t.fields)
 		return offsets[n-1] + s.Sizeof(t.fields[n-1].typ)
-	case *Sum:
-		panic("Sizeof unimplemented for type sum")
 	case *Interface:
 		return s.WordSize * 2
+	case *TypeParam, *Union:
+		unreachable()
 	}
 	return s.WordSize // catch-all
 }
diff --git a/src/cmd/compile/internal/types2/slice.go b/src/cmd/compile/internal/types2/slice.go
new file mode 100644
index 0000000..9c22a6f
--- /dev/null
+++ b/src/cmd/compile/internal/types2/slice.go
@@ -0,0 +1,19 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Slice represents a slice type.
+type Slice struct {
+	elem Type
+}
+
+// NewSlice returns a new slice type for the given element type.
+func NewSlice(elem Type) *Slice { return &Slice{elem: elem} }
+
+// Elem returns the element type of slice s.
+func (s *Slice) Elem() Type { return s.elem }
+
+func (s *Slice) Underlying() Type { return s }
+func (s *Slice) String() string   { return TypeString(s, nil) }
diff --git a/src/cmd/compile/internal/types2/stmt.go b/src/cmd/compile/internal/types2/stmt.go
index c3e646c..7865c2d 100644
--- a/src/cmd/compile/internal/types2/stmt.go
+++ b/src/cmd/compile/internal/types2/stmt.go
@@ -14,7 +14,7 @@
 
 func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body *syntax.BlockStmt, iota constant.Value) {
 	if check.conf.IgnoreFuncBodies {
-		panic("internal error: function body not ignored")
+		panic("function body not ignored")
 	}
 
 	if check.conf.Trace {
@@ -64,7 +64,8 @@
 
 func (check *Checker) usage(scope *Scope) {
 	var unused []*Var
-	for _, elem := range scope.elems {
+	for name, elem := range scope.elems {
+		elem = resolve(name, elem)
 		if v, _ := elem.(*Var); v != nil && !v.used {
 			unused = append(unused, v)
 		}
@@ -255,7 +256,7 @@
 			// look for duplicate types for a given value
 			// (quadratic algorithm, but these lists tend to be very short)
 			for _, vt := range seen[val] {
-				if check.identical(v.typ, vt.typ) {
+				if Identical(v.typ, vt.typ) {
 					var err error_
 					err.errorf(&v, "duplicate case %s in expression switch", &v)
 					err.errorf(vt.pos, "previous case")
@@ -281,7 +282,7 @@
 		// look for duplicate types
 		// (quadratic algorithm, but type switches tend to be reasonably small)
 		for t, other := range seen {
-			if T == nil && t == nil || T != nil && t != nil && check.identical(T, t) {
+			if T == nil && t == nil || T != nil && t != nil && Identical(T, t) {
 				// talk about "case" rather than "type" because of nil case
 				Ts := "nil"
 				if T != nil {
@@ -351,25 +352,33 @@
 		check.errorf(&x, "%s %s", &x, msg)
 
 	case *syntax.SendStmt:
-		var ch, x operand
+		var ch, val operand
 		check.expr(&ch, s.Chan)
-		check.expr(&x, s.Value)
-		if ch.mode == invalid || x.mode == invalid {
+		check.expr(&val, s.Value)
+		if ch.mode == invalid || val.mode == invalid {
 			return
 		}
-
-		tch := asChan(ch.typ)
-		if tch == nil {
-			check.errorf(s, invalidOp+"cannot send to non-chan type %s", ch.typ)
+		var elem Type
+		if !underIs(ch.typ, func(u Type) bool {
+			uch, _ := u.(*Chan)
+			if uch == nil {
+				check.errorf(s, invalidOp+"cannot send to non-channel %s", &ch)
+				return false
+			}
+			if uch.dir == RecvOnly {
+				check.errorf(s, invalidOp+"cannot send to receive-only channel %s", &ch)
+				return false
+			}
+			if elem != nil && !Identical(uch.elem, elem) {
+				check.errorf(s, invalidOp+"channels of %s must have the same element type", &ch)
+				return false
+			}
+			elem = uch.elem
+			return true
+		}) {
 			return
 		}
-
-		if tch.dir == RecvOnly {
-			check.errorf(s, invalidOp+"cannot send to receive-only type %s", tch)
-			return
-		}
-
-		check.assignment(&x, tch.elem, "send")
+		check.assignment(&val, elem, "send")
 
 	case *syntax.AssignStmt:
 		lhs := unpackExpr(s.Lhs)
@@ -780,9 +789,9 @@
 	// determine key/value types
 	var key, val Type
 	if x.mode != invalid {
+		// Ranging over a type parameter is permitted if it has a structural type.
 		typ := optype(x.typ)
 		if _, ok := typ.(*Chan); ok && sValue != nil {
-			// TODO(gri) this also needs to happen for channels in generic variables
 			check.softErrorf(sValue, "range over %s permits only one iteration variable", &x)
 			// ok to continue
 		}
@@ -891,7 +900,7 @@
 // variables are used or present; this matters if we range over a generic
 // type where not all keys or values are of the same type.
 func rangeKeyVal(typ Type, wantKey, wantVal bool) (Type, Type, string) {
-	switch typ := typ.(type) {
+	switch typ := arrayPtrDeref(typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			return Typ[Int], universeRune, "" // use 'rune' name
@@ -900,10 +909,6 @@
 		return Typ[Int], typ.elem, ""
 	case *Slice:
 		return Typ[Int], typ.elem, ""
-	case *Pointer:
-		if typ := asArray(typ.base); typ != nil {
-			return Typ[Int], typ.elem, ""
-		}
 	case *Map:
 		return typ.key, typ.elem, ""
 	case *Chan:
@@ -912,32 +917,9 @@
 			msg = "receive from send-only channel"
 		}
 		return typ.elem, Typ[Invalid], msg
-	case *Sum:
-		first := true
-		var key, val Type
-		var msg string
-		typ.is(func(t Type) bool {
-			k, v, m := rangeKeyVal(under(t), wantKey, wantVal)
-			if k == nil || m != "" {
-				key, val, msg = k, v, m
-				return false
-			}
-			if first {
-				key, val, msg = k, v, m
-				first = false
-				return true
-			}
-			if wantKey && !Identical(key, k) {
-				key, val, msg = nil, nil, "all possible values must have the same key type"
-				return false
-			}
-			if wantVal && !Identical(val, v) {
-				key, val, msg = nil, nil, "all possible values must have the same element type"
-				return false
-			}
-			return true
-		})
-		return key, val, msg
+	case *top:
+		// we have a type parameter with no structural type
+		return nil, nil, "no structural type"
 	}
 	return nil, nil, ""
 }
diff --git a/src/cmd/compile/internal/types2/struct.go b/src/cmd/compile/internal/types2/struct.go
new file mode 100644
index 0000000..f0c27c0
--- /dev/null
+++ b/src/cmd/compile/internal/types2/struct.go
@@ -0,0 +1,213 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"cmd/compile/internal/syntax"
+	"strconv"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Struct represents a struct type.
+type Struct struct {
+	fields []*Var
+	tags   []string // field tags; nil if there are no tags
+}
+
+// NewStruct returns a new struct with the given fields and corresponding field tags.
+// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
+// only as long as required to hold the tag with the largest index i. Consequently,
+// if no field has a tag, tags may be nil.
+func NewStruct(fields []*Var, tags []string) *Struct {
+	var fset objset
+	for _, f := range fields {
+		if f.name != "_" && fset.insert(f) != nil {
+			panic("multiple fields with the same name")
+		}
+	}
+	if len(tags) > len(fields) {
+		panic("more tags than fields")
+	}
+	return &Struct{fields: fields, tags: tags}
+}
+
+// NumFields returns the number of fields in the struct (including blank and embedded fields).
+func (s *Struct) NumFields() int { return len(s.fields) }
+
+// Field returns the i'th field for 0 <= i < NumFields().
+func (s *Struct) Field(i int) *Var { return s.fields[i] }
+
+// Tag returns the i'th field tag for 0 <= i < NumFields().
+func (s *Struct) Tag(i int) string {
+	if i < len(s.tags) {
+		return s.tags[i]
+	}
+	return ""
+}
+
+func (s *Struct) Underlying() Type { return s }
+func (s *Struct) String() string   { return TypeString(s, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (check *Checker) structType(styp *Struct, e *syntax.StructType) {
+	if e.FieldList == nil {
+		return
+	}
+
+	// struct fields and tags
+	var fields []*Var
+	var tags []string
+
+	// for double-declaration checks
+	var fset objset
+
+	// current field typ and tag
+	var typ Type
+	var tag string
+	add := func(ident *syntax.Name, embedded bool, pos syntax.Pos) {
+		if tag != "" && tags == nil {
+			tags = make([]string, len(fields))
+		}
+		if tags != nil {
+			tags = append(tags, tag)
+		}
+
+		name := ident.Value
+		fld := NewField(pos, check.pkg, name, typ, embedded)
+		// spec: "Within a struct, non-blank field names must be unique."
+		if name == "_" || check.declareInSet(&fset, pos, fld) {
+			fields = append(fields, fld)
+			check.recordDef(ident, fld)
+		}
+	}
+
+	// addInvalid adds an embedded field of invalid type to the struct for
+	// fields with errors; this keeps the number of struct fields in sync
+	// with the source as long as the fields are _ or have different names
+	// (issue #25627).
+	addInvalid := func(ident *syntax.Name, pos syntax.Pos) {
+		typ = Typ[Invalid]
+		tag = ""
+		add(ident, true, pos)
+	}
+
+	var prev syntax.Expr
+	for i, f := range e.FieldList {
+		// Fields declared syntactically with the same type (e.g.: a, b, c T)
+		// share the same type expression. Only check type if it's a new type.
+		if i == 0 || f.Type != prev {
+			typ = check.varType(f.Type)
+			prev = f.Type
+		}
+		tag = ""
+		if i < len(e.TagList) {
+			tag = check.tag(e.TagList[i])
+		}
+		if f.Name != nil {
+			// named field
+			add(f.Name, false, f.Name.Pos())
+		} else {
+			// embedded field
+			// spec: "An embedded type must be specified as a type name T or as a
+			// pointer to a non-interface type name *T, and T itself may not be a
+			// pointer type."
+			pos := syntax.StartPos(f.Type)
+			name := embeddedFieldIdent(f.Type)
+			if name == nil {
+				check.errorf(pos, "invalid embedded field type %s", f.Type)
+				name = &syntax.Name{Value: "_"} // TODO(gri) need to set position to pos
+				addInvalid(name, pos)
+				continue
+			}
+			add(name, true, pos)
+
+			// Because we have a name, typ must be of the form T or *T, where T is the name
+			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
+			// We must delay this check to the end because we don't want to instantiate
+			// (via under(t)) a possibly incomplete type.
+			embeddedTyp := typ // for closure below
+			embeddedPos := pos
+			check.later(func() {
+				t, isPtr := deref(embeddedTyp)
+				switch t := under(t).(type) {
+				case *Basic:
+					if t == Typ[Invalid] {
+						// error was reported before
+						return
+					}
+					// unsafe.Pointer is treated like a regular pointer
+					if t.kind == UnsafePointer {
+						check.error(embeddedPos, "embedded field type cannot be unsafe.Pointer")
+					}
+				case *Pointer:
+					check.error(embeddedPos, "embedded field type cannot be a pointer")
+				case *TypeParam:
+					check.error(embeddedPos, "embedded field type cannot be a (pointer to a) type parameter")
+				case *Interface:
+					if isPtr {
+						check.error(embeddedPos, "embedded field type cannot be a pointer to an interface")
+					}
+				}
+			})
+		}
+	}
+
+	styp.fields = fields
+	styp.tags = tags
+}
+
+func embeddedFieldIdent(e syntax.Expr) *syntax.Name {
+	switch e := e.(type) {
+	case *syntax.Name:
+		return e
+	case *syntax.Operation:
+		if base := ptrBase(e); base != nil {
+			// *T is valid, but **T is not
+			if op, _ := base.(*syntax.Operation); op == nil || ptrBase(op) == nil {
+				return embeddedFieldIdent(e.X)
+			}
+		}
+	case *syntax.SelectorExpr:
+		return e.Sel
+	case *syntax.IndexExpr:
+		return embeddedFieldIdent(e.X)
+	}
+	return nil // invalid embedded field
+}
+
+func (check *Checker) declareInSet(oset *objset, pos syntax.Pos, obj Object) bool {
+	if alt := oset.insert(obj); alt != nil {
+		var err error_
+		err.errorf(pos, "%s redeclared", obj.Name())
+		err.recordAltDecl(alt)
+		check.report(&err)
+		return false
+	}
+	return true
+}
+
+func (check *Checker) tag(t *syntax.BasicLit) string {
+	// If t.Bad, an error was reported during parsing.
+	if t != nil && !t.Bad {
+		if t.Kind == syntax.StringLit {
+			if val, err := strconv.Unquote(t.Value); err == nil {
+				return val
+			}
+		}
+		check.errorf(t, invalidAST+"incorrect tag syntax: %q", t.Value)
+	}
+	return ""
+}
+
+func ptrBase(x *syntax.Operation) syntax.Expr {
+	if x.Op == syntax.Mul && x.Y == nil {
+		return x.X
+	}
+	return nil
+}
diff --git a/src/cmd/compile/internal/types2/subst.go b/src/cmd/compile/internal/types2/subst.go
index c8e428c..26796fc 100644
--- a/src/cmd/compile/internal/types2/subst.go
+++ b/src/cmd/compile/internal/types2/subst.go
@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This file implements instantiation of generic types
-// through substitution of type parameters by actual
-// types.
+// This file implements type parameter substitution.
 
 package types2
 
@@ -28,12 +26,7 @@
 	assert(len(tpars) == len(targs))
 	proj := make(map[*TypeParam]Type, len(tpars))
 	for i, tpar := range tpars {
-		// We must expand type arguments otherwise *instance
-		// types end up as components in composite types.
-		// TODO(gri) explain why this causes problems, if it does
-		targ := expand(targs[i]) // possibly nil
-		targs[i] = targ
-		proj[tpar.typ.(*TypeParam)] = targ
+		proj[tpar.typ.(*TypeParam)] = targs[i]
 	}
 	return &substMap{targs, proj}
 }
@@ -53,158 +46,6 @@
 	return tpar
 }
 
-func (check *Checker) instantiate(pos syntax.Pos, typ Type, targs []Type, poslist []syntax.Pos) (res Type) {
-	if check.conf.Trace {
-		check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
-		check.indent++
-		defer func() {
-			check.indent--
-			var under Type
-			if res != nil {
-				// Calling under() here may lead to endless instantiations.
-				// Test case: type T[P any] T[P]
-				// TODO(gri) investigate if that's a bug or to be expected.
-				under = res.Underlying()
-			}
-			check.trace(pos, "=> %s (under = %s)", res, under)
-		}()
-	}
-
-	assert(len(poslist) <= len(targs))
-
-	// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
-	var tparams []*TypeName
-	switch t := typ.(type) {
-	case *Named:
-		tparams = t.tparams
-	case *Signature:
-		tparams = t.tparams
-		defer func() {
-			// If we had an unexpected failure somewhere don't panic below when
-			// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
-			// is returned.
-			if _, ok := res.(*Signature); !ok {
-				return
-			}
-			// If the signature doesn't use its type parameters, subst
-			// will not make a copy. In that case, make a copy now (so
-			// we can set tparams to nil w/o causing side-effects).
-			if t == res {
-				copy := *t
-				res = &copy
-			}
-			// After instantiating a generic signature, it is not generic
-			// anymore; we need to set tparams to nil.
-			res.(*Signature).tparams = nil
-		}()
-
-	default:
-		check.dump("%v: cannot instantiate %v", pos, typ)
-		unreachable() // only defined types and (defined) functions can be generic
-
-	}
-
-	// the number of supplied types must match the number of type parameters
-	if len(targs) != len(tparams) {
-		// TODO(gri) provide better error message
-		check.errorf(pos, "got %d arguments but %d type parameters", len(targs), len(tparams))
-		return Typ[Invalid]
-	}
-
-	if len(tparams) == 0 {
-		return typ // nothing to do (minor optimization)
-	}
-
-	smap := makeSubstMap(tparams, targs)
-
-	// check bounds
-	for i, tname := range tparams {
-		tpar := tname.typ.(*TypeParam)
-		iface := tpar.Bound()
-		if iface.Empty() {
-			continue // no type bound
-		}
-
-		targ := targs[i]
-
-		// best position for error reporting
-		pos := pos
-		if i < len(poslist) {
-			pos = poslist[i]
-		}
-
-		// The type parameter bound is parameterized with the same type parameters
-		// as the instantiated type; before we can use it for bounds checking we
-		// need to instantiate it with the type arguments with which we instantiate
-		// the parameterized type.
-		iface = check.subst(pos, iface, smap).(*Interface)
-
-		// targ must implement iface (methods)
-		// - check only if we have methods
-		check.completeInterface(nopos, iface)
-		if len(iface.allMethods) > 0 {
-			// If the type argument is a pointer to a type parameter, the type argument's
-			// method set is empty.
-			// TODO(gri) is this what we want? (spec question)
-			if base, isPtr := deref(targ); isPtr && asTypeParam(base) != nil {
-				check.errorf(pos, "%s has no methods", targ)
-				break
-			}
-			if m, wrong := check.missingMethod(targ, iface, true); m != nil {
-				// TODO(gri) needs to print updated name to avoid major confusion in error message!
-				//           (print warning for now)
-				// Old warning:
-				// check.softErrorf(pos, "%s does not satisfy %s (warning: name not updated) = %s (missing method %s)", targ, tpar.bound, iface, m)
-				if m.name == "==" {
-					// We don't want to report "missing method ==".
-					check.softErrorf(pos, "%s does not satisfy comparable", targ)
-				} else if wrong != nil {
-					// TODO(gri) This can still report uninstantiated types which makes the error message
-					//           more difficult to read then necessary.
-					check.softErrorf(pos,
-						"%s does not satisfy %s: wrong method signature\n\tgot  %s\n\twant %s",
-						targ, tpar.bound, wrong, m,
-					)
-				} else {
-					check.softErrorf(pos, "%s does not satisfy %s (missing method %s)", targ, tpar.bound, m.name)
-				}
-				break
-			}
-		}
-
-		// targ's underlying type must also be one of the interface types listed, if any
-		if iface.allTypes == nil {
-			continue // nothing to do
-		}
-
-		// If targ is itself a type parameter, each of its possible types, but at least one, must be in the
-		// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
-		if targ := asTypeParam(targ); targ != nil {
-			targBound := targ.Bound()
-			if targBound.allTypes == nil {
-				check.softErrorf(pos, "%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
-				break
-			}
-			for _, t := range unpack(targBound.allTypes) {
-				if !iface.isSatisfiedBy(t) {
-					// TODO(gri) match this error message with the one below (or vice versa)
-					check.softErrorf(pos, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, t, iface.allTypes)
-					break
-				}
-			}
-			break
-		}
-
-		// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
-		if !iface.isSatisfiedBy(targ) {
-			check.softErrorf(pos, "%s does not satisfy %s (%s not found in %s)", targ, tpar.bound, under(targ), iface.allTypes)
-			break
-		}
-	}
-
-	return check.subst(pos, typ, smap)
-}
-
 // subst returns the type typ with its type parameters tpars replaced by
 // the corresponding type arguments targs, recursively.
 // subst is functional in the sense that it doesn't modify the incoming
@@ -224,15 +65,28 @@
 	}
 
 	// general case
-	subst := subster{check, pos, make(map[Type]Type), smap}
+	var subst subster
+	subst.pos = pos
+	subst.smap = smap
+	if check != nil {
+		subst.check = check
+		subst.typMap = check.typMap
+	} else {
+		// If we don't have a *Checker and its global type map,
+		// use a local version. Besides avoiding duplicate work,
+		// the type map prevents infinite recursive substitution
+		// for recursive types (example: type T[P any] *T[P]).
+		subst.typMap = make(map[string]*Named)
+	}
+
 	return subst.typ(typ)
 }
 
 type subster struct {
-	check *Checker
-	pos   syntax.Pos
-	cache map[Type]Type
-	smap  *substMap
+	pos    syntax.Pos
+	smap   *substMap
+	check  *Checker // nil if called via Instantiate
+	typMap map[string]*Named
 }
 
 func (subst *subster) typ(typ Type) Type {
@@ -241,7 +95,7 @@
 		// Call typOrNil if it's possible that typ is nil.
 		panic("nil typ")
 
-	case *Basic, *bottom, *top:
+	case *Basic, *top:
 		// nothing to do
 
 	case *Array:
@@ -290,29 +144,20 @@
 			}
 		}
 
-	case *Sum:
-		types, copied := subst.typeList(t.types)
+	case *Union:
+		terms, copied := subst.termlist(t.terms)
 		if copied {
-			// Don't do it manually, with a Sum literal: the new
-			// types list may not be unique and NewSum may remove
-			// duplicates.
-			return NewSum(types)
+			// term list substitution may introduce duplicate terms (unlikely but possible).
+			// This is ok; lazy type set computation will determine the actual type set
+			// in normal form.
+			return &Union{terms, nil}
 		}
 
 	case *Interface:
 		methods, mcopied := subst.funcList(t.methods)
-		types := t.types
-		if t.types != nil {
-			types = subst.typ(t.types)
-		}
 		embeddeds, ecopied := subst.typeList(t.embeddeds)
-		if mcopied || types != t.types || ecopied {
-			iface := &Interface{methods: methods, types: types, embeddeds: embeddeds}
-			if subst.check == nil {
-				panic("internal error: cannot instantiate interfaces yet")
-			}
-			subst.check.posMap[iface] = subst.check.posMap[t] // satisfy completeInterface requirement
-			subst.check.completeInterface(nopos, iface)
+		if mcopied || ecopied {
+			iface := &Interface{methods: methods, embeddeds: embeddeds, complete: t.complete}
 			return iface
 		}
 
@@ -342,7 +187,7 @@
 			}
 		}
 
-		if t.tparams == nil {
+		if t.TParams().Len() == 0 {
 			dump(">>> %s is not parameterized", t)
 			return t // type is not parameterized
 		}
@@ -352,7 +197,7 @@
 		if len(t.targs) > 0 {
 			// already instantiated
 			dump(">>> %s already instantiated", t)
-			assert(len(t.targs) == len(t.tparams))
+			assert(len(t.targs) == t.TParams().Len())
 			// For each (existing) type argument targ, determine if it needs
 			// to be substituted; i.e., if it is or contains a type parameter
 			// that has a type argument for it.
@@ -362,7 +207,7 @@
 				if new_targ != targ {
 					dump(">>> substituted %d targ %s => %s", i, targ, new_targ)
 					if new_targs == nil {
-						new_targs = make([]Type, len(t.tparams))
+						new_targs = make([]Type, t.TParams().Len())
 						copy(new_targs, t.targs)
 					}
 					new_targs[i] = new_targ
@@ -382,26 +227,23 @@
 		// before creating a new named type, check if we have this one already
 		h := instantiatedHash(t, new_targs)
 		dump(">>> new type hash: %s", h)
-		if subst.check != nil {
-			if named, found := subst.check.typMap[h]; found {
-				dump(">>> found %s", named)
-				subst.cache[t] = named
-				return named
-			}
+		if named, found := subst.typMap[h]; found {
+			dump(">>> found %s", named)
+			return named
 		}
 
-		// create a new named type and populate caches to avoid endless recursion
+		// create a new named type and populate typMap to avoid endless recursion
 		tname := NewTypeName(subst.pos, t.obj.pkg, t.obj.name, nil)
-		named := subst.check.newNamed(tname, t, t.underlying, t.tparams, t.methods) // method signatures are updated lazily
+		named := subst.check.newNamed(tname, t, t.Underlying(), t.TParams(), t.methods) // method signatures are updated lazily
 		named.targs = new_targs
-		if subst.check != nil {
-			subst.check.typMap[h] = named
-		}
-		subst.cache[t] = named
+		subst.typMap[h] = named
+		t.expand() // must happen after typMap update to avoid infinite recursion
 
 		// do the substitution
 		dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, new_targs)
-		named.underlying = subst.typOrNil(t.underlying)
+		named.underlying = subst.typOrNil(t.Underlying())
+		dump(">>> underlying: %v", named.underlying)
+		assert(named.underlying != nil)
 		named.fromRHS = named.underlying // for cycle detection (Checker.validType)
 
 		return named
@@ -409,10 +251,6 @@
 	case *TypeParam:
 		return subst.smap.lookup(t)
 
-	case *instance:
-		// TODO(gri) can we avoid the expansion here and just substitute the type parameters?
-		return subst.typ(t.expand())
-
 	default:
 		unimplemented()
 	}
@@ -420,14 +258,17 @@
 	return typ
 }
 
-// TODO(gri) Eventually, this should be more sophisticated.
-//           It won't work correctly for locally declared types.
+var instanceHashing = 0
+
 func instantiatedHash(typ *Named, targs []Type) string {
+	assert(instanceHashing == 0)
+	instanceHashing++
 	var buf bytes.Buffer
 	writeTypeName(&buf, typ.obj, nil)
 	buf.WriteByte('[')
 	writeTypeList(&buf, targs, nil, nil)
 	buf.WriteByte(']')
+	instanceHashing--
 
 	// With respect to the represented type, whether a
 	// type is fully expanded or stored as instance
@@ -545,3 +386,21 @@
 	}
 	return
 }
+
+func (subst *subster) termlist(in []*Term) (out []*Term, copied bool) {
+	out = in
+	for i, t := range in {
+		if u := subst.typ(t.typ); u != t.typ {
+			if !copied {
+				// first function that got substituted => allocate new out slice
+				// and copy all functions
+				new := make([]*Term, len(in))
+				copy(new, out)
+				out = new
+				copied = true
+			}
+			out[i] = NewTerm(t.tilde, u)
+		}
+	}
+	return
+}
diff --git a/src/cmd/compile/internal/types2/termlist.go b/src/cmd/compile/internal/types2/termlist.go
new file mode 100644
index 0000000..378ba6b
--- /dev/null
+++ b/src/cmd/compile/internal/types2/termlist.go
@@ -0,0 +1,167 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "bytes"
+
+// A termlist represents the type set represented by the union
+// t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
+// A termlist is in normal form if all terms are disjoint.
+// termlist operations don't require the operands to be in
+// normal form.
+type termlist []*term
+
+// allTermlist represents the set of all types.
+// It is in normal form.
+var allTermlist = termlist{new(term)}
+
+// String prints the termlist exactly (without normalization).
+func (xl termlist) String() string {
+	if len(xl) == 0 {
+		return "∅"
+	}
+	var buf bytes.Buffer
+	for i, x := range xl {
+		if i > 0 {
+			buf.WriteString(" ∪ ")
+		}
+		buf.WriteString(x.String())
+	}
+	return buf.String()
+}
+
+// isEmpty reports whether the termlist xl represents the empty set of types.
+func (xl termlist) isEmpty() bool {
+	// If there's a non-nil term, the entire list is not empty.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil {
+			return false
+		}
+	}
+	return true
+}
+
+// isAll reports whether the termlist xl represents the set of all types.
+func (xl termlist) isAll() bool {
+	// If there's a 𝓤 term, the entire list is 𝓤.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil && x.typ == nil {
+			return true
+		}
+	}
+	return false
+}
+
+// norm returns the normal form of xl.
+func (xl termlist) norm() termlist {
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	used := make([]bool, len(xl))
+	var rl termlist
+	for i, xi := range xl {
+		if xi == nil || used[i] {
+			continue
+		}
+		for j := i + 1; j < len(xl); j++ {
+			xj := xl[j]
+			if xj == nil || used[j] {
+				continue
+			}
+			if u1, u2 := xi.union(xj); u2 == nil {
+				// If we encounter a 𝓤 term, the entire list is 𝓤.
+				// Exit early.
+				// (Note that this is not just an optimization;
+				// if we continue, we may end up with a 𝓤 term
+				// and other terms and the result would not be
+				// in normal form.)
+				if u1.typ == nil {
+					return allTermlist
+				}
+				xi = u1
+				used[j] = true // xj is now unioned into xi - ignore it in future iterations
+			}
+		}
+		rl = append(rl, xi)
+	}
+	return rl
+}
+
+// If the type set represented by xl is specified by a single (non-𝓤) term,
+// structuralType returns that type. Otherwise it returns nil.
+func (xl termlist) structuralType() Type {
+	if nl := xl.norm(); len(nl) == 1 {
+		return nl[0].typ // if nl.isAll() then typ is nil, which is ok
+	}
+	return nil
+}
+
+// union returns the union xl ∪ yl.
+func (xl termlist) union(yl termlist) termlist {
+	return append(xl, yl...).norm()
+}
+
+// intersect returns the intersection xl ∩ yl.
+func (xl termlist) intersect(yl termlist) termlist {
+	if xl.isEmpty() || yl.isEmpty() {
+		return nil
+	}
+
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	var rl termlist
+	for _, x := range xl {
+		for _, y := range yl {
+			if r := x.intersect(y); r != nil {
+				rl = append(rl, r)
+			}
+		}
+	}
+	return rl.norm()
+}
+
+// equal reports whether xl and yl represent the same type set.
+func (xl termlist) equal(yl termlist) bool {
+	// TODO(gri) this should be more efficient
+	return xl.subsetOf(yl) && yl.subsetOf(xl)
+}
+
+// includes reports whether t ∈ xl.
+func (xl termlist) includes(t Type) bool {
+	for _, x := range xl {
+		if x.includes(t) {
+			return true
+		}
+	}
+	return false
+}
+
+// supersetOf reports whether y ⊆ xl.
+func (xl termlist) supersetOf(y *term) bool {
+	for _, x := range xl {
+		if y.subsetOf(x) {
+			return true
+		}
+	}
+	return false
+}
+
+// subsetOf reports whether xl ⊆ yl.
+func (xl termlist) subsetOf(yl termlist) bool {
+	if yl.isEmpty() {
+		return xl.isEmpty()
+	}
+
+	// each term x of xl must be a subset of yl
+	for _, x := range xl {
+		if !yl.supersetOf(x) {
+			return false // x is not a subset yl
+		}
+	}
+	return true
+}
diff --git a/src/cmd/compile/internal/types2/termlist_test.go b/src/cmd/compile/internal/types2/termlist_test.go
new file mode 100644
index 0000000..2f3772d
--- /dev/null
+++ b/src/cmd/compile/internal/types2/termlist_test.go
@@ -0,0 +1,313 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"strings"
+	"testing"
+)
+
+// maketl makes a term list from a string of the term list.
+func maketl(s string) termlist {
+	s = strings.Replace(s, " ", "", -1)
+	names := strings.Split(s, "∪")
+	r := make(termlist, len(names))
+	for i, n := range names {
+		r[i] = testTerm(n)
+	}
+	return r
+}
+
+func TestTermlistTop(t *testing.T) {
+	if !allTermlist.isAll() {
+		t.Errorf("allTermlist is not the set of all types")
+	}
+}
+
+func TestTermlistString(t *testing.T) {
+	for _, want := range []string{
+		"∅",
+		"𝓤",
+		"int",
+		"~int",
+		"myInt",
+		"∅ ∪ ∅",
+		"𝓤 ∪ 𝓤",
+		"∅ ∪ 𝓤 ∪ int",
+		"∅ ∪ 𝓤 ∪ int ∪ myInt",
+	} {
+		if got := maketl(want).String(); got != want {
+			t.Errorf("(%v).String() == %v", want, got)
+		}
+	}
+}
+
+func TestTermlistIsEmpty(t *testing.T) {
+	for test, want := range map[string]bool{
+		"∅":             true,
+		"∅ ∪ ∅":         true,
+		"∅ ∪ ∅ ∪ 𝓤":     false,
+		"∅ ∪ ∅ ∪ myInt": false,
+		"𝓤":             false,
+		"𝓤 ∪ int":       false,
+		"𝓤 ∪ myInt ∪ ∅": false,
+	} {
+		xl := maketl(test)
+		got := xl.isEmpty()
+		if got != want {
+			t.Errorf("(%v).isEmpty() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistIsAll(t *testing.T) {
+	for test, want := range map[string]bool{
+		"∅":             false,
+		"∅ ∪ ∅":         false,
+		"int ∪ ~string": false,
+		"~int ∪ myInt":  false,
+		"∅ ∪ ∅ ∪ 𝓤":     true,
+		"𝓤":             true,
+		"𝓤 ∪ int":       true,
+		"myInt ∪ 𝓤":     true,
+	} {
+		xl := maketl(test)
+		got := xl.isAll()
+		if got != want {
+			t.Errorf("(%v).isAll() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistNorm(t *testing.T) {
+	for _, test := range []struct {
+		xl, want string
+	}{
+		{"∅", "∅"},
+		{"∅ ∪ ∅", "∅"},
+		{"∅ ∪ int", "int"},
+		{"∅ ∪ myInt", "myInt"},
+		{"𝓤 ∪ int", "𝓤"},
+		{"𝓤 ∪ myInt", "𝓤"},
+		{"int ∪ myInt", "int ∪ myInt"},
+		{"~int ∪ int", "~int"},
+		{"~int ∪ myInt", "~int"},
+		{"int ∪ ~string ∪ int", "int ∪ ~string"},
+		{"~int ∪ string ∪ 𝓤 ∪ ~string ∪ int", "𝓤"},
+		{"~int ∪ string ∪ myInt ∪ ~string ∪ int", "~int ∪ ~string"},
+	} {
+		xl := maketl(test.xl)
+		got := maketl(test.xl).norm()
+		if got.String() != test.want {
+			t.Errorf("(%v).norm() = %v; want %v", xl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistStructuralType(t *testing.T) {
+	// helper to deal with nil types
+	tstring := func(typ Type) string {
+		if typ == nil {
+			return "nil"
+		}
+		return typ.String()
+	}
+
+	for test, want := range map[string]string{
+		"∅":                 "nil",
+		"𝓤":                 "nil",
+		"int":               "int",
+		"myInt":             "myInt",
+		"~int":              "int",
+		"~int ∪ string":     "nil",
+		"~int ∪ myInt":      "int",
+		"∅ ∪ int":           "int",
+		"∅ ∪ ~int":          "int",
+		"∅ ∪ ~int ∪ string": "nil",
+	} {
+		xl := maketl(test)
+		got := tstring(xl.structuralType())
+		if got != want {
+			t.Errorf("(%v).structuralType() == %v; want %v", test, got, want)
+		}
+	}
+}
+
+func TestTermlistUnion(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl, want string
+	}{
+
+		{"∅", "∅", "∅"},
+		{"∅", "𝓤", "𝓤"},
+		{"∅", "int", "int"},
+		{"𝓤", "~int", "𝓤"},
+		{"int", "~int", "~int"},
+		{"int", "string", "int ∪ string"},
+		{"int", "myInt", "int ∪ myInt"},
+		{"~int", "myInt", "~int"},
+		{"int ∪ string", "~string", "int ∪ ~string"},
+		{"~int ∪ string", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ string ∪ ∅", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ myInt ∪ ∅", "~string ∪ int", "~int ∪ ~string"},
+		{"~int ∪ string ∪ 𝓤", "~string ∪ int", "𝓤"},
+		{"~int ∪ string ∪ myInt", "~string ∪ int", "~int ∪ ~string"},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.union(yl).String()
+		if got != test.want {
+			t.Errorf("(%v).union(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistIntersect(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl, want string
+	}{
+
+		{"∅", "∅", "∅"},
+		{"∅", "𝓤", "∅"},
+		{"∅", "int", "∅"},
+		{"∅", "myInt", "∅"},
+		{"𝓤", "~int", "~int"},
+		{"𝓤", "myInt", "myInt"},
+		{"int", "~int", "int"},
+		{"int", "string", "∅"},
+		{"int", "myInt", "∅"},
+		{"~int", "myInt", "myInt"},
+		{"int ∪ string", "~string", "string"},
+		{"~int ∪ string", "~string ∪ int", "int ∪ string"},
+		{"~int ∪ string ∪ ∅", "~string ∪ int", "int ∪ string"},
+		{"~int ∪ myInt ∪ ∅", "~string ∪ int", "int"},
+		{"~int ∪ string ∪ 𝓤", "~string ∪ int", "int ∪ ~string"},
+		{"~int ∪ string ∪ myInt", "~string ∪ int", "int ∪ string"},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.intersect(yl).String()
+		if got != test.want {
+			t.Errorf("(%v).intersect(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistEqual(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl string
+		want   bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", false},
+		{"𝓤", "𝓤", true},
+		{"𝓤 ∪ int", "𝓤", true},
+		{"𝓤 ∪ int", "string ∪ 𝓤", true},
+		{"𝓤 ∪ myInt", "string ∪ 𝓤", true},
+		{"int ∪ ~string", "string ∪ int", false},
+		{"~int ∪ string", "string ∪ myInt", false},
+		{"int ∪ ~string ∪ ∅", "string ∪ int ∪ ~string", true},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.equal(yl)
+		if got != test.want {
+			t.Errorf("(%v).equal(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistIncludes(t *testing.T) {
+	for _, test := range []struct {
+		xl, typ string
+		want    bool
+	}{
+		{"∅", "int", false},
+		{"𝓤", "int", true},
+		{"~int", "int", true},
+		{"int", "string", false},
+		{"~int", "string", false},
+		{"~int", "myInt", true},
+		{"int ∪ string", "string", true},
+		{"~int ∪ string", "int", true},
+		{"~int ∪ string", "myInt", true},
+		{"~int ∪ myInt ∪ ∅", "myInt", true},
+		{"myInt ∪ ∅ ∪ 𝓤", "int", true},
+	} {
+		xl := maketl(test.xl)
+		yl := testTerm(test.typ).typ
+		got := xl.includes(yl)
+		if got != test.want {
+			t.Errorf("(%v).includes(%v) = %v; want %v", test.xl, yl, got, test.want)
+		}
+	}
+}
+
+func TestTermlistSupersetOf(t *testing.T) {
+	for _, test := range []struct {
+		xl, typ string
+		want    bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", false},
+		{"∅", "int", false},
+		{"𝓤", "∅", true},
+		{"𝓤", "𝓤", true},
+		{"𝓤", "int", true},
+		{"𝓤", "~int", true},
+		{"𝓤", "myInt", true},
+		{"~int", "int", true},
+		{"~int", "~int", true},
+		{"~int", "myInt", true},
+		{"int", "~int", false},
+		{"myInt", "~int", false},
+		{"int", "string", false},
+		{"~int", "string", false},
+		{"int ∪ string", "string", true},
+		{"int ∪ string", "~string", false},
+		{"~int ∪ string", "int", true},
+		{"~int ∪ string", "myInt", true},
+		{"~int ∪ string ∪ ∅", "string", true},
+		{"~string ∪ ∅ ∪ 𝓤", "myInt", true},
+	} {
+		xl := maketl(test.xl)
+		y := testTerm(test.typ)
+		got := xl.supersetOf(y)
+		if got != test.want {
+			t.Errorf("(%v).supersetOf(%v) = %v; want %v", test.xl, y, got, test.want)
+		}
+	}
+}
+
+func TestTermlistSubsetOf(t *testing.T) {
+	for _, test := range []struct {
+		xl, yl string
+		want   bool
+	}{
+		{"∅", "∅", true},
+		{"∅", "𝓤", true},
+		{"𝓤", "∅", false},
+		{"𝓤", "𝓤", true},
+		{"int", "int ∪ string", true},
+		{"~int", "int ∪ string", false},
+		{"~int", "myInt ∪ string", false},
+		{"myInt", "~int ∪ string", true},
+		{"~int", "string ∪ string ∪ int ∪ ~int", true},
+		{"myInt", "string ∪ string ∪ ~int", true},
+		{"int ∪ string", "string", false},
+		{"int ∪ string", "string ∪ int", true},
+		{"int ∪ ~string", "string ∪ int", false},
+		{"myInt ∪ ~string", "string ∪ int ∪ 𝓤", true},
+		{"int ∪ ~string", "string ∪ int ∪ ∅ ∪ string", false},
+		{"int ∪ myInt", "string ∪ ~int ∪ ∅ ∪ string", true},
+	} {
+		xl := maketl(test.xl)
+		yl := maketl(test.yl)
+		got := xl.subsetOf(yl)
+		if got != test.want {
+			t.Errorf("(%v).subsetOf(%v) = %v; want %v", test.xl, test.yl, got, test.want)
+		}
+	}
+}
diff --git a/src/cmd/compile/internal/types2/testdata/check/builtins.go2 b/src/cmd/compile/internal/types2/testdata/check/builtins.go2
index 3918d83..0cfea93 100644
--- a/src/cmd/compile/internal/types2/testdata/check/builtins.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/builtins.go2
@@ -6,48 +6,222 @@
 
 package builtins
 
-type Bmc interface {
-	type map[rune]string, chan int
+import "unsafe"
+
+// close
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+	close(ch /* ERROR cannot close non-channel */)
 }
 
-type Bms interface {
-	type map[string]int, []int
+func _[T C0](ch T) {
+	close(ch /* ERROR cannot close non-channel */)
 }
 
-type Bcs interface {
-	type chan bool, []float64
+func _[T C1](ch T) {
+	close(ch)
 }
 
-type Bss interface {
-	type []int, []string
+func _[T C2](ch T) {
+	close(ch /* ERROR cannot close receive-only channel */)
 }
 
-func _[T any] () {
-	_ = make(T /* ERROR invalid argument */ )
-	_ = make(T /* ERROR invalid argument */ , 10)
-	_ = make(T /* ERROR invalid argument */ , 10, 20)
+func _[T C3](ch T) {
+	close(ch)
 }
 
-func _[T Bmc] () {
-	_ = make(T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 1 or 2 arguments */ (T, 10, 20)
+func _[T C4](ch T) {
+	close(ch)
 }
 
-func _[T Bms] () {
-	_ = make /* ERROR expects 2 arguments */ (T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 2 arguments */ (T, 10, 20)
+func _[T C5[X], X any](ch T) {
+	close(ch)
 }
 
-func _[T Bcs] () {
-	_ = make /* ERROR expects 2 arguments */ (T)
-	_ = make(T, 10)
-	_ = make /* ERROR expects 2 arguments */ (T, 10, 20)
+// delete
+
+type M0 interface{ int }
+type M1 interface{ map[string]int }
+type M2 interface { map[string]int | map[string]float64 }
+type M3 interface{ map[string]int | map[rune]int }
+type M4[K comparable, V any] interface{ map[K]V | map[rune]V }
+
+func _[T any](m T) {
+	delete(m /* ERROR not a map */, "foo")
 }
 
-func _[T Bss] () {
-	_ = make /* ERROR expects 2 or 3 arguments */ (T)
-	_ = make(T, 10)
-	_ = make(T, 10, 20)
+func _[T M0](m T) {
+	delete(m /* ERROR not a map */, "foo")
+}
+
+func _[T M1](m T) {
+	delete(m, "foo")
+}
+
+func _[T M2](m T) {
+	delete(m, "foo")
+	delete(m, 0 /* ERROR cannot use .* as string */)
+}
+
+func _[T M3](m T) {
+	delete(m /* ERROR must have identical key types */, "foo")
+}
+
+func _[T M4[rune, V], V any](m T) {
+	delete(m, 'k')
+}
+
+func _[T M4[K, V], K comparable, V any](m T) {
+	delete(m /* ERROR must have identical key types */, "foo")
+}
+
+// make
+
+func _[
+	S1 interface{ []int },
+	S2 interface{ []int | chan int },
+
+	M1 interface{ map[string]int },
+	M2 interface{ map[string]int | chan int },
+
+	C1 interface{ chan int },
+	C2 interface{ chan int | chan string },
+]() {
+	type S0 []int
+	_ = make([]int, 10)
+	_ = make(S0, 10)
+	_ = make(S1, 10)
+	_ = make /* ERROR not enough arguments */ ()
+	_ = make /* ERROR expects 2 or 3 arguments */ (S1)
+	_ = make(S1, 10, 20)
+	_ = make /* ERROR expects 2 or 3 arguments */ (S1, 10, 20, 30)
+	_ = make(S2 /* ERROR cannot make .* no structural type */ , 10)
+
+	type M0 map[string]int
+	_ = make(map[string]int)
+	_ = make(M0)
+	_ = make(M1)
+	_ = make(M1, 10)
+	_ = make/* ERROR expects 1 or 2 arguments */(M1, 10, 20)
+	_ = make(M2 /* ERROR cannot make .* no structural type */ )
+
+	type C0 chan int
+	_ = make(chan int)
+	_ = make(C0)
+	_ = make(C1)
+	_ = make(C1, 10)
+	_ = make/* ERROR expects 1 or 2 arguments */(C1, 10, 20)
+	_ = make(C2 /* ERROR cannot make .* no structural type */ )
+}
+
+// unsafe.Alignof
+
+func _[T comparable]() {
+	var (
+		b int64
+		a [10]T
+		s struct{ f T }
+		p *T
+		l []T
+		f func(T)
+		i interface{ m() T }
+		c chan T
+		m map[T]T
+		t T
+	)
+
+	const bb = unsafe.Alignof(b)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Alignof(p)
+	assert(pp == 8)
+	const ll = unsafe.Alignof(l)
+	assert(ll == 8)
+	const ff = unsafe.Alignof(f)
+	assert(ff == 8)
+	const ii = unsafe.Alignof(i)
+	assert(ii == 8)
+	const cc = unsafe.Alignof(c)
+	assert(cc == 8)
+	const mm = unsafe.Alignof(m)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
+
+// unsafe.Offsetof
+
+func _[T comparable]() {
+	var (
+		b struct{ _, f int64 }
+		a struct{ _, f [10]T }
+		s struct{ _, f struct{ f T } }
+		p struct{ _, f *T }
+		l struct{ _, f []T }
+		f struct{ _, f func(T) }
+		i struct{ _, f interface{ m() T } }
+		c struct{ _, f chan T }
+		m struct{ _, f map[T]T }
+		t struct{ _, f T }
+	)
+
+	const bb = unsafe.Offsetof(b.f)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Offsetof(p.f)
+	assert(pp == 8)
+	const ll = unsafe.Offsetof(l.f)
+	assert(ll == 24)
+	const ff = unsafe.Offsetof(f.f)
+	assert(ff == 8)
+	const ii = unsafe.Offsetof(i.f)
+	assert(ii == 16)
+	const cc = unsafe.Offsetof(c.f)
+	assert(cc == 8)
+	const mm = unsafe.Offsetof(m.f)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
+
+// unsafe.Sizeof
+
+func _[T comparable]() {
+	var (
+		b int64
+		a [10]T
+		s struct{ f T }
+		p *T
+		l []T
+		f func(T)
+		i interface{ m() T }
+		c chan T
+		m map[T]T
+		t T
+	)
+
+	const bb = unsafe.Sizeof(b)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Sizeof(p)
+	assert(pp == 8)
+	const ll = unsafe.Sizeof(l)
+	assert(ll == 24)
+	const ff = unsafe.Sizeof(f)
+	assert(ff == 8)
+	const ii = unsafe.Sizeof(i)
+	assert(ii == 16)
+	const cc = unsafe.Sizeof(c)
+	assert(cc == 8)
+	const mm = unsafe.Sizeof(m)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
 }
diff --git a/src/cmd/compile/internal/types2/testdata/check/builtins.src b/src/cmd/compile/internal/types2/testdata/check/builtins.src
index 6d1f471..17e4068 100644
--- a/src/cmd/compile/internal/types2/testdata/check/builtins.src
+++ b/src/cmd/compile/internal/types2/testdata/check/builtins.src
@@ -144,7 +144,7 @@
 	var r <-chan int
 	close() // ERROR not enough arguments
 	close(1, 2) // ERROR too many arguments
-	close(42 /* ERROR not a channel */)
+	close(42 /* ERROR cannot close non-channel */)
 	close(r /* ERROR receive-only channel */)
 	close(c)
 	_ = close /* ERROR used as value */ (c)
diff --git a/src/cmd/compile/internal/types2/testdata/check/const0.src b/src/cmd/compile/internal/types2/testdata/check/const0.src
index 5608b15..3cffdf9 100644
--- a/src/cmd/compile/internal/types2/testdata/check/const0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/const0.src
@@ -27,7 +27,7 @@
 	ub1 = true
 	ub2 = 2 < 1
 	ub3 = ui1 == uf1
-	ub4 = true /* ERROR "cannot convert" */ == 0
+	ub4 = true /* ERROR "mismatched types untyped bool and untyped int" */ == 0
 
 	// integer values
 	ui0 = 0
diff --git a/src/cmd/compile/internal/types2/testdata/check/cycles4.src b/src/cmd/compile/internal/types2/testdata/check/cycles4.src
index 445babc..924aabf 100644
--- a/src/cmd/compile/internal/types2/testdata/check/cycles4.src
+++ b/src/cmd/compile/internal/types2/testdata/check/cycles4.src
@@ -4,6 +4,8 @@
 
 package p
 
+import "unsafe"
+
 // Check that all methods of T are collected before
 // determining the result type of m (which embeds
 // all methods of T).
@@ -13,7 +15,7 @@
 	E
 }
 
-var _ = T.m(nil).m().e()
+var _ int = T.m(nil).m().e()
 
 type E interface {
 	e() int
@@ -22,7 +24,7 @@
 // Check that unresolved forward chains are followed
 // (see also comment in resolver.go, checker.typeDecl).
 
-var _ = C.m(nil).m().e()
+var _ int = C.m(nil).m().e()
 
 type A B
 
@@ -108,3 +110,12 @@
 type Event interface {
 	Target() Element
 }
+
+// Check that accessing an interface method too early doesn't lead
+// to follow-on errors due to an incorrectly computed type set.
+
+type T8 interface {
+	m() [unsafe.Sizeof(T8.m /* ERROR undefined */ )]int
+}
+
+var _ = T8.m // no error expected here
diff --git a/src/cmd/compile/internal/types2/testdata/check/decls0.src b/src/cmd/compile/internal/types2/testdata/check/decls0.src
index e78d886..f051a4f 100644
--- a/src/cmd/compile/internal/types2/testdata/check/decls0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/decls0.src
@@ -4,7 +4,7 @@
 
 // type declarations
 
-package decls0
+package go1_17 // don't permit non-interface elements in interfaces
 
 import "unsafe"
 
@@ -185,10 +185,10 @@
 func f3() (x f3 /* ERROR "not a type" */ ) { return }
 func f4() (x *f4 /* ERROR "not a type" */ ) { return }
 
-func (S0) m1(x S0 /* ERROR value .* is not a type */ .m1) {}
-func (S0) m2(x *S0 /* ERROR value .* is not a type */ .m2) {}
-func (S0) m3() (x S0 /* ERROR value .* is not a type */ .m3) { return }
-func (S0) m4() (x *S0 /* ERROR value .* is not a type */ .m4) { return }
+func (S0) m1(x S0 /* ERROR illegal cycle in method declaration */ .m1) {}
+func (S0) m2(x *S0 /* ERROR illegal cycle in method declaration */ .m2) {}
+func (S0) m3() (x S0 /* ERROR illegal cycle in method declaration */ .m3) { return }
+func (S0) m4() (x *S0 /* ERROR illegal cycle in method declaration */ .m4) { return }
 
 // interfaces may not have any blank methods
 type BlankI interface {
diff --git a/src/cmd/compile/internal/types2/testdata/check/decls1.src b/src/cmd/compile/internal/types2/testdata/check/decls1.src
index e6beb78..1167ced 100644
--- a/src/cmd/compile/internal/types2/testdata/check/decls1.src
+++ b/src/cmd/compile/internal/types2/testdata/check/decls1.src
@@ -83,7 +83,7 @@
 
 // Constant expression initializations
 var (
-	v1 = 1 /* ERROR "cannot convert" */ + "foo"
+	v1 = 1 /* ERROR "mismatched types untyped int and untyped string" */ + "foo"
 	v2 = c + 255
 	v3 = c + 256 /* ERROR "overflows" */
 	v4 = r + 2147483647
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr1.src b/src/cmd/compile/internal/types2/testdata/check/expr1.src
index 4ead815..85ad234 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr1.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr1.src
@@ -111,10 +111,10 @@
 func _(x, y string, z mystring) {
 	x = x + "foo"
 	x = x /* ERROR not defined */ - "foo"
-	x = x + 1 // ERROR cannot convert
+	x = x + 1 // ERROR mismatched types string and untyped int
 	x = x + y
 	x = x /* ERROR not defined */ - y
-	x = x * 10 // ERROR cannot convert
+	x = x * 10 // ERROR mismatched types string and untyped int
 }
 
 func f() (a, b int) { return }
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr2.src b/src/cmd/compile/internal/types2/testdata/check/expr2.src
index 0c959e8..f9726b5 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr2.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr2.src
@@ -10,7 +10,7 @@
 	const t = true == true
 	const f = true == false
 	_ = t /* ERROR "cannot compare" */ < f
-	_ = 0 /* ERROR "cannot convert" */ == t
+	_ = 0 /* ERROR "mismatched types untyped int and untyped bool" */ == t
 	var b bool
 	var x, y float32
 	b = x < y
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr3.src b/src/cmd/compile/internal/types2/testdata/check/expr3.src
index eab3f72..fd28421 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr3.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr3.src
@@ -104,7 +104,7 @@
 	var ok mybool
 	_, ok = m["bar"]
 	_ = ok
-	_ = m[0 /* ERROR "cannot use 0" */ ] + "foo" // ERROR "cannot convert"
+	_ = m[0 /* ERROR "cannot use 0" */ ] + "foo" // ERROR "mismatched types int and untyped string"
 
 	var t string
 	_ = t[- /* ERROR "negative" */ 1]
diff --git a/src/cmd/compile/internal/types2/testdata/check/issues.go2 b/src/cmd/compile/internal/types2/testdata/check/issues.go2
index 1c73b5d..effc2db 100644
--- a/src/cmd/compile/internal/types2/testdata/check/issues.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/issues.go2
@@ -24,25 +24,23 @@
 	eql[io.Reader](nil, nil)
 }
 
-// If we have a receiver of pointer type (below: *T) we must ignore
-// the pointer in the implementation of the method lookup because
-// the type bound of T is an interface and pointer to interface types
-// have no methods and then the lookup would fail.
+// If we have a receiver of pointer to type parameter type (below: *T)
+// we don't have any methods, like for interfaces.
 type C[T any] interface {
     m()
 }
 
 // using type bound C
 func _[T C[T]](x *T) {
-	x.m()
+	x.m /* ERROR x\.m undefined */ ()
 }
 
 // using an interface literal as bound
 func _[T interface{ m() }](x *T) {
-	x.m()
+	x.m /* ERROR x\.m undefined */ ()
 }
 
-func f2[_ interface{ m1(); m2() }]()
+func f2[_ interface{ m1(); m2() }]() {}
 
 type T struct{}
 func (T) m1()
@@ -57,15 +55,15 @@
 // type with a type list constraint, all of the type argument's types in its
 // bound, but at least one (!), must be in the type list of the bound of the
 // corresponding parameterized type's type parameter.
-type T1[P interface{type uint}] struct{}
+type T1[P interface{~uint}] struct{}
 
 func _[P any]() {
-    _ = T1[P /* ERROR P has no type constraints */ ]{}
+    _ = T1[P /* ERROR P has no constraints */ ]{}
 }
 
 // This is the original (simplified) program causing the same issue.
 type Unsigned interface {
-	type uint
+	~uint
 }
 
 type T2[U Unsigned] struct {
@@ -76,8 +74,8 @@
     return u.s + 1
 }
 
-func NewT2[U any]() T2[U /* ERROR U has no type constraints */ ] {
-    return T2[U /* ERROR U has no type constraints */ ]{}
+func NewT2[U any]() T2[U /* ERROR U has no constraints */ ] {
+    return T2[U /* ERROR U has no constraints */ ]{}
 }
 
 func _() {
@@ -156,7 +154,7 @@
 // predicate disjunction in the implementation was wrong because if a type list
 // contains both an integer and a floating-point type, the type parameter is
 // neither an integer or a floating-point number.
-func convert[T1, T2 interface{type int, uint, float32}](v T1) T2 {
+func convert[T1, T2 interface{~int | ~uint | ~float32}](v T1) T2 {
 	return T2(v)
 }
 
@@ -168,12 +166,12 @@
 // both numeric, or both strings. The implementation had the same problem
 // with this check as the conversion issue above (issue #39623).
 
-func issue39623[T interface{type int, string}](x, y T) T {
+func issue39623[T interface{~int | ~string}](x, y T) T {
 	return x + y
 }
 
 // Simplified, from https://go2goplay.golang.org/p/efS6x6s-9NI:
-func Sum[T interface{type int, string}](s []T) (sum T) {
+func Sum[T interface{~int | ~string}](s []T) (sum T) {
 	for _, v := range s {
 		sum += v
 	}
@@ -182,19 +180,19 @@
 
 // Assignability of an unnamed pointer type to a type parameter that
 // has a matching underlying type.
-func _[T interface{}, PT interface{type *T}] (x T) PT {
+func _[T interface{}, PT interface{~*T}] (x T) PT {
     return &x
 }
 
 // Indexing of generic types containing type parameters in their type list:
-func at[T interface{ type []E }, E interface{}](x T, i int) E {
+func at[T interface{ ~[]E }, E interface{}](x T, i int) E {
         return x[i]
 }
 
 // A generic type inside a function acts like a named type. Its underlying
 // type is itself, its "operational type" is defined by the type list in
 // the tybe bound, if any.
-func _[T interface{type int}](x T) {
+func _[T interface{~int}](x T) {
 	type myint int
 	var _ int = int(x)
 	var _ T = 42
@@ -203,24 +201,24 @@
 
 // Indexing a generic type with an array type bound checks length.
 // (Example by mdempsky@.)
-func _[T interface { type [10]int }](x T) {
+func _[T interface { ~[10]int }](x T) {
 	_ = x[9] // ok
 	_ = x[20 /* ERROR out of bounds */ ]
 }
 
 // Pointer indirection of a generic type.
-func _[T interface{ type *int }](p T) int {
+func _[T interface{ ~*int }](p T) int {
 	return *p
 }
 
 // Channel sends and receives on generic types.
-func _[T interface{ type chan int }](ch T) int {
+func _[T interface{ ~chan int }](ch T) int {
 	ch <- 0
 	return <- ch
 }
 
 // Calling of a generic variable.
-func _[T interface{ type func() }](f T) {
+func _[T interface{ ~func() }](f T) {
 	f()
 	go f()
 }
@@ -232,9 +230,9 @@
 // type parameter that was substituted with a defined type.
 // Test case from an (originally) failing example.
 
-type sliceOf[E any] interface{ type []E }
+type sliceOf[E any] interface{ ~[]E }
 
-func append[T interface{}, S sliceOf[T], T2 interface{ type T }](s S, t ...T2) S
+func append[T interface{}, S sliceOf[T], T2 interface{}](s S, t ...T2) S { panic(0) }
 
 var f           func()
 var cancelSlice []context.CancelFunc
@@ -242,7 +240,7 @@
 
 // A generic function must be instantiated with a type, not a value.
 
-func g[T any](T) T
+func g[T any](T) T { panic(0) }
 
 var _ = g[int]
 var _ = g[nil /* ERROR is not a type */ ]
diff --git a/src/cmd/compile/internal/types2/testdata/check/issues.src b/src/cmd/compile/internal/types2/testdata/check/issues.src
index 21aa208..692ed37 100644
--- a/src/cmd/compile/internal/types2/testdata/check/issues.src
+++ b/src/cmd/compile/internal/types2/testdata/check/issues.src
@@ -2,11 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package issues
+package go1_17 // don't permit non-interface elements in interfaces
 
 import (
 	"fmt"
-	syn "cmd/compile/internal/syntax"
+	syn "regexp/syntax"
 	t1 "text/template"
 	t2 "html/template"
 )
@@ -329,10 +329,10 @@
 func issue28281g() (... /* ERROR can only use ... with final parameter in list */ TT)
 
 // Issue #26234: Make various field/method lookup errors easier to read by matching cmd/compile's output
-func issue26234a(f *syn.File) {
+func issue26234a(f *syn.Prog) {
 	// The error message below should refer to the actual package name (syntax)
 	// not the local package name (syn).
-	f.foo /* ERROR f.foo undefined \(type \*syntax.File has no field or method foo\) */
+	f.foo /* ERROR f\.foo undefined \(type \*syntax\.Prog has no field or method foo\) */
 }
 
 type T struct {
@@ -357,11 +357,11 @@
 	var _ T = 0 // ERROR cannot use 0 \(untyped int constant\) as T
 
 	// There is only one package with name syntax imported, only use the (global) package name in error messages.
-	var _ *syn.File = 0 // ERROR cannot use 0 \(untyped int constant\) as \*syntax.File
+	var _ *syn.Prog = 0 // ERROR cannot use 0 \(untyped int constant\) as \*syntax.Prog
 
 	// Because both t1 and t2 have the same global package name (template),
 	// qualify packages with full path name in this case.
-	var _ t1.Template = t2 /* ERROR cannot use .* \(value of type "html/template".Template\) as "text/template".Template */ .Template{}
+	var _ t1.Template = t2 /* ERROR cannot use .* \(value of type .html/template.\.Template\) as .text/template.\.Template */ .Template{}
 }
 
 func issue42989(s uint) {
diff --git a/src/cmd/compile/internal/types2/testdata/check/linalg.go2 b/src/cmd/compile/internal/types2/testdata/check/linalg.go2
index 0d27603..efc090a 100644
--- a/src/cmd/compile/internal/types2/testdata/check/linalg.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/linalg.go2
@@ -9,10 +9,10 @@
 // Numeric is type bound that matches any numeric type.
 // It would likely be in a constraints package in the standard library.
 type Numeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		complex64, complex128
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~complex64 | ~complex128
 }
 
 func DotProduct[T Numeric](s1, s2 []T) T {
@@ -42,14 +42,14 @@
 
 // OrderedNumeric is a type bound that matches numeric types that support the < operator.
 type OrderedNumeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
 }
 
 // Complex is a type bound that matches the two complex types, which do not have a < operator.
 type Complex interface {
-	type complex64, complex128
+	~complex64 | ~complex128
 }
 
 // OrderedAbs is a helper type that defines an Abs method for
diff --git a/src/cmd/compile/internal/types2/testdata/check/map2.go2 b/src/cmd/compile/internal/types2/testdata/check/map2.go2
index 2833445..be2c49f 100644
--- a/src/cmd/compile/internal/types2/testdata/check/map2.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/map2.go2
@@ -114,7 +114,7 @@
 
 // chans
 
-func chans_Ranger[T any]() (*chans_Sender[T], *chans_Receiver[T])
+func chans_Ranger[T any]() (*chans_Sender[T], *chans_Receiver[T]) { panic(0) }
 
 // A sender is used to send values to a Receiver.
 type chans_Sender[T any] struct {
diff --git a/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go2 b/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go2
index c2f282b..1b40659 100644
--- a/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/mtypeparams.go2
@@ -10,7 +10,7 @@
 
 type S struct{}
 
-func (S) m[T any](v T)
+func (S) m[T any](v T) {}
 
 // TODO(gri) Once we collect interface method type parameters
 //           in the parser, we can enable these tests again.
diff --git a/src/cmd/compile/internal/types2/testdata/check/stmt0.src b/src/cmd/compile/internal/types2/testdata/check/stmt0.src
index bedcbe5..d744f2b 100644
--- a/src/cmd/compile/internal/types2/testdata/check/stmt0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/stmt0.src
@@ -49,18 +49,18 @@
 	b = true
 
 	i += 1
-	i += "foo" /* ERROR "cannot convert.*int" */
+	i += "foo" /* ERROR "mismatched types int and untyped string" */
 
 	f -= 1
 	f /= 0
 	f = float32(0)/0 /* ERROR "division by zero" */
-	f -= "foo" /* ERROR "cannot convert.*float64" */
+	f -= "foo" /* ERROR "mismatched types float64 and untyped string" */
 
 	c *= 1
 	c /= 0
 
 	s += "bar"
-	s += 1 /* ERROR "cannot convert.*string" */
+	s += 1 /* ERROR "mismatched types string and untyped int" */
 
 	var u64 uint64
 	u64 += 1<<u64
@@ -937,13 +937,13 @@
 // errors reported).
 func issue10148() {
 	for y /* ERROR declared but not used */ := range "" {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int*/ + 1
 	}
 	for range 1 /* ERROR cannot range over 1 */ {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int*/ + 1
 	}
 	for y := range 1 /* ERROR cannot range over 1 */ {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int*/ + 1
 	}
 }
 
diff --git a/src/cmd/compile/internal/types2/testdata/check/tinference.go2 b/src/cmd/compile/internal/types2/testdata/check/tinference.go2
index a53fde0..0afb77c 100644
--- a/src/cmd/compile/internal/types2/testdata/check/tinference.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/tinference.go2
@@ -8,36 +8,38 @@
 
 type any interface{}
 
-func f0[A any, B interface{type C}, C interface{type D}, D interface{type A}](A, B, C, D)
-func _() {
-	f := f0[string]
-	f("a", "b", "c", "d")
-	f0("a", "b", "c", "d")
-}
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+// func f0[A any, B interface{~C}, C interface{~D}, D interface{~A}](A, B, C, D)
+// func _() {
+// 	f := f0[string]
+// 	f("a", "b", "c", "d")
+// 	f0("a", "b", "c", "d")
+// }
+// 
+// func f1[A any, B interface{~A}](A, B)
+// func _() {
+// 	f := f1[int]
+// 	f(int(0), int(0))
+// 	f1(int(0), int(0))
+// }
 
-func f1[A any, B interface{type A}](A, B)
-func _() {
-	f := f1[int]
-	f(int(0), int(0))
-	f1(int(0), int(0))
-}
-
-func f2[A any, B interface{type []A}](A, B)
+func f2[A any, B interface{~[]A}](A, B) {}
 func _() {
 	f := f2[byte]
 	f(byte(0), []byte{})
 	f2(byte(0), []byte{})
 }
 
-func f3[A any, B interface{type C}, C interface{type *A}](A, B, C)
-func _() {
-	f := f3[int]
-	var x int
-	f(x, &x, &x)
-	f3(x, &x, &x)
-}
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+// func f3[A any, B interface{~C}, C interface{~*A}](A, B, C)
+// func _() {
+// 	f := f3[int]
+// 	var x int
+// 	f(x, &x, &x)
+// 	f3(x, &x, &x)
+// }
 
-func f4[A any, B interface{type []C}, C interface{type *A}](A, B, C)
+func f4[A any, B interface{~[]C}, C interface{~*A}](A, B, C) {}
 func _() {
 	f := f4[int]
 	var x int
@@ -45,14 +47,14 @@
 	f4(x, []*int{}, &x)
 }
 
-func f5[A interface{type struct{b B; c C}}, B any, C interface{type *B}](x B) A
+func f5[A interface{~struct{b B; c C}}, B any, C interface{~*B}](x B) A { panic(0) }
 func _() {
 	x := f5(1.2)
 	var _ float64 = x.b
 	var _ float64 = *x.c
 }
 
-func f6[A any, B interface{type struct{f []A}}](B) A
+func f6[A any, B interface{~struct{f []A}}](B) A { panic(0) }
 func _() {
 	x := f6(struct{f []string}{})
 	var _ string = x
@@ -60,11 +62,11 @@
 
 // TODO(gri) Need to flag invalid recursive constraints. At the
 // moment these cause infinite recursions and stack overflow.
-// func f7[A interface{type B}, B interface{type A}]()
+// func f7[A interface{type B}, B interface{~A}]()
 
 // More realistic examples
 
-func Double[S interface{ type []E }, E interface{ type int, int8, int16, int32, int64 }](s S) S {
+func Double[S interface{ ~[]E }, E interface{ ~int | ~int8 | ~int16 | ~int32 | ~int64 }](s S) S {
 	r := make(S, len(s))
 	for i, v := range s {
 		r[i] = v + v
@@ -80,7 +82,7 @@
 
 type Setter[B any] interface {
 	Set(string)
-	type *B
+	~*B
 }
 
 func FromStrings[T interface{}, PT Setter[T]](s []string) []T {
diff --git a/src/cmd/compile/internal/types2/testdata/check/typeinst2.go2 b/src/cmd/compile/internal/types2/testdata/check/typeinst2.go2
index 6e2104a..d087c26 100644
--- a/src/cmd/compile/internal/types2/testdata/check/typeinst2.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/typeinst2.go2
@@ -85,7 +85,7 @@
 	Abs() T
 }
 
-func AbsDifference[T NumericAbs[T]](x T)
+func AbsDifference[T NumericAbs[T]](x T) { panic(0) }
 
 type OrderedAbs[T any] T
 
@@ -97,7 +97,7 @@
 
 // same code, reduced to essence
 
-func g[P interface{ m() P }](x P)
+func g[P interface{ m() P }](x P) { panic(0) }
 
 type T4[P any] P
 
@@ -148,15 +148,15 @@
 	p.pm()
 }
 
-// An interface can (explicitly) declare at most one type list.
+// It is ok to have multiple embedded unions.
 type _ interface {
 	m0()
-	type int, string, bool
-	type /* ERROR multiple type lists */ float32, float64
+	~int | ~string | ~bool
+	~float32 | ~float64
 	m1()
 	m2()
-	type /* ERROR multiple type lists */ complex64, complex128
-	type /* ERROR multiple type lists */ rune
+	~complex64 | ~complex128
+	~rune
 }
 
 // Interface type lists may contain each type at most once.
@@ -164,23 +164,24 @@
 // for them to be all in a single list, and we report the error
 // as well.)
 type _ interface {
-	type int, int /* ERROR duplicate type int */
-	type /* ERROR multiple type lists */ int /* ERROR duplicate type int */
+	~int|~int /* ERROR overlapping terms ~int */
+	~int|int /* ERROR overlapping terms int */
+	int|int /* ERROR overlapping terms int */
 }
 
 type _ interface {
-	type struct{f int}, struct{g int}, struct /* ERROR duplicate type */ {f int}
+	~struct{f int} | ~struct{g int} | ~struct /* ERROR overlapping terms */ {f int}
 }
 
 // Interface type lists can contain any type, incl. *Named types.
 // Verify that we use the underlying type to compute the operational type.
 type MyInt int
-func add1[T interface{type MyInt}](x T) T {
+func add1[T interface{MyInt}](x T) T {
 	return x + 1
 }
 
 type MyString string
-func double[T interface{type MyInt, MyString}](x T) T {
+func double[T interface{MyInt|MyString}](x T) T {
 	return x + x
 }
 
@@ -189,22 +190,22 @@
 // type lists.
 
 type E0 interface {
-	type int, bool, string
+	~int | ~bool | ~string
 }
 
 type E1 interface {
-	type int, float64, string
+	~int | ~float64 | ~string
 }
 
 type E2 interface {
-	type float64
+	~float64
 }
 
 type I0 interface {
 	E0
 }
 
-func f0[T I0]()
+func f0[T I0]() {}
 var _ = f0[int]
 var _ = f0[bool]
 var _ = f0[string]
@@ -215,7 +216,7 @@
 	E1
 }
 
-func f01[T I01]()
+func f01[T I01]() {}
 var _ = f01[int]
 var _ = f01[bool /* ERROR does not satisfy I0 */ ]
 var _ = f01[string]
@@ -227,7 +228,7 @@
 	E2
 }
 
-func f012[T I012]()
+func f012[T I012]() {}
 var _ = f012[int /* ERROR does not satisfy I012 */ ]
 var _ = f012[bool /* ERROR does not satisfy I012 */ ]
 var _ = f012[string /* ERROR does not satisfy I012 */ ]
@@ -238,7 +239,7 @@
 	E2
 }
 
-func f12[T I12]()
+func f12[T I12]() {}
 var _ = f12[int /* ERROR does not satisfy I12 */ ]
 var _ = f12[bool /* ERROR does not satisfy I12 */ ]
 var _ = f12[string /* ERROR does not satisfy I12 */ ]
@@ -246,10 +247,10 @@
 
 type I0_ interface {
 	E0
-	type int
+	~int
 }
 
-func f0_[T I0_]()
+func f0_[T I0_]() {}
 var _ = f0_[int]
 var _ = f0_[bool /* ERROR does not satisfy I0_ */ ]
 var _ = f0_[string /* ERROR does not satisfy I0_ */ ]
diff --git a/src/cmd/compile/internal/types2/testdata/check/typeparams.go2 b/src/cmd/compile/internal/types2/testdata/check/typeparams.go2
index badda01..1ad80b1 100644
--- a/src/cmd/compile/internal/types2/testdata/check/typeparams.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/typeparams.go2
@@ -6,18 +6,18 @@
 
 // import "io" // for type assertion tests
 
-// The predeclared identifier "any" is only visible as a constraint
+// The predeclared identifier "any" can only be used as a constraint
 // in a type parameter list.
-var _ any // ERROR undeclared
-func _[_ any /* ok here */ , _ interface{any /* ERROR undeclared */ }](any /* ERROR undeclared */ ) {
-        var _ any /* ERROR undeclared */
+var _ any // ERROR cannot use any outside constraint position
+func _[_ any /* ok here */ , _ interface{any /* ERROR constraint */ }](any /* ERROR constraint */ ) {
+        var _ any /* ERROR constraint */
 }
 
 func identity[T any](x T) T { return x }
 
-func _[_ any](x int) int
-func _[T any](T /* ERROR redeclared */ T)()
-func _[T, T /* ERROR redeclared */ any]()
+func _[_ any](x int) int { panic(0) }
+func _[T any](T /* ERROR redeclared */ T)() {}
+func _[T, T /* ERROR redeclared */ any]() {}
 
 // Constraints (incl. any) may be parenthesized.
 func _[_ (any)]() {}
@@ -52,22 +52,22 @@
 
 type F[A, B any] func(A, B) (B, A)
 
-func min[T interface{ type int }](x, y T) T {
+func min[T interface{ ~int }](x, y T) T {
         if x < y {
                 return x
         }
         return y
 }
 
-func _[T interface{type int, float32}](x, y T) bool { return x < y }
+func _[T interface{~int | ~float32}](x, y T) bool { return x < y }
 func _[T any](x, y T) bool { return x /* ERROR cannot compare */ < y }
-func _[T interface{type int, float32, bool}](x, y T) bool { return x /* ERROR cannot compare */ < y }
+func _[T interface{~int | ~float32 | ~bool}](x, y T) bool { return x /* ERROR cannot compare */ < y }
 
 func _[T C1[T]](x, y T) bool { return x /* ERROR cannot compare */ < y }
 func _[T C2[T]](x, y T) bool { return x < y }
 
 type C1[T any] interface{}
-type C2[T any] interface{ type int, float32 }
+type C2[T any] interface{ ~int | ~float32 }
 
 func new[T any]() *T {
         var x T
@@ -77,66 +77,71 @@
 var _ = new /* ERROR cannot use generic function new */
 var _ *int = new[int]()
 
-func _[T any](map[T /* ERROR invalid map key type T \(missing comparable constraint\) */]int) // w/o constraint we don't know if T is comparable
+func _[T any](map[T /* ERROR invalid map key type T \(missing comparable constraint\) */]int) {} // w/o constraint we don't know if T is comparable
 
-func f1[T1 any](struct{T1}) int
+func f1[T1 any](struct{T1 /* ERROR cannot be a .* type parameter */ }) int { panic(0) }
 var _ = f1[int](struct{T1}{})
 type T1 = int
 
-func f2[t1 any](struct{t1; x float32}) int
+func f2[t1 any](struct{t1 /* ERROR cannot be a .* type parameter */ ; x float32}) int { panic(0) }
 var _ = f2[t1](struct{t1; x float32}{})
 type t1 = int
 
 
-func f3[A, B, C any](A, struct{x B}, func(A, struct{x B}, *C)) int
+func f3[A, B, C any](A, struct{x B}, func(A, struct{x B}, *C)) int { panic(0) }
 
 var _ = f3[int, rune, bool](1, struct{x rune}{}, nil)
 
 // indexing
 
 func _[T any] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type int }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type string }] (x T, i int) { _ = x[i] }
-func _[T interface{ type []int }] (x T, i int) { _ = x[i] }
-func _[T interface{ type [10]int, *[20]int, map[int]int }] (x T, i int) { _ = x[i] }
-func _[T interface{ type string, []byte }] (x T, i int) { _ = x[i] }
-func _[T interface{ type []int, [1]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type string, []rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~int }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~string }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[]int }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[10]int | ~*[20]int | ~map[int]int }] (x T, i int) { _ = x /* ERROR cannot index */ [i] } // map and non-map types
+func _[T interface{ ~string | ~[]byte }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[]int | ~[1]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~string | ~[]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
 
-// indexing with various combinations of map types in type lists (see issue #42616)
-func _[T interface{ type []E, map[int]E }, E any](x T, i int) { _ = x[i] }
-func _[T interface{ type []E }, E any](x T, i int) { _ = &x[i] }
-func _[T interface{ type map[int]E }, E any](x T, i int) { _, _ = x[i] } // comma-ok permitted
-func _[T interface{ type []E, map[int]E }, E any](x T, i int) { _ = &x /* ERROR cannot take address */ [i] }
-func _[T interface{ type []E, map[int]E, map[uint]E }, E any](x T, i int) { _ = x /* ERROR cannot index */ [i] } // different map element types
-func _[T interface{ type []E, map[string]E }, E any](x T, i int) { _ = x[i /* ERROR cannot use i */ ] }
+// indexing with various combinations of map types in type sets (see issue #42616)
+func _[T interface{ ~[]E | ~map[int]E }, E any](x T, i int) { _ = x /* ERROR cannot index */ [i] } // map and non-map types
+func _[T interface{ ~[]E }, E any](x T, i int) { _ = &x[i] }
+func _[T interface{ ~map[int]E }, E any](x T, i int) { _, _ = x[i] } // comma-ok permitted
+func _[T interface{ ~map[int]E }, E any](x T, i int) { _ = &x /* ERROR cannot take address */ [i] }
+func _[T interface{ ~map[int]E | ~map[uint]E }, E any](x T, i int) { _ = x /* ERROR cannot index */ [i] } // different map element types
+func _[T interface{ ~[]E | ~map[string]E }, E any](x T, i int) { _ = x /* ERROR cannot index */ [i] } // map and non-map types
+
+// indexing with various combinations of array and other types in type sets
+func _[T interface{ [10]int }](x T, i int) { _ = x[i]; _ = x[9]; _ = x[10 /* ERROR out of bounds */ ] }
+func _[T interface{ [10]byte | string }](x T, i int) { _ = x[i]; _ = x[9]; _ = x[10 /* ERROR out of bounds */ ] }
+func _[T interface{ [10]int | *[20]int | []int }](x T, i int) { _ = x[i]; _ = x[9]; _ = x[10 /* ERROR out of bounds */ ] }
 
 // slicing
 // TODO(gri) implement this
 
-func _[T interface{ type string }] (x T, i, j, k int) { _ = x /* ERROR invalid operation */ [i:j:k] }
+func _[T interface{ ~string }] (x T, i, j, k int) { _ = x /* ERROR generic slice expressions not yet implemented */ [i:j:k] }
 
 // len/cap built-ins
 
 func _[T any](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string, []byte, int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string }](x T) { _ = len(x) }
-func _[T interface{ type [10]int }](x T) { _ = len(x) }
-func _[T interface{ type []byte }](x T) { _ = len(x) }
-func _[T interface{ type map[int]int }](x T) { _ = len(x) }
-func _[T interface{ type chan int }](x T) { _ = len(x) }
-func _[T interface{ type string, []byte, chan int }](x T) { _ = len(x) }
+func _[T interface{ ~int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string | ~[]byte | ~int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string }](x T) { _ = len(x) }
+func _[T interface{ ~[10]int }](x T) { _ = len(x) }
+func _[T interface{ ~[]byte }](x T) { _ = len(x) }
+func _[T interface{ ~map[int]int }](x T) { _ = len(x) }
+func _[T interface{ ~chan int }](x T) { _ = len(x) }
+func _[T interface{ ~string | ~[]byte | ~chan int }](x T) { _ = len(x) }
 
 func _[T any](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string, []byte, int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type [10]int }](x T) { _ = cap(x) }
-func _[T interface{ type []byte }](x T) { _ = cap(x) }
-func _[T interface{ type map[int]int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type chan int }](x T) { _ = cap(x) }
-func _[T interface{ type []byte, chan int }](x T) { _ = cap(x) }
+func _[T interface{ ~int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string | ~[]byte | ~int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~[10]int }](x T) { _ = cap(x) }
+func _[T interface{ ~[]byte }](x T) { _ = cap(x) }
+func _[T interface{ ~map[int]int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~chan int }](x T) { _ = cap(x) }
+func _[T interface{ ~[]byte | ~chan int }](x T) { _ = cap(x) }
 
 // range iteration
 
@@ -144,64 +149,136 @@
         for range x /* ERROR cannot range */ {}
 }
 
-func _[T interface{ type string, []string }](x T) {
-        for range x {}
-        for i := range x { _ = i }
-        for i, _ := range x { _ = i }
-        for i, e := range x /* ERROR must have the same element type */ { _ = i }
-        for _, e := range x /* ERROR must have the same element type */ {}
-        var e rune
-        _ = e
-        for _, (e) = range x /* ERROR must have the same element type */ {}
-}
+type myString string
 
+func _[
+        B1 interface{ string },
+        B2 interface{ string | myString },
 
-func _[T interface{ type string, []rune, map[int]rune }](x T) {
-        for _, e := range x { _ = e }
-        for i, e := range x { _ = i; _ = e }
-}
+        C1 interface{ chan int },
+        C2 interface{ chan int | <-chan int },
+        C3 interface{ chan<- int },
 
-func _[T interface{ type string, []rune, map[string]rune }](x T) {
-        for _, e := range x { _ = e }
-        for i, e := range x /* ERROR must have the same key type */ { _ = e }
-}
+        S1 interface{ []int },
+        S2 interface{ []int | [10]int },
 
-func _[T interface{ type string, chan int }](x T) {
-        for range x {}
-        for i := range x { _ = i }
-        for i, _ := range x { _ = i } // TODO(gri) should get an error here: channels only return one value
-}
+        A1 interface{ [10]int },
+        A2 interface{ [10]int | []int },
 
-func _[T interface{ type string, chan<-int }](x T) {
-        for i := range x /* ERROR send-only channel */ { _ = i }
+        P1 interface{ *[10]int },
+        P2 interface{ *[10]int | *[]int },
+
+        M1 interface{ map[string]int },
+        M2 interface{ map[string]int | map[string]string },
+]() {
+        var b0 string
+        for range b0 {}
+        for _ = range b0 {}
+        for _, _ = range b0 {}
+
+        var b1 B1
+        for range b1 {}
+        for _ = range b1 {}
+        for _, _ = range b1 {}
+
+        var b2 B2
+        for range b2 /* ERROR cannot range over b2 .* no structural type */ {}
+
+        var c0 chan int
+        for range c0 {}
+        for _ = range c0 {}
+        for _, _ /* ERROR permits only one iteration variable */ = range c0 {}
+
+        var c1 C1
+        for range c1 {}
+        for _ = range c1 {}
+        for _, _ /* ERROR permits only one iteration variable */ = range c1 {}
+
+        var c2 C2
+        for range c2 /* ERROR cannot range over c2 .* no structural type */ {}
+
+        var c3 C3
+        for range c3 /* ERROR receive from send-only channel */ {}
+
+        var s0 []int
+        for range s0 {}
+        for _ = range s0 {}
+        for _, _ = range s0 {}
+
+        var s1 S1
+        for range s1 {}
+        for _ = range s1 {}
+        for _, _ = range s1 {}
+
+        var s2 S2
+        for range s2 /* ERROR cannot range over s2 .* no structural type */ {}
+
+        var a0 []int
+        for range a0 {}
+        for _ = range a0 {}
+        for _, _ = range a0 {}
+
+        var a1 A1
+        for range a1 {}
+        for _ = range a1 {}
+        for _, _ = range a1 {}
+
+        var a2 A2
+        for range a2 /* ERROR cannot range over a2 .* no structural type */ {}
+
+        var p0 *[10]int
+        for range p0 {}
+        for _ = range p0 {}
+        for _, _ = range p0 {}
+
+        var p1 P1
+        for range p1 {}
+        for _ = range p1 {}
+        for _, _ = range p1 {}
+
+        var p2 P2
+        for range p2 /* ERROR cannot range over p2 .* no structural type */ {}
+
+        var m0 map[string]int
+        for range m0 {}
+        for _ = range m0 {}
+        for _, _ = range m0 {}
+
+        var m1 M1
+        for range m1 {}
+        for _ = range m1 {}
+        for _, _ = range m1 {}
+
+        var m2 M2
+        for range m2 /* ERROR cannot range over m2 .* no structural type */ {}
 }
 
 // type inference checks
 
 var _ = new() /* ERROR cannot infer T */
 
-func f4[A, B, C any](A, B) C
+func f4[A, B, C any](A, B) C { panic(0) }
 
 var _ = f4(1, 2) /* ERROR cannot infer C */
 var _ = f4[int, float32, complex128](1, 2)
 
-func f5[A, B, C any](A, []*B, struct{f []C}) int
+func f5[A, B, C any](A, []*B, struct{f []C}) int { panic(0) }
 
 var _ = f5[int, float32, complex128](0, nil, struct{f []complex128}{})
 var _ = f5(0, nil, struct{f []complex128}{}) // ERROR cannot infer
 var _ = f5(0, []*float32{new[float32]()}, struct{f []complex128}{})
 
-func f6[A any](A, []A) int
+func f6[A any](A, []A) int { panic(0) }
 
 var _ = f6(0, nil)
 
-func f6nil[A any](A) int
+func f6nil[A any](A) int { panic(0) }
 
 var _ = f6nil(nil) // ERROR cannot infer
 
 // type inference with variadic functions
 
-func f7[T any](...T) T
+func f7[T any](...T) T { panic(0) }
 
 var _ int = f7() /* ERROR cannot infer T */
 var _ int = f7(1)
@@ -214,7 +291,7 @@
 var _ = f7(1, 2.3 /* ERROR does not match */ )
 var _ = f7(1.2, 3 /* ERROR does not match */ )
 
-func f8[A, B any](A, B, ...B) int
+func f8[A, B any](A, B, ...B) int { panic(0) }
 
 var _ = f8(1) /* ERROR not enough arguments */
 var _ = f8(1, 2.3)
@@ -241,7 +318,7 @@
 
 type S1[P any] struct { f P }
 
-func f9[P any](x S1[P])
+func f9[P any](x S1[P]) {}
 
 func _() {
         f9[int](S1[int]{42})
@@ -250,7 +327,7 @@
 
 type S2[A, B, C any] struct{}
 
-func f10[X, Y, Z any](a S2[X, int, Z], b S2[X, Y, bool])
+func f10[X, Y, Z any](a S2[X, int, Z], b S2[X, Y, bool]) {}
 
 func _[P any]() {
         f10[int, float32, string](S2[int, int, string]{}, S2[int, float32, bool]{})
@@ -261,7 +338,7 @@
 // corner case for type inference
 // (was bug: after instanting f11, the type-checker didn't mark f11 as non-generic)
 
-func f11[T any]()
+func f11[T any]() {}
 
 func _() {
 	f11[int]()
@@ -269,7 +346,7 @@
 
 // the previous example was extracted from
 
-func f12[T interface{m() T}]()
+func f12[T interface{m() T}]() {}
 
 type A[T any] T
 
@@ -297,15 +374,15 @@
 
 type R0 struct{}
 
-func (R0) _[T any](x T)
-func (R0 /* ERROR invalid receiver */ ) _[R0 any]() // scope of type parameters starts at "func"
+func (R0) _[T any](x T) {}
+func (R0 /* ERROR invalid receiver */ ) _[R0 any]() {} // scope of type parameters starts at "func"
 
 type R1[A, B any] struct{}
 
 func (_ R1[A, B]) m0(A, B)
-func (_ R1[A, B]) m1[T any](A, B, T) T
+func (_ R1[A, B]) m1[T any](A, B, T) T { panic(0) }
 func (_ R1 /* ERROR not a generic type */ [R1, _]) _()
-func (_ R1[A, B]) _[A /* ERROR redeclared */ any](B)
+func (_ R1[A, B]) _[A /* ERROR redeclared */ any](B) {}
 
 func _() {
         var r R1[int, string]
@@ -400,7 +477,7 @@
 	}
 }
 
-func _[T interface{type int}](x T) {
+func _[T interface{~int}](x T) {
 	_ = x /* ERROR not an interface */ .(int)
 	switch x /* ERROR not an interface */ .(type) {
 	}
diff --git a/src/cmd/compile/internal/types2/testdata/check/unions.go2 b/src/cmd/compile/internal/types2/testdata/check/unions.go2
new file mode 100644
index 0000000..bcd7de6
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/check/unions.go2
@@ -0,0 +1,66 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Check that overlong unions don't bog down type checking.
+// Disallow them for now.
+
+package p
+
+type t int
+
+type (
+	t00 t; t01 t; t02 t; t03 t; t04 t; t05 t; t06 t; t07 t; t08 t; t09 t
+	t10 t; t11 t; t12 t; t13 t; t14 t; t15 t; t16 t; t17 t; t18 t; t19 t
+	t20 t; t21 t; t22 t; t23 t; t24 t; t25 t; t26 t; t27 t; t28 t; t29 t
+	t30 t; t31 t; t32 t; t33 t; t34 t; t35 t; t36 t; t37 t; t38 t; t39 t
+	t40 t; t41 t; t42 t; t43 t; t44 t; t45 t; t46 t; t47 t; t48 t; t49 t
+	t50 t; t51 t; t52 t; t53 t; t54 t; t55 t; t56 t; t57 t; t58 t; t59 t
+	t60 t; t61 t; t62 t; t63 t; t64 t; t65 t; t66 t; t67 t; t68 t; t69 t
+	t70 t; t71 t; t72 t; t73 t; t74 t; t75 t; t76 t; t77 t; t78 t; t79 t
+	t80 t; t81 t; t82 t; t83 t; t84 t; t85 t; t86 t; t87 t; t88 t; t89 t
+	t90 t; t91 t; t92 t; t93 t; t94 t; t95 t; t96 t; t97 t; t98 t; t99 t
+)
+
+type u99 interface {
+	t00|t01|t02|t03|t04|t05|t06|t07|t08|t09|
+	t10|t11|t12|t13|t14|t15|t16|t17|t18|t19|
+	t20|t21|t22|t23|t24|t25|t26|t27|t28|t29|
+	t30|t31|t32|t33|t34|t35|t36|t37|t38|t39|
+	t40|t41|t42|t43|t44|t45|t46|t47|t48|t49|
+	t50|t51|t52|t53|t54|t55|t56|t57|t58|t59|
+	t60|t61|t62|t63|t64|t65|t66|t67|t68|t69|
+	t70|t71|t72|t73|t74|t75|t76|t77|t78|t79|
+	t80|t81|t82|t83|t84|t85|t86|t87|t88|t89|
+	t90|t91|t92|t93|t94|t95|t96|t97|t98
+}
+
+type u100a interface {
+	u99|float32
+}
+
+type u100b interface {
+	u99|float64
+}
+
+type u101 interface {
+	t00|t01|t02|t03|t04|t05|t06|t07|t08|t09|
+	t10|t11|t12|t13|t14|t15|t16|t17|t18|t19|
+	t20|t21|t22|t23|t24|t25|t26|t27|t28|t29|
+	t30|t31|t32|t33|t34|t35|t36|t37|t38|t39|
+	t40|t41|t42|t43|t44|t45|t46|t47|t48|t49|
+	t50|t51|t52|t53|t54|t55|t56|t57|t58|t59|
+	t60|t61|t62|t63|t64|t65|t66|t67|t68|t69|
+	t70|t71|t72|t73|t74|t75|t76|t77|t78|t79|
+	t80|t81|t82|t83|t84|t85|t86|t87|t88|t89|
+	t90|t91|t92|t93|t94|t95|t96|t97|t98|t99|
+        int // ERROR cannot handle more than 100 union terms
+}
+
+type u102 interface {
+        int /* ERROR cannot handle more than 100 union terms */ |string|u100a
+}
+
+type u200 interface {
+        u100a /* ERROR cannot handle more than 100 union terms */ |u100b
+}
diff --git a/src/cmd/compile/internal/types2/testdata/examples/constraints.go2 b/src/cmd/compile/internal/types2/testdata/examples/constraints.go2
new file mode 100644
index 0000000..f40d18c
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/examples/constraints.go2
@@ -0,0 +1,91 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file shows some examples of generic constraint interfaces.
+
+package p
+
+type (
+	// Type lists are processed as unions but an error is reported.
+	// TODO(gri) remove this once the parser doesn't accept type lists anymore.
+	_ interface{
+		type /* ERROR use generalized embedding syntax instead of a type list */ int
+	}
+	_ interface{
+		type /* ERROR use generalized embedding syntax instead of a type list */ int
+		type float32
+	}
+)
+
+type MyInt int
+
+type (
+	// Arbitrary types may be embedded like interfaces.
+	_ interface{int}
+	_ interface{~int}
+
+	// Types may be combined into a union.
+	union interface{int|~string}
+
+	// Union terms must describe disjoint (non-overlapping) type sets.
+	_ interface{int|int /* ERROR overlapping terms int */ }
+	_ interface{int|~ /* ERROR overlapping terms ~int */ int }
+	_ interface{~int|~ /* ERROR overlapping terms ~int */ int }
+	_ interface{~int|MyInt /* ERROR overlapping terms p.MyInt and ~int */ }
+	_ interface{int|interface{}}
+	_ interface{int|~string|union}
+	_ interface{int|~string|interface{int}}
+	_ interface{union|union /* ERROR overlapping terms p.union and p.union */ }
+
+	// For now we do not permit interfaces with methods in unions.
+	_ interface{~ /* ERROR invalid use of ~ */ interface{}}
+	_ interface{int|interface /* ERROR cannot use .* in union */ { m() }}
+)
+
+type (
+	// Tilde is not permitted on defined types or interfaces.
+	foo int
+	bar interface{}
+	_ interface{foo}
+	_ interface{~ /* ERROR invalid use of ~ */ foo }
+	_ interface{~ /* ERROR invalid use of ~ */ bar }
+)
+
+// Stand-alone type parameters are not permitted as elements or terms in unions.
+type (
+	_[T interface{ *T } ] struct{}        // ok
+	_[T interface{ int | *T } ] struct{}  // ok
+	_[T interface{ T /* ERROR cannot embed a type parameter */ } ] struct{}
+	_[T interface{ ~T /* ERROR cannot embed a type parameter */ } ] struct{}
+	_[T interface{ int|T /* ERROR cannot embed a type parameter */ }] struct{}
+)
+
+// Multiple embedded union elements are intersected. The order in which they
+// appear in the interface doesn't matter since intersection is a symmetric
+// operation.
+
+type myInt1 int
+type myInt2 int
+
+func _[T interface{ myInt1|myInt2; ~int }]() T { return T(0) }
+func _[T interface{ ~int; myInt1|myInt2 }]() T { return T(0) }
+
+// Here the intersections are empty - there's no type that's in the type set of T.
+func _[T interface{ myInt1|myInt2; int }]() T { return T(0 /* ERROR cannot convert */ ) }
+func _[T interface{ int; myInt1|myInt2 }]() T { return T(0 /* ERROR cannot convert */ ) }
+
+// Union elements may be interfaces as long as they don't define
+// any methods or embed comparable.
+
+type (
+	Integer interface{ ~int|~int8|~int16|~int32|~int64 }
+	Unsigned interface{ ~uint|~uint8|~uint16|~uint32|~uint64 }
+	Floats interface{ ~float32|~float64 }
+	Complex interface{ ~complex64|~complex128 }
+	Number interface{ Integer|Unsigned|Floats|Complex }
+	Ordered interface{ Integer|Unsigned|Floats|~string }
+
+	_ interface{ Number | error /* ERROR cannot use error in union */ }
+	_ interface{ Ordered | comparable /* ERROR cannot use comparable in union */ }
+)
diff --git a/src/cmd/compile/internal/types2/testdata/examples/functions.go2 b/src/cmd/compile/internal/types2/testdata/examples/functions.go2
index 0c2a408..ef8953c 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/functions.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/functions.go2
@@ -66,7 +66,7 @@
 
 // Type inference works in a straight-forward manner even
 // for variadic functions.
-func variadic[A, B any](A, B, ...B) int
+func variadic[A, B any](A, B, ...B) int { panic(0) }
 
 // var _ = variadic(1) // ERROR not enough arguments
 var _ = variadic(1, 2.3)
@@ -98,7 +98,7 @@
 // Here's an example of a recursive function call with variadic
 // arguments and type inference inferring the type parameter of
 // the caller (i.e., itself).
-func max[T interface{ type int }](x ...T) T {
+func max[T interface{ ~int }](x ...T) T {
 	var x0 T
 	if len(x) > 0 {
 		x0 = x[0]
@@ -118,9 +118,9 @@
 // Thus even if a type can be inferred successfully, the function
 // call may not be valid.
 
-func fboth[T any](chan T)
-func frecv[T any](<-chan T)
-func fsend[T any](chan<- T)
+func fboth[T any](chan T) {}
+func frecv[T any](<-chan T) {}
+func fsend[T any](chan<- T) {}
 
 func _() {
 	var both chan int
@@ -140,9 +140,9 @@
 	fsend(send)
 }
 
-func ffboth[T any](func(chan T))
-func ffrecv[T any](func(<-chan T))
-func ffsend[T any](func(chan<- T))
+func ffboth[T any](func(chan T)) {}
+func ffrecv[T any](func(<-chan T)) {}
+func ffsend[T any](func(chan<- T)) {}
 
 func _() {
 	var both func(chan int)
@@ -169,9 +169,9 @@
 // assignment is permitted, parameter passing is permitted as well,
 // so type inference should be able to handle these cases well.
 
-func g1[T any]([]T)
-func g2[T any]([]T, T)
-func g3[T any](*T, ...T)
+func g1[T any]([]T) {}
+func g2[T any]([]T, T) {}
+func g3[T any](*T, ...T) {}
 
 func _() {
 	type intSlize []int
@@ -195,7 +195,7 @@
 
 // Here's a realistic example.
 
-func append[T any](s []T, t ...T) []T
+func append[T any](s []T, t ...T) []T { panic(0) }
 
 func _() {
 	var f func()
@@ -208,8 +208,12 @@
 // (that would indicate a slice type). Thus, generic functions cannot
 // have empty type parameter lists, either. This is a syntax error.
 
-func h[] /* ERROR empty type parameter list */ ()
+func h[] /* ERROR empty type parameter list */ () {}
 
 func _() {
 	h[] /* ERROR operand */ ()
 }
+
+// Parameterized functions must have a function body.
+
+func _ /* ERROR missing function body */ [P any]()
diff --git a/src/cmd/compile/internal/types2/testdata/examples/inference.go2 b/src/cmd/compile/internal/types2/testdata/examples/inference.go2
index b47ce75..e169aec 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/inference.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/inference.go2
@@ -7,10 +7,10 @@
 package p
 
 type Ordered interface {
-	type int, float64, string
+	~int|~float64|~string
 }
 
-func min[T Ordered](x, y T) T
+func min[T Ordered](x, y T) T { panic(0) }
 
 func _() {
 	// min can be called with explicit instantiation.
@@ -37,7 +37,7 @@
 	_ = min("foo", "bar")
 }
 
-func mixed[T1, T2, T3 any](T1, T2, T3)
+func mixed[T1, T2, T3 any](T1, T2, T3) {}
 
 func _() {
 	// mixed can be called with explicit instantiation.
@@ -54,7 +54,7 @@
 	mixed[int, string](1.1 /* ERROR cannot use 1.1 */ , "", false)
 }
 
-func related1[Slice interface{type []Elem}, Elem any](s Slice, e Elem)
+func related1[Slice interface{~[]Elem}, Elem any](s Slice, e Elem) {}
 
 func _() {
 	// related1 can be called with explicit instantiation.
@@ -78,7 +78,7 @@
 	related1(si, "foo" /* ERROR cannot use "foo" */ )
 }
 
-func related2[Elem any, Slice interface{type []Elem}](e Elem, s Slice)
+func related2[Elem any, Slice interface{~[]Elem}](e Elem, s Slice) {}
 
 func _() {
 	// related2 can be called with explicit instantiation.
diff --git a/src/cmd/compile/internal/types2/testdata/examples/methods.go2 b/src/cmd/compile/internal/types2/testdata/examples/methods.go2
index 76c6539..4e87041 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/methods.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/methods.go2
@@ -6,6 +6,8 @@
 
 package p
 
+import "unsafe"
+
 // Parameterized types may have methods.
 type T1[A any] struct{ a A }
 
@@ -94,3 +96,18 @@
 type T0 struct{}
 func (T0) _() {}
 func (T1[A]) _() {}
+
+// A generic receiver type may constrain its type parameter such
+// that it must be a pointer type. Such receiver types are not
+// permitted.
+type T3a[P interface{ ~int | ~string | ~float64 }] P
+
+func (T3a[_]) m() {} // this is ok
+
+type T3b[P interface{ ~unsafe.Pointer }] P
+
+func (T3b /* ERROR invalid receiver */ [_]) m() {}
+
+type T3c[P interface{ *int | *string }] P
+
+func (T3c /* ERROR invalid receiver */ [_]) m() {}
diff --git a/src/cmd/compile/internal/types2/testdata/examples/operations.go2 b/src/cmd/compile/internal/types2/testdata/examples/operations.go2
new file mode 100644
index 0000000..18e4d60
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/examples/operations.go2
@@ -0,0 +1,29 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// indirection
+
+func _[P any](p P) {
+        _ = *p // ERROR cannot indirect p
+}
+
+func _[P interface{ int }](p P) {
+        _ = *p // ERROR cannot indirect p
+}
+
+func _[P interface{ *int }](p P) {
+        _ = *p
+}
+
+func _[P interface{ *int | *string }](p P) {
+        _ = *p // ERROR must have identical base types
+}
+
+type intPtr *int
+
+func _[P interface{ *int | intPtr } ](p P) {
+        var _ int = *p
+}
diff --git a/src/cmd/compile/internal/types2/testdata/examples/types.go2 b/src/cmd/compile/internal/types2/testdata/examples/types.go2
index a7825ed..d662444 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/types.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/types.go2
@@ -155,30 +155,40 @@
 	List /* ERROR List redeclared */ [int]
 }
 
+// Issue #45639: We don't allow this anymore. Keep this code
+//               in case we decide to revisit this decision.
+//
 // It's possible to declare local types whose underlying types
 // are type parameters. As with ordinary type definitions, the
 // types underlying properties are "inherited" but the methods
 // are not.
-func _[T interface{ m(); type int }]() {
-	type L T
-	var x L
+// func _[T interface{ m(); ~int }]() {
+// 	type L T
+// 	var x L
+// 
+// 	// m is not defined on L (it is not "inherited" from
+// 	// its underlying type).
+// 	x.m /* ERROR x.m undefined */ ()
+// 
+// 	// But the properties of T, such that as that it supports
+// 	// the operations of the types given by its type bound,
+// 	// are also the properties of L.
+// 	x++
+// 	_ = x - x
+// 
+// 	// On the other hand, if we define a local alias for T,
+// 	// that alias stands for T as expected.
+// 	type A = T
+// 	var y A
+// 	y.m()
+// 	_ = y < 0
+// }
 
-	// m is not defined on L (it is not "inherited" from
-	// its underlying type).
-	x.m /* ERROR x.m undefined */ ()
-
-	// But the properties of T, such that as that it supports
-	// the operations of the types given by its type bound,
-	// are also the properties of L.
-	x++
-	_ = x - x
-
-	// On the other hand, if we define a local alias for T,
-	// that alias stands for T as expected.
-	type A = T
-	var y A
-	y.m()
-	_ = y < 0
+// It is not permitted to declare a local type whose underlying
+// type is a type parameters not declared by that type declaration.
+func _[T any]() {
+	type _ T         // ERROR cannot use function type parameter T as RHS in type declaration
+	type _ [_ any] T // ERROR cannot use function type parameter T as RHS in type declaration
 }
 
 // As a special case, an explicit type argument may be omitted
@@ -206,15 +216,15 @@
 type B1[_ any] interface{}
 type B2[_, _ any] interface{}
 
-func _[T1 B0]()
-func _[T1 B1[T1]]()
-func _[T1 B2 /* ERROR cannot use generic type .* without instantiation */ ]()
+func _[T1 B0]() {}
+func _[T1 B1[T1]]() {}
+func _[T1 B2 /* ERROR cannot use generic type .* without instantiation */ ]() {}
 
-func _[T1, T2 B0]()
-func _[T1 B1[T1], T2 B1[T2]]()
-func _[T1, T2 B2 /* ERROR cannot use generic type .* without instantiation */ ]()
+func _[T1, T2 B0]() {}
+func _[T1 B1[T1], T2 B1[T2]]() {}
+func _[T1, T2 B2 /* ERROR cannot use generic type .* without instantiation */ ]() {}
 
-func _[T1 B0, T2 B1[T2]]() // here B1 applies to T2
+func _[T1 B0, T2 B1[T2]]() {} // here B1 applies to T2
 
 // When the type argument is left away, the type bound is
 // instantiated for each type parameter with that type
@@ -232,11 +242,11 @@
 // The type of variables (incl. parameters and return values) cannot
 // be an interface with type constraints or be/embed comparable.
 type I interface {
-	type int
+	~int
 }
 
 var (
-	_ interface /* ERROR contains type constraints */ {type int}
+	_ interface /* ERROR contains type constraints */ {~int}
 	_ I /* ERROR contains type constraints */
 )
 
@@ -267,7 +277,7 @@
 // (If a type list contains just a single const type, we could
 // allow it, but such type lists don't make much sense in the
 // first place.)
-func _[T interface { type int, float64 }]() {
+func _[T interface{~int|~float64}]() {
 	// not valid
 	const _ = T /* ERROR not constant */ (0)
 	const _ T /* ERROR invalid constant type T */ = 1
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39634.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39634.go2
index 2c1299f..8d14f8a 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39634.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39634.go2
@@ -31,13 +31,14 @@
 func main7() { var _ foo7 = x7[int]{} }
 
 // crash 8
-type foo8[A any] interface { type A }
-func bar8[A foo8[A]](a A) {}
-func main8() {}
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+// type foo8[A any] interface { ~A }
+// func bar8[A foo8[A]](a A) {}
+// func main8() {}
 
 // crash 9
-type foo9[A any] interface { type foo9 /* ERROR interface contains type constraints */ [A] }
-func _() { var _ = new(foo9 /* ERROR interface contains type constraints */ [int]) }
+type foo9[A any] interface { foo9 /* ERROR illegal cycle */ [A] }
+func _() { var _ = new(foo9 /* ERROR illegal cycle */ [int]) }
 
 // crash 12
 var u /* ERROR cycle */ , i [func /* ERROR used as value */ /* ERROR used as value */ (u, c /* ERROR undeclared */ /* ERROR undeclared */ ) {}(0, len /* ERROR must be called */ /* ERROR must be called */ )]c /* ERROR undeclared */ /* ERROR undeclared */
@@ -49,7 +50,7 @@
 
 // crash 16
 type Foo16[T any] r16 /* ERROR not a type */
-func r16[T any]() Foo16[Foo16[T]]
+func r16[T any]() Foo16[Foo16[T]] { panic(0) }
 
 // crash 17
 type Y17 interface{ c() }
@@ -57,7 +58,7 @@
 	c() Y17
 	Y17 /* ERROR duplicate method */
 }
-func F17[T Z17](T)
+func F17[T Z17](T) {}
 
 // crash 18
 type o18[T any] []func(_ o18[[]_ /* ERROR cannot use _ */ ])
@@ -87,5 +88,5 @@
 func F26[Z any]() T26 { return F26 /* ERROR without instantiation */ /* ERROR missing method */ [] /* ERROR operand */ }
 
 // crash 27
-func e27[T any]() interface{ x27 /* ERROR not a type */ }
+func e27[T any]() interface{ x27 /* ERROR not a type */ } { panic(0) }
 func x27() { e27( /* ERROR cannot infer T */ ) }
\ No newline at end of file
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39680.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39680.go2
index 9bc26f3..e56bc35 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39680.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39680.go2
@@ -4,16 +4,19 @@
 
 package p
 
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+
+/*
 import "fmt"
 
 // Minimal test case.
-func _[T interface{type T}](x T) T{
+func _[T interface{~T}](x T) T{
 	return x
 }
 
 // Test case from issue.
 type constr[T any] interface {
-	type T
+	~T
 }
 
 func Print[T constr[T]](s []T) {
@@ -25,3 +28,4 @@
 func f() {
 	Print([]string{"Hello, ", "playground\n"})
 }
+*/
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39693.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39693.go2
index 316ab19..301c13b 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39693.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39693.go2
@@ -4,11 +4,20 @@
 
 package p
 
-type Number interface {
-	int     /* ERROR int is not an interface */
-	float64 /* ERROR float64 is not an interface */
+type Number1 interface {
+	// embedding non-interface types is permitted
+	int
+	float64
 }
 
-func Add[T Number](a, b T) T {
+func Add1[T Number1](a, b T) T {
 	return a /* ERROR not defined */ + b
 }
+
+type Number2 interface {
+	int|float64
+}
+
+func Add2[T Number2](a, b T) T {
+	return a + b
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39699.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39699.go2
index 75491e7..72f8399 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39699.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39699.go2
@@ -8,7 +8,7 @@
 }
 
 type T1 interface{
-	type int
+	~int
 }
 
 type T2 interface{
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39711.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39711.go2
index df621a4..85eb0a7 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39711.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39711.go2
@@ -7,5 +7,7 @@
 // Do not report a duplicate type error for this type list.
 // (Check types after interfaces have been completed.)
 type _ interface {
-	type interface{ Error() string }, interface{ String() string }
+	// TODO(gri) Once we have full type sets we can enable this again.
+	// Fow now we don't permit interfaces in type lists.
+	// type interface{ Error() string }, interface{ String() string }
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39723.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39723.go2
index 55464e6..d5311ed 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39723.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39723.go2
@@ -6,4 +6,4 @@
 
 // A constraint must be an interface; it cannot
 // be a type parameter, for instance.
-func _[A interface{ type interface{} }, B A /* ERROR not an interface */ ]()
+func _[A interface{ ~int }, B A /* ERROR not an interface */ ]() {}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39725.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39725.go2
index e19b677..62dc45a 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39725.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39725.go2
@@ -4,13 +4,13 @@
 
 package p
 
-func f1[T1, T2 any](T1, T2, struct{a T1; b T2})
+func f1[T1, T2 any](T1, T2, struct{a T1; b T2}) {}
 func _() {
 	f1(42, string("foo"), struct /* ERROR does not match inferred type struct\{a int; b string\} */ {a, b int}{})
 }
 
 // simplified test case from issue
-func f2[T any](_ []T, _ func(T))
+func f2[T any](_ []T, _ func(T)) {}
 func _() {
 	f2([]string{}, func /* ERROR does not match inferred type func\(string\) */ (f []byte) {})
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go2
index b7ab688..257b73a 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go2
@@ -4,14 +4,14 @@
 
 package p
 
-func _[T interface{type map[string]int}](x T) {
+func _[T interface{~map[string]int}](x T) {
 	_ = x == nil
 }
 
 // simplified test case from issue
 
 type PathParamsConstraint interface {
-        type map[string]string, []struct{key, value string}
+        ~map[string]string | ~[]struct{key, value string}
 }
 
 type PathParams[T PathParamsConstraint] struct {
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39938.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39938.go2
index 76e7e36..0da6e10 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39938.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39938.go2
@@ -8,8 +8,8 @@
 
 type E0[P any] P
 type E1[P any] *P
-type E2[P any] struct{ P }
-type E3[P any] struct{ *P }
+type E2[P any] struct{ _ P }
+type E3[P any] struct{ _ *P }
 
 type T0 /* ERROR illegal cycle */ struct {
         _ E0[T0]
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39948.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39948.go2
index c2b4609..e38e572 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39948.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39948.go2
@@ -5,5 +5,5 @@
 package p
 
 type T[P any] interface{
-	P // ERROR P is a type parameter, not an interface
+	P // ERROR cannot embed a type parameter
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39976.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39976.go2
index 3db4eae..d703da9 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39976.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue39976.go2
@@ -7,7 +7,7 @@
 type policy[K, V any] interface{}
 type LRU[K, V any] struct{}
 
-func NewCache[K, V any](p policy[K, V])
+func NewCache[K, V any](p policy[K, V]) {}
 
 func _() {
 	var lru LRU[int, string]
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40038.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40038.go2
index 8948d61..0981a33 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40038.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40038.go2
@@ -8,7 +8,7 @@
 
 func (A[T]) m(A[T])
 
-func f[P interface{m(P)}]()
+func f[P interface{m(P)}]() {}
 
 func _() {
 	_ = f[A[int]]
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40056.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40056.go2
index 747aab4..a3f3eec 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40056.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40056.go2
@@ -10,6 +10,6 @@
 
 type S struct {}
 
-func NewS[T any]() *S
+func NewS[T any]() *S { panic(0) }
 
 func (_ *S /* ERROR S is not a generic type */ [T]) M()
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40301.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40301.go2
index 5d97855..c78f9a1 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40301.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40301.go2
@@ -7,6 +7,6 @@
 import "unsafe"
 
 func _[T any](x T) {
-	_ = unsafe /* ERROR undefined */ .Alignof(x)
-	_ = unsafe /* ERROR undefined */ .Sizeof(x)
+	_ = unsafe.Alignof(x)
+	_ = unsafe.Sizeof(x)
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40684.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40684.go2
index 0269c3a..58d0f69 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40684.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40684.go2
@@ -6,8 +6,8 @@
 
 type T[_ any] int
 
-func f[_ any]()
-func g[_, _ any]()
+func f[_ any]() {}
+func g[_, _ any]() {}
 
 func _() {
 	_ = f[T /* ERROR without instantiation */ ]
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40789.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40789.go2
new file mode 100644
index 0000000..9eea4ad
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue40789.go2
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+func main() {
+	m := map[string]int{
+		"a": 6,
+		"b": 7,
+	}
+	fmt.Println(copyMap[map[string]int, string, int](m))
+}
+
+type Map[K comparable, V any] interface {
+	map[K] V
+}
+
+func copyMap[M Map[K, V], K comparable, V any](m M) M {
+	m1 := make(M)
+	for k, v := range m {
+		m1[k] = v
+	}
+	return m1
+}
+
+// simpler test case from the same issue
+
+type A[X comparable] interface {
+	[]X
+}
+
+func f[B A[X], X comparable]() B {
+	return nil
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2
index 61f766b..4642ab6 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2
@@ -7,7 +7,7 @@
 // Test case from issue.
 
 type Nat interface {
-	type Zero, Succ
+	Zero|Succ
 }
 
 type Zero struct{}
@@ -22,7 +22,7 @@
 }
 
 type I2 interface {
-	type int
+	~int
 }
 
 type I3 interface {
@@ -47,7 +47,7 @@
 }
 
 type _ struct{
-	I3 // ERROR interface contains type constraints
+	I3 // ERROR interface is .* comparable
 }
 
 // General composite types.
@@ -59,19 +59,19 @@
 	_ []I1 // ERROR interface is .* comparable
 	_ []I2 // ERROR interface contains type constraints
 
-	_ *I3 // ERROR interface contains type constraints
+	_ *I3 // ERROR interface is .* comparable
 	_ map[I1 /* ERROR interface is .* comparable */ ]I2 // ERROR interface contains type constraints
-	_ chan I3 // ERROR interface contains type constraints
+	_ chan I3 // ERROR interface is .* comparable
 	_ func(I1 /* ERROR interface is .* comparable */ )
 	_ func() I2 // ERROR interface contains type constraints
 )
 
 // Other cases.
 
-var _ = [...]I3 /* ERROR interface contains type constraints */ {}
+var _ = [...]I3 /* ERROR interface is .* comparable */ {}
 
 func _(x interface{}) {
-	_ = x.(I3 /* ERROR interface contains type constraints */ )
+	_ = x.(I3 /* ERROR interface is .* comparable */ )
 }
 
 type T1[_ any] struct{}
@@ -79,9 +79,9 @@
 var _ T1[I2 /* ERROR interface contains type constraints */ ]
 var _ T3[int, I2 /* ERROR interface contains type constraints */ , float32]
 
-func f1[_ any]() int
+func f1[_ any]() int { panic(0) }
 var _ = f1[I2 /* ERROR interface contains type constraints */ ]()
-func f3[_, _, _ any]() int
+func f3[_, _, _ any]() int { panic(0) }
 var _ = f3[int, I2 /* ERROR interface contains type constraints */ , float32]()
 
 func _(x interface{}) {
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue42758.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue42758.go2
index 698cb8a..bf0031f 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue42758.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue42758.go2
@@ -17,7 +17,7 @@
 }
 
 type constraint interface {
-	type int
+	~int
 }
 
 func _[T constraint](x interface{}){
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43671.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43671.go2
new file mode 100644
index 0000000..6cc3801
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43671.go2
@@ -0,0 +1,58 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | <-chan T }
+
+func _[T any](ch T) {
+	<-ch // ERROR cannot receive from non-channel
+}
+
+func _[T C0](ch T) {
+	<-ch // ERROR cannot receive from non-channel
+}
+
+func _[T C1](ch T) {
+	<-ch
+}
+
+func _[T C2](ch T) {
+	<-ch
+}
+
+func _[T C3](ch T) {
+	<-ch // ERROR channels of ch .* must have the same element type
+}
+
+func _[T C4](ch T) {
+	<-ch // ERROR cannot receive from send-only channel
+}
+
+func _[T C5[X], X any](ch T, x X) {
+	x = <-ch
+}
+
+// test case from issue, slightly modified
+type RecvChan[T any] interface {
+	~chan T | ~<-chan T
+}
+
+func _[T any, C RecvChan[T]](ch C) T {
+	return <-ch
+}
+
+func f[T any, C interface{ chan T }](ch C) T {
+	return <-ch
+}
+
+func _(ch chan int) {
+	var x int = f(ch) // test constraint type inference for this case
+	_ = x
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
index b1e4249..b8ba0ad 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2
@@ -4,7 +4,7 @@
 
 package p
 
-func f[F interface{type *Q}, G interface{type *R}, Q, R any](q Q, r R) {}
+func f[F interface{~*Q}, G interface{~*R}, Q, R any](q Q, r R) {}
 
 func _() {
 	f[*float64, *int](1, 2)
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45635.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45635.go2
index 65662cd..2937959 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45635.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45635.go2
@@ -13,7 +13,7 @@
 var _ N[] /* ERROR expecting type */
 
 type I interface {
-	type map[int]int, []int
+	~[]int
 }
 
 func _[T I](i, j int) {
@@ -27,6 +27,5 @@
 	_ = s[i, j /* ERROR more than one index */ ]
 
 	var t T
-	// TODO(gri) fix multiple error below
-	_ = t[i, j /* ERROR more than one index */ /* ERROR more than one index */ ]
+	_ = t[i, j /* ERROR more than one index */ ]
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45639.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45639.go2
new file mode 100644
index 0000000..441fb4c
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45639.go2
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package P
+
+// It is not permitted to declare a local type whose underlying
+// type is a type parameters not declared by that type declaration.
+func _[T any]() {
+	type _ T         // ERROR cannot use function type parameter T as RHS in type declaration
+	type _ [_ any] T // ERROR cannot use function type parameter T as RHS in type declaration
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2
index 7678e34..f25b9d2 100644
--- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2
@@ -5,7 +5,7 @@
 package issue45985
 
 // TODO(gri): this error should be on app[int] below.
-func app[S /* ERROR "type S = S does not match" */ interface{ type []T }, T any](s S, e T) S {
+func app[S /* ERROR "type S = S does not match" */ interface{ ~[]T }, T any](s S, e T) S {
     return append(s, e)
 }
 
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46090.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46090.go2
new file mode 100644
index 0000000..81b3197
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46090.go2
@@ -0,0 +1,9 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The predeclared type comparable is not visible before Go 1.18.
+
+package go1_17
+
+type _ comparable // ERROR undeclared
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46275.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46275.go2
new file mode 100644
index 0000000..f41ae26
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46275.go2
@@ -0,0 +1,26 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package issue46275
+
+type N[T any] struct {
+        *N[T]
+        t T
+}
+
+func (n *N[T]) Elem() T {
+        return n.t
+}
+
+type I interface {
+        Elem() string
+}
+
+func _() {
+        var n1 *N[string]
+        var _ I = n1
+        type NS N[string]
+        var n2 *NS
+        var _ I = n2
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src
new file mode 100644
index 0000000..da1f1ff
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src
@@ -0,0 +1,28 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type T1 struct{}
+func (t T1) m(int) {}
+var f1 func(T1)
+
+type T2 struct{}
+func (t T2) m(x int) {}
+var f2 func(T2)
+
+type T3 struct{}
+func (T3) m(int) {}
+var f3 func(T3)
+
+type T4 struct{}
+func (T4) m(x int) {}
+var f4 func(T4)
+
+func _() {
+	f1 = T1 /* ERROR func\(T1, int\) */ .m
+	f2 = T2 /* ERROR func\(t T2, x int\) */ .m
+	f3 = T3 /* ERROR func\(T3, int\) */ .m
+	f4 = T4 /* ERROR func\(_ T4, x int\) */ .m
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2
new file mode 100644
index 0000000..b184f9b
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2
@@ -0,0 +1,20 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type Mer interface { M() }
+
+func F[T Mer](p *T) {
+	p.M /* ERROR p\.M undefined */ ()
+}
+
+type MyMer int
+
+func (MyMer) M() {}
+
+func _() {
+	F(new(MyMer))
+	F[Mer](nil)
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2
new file mode 100644
index 0000000..00828eb
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2
@@ -0,0 +1,40 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+	ch /* ERROR cannot send to non-channel */ <- 0
+}
+
+func _[T C0](ch T) {
+	ch /* ERROR cannot send to non-channel */ <- 0
+}
+
+func _[T C1](ch T) {
+	ch <- 0
+}
+
+func _[T C2](ch T) {
+	ch /* ERROR cannot send to receive-only channel */ <- 0
+}
+
+func _[T C3](ch T) {
+	ch /* ERROR channels of ch .* must have the same element type */ <- 0
+}
+
+func _[T C4](ch T) {
+	ch <- 0
+}
+
+func _[T C5[X], X any](ch T, x X) {
+	ch <- x
+}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47127.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47127.go2
new file mode 100644
index 0000000..108d600
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47127.go2
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Embedding of stand-alone type parameters is not permitted.
+
+package p
+
+type (
+        _[P any] interface{ *P | []P | chan P | map[string]P }
+        _[P any] interface{ P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+)
+
+func _[P any]() {
+        type (
+                _[P any] interface{ *P | []P | chan P | map[string]P }
+                _[P any] interface{ P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+
+                _ interface{ *P | []P | chan P | map[string]P }
+                _ interface{ P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+        )
+}
+
+func _[P any, Q interface{ *P | []P | chan P | map[string]P }]() {}
+func _[P any, Q interface{ P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ ~P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ int | P /* ERROR "cannot embed a type parameter" */ }]() {}
+func _[P any, Q interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }]() {}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47411.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47411.go2
new file mode 100644
index 0000000..77281a1
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47411.go2
@@ -0,0 +1,26 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f[_ comparable]() {}
+func g[_ interface{interface{comparable; ~int|~string}}]() {}
+
+func _[P comparable,
+        Q interface{ comparable; ~int|~string },
+        R any,                               // not comparable
+        S interface{ comparable; ~func() },  // not comparable
+]() {
+        _ = f[int]
+        _ = f[P]
+        _ = f[Q]
+        _ = f[func( /* ERROR does not satisfy comparable */ )]
+        _ = f[R /* ERROR R has no constraints */ ]
+
+        _ = g[int]
+        _ = g[P /* ERROR P has no type constraints */ ]
+        _ = g[Q]
+        _ = g[func( /* ERROR does not satisfy comparable */ )]
+        _ = g[R /* ERROR R has no constraints */ ]
+}
diff --git a/src/cmd/compile/internal/types2/tuple.go b/src/cmd/compile/internal/types2/tuple.go
new file mode 100644
index 0000000..a3946be
--- /dev/null
+++ b/src/cmd/compile/internal/types2/tuple.go
@@ -0,0 +1,36 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
+// Tuples are used as components of signatures and to represent the type of multiple
+// assignments; they are not first class types of Go.
+type Tuple struct {
+	vars []*Var
+}
+
+// NewTuple returns a new tuple for the given variables.
+func NewTuple(x ...*Var) *Tuple {
+	if len(x) > 0 {
+		return &Tuple{vars: x}
+	}
+	// TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer;
+	//           it's too subtle and causes problems.
+	return nil
+}
+
+// Len returns the number variables of tuple t.
+func (t *Tuple) Len() int {
+	if t != nil {
+		return len(t.vars)
+	}
+	return 0
+}
+
+// At returns the i'th variable of tuple t.
+func (t *Tuple) At(i int) *Var { return t.vars[i] }
+
+func (t *Tuple) Underlying() Type { return t }
+func (t *Tuple) String() string   { return TypeString(t, nil) }
diff --git a/src/cmd/compile/internal/types2/type.go b/src/cmd/compile/internal/types2/type.go
index e6c260f..6378296 100644
--- a/src/cmd/compile/internal/types2/type.go
+++ b/src/cmd/compile/internal/types2/type.go
@@ -4,12 +4,6 @@
 
 package types2
 
-import (
-	"cmd/compile/internal/syntax"
-	"fmt"
-	"sync/atomic"
-)
-
 // A Type represents a type of Go.
 // All types implement the Type interface.
 type Type interface {
@@ -22,895 +16,55 @@
 	String() string
 }
 
-// BasicKind describes the kind of basic type.
-type BasicKind int
-
-const (
-	Invalid BasicKind = iota // type is invalid
-
-	// predeclared types
-	Bool
-	Int
-	Int8
-	Int16
-	Int32
-	Int64
-	Uint
-	Uint8
-	Uint16
-	Uint32
-	Uint64
-	Uintptr
-	Float32
-	Float64
-	Complex64
-	Complex128
-	String
-	UnsafePointer
-
-	// types for untyped values
-	UntypedBool
-	UntypedInt
-	UntypedRune
-	UntypedFloat
-	UntypedComplex
-	UntypedString
-	UntypedNil
-
-	// aliases
-	Byte = Uint8
-	Rune = Int32
-)
-
-// BasicInfo is a set of flags describing properties of a basic type.
-type BasicInfo int
-
-// Properties of basic types.
-const (
-	IsBoolean BasicInfo = 1 << iota
-	IsInteger
-	IsUnsigned
-	IsFloat
-	IsComplex
-	IsString
-	IsUntyped
-
-	IsOrdered   = IsInteger | IsFloat | IsString
-	IsNumeric   = IsInteger | IsFloat | IsComplex
-	IsConstType = IsBoolean | IsNumeric | IsString
-)
-
-// A Basic represents a basic type.
-type Basic struct {
-	kind BasicKind
-	info BasicInfo
-	name string
-}
-
-// Kind returns the kind of basic type b.
-func (b *Basic) Kind() BasicKind { return b.kind }
-
-// Info returns information about properties of basic type b.
-func (b *Basic) Info() BasicInfo { return b.info }
-
-// Name returns the name of basic type b.
-func (b *Basic) Name() string { return b.name }
-
-// An Array represents an array type.
-type Array struct {
-	len  int64
-	elem Type
-}
-
-// NewArray returns a new array type for the given element type and length.
-// A negative length indicates an unknown length.
-func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} }
-
-// Len returns the length of array a.
-// A negative result indicates an unknown length.
-func (a *Array) Len() int64 { return a.len }
-
-// Elem returns element type of array a.
-func (a *Array) Elem() Type { return a.elem }
-
-// A Slice represents a slice type.
-type Slice struct {
-	elem Type
-}
-
-// NewSlice returns a new slice type for the given element type.
-func NewSlice(elem Type) *Slice { return &Slice{elem: elem} }
-
-// Elem returns the element type of slice s.
-func (s *Slice) Elem() Type { return s.elem }
-
-// A Struct represents a struct type.
-type Struct struct {
-	fields []*Var
-	tags   []string // field tags; nil if there are no tags
-}
-
-// NewStruct returns a new struct with the given fields and corresponding field tags.
-// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
-// only as long as required to hold the tag with the largest index i. Consequently,
-// if no field has a tag, tags may be nil.
-func NewStruct(fields []*Var, tags []string) *Struct {
-	var fset objset
-	for _, f := range fields {
-		if f.name != "_" && fset.insert(f) != nil {
-			panic("multiple fields with the same name")
-		}
-	}
-	if len(tags) > len(fields) {
-		panic("more tags than fields")
-	}
-	return &Struct{fields: fields, tags: tags}
-}
-
-// NumFields returns the number of fields in the struct (including blank and embedded fields).
-func (s *Struct) NumFields() int { return len(s.fields) }
-
-// Field returns the i'th field for 0 <= i < NumFields().
-func (s *Struct) Field(i int) *Var { return s.fields[i] }
-
-// Tag returns the i'th field tag for 0 <= i < NumFields().
-func (s *Struct) Tag(i int) string {
-	if i < len(s.tags) {
-		return s.tags[i]
-	}
-	return ""
-}
-
-// A Pointer represents a pointer type.
-type Pointer struct {
-	base Type // element type
-}
-
-// NewPointer returns a new pointer type for the given element (base) type.
-func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
-
-// Elem returns the element type for the given pointer p.
-func (p *Pointer) Elem() Type { return p.base }
-
-// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
-// Tuples are used as components of signatures and to represent the type of multiple
-// assignments; they are not first class types of Go.
-type Tuple struct {
-	vars []*Var
-}
-
-// NewTuple returns a new tuple for the given variables.
-func NewTuple(x ...*Var) *Tuple {
-	if len(x) > 0 {
-		return &Tuple{vars: x}
-	}
-	// TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer;
-	//           it's too subtle and causes problems.
-	return nil
-}
-
-// Len returns the number variables of tuple t.
-func (t *Tuple) Len() int {
-	if t != nil {
-		return len(t.vars)
-	}
-	return 0
-}
-
-// At returns the i'th variable of tuple t.
-func (t *Tuple) At(i int) *Var { return t.vars[i] }
-
-// A Signature represents a (non-builtin) function or method type.
-// The receiver is ignored when comparing signatures for identity.
-type Signature struct {
-	// We need to keep the scope in Signature (rather than passing it around
-	// and store it in the Func Object) because when type-checking a function
-	// literal we call the general type checker which returns a general Type.
-	// We then unpack the *Signature and use the scope for the literal body.
-	rparams  []*TypeName // receiver type parameters from left to right; or nil
-	tparams  []*TypeName // type parameters from left to right; or nil
-	scope    *Scope      // function scope, present for package-local signatures
-	recv     *Var        // nil if not a method
-	params   *Tuple      // (incoming) parameters from left to right; or nil
-	results  *Tuple      // (outgoing) results from left to right; or nil
-	variadic bool        // true if the last parameter's type is of the form ...T (or string, for append built-in only)
-}
-
-// NewSignature returns a new function type for the given receiver, parameters,
-// and results, either of which may be nil. If variadic is set, the function
-// is variadic, it must have at least one parameter, and the last parameter
-// must be of unnamed slice type.
-func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
-	if variadic {
-		n := params.Len()
-		if n == 0 {
-			panic("types2.NewSignature: variadic function must have at least one parameter")
-		}
-		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
-			panic("types2.NewSignature: variadic parameter must be of unnamed slice type")
-		}
-	}
-	return &Signature{recv: recv, params: params, results: results, variadic: variadic}
-}
-
-// Recv returns the receiver of signature s (if a method), or nil if a
-// function. It is ignored when comparing signatures for identity.
-//
-// For an abstract method, Recv returns the enclosing interface either
-// as a *Named or an *Interface. Due to embedding, an interface may
-// contain methods whose receiver type is a different interface.
-func (s *Signature) Recv() *Var { return s.recv }
-
-// TParams returns the type parameters of signature s, or nil.
-func (s *Signature) TParams() []*TypeName { return s.tparams }
-
-// RParams returns the receiver type params of signature s, or nil.
-func (s *Signature) RParams() []*TypeName { return s.rparams }
-
-// SetTParams sets the type parameters of signature s.
-func (s *Signature) SetTParams(tparams []*TypeName) { s.tparams = tparams }
-
-// Params returns the parameters of signature s, or nil.
-func (s *Signature) Params() *Tuple { return s.params }
-
-// Results returns the results of signature s, or nil.
-func (s *Signature) Results() *Tuple { return s.results }
-
-// Variadic reports whether the signature s is variadic.
-func (s *Signature) Variadic() bool { return s.variadic }
-
-// A Sum represents a set of possible types.
-// Sums are currently used to represent type lists of interfaces
-// and thus the underlying types of type parameters; they are not
-// first class types of Go.
-type Sum struct {
-	types []Type // types are unique
-}
-
-// NewSum returns a new Sum type consisting of the provided
-// types if there are more than one. If there is exactly one
-// type, it returns that type. If the list of types is empty
-// the result is nil.
-func NewSum(types []Type) Type {
-	if len(types) == 0 {
-		return nil
-	}
-
-	// What should happen if types contains a sum type?
-	// Do we flatten the types list? For now we check
-	// and panic. This should not be possible for the
-	// current use case of type lists.
-	// TODO(gri) Come up with the rules for sum types.
-	for _, t := range types {
-		if _, ok := t.(*Sum); ok {
-			panic("sum type contains sum type - unimplemented")
-		}
-	}
-
-	if len(types) == 1 {
-		return types[0]
-	}
-	return &Sum{types: types}
-}
-
-// is reports whether all types in t satisfy pred.
-func (s *Sum) is(pred func(Type) bool) bool {
-	if s == nil {
-		return false
-	}
-	for _, t := range s.types {
-		if !pred(t) {
-			return false
-		}
-	}
-	return true
-}
-
-// An Interface represents an interface type.
-type Interface struct {
-	methods   []*Func // ordered list of explicitly declared methods
-	types     Type    // (possibly a Sum) type declared with a type list (TODO(gri) need better field name)
-	embeddeds []Type  // ordered list of explicitly embedded types
-
-	allMethods []*Func // ordered list of methods declared with or embedded in this interface (TODO(gri): replace with mset)
-	allTypes   Type    // intersection of all embedded and locally declared types  (TODO(gri) need better field name)
-
-	obj Object // type declaration defining this interface; or nil (for better error messages)
-}
-
-// unpack unpacks a type into a list of types.
-// TODO(gri) Try to eliminate the need for this function.
-func unpack(typ Type) []Type {
-	if typ == nil {
-		return nil
-	}
-	if sum := asSum(typ); sum != nil {
-		return sum.types
-	}
-	return []Type{typ}
-}
-
-// is reports whether interface t represents types that all satisfy pred.
-func (t *Interface) is(pred func(Type) bool) bool {
-	if t.allTypes == nil {
-		return false // we must have at least one type! (was bug)
-	}
-	for _, t := range unpack(t.allTypes) {
-		if !pred(t) {
-			return false
-		}
-	}
-	return true
-}
-
-// emptyInterface represents the empty (completed) interface
-var emptyInterface = Interface{allMethods: markComplete}
-
-// markComplete is used to mark an empty interface as completely
-// set up by setting the allMethods field to a non-nil empty slice.
-var markComplete = make([]*Func, 0)
-
-// NewInterface returns a new (incomplete) interface for the given methods and embedded types.
-// Each embedded type must have an underlying type of interface type.
-// NewInterface takes ownership of the provided methods and may modify their types by setting
-// missing receivers. To compute the method set of the interface, Complete must be called.
-//
-// Deprecated: Use NewInterfaceType instead which allows any (even non-defined) interface types
-// to be embedded. This is necessary for interfaces that embed alias type names referring to
-// non-defined (literal) interface types.
-func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
-	tnames := make([]Type, len(embeddeds))
-	for i, t := range embeddeds {
-		tnames[i] = t
-	}
-	return NewInterfaceType(methods, tnames)
-}
-
-// NewInterfaceType returns a new (incomplete) interface for the given methods and embedded types.
-// Each embedded type must have an underlying type of interface type (this property is not
-// verified for defined types, which may be in the process of being set up and which don't
-// have a valid underlying type yet).
-// NewInterfaceType takes ownership of the provided methods and may modify their types by setting
-// missing receivers. To compute the method set of the interface, Complete must be called.
-func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
-	if len(methods) == 0 && len(embeddeds) == 0 {
-		return &emptyInterface
-	}
-
-	// set method receivers if necessary
-	typ := new(Interface)
-	for _, m := range methods {
-		if sig := m.typ.(*Signature); sig.recv == nil {
-			sig.recv = NewVar(m.pos, m.pkg, "", typ)
-		}
-	}
-
-	// All embedded types should be interfaces; however, defined types
-	// may not yet be fully resolved. Only verify that non-defined types
-	// are interfaces. This matches the behavior of the code before the
-	// fix for #25301 (issue #25596).
-	for _, t := range embeddeds {
-		if _, ok := t.(*Named); !ok && !IsInterface(t) {
-			panic("embedded type is not an interface")
-		}
-	}
-
-	// sort for API stability
-	sortMethods(methods)
-	sortTypes(embeddeds)
-
-	typ.methods = methods
-	typ.embeddeds = embeddeds
-	return typ
-}
-
-// NumExplicitMethods returns the number of explicitly declared methods of interface t.
-func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
-
-// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
-// The methods are ordered by their unique Id.
-func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
-
-// NumEmbeddeds returns the number of embedded types in interface t.
-func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
-
-// Embedded returns the i'th embedded defined (*Named) type of interface t for 0 <= i < t.NumEmbeddeds().
-// The result is nil if the i'th embedded type is not a defined type.
-//
-// Deprecated: Use EmbeddedType which is not restricted to defined (*Named) types.
-func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named); return tname }
-
-// EmbeddedType returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
-func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
-
-// NumMethods returns the total number of methods of interface t.
-// The interface must have been completed.
-func (t *Interface) NumMethods() int { t.assertCompleteness(); return len(t.allMethods) }
-
-func (t *Interface) assertCompleteness() {
-	if t.allMethods == nil {
-		panic("interface is incomplete")
-	}
-}
-
-// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
-// The methods are ordered by their unique Id.
-// The interface must have been completed.
-func (t *Interface) Method(i int) *Func { t.assertCompleteness(); return t.allMethods[i] }
-
-// Empty reports whether t is the empty interface.
-func (t *Interface) Empty() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		// A non-nil allTypes may still be empty and represents the bottom type.
-		return len(t.allMethods) == 0 && t.allTypes == nil
-	}
-	return !t.iterate(func(t *Interface) bool {
-		return len(t.methods) > 0 || t.types != nil
-	}, nil)
-}
-
-// HasTypeList reports whether interface t has a type list, possibly from an embedded type.
-func (t *Interface) HasTypeList() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		return t.allTypes != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		return t.types != nil
-	}, nil)
-}
-
-// IsComparable reports whether interface t is or embeds the predeclared interface "comparable".
-func (t *Interface) IsComparable() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		_, m := lookupMethod(t.allMethods, nil, "==")
-		return m != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		_, m := lookupMethod(t.methods, nil, "==")
-		return m != nil
-	}, nil)
-}
-
-// IsConstraint reports t.HasTypeList() || t.IsComparable().
-func (t *Interface) IsConstraint() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		if t.allTypes != nil {
-			return true
-		}
-		_, m := lookupMethod(t.allMethods, nil, "==")
-		return m != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		if t.types != nil {
-			return true
-		}
-		_, m := lookupMethod(t.methods, nil, "==")
-		return m != nil
-	}, nil)
-}
-
-// iterate calls f with t and then with any embedded interface of t, recursively, until f returns true.
-// iterate reports whether any call to f returned true.
-func (t *Interface) iterate(f func(*Interface) bool, seen map[*Interface]bool) bool {
-	if f(t) {
-		return true
-	}
-	for _, e := range t.embeddeds {
-		// e should be an interface but be careful (it may be invalid)
-		if e := asInterface(e); e != nil {
-			// Cyclic interfaces such as "type E interface { E }" are not permitted
-			// but they are still constructed and we need to detect such cycles.
-			if seen[e] {
-				continue
-			}
-			if seen == nil {
-				seen = make(map[*Interface]bool)
-			}
-			seen[e] = true
-			if e.iterate(f, seen) {
-				return true
-			}
-		}
-	}
-	return false
-}
-
-// isSatisfiedBy reports whether interface t's type list is satisfied by the type typ.
-// If the type list is empty (absent), typ trivially satisfies the interface.
-// TODO(gri) This is not a great name. Eventually, we should have a more comprehensive
-//           "implements" predicate.
-func (t *Interface) isSatisfiedBy(typ Type) bool {
-	t.Complete()
-	if t.allTypes == nil {
-		return true
-	}
-	types := unpack(t.allTypes)
-	return includes(types, typ) || includes(types, under(typ))
-}
-
-// Complete computes the interface's method set. It must be called by users of
-// NewInterfaceType and NewInterface after the interface's embedded types are
-// fully defined and before using the interface type in any way other than to
-// form other types. The interface must not contain duplicate methods or a
-// panic occurs. Complete returns the receiver.
-func (t *Interface) Complete() *Interface {
-	// TODO(gri) consolidate this method with Checker.completeInterface
-	if t.allMethods != nil {
-		return t
-	}
-
-	t.allMethods = markComplete // avoid infinite recursion
-
-	var todo []*Func
-	var methods []*Func
-	var seen objset
-	addMethod := func(m *Func, explicit bool) {
-		switch other := seen.insert(m); {
-		case other == nil:
-			methods = append(methods, m)
-		case explicit:
-			panic("duplicate method " + m.name)
-		default:
-			// check method signatures after all locally embedded interfaces are computed
-			todo = append(todo, m, other.(*Func))
-		}
-	}
-
-	for _, m := range t.methods {
-		addMethod(m, true)
-	}
-
-	allTypes := t.types
-
-	for _, typ := range t.embeddeds {
-		utyp := under(typ)
-		etyp := asInterface(utyp)
-		if etyp == nil {
-			if utyp != Typ[Invalid] {
-				panic(fmt.Sprintf("%s is not an interface", typ))
-			}
-			continue
-		}
-		etyp.Complete()
-		for _, m := range etyp.allMethods {
-			addMethod(m, false)
-		}
-		allTypes = intersect(allTypes, etyp.allTypes)
-	}
-
-	for i := 0; i < len(todo); i += 2 {
-		m := todo[i]
-		other := todo[i+1]
-		if !Identical(m.typ, other.typ) {
-			panic("duplicate method " + m.name)
-		}
-	}
-
-	if methods != nil {
-		sortMethods(methods)
-		t.allMethods = methods
-	}
-	t.allTypes = allTypes
-
-	return t
-}
-
-// A Map represents a map type.
-type Map struct {
-	key, elem Type
-}
-
-// NewMap returns a new map for the given key and element types.
-func NewMap(key, elem Type) *Map {
-	return &Map{key: key, elem: elem}
-}
-
-// Key returns the key type of map m.
-func (m *Map) Key() Type { return m.key }
-
-// Elem returns the element type of map m.
-func (m *Map) Elem() Type { return m.elem }
-
-// A Chan represents a channel type.
-type Chan struct {
-	dir  ChanDir
-	elem Type
-}
-
-// A ChanDir value indicates a channel direction.
-type ChanDir int
-
-// The direction of a channel is indicated by one of these constants.
-const (
-	SendRecv ChanDir = iota
-	SendOnly
-	RecvOnly
-)
-
-// NewChan returns a new channel type for the given direction and element type.
-func NewChan(dir ChanDir, elem Type) *Chan {
-	return &Chan{dir: dir, elem: elem}
-}
-
-// Dir returns the direction of channel c.
-func (c *Chan) Dir() ChanDir { return c.dir }
-
-// Elem returns the element type of channel c.
-func (c *Chan) Elem() Type { return c.elem }
-
-// TODO(gri) Clean up Named struct below; specifically the fromRHS field (can we use underlying?).
-
-// A Named represents a named (defined) type.
-type Named struct {
-	check      *Checker    // for Named.under implementation
-	info       typeInfo    // for cycle detection
-	obj        *TypeName   // corresponding declared object
-	orig       *Named      // original, uninstantiated type
-	fromRHS    Type        // type (on RHS of declaration) this *Named type is derived from (for cycle reporting)
-	underlying Type        // possibly a *Named during setup; never a *Named once set up completely
-	tparams    []*TypeName // type parameters, or nil
-	targs      []Type      // type arguments (after instantiation), or nil
-	methods    []*Func     // methods declared for this type (not the method set of this type); signatures are type-checked lazily
-}
-
-// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
-// If the given type name obj doesn't have a type yet, its type is set to the returned named type.
-// The underlying type must not be a *Named.
-func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
-	if _, ok := underlying.(*Named); ok {
-		panic("types2.NewNamed: underlying type must not be *Named")
-	}
-	return (*Checker)(nil).newNamed(obj, nil, underlying, nil, methods)
-}
-
-// newNamed is like NewNamed but with a *Checker receiver and additional orig argument.
-func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams []*TypeName, methods []*Func) *Named {
-	typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods}
-	if typ.orig == nil {
-		typ.orig = typ
-	}
-	if obj.typ == nil {
-		obj.typ = typ
-	}
-	return typ
-}
-
-// Obj returns the type name for the named type t.
-func (t *Named) Obj() *TypeName { return t.obj }
-
-// Orig returns the original generic type an instantiated type is derived from.
-// If t is not an instantiated type, the result is t.
-func (t *Named) Orig() *Named { return t.orig }
-
-// TODO(gri) Come up with a better representation and API to distinguish
-//           between parameterized instantiated and non-instantiated types.
-
-// TParams returns the type parameters of the named type t, or nil.
-// The result is non-nil for an (originally) parameterized type even if it is instantiated.
-func (t *Named) TParams() []*TypeName { return t.tparams }
-
-// SetTParams sets the type parameters of the named type t.
-func (t *Named) SetTParams(tparams []*TypeName) { t.tparams = tparams }
-
-// TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated.
-func (t *Named) TArgs() []Type { return t.targs }
-
-// SetTArgs sets the type arguments of the named type t.
-func (t *Named) SetTArgs(args []Type) { t.targs = args }
-
-// NumMethods returns the number of explicit methods whose receiver is named type t.
-func (t *Named) NumMethods() int { return len(t.methods) }
-
-// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
-func (t *Named) Method(i int) *Func { return t.methods[i] }
-
-// SetUnderlying sets the underlying type and marks t as complete.
-func (t *Named) SetUnderlying(underlying Type) {
-	if underlying == nil {
-		panic("types2.Named.SetUnderlying: underlying type must not be nil")
-	}
-	if _, ok := underlying.(*Named); ok {
-		panic("types2.Named.SetUnderlying: underlying type must not be *Named")
-	}
-	t.underlying = underlying
-}
-
-// AddMethod adds method m unless it is already in the method list.
-func (t *Named) AddMethod(m *Func) {
-	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
-		t.methods = append(t.methods, m)
-	}
-}
-
-// Note: This is a uint32 rather than a uint64 because the
-// respective 64 bit atomic instructions are not available
-// on all platforms.
-var lastId uint32
-
-// nextId returns a value increasing monotonically by 1 with
-// each call, starting with 1. It may be called concurrently.
-func nextId() uint64 { return uint64(atomic.AddUint32(&lastId, 1)) }
-
-// A TypeParam represents a type parameter type.
-type TypeParam struct {
-	check *Checker  // for lazy type bound completion
-	id    uint64    // unique id, for debugging only
-	obj   *TypeName // corresponding type name
-	index int       // type parameter index in source order, starting at 0
-	bound Type      // *Named or *Interface; underlying type is always *Interface
-}
-
-// Obj returns the type name for the type parameter t.
-func (t *TypeParam) Obj() *TypeName { return t.obj }
-
-// NewTypeParam returns a new TypeParam.
-func (check *Checker) NewTypeParam(obj *TypeName, index int, bound Type) *TypeParam {
-	assert(bound != nil)
-	typ := &TypeParam{check: check, id: nextId(), obj: obj, index: index, bound: bound}
-	if obj.typ == nil {
-		obj.typ = typ
-	}
-	return typ
-}
-
-func (t *TypeParam) Bound() *Interface {
-	iface := asInterface(t.bound)
-	// use the type bound position if we have one
-	pos := nopos
-	if n, _ := t.bound.(*Named); n != nil {
-		pos = n.obj.pos
-	}
-	// TODO(gri) switch this to an unexported method on Checker.
-	t.check.completeInterface(pos, iface)
-	return iface
-}
-
-// optype returns a type's operational type. Except for
-// type parameters, the operational type is the same
-// as the underlying type (as returned by under). For
-// Type parameters, the operational type is determined
-// by the corresponding type bound's type list. The
-// result may be the bottom or top type, but it is never
-// the incoming type parameter.
-func optype(typ Type) Type {
-	if t := asTypeParam(typ); t != nil {
-		// If the optype is typ, return the top type as we have
-		// no information. It also prevents infinite recursion
-		// via the asTypeParam converter function. This can happen
-		// for a type parameter list of the form:
-		// (type T interface { type T }).
-		// See also issue #39680.
-		if u := t.Bound().allTypes; u != nil && u != typ {
-			// u != typ and u is a type parameter => under(u) != typ, so this is ok
-			return under(u)
-		}
-		return theTop
-	}
-	return under(typ)
-}
-
-// An instance represents an instantiated generic type syntactically
-// (without expanding the instantiation). Type instances appear only
-// during type-checking and are replaced by their fully instantiated
-// (expanded) types before the end of type-checking.
-type instance struct {
-	check   *Checker     // for lazy instantiation
-	pos     syntax.Pos   // position of type instantiation; for error reporting only
-	base    *Named       // parameterized type to be instantiated
-	targs   []Type       // type arguments
-	poslist []syntax.Pos // position of each targ; for error reporting only
-	value   Type         // base(targs...) after instantiation or Typ[Invalid]; nil if not yet set
-}
-
-// expand returns the instantiated (= expanded) type of t.
-// The result is either an instantiated *Named type, or
-// Typ[Invalid] if there was an error.
-func (t *instance) expand() Type {
-	v := t.value
-	if v == nil {
-		v = t.check.instantiate(t.pos, t.base, t.targs, t.poslist)
-		if v == nil {
-			v = Typ[Invalid]
-		}
-		t.value = v
-	}
-	// After instantiation we must have an invalid or a *Named type.
-	if debug && v != Typ[Invalid] {
-		_ = v.(*Named)
-	}
-	return v
-}
-
-// expand expands a type instance into its instantiated
-// type and leaves all other types alone. expand does
-// not recurse.
-func expand(typ Type) Type {
-	if t, _ := typ.(*instance); t != nil {
-		return t.expand()
-	}
-	return typ
-}
-
-// expandf is set to expand.
-// Call expandf when calling expand causes compile-time cycle error.
-var expandf func(Type) Type
-
-func init() { expandf = expand }
-
-// bottom represents the bottom of the type lattice.
-// It is the underlying type of a type parameter that
-// cannot be satisfied by any type, usually because
-// the intersection of type constraints left nothing).
-type bottom struct{}
-
-// theBottom is the singleton bottom type.
-var theBottom = &bottom{}
-
 // top represents the top of the type lattice.
 // It is the underlying type of a type parameter that
 // can be satisfied by any type (ignoring methods),
-// usually because the type constraint has no type
-// list.
+// because its type constraint contains no restrictions
+// besides methods.
 type top struct{}
 
 // theTop is the singleton top type.
 var theTop = &top{}
 
-// Type-specific implementations of Underlying.
-func (t *Basic) Underlying() Type     { return t }
-func (t *Array) Underlying() Type     { return t }
-func (t *Slice) Underlying() Type     { return t }
-func (t *Struct) Underlying() Type    { return t }
-func (t *Pointer) Underlying() Type   { return t }
-func (t *Tuple) Underlying() Type     { return t }
-func (t *Signature) Underlying() Type { return t }
-func (t *Sum) Underlying() Type       { return t }
-func (t *Interface) Underlying() Type { return t }
-func (t *Map) Underlying() Type       { return t }
-func (t *Chan) Underlying() Type      { return t }
-func (t *Named) Underlying() Type     { return t.underlying }
-func (t *TypeParam) Underlying() Type { return t }
-func (t *instance) Underlying() Type  { return t }
-func (t *bottom) Underlying() Type    { return t }
-func (t *top) Underlying() Type       { return t }
-
-// Type-specific implementations of String.
-func (t *Basic) String() string     { return TypeString(t, nil) }
-func (t *Array) String() string     { return TypeString(t, nil) }
-func (t *Slice) String() string     { return TypeString(t, nil) }
-func (t *Struct) String() string    { return TypeString(t, nil) }
-func (t *Pointer) String() string   { return TypeString(t, nil) }
-func (t *Tuple) String() string     { return TypeString(t, nil) }
-func (t *Signature) String() string { return TypeString(t, nil) }
-func (t *Sum) String() string       { return TypeString(t, nil) }
-func (t *Interface) String() string { return TypeString(t, nil) }
-func (t *Map) String() string       { return TypeString(t, nil) }
-func (t *Chan) String() string      { return TypeString(t, nil) }
-func (t *Named) String() string     { return TypeString(t, nil) }
-func (t *TypeParam) String() string { return TypeString(t, nil) }
-func (t *instance) String() string  { return TypeString(t, nil) }
-func (t *bottom) String() string    { return TypeString(t, nil) }
-func (t *top) String() string       { return TypeString(t, nil) }
+func (t *top) Underlying() Type { return t }
+func (t *top) String() string   { return TypeString(t, nil) }
 
 // under returns the true expanded underlying type.
 // If it doesn't exist, the result is Typ[Invalid].
 // under must only be called when a type is known
 // to be fully set up.
 func under(t Type) Type {
-	// TODO(gri) is this correct for *Sum?
+	// TODO(gri) is this correct for *Union?
 	if n := asNamed(t); n != nil {
 		return n.under()
 	}
 	return t
 }
 
+// optype returns a type's operational type. Except for
+// type parameters, the operational type is the same
+// as the underlying type (as returned by under). For
+// Type parameters, the operational type is the structural
+// type, if any; otherwise it's the top type.
+// The result is never the incoming type parameter.
+func optype(typ Type) Type {
+	if t := asTypeParam(typ); t != nil {
+		// TODO(gri) review accuracy of this comment
+		// If the optype is typ, return the top type as we have
+		// no information. It also prevents infinite recursion
+		// via the asTypeParam converter function. This can happen
+		// for a type parameter list of the form:
+		// (type T interface { type T }).
+		// See also issue #39680.
+		if u := t.structuralType(); u != nil {
+			assert(u != typ) // "naked" type parameters cannot be embedded
+			return u
+		}
+		return theTop
+	}
+	return under(typ)
+}
+
 // Converters
 //
 // A converter must only be called when a type is
@@ -944,39 +98,26 @@
 	return op
 }
 
-// asTuple is not needed - not provided
-
 func asSignature(t Type) *Signature {
 	op, _ := optype(t).(*Signature)
 	return op
 }
 
-func asSum(t Type) *Sum {
-	op, _ := optype(t).(*Sum)
-	return op
-}
-
-func asInterface(t Type) *Interface {
-	op, _ := optype(t).(*Interface)
-	return op
-}
-
-func asMap(t Type) *Map {
-	op, _ := optype(t).(*Map)
-	return op
-}
-
-func asChan(t Type) *Chan {
-	op, _ := optype(t).(*Chan)
-	return op
-}
-
-// If the argument to asNamed and asTypeParam is of the respective types
+// If the argument to asInterface, asNamed, or asTypeParam is of the respective type
 // (possibly after expanding an instance type), these methods return that type.
 // Otherwise the result is nil.
 
+// asInterface does not need to look at optype (type sets don't contain interfaces)
+func asInterface(t Type) *Interface {
+	u, _ := under(t).(*Interface)
+	return u
+}
+
 func asNamed(t Type) *Named {
-	e, _ := expand(t).(*Named)
+	e, _ := t.(*Named)
+	if e != nil {
+		e.expand()
+	}
 	return e
 }
 
@@ -991,3 +132,4 @@
 func AsNamed(t Type) *Named         { return asNamed(t) }
 func AsSignature(t Type) *Signature { return asSignature(t) }
 func AsInterface(t Type) *Interface { return asInterface(t) }
+func AsTypeParam(t Type) *TypeParam { return asTypeParam(t) }
diff --git a/src/cmd/compile/internal/types2/typeparam.go b/src/cmd/compile/internal/types2/typeparam.go
new file mode 100644
index 0000000..4b4282e
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeparam.go
@@ -0,0 +1,143 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "sync/atomic"
+
+// Note: This is a uint32 rather than a uint64 because the
+// respective 64 bit atomic instructions are not available
+// on all platforms.
+var lastID uint32
+
+// nextID returns a value increasing monotonically by 1 with
+// each call, starting with 1. It may be called concurrently.
+func nextID() uint64 { return uint64(atomic.AddUint32(&lastID, 1)) }
+
+// A TypeParam represents a type parameter type.
+type TypeParam struct {
+	check *Checker  // for lazy type bound completion
+	id    uint64    // unique id, for debugging only
+	obj   *TypeName // corresponding type name
+	index int       // type parameter index in source order, starting at 0
+	// TODO(rfindley): this could also be Typ[Invalid]. Verify that this is handled correctly.
+	bound Type // *Named or *Interface; underlying type is always *Interface
+}
+
+// Obj returns the type name for the type parameter t.
+func (t *TypeParam) Obj() *TypeName { return t.obj }
+
+// NewTypeParam returns a new TypeParam. Type parameters may be set on a Named
+// or Signature type by calling SetTParams. Setting a type parameter on more
+// than one type will result in a panic.
+//
+// The bound argument can be nil, and set later via SetBound.
+func (check *Checker) NewTypeParam(obj *TypeName, bound Type) *TypeParam {
+	// Always increment lastID, even if it is not used.
+	id := nextID()
+	if check != nil {
+		check.nextID++
+		id = check.nextID
+	}
+	typ := &TypeParam{check: check, id: id, obj: obj, index: -1, bound: bound}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	return typ
+}
+
+// Index returns the index of the type param within its param list.
+func (t *TypeParam) Index() int {
+	return t.index
+}
+
+// SetId sets the unique id of a type param. Should only be used for type params
+// in imported generic types.
+func (t *TypeParam) SetId(id uint64) {
+	t.id = id
+}
+
+// Constraint returns the type constraint specified for t.
+func (t *TypeParam) Constraint() Type {
+	// compute the type set if possible (we may not have an interface)
+	if iface, _ := under(t.bound).(*Interface); iface != nil {
+		// use the type bound position if we have one
+		pos := nopos
+		if n, _ := t.bound.(*Named); n != nil {
+			pos = n.obj.pos
+		}
+		computeInterfaceTypeSet(t.check, pos, iface)
+	}
+	return t.bound
+}
+
+// SetConstraint sets the type constraint for t.
+func (t *TypeParam) SetConstraint(bound Type) {
+	if bound == nil {
+		panic("nil constraint")
+	}
+	t.bound = bound
+}
+
+func (t *TypeParam) Underlying() Type { return t }
+func (t *TypeParam) String() string   { return TypeString(t, nil) }
+
+// TypeParams holds a list of type parameters bound to a type.
+type TypeParams struct{ tparams []*TypeName }
+
+// Len returns the number of type parameters in the list.
+// It is safe to call on a nil receiver.
+func (tps *TypeParams) Len() int {
+	return len(tps.list())
+}
+
+// At returns the i'th type parameter in the list.
+func (tps *TypeParams) At(i int) *TypeName {
+	return tps.list()[i]
+}
+
+func (tps *TypeParams) list() []*TypeName {
+	if tps == nil {
+		return nil
+	}
+	return tps.tparams
+}
+
+func bindTParams(list []*TypeName) *TypeParams {
+	if len(list) == 0 {
+		return nil
+	}
+	for i, tp := range list {
+		typ := tp.Type().(*TypeParam)
+		if typ.index >= 0 {
+			panic("type parameter bound more than once")
+		}
+		typ.index = i
+	}
+	return &TypeParams{tparams: list}
+}
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// iface returns the constraint interface of t.
+func (t *TypeParam) iface() *Interface {
+	if iface, _ := under(t.Constraint()).(*Interface); iface != nil {
+		return iface
+	}
+	return &emptyInterface
+}
+
+// structuralType returns the structural type of the type parameter's constraint; or nil.
+func (t *TypeParam) structuralType() Type {
+	return t.iface().typeSet().structuralType()
+}
+
+func (t *TypeParam) is(f func(*term) bool) bool {
+	return t.iface().typeSet().is(f)
+}
+
+func (t *TypeParam) underIs(f func(Type) bool) bool {
+	return t.iface().typeSet().underIs(f)
+}
diff --git a/src/cmd/compile/internal/types2/types_test.go b/src/cmd/compile/internal/types2/types_test.go
index 0964021..1525844 100644
--- a/src/cmd/compile/internal/types2/types_test.go
+++ b/src/cmd/compile/internal/types2/types_test.go
@@ -4,14 +4,9 @@
 
 package types2
 
-import "sync/atomic"
-
 func init() {
 	acceptMethodTypeParams = true
 }
 
-// Upon calling ResetId, nextId starts with 1 again.
-// It may be called concurrently. This is only needed
-// for tests where we may want to have a consistent
-// numbering for each individual test case.
-func ResetId() { atomic.StoreUint32(&lastId, 0) }
+// Debug is set if types2 is built with debug mode enabled.
+const Debug = debug
diff --git a/src/cmd/compile/internal/types2/typeset.go b/src/cmd/compile/internal/types2/typeset.go
new file mode 100644
index 0000000..5955bbe
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeset.go
@@ -0,0 +1,392 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"bytes"
+	"cmd/compile/internal/syntax"
+	"fmt"
+	"sort"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A TypeSet represents the type set of an interface.
+type TypeSet struct {
+	comparable bool // if set, the interface is or embeds comparable
+	// TODO(gri) consider using a set for the methods for faster lookup
+	methods []*Func  // all methods of the interface; sorted by unique ID
+	terms   termlist // type terms of the type set
+}
+
+// IsEmpty reports whether type set s is the empty set.
+func (s *TypeSet) IsEmpty() bool { return s.terms.isEmpty() }
+
+// IsAll reports whether type set s is the set of all types (corresponding to the empty interface).
+func (s *TypeSet) IsAll() bool {
+	return !s.comparable && len(s.methods) == 0 && s.terms.isAll()
+}
+
+// TODO(gri) IsMethodSet is not a great name for this predicate. Find a better one.
+
+// IsMethodSet reports whether the type set s is described by a single set of methods.
+func (s *TypeSet) IsMethodSet() bool { return !s.comparable && s.terms.isAll() }
+
+// IsComparable reports whether each type in the set is comparable.
+func (s *TypeSet) IsComparable() bool {
+	if s.terms.isAll() {
+		return s.comparable
+	}
+	return s.is(func(t *term) bool {
+		return Comparable(t.typ)
+	})
+}
+
+// TODO(gri) IsTypeSet is not a great name for this predicate. Find a better one.
+
+// IsTypeSet reports whether the type set s is represented by a finite set of underlying types.
+func (s *TypeSet) IsTypeSet() bool {
+	return !s.comparable && len(s.methods) == 0
+}
+
+// NumMethods returns the number of methods available.
+func (s *TypeSet) NumMethods() int { return len(s.methods) }
+
+// Method returns the i'th method of type set s for 0 <= i < s.NumMethods().
+// The methods are ordered by their unique ID.
+func (s *TypeSet) Method(i int) *Func { return s.methods[i] }
+
+// LookupMethod returns the index of and method with matching package and name, or (-1, nil).
+func (s *TypeSet) LookupMethod(pkg *Package, name string) (int, *Func) {
+	// TODO(gri) s.methods is sorted - consider binary search
+	return lookupMethod(s.methods, pkg, name)
+}
+
+func (s *TypeSet) String() string {
+	switch {
+	case s.IsEmpty():
+		return "∅"
+	case s.IsAll():
+		return "𝓤"
+	}
+
+	hasMethods := len(s.methods) > 0
+	hasTerms := s.hasTerms()
+
+	var buf bytes.Buffer
+	buf.WriteByte('{')
+	if s.comparable {
+		buf.WriteString(" comparable")
+		if hasMethods || hasTerms {
+			buf.WriteByte(';')
+		}
+	}
+	for i, m := range s.methods {
+		if i > 0 {
+			buf.WriteByte(';')
+		}
+		buf.WriteByte(' ')
+		buf.WriteString(m.String())
+	}
+	if hasMethods && hasTerms {
+		buf.WriteByte(';')
+	}
+	if hasTerms {
+		buf.WriteString(s.terms.String())
+	}
+	buf.WriteString(" }") // there was at least one method or term
+
+	return buf.String()
+}
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (s *TypeSet) hasTerms() bool             { return !s.terms.isAll() }
+func (s *TypeSet) structuralType() Type       { return s.terms.structuralType() }
+func (s *TypeSet) includes(t Type) bool       { return s.terms.includes(t) }
+func (s1 *TypeSet) subsetOf(s2 *TypeSet) bool { return s1.terms.subsetOf(s2.terms) }
+
+// TODO(gri) TypeSet.is and TypeSet.underIs should probably also go into termlist.go
+
+var topTerm = term{false, theTop}
+
+func (s *TypeSet) is(f func(*term) bool) bool {
+	if len(s.terms) == 0 {
+		return false
+	}
+	for _, t := range s.terms {
+		// Terms represent the top term with a nil type.
+		// The rest of the type checker uses the top type
+		// instead. Convert.
+		// TODO(gri) investigate if we can do without this
+		if t.typ == nil {
+			t = &topTerm
+		}
+		if !f(t) {
+			return false
+		}
+	}
+	return true
+}
+
+func (s *TypeSet) underIs(f func(Type) bool) bool {
+	if len(s.terms) == 0 {
+		return false
+	}
+	for _, t := range s.terms {
+		// see corresponding comment in TypeSet.is
+		u := t.typ
+		if u == nil {
+			u = theTop
+		}
+		// t == under(t) for ~t terms
+		if !t.tilde {
+			u = under(u)
+		}
+		if debug {
+			assert(Identical(u, under(u)))
+		}
+		if !f(u) {
+			return false
+		}
+	}
+	return true
+}
+
+// topTypeSet may be used as type set for the empty interface.
+var topTypeSet = TypeSet{terms: allTermlist}
+
+// computeInterfaceTypeSet may be called with check == nil.
+func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *TypeSet {
+	if ityp.tset != nil {
+		return ityp.tset
+	}
+
+	// If the interface is not fully set up yet, the type set will
+	// not be complete, which may lead to errors when using the the
+	// type set (e.g. missing method). Don't compute a partial type
+	// set (and don't store it!), so that we still compute the full
+	// type set eventually. Instead, return the top type set and
+	// let any follow-on errors play out.
+	if !ityp.complete {
+		return &topTypeSet
+	}
+
+	if check != nil && check.conf.Trace {
+		// Types don't generally have position information.
+		// If we don't have a valid pos provided, try to use
+		// one close enough.
+		if !pos.IsKnown() && len(ityp.methods) > 0 {
+			pos = ityp.methods[0].pos
+		}
+
+		check.trace(pos, "type set for %s", ityp)
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(pos, "=> %s ", ityp.typeSet())
+		}()
+	}
+
+	// An infinitely expanding interface (due to a cycle) is detected
+	// elsewhere (Checker.validType), so here we simply assume we only
+	// have valid interfaces. Mark the interface as complete to avoid
+	// infinite recursion if the validType check occurs later for some
+	// reason.
+	ityp.tset = &TypeSet{terms: allTermlist} // TODO(gri) is this sufficient?
+
+	// Methods of embedded interfaces are collected unchanged; i.e., the identity
+	// of a method I.m's Func Object of an interface I is the same as that of
+	// the method m in an interface that embeds interface I. On the other hand,
+	// if a method is embedded via multiple overlapping embedded interfaces, we
+	// don't provide a guarantee which "original m" got chosen for the embedding
+	// interface. See also issue #34421.
+	//
+	// If we don't care to provide this identity guarantee anymore, instead of
+	// reusing the original method in embeddings, we can clone the method's Func
+	// Object and give it the position of a corresponding embedded interface. Then
+	// we can get rid of the mpos map below and simply use the cloned method's
+	// position.
+
+	var todo []*Func
+	var seen objset
+	var methods []*Func
+	mpos := make(map[*Func]syntax.Pos) // method specification or method embedding position, for good error messages
+	addMethod := func(pos syntax.Pos, m *Func, explicit bool) {
+		switch other := seen.insert(m); {
+		case other == nil:
+			methods = append(methods, m)
+			mpos[m] = pos
+		case explicit:
+			if check == nil {
+				panic(fmt.Sprintf("%s: duplicate method %s", m.pos, m.name))
+			}
+			// check != nil
+			var err error_
+			err.errorf(pos, "duplicate method %s", m.name)
+			err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
+			check.report(&err)
+		default:
+			// We have a duplicate method name in an embedded (not explicitly declared) method.
+			// Check method signatures after all types are computed (issue #33656).
+			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
+			// error here as well (even though we could do it eagerly) because it's the same
+			// error message.
+			if check == nil {
+				// check method signatures after all locally embedded interfaces are computed
+				todo = append(todo, m, other.(*Func))
+				break
+			}
+			// check != nil
+			check.later(func() {
+				if !check.allowVersion(m.pkg, 1, 14) || !Identical(m.typ, other.Type()) {
+					var err error_
+					err.errorf(pos, "duplicate method %s", m.name)
+					err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
+					check.report(&err)
+				}
+			})
+		}
+	}
+
+	for _, m := range ityp.methods {
+		addMethod(m.pos, m, true)
+	}
+
+	// collect embedded elements
+	var allTerms = allTermlist
+	for i, typ := range ityp.embeddeds {
+		// The embedding position is nil for imported interfaces
+		// and also for interface copies after substitution (but
+		// in that case we don't need to report errors again).
+		var pos syntax.Pos // embedding position
+		if ityp.embedPos != nil {
+			pos = (*ityp.embedPos)[i]
+		}
+		var terms termlist
+		switch u := under(typ).(type) {
+		case *Interface:
+			tset := computeInterfaceTypeSet(check, pos, u)
+			if tset.comparable {
+				ityp.tset.comparable = true
+			}
+			for _, m := range tset.methods {
+				addMethod(pos, m, false) // use embedding position pos rather than m.pos
+			}
+			terms = tset.terms
+		case *Union:
+			tset := computeUnionTypeSet(check, pos, u)
+			if tset == &invalidTypeSet {
+				continue // ignore invalid unions
+			}
+			terms = tset.terms
+		case *TypeParam:
+			// Embedding stand-alone type parameters is not permitted.
+			// This case is handled during union parsing.
+			unreachable()
+		default:
+			if typ == Typ[Invalid] {
+				continue
+			}
+			if check != nil && !check.allowVersion(check.pkg, 1, 18) {
+				check.errorf(pos, "%s is not an interface", typ)
+				continue
+			}
+			terms = termlist{{false, typ}}
+		}
+		// The type set of an interface is the intersection
+		// of the type sets of all its elements.
+		// Intersection cannot produce longer termlists and
+		// thus cannot overflow.
+		allTerms = allTerms.intersect(terms)
+	}
+	ityp.embedPos = nil // not needed anymore (errors have been reported)
+
+	// process todo's (this only happens if check == nil)
+	for i := 0; i < len(todo); i += 2 {
+		m := todo[i]
+		other := todo[i+1]
+		if !Identical(m.typ, other.typ) {
+			panic(fmt.Sprintf("%s: duplicate method %s", m.pos, m.name))
+		}
+	}
+
+	if methods != nil {
+		sortMethods(methods)
+		ityp.tset.methods = methods
+	}
+	ityp.tset.terms = allTerms
+
+	return ityp.tset
+}
+
+func sortMethods(list []*Func) {
+	sort.Sort(byUniqueMethodName(list))
+}
+
+func assertSortedMethods(list []*Func) {
+	if !debug {
+		panic("assertSortedMethods called outside debug mode")
+	}
+	if !sort.IsSorted(byUniqueMethodName(list)) {
+		panic("methods not sorted")
+	}
+}
+
+// byUniqueMethodName method lists can be sorted by their unique method names.
+type byUniqueMethodName []*Func
+
+func (a byUniqueMethodName) Len() int           { return len(a) }
+func (a byUniqueMethodName) Less(i, j int) bool { return a[i].less(&a[j].object) }
+func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
+// invalidTypeSet is a singleton type set to signal an invalid type set
+// due to an error. It's also a valid empty type set, so consumers of
+// type sets may choose to ignore it.
+var invalidTypeSet TypeSet
+
+// computeUnionTypeSet may be called with check == nil.
+// The result is &invalidTypeSet if the union overflows.
+func computeUnionTypeSet(check *Checker, pos syntax.Pos, utyp *Union) *TypeSet {
+	if utyp.tset != nil {
+		return utyp.tset
+	}
+
+	// avoid infinite recursion (see also computeInterfaceTypeSet)
+	utyp.tset = new(TypeSet)
+
+	var allTerms termlist
+	for _, t := range utyp.terms {
+		var terms termlist
+		switch u := under(t.typ).(type) {
+		case *Interface:
+			terms = computeInterfaceTypeSet(check, pos, u).terms
+		case *TypeParam:
+			// A stand-alone type parameters is not permitted as union term.
+			// This case is handled during union parsing.
+			unreachable()
+		default:
+			if t.typ == Typ[Invalid] {
+				continue
+			}
+			terms = termlist{(*term)(t)}
+		}
+		// The type set of a union expression is the union
+		// of the type sets of each term.
+		allTerms = allTerms.union(terms)
+		if len(allTerms) > maxTermCount {
+			if check != nil {
+				check.errorf(pos, "cannot handle more than %d union terms (implementation limitation)", maxTermCount)
+			}
+			utyp.tset = &invalidTypeSet
+			return utyp.tset
+		}
+	}
+	utyp.tset.terms = allTerms
+
+	return utyp.tset
+}
diff --git a/src/cmd/compile/internal/types2/typeset_test.go b/src/cmd/compile/internal/types2/typeset_test.go
new file mode 100644
index 0000000..0e14d52
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeset_test.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "testing"
+
+func TestInvalidTypeSet(t *testing.T) {
+	if !invalidTypeSet.IsEmpty() {
+		t.Error("invalidTypeSet is not empty")
+	}
+}
+
+// TODO(gri) add more tests
diff --git a/src/cmd/compile/internal/types2/typestring.go b/src/cmd/compile/internal/types2/typestring.go
index 4001669..cb7cf73 100644
--- a/src/cmd/compile/internal/types2/typestring.go
+++ b/src/cmd/compile/internal/types2/typestring.go
@@ -39,27 +39,6 @@
 	}
 }
 
-// If gcCompatibilityMode is set, printing of types is modified
-// to match the representation of some types in the gc compiler:
-//
-//	- byte and rune lose their alias name and simply stand for
-//	  uint8 and int32 respectively
-//	- embedded interfaces get flattened (the embedding info is lost,
-//	  and certain recursive interface types cannot be printed anymore)
-//
-// This makes it easier to compare packages computed with the type-
-// checker vs packages imported from gc export data.
-//
-// Caution: This flag affects all uses of WriteType, globally.
-// It is only provided for testing in conjunction with
-// gc-generated data.
-//
-// This flag is exported in the x/tools/go/types package. We don't
-// need it at the moment in the std repo and so we don't export it
-// anymore. We should eventually try to remove it altogether.
-// TODO(gri) remove this
-var gcCompatibilityMode bool
-
 // TypeString returns the string representation of typ.
 // The Qualifier controls the printing of
 // package-level objects, and may be nil.
@@ -106,16 +85,6 @@
 				break
 			}
 		}
-
-		if gcCompatibilityMode {
-			// forget the alias names
-			switch t.kind {
-			case Byte:
-				t = Typ[Uint8]
-			case Rune:
-				t = Typ[Int32]
-			}
-		}
 		buf.WriteString(t.name)
 
 	case *Array:
@@ -157,80 +126,39 @@
 		buf.WriteString("func")
 		writeSignature(buf, t, qf, visited)
 
-	case *Sum:
-		for i, t := range t.types {
+	case *Union:
+		// Unions only appear as (syntactic) embedded elements
+		// in interfaces and syntactically cannot be empty.
+		if t.Len() == 0 {
+			panic("empty union")
+		}
+		for i, t := range t.terms {
 			if i > 0 {
-				buf.WriteString(", ")
+				buf.WriteByte('|')
 			}
-			writeType(buf, t, qf, visited)
+			if t.tilde {
+				buf.WriteByte('~')
+			}
+			writeType(buf, t.typ, qf, visited)
 		}
 
 	case *Interface:
-		// We write the source-level methods and embedded types rather
-		// than the actual method set since resolved method signatures
-		// may have non-printable cycles if parameters have embedded
-		// interface types that (directly or indirectly) embed the
-		// current interface. For instance, consider the result type
-		// of m:
-		//
-		//     type T interface{
-		//         m() interface{ T }
-		//     }
-		//
 		buf.WriteString("interface{")
-		empty := true
-		if gcCompatibilityMode {
-			// print flattened interface
-			// (useful to compare against gc-generated interfaces)
-			for i, m := range t.allMethods {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				buf.WriteString(m.name)
-				writeSignature(buf, m.typ.(*Signature), qf, visited)
-				empty = false
-			}
-			if !empty && t.allTypes != nil {
+		first := true
+		for _, m := range t.methods {
+			if !first {
 				buf.WriteString("; ")
 			}
-			if t.allTypes != nil {
-				buf.WriteString("type ")
-				writeType(buf, t.allTypes, qf, visited)
-			}
-		} else {
-			// print explicit interface methods and embedded types
-			for i, m := range t.methods {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				buf.WriteString(m.name)
-				writeSignature(buf, m.typ.(*Signature), qf, visited)
-				empty = false
-			}
-			if !empty && t.types != nil {
-				buf.WriteString("; ")
-			}
-			if t.types != nil {
-				buf.WriteString("type ")
-				writeType(buf, t.types, qf, visited)
-				empty = false
-			}
-			if !empty && len(t.embeddeds) > 0 {
-				buf.WriteString("; ")
-			}
-			for i, typ := range t.embeddeds {
-				if i > 0 {
-					buf.WriteString("; ")
-				}
-				writeType(buf, typ, qf, visited)
-				empty = false
-			}
+			first = false
+			buf.WriteString(m.name)
+			writeSignature(buf, m.typ.(*Signature), qf, visited)
 		}
-		if t.allMethods == nil || len(t.methods) > len(t.allMethods) {
-			if !empty {
-				buf.WriteByte(' ')
+		for _, typ := range t.embeddeds {
+			if !first {
+				buf.WriteString("; ")
 			}
-			buf.WriteString("/* incomplete */")
+			first = false
+			writeType(buf, typ, qf, visited)
 		}
 		buf.WriteByte('}')
 
@@ -255,7 +183,7 @@
 		case RecvOnly:
 			s = "<-chan "
 		default:
-			panic("unreachable")
+			unreachable()
 		}
 		buf.WriteString(s)
 		if parens {
@@ -267,39 +195,40 @@
 		}
 
 	case *Named:
+		if t.instance != nil {
+			buf.WriteByte(instanceMarker)
+		}
 		writeTypeName(buf, t.obj, qf)
 		if t.targs != nil {
 			// instantiated type
 			buf.WriteByte('[')
 			writeTypeList(buf, t.targs, qf, visited)
 			buf.WriteByte(']')
-		} else if t.tparams != nil {
+		} else if t.TParams().Len() != 0 {
 			// parameterized type
-			writeTParamList(buf, t.tparams, qf, visited)
+			writeTParamList(buf, t.TParams().list(), qf, visited)
 		}
 
 	case *TypeParam:
 		s := "?"
 		if t.obj != nil {
+			// Optionally write out package for typeparams (like Named).
+			// TODO(danscales): this is required for import/export, so
+			// we maybe need a separate function that won't be changed
+			// for debugging purposes.
+			if t.obj.pkg != nil {
+				writePackage(buf, t.obj.pkg, qf)
+			}
 			s = t.obj.name
 		}
 		buf.WriteString(s + subscript(t.id))
 
-	case *instance:
-		buf.WriteByte(instanceMarker) // indicate "non-evaluated" syntactic instance
-		writeTypeName(buf, t.base.obj, qf)
-		buf.WriteByte('[')
-		writeTypeList(buf, t.targs, qf, visited)
-		buf.WriteByte(']')
-
-	case *bottom:
-		buf.WriteString("⊥")
-
 	case *top:
 		buf.WriteString("⊤")
 
 	default:
 		// For externally defined implementations of Type.
+		// Note: In this case cycles won't be caught.
 		buf.WriteString(t.String())
 	}
 }
@@ -317,23 +246,27 @@
 	buf.WriteString("[")
 	var prev Type
 	for i, p := range list {
-		// TODO(gri) support 'any' sugar here.
-		var b Type = &emptyInterface
-		if t, _ := p.typ.(*TypeParam); t != nil && t.bound != nil {
-			b = t.bound
+		// Determine the type parameter and its constraint.
+		// list is expected to hold type parameter names,
+		// but don't crash if that's not the case.
+		tpar, _ := p.typ.(*TypeParam)
+		var bound Type
+		if tpar != nil {
+			bound = tpar.bound // should not be nil but we want to see it if it is
 		}
+
 		if i > 0 {
-			if b != prev {
-				// type bound changed - write previous one before advancing
+			if bound != prev {
+				// bound changed - write previous one before advancing
 				buf.WriteByte(' ')
 				writeType(buf, prev, qf, visited)
 			}
 			buf.WriteString(", ")
 		}
-		prev = b
+		prev = bound
 
-		if t, _ := p.typ.(*TypeParam); t != nil {
-			writeType(buf, t, qf, visited)
+		if tpar != nil {
+			writeType(buf, tpar, qf, visited)
 		} else {
 			buf.WriteString(p.name)
 		}
@@ -346,17 +279,38 @@
 }
 
 func writeTypeName(buf *bytes.Buffer, obj *TypeName, qf Qualifier) {
-	s := "<Named w/o object>"
-	if obj != nil {
-		if obj.pkg != nil {
-			writePackage(buf, obj.pkg, qf)
-		}
-		// TODO(gri): function-local named types should be displayed
-		// differently from named types at package level to avoid
-		// ambiguity.
-		s = obj.name
+	if obj == nil {
+		buf.WriteString("<Named w/o object>")
+		return
 	}
-	buf.WriteString(s)
+	if obj.pkg != nil {
+		writePackage(buf, obj.pkg, qf)
+	}
+	buf.WriteString(obj.name)
+
+	if instanceHashing != 0 {
+		// For local defined types, use the (original!) TypeName's scope
+		// numbers to disambiguate.
+		typ := obj.typ.(*Named)
+		// TODO(gri) Figure out why typ.orig != typ.orig.orig sometimes
+		//           and whether the loop can iterate more than twice.
+		//           (It seems somehow connected to instance types.)
+		for typ.orig != typ {
+			typ = typ.orig
+		}
+		writeScopeNumbers(buf, typ.obj.parent)
+	}
+}
+
+// writeScopeNumbers writes the number sequence for this scope to buf
+// in the form ".i.j.k" where i, j, k, etc. stand for scope numbers.
+// If a scope is nil or has no parent (such as a package scope), nothing
+// is written.
+func writeScopeNumbers(buf *bytes.Buffer, s *Scope) {
+	if s != nil && s.number > 0 {
+		writeScopeNumbers(buf, s.parent)
+		fmt.Fprintf(buf, ".%d", s.number)
+	}
 }
 
 func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visited []Type) {
@@ -379,7 +333,7 @@
 					// special case:
 					// append(s, "foo"...) leads to signature func([]byte, string...)
 					if t := asBasic(typ); t == nil || t.kind != String {
-						panic("internal error: string type expected")
+						panic("expected string type")
 					}
 					writeType(buf, typ, qf, visited)
 					buf.WriteString("...")
@@ -401,8 +355,8 @@
 }
 
 func writeSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier, visited []Type) {
-	if sig.tparams != nil {
-		writeTParamList(buf, sig.tparams, qf, visited)
+	if sig.TParams().Len() != 0 {
+		writeTParamList(buf, sig.TParams().list(), qf, visited)
 	}
 
 	writeTuple(buf, sig.params, sig.variadic, qf, visited)
diff --git a/src/cmd/compile/internal/types2/typestring_test.go b/src/cmd/compile/internal/types2/typestring_test.go
index d98e9a5..0ed2934 100644
--- a/src/cmd/compile/internal/types2/typestring_test.go
+++ b/src/cmd/compile/internal/types2/typestring_test.go
@@ -91,7 +91,8 @@
 	dup("interface{}"),
 	dup("interface{m()}"),
 	dup(`interface{String() string; m(int) float32}`),
-	dup(`interface{type int, float32, complex128}`),
+	dup("interface{int|float32|complex128}"),
+	dup("interface{int|~float32|~complex128}"),
 
 	// maps
 	dup("map[string]int"),
@@ -135,60 +136,6 @@
 	}
 }
 
-var nopos syntax.Pos
-
-func TestIncompleteInterfaces(t *testing.T) {
-	sig := NewSignature(nil, nil, nil, false)
-	m := NewFunc(nopos, nil, "m", sig)
-	for _, test := range []struct {
-		typ  *Interface
-		want string
-	}{
-		{new(Interface), "interface{/* incomplete */}"},
-		{new(Interface).Complete(), "interface{}"},
-
-		{NewInterface(nil, nil), "interface{}"},
-		{NewInterface(nil, nil).Complete(), "interface{}"},
-		{NewInterface([]*Func{}, nil), "interface{}"},
-		{NewInterface([]*Func{}, nil).Complete(), "interface{}"},
-		{NewInterface(nil, []*Named{}), "interface{}"},
-		{NewInterface(nil, []*Named{}).Complete(), "interface{}"},
-		{NewInterface([]*Func{m}, nil), "interface{m() /* incomplete */}"},
-		{NewInterface([]*Func{m}, nil).Complete(), "interface{m()}"},
-		{NewInterface(nil, []*Named{newDefined(new(Interface).Complete())}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(new(Interface).Complete())}).Complete(), "interface{T}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil))}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil).Complete())}), "interface{T /* incomplete */}"},
-		{NewInterface(nil, []*Named{newDefined(NewInterface([]*Func{m}, nil).Complete())}).Complete(), "interface{T}"},
-
-		{NewInterfaceType(nil, nil), "interface{}"},
-		{NewInterfaceType(nil, nil).Complete(), "interface{}"},
-		{NewInterfaceType([]*Func{}, nil), "interface{}"},
-		{NewInterfaceType([]*Func{}, nil).Complete(), "interface{}"},
-		{NewInterfaceType(nil, []Type{}), "interface{}"},
-		{NewInterfaceType(nil, []Type{}).Complete(), "interface{}"},
-		{NewInterfaceType([]*Func{m}, nil), "interface{m() /* incomplete */}"},
-		{NewInterfaceType([]*Func{m}, nil).Complete(), "interface{m()}"},
-		{NewInterfaceType(nil, []Type{new(Interface).Complete()}), "interface{interface{} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{new(Interface).Complete()}).Complete(), "interface{interface{}}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil)}), "interface{interface{m() /* incomplete */} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil).Complete()}), "interface{interface{m()} /* incomplete */}"},
-		{NewInterfaceType(nil, []Type{NewInterfaceType([]*Func{m}, nil).Complete()}).Complete(), "interface{interface{m()}}"},
-	} {
-		got := test.typ.String()
-		if got != test.want {
-			t.Errorf("got: %s, want: %s", got, test.want)
-		}
-	}
-}
-
-// newDefined creates a new defined type named T with the given underlying type.
-// Helper function for use with TestIncompleteInterfaces only.
-func newDefined(underlying Type) *Named {
-	tname := NewTypeName(nopos, nil, "T", nil)
-	return NewNamed(tname, underlying, nil)
-}
-
 func TestQualifiedTypeString(t *testing.T) {
 	p, _ := pkgFor("p.go", "package p; type T int", nil)
 	q, _ := pkgFor("q.go", "package q", nil)
diff --git a/src/cmd/compile/internal/types2/typeterm.go b/src/cmd/compile/internal/types2/typeterm.go
new file mode 100644
index 0000000..1d7223f
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeterm.go
@@ -0,0 +1,166 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+// A term describes elementary type sets:
+//
+//   ∅:  (*term)(nil)     == ∅                      // set of no types (empty set)
+//   𝓤:  &term{}          == 𝓤                      // set of all types (𝓤niverse)
+//   T:  &term{false, T}  == {T}                    // set of type T
+//  ~t:  &term{true, t}   == {t' | under(t') == t}  // set of types with underlying type t
+//
+type term struct {
+	tilde bool // valid if typ != nil
+	typ   Type
+}
+
+func (x *term) String() string {
+	switch {
+	case x == nil:
+		return "∅"
+	case x.typ == nil:
+		return "𝓤"
+	case x.tilde:
+		return "~" + x.typ.String()
+	default:
+		return x.typ.String()
+	}
+}
+
+// equal reports whether x and y represent the same type set.
+func (x *term) equal(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return x == y
+	case x.typ == nil || y.typ == nil:
+		return x.typ == y.typ
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	return x.tilde == y.tilde && Identical(x.typ, y.typ)
+}
+
+// union returns the union x ∪ y: zero, one, or two non-nil terms.
+func (x *term) union(y *term) (_, _ *term) {
+	// easy cases
+	switch {
+	case x == nil && y == nil:
+		return nil, nil // ∅ ∪ ∅ == ∅
+	case x == nil:
+		return y, nil // ∅ ∪ y == y
+	case y == nil:
+		return x, nil // x ∪ ∅ == x
+	case x.typ == nil:
+		return x, nil // 𝓤 ∪ y == 𝓤
+	case y.typ == nil:
+		return y, nil // x ∪ 𝓤 == 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∪ ~t == ~t
+	// ~t ∪  T == ~t
+	//  T ∪ ~t == ~t
+	//  T ∪  T ==  T
+	if x.tilde || !y.tilde {
+		return x, nil
+	}
+	return y, nil
+}
+
+// intersect returns the intersection x ∩ y.
+func (x *term) intersect(y *term) *term {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
+	case x.typ == nil:
+		return y // 𝓤 ∩ y == y
+	case y.typ == nil:
+		return x // x ∩ 𝓤 == x
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return nil // x ∩ y == ∅ if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∩ ~t == ~t
+	// ~t ∩  T ==  T
+	//  T ∩ ~t ==  T
+	//  T ∩  T ==  T
+	if !x.tilde || y.tilde {
+		return x
+	}
+	return y
+}
+
+// includes reports whether t ∈ x.
+func (x *term) includes(t Type) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return false // t ∈ ∅ == false
+	case x.typ == nil:
+		return true // t ∈ 𝓤 == true
+	}
+	// ∅ ⊂ x ⊂ 𝓤
+
+	u := t
+	if x.tilde {
+		u = under(u)
+	}
+	return Identical(x.typ, u)
+}
+
+// subsetOf reports whether x ⊆ y.
+func (x *term) subsetOf(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return true // ∅ ⊆ y == true
+	case y == nil:
+		return false // x ⊆ ∅ == false since x != ∅
+	case y.typ == nil:
+		return true // x ⊆ 𝓤 == true
+	case x.typ == nil:
+		return false // 𝓤 ⊆ y == false since y != 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return false // x ⊆ y == false if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ⊆ ~t == true
+	// ~t ⊆ T == false
+	//  T ⊆ ~t == true
+	//  T ⊆  T == true
+	return !x.tilde || y.tilde
+}
+
+// disjoint reports whether x ∩ y == ∅.
+// x.typ and y.typ must not be nil.
+func (x *term) disjoint(y *term) bool {
+	if debug && (x.typ == nil || y.typ == nil) {
+		panic("invalid argument(s)")
+	}
+	ux := x.typ
+	if y.tilde {
+		ux = under(ux)
+	}
+	uy := y.typ
+	if x.tilde {
+		uy = under(uy)
+	}
+	return !Identical(ux, uy)
+}
diff --git a/src/cmd/compile/internal/types2/typeterm_test.go b/src/cmd/compile/internal/types2/typeterm_test.go
new file mode 100644
index 0000000..5a5c1fa
--- /dev/null
+++ b/src/cmd/compile/internal/types2/typeterm_test.go
@@ -0,0 +1,239 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import (
+	"strings"
+	"testing"
+)
+
+var myInt = func() Type {
+	tname := NewTypeName(nopos, nil, "myInt", nil)
+	return NewNamed(tname, Typ[Int], nil)
+}()
+
+var testTerms = map[string]*term{
+	"∅":       nil,
+	"𝓤":       {},
+	"int":     {false, Typ[Int]},
+	"~int":    {true, Typ[Int]},
+	"string":  {false, Typ[String]},
+	"~string": {true, Typ[String]},
+	"myInt":   {false, myInt},
+}
+
+func TestTermString(t *testing.T) {
+	for want, x := range testTerms {
+		if got := x.String(); got != want {
+			t.Errorf("%v.String() == %v; want %v", x, got, want)
+		}
+	}
+}
+
+func split(s string, n int) []string {
+	r := strings.Split(s, " ")
+	if len(r) != n {
+		panic("invalid test case: " + s)
+	}
+	return r
+}
+
+func testTerm(name string) *term {
+	r, ok := testTerms[name]
+	if !ok {
+		panic("invalid test argument: " + name)
+	}
+	return r
+}
+
+func TestTermEqual(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ T",
+		"𝓤 𝓤 T",
+		"int int T",
+		"~int ~int T",
+		"myInt myInt T",
+		"∅ 𝓤 F",
+		"∅ int F",
+		"∅ ~int F",
+		"𝓤 int F",
+		"𝓤 ~int F",
+		"𝓤 myInt F",
+		"int ~int F",
+		"int myInt F",
+		"~int myInt F",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.equal(y); got != want {
+			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
+		}
+		// equal is symmetric
+		x, y = y, x
+		if got := x.equal(y); got != want {
+			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermUnion(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ ∅ ∅",
+		"∅ 𝓤 𝓤 ∅",
+		"∅ int int ∅",
+		"∅ ~int ~int ∅",
+		"∅ myInt myInt ∅",
+		"𝓤 𝓤 𝓤 ∅",
+		"𝓤 int 𝓤 ∅",
+		"𝓤 ~int 𝓤 ∅",
+		"𝓤 myInt 𝓤 ∅",
+		"int int int ∅",
+		"int ~int ~int ∅",
+		"int string int string",
+		"int ~string int ~string",
+		"int myInt int myInt",
+		"~int ~string ~int ~string",
+		"~int myInt ~int ∅",
+
+		// union is symmetric, but the result order isn't - repeat symmetric cases explictly
+		"𝓤 ∅ 𝓤 ∅",
+		"int ∅ int ∅",
+		"~int ∅ ~int ∅",
+		"myInt ∅ myInt ∅",
+		"int 𝓤 𝓤 ∅",
+		"~int 𝓤 𝓤 ∅",
+		"myInt 𝓤 𝓤 ∅",
+		"~int int ~int ∅",
+		"string int string int",
+		"~string int ~string int",
+		"myInt int myInt int",
+		"~string ~int ~string ~int",
+		"myInt ~int ~int ∅",
+	} {
+		args := split(test, 4)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want1 := testTerm(args[2])
+		want2 := testTerm(args[3])
+		if got1, got2 := x.union(y); !got1.equal(want1) || !got2.equal(want2) {
+			t.Errorf("%v.union(%v) = %v, %v; want %v, %v", x, y, got1, got2, want1, want2)
+		}
+	}
+}
+
+func TestTermIntersection(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ ∅",
+		"∅ 𝓤 ∅",
+		"∅ int ∅",
+		"∅ ~int ∅",
+		"∅ myInt ∅",
+		"𝓤 𝓤 𝓤",
+		"𝓤 int int",
+		"𝓤 ~int ~int",
+		"𝓤 myInt myInt",
+		"int int int",
+		"int ~int int",
+		"int string ∅",
+		"int ~string ∅",
+		"int string ∅",
+		"~int ~string ∅",
+		"~int myInt myInt",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := testTerm(args[2])
+		if got := x.intersect(y); !got.equal(want) {
+			t.Errorf("%v.intersect(%v) = %v; want %v", x, y, got, want)
+		}
+		// intersect is symmetric
+		x, y = y, x
+		if got := x.intersect(y); !got.equal(want) {
+			t.Errorf("%v.intersect(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermIncludes(t *testing.T) {
+	for _, test := range []string{
+		"∅ int F",
+		"𝓤 int T",
+		"int int T",
+		"~int int T",
+		"~int myInt T",
+		"string int F",
+		"~string int F",
+		"myInt int F",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1]).typ
+		want := args[2] == "T"
+		if got := x.includes(y); got != want {
+			t.Errorf("%v.includes(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermSubsetOf(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ T",
+		"𝓤 𝓤 T",
+		"int int T",
+		"~int ~int T",
+		"myInt myInt T",
+		"∅ 𝓤 T",
+		"∅ int T",
+		"∅ ~int T",
+		"∅ myInt T",
+		"𝓤 int F",
+		"𝓤 ~int F",
+		"𝓤 myInt F",
+		"int ~int T",
+		"int myInt F",
+		"~int myInt F",
+		"myInt int F",
+		"myInt ~int T",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.subsetOf(y); got != want {
+			t.Errorf("%v.subsetOf(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermDisjoint(t *testing.T) {
+	for _, test := range []string{
+		"int int F",
+		"~int ~int F",
+		"int ~int F",
+		"int string T",
+		"int ~string T",
+		"int myInt T",
+		"~int ~string T",
+		"~int myInt F",
+		"string myInt T",
+		"~string myInt T",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.disjoint(y); got != want {
+			t.Errorf("%v.disjoint(%v) = %v; want %v", x, y, got, want)
+		}
+		// disjoint is symmetric
+		x, y = y, x
+		if got := x.disjoint(y); got != want {
+			t.Errorf("%v.disjoint(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
diff --git a/src/cmd/compile/internal/types2/typexpr.go b/src/cmd/compile/internal/types2/typexpr.go
index e64d804..6a9eacd 100644
--- a/src/cmd/compile/internal/types2/typexpr.go
+++ b/src/cmd/compile/internal/types2/typexpr.go
@@ -10,14 +10,9 @@
 	"cmd/compile/internal/syntax"
 	"fmt"
 	"go/constant"
-	"sort"
-	"strconv"
 	"strings"
 )
 
-// Disabled by default, but enabled when running tests (via types_test.go).
-var acceptMethodTypeParams bool
-
 // ident type-checks identifier e and initializes x with the value or type of e.
 // If an error occurred, x.mode is set to invalid.
 // For the meaning of def, see Checker.definedType, below.
@@ -30,7 +25,8 @@
 	// Note that we cannot use check.lookup here because the returned scope
 	// may be different from obj.Parent(). See also Scope.LookupParent doc.
 	scope, obj := check.scope.LookupParent(e.Value, check.pos)
-	if obj == nil {
+	switch obj {
+	case nil:
 		if e.Value == "_" {
 			check.error(e, "cannot use _ as value or type")
 		} else {
@@ -41,6 +37,16 @@
 			}
 		}
 		return
+	case universeAny, universeComparable:
+		if !check.allowVersion(check.pkg, 1, 18) {
+			check.errorf(e, "undeclared name: %s (requires version go1.18 or later)", e.Value)
+			return
+		}
+		// If we allow "any" for general use, this if-statement can be removed (issue #33232).
+		if obj == universeAny {
+			check.error(e, "cannot use any outside constraint position")
+			return
+		}
 	}
 	check.recordUse(e, obj)
 
@@ -63,7 +69,7 @@
 	// If so, mark the respective package as used.
 	// (This code is only needed for dot-imports. Without them,
 	// we only have to mark variables, see *Var case below).
-	if pkgName := check.dotImportMap[dotImportKey{scope, obj}]; pkgName != nil {
+	if pkgName := check.dotImportMap[dotImportKey{scope, obj.Name()}]; pkgName != nil {
 		pkgName.used = true
 	}
 
@@ -141,18 +147,18 @@
 // ordinaryType reports an error if typ is an interface type containing
 // type lists or is (or embeds) the predeclared type comparable.
 func (check *Checker) ordinaryType(pos syntax.Pos, typ Type) {
-	// We don't want to call under() (via Interface) or complete interfaces while we
+	// We don't want to call under() (via asInterface) or complete interfaces while we
 	// are in the middle of type-checking parameter declarations that might belong to
 	// interface methods. Delay this check to the end of type-checking.
 	check.later(func() {
 		if t := asInterface(typ); t != nil {
-			check.completeInterface(pos, t) // TODO(gri) is this the correct position?
-			if t.allTypes != nil {
-				check.softErrorf(pos, "interface contains type constraints (%s)", t.allTypes)
-				return
-			}
-			if t.IsComparable() {
-				check.softErrorf(pos, "interface is (or embeds) comparable")
+			tset := computeInterfaceTypeSet(check, pos, t) // TODO(gri) is this the correct position?
+			if !tset.IsMethodSet() {
+				if tset.comparable {
+					check.softErrorf(pos, "interface is (or embeds) comparable")
+				} else {
+					check.softErrorf(pos, "interface contains type constraints")
+				}
 			}
 		}
 	})
@@ -198,238 +204,6 @@
 	return typ
 }
 
-// isubst returns an x with identifiers substituted per the substitution map smap.
-// isubst only handles the case of (valid) method receiver type expressions correctly.
-func isubst(x syntax.Expr, smap map[*syntax.Name]*syntax.Name) syntax.Expr {
-	switch n := x.(type) {
-	case *syntax.Name:
-		if alt := smap[n]; alt != nil {
-			return alt
-		}
-	// case *syntax.StarExpr:
-	// 	X := isubst(n.X, smap)
-	// 	if X != n.X {
-	// 		new := *n
-	// 		new.X = X
-	// 		return &new
-	// 	}
-	case *syntax.Operation:
-		if n.Op == syntax.Mul && n.Y == nil {
-			X := isubst(n.X, smap)
-			if X != n.X {
-				new := *n
-				new.X = X
-				return &new
-			}
-		}
-	case *syntax.IndexExpr:
-		Index := isubst(n.Index, smap)
-		if Index != n.Index {
-			new := *n
-			new.Index = Index
-			return &new
-		}
-	case *syntax.ListExpr:
-		var elems []syntax.Expr
-		for i, elem := range n.ElemList {
-			new := isubst(elem, smap)
-			if new != elem {
-				if elems == nil {
-					elems = make([]syntax.Expr, len(n.ElemList))
-					copy(elems, n.ElemList)
-				}
-				elems[i] = new
-			}
-		}
-		if elems != nil {
-			new := *n
-			new.ElemList = elems
-			return &new
-		}
-	case *syntax.ParenExpr:
-		return isubst(n.X, smap) // no need to keep parentheses
-	default:
-		// Other receiver type expressions are invalid.
-		// It's fine to ignore those here as they will
-		// be checked elsewhere.
-	}
-	return x
-}
-
-// funcType type-checks a function or method type.
-func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []*syntax.Field, ftyp *syntax.FuncType) {
-	check.openScope(ftyp, "function")
-	check.scope.isFunc = true
-	check.recordScope(ftyp, check.scope)
-	sig.scope = check.scope
-	defer check.closeScope()
-
-	var recvTyp syntax.Expr // rewritten receiver type; valid if != nil
-	if recvPar != nil {
-		// collect generic receiver type parameters, if any
-		// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
-		// - the receiver specification acts as local declaration for its type parameters, which may be blank
-		_, rname, rparams := check.unpackRecv(recvPar.Type, true)
-		if len(rparams) > 0 {
-			// Blank identifiers don't get declared and regular type-checking of the instantiated
-			// parameterized receiver type expression fails in Checker.collectParams of receiver.
-			// Identify blank type parameters and substitute each with a unique new identifier named
-			// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
-			// name.
-			var smap map[*syntax.Name]*syntax.Name // substitution map from "_" to "!n" identifiers
-			for i, p := range rparams {
-				if p.Value == "_" {
-					new := *p
-					new.Value = fmt.Sprintf("%d_", i)
-					rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
-					if smap == nil {
-						smap = make(map[*syntax.Name]*syntax.Name)
-					}
-					smap[p] = &new
-				}
-			}
-			if smap != nil {
-				// blank identifiers were found => use rewritten receiver type
-				recvTyp = isubst(recvPar.Type, smap)
-			}
-			// TODO(gri) rework declareTypeParams
-			sig.rparams = nil
-			for _, rparam := range rparams {
-				sig.rparams = check.declareTypeParam(sig.rparams, rparam)
-			}
-			// determine receiver type to get its type parameters
-			// and the respective type parameter bounds
-			var recvTParams []*TypeName
-			if rname != nil {
-				// recv should be a Named type (otherwise an error is reported elsewhere)
-				// Also: Don't report an error via genericType since it will be reported
-				//       again when we type-check the signature.
-				// TODO(gri) maybe the receiver should be marked as invalid instead?
-				if recv := asNamed(check.genericType(rname, false)); recv != nil {
-					recvTParams = recv.tparams
-				}
-			}
-			// provide type parameter bounds
-			// - only do this if we have the right number (otherwise an error is reported elsewhere)
-			if len(sig.rparams) == len(recvTParams) {
-				// We have a list of *TypeNames but we need a list of Types.
-				list := make([]Type, len(sig.rparams))
-				for i, t := range sig.rparams {
-					list[i] = t.typ
-				}
-				smap := makeSubstMap(recvTParams, list)
-				for i, tname := range sig.rparams {
-					bound := recvTParams[i].typ.(*TypeParam).bound
-					// bound is (possibly) parameterized in the context of the
-					// receiver type declaration. Substitute parameters for the
-					// current context.
-					// TODO(gri) should we assume now that bounds always exist?
-					//           (no bound == empty interface)
-					if bound != nil {
-						bound = check.subst(tname.pos, bound, smap)
-						tname.typ.(*TypeParam).bound = bound
-					}
-				}
-			}
-		}
-	}
-
-	if tparams != nil {
-		sig.tparams = check.collectTypeParams(tparams)
-		// Always type-check method type parameters but complain if they are not enabled.
-		// (A separate check is needed when type-checking interface method signatures because
-		// they don't have a receiver specification.)
-		if recvPar != nil && !acceptMethodTypeParams {
-			check.error(ftyp, "methods cannot have type parameters")
-		}
-	}
-
-	// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
-	// declarations and then squash that scope into the parent scope (and report any redeclarations at
-	// that time).
-	scope := NewScope(check.scope, nopos, nopos, "function body (temp. scope)")
-	var recvList []*Var // TODO(gri) remove the need for making a list here
-	if recvPar != nil {
-		recvList, _ = check.collectParams(scope, []*syntax.Field{recvPar}, recvTyp, false) // use rewritten receiver type, if any
-	}
-	params, variadic := check.collectParams(scope, ftyp.ParamList, nil, true)
-	results, _ := check.collectParams(scope, ftyp.ResultList, nil, false)
-	scope.Squash(func(obj, alt Object) {
-		var err error_
-		err.errorf(obj, "%s redeclared in this block", obj.Name())
-		err.recordAltDecl(alt)
-		check.report(&err)
-	})
-
-	if recvPar != nil {
-		// recv parameter list present (may be empty)
-		// spec: "The receiver is specified via an extra parameter section preceding the
-		// method name. That parameter section must declare a single parameter, the receiver."
-		var recv *Var
-		switch len(recvList) {
-		case 0:
-			// error reported by resolver
-			recv = NewParam(nopos, nil, "", Typ[Invalid]) // ignore recv below
-		default:
-			// more than one receiver
-			check.error(recvList[len(recvList)-1].Pos(), "method must have exactly one receiver")
-			fallthrough // continue with first receiver
-		case 1:
-			recv = recvList[0]
-		}
-
-		// TODO(gri) We should delay rtyp expansion to when we actually need the
-		//           receiver; thus all checks here should be delayed to later.
-		rtyp, _ := deref(recv.typ)
-		rtyp = expand(rtyp)
-
-		// spec: "The receiver type must be of the form T or *T where T is a type name."
-		// (ignore invalid types - error was reported before)
-		if t := rtyp; t != Typ[Invalid] {
-			var err string
-			if T := asNamed(t); T != nil {
-				// spec: "The type denoted by T is called the receiver base type; it must not
-				// be a pointer or interface type and it must be declared in the same package
-				// as the method."
-				if T.obj.pkg != check.pkg {
-					err = "type not defined in this package"
-					if check.conf.CompilerErrorMessages {
-						check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
-						err = ""
-					}
-				} else {
-					switch u := optype(T).(type) {
-					case *Basic:
-						// unsafe.Pointer is treated like a regular pointer
-						if u.kind == UnsafePointer {
-							err = "unsafe.Pointer"
-						}
-					case *Pointer, *Interface:
-						err = "pointer or interface type"
-					}
-				}
-			} else if T := asBasic(t); T != nil {
-				err = "basic or unnamed type"
-				if check.conf.CompilerErrorMessages {
-					check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
-					err = ""
-				}
-			} else {
-				check.errorf(recv.pos, "invalid receiver type %s", recv.typ)
-			}
-			if err != "" {
-				check.errorf(recv.pos, "invalid receiver type %s (%s)", recv.typ, err)
-				// ok to continue
-			}
-		}
-		sig.recv = recv
-	}
-
-	sig.params = NewTuple(params...)
-	sig.results = NewTuple(results...)
-	sig.variadic = variadic
-}
-
 // goTypeName returns the Go type name for typ and
 // removes any occurrences of "types2." from that name.
 func goTypeName(typ Type) string {
@@ -647,44 +421,32 @@
 	return Typ[Invalid]
 }
 
-func (check *Checker) instantiatedType(x syntax.Expr, targs []syntax.Expr, def *Named) Type {
-	b := check.genericType(x, true) // TODO(gri) what about cycles?
-	if b == Typ[Invalid] {
-		return b // error already reported
-	}
-	base := asNamed(b)
-	if base == nil {
-		unreachable() // should have been caught by genericType
+func (check *Checker) instantiatedType(x syntax.Expr, targsx []syntax.Expr, def *Named) Type {
+	base := check.genericType(x, true)
+	if base == Typ[Invalid] {
+		return base // error already reported
 	}
 
-	// create a new type instance rather than instantiate the type
-	// TODO(gri) should do argument number check here rather than
-	//           when instantiating the type?
-	typ := new(instance)
-	def.setUnderlying(typ)
-
-	typ.check = check
-	typ.pos = x.Pos()
-	typ.base = base
-
-	// evaluate arguments (always)
-	typ.targs = check.typeList(targs)
-	if typ.targs == nil {
+	// evaluate arguments
+	targs := check.typeList(targsx)
+	if targs == nil {
 		def.setUnderlying(Typ[Invalid]) // avoid later errors due to lazy instantiation
 		return Typ[Invalid]
 	}
 
-	// determine argument positions (for error reporting)
-	typ.poslist = make([]syntax.Pos, len(targs))
-	for i, arg := range targs {
-		typ.poslist[i] = syntax.StartPos(arg)
+	// determine argument positions
+	posList := make([]syntax.Pos, len(targs))
+	for i, arg := range targsx {
+		posList[i] = syntax.StartPos(arg)
 	}
 
+	typ := check.InstantiateLazy(x.Pos(), base, targs, posList, true)
+	def.setUnderlying(typ)
+
 	// make sure we check instantiation works at least once
 	// and that the resulting type is valid
 	check.later(func() {
-		t := typ.expand()
-		check.validType(t, nil)
+		check.validType(typ, nil)
 	})
 
 	return typ
@@ -732,537 +494,3 @@
 	}
 	return res
 }
-
-// collectParams declares the parameters of list in scope and returns the corresponding
-// variable list. If type0 != nil, it is used instead of the first type in list.
-func (check *Checker) collectParams(scope *Scope, list []*syntax.Field, type0 syntax.Expr, variadicOk bool) (params []*Var, variadic bool) {
-	if list == nil {
-		return
-	}
-
-	var named, anonymous bool
-
-	var typ Type
-	var prev syntax.Expr
-	for i, field := range list {
-		ftype := field.Type
-		// type-check type of grouped fields only once
-		if ftype != prev {
-			prev = ftype
-			if i == 0 && type0 != nil {
-				ftype = type0
-			}
-			if t, _ := ftype.(*syntax.DotsType); t != nil {
-				ftype = t.Elem
-				if variadicOk && i == len(list)-1 {
-					variadic = true
-				} else {
-					check.softErrorf(t, "can only use ... with final parameter in list")
-					// ignore ... and continue
-				}
-			}
-			typ = check.varType(ftype)
-		}
-		// The parser ensures that f.Tag is nil and we don't
-		// care if a constructed AST contains a non-nil tag.
-		if field.Name != nil {
-			// named parameter
-			name := field.Name.Value
-			if name == "" {
-				check.error(field.Name, invalidAST+"anonymous parameter")
-				// ok to continue
-			}
-			par := NewParam(field.Name.Pos(), check.pkg, name, typ)
-			check.declare(scope, field.Name, par, scope.pos)
-			params = append(params, par)
-			named = true
-		} else {
-			// anonymous parameter
-			par := NewParam(ftype.Pos(), check.pkg, "", typ)
-			check.recordImplicit(field, par)
-			params = append(params, par)
-			anonymous = true
-		}
-	}
-
-	if named && anonymous {
-		check.error(list[0], invalidAST+"list contains both named and anonymous parameters")
-		// ok to continue
-	}
-
-	// For a variadic function, change the last parameter's type from T to []T.
-	// Since we type-checked T rather than ...T, we also need to retro-actively
-	// record the type for ...T.
-	if variadic {
-		last := params[len(params)-1]
-		last.typ = &Slice{elem: last.typ}
-		check.recordTypeAndValue(list[len(list)-1].Type, typexpr, last.typ, nil)
-	}
-
-	return
-}
-
-func (check *Checker) declareInSet(oset *objset, pos syntax.Pos, obj Object) bool {
-	if alt := oset.insert(obj); alt != nil {
-		var err error_
-		err.errorf(pos, "%s redeclared", obj.Name())
-		err.recordAltDecl(alt)
-		check.report(&err)
-		return false
-	}
-	return true
-}
-
-func (check *Checker) interfaceType(ityp *Interface, iface *syntax.InterfaceType, def *Named) {
-	var tname *syntax.Name // most recent "type" name
-	var types []syntax.Expr
-	for _, f := range iface.MethodList {
-		if f.Name != nil {
-			// We have a method with name f.Name, or a type
-			// of a type list (f.Name.Value == "type").
-			name := f.Name.Value
-			if name == "_" {
-				if check.conf.CompilerErrorMessages {
-					check.error(f.Name, "methods must have a unique non-blank name")
-				} else {
-					check.error(f.Name, "invalid method name _")
-				}
-				continue // ignore
-			}
-
-			if name == "type" {
-				// Always collect all type list entries, even from
-				// different type lists, under the assumption that
-				// the author intended to include all types.
-				types = append(types, f.Type)
-				if tname != nil && tname != f.Name {
-					check.error(f.Name, "cannot have multiple type lists in an interface")
-				}
-				tname = f.Name
-				continue
-			}
-
-			typ := check.typ(f.Type)
-			sig, _ := typ.(*Signature)
-			if sig == nil {
-				if typ != Typ[Invalid] {
-					check.errorf(f.Type, invalidAST+"%s is not a method signature", typ)
-				}
-				continue // ignore
-			}
-
-			// Always type-check method type parameters but complain if they are not enabled.
-			// (This extra check is needed here because interface method signatures don't have
-			// a receiver specification.)
-			if sig.tparams != nil && !acceptMethodTypeParams {
-				check.error(f.Type, "methods cannot have type parameters")
-			}
-
-			// use named receiver type if available (for better error messages)
-			var recvTyp Type = ityp
-			if def != nil {
-				recvTyp = def
-			}
-			sig.recv = NewVar(f.Name.Pos(), check.pkg, "", recvTyp)
-
-			m := NewFunc(f.Name.Pos(), check.pkg, name, sig)
-			check.recordDef(f.Name, m)
-			ityp.methods = append(ityp.methods, m)
-		} else {
-			// We have an embedded type. completeInterface will
-			// eventually verify that we have an interface.
-			ityp.embeddeds = append(ityp.embeddeds, check.typ(f.Type))
-			check.posMap[ityp] = append(check.posMap[ityp], f.Type.Pos())
-		}
-	}
-
-	// type constraints
-	ityp.types = NewSum(check.collectTypeConstraints(iface.Pos(), types))
-
-	if len(ityp.methods) == 0 && ityp.types == nil && len(ityp.embeddeds) == 0 {
-		// empty interface
-		ityp.allMethods = markComplete
-		return
-	}
-
-	// sort for API stability
-	sortMethods(ityp.methods)
-	sortTypes(ityp.embeddeds)
-
-	check.later(func() { check.completeInterface(iface.Pos(), ityp) })
-}
-
-func (check *Checker) completeInterface(pos syntax.Pos, ityp *Interface) {
-	if ityp.allMethods != nil {
-		return
-	}
-
-	// completeInterface may be called via the LookupFieldOrMethod,
-	// MissingMethod, Identical, or IdenticalIgnoreTags external API
-	// in which case check will be nil. In this case, type-checking
-	// must be finished and all interfaces should have been completed.
-	if check == nil {
-		panic("internal error: incomplete interface")
-	}
-
-	if check.conf.Trace {
-		// Types don't generally have position information.
-		// If we don't have a valid pos provided, try to use
-		// one close enough.
-		if !pos.IsKnown() && len(ityp.methods) > 0 {
-			pos = ityp.methods[0].pos
-		}
-
-		check.trace(pos, "complete %s", ityp)
-		check.indent++
-		defer func() {
-			check.indent--
-			check.trace(pos, "=> %s (methods = %v, types = %v)", ityp, ityp.allMethods, ityp.allTypes)
-		}()
-	}
-
-	// An infinitely expanding interface (due to a cycle) is detected
-	// elsewhere (Checker.validType), so here we simply assume we only
-	// have valid interfaces. Mark the interface as complete to avoid
-	// infinite recursion if the validType check occurs later for some
-	// reason.
-	ityp.allMethods = markComplete
-
-	// Methods of embedded interfaces are collected unchanged; i.e., the identity
-	// of a method I.m's Func Object of an interface I is the same as that of
-	// the method m in an interface that embeds interface I. On the other hand,
-	// if a method is embedded via multiple overlapping embedded interfaces, we
-	// don't provide a guarantee which "original m" got chosen for the embedding
-	// interface. See also issue #34421.
-	//
-	// If we don't care to provide this identity guarantee anymore, instead of
-	// reusing the original method in embeddings, we can clone the method's Func
-	// Object and give it the position of a corresponding embedded interface. Then
-	// we can get rid of the mpos map below and simply use the cloned method's
-	// position.
-
-	var seen objset
-	var methods []*Func
-	mpos := make(map[*Func]syntax.Pos) // method specification or method embedding position, for good error messages
-	addMethod := func(pos syntax.Pos, m *Func, explicit bool) {
-		switch other := seen.insert(m); {
-		case other == nil:
-			methods = append(methods, m)
-			mpos[m] = pos
-		case explicit:
-			var err error_
-			err.errorf(pos, "duplicate method %s", m.name)
-			err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
-			check.report(&err)
-		default:
-			// We have a duplicate method name in an embedded (not explicitly declared) method.
-			// Check method signatures after all types are computed (issue #33656).
-			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
-			// error here as well (even though we could do it eagerly) because it's the same
-			// error message.
-			check.later(func() {
-				if !check.allowVersion(m.pkg, 1, 14) || !check.identical(m.typ, other.Type()) {
-					var err error_
-					err.errorf(pos, "duplicate method %s", m.name)
-					err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
-					check.report(&err)
-				}
-			})
-		}
-	}
-
-	for _, m := range ityp.methods {
-		addMethod(m.pos, m, true)
-	}
-
-	// collect types
-	allTypes := ityp.types
-
-	posList := check.posMap[ityp]
-	for i, typ := range ityp.embeddeds {
-		pos := posList[i] // embedding position
-		utyp := under(typ)
-		etyp := asInterface(utyp)
-		if etyp == nil {
-			if utyp != Typ[Invalid] {
-				var format string
-				if _, ok := utyp.(*TypeParam); ok {
-					format = "%s is a type parameter, not an interface"
-				} else {
-					format = "%s is not an interface"
-				}
-				check.errorf(pos, format, typ)
-			}
-			continue
-		}
-		check.completeInterface(pos, etyp)
-		for _, m := range etyp.allMethods {
-			addMethod(pos, m, false) // use embedding position pos rather than m.pos
-		}
-		allTypes = intersect(allTypes, etyp.allTypes)
-	}
-
-	if methods != nil {
-		sortMethods(methods)
-		ityp.allMethods = methods
-	}
-	ityp.allTypes = allTypes
-}
-
-// intersect computes the intersection of the types x and y.
-// Note: A incomming nil type stands for the top type. A top
-// type result is returned as nil.
-func intersect(x, y Type) (r Type) {
-	defer func() {
-		if r == theTop {
-			r = nil
-		}
-	}()
-
-	switch {
-	case x == theBottom || y == theBottom:
-		return theBottom
-	case x == nil || x == theTop:
-		return y
-	case y == nil || x == theTop:
-		return x
-	}
-
-	xtypes := unpack(x)
-	ytypes := unpack(y)
-	// Compute the list rtypes which includes only
-	// types that are in both xtypes and ytypes.
-	// Quadratic algorithm, but good enough for now.
-	// TODO(gri) fix this
-	var rtypes []Type
-	for _, x := range xtypes {
-		if includes(ytypes, x) {
-			rtypes = append(rtypes, x)
-		}
-	}
-
-	if rtypes == nil {
-		return theBottom
-	}
-	return NewSum(rtypes)
-}
-
-func sortTypes(list []Type) {
-	sort.Stable(byUniqueTypeName(list))
-}
-
-// byUniqueTypeName named type lists can be sorted by their unique type names.
-type byUniqueTypeName []Type
-
-func (a byUniqueTypeName) Len() int           { return len(a) }
-func (a byUniqueTypeName) Less(i, j int) bool { return sortName(a[i]) < sortName(a[j]) }
-func (a byUniqueTypeName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-
-func sortName(t Type) string {
-	if named := asNamed(t); named != nil {
-		return named.obj.Id()
-	}
-	return ""
-}
-
-func sortMethods(list []*Func) {
-	sort.Sort(byUniqueMethodName(list))
-}
-
-func assertSortedMethods(list []*Func) {
-	if !debug {
-		panic("internal error: assertSortedMethods called outside debug mode")
-	}
-	if !sort.IsSorted(byUniqueMethodName(list)) {
-		panic("internal error: methods not sorted")
-	}
-}
-
-// byUniqueMethodName method lists can be sorted by their unique method names.
-type byUniqueMethodName []*Func
-
-func (a byUniqueMethodName) Len() int           { return len(a) }
-func (a byUniqueMethodName) Less(i, j int) bool { return a[i].less(a[j]) }
-func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-
-func (check *Checker) tag(t *syntax.BasicLit) string {
-	// If t.Bad, an error was reported during parsing.
-	if t != nil && !t.Bad {
-		if t.Kind == syntax.StringLit {
-			if val, err := strconv.Unquote(t.Value); err == nil {
-				return val
-			}
-		}
-		check.errorf(t, invalidAST+"incorrect tag syntax: %q", t.Value)
-	}
-	return ""
-}
-
-func (check *Checker) structType(styp *Struct, e *syntax.StructType) {
-	if e.FieldList == nil {
-		return
-	}
-
-	// struct fields and tags
-	var fields []*Var
-	var tags []string
-
-	// for double-declaration checks
-	var fset objset
-
-	// current field typ and tag
-	var typ Type
-	var tag string
-	add := func(ident *syntax.Name, embedded bool, pos syntax.Pos) {
-		if tag != "" && tags == nil {
-			tags = make([]string, len(fields))
-		}
-		if tags != nil {
-			tags = append(tags, tag)
-		}
-
-		name := ident.Value
-		fld := NewField(pos, check.pkg, name, typ, embedded)
-		// spec: "Within a struct, non-blank field names must be unique."
-		if name == "_" || check.declareInSet(&fset, pos, fld) {
-			fields = append(fields, fld)
-			check.recordDef(ident, fld)
-		}
-	}
-
-	// addInvalid adds an embedded field of invalid type to the struct for
-	// fields with errors; this keeps the number of struct fields in sync
-	// with the source as long as the fields are _ or have different names
-	// (issue #25627).
-	addInvalid := func(ident *syntax.Name, pos syntax.Pos) {
-		typ = Typ[Invalid]
-		tag = ""
-		add(ident, true, pos)
-	}
-
-	var prev syntax.Expr
-	for i, f := range e.FieldList {
-		// Fields declared syntactically with the same type (e.g.: a, b, c T)
-		// share the same type expression. Only check type if it's a new type.
-		if i == 0 || f.Type != prev {
-			typ = check.varType(f.Type)
-			prev = f.Type
-		}
-		tag = ""
-		if i < len(e.TagList) {
-			tag = check.tag(e.TagList[i])
-		}
-		if f.Name != nil {
-			// named field
-			add(f.Name, false, f.Name.Pos())
-		} else {
-			// embedded field
-			// spec: "An embedded type must be specified as a type name T or as a
-			// pointer to a non-interface type name *T, and T itself may not be a
-			// pointer type."
-			pos := syntax.StartPos(f.Type)
-			name := embeddedFieldIdent(f.Type)
-			if name == nil {
-				check.errorf(pos, "invalid embedded field type %s", f.Type)
-				name = &syntax.Name{Value: "_"} // TODO(gri) need to set position to pos
-				addInvalid(name, pos)
-				continue
-			}
-			add(name, true, pos)
-
-			// Because we have a name, typ must be of the form T or *T, where T is the name
-			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
-			// We must delay this check to the end because we don't want to instantiate
-			// (via under(t)) a possibly incomplete type.
-			embeddedTyp := typ // for closure below
-			embeddedPos := pos
-			check.later(func() {
-				t, isPtr := deref(embeddedTyp)
-				switch t := optype(t).(type) {
-				case *Basic:
-					if t == Typ[Invalid] {
-						// error was reported before
-						return
-					}
-					// unsafe.Pointer is treated like a regular pointer
-					if t.kind == UnsafePointer {
-						check.error(embeddedPos, "embedded field type cannot be unsafe.Pointer")
-					}
-				case *Pointer:
-					check.error(embeddedPos, "embedded field type cannot be a pointer")
-				case *Interface:
-					if isPtr {
-						check.error(embeddedPos, "embedded field type cannot be a pointer to an interface")
-					}
-				}
-			})
-		}
-	}
-
-	styp.fields = fields
-	styp.tags = tags
-}
-
-func embeddedFieldIdent(e syntax.Expr) *syntax.Name {
-	switch e := e.(type) {
-	case *syntax.Name:
-		return e
-	case *syntax.Operation:
-		if base := ptrBase(e); base != nil {
-			// *T is valid, but **T is not
-			if op, _ := base.(*syntax.Operation); op == nil || ptrBase(op) == nil {
-				return embeddedFieldIdent(e.X)
-			}
-		}
-	case *syntax.SelectorExpr:
-		return e.Sel
-	case *syntax.IndexExpr:
-		return embeddedFieldIdent(e.X)
-	}
-	return nil // invalid embedded field
-}
-
-func (check *Checker) collectTypeConstraints(pos syntax.Pos, types []syntax.Expr) []Type {
-	list := make([]Type, 0, len(types)) // assume all types are correct
-	for _, texpr := range types {
-		if texpr == nil {
-			check.error(pos, invalidAST+"missing type constraint")
-			continue
-		}
-		list = append(list, check.varType(texpr))
-	}
-
-	// Ensure that each type is only present once in the type list.  Types may be
-	// interfaces, which may not be complete yet. It's ok to do this check at the
-	// end because it's not a requirement for correctness of the code.
-	// Note: This is a quadratic algorithm, but type lists tend to be short.
-	check.later(func() {
-		for i, t := range list {
-			if t := asInterface(t); t != nil {
-				check.completeInterface(types[i].Pos(), t)
-			}
-			if includes(list[:i], t) {
-				check.softErrorf(types[i], "duplicate type %s in type list", t)
-			}
-		}
-	})
-
-	return list
-}
-
-// includes reports whether typ is in list
-func includes(list []Type, typ Type) bool {
-	for _, e := range list {
-		if Identical(typ, e) {
-			return true
-		}
-	}
-	return false
-}
-
-func ptrBase(x *syntax.Operation) syntax.Expr {
-	if x.Op == syntax.Mul && x.Y == nil {
-		return x.X
-	}
-	return nil
-}
diff --git a/src/cmd/compile/internal/types2/unify.go b/src/cmd/compile/internal/types2/unify.go
index e1832bb..ae81382 100644
--- a/src/cmd/compile/internal/types2/unify.go
+++ b/src/cmd/compile/internal/types2/unify.go
@@ -6,7 +6,10 @@
 
 package types2
 
-import "bytes"
+import (
+	"bytes"
+	"fmt"
+)
 
 // The unifier maintains two separate sets of type parameters x and y
 // which are used to resolve type parameters in the x and y arguments
@@ -34,7 +37,6 @@
 // and the respective types inferred for each type parameter.
 // A unifier is created by calling newUnifier.
 type unifier struct {
-	check *Checker
 	exact bool
 	x, y  tparamsList // x and y must initialized via tparamsList.init
 	types []Type      // inferred types, shared by x and y
@@ -45,8 +47,8 @@
 // exactly. If exact is not set, a named type's underlying type
 // is considered if unification would fail otherwise, and the
 // direction of channels is ignored.
-func newUnifier(check *Checker, exact bool) *unifier {
-	u := &unifier{check: check, exact: exact}
+func newUnifier(exact bool) *unifier {
+	u := &unifier{exact: exact}
 	u.x.unifier = u
 	u.y.unifier = u
 	return u
@@ -148,10 +150,17 @@
 // If typ is a type parameter of d, index returns the type parameter index.
 // Otherwise, the result is < 0.
 func (d *tparamsList) index(typ Type) int {
-	if t, ok := typ.(*TypeParam); ok {
-		if i := t.index; i < len(d.tparams) && d.tparams[i].typ == t {
-			return i
-		}
+	if tpar, ok := typ.(*TypeParam); ok {
+		return tparamIndex(d.tparams, tpar)
+	}
+	return -1
+}
+
+// If tpar is a type parameter in list, tparamIndex returns the type parameter index.
+// Otherwise, the result is < 0. tpar must not be nil.
+func tparamIndex(list []*TypeName, tpar *TypeParam) int {
+	if i := tpar.index; i < len(list) && list[i].typ == tpar {
+		return i
 	}
 	return -1
 }
@@ -220,10 +229,6 @@
 // code the corresponding changes should be made here.
 // Must not be called directly from outside the unifier.
 func (u *unifier) nify(x, y Type, p *ifacePair) bool {
-	// types must be expanded for comparison
-	x = expand(x)
-	y = expand(y)
-
 	if !u.exact {
 		// If exact unification is known to fail because we attempt to
 		// match a type name against an unnamed type literal, consider
@@ -352,25 +357,18 @@
 				u.nify(x.results, y.results, p)
 		}
 
-	case *Sum:
-		// This should not happen with the current internal use of sum types.
-		panic("type inference across sum types not implemented")
-
 	case *Interface:
 		// Two interface types are identical if they have the same set of methods with
 		// the same names and identical function types. Lower-case method names from
 		// different packages are always different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			// If identical0 is called (indirectly) via an external API entry point
-			// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
-			// that case, interfaces are expected to be complete and lazy completion
-			// here is not needed.
-			if u.check != nil {
-				u.check.completeInterface(nopos, x)
-				u.check.completeInterface(nopos, y)
+			xset := x.typeSet()
+			yset := y.typeSet()
+			if !xset.terms.equal(yset.terms) {
+				return false
 			}
-			a := x.allMethods
-			b := y.allMethods
+			a := xset.methods
+			b := yset.methods
 			if len(a) == len(b) {
 				// Interface types are the only types where cycles can occur
 				// that are not "terminated" via named types; and such cycles
@@ -434,6 +432,8 @@
 		// 	return x.obj == y.obj
 		// }
 		if y, ok := y.(*Named); ok {
+			x.expand()
+			y.expand()
 			// TODO(gri) This is not always correct: two types may have the same names
 			//           in the same package if one of them is nested in a function.
 			//           Extremely unlikely but we need an always correct solution.
@@ -454,15 +454,11 @@
 		// are identical if they originate in the same declaration.
 		return x == y
 
-	// case *instance:
-	//	unreachable since types are expanded
-
 	case nil:
 		// avoid a crash in case of nil type
 
 	default:
-		u.check.dump("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams)
-		unreachable()
+		panic(fmt.Sprintf("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams))
 	}
 
 	return false
diff --git a/src/cmd/compile/internal/types2/union.go b/src/cmd/compile/internal/types2/union.go
new file mode 100644
index 0000000..f61c37a
--- /dev/null
+++ b/src/cmd/compile/internal/types2/union.go
@@ -0,0 +1,150 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types2
+
+import "cmd/compile/internal/syntax"
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Union represents a union of terms embedded in an interface.
+type Union struct {
+	terms []*Term  // list of syntactical terms (not a canonicalized termlist)
+	tset  *TypeSet // type set described by this union, computed lazily
+}
+
+// NewUnion returns a new Union type with the given terms.
+// It is an error to create an empty union; they are syntactically not possible.
+func NewUnion(terms []*Term) *Union {
+	if len(terms) == 0 {
+		panic("empty union")
+	}
+	return &Union{terms, nil}
+}
+
+func (u *Union) Len() int         { return len(u.terms) }
+func (u *Union) Term(i int) *Term { return u.terms[i] }
+
+func (u *Union) Underlying() Type { return u }
+func (u *Union) String() string   { return TypeString(u, nil) }
+
+// A Term represents a term in a Union.
+type Term term
+
+// NewTerm returns a new union term.
+func NewTerm(tilde bool, typ Type) *Term { return &Term{tilde, typ} }
+
+func (t *Term) Tilde() bool    { return t.tilde }
+func (t *Term) Type() Type     { return t.typ }
+func (t *Term) String() string { return (*term)(t).String() }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// Avoid excessive type-checking times due to quadratic termlist operations.
+const maxTermCount = 100
+
+// parseUnion parses the given list of type expressions tlist as a union of
+// those expressions. The result is a Union type, or Typ[Invalid] for some
+// errors.
+func parseUnion(check *Checker, tlist []syntax.Expr) Type {
+	var terms []*Term
+	for _, x := range tlist {
+		tilde, typ := parseTilde(check, x)
+		if len(tlist) == 1 && !tilde {
+			return typ // single type (optimization)
+		}
+		if len(terms) >= maxTermCount {
+			check.errorf(x, "cannot handle more than %d union terms (implementation limitation)", maxTermCount)
+			return Typ[Invalid]
+		}
+		terms = append(terms, NewTerm(tilde, typ))
+	}
+
+	// Check validity of terms.
+	// Do this check later because it requires types to be set up.
+	// Note: This is a quadratic algorithm, but unions tend to be short.
+	check.later(func() {
+		for i, t := range terms {
+			if t.typ == Typ[Invalid] {
+				continue
+			}
+
+			x := tlist[i]
+			pos := syntax.StartPos(x)
+			// We may not know the position of x if it was a typechecker-
+			// introduced ~T term for a type list entry T. Use the position
+			// of T instead.
+			// TODO(gri) remove this test once we don't support type lists anymore
+			if !pos.IsKnown() {
+				if op, _ := x.(*syntax.Operation); op != nil {
+					pos = syntax.StartPos(op.X)
+				}
+			}
+
+			u := under(t.typ)
+			f, _ := u.(*Interface)
+			if t.tilde {
+				if f != nil {
+					check.errorf(x, "invalid use of ~ (%s is an interface)", t.typ)
+					continue // don't report another error for t
+				}
+
+				if !Identical(u, t.typ) {
+					check.errorf(x, "invalid use of ~ (underlying type of %s is %s)", t.typ, u)
+					continue // don't report another error for t
+				}
+			}
+
+			// Stand-alone embedded interfaces are ok and are handled by the single-type case
+			// in the beginning. Embedded interfaces with tilde are excluded above. If we reach
+			// here, we must have at least two terms in the union.
+			if f != nil && !f.typeSet().IsTypeSet() {
+				check.errorf(pos, "cannot use %s in union (interface contains methods)", t)
+				continue // don't report another error for t
+			}
+
+			// Report overlapping (non-disjoint) terms such as
+			// a|a, a|~a, ~a|~a, and ~a|A (where under(A) == a).
+			if j := overlappingTerm(terms[:i], t); j >= 0 {
+				check.softErrorf(pos, "overlapping terms %s and %s", t, terms[j])
+			}
+		}
+	})
+
+	return &Union{terms, nil}
+}
+
+func parseTilde(check *Checker, x syntax.Expr) (tilde bool, typ Type) {
+	if op, _ := x.(*syntax.Operation); op != nil && op.Op == syntax.Tilde {
+		x = op.X
+		tilde = true
+	}
+	typ = check.anyType(x)
+	// embedding stand-alone type parameters is not permitted (issue #47127).
+	if _, ok := under(typ).(*TypeParam); ok {
+		check.error(x, "cannot embed a type parameter")
+		typ = Typ[Invalid]
+	}
+	return
+}
+
+// overlappingTerm reports the index of the term x in terms which is
+// overlapping (not disjoint) from y. The result is < 0 if there is no
+// such term.
+func overlappingTerm(terms []*Term, y *Term) int {
+	for i, x := range terms {
+		// disjoint requires non-nil, non-top arguments
+		if debug {
+			if x == nil || x.typ == nil || y == nil || y.typ == nil {
+				panic("empty or top union term")
+			}
+		}
+		if !(*term)(x).disjoint((*term)(y)) {
+			return i
+		}
+	}
+	return -1
+}
diff --git a/src/cmd/compile/internal/types2/universe.go b/src/cmd/compile/internal/types2/universe.go
index 76d4e55..f14c079 100644
--- a/src/cmd/compile/internal/types2/universe.go
+++ b/src/cmd/compile/internal/types2/universe.go
@@ -20,11 +20,12 @@
 var Unsafe *Package
 
 var (
-	universeIota  *Const
-	universeByte  *Basic // uint8 alias, but has name "byte"
-	universeRune  *Basic // int32 alias, but has name "rune"
-	universeAny   *Interface
-	universeError *Named
+	universeIota       Object
+	universeByte       Type // uint8 alias, but has name "byte"
+	universeRune       Type // int32 alias, but has name "rune"
+	universeAny        Object
+	universeError      Type
+	universeComparable Object
 )
 
 // Typ contains the predeclared *Basic types indexed by their
@@ -77,20 +78,30 @@
 		def(NewTypeName(nopos, nil, t.name, t))
 	}
 
-	// any
-	// (Predeclared and entered into universe scope so we do all the
-	// usual checks; but removed again from scope later since it's
-	// only visible as constraint in a type parameter list.)
+	// type any = interface{}
 	def(NewTypeName(nopos, nil, "any", &emptyInterface))
 
-	// Error has a nil package in its qualified name since it is in no package
+	// type error interface{ Error() string }
 	{
+		obj := NewTypeName(nopos, nil, "error", nil)
+		obj.setColor(black)
 		res := NewVar(nopos, nil, "", Typ[String])
-		sig := &Signature{results: NewTuple(res)}
+		sig := NewSignature(nil, nil, NewTuple(res), false)
 		err := NewFunc(nopos, nil, "Error", sig)
-		typ := &Named{underlying: NewInterfaceType([]*Func{err}, nil).Complete()}
+		ityp := &Interface{obj, []*Func{err}, nil, nil, true, nil}
+		computeInterfaceTypeSet(nil, nopos, ityp) // prevent races due to lazy computation of tset
+		typ := NewNamed(obj, ityp, nil)
 		sig.recv = NewVar(nopos, nil, "", typ)
-		def(NewTypeName(nopos, nil, "error", typ))
+		def(obj)
+	}
+
+	// type comparable interface{ /* type set marked comparable */ }
+	{
+		obj := NewTypeName(nopos, nil, "comparable", nil)
+		obj.setColor(black)
+		ityp := &Interface{obj, nil, nil, nil, true, &TypeSet{true, nil, allTermlist}}
+		NewNamed(obj, ityp, nil)
+		def(obj)
 	}
 }
 
@@ -200,33 +211,6 @@
 	def(newBuiltin(_Trace))
 }
 
-func defPredeclaredComparable() {
-	// The "comparable" interface can be imagined as defined like
-	//
-	// type comparable interface {
-	//         == () untyped bool
-	//         != () untyped bool
-	// }
-	//
-	// == and != cannot be user-declared but we can declare
-	// a magic method == and check for its presence when needed.
-
-	// Define interface { == () }. We don't care about the signature
-	// for == so leave it empty except for the receiver, which is
-	// set up later to match the usual interface method assumptions.
-	sig := new(Signature)
-	eql := NewFunc(nopos, nil, "==", sig)
-	iface := NewInterfaceType([]*Func{eql}, nil).Complete()
-
-	// set up the defined type for the interface
-	obj := NewTypeName(nopos, nil, "comparable", nil)
-	named := NewNamed(obj, iface, nil)
-	obj.color_ = black
-	sig.recv = NewVar(nopos, nil, "", named) // complete == signature
-
-	def(obj)
-}
-
 func init() {
 	Universe = NewScope(nil, nopos, nopos, "universe")
 	Unsafe = NewPackage("unsafe", "unsafe")
@@ -236,16 +220,13 @@
 	defPredeclaredConsts()
 	defPredeclaredNil()
 	defPredeclaredFuncs()
-	defPredeclaredComparable()
 
-	universeIota = Universe.Lookup("iota").(*Const)
-	universeByte = Universe.Lookup("byte").(*TypeName).typ.(*Basic)
-	universeRune = Universe.Lookup("rune").(*TypeName).typ.(*Basic)
-	universeAny = Universe.Lookup("any").(*TypeName).typ.(*Interface)
-	universeError = Universe.Lookup("error").(*TypeName).typ.(*Named)
-
-	// "any" is only visible as constraint in a type parameter list
-	delete(Universe.elems, "any")
+	universeIota = Universe.Lookup("iota")
+	universeByte = Universe.Lookup("byte").Type()
+	universeRune = Universe.Lookup("rune").Type()
+	universeAny = Universe.Lookup("any")
+	universeError = Universe.Lookup("error").Type()
+	universeComparable = Universe.Lookup("comparable")
 }
 
 // Objects with names containing blanks are internal and not entered into
@@ -277,6 +258,6 @@
 		}
 	}
 	if scope.Insert(obj) != nil {
-		panic("internal error: double declaration")
+		panic("double declaration of predeclared identifier")
 	}
 }
diff --git a/src/cmd/compile/internal/walk/assign.go b/src/cmd/compile/internal/walk/assign.go
index 6d697a5..d4c1aaf 100644
--- a/src/cmd/compile/internal/walk/assign.go
+++ b/src/cmd/compile/internal/walk/assign.go
@@ -429,6 +429,7 @@
 		ir.OBITNOT,
 		ir.OCONV,
 		ir.OCONVIFACE,
+		ir.OCONVIDATA,
 		ir.OCONVNOP,
 		ir.ODIV,
 		ir.ODOT,
diff --git a/src/cmd/compile/internal/walk/builtin.go b/src/cmd/compile/internal/walk/builtin.go
index 14efc05..af4f8f4 100644
--- a/src/cmd/compile/internal/walk/builtin.go
+++ b/src/cmd/compile/internal/walk/builtin.go
@@ -641,16 +641,9 @@
 	return walkStmt(typecheck.Stmt(r))
 }
 
-// walkRecover walks an ORECOVER node.
-func walkRecover(nn *ir.CallExpr, init *ir.Nodes) ir.Node {
-	// Call gorecover with the FP of this frame.
-	// FP is equal to caller's SP plus FixedFrameSize().
-	var fp ir.Node = mkcall("getcallersp", types.Types[types.TUINTPTR], init)
-	if off := base.Ctxt.FixedFrameSize(); off != 0 {
-		fp = ir.NewBinaryExpr(fp.Pos(), ir.OADD, fp, ir.NewInt(off))
-	}
-	fp = ir.NewConvExpr(fp.Pos(), ir.OCONVNOP, types.NewPtr(types.Types[types.TINT32]), fp)
-	return mkcall("gorecover", nn.Type(), init, fp)
+// walkRecover walks an ORECOVERFP node.
+func walkRecoverFP(nn *ir.CallExpr, init *ir.Nodes) ir.Node {
+	return mkcall("gorecover", nn.Type(), init, walkExpr(nn.Args[0], init))
 }
 
 func walkUnsafeSlice(n *ir.BinaryExpr, init *ir.Nodes) ir.Node {
diff --git a/src/cmd/compile/internal/walk/closure.go b/src/cmd/compile/internal/walk/closure.go
index 2194e1c..902e01e 100644
--- a/src/cmd/compile/internal/walk/closure.go
+++ b/src/cmd/compile/internal/walk/closure.go
@@ -37,14 +37,6 @@
 		return // leave for walkClosure to handle
 	}
 
-	// If wrapGoDefer() in the order phase has flagged this call,
-	// avoid eliminating the closure even if there is a direct call to
-	// (the closure is needed to simplify the register ABI). See
-	// wrapGoDefer for more details.
-	if n.PreserveClosure {
-		return
-	}
-
 	// We are going to insert captured variables before input args.
 	var params []*types.Field
 	var decls []*ir.Name
@@ -122,6 +114,9 @@
 	clos := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ), nil)
 	clos.SetEsc(clo.Esc())
 	clos.List = append([]ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, clofn.Nname)}, closureArgs(clo)...)
+	for i, value := range clos.List {
+		clos.List[i] = ir.NewStructKeyExpr(base.Pos, typ.Field(i), value)
+	}
 
 	addr := typecheck.NodAddr(clos)
 	addr.SetEsc(clo.Esc())
@@ -161,7 +156,7 @@
 	return args
 }
 
-func walkCallPart(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
+func walkMethodValue(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
 	// Create closure in the form of a composite literal.
 	// For x.M with receiver (x) type T, the generated code looks like:
 	//
@@ -175,18 +170,16 @@
 		n.X = cheapExpr(n.X, init)
 		n.X = walkExpr(n.X, nil)
 
-		tab := typecheck.Expr(ir.NewUnaryExpr(base.Pos, ir.OITAB, n.X))
-
-		c := ir.NewUnaryExpr(base.Pos, ir.OCHECKNIL, tab)
-		c.SetTypecheck(1)
-		init.Append(c)
+		tab := ir.NewUnaryExpr(base.Pos, ir.OITAB, n.X)
+		check := ir.NewUnaryExpr(base.Pos, ir.OCHECKNIL, tab)
+		init.Append(typecheck.Stmt(check))
 	}
 
-	typ := typecheck.PartialCallType(n)
+	typ := typecheck.MethodValueType(n)
 
 	clos := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ), nil)
 	clos.SetEsc(n.Esc())
-	clos.List = []ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, typecheck.MethodValueWrapper(n).Nname), n.X}
+	clos.List = []ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, methodValueWrapper(n)), n.X}
 
 	addr := typecheck.NodAddr(clos)
 	addr.SetEsc(n.Esc())
@@ -205,3 +198,74 @@
 
 	return walkExpr(cfn, init)
 }
+
+// methodValueWrapper returns the ONAME node representing the
+// wrapper function (*-fm) needed for the given method value. If the
+// wrapper function hasn't already been created yet, it's created and
+// added to typecheck.Target.Decls.
+func methodValueWrapper(dot *ir.SelectorExpr) *ir.Name {
+	if dot.Op() != ir.OMETHVALUE {
+		base.Fatalf("methodValueWrapper: unexpected %v (%v)", dot, dot.Op())
+	}
+
+	t0 := dot.Type()
+	meth := dot.Sel
+	rcvrtype := dot.X.Type()
+	sym := ir.MethodSymSuffix(rcvrtype, meth, "-fm")
+
+	if sym.Uniq() {
+		return sym.Def.(*ir.Name)
+	}
+	sym.SetUniq(true)
+
+	savecurfn := ir.CurFunc
+	saveLineNo := base.Pos
+	ir.CurFunc = nil
+
+	// Set line number equal to the line number where the method is declared.
+	if pos := dot.Selection.Pos; pos.IsKnown() {
+		base.Pos = pos
+	}
+	// Note: !dot.Selection.Pos.IsKnown() happens for method expressions where
+	// the method is implicitly declared. The Error method of the
+	// built-in error type is one such method.  We leave the line
+	// number at the use of the method expression in this
+	// case. See issue 29389.
+
+	tfn := ir.NewFuncType(base.Pos, nil,
+		typecheck.NewFuncParams(t0.Params(), true),
+		typecheck.NewFuncParams(t0.Results(), false))
+
+	fn := typecheck.DeclFunc(sym, tfn)
+	fn.SetDupok(true)
+	fn.SetWrapper(true)
+
+	// Declare and initialize variable holding receiver.
+	ptr := ir.NewHiddenParam(base.Pos, fn, typecheck.Lookup(".this"), rcvrtype)
+
+	call := ir.NewCallExpr(base.Pos, ir.OCALL, ir.NewSelectorExpr(base.Pos, ir.OXDOT, ptr, meth), nil)
+	call.Args = ir.ParamNames(tfn.Type())
+	call.IsDDD = tfn.Type().IsVariadic()
+
+	var body ir.Node = call
+	if t0.NumResults() != 0 {
+		ret := ir.NewReturnStmt(base.Pos, nil)
+		ret.Results = []ir.Node{call}
+		body = ret
+	}
+
+	fn.Body = []ir.Node{body}
+	typecheck.FinishFuncBody()
+
+	typecheck.Func(fn)
+	// Need to typecheck the body of the just-generated wrapper.
+	// typecheckslice() requires that Curfn is set when processing an ORETURN.
+	ir.CurFunc = fn
+	typecheck.Stmts(fn.Body)
+	sym.Def = fn.Nname
+	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
+	ir.CurFunc = savecurfn
+	base.Pos = saveLineNo
+
+	return fn.Nname
+}
diff --git a/src/cmd/compile/internal/walk/complit.go b/src/cmd/compile/internal/walk/complit.go
index abd920d..6c6b498 100644
--- a/src/cmd/compile/internal/walk/complit.go
+++ b/src/cmd/compile/internal/walk/complit.go
@@ -218,11 +218,11 @@
 	case ir.OSTRUCTLIT:
 		splitnode = func(rn ir.Node) (ir.Node, ir.Node) {
 			r := rn.(*ir.StructKeyExpr)
-			if r.Field.IsBlank() || isBlank {
+			if r.Sym().IsBlank() || isBlank {
 				return ir.BlankNode, r.Value
 			}
 			ir.SetPos(r)
-			return ir.NewSelectorExpr(base.Pos, ir.ODOT, var_, r.Field), r.Value
+			return ir.NewSelectorExpr(base.Pos, ir.ODOT, var_, r.Sym()), r.Value
 		}
 	default:
 		base.Fatalf("fixedlit bad op: %v", n.Op())
diff --git a/src/cmd/compile/internal/walk/convert.go b/src/cmd/compile/internal/walk/convert.go
index 26e17a1..27a07ce 100644
--- a/src/cmd/compile/internal/walk/convert.go
+++ b/src/cmd/compile/internal/walk/convert.go
@@ -41,46 +41,98 @@
 
 // walkConvInterface walks an OCONVIFACE node.
 func walkConvInterface(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
+
 	n.X = walkExpr(n.X, init)
 
 	fromType := n.X.Type()
 	toType := n.Type()
-
-	if !fromType.IsInterface() && !ir.IsBlank(ir.CurFunc.Nname) { // skip unnamed functions (func _())
+	if !fromType.IsInterface() && !ir.IsBlank(ir.CurFunc.Nname) {
+		// skip unnamed functions (func _())
 		reflectdata.MarkTypeUsedInInterface(fromType, ir.CurFunc.LSym)
 	}
 
-	// typeword generates the type word of the interface value.
-	typeword := func() ir.Node {
+	if !fromType.IsInterface() {
+		var typeWord ir.Node
 		if toType.IsEmptyInterface() {
-			return reflectdata.TypePtr(fromType)
+			typeWord = reflectdata.TypePtr(fromType)
+		} else {
+			typeWord = reflectdata.ITabAddr(fromType, toType)
 		}
-		return reflectdata.ITabAddr(fromType, toType)
-	}
-
-	// Optimize convT2E or convT2I as a two-word copy when T is pointer-shaped.
-	if types.IsDirectIface(fromType) {
-		l := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeword(), n.X)
+		l := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeWord, dataWord(n.X, init, n.Esc() != ir.EscNone))
 		l.SetType(toType)
 		l.SetTypecheck(n.Typecheck())
 		return l
 	}
+	if fromType.IsEmptyInterface() {
+		base.Fatalf("OCONVIFACE can't operate on an empty interface")
+	}
 
-	// Optimize convT2{E,I} for many cases in which T is not pointer-shaped,
-	// by using an existing addressable value identical to n.Left
-	// or creating one on the stack.
+	// Evaluate the input interface.
+	c := typecheck.Temp(fromType)
+	init.Append(ir.NewAssignStmt(base.Pos, c, n.X))
+
+	// Grab its parts.
+	itab := ir.NewUnaryExpr(base.Pos, ir.OITAB, c)
+	itab.SetType(types.Types[types.TUINTPTR].PtrTo())
+	itab.SetTypecheck(1)
+	data := ir.NewUnaryExpr(base.Pos, ir.OIDATA, c)
+	data.SetType(types.Types[types.TUINT8].PtrTo()) // Type is generic pointer - we're just passing it through.
+	data.SetTypecheck(1)
+
+	var typeWord ir.Node
+	if toType.IsEmptyInterface() {
+		// Implement interface to empty interface conversion.
+		// res = itab
+		// if res != nil {
+		//    res = res.type
+		// }
+		typeWord = typecheck.Temp(types.NewPtr(types.Types[types.TUINT8]))
+		init.Append(ir.NewAssignStmt(base.Pos, typeWord, itab))
+		nif := ir.NewIfStmt(base.Pos, typecheck.Expr(ir.NewBinaryExpr(base.Pos, ir.ONE, typeWord, typecheck.NodNil())), nil, nil)
+		nif.Body = []ir.Node{ir.NewAssignStmt(base.Pos, typeWord, itabType(typeWord))}
+		init.Append(nif)
+	} else {
+		// Must be converting I2I (more specific to less specific interface).
+		// res = convI2I(toType, itab)
+		fn := typecheck.LookupRuntime("convI2I")
+		types.CalcSize(fn.Type())
+		call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, nil)
+		call.Args = []ir.Node{reflectdata.TypePtr(toType), itab}
+		typeWord = walkExpr(typecheck.Expr(call), init)
+	}
+
+	// Build the result.
+	// e = iface{typeWord, data}
+	e := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeWord, data)
+	e.SetType(toType) // assign type manually, typecheck doesn't understand OEFACE.
+	e.SetTypecheck(1)
+	return e
+}
+
+// Returns the data word (the second word) used to represent n in an interface.
+// n must not be of interface type.
+// esc describes whether the result escapes.
+func dataWord(n ir.Node, init *ir.Nodes, escapes bool) ir.Node {
+	fromType := n.Type()
+
+	// If it's a pointer, it is its own representation.
+	if types.IsDirectIface(fromType) {
+		return n
+	}
+
+	// Try a bunch of cases to avoid an allocation.
 	var value ir.Node
 	switch {
 	case fromType.Size() == 0:
-		// n.Left is zero-sized. Use zerobase.
-		cheapExpr(n.X, init) // Evaluate n.Left for side-effects. See issue 19246.
+		// n is zero-sized. Use zerobase.
+		cheapExpr(n, init) // Evaluate n for side-effects. See issue 19246.
 		value = ir.NewLinksymExpr(base.Pos, ir.Syms.Zerobase, types.Types[types.TUINTPTR])
 	case fromType.IsBoolean() || (fromType.Size() == 1 && fromType.IsInteger()):
-		// n.Left is a bool/byte. Use staticuint64s[n.Left * 8] on little-endian
-		// and staticuint64s[n.Left * 8 + 7] on big-endian.
-		n.X = cheapExpr(n.X, init)
-		// byteindex widens n.Left so that the multiplication doesn't overflow.
-		index := ir.NewBinaryExpr(base.Pos, ir.OLSH, byteindex(n.X), ir.NewInt(3))
+		// n is a bool/byte. Use staticuint64s[n * 8] on little-endian
+		// and staticuint64s[n * 8 + 7] on big-endian.
+		n = cheapExpr(n, init)
+		// byteindex widens n so that the multiplication doesn't overflow.
+		index := ir.NewBinaryExpr(base.Pos, ir.OLSH, byteindex(n), ir.NewInt(3))
 		if ssagen.Arch.LinkArch.ByteOrder == binary.BigEndian {
 			index = ir.NewBinaryExpr(base.Pos, ir.OADD, index, ir.NewInt(7))
 		}
@@ -90,118 +142,71 @@
 		xe := ir.NewIndexExpr(base.Pos, staticuint64s, index)
 		xe.SetBounded(true)
 		value = xe
-	case n.X.Op() == ir.ONAME && n.X.(*ir.Name).Class == ir.PEXTERN && n.X.(*ir.Name).Readonly():
-		// n.Left is a readonly global; use it directly.
-		value = n.X
-	case !fromType.IsInterface() && n.Esc() == ir.EscNone && fromType.Width <= 1024:
-		// n.Left does not escape. Use a stack temporary initialized to n.Left.
+	case n.Op() == ir.ONAME && n.(*ir.Name).Class == ir.PEXTERN && n.(*ir.Name).Readonly():
+		// n is a readonly global; use it directly.
+		value = n
+	case !escapes && fromType.Width <= 1024:
+		// n does not escape. Use a stack temporary initialized to n.
 		value = typecheck.Temp(fromType)
-		init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, value, n.X)))
+		init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, value, n)))
 	}
-
 	if value != nil {
-		// Value is identical to n.Left.
-		// Construct the interface directly: {type/itab, &value}.
-		l := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeword(), typecheck.Expr(typecheck.NodAddr(value)))
-		l.SetType(toType)
-		l.SetTypecheck(n.Typecheck())
-		return l
+		// The interface data word is &value.
+		return typecheck.Expr(typecheck.NodAddr(value))
 	}
 
-	// Implement interface to empty interface conversion.
-	// tmp = i.itab
-	// if tmp != nil {
-	//    tmp = tmp.type
-	// }
-	// e = iface{tmp, i.data}
-	if toType.IsEmptyInterface() && fromType.IsInterface() && !fromType.IsEmptyInterface() {
-		// Evaluate the input interface.
-		c := typecheck.Temp(fromType)
-		init.Append(ir.NewAssignStmt(base.Pos, c, n.X))
+	// Time to do an allocation. We'll call into the runtime for that.
+	fnname, argType, needsaddr := dataWordFuncName(fromType)
+	fn := typecheck.LookupRuntime(fnname)
 
-		// Get the itab out of the interface.
-		tmp := typecheck.Temp(types.NewPtr(types.Types[types.TUINT8]))
-		init.Append(ir.NewAssignStmt(base.Pos, tmp, typecheck.Expr(ir.NewUnaryExpr(base.Pos, ir.OITAB, c))))
-
-		// Get the type out of the itab.
-		nif := ir.NewIfStmt(base.Pos, typecheck.Expr(ir.NewBinaryExpr(base.Pos, ir.ONE, tmp, typecheck.NodNil())), nil, nil)
-		nif.Body = []ir.Node{ir.NewAssignStmt(base.Pos, tmp, itabType(tmp))}
-		init.Append(nif)
-
-		// Build the result.
-		e := ir.NewBinaryExpr(base.Pos, ir.OEFACE, tmp, ifaceData(n.Pos(), c, types.NewPtr(types.Types[types.TUINT8])))
-		e.SetType(toType) // assign type manually, typecheck doesn't understand OEFACE.
-		e.SetTypecheck(1)
-		return e
-	}
-
-	fnname, argType, needsaddr := convFuncName(fromType, toType)
-
-	if !needsaddr && !fromType.IsInterface() {
-		// Use a specialized conversion routine that only returns a data pointer.
-		// ptr = convT2X(val)
-		// e = iface{typ/tab, ptr}
-		fn := typecheck.LookupRuntime(fnname)
-		types.CalcSize(fromType)
-
-		arg := n.X
+	var args []ir.Node
+	if needsaddr {
+		// Types of large or unknown size are passed by reference.
+		// Orderexpr arranged for n to be a temporary for all
+		// the conversions it could see. Comparison of an interface
+		// with a non-interface, especially in a switch on interface value
+		// with non-interface cases, is not visible to order.stmt, so we
+		// have to fall back on allocating a temp here.
+		if !ir.IsAddressable(n) {
+			n = copyExpr(n, fromType, init)
+		}
+		fn = typecheck.SubstArgTypes(fn, fromType)
+		args = []ir.Node{reflectdata.TypePtr(fromType), typecheck.NodAddr(n)}
+	} else {
+		// Use a specialized conversion routine that takes the type being
+		// converted by value, not by pointer.
+		var arg ir.Node
 		switch {
 		case fromType == argType:
 			// already in the right type, nothing to do
+			arg = n
 		case fromType.Kind() == argType.Kind(),
 			fromType.IsPtrShaped() && argType.IsPtrShaped():
 			// can directly convert (e.g. named type to underlying type, or one pointer to another)
-			arg = ir.NewConvExpr(n.Pos(), ir.OCONVNOP, argType, arg)
+			// TODO: never happens because pointers are directIface?
+			arg = ir.NewConvExpr(n.Pos(), ir.OCONVNOP, argType, n)
 		case fromType.IsInteger() && argType.IsInteger():
 			// can directly convert (e.g. int32 to uint32)
-			arg = ir.NewConvExpr(n.Pos(), ir.OCONV, argType, arg)
+			arg = ir.NewConvExpr(n.Pos(), ir.OCONV, argType, n)
 		default:
 			// unsafe cast through memory
-			arg = copyExpr(arg, arg.Type(), init)
+			arg = copyExpr(n, fromType, init)
 			var addr ir.Node = typecheck.NodAddr(arg)
 			addr = ir.NewConvExpr(n.Pos(), ir.OCONVNOP, argType.PtrTo(), addr)
 			arg = ir.NewStarExpr(n.Pos(), addr)
 			arg.SetType(argType)
 		}
-
-		call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, nil)
-		call.Args = []ir.Node{arg}
-		e := ir.NewBinaryExpr(base.Pos, ir.OEFACE, typeword(), safeExpr(walkExpr(typecheck.Expr(call), init), init))
-		e.SetType(toType)
-		e.SetTypecheck(1)
-		return e
+		args = []ir.Node{arg}
 	}
-
-	var tab ir.Node
-	if fromType.IsInterface() {
-		// convI2I
-		tab = reflectdata.TypePtr(toType)
-	} else {
-		// convT2x
-		tab = typeword()
-	}
-
-	v := n.X
-	if needsaddr {
-		// Types of large or unknown size are passed by reference.
-		// Orderexpr arranged for n.Left to be a temporary for all
-		// the conversions it could see. Comparison of an interface
-		// with a non-interface, especially in a switch on interface value
-		// with non-interface cases, is not visible to order.stmt, so we
-		// have to fall back on allocating a temp here.
-		if !ir.IsAddressable(v) {
-			v = copyExpr(v, v.Type(), init)
-		}
-		v = typecheck.NodAddr(v)
-	}
-
-	types.CalcSize(fromType)
-	fn := typecheck.LookupRuntime(fnname)
-	fn = typecheck.SubstArgTypes(fn, fromType, toType)
-	types.CalcSize(fn.Type())
 	call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, nil)
-	call.Args = []ir.Node{tab, v}
-	return walkExpr(typecheck.Expr(call), init)
+	call.Args = args
+	return safeExpr(walkExpr(typecheck.Expr(call), init), init)
+}
+
+// walkConvIData walks an OCONVIDATA node.
+func walkConvIData(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
+	n.X = walkExpr(n.X, init)
+	return dataWord(n.X, init, n.Esc() != ir.EscNone)
 }
 
 // walkBytesRunesToString walks an OBYTES2STR or ORUNES2STR node.
@@ -312,50 +317,35 @@
 	return mkcall("stringtoslicerune", n.Type(), init, a, typecheck.Conv(n.X, types.Types[types.TSTRING]))
 }
 
-// convFuncName builds the runtime function name for interface conversion.
-// It also returns the argument type that the runtime function takes, and
-// whether the function expects the data by address.
-// Not all names are possible. For example, we never generate convE2E or convE2I.
-func convFuncName(from, to *types.Type) (fnname string, argType *types.Type, needsaddr bool) {
-	tkind := to.Tie()
-	switch from.Tie() {
-	case 'I':
-		if tkind == 'I' {
-			return "convI2I", types.Types[types.TINTER], false
-		}
-	case 'T':
+// dataWordFuncName returns the name of the function used to convert a value of type "from"
+// to the data word of an interface.
+// argType is the type the argument needs to be coerced to.
+// needsaddr reports whether the value should be passed (needaddr==false) or its address (needsaddr==true).
+func dataWordFuncName(from *types.Type) (fnname string, argType *types.Type, needsaddr bool) {
+	if from.IsInterface() {
+		base.Fatalf("can only handle non-interfaces")
+	}
+	switch {
+	case from.Size() == 2 && from.Align == 2:
+		return "convT16", types.Types[types.TUINT16], false
+	case from.Size() == 4 && from.Align == 4 && !from.HasPointers():
+		return "convT32", types.Types[types.TUINT32], false
+	case from.Size() == 8 && from.Align == types.Types[types.TUINT64].Align && !from.HasPointers():
+		return "convT64", types.Types[types.TUINT64], false
+	}
+	if sc := from.SoleComponent(); sc != nil {
 		switch {
-		case from.Size() == 2 && from.Align == 2:
-			return "convT16", types.Types[types.TUINT16], false
-		case from.Size() == 4 && from.Align == 4 && !from.HasPointers():
-			return "convT32", types.Types[types.TUINT32], false
-		case from.Size() == 8 && from.Align == types.Types[types.TUINT64].Align && !from.HasPointers():
-			return "convT64", types.Types[types.TUINT64], false
-		}
-		if sc := from.SoleComponent(); sc != nil {
-			switch {
-			case sc.IsString():
-				return "convTstring", types.Types[types.TSTRING], false
-			case sc.IsSlice():
-				return "convTslice", types.NewSlice(types.Types[types.TUINT8]), false // the element type doesn't matter
-			}
-		}
-
-		switch tkind {
-		case 'E':
-			if !from.HasPointers() {
-				return "convT2Enoptr", types.Types[types.TUNSAFEPTR], true
-			}
-			return "convT2E", types.Types[types.TUNSAFEPTR], true
-		case 'I':
-			if !from.HasPointers() {
-				return "convT2Inoptr", types.Types[types.TUNSAFEPTR], true
-			}
-			return "convT2I", types.Types[types.TUNSAFEPTR], true
+		case sc.IsString():
+			return "convTstring", types.Types[types.TSTRING], false
+		case sc.IsSlice():
+			return "convTslice", types.NewSlice(types.Types[types.TUINT8]), false // the element type doesn't matter
 		}
 	}
-	base.Fatalf("unknown conv func %c2%c", from.Tie(), to.Tie())
-	panic("unreachable")
+
+	if from.HasPointers() {
+		return "convT", types.Types[types.TUNSAFEPTR], true
+	}
+	return "convTnoptr", types.Types[types.TUNSAFEPTR], true
 }
 
 // rtconvfn returns the parameter and result types that will be used by a
@@ -462,7 +452,9 @@
 	// TODO(mdempsky): Make stricter. We only need to exempt
 	// reflect.Value.Pointer and reflect.Value.UnsafeAddr.
 	switch n.X.Op() {
-	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
+	case ir.OCALLMETH:
+		base.FatalfAt(n.X.Pos(), "OCALLMETH missed by typecheck")
+	case ir.OCALLFUNC, ir.OCALLINTER:
 		return n
 	}
 
@@ -499,7 +491,7 @@
 
 	cheap := cheapExpr(n, init)
 
-	slice := typecheck.MakeDotArgs(types.NewSlice(types.Types[types.TUNSAFEPTR]), originals)
+	slice := typecheck.MakeDotArgs(base.Pos, types.NewSlice(types.Types[types.TUNSAFEPTR]), originals)
 	slice.SetEsc(ir.EscNone)
 
 	init.Append(mkcall("checkptrArithmetic", nil, init, typecheck.ConvNop(cheap, types.Types[types.TUNSAFEPTR]), slice))
diff --git a/src/cmd/compile/internal/walk/expr.go b/src/cmd/compile/internal/walk/expr.go
index 2fb9077..26e2254 100644
--- a/src/cmd/compile/internal/walk/expr.go
+++ b/src/cmd/compile/internal/walk/expr.go
@@ -82,7 +82,7 @@
 		base.Fatalf("walkExpr: switch 1 unknown op %+v", n.Op())
 		panic("unreachable")
 
-	case ir.ONONAME, ir.OGETG:
+	case ir.OGETG, ir.OGETCALLERPC, ir.OGETCALLERSP:
 		return n
 
 	case ir.OTYPE, ir.ONAME, ir.OLITERAL, ir.ONIL, ir.OLINKSYMOFFSET:
@@ -136,6 +136,10 @@
 		n := n.(*ir.TypeAssertExpr)
 		return walkDotType(n, init)
 
+	case ir.ODYNAMICDOTTYPE, ir.ODYNAMICDOTTYPE2:
+		n := n.(*ir.DynamicTypeAssertExpr)
+		return walkDynamicDotType(n, init)
+
 	case ir.OLEN, ir.OCAP:
 		n := n.(*ir.UnaryExpr)
 		return walkLenCap(n, init)
@@ -161,13 +165,13 @@
 		n := n.(*ir.UnaryExpr)
 		return mkcall("gopanic", nil, init, n.X)
 
-	case ir.ORECOVER:
-		return walkRecover(n.(*ir.CallExpr), init)
+	case ir.ORECOVERFP:
+		return walkRecoverFP(n.(*ir.CallExpr), init)
 
 	case ir.OCFUNC:
 		return n
 
-	case ir.OCALLINTER, ir.OCALLFUNC, ir.OCALLMETH:
+	case ir.OCALLINTER, ir.OCALLFUNC:
 		n := n.(*ir.CallExpr)
 		return walkCall(n, init)
 
@@ -206,6 +210,10 @@
 		n := n.(*ir.ConvExpr)
 		return walkConvInterface(n, init)
 
+	case ir.OCONVIDATA:
+		n := n.(*ir.ConvExpr)
+		return walkConvIData(n, init)
+
 	case ir.OCONV, ir.OCONVNOP:
 		n := n.(*ir.ConvExpr)
 		return walkConv(n, init)
@@ -308,8 +316,8 @@
 	case ir.OCLOSURE:
 		return walkClosure(n.(*ir.ClosureExpr), init)
 
-	case ir.OCALLPART:
-		return walkCallPart(n.(*ir.SelectorExpr), init)
+	case ir.OMETHVALUE:
+		return walkMethodValue(n.(*ir.SelectorExpr), init)
 	}
 
 	// No return! Each case must return (or panic),
@@ -487,9 +495,12 @@
 	return r1
 }
 
-// walkCall walks an OCALLFUNC, OCALLINTER, or OCALLMETH node.
+// walkCall walks an OCALLFUNC or OCALLINTER node.
 func walkCall(n *ir.CallExpr, init *ir.Nodes) ir.Node {
-	if n.Op() == ir.OCALLINTER || n.Op() == ir.OCALLMETH {
+	if n.Op() == ir.OCALLMETH {
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+	}
+	if n.Op() == ir.OCALLINTER || n.X.Op() == ir.OMETHEXPR {
 		// We expect both interface call reflect.Type.Method and concrete
 		// call reflect.(*rtype).Method.
 		usemethod(n)
@@ -549,20 +560,8 @@
 	}
 	n.SetWalked(true)
 
-	// If this is a method call t.M(...),
-	// rewrite into a function call T.M(t, ...).
-	// TODO(mdempsky): Do this right after type checking.
 	if n.Op() == ir.OCALLMETH {
-		withRecv := make([]ir.Node, len(n.Args)+1)
-		dot := n.X.(*ir.SelectorExpr)
-		withRecv[0] = dot.X
-		copy(withRecv[1:], n.Args)
-		n.Args = withRecv
-
-		dot = ir.NewSelectorExpr(dot.Pos(), ir.OXDOT, ir.TypeNode(dot.X.Type()), dot.Selection.Sym)
-
-		n.SetOp(ir.OCALLFUNC)
-		n.X = typecheck.Expr(dot)
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
 	}
 
 	args := n.Args
@@ -671,6 +670,13 @@
 	return n
 }
 
+// walkDynamicdotType walks an ODYNAMICDOTTYPE or ODYNAMICDOTTYPE2 node.
+func walkDynamicDotType(n *ir.DynamicTypeAssertExpr, init *ir.Nodes) ir.Node {
+	n.X = walkExpr(n.X, init)
+	n.T = walkExpr(n.T, init)
+	return n
+}
+
 // walkIndex walks an OINDEX node.
 func walkIndex(n *ir.IndexExpr, init *ir.Nodes) ir.Node {
 	n.X = walkExpr(n.X, init)
@@ -931,42 +937,8 @@
 	return false
 }
 
-// usemethod checks interface method calls for uses of reflect.Type.Method.
+// usemethod checks calls for uses of reflect.Type.{Method,MethodByName}.
 func usemethod(n *ir.CallExpr) {
-	t := n.X.Type()
-
-	// Looking for either of:
-	//	Method(int) reflect.Method
-	//	MethodByName(string) (reflect.Method, bool)
-	//
-	// TODO(crawshaw): improve precision of match by working out
-	//                 how to check the method name.
-	if n := t.NumParams(); n != 1 {
-		return
-	}
-	if n := t.NumResults(); n != 1 && n != 2 {
-		return
-	}
-	p0 := t.Params().Field(0)
-	res0 := t.Results().Field(0)
-	var res1 *types.Field
-	if t.NumResults() == 2 {
-		res1 = t.Results().Field(1)
-	}
-
-	if res1 == nil {
-		if p0.Type.Kind() != types.TINT {
-			return
-		}
-	} else {
-		if !p0.Type.IsString() {
-			return
-		}
-		if !res1.Type.IsBoolean() {
-			return
-		}
-	}
-
 	// Don't mark reflect.(*rtype).Method, etc. themselves in the reflect package.
 	// Those functions may be alive via the itab, which should not cause all methods
 	// alive. We only want to mark their callers.
@@ -977,10 +949,43 @@
 		}
 	}
 
-	// Note: Don't rely on res0.Type.String() since its formatting depends on multiple factors
-	//       (including global variables such as numImports - was issue #19028).
-	// Also need to check for reflect package itself (see Issue #38515).
-	if s := res0.Type.Sym(); s != nil && s.Name == "Method" && types.IsReflectPkg(s.Pkg) {
+	dot, ok := n.X.(*ir.SelectorExpr)
+	if !ok {
+		return
+	}
+
+	// Looking for either direct method calls and interface method calls of:
+	//	reflect.Type.Method       - func(int) reflect.Method
+	//	reflect.Type.MethodByName - func(string) (reflect.Method, bool)
+	var pKind types.Kind
+
+	switch dot.Sel.Name {
+	case "Method":
+		pKind = types.TINT
+	case "MethodByName":
+		pKind = types.TSTRING
+	default:
+		return
+	}
+
+	t := dot.Selection.Type
+	if t.NumParams() != 1 || t.Params().Field(0).Type.Kind() != pKind {
+		return
+	}
+	switch t.NumResults() {
+	case 1:
+		// ok
+	case 2:
+		if t.Results().Field(1).Type.Kind() != types.TBOOL {
+			return
+		}
+	default:
+		return
+	}
+
+	// Check that first result type is "reflect.Method". Note that we have to check sym name and sym package
+	// separately, as we can't check for exact string "reflect.Method" reliably (e.g., see #19028 and #38515).
+	if s := t.Results().Field(0).Type.Sym(); s != nil && s.Name == "Method" && types.IsReflectPkg(s.Pkg) {
 		ir.CurFunc.SetReflectMethod(true)
 		// The LSym is initialized at this point. We need to set the attribute on the LSym.
 		ir.CurFunc.LSym.Set(obj.AttrReflectMethod, true)
diff --git a/src/cmd/compile/internal/walk/order.go b/src/cmd/compile/internal/walk/order.go
index b733d3a2..6e336f5 100644
--- a/src/cmd/compile/internal/walk/order.go
+++ b/src/cmd/compile/internal/walk/order.go
@@ -7,10 +7,8 @@
 import (
 	"fmt"
 	"go/constant"
-	"internal/buildcfg"
 
 	"cmd/compile/internal/base"
-	"cmd/compile/internal/escape"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/reflectdata"
 	"cmd/compile/internal/staticinit"
@@ -53,7 +51,7 @@
 type orderState struct {
 	out  []ir.Node             // list of generated statements
 	temp []*ir.Name            // stack of temporary variables
-	free map[string][]*ir.Name // free list of unused temporaries, by type.LongString().
+	free map[string][]*ir.Name // free list of unused temporaries, by type.LinkString().
 	edit func(ir.Node) ir.Node // cached closure of o.exprNoLHS
 }
 
@@ -78,20 +76,14 @@
 // If clear is true, newTemp emits code to zero the temporary.
 func (o *orderState) newTemp(t *types.Type, clear bool) *ir.Name {
 	var v *ir.Name
-	// Note: LongString is close to the type equality we want,
-	// but not exactly. We still need to double-check with types.Identical.
-	key := t.LongString()
-	a := o.free[key]
-	for i, n := range a {
-		if types.Identical(t, n.Type()) {
-			v = a[i]
-			a[i] = a[len(a)-1]
-			a = a[:len(a)-1]
-			o.free[key] = a
-			break
+	key := t.LinkString()
+	if a := o.free[key]; len(a) > 0 {
+		v = a[len(a)-1]
+		if !types.Identical(t, v.Type()) {
+			base.Fatalf("expected %L to have type %v", v, t)
 		}
-	}
-	if v == nil {
+		o.free[key] = a[:len(a)-1]
+	} else {
 		v = typecheck.Temp(t)
 	}
 	if clear {
@@ -372,7 +364,7 @@
 // which must have been returned by markTemp.
 func (o *orderState) popTemp(mark ordermarker) {
 	for _, n := range o.temp[mark:] {
-		key := n.Type().LongString()
+		key := n.Type().LinkString()
 		o.free[key] = append(o.free[key], n)
 	}
 	o.temp = o.temp[:mark]
@@ -514,15 +506,18 @@
 }
 
 // call orders the call expression n.
-// n.Op is OCALLMETH/OCALLFUNC/OCALLINTER or a builtin like OCOPY.
+// n.Op is OCALLFUNC/OCALLINTER or a builtin like OCOPY.
 func (o *orderState) call(nn ir.Node) {
 	if len(nn.Init()) > 0 {
 		// Caller should have already called o.init(nn).
 		base.Fatalf("%v with unexpected ninit", nn.Op())
 	}
+	if nn.Op() == ir.OCALLMETH {
+		base.FatalfAt(nn.Pos(), "OCALLMETH missed by typecheck")
+	}
 
 	// Builtin functions.
-	if nn.Op() != ir.OCALLFUNC && nn.Op() != ir.OCALLMETH && nn.Op() != ir.OCALLINTER {
+	if nn.Op() != ir.OCALLFUNC && nn.Op() != ir.OCALLINTER {
 		switch n := nn.(type) {
 		default:
 			base.Fatalf("unexpected call: %+v", n)
@@ -554,39 +549,6 @@
 
 	n.X = o.expr(n.X, nil)
 	o.exprList(n.Args)
-
-	if n.Op() == ir.OCALLINTER {
-		return
-	}
-	keepAlive := func(arg ir.Node) {
-		// If the argument is really a pointer being converted to uintptr,
-		// arrange for the pointer to be kept alive until the call returns,
-		// by copying it into a temp and marking that temp
-		// still alive when we pop the temp stack.
-		if arg.Op() == ir.OCONVNOP {
-			arg := arg.(*ir.ConvExpr)
-			if arg.X.Type().IsUnsafePtr() {
-				x := o.copyExpr(arg.X)
-				arg.X = x
-				x.SetAddrtaken(true) // ensure SSA keeps the x variable
-				n.KeepAlive = append(n.KeepAlive, x)
-			}
-		}
-	}
-
-	// Check for "unsafe-uintptr" tag provided by escape analysis.
-	for i, param := range n.X.Type().Params().FieldSlice() {
-		if param.Note == escape.UnsafeUintptrNote || param.Note == escape.UintptrEscapesNote {
-			if arg := n.Args[i]; arg.Op() == ir.OSLICELIT {
-				arg := arg.(*ir.CompLitExpr)
-				for _, elt := range arg.List {
-					keepAlive(elt)
-				}
-			} else {
-				keepAlive(arg)
-			}
-		}
-	}
 }
 
 // mapAssign appends n to o.out.
@@ -693,9 +655,20 @@
 		n := n.(*ir.AssignListStmt)
 		t := o.markTemp()
 		o.exprList(n.Lhs)
-		o.init(n.Rhs[0])
-		o.call(n.Rhs[0])
-		o.as2func(n)
+		call := n.Rhs[0]
+		o.init(call)
+		if ic, ok := call.(*ir.InlinedCallExpr); ok {
+			o.stmtList(ic.Body)
+
+			n.SetOp(ir.OAS2)
+			n.Rhs = ic.ReturnVars
+
+			o.exprList(n.Rhs)
+			o.out = append(o.out, n)
+		} else {
+			o.call(call)
+			o.as2func(n)
+		}
 		o.cleanTemp(t)
 
 	// Special: use temporary variables to hold result,
@@ -713,6 +686,10 @@
 		case ir.ODOTTYPE2:
 			r := r.(*ir.TypeAssertExpr)
 			r.X = o.expr(r.X, nil)
+		case ir.ODYNAMICDOTTYPE2:
+			r := r.(*ir.DynamicTypeAssertExpr)
+			r.X = o.expr(r.X, nil)
+			r.T = o.expr(r.T, nil)
 		case ir.ORECV:
 			r := r.(*ir.UnaryExpr)
 			r.X = o.expr(r.X, nil)
@@ -748,14 +725,25 @@
 		o.out = append(o.out, n)
 
 	// Special: handle call arguments.
-	case ir.OCALLFUNC, ir.OCALLINTER, ir.OCALLMETH:
+	case ir.OCALLFUNC, ir.OCALLINTER:
 		n := n.(*ir.CallExpr)
 		t := o.markTemp()
 		o.call(n)
 		o.out = append(o.out, n)
 		o.cleanTemp(t)
 
-	case ir.OCLOSE, ir.ORECV:
+	case ir.OINLCALL:
+		n := n.(*ir.InlinedCallExpr)
+		o.stmtList(n.Body)
+
+		// discard results; double-check for no side effects
+		for _, result := range n.ReturnVars {
+			if staticinit.AnySideEffects(result) {
+				base.FatalfAt(result.Pos(), "inlined call result has side effects: %v", result)
+			}
+		}
+
+	case ir.OCHECKNIL, ir.OCLOSE, ir.OPANIC, ir.ORECV:
 		n := n.(*ir.UnaryExpr)
 		t := o.markTemp()
 		n.X = o.expr(n.X, nil)
@@ -770,10 +758,10 @@
 		o.out = append(o.out, n)
 		o.cleanTemp(t)
 
-	case ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+	case ir.OPRINT, ir.OPRINTN, ir.ORECOVERFP:
 		n := n.(*ir.CallExpr)
 		t := o.markTemp()
-		o.exprList(n.Args)
+		o.call(n)
 		o.out = append(o.out, n)
 		o.cleanTemp(t)
 
@@ -783,16 +771,6 @@
 		t := o.markTemp()
 		o.init(n.Call)
 		o.call(n.Call)
-		if n.Call.Op() == ir.ORECOVER {
-			// Special handling of "defer recover()". We need to evaluate the FP
-			// argument before wrapping.
-			var init ir.Nodes
-			n.Call = walkRecover(n.Call.(*ir.CallExpr), &init)
-			o.stmtList(init)
-		}
-		if buildcfg.Experiment.RegabiDefer {
-			o.wrapGoDefer(n)
-		}
 		o.out = append(o.out, n)
 		o.cleanTemp(t)
 
@@ -830,16 +808,6 @@
 		orderBlock(&n.Else, o.free)
 		o.out = append(o.out, n)
 
-	case ir.OPANIC:
-		n := n.(*ir.UnaryExpr)
-		t := o.markTemp()
-		n.X = o.expr(n.X, nil)
-		if !n.X.Type().IsEmptyInterface() {
-			base.FatalfAt(n.Pos(), "bad argument to panic: %L", n.X)
-		}
-		o.out = append(o.out, n)
-		o.cleanTemp(t)
-
 	case ir.ORANGE:
 		// n.Right is the expression being ranged over.
 		// order it, and then make a copy if we need one.
@@ -1192,23 +1160,26 @@
 
 	// concrete type (not interface) argument might need an addressable
 	// temporary to pass to the runtime conversion routine.
-	case ir.OCONVIFACE:
+	case ir.OCONVIFACE, ir.OCONVIDATA:
 		n := n.(*ir.ConvExpr)
 		n.X = o.expr(n.X, nil)
 		if n.X.Type().IsInterface() {
 			return n
 		}
-		if _, _, needsaddr := convFuncName(n.X.Type(), n.Type()); needsaddr || isStaticCompositeLiteral(n.X) {
+		if _, _, needsaddr := dataWordFuncName(n.X.Type()); needsaddr || isStaticCompositeLiteral(n.X) {
 			// Need a temp if we need to pass the address to the conversion function.
 			// We also process static composite literal node here, making a named static global
-			// whose address we can put directly in an interface (see OCONVIFACE case in walk).
+			// whose address we can put directly in an interface (see OCONVIFACE/OCONVIDATA case in walk).
 			n.X = o.addrTemp(n.X)
 		}
 		return n
 
 	case ir.OCONVNOP:
 		n := n.(*ir.ConvExpr)
-		if n.Type().IsKind(types.TUNSAFEPTR) && n.X.Type().IsKind(types.TUINTPTR) && (n.X.Op() == ir.OCALLFUNC || n.X.Op() == ir.OCALLINTER || n.X.Op() == ir.OCALLMETH) {
+		if n.X.Op() == ir.OCALLMETH {
+			base.FatalfAt(n.X.Pos(), "OCALLMETH missed by typecheck")
+		}
+		if n.Type().IsKind(types.TUNSAFEPTR) && n.X.Type().IsKind(types.TUINTPTR) && (n.X.Op() == ir.OCALLFUNC || n.X.Op() == ir.OCALLINTER) {
 			call := n.X.(*ir.CallExpr)
 			// When reordering unsafe.Pointer(f()) into a separate
 			// statement, the conversion and function call must stay
@@ -1261,9 +1232,12 @@
 		o.out = append(o.out, nif)
 		return r
 
+	case ir.OCALLMETH:
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+		panic("unreachable")
+
 	case ir.OCALLFUNC,
 		ir.OCALLINTER,
-		ir.OCALLMETH,
 		ir.OCAP,
 		ir.OCOMPLEX,
 		ir.OCOPY,
@@ -1275,7 +1249,7 @@
 		ir.OMAKESLICECOPY,
 		ir.ONEW,
 		ir.OREAL,
-		ir.ORECOVER,
+		ir.ORECOVERFP,
 		ir.OSTR2BYTES,
 		ir.OSTR2BYTESTMP,
 		ir.OSTR2RUNES:
@@ -1293,6 +1267,11 @@
 		}
 		return n
 
+	case ir.OINLCALL:
+		n := n.(*ir.InlinedCallExpr)
+		o.stmtList(n.Body)
+		return n.SingleResult()
+
 	case ir.OAPPEND:
 		// Check for append(x, make([]T, y)...) .
 		n := n.(*ir.CallExpr)
@@ -1327,11 +1306,11 @@
 		}
 		return n
 
-	case ir.OCALLPART:
+	case ir.OMETHVALUE:
 		n := n.(*ir.SelectorExpr)
 		n.X = o.expr(n.X, nil)
 		if n.Transient() {
-			t := typecheck.PartialCallType(n)
+			t := typecheck.MethodValueType(n)
 			n.Prealloc = o.newTemp(t, false)
 		}
 		return n
@@ -1498,313 +1477,6 @@
 	o.stmt(typecheck.Stmt(as))
 }
 
-var wrapGoDefer_prgen int
-
-// wrapGoDefer wraps the target of a "go" or "defer" statement with a
-// new "function with no arguments" closure. Specifically, it converts
-//
-//   defer f(x, y)
-//
-// to
-//
-//   x1, y1 := x, y
-//   defer func() { f(x1, y1) }()
-//
-// This is primarily to enable a quicker bringup of defers under the
-// new register ABI; by doing this conversion, we can simplify the
-// code in the runtime that invokes defers on the panic path.
-func (o *orderState) wrapGoDefer(n *ir.GoDeferStmt) {
-	call := n.Call
-
-	var callX ir.Node        // thing being called
-	var callArgs []ir.Node   // call arguments
-	var keepAlive []*ir.Name // KeepAlive list from call, if present
-
-	// A helper to recreate the call within the closure.
-	var mkNewCall func(pos src.XPos, op ir.Op, fun ir.Node, args []ir.Node) ir.Node
-
-	// Defer calls come in many shapes and sizes; not all of them
-	// are ir.CallExpr's. Examine the type to see what we're dealing with.
-	switch x := call.(type) {
-	case *ir.CallExpr:
-		callX = x.X
-		callArgs = x.Args
-		keepAlive = x.KeepAlive
-		mkNewCall = func(pos src.XPos, op ir.Op, fun ir.Node, args []ir.Node) ir.Node {
-			newcall := ir.NewCallExpr(pos, op, fun, args)
-			newcall.IsDDD = x.IsDDD
-			return ir.Node(newcall)
-		}
-	case *ir.UnaryExpr: // ex: OCLOSE
-		callArgs = []ir.Node{x.X}
-		mkNewCall = func(pos src.XPos, op ir.Op, fun ir.Node, args []ir.Node) ir.Node {
-			if len(args) != 1 {
-				panic("internal error, expecting single arg")
-			}
-			return ir.Node(ir.NewUnaryExpr(pos, op, args[0]))
-		}
-	case *ir.BinaryExpr: // ex: OCOPY
-		callArgs = []ir.Node{x.X, x.Y}
-		mkNewCall = func(pos src.XPos, op ir.Op, fun ir.Node, args []ir.Node) ir.Node {
-			if len(args) != 2 {
-				panic("internal error, expecting two args")
-			}
-			return ir.Node(ir.NewBinaryExpr(pos, op, args[0], args[1]))
-		}
-	default:
-		panic("unhandled op")
-	}
-
-	// No need to wrap if called func has no args, no receiver, and no results.
-	// However in the case of "defer func() { ... }()" we need to
-	// protect against the possibility of directClosureCall rewriting
-	// things so that the call does have arguments.
-	//
-	// Do wrap method calls (OCALLMETH, OCALLINTER), because it has
-	// a receiver.
-	//
-	// Also do wrap builtin functions, because they may be expanded to
-	// calls with arguments (e.g. ORECOVER).
-	//
-	// TODO: maybe not wrap if the called function has no arguments and
-	// only in-register results?
-	if len(callArgs) == 0 && call.Op() == ir.OCALLFUNC && callX.Type().NumResults() == 0 {
-		if c, ok := call.(*ir.CallExpr); ok && callX != nil && callX.Op() == ir.OCLOSURE {
-			cloFunc := callX.(*ir.ClosureExpr).Func
-			cloFunc.SetClosureCalled(false)
-			c.PreserveClosure = true
-		}
-		return
-	}
-
-	if c, ok := call.(*ir.CallExpr); ok {
-		// To simplify things, turn f(a, b, []T{c, d, e}...) back
-		// into f(a, b, c, d, e) -- when the final call is run through the
-		// type checker below, it will rebuild the proper slice literal.
-		undoVariadic(c)
-		callX = c.X
-		callArgs = c.Args
-	}
-
-	// This is set to true if the closure we're generating escapes
-	// (needs heap allocation).
-	cloEscapes := func() bool {
-		if n.Op() == ir.OGO {
-			// For "go", assume that all closures escape.
-			return true
-		}
-		// For defer, just use whatever result escape analysis
-		// has determined for the defer.
-		return n.Esc() != ir.EscNever
-	}()
-
-	// A helper for making a copy of an argument. Note that it is
-	// not safe to use o.copyExpr(arg) if we're putting a
-	// reference to the temp into the closure (as opposed to
-	// copying it in by value), since in the by-reference case we
-	// need a temporary whose lifetime extends to the end of the
-	// function (as opposed to being local to the current block or
-	// statement being ordered).
-	mkArgCopy := func(arg ir.Node) *ir.Name {
-		t := arg.Type()
-		byval := t.Size() <= 128 || cloEscapes
-		var argCopy *ir.Name
-		if byval {
-			argCopy = o.copyExpr(arg)
-		} else {
-			argCopy = typecheck.Temp(t)
-			o.append(ir.NewAssignStmt(base.Pos, argCopy, arg))
-		}
-		// The value of 128 below is meant to be consistent with code
-		// in escape analysis that picks byval/byaddr based on size.
-		argCopy.SetByval(byval)
-		return argCopy
-	}
-
-	// getUnsafeArg looks for an unsafe.Pointer arg that has been
-	// previously captured into the call's keepalive list, returning
-	// the name node for it if found.
-	getUnsafeArg := func(arg ir.Node) *ir.Name {
-		// Look for uintptr(unsafe.Pointer(name))
-		if arg.Op() != ir.OCONVNOP {
-			return nil
-		}
-		if !arg.Type().IsUintptr() {
-			return nil
-		}
-		if !arg.(*ir.ConvExpr).X.Type().IsUnsafePtr() {
-			return nil
-		}
-		arg = arg.(*ir.ConvExpr).X
-		argname, ok := arg.(*ir.Name)
-		if !ok {
-			return nil
-		}
-		for i := range keepAlive {
-			if argname == keepAlive[i] {
-				return argname
-			}
-		}
-		return nil
-	}
-
-	// Copy the arguments to the function into temps.
-	//
-	// For calls with uintptr(unsafe.Pointer(...)) args that are being
-	// kept alive (see code in (*orderState).call that does this), use
-	// the existing arg copy instead of creating a new copy.
-	unsafeArgs := make([]*ir.Name, len(callArgs))
-	origArgs := callArgs
-	var newNames []*ir.Name
-	for i := range callArgs {
-		arg := callArgs[i]
-		var argname *ir.Name
-		unsafeArgName := getUnsafeArg(arg)
-		if unsafeArgName != nil {
-			// arg has been copied already, use keepalive copy
-			argname = unsafeArgName
-			unsafeArgs[i] = unsafeArgName
-		} else {
-			argname = mkArgCopy(arg)
-		}
-		newNames = append(newNames, argname)
-	}
-
-	// Deal with cases where the function expression (what we're
-	// calling) is not a simple function symbol.
-	var fnExpr *ir.Name
-	var methSelectorExpr *ir.SelectorExpr
-	if callX != nil {
-		switch {
-		case callX.Op() == ir.ODOTMETH || callX.Op() == ir.ODOTINTER:
-			// Handle defer of a method call, e.g. "defer v.MyMethod(x, y)"
-			n := callX.(*ir.SelectorExpr)
-			n.X = mkArgCopy(n.X)
-			methSelectorExpr = n
-			if callX.Op() == ir.ODOTINTER {
-				// Currently for "defer i.M()" if i is nil it panics at the
-				// point of defer statement, not when deferred function is called.
-				// (I think there is an issue discussing what is the intended
-				// behavior but I cannot find it.)
-				// We need to do the nil check outside of the wrapper.
-				tab := typecheck.Expr(ir.NewUnaryExpr(base.Pos, ir.OITAB, n.X))
-				c := ir.NewUnaryExpr(n.Pos(), ir.OCHECKNIL, tab)
-				c.SetTypecheck(1)
-				o.append(c)
-			}
-		case !(callX.Op() == ir.ONAME && callX.(*ir.Name).Class == ir.PFUNC):
-			// Deal with "defer returnsafunc()(x, y)" (for
-			// example) by copying the callee expression.
-			fnExpr = mkArgCopy(callX)
-			if callX.Op() == ir.OCLOSURE {
-				// For "defer func(...)", in addition to copying the
-				// closure into a temp, mark it as no longer directly
-				// called.
-				callX.(*ir.ClosureExpr).Func.SetClosureCalled(false)
-			}
-		}
-	}
-
-	// Create a new no-argument function that we'll hand off to defer.
-	var noFuncArgs []*ir.Field
-	noargst := ir.NewFuncType(base.Pos, nil, noFuncArgs, nil)
-	wrapGoDefer_prgen++
-	outerfn := ir.CurFunc
-	wrapname := fmt.Sprintf("%v·dwrap·%d", outerfn, wrapGoDefer_prgen)
-	sym := types.LocalPkg.Lookup(wrapname)
-	fn := typecheck.DeclFunc(sym, noargst)
-	fn.SetIsHiddenClosure(true)
-	fn.SetWrapper(true)
-
-	// helper for capturing reference to a var declared in an outer scope.
-	capName := func(pos src.XPos, fn *ir.Func, n *ir.Name) *ir.Name {
-		t := n.Type()
-		cv := ir.CaptureName(pos, fn, n)
-		cv.SetType(t)
-		return typecheck.Expr(cv).(*ir.Name)
-	}
-
-	// Call args (x1, y1) need to be captured as part of the newly
-	// created closure.
-	newCallArgs := []ir.Node{}
-	for i := range newNames {
-		var arg ir.Node
-		arg = capName(callArgs[i].Pos(), fn, newNames[i])
-		if unsafeArgs[i] != nil {
-			arg = ir.NewConvExpr(arg.Pos(), origArgs[i].Op(), origArgs[i].Type(), arg)
-		}
-		newCallArgs = append(newCallArgs, arg)
-	}
-	// Also capture the function or method expression (if needed) into
-	// the closure.
-	if fnExpr != nil {
-		callX = capName(callX.Pos(), fn, fnExpr)
-	}
-	if methSelectorExpr != nil {
-		methSelectorExpr.X = capName(callX.Pos(), fn, methSelectorExpr.X.(*ir.Name))
-	}
-	ir.FinishCaptureNames(n.Pos(), outerfn, fn)
-
-	// This flags a builtin as opposed to a regular call.
-	irregular := (call.Op() != ir.OCALLFUNC &&
-		call.Op() != ir.OCALLMETH &&
-		call.Op() != ir.OCALLINTER)
-
-	// Construct new function body:  f(x1, y1)
-	op := ir.OCALL
-	if irregular {
-		op = call.Op()
-	}
-	newcall := mkNewCall(call.Pos(), op, callX, newCallArgs)
-
-	// Type-check the result.
-	if !irregular {
-		typecheck.Call(newcall.(*ir.CallExpr))
-	} else {
-		typecheck.Stmt(newcall)
-	}
-
-	// Finalize body, register function on the main decls list.
-	fn.Body = []ir.Node{newcall}
-	typecheck.FinishFuncBody()
-	typecheck.Func(fn)
-	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
-
-	// Create closure expr
-	clo := ir.NewClosureExpr(n.Pos(), fn)
-	fn.OClosure = clo
-	clo.SetType(fn.Type())
-
-	// Set escape properties for closure.
-	if n.Op() == ir.OGO {
-		// For "go", assume that the closure is going to escape
-		// (with an exception for the runtime, which doesn't
-		// permit heap-allocated closures).
-		if base.Ctxt.Pkgpath != "runtime" {
-			clo.SetEsc(ir.EscHeap)
-		}
-	} else {
-		// For defer, just use whatever result escape analysis
-		// has determined for the defer.
-		if n.Esc() == ir.EscNever {
-			clo.SetTransient(true)
-			clo.SetEsc(ir.EscNone)
-		}
-	}
-
-	// Create new top level call to closure over argless function.
-	topcall := ir.NewCallExpr(n.Pos(), ir.OCALL, clo, []ir.Node{})
-	typecheck.Call(topcall)
-
-	// Tag the call to insure that directClosureCall doesn't undo our work.
-	topcall.PreserveClosure = true
-
-	fn.SetClosureCalled(false)
-
-	// Finally, point the defer statement at the newly generated call.
-	n.Call = topcall
-}
-
 // isFuncPCIntrinsic returns whether n is a direct call of internal/abi.FuncPCABIxxx functions.
 func isFuncPCIntrinsic(n *ir.CallExpr) bool {
 	if n.Op() != ir.OCALLFUNC || n.X.Op() != ir.ONAME {
diff --git a/src/cmd/compile/internal/walk/stmt.go b/src/cmd/compile/internal/walk/stmt.go
index 0bf7668..4581bca 100644
--- a/src/cmd/compile/internal/walk/stmt.go
+++ b/src/cmd/compile/internal/walk/stmt.go
@@ -7,7 +7,6 @@
 import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
-	"cmd/compile/internal/typecheck"
 )
 
 // The result of walkStmt MUST be assigned back to n, e.g.
@@ -41,7 +40,6 @@
 		ir.OAS2MAPR,
 		ir.OCLOSE,
 		ir.OCOPY,
-		ir.OCALLMETH,
 		ir.OCALLINTER,
 		ir.OCALL,
 		ir.OCALLFUNC,
@@ -50,7 +48,7 @@
 		ir.OPRINT,
 		ir.OPRINTN,
 		ir.OPANIC,
-		ir.ORECOVER,
+		ir.ORECOVERFP,
 		ir.OGETG:
 		if n.Typecheck() == 0 {
 			base.Fatalf("missing typecheck: %+v", n)
@@ -187,33 +185,28 @@
 	return n
 }
 
+// validGoDeferCall reports whether call is a valid call to appear in
+// a go or defer statement; that is, whether it's a regular function
+// call without arguments or results.
+func validGoDeferCall(call ir.Node) bool {
+	if call, ok := call.(*ir.CallExpr); ok && call.Op() == ir.OCALLFUNC && len(call.KeepAlive) == 0 {
+		sig := call.X.Type()
+		return sig.NumParams()+sig.NumResults() == 0
+	}
+	return false
+}
+
 // walkGoDefer walks an OGO or ODEFER node.
 func walkGoDefer(n *ir.GoDeferStmt) ir.Node {
-	var init ir.Nodes
-	switch call := n.Call; call.Op() {
-	case ir.OPRINT, ir.OPRINTN:
-		call := call.(*ir.CallExpr)
-		n.Call = wrapCall(call, &init)
-
-	case ir.ODELETE:
-		call := call.(*ir.CallExpr)
-		n.Call = wrapCall(call, &init)
-
-	case ir.OCOPY:
-		call := call.(*ir.BinaryExpr)
-		n.Call = walkCopy(call, &init, true)
-
-	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
-		call := call.(*ir.CallExpr)
-		if len(call.KeepAlive) > 0 {
-			n.Call = wrapCall(call, &init)
-		} else {
-			n.Call = walkExpr(call, &init)
-		}
-
-	default:
-		n.Call = walkExpr(call, &init)
+	if !validGoDeferCall(n.Call) {
+		base.FatalfAt(n.Pos(), "invalid %v call: %v", n.Op(), n.Call)
 	}
+
+	var init ir.Nodes
+
+	call := n.Call.(*ir.CallExpr)
+	call.X = walkExpr(call.X, &init)
+
 	if len(init) > 0 {
 		init.Append(n)
 		return ir.NewBlockStmt(n.Pos(), init)
@@ -228,110 +221,3 @@
 	walkStmtList(n.Else)
 	return n
 }
-
-// Rewrite
-//	go builtin(x, y, z)
-// into
-//	go func(a1, a2, a3) {
-//		builtin(a1, a2, a3)
-//	}(x, y, z)
-// for print, println, and delete.
-//
-// Rewrite
-//	go f(x, y, uintptr(unsafe.Pointer(z)))
-// into
-//	go func(a1, a2, a3) {
-//		f(a1, a2, uintptr(a3))
-//	}(x, y, unsafe.Pointer(z))
-// for function contains unsafe-uintptr arguments.
-
-var wrapCall_prgen int
-
-// The result of wrapCall MUST be assigned back to n, e.g.
-// 	n.Left = wrapCall(n.Left, init)
-func wrapCall(n *ir.CallExpr, init *ir.Nodes) ir.Node {
-	if len(n.Init()) != 0 {
-		walkStmtList(n.Init())
-		init.Append(ir.TakeInit(n)...)
-	}
-
-	isBuiltinCall := n.Op() != ir.OCALLFUNC && n.Op() != ir.OCALLMETH && n.Op() != ir.OCALLINTER
-
-	// Turn f(a, b, []T{c, d, e}...) back into f(a, b, c, d, e).
-	if !isBuiltinCall && n.IsDDD {
-		undoVariadic(n)
-	}
-
-	wrapArgs := n.Args
-	// If there's a receiver argument, it needs to be passed through the wrapper too.
-	if n.Op() == ir.OCALLMETH || n.Op() == ir.OCALLINTER {
-		recv := n.X.(*ir.SelectorExpr).X
-		wrapArgs = append([]ir.Node{recv}, wrapArgs...)
-	}
-
-	// origArgs keeps track of what argument is uintptr-unsafe/unsafe-uintptr conversion.
-	origArgs := make([]ir.Node, len(wrapArgs))
-	var funcArgs []*ir.Field
-	for i, arg := range wrapArgs {
-		s := typecheck.LookupNum("a", i)
-		if !isBuiltinCall && arg.Op() == ir.OCONVNOP && arg.Type().IsUintptr() && arg.(*ir.ConvExpr).X.Type().IsUnsafePtr() {
-			origArgs[i] = arg
-			arg = arg.(*ir.ConvExpr).X
-			wrapArgs[i] = arg
-		}
-		funcArgs = append(funcArgs, ir.NewField(base.Pos, s, nil, arg.Type()))
-	}
-	t := ir.NewFuncType(base.Pos, nil, funcArgs, nil)
-
-	wrapCall_prgen++
-	sym := typecheck.LookupNum("wrap·", wrapCall_prgen)
-	fn := typecheck.DeclFunc(sym, t)
-
-	args := ir.ParamNames(t.Type())
-	for i, origArg := range origArgs {
-		if origArg == nil {
-			continue
-		}
-		args[i] = ir.NewConvExpr(base.Pos, origArg.Op(), origArg.Type(), args[i])
-	}
-	if n.Op() == ir.OCALLMETH || n.Op() == ir.OCALLINTER {
-		// Move wrapped receiver argument back to its appropriate place.
-		recv := typecheck.Expr(args[0])
-		n.X.(*ir.SelectorExpr).X = recv
-		args = args[1:]
-	}
-	call := ir.NewCallExpr(base.Pos, n.Op(), n.X, args)
-	if !isBuiltinCall {
-		call.SetOp(ir.OCALL)
-		call.IsDDD = n.IsDDD
-	}
-	fn.Body = []ir.Node{call}
-
-	typecheck.FinishFuncBody()
-
-	typecheck.Func(fn)
-	typecheck.Stmts(fn.Body)
-	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
-
-	call = ir.NewCallExpr(base.Pos, ir.OCALL, fn.Nname, wrapArgs)
-	return walkExpr(typecheck.Stmt(call), init)
-}
-
-// undoVariadic turns a call to a variadic function of the form
-//
-//      f(a, b, []T{c, d, e}...)
-//
-// back into
-//
-//      f(a, b, c, d, e)
-//
-func undoVariadic(call *ir.CallExpr) {
-	if call.IsDDD {
-		last := len(call.Args) - 1
-		if va := call.Args[last]; va.Op() == ir.OSLICELIT {
-			va := va.(*ir.CompLitExpr)
-			call.Args = append(call.Args[:last], va.List...)
-			call.IsDDD = false
-		}
-	}
-}
diff --git a/src/cmd/compile/internal/walk/switch.go b/src/cmd/compile/internal/walk/switch.go
index 162de01..3705c5b 100644
--- a/src/cmd/compile/internal/walk/switch.go
+++ b/src/cmd/compile/internal/walk/switch.go
@@ -360,10 +360,10 @@
 			}
 
 			if singleType != nil && singleType.IsInterface() {
-				s.Add(ncase.Pos(), n1.Type(), caseVar, jmp)
+				s.Add(ncase.Pos(), n1, caseVar, jmp)
 				caseVarInitialized = true
 			} else {
-				s.Add(ncase.Pos(), n1.Type(), nil, jmp)
+				s.Add(ncase.Pos(), n1, nil, jmp)
 			}
 		}
 
@@ -377,6 +377,17 @@
 				}
 				val = ifaceData(ncase.Pos(), s.facename, singleType)
 			}
+			if len(ncase.List) == 1 && ncase.List[0].Op() == ir.ODYNAMICTYPE {
+				dt := ncase.List[0].(*ir.DynamicType)
+				x := ir.NewDynamicTypeAssertExpr(ncase.Pos(), ir.ODYNAMICDOTTYPE, val, dt.X)
+				if dt.ITab != nil {
+					// TODO: make ITab a separate field in DynamicTypeAssertExpr?
+					x.T = dt.ITab
+				}
+				x.SetType(caseVar.Type())
+				x.SetTypecheck(1)
+				val = x
+			}
 			l := []ir.Node{
 				ir.NewDecl(ncase.Pos(), ir.ODCL, caseVar),
 				ir.NewAssignStmt(ncase.Pos(), caseVar, val),
@@ -446,7 +457,8 @@
 	body ir.Nodes
 }
 
-func (s *typeSwitch) Add(pos src.XPos, typ *types.Type, caseVar *ir.Name, jmp ir.Node) {
+func (s *typeSwitch) Add(pos src.XPos, n1 ir.Node, caseVar *ir.Name, jmp ir.Node) {
+	typ := n1.Type()
 	var body ir.Nodes
 	if caseVar != nil {
 		l := []ir.Node{
@@ -462,9 +474,25 @@
 	// cv, ok = iface.(type)
 	as := ir.NewAssignListStmt(pos, ir.OAS2, nil, nil)
 	as.Lhs = []ir.Node{caseVar, s.okname} // cv, ok =
-	dot := ir.NewTypeAssertExpr(pos, s.facename, nil)
-	dot.SetType(typ) // iface.(type)
-	as.Rhs = []ir.Node{dot}
+	switch n1.Op() {
+	case ir.OTYPE:
+		// Static type assertion (non-generic)
+		dot := ir.NewTypeAssertExpr(pos, s.facename, nil)
+		dot.SetType(typ) // iface.(type)
+		as.Rhs = []ir.Node{dot}
+	case ir.ODYNAMICTYPE:
+		// Dynamic type assertion (generic)
+		dt := n1.(*ir.DynamicType)
+		dot := ir.NewDynamicTypeAssertExpr(pos, ir.ODYNAMICDOTTYPE, s.facename, dt.X)
+		if dt.ITab != nil {
+			dot.T = dt.ITab
+		}
+		dot.SetType(typ)
+		dot.SetTypecheck(1)
+		as.Rhs = []ir.Node{dot}
+	default:
+		base.Fatalf("unhandled type case %s", n1.Op())
+	}
 	appendWalkStmt(&body, as)
 
 	// if ok { goto label }
@@ -473,9 +501,10 @@
 	nif.Body = []ir.Node{jmp}
 	body.Append(nif)
 
-	if !typ.IsInterface() {
+	if n1.Op() == ir.OTYPE && !typ.IsInterface() {
+		// Defer static, noninterface cases so they can be binary searched by hash.
 		s.clauses = append(s.clauses, typeClause{
-			hash: types.TypeHash(typ),
+			hash: types.TypeHash(n1.Type()),
 			body: body,
 		})
 		return
diff --git a/src/cmd/compile/internal/walk/walk.go b/src/cmd/compile/internal/walk/walk.go
index 26da6e3..6551fe7 100644
--- a/src/cmd/compile/internal/walk/walk.go
+++ b/src/cmd/compile/internal/walk/walk.go
@@ -113,8 +113,7 @@
 		base.Fatalf("vmkcall %v needs %v args got %v", fn, n, len(va))
 	}
 
-	call := ir.NewCallExpr(base.Pos, ir.OCALL, fn, va)
-	typecheck.Call(call)
+	call := typecheck.Call(base.Pos, fn, va, false).(*ir.CallExpr)
 	call.SetType(t)
 	return walkExpr(call, init).(*ir.CallExpr)
 }
@@ -308,7 +307,7 @@
 		default:
 			base.FatalfAt(n.Pos(), "mayCall %+v", n)
 
-		case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER,
+		case ir.OCALLFUNC, ir.OCALLINTER,
 			ir.OUNSAFEADD, ir.OUNSAFESLICE:
 			return true
 
@@ -343,7 +342,7 @@
 			ir.OCAP, ir.OIMAG, ir.OLEN, ir.OREAL,
 			ir.OCONVNOP, ir.ODOT,
 			ir.OCFUNC, ir.OIDATA, ir.OITAB, ir.OSPTR,
-			ir.OBYTES2STRTMP, ir.OGETG, ir.OSLICEHEADER:
+			ir.OBYTES2STRTMP, ir.OGETG, ir.OGETCALLERPC, ir.OGETCALLERSP, ir.OSLICEHEADER:
 			// ok: operations that don't require function calls.
 			// Expand as needed.
 		}
diff --git a/src/cmd/compile/internal/wasm/ssa.go b/src/cmd/compile/internal/wasm/ssa.go
index 31b0901..0b2ca3f 100644
--- a/src/cmd/compile/internal/wasm/ssa.go
+++ b/src/cmd/compile/internal/wasm/ssa.go
@@ -24,7 +24,6 @@
 
 	arch.ZeroRange = zeroRange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
@@ -126,7 +125,11 @@
 	case ssa.OpWasmLoweredStaticCall, ssa.OpWasmLoweredClosureCall, ssa.OpWasmLoweredInterCall:
 		s.PrepareCall(v)
 		if call, ok := v.Aux.(*ssa.AuxCall); ok && call.Fn == ir.Syms.Deferreturn {
-			// add a resume point before call to deferreturn so it can be called again via jmpdefer
+			// The runtime needs to inject jumps to
+			// deferreturn calls using the address in
+			// _func.deferreturn. Hence, the call to
+			// deferreturn must itself be a resumption
+			// point so it gets a target PC.
 			s.Prog(wasm.ARESUMEPOINT)
 		}
 		if v.Op == ssa.OpWasmLoweredClosureCall {
diff --git a/src/cmd/compile/internal/x86/galign.go b/src/cmd/compile/internal/x86/galign.go
index 00a20e4..5565bd3 100644
--- a/src/cmd/compile/internal/x86/galign.go
+++ b/src/cmd/compile/internal/x86/galign.go
@@ -34,7 +34,6 @@
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 }
diff --git a/src/cmd/go.mod b/src/cmd/go.mod
index cd03968e..ccfff09 100644
--- a/src/cmd/go.mod
+++ b/src/cmd/go.mod
@@ -1,6 +1,6 @@
 module cmd
 
-go 1.17
+go 1.18
 
 require (
 	github.com/google/pprof v0.0.0-20210506205249-923b5ab0fc1a
@@ -10,6 +10,6 @@
 	golang.org/x/mod v0.4.3-0.20210608190319-0f08993efd8a
 	golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744 // indirect
 	golang.org/x/term v0.0.0-20210503060354-a79de5458b56
-	golang.org/x/tools v0.1.2-0.20210519160823-49064d2332f9
+	golang.org/x/tools v0.1.6-0.20210809225032-337cebd2c151
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 )
diff --git a/src/cmd/go.sum b/src/cmd/go.sum
index d728aca..f4d41f0 100644
--- a/src/cmd/go.sum
+++ b/src/cmd/go.sum
@@ -5,41 +5,18 @@
 github.com/google/pprof v0.0.0-20210506205249-923b5ab0fc1a/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639 h1:mV02weKRL81bEnm8A0HT1/CAelMQDBuQIfLw8n+d6xI=
 github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
-github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 golang.org/x/arch v0.0.0-20210502124803-cbf565b21d1e h1:pv3V0NlNSh5Q6AX/StwGLBjcLS7UN4m4Gq+V+uSecqM=
 golang.org/x/arch v0.0.0-20210502124803-cbf565b21d1e/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e h1:8foAy0aoO5GkqCvAEJ4VC4P3zksTg4X4aJCDpZzmgQI=
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e/go.mod h1:P+XmwS30IXTQdn5tA2iutPOUgjI07+tq3H3K9MVA1s8=
-golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.3-0.20210608190319-0f08993efd8a h1:e8qnjKz4EE6OjRki9wTadWSIogINvq10sMcuBRORxMY=
 golang.org/x/mod v0.4.3-0.20210608190319-0f08993efd8a/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
-golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
-golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744 h1:yhBbb4IRs2HS9PPlAg6DMC6mUOKexJBNsLf4Z+6En1Q=
 golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210503060354-a79de5458b56 h1:b8jxX3zqjpqb2LklXPzKSGJhzyxCOZSz8ncv8Nv+y7w=
 golang.org/x/term v0.0.0-20210503060354-a79de5458b56/go.mod h1:tfny5GFUkzUvx4ps4ajbZsCe5lw1metzhBm9T3x7oIY=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.1.2-0.20210519160823-49064d2332f9 h1:2XlR/j4I4xz5GQZI7zBjqTfezYyRIE2jD5IMousB2rg=
-golang.org/x/tools v0.1.2-0.20210519160823-49064d2332f9/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/tools v0.1.6-0.20210809225032-337cebd2c151 h1:jHjT6WuVKEMzjJgrS1+r1wk54oxwqumUnvtn0QZXyXE=
+golang.org/x/tools v0.1.6-0.20210809225032-337cebd2c151/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-rsc.io/pdf v0.1.1/go.mod h1:n8OzWcQ6Sp37PL01nO98y4iUCRdTGarVfzxY20ICaU4=
diff --git a/src/cmd/go/go_test.go b/src/cmd/go/go_test.go
index 6ce2765..b13191f 100644
--- a/src/cmd/go/go_test.go
+++ b/src/cmd/go/go_test.go
@@ -806,7 +806,9 @@
 		"src/internal/abi",
 		"src/internal/bytealg",
 		"src/internal/cpu",
+		"src/internal/goarch",
 		"src/internal/goexperiment",
+		"src/internal/goos",
 		"src/math/bits",
 		"src/unsafe",
 		filepath.Join("pkg", runtime.GOOS+"_"+runtime.GOARCH),
diff --git a/src/cmd/go/internal/work/gc.go b/src/cmd/go/internal/work/gc.go
index 85da4f8..2ae908b 100644
--- a/src/cmd/go/internal/work/gc.go
+++ b/src/cmd/go/internal/work/gc.go
@@ -29,6 +29,18 @@
 // The 'path' used for GOROOT_FINAL when -trimpath is specified
 const trimPathGoRootFinal = "go"
 
+var runtimePackages = map[string]struct{}{
+	"internal/abi":            struct{}{},
+	"internal/bytealg":        struct{}{},
+	"internal/cpu":            struct{}{},
+	"internal/goarch":         struct{}{},
+	"internal/goos":           struct{}{},
+	"runtime":                 struct{}{},
+	"runtime/internal/atomic": struct{}{},
+	"runtime/internal/math":   struct{}{},
+	"runtime/internal/sys":    struct{}{},
+}
+
 // The Go toolchain.
 
 type gcToolchain struct{}
@@ -88,11 +100,8 @@
 	if p.Standard {
 		gcargs = append(gcargs, "-std")
 	}
-	compilingRuntime := p.Standard && (p.ImportPath == "runtime" || strings.HasPrefix(p.ImportPath, "runtime/internal"))
-	// The runtime package imports a couple of general internal packages.
-	if p.Standard && (p.ImportPath == "internal/cpu" || p.ImportPath == "internal/bytealg" || p.ImportPath == "internal/abi") {
-		compilingRuntime = true
-	}
+	_, compilingRuntime := runtimePackages[p.ImportPath]
+	compilingRuntime = compilingRuntime && p.Standard
 	if compilingRuntime {
 		// runtime compiles with a special gc flag to check for
 		// memory allocations that are invalid in the runtime package,
diff --git a/src/cmd/gofmt/gofmt_test.go b/src/cmd/gofmt/gofmt_test.go
index f0d3f878..9ef7676 100644
--- a/src/cmd/gofmt/gofmt_test.go
+++ b/src/cmd/gofmt/gofmt_test.go
@@ -54,8 +54,6 @@
 	return ""
 }
 
-var typeParamsEnabled = false
-
 func runTest(t *testing.T, in, out string) {
 	// process flags
 	*simplifyAST = false
@@ -78,11 +76,6 @@
 		case "-stdin":
 			// fake flag - pretend input is from stdin
 			stdin = true
-		case "-G":
-			// fake flag - test is for generic code
-			if !typeParamsEnabled {
-				return
-			}
 		default:
 			t.Errorf("unrecognized flag name: %s", name)
 		}
diff --git a/src/cmd/gofmt/testdata/typeparams.golden b/src/cmd/gofmt/testdata/typeparams.golden
index 35f08d1..f71bd13 100644
--- a/src/cmd/gofmt/testdata/typeparams.golden
+++ b/src/cmd/gofmt/testdata/typeparams.golden
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//gofmt -G
+//gofmt
 
 package typeparams
 
diff --git a/src/cmd/gofmt/testdata/typeparams.input b/src/cmd/gofmt/testdata/typeparams.input
index 7f3212c..5d4c53d 100644
--- a/src/cmd/gofmt/testdata/typeparams.input
+++ b/src/cmd/gofmt/testdata/typeparams.input
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//gofmt -G
+//gofmt
 
 package typeparams
 
diff --git a/src/cmd/internal/dwarf/dwarf.go b/src/cmd/internal/dwarf/dwarf.go
index ec441c2..860c7d6 100644
--- a/src/cmd/internal/dwarf/dwarf.go
+++ b/src/cmd/internal/dwarf/dwarf.go
@@ -1266,7 +1266,7 @@
 // its corresponding 'abstract' DIE (containing location-independent
 // attributes such as name, type, etc). Inlined subroutine DIEs can
 // have other inlined subroutine DIEs as children.
-func putInlinedFunc(ctxt Context, s *FnState, callersym Sym, callIdx int) error {
+func putInlinedFunc(ctxt Context, s *FnState, callIdx int) error {
 	ic := s.InlCalls.Calls[callIdx]
 	callee := ic.AbsFunSym
 
@@ -1277,7 +1277,7 @@
 	Uleb128put(ctxt, s.Info, int64(abbrev))
 
 	if logDwarf {
-		ctxt.Logf("putInlinedFunc(caller=%v,callee=%v,abbrev=%d)\n", callersym, callee, abbrev)
+		ctxt.Logf("putInlinedFunc(callee=%v,abbrev=%d)\n", callee, abbrev)
 	}
 
 	// Abstract origin.
@@ -1312,8 +1312,7 @@
 
 	// Children of this inline.
 	for _, sib := range inlChildren(callIdx, &s.InlCalls) {
-		absfn := s.InlCalls.Calls[sib].AbsFunSym
-		err := putInlinedFunc(ctxt, s, absfn, sib)
+		err := putInlinedFunc(ctxt, s, sib)
 		if err != nil {
 			return err
 		}
@@ -1354,8 +1353,7 @@
 
 	// Inlined subroutines.
 	for _, sib := range inlChildren(-1, &s.InlCalls) {
-		absfn := s.InlCalls.Calls[sib].AbsFunSym
-		err := putInlinedFunc(ctxt, s, absfn, sib)
+		err := putInlinedFunc(ctxt, s, sib)
 		if err != nil {
 			return err
 		}
@@ -1402,8 +1400,7 @@
 
 	// Inlined subroutines.
 	for _, sib := range inlChildren(-1, &s.InlCalls) {
-		absfn := s.InlCalls.Calls[sib].AbsFunSym
-		err := putInlinedFunc(ctxt, s, absfn, sib)
+		err := putInlinedFunc(ctxt, s, sib)
 		if err != nil {
 			return err
 		}
diff --git a/src/cmd/internal/goobj/builtinlist.go b/src/cmd/internal/goobj/builtinlist.go
index 9f24813..608c0d7 100644
--- a/src/cmd/internal/goobj/builtinlist.go
+++ b/src/cmd/internal/goobj/builtinlist.go
@@ -33,6 +33,7 @@
 	{"runtime.goPanicSlice3BU", 1},
 	{"runtime.goPanicSlice3C", 1},
 	{"runtime.goPanicSlice3CU", 1},
+	{"runtime.goPanicSliceConvert", 1},
 	{"runtime.printbool", 1},
 	{"runtime.printfloat", 1},
 	{"runtime.printint", 1},
@@ -129,6 +130,8 @@
 	{"runtime.makeslice64", 1},
 	{"runtime.makeslicecopy", 1},
 	{"runtime.growslice", 1},
+	{"runtime.unsafeslice", 1},
+	{"runtime.unsafeslice64", 1},
 	{"runtime.memmove", 1},
 	{"runtime.memclrNoHeapPointers", 1},
 	{"runtime.memclrHasPointers", 1},
@@ -203,7 +206,9 @@
 	{"runtime.newproc", 1},
 	{"runtime.panicoverflow", 1},
 	{"runtime.sigpanic", 1},
-	{"runtime.gcWriteBarrier", 0},
+	{"runtime.gcWriteBarrier", 1},
+	{"runtime.duffzero", 1},
+	{"runtime.duffcopy", 1},
 	{"runtime.morestack", 0},
 	{"runtime.morestackc", 0},
 	{"runtime.morestack_noctxt", 0},
diff --git a/src/cmd/internal/goobj/mkbuiltin.go b/src/cmd/internal/goobj/mkbuiltin.go
index 18b9695..c9995fc 100644
--- a/src/cmd/internal/goobj/mkbuiltin.go
+++ b/src/cmd/internal/goobj/mkbuiltin.go
@@ -151,7 +151,9 @@
 	{"sigpanic", 1},
 
 	// compiler backend inserted calls
-	{"gcWriteBarrier", 0}, // asm function, ABI0
+	{"gcWriteBarrier", 1},
+	{"duffzero", 1},
+	{"duffcopy", 1},
 
 	// assembler backend inserted calls
 	{"morestack", 0},        // asm function, ABI0
diff --git a/src/cmd/internal/obj/arm/asm5.go b/src/cmd/internal/obj/arm/asm5.go
index ccf5f9e..7b16827 100644
--- a/src/cmd/internal/obj/arm/asm5.go
+++ b/src/cmd/internal/obj/arm/asm5.go
@@ -355,11 +355,10 @@
 var xcmp [C_GOK + 1][C_GOK + 1]bool
 
 var (
-	deferreturn *obj.LSym
-	symdiv      *obj.LSym
-	symdivu     *obj.LSym
-	symmod      *obj.LSym
-	symmodu     *obj.LSym
+	symdiv  *obj.LSym
+	symdivu *obj.LSym
+	symmod  *obj.LSym
+	symmodu *obj.LSym
 )
 
 // Note about encoding: Prog.scond holds the condition encoding,
@@ -1219,8 +1218,6 @@
 		return
 	}
 
-	deferreturn = ctxt.LookupABI("runtime.deferreturn", obj.ABIInternal)
-
 	symdiv = ctxt.Lookup("runtime._div")
 	symdivu = ctxt.Lookup("runtime._divu")
 	symmod = ctxt.Lookup("runtime._mod")
diff --git a/src/cmd/internal/obj/arm64/obj7.go b/src/cmd/internal/obj/arm64/obj7.go
index e41fb3b..31b7c43 100644
--- a/src/cmd/internal/obj/arm64/obj7.go
+++ b/src/cmd/internal/obj/arm64/obj7.go
@@ -52,7 +52,7 @@
 }
 
 func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
-	// MOV	g_stackguard(g), R1
+	// MOV	g_stackguard(g), RT1
 	p = obj.Appendp(p, c.newprog)
 
 	p.As = AMOVD
@@ -63,7 +63,7 @@
 		p.From.Offset = 3 * int64(c.ctxt.Arch.PtrSize) // G.stackguard1
 	}
 	p.To.Type = obj.TYPE_REG
-	p.To.Reg = REG_R1
+	p.To.Reg = REGRT1
 
 	// Mark the stack bound check and morestack call async nonpreemptible.
 	// If we get preempted here, when resumed the preemption request is
@@ -74,25 +74,25 @@
 	q := (*obj.Prog)(nil)
 	if framesize <= objabi.StackSmall {
 		// small stack: SP < stackguard
-		//	MOV	SP, R2
-		//	CMP	stackguard, R2
+		//	MOV	SP, RT2
+		//	CMP	stackguard, RT2
 		p = obj.Appendp(p, c.newprog)
 
 		p.As = AMOVD
 		p.From.Type = obj.TYPE_REG
 		p.From.Reg = REGSP
 		p.To.Type = obj.TYPE_REG
-		p.To.Reg = REG_R2
+		p.To.Reg = REGRT2
 
 		p = obj.Appendp(p, c.newprog)
 		p.As = ACMP
 		p.From.Type = obj.TYPE_REG
-		p.From.Reg = REG_R1
-		p.Reg = REG_R2
+		p.From.Reg = REGRT1
+		p.Reg = REGRT2
 	} else if framesize <= objabi.StackBig {
 		// large stack: SP-framesize < stackguard-StackSmall
-		//	SUB	$(framesize-StackSmall), SP, R2
-		//	CMP	stackguard, R2
+		//	SUB	$(framesize-StackSmall), SP, RT2
+		//	CMP	stackguard, RT2
 		p = obj.Appendp(p, c.newprog)
 
 		p.As = ASUB
@@ -100,13 +100,13 @@
 		p.From.Offset = int64(framesize) - objabi.StackSmall
 		p.Reg = REGSP
 		p.To.Type = obj.TYPE_REG
-		p.To.Reg = REG_R2
+		p.To.Reg = REGRT2
 
 		p = obj.Appendp(p, c.newprog)
 		p.As = ACMP
 		p.From.Type = obj.TYPE_REG
-		p.From.Reg = REG_R1
-		p.Reg = REG_R2
+		p.From.Reg = REGRT1
+		p.Reg = REGRT2
 	} else {
 		// Such a large stack we need to protect against underflow.
 		// The runtime guarantees SP > objabi.StackBig, but
@@ -115,10 +115,10 @@
 		// stack guard to incorrectly succeed. We explicitly
 		// guard against underflow.
 		//
-		//	SUBS	$(framesize-StackSmall), SP, R2
+		//	SUBS	$(framesize-StackSmall), SP, RT2
 		//	// On underflow, jump to morestack
 		//	BLO	label_of_call_to_morestack
-		//	CMP	stackguard, R2
+		//	CMP	stackguard, RT2
 
 		p = obj.Appendp(p, c.newprog)
 		p.As = ASUBS
@@ -126,7 +126,7 @@
 		p.From.Offset = int64(framesize) - objabi.StackSmall
 		p.Reg = REGSP
 		p.To.Type = obj.TYPE_REG
-		p.To.Reg = REG_R2
+		p.To.Reg = REGRT2
 
 		p = obj.Appendp(p, c.newprog)
 		q = p
@@ -136,8 +136,8 @@
 		p = obj.Appendp(p, c.newprog)
 		p.As = ACMP
 		p.From.Type = obj.TYPE_REG
-		p.From.Reg = REG_R1
-		p.Reg = REG_R2
+		p.From.Reg = REGRT1
+		p.Reg = REGRT2
 	}
 
 	// BLS	do-morestack
@@ -161,17 +161,20 @@
 	pcdata := c.ctxt.EmitEntryStackMap(c.cursym, spfix, c.newprog)
 	pcdata = c.ctxt.StartUnsafePoint(pcdata, c.newprog)
 
+	if q != nil {
+		q.To.SetTarget(pcdata)
+	}
+	bls.To.SetTarget(pcdata)
+
+	spill := c.cursym.Func().SpillRegisterArgs(pcdata, c.newprog)
+
 	// MOV	LR, R3
-	movlr := obj.Appendp(pcdata, c.newprog)
+	movlr := obj.Appendp(spill, c.newprog)
 	movlr.As = AMOVD
 	movlr.From.Type = obj.TYPE_REG
 	movlr.From.Reg = REGLINK
 	movlr.To.Type = obj.TYPE_REG
 	movlr.To.Reg = REG_R3
-	if q != nil {
-		q.To.SetTarget(movlr)
-	}
-	bls.To.SetTarget(movlr)
 
 	debug := movlr
 	if false {
@@ -196,7 +199,8 @@
 	}
 	call.To.Sym = c.ctxt.Lookup(morestack)
 
-	pcdata = c.ctxt.EndUnsafePoint(call, c.newprog, -1)
+	unspill := c.cursym.Func().UnspillRegisterArgs(call, c.newprog)
+	pcdata = c.ctxt.EndUnsafePoint(unspill, c.newprog, -1)
 
 	// B	start
 	jmp := obj.Appendp(pcdata, c.newprog)
@@ -321,9 +325,9 @@
 		//     CALL REGTMP
 		var sym *obj.LSym
 		if p.As == obj.ADUFFZERO {
-			sym = c.ctxt.Lookup("runtime.duffzero")
+			sym = c.ctxt.LookupABI("runtime.duffzero", obj.ABIInternal)
 		} else {
-			sym = c.ctxt.Lookup("runtime.duffcopy")
+			sym = c.ctxt.LookupABI("runtime.duffcopy", obj.ABIInternal)
 		}
 		offset := p.To.Offset
 		p.As = AMOVD
@@ -631,38 +635,38 @@
 			if c.cursym.Func().Text.From.Sym.Wrapper() {
 				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
 				//
-				//	MOV  g_panic(g), R1
+				//	MOV  g_panic(g), RT1
 				//	CBNZ checkargp
 				// end:
 				//	NOP
 				// ... function body ...
 				// checkargp:
-				//	MOV  panic_argp(R1), R2
-				//	ADD  $(autosize+8), RSP, R3
-				//	CMP  R2, R3
+				//	MOV  panic_argp(RT1), RT2
+				//	ADD  $(autosize+8), RSP, R20
+				//	CMP  RT2, R20
 				//	BNE  end
-				//	ADD  $8, RSP, R4
-				//	MOVD R4, panic_argp(R1)
+				//	ADD  $8, RSP, R20
+				//	MOVD R20, panic_argp(RT1)
 				//	B    end
 				//
 				// The NOP is needed to give the jumps somewhere to land.
 				// It is a liblink NOP, not an ARM64 NOP: it encodes to 0 instruction bytes.
 				q = q1
 
-				// MOV g_panic(g), R1
+				// MOV g_panic(g), RT1
 				q = obj.Appendp(q, c.newprog)
 				q.As = AMOVD
 				q.From.Type = obj.TYPE_MEM
 				q.From.Reg = REGG
 				q.From.Offset = 4 * int64(c.ctxt.Arch.PtrSize) // G.panic
 				q.To.Type = obj.TYPE_REG
-				q.To.Reg = REG_R1
+				q.To.Reg = REGRT1
 
-				// CBNZ R1, checkargp
+				// CBNZ RT1, checkargp
 				cbnz := obj.Appendp(q, c.newprog)
 				cbnz.As = ACBNZ
 				cbnz.From.Type = obj.TYPE_REG
-				cbnz.From.Reg = REG_R1
+				cbnz.From.Reg = REGRT1
 				cbnz.To.Type = obj.TYPE_BRANCH
 
 				// Empty branch target at the top of the function body
@@ -674,33 +678,33 @@
 				for last = end; last.Link != nil; last = last.Link {
 				}
 
-				// MOV panic_argp(R1), R2
+				// MOV panic_argp(RT1), RT2
 				mov := obj.Appendp(last, c.newprog)
 				mov.As = AMOVD
 				mov.From.Type = obj.TYPE_MEM
-				mov.From.Reg = REG_R1
+				mov.From.Reg = REGRT1
 				mov.From.Offset = 0 // Panic.argp
 				mov.To.Type = obj.TYPE_REG
-				mov.To.Reg = REG_R2
+				mov.To.Reg = REGRT2
 
 				// CBNZ branches to the MOV above
 				cbnz.To.SetTarget(mov)
 
-				// ADD $(autosize+8), SP, R3
+				// ADD $(autosize+8), SP, R20
 				q = obj.Appendp(mov, c.newprog)
 				q.As = AADD
 				q.From.Type = obj.TYPE_CONST
 				q.From.Offset = int64(c.autosize) + 8
 				q.Reg = REGSP
 				q.To.Type = obj.TYPE_REG
-				q.To.Reg = REG_R3
+				q.To.Reg = REG_R20
 
-				// CMP R2, R3
+				// CMP RT2, R20
 				q = obj.Appendp(q, c.newprog)
 				q.As = ACMP
 				q.From.Type = obj.TYPE_REG
-				q.From.Reg = REG_R2
-				q.Reg = REG_R3
+				q.From.Reg = REGRT2
+				q.Reg = REG_R20
 
 				// BNE end
 				q = obj.Appendp(q, c.newprog)
@@ -708,22 +712,22 @@
 				q.To.Type = obj.TYPE_BRANCH
 				q.To.SetTarget(end)
 
-				// ADD $8, SP, R4
+				// ADD $8, SP, R20
 				q = obj.Appendp(q, c.newprog)
 				q.As = AADD
 				q.From.Type = obj.TYPE_CONST
 				q.From.Offset = 8
 				q.Reg = REGSP
 				q.To.Type = obj.TYPE_REG
-				q.To.Reg = REG_R4
+				q.To.Reg = REG_R20
 
-				// MOV R4, panic_argp(R1)
+				// MOV R20, panic_argp(RT1)
 				q = obj.Appendp(q, c.newprog)
 				q.As = AMOVD
 				q.From.Type = obj.TYPE_REG
-				q.From.Reg = REG_R4
+				q.From.Reg = REG_R20
 				q.To.Type = obj.TYPE_MEM
-				q.To.Reg = REG_R1
+				q.To.Reg = REGRT1
 				q.To.Offset = 0 // Panic.argp
 
 				// B end
diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
index 24fb5a1..01466ea 100644
--- a/src/cmd/internal/obj/objfile.go
+++ b/src/cmd/internal/obj/objfile.go
@@ -452,6 +452,11 @@
 		binary.LittleEndian.PutUint64(tmp[6:14], uint64(r.Add))
 		h.Write(tmp[:])
 		rs := r.Sym
+		if rs == nil {
+			fmt.Printf("symbol: %s\n", s)
+			fmt.Printf("relocation: %#v\n", r)
+			panic("nil symbol target in relocation")
+		}
 		switch rs.PkgIdx {
 		case goobj.PkgIdxHashed64:
 			h.Write([]byte{0})
diff --git a/src/cmd/internal/obj/wasm/wasmobj.go b/src/cmd/internal/obj/wasm/wasmobj.go
index ceeae7a2..4d276db 100644
--- a/src/cmd/internal/obj/wasm/wasmobj.go
+++ b/src/cmd/internal/obj/wasm/wasmobj.go
@@ -129,8 +129,6 @@
 	morestackNoCtxt *obj.LSym
 	gcWriteBarrier  *obj.LSym
 	sigpanic        *obj.LSym
-	deferreturn     *obj.LSym
-	jmpdefer        *obj.LSym
 )
 
 const (
@@ -143,10 +141,6 @@
 	morestackNoCtxt = ctxt.Lookup("runtime.morestack_noctxt")
 	gcWriteBarrier = ctxt.LookupABI("runtime.gcWriteBarrier", obj.ABIInternal)
 	sigpanic = ctxt.LookupABI("runtime.sigpanic", obj.ABIInternal)
-	deferreturn = ctxt.LookupABI("runtime.deferreturn", obj.ABIInternal)
-	// jmpdefer is defined in assembly as ABI0. The compiler will
-	// generate a direct ABI0 call from Go, so look for that.
-	jmpdefer = ctxt.LookupABI(`"".jmpdefer`, obj.ABI0)
 }
 
 func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
@@ -423,12 +417,6 @@
 				pcAfterCall-- // sigpanic expects to be called without advancing the pc
 			}
 
-			// jmpdefer manipulates the return address on the stack so deferreturn gets called repeatedly.
-			// Model this in WebAssembly with a loop.
-			if call.To.Sym == deferreturn {
-				p = appendp(p, ALoop)
-			}
-
 			// SP -= 8
 			p = appendp(p, AGet, regAddr(REG_SP))
 			p = appendp(p, AI32Const, constAddr(8))
@@ -479,15 +467,6 @@
 				break
 			}
 
-			// jmpdefer removes the frame of deferreturn from the Go stack.
-			// However, its WebAssembly function still returns normally,
-			// so we need to return from deferreturn without removing its
-			// stack frame (no RET), because the frame is already gone.
-			if call.To.Sym == jmpdefer {
-				p = appendp(p, AReturn)
-				break
-			}
-
 			// return value of call is on the top of the stack, indicating whether to unwind the WebAssembly stack
 			if call.As == ACALLNORESUME && call.To.Sym != sigpanic { // sigpanic unwinds the stack, but it never resumes
 				// trying to unwind WebAssembly stack but call has no resume point, terminate with error
@@ -500,21 +479,6 @@
 				unwindExitBranches = append(unwindExitBranches, p)
 			}
 
-			// jump to before the call if jmpdefer has reset the return address to the call's PC
-			if call.To.Sym == deferreturn {
-				// get PC_B from -8(SP)
-				p = appendp(p, AGet, regAddr(REG_SP))
-				p = appendp(p, AI32Const, constAddr(8))
-				p = appendp(p, AI32Sub)
-				p = appendp(p, AI32Load16U, constAddr(0))
-				p = appendp(p, ATee, regAddr(REG_PC_B))
-
-				p = appendp(p, AI32Const, constAddr(call.Pc))
-				p = appendp(p, AI32Eq)
-				p = appendp(p, ABrIf, constAddr(0))
-				p = appendp(p, AEnd) // end of Loop
-			}
-
 		case obj.ARET, ARETUNWIND:
 			ret := *p
 			p.As = obj.ANOP
diff --git a/src/cmd/internal/obj/x86/asm6.go b/src/cmd/internal/obj/x86/asm6.go
index 17fa767..331a98d 100644
--- a/src/cmd/internal/obj/x86/asm6.go
+++ b/src/cmd/internal/obj/x86/asm6.go
@@ -43,7 +43,6 @@
 
 var (
 	plan9privates *obj.LSym
-	deferreturn   *obj.LSym
 )
 
 // Instruction layout.
diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index e2732d5..183ca2e 100644
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -35,7 +35,6 @@
 	"cmd/internal/objabi"
 	"cmd/internal/src"
 	"cmd/internal/sys"
-	"internal/buildcfg"
 	"log"
 	"math"
 	"path"
@@ -647,13 +646,12 @@
 
 	var regg int16
 	if !p.From.Sym.NoSplit() || p.From.Sym.Wrapper() {
-		if ctxt.Arch.Family == sys.AMD64 && buildcfg.Experiment.RegabiG && cursym.ABI() == obj.ABIInternal {
+		if ctxt.Arch.Family == sys.AMD64 && cursym.ABI() == obj.ABIInternal {
 			regg = REGG // use the g register directly in ABIInternal
 		} else {
 			p = obj.Appendp(p, newprog)
 			regg = REG_CX
 			if ctxt.Arch.Family == sys.AMD64 {
-				// Using this register means that stacksplit works w/ //go:registerparams even when !buildcfg.Experiment.RegabiG
 				regg = REGG // == REG_R14
 			}
 			p = load_g(ctxt, p, newprog, regg) // load g into regg
diff --git a/src/cmd/internal/objabi/funcid.go b/src/cmd/internal/objabi/funcid.go
index 93ebd7b..68f6a26 100644
--- a/src/cmd/internal/objabi/funcid.go
+++ b/src/cmd/internal/objabi/funcid.go
@@ -34,7 +34,6 @@
 	FuncID_gogo
 	FuncID_gopanic
 	FuncID_handleAsyncEvent
-	FuncID_jmpdefer
 	FuncID_mcall
 	FuncID_morestack
 	FuncID_mstart
@@ -60,7 +59,6 @@
 	"gogo":             FuncID_gogo,
 	"gopanic":          FuncID_gopanic,
 	"handleAsyncEvent": FuncID_handleAsyncEvent,
-	"jmpdefer":         FuncID_jmpdefer,
 	"main":             FuncID_runtime_main,
 	"mcall":            FuncID_mcall,
 	"morestack":        FuncID_morestack,
@@ -74,7 +72,6 @@
 	// Don't show in call stack but otherwise not special.
 	"deferreturn":       FuncID_wrapper,
 	"runOpenDeferFrame": FuncID_wrapper,
-	"reflectcallSave":   FuncID_wrapper,
 	"deferCallSave":     FuncID_wrapper,
 }
 
diff --git a/src/cmd/link/internal/ld/deadcode.go b/src/cmd/link/internal/ld/deadcode.go
index 416e5da..dd5dafc 100644
--- a/src/cmd/link/internal/ld/deadcode.go
+++ b/src/cmd/link/internal/ld/deadcode.go
@@ -408,6 +408,9 @@
 // Decode the method of interface type symbol symIdx at offset off.
 func (d *deadcodePass) decodeIfaceMethod(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym, off int64) methodsig {
 	p := ldr.Data(symIdx)
+	if p == nil {
+		panic(fmt.Sprintf("missing symbol %q", ldr.SymName(symIdx)))
+	}
 	if decodetypeKind(arch, p)&kindMask != kindInterface {
 		panic(fmt.Sprintf("symbol %q is not an interface", ldr.SymName(symIdx)))
 	}
diff --git a/src/cmd/link/internal/ld/dwarf_test.go b/src/cmd/link/internal/ld/dwarf_test.go
index 2f59c2f..543dd5c 100644
--- a/src/cmd/link/internal/ld/dwarf_test.go
+++ b/src/cmd/link/internal/ld/dwarf_test.go
@@ -101,8 +101,11 @@
 	}
 
 	cmd := exec.Command(testenv.GoToolPath(t), "build", gcflags, "-o", dst, src)
-	if b, err := cmd.CombinedOutput(); err != nil {
-		t.Logf("build: %s\n", b)
+	b, err := cmd.CombinedOutput()
+	if len(b) != 0 {
+		t.Logf("## build output:\n%s", b)
+	}
+	if err != nil {
 		t.Fatalf("build error: %v", err)
 	}
 
diff --git a/src/cmd/link/internal/ld/pcln.go b/src/cmd/link/internal/ld/pcln.go
index 05fd302..70e3e12 100644
--- a/src/cmd/link/internal/ld/pcln.go
+++ b/src/cmd/link/internal/ld/pcln.go
@@ -129,11 +129,10 @@
 	for ri := 0; ri < relocs.Count(); ri++ {
 		r := relocs.At(ri)
 		if target.IsWasm() && r.Type() == objabi.R_ADDR {
-			// Wasm does not have a live variable set at the deferreturn
-			// call itself. Instead it has one identified by the
-			// resumption point immediately preceding the deferreturn.
-			// The wasm code has a R_ADDR relocation which is used to
-			// set the resumption point to PC_B.
+			// wasm/ssa.go generates an ARESUMEPOINT just
+			// before the deferreturn call. The "PC" of
+			// the deferreturn call is stored in the
+			// R_ADDR relocation on the ARESUMEPOINT.
 			lastWasmAddr = uint32(r.Add())
 		}
 		if r.Type().IsDirectCall() && (r.Sym() == deferReturnSym || ldr.IsDeferReturnTramp(r.Sym())) {
diff --git a/src/cmd/link/internal/ld/symtab.go b/src/cmd/link/internal/ld/symtab.go
index 00f5578..1f5e333 100644
--- a/src/cmd/link/internal/ld/symtab.go
+++ b/src/cmd/link/internal/ld/symtab.go
@@ -300,6 +300,7 @@
 	ctxt.Out.Write8(uint8(t + 0x80)) /* 0x80 is variable length */
 
 	name := ldr.SymName(s)
+	name = mangleABIName(ctxt, ldr, s, name)
 	ctxt.Out.WriteString(name)
 	ctxt.Out.Write8(0)
 
diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go
index 7230054..fed9c7b 100644
--- a/src/cmd/link/link_test.go
+++ b/src/cmd/link/link_test.go
@@ -545,14 +545,13 @@
 package main
 import (
 	"fmt"
-	"reflect"
 )
 func alignPc()
+var alignPcFnAddr uintptr
 
 func main() {
-	addr := reflect.ValueOf(alignPc).Pointer()
-	if (addr % 512) != 0 {
-		fmt.Printf("expected 512 bytes alignment, got %v\n", addr)
+	if alignPcFnAddr % 512 != 0 {
+		fmt.Printf("expected 512 bytes alignment, got %v\n", alignPcFnAddr)
 	} else {
 		fmt.Printf("PASS")
 	}
@@ -567,6 +566,9 @@
 	PCALIGN	$512
 	MOVD	$3, R1
 	RET
+
+GLOBL	·alignPcFnAddr(SB),RODATA,$8
+DATA	·alignPcFnAddr(SB)/8,$·alignPc(SB)
 `
 
 // TestFuncAlign verifies that the address of a function can be aligned
diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go
index eb0016b..7b82d0b 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/asmdecl/asmdecl.go
@@ -51,6 +51,11 @@
 	bigEndian bool
 	stack     string
 	lr        bool
+	// retRegs is a list of registers for return value in register ABI (ABIInternal).
+	// For now, as we only check whether we write to any result, here we only need to
+	// include the first integer register and first floating-point register. Accessing
+	// any of them counts as writing to result.
+	retRegs []string
 	// calculated during initialization
 	sizes    types.Sizes
 	intSize  int
@@ -79,8 +84,8 @@
 var (
 	asmArch386      = asmArch{name: "386", bigEndian: false, stack: "SP", lr: false}
 	asmArchArm      = asmArch{name: "arm", bigEndian: false, stack: "R13", lr: true}
-	asmArchArm64    = asmArch{name: "arm64", bigEndian: false, stack: "RSP", lr: true}
-	asmArchAmd64    = asmArch{name: "amd64", bigEndian: false, stack: "SP", lr: false}
+	asmArchArm64    = asmArch{name: "arm64", bigEndian: false, stack: "RSP", lr: true, retRegs: []string{"R0", "F0"}}
+	asmArchAmd64    = asmArch{name: "amd64", bigEndian: false, stack: "SP", lr: false, retRegs: []string{"AX", "X0"}}
 	asmArchMips     = asmArch{name: "mips", bigEndian: true, stack: "R29", lr: true}
 	asmArchMipsLE   = asmArch{name: "mipsle", bigEndian: false, stack: "R29", lr: true}
 	asmArchMips64   = asmArch{name: "mips64", bigEndian: true, stack: "R29", lr: true}
@@ -137,7 +142,7 @@
 	asmSP        = re(`[^+\-0-9](([0-9]+)\(([A-Z0-9]+)\))`)
 	asmOpcode    = re(`^\s*(?:[A-Z0-9a-z_]+:)?\s*([A-Z]+)\s*([^,]*)(?:,\s*(.*))?`)
 	ppc64Suff    = re(`([BHWD])(ZU|Z|U|BR)?$`)
-	abiSuff      = re(`^(.+)<ABI.+>$`)
+	abiSuff      = re(`^(.+)<(ABI.+)>$`)
 )
 
 func run(pass *analysis.Pass) (interface{}, error) {
@@ -185,6 +190,7 @@
 		var (
 			fn                 *asmFunc
 			fnName             string
+			abi                string
 			localSize, argSize int
 			wroteSP            bool
 			noframe            bool
@@ -195,18 +201,22 @@
 		flushRet := func() {
 			if fn != nil && fn.vars["ret"] != nil && !haveRetArg && len(retLine) > 0 {
 				v := fn.vars["ret"]
+				resultStr := fmt.Sprintf("%d-byte ret+%d(FP)", v.size, v.off)
+				if abi == "ABIInternal" {
+					resultStr = "result register"
+				}
 				for _, line := range retLine {
-					pass.Reportf(analysisutil.LineStart(tf, line), "[%s] %s: RET without writing to %d-byte ret+%d(FP)", arch, fnName, v.size, v.off)
+					pass.Reportf(analysisutil.LineStart(tf, line), "[%s] %s: RET without writing to %s", arch, fnName, resultStr)
 				}
 			}
 			retLine = nil
 		}
-		trimABI := func(fnName string) string {
+		trimABI := func(fnName string) (string, string) {
 			m := abiSuff.FindStringSubmatch(fnName)
 			if m != nil {
-				return m[1]
+				return m[1], m[2]
 			}
-			return fnName
+			return fnName, ""
 		}
 		for lineno, line := range lines {
 			lineno++
@@ -273,11 +283,12 @@
 						// log.Printf("%s:%d: [%s] cannot check cross-package assembly function: %s is in package %s", fname, lineno, arch, fnName, pkgPath)
 						fn = nil
 						fnName = ""
+						abi = ""
 						continue
 					}
 				}
 				// Trim off optional ABI selector.
-				fnName := trimABI(fnName)
+				fnName, abi = trimABI(fnName)
 				flag := m[3]
 				fn = knownFunc[fnName][arch]
 				if fn != nil {
@@ -305,6 +316,7 @@
 				flushRet()
 				fn = nil
 				fnName = ""
+				abi = ""
 				continue
 			}
 
@@ -335,6 +347,15 @@
 				haveRetArg = true
 			}
 
+			if abi == "ABIInternal" && !haveRetArg {
+				for _, reg := range archDef.retRegs {
+					if strings.Contains(line, reg) {
+						haveRetArg = true
+						break
+					}
+				}
+			}
+
 			for _, m := range asmSP.FindAllStringSubmatch(line, -1) {
 				if m[3] != archDef.stack || wroteSP || noframe {
 					continue
diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go
index 822820f..6589478 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go
@@ -555,7 +555,7 @@
 	format, idx := formatString(pass, call)
 	if idx < 0 {
 		if false {
-			pass.Reportf(call.Lparen, "can't check non-constant format in call to %s", fn.Name())
+			pass.Reportf(call.Lparen, "can't check non-constant format in call to %s", fn.FullName())
 		}
 		return
 	}
@@ -563,7 +563,7 @@
 	firstArg := idx + 1 // Arguments are immediately after format string.
 	if !strings.Contains(format, "%") {
 		if len(call.Args) > firstArg {
-			pass.Reportf(call.Lparen, "%s call has arguments but no formatting directives", fn.Name())
+			pass.Reportf(call.Lparen, "%s call has arguments but no formatting directives", fn.FullName())
 		}
 		return
 	}
@@ -577,7 +577,7 @@
 		if format[i] != '%' {
 			continue
 		}
-		state := parsePrintfVerb(pass, call, fn.Name(), format[i:], firstArg, argNum)
+		state := parsePrintfVerb(pass, call, fn.FullName(), format[i:], firstArg, argNum)
 		if state == nil {
 			return
 		}
@@ -589,8 +589,12 @@
 			anyIndex = true
 		}
 		if state.verb == 'w' {
-			if kind != KindErrorf {
-				pass.Reportf(call.Pos(), "%s call has error-wrapping directive %%w, which is only supported by Errorf", state.name)
+			switch kind {
+			case KindNone, KindPrint:
+				pass.Reportf(call.Pos(), "%s does not support error-wrapping directive %%w", state.name)
+				return
+			case KindPrintf:
+				pass.Reportf(call.Pos(), "%s call has error-wrapping directive %%w, which is only supported for functions backed by fmt.Errorf", state.name)
 				return
 			}
 			if anyW {
@@ -621,7 +625,7 @@
 	if maxArgNum != len(call.Args) {
 		expect := maxArgNum - firstArg
 		numArgs := len(call.Args) - firstArg
-		pass.ReportRangef(call, "%s call needs %v but has %v", fn.Name(), count(expect, "arg"), count(numArgs, "arg"))
+		pass.ReportRangef(call, "%s call needs %v but has %v", fn.FullName(), count(expect, "arg"), count(numArgs, "arg"))
 	}
 }
 
@@ -949,7 +953,7 @@
 	}
 	if id, ok := e.(*ast.Ident); ok {
 		if pass.TypesInfo.Uses[id] == sig.Recv() {
-			return method.Name(), true
+			return method.FullName(), true
 		}
 	}
 	return "", false
@@ -1044,7 +1048,7 @@
 		if sel, ok := call.Args[0].(*ast.SelectorExpr); ok {
 			if x, ok := sel.X.(*ast.Ident); ok {
 				if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") {
-					pass.ReportRangef(call, "%s does not take io.Writer but has first arg %s", fn.Name(), analysisutil.Format(pass.Fset, call.Args[0]))
+					pass.ReportRangef(call, "%s does not take io.Writer but has first arg %s", fn.FullName(), analysisutil.Format(pass.Fset, call.Args[0]))
 				}
 			}
 		}
@@ -1058,7 +1062,7 @@
 		if strings.Contains(s, "%") {
 			m := printFormatRE.FindStringSubmatch(s)
 			if m != nil {
-				pass.ReportRangef(call, "%s call has possible formatting directive %s", fn.Name(), m[0])
+				pass.ReportRangef(call, "%s call has possible formatting directive %s", fn.FullName(), m[0])
 			}
 		}
 	}
@@ -1068,16 +1072,16 @@
 		if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
 			str, _ := strconv.Unquote(lit.Value)
 			if strings.HasSuffix(str, "\n") {
-				pass.ReportRangef(call, "%s arg list ends with redundant newline", fn.Name())
+				pass.ReportRangef(call, "%s arg list ends with redundant newline", fn.FullName())
 			}
 		}
 	}
 	for _, arg := range args {
 		if isFunctionValue(pass, arg) {
-			pass.ReportRangef(call, "%s arg %s is a func value, not called", fn.Name(), analysisutil.Format(pass.Fset, arg))
+			pass.ReportRangef(call, "%s arg %s is a func value, not called", fn.FullName(), analysisutil.Format(pass.Fset, arg))
 		}
 		if methodName, ok := recursiveStringer(pass, arg); ok {
-			pass.ReportRangef(call, "%s arg %s causes recursive call to %s method", fn.Name(), analysisutil.Format(pass.Fset, arg), methodName)
+			pass.ReportRangef(call, "%s arg %s causes recursive call to %s method", fn.FullName(), analysisutil.Format(pass.Fset, arg), methodName)
 		}
 	}
 }
diff --git a/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go b/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
index cf72ea9..5fe75b1 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
@@ -9,6 +9,8 @@
 	"go/ast"
 	"reflect"
 	"sort"
+
+	"golang.org/x/tools/internal/typeparams"
 )
 
 // An ApplyFunc is invoked by Apply for each node n, even if n is nil,
@@ -437,7 +439,13 @@
 		}
 
 	default:
-		panic(fmt.Sprintf("Apply: unexpected node type %T", n))
+		if ix := typeparams.GetIndexExprData(n); ix != nil {
+			a.apply(n, "X", nil, ix.X)
+			// *ast.IndexExpr was handled above, so n must be an *ast.MultiIndexExpr.
+			a.applyList(n, "Indices")
+		} else {
+			panic(fmt.Sprintf("Apply: unexpected node type %T", n))
+		}
 	}
 
 	if a.post != nil && !a.post(&a.cursor) {
diff --git a/src/cmd/vendor/golang.org/x/tools/go/types/objectpath/objectpath.go b/src/cmd/vendor/golang.org/x/tools/go/types/objectpath/objectpath.go
index cffd7ac..81e8fdc 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/types/objectpath/objectpath.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/types/objectpath/objectpath.go
@@ -58,7 +58,7 @@
 // - The only OT operator is Object.Type,
 //   which we encode as '.' because dot cannot appear in an identifier.
 // - The TT operators are encoded as [EKPRU].
-// - The OT operators are encoded as [AFMO];
+// - The TO operators are encoded as [AFMO];
 //   three of these (At,Field,Method) require an integer operand,
 //   which is encoded as a string of decimal digits.
 //   These indices are stable across different representations
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/input.go b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/input.go
index ac37703..c103816 100644
--- a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/input.go
+++ b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/input.go
@@ -27,23 +27,23 @@
 // RuneRoles detects the roles of each byte rune in an input string and stores it in the output
 // slice. The rune role depends on the input type. Stops when it parsed all the runes in the string
 // or when it filled the output. If output is nil, then it gets created.
-func RuneRoles(str string, reuse []RuneRole) []RuneRole {
+func RuneRoles(candidate []byte, reuse []RuneRole) []RuneRole {
 	var output []RuneRole
-	if cap(reuse) < len(str) {
-		output = make([]RuneRole, 0, len(str))
+	if cap(reuse) < len(candidate) {
+		output = make([]RuneRole, 0, len(candidate))
 	} else {
 		output = reuse[:0]
 	}
 
 	prev, prev2 := rtNone, rtNone
-	for i := 0; i < len(str); i++ {
-		r := rune(str[i])
+	for i := 0; i < len(candidate); i++ {
+		r := rune(candidate[i])
 
 		role := RNone
 
 		curr := rtLower
-		if str[i] <= unicode.MaxASCII {
-			curr = runeType(rt[str[i]] - '0')
+		if candidate[i] <= unicode.MaxASCII {
+			curr = runeType(rt[candidate[i]] - '0')
 		}
 
 		if curr == rtLower {
@@ -58,7 +58,7 @@
 			if prev == rtUpper {
 				// This and previous characters are both upper case.
 
-				if i+1 == len(str) {
+				if i+1 == len(candidate) {
 					// This is last character, previous was also uppercase -> this is UCTail
 					// i.e., (current char is C): aBC / BC / ABC
 					role = RUCTail
@@ -118,11 +118,26 @@
 	return input[start+1 : end+1]
 }
 
-// ToLower transforms the input string to lower case, which is stored in the output byte slice.
+// fromChunks copies string chunks into the given buffer.
+func fromChunks(chunks []string, buffer []byte) []byte {
+	ii := 0
+	for _, chunk := range chunks {
+		for i := 0; i < len(chunk); i++ {
+			if ii >= cap(buffer) {
+				break
+			}
+			buffer[ii] = chunk[i]
+			ii++
+		}
+	}
+	return buffer[:ii]
+}
+
+// toLower transforms the input string to lower case, which is stored in the output byte slice.
 // The lower casing considers only ASCII values - non ASCII values are left unmodified.
 // Stops when parsed all input or when it filled the output slice. If output is nil, then it gets
 // created.
-func ToLower(input string, reuse []byte) []byte {
+func toLower(input []byte, reuse []byte) []byte {
 	output := reuse
 	if cap(reuse) < len(input) {
 		output = make([]byte, len(input))
@@ -130,7 +145,7 @@
 
 	for i := 0; i < len(input); i++ {
 		r := rune(input[i])
-		if r <= unicode.MaxASCII {
+		if input[i] <= unicode.MaxASCII {
 			if 'A' <= r && r <= 'Z' {
 				r += 'a' - 'A'
 			}
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/matcher.go b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/matcher.go
index 16a6430..265cdcf 100644
--- a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/matcher.go
+++ b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/matcher.go
@@ -51,8 +51,12 @@
 	lastCandidateLen     int // in bytes
 	lastCandidateMatched bool
 
-	// Here we save the last candidate in lower-case. This is basically a byte slice we reuse for
-	// performance reasons, so the slice is not reallocated for every candidate.
+	// Reusable buffers to avoid allocating for every candidate.
+	//  - inputBuf stores the concatenated input chunks
+	//  - lowerBuf stores the last candidate in lower-case
+	//  - rolesBuf stores the calculated roles for each rune in the last
+	//    candidate.
+	inputBuf [MaxInputSize]byte
 	lowerBuf [MaxInputSize]byte
 	rolesBuf [MaxInputSize]RuneRole
 }
@@ -72,7 +76,7 @@
 
 	m := &Matcher{
 		pattern:      pattern,
-		patternLower: ToLower(pattern, nil),
+		patternLower: toLower([]byte(pattern), nil),
 	}
 
 	for i, c := range m.patternLower {
@@ -88,7 +92,7 @@
 		m.patternShort = m.patternLower
 	}
 
-	m.patternRoles = RuneRoles(pattern, nil)
+	m.patternRoles = RuneRoles([]byte(pattern), nil)
 
 	if len(pattern) > 0 {
 		maxCharScore := 4
@@ -102,10 +106,15 @@
 // This is not designed for parallel use. Multiple candidates must be scored sequentially.
 // Returns a score between 0 and 1 (0 - no match, 1 - perfect match).
 func (m *Matcher) Score(candidate string) float32 {
+	return m.ScoreChunks([]string{candidate})
+}
+
+func (m *Matcher) ScoreChunks(chunks []string) float32 {
+	candidate := fromChunks(chunks, m.inputBuf[:])
 	if len(candidate) > MaxInputSize {
 		candidate = candidate[:MaxInputSize]
 	}
-	lower := ToLower(candidate, m.lowerBuf[:])
+	lower := toLower(candidate, m.lowerBuf[:])
 	m.lastCandidateLen = len(candidate)
 
 	if len(m.pattern) == 0 {
@@ -174,7 +183,7 @@
 	return ret
 }
 
-func (m *Matcher) match(candidate string, candidateLower []byte) bool {
+func (m *Matcher) match(candidate []byte, candidateLower []byte) bool {
 	i, j := 0, 0
 	for ; i < len(candidateLower) && j < len(m.patternLower); i++ {
 		if candidateLower[i] == m.patternLower[j] {
@@ -192,7 +201,7 @@
 	return true
 }
 
-func (m *Matcher) computeScore(candidate string, candidateLower []byte) int {
+func (m *Matcher) computeScore(candidate []byte, candidateLower []byte) int {
 	pattLen, candLen := len(m.pattern), len(candidate)
 
 	for j := 0; j <= len(m.pattern); j++ {
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/symbol.go b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/symbol.go
new file mode 100644
index 0000000..062f491
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/lsp/fuzzy/symbol.go
@@ -0,0 +1,224 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fuzzy
+
+import (
+	"unicode"
+)
+
+// SymbolMatcher implements a fuzzy matching algorithm optimized for Go symbols
+// of the form:
+//  example.com/path/to/package.object.field
+//
+// Knowing that we are matching symbols like this allows us to make the
+// following optimizations:
+//  - We can incorporate right-to-left relevance directly into the score
+//    calculation.
+//  - We can match from right to left, discarding leading bytes if the input is
+//    too long.
+//  - We just take the right-most match without losing too much precision. This
+//    allows us to use an O(n) algorithm.
+//  - We can operate directly on chunked strings; in many cases we will
+//    be storing the package path and/or package name separately from the
+//    symbol or identifiers, so doing this avoids allocating strings.
+//  - We can return the index of the right-most match, allowing us to trim
+//    irrelevant qualification.
+//
+// This implementation is experimental, serving as a reference fast algorithm
+// to compare to the fuzzy algorithm implemented by Matcher.
+type SymbolMatcher struct {
+	// Using buffers of length 256 is both a reasonable size for most qualified
+	// symbols, and makes it easy to avoid bounds checks by using uint8 indexes.
+	pattern     [256]rune
+	patternLen  uint8
+	inputBuffer [256]rune   // avoid allocating when considering chunks
+	roles       [256]uint32 // which roles does a rune play (word start, etc.)
+	segments    [256]uint8  // how many segments from the right is each rune
+}
+
+const (
+	segmentStart uint32 = 1 << iota
+	wordStart
+	separator
+)
+
+// NewSymbolMatcher creates a SymbolMatcher that may be used to match the given
+// search pattern.
+//
+// Currently this matcher only accepts case-insensitive fuzzy patterns.
+//
+// TODO(rfindley):
+//  - implement smart-casing
+//  - implement space-separated groups
+//  - implement ', ^, and $ modifiers
+//
+// An empty pattern matches no input.
+func NewSymbolMatcher(pattern string) *SymbolMatcher {
+	m := &SymbolMatcher{}
+	for _, p := range pattern {
+		m.pattern[m.patternLen] = unicode.ToLower(p)
+		m.patternLen++
+		if m.patternLen == 255 || int(m.patternLen) == len(pattern) {
+			// break at 255 so that we can represent patternLen with a uint8.
+			break
+		}
+	}
+	return m
+}
+
+// Match looks for the right-most match of the search pattern within the symbol
+// represented by concatenating the given chunks, returning its offset and
+// score.
+//
+// If a match is found, the first return value will hold the absolute byte
+// offset within all chunks for the start of the symbol. In other words, the
+// index of the match within strings.Join(chunks, ""). If no match is found,
+// the first return value will be -1.
+//
+// The second return value will be the score of the match, which is always
+// between 0 and 1, inclusive. A score of 0 indicates no match.
+func (m *SymbolMatcher) Match(chunks []string) (int, float64) {
+	// Explicit behavior for an empty pattern.
+	//
+	// As a minor optimization, this also avoids nilness checks later on, since
+	// the compiler can prove that m != nil.
+	if m.patternLen == 0 {
+		return -1, 0
+	}
+
+	// First phase: populate the input buffer with lower-cased runes.
+	//
+	// We could also check for a forward match here, but since we'd have to write
+	// the entire input anyway this has negligible impact on performance.
+
+	var (
+		inputLen  = uint8(0)
+		modifiers = wordStart | segmentStart
+	)
+
+input:
+	for _, chunk := range chunks {
+		for _, r := range chunk {
+			if r == '.' || r == '/' {
+				modifiers |= separator
+			}
+			// optimization: avoid calls to unicode.ToLower, which can't be inlined.
+			l := r
+			if r <= unicode.MaxASCII {
+				if 'A' <= r && r <= 'Z' {
+					l = r + 'a' - 'A'
+				}
+			} else {
+				l = unicode.ToLower(r)
+			}
+			if l != r {
+				modifiers |= wordStart
+			}
+			m.inputBuffer[inputLen] = l
+			m.roles[inputLen] = modifiers
+			inputLen++
+			if m.roles[inputLen-1]&separator != 0 {
+				modifiers = wordStart | segmentStart
+			} else {
+				modifiers = 0
+			}
+			// TODO: we should prefer the right-most input if it overflows, rather
+			//       than the left-most as we're doing here.
+			if inputLen == 255 {
+				break input
+			}
+		}
+	}
+
+	// Second phase: find the right-most match, and count segments from the
+	// right.
+
+	var (
+		pi    = uint8(m.patternLen - 1) // pattern index
+		p     = m.pattern[pi]           // pattern rune
+		start = -1                      // start offset of match
+		rseg  = uint8(0)
+	)
+	const maxSeg = 3 // maximum number of segments from the right to count, for scoring purposes.
+
+	for ii := inputLen - 1; ; ii-- {
+		r := m.inputBuffer[ii]
+		if rseg < maxSeg && m.roles[ii]&separator != 0 {
+			rseg++
+		}
+		m.segments[ii] = rseg
+		if p == r {
+			if pi == 0 {
+				start = int(ii)
+				break
+			}
+			pi--
+			p = m.pattern[pi]
+		}
+		// Don't check ii >= 0 in the loop condition: ii is a uint8.
+		if ii == 0 {
+			break
+		}
+	}
+
+	if start < 0 {
+		// no match: skip scoring
+		return -1, 0
+	}
+
+	// Third phase: find the shortest match, and compute the score.
+
+	// Score is the average score for each character.
+	//
+	// A character score is the multiple of:
+	//   1. 1.0 if the character starts a segment, .8 if the character start a
+	//      mid-segment word, otherwise 0.6. This carries over to immediately
+	//      following characters.
+	//   2. 1.0 if the character is part of the last segment, otherwise
+	//      1.0-.2*<segments from the right>, with a max segment count of 3.
+	//
+	// This is a very naive algorithm, but it is fast. There's lots of prior art
+	// here, and we should leverage it. For example, we could explicitly consider
+	// character distance, and exact matches of words or segments.
+	//
+	// Also note that this might not actually find the highest scoring match, as
+	// doing so could require a non-linear algorithm, depending on how the score
+	// is calculated.
+
+	pi = 0
+	p = m.pattern[pi]
+
+	const (
+		segStreak  = 1.0
+		wordStreak = 0.8
+		noStreak   = 0.6
+		perSegment = 0.2 // we count at most 3 segments above
+	)
+
+	streakBonus := noStreak
+	totScore := 0.0
+	for ii := uint8(start); ii < inputLen; ii++ {
+		r := m.inputBuffer[ii]
+		if r == p {
+			pi++
+			p = m.pattern[pi]
+			// Note: this could be optimized with some bit operations.
+			switch {
+			case m.roles[ii]&segmentStart != 0 && segStreak > streakBonus:
+				streakBonus = segStreak
+			case m.roles[ii]&wordStart != 0 && wordStreak > streakBonus:
+				streakBonus = wordStreak
+			}
+			totScore += streakBonus * (1.0 - float64(m.segments[ii])*perSegment)
+			if pi >= m.patternLen {
+				break
+			}
+		} else {
+			streakBonus = noStreak
+		}
+	}
+
+	return start, totScore / float64(m.patternLen)
+}
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/common.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/common.go
new file mode 100644
index 0000000..9fc6b4b
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/common.go
@@ -0,0 +1,25 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package typeparams provides functions to work indirectly with type parameter
+// data stored in go/ast and go/types objects, while these API are guarded by a
+// build constraint.
+//
+// This package exists to make it easier for tools to work with generic code,
+// while also compiling against older Go versions.
+package typeparams
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// A IndexExprData holds data from both ast.IndexExpr and the new
+// ast.MultiIndexExpr, which was introduced in Go 1.18.
+type IndexExprData struct {
+	X       ast.Expr   // expression
+	Lbrack  token.Pos  // position of "["
+	Indices []ast.Expr // index expressions
+	Rbrack  token.Pos  // position of "]"
+}
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go
new file mode 100644
index 0000000..e975e47
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go
@@ -0,0 +1,93 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !typeparams || !go1.18
+// +build !typeparams !go1.18
+
+package typeparams
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+// NOTE: doc comments must be kept in sync with typeparams.go.
+
+// Enabled reports whether type parameters are enabled in the current build
+// environment.
+const Enabled = false
+
+// GetIndexExprData extracts data from AST nodes that represent index
+// expressions.
+//
+// For an ast.IndexExpr, the resulting IndexExprData will have exactly one
+// index expression. For an ast.MultiIndexExpr (go1.18+), it may have a
+// variable number of index expressions.
+//
+// For nodes that don't represent index expressions, GetIndexExprData returns
+// nil.
+func GetIndexExprData(n ast.Node) *IndexExprData {
+	if e, _ := n.(*ast.IndexExpr); e != nil {
+		return &IndexExprData{
+			X:       e.X,
+			Lbrack:  e.Lbrack,
+			Indices: []ast.Expr{e.Index},
+			Rbrack:  e.Rbrack,
+		}
+	}
+	return nil
+}
+
+// ForTypeDecl extracts the (possibly nil) type parameter node list from n.
+func ForTypeDecl(*ast.TypeSpec) *ast.FieldList {
+	return nil
+}
+
+// ForFuncDecl extracts the (possibly nil) type parameter node list from n.
+func ForFuncDecl(*ast.FuncDecl) *ast.FieldList {
+	return nil
+}
+
+// ForSignature extracts the (possibly empty) type parameter object list from
+// sig.
+func ForSignature(*types.Signature) []*types.TypeName {
+	return nil
+}
+
+// IsComparable reports if iface is the comparable interface.
+func IsComparable(*types.Interface) bool {
+	return false
+}
+
+// IsConstraint reports whether iface may only be used as a type parameter
+// constraint (i.e. has a type set or is the comparable interface).
+func IsConstraint(*types.Interface) bool {
+	return false
+}
+
+// ForNamed extracts the (possibly empty) type parameter object list from
+// named.
+func ForNamed(*types.Named) []*types.TypeName {
+	return nil
+}
+
+// NamedTArgs extracts the (possibly empty) type argument list from named.
+func NamedTArgs(*types.Named) []types.Type {
+	return nil
+}
+
+// InitInferred initializes info to record inferred type information.
+func InitInferred(*types.Info) {
+}
+
+// GetInferred extracts inferred type information from info for e.
+//
+// The expression e may have an inferred type if it is an *ast.IndexExpr
+// representing partial instantiation of a generic function type for which type
+// arguments have been inferred using constraint type inference, or if it is an
+// *ast.CallExpr for which type type arguments have be inferred using both
+// constraint type inference and function argument inference.
+func GetInferred(*types.Info, ast.Expr) ([]types.Type, *types.Signature) {
+	return nil, nil
+}
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
new file mode 100644
index 0000000..be6b052
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
@@ -0,0 +1,115 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build typeparams && go1.18
+// +build typeparams,go1.18
+
+package typeparams
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+// NOTE: doc comments must be kept in sync with notypeparams.go.
+
+// Enabled reports whether type parameters are enabled in the current build
+// environment.
+const Enabled = true
+
+// GetIndexExprData extracts data from AST nodes that represent index
+// expressions.
+//
+// For an ast.IndexExpr, the resulting IndexExprData will have exactly one
+// index expression. For an ast.MultiIndexExpr (go1.18+), it may have a
+// variable number of index expressions.
+//
+// For nodes that don't represent index expressions, GetIndexExprData returns
+// nil.
+func GetIndexExprData(n ast.Node) *IndexExprData {
+	switch e := n.(type) {
+	case *ast.IndexExpr:
+		return &IndexExprData{
+			X:       e.X,
+			Lbrack:  e.Lbrack,
+			Indices: []ast.Expr{e.Index},
+			Rbrack:  e.Rbrack,
+		}
+	case *ast.MultiIndexExpr:
+		return (*IndexExprData)(e)
+	}
+	return nil
+}
+
+// ForTypeDecl extracts the (possibly nil) type parameter node list from n.
+func ForTypeDecl(n *ast.TypeSpec) *ast.FieldList {
+	return n.TParams
+}
+
+// ForFuncDecl extracts the (possibly nil) type parameter node list from n.
+func ForFuncDecl(n *ast.FuncDecl) *ast.FieldList {
+	if n.Type != nil {
+		return n.Type.TParams
+	}
+	return nil
+}
+
+// ForSignature extracts the (possibly empty) type parameter object list from
+// sig.
+func ForSignature(sig *types.Signature) []*types.TypeName {
+	return tparamsSlice(sig.TParams())
+}
+
+// IsComparable reports if iface is the comparable interface.
+func IsComparable(iface *types.Interface) bool {
+	return iface.IsComparable()
+}
+
+// IsConstraint reports whether iface may only be used as a type parameter
+// constraint (i.e. has a type set or is the comparable interface).
+func IsConstraint(iface *types.Interface) bool {
+	return iface.IsConstraint()
+}
+
+// ForNamed extracts the (possibly empty) type parameter object list from
+// named.
+func ForNamed(named *types.Named) []*types.TypeName {
+	return tparamsSlice(named.TParams())
+}
+
+func tparamsSlice(tparams *types.TypeParams) []*types.TypeName {
+	if tparams.Len() == 0 {
+		return nil
+	}
+	result := make([]*types.TypeName, tparams.Len())
+	for i := 0; i < tparams.Len(); i++ {
+		result[i] = tparams.At(i)
+	}
+	return result
+}
+
+// NamedTArgs extracts the (possibly empty) type argument list from named.
+func NamedTArgs(named *types.Named) []types.Type {
+	return named.TArgs()
+}
+
+// InitInferred initializes info to record inferred type information.
+func InitInferred(info *types.Info) {
+	info.Inferred = make(map[ast.Expr]types.Inferred)
+}
+
+// GetInferred extracts inferred type information from info for e.
+//
+// The expression e may have an inferred type if it is an *ast.IndexExpr
+// representing partial instantiation of a generic function type for which type
+// arguments have been inferred using constraint type inference, or if it is an
+// *ast.CallExpr for which type type arguments have be inferred using both
+// constraint type inference and function argument inference.
+func GetInferred(info *types.Info, e ast.Expr) ([]types.Type, *types.Signature) {
+	if info.Inferred == nil {
+		return nil, nil
+	}
+	inf := info.Inferred[e]
+	return inf.TArgs, inf.Sig
+}
diff --git a/src/cmd/vendor/modules.txt b/src/cmd/vendor/modules.txt
index 34dbdaf..c98bdcd 100644
--- a/src/cmd/vendor/modules.txt
+++ b/src/cmd/vendor/modules.txt
@@ -48,7 +48,7 @@
 # golang.org/x/term v0.0.0-20210503060354-a79de5458b56
 ## explicit; go 1.17
 golang.org/x/term
-# golang.org/x/tools v0.1.2-0.20210519160823-49064d2332f9
+# golang.org/x/tools v0.1.6-0.20210809225032-337cebd2c151
 ## explicit; go 1.17
 golang.org/x/tools/cover
 golang.org/x/tools/go/analysis
@@ -92,6 +92,7 @@
 golang.org/x/tools/go/types/typeutil
 golang.org/x/tools/internal/analysisinternal
 golang.org/x/tools/internal/lsp/fuzzy
+golang.org/x/tools/internal/typeparams
 # golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1
 ## explicit; go 1.11
 golang.org/x/xerrors
diff --git a/src/cmd/vet/testdata/print/print.go b/src/cmd/vet/testdata/print/print.go
index fca5949..46240e8 100644
--- a/src/cmd/vet/testdata/print/print.go
+++ b/src/cmd/vet/testdata/print/print.go
@@ -491,10 +491,10 @@
 func (s recursiveStringer) String() string {
 	_ = fmt.Sprintf("%d", s)
 	_ = fmt.Sprintf("%#v", s)
-	_ = fmt.Sprintf("%v", s)  // ERROR "Sprintf format %v with arg s causes recursive String method call"
-	_ = fmt.Sprintf("%v", &s) // ERROR "Sprintf format %v with arg &s causes recursive String method call"
+	_ = fmt.Sprintf("%v", s)  // ERROR "Sprintf format %v with arg s causes recursive .*String method call"
+	_ = fmt.Sprintf("%v", &s) // ERROR "Sprintf format %v with arg &s causes recursive .*String method call"
 	_ = fmt.Sprintf("%T", s)  // ok; does not recursively call String
-	return fmt.Sprintln(s)    // ERROR "Sprintln arg s causes recursive call to String method"
+	return fmt.Sprintln(s)    // ERROR "Sprintln arg s causes recursive call to .*String method"
 }
 
 type recursivePtrStringer int
@@ -502,7 +502,7 @@
 func (p *recursivePtrStringer) String() string {
 	_ = fmt.Sprintf("%v", *p)
 	_ = fmt.Sprint(&p)     // ok; prints address
-	return fmt.Sprintln(p) // ERROR "Sprintln arg p causes recursive call to String method"
+	return fmt.Sprintln(p) // ERROR "Sprintln arg p causes recursive call to .*String method"
 }
 
 type BoolFormatter bool
diff --git a/src/go.mod b/src/go.mod
index 379dcf5..1fb8cbf 100644
--- a/src/go.mod
+++ b/src/go.mod
@@ -1,6 +1,6 @@
 module std
 
-go 1.17
+go 1.18
 
 require (
 	golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e
diff --git a/src/go.sum b/src/go.sum
index 6e869b9..b3de6c5 100644
--- a/src/go.sum
+++ b/src/go.sum
@@ -1,15 +1,8 @@
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e h1:8foAy0aoO5GkqCvAEJ4VC4P3zksTg4X4aJCDpZzmgQI=
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e/go.mod h1:P+XmwS30IXTQdn5tA2iutPOUgjI07+tq3H3K9MVA1s8=
-golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210510120150-4163338589ed h1:p9UgmWI9wKpfYmgaV/IZKGdXc5qEK45tDwwwDyjS26I=
 golang.org/x/net v0.0.0-20210510120150-4163338589ed/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744 h1:yhBbb4IRs2HS9PPlAg6DMC6mUOKexJBNsLf4Z+6En1Q=
 golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7-0.20210503195748-5c7c50ebbd4f h1:yQJrRE0hDxDFmZLlRaw+3vusO4fwNHgHIjUOMO7bHYI=
 golang.org/x/text v0.3.7-0.20210503195748-5c7c50ebbd4f/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
-golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
diff --git a/src/go/ast/ast.go b/src/go/ast/ast.go
index 337c87f..b0f1330 100644
--- a/src/go/ast/ast.go
+++ b/src/go/ast/ast.go
@@ -344,6 +344,15 @@
 		Rbrack token.Pos // position of "]"
 	}
 
+	// A MultiIndexExpr node represents an expression followed by multiple
+	// indices.
+	MultiIndexExpr struct {
+		X       Expr      // expression
+		Lbrack  token.Pos // position of "["
+		Indices []Expr    // index expressions
+		Rbrack  token.Pos // position of "]"
+	}
+
 	// A SliceExpr node represents an expression followed by slice indices.
 	SliceExpr struct {
 		X      Expr      // expression
@@ -440,6 +449,14 @@
 
 	// Pointer types are represented via StarExpr nodes.
 
+	// A FuncType node represents a function type.
+	FuncType struct {
+		Func    token.Pos  // position of "func" keyword (token.NoPos if there is no "func")
+		TParams *FieldList // type parameters; or nil
+		Params  *FieldList // (incoming) parameters; non-nil
+		Results *FieldList // (outgoing) results; or nil
+	}
+
 	// An InterfaceType node represents an interface type.
 	InterfaceType struct {
 		Interface  token.Pos  // position of "interface" keyword
@@ -479,6 +496,7 @@
 func (x *ParenExpr) Pos() token.Pos      { return x.Lparen }
 func (x *SelectorExpr) Pos() token.Pos   { return x.X.Pos() }
 func (x *IndexExpr) Pos() token.Pos      { return x.X.Pos() }
+func (x *MultiIndexExpr) Pos() token.Pos { return x.X.Pos() }
 func (x *SliceExpr) Pos() token.Pos      { return x.X.Pos() }
 func (x *TypeAssertExpr) Pos() token.Pos { return x.X.Pos() }
 func (x *CallExpr) Pos() token.Pos       { return x.Fun.Pos() }
@@ -512,6 +530,7 @@
 func (x *ParenExpr) End() token.Pos      { return x.Rparen + 1 }
 func (x *SelectorExpr) End() token.Pos   { return x.Sel.End() }
 func (x *IndexExpr) End() token.Pos      { return x.Rbrack + 1 }
+func (x *MultiIndexExpr) End() token.Pos { return x.Rbrack + 1 }
 func (x *SliceExpr) End() token.Pos      { return x.Rbrack + 1 }
 func (x *TypeAssertExpr) End() token.Pos { return x.Rparen + 1 }
 func (x *CallExpr) End() token.Pos       { return x.Rparen + 1 }
@@ -543,6 +562,7 @@
 func (*ParenExpr) exprNode()      {}
 func (*SelectorExpr) exprNode()   {}
 func (*IndexExpr) exprNode()      {}
+func (*MultiIndexExpr) exprNode() {}
 func (*SliceExpr) exprNode()      {}
 func (*TypeAssertExpr) exprNode() {}
 func (*CallExpr) exprNode()       {}
@@ -892,6 +912,16 @@
 		Values  []Expr        // initial values; or nil
 		Comment *CommentGroup // line comments; or nil
 	}
+
+	// A TypeSpec node represents a type declaration (TypeSpec production).
+	TypeSpec struct {
+		Doc     *CommentGroup // associated documentation; or nil
+		Name    *Ident        // type name
+		TParams *FieldList    // type parameters; or nil
+		Assign  token.Pos     // position of '=', if any
+		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
+		Comment *CommentGroup // line comments; or nil
+	}
 )
 
 // Pos and End implementations for spec nodes.
diff --git a/src/go/ast/ast_notypeparams.go b/src/go/ast/ast_notypeparams.go
deleted file mode 100644
index fa132fb..0000000
--- a/src/go/ast/ast_notypeparams.go
+++ /dev/null
@@ -1,28 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !typeparams
-// +build !typeparams
-
-package ast
-
-import "go/token"
-
-type (
-	// A FuncType node represents a function type.
-	FuncType struct {
-		Func    token.Pos  // position of "func" keyword (token.NoPos if there is no "func")
-		Params  *FieldList // (incoming) parameters; non-nil
-		Results *FieldList // (outgoing) results; or nil
-	}
-
-	// A TypeSpec node represents a type declaration (TypeSpec production).
-	TypeSpec struct {
-		Doc     *CommentGroup // associated documentation; or nil
-		Name    *Ident        // type name
-		Assign  token.Pos     // position of '=', if any
-		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
-		Comment *CommentGroup // line comments; or nil
-	}
-)
diff --git a/src/go/ast/ast_typeparams.go b/src/go/ast/ast_typeparams.go
deleted file mode 100644
index 24fdc5f..0000000
--- a/src/go/ast/ast_typeparams.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build typeparams
-// +build typeparams
-
-package ast
-
-import "go/token"
-
-type (
-	// A FuncType node represents a function type.
-	FuncType struct {
-		Func    token.Pos  // position of "func" keyword (token.NoPos if there is no "func")
-		TParams *FieldList // type parameters; or nil
-		Params  *FieldList // (incoming) parameters; non-nil
-		Results *FieldList // (outgoing) results; or nil
-	}
-
-	// A TypeSpec node represents a type declaration (TypeSpec production).
-	TypeSpec struct {
-		Doc     *CommentGroup // associated documentation; or nil
-		Name    *Ident        // type name
-		TParams *FieldList    // type parameters; or nil
-		Assign  token.Pos     // position of '=', if any
-		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
-		Comment *CommentGroup // line comments; or nil
-	}
-
-	// A ListExpr node represents a list of expressions separated by commas.
-	// ListExpr nodes are used as index in IndexExpr nodes representing type
-	// or function instantiations with more than one type argument.
-	ListExpr struct {
-		ElemList []Expr
-	}
-)
-
-func (*ListExpr) exprNode() {}
-func (x *ListExpr) Pos() token.Pos {
-	if len(x.ElemList) > 0 {
-		return x.ElemList[0].Pos()
-	}
-	return token.NoPos
-}
-func (x *ListExpr) End() token.Pos {
-	if len(x.ElemList) > 0 {
-		return x.ElemList[len(x.ElemList)-1].End()
-	}
-	return token.NoPos
-}
diff --git a/src/go/ast/walk.go b/src/go/ast/walk.go
index 9224264..c8abc40 100644
--- a/src/go/ast/walk.go
+++ b/src/go/ast/walk.go
@@ -4,6 +4,8 @@
 
 package ast
 
+import "fmt"
+
 // A Visitor's Visit method is invoked for each node encountered by Walk.
 // If the result visitor w is not nil, Walk visits each of the children
 // of node with the visitor w, followed by a call of w.Visit(nil).
@@ -114,6 +116,12 @@
 		Walk(v, n.X)
 		Walk(v, n.Index)
 
+	case *MultiIndexExpr:
+		Walk(v, n.X)
+		for _, index := range n.Indices {
+			Walk(v, index)
+		}
+
 	case *SliceExpr:
 		Walk(v, n.X)
 		if n.Low != nil {
@@ -161,7 +169,9 @@
 		Walk(v, n.Fields)
 
 	case *FuncType:
-		walkFuncTypeParams(v, n)
+		if n.TParams != nil {
+			Walk(v, n.TParams)
+		}
 		if n.Params != nil {
 			Walk(v, n.Params)
 		}
@@ -316,7 +326,9 @@
 			Walk(v, n.Doc)
 		}
 		Walk(v, n.Name)
-		walkTypeSpecParams(v, n)
+		if n.TParams != nil {
+			Walk(v, n.TParams)
+		}
 		Walk(v, n.Type)
 		if n.Comment != nil {
 			Walk(v, n.Comment)
@@ -363,7 +375,7 @@
 		}
 
 	default:
-		walkOtherNodes(v, n)
+		panic(fmt.Sprintf("ast.Walk: unexpected node type %T", n))
 	}
 
 	v.Visit(nil)
diff --git a/src/go/ast/walk_notypeparams.go b/src/go/ast/walk_notypeparams.go
deleted file mode 100644
index d43e13d..0000000
--- a/src/go/ast/walk_notypeparams.go
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !typeparams
-// +build !typeparams
-
-package ast
-
-import "fmt"
-
-func walkFuncTypeParams(v Visitor, n *FuncType) {}
-func walkTypeSpecParams(v Visitor, n *TypeSpec) {}
-
-func walkOtherNodes(v Visitor, n Node) {
-	panic(fmt.Sprintf("ast.Walk: unexpected node type %T", n))
-}
diff --git a/src/go/ast/walk_typeparams.go b/src/go/ast/walk_typeparams.go
deleted file mode 100644
index b662133..0000000
--- a/src/go/ast/walk_typeparams.go
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build typeparams
-// +build typeparams
-
-package ast
-
-import (
-	"fmt"
-)
-
-func walkFuncTypeParams(v Visitor, n *FuncType) {
-	if n.TParams != nil {
-		Walk(v, n.TParams)
-	}
-}
-
-func walkTypeSpecParams(v Visitor, n *TypeSpec) {
-	if n.TParams != nil {
-		Walk(v, n.TParams)
-	}
-}
-
-func walkOtherNodes(v Visitor, n Node) {
-	if e, ok := n.(*ListExpr); ok {
-		if e != nil {
-			for _, elem := range e.ElemList {
-				Walk(v, elem)
-			}
-		}
-	} else {
-		panic(fmt.Sprintf("ast.Walk: unexpected node type %T", n))
-	}
-}
diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index 45e2f25..80f8e1a 100644
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -71,17 +71,19 @@
 	# No dependencies allowed for any of these packages.
 	NONE
 	< container/list, container/ring,
-	  internal/cfg, internal/cpu, internal/goexperiment,
+	  internal/cfg, internal/cpu, internal/goarch,
+	  internal/goexperiment, internal/goos,
 	  internal/goversion, internal/nettrace,
 	  unicode/utf8, unicode/utf16, unicode,
 	  unsafe;
 
-	# These packages depend only on unsafe.
-	unsafe
+	# These packages depend only on internal/goarch and unsafe.
+	internal/goarch, unsafe
 	< internal/abi;
 
 	# RUNTIME is the core runtime group of packages, all of them very light-weight.
-	internal/abi, internal/cpu, internal/goexperiment, unsafe
+	internal/abi, internal/cpu, internal/goarch,
+	internal/goexperiment, internal/goos, unsafe
 	< internal/bytealg
 	< internal/itoa
 	< internal/unsafeheader
diff --git a/src/go/constant/kind_string.go b/src/go/constant/kind_string.go
new file mode 100644
index 0000000..7003325
--- /dev/null
+++ b/src/go/constant/kind_string.go
@@ -0,0 +1,28 @@
+// Code generated by "stringer -type Kind"; DO NOT EDIT.
+
+package constant
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[Unknown-0]
+	_ = x[Bool-1]
+	_ = x[String-2]
+	_ = x[Int-3]
+	_ = x[Float-4]
+	_ = x[Complex-5]
+}
+
+const _Kind_name = "UnknownBoolStringIntFloatComplex"
+
+var _Kind_index = [...]uint8{0, 7, 11, 17, 20, 25, 32}
+
+func (i Kind) String() string {
+	if i < 0 || i >= Kind(len(_Kind_index)-1) {
+		return "Kind(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Kind_name[_Kind_index[i]:_Kind_index[i+1]]
+}
diff --git a/src/go/constant/value.go b/src/go/constant/value.go
index 78cb3f8..014e873 100644
--- a/src/go/constant/value.go
+++ b/src/go/constant/value.go
@@ -24,6 +24,8 @@
 	"unicode/utf8"
 )
 
+//go:generate stringer -type Kind
+
 // Kind specifies the kind of value represented by a Value.
 type Kind int
 
diff --git a/src/go/internal/gcimporter/gcimporter_test.go b/src/go/internal/gcimporter/gcimporter_test.go
index 3c76aaf..286b8a6 100644
--- a/src/go/internal/gcimporter/gcimporter_test.go
+++ b/src/go/internal/gcimporter/gcimporter_test.go
@@ -138,6 +138,7 @@
 	skipSpecialPlatforms(t)
 
 	// This package only handles gc export data.
+	// Disable test until we put in the new export version.
 	if runtime.Compiler != "gc" {
 		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
 	}
diff --git a/src/go/internal/gcimporter/iimport.go b/src/go/internal/gcimporter/iimport.go
index 76d47d0..dbc9b3a 100644
--- a/src/go/internal/gcimporter/iimport.go
+++ b/src/go/internal/gcimporter/iimport.go
@@ -41,6 +41,16 @@
 	return i
 }
 
+// Keep this in sync with constants in iexport.go.
+const (
+	iexportVersionGo1_11 = 0
+	iexportVersionPosCol = 1
+	// TODO: before release, change this back to 2.
+	iexportVersionGenerics = iexportVersionPosCol
+
+	iexportVersionCurrent = iexportVersionGenerics
+)
+
 const predeclReserved = 32
 
 type itag uint64
@@ -56,6 +66,8 @@
 	signatureType
 	structType
 	interfaceType
+	typeParamType
+	instType
 )
 
 // iImportData imports a package from the serialized package data
@@ -63,7 +75,7 @@
 // If the export data version is not recognized or the format is otherwise
 // compromised, an error is returned.
 func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataReader *bufio.Reader, path string) (pkg *types.Package, err error) {
-	const currentVersion = 1
+	const currentVersion = iexportVersionCurrent
 	version := int64(-1)
 	defer func() {
 		if e := recover(); e != nil {
@@ -79,9 +91,13 @@
 
 	version = int64(r.uint64())
 	switch version {
-	case currentVersion, 0:
+	case /* iexportVersionGenerics, */ iexportVersionPosCol, iexportVersionGo1_11:
 	default:
-		errorf("unknown iexport format version %d", version)
+		if version > iexportVersionGenerics {
+			errorf("unstable iexport format version %d, just rebuild compiler and std library", version)
+		} else {
+			errorf("unknown iexport format version %d", version)
+		}
 	}
 
 	sLen := int64(r.uint64())
@@ -95,8 +111,9 @@
 	declData := data[sLen:]
 
 	p := iimporter{
-		ipath:   path,
-		version: int(version),
+		exportVersion: version,
+		ipath:         path,
+		version:       int(version),
 
 		stringData:  stringData,
 		stringCache: make(map[uint64]string),
@@ -172,8 +189,9 @@
 }
 
 type iimporter struct {
-	ipath   string
-	version int
+	exportVersion int64
+	ipath         string
+	version       int
 
 	stringData  []byte
 	stringCache map[uint64]string
@@ -276,6 +294,9 @@
 
 		r.declare(types.NewFunc(pos, r.currPkg, name, sig))
 
+	case 'G':
+		errorf("unexpected parameterized function/method")
+
 	case 'T':
 		// Types can be recursive. We need to setup a stub
 		// declaration before recursing.
@@ -297,6 +318,9 @@
 			}
 		}
 
+	case 'U':
+		errorf("unexpected parameterized type")
+
 	case 'V':
 		typ := r.typ()
 
@@ -549,6 +573,14 @@
 		typ := types.NewInterfaceType(methods, embeddeds)
 		r.p.interfaceList = append(r.p.interfaceList, typ)
 		return typ
+
+	case typeParamType:
+		errorf("do not handle type param types yet")
+		return nil
+
+	case instType:
+		errorf("do not handle instantiated types yet")
+		return nil
 	}
 }
 
diff --git a/src/go/internal/gcimporter/support.go b/src/go/internal/gcimporter/support.go
index b8bb14d..09810dd 100644
--- a/src/go/internal/gcimporter/support.go
+++ b/src/go/internal/gcimporter/support.go
@@ -122,6 +122,9 @@
 
 	// used internally by gc; never used by this package or in .a files
 	anyType{},
+
+	// comparable
+	types.Universe.Lookup("comparable").Type(),
 }
 
 type anyType struct{}
diff --git a/src/go/internal/typeparams/notypeparams.go b/src/go/internal/typeparams/notypeparams.go
deleted file mode 100644
index 2ceafaa..0000000
--- a/src/go/internal/typeparams/notypeparams.go
+++ /dev/null
@@ -1,40 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !typeparams
-// +build !typeparams
-
-package typeparams
-
-import (
-	"go/ast"
-)
-
-const Enabled = false
-
-func PackExpr(list []ast.Expr) ast.Expr {
-	switch len(list) {
-	case 1:
-		return list[0]
-	default:
-		// The parser should not attempt to pack multiple expressions into an
-		// IndexExpr if type params are disabled.
-		panic("multiple index expressions are unsupported without type params")
-	}
-}
-
-func UnpackExpr(expr ast.Expr) []ast.Expr {
-	return []ast.Expr{expr}
-}
-
-func IsListExpr(n ast.Node) bool {
-	return false
-}
-
-func Get(ast.Node) *ast.FieldList {
-	return nil
-}
-
-func Set(node ast.Node, params *ast.FieldList) {
-}
diff --git a/src/go/internal/typeparams/typeparams.go b/src/go/internal/typeparams/typeparams.go
index 871e95d..3191654 100644
--- a/src/go/internal/typeparams/typeparams.go
+++ b/src/go/internal/typeparams/typeparams.go
@@ -2,50 +2,59 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
 package typeparams
 
 import (
 	"fmt"
 	"go/ast"
+	"go/token"
 )
 
-const Enabled = true
-
-func PackExpr(list []ast.Expr) ast.Expr {
-	switch len(list) {
+func PackIndexExpr(x ast.Expr, lbrack token.Pos, exprs []ast.Expr, rbrack token.Pos) ast.Expr {
+	switch len(exprs) {
 	case 0:
-		// Return an empty ListExpr here, rather than nil, as IndexExpr.Index must
-		// never be nil.
-		// TODO(rFindley) would a BadExpr be more appropriate here?
-		return &ast.ListExpr{}
+		panic("internal error: PackIndexExpr with empty expr slice")
 	case 1:
-		return list[0]
+		return &ast.IndexExpr{
+			X:      x,
+			Lbrack: lbrack,
+			Index:  exprs[0],
+			Rbrack: rbrack,
+		}
 	default:
-		return &ast.ListExpr{ElemList: list}
+		return &ast.MultiIndexExpr{
+			X:       x,
+			Lbrack:  lbrack,
+			Indices: exprs,
+			Rbrack:  rbrack,
+		}
 	}
 }
 
-// TODO(gri) Should find a more efficient solution that doesn't
-//           require introduction of a new slice for simple
-//           expressions.
-func UnpackExpr(x ast.Expr) []ast.Expr {
-	if x, _ := x.(*ast.ListExpr); x != nil {
-		return x.ElemList
-	}
-	if x != nil {
-		return []ast.Expr{x}
+// IndexExpr wraps an ast.IndexExpr or ast.MultiIndexExpr into the
+// MultiIndexExpr interface.
+//
+// Orig holds the original ast.Expr from which this IndexExpr was derived.
+type IndexExpr struct {
+	Orig ast.Expr // the wrapped expr, which may be distinct from MultiIndexExpr below.
+	*ast.MultiIndexExpr
+}
+
+func UnpackIndexExpr(n ast.Node) *IndexExpr {
+	switch e := n.(type) {
+	case *ast.IndexExpr:
+		return &IndexExpr{e, &ast.MultiIndexExpr{
+			X:       e.X,
+			Lbrack:  e.Lbrack,
+			Indices: []ast.Expr{e.Index},
+			Rbrack:  e.Rbrack,
+		}}
+	case *ast.MultiIndexExpr:
+		return &IndexExpr{e, e}
 	}
 	return nil
 }
 
-func IsListExpr(n ast.Node) bool {
-	_, ok := n.(*ast.ListExpr)
-	return ok
-}
-
 func Get(n ast.Node) *ast.FieldList {
 	switch n := n.(type) {
 	case *ast.TypeSpec:
diff --git a/src/go/parser/error_test.go b/src/go/parser/error_test.go
index f4f0a52..f35ba0b 100644
--- a/src/go/parser/error_test.go
+++ b/src/go/parser/error_test.go
@@ -186,16 +186,14 @@
 	}
 	for _, d := range list {
 		name := d.Name()
-		if !d.IsDir() && !strings.HasPrefix(name, ".") && (strings.HasSuffix(name, ".src") || strings.HasSuffix(name, ".go2")) {
-			mode := DeclarationErrors | AllErrors
-			if strings.HasSuffix(name, ".go2") {
-				if !typeparams.Enabled {
-					continue
+		t.Run(name, func(t *testing.T) {
+			if !d.IsDir() && !strings.HasPrefix(name, ".") && (strings.HasSuffix(name, ".src") || strings.HasSuffix(name, ".go2")) {
+				mode := DeclarationErrors | AllErrors
+				if !strings.HasSuffix(name, ".go2") {
+					mode |= typeparams.DisallowParsing
 				}
-			} else {
-				mode |= typeparams.DisallowParsing
+				checkErrors(t, filepath.Join(testdata, name), nil, mode, true)
 			}
-			checkErrors(t, filepath.Join(testdata, name), nil, mode, true)
-		}
+		})
 	}
 }
diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index f10c865..bdc2ad3 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -77,7 +77,7 @@
 }
 
 func (p *parser) parseTypeParams() bool {
-	return typeparams.Enabled && p.mode&typeparams.DisallowParsing == 0
+	return p.mode&typeparams.DisallowParsing == 0
 }
 
 // ----------------------------------------------------------------------------
@@ -600,7 +600,7 @@
 	}
 
 	// x[P], x[P1, P2], ...
-	return nil, &ast.IndexExpr{X: x, Lbrack: lbrack, Index: typeparams.PackExpr(args), Rbrack: rbrack}
+	return nil, typeparams.PackIndexExpr(x, lbrack, args, rbrack)
 }
 
 func (p *parser) parseFieldDecl() *ast.Field {
@@ -980,6 +980,7 @@
 				list := []ast.Expr{x}
 				if p.atComma("type argument list", token.RBRACK) {
 					p.exprLev++
+					p.next()
 					for p.tok != token.RBRACK && p.tok != token.EOF {
 						list = append(list, p.parseType())
 						if !p.atComma("type argument list", token.RBRACK) {
@@ -990,7 +991,7 @@
 					p.exprLev--
 				}
 				rbrack := p.expectClosing(token.RBRACK, "type argument list")
-				typ = &ast.IndexExpr{X: ident, Lbrack: lbrack, Index: typeparams.PackExpr(list), Rbrack: rbrack}
+				typ = typeparams.PackIndexExpr(ident, lbrack, list, rbrack)
 			}
 		case p.tok == token.LPAREN:
 			// ordinary method
@@ -1011,11 +1012,56 @@
 			typ = p.parseTypeInstance(typ)
 		}
 	}
-	p.expectSemi() // call before accessing p.linecomment
 
-	spec := &ast.Field{Doc: doc, Names: idents, Type: typ, Comment: p.lineComment}
+	// Comment is added at the callsite: the field below may joined with
+	// additional type specs using '|'.
+	// TODO(rfindley) this should be refactored.
+	// TODO(rfindley) add more tests for comment handling.
+	return &ast.Field{Doc: doc, Names: idents, Type: typ}
+}
 
-	return spec
+func (p *parser) embeddedElem(f *ast.Field) *ast.Field {
+	if p.trace {
+		defer un(trace(p, "EmbeddedElem"))
+	}
+	if f == nil {
+		f = new(ast.Field)
+		f.Type = p.embeddedTerm()
+	}
+	for p.tok == token.OR {
+		t := new(ast.BinaryExpr)
+		t.OpPos = p.pos
+		t.Op = token.OR
+		p.next()
+		t.X = f.Type
+		t.Y = p.embeddedTerm()
+		f.Type = t
+	}
+	return f
+}
+
+func (p *parser) embeddedTerm() ast.Expr {
+	if p.trace {
+		defer un(trace(p, "EmbeddedTerm"))
+	}
+	if p.tok == token.TILDE {
+		t := new(ast.UnaryExpr)
+		t.OpPos = p.pos
+		t.Op = token.TILDE
+		p.next()
+		t.X = p.parseType()
+		return t
+	}
+
+	t := p.tryIdentOrType()
+	if t == nil {
+		pos := p.pos
+		p.errorExpected(pos, "~ term or type")
+		p.advance(exprEnd)
+		return &ast.BadExpr{From: pos, To: p.pos}
+	}
+
+	return t
 }
 
 func (p *parser) parseInterfaceType() *ast.InterfaceType {
@@ -1025,11 +1071,28 @@
 
 	pos := p.expect(token.INTERFACE)
 	lbrace := p.expect(token.LBRACE)
+
 	var list []*ast.Field
-	for p.tok == token.IDENT || p.parseTypeParams() && p.tok == token.TYPE {
-		if p.tok == token.IDENT {
-			list = append(list, p.parseMethodSpec())
-		} else {
+
+parseElements:
+	for {
+		switch {
+		case p.tok == token.IDENT:
+			f := p.parseMethodSpec()
+			if f.Names == nil && p.parseTypeParams() {
+				f = p.embeddedElem(f)
+			}
+			p.expectSemi()
+			f.Comment = p.lineComment
+			list = append(list, f)
+		case p.tok == token.TILDE && p.parseTypeParams():
+			f := p.embeddedElem(nil)
+			p.expectSemi()
+			f.Comment = p.lineComment
+			list = append(list, f)
+		case p.tok == token.TYPE && p.parseTypeParams():
+			// TODO(rfindley): remove TypeList syntax and refactor the clauses above.
+
 			// all types in a type list share the same field name "type"
 			// (since type is a keyword, a Go program cannot have that field name)
 			name := []*ast.Ident{{NamePos: p.pos, Name: "type"}}
@@ -1039,8 +1102,22 @@
 				list = append(list, &ast.Field{Names: name, Type: typ})
 			}
 			p.expectSemi()
+		case p.parseTypeParams():
+			if t := p.tryIdentOrType(); t != nil {
+				f := new(ast.Field)
+				f.Type = t
+				f = p.embeddedElem(f)
+				p.expectSemi()
+				f.Comment = p.lineComment
+				list = append(list, f)
+			} else {
+				break parseElements
+			}
+		default:
+			break parseElements
 		}
 	}
+
 	// TODO(rfindley): the error produced here could be improved, since we could
 	// accept a identifier, 'type', or a '}' at this point.
 	rbrace := p.expect(token.RBRACE)
@@ -1101,7 +1178,6 @@
 	}
 
 	opening := p.expect(token.LBRACK)
-
 	p.exprLev++
 	var list []ast.Expr
 	for p.tok != token.RBRACK && p.tok != token.EOF {
@@ -1115,7 +1191,17 @@
 
 	closing := p.expectClosing(token.RBRACK, "type argument list")
 
-	return &ast.IndexExpr{X: typ, Lbrack: opening, Index: typeparams.PackExpr(list), Rbrack: closing}
+	if len(list) == 0 {
+		p.errorExpected(closing, "type argument list")
+		return &ast.IndexExpr{
+			X:      typ,
+			Lbrack: opening,
+			Index:  &ast.BadExpr{From: opening + 1, To: closing},
+			Rbrack: closing,
+		}
+	}
+
+	return typeparams.PackIndexExpr(typ, opening, list, closing)
 }
 
 func (p *parser) tryIdentOrType() ast.Expr {
@@ -1378,7 +1464,7 @@
 	}
 
 	// instance expression
-	return &ast.IndexExpr{X: x, Lbrack: lbrack, Index: typeparams.PackExpr(args), Rbrack: rbrack}
+	return typeparams.PackIndexExpr(x, lbrack, args, rbrack)
 }
 
 func (p *parser) parseCallOrConversion(fun ast.Expr) *ast.CallExpr {
@@ -1480,6 +1566,7 @@
 		panic("unreachable")
 	case *ast.SelectorExpr:
 	case *ast.IndexExpr:
+	case *ast.MultiIndexExpr:
 	case *ast.SliceExpr:
 	case *ast.TypeAssertExpr:
 		// If t.Type == nil we have a type assertion of the form
@@ -1569,7 +1656,7 @@
 					return
 				}
 				// x is possibly a composite literal type
-			case *ast.IndexExpr:
+			case *ast.IndexExpr, *ast.MultiIndexExpr:
 				if p.exprLev < 0 {
 					return
 				}
diff --git a/src/go/parser/resolver_test.go b/src/go/parser/resolver_test.go
index 625c009..0c06c59 100644
--- a/src/go/parser/resolver_test.go
+++ b/src/go/parser/resolver_test.go
@@ -41,11 +41,7 @@
 			path := filepath.Join(dir, fi.Name())
 			src := readFile(path) // panics on failure
 			var mode Mode
-			if strings.HasSuffix(path, ".go2") {
-				if !typeparams.Enabled {
-					t.Skip("type params are not enabled")
-				}
-			} else {
+			if !strings.HasSuffix(path, ".go2") {
 				mode |= typeparams.DisallowParsing
 			}
 			file, err := ParseFile(fset, path, src, mode)
diff --git a/src/go/parser/short_test.go b/src/go/parser/short_test.go
index 67fef15..bfc6f67 100644
--- a/src/go/parser/short_test.go
+++ b/src/go/parser/short_test.go
@@ -133,9 +133,6 @@
 		}
 	})
 	t.Run("tparams", func(t *testing.T) {
-		if !typeparams.Enabled {
-			t.Skip("type params are not enabled")
-		}
 		for _, src := range valids {
 			checkErrors(t, src, src, DeclarationErrors|AllErrors, false)
 		}
@@ -200,10 +197,12 @@
 	`package p; func (type /* ERROR "found 'type'" */ T)(T) _()`,
 	`package p; type _[A+B, /* ERROR "expected ']'" */ ] int`,
 
-	// TODO: this error should be positioned on the ':'
+	// TODO(rfindley): this error should be positioned on the ':'
 	`package p; var a = a[[]int:[ /* ERROR "expected expression" */ ]int];`,
-	// TODO: the compiler error is better here: "cannot parenthesize embedded type"
-	`package p; type I1 interface{}; type I2 interface{ (/* ERROR "expected '}', found '\('" */ I1) }`,
+
+	// TODO(rfindley): the compiler error is better here: "cannot parenthesize embedded type"
+	// TODO(rfindley): confirm that parenthesized types should now be accepted.
+	// `package p; type I1 interface{}; type I2 interface{ (/* ERROR "expected '}', found '\('" */ I1) }`,
 
 	// issue 8656
 	`package p; func f() (a b string /* ERROR "missing ','" */ , ok bool)`,
@@ -266,9 +265,6 @@
 		}
 	})
 	t.Run("tparams", func(t *testing.T) {
-		if !typeparams.Enabled {
-			t.Skip("type params are not enabled")
-		}
 		for _, src := range invalids {
 			checkErrors(t, src, src, DeclarationErrors|AllErrors, true)
 		}
diff --git a/src/go/parser/testdata/interface.go2 b/src/go/parser/testdata/interface.go2
new file mode 100644
index 0000000..b399d75
--- /dev/null
+++ b/src/go/parser/testdata/interface.go2
@@ -0,0 +1,80 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains test cases for interfaces containing
+// constraint elements.
+//
+// For now, we accept both ordinary type lists and the
+// more complex constraint elements.
+
+package p
+
+type _ interface {
+	m()
+	type int
+	type int, string
+	E
+}
+
+type _ interface {
+	m()
+	~int
+	int | string
+	int | ~string
+	~int | ~string
+}
+
+type _ interface {
+	m()
+	~int
+	T[int, string] | string
+	int | ~T[string, struct{}]
+	~int | ~string
+	type bool, int, float64
+}
+
+type _ interface {
+	int
+	[]byte
+	[10]int
+	struct{}
+	*int
+	func()
+	interface{}
+	map[string]int
+	chan T
+	chan<- T
+	<-chan T
+	T[int]
+}
+
+type _ interface {
+	int | string
+	[]byte | string
+	[10]int | string
+	struct{} | string
+	*int | string
+	func() | string
+	interface{} | string
+	map[string]int | string
+	chan T | string
+	chan<- T | string
+	<-chan T | string
+	T[int] | string
+}
+
+type _ interface {
+	~int | string
+	~[]byte | string
+	~[10]int | string
+	~struct{} | string
+	~*int | string
+	~func() | string
+	~interface{} | string
+	~map[string]int | string
+	~chan T | string
+	~chan<- T | string
+	~<-chan T | string
+	~T[int] | string
+}
diff --git a/src/go/printer/nodes.go b/src/go/printer/nodes.go
index 913281e..239fcbd 100644
--- a/src/go/printer/nodes.go
+++ b/src/go/printer/nodes.go
@@ -871,17 +871,15 @@
 		// TODO(gri): should treat[] like parentheses and undo one level of depth
 		p.expr1(x.X, token.HighestPrec, 1)
 		p.print(x.Lbrack, token.LBRACK)
-		// Note: we're a bit defensive here to handle the case of a ListExpr of
-		// length 1.
-		if list := typeparams.UnpackExpr(x.Index); len(list) > 0 {
-			if len(list) > 1 {
-				p.exprList(x.Lbrack, list, depth+1, commaTerm, x.Rbrack, false)
-			} else {
-				p.expr0(list[0], depth+1)
-			}
-		} else {
-			p.expr0(x.Index, depth+1)
-		}
+		p.expr0(x.Index, depth+1)
+		p.print(x.Rbrack, token.RBRACK)
+
+	case *ast.MultiIndexExpr:
+		// TODO(gri): as for IndexExpr, should treat [] like parentheses and undo
+		// one level of depth
+		p.expr1(x.X, token.HighestPrec, 1)
+		p.print(x.Lbrack, token.LBRACK)
+		p.exprList(x.Lbrack, x.Indices, depth+1, commaTerm, x.Rbrack, false)
 		p.print(x.Rbrack, token.RBRACK)
 
 	case *ast.SliceExpr:
diff --git a/src/go/printer/printer_test.go b/src/go/printer/printer_test.go
index 20c97b8..ff8be4a 100644
--- a/src/go/printer/printer_test.go
+++ b/src/go/printer/printer_test.go
@@ -10,7 +10,6 @@
 	"flag"
 	"fmt"
 	"go/ast"
-	"go/internal/typeparams"
 	"go/parser"
 	"go/token"
 	"io"
@@ -222,9 +221,6 @@
 func TestFiles(t *testing.T) {
 	t.Parallel()
 	for _, e := range data {
-		if !typeparams.Enabled && e.mode&allowTypeParams != 0 {
-			continue
-		}
 		source := filepath.Join(dataDir, e.source)
 		golden := filepath.Join(dataDir, e.golden)
 		mode := e.mode
diff --git a/src/go/scanner/scanner.go b/src/go/scanner/scanner.go
index f08e28c..ca4b526 100644
--- a/src/go/scanner/scanner.go
+++ b/src/go/scanner/scanner.go
@@ -969,6 +969,8 @@
 			}
 		case '|':
 			tok = s.switch3(token.OR, token.OR_ASSIGN, '|', token.LOR)
+		case '~':
+			tok = token.TILDE
 		default:
 			// next reports unexpected BOMs - don't repeat
 			if ch != bom {
diff --git a/src/go/scanner/scanner_test.go b/src/go/scanner/scanner_test.go
index db123c3..de45e16 100644
--- a/src/go/scanner/scanner_test.go
+++ b/src/go/scanner/scanner_test.go
@@ -40,7 +40,7 @@
 	class int
 }
 
-var tokens = [...]elt{
+var tokens = []elt{
 	// Special tokens
 	{token.COMMENT, "/* a comment */", special},
 	{token.COMMENT, "// a comment \n", special},
@@ -149,6 +149,7 @@
 	{token.RBRACE, "}", operator},
 	{token.SEMICOLON, ";", operator},
 	{token.COLON, ":", operator},
+	{token.TILDE, "~", operator},
 
 	// Keywords
 	{token.BREAK, "break", keyword},
diff --git a/src/go/token/token.go b/src/go/token/token.go
index 96a1079..d22e575 100644
--- a/src/go/token/token.go
+++ b/src/go/token/token.go
@@ -125,6 +125,11 @@
 	TYPE
 	VAR
 	keyword_end
+
+	additional_beg
+	// additional tokens, handled in an ad-hoc manner
+	TILDE
+	additional_end
 )
 
 var tokens = [...]string{
@@ -225,6 +230,8 @@
 	SWITCH: "switch",
 	TYPE:   "type",
 	VAR:    "var",
+
+	TILDE: "~",
 }
 
 // String returns the string corresponding to the token tok.
@@ -304,7 +311,9 @@
 // IsOperator returns true for tokens corresponding to operators and
 // delimiters; it returns false otherwise.
 //
-func (tok Token) IsOperator() bool { return operator_beg < tok && tok < operator_end }
+func (tok Token) IsOperator() bool {
+	return (operator_beg < tok && tok < operator_end) || tok == TILDE
+}
 
 // IsKeyword returns true for tokens corresponding to keywords;
 // it returns false otherwise.
diff --git a/src/go/types/api.go b/src/go/types/api.go
index 8c0d9d2..315f77f 100644
--- a/src/go/types/api.go
+++ b/src/go/types/api.go
@@ -34,6 +34,8 @@
 	"go/token"
 )
 
+const allowTypeLists = false
+
 // An Error describes a type-checking error; it implements the error interface.
 // A "soft" error is an error that still permits a valid interpretation of a
 // package (such as "unused variable"); "hard" errors may lead to unpredictable
@@ -101,12 +103,12 @@
 // A Config specifies the configuration for type checking.
 // The zero value for Config is a ready-to-use default configuration.
 type Config struct {
-	// goVersion describes the accepted Go language version. The string
+	// GoVersion describes the accepted Go language version. The string
 	// must follow the format "go%d.%d" (e.g. "go1.12") or it must be
 	// empty; an empty string indicates the latest language version.
 	// If the format is invalid, invoking the type checker will cause a
 	// panic.
-	goVersion string
+	GoVersion string
 
 	// If IgnoreFuncBodies is set, function bodies are not
 	// type-checked.
@@ -160,7 +162,101 @@
 	conf.go115UsesCgo = true
 }
 
-// The Info struct is found in api_notypeparams.go and api_typeparams.go.
+// Info holds result type information for a type-checked package.
+// Only the information for which a map is provided is collected.
+// If the package has type errors, the collected information may
+// be incomplete.
+type Info struct {
+	// Types maps expressions to their types, and for constant
+	// expressions, also their values. Invalid expressions are
+	// omitted.
+	//
+	// For (possibly parenthesized) identifiers denoting built-in
+	// functions, the recorded signatures are call-site specific:
+	// if the call result is not a constant, the recorded type is
+	// an argument-specific signature. Otherwise, the recorded type
+	// is invalid.
+	//
+	// The Types map does not record the type of every identifier,
+	// only those that appear where an arbitrary expression is
+	// permitted. For instance, the identifier f in a selector
+	// expression x.f is found only in the Selections map, the
+	// identifier z in a variable declaration 'var z int' is found
+	// only in the Defs map, and identifiers denoting packages in
+	// qualified identifiers are collected in the Uses map.
+	Types map[ast.Expr]TypeAndValue
+
+	// Inferred maps calls of parameterized functions that use
+	// type inference to the inferred type arguments and signature
+	// of the function called. The recorded "call" expression may be
+	// an *ast.CallExpr (as in f(x)), or an *ast.IndexExpr (s in f[T]).
+	Inferred map[ast.Expr]Inferred
+
+	// Defs maps identifiers to the objects they define (including
+	// package names, dots "." of dot-imports, and blank "_" identifiers).
+	// For identifiers that do not denote objects (e.g., the package name
+	// in package clauses, or symbolic variables t in t := x.(type) of
+	// type switch headers), the corresponding objects are nil.
+	//
+	// For an embedded field, Defs returns the field *Var it defines.
+	//
+	// Invariant: Defs[id] == nil || Defs[id].Pos() == id.Pos()
+	Defs map[*ast.Ident]Object
+
+	// Uses maps identifiers to the objects they denote.
+	//
+	// For an embedded field, Uses returns the *TypeName it denotes.
+	//
+	// Invariant: Uses[id].Pos() != id.Pos()
+	Uses map[*ast.Ident]Object
+
+	// Implicits maps nodes to their implicitly declared objects, if any.
+	// The following node and object types may appear:
+	//
+	//     node               declared object
+	//
+	//     *ast.ImportSpec    *PkgName for imports without renames
+	//     *ast.CaseClause    type-specific *Var for each type switch case clause (incl. default)
+	//     *ast.Field         anonymous parameter *Var (incl. unnamed results)
+	//
+	Implicits map[ast.Node]Object
+
+	// Selections maps selector expressions (excluding qualified identifiers)
+	// to their corresponding selections.
+	Selections map[*ast.SelectorExpr]*Selection
+
+	// Scopes maps ast.Nodes to the scopes they define. Package scopes are not
+	// associated with a specific node but with all files belonging to a package.
+	// Thus, the package scope can be found in the type-checked Package object.
+	// Scopes nest, with the Universe scope being the outermost scope, enclosing
+	// the package scope, which contains (one or more) files scopes, which enclose
+	// function scopes which in turn enclose statement and function literal scopes.
+	// Note that even though package-level functions are declared in the package
+	// scope, the function scopes are embedded in the file scope of the file
+	// containing the function declaration.
+	//
+	// The following node types may appear in Scopes:
+	//
+	//     *ast.File
+	//     *ast.FuncType
+	//     *ast.BlockStmt
+	//     *ast.IfStmt
+	//     *ast.SwitchStmt
+	//     *ast.TypeSwitchStmt
+	//     *ast.CaseClause
+	//     *ast.CommClause
+	//     *ast.ForStmt
+	//     *ast.RangeStmt
+	//
+	Scopes map[ast.Node]*Scope
+
+	// InitOrder is the list of package-level initializers in the order in which
+	// they must be executed. Initializers referring to variables related by an
+	// initialization dependency appear in topological order, the others appear
+	// in source order. Variables without an initialization expression do not
+	// appear in this list.
+	InitOrder []*Initializer
+}
 
 // TypeOf returns the type of expression e, or nil if not found.
 // Precondition: the Types, Uses and Defs maps are populated.
@@ -252,10 +348,10 @@
 	return tv.mode == commaok || tv.mode == mapindex
 }
 
-// _Inferred reports the _Inferred type arguments and signature
+// Inferred reports the Inferred type arguments and signature
 // for a parameterized function call that uses type inference.
-type _Inferred struct {
-	Targs []Type
+type Inferred struct {
+	TArgs []Type
 	Sig   *Signature
 }
 
@@ -324,11 +420,11 @@
 // Identical reports whether x and y are identical types.
 // Receivers of Signature types are ignored.
 func Identical(x, y Type) bool {
-	return (*Checker)(nil).identical(x, y)
+	return identical(x, y, true, nil)
 }
 
 // IdenticalIgnoreTags reports whether x and y are identical types if tags are ignored.
 // Receivers of Signature types are ignored.
 func IdenticalIgnoreTags(x, y Type) bool {
-	return (*Checker)(nil).identicalIgnoreTags(x, y)
+	return identical(x, y, false, nil)
 }
diff --git a/src/go/types/api_notypeparams.go b/src/go/types/api_notypeparams.go
deleted file mode 100644
index 9f7cb7e..0000000
--- a/src/go/types/api_notypeparams.go
+++ /dev/null
@@ -1,104 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !typeparams
-// +build !typeparams
-
-package types
-
-import "go/ast"
-
-// Info holds result type information for a type-checked package.
-// Only the information for which a map is provided is collected.
-// If the package has type errors, the collected information may
-// be incomplete.
-type Info struct {
-	// Types maps expressions to their types, and for constant
-	// expressions, also their values. Invalid expressions are
-	// omitted.
-	//
-	// For (possibly parenthesized) identifiers denoting built-in
-	// functions, the recorded signatures are call-site specific:
-	// if the call result is not a constant, the recorded type is
-	// an argument-specific signature. Otherwise, the recorded type
-	// is invalid.
-	//
-	// The Types map does not record the type of every identifier,
-	// only those that appear where an arbitrary expression is
-	// permitted. For instance, the identifier f in a selector
-	// expression x.f is found only in the Selections map, the
-	// identifier z in a variable declaration 'var z int' is found
-	// only in the Defs map, and identifiers denoting packages in
-	// qualified identifiers are collected in the Uses map.
-	Types map[ast.Expr]TypeAndValue
-
-	// Defs maps identifiers to the objects they define (including
-	// package names, dots "." of dot-imports, and blank "_" identifiers).
-	// For identifiers that do not denote objects (e.g., the package name
-	// in package clauses, or symbolic variables t in t := x.(type) of
-	// type switch headers), the corresponding objects are nil.
-	//
-	// For an embedded field, Defs returns the field *Var it defines.
-	//
-	// Invariant: Defs[id] == nil || Defs[id].Pos() == id.Pos()
-	Defs map[*ast.Ident]Object
-
-	// Uses maps identifiers to the objects they denote.
-	//
-	// For an embedded field, Uses returns the *TypeName it denotes.
-	//
-	// Invariant: Uses[id].Pos() != id.Pos()
-	Uses map[*ast.Ident]Object
-
-	// Implicits maps nodes to their implicitly declared objects, if any.
-	// The following node and object types may appear:
-	//
-	//     node               declared object
-	//
-	//     *ast.ImportSpec    *PkgName for imports without renames
-	//     *ast.CaseClause    type-specific *Var for each type switch case clause (incl. default)
-	//     *ast.Field         anonymous parameter *Var (incl. unnamed results)
-	//
-	Implicits map[ast.Node]Object
-
-	// Selections maps selector expressions (excluding qualified identifiers)
-	// to their corresponding selections.
-	Selections map[*ast.SelectorExpr]*Selection
-
-	// Scopes maps ast.Nodes to the scopes they define. Package scopes are not
-	// associated with a specific node but with all files belonging to a package.
-	// Thus, the package scope can be found in the type-checked Package object.
-	// Scopes nest, with the Universe scope being the outermost scope, enclosing
-	// the package scope, which contains (one or more) files scopes, which enclose
-	// function scopes which in turn enclose statement and function literal scopes.
-	// Note that even though package-level functions are declared in the package
-	// scope, the function scopes are embedded in the file scope of the file
-	// containing the function declaration.
-	//
-	// The following node types may appear in Scopes:
-	//
-	//     *ast.File
-	//     *ast.FuncType
-	//     *ast.BlockStmt
-	//     *ast.IfStmt
-	//     *ast.SwitchStmt
-	//     *ast.TypeSwitchStmt
-	//     *ast.CaseClause
-	//     *ast.CommClause
-	//     *ast.ForStmt
-	//     *ast.RangeStmt
-	//
-	Scopes map[ast.Node]*Scope
-
-	// InitOrder is the list of package-level initializers in the order in which
-	// they must be executed. Initializers referring to variables related by an
-	// initialization dependency appear in topological order, the others appear
-	// in source order. Variables without an initialization expression do not
-	// appear in this list.
-	InitOrder []*Initializer
-}
-
-func getInferred(info *Info) map[ast.Expr]_Inferred {
-	return nil
-}
diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index f964c65..f138af5 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -343,16 +343,16 @@
 		{broken + `x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string][-1]int`},
 
 		// parameterized functions
-		{genericPkg + `p0; func f[T any](T); var _ = f[int]`, `f`, `func[T₁ interface{}](T₁)`},
+		{genericPkg + `p0; func f[T any](T); var _ = f[int]`, `f`, `func[generic_p0.T₁ interface{}](generic_p0.T₁)`},
 		{genericPkg + `p1; func f[T any](T); var _ = f[int]`, `f[int]`, `func(int)`},
-		{genericPkg + `p2; func f[T any](T); func _() { f(42) }`, `f`, `func[T₁ interface{}](T₁)`},
+		{genericPkg + `p2; func f[T any](T); func _() { f(42) }`, `f`, `func[generic_p2.T₁ interface{}](generic_p2.T₁)`},
 		{genericPkg + `p3; func f[T any](T); func _() { f(42) }`, `f(42)`, `()`},
 
 		// type parameters
 		{genericPkg + `t0; type t[] int; var _ t`, `t`, `generic_t0.t`}, // t[] is a syntax error that is ignored in this test in favor of t
-		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[P₁ interface{}]`},
-		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[P₁ interface{}]`},
-		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[P₁, Q₂ interface{}]`},
+		{genericPkg + `t1; type t[P any] int; var _ t[int]`, `t`, `generic_t1.t[generic_t1.P₁ interface{}]`},
+		{genericPkg + `t2; type t[P interface{}] int; var _ t[int]`, `t`, `generic_t2.t[generic_t2.P₁ interface{}]`},
+		{genericPkg + `t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `generic_t3.t[generic_t3.P₁, generic_t3.Q₂ interface{}]`},
 
 		// TODO (rFindley): compare with types2, which resolves the type broken_t4.t[P₁, Q₂ interface{m()}] here
 		{broken + `t4; type t[P, Q interface{ m() }] int; var _ t[int, int]`, `t`, `broken_t4.t`},
@@ -361,14 +361,10 @@
 		{genericPkg + `g0; type t[P any] int; var x struct{ f t[int] }; var _ = x.f`, `x.f`, `generic_g0.t[int]`},
 
 		// issue 45096
-		{genericPkg + `issue45096; func _[T interface{ type int8, int16, int32  }](x T) { _ = x < 0 }`, `0`, `T₁`},
+		{genericPkg + `issue45096; func _[T interface{ ~int8 | ~int16 | ~int32  }](x T) { _ = x < 0 }`, `0`, `generic_issue45096.T₁`},
 	}
 
 	for _, test := range tests {
-		ResetId() // avoid renumbering of type parameter ids when adding tests
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
 		var name string
 		if strings.HasPrefix(test.src, broken) {
@@ -402,6 +398,129 @@
 	}
 }
 
+func TestInferredInfo(t *testing.T) {
+	var tests = []struct {
+		src   string
+		fun   string
+		targs []string
+		sig   string
+	}{
+		{genericPkg + `p0; func f[T any](T); func _() { f(42) }`,
+			`f`,
+			[]string{`int`},
+			`func(int)`,
+		},
+		{genericPkg + `p1; func f[T any](T) T; func _() { f('@') }`,
+			`f`,
+			[]string{`rune`},
+			`func(rune) rune`,
+		},
+		{genericPkg + `p2; func f[T any](...T) T; func _() { f(0i) }`,
+			`f`,
+			[]string{`complex128`},
+			`func(...complex128) complex128`,
+		},
+		{genericPkg + `p3; func f[A, B, C any](A, *B, []C); func _() { f(1.2, new(string), []byte{}) }`,
+			`f`,
+			[]string{`float64`, `string`, `byte`},
+			`func(float64, *string, []byte)`,
+		},
+		{genericPkg + `p4; func f[A, B any](A, *B, ...[]B); func _() { f(1.2, new(byte)) }`,
+			`f`,
+			[]string{`float64`, `byte`},
+			`func(float64, *byte, ...[]byte)`,
+		},
+
+		{genericPkg + `s1; func f[T any, P interface{~*T}](x T); func _(x string) { f(x) }`,
+			`f`,
+			[]string{`string`, `*string`},
+			`func(x string)`,
+		},
+		{genericPkg + `s2; func f[T any, P interface{~*T}](x []T); func _(x []int) { f(x) }`,
+			`f`,
+			[]string{`int`, `*int`},
+			`func(x []int)`,
+		},
+		{genericPkg + `s3; type C[T any] interface{~chan<- T}; func f[T any, P C[T]](x []T); func _(x []int) { f(x) }`,
+			`f`,
+			[]string{`int`, `chan<- int`},
+			`func(x []int)`,
+		},
+		{genericPkg + `s4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T); func _(x []int) { f(x) }`,
+			`f`,
+			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
+			`func(x []int)`,
+		},
+
+		{genericPkg + `t1; func f[T any, P interface{~*T}]() T; func _() { _ = f[string] }`,
+			`f`,
+			[]string{`string`, `*string`},
+			`func() string`,
+		},
+		{genericPkg + `t2; type C[T any] interface{~chan<- T}; func f[T any, P C[T]]() []T; func _() { _ = f[int] }`,
+			`f`,
+			[]string{`int`, `chan<- int`},
+			`func() []int`,
+		},
+		{genericPkg + `t3; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T; func _() { _ = f[int] }`,
+			`f`,
+			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
+			`func() []int`,
+		},
+	}
+
+	for _, test := range tests {
+		info := Info{}
+		info.Inferred = make(map[ast.Expr]Inferred)
+		name, err := mayTypecheck(t, "InferredInfo", test.src, &info)
+		if err != nil {
+			t.Errorf("package %s: %v", name, err)
+			continue
+		}
+
+		// look for inferred type arguments and signature
+		var targs []Type
+		var sig *Signature
+		for call, inf := range info.Inferred {
+			var fun ast.Expr
+			switch x := call.(type) {
+			case *ast.CallExpr:
+				fun = x.Fun
+			case *ast.IndexExpr:
+				fun = x.X
+			default:
+				panic(fmt.Sprintf("unexpected call expression type %T", call))
+			}
+			if ExprString(fun) == test.fun {
+				targs = inf.TArgs
+				sig = inf.Sig
+				break
+			}
+		}
+		if targs == nil {
+			t.Errorf("package %s: no inferred information found for %s", name, test.fun)
+			continue
+		}
+
+		// check that type arguments are correct
+		if len(targs) != len(test.targs) {
+			t.Errorf("package %s: got %d type arguments; want %d", name, len(targs), len(test.targs))
+			continue
+		}
+		for i, targ := range targs {
+			if got := targ.String(); got != test.targs[i] {
+				t.Errorf("package %s, %d. type argument: got %s; want %s", name, i, got, test.targs[i])
+				continue
+			}
+		}
+
+		// check that signature is correct
+		if got := sig.String(); got != test.sig {
+			t.Errorf("package %s: got %s; want %s", name, got, test.sig)
+		}
+	}
+}
+
 func TestDefsInfo(t *testing.T) {
 	var tests = []struct {
 		src  string
@@ -424,9 +543,6 @@
 	}
 
 	for _, test := range tests {
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{
 			Defs: make(map[*ast.Ident]Object),
 		}
@@ -472,9 +588,6 @@
 	}
 
 	for _, test := range tests {
-		if strings.HasPrefix(test.src, genericPkg) && !typeparams.Enabled {
-			continue
-		}
 		info := Info{
 			Uses: make(map[*ast.Ident]Object),
 		}
@@ -1716,3 +1829,28 @@
 		}
 	}
 }
+
+func TestInstantiate(t *testing.T) {
+	// eventually we like more tests but this is a start
+	const src = genericPkg + "p; type T[P any] *T[P]"
+	pkg, err := pkgFor(".", src, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// type T should have one type parameter
+	T := pkg.Scope().Lookup("T").Type().(*Named)
+	if n := T.TParams().Len(); n != 1 {
+		t.Fatalf("expected 1 type parameter; found %d", n)
+	}
+
+	// instantiation should succeed (no endless recursion)
+	// even with a nil *Checker
+	var check *Checker
+	res := check.Instantiate(token.NoPos, T, []Type{Typ[Int]}, nil, false)
+
+	// instantiated type should point to itself
+	if res.Underlying().(*Pointer).Elem() != res {
+		t.Fatalf("unexpected result type: %s", res)
+	}
+}
diff --git a/src/go/types/api_typeparams.go b/src/go/types/api_typeparams.go
deleted file mode 100644
index ed744c4..0000000
--- a/src/go/types/api_typeparams.go
+++ /dev/null
@@ -1,53 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build typeparams
-// +build typeparams
-
-package types
-
-import (
-	"go/ast"
-)
-
-type (
-	Inferred  = _Inferred
-	Sum       = _Sum
-	TypeParam = _TypeParam
-)
-
-func NewSum(types []Type) Type { return _NewSum(types) }
-
-func (s *Signature) TParams() []*TypeName           { return s._TParams() }
-func (s *Signature) SetTParams(tparams []*TypeName) { s._SetTParams(tparams) }
-
-func (t *Interface) HasTypeList() bool  { return t._HasTypeList() }
-func (t *Interface) IsComparable() bool { return t._IsComparable() }
-func (t *Interface) IsConstraint() bool { return t._IsConstraint() }
-
-func (t *Named) TParams() []*TypeName { return t._TParams() }
-func (t *Named) TArgs() []Type        { return t._TArgs() }
-func (t *Named) SetTArgs(args []Type) { t._SetTArgs(args) }
-
-// Info is documented in api_notypeparams.go.
-type Info struct {
-	Types map[ast.Expr]TypeAndValue
-
-	// Inferred maps calls of parameterized functions that use type inference to
-	// the Inferred type arguments and signature of the function called. The
-	// recorded "call" expression may be an *ast.CallExpr (as in f(x)), or an
-	// *ast.IndexExpr (s in f[T]).
-	Inferred map[ast.Expr]_Inferred
-
-	Defs       map[*ast.Ident]Object
-	Uses       map[*ast.Ident]Object
-	Implicits  map[ast.Node]Object
-	Selections map[*ast.SelectorExpr]*Selection
-	Scopes     map[ast.Node]*Scope
-	InitOrder  []*Initializer
-}
-
-func getInferred(info *Info) map[ast.Expr]_Inferred {
-	return info.Inferred
-}
diff --git a/src/go/types/api_typeparams_test.go b/src/go/types/api_typeparams_test.go
deleted file mode 100644
index 15c9bf0..0000000
--- a/src/go/types/api_typeparams_test.go
+++ /dev/null
@@ -1,139 +0,0 @@
-// Copyright 2021 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build typeparams
-// +build typeparams
-
-package types_test
-
-import (
-	"fmt"
-	"go/ast"
-	"testing"
-
-	. "go/types"
-)
-
-func TestInferredInfo(t *testing.T) {
-	var tests = []struct {
-		src   string
-		fun   string
-		targs []string
-		sig   string
-	}{
-		{genericPkg + `p0; func f[T any](T); func _() { f(42) }`,
-			`f`,
-			[]string{`int`},
-			`func(int)`,
-		},
-		{genericPkg + `p1; func f[T any](T) T; func _() { f('@') }`,
-			`f`,
-			[]string{`rune`},
-			`func(rune) rune`,
-		},
-		{genericPkg + `p2; func f[T any](...T) T; func _() { f(0i) }`,
-			`f`,
-			[]string{`complex128`},
-			`func(...complex128) complex128`,
-		},
-		{genericPkg + `p3; func f[A, B, C any](A, *B, []C); func _() { f(1.2, new(string), []byte{}) }`,
-			`f`,
-			[]string{`float64`, `string`, `byte`},
-			`func(float64, *string, []byte)`,
-		},
-		{genericPkg + `p4; func f[A, B any](A, *B, ...[]B); func _() { f(1.2, new(byte)) }`,
-			`f`,
-			[]string{`float64`, `byte`},
-			`func(float64, *byte, ...[]byte)`,
-		},
-
-		{genericPkg + `s1; func f[T any, P interface{type *T}](x T); func _(x string) { f(x) }`,
-			`f`,
-			[]string{`string`, `*string`},
-			`func(x string)`,
-		},
-		{genericPkg + `s2; func f[T any, P interface{type *T}](x []T); func _(x []int) { f(x) }`,
-			`f`,
-			[]string{`int`, `*int`},
-			`func(x []int)`,
-		},
-		{genericPkg + `s3; type C[T any] interface{type chan<- T}; func f[T any, P C[T]](x []T); func _(x []int) { f(x) }`,
-			`f`,
-			[]string{`int`, `chan<- int`},
-			`func(x []int)`,
-		},
-		{genericPkg + `s4; type C[T any] interface{type chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T); func _(x []int) { f(x) }`,
-			`f`,
-			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
-			`func(x []int)`,
-		},
-
-		{genericPkg + `t1; func f[T any, P interface{type *T}]() T; func _() { _ = f[string] }`,
-			`f`,
-			[]string{`string`, `*string`},
-			`func() string`,
-		},
-		{genericPkg + `t2; type C[T any] interface{type chan<- T}; func f[T any, P C[T]]() []T; func _() { _ = f[int] }`,
-			`f`,
-			[]string{`int`, `chan<- int`},
-			`func() []int`,
-		},
-		{genericPkg + `t3; type C[T any] interface{type chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T; func _() { _ = f[int] }`,
-			`f`,
-			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
-			`func() []int`,
-		},
-	}
-
-	for _, test := range tests {
-		info := Info{}
-		info.Inferred = make(map[ast.Expr]Inferred)
-		name, err := mayTypecheck(t, "InferredInfo", test.src, &info)
-		if err != nil {
-			t.Errorf("package %s: %v", name, err)
-			continue
-		}
-
-		// look for inferred type arguments and signature
-		var targs []Type
-		var sig *Signature
-		for call, inf := range info.Inferred {
-			var fun ast.Expr
-			switch x := call.(type) {
-			case *ast.CallExpr:
-				fun = x.Fun
-			case *ast.IndexExpr:
-				fun = x.X
-			default:
-				panic(fmt.Sprintf("unexpected call expression type %T", call))
-			}
-			if ExprString(fun) == test.fun {
-				targs = inf.Targs
-				sig = inf.Sig
-				break
-			}
-		}
-		if targs == nil {
-			t.Errorf("package %s: no inferred information found for %s", name, test.fun)
-			continue
-		}
-
-		// check that type arguments are correct
-		if len(targs) != len(test.targs) {
-			t.Errorf("package %s: got %d type arguments; want %d", name, len(targs), len(test.targs))
-			continue
-		}
-		for i, targ := range targs {
-			if got := targ.String(); got != test.targs[i] {
-				t.Errorf("package %s, %d. type argument: got %s; want %s", name, i, got, test.targs[i])
-				continue
-			}
-		}
-
-		// check that signature is correct
-		if got := sig.String(); got != test.sig {
-			t.Errorf("package %s: got %s; want %s", name, got, test.sig)
-		}
-	}
-}
diff --git a/src/go/types/array.go b/src/go/types/array.go
new file mode 100644
index 0000000..5b28474
--- /dev/null
+++ b/src/go/types/array.go
@@ -0,0 +1,25 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// An Array represents an array type.
+type Array struct {
+	len  int64
+	elem Type
+}
+
+// NewArray returns a new array type for the given element type and length.
+// A negative length indicates an unknown length.
+func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} }
+
+// Len returns the length of array a.
+// A negative result indicates an unknown length.
+func (a *Array) Len() int64 { return a.len }
+
+// Elem returns element type of array a.
+func (a *Array) Elem() Type { return a.elem }
+
+func (t *Array) Underlying() Type { return t }
+func (t *Array) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/assignments.go b/src/go/types/assignments.go
index 18eae62..595f426 100644
--- a/src/go/types/assignments.go
+++ b/src/go/types/assignments.go
@@ -71,7 +71,7 @@
 	}
 
 	// A generic (non-instantiated) function value cannot be assigned to a variable.
-	if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
+	if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
 		check.errorf(x, _Todo, "cannot use generic function %s without instantiation in %s", x, context)
 	}
 
diff --git a/src/go/types/basic.go b/src/go/types/basic.go
new file mode 100644
index 0000000..215923f
--- /dev/null
+++ b/src/go/types/basic.go
@@ -0,0 +1,82 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// BasicKind describes the kind of basic type.
+type BasicKind int
+
+const (
+	Invalid BasicKind = iota // type is invalid
+
+	// predeclared types
+	Bool
+	Int
+	Int8
+	Int16
+	Int32
+	Int64
+	Uint
+	Uint8
+	Uint16
+	Uint32
+	Uint64
+	Uintptr
+	Float32
+	Float64
+	Complex64
+	Complex128
+	String
+	UnsafePointer
+
+	// types for untyped values
+	UntypedBool
+	UntypedInt
+	UntypedRune
+	UntypedFloat
+	UntypedComplex
+	UntypedString
+	UntypedNil
+
+	// aliases
+	Byte = Uint8
+	Rune = Int32
+)
+
+// BasicInfo is a set of flags describing properties of a basic type.
+type BasicInfo int
+
+// Properties of basic types.
+const (
+	IsBoolean BasicInfo = 1 << iota
+	IsInteger
+	IsUnsigned
+	IsFloat
+	IsComplex
+	IsString
+	IsUntyped
+
+	IsOrdered   = IsInteger | IsFloat | IsString
+	IsNumeric   = IsInteger | IsFloat | IsComplex
+	IsConstType = IsBoolean | IsNumeric | IsString
+)
+
+// A Basic represents a basic type.
+type Basic struct {
+	kind BasicKind
+	info BasicInfo
+	name string
+}
+
+// Kind returns the kind of basic type b.
+func (b *Basic) Kind() BasicKind { return b.kind }
+
+// Info returns information about properties of basic type b.
+func (b *Basic) Info() BasicInfo { return b.info }
+
+// Name returns the name of basic type b.
+func (b *Basic) Name() string { return b.name }
+
+func (t *Basic) Underlying() Type { return t }
+func (t *Basic) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/builtins.go b/src/go/types/builtins.go
index 2a2d54d..c73d946 100644
--- a/src/go/types/builtins.go
+++ b/src/go/types/builtins.go
@@ -179,9 +179,9 @@
 				mode = value
 			}
 
-		case *_Sum:
-			if t.is(func(t Type) bool {
-				switch t := under(t).(type) {
+		case *Union:
+			if t.underIs(func(t Type) bool {
+				switch t := t.(type) {
 				case *Basic:
 					if isString(t) && id == _Len {
 						return true
@@ -217,19 +217,23 @@
 
 	case _Close:
 		// close(c)
-		c := asChan(x.typ)
-		if c == nil {
-			check.invalidArg(x, _InvalidClose, "%s is not a channel", x)
+		if !underIs(x.typ, func(u Type) bool {
+			uch, _ := u.(*Chan)
+			if uch == nil {
+				check.invalidOp(x, _InvalidClose, "cannot close non-channel %s", x)
+				return false
+			}
+			if uch.dir == RecvOnly {
+				check.invalidOp(x, _InvalidClose, "cannot close receive-only channel %s", x)
+				return false
+			}
+			return true
+		}) {
 			return
 		}
-		if c.dir == RecvOnly {
-			check.invalidArg(x, _InvalidClose, "%s must not be a receive-only channel", x)
-			return
-		}
-
 		x.mode = novalue
 		if check.Types != nil {
-			check.recordBuiltinType(call.Fun, makeSig(nil, c))
+			check.recordBuiltinType(call.Fun, makeSig(nil, x.typ))
 		}
 
 	case _Complex:
@@ -286,7 +290,7 @@
 		}
 
 		// both argument types must be identical
-		if !check.identical(x.typ, y.typ) {
+		if !Identical(x.typ, y.typ) {
 			check.invalidArg(x, _InvalidComplex, "mismatched types %s and %s", x.typ, y.typ)
 			return
 		}
@@ -337,13 +341,15 @@
 			return
 		}
 		var src Type
-		switch t := optype(y.typ).(type) {
+		switch t := under(y.typ).(type) {
 		case *Basic:
 			if isString(y.typ) {
 				src = universeByte
 			}
 		case *Slice:
 			src = t.elem
+		case *TypeParam:
+			check.error(x, _Todo, "copy on generic operands not yet implemented")
 		}
 
 		if dst == nil || src == nil {
@@ -351,7 +357,7 @@
 			return
 		}
 
-		if !check.identical(dst, src) {
+		if !Identical(dst, src) {
 			check.invalidArg(x, _InvalidCopy, "arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
 			return
 		}
@@ -363,25 +369,40 @@
 		x.typ = Typ[Int]
 
 	case _Delete:
-		// delete(m, k)
-		m := asMap(x.typ)
-		if m == nil {
-			check.invalidArg(x, _InvalidDelete, "%s is not a map", x)
+		// delete(map_, key)
+		// map_ must be a map type or a type parameter describing map types.
+		// The key cannot be a type parameter for now.
+		map_ := x.typ
+		var key Type
+		if !underIs(map_, func(u Type) bool {
+			map_, _ := u.(*Map)
+			if map_ == nil {
+				check.invalidArg(x, _InvalidDelete, "%s is not a map", x)
+				return false
+			}
+			if key != nil && !Identical(map_.key, key) {
+				check.invalidArg(x, _Todo, "maps of %s must have identical key types", x)
+				return false
+			}
+			key = map_.key
+			return true
+		}) {
 			return
 		}
+
 		arg(x, 1) // k
 		if x.mode == invalid {
 			return
 		}
 
-		check.assignment(x, m.key, "argument to delete")
+		check.assignment(x, key, "argument to delete")
 		if x.mode == invalid {
 			return
 		}
 
 		x.mode = novalue
 		if check.Types != nil {
-			check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
+			check.recordBuiltinType(call.Fun, makeSig(nil, map_, key))
 		}
 
 	case _Imag, _Real:
@@ -464,13 +485,13 @@
 		var valid func(t Type) bool
 		valid = func(t Type) bool {
 			var m int
-			switch t := optype(t).(type) {
+			switch t := under(t).(type) {
 			case *Slice:
 				m = 2
 			case *Map, *Chan:
 				m = 1
-			case *_Sum:
-				return t.is(valid)
+			case *TypeParam:
+				return t.underIs(valid)
 			default:
 				return false
 			}
@@ -612,19 +633,22 @@
 
 	case _Alignof:
 		// unsafe.Alignof(x T) uintptr
-		if asTypeParam(x.typ) != nil {
-			check.invalidOp(call, _Todo, "unsafe.Alignof undefined for %s", x)
-			return
-		}
 		check.assignment(x, nil, "argument to unsafe.Alignof")
 		if x.mode == invalid {
 			return
 		}
 
-		x.mode = constant_
-		x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+		if hasVarSize(x.typ) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], x.typ))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Offsetof:
 		// unsafe.Offsetof(x T) uintptr, where x must be a selector
@@ -644,7 +668,7 @@
 
 		base := derefStructPtr(x.typ)
 		sel := selx.Sel.Name
-		obj, index, indirect := check.lookupFieldOrMethod(base, false, check.pkg, sel)
+		obj, index, indirect := LookupFieldOrMethod(base, false, check.pkg, sel)
 		switch obj.(type) {
 		case nil:
 			check.invalidArg(x, _MissingFieldOrMethod, "%s has no single field %s", base, sel)
@@ -662,30 +686,43 @@
 			return
 		}
 
-		// TODO(gri) Should we pass x.typ instead of base (and indirect report if derefStructPtr indirected)?
+		// TODO(gri) Should we pass x.typ instead of base (and have indirect report if derefStructPtr indirected)?
 		check.recordSelection(selx, FieldVal, base, obj, index, false)
 
-		offs := check.conf.offsetof(base, index)
-		x.mode = constant_
-		x.val = constant.MakeInt64(offs)
+		// The field offset is considered a variable even if the field is declared before
+		// the part of the struct which is variable-sized. This makes both the rules
+		// simpler and also permits (or at least doesn't prevent) a compiler from re-
+		// arranging struct fields if it wanted to.
+		if hasVarSize(base) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], obj.Type()))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.offsetof(base, index))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Sizeof:
 		// unsafe.Sizeof(x T) uintptr
-		if asTypeParam(x.typ) != nil {
-			check.invalidOp(call, _Todo, "unsafe.Sizeof undefined for %s", x)
-			return
-		}
 		check.assignment(x, nil, "argument to unsafe.Sizeof")
 		if x.mode == invalid {
 			return
 		}
 
-		x.mode = constant_
-		x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+		if hasVarSize(x.typ) {
+			x.mode = value
+			if check.Types != nil {
+				check.recordBuiltinType(call.Fun, makeSig(Typ[Uintptr], x.typ))
+			}
+		} else {
+			x.mode = constant_
+			x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+			// result is constant - no need to record signature
+		}
 		x.typ = Typ[Uintptr]
-		// result is constant - no need to record signature
 
 	case _Slice:
 		// unsafe.Slice(ptr *T, len IntegerType) []T
@@ -757,6 +794,25 @@
 	return true
 }
 
+// hasVarSize reports if the size of type t is variable due to type parameters.
+func hasVarSize(t Type) bool {
+	switch t := under(t).(type) {
+	case *Array:
+		return hasVarSize(t.elem)
+	case *Struct:
+		for _, f := range t.fields {
+			if hasVarSize(f.typ) {
+				return true
+			}
+		}
+	case *TypeParam:
+		return true
+	case *Named, *Union, *top:
+		unreachable()
+	}
+	return false
+}
+
 // applyTypeFunc applies f to x. If x is a type parameter,
 // the result is a type parameter constrained by an new
 // interface bound. The type bounds for that interface
@@ -769,9 +825,11 @@
 		// Test if t satisfies the requirements for the argument
 		// type and collect possible result types at the same time.
 		var rtypes []Type
-		if !tp.Bound().is(func(x Type) bool {
-			if r := f(x); r != nil {
+		var tildes []bool
+		if !tp.iface().is(func(typ Type, tilde bool) bool {
+			if r := f(typ); r != nil {
 				rtypes = append(rtypes, r)
+				tildes = append(tildes, tilde)
 				return true
 			}
 			return false
@@ -779,11 +837,14 @@
 			return nil
 		}
 
-		// construct a suitable new type parameter
-		tpar := NewTypeName(token.NoPos, nil /* = Universe pkg */, "<type parameter>", nil)
-		ptyp := check.newTypeParam(tpar, 0, &emptyInterface) // assigns type to tpar as a side-effect
-		tsum := _NewSum(rtypes)
-		ptyp.bound = &Interface{types: tsum, allMethods: markComplete, allTypes: tsum}
+		// Construct a suitable new type parameter for the sum type. The
+		// type param is placed in the current package so export/import
+		// works as expected.
+		tpar := NewTypeName(token.NoPos, check.pkg, "<type parameter>", nil)
+		ptyp := check.NewTypeParam(tpar, &emptyInterface) // assigns type to tpar as a side-effect
+		ptyp.index = tp.index
+		tsum := newUnion(rtypes, tildes)
+		ptyp.bound = &Interface{complete: true, tset: &_TypeSet{types: tsum}}
 
 		return ptyp
 	}
diff --git a/src/go/types/builtins_test.go b/src/go/types/builtins_test.go
index 11de9a1..cee3d31 100644
--- a/src/go/types/builtins_test.go
+++ b/src/go/types/builtins_test.go
@@ -113,12 +113,15 @@
 
 	{"Alignof", `_ = unsafe.Alignof(0)`, `invalid type`},                 // constant
 	{"Alignof", `var x struct{}; _ = unsafe.Alignof(x)`, `invalid type`}, // constant
+	{"Alignof", `var x P; _ = unsafe.Alignof(x)`, `func(p.P₁) uintptr`},
 
 	{"Offsetof", `var x struct{f bool}; _ = unsafe.Offsetof(x.f)`, `invalid type`},           // constant
 	{"Offsetof", `var x struct{_ int; f bool}; _ = unsafe.Offsetof((&x).f)`, `invalid type`}, // constant
+	{"Offsetof", `var x struct{_ int; f P}; _ = unsafe.Offsetof((&x).f)`, `func(p.P₁) uintptr`},
 
 	{"Sizeof", `_ = unsafe.Sizeof(0)`, `invalid type`},                 // constant
 	{"Sizeof", `var x struct{}; _ = unsafe.Sizeof(x)`, `invalid type`}, // constant
+	{"Sizeof", `var x P; _ = unsafe.Sizeof(x)`, `func(p.P₁) uintptr`},
 
 	{"Slice", `var p *int; _ = unsafe.Slice(p, 1)`, `func(*int, int) []int`},
 	{"Slice", `var p *byte; var n uintptr; _ = unsafe.Slice(p, n)`, `func(*byte, uintptr) []byte`},
@@ -151,8 +154,10 @@
 	}
 }
 
+// parseGenericSrc in types2 is not necessary. We can just parse in testBuiltinSignature below.
+
 func testBuiltinSignature(t *testing.T, name, src0, want string) {
-	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _() { %s }`, src0)
+	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _[P any]() { %s }`, src0)
 	f, err := parser.ParseFile(fset, "", src, 0)
 	if err != nil {
 		t.Errorf("%s: %s", src0, err)
diff --git a/src/go/types/call.go b/src/go/types/call.go
index 631ea42..da2f319 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -16,23 +16,22 @@
 
 // funcInst type-checks a function instantiation inst and returns the result in x.
 // The operand x must be the evaluation of inst.X and its type must be a signature.
-func (check *Checker) funcInst(x *operand, inst *ast.IndexExpr) {
-	xlist := typeparams.UnpackExpr(inst.Index)
-	targs := check.typeList(xlist)
+func (check *Checker) funcInst(x *operand, ix *typeparams.IndexExpr) {
+	targs := check.typeList(ix.Indices)
 	if targs == nil {
 		x.mode = invalid
-		x.expr = inst
+		x.expr = ix.Orig
 		return
 	}
-	assert(len(targs) == len(xlist))
+	assert(len(targs) == len(ix.Indices))
 
 	// check number of type arguments (got) vs number of type parameters (want)
 	sig := x.typ.(*Signature)
-	got, want := len(targs), len(sig.tparams)
+	got, want := len(targs), sig.TParams().Len()
 	if got > want {
-		check.errorf(xlist[got-1], _Todo, "got %d type arguments but want %d", got, want)
+		check.errorf(ix.Indices[got-1], _Todo, "got %d type arguments but want %d", got, want)
 		x.mode = invalid
-		x.expr = inst
+		x.expr = ix.Orig
 		return
 	}
 
@@ -40,11 +39,11 @@
 	inferred := false
 
 	if got < want {
-		targs = check.infer(inst, sig.tparams, targs, nil, nil, true)
+		targs = check.infer(ix.Orig, sig.TParams().list(), targs, nil, nil, true)
 		if targs == nil {
 			// error was already reported
 			x.mode = invalid
-			x.expr = inst
+			x.expr = ix.Orig
 			return
 		}
 		got = len(targs)
@@ -55,34 +54,36 @@
 	// determine argument positions (for error reporting)
 	// TODO(rFindley) use a positioner here? instantiate would need to be
 	//                updated accordingly.
-	poslist := make([]token.Pos, len(xlist))
-	for i, x := range xlist {
+	poslist := make([]token.Pos, len(ix.Indices))
+	for i, x := range ix.Indices {
 		poslist[i] = x.Pos()
 	}
 
 	// instantiate function signature
-	res := check.instantiate(x.Pos(), sig, targs, poslist).(*Signature)
-	assert(res.tparams == nil) // signature is not generic anymore
+	res := check.Instantiate(x.Pos(), sig, targs, poslist, true).(*Signature)
+	assert(res.TParams().Len() == 0) // signature is not generic anymore
 	if inferred {
-		check.recordInferred(inst, targs, res)
+		check.recordInferred(ix.Orig, targs, res)
 	}
 	x.typ = res
 	x.mode = value
-	x.expr = inst
+	x.expr = ix.Orig
 }
 
 func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
-	var inst *ast.IndexExpr
-	if iexpr, _ := call.Fun.(*ast.IndexExpr); iexpr != nil {
-		if check.indexExpr(x, iexpr) {
+	ix := typeparams.UnpackIndexExpr(call.Fun)
+	if ix != nil {
+		if check.indexExpr(x, ix) {
 			// Delay function instantiation to argument checking,
 			// where we combine type and value arguments for type
 			// inference.
 			assert(x.mode == value)
-			inst = iexpr
+		} else {
+			ix = nil
 		}
-		x.expr = iexpr
+		x.expr = call.Fun
 		check.record(x)
+
 	} else {
 		check.exprOrType(x, call.Fun)
 	}
@@ -108,8 +109,7 @@
 					break
 				}
 				if t := asInterface(T); t != nil {
-					check.completeInterface(token.NoPos, t)
-					if t._IsConstraint() {
+					if t.IsConstraint() {
 						check.errorf(call, _Todo, "cannot use interface %s in conversion (contains type list or is comparable)", T)
 						break
 					}
@@ -149,21 +149,20 @@
 
 	// evaluate type arguments, if any
 	var targs []Type
-	if inst != nil {
-		xlist := typeparams.UnpackExpr(inst.Index)
-		targs = check.typeList(xlist)
+	if ix != nil {
+		targs = check.typeList(ix.Indices)
 		if targs == nil {
 			check.use(call.Args...)
 			x.mode = invalid
 			x.expr = call
 			return statement
 		}
-		assert(len(targs) == len(xlist))
+		assert(len(targs) == len(ix.Indices))
 
 		// check number of type arguments (got) vs number of type parameters (want)
-		got, want := len(targs), len(sig.tparams)
+		got, want := len(targs), sig.TParams().Len()
 		if got > want {
-			check.errorf(xlist[want], _Todo, "got %d type arguments but want %d", got, want)
+			check.errorf(ix.Indices[want], _Todo, "got %d type arguments but want %d", got, want)
 			check.use(call.Args...)
 			x.mode = invalid
 			x.expr = call
@@ -195,7 +194,7 @@
 
 	// if type inference failed, a parametrized result must be invalidated
 	// (operands cannot have a parametrized type)
-	if x.mode == value && len(sig.tparams) > 0 && isParameterized(sig.tparams, x.typ) {
+	if x.mode == value && sig.TParams().Len() > 0 && isParameterized(sig.TParams().list(), x.typ) {
 		x.mode = invalid
 	}
 
@@ -325,24 +324,24 @@
 	}
 
 	// infer type arguments and instantiate signature if necessary
-	if len(sig.tparams) > 0 {
+	if sig.TParams().Len() > 0 {
 		// TODO(gri) provide position information for targs so we can feed
 		//           it to the instantiate call for better error reporting
-		targs := check.infer(call, sig.tparams, targs, sigParams, args, true)
+		targs := check.infer(call, sig.TParams().list(), targs, sigParams, args, true)
 		if targs == nil {
 			return // error already reported
 		}
 
 		// compute result signature
-		rsig = check.instantiate(call.Pos(), sig, targs, nil).(*Signature)
-		assert(rsig.tparams == nil) // signature is not generic anymore
+		rsig = check.Instantiate(call.Pos(), sig, targs, nil, true).(*Signature)
+		assert(rsig.TParams().Len() == 0) // signature is not generic anymore
 		check.recordInferred(call, targs, rsig)
 
 		// Optimization: Only if the parameter list was adjusted do we
 		// need to compute it from the adjusted list; otherwise we can
 		// simply use the result signature's parameter list.
 		if adjusted {
-			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.tparams, targs)).(*Tuple)
+			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.TParams().list(), targs)).(*Tuple)
 		} else {
 			sigParams = rsig.params
 		}
@@ -471,7 +470,7 @@
 
 	check.instantiatedOperand(x)
 
-	obj, index, indirect = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
+	obj, index, indirect = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
 	if obj == nil {
 		switch {
 		case index != nil:
@@ -483,11 +482,10 @@
 			var why string
 			if tpar := asTypeParam(x.typ); tpar != nil {
 				// Type parameter bounds don't specify fields, so don't mention "field".
-				switch obj := tpar.Bound().obj.(type) {
-				case nil:
+				if tname := tpar.iface().obj; tname != nil {
+					why = check.sprintf("interface %s has no method %s", tname.name, sel)
+				} else {
 					why = check.sprintf("type bound for %s has no method %s", x.typ, sel)
-				case *TypeName:
-					why = check.sprintf("interface %s has no method %s", obj.name, sel)
 				}
 			} else {
 				why = check.sprintf("type %s has no field or method %s", x.typ, sel)
@@ -501,7 +499,7 @@
 				} else {
 					changeCase = string(unicode.ToUpper(r)) + sel[1:]
 				}
-				if obj, _, _ = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
+				if obj, _, _ = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
 					why += ", but does have " + changeCase
 				}
 			}
@@ -519,7 +517,7 @@
 		// the signature accordingly.
 		// TODO(gri) factor this code out
 		sig := m.typ.(*Signature)
-		if len(sig.rparams) > 0 {
+		if sig.RParams().Len() > 0 {
 			// For inference to work, we must use the receiver type
 			// matching the receiver in the actual method declaration.
 			// If the method is embedded, the matching receiver is the
@@ -547,7 +545,7 @@
 			// the receiver type arguments here, the receiver must be be otherwise invalid
 			// and an error has been reported elsewhere.
 			arg := operand{mode: variable, expr: x.expr, typ: recv}
-			targs := check.infer(m, sig.rparams, nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
+			targs := check.infer(m, sig.RParams().list(), nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
 			if targs == nil {
 				// We may reach here if there were other errors (see issue #40056).
 				goto Error
@@ -556,7 +554,7 @@
 			// (If we modify m, some tests will fail; possibly because the m is in use.)
 			// TODO(gri) investigate and provide a correct explanation here
 			copy := *m
-			copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.rparams, targs))
+			copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.RParams().list(), targs))
 			obj = &copy
 		}
 		// TODO(gri) we also need to do substitution for parameterized interface methods
@@ -575,17 +573,37 @@
 
 		check.recordSelection(e, MethodExpr, x.typ, m, index, indirect)
 
+		sig := m.typ.(*Signature)
+		if sig.recv == nil {
+			check.error(e, _InvalidDeclCycle, "illegal cycle in method declaration")
+			goto Error
+		}
+
 		// the receiver type becomes the type of the first function
 		// argument of the method expression's function type
 		var params []*Var
-		sig := m.typ.(*Signature)
 		if sig.params != nil {
 			params = sig.params.vars
 		}
+		// Be consistent about named/unnamed parameters. This is not needed
+		// for type-checking, but the newly constructed signature may appear
+		// in an error message and then have mixed named/unnamed parameters.
+		// (An alternative would be to not print parameter names in errors,
+		// but it's useful to see them; this is cheap and method expressions
+		// are rare.)
+		name := ""
+		if len(params) > 0 && params[0].name != "" {
+			// name needed
+			name = sig.recv.name
+			if name == "" {
+				name = "_"
+			}
+		}
+		params = append([]*Var{NewVar(sig.recv.pos, sig.recv.pkg, name, x.typ)}, params...)
 		x.mode = value
 		x.typ = &Signature{
 			tparams:  sig.tparams,
-			params:   NewTuple(append([]*Var{NewVar(token.NoPos, check.pkg, "_", x.typ)}, params...)...),
+			params:   NewTuple(params...),
 			results:  sig.results,
 			variadic: sig.variadic,
 		}
diff --git a/src/go/types/chan.go b/src/go/types/chan.go
new file mode 100644
index 0000000..1f7b72b
--- /dev/null
+++ b/src/go/types/chan.go
@@ -0,0 +1,35 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Chan represents a channel type.
+type Chan struct {
+	dir  ChanDir
+	elem Type
+}
+
+// A ChanDir value indicates a channel direction.
+type ChanDir int
+
+// The direction of a channel is indicated by one of these constants.
+const (
+	SendRecv ChanDir = iota
+	SendOnly
+	RecvOnly
+)
+
+// NewChan returns a new channel type for the given direction and element type.
+func NewChan(dir ChanDir, elem Type) *Chan {
+	return &Chan{dir: dir, elem: elem}
+}
+
+// Dir returns the direction of channel c.
+func (c *Chan) Dir() ChanDir { return c.dir }
+
+// Elem returns the element type of channel c.
+func (c *Chan) Elem() Type { return c.elem }
+
+func (t *Chan) Underlying() Type { return t }
+func (t *Chan) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/check.go b/src/go/types/check.go
index a923c3c..b2d076d 100644
--- a/src/go/types/check.go
+++ b/src/go/types/check.go
@@ -73,7 +73,7 @@
 // A dotImportKey describes a dot-imported object in the given scope.
 type dotImportKey struct {
 	scope *Scope
-	obj   Object
+	name  string
 }
 
 // A Checker maintains the state of the type checker.
@@ -85,11 +85,11 @@
 	fset *token.FileSet
 	pkg  *Package
 	*Info
-	version version                    // accepted language version
-	objMap  map[Object]*declInfo       // maps package-level objects and (non-interface) methods to declaration info
-	impMap  map[importKey]*Package     // maps (import path, source directory) to (complete or fake) package
-	posMap  map[*Interface][]token.Pos // maps interface types to lists of embedded interface positions
-	typMap  map[string]*Named          // maps an instantiated named type hash to a *Named type
+	version version                // accepted language version
+	nextID  uint64                 // unique Id for type parameters (first valid Id is 1)
+	objMap  map[Object]*declInfo   // maps package-level objects and (non-interface) methods to declaration info
+	impMap  map[importKey]*Package // maps (import path, source directory) to (complete or fake) package
+	typMap  map[string]*Named      // maps an instantiated named type hash to a *Named type
 
 	// pkgPathMap maps package names to the set of distinct import paths we've
 	// seen for that name, anywhere in the import graph. It is used for
@@ -179,9 +179,9 @@
 		info = new(Info)
 	}
 
-	version, err := parseGoVersion(conf.goVersion)
+	version, err := parseGoVersion(conf.GoVersion)
 	if err != nil {
-		panic(fmt.Sprintf("invalid Go version %q (%v)", conf.goVersion, err))
+		panic(fmt.Sprintf("invalid Go version %q (%v)", conf.GoVersion, err))
 	}
 
 	return &Checker{
@@ -192,7 +192,6 @@
 		version: version,
 		objMap:  make(map[Object]*declInfo),
 		impMap:  make(map[importKey]*Package),
-		posMap:  make(map[*Interface][]token.Pos),
 		typMap:  make(map[string]*Named),
 	}
 }
@@ -274,10 +273,6 @@
 
 	check.recordUntyped()
 
-	if check.Info != nil {
-		sanitizeInfo(check.Info)
-	}
-
 	check.pkg.complete = true
 
 	// no longer needed - release memory
@@ -411,8 +406,8 @@
 func (check *Checker) recordInferred(call ast.Expr, targs []Type, sig *Signature) {
 	assert(call != nil)
 	assert(sig != nil)
-	if m := getInferred(check.Info); m != nil {
-		m[call] = _Inferred{targs, sig}
+	if m := check.Info.Inferred; m != nil {
+		m[call] = Inferred{targs, sig}
 	}
 }
 
diff --git a/src/go/types/check_test.go b/src/go/types/check_test.go
index f83abf11..8c8452c 100644
--- a/src/go/types/check_test.go
+++ b/src/go/types/check_test.go
@@ -202,15 +202,13 @@
 	return ""
 }
 
-func checkFiles(t *testing.T, sizes Sizes, goVersion string, filenames []string, srcs [][]byte, manual bool, imp Importer) {
+func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, manual bool, imp Importer) {
 	if len(filenames) == 0 {
 		t.Fatal("no source files")
 	}
 
-	if strings.HasSuffix(filenames[0], ".go2") && !typeparams.Enabled {
-		t.Skip("type params are not enabled")
-	}
-	if strings.HasSuffix(filenames[0], ".go1") && typeparams.Enabled {
+	if strings.HasSuffix(filenames[0], ".go1") {
+		// TODO(rfindley): re-enable this test by using GoVersion.
 		t.Skip("type params are enabled")
 	}
 
@@ -228,6 +226,7 @@
 	}
 
 	// if no Go version is given, consider the package name
+	goVersion := *goVersion
 	if goVersion == "" {
 		goVersion = asGoVersion(pkgName)
 	}
@@ -243,7 +242,7 @@
 	// typecheck and collect typechecker errors
 	var conf Config
 	conf.Sizes = sizes
-	SetGoVersion(&conf, goVersion)
+	conf.GoVersion = goVersion
 
 	// special case for importC.src
 	if len(filenames) == 1 {
@@ -303,29 +302,48 @@
 	}
 }
 
-// TestManual is for manual testing of input files, provided as a list
-// of arguments after the test arguments (and a separating "--"). For
-// instance, to check the files foo.go and bar.go, use:
+// TestManual is for manual testing of a package - either provided
+// as a list of filenames belonging to the package, or a directory
+// name containing the package files - after the test arguments
+// (and a separating "--"). For instance, to test the package made
+// of the files foo.go and bar.go, use:
 //
 // 	go test -run Manual -- foo.go bar.go
 //
-// Provide the -verify flag to verify errors against ERROR comments in
-// the input files rather than having a list of errors reported.
-// The accepted Go language version can be controlled with the -lang flag.
+// If no source arguments are provided, the file testdata/manual.go2
+// is used instead.
+// Provide the -verify flag to verify errors against ERROR comments
+// in the input files rather than having a list of errors reported.
+// The accepted Go language version can be controlled with the -lang
+// flag.
 func TestManual(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
 	filenames := flag.Args()
 	if len(filenames) == 0 {
-		return
+		filenames = []string{filepath.FromSlash("testdata/manual.go2")}
 	}
-	testenv.MustHaveGoBuild(t)
+
+	info, err := os.Stat(filenames[0])
+	if err != nil {
+		t.Fatalf("TestManual: %v", err)
+	}
+
 	DefPredeclaredTestFuncs()
-	testPkg(t, filenames, *goVersion, true)
+	if info.IsDir() {
+		if len(filenames) > 1 {
+			t.Fatal("TestManual: must have only one directory argument")
+		}
+		testDir(t, filenames[0], true)
+	} else {
+		testPkg(t, filenames, true)
+	}
 }
 
 func TestLongConstants(t *testing.T) {
 	format := "package longconst\n\nconst _ = %s\nconst _ = %s // ERROR excessively long constant"
 	src := fmt.Sprintf(format, strings.Repeat("1", 9999), strings.Repeat("1", 10001))
-	checkFiles(t, nil, "", []string{"longconst.go"}, [][]byte{[]byte(src)}, false, nil)
+	testFiles(t, nil, []string{"longconst.go"}, [][]byte{[]byte(src)}, false, nil)
 }
 
 // TestIndexRepresentability tests that constant index operands must
@@ -333,32 +351,24 @@
 // represent larger values.
 func TestIndexRepresentability(t *testing.T) {
 	const src = "package index\n\nvar s []byte\nvar _ = s[int64 /* ERROR \"int64\\(1\\) << 40 \\(.*\\) overflows int\" */ (1) << 40]"
-	checkFiles(t, &StdSizes{4, 4}, "", []string{"index.go"}, [][]byte{[]byte(src)}, false, nil)
-}
-
-func TestIssue46453(t *testing.T) {
-	if typeparams.Enabled {
-		t.Skip("type params are enabled")
-	}
-	const src = "package p\ntype _ comparable // ERROR \"undeclared name: comparable\""
-	checkFiles(t, nil, "", []string{"issue46453.go"}, [][]byte{[]byte(src)}, false, nil)
+	testFiles(t, &StdSizes{4, 4}, []string{"index.go"}, [][]byte{[]byte(src)}, false, nil)
 }
 
 func TestIssue47243_TypedRHS(t *testing.T) {
 	// The RHS of the shift expression below overflows uint on 32bit platforms,
 	// but this is OK as it is explicitly typed.
 	const src = "package issue47243\n\nvar a uint64; var _ = a << uint64(4294967296)" // uint64(1<<32)
-	checkFiles(t, &StdSizes{4, 4}, "", []string{"p.go"}, [][]byte{[]byte(src)}, false, nil)
+	testFiles(t, &StdSizes{4, 4}, []string{"p.go"}, [][]byte{[]byte(src)}, false, nil)
 }
 
-func TestCheck(t *testing.T)     { DefPredeclaredTestFuncs(); testDir(t, "check") }
-func TestExamples(t *testing.T)  { testDir(t, "examples") }
-func TestFixedbugs(t *testing.T) { testDir(t, "fixedbugs") }
+func TestCheck(t *testing.T)     { DefPredeclaredTestFuncs(); testDirFiles(t, "testdata/check", false) }
+func TestExamples(t *testing.T)  { testDirFiles(t, "testdata/examples", false) }
+func TestFixedbugs(t *testing.T) { testDirFiles(t, "testdata/fixedbugs", false) }
 
-func testDir(t *testing.T, dir string) {
+func testDirFiles(t *testing.T, dir string, manual bool) {
 	testenv.MustHaveGoBuild(t)
+	dir = filepath.FromSlash(dir)
 
-	dir = filepath.Join("testdata", dir)
 	fis, err := os.ReadDir(dir)
 	if err != nil {
 		t.Error(err)
@@ -368,28 +378,38 @@
 	for _, fi := range fis {
 		path := filepath.Join(dir, fi.Name())
 
-		// if fi is a directory, its files make up a single package
-		var filenames []string
+		// If fi is a directory, its files make up a single package.
 		if fi.IsDir() {
-			fis, err := os.ReadDir(path)
-			if err != nil {
-				t.Error(err)
-				continue
-			}
-			for _, fi := range fis {
-				filenames = append(filenames, filepath.Join(path, fi.Name()))
-			}
+			testDir(t, path, manual)
 		} else {
-			filenames = []string{path}
+			t.Run(filepath.Base(path), func(t *testing.T) {
+				testPkg(t, []string{path}, manual)
+			})
 		}
-		t.Run(filepath.Base(path), func(t *testing.T) {
-			testPkg(t, filenames, "", false)
-		})
 	}
 }
 
+func testDir(t *testing.T, dir string, manual bool) {
+	testenv.MustHaveGoBuild(t)
+
+	fis, err := os.ReadDir(dir)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	var filenames []string
+	for _, fi := range fis {
+		filenames = append(filenames, filepath.Join(dir, fi.Name()))
+	}
+
+	t.Run(filepath.Base(dir), func(t *testing.T) {
+		testPkg(t, filenames, manual)
+	})
+}
+
 // TODO(rFindley) reconcile the different test setup in go/types with types2.
-func testPkg(t *testing.T, filenames []string, goVersion string, manual bool) {
+func testPkg(t *testing.T, filenames []string, manual bool) {
 	srcs := make([][]byte, len(filenames))
 	for i, filename := range filenames {
 		src, err := os.ReadFile(filename)
@@ -398,5 +418,5 @@
 		}
 		srcs[i] = src
 	}
-	checkFiles(t, nil, goVersion, filenames, srcs, manual, nil)
+	testFiles(t, nil, filenames, srcs, manual, nil)
 }
diff --git a/src/go/types/conversions.go b/src/go/types/conversions.go
index ad6d3ee..a1fcdd4 100644
--- a/src/go/types/conversions.go
+++ b/src/go/types/conversions.go
@@ -94,7 +94,7 @@
 	V := x.typ
 	Vu := under(V)
 	Tu := under(T)
-	if check.identicalIgnoreTags(Vu, Tu) {
+	if IdenticalIgnoreTags(Vu, Tu) {
 		return true
 	}
 
@@ -102,7 +102,7 @@
 	// have identical underlying types if tags are ignored"
 	if V, ok := V.(*Pointer); ok {
 		if T, ok := T.(*Pointer); ok {
-			if check.identicalIgnoreTags(under(V.base), under(T.base)) {
+			if IdenticalIgnoreTags(under(V.base), under(T.base)) {
 				return true
 			}
 		}
@@ -143,7 +143,7 @@
 	if s := asSlice(V); s != nil {
 		if p := asPointer(T); p != nil {
 			if a := asArray(p.Elem()); a != nil {
-				if check.identical(s.Elem(), a.Elem()) {
+				if Identical(s.Elem(), a.Elem()) {
 					if check == nil || check.allowVersion(check.pkg, 1, 17) {
 						return true
 					}
diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index 9211feb..831b1da 100644
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -317,6 +317,7 @@
 		}
 
 	case *Named:
+		t.expand()
 		// don't touch the type if it is from a different package or the Universe scope
 		// (doing so would lead to a race condition - was issue #35049)
 		if t.obj.pkg != check.pkg {
@@ -333,7 +334,7 @@
 		switch t.info {
 		case unknown:
 			t.info = marked
-			t.info = check.validType(t.orig, append(path, t.obj)) // only types of current package added to path
+			t.info = check.validType(t.fromRHS, append(path, t.obj)) // only types of current package added to path
 		case marked:
 			// cycle detected
 			for i, tn := range path {
@@ -349,9 +350,6 @@
 			panic("internal error: cycle start not found")
 		}
 		return t.info
-
-	case *instance:
-		return check.validType(t.expand(), path)
 	}
 
 	return valid
@@ -569,102 +567,6 @@
 	check.initVars(lhs, []ast.Expr{init}, token.NoPos)
 }
 
-// under returns the expanded underlying type of n0; possibly by following
-// forward chains of named types. If an underlying type is found, resolve
-// the chain by setting the underlying type for each defined type in the
-// chain before returning it. If no underlying type is found or a cycle
-// is detected, the result is Typ[Invalid]. If a cycle is detected and
-// n0.check != nil, the cycle is reported.
-func (n0 *Named) under() Type {
-	u := n0.underlying
-
-	if u == Typ[Invalid] {
-		return u
-	}
-
-	// If the underlying type of a defined type is not a defined
-	// (incl. instance) type, then that is the desired underlying
-	// type.
-	switch u.(type) {
-	case nil:
-		return Typ[Invalid]
-	default:
-		// common case
-		return u
-	case *Named, *instance:
-		// handled below
-	}
-
-	if n0.check == nil {
-		panic("internal error: Named.check == nil but type is incomplete")
-	}
-
-	// Invariant: after this point n0 as well as any named types in its
-	// underlying chain should be set up when this function exits.
-	check := n0.check
-
-	// If we can't expand u at this point, it is invalid.
-	n := asNamed(u)
-	if n == nil {
-		n0.underlying = Typ[Invalid]
-		return n0.underlying
-	}
-
-	// Otherwise, follow the forward chain.
-	seen := map[*Named]int{n0: 0}
-	path := []Object{n0.obj}
-	for {
-		u = n.underlying
-		if u == nil {
-			u = Typ[Invalid]
-			break
-		}
-		var n1 *Named
-		switch u1 := u.(type) {
-		case *Named:
-			n1 = u1
-		case *instance:
-			n1, _ = u1.expand().(*Named)
-			if n1 == nil {
-				u = Typ[Invalid]
-			}
-		}
-		if n1 == nil {
-			break // end of chain
-		}
-
-		seen[n] = len(seen)
-		path = append(path, n.obj)
-		n = n1
-
-		if i, ok := seen[n]; ok {
-			// cycle
-			check.cycleError(path[i:])
-			u = Typ[Invalid]
-			break
-		}
-	}
-
-	for n := range seen {
-		// We should never have to update the underlying type of an imported type;
-		// those underlying types should have been resolved during the import.
-		// Also, doing so would lead to a race condition (was issue #31749).
-		// Do this check always, not just in debug mode (it's cheap).
-		if n.obj.pkg != check.pkg {
-			panic("internal error: imported type with unresolved underlying type")
-		}
-		n.underlying = u
-	}
-
-	return u
-}
-
-func (n *Named) setUnderlying(typ Type) {
-	if n != nil {
-		n.underlying = typ
-	}
-}
-
 func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) {
 	assert(obj.typ == nil)
 
@@ -680,58 +582,57 @@
 		alias = false
 	}
 
+	// alias declaration
 	if alias {
-		// type alias declaration
 		if !check.allowVersion(check.pkg, 1, 9) {
 			check.errorf(atPos(tdecl.Assign), _BadDecl, "type aliases requires go1.9 or later")
 		}
 
 		obj.typ = Typ[Invalid]
 		obj.typ = check.anyType(tdecl.Type)
-
-	} else {
-		// defined type declaration
-
-		named := check.newNamed(obj, nil, nil)
-		def.setUnderlying(named)
-		obj.typ = named // make sure recursive type declarations terminate
-
-		if tparams := typeparams.Get(tdecl); tparams != nil {
-			check.openScope(tdecl, "type parameters")
-			defer check.closeScope()
-			named.tparams = check.collectTypeParams(tparams)
-		}
-
-		// determine underlying type of named
-		named.orig = check.definedType(tdecl.Type, named)
-
-		// The underlying type of named may be itself a named type that is
-		// incomplete:
-		//
-		//	type (
-		//		A B
-		//		B *C
-		//		C A
-		//	)
-		//
-		// The type of C is the (named) type of A which is incomplete,
-		// and which has as its underlying type the named type B.
-		// Determine the (final, unnamed) underlying type by resolving
-		// any forward chain.
-		// TODO(gri) Investigate if we can just use named.origin here
-		//           and rely on lazy computation of the underlying type.
-		named.underlying = under(named)
-	}
-
-}
-
-func (check *Checker) collectTypeParams(list *ast.FieldList) (tparams []*TypeName) {
-	// Type parameter lists should not be empty. The parser will
-	// complain but we still may get an incorrect AST: ignore it.
-	if list.NumFields() == 0 {
 		return
 	}
 
+	// type definition or generic type declaration
+	named := check.newNamed(obj, nil, nil, nil, nil)
+	def.setUnderlying(named)
+
+	if tparams := typeparams.Get(tdecl); tparams != nil {
+		check.openScope(tdecl, "type parameters")
+		defer check.closeScope()
+		named.tparams = check.collectTypeParams(tparams)
+	}
+
+	// determine underlying type of named
+	named.fromRHS = check.definedType(tdecl.Type, named)
+	assert(named.fromRHS != nil)
+
+	// The underlying type of named may be itself a named type that is
+	// incomplete:
+	//
+	//	type (
+	//		A B
+	//		B *C
+	//		C A
+	//	)
+	//
+	// The type of C is the (named) type of A which is incomplete,
+	// and which has as its underlying type the named type B.
+	// Determine the (final, unnamed) underlying type by resolving
+	// any forward chain.
+	// TODO(gri) Investigate if we can just use named.fromRHS here
+	//           and rely on lazy computation of the underlying type.
+	named.underlying = under(named)
+
+	// If the RHS is a type parameter, it must be from this type declaration.
+	if tpar, _ := named.underlying.(*TypeParam); tpar != nil && tparamIndex(named.TParams().list(), tpar) < 0 {
+		check.errorf(tdecl.Type, _Todo, "cannot use function type parameter %s as RHS in type declaration", tpar)
+		named.underlying = Typ[Invalid]
+	}
+}
+
+func (check *Checker) collectTypeParams(list *ast.FieldList) *TypeParams {
+	var tparams []*TypeName
 	// Declare type parameters up-front, with empty interface as type bound.
 	// The scope of type parameters starts at the beginning of the type parameter
 	// list (so we can have mutually recursive parameterized interfaces).
@@ -739,52 +640,28 @@
 		tparams = check.declareTypeParams(tparams, f.Names)
 	}
 
-	setBoundAt := func(at int, bound Type) {
-		assert(IsInterface(bound))
-		tparams[at].typ.(*_TypeParam).bound = bound
-	}
-
 	index := 0
 	var bound Type
 	for _, f := range list.List {
 		if f.Type == nil {
 			goto next
 		}
-
-		// The predeclared identifier "any" is visible only as a constraint
-		// in a type parameter list. Look for it before general constraint
-		// resolution.
-		if tident, _ := unparen(f.Type).(*ast.Ident); tident != nil && tident.Name == "any" && check.lookup("any") == nil {
-			bound = universeAny
-		} else {
-			bound = check.typ(f.Type)
-		}
-
-		// type bound must be an interface
-		// TODO(gri) We should delay the interface check because
-		//           we may not have a complete interface yet:
-		//           type C(type T C) interface {}
-		//           (issue #39724).
-		if _, ok := under(bound).(*Interface); ok {
-			// Otherwise, set the bound for each type parameter.
-			for i := range f.Names {
-				setBoundAt(index+i, bound)
-			}
-		} else if bound != Typ[Invalid] {
-			check.errorf(f.Type, _Todo, "%s is not an interface", bound)
+		bound = check.boundType(f.Type)
+		for i := range f.Names {
+			tparams[index+i].typ.(*TypeParam).bound = bound
 		}
 
 	next:
 		index += len(f.Names)
 	}
 
-	return
+	return bindTParams(tparams)
 }
 
 func (check *Checker) declareTypeParams(tparams []*TypeName, names []*ast.Ident) []*TypeName {
 	for _, name := range names {
 		tpar := NewTypeName(name.Pos(), check.pkg, name.Name, nil)
-		check.newTypeParam(tpar, len(tparams), &emptyInterface) // assigns type to tpar as a side-effect
+		check.NewTypeParam(tpar, &emptyInterface)               // assigns type to tpar as a side-effect
 		check.declare(check.scope, name, tpar, check.scope.pos) // TODO(gri) check scope position
 		tparams = append(tparams, tpar)
 	}
@@ -796,6 +673,25 @@
 	return tparams
 }
 
+// boundType type-checks the type expression e and returns its type, or Typ[Invalid].
+// The type must be an interface, including the predeclared type "any".
+func (check *Checker) boundType(e ast.Expr) Type {
+	// The predeclared identifier "any" is visible only as a type bound in a type parameter list.
+	// If we allow "any" for general use, this if-statement can be removed (issue #33232).
+	if name, _ := unparen(e).(*ast.Ident); name != nil && name.Name == "any" && check.lookup("any") == universeAny {
+		return universeAny.Type()
+	}
+
+	bound := check.typ(e)
+	check.later(func() {
+		u := under(bound)
+		if _, ok := u.(*Interface); !ok && u != Typ[Invalid] {
+			check.errorf(e, _Todo, "%s is not an interface", bound)
+		}
+	})
+	return bound
+}
+
 func (check *Checker) collectMethods(obj *TypeName) {
 	// get associated methods
 	// (Checker.collectObjects only collects methods with non-blank names;
@@ -815,7 +711,7 @@
 	// and field names must be distinct."
 	base := asNamed(obj.typ) // shouldn't fail but be conservative
 	if base != nil {
-		if t, _ := base.underlying.(*Struct); t != nil {
+		if t, _ := base.Underlying().(*Struct); t != nil {
 			for _, fld := range t.fields {
 				if fld.name != "_" {
 					assert(mset.insert(fld) == nil)
@@ -851,6 +747,7 @@
 		}
 
 		if base != nil {
+			base.load() // TODO(mdempsky): Probably unnecessary.
 			base.methods = append(base.methods, m)
 		}
 	}
diff --git a/src/go/types/errorcodes.go b/src/go/types/errorcodes.go
index 3d24da7..bcc850f 100644
--- a/src/go/types/errorcodes.go
+++ b/src/go/types/errorcodes.go
@@ -281,16 +281,7 @@
 	_IncomparableMapKey
 
 	// _InvalidIfaceEmbed occurs when a non-interface type is embedded in an
-	// interface.
-	//
-	// Example:
-	//  type T struct {}
-	//
-	//  func (T) m()
-	//
-	//  type I interface {
-	//  	T
-	//  }
+	// interface (for go 1.17 or earlier).
 	_InvalidIfaceEmbed
 
 	// _InvalidPtrEmbed occurs when an embedded field is of the pointer form *T,
@@ -884,7 +875,7 @@
 	// context in which it is used.
 	//
 	// Example:
-	//  var _ = 1 + ""
+	//  var _ = 1 + nil
 	_InvalidUntypedConversion
 
 	// _BadOffsetofSyntax occurs when unsafe.Offsetof is called with an argument
diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index 58962e7..c9a55aa 100644
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -144,6 +144,14 @@
 	token.SHL: "shift",
 }
 
+func underIs(typ Type, f func(Type) bool) bool {
+	u := under(typ)
+	if tpar, _ := u.(*TypeParam); tpar != nil {
+		return tpar.underIs(f)
+	}
+	return f(u)
+}
+
 // The unary expression e may be nil. It's passed in for better error messages only.
 func (check *Checker) unary(x *operand, e *ast.UnaryExpr) {
 	check.expr(x, e.X)
@@ -164,19 +172,29 @@
 		return
 
 	case token.ARROW:
-		typ := asChan(x.typ)
-		if typ == nil {
-			check.invalidOp(x, _InvalidReceive, "cannot receive from non-channel %s", x)
-			x.mode = invalid
-			return
-		}
-		if typ.dir == SendOnly {
-			check.invalidOp(x, _InvalidReceive, "cannot receive from send-only channel %s", x)
+		var elem Type
+		if !underIs(x.typ, func(u Type) bool {
+			ch, _ := u.(*Chan)
+			if ch == nil {
+				check.invalidOp(x, _InvalidReceive, "cannot receive from non-channel %s", x)
+				return false
+			}
+			if ch.dir == SendOnly {
+				check.invalidOp(x, _InvalidReceive, "cannot receive from send-only channel %s", x)
+				return false
+			}
+			if elem != nil && !Identical(ch.elem, elem) {
+				check.invalidOp(x, _Todo, "channels of %s must have the same element type", x)
+				return false
+			}
+			elem = ch.elem
+			return true
+		}) {
 			x.mode = invalid
 			return
 		}
 		x.mode = commaok
-		x.typ = typ.elem
+		x.typ = elem
 		check.hasCallOrRecv = true
 		return
 	}
@@ -622,7 +640,7 @@
 		return x.typ, nil, 0
 	}
 
-	switch t := optype(target).(type) {
+	switch t := under(target).(type) {
 	case *Basic:
 		if x.mode == constant_ {
 			v, code := check.representation(x, t)
@@ -661,8 +679,8 @@
 		default:
 			return nil, nil, _InvalidUntypedConversion
 		}
-	case *_Sum:
-		ok := t.is(func(t Type) bool {
+	case *TypeParam:
+		ok := t.underIs(func(t Type) bool {
 			target, _, _ := check.implicitTypeAndValue(x, t)
 			return target != nil
 		})
@@ -682,7 +700,6 @@
 			return Typ[UntypedNil], nil, 0
 		}
 		// cannot assign untyped values to non-empty interfaces
-		check.completeInterface(token.NoPos, t)
 		if !t.Empty() {
 			return nil, nil, _InvalidUntypedConversion
 		}
@@ -943,14 +960,28 @@
 		return
 	}
 
-	check.convertUntyped(x, y.typ)
-	if x.mode == invalid {
-		return
+	canMix := func(x, y *operand) bool {
+		if IsInterface(x.typ) || IsInterface(y.typ) {
+			return true
+		}
+		if isBoolean(x.typ) != isBoolean(y.typ) {
+			return false
+		}
+		if isString(x.typ) != isString(y.typ) {
+			return false
+		}
+		return true
 	}
-	check.convertUntyped(&y, x.typ)
-	if y.mode == invalid {
-		x.mode = invalid
-		return
+	if canMix(x, &y) {
+		check.convertUntyped(x, y.typ)
+		if x.mode == invalid {
+			return
+		}
+		check.convertUntyped(&y, x.typ)
+		if y.mode == invalid {
+			x.mode = invalid
+			return
+		}
 	}
 
 	if isComparison(op) {
@@ -958,7 +989,7 @@
 		return
 	}
 
-	if !check.identical(x.typ, y.typ) {
+	if !Identical(x.typ, y.typ) {
 		// only report an error if we have valid types
 		// (otherwise we had an error reported elsewhere already)
 		if x.typ != Typ[Invalid] && y.typ != Typ[Invalid] {
@@ -1154,7 +1185,7 @@
 			goto Error
 		}
 
-		switch utyp := optype(base).(type) {
+		switch utyp := under(base).(type) {
 		case *Struct:
 			if len(e.Elts) == 0 {
 				break
@@ -1284,7 +1315,7 @@
 					xkey := keyVal(x.val)
 					if asInterface(utyp.key) != nil {
 						for _, vtyp := range visited[xkey] {
-							if check.identical(vtyp, x.typ) {
+							if Identical(vtyp, x.typ) {
 								duplicate = true
 								break
 							}
@@ -1333,9 +1364,10 @@
 	case *ast.SelectorExpr:
 		check.selector(x, e)
 
-	case *ast.IndexExpr:
-		if check.indexExpr(x, e) {
-			check.funcInst(x, e)
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(e)
+		if check.indexExpr(x, ix) {
+			check.funcInst(x, ix)
 		}
 		if x.mode == invalid {
 			goto Error
@@ -1384,13 +1416,24 @@
 		case typexpr:
 			x.typ = &Pointer{base: x.typ}
 		default:
-			if typ := asPointer(x.typ); typ != nil {
-				x.mode = variable
-				x.typ = typ.base
-			} else {
-				check.invalidOp(x, _InvalidIndirection, "cannot indirect %s", x)
+			var base Type
+			if !underIs(x.typ, func(u Type) bool {
+				p, _ := u.(*Pointer)
+				if p == nil {
+					check.invalidOp(x, _InvalidIndirection, "cannot indirect %s", x)
+					return false
+				}
+				if base != nil && !Identical(p.base, base) {
+					check.invalidOp(x, _Todo, "pointers of %s must have identical base types", x)
+					return false
+				}
+				base = p.base
+				return true
+			}) {
 				goto Error
 			}
+			x.mode = variable
+			x.typ = base
 		}
 
 	case *ast.UnaryExpr:
@@ -1425,12 +1468,7 @@
 		// types, which are comparatively rare.
 
 	default:
-		if typeparams.IsListExpr(e) {
-			// catch-all for unexpected expression lists
-			check.errorf(e, _Todo, "unexpected list of expressions")
-		} else {
-			panic(fmt.Sprintf("%s: unknown expression type %T", check.fset.Position(e.Pos()), e))
-		}
+		panic(fmt.Sprintf("%s: unknown expression type %T", check.fset.Position(e.Pos()), e))
 	}
 
 	// everything went well
@@ -1475,7 +1513,7 @@
 	}
 	var msg string
 	if wrongType != nil {
-		if check.identical(method.typ, wrongType.typ) {
+		if Identical(method.typ, wrongType.typ) {
 			msg = fmt.Sprintf("missing method %s (%s has pointer receiver)", method.name, method.name)
 		} else {
 			msg = fmt.Sprintf("wrong type for method %s (have %s, want %s)", method.name, wrongType.typ, method.typ)
diff --git a/src/go/types/exprstring.go b/src/go/types/exprstring.go
index f05e642..aee8a5b 100644
--- a/src/go/types/exprstring.go
+++ b/src/go/types/exprstring.go
@@ -67,11 +67,11 @@
 		buf.WriteByte('.')
 		buf.WriteString(x.Sel.Name)
 
-	case *ast.IndexExpr:
-		WriteExpr(buf, x.X)
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(x)
+		WriteExpr(buf, ix.X)
 		buf.WriteByte('[')
-		exprs := typeparams.UnpackExpr(x.Index)
-		for i, e := range exprs {
+		for i, e := range ix.Indices {
 			if i > 0 {
 				buf.WriteString(", ")
 			}
diff --git a/src/go/types/exprstring_test.go b/src/go/types/exprstring_test.go
index 5110288..a67f6a9 100644
--- a/src/go/types/exprstring_test.go
+++ b/src/go/types/exprstring_test.go
@@ -27,6 +27,40 @@
 	{"func(x int) complex128 {}", "(func(x int) complex128 literal)"},
 	{"[]int{1, 2, 3}", "([]int literal)"},
 
+	// type expressions
+	dup("[1 << 10]byte"),
+	dup("[]int"),
+	dup("*int"),
+	dup("struct{x int}"),
+	dup("func()"),
+	dup("func(int, float32) string"),
+	dup("interface{m()}"),
+	dup("interface{m() string; n(x int)}"),
+	dup("interface{type int}"),
+
+	// The following exprs do not get formatted correctly: each element in the
+	// type list is printed on a separate line. This is left as a placeholder
+	// until type lists are removed.
+	// TODO(rfindley): remove this once type lists are gone.
+	// dup("interface{type int, float64, string}"),
+	// dup("interface{type int; m()}"),
+	// dup("interface{type int, float64, string; m() string; n(x int)}"),
+	dup("map[string]int"),
+	dup("chan E"),
+	dup("<-chan E"),
+	dup("chan<- E"),
+
+	// new interfaces
+	dup("interface{int}"),
+	dup("interface{~int}"),
+	dup("interface{~int}"),
+	dup("interface{int | string}"),
+	dup("interface{~int | ~string; float64; m()}"),
+
+	// See above.
+	// dup("interface{type a, b, c; ~int | ~string; float64; m()}"),
+	dup("interface{~T[int, string] | string}"),
+
 	// non-type expressions
 	dup("(x)"),
 	dup("x.f"),
diff --git a/src/go/types/index.go b/src/go/types/index.go
index 2ba3475..a49bc55 100644
--- a/src/go/types/index.go
+++ b/src/go/types/index.go
@@ -15,25 +15,25 @@
 // If e is a valid function instantiation, indexExpr returns true.
 // In that case x represents the uninstantiated function value and
 // it is the caller's responsibility to instantiate the function.
-func (check *Checker) indexExpr(x *operand, e *ast.IndexExpr) (isFuncInst bool) {
+func (check *Checker) indexExpr(x *operand, e *typeparams.IndexExpr) (isFuncInst bool) {
 	check.exprOrType(x, e.X)
 
 	switch x.mode {
 	case invalid:
-		check.use(typeparams.UnpackExpr(e.Index)...)
+		check.use(e.Indices...)
 		return false
 
 	case typexpr:
 		// type instantiation
 		x.mode = invalid
-		x.typ = check.varType(e)
+		x.typ = check.varType(e.Orig)
 		if x.typ != Typ[Invalid] {
 			x.mode = typexpr
 		}
 		return false
 
 	case value:
-		if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
+		if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
 			// function instantiation
 			return true
 		}
@@ -41,7 +41,7 @@
 
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch typ := optype(x.typ).(type) {
+	switch typ := under(x.typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			valid = true
@@ -80,7 +80,7 @@
 		index := check.singleIndex(e)
 		if index == nil {
 			x.mode = invalid
-			return
+			return false
 		}
 		var key operand
 		check.expr(&key, index)
@@ -88,88 +88,81 @@
 		// ok to continue even if indexing failed - map element type is known
 		x.mode = mapindex
 		x.typ = typ.elem
-		x.expr = e
-		return
+		x.expr = e.Orig
+		return false
 
-	case *_Sum:
-		// A sum type can be indexed if all of the sum's types
-		// support indexing and have the same index and element
-		// type. Special rules apply for maps in the sum type.
-		var tkey, telem Type // key is for map types only
-		nmaps := 0           // number of map types in sum type
-		if typ.is(func(t Type) bool {
-			var e Type
-			switch t := under(t).(type) {
+	case *TypeParam:
+		// TODO(gri) report detailed failure cause for better error messages
+		var tkey, telem Type // tkey != nil if we have maps
+		if typ.underIs(func(u Type) bool {
+			var key, elem Type
+			alen := int64(-1) // valid if >= 0
+			switch t := u.(type) {
 			case *Basic:
-				if isString(t) {
-					e = universeByte
-				}
-			case *Array:
-				e = t.elem
-			case *Pointer:
-				if t := asArray(t.base); t != nil {
-					e = t.elem
-				}
-			case *Slice:
-				e = t.elem
-			case *Map:
-				// If there are multiple maps in the sum type,
-				// they must have identical key types.
-				// TODO(gri) We may be able to relax this rule
-				// but it becomes complicated very quickly.
-				if tkey != nil && !Identical(t.key, tkey) {
+				if !isString(t) {
 					return false
 				}
-				tkey = t.key
-				e = t.elem
-				nmaps++
-			case *_TypeParam:
-				check.errorf(x, 0, "type of %s contains a type parameter - cannot index (implementation restriction)", x)
-			case *instance:
-				panic("unimplemented")
-			}
-			if e == nil || telem != nil && !Identical(e, telem) {
+				elem = universeByte
+			case *Array:
+				elem = t.elem
+				alen = t.len
+			case *Pointer:
+				a, _ := under(t.base).(*Array)
+				if a == nil {
+					return false
+				}
+				elem = a.elem
+				alen = a.len
+			case *Slice:
+				elem = t.elem
+			case *Map:
+				key = t.key
+				elem = t.elem
+			default:
 				return false
 			}
-			telem = e
+			assert(elem != nil)
+			if telem == nil {
+				// first type
+				tkey, telem = key, elem
+				length = alen
+			} else {
+				// all map keys must be identical (incl. all nil)
+				if !Identical(key, tkey) {
+					return false
+				}
+				// all element types must be identical
+				if !Identical(elem, telem) {
+					return false
+				}
+				tkey, telem = key, elem
+				// track the minimal length for arrays
+				if alen >= 0 && alen < length {
+					length = alen
+				}
+			}
 			return true
 		}) {
-			// If there are maps, the index expression must be assignable
-			// to the map key type (as for simple map index expressions).
-			if nmaps > 0 {
+			// For maps, the index expression must be assignable to the map key type.
+			if tkey != nil {
 				index := check.singleIndex(e)
 				if index == nil {
 					x.mode = invalid
-					return
+					return false
 				}
 				var key operand
 				check.expr(&key, index)
 				check.assignment(&key, tkey, "map index")
 				// ok to continue even if indexing failed - map element type is known
-
-				// If there are only maps, we are done.
-				if nmaps == len(typ.types) {
-					x.mode = mapindex
-					x.typ = telem
-					x.expr = e
-					return
-				}
-
-				// Otherwise we have mix of maps and other types. For
-				// now we require that the map key be an integer type.
-				// TODO(gri) This is probably not good enough.
-				valid = isInteger(tkey)
-				// avoid 2nd indexing error if indexing failed above
-				if !valid && key.mode == invalid {
-					x.mode = invalid
-					return
-				}
-				x.mode = value // map index expressions are not addressable
-			} else {
-				// no maps
-				valid = true
-				x.mode = variable
+				x.mode = mapindex
+				x.typ = telem
+				x.expr = e
+				return false
 			}
+
+			// no maps
+			valid = true
+			x.mode = variable
 			x.typ = telem
 		}
 	}
@@ -177,13 +170,13 @@
 	if !valid {
 		check.invalidOp(x, _NonIndexableOperand, "cannot index %s", x)
 		x.mode = invalid
-		return
+		return false
 	}
 
 	index := check.singleIndex(e)
 	if index == nil {
 		x.mode = invalid
-		return
+		return false
 	}
 
 	// In pathological (invalid) cases (e.g.: type T1 [][[]T1{}[0][0]]T0)
@@ -206,7 +199,7 @@
 
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch typ := optype(x.typ).(type) {
+	switch typ := under(x.typ).(type) {
 	case *Basic:
 		if isString(typ) {
 			if e.Slice3 {
@@ -246,8 +239,8 @@
 		valid = true
 		// x.typ doesn't change
 
-	case *_Sum, *_TypeParam:
-		check.errorf(x, 0, "generic slice expressions not yet implemented")
+	case *TypeParam:
+		check.errorf(x, _Todo, "generic slice expressions not yet implemented")
 		x.mode = invalid
 		return
 	}
@@ -311,23 +304,16 @@
 // singleIndex returns the (single) index from the index expression e.
 // If the index is missing, or if there are multiple indices, an error
 // is reported and the result is nil.
-func (check *Checker) singleIndex(e *ast.IndexExpr) ast.Expr {
-	index := e.Index
-	if index == nil {
-		check.invalidAST(e, "missing index for %s", e)
+func (check *Checker) singleIndex(expr *typeparams.IndexExpr) ast.Expr {
+	if len(expr.Indices) == 0 {
+		check.invalidAST(expr.Orig, "index expression %v with 0 indices", expr)
 		return nil
 	}
-
-	indexes := typeparams.UnpackExpr(index)
-	if len(indexes) == 0 {
-		check.invalidAST(index, "index expression %v with 0 indices", index)
-		return nil
-	}
-	if len(indexes) > 1 {
+	if len(expr.Indices) > 1 {
 		// TODO(rFindley) should this get a distinct error code?
-		check.invalidOp(indexes[1], _InvalidIndex, "more than one index")
+		check.invalidOp(expr.Indices[1], _InvalidIndex, "more than one index")
 	}
-	return indexes[0]
+	return expr.Indices[0]
 }
 
 // index checks an index expression for validity.
diff --git a/src/go/types/infer.go b/src/go/types/infer.go
index 5d49351..6e70a10 100644
--- a/src/go/types/infer.go
+++ b/src/go/types/infer.go
@@ -93,7 +93,7 @@
 	// Unify parameter and argument types for generic parameters with typed arguments
 	// and collect the indices of generic parameters with untyped arguments.
 	// Terminology: generic parameter = function parameter with a type-parameterized type
-	u := newUnifier(check, false)
+	u := newUnifier(false)
 	u.x.init(tparams)
 
 	// Set the type arguments which we know already.
@@ -189,7 +189,7 @@
 		// only parameter type it can possibly match against is a *TypeParam.
 		// Thus, only consider untyped arguments for generic parameters that
 		// are not of composite types and which don't have a type inferred yet.
-		if tpar, _ := par.typ.(*_TypeParam); tpar != nil && targs[tpar.index] == nil {
+		if tpar, _ := par.typ.(*TypeParam); tpar != nil && targs[tpar.index] == nil {
 			arg := args[i]
 			targ := Default(arg.typ)
 			// The default type for an untyped nil is untyped nil. We must not
@@ -302,8 +302,8 @@
 			}
 		}
 
-	case *_Sum:
-		return w.isParameterizedList(t.types)
+	case *Union:
+		return w.isParameterizedTermList(t.terms)
 
 	case *Signature:
 		// t.tparams may not be nil if we are looking at a signature
@@ -316,24 +316,13 @@
 		return w.isParameterized(t.params) || w.isParameterized(t.results)
 
 	case *Interface:
-		if t.allMethods != nil {
-			// TODO(rFindley) at some point we should enforce completeness here
-			for _, m := range t.allMethods {
-				if w.isParameterized(m.typ) {
-					return true
-				}
+		tset := t.typeSet()
+		for _, m := range tset.methods {
+			if w.isParameterized(m.typ) {
+				return true
 			}
-			return w.isParameterizedList(unpackType(t.allTypes))
 		}
-
-		return t.iterate(func(t *Interface) bool {
-			for _, m := range t.methods {
-				if w.isParameterized(m.typ) {
-					return true
-				}
-			}
-			return w.isParameterizedList(unpackType(t.types))
-		}, nil)
+		return w.isParameterized(tset.types)
 
 	case *Map:
 		return w.isParameterized(t.key) || w.isParameterized(t.elem)
@@ -342,15 +331,12 @@
 		return w.isParameterized(t.elem)
 
 	case *Named:
-		return w.isParameterizedList(t.targs)
+		return w.isParameterizedTypeList(t.targs)
 
-	case *_TypeParam:
+	case *TypeParam:
 		// t must be one of w.tparams
 		return t.index < len(w.tparams) && w.tparams[t.index].typ == t
 
-	case *instance:
-		return w.isParameterizedList(t.targs)
-
 	default:
 		unreachable()
 	}
@@ -358,7 +344,7 @@
 	return false
 }
 
-func (w *tpWalker) isParameterizedList(list []Type) bool {
+func (w *tpWalker) isParameterizedTypeList(list []Type) bool {
 	for _, t := range list {
 		if w.isParameterized(t) {
 			return true
@@ -367,6 +353,15 @@
 	return false
 }
 
+func (w *tpWalker) isParameterizedTermList(list []*term) bool {
+	for _, t := range list {
+		if w.isParameterized(t.typ) {
+			return true
+		}
+	}
+	return false
+}
+
 // inferB returns the list of actual type arguments inferred from the type parameters'
 // bounds and an initial set of type arguments. If type inference is impossible because
 // unification fails, an error is reported if report is set to true, the resulting types
@@ -380,7 +375,7 @@
 
 	// Setup bidirectional unification between those structural bounds
 	// and the corresponding type arguments (which may be nil!).
-	u := newUnifier(check, false)
+	u := newUnifier(false)
 	u.x.init(tparams)
 	u.y = u.x // type parameters between LHS and RHS of unification are identical
 
@@ -393,7 +388,7 @@
 
 	// Unify type parameters with their structural constraints, if any.
 	for _, tpar := range tparams {
-		typ := tpar.typ.(*_TypeParam)
+		typ := tpar.typ.(*TypeParam)
 		sbound := check.structuralType(typ.bound)
 		if sbound != nil {
 			if !u.unify(typ, sbound) {
@@ -407,8 +402,8 @@
 
 	// u.x.types() now contains the incoming type arguments plus any additional type
 	// arguments for which there were structural constraints. The newly inferred non-
-	// nil entries may still contain references to other type parameters. For instance,
-	// for [A any, B interface{type []C}, C interface{type *A}], if A == int
+	// nil entries may still contain references to other type parameters.
+	// For instance, for [A any, B interface{ []C }, C interface{ *A }], if A == int
 	// was given, unification produced the type list [int, []C, *A]. We eliminate the
 	// remaining type parameters by substituting the type parameters in this type list
 	// until nothing changes anymore.
@@ -471,12 +466,16 @@
 // structuralType returns the structural type of a constraint, if any.
 func (check *Checker) structuralType(constraint Type) Type {
 	if iface, _ := under(constraint).(*Interface); iface != nil {
-		check.completeInterface(token.NoPos, iface)
-		types := unpackType(iface.allTypes)
-		if len(types) == 1 {
-			return types[0]
+		types := iface.typeSet().types
+		if u, _ := types.(*Union); u != nil {
+			if u.NumTerms() == 1 {
+				// TODO(gri) do we need to respect tilde?
+				t, _ := u.Term(0)
+				return t
+			}
+			return nil
 		}
-		return nil
+		return types
 	}
-	return constraint
+	return nil
 }
diff --git a/src/go/types/instantiate.go b/src/go/types/instantiate.go
new file mode 100644
index 0000000..6d56eb7
--- /dev/null
+++ b/src/go/types/instantiate.go
@@ -0,0 +1,248 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file implements instantiation of generic types
+// through substitution of type parameters by type arguments.
+
+package types
+
+import (
+	"fmt"
+	"go/token"
+)
+
+// Instantiate instantiates the type typ with the given type arguments
+// targs. To check type constraint satisfaction, verify must be set.
+// pos and posList correspond to the instantiation and type argument
+// positions respectively; posList may be nil or shorter than the number
+// of type arguments provided.
+// typ must be a *Named or a *Signature type, and its number of type
+// parameters must match the number of provided type arguments.
+// The receiver (check) may be nil if and only if verify is not set.
+// The result is a new, instantiated (not generic) type of the same kind
+// (either a *Named or a *Signature).
+// Any methods attached to a *Named are simply copied; they are not
+// instantiated.
+func (check *Checker) Instantiate(pos token.Pos, typ Type, targs []Type, posList []token.Pos, verify bool) (res Type) {
+	var tparams []*TypeName
+	switch t := typ.(type) {
+	case *Named:
+		tparams = t.TParams().list()
+	case *Signature:
+		tparams = t.TParams().list()
+		defer func() {
+			// If we had an unexpected failure somewhere don't panic below when
+			// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
+			// is returned.
+			if _, ok := res.(*Signature); !ok {
+				return
+			}
+			// If the signature doesn't use its type parameters, subst
+			// will not make a copy. In that case, make a copy now (so
+			// we can set tparams to nil w/o causing side-effects).
+			if t == res {
+				copy := *t
+				res = &copy
+			}
+			// After instantiating a generic signature, it is not generic
+			// anymore; we need to set tparams to nil.
+			res.(*Signature).tparams = nil
+		}()
+	default:
+		// only types and functions can be generic
+		panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
+	}
+
+	inst := check.instantiate(pos, typ, tparams, targs, posList)
+	if verify && len(tparams) == len(targs) {
+		check.verify(pos, tparams, targs, posList)
+	}
+	return inst
+}
+
+func (check *Checker) instantiate(pos token.Pos, typ Type, tparams []*TypeName, targs []Type, posList []token.Pos) (res Type) {
+	// the number of supplied types must match the number of type parameters
+	if len(targs) != len(tparams) {
+		// TODO(gri) provide better error message
+		if check != nil {
+			check.errorf(atPos(pos), _Todo, "got %d arguments but %d type parameters", len(targs), len(tparams))
+			return Typ[Invalid]
+		}
+		panic(fmt.Sprintf("%v: got %d arguments but %d type parameters", pos, len(targs), len(tparams)))
+	}
+
+	if check != nil && trace {
+		check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
+		check.indent++
+		defer func() {
+			check.indent--
+			var under Type
+			if res != nil {
+				// Calling under() here may lead to endless instantiations.
+				// Test case: type T[P any] T[P]
+				// TODO(gri) investigate if that's a bug or to be expected.
+				under = res.Underlying()
+			}
+			check.trace(pos, "=> %s (under = %s)", res, under)
+		}()
+	}
+
+	assert(len(posList) <= len(targs))
+
+	// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
+
+	if len(tparams) == 0 {
+		return typ // nothing to do (minor optimization)
+	}
+
+	smap := makeSubstMap(tparams, targs)
+
+	return check.subst(pos, typ, smap)
+}
+
+// InstantiateLazy is like Instantiate, but avoids actually
+// instantiating the type until needed. typ must be a *Named
+// type.
+func (check *Checker) InstantiateLazy(pos token.Pos, typ Type, targs []Type, posList []token.Pos, verify bool) Type {
+	// Don't use asNamed here: we don't want to expand the base during lazy
+	// instantiation.
+	base := typ.(*Named)
+	if base == nil {
+		panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
+	}
+	if verify && base.TParams().Len() == len(targs) {
+		check.later(func() {
+			check.verify(pos, base.tparams.list(), targs, posList)
+		})
+	}
+	h := instantiatedHash(base, targs)
+	if check != nil {
+		// typ may already have been instantiated with identical type arguments. In
+		// that case, re-use the existing instance.
+		if named := check.typMap[h]; named != nil {
+			return named
+		}
+	}
+
+	tname := NewTypeName(pos, base.obj.pkg, base.obj.name, nil)
+	named := check.newNamed(tname, base, nil, nil, nil) // methods and tparams are set when named is loaded.
+	named.targs = targs
+	named.instance = &instance{pos, posList}
+
+	if check != nil {
+		check.typMap[h] = named
+	}
+
+	return named
+}
+
+func (check *Checker) verify(pos token.Pos, tparams []*TypeName, targs []Type, posList []token.Pos) {
+	if check == nil {
+		panic("cannot have nil Checker if verifying constraints")
+	}
+
+	smap := makeSubstMap(tparams, targs)
+	for i, tname := range tparams {
+		// best position for error reporting
+		pos := pos
+		if i < len(posList) {
+			pos = posList[i]
+		}
+
+		// stop checking bounds after the first failure
+		if !check.satisfies(pos, targs[i], tname.typ.(*TypeParam), smap) {
+			break
+		}
+	}
+}
+
+// satisfies reports whether the type argument targ satisfies the constraint of type parameter
+// parameter tpar (after any of its type parameters have been substituted through smap).
+// A suitable error is reported if the result is false.
+// TODO(gri) This should be a method of interfaces or type sets.
+func (check *Checker) satisfies(pos token.Pos, targ Type, tpar *TypeParam, smap *substMap) bool {
+	iface := tpar.iface()
+	if iface.Empty() {
+		return true // no type bound
+	}
+
+	// The type parameter bound is parameterized with the same type parameters
+	// as the instantiated type; before we can use it for bounds checking we
+	// need to instantiate it with the type arguments with which we instantiate
+	// the parameterized type.
+	iface = check.subst(pos, iface, smap).(*Interface)
+
+	// if iface is comparable, targ must be comparable
+	// TODO(gri) the error messages needs to be better, here
+	if iface.IsComparable() && !Comparable(targ) {
+		if tpar := asTypeParam(targ); tpar != nil && tpar.iface().typeSet().IsTop() {
+			check.softErrorf(atPos(pos), _Todo, "%s has no constraints", targ)
+			return false
+		}
+		check.softErrorf(atPos(pos), _Todo, "%s does not satisfy comparable", targ)
+		return false
+	}
+
+	// targ must implement iface (methods)
+	// - check only if we have methods
+	if iface.NumMethods() > 0 {
+		// If the type argument is a pointer to a type parameter, the type argument's
+		// method set is empty.
+		// TODO(gri) is this what we want? (spec question)
+		if base, isPtr := deref(targ); isPtr && asTypeParam(base) != nil {
+			check.errorf(atPos(pos), 0, "%s has no methods", targ)
+			return false
+		}
+		if m, wrong := check.missingMethod(targ, iface, true); m != nil {
+			// TODO(gri) needs to print updated name to avoid major confusion in error message!
+			//           (print warning for now)
+			// Old warning:
+			// check.softErrorf(pos, "%s does not satisfy %s (warning: name not updated) = %s (missing method %s)", targ, tpar.bound, iface, m)
+			if wrong != nil {
+				// TODO(gri) This can still report uninstantiated types which makes the error message
+				//           more difficult to read then necessary.
+				// TODO(rFindley) should this use parentheses rather than ':' for qualification?
+				check.softErrorf(atPos(pos), _Todo,
+					"%s does not satisfy %s: wrong method signature\n\tgot  %s\n\twant %s",
+					targ, tpar.bound, wrong, m,
+				)
+			} else {
+				check.softErrorf(atPos(pos), 0, "%s does not satisfy %s (missing method %s)", targ, tpar.bound, m.name)
+			}
+			return false
+		}
+	}
+
+	// targ's underlying type must also be one of the interface types listed, if any
+	if iface.typeSet().types == nil {
+		return true // nothing to do
+	}
+
+	// If targ is itself a type parameter, each of its possible types, but at least one, must be in the
+	// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
+	if targ := asTypeParam(targ); targ != nil {
+		targBound := targ.iface()
+		if targBound.typeSet().types == nil {
+			check.softErrorf(atPos(pos), _Todo, "%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
+			return false
+		}
+		return iface.is(func(typ Type, tilde bool) bool {
+			// TODO(gri) incorporate tilde information!
+			if !iface.isSatisfiedBy(typ) {
+				// TODO(gri) match this error message with the one below (or vice versa)
+				check.softErrorf(atPos(pos), 0, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, typ, iface.typeSet().types)
+				return false
+			}
+			return true
+		})
+	}
+
+	// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
+	if !iface.isSatisfiedBy(targ) {
+		check.softErrorf(atPos(pos), _Todo, "%s does not satisfy %s (%s not found in %s)", targ, tpar.bound, targ, iface.typeSet().types)
+		return false
+	}
+
+	return true
+}
diff --git a/src/go/types/interface.go b/src/go/types/interface.go
new file mode 100644
index 0000000..d8f9671
--- /dev/null
+++ b/src/go/types/interface.go
@@ -0,0 +1,280 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/ast"
+	"go/internal/typeparams"
+	"go/token"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// An Interface represents an interface type.
+type Interface struct {
+	obj       *TypeName    // type name object defining this interface; or nil (for better error messages)
+	methods   []*Func      // ordered list of explicitly declared methods
+	embeddeds []Type       // ordered list of explicitly embedded elements
+	embedPos  *[]token.Pos // positions of embedded elements; or nil (for error messages) - use pointer to save space
+	complete  bool         // indicates that obj, methods, and embeddeds are set and type set can be computed
+
+	tset *_TypeSet // type set described by this interface, computed lazily
+}
+
+// typeSet returns the type set for interface t.
+func (t *Interface) typeSet() *_TypeSet { return computeTypeSet(nil, token.NoPos, t) }
+
+// is reports whether interface t represents types that all satisfy f.
+func (t *Interface) is(f func(Type, bool) bool) bool {
+	switch t := t.typeSet().types.(type) {
+	case nil, *top:
+		// TODO(gri) should settle on top or nil to represent this case
+		return false // we must have at least one type! (was bug)
+	case *Union:
+		return t.is(func(t *term) bool { return f(t.typ, t.tilde) })
+	default:
+		return f(t, false)
+	}
+}
+
+// emptyInterface represents the empty (completed) interface
+var emptyInterface = Interface{complete: true, tset: &topTypeSet}
+
+// NewInterface returns a new interface for the given methods and embedded types.
+// NewInterface takes ownership of the provided methods and may modify their types
+// by setting missing receivers.
+//
+// Deprecated: Use NewInterfaceType instead which allows arbitrary embedded types.
+func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
+	tnames := make([]Type, len(embeddeds))
+	for i, t := range embeddeds {
+		tnames[i] = t
+	}
+	return NewInterfaceType(methods, tnames)
+}
+
+// NewInterfaceType returns a new interface for the given methods and embedded types.
+// NewInterfaceType takes ownership of the provided methods and may modify their types
+// by setting missing receivers.
+func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
+	if len(methods) == 0 && len(embeddeds) == 0 {
+		return &emptyInterface
+	}
+
+	// set method receivers if necessary
+	typ := new(Interface)
+	for _, m := range methods {
+		if sig := m.typ.(*Signature); sig.recv == nil {
+			sig.recv = NewVar(m.pos, m.pkg, "", typ)
+		}
+	}
+
+	// sort for API stability
+	sortMethods(methods)
+
+	typ.methods = methods
+	typ.embeddeds = embeddeds
+	typ.complete = true
+
+	return typ
+}
+
+// NumExplicitMethods returns the number of explicitly declared methods of interface t.
+func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
+
+// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
+
+// NumEmbeddeds returns the number of embedded types in interface t.
+func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
+
+// Embedded returns the i'th embedded defined (*Named) type of interface t for 0 <= i < t.NumEmbeddeds().
+// The result is nil if the i'th embedded type is not a defined type.
+//
+// Deprecated: Use EmbeddedType which is not restricted to defined (*Named) types.
+func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named); return tname }
+
+// EmbeddedType returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
+func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
+
+// NumMethods returns the total number of methods of interface t.
+func (t *Interface) NumMethods() int { return t.typeSet().NumMethods() }
+
+// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) Method(i int) *Func { return t.typeSet().Method(i) }
+
+// Empty reports whether t is the empty interface.
+func (t *Interface) Empty() bool { return t.typeSet().IsTop() }
+
+// IsComparable reports whether each type in interface t's type set is comparable.
+func (t *Interface) IsComparable() bool { return t.typeSet().IsComparable() }
+
+// IsConstraint reports whether interface t is not just a method set.
+func (t *Interface) IsConstraint() bool { return !t.typeSet().IsMethodSet() }
+
+// isSatisfiedBy reports whether interface t's type list is satisfied by the type typ.
+// If the type list is empty (absent), typ trivially satisfies the interface.
+// TODO(gri) This is not a great name. Eventually, we should have a more comprehensive
+//           "implements" predicate.
+func (t *Interface) isSatisfiedBy(typ Type) bool {
+	t.Complete()
+	switch t := t.typeSet().types.(type) {
+	case nil:
+		return true // no type restrictions
+	case *Union:
+		r, _ := t.intersect(typ, false)
+		return r != nil
+	default:
+		return Identical(t, typ)
+	}
+}
+
+// Complete computes the interface's type set. It must be called by users of
+// NewInterfaceType and NewInterface after the interface's embedded types are
+// fully defined and before using the interface type in any way other than to
+// form other types. The interface must not contain duplicate methods or a
+// panic occurs. Complete returns the receiver.
+//
+// Deprecated: Type sets are now computed lazily, on demand; this function
+//             is only here for backward-compatibility. It does not have to
+//             be called explicitly anymore.
+func (t *Interface) Complete() *Interface {
+	// Some tests are still depending on the state change
+	// (string representation of an Interface not containing an
+	// /* incomplete */ marker) caused by the explicit Complete
+	// call, so we compute the type set eagerly here.
+	t.complete = true
+	t.typeSet()
+	return t
+}
+
+func (t *Interface) Underlying() Type { return t }
+func (t *Interface) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, def *Named) {
+	var tlist []ast.Expr
+	var tname *ast.Ident // "type" name of first entry in a type list declaration
+
+	addEmbedded := func(pos token.Pos, typ Type) {
+		ityp.embeddeds = append(ityp.embeddeds, typ)
+		if ityp.embedPos == nil {
+			ityp.embedPos = new([]token.Pos)
+		}
+		*ityp.embedPos = append(*ityp.embedPos, pos)
+	}
+
+	for _, f := range iface.Methods.List {
+		if len(f.Names) == 0 {
+			// We have an embedded type; possibly a union of types.
+			addEmbedded(f.Type.Pos(), parseUnion(check, flattenUnion(nil, f.Type)))
+			continue
+		}
+
+		// We have a method with name f.Names[0], or a type
+		// of a type list (name.Name == "type").
+		// (The parser ensures that there's only one method
+		// and we don't care if a constructed AST has more.)
+		name := f.Names[0]
+		if name.Name == "_" {
+			check.errorf(name, _BlankIfaceMethod, "invalid method name _")
+			continue // ignore
+		}
+
+		// TODO(rfindley) Remove type list handling once the parser doesn't accept type lists anymore.
+		if name.Name == "type" {
+			// Report an error for the first type list per interface
+			// if we don't allow type lists, but continue.
+			if !allowTypeLists && tlist == nil {
+				check.softErrorf(name, _Todo, "use generalized embedding syntax instead of a type list")
+			}
+			// For now, collect all type list entries as if it
+			// were a single union, where each union element is
+			// of the form ~T.
+			// TODO(rfindley) remove once we disallow type lists
+			op := new(ast.UnaryExpr)
+			op.Op = token.TILDE
+			op.X = f.Type
+			tlist = append(tlist, op)
+			// Report an error if we have multiple type lists in an
+			// interface, but only if they are permitted in the first place.
+			if allowTypeLists && tname != nil && tname != name {
+				check.errorf(name, _Todo, "cannot have multiple type lists in an interface")
+			}
+			tname = name
+			continue
+		}
+
+		typ := check.typ(f.Type)
+		sig, _ := typ.(*Signature)
+		if sig == nil {
+			if typ != Typ[Invalid] {
+				check.invalidAST(f.Type, "%s is not a method signature", typ)
+			}
+			continue // ignore
+		}
+
+		// Always type-check method type parameters but complain if they are not enabled.
+		// (This extra check is needed here because interface method signatures don't have
+		// a receiver specification.)
+		if sig.tparams != nil {
+			var at positioner = f.Type
+			if tparams := typeparams.Get(f.Type); tparams != nil {
+				at = tparams
+			}
+			check.errorf(at, _Todo, "methods cannot have type parameters")
+		}
+
+		// use named receiver type if available (for better error messages)
+		var recvTyp Type = ityp
+		if def != nil {
+			recvTyp = def
+		}
+		sig.recv = NewVar(name.Pos(), check.pkg, "", recvTyp)
+
+		m := NewFunc(name.Pos(), check.pkg, name.Name, sig)
+		check.recordDef(name, m)
+		ityp.methods = append(ityp.methods, m)
+	}
+
+	// type constraints
+	if tlist != nil {
+		// TODO(rfindley): this differs from types2 due to the use of Pos() below,
+		// which should actually be on the ~. Confirm that this position is correct.
+		addEmbedded(tlist[0].Pos(), parseUnion(check, tlist))
+	}
+
+	// All methods and embedded elements for this interface are collected;
+	// i.e., this interface is may be used in a type set computation.
+	ityp.complete = true
+
+	if len(ityp.methods) == 0 && len(ityp.embeddeds) == 0 {
+		// empty interface
+		ityp.tset = &topTypeSet
+		return
+	}
+
+	// sort for API stability
+	sortMethods(ityp.methods)
+	// (don't sort embeddeds: they must correspond to *embedPos entries)
+
+	// Compute type set with a non-nil *Checker as soon as possible
+	// to report any errors. Subsequent uses of type sets will use
+	// this computed type set and won't need to pass in a *Checker.
+	check.later(func() { computeTypeSet(check, iface.Pos(), ityp) })
+}
+
+func flattenUnion(list []ast.Expr, x ast.Expr) []ast.Expr {
+	if o, _ := x.(*ast.BinaryExpr); o != nil && o.Op == token.OR {
+		list = flattenUnion(list, o.X)
+		x = o.Y
+	}
+	return append(list, x)
+}
diff --git a/src/go/types/issues_test.go b/src/go/types/issues_test.go
index 519e199..51995af 100644
--- a/src/go/types/issues_test.go
+++ b/src/go/types/issues_test.go
@@ -634,7 +634,7 @@
 	}
 	imp := importHelper{pkg: a, fallback: importer.Default()}
 
-	checkFiles(t, nil, "", []string{"b.go"}, [][]byte{[]byte(bsrc)}, false, imp)
-	checkFiles(t, nil, "", []string{"c.go"}, [][]byte{[]byte(csrc)}, false, imp)
-	checkFiles(t, nil, "", []string{"t.go"}, [][]byte{[]byte(tsrc)}, false, imp)
+	testFiles(t, nil, []string{"b.go"}, [][]byte{[]byte(bsrc)}, false, imp)
+	testFiles(t, nil, []string{"c.go"}, [][]byte{[]byte(csrc)}, false, imp)
+	testFiles(t, nil, []string{"t.go"}, [][]byte{[]byte(tsrc)}, false, imp)
 }
diff --git a/src/go/types/labels.go b/src/go/types/labels.go
index 8cf6e63..f3b7f21 100644
--- a/src/go/types/labels.go
+++ b/src/go/types/labels.go
@@ -36,7 +36,8 @@
 	}
 
 	// spec: "It is illegal to define a label that is never used."
-	for _, obj := range all.elems {
+	for name, obj := range all.elems {
+		obj = resolve(name, obj)
 		if lbl := obj.(*Label); !lbl.used {
 			check.softErrorf(lbl, _UnusedLabel, "label %s declared but not used", lbl.name)
 		}
diff --git a/src/go/types/lookup.go b/src/go/types/lookup.go
index 9c7bfd4..7cab336 100644
--- a/src/go/types/lookup.go
+++ b/src/go/types/lookup.go
@@ -8,6 +8,11 @@
 
 import "go/token"
 
+// Internal use of LookupFieldOrMethod: If the obj result is a method
+// associated with a concrete (non-interface) type, the method's signature
+// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
+// the method's type.
+
 // LookupFieldOrMethod looks up a field or method with given package and name
 // in T and returns the corresponding *Var or *Func, an index sequence, and a
 // bool indicating if there were any pointer indirections on the path to the
@@ -35,19 +40,6 @@
 //	the method's formal receiver base type, nor was the receiver addressable.
 //
 func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
-	return (*Checker)(nil).lookupFieldOrMethod(T, addressable, pkg, name)
-}
-
-// Internal use of Checker.lookupFieldOrMethod: If the obj result is a method
-// associated with a concrete (non-interface) type, the method's signature
-// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
-// the method's type.
-// TODO(gri) Now that we provide the *Checker, we can probably remove this
-// caveat by calling Checker.objDecl from lookupFieldOrMethod. Investigate.
-
-// lookupFieldOrMethod is like the external version but completes interfaces
-// as necessary.
-func (check *Checker) lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// Methods cannot be associated to a named pointer type
 	// (spec: "The type denoted by T is called the receiver base type;
 	// it must not be a pointer or interface type and it must be declared
@@ -56,8 +48,8 @@
 	// pointer type but discard the result if it is a method since we would
 	// not have found it for T (see also issue 8590).
 	if t := asNamed(T); t != nil {
-		if p, _ := t.underlying.(*Pointer); p != nil {
-			obj, index, indirect = check.rawLookupFieldOrMethod(p, false, pkg, name)
+		if p, _ := t.Underlying().(*Pointer); p != nil {
+			obj, index, indirect = lookupFieldOrMethod(p, false, pkg, name)
 			if _, ok := obj.(*Func); ok {
 				return nil, nil, false
 			}
@@ -65,7 +57,7 @@
 		}
 	}
 
-	return check.rawLookupFieldOrMethod(T, addressable, pkg, name)
+	return lookupFieldOrMethod(T, addressable, pkg, name)
 }
 
 // TODO(gri) The named type consolidation and seen maps below must be
@@ -73,10 +65,9 @@
 //           types always have only one representation (even when imported
 //           indirectly via different packages.)
 
-// rawLookupFieldOrMethod should only be called by lookupFieldOrMethod and missingMethod.
-func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
+// lookupFieldOrMethod should only be called by LookupFieldOrMethod and missingMethod.
+func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// WARNING: The code in this function is extremely subtle - do not modify casually!
-	//          This function and NewMethodSet should be kept in sync.
 
 	if name == "_" {
 		return // blank fields/methods are never found
@@ -84,10 +75,12 @@
 
 	typ, isPtr := deref(T)
 
-	// *typ where typ is an interface has no methods.
-	// Be cautious: typ may be nil (issue 39634, crash #3).
-	if typ == nil || isPtr && IsInterface(typ) {
-		return
+	// *typ where typ is an interface or type parameter has no methods.
+	switch under(typ).(type) {
+	case *Interface, *TypeParam:
+		if isPtr {
+			return
+		}
 	}
 
 	// Start with typ as single entry at shallowest depth.
@@ -107,7 +100,7 @@
 		var next []embeddedType // embedded types found at current depth
 
 		// look for (pkg, name) in all types at current depth
-		var tpar *_TypeParam // set if obj receiver is a type parameter
+		var tpar *TypeParam // set if obj receiver is a type parameter
 		for _, e := range current {
 			typ := e.typ
 
@@ -128,6 +121,7 @@
 				seen[named] = true
 
 				// look for a matching attached method
+				named.load()
 				if i, m := lookupMethod(named.methods, pkg, name); m != nil {
 					// potential match
 					// caution: method may not have a proper signature yet
@@ -185,9 +179,7 @@
 
 			case *Interface:
 				// look for a matching method
-				// TODO(gri) t.allMethods is sorted - use binary search
-				check.completeInterface(token.NoPos, t)
-				if i, m := lookupMethod(t.allMethods, pkg, name); m != nil {
+				if i, m := t.typeSet().LookupMethod(pkg, name); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -197,10 +189,8 @@
 					indirect = e.indirect
 				}
 
-			case *_TypeParam:
-				// only consider explicit methods in the type parameter bound, not
-				// methods that may be common to all types in the type list.
-				if i, m := lookupMethod(t.Bound().allMethods, pkg, name); m != nil {
+			case *TypeParam:
+				if i, m := t.iface().typeSet().LookupMethod(pkg, name); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -229,7 +219,7 @@
 			return
 		}
 
-		current = check.consolidateMultiples(next)
+		current = consolidateMultiples(next)
 	}
 
 	return nil, nil, false // not found
@@ -246,7 +236,7 @@
 // consolidateMultiples collects multiple list entries with the same type
 // into a single entry marked as containing multiples. The result is the
 // consolidated list.
-func (check *Checker) consolidateMultiples(list []embeddedType) []embeddedType {
+func consolidateMultiples(list []embeddedType) []embeddedType {
 	if len(list) <= 1 {
 		return list // at most one entry - nothing to do
 	}
@@ -254,7 +244,7 @@
 	n := 0                     // number of entries w/ unique type
 	prev := make(map[Type]int) // index at which type was previously seen
 	for _, e := range list {
-		if i, found := check.lookupType(prev, e.typ); found {
+		if i, found := lookupType(prev, e.typ); found {
 			list[i].multiples = true
 			// ignore this entry
 		} else {
@@ -266,14 +256,14 @@
 	return list[:n]
 }
 
-func (check *Checker) lookupType(m map[Type]int, typ Type) (int, bool) {
+func lookupType(m map[Type]int, typ Type) (int, bool) {
 	// fast path: maybe the types are equal
 	if i, found := m[typ]; found {
 		return i, true
 	}
 
 	for t, i := range m {
-		if check.identical(t, typ) {
+		if Identical(t, typ) {
 			return i, true
 		}
 	}
@@ -306,40 +296,40 @@
 // To improve error messages, also report the wrong signature
 // when the method exists on *V instead of V.
 func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method, wrongType *Func) {
-	check.completeInterface(token.NoPos, T)
-
 	// fast path for common case
 	if T.Empty() {
 		return
 	}
 
 	if ityp := asInterface(V); ityp != nil {
-		check.completeInterface(token.NoPos, ityp)
-		// TODO(gri) allMethods is sorted - can do this more efficiently
-		for _, m := range T.allMethods {
-			_, f := lookupMethod(ityp.allMethods, m.pkg, m.name)
+		// TODO(gri) the methods are sorted - could do this more efficiently
+		for _, m := range T.typeSet().methods {
+			_, f := ityp.typeSet().LookupMethod(m.pkg, m.name)
 
 			if f == nil {
-				// if m is the magic method == we're ok (interfaces are comparable)
-				if m.name == "==" || !static {
+				if !static {
 					continue
 				}
 				return m, f
 			}
 
+			// both methods must have the same number of type parameters
 			ftyp := f.typ.(*Signature)
 			mtyp := m.typ.(*Signature)
-			if len(ftyp.tparams) != len(mtyp.tparams) {
+			if ftyp.TParams().Len() != mtyp.TParams().Len() {
 				return m, f
 			}
+			if ftyp.TParams().Len() > 0 {
+				panic("internal error: method with type parameters")
+			}
 
 			// If the methods have type parameters we don't care whether they
 			// are the same or not, as long as they match up. Use unification
 			// to see if they can be made to match.
 			// TODO(gri) is this always correct? what about type bounds?
 			// (Alternative is to rename/subst type parameters and compare.)
-			u := newUnifier(check, true)
-			u.x.init(ftyp.tparams)
+			u := newUnifier(true)
+			u.x.init(ftyp.TParams().list())
 			if !u.unify(ftyp, mtyp) {
 				return m, f
 			}
@@ -351,14 +341,14 @@
 	// A concrete type implements T if it implements all methods of T.
 	Vd, _ := deref(V)
 	Vn := asNamed(Vd)
-	for _, m := range T.allMethods {
+	for _, m := range T.typeSet().methods {
 		// TODO(gri) should this be calling lookupFieldOrMethod instead (and why not)?
-		obj, _, _ := check.rawLookupFieldOrMethod(V, false, m.pkg, m.name)
+		obj, _, _ := lookupFieldOrMethod(V, false, m.pkg, m.name)
 
 		// Check if *V implements this method of T.
 		if obj == nil {
 			ptr := NewPointer(V)
-			obj, _, _ = check.rawLookupFieldOrMethod(ptr, false, m.pkg, m.name)
+			obj, _, _ = lookupFieldOrMethod(ptr, false, m.pkg, m.name)
 			if obj != nil {
 				return m, obj.(*Func)
 			}
@@ -367,10 +357,6 @@
 		// we must have a method (not a field of matching function type)
 		f, _ := obj.(*Func)
 		if f == nil {
-			// if m is the magic method == and V is comparable, we're ok
-			if m.name == "==" && Comparable(V) {
-				continue
-			}
 			return m, nil
 		}
 
@@ -382,9 +368,12 @@
 		// both methods must have the same number of type parameters
 		ftyp := f.typ.(*Signature)
 		mtyp := m.typ.(*Signature)
-		if len(ftyp.tparams) != len(mtyp.tparams) {
+		if ftyp.TParams().Len() != mtyp.TParams().Len() {
 			return m, f
 		}
+		if ftyp.TParams().Len() > 0 {
+			panic("internal error: method with type parameters")
+		}
 
 		// If V is a (instantiated) generic type, its methods are still
 		// parameterized using the original (declaration) receiver type
@@ -393,17 +382,17 @@
 		// In order to compare the signatures, substitute the receiver
 		// type parameters of ftyp with V's instantiation type arguments.
 		// This lazily instantiates the signature of method f.
-		if Vn != nil && len(Vn.tparams) > 0 {
+		if Vn != nil && Vn.TParams().Len() > 0 {
 			// Be careful: The number of type arguments may not match
 			// the number of receiver parameters. If so, an error was
 			// reported earlier but the length discrepancy is still
 			// here. Exit early in this case to prevent an assertion
 			// failure in makeSubstMap.
 			// TODO(gri) Can we avoid this check by fixing the lengths?
-			if len(ftyp.rparams) != len(Vn.targs) {
+			if len(ftyp.RParams().list()) != len(Vn.targs) {
 				return
 			}
-			ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.rparams, Vn.targs)).(*Signature)
+			ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.RParams().list(), Vn.targs)).(*Signature)
 		}
 
 		// If the methods have type parameters we don't care whether they
@@ -411,8 +400,8 @@
 		// to see if they can be made to match.
 		// TODO(gri) is this always correct? what about type bounds?
 		// (Alternative is to rename/subst type parameters and compare.)
-		u := newUnifier(check, true)
-		u.x.init(ftyp.tparams)
+		u := newUnifier(true)
+		u.x.init(ftyp.RParams().list())
 		if !u.unify(ftyp, mtyp) {
 			return m, f
 		}
diff --git a/src/go/types/map.go b/src/go/types/map.go
new file mode 100644
index 0000000..01e13b2
--- /dev/null
+++ b/src/go/types/map.go
@@ -0,0 +1,24 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Map represents a map type.
+type Map struct {
+	key, elem Type
+}
+
+// NewMap returns a new map for the given key and element types.
+func NewMap(key, elem Type) *Map {
+	return &Map{key: key, elem: elem}
+}
+
+// Key returns the key type of map m.
+func (m *Map) Key() Type { return m.key }
+
+// Elem returns the element type of map m.
+func (m *Map) Elem() Type { return m.elem }
+
+func (t *Map) Underlying() Type { return t }
+func (t *Map) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/methodset.go b/src/go/types/methodset.go
index ae8011a..1462601 100644
--- a/src/go/types/methodset.go
+++ b/src/go/types/methodset.go
@@ -130,7 +130,7 @@
 				// continue with underlying type, but only if it's not a type parameter
 				// TODO(rFindley): should this use named.under()? Can there be a difference?
 				typ = named.underlying
-				if _, ok := typ.(*_TypeParam); ok {
+				if _, ok := typ.(*TypeParam); ok {
 					continue
 				}
 			}
@@ -157,10 +157,10 @@
 				}
 
 			case *Interface:
-				mset = mset.add(t.allMethods, e.index, true, e.multiples)
+				mset = mset.add(t.typeSet().methods, e.index, true, e.multiples)
 
-			case *_TypeParam:
-				mset = mset.add(t.Bound().allMethods, e.index, true, e.multiples)
+			case *TypeParam:
+				mset = mset.add(t.iface().typeSet().methods, e.index, true, e.multiples)
 			}
 		}
 
@@ -190,12 +190,7 @@
 			}
 		}
 
-		// It's ok to call consolidateMultiples with a nil *Checker because
-		// MethodSets are not used internally (outside debug mode). When used
-		// externally, interfaces are expected to be completed and then we do
-		// not need a *Checker to complete them when (indirectly) calling
-		// Checker.identical via consolidateMultiples.
-		current = (*Checker)(nil).consolidateMultiples(next)
+		current = consolidateMultiples(next)
 	}
 
 	if len(base) == 0 {
diff --git a/src/go/types/methodset_test.go b/src/go/types/methodset_test.go
index 4a373fa..73a8442 100644
--- a/src/go/types/methodset_test.go
+++ b/src/go/types/methodset_test.go
@@ -7,7 +7,6 @@
 import (
 	"testing"
 
-	"go/internal/typeparams"
 	. "go/types"
 )
 
@@ -47,12 +46,15 @@
 
 	genericTests := map[string][]method{
 		// By convention, look up a in the scope of "g"
-		"type C interface{ f() }; func g[T C](a T){}":                       {{"f", []int{0}, true}},
-		"type C interface{ f() }; func g[T C]() { var a T; _ = a }":         {{"f", []int{0}, true}},
-		"type C interface{ f() }; func g[T C]() { var a struct{T}; _ = a }": {{"f", []int{0, 0}, true}},
+		"type C interface{ f() }; func g[T C](a T){}":               {{"f", []int{0}, true}},
+		"type C interface{ f() }; func g[T C]() { var a T; _ = a }": {{"f", []int{0}, true}},
 
-		// Issue #45639.
-		"type C interface{ f() }; func g[T C]() { type Y T; var a Y; _ = a }": {},
+		// Issue #43621: We don't allow this anymore. Keep this code in case we
+		// decide to revisit this decision.
+		// "type C interface{ f() }; func g[T C]() { var a struct{T}; _ = a }": {{"f", []int{0, 0}, true}},
+
+		// Issue #45639: We also don't allow this anymore.
+		// "type C interface{ f() }; func g[T C]() { type Y T; var a Y; _ = a }": {},
 	}
 
 	check := func(src string, methods []method, generic bool) {
@@ -101,9 +103,7 @@
 		check(src, methods, false)
 	}
 
-	if typeparams.Enabled {
-		for src, methods := range genericTests {
-			check(src, methods, true)
-		}
+	for src, methods := range genericTests {
+		check(src, methods, true)
 	}
 }
diff --git a/src/go/types/named.go b/src/go/types/named.go
new file mode 100644
index 0000000..f26b50a
--- /dev/null
+++ b/src/go/types/named.go
@@ -0,0 +1,296 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/token"
+	"sync"
+)
+
+// TODO(rfindley) Clean up Named struct below; specifically the fromRHS field (can we use underlying?).
+
+// A Named represents a named (defined) type.
+type Named struct {
+	check      *Checker
+	info       typeInfo    // for cycle detection
+	obj        *TypeName   // corresponding declared object
+	orig       *Named      // original, uninstantiated type
+	fromRHS    Type        // type (on RHS of declaration) this *Named type is derived of (for cycle reporting)
+	underlying Type        // possibly a *Named during setup; never a *Named once set up completely
+	instance   *instance   // syntactic information for lazy instantiation
+	tparams    *TypeParams // type parameters, or nil
+	targs      []Type      // type arguments (after instantiation), or nil
+	methods    []*Func     // methods declared for this type (not the method set of this type); signatures are type-checked lazily
+
+	resolve func(*Named) ([]*TypeName, Type, []*Func)
+	once    sync.Once
+}
+
+// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
+// If the given type name obj doesn't have a type yet, its type is set to the returned named type.
+// The underlying type must not be a *Named.
+func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
+	if _, ok := underlying.(*Named); ok {
+		panic("types.NewNamed: underlying type must not be *Named")
+	}
+	return (*Checker)(nil).newNamed(obj, nil, underlying, nil, methods)
+}
+
+func (t *Named) load() *Named {
+	// If t is an instantiated type, it derives its methods and tparams from its
+	// base type. Since we expect type parameters and methods to be set after a
+	// call to load, we must load the base and copy here.
+	//
+	// underlying is set when t is expanded.
+	//
+	// By convention, a type instance is loaded iff its tparams are set.
+	if len(t.targs) > 0 && t.tparams == nil {
+		t.orig.load()
+		t.tparams = t.orig.tparams
+		t.methods = t.orig.methods
+	}
+	if t.resolve == nil {
+		return t
+	}
+
+	t.once.Do(func() {
+		// TODO(mdempsky): Since we're passing t to resolve anyway
+		// (necessary because types2 expects the receiver type for methods
+		// on defined interface types to be the Named rather than the
+		// underlying Interface), maybe it should just handle calling
+		// SetTParams, SetUnderlying, and AddMethod instead?  Those
+		// methods would need to support reentrant calls though.  It would
+		// also make the API more future-proof towards further extensions
+		// (like SetTParams).
+
+		tparams, underlying, methods := t.resolve(t)
+
+		switch underlying.(type) {
+		case nil, *Named:
+			panic("invalid underlying type")
+		}
+
+		t.tparams = bindTParams(tparams)
+		t.underlying = underlying
+		t.methods = methods
+	})
+	return t
+}
+
+// newNamed is like NewNamed but with a *Checker receiver and additional orig argument.
+func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams *TypeParams, methods []*Func) *Named {
+	typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods}
+	if typ.orig == nil {
+		typ.orig = typ
+	}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	// Ensure that typ is always expanded, at which point the check field can be
+	// nilled out.
+	//
+	// Note that currently we cannot nil out check inside typ.under(), because
+	// it's possible that typ is expanded multiple times.
+	//
+	// TODO(rFindley): clean this up so that under is the only function mutating
+	//                 named types.
+	if check != nil {
+		check.later(func() {
+			switch typ.under().(type) {
+			case *Named:
+				panic("internal error: unexpanded underlying type")
+			}
+			typ.check = nil
+		})
+	}
+	return typ
+}
+
+// Obj returns the type name for the named type t.
+func (t *Named) Obj() *TypeName { return t.obj }
+
+// _Orig returns the original generic type an instantiated type is derived from.
+// If t is not an instantiated type, the result is t.
+func (t *Named) _Orig() *Named { return t.orig }
+
+// TODO(gri) Come up with a better representation and API to distinguish
+//           between parameterized instantiated and non-instantiated types.
+
+// TParams returns the type parameters of the named type t, or nil.
+// The result is non-nil for an (originally) parameterized type even if it is instantiated.
+func (t *Named) TParams() *TypeParams { return t.load().tparams }
+
+// SetTParams sets the type parameters of the named type t.
+func (t *Named) SetTParams(tparams []*TypeName) { t.load().tparams = bindTParams(tparams) }
+
+// NumTArgs returns the number of type arguments used to instantiate the named
+// type t, or 0 if t is not an instantiated type.
+func (t *Named) NumTArgs() int { return len(t.targs) }
+
+// TArgs returns the i'th type argument of the named type t for 0 <= i < t.NumTArgs().
+func (t *Named) TArg(i int) Type { return t.targs[i] }
+
+// SetTArgs sets the type arguments of the named type t.
+func (t *Named) SetTArgs(args []Type) { t.targs = args }
+
+// NumMethods returns the number of explicit methods whose receiver is named type t.
+func (t *Named) NumMethods() int { return len(t.load().methods) }
+
+// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
+func (t *Named) Method(i int) *Func { return t.load().methods[i] }
+
+// SetUnderlying sets the underlying type and marks t as complete.
+func (t *Named) SetUnderlying(underlying Type) {
+	if underlying == nil {
+		panic("types.Named.SetUnderlying: underlying type must not be nil")
+	}
+	if _, ok := underlying.(*Named); ok {
+		panic("types.Named.SetUnderlying: underlying type must not be *Named")
+	}
+	t.load().underlying = underlying
+}
+
+// AddMethod adds method m unless it is already in the method list.
+func (t *Named) AddMethod(m *Func) {
+	t.load()
+	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
+		t.methods = append(t.methods, m)
+	}
+}
+
+func (t *Named) Underlying() Type { return t.load().underlying }
+func (t *Named) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// under returns the expanded underlying type of n0; possibly by following
+// forward chains of named types. If an underlying type is found, resolve
+// the chain by setting the underlying type for each defined type in the
+// chain before returning it. If no underlying type is found or a cycle
+// is detected, the result is Typ[Invalid]. If a cycle is detected and
+// n0.check != nil, the cycle is reported.
+func (n0 *Named) under() Type {
+	n0.expand()
+
+	u := n0.Underlying()
+
+	if u == Typ[Invalid] {
+		return u
+	}
+
+	// If the underlying type of a defined type is not a defined
+	// (incl. instance) type, then that is the desired underlying
+	// type.
+	switch u.(type) {
+	case nil:
+		return Typ[Invalid]
+	default:
+		// common case
+		return u
+	case *Named:
+		// handled below
+	}
+
+	if n0.check == nil {
+		panic("internal error: Named.check == nil but type is incomplete")
+	}
+
+	// Invariant: after this point n0 as well as any named types in its
+	// underlying chain should be set up when this function exits.
+	check := n0.check
+
+	// If we can't expand u at this point, it is invalid.
+	n := asNamed(u)
+	if n == nil {
+		n0.underlying = Typ[Invalid]
+		return n0.underlying
+	}
+
+	// Otherwise, follow the forward chain.
+	seen := map[*Named]int{n0: 0}
+	path := []Object{n0.obj}
+	for {
+		u = n.Underlying()
+		if u == nil {
+			u = Typ[Invalid]
+			break
+		}
+		var n1 *Named
+		switch u1 := u.(type) {
+		case *Named:
+			u1.expand()
+			n1 = u1
+		}
+		if n1 == nil {
+			break // end of chain
+		}
+
+		seen[n] = len(seen)
+		path = append(path, n.obj)
+		n = n1
+
+		if i, ok := seen[n]; ok {
+			// cycle
+			check.cycleError(path[i:])
+			u = Typ[Invalid]
+			break
+		}
+	}
+
+	for n := range seen {
+		// We should never have to update the underlying type of an imported type;
+		// those underlying types should have been resolved during the import.
+		// Also, doing so would lead to a race condition (was issue #31749).
+		// Do this check always, not just in debug mode (it's cheap).
+		if n.obj.pkg != check.pkg {
+			panic("internal error: imported type with unresolved underlying type")
+		}
+		n.underlying = u
+	}
+
+	return u
+}
+
+func (n *Named) setUnderlying(typ Type) {
+	if n != nil {
+		n.underlying = typ
+	}
+}
+
+// instance holds position information for use in lazy instantiation.
+//
+// TODO(rfindley): come up with a better name for this type, now that its usage
+// has changed.
+type instance struct {
+	pos     token.Pos   // position of type instantiation; for error reporting only
+	posList []token.Pos // position of each targ; for error reporting only
+}
+
+// expand ensures that the underlying type of n is instantiated.
+// The underlying type will be Typ[Invalid] if there was an error.
+// TODO(rfindley): expand would be a better name for this method, but conflicts
+// with the existing concept of lazy expansion. Need to reconcile this.
+func (n *Named) expand() {
+	if n.instance != nil {
+		// n must be loaded before instantiation, in order to have accurate
+		// tparams. This is done implicitly by the call to n.TParams, but making it
+		// explicit is harmless: load is idempotent.
+		n.load()
+		inst := n.check.instantiate(n.instance.pos, n.orig.underlying, n.TParams().list(), n.targs, n.instance.posList)
+		n.underlying = inst
+		n.fromRHS = inst
+		n.instance = nil
+	}
+}
+
+// expand expands uninstantiated named types and leaves all other types alone.
+// expand does not recurse.
+func expand(typ Type) Type {
+	if t, _ := typ.(*Named); t != nil {
+		t.expand()
+	}
+	return typ
+}
diff --git a/src/go/types/object.go b/src/go/types/object.go
index 50346ec..7266623 100644
--- a/src/go/types/object.go
+++ b/src/go/types/object.go
@@ -230,6 +230,14 @@
 	return &TypeName{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}}
 }
 
+// _NewTypeNameLazy returns a new defined type like NewTypeName, but it
+// lazily calls resolve to finish constructing the Named object.
+func _NewTypeNameLazy(pos token.Pos, pkg *Package, name string, resolve func(named *Named) (tparams []*TypeName, underlying Type, methods []*Func)) *TypeName {
+	obj := NewTypeName(pos, pkg, name, nil)
+	NewNamed(obj, nil, nil).resolve = resolve
+	return obj
+}
+
 // IsAlias reports whether obj is an alias name for a type.
 func (obj *TypeName) IsAlias() bool {
 	switch t := obj.typ.(type) {
@@ -421,6 +429,9 @@
 		if _, ok := typ.(*Basic); ok {
 			return
 		}
+		if named, _ := typ.(*Named); named != nil && named.TParams().Len() > 0 {
+			writeTParamList(buf, named.TParams().list(), qf, nil)
+		}
 		if tname.IsAlias() {
 			buf.WriteString(" =")
 		} else {
diff --git a/src/go/types/object_test.go b/src/go/types/object_test.go
index 2b6057b..0ff8fdd 100644
--- a/src/go/types/object_test.go
+++ b/src/go/types/object_test.go
@@ -22,7 +22,7 @@
 	check(Unsafe.Scope().Lookup("Pointer").(*TypeName), false)
 	for _, name := range Universe.Names() {
 		if obj, _ := Universe.Lookup(name).(*TypeName); obj != nil {
-			check(obj, name == "byte" || name == "rune")
+			check(obj, name == "any" || name == "byte" || name == "rune")
 		}
 	}
 
diff --git a/src/go/types/operand.go b/src/go/types/operand.go
index 6463728c..aea8bf5 100644
--- a/src/go/types/operand.go
+++ b/src/go/types/operand.go
@@ -159,16 +159,20 @@
 	if hasType {
 		if x.typ != Typ[Invalid] {
 			var intro string
-			switch {
-			case isGeneric(x.typ):
-				intro = " of generic type "
-			case asTypeParam(x.typ) != nil:
-				intro = " of type parameter type "
-			default:
+			var tpar *TypeParam
+			if isGeneric(x.typ) {
+				intro = " of parameterized type "
+			} else if tpar = asTypeParam(x.typ); tpar != nil {
+				intro = " of type parameter "
+			} else {
 				intro = " of type "
 			}
 			buf.WriteString(intro)
 			WriteType(&buf, x.typ, qf)
+			if tpar != nil {
+				buf.WriteString(" constrained by ")
+				WriteType(&buf, tpar.bound, qf) // do not compute interface type sets here
+			}
 		} else {
 			buf.WriteString(" with invalid type")
 		}
@@ -233,20 +237,35 @@
 
 	V := x.typ
 
+	const debugAssignableTo = false
+	if debugAssignableTo && check != nil {
+		check.dump("V = %s", V)
+		check.dump("T = %s", T)
+	}
+
 	// x's type is identical to T
-	if check.identical(V, T) {
+	if Identical(V, T) {
 		return true, 0
 	}
 
 	Vu := optype(V)
 	Tu := optype(T)
 
+	if debugAssignableTo && check != nil {
+		check.dump("Vu = %s", Vu)
+		check.dump("Tu = %s", Tu)
+	}
+
 	// x is an untyped value representable by a value of type T.
 	if isUntyped(Vu) {
-		if t, ok := Tu.(*_Sum); ok {
-			return t.is(func(t Type) bool {
+		if t, ok := Tu.(*Union); ok {
+			return t.is(func(t *term) bool {
 				// TODO(gri) this could probably be more efficient
-				ok, _ := x.assignableTo(check, t, reason)
+				if t.tilde {
+					// TODO(gri) We need to check assignability
+					//           for the underlying type of x.
+				}
+				ok, _ := x.assignableTo(check, t.typ, reason)
 				return ok
 			}), _IncompatibleAssign
 		}
@@ -257,7 +276,7 @@
 
 	// x's type V and T have identical underlying types
 	// and at least one of V or T is not a named type
-	if check.identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
+	if Identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
 		return true, 0
 	}
 
@@ -266,7 +285,7 @@
 		if m, wrongType := check.missingMethod(V, Ti, true); m != nil /* Implements(V, Ti) */ {
 			if reason != nil {
 				if wrongType != nil {
-					if check.identical(m.typ, wrongType.typ) {
+					if Identical(m.typ, wrongType.typ) {
 						*reason = fmt.Sprintf("missing method %s (%s has pointer receiver)", m.name, m.name)
 					} else {
 						*reason = fmt.Sprintf("wrong type for method %s (have %s, want %s)", m.Name(), wrongType.typ, m.typ)
@@ -285,7 +304,7 @@
 	// type, x's type V and T have identical element types,
 	// and at least one of V or T is not a named type
 	if Vc, ok := Vu.(*Chan); ok && Vc.dir == SendRecv {
-		if Tc, ok := Tu.(*Chan); ok && check.identical(Vc.elem, Tc.elem) {
+		if Tc, ok := Tu.(*Chan); ok && Identical(Vc.elem, Tc.elem) {
 			return !isNamed(V) || !isNamed(T), _InvalidChanAssign
 		}
 	}
diff --git a/src/go/types/pointer.go b/src/go/types/pointer.go
new file mode 100644
index 0000000..6352ee5
--- /dev/null
+++ b/src/go/types/pointer.go
@@ -0,0 +1,19 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Pointer represents a pointer type.
+type Pointer struct {
+	base Type // element type
+}
+
+// NewPointer returns a new pointer type for the given element (base) type.
+func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
+
+// Elem returns the element type for the given pointer p.
+func (p *Pointer) Elem() Type { return p.base }
+
+func (t *Pointer) Underlying() Type { return t }
+func (t *Pointer) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/predicates.go b/src/go/types/predicates.go
index 7bb0264..2392469 100644
--- a/src/go/types/predicates.go
+++ b/src/go/types/predicates.go
@@ -6,15 +6,11 @@
 
 package types
 
-import (
-	"go/token"
-)
-
 // isNamed reports whether typ has a name.
 // isNamed may be called with types that are not fully set up.
 func isNamed(typ Type) bool {
 	switch typ.(type) {
-	case *Basic, *Named, *_TypeParam, *instance:
+	case *Basic, *Named, *TypeParam:
 		return true
 	}
 	return false
@@ -25,15 +21,15 @@
 func isGeneric(typ Type) bool {
 	// A parameterized type is only instantiated if it doesn't have an instantiation already.
 	named, _ := typ.(*Named)
-	return named != nil && named.obj != nil && named.tparams != nil && named.targs == nil
+	return named != nil && named.obj != nil && named.targs == nil && named.TParams() != nil
 }
 
 func is(typ Type, what BasicInfo) bool {
-	switch t := optype(typ).(type) {
+	switch t := under(typ).(type) {
 	case *Basic:
 		return t.info&what != 0
-	case *_Sum:
-		return t.is(func(typ Type) bool { return is(typ, what) })
+	case *TypeParam:
+		return t.underIs(func(typ Type) bool { return is(typ, what) })
 	}
 	return false
 }
@@ -61,9 +57,6 @@
 func isTyped(typ Type) bool {
 	// isTyped is called with types that are not fully
 	// set up. Must not call asBasic()!
-	// A *Named or *instance type is always typed, so
-	// we only need to check if we have a true *Basic
-	// type.
 	t, _ := typ.(*Basic)
 	return t == nil || t.info&IsUntyped == 0
 }
@@ -100,19 +93,7 @@
 	}
 	seen[T] = true
 
-	// If T is a type parameter not constrained by any type
-	// list (i.e., it's underlying type is the top type),
-	// T is comparable if it has the == method. Otherwise,
-	// the underlying type "wins". For instance
-	//
-	//     interface{ comparable; type []byte }
-	//
-	// is not comparable because []byte is not comparable.
-	if t := asTypeParam(T); t != nil && optype(t) == theTop {
-		return t.Bound()._IsComparable()
-	}
-
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Basic:
 		// assume invalid types to be comparable
 		// to avoid follow-up errors
@@ -128,42 +109,25 @@
 		return true
 	case *Array:
 		return comparable(t.elem, seen)
-	case *_Sum:
-		pred := func(t Type) bool {
-			return comparable(t, seen)
-		}
-		return t.is(pred)
-	case *_TypeParam:
-		return t.Bound()._IsComparable()
+	case *TypeParam:
+		return t.iface().IsComparable()
 	}
 	return false
 }
 
 // hasNil reports whether a type includes the nil value.
 func hasNil(typ Type) bool {
-	switch t := optype(typ).(type) {
+	switch t := under(typ).(type) {
 	case *Basic:
 		return t.kind == UnsafePointer
 	case *Slice, *Pointer, *Signature, *Interface, *Map, *Chan:
 		return true
-	case *_Sum:
-		return t.is(hasNil)
+	case *TypeParam:
+		return t.underIs(hasNil)
 	}
 	return false
 }
 
-// identical reports whether x and y are identical types.
-// Receivers of Signature types are ignored.
-func (check *Checker) identical(x, y Type) bool {
-	return check.identical0(x, y, true, nil)
-}
-
-// identicalIgnoreTags reports whether x and y are identical types if tags are ignored.
-// Receivers of Signature types are ignored.
-func (check *Checker) identicalIgnoreTags(x, y Type) bool {
-	return check.identical0(x, y, false, nil)
-}
-
 // An ifacePair is a node in a stack of interface type pairs compared for identity.
 type ifacePair struct {
 	x, y *Interface
@@ -175,10 +139,10 @@
 }
 
 // For changes to this code the corresponding changes should be made to unifier.nify.
-func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
+func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
 	// types must be expanded for comparison
-	x = expandf(x)
-	y = expandf(y)
+	x = expand(x)
+	y = expand(y)
 
 	if x == y {
 		return true
@@ -199,13 +163,13 @@
 		if y, ok := y.(*Array); ok {
 			// If one or both array lengths are unknown (< 0) due to some error,
 			// assume they are the same to avoid spurious follow-on errors.
-			return (x.len < 0 || y.len < 0 || x.len == y.len) && check.identical0(x.elem, y.elem, cmpTags, p)
+			return (x.len < 0 || y.len < 0 || x.len == y.len) && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Slice:
 		// Two slice types are identical if they have identical element types.
 		if y, ok := y.(*Slice); ok {
-			return check.identical0(x.elem, y.elem, cmpTags, p)
+			return identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Struct:
@@ -220,7 +184,7 @@
 					if f.embedded != g.embedded ||
 						cmpTags && x.Tag(i) != y.Tag(i) ||
 						!f.sameId(g.pkg, g.name) ||
-						!check.identical0(f.typ, g.typ, cmpTags, p) {
+						!identical(f.typ, g.typ, cmpTags, p) {
 						return false
 					}
 				}
@@ -231,7 +195,7 @@
 	case *Pointer:
 		// Two pointer types are identical if they have identical base types.
 		if y, ok := y.(*Pointer); ok {
-			return check.identical0(x.base, y.base, cmpTags, p)
+			return identical(x.base, y.base, cmpTags, p)
 		}
 
 	case *Tuple:
@@ -242,7 +206,7 @@
 				if x != nil {
 					for i, v := range x.vars {
 						w := y.vars[i]
-						if !check.identical0(v.typ, w.typ, cmpTags, p) {
+						if !identical(v.typ, w.typ, cmpTags, p) {
 							return false
 						}
 					}
@@ -260,49 +224,37 @@
 		// parameter names.
 		if y, ok := y.(*Signature); ok {
 			return x.variadic == y.variadic &&
-				check.identicalTParams(x.tparams, y.tparams, cmpTags, p) &&
-				check.identical0(x.params, y.params, cmpTags, p) &&
-				check.identical0(x.results, y.results, cmpTags, p)
+				identicalTParams(x.TParams().list(), y.TParams().list(), cmpTags, p) &&
+				identical(x.params, y.params, cmpTags, p) &&
+				identical(x.results, y.results, cmpTags, p)
 		}
 
-	case *_Sum:
-		// Two sum types are identical if they contain the same types.
-		// (Sum types always consist of at least two types. Also, the
-		// the set (list) of types in a sum type consists of unique
-		// types - each type appears exactly once. Thus, two sum types
+	case *Union:
+		// Two union types are identical if they contain the same terms.
+		// The set (list) of types in a union type consists of unique
+		// types - each type appears exactly once. Thus, two union types
 		// must contain the same number of types to have chance of
 		// being equal.
-		if y, ok := y.(*_Sum); ok && len(x.types) == len(y.types) {
-			// Every type in x.types must be in y.types.
-			// Quadratic algorithm, but probably good enough for now.
-			// TODO(gri) we need a fast quick type ID/hash for all types.
-		L:
-			for _, x := range x.types {
-				for _, y := range y.types {
-					if Identical(x, y) {
-						continue L // x is in y.types
-					}
-				}
-				return false // x is not in y.types
-			}
-			return true
+		if y, ok := y.(*Union); ok {
+			return identicalTerms(x.terms, y.terms)
 		}
 
 	case *Interface:
+		// Two interface types are identical if they describe the same type sets.
+		// With the existing implementation restriction, this simplifies to:
+		//
 		// Two interface types are identical if they have the same set of methods with
-		// the same names and identical function types. Lower-case method names from
-		// different packages are always different. The order of the methods is irrelevant.
+		// the same names and identical function types, and if any type restrictions
+		// are the same. Lower-case method names from different packages are always
+		// different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			// If identical0 is called (indirectly) via an external API entry point
-			// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
-			// that case, interfaces are expected to be complete and lazy completion
-			// here is not needed.
-			if check != nil {
-				check.completeInterface(token.NoPos, x)
-				check.completeInterface(token.NoPos, y)
+			xset := x.typeSet()
+			yset := y.typeSet()
+			if !Identical(xset.types, yset.types) {
+				return false
 			}
-			a := x.allMethods
-			b := y.allMethods
+			a := xset.methods
+			b := yset.methods
 			if len(a) == len(b) {
 				// Interface types are the only types where cycles can occur
 				// that are not "terminated" via named types; and such cycles
@@ -339,7 +291,7 @@
 				}
 				for i, f := range a {
 					g := b[i]
-					if f.Id() != g.Id() || !check.identical0(f.typ, g.typ, cmpTags, q) {
+					if f.Id() != g.Id() || !identical(f.typ, g.typ, cmpTags, q) {
 						return false
 					}
 				}
@@ -350,14 +302,14 @@
 	case *Map:
 		// Two map types are identical if they have identical key and value types.
 		if y, ok := y.(*Map); ok {
-			return check.identical0(x.key, y.key, cmpTags, p) && check.identical0(x.elem, y.elem, cmpTags, p)
+			return identical(x.key, y.key, cmpTags, p) && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Chan:
 		// Two channel types are identical if they have identical value types
 		// and the same direction.
 		if y, ok := y.(*Chan); ok {
-			return x.dir == y.dir && check.identical0(x.elem, y.elem, cmpTags, p)
+			return x.dir == y.dir && identical(x.elem, y.elem, cmpTags, p)
 		}
 
 	case *Named:
@@ -370,16 +322,12 @@
 			return x.obj == y.obj
 		}
 
-	case *_TypeParam:
+	case *TypeParam:
 		// nothing to do (x and y being equal is caught in the very beginning of this function)
 
-	// case *instance:
-	//	unreachable since types are expanded
-
-	case *bottom, *top:
-		// Either both types are theBottom, or both are theTop in which
-		// case the initial x == y check will have caught them. Otherwise
-		// they are not identical.
+	case *top:
+		// Either both types are theTop in which case the initial x == y check
+		// will have caught them. Otherwise they are not identical.
 
 	case nil:
 		// avoid a crash in case of nil type
@@ -391,13 +339,13 @@
 	return false
 }
 
-func (check *Checker) identicalTParams(x, y []*TypeName, cmpTags bool, p *ifacePair) bool {
+func identicalTParams(x, y []*TypeName, cmpTags bool, p *ifacePair) bool {
 	if len(x) != len(y) {
 		return false
 	}
 	for i, x := range x {
 		y := y[i]
-		if !check.identical0(x.typ.(*_TypeParam).bound, y.typ.(*_TypeParam).bound, cmpTags, p) {
+		if !identical(x.typ.(*TypeParam).bound, y.typ.(*TypeParam).bound, cmpTags, p) {
 			return false
 		}
 	}
diff --git a/src/go/types/resolver.go b/src/go/types/resolver.go
index 114647a..5e58c3d 100644
--- a/src/go/types/resolver.go
+++ b/src/go/types/resolver.go
@@ -276,7 +276,7 @@
 				}
 
 				if name == "init" {
-					check.errorf(d.spec.Name, _InvalidInitDecl, "cannot import package as init - init must be a func")
+					check.errorf(d.spec, _InvalidInitDecl, "cannot import package as init - init must be a func")
 					return
 				}
 
@@ -309,20 +309,24 @@
 						check.dotImportMap = make(map[dotImportKey]*PkgName)
 					}
 					// merge imported scope with file scope
-					for _, obj := range imp.scope.elems {
+					for name, obj := range imp.scope.elems {
+						// Note: Avoid eager resolve(name, obj) here, so we only
+						// resolve dot-imported objects as needed.
+
 						// A package scope may contain non-exported objects,
 						// do not import them!
-						if obj.Exported() {
+						if token.IsExported(name) {
 							// declare dot-imported object
 							// (Do not use check.declare because it modifies the object
 							// via Object.setScopePos, which leads to a race condition;
 							// the object may be imported into more than one file scope
 							// concurrently. See issue #32154.)
-							if alt := fileScope.Insert(obj); alt != nil {
-								check.errorf(d.spec.Name, _DuplicateDecl, "%s redeclared in this block", obj.Name())
+							if alt := fileScope.Lookup(name); alt != nil {
+								check.errorf(d.spec.Name, _DuplicateDecl, "%s redeclared in this block", alt.Name())
 								check.reportAltDecl(alt)
 							} else {
-								check.dotImportMap[dotImportKey{fileScope, obj}] = pkgName
+								fileScope.insert(name, obj)
+								check.dotImportMap[dotImportKey{fileScope, name}] = pkgName
 							}
 						}
 					}
@@ -443,8 +447,9 @@
 
 	// verify that objects in package and file scopes have different names
 	for _, scope := range fileScopes {
-		for _, obj := range scope.elems {
-			if alt := pkg.scope.Lookup(obj.Name()); alt != nil {
+		for name, obj := range scope.elems {
+			if alt := pkg.scope.Lookup(name); alt != nil {
+				obj = resolve(name, obj)
 				if pkg, ok := obj.(*PkgName); ok {
 					check.errorf(alt, _DuplicateDecl, "%s already declared through import of %s", alt.Name(), pkg.Imported())
 					check.reportAltDecl(pkg)
@@ -499,10 +504,12 @@
 	}
 
 	// unpack type parameters, if any
-	if ptyp, _ := rtyp.(*ast.IndexExpr); ptyp != nil {
-		rtyp = ptyp.X
+	switch rtyp.(type) {
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(rtyp)
+		rtyp = ix.X
 		if unpackParams {
-			for _, arg := range typeparams.UnpackExpr(ptyp.Index) {
+			for _, arg := range ix.Indices {
 				var par *ast.Ident
 				switch arg := arg.(type) {
 				case *ast.Ident:
@@ -510,7 +517,7 @@
 				case *ast.BadExpr:
 					// ignore - error already reported by parser
 				case nil:
-					check.invalidAST(ptyp, "parameterized receiver contains nil parameters")
+					check.invalidAST(ix.Orig, "parameterized receiver contains nil parameters")
 				default:
 					check.errorf(arg, _Todo, "receiver type parameter %s must be an identifier", arg)
 				}
diff --git a/src/go/types/sanitize.go b/src/go/types/sanitize.go
deleted file mode 100644
index 727ec17..0000000
--- a/src/go/types/sanitize.go
+++ /dev/null
@@ -1,206 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package types
-
-// sanitizeInfo walks the types contained in info to ensure that all instances
-// are expanded.
-//
-// This includes some objects that may be shared across concurrent
-// type-checking passes (such as those in the universe scope), so we are
-// careful here not to write types that are already sanitized. This avoids a
-// data race as any shared types should already be sanitized.
-func sanitizeInfo(info *Info) {
-	var s sanitizer = make(map[Type]Type)
-
-	// Note: Some map entries are not references.
-	// If modified, they must be assigned back.
-
-	for e, tv := range info.Types {
-		if typ := s.typ(tv.Type); typ != tv.Type {
-			tv.Type = typ
-			info.Types[e] = tv
-		}
-	}
-
-	inferred := getInferred(info)
-	for e, inf := range inferred {
-		changed := false
-		for i, targ := range inf.Targs {
-			if typ := s.typ(targ); typ != targ {
-				inf.Targs[i] = typ
-				changed = true
-			}
-		}
-		if typ := s.typ(inf.Sig); typ != inf.Sig {
-			inf.Sig = typ.(*Signature)
-			changed = true
-		}
-		if changed {
-			inferred[e] = inf
-		}
-	}
-
-	for _, obj := range info.Defs {
-		if obj != nil {
-			if typ := s.typ(obj.Type()); typ != obj.Type() {
-				obj.setType(typ)
-			}
-		}
-	}
-
-	for _, obj := range info.Uses {
-		if obj != nil {
-			if typ := s.typ(obj.Type()); typ != obj.Type() {
-				obj.setType(typ)
-			}
-		}
-	}
-
-	// TODO(gri) sanitize as needed
-	// - info.Implicits
-	// - info.Selections
-	// - info.Scopes
-	// - info.InitOrder
-}
-
-type sanitizer map[Type]Type
-
-func (s sanitizer) typ(typ Type) Type {
-	if typ == nil {
-		return nil
-	}
-
-	if t, found := s[typ]; found {
-		return t
-	}
-	s[typ] = typ
-
-	switch t := typ.(type) {
-	case *Basic, *bottom, *top:
-		// nothing to do
-
-	case *Array:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Slice:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Struct:
-		s.varList(t.fields)
-
-	case *Pointer:
-		if base := s.typ(t.base); base != t.base {
-			t.base = base
-		}
-
-	case *Tuple:
-		s.tuple(t)
-
-	case *Signature:
-		s.var_(t.recv)
-		s.tuple(t.params)
-		s.tuple(t.results)
-
-	case *_Sum:
-		s.typeList(t.types)
-
-	case *Interface:
-		s.funcList(t.methods)
-		if types := s.typ(t.types); types != t.types {
-			t.types = types
-		}
-		s.typeList(t.embeddeds)
-		s.funcList(t.allMethods)
-		if allTypes := s.typ(t.allTypes); allTypes != t.allTypes {
-			t.allTypes = allTypes
-		}
-
-	case *Map:
-		if key := s.typ(t.key); key != t.key {
-			t.key = key
-		}
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Chan:
-		if elem := s.typ(t.elem); elem != t.elem {
-			t.elem = elem
-		}
-
-	case *Named:
-		if debug && t.check != nil {
-			panic("internal error: Named.check != nil")
-		}
-		if orig := s.typ(t.orig); orig != t.orig {
-			t.orig = orig
-		}
-		if under := s.typ(t.underlying); under != t.underlying {
-			t.underlying = under
-		}
-		s.typeList(t.targs)
-		s.funcList(t.methods)
-
-	case *_TypeParam:
-		if bound := s.typ(t.bound); bound != t.bound {
-			t.bound = bound
-		}
-
-	case *instance:
-		typ = t.expand()
-		s[t] = typ
-
-	default:
-		panic("unimplemented")
-	}
-
-	return typ
-}
-
-func (s sanitizer) var_(v *Var) {
-	if v != nil {
-		if typ := s.typ(v.typ); typ != v.typ {
-			v.typ = typ
-		}
-	}
-}
-
-func (s sanitizer) varList(list []*Var) {
-	for _, v := range list {
-		s.var_(v)
-	}
-}
-
-func (s sanitizer) tuple(t *Tuple) {
-	if t != nil {
-		s.varList(t.vars)
-	}
-}
-
-func (s sanitizer) func_(f *Func) {
-	if f != nil {
-		if typ := s.typ(f.typ); typ != f.typ {
-			f.typ = typ
-		}
-	}
-}
-
-func (s sanitizer) funcList(list []*Func) {
-	for _, f := range list {
-		s.func_(f)
-	}
-}
-
-func (s sanitizer) typeList(list []Type) {
-	for i, t := range list {
-		if typ := s.typ(t); typ != t {
-			list[i] = typ
-		}
-	}
-}
diff --git a/src/go/types/scope.go b/src/go/types/scope.go
index 26c28d1..010727e 100644
--- a/src/go/types/scope.go
+++ b/src/go/types/scope.go
@@ -13,6 +13,7 @@
 	"io"
 	"sort"
 	"strings"
+	"sync"
 )
 
 // A Scope maintains a set of objects and links to its containing
@@ -22,6 +23,7 @@
 type Scope struct {
 	parent   *Scope
 	children []*Scope
+	number   int               // parent.children[number-1] is this scope; 0 if there is no parent
 	elems    map[string]Object // lazily allocated
 	pos, end token.Pos         // scope extent; may be invalid
 	comment  string            // for debugging only
@@ -31,10 +33,11 @@
 // NewScope returns a new, empty scope contained in the given parent
 // scope, if any. The comment is for debugging only.
 func NewScope(parent *Scope, pos, end token.Pos, comment string) *Scope {
-	s := &Scope{parent, nil, nil, pos, end, comment, false}
+	s := &Scope{parent, nil, 0, nil, pos, end, comment, false}
 	// don't add children to Universe scope!
 	if parent != nil && parent != Universe {
 		parent.children = append(parent.children, s)
+		s.number = len(parent.children)
 	}
 	return s
 }
@@ -66,7 +69,7 @@
 // Lookup returns the object in scope s with the given name if such an
 // object exists; otherwise the result is nil.
 func (s *Scope) Lookup(name string) Object {
-	return s.elems[name]
+	return resolve(name, s.elems[name])
 }
 
 // LookupParent follows the parent chain of scopes starting with s until
@@ -81,7 +84,7 @@
 // whose scope is the scope of the package that exported them.
 func (s *Scope) LookupParent(name string, pos token.Pos) (*Scope, Object) {
 	for ; s != nil; s = s.parent {
-		if obj := s.elems[name]; obj != nil && (!pos.IsValid() || obj.scopePos() <= pos) {
+		if obj := s.Lookup(name); obj != nil && (!pos.IsValid() || obj.scopePos() <= pos) {
 			return s, obj
 		}
 	}
@@ -95,19 +98,38 @@
 // if not already set, and returns nil.
 func (s *Scope) Insert(obj Object) Object {
 	name := obj.Name()
-	if alt := s.elems[name]; alt != nil {
+	if alt := s.Lookup(name); alt != nil {
 		return alt
 	}
-	if s.elems == nil {
-		s.elems = make(map[string]Object)
-	}
-	s.elems[name] = obj
+	s.insert(name, obj)
 	if obj.Parent() == nil {
 		obj.setParent(s)
 	}
 	return nil
 }
 
+// _InsertLazy is like Insert, but allows deferring construction of the
+// inserted object until it's accessed with Lookup. The Object
+// returned by resolve must have the same name as given to _InsertLazy.
+// If s already contains an alternative object with the same name,
+// _InsertLazy leaves s unchanged and returns false. Otherwise it
+// records the binding and returns true. The object's parent scope
+// will be set to s after resolve is called.
+func (s *Scope) _InsertLazy(name string, resolve func() Object) bool {
+	if s.elems[name] != nil {
+		return false
+	}
+	s.insert(name, &lazyObject{parent: s, resolve: resolve})
+	return true
+}
+
+func (s *Scope) insert(name string, obj Object) {
+	if s.elems == nil {
+		s.elems = make(map[string]Object)
+	}
+	s.elems[name] = obj
+}
+
 // squash merges s with its parent scope p by adding all
 // objects of s to p, adding all children of s to the
 // children of p, and removing s from p's children.
@@ -117,7 +139,8 @@
 func (s *Scope) squash(err func(obj, alt Object)) {
 	p := s.parent
 	assert(p != nil)
-	for _, obj := range s.elems {
+	for name, obj := range s.elems {
+		obj = resolve(name, obj)
 		obj.setParent(nil)
 		if alt := p.Insert(obj); alt != nil {
 			err(obj, alt)
@@ -196,7 +219,7 @@
 
 	indn1 := indn + ind
 	for _, name := range s.Names() {
-		fmt.Fprintf(w, "%s%s\n", indn1, s.elems[name])
+		fmt.Fprintf(w, "%s%s\n", indn1, s.Lookup(name))
 	}
 
 	if recurse {
@@ -214,3 +237,57 @@
 	s.WriteTo(&buf, 0, false)
 	return buf.String()
 }
+
+// A lazyObject represents an imported Object that has not been fully
+// resolved yet by its importer.
+type lazyObject struct {
+	parent  *Scope
+	resolve func() Object
+	obj     Object
+	once    sync.Once
+}
+
+// resolve returns the Object represented by obj, resolving lazy
+// objects as appropriate.
+func resolve(name string, obj Object) Object {
+	if lazy, ok := obj.(*lazyObject); ok {
+		lazy.once.Do(func() {
+			obj := lazy.resolve()
+
+			if _, ok := obj.(*lazyObject); ok {
+				panic("recursive lazy object")
+			}
+			if obj.Name() != name {
+				panic("lazy object has unexpected name")
+			}
+
+			if obj.Parent() == nil {
+				obj.setParent(lazy.parent)
+			}
+			lazy.obj = obj
+		})
+
+		obj = lazy.obj
+	}
+	return obj
+}
+
+// stub implementations so *lazyObject implements Object and we can
+// store them directly into Scope.elems.
+func (*lazyObject) Parent() *Scope                        { panic("unreachable") }
+func (*lazyObject) Pos() token.Pos                        { panic("unreachable") }
+func (*lazyObject) Pkg() *Package                         { panic("unreachable") }
+func (*lazyObject) Name() string                          { panic("unreachable") }
+func (*lazyObject) Type() Type                            { panic("unreachable") }
+func (*lazyObject) Exported() bool                        { panic("unreachable") }
+func (*lazyObject) Id() string                            { panic("unreachable") }
+func (*lazyObject) String() string                        { panic("unreachable") }
+func (*lazyObject) order() uint32                         { panic("unreachable") }
+func (*lazyObject) color() color                          { panic("unreachable") }
+func (*lazyObject) setType(Type)                          { panic("unreachable") }
+func (*lazyObject) setOrder(uint32)                       { panic("unreachable") }
+func (*lazyObject) setColor(color color)                  { panic("unreachable") }
+func (*lazyObject) setParent(*Scope)                      { panic("unreachable") }
+func (*lazyObject) sameId(pkg *Package, name string) bool { panic("unreachable") }
+func (*lazyObject) scopePos() token.Pos                   { panic("unreachable") }
+func (*lazyObject) setScopePos(pos token.Pos)             { panic("unreachable") }
diff --git a/src/go/types/signature.go b/src/go/types/signature.go
new file mode 100644
index 0000000..5a69bb1
--- /dev/null
+++ b/src/go/types/signature.go
@@ -0,0 +1,352 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"fmt"
+	"go/ast"
+	"go/internal/typeparams"
+	"go/token"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Signature represents a (non-builtin) function or method type.
+// The receiver is ignored when comparing signatures for identity.
+type Signature struct {
+	// We need to keep the scope in Signature (rather than passing it around
+	// and store it in the Func Object) because when type-checking a function
+	// literal we call the general type checker which returns a general Type.
+	// We then unpack the *Signature and use the scope for the literal body.
+	rparams  *TypeParams // receiver type parameters from left to right, or nil
+	tparams  *TypeParams // type parameters from left to right, or nil
+	scope    *Scope      // function scope, present for package-local signatures
+	recv     *Var        // nil if not a method
+	params   *Tuple      // (incoming) parameters from left to right; or nil
+	results  *Tuple      // (outgoing) results from left to right; or nil
+	variadic bool        // true if the last parameter's type is of the form ...T (or string, for append built-in only)
+}
+
+// NewSignature returns a new function type for the given receiver, parameters,
+// and results, either of which may be nil. If variadic is set, the function
+// is variadic, it must have at least one parameter, and the last parameter
+// must be of unnamed slice type.
+func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
+	if variadic {
+		n := params.Len()
+		if n == 0 {
+			panic("types.NewSignature: variadic function must have at least one parameter")
+		}
+		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
+			panic("types.NewSignature: variadic parameter must be of unnamed slice type")
+		}
+	}
+	return &Signature{recv: recv, params: params, results: results, variadic: variadic}
+}
+
+// Recv returns the receiver of signature s (if a method), or nil if a
+// function. It is ignored when comparing signatures for identity.
+//
+// For an abstract method, Recv returns the enclosing interface either
+// as a *Named or an *Interface. Due to embedding, an interface may
+// contain methods whose receiver type is a different interface.
+func (s *Signature) Recv() *Var { return s.recv }
+
+// TParams returns the type parameters of signature s, or nil.
+func (s *Signature) TParams() *TypeParams { return s.tparams }
+
+// SetTParams sets the type parameters of signature s.
+func (s *Signature) SetTParams(tparams []*TypeName) { s.tparams = bindTParams(tparams) }
+
+// RParams returns the receiver type parameters of signature s, or nil.
+func (s *Signature) RParams() *TypeParams { return s.rparams }
+
+// SetRParams sets the receiver type params of signature s.
+func (s *Signature) SetRParams(rparams []*TypeName) { s.rparams = bindTParams(rparams) }
+
+// Params returns the parameters of signature s, or nil.
+func (s *Signature) Params() *Tuple { return s.params }
+
+// Results returns the results of signature s, or nil.
+func (s *Signature) Results() *Tuple { return s.results }
+
+// Variadic reports whether the signature s is variadic.
+func (s *Signature) Variadic() bool { return s.variadic }
+
+func (t *Signature) Underlying() Type { return t }
+func (t *Signature) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// funcType type-checks a function or method type.
+func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast.FuncType) {
+	check.openScope(ftyp, "function")
+	check.scope.isFunc = true
+	check.recordScope(ftyp, check.scope)
+	sig.scope = check.scope
+	defer check.closeScope()
+
+	var recvTyp ast.Expr // rewritten receiver type; valid if != nil
+	if recvPar != nil && len(recvPar.List) > 0 {
+		// collect generic receiver type parameters, if any
+		// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
+		// - the receiver specification acts as local declaration for its type parameters, which may be blank
+		_, rname, rparams := check.unpackRecv(recvPar.List[0].Type, true)
+		if len(rparams) > 0 {
+			// Blank identifiers don't get declared and regular type-checking of the instantiated
+			// parameterized receiver type expression fails in Checker.collectParams of receiver.
+			// Identify blank type parameters and substitute each with a unique new identifier named
+			// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
+			// name.
+			var smap map[*ast.Ident]*ast.Ident // substitution map from "_" to "n_" identifiers
+			for i, p := range rparams {
+				if p.Name == "_" {
+					new := *p
+					new.Name = fmt.Sprintf("%d_", i)
+					rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
+					if smap == nil {
+						smap = make(map[*ast.Ident]*ast.Ident)
+					}
+					smap[p] = &new
+				}
+			}
+			if smap != nil {
+				// blank identifiers were found => use rewritten receiver type
+				recvTyp = isubst(recvPar.List[0].Type, smap)
+			}
+			sig.rparams = bindTParams(check.declareTypeParams(nil, rparams))
+			// determine receiver type to get its type parameters
+			// and the respective type parameter bounds
+			var recvTParams []*TypeName
+			if rname != nil {
+				// recv should be a Named type (otherwise an error is reported elsewhere)
+				// Also: Don't report an error via genericType since it will be reported
+				//       again when we type-check the signature.
+				// TODO(gri) maybe the receiver should be marked as invalid instead?
+				if recv := asNamed(check.genericType(rname, false)); recv != nil {
+					recvTParams = recv.TParams().list()
+				}
+			}
+			// provide type parameter bounds
+			// - only do this if we have the right number (otherwise an error is reported elsewhere)
+			if sig.RParams().Len() == len(recvTParams) {
+				// We have a list of *TypeNames but we need a list of Types.
+				list := make([]Type, sig.RParams().Len())
+				for i, t := range sig.RParams().list() {
+					list[i] = t.typ
+				}
+				smap := makeSubstMap(recvTParams, list)
+				for i, tname := range sig.RParams().list() {
+					bound := recvTParams[i].typ.(*TypeParam).bound
+					// bound is (possibly) parameterized in the context of the
+					// receiver type declaration. Substitute parameters for the
+					// current context.
+					// TODO(gri) should we assume now that bounds always exist?
+					//           (no bound == empty interface)
+					if bound != nil {
+						bound = check.subst(tname.pos, bound, smap)
+						tname.typ.(*TypeParam).bound = bound
+					}
+				}
+			}
+		}
+	}
+
+	if tparams := typeparams.Get(ftyp); tparams != nil {
+		sig.tparams = check.collectTypeParams(tparams)
+		// Always type-check method type parameters but complain that they are not allowed.
+		// (A separate check is needed when type-checking interface method signatures because
+		// they don't have a receiver specification.)
+		if recvPar != nil {
+			check.errorf(tparams, _Todo, "methods cannot have type parameters")
+		}
+	}
+
+	// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
+	// declarations and then squash that scope into the parent scope (and report any redeclarations at
+	// that time).
+	scope := NewScope(check.scope, token.NoPos, token.NoPos, "function body (temp. scope)")
+	recvList, _ := check.collectParams(scope, recvPar, recvTyp, false) // use rewritten receiver type, if any
+	params, variadic := check.collectParams(scope, ftyp.Params, nil, true)
+	results, _ := check.collectParams(scope, ftyp.Results, nil, false)
+	scope.squash(func(obj, alt Object) {
+		check.errorf(obj, _DuplicateDecl, "%s redeclared in this block", obj.Name())
+		check.reportAltDecl(alt)
+	})
+
+	if recvPar != nil {
+		// recv parameter list present (may be empty)
+		// spec: "The receiver is specified via an extra parameter section preceding the
+		// method name. That parameter section must declare a single parameter, the receiver."
+		var recv *Var
+		switch len(recvList) {
+		case 0:
+			// error reported by resolver
+			recv = NewParam(0, nil, "", Typ[Invalid]) // ignore recv below
+		default:
+			// more than one receiver
+			check.error(recvList[len(recvList)-1], _BadRecv, "method must have exactly one receiver")
+			fallthrough // continue with first receiver
+		case 1:
+			recv = recvList[0]
+		}
+
+		// TODO(gri) We should delay rtyp expansion to when we actually need the
+		//           receiver; thus all checks here should be delayed to later.
+		rtyp, _ := deref(recv.typ)
+		rtyp = expand(rtyp)
+
+		// spec: "The receiver type must be of the form T or *T where T is a type name."
+		// (ignore invalid types - error was reported before)
+		if rtyp != Typ[Invalid] {
+			var err string
+			switch T := rtyp.(type) {
+			case *Named:
+				// spec: "The type denoted by T is called the receiver base type; it must not
+				// be a pointer or interface type and it must be declared in the same package
+				// as the method."
+				if T.obj.pkg != check.pkg {
+					err = "type not defined in this package"
+				} else {
+					// The underlying type of a receiver base type can be a type parameter;
+					// e.g. for methods with a generic receiver T[P] with type T[P any] P.
+					underIs(T, func(u Type) bool {
+						switch u := u.(type) {
+						case *Basic:
+							// unsafe.Pointer is treated like a regular pointer
+							if u.kind == UnsafePointer {
+								err = "unsafe.Pointer"
+								return false
+							}
+						case *Pointer, *Interface:
+							err = "pointer or interface type"
+							return false
+						}
+						return true
+					})
+				}
+			case *Basic:
+				err = "basic or unnamed type"
+			default:
+				check.errorf(recv, _InvalidRecv, "invalid receiver type %s", recv.typ)
+			}
+			if err != "" {
+				check.errorf(recv, _InvalidRecv, "invalid receiver type %s (%s)", recv.typ, err)
+				// ok to continue
+			}
+		}
+		sig.recv = recv
+	}
+
+	sig.params = NewTuple(params...)
+	sig.results = NewTuple(results...)
+	sig.variadic = variadic
+}
+
+// collectParams declares the parameters of list in scope and returns the corresponding
+// variable list. If type0 != nil, it is used instead of the first type in list.
+func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, type0 ast.Expr, variadicOk bool) (params []*Var, variadic bool) {
+	if list == nil {
+		return
+	}
+
+	var named, anonymous bool
+	for i, field := range list.List {
+		ftype := field.Type
+		if i == 0 && type0 != nil {
+			ftype = type0
+		}
+		if t, _ := ftype.(*ast.Ellipsis); t != nil {
+			ftype = t.Elt
+			if variadicOk && i == len(list.List)-1 && len(field.Names) <= 1 {
+				variadic = true
+			} else {
+				check.softErrorf(t, _MisplacedDotDotDot, "can only use ... with final parameter in list")
+				// ignore ... and continue
+			}
+		}
+		typ := check.varType(ftype)
+		// The parser ensures that f.Tag is nil and we don't
+		// care if a constructed AST contains a non-nil tag.
+		if len(field.Names) > 0 {
+			// named parameter
+			for _, name := range field.Names {
+				if name.Name == "" {
+					check.invalidAST(name, "anonymous parameter")
+					// ok to continue
+				}
+				par := NewParam(name.Pos(), check.pkg, name.Name, typ)
+				check.declare(scope, name, par, scope.pos)
+				params = append(params, par)
+			}
+			named = true
+		} else {
+			// anonymous parameter
+			par := NewParam(ftype.Pos(), check.pkg, "", typ)
+			check.recordImplicit(field, par)
+			params = append(params, par)
+			anonymous = true
+		}
+	}
+
+	if named && anonymous {
+		check.invalidAST(list, "list contains both named and anonymous parameters")
+		// ok to continue
+	}
+
+	// For a variadic function, change the last parameter's type from T to []T.
+	// Since we type-checked T rather than ...T, we also need to retro-actively
+	// record the type for ...T.
+	if variadic {
+		last := params[len(params)-1]
+		last.typ = &Slice{elem: last.typ}
+		check.recordTypeAndValue(list.List[len(list.List)-1].Type, typexpr, last.typ, nil)
+	}
+
+	return
+}
+
+// isubst returns an x with identifiers substituted per the substitution map smap.
+// isubst only handles the case of (valid) method receiver type expressions correctly.
+func isubst(x ast.Expr, smap map[*ast.Ident]*ast.Ident) ast.Expr {
+	switch n := x.(type) {
+	case *ast.Ident:
+		if alt := smap[n]; alt != nil {
+			return alt
+		}
+	case *ast.StarExpr:
+		X := isubst(n.X, smap)
+		if X != n.X {
+			new := *n
+			new.X = X
+			return &new
+		}
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(x)
+		var newIndexes []ast.Expr
+		for i, index := range ix.Indices {
+			new := isubst(index, smap)
+			if new != index {
+				if newIndexes == nil {
+					newIndexes = make([]ast.Expr, len(ix.Indices))
+					copy(newIndexes, ix.Indices)
+				}
+				newIndexes[i] = new
+			}
+		}
+		if newIndexes != nil {
+			return typeparams.PackIndexExpr(ix.X, ix.Lbrack, newIndexes, ix.Rbrack)
+		}
+	case *ast.ParenExpr:
+		return isubst(n.X, smap) // no need to keep parentheses
+	default:
+		// Other receiver type expressions are invalid.
+		// It's fine to ignore those here as they will
+		// be checked elsewhere.
+	}
+	return x
+}
diff --git a/src/go/types/sizeof_test.go b/src/go/types/sizeof_test.go
index 5a9d07c..67a9b39 100644
--- a/src/go/types/sizeof_test.go
+++ b/src/go/types/sizeof_test.go
@@ -25,15 +25,14 @@
 		{Struct{}, 24, 48},
 		{Pointer{}, 8, 16},
 		{Tuple{}, 12, 24},
-		{Signature{}, 44, 88},
-		{_Sum{}, 12, 24},
-		{Interface{}, 60, 120},
+		{Signature{}, 28, 56},
+		{Union{}, 12, 24},
+		{Interface{}, 40, 80},
 		{Map{}, 16, 32},
 		{Chan{}, 12, 24},
-		{Named{}, 64, 128},
-		{_TypeParam{}, 28, 48},
-		{instance{}, 44, 88},
-		{bottom{}, 0, 0},
+		{Named{}, 80, 152},
+		{TypeParam{}, 28, 48},
+		{term{}, 12, 24},
 		{top{}, 0, 0},
 
 		// Objects
@@ -47,8 +46,9 @@
 		{Nil{}, 40, 72},
 
 		// Misc
-		{Scope{}, 40, 80},
+		{Scope{}, 44, 88},
 		{Package{}, 40, 80},
+		{_TypeSet{}, 24, 48},
 	}
 	for _, test := range tests {
 		got := reflect.TypeOf(test.val).Size()
diff --git a/src/go/types/sizes.go b/src/go/types/sizes.go
index 67052bb..4c85bfe 100644
--- a/src/go/types/sizes.go
+++ b/src/go/types/sizes.go
@@ -48,7 +48,7 @@
 func (s *StdSizes) Alignof(T Type) int64 {
 	// For arrays and structs, alignment is defined in terms
 	// of alignment of the elements and fields, respectively.
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Array:
 		// spec: "For a variable x of array type: unsafe.Alignof(x)
 		// is the same as unsafe.Alignof(x[0]), but at least 1."
@@ -73,6 +73,8 @@
 		if t.Info()&IsString != 0 {
 			return s.WordSize
 		}
+	case *TypeParam, *Union:
+		unreachable()
 	}
 	a := s.Sizeof(T) // may be 0
 	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
@@ -118,7 +120,7 @@
 }
 
 func (s *StdSizes) Sizeof(T Type) int64 {
-	switch t := optype(T).(type) {
+	switch t := under(T).(type) {
 	case *Basic:
 		assert(isTyped(T))
 		k := t.kind
@@ -148,10 +150,10 @@
 		}
 		offsets := s.Offsetsof(t.fields)
 		return offsets[n-1] + s.Sizeof(t.fields[n-1].typ)
-	case *_Sum:
-		panic("Sizeof unimplemented for type sum")
 	case *Interface:
 		return s.WordSize * 2
+	case *TypeParam, *Union:
+		unreachable()
 	}
 	return s.WordSize // catch-all
 }
diff --git a/src/go/types/slice.go b/src/go/types/slice.go
new file mode 100644
index 0000000..debdd81
--- /dev/null
+++ b/src/go/types/slice.go
@@ -0,0 +1,19 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Slice represents a slice type.
+type Slice struct {
+	elem Type
+}
+
+// NewSlice returns a new slice type for the given element type.
+func NewSlice(elem Type) *Slice { return &Slice{elem: elem} }
+
+// Elem returns the element type of slice s.
+func (s *Slice) Elem() Type { return s.elem }
+
+func (t *Slice) Underlying() Type { return t }
+func (t *Slice) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/stdlib_test.go b/src/go/types/stdlib_test.go
index d86a77a..3eb7519 100644
--- a/src/go/types/stdlib_test.go
+++ b/src/go/types/stdlib_test.go
@@ -140,8 +140,7 @@
 		// parse and type-check file
 		file, err := parser.ParseFile(fset, filename, nil, 0)
 		if err == nil {
-			conf := Config{Importer: stdLibImporter}
-			SetGoVersion(&conf, goVersion)
+			conf := Config{GoVersion: goVersion, Importer: stdLibImporter}
 			_, err = conf.Check(filename, fset, []*ast.File{file}, nil)
 		}
 
diff --git a/src/go/types/stmt.go b/src/go/types/stmt.go
index 47f6dcf..0f0a2e4 100644
--- a/src/go/types/stmt.go
+++ b/src/go/types/stmt.go
@@ -65,7 +65,8 @@
 
 func (check *Checker) usage(scope *Scope) {
 	var unused []*Var
-	for _, elem := range scope.elems {
+	for name, elem := range scope.elems {
+		elem = resolve(name, elem)
 		if v, _ := elem.(*Var); v != nil && !v.used {
 			unused = append(unused, v)
 		}
@@ -264,7 +265,7 @@
 			// look for duplicate types for a given value
 			// (quadratic algorithm, but these lists tend to be very short)
 			for _, vt := range seen[val] {
-				if check.identical(v.typ, vt.typ) {
+				if Identical(v.typ, vt.typ) {
 					check.errorf(&v, _DuplicateCase, "duplicate case %s in expression switch", &v)
 					check.error(atPos(vt.pos), _DuplicateCase, "\tprevious case") // secondary error, \t indented
 					continue L
@@ -288,7 +289,7 @@
 		// look for duplicate types
 		// (quadratic algorithm, but type switches tend to be reasonably small)
 		for t, other := range seen {
-			if T == nil && t == nil || T != nil && t != nil && check.identical(T, t) {
+			if T == nil && t == nil || T != nil && t != nil && Identical(T, t) {
 				// talk about "case" rather than "type" because of nil case
 				Ts := "nil"
 				if T != nil {
@@ -360,25 +361,33 @@
 		check.errorf(&x, code, "%s %s", &x, msg)
 
 	case *ast.SendStmt:
-		var ch, x operand
+		var ch, val operand
 		check.expr(&ch, s.Chan)
-		check.expr(&x, s.Value)
-		if ch.mode == invalid || x.mode == invalid {
+		check.expr(&val, s.Value)
+		if ch.mode == invalid || val.mode == invalid {
 			return
 		}
-
-		tch := asChan(ch.typ)
-		if tch == nil {
-			check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to non-chan type %s", ch.typ)
+		var elem Type
+		if !underIs(ch.typ, func(u Type) bool {
+			uch, _ := u.(*Chan)
+			if uch == nil {
+				check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to non-channel %s", &ch)
+				return false
+			}
+			if uch.dir == RecvOnly {
+				check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to receive-only channel %s", &ch)
+				return false
+			}
+			if elem != nil && !Identical(uch.elem, elem) {
+				check.invalidOp(inNode(s, s.Arrow), _Todo, "channels of %s must have the same element type", &ch)
+				return false
+			}
+			elem = uch.elem
+			return true
+		}) {
 			return
 		}
-
-		if tch.dir == RecvOnly {
-			check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to receive-only type %s", tch)
-			return
-		}
-
-		check.assignment(&x, tch.elem, "send")
+		check.assignment(&val, elem, "send")
 
 	case *ast.IncDecStmt:
 		var op token.Token
@@ -911,12 +920,12 @@
 			msg = "send-only channel"
 		}
 		return typ.elem, Typ[Invalid], msg
-	case *_Sum:
+	case *Union:
 		first := true
 		var key, val Type
 		var msg string
-		typ.is(func(t Type) bool {
-			k, v, m := rangeKeyVal(under(t), wantKey, wantVal)
+		typ.underIs(func(t Type) bool {
+			k, v, m := rangeKeyVal(t, wantKey, wantVal)
 			if k == nil || m != "" {
 				key, val, msg = k, v, m
 				return false
diff --git a/src/go/types/struct.go b/src/go/types/struct.go
new file mode 100644
index 0000000..48b0734
--- /dev/null
+++ b/src/go/types/struct.go
@@ -0,0 +1,202 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/ast"
+	"go/token"
+	"strconv"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Struct represents a struct type.
+type Struct struct {
+	fields []*Var
+	tags   []string // field tags; nil if there are no tags
+}
+
+// NewStruct returns a new struct with the given fields and corresponding field tags.
+// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
+// only as long as required to hold the tag with the largest index i. Consequently,
+// if no field has a tag, tags may be nil.
+func NewStruct(fields []*Var, tags []string) *Struct {
+	var fset objset
+	for _, f := range fields {
+		if f.name != "_" && fset.insert(f) != nil {
+			panic("multiple fields with the same name")
+		}
+	}
+	if len(tags) > len(fields) {
+		panic("more tags than fields")
+	}
+	return &Struct{fields: fields, tags: tags}
+}
+
+// NumFields returns the number of fields in the struct (including blank and embedded fields).
+func (s *Struct) NumFields() int { return len(s.fields) }
+
+// Field returns the i'th field for 0 <= i < NumFields().
+func (s *Struct) Field(i int) *Var { return s.fields[i] }
+
+// Tag returns the i'th field tag for 0 <= i < NumFields().
+func (s *Struct) Tag(i int) string {
+	if i < len(s.tags) {
+		return s.tags[i]
+	}
+	return ""
+}
+
+func (t *Struct) Underlying() Type { return t }
+func (t *Struct) String() string   { return TypeString(t, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (check *Checker) structType(styp *Struct, e *ast.StructType) {
+	list := e.Fields
+	if list == nil {
+		return
+	}
+
+	// struct fields and tags
+	var fields []*Var
+	var tags []string
+
+	// for double-declaration checks
+	var fset objset
+
+	// current field typ and tag
+	var typ Type
+	var tag string
+	add := func(ident *ast.Ident, embedded bool, pos token.Pos) {
+		if tag != "" && tags == nil {
+			tags = make([]string, len(fields))
+		}
+		if tags != nil {
+			tags = append(tags, tag)
+		}
+
+		name := ident.Name
+		fld := NewField(pos, check.pkg, name, typ, embedded)
+		// spec: "Within a struct, non-blank field names must be unique."
+		if name == "_" || check.declareInSet(&fset, pos, fld) {
+			fields = append(fields, fld)
+			check.recordDef(ident, fld)
+		}
+	}
+
+	// addInvalid adds an embedded field of invalid type to the struct for
+	// fields with errors; this keeps the number of struct fields in sync
+	// with the source as long as the fields are _ or have different names
+	// (issue #25627).
+	addInvalid := func(ident *ast.Ident, pos token.Pos) {
+		typ = Typ[Invalid]
+		tag = ""
+		add(ident, true, pos)
+	}
+
+	for _, f := range list.List {
+		typ = check.varType(f.Type)
+		tag = check.tag(f.Tag)
+		if len(f.Names) > 0 {
+			// named fields
+			for _, name := range f.Names {
+				add(name, false, name.Pos())
+			}
+		} else {
+			// embedded field
+			// spec: "An embedded type must be specified as a type name T or as a
+			// pointer to a non-interface type name *T, and T itself may not be a
+			// pointer type."
+			pos := f.Type.Pos()
+			name := embeddedFieldIdent(f.Type)
+			if name == nil {
+				// TODO(rFindley): using invalidAST here causes test failures (all
+				//                 errors should have codes). Clean this up.
+				check.errorf(f.Type, _Todo, "invalid AST: embedded field type %s has no name", f.Type)
+				name = ast.NewIdent("_")
+				name.NamePos = pos
+				addInvalid(name, pos)
+				continue
+			}
+			add(name, true, pos)
+
+			// Because we have a name, typ must be of the form T or *T, where T is the name
+			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
+			// We must delay this check to the end because we don't want to instantiate
+			// (via under(t)) a possibly incomplete type.
+
+			// for use in the closure below
+			embeddedTyp := typ
+			embeddedPos := f.Type
+
+			check.later(func() {
+				t, isPtr := deref(embeddedTyp)
+				switch t := under(t).(type) {
+				case *Basic:
+					if t == Typ[Invalid] {
+						// error was reported before
+						return
+					}
+					// unsafe.Pointer is treated like a regular pointer
+					if t.kind == UnsafePointer {
+						check.error(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be unsafe.Pointer")
+					}
+				case *Pointer:
+					check.error(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a pointer")
+				case *TypeParam:
+					check.error(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a (pointer to a) type parameter")
+				case *Interface:
+					if isPtr {
+						check.error(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a pointer to an interface")
+					}
+				}
+			})
+		}
+	}
+
+	styp.fields = fields
+	styp.tags = tags
+}
+
+func embeddedFieldIdent(e ast.Expr) *ast.Ident {
+	switch e := e.(type) {
+	case *ast.Ident:
+		return e
+	case *ast.StarExpr:
+		// *T is valid, but **T is not
+		if _, ok := e.X.(*ast.StarExpr); !ok {
+			return embeddedFieldIdent(e.X)
+		}
+	case *ast.SelectorExpr:
+		return e.Sel
+	case *ast.IndexExpr:
+		return embeddedFieldIdent(e.X)
+	}
+	return nil // invalid embedded field
+}
+
+func (check *Checker) declareInSet(oset *objset, pos token.Pos, obj Object) bool {
+	if alt := oset.insert(obj); alt != nil {
+		check.errorf(atPos(pos), _DuplicateDecl, "%s redeclared", obj.Name())
+		check.reportAltDecl(alt)
+		return false
+	}
+	return true
+}
+
+func (check *Checker) tag(t *ast.BasicLit) string {
+	if t != nil {
+		if t.Kind == token.STRING {
+			if val, err := strconv.Unquote(t.Value); err == nil {
+				return val
+			}
+		}
+		check.invalidAST(t, "incorrect tag syntax: %q", t.Value)
+	}
+	return ""
+}
diff --git a/src/go/types/subst.go b/src/go/types/subst.go
index 931375f..322e30d 100644
--- a/src/go/types/subst.go
+++ b/src/go/types/subst.go
@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This file implements instantiation of generic types
-// through substitution of type parameters by actual
-// types.
+// This file implements type parameter substitution.
 
 package types
 
@@ -22,21 +20,16 @@
 	// TODO(gri) rewrite that code, get rid of this field, and make this
 	//           struct just the map (proj)
 	targs []Type
-	proj  map[*_TypeParam]Type
+	proj  map[*TypeParam]Type
 }
 
 // makeSubstMap creates a new substitution map mapping tpars[i] to targs[i].
 // If targs[i] is nil, tpars[i] is not substituted.
 func makeSubstMap(tpars []*TypeName, targs []Type) *substMap {
 	assert(len(tpars) == len(targs))
-	proj := make(map[*_TypeParam]Type, len(tpars))
+	proj := make(map[*TypeParam]Type, len(tpars))
 	for i, tpar := range tpars {
-		// We must expand type arguments otherwise *instance
-		// types end up as components in composite types.
-		// TODO(gri) explain why this causes problems, if it does
-		targ := expand(targs[i]) // possibly nil
-		targs[i] = targ
-		proj[tpar.typ.(*_TypeParam)] = targ
+		proj[tpar.typ.(*TypeParam)] = targs[i]
 	}
 	return &substMap{targs, proj}
 }
@@ -49,165 +42,13 @@
 	return len(m.proj) == 0
 }
 
-func (m *substMap) lookup(tpar *_TypeParam) Type {
+func (m *substMap) lookup(tpar *TypeParam) Type {
 	if t := m.proj[tpar]; t != nil {
 		return t
 	}
 	return tpar
 }
 
-func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, poslist []token.Pos) (res Type) {
-	if trace {
-		check.trace(pos, "-- instantiating %s with %s", typ, typeListString(targs))
-		check.indent++
-		defer func() {
-			check.indent--
-			var under Type
-			if res != nil {
-				// Calling under() here may lead to endless instantiations.
-				// Test case: type T[P any] T[P]
-				// TODO(gri) investigate if that's a bug or to be expected.
-				under = res.Underlying()
-			}
-			check.trace(pos, "=> %s (under = %s)", res, under)
-		}()
-	}
-
-	assert(len(poslist) <= len(targs))
-
-	// TODO(gri) What is better here: work with TypeParams, or work with TypeNames?
-	var tparams []*TypeName
-	switch t := typ.(type) {
-	case *Named:
-		tparams = t.tparams
-	case *Signature:
-		tparams = t.tparams
-		defer func() {
-			// If we had an unexpected failure somewhere don't panic below when
-			// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
-			// is returned.
-			if _, ok := res.(*Signature); !ok {
-				return
-			}
-			// If the signature doesn't use its type parameters, subst
-			// will not make a copy. In that case, make a copy now (so
-			// we can set tparams to nil w/o causing side-effects).
-			if t == res {
-				copy := *t
-				res = &copy
-			}
-			// After instantiating a generic signature, it is not generic
-			// anymore; we need to set tparams to nil.
-			res.(*Signature).tparams = nil
-		}()
-
-	default:
-		check.dump("%v: cannot instantiate %v", pos, typ)
-		unreachable() // only defined types and (defined) functions can be generic
-	}
-
-	// the number of supplied types must match the number of type parameters
-	if len(targs) != len(tparams) {
-		// TODO(gri) provide better error message
-		check.errorf(atPos(pos), _Todo, "got %d arguments but %d type parameters", len(targs), len(tparams))
-		return Typ[Invalid]
-	}
-
-	if len(tparams) == 0 {
-		return typ // nothing to do (minor optimization)
-	}
-
-	smap := makeSubstMap(tparams, targs)
-
-	// check bounds
-	for i, tname := range tparams {
-		tpar := tname.typ.(*_TypeParam)
-		iface := tpar.Bound()
-		if iface.Empty() {
-			continue // no type bound
-		}
-
-		targ := targs[i]
-
-		// best position for error reporting
-		pos := pos
-		if i < len(poslist) {
-			pos = poslist[i]
-		}
-
-		// The type parameter bound is parameterized with the same type parameters
-		// as the instantiated type; before we can use it for bounds checking we
-		// need to instantiate it with the type arguments with which we instantiate
-		// the parameterized type.
-		iface = check.subst(pos, iface, smap).(*Interface)
-
-		// targ must implement iface (methods)
-		// - check only if we have methods
-		check.completeInterface(token.NoPos, iface)
-		if len(iface.allMethods) > 0 {
-			// If the type argument is a pointer to a type parameter, the type argument's
-			// method set is empty.
-			// TODO(gri) is this what we want? (spec question)
-			if base, isPtr := deref(targ); isPtr && asTypeParam(base) != nil {
-				check.errorf(atPos(pos), 0, "%s has no methods", targ)
-				break
-			}
-			if m, wrong := check.missingMethod(targ, iface, true); m != nil {
-				// TODO(gri) needs to print updated name to avoid major confusion in error message!
-				//           (print warning for now)
-				// Old warning:
-				// check.softErrorf(pos, "%s does not satisfy %s (warning: name not updated) = %s (missing method %s)", targ, tpar.bound, iface, m)
-				if m.name == "==" {
-					// We don't want to report "missing method ==".
-					check.softErrorf(atPos(pos), 0, "%s does not satisfy comparable", targ)
-				} else if wrong != nil {
-					// TODO(gri) This can still report uninstantiated types which makes the error message
-					//           more difficult to read then necessary.
-					// TODO(rFindley) should this use parentheses rather than ':' for qualification?
-					check.softErrorf(atPos(pos), _Todo,
-						"%s does not satisfy %s: wrong method signature\n\tgot  %s\n\twant %s",
-						targ, tpar.bound, wrong, m,
-					)
-				} else {
-					check.softErrorf(atPos(pos), 0, "%s does not satisfy %s (missing method %s)", targ, tpar.bound, m.name)
-				}
-				break
-			}
-		}
-
-		// targ's underlying type must also be one of the interface types listed, if any
-		if iface.allTypes == nil {
-			continue // nothing to do
-		}
-
-		// If targ is itself a type parameter, each of its possible types, but at least one, must be in the
-		// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
-		if targ := asTypeParam(targ); targ != nil {
-			targBound := targ.Bound()
-			if targBound.allTypes == nil {
-				check.softErrorf(atPos(pos), _Todo, "%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
-				break
-			}
-			for _, t := range unpackType(targBound.allTypes) {
-				if !iface.isSatisfiedBy(t) {
-					// TODO(gri) match this error message with the one below (or vice versa)
-					check.softErrorf(atPos(pos), 0, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, t, iface.allTypes)
-					break
-				}
-			}
-			break
-		}
-
-		// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
-		if !iface.isSatisfiedBy(targ) {
-			check.softErrorf(atPos(pos), _Todo, "%s does not satisfy %s (%s or %s not found in %s)", targ, tpar.bound, targ, under(targ), iface.allTypes)
-			break
-		}
-	}
-
-	return check.subst(pos, typ, smap)
-}
-
 // subst returns the type typ with its type parameters tpars replaced by
 // the corresponding type arguments targs, recursively.
 // subst is functional in the sense that it doesn't modify the incoming
@@ -222,20 +63,33 @@
 	switch t := typ.(type) {
 	case *Basic:
 		return typ // nothing to do
-	case *_TypeParam:
+	case *TypeParam:
 		return smap.lookup(t)
 	}
 
 	// general case
-	subst := subster{check, pos, make(map[Type]Type), smap}
+	var subst subster
+	subst.pos = pos
+	subst.smap = smap
+	if check != nil {
+		subst.check = check
+		subst.typMap = check.typMap
+	} else {
+		// If we don't have a *Checker and its global type map,
+		// use a local version. Besides avoiding duplicate work,
+		// the type map prevents infinite recursive substitution
+		// for recursive types (example: type T[P any] *T[P]).
+		subst.typMap = make(map[string]*Named)
+	}
+
 	return subst.typ(typ)
 }
 
 type subster struct {
-	check *Checker
-	pos   token.Pos
-	cache map[Type]Type
-	smap  *substMap
+	pos    token.Pos
+	smap   *substMap
+	check  *Checker // nil if called via Instantiate
+	typMap map[string]*Named
 }
 
 func (subst *subster) typ(typ Type) Type {
@@ -244,7 +98,7 @@
 		// Call typOrNil if it's possible that typ is nil.
 		panic("nil typ")
 
-	case *Basic, *bottom, *top:
+	case *Basic, *top:
 		// nothing to do
 
 	case *Array:
@@ -293,26 +147,23 @@
 			}
 		}
 
-	case *_Sum:
-		types, copied := subst.typeList(t.types)
+	case *Union:
+		terms, copied := subst.termList(t.terms)
 		if copied {
-			// Don't do it manually, with a Sum literal: the new
-			// types list may not be unique and NewSum may remove
-			// duplicates.
-			return _NewSum(types)
+			// TODO(gri) Remove duplicates that may have crept in after substitution
+			//           (unlikely but possible). This matters for the Identical
+			//           predicate on unions.
+			return &Union{terms}
 		}
 
 	case *Interface:
 		methods, mcopied := subst.funcList(t.methods)
-		types := t.types
-		if t.types != nil {
-			types = subst.typ(t.types)
-		}
 		embeddeds, ecopied := subst.typeList(t.embeddeds)
-		if mcopied || types != t.types || ecopied {
-			iface := &Interface{methods: methods, types: types, embeddeds: embeddeds}
-			subst.check.posMap[iface] = subst.check.posMap[t] // satisfy completeInterface requirement
-			subst.check.completeInterface(token.NoPos, iface)
+		if mcopied || ecopied {
+			iface := &Interface{methods: methods, embeddeds: embeddeds, complete: t.complete}
+			if subst.check == nil {
+				panic("internal error: cannot instantiate interfaces yet")
+			}
 			return iface
 		}
 
@@ -330,17 +181,19 @@
 		}
 
 	case *Named:
-		subst.check.indent++
-		defer func() {
-			subst.check.indent--
-		}()
-		dump := func(format string, args ...interface{}) {
-			if trace {
+		// dump is for debugging
+		dump := func(string, ...interface{}) {}
+		if subst.check != nil && trace {
+			subst.check.indent++
+			defer func() {
+				subst.check.indent--
+			}()
+			dump = func(format string, args ...interface{}) {
 				subst.check.trace(subst.pos, format, args...)
 			}
 		}
 
-		if t.tparams == nil {
+		if t.TParams().Len() == 0 {
 			dump(">>> %s is not parameterized", t)
 			return t // type is not parameterized
 		}
@@ -350,7 +203,7 @@
 		if len(t.targs) > 0 {
 			// already instantiated
 			dump(">>> %s already instantiated", t)
-			assert(len(t.targs) == len(t.tparams))
+			assert(len(t.targs) == t.TParams().Len())
 			// For each (existing) type argument targ, determine if it needs
 			// to be substituted; i.e., if it is or contains a type parameter
 			// that has a type argument for it.
@@ -360,7 +213,7 @@
 				if newTarg != targ {
 					dump(">>> substituted %d targ %s => %s", i, targ, newTarg)
 					if newTargs == nil {
-						newTargs = make([]Type, len(t.tparams))
+						newTargs = make([]Type, t.TParams().Len())
 						copy(newTargs, t.targs)
 					}
 					newTargs[i] = newTarg
@@ -381,34 +234,30 @@
 		// before creating a new named type, check if we have this one already
 		h := instantiatedHash(t, newTargs)
 		dump(">>> new type hash: %s", h)
-		if named, found := subst.check.typMap[h]; found {
+		if named, found := subst.typMap[h]; found {
 			dump(">>> found %s", named)
-			subst.cache[t] = named
 			return named
 		}
 
-		// create a new named type and populate caches to avoid endless recursion
+		// create a new named type and populate typMap to avoid endless recursion
 		tname := NewTypeName(subst.pos, t.obj.pkg, t.obj.name, nil)
-		named := subst.check.newNamed(tname, t.underlying, t.methods) // method signatures are updated lazily
-		named.tparams = t.tparams                                     // new type is still parameterized
+		named := subst.check.newNamed(tname, t, t.Underlying(), t.TParams(), t.methods) // method signatures are updated lazily
 		named.targs = newTargs
-		subst.check.typMap[h] = named
-		subst.cache[t] = named
+		subst.typMap[h] = named
+		t.expand() // must happen after typMap update to avoid infinite recursion
 
 		// do the substitution
 		dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTargs)
-		named.underlying = subst.typOrNil(t.underlying)
-		named.orig = named.underlying // for cycle detection (Checker.validType)
+		named.underlying = subst.typOrNil(t.Underlying())
+		dump(">>> underlying: %v", named.underlying)
+		assert(named.underlying != nil)
+		named.fromRHS = named.underlying // for cycle detection (Checker.validType)
 
 		return named
 
-	case *_TypeParam:
+	case *TypeParam:
 		return subst.smap.lookup(t)
 
-	case *instance:
-		// TODO(gri) can we avoid the expansion here and just substitute the type parameters?
-		return subst.typ(t.expand())
-
 	default:
 		panic("unimplemented")
 	}
@@ -416,14 +265,17 @@
 	return typ
 }
 
-// TODO(gri) Eventually, this should be more sophisticated.
-//           It won't work correctly for locally declared types.
+var instanceHashing = 0
+
 func instantiatedHash(typ *Named, targs []Type) string {
+	assert(instanceHashing == 0)
+	instanceHashing++
 	var buf bytes.Buffer
 	writeTypeName(&buf, typ.obj, nil)
 	buf.WriteByte('[')
 	writeTypeList(&buf, targs, nil, nil)
 	buf.WriteByte(']')
+	instanceHashing--
 
 	// With respect to the represented type, whether a
 	// type is fully expanded or stored as instance
@@ -541,3 +393,21 @@
 	}
 	return
 }
+
+func (subst *subster) termList(in []*term) (out []*term, copied bool) {
+	out = in
+	for i, t := range in {
+		if u := subst.typ(t.typ); u != t.typ {
+			if !copied {
+				// first function that got substituted => allocate new out slice
+				// and copy all functions
+				new := make([]*term, len(in))
+				copy(new, out)
+				out = new
+				copied = true
+			}
+			out[i] = &term{t.tilde, u}
+		}
+	}
+	return
+}
diff --git a/src/go/types/testdata/check/builtins.go2 b/src/go/types/testdata/check/builtins.go2
index 3918d83..3881090 100644
--- a/src/go/types/testdata/check/builtins.go2
+++ b/src/go/types/testdata/check/builtins.go2
@@ -6,48 +6,231 @@
 
 package builtins
 
+import "unsafe"
+
+// close
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+	close(ch /* ERROR cannot close non-channel */)
+}
+
+func _[T C0](ch T) {
+	close(ch /* ERROR cannot close non-channel */)
+}
+
+func _[T C1](ch T) {
+	close(ch)
+}
+
+func _[T C2](ch T) {
+	close(ch /* ERROR cannot close receive-only channel */)
+}
+
+func _[T C3](ch T) {
+	close(ch)
+}
+
+func _[T C4](ch T) {
+	close(ch)
+}
+
+func _[T C5[X], X any](ch T) {
+	close(ch)
+}
+
+// delete
+
+type M0 interface{ int }
+type M1 interface{ map[string]int }
+type M2 interface { map[string]int | map[string]float64 }
+type M3 interface{ map[string]int | map[rune]int }
+type M4[K comparable, V any] interface{ map[K]V | map[rune]V }
+
+func _[T any](m T) {
+	delete(m /* ERROR not a map */, "foo")
+}
+
+func _[T M0](m T) {
+	delete(m /* ERROR not a map */, "foo")
+}
+
+func _[T M1](m T) {
+	delete(m, "foo")
+}
+
+func _[T M2](m T) {
+	delete(m, "foo")
+	delete(m, 0 /* ERROR cannot use .* as string */)
+}
+
+func _[T M3](m T) {
+	delete(m /* ERROR must have identical key types */, "foo")
+}
+
+func _[T M4[rune, V], V any](m T) {
+	delete(m, 'k')
+}
+
+func _[T M4[K, V], K comparable, V any](m T) {
+	delete(m /* ERROR must have identical key types */, "foo")
+}
+
+// make
+
 type Bmc interface {
-	type map[rune]string, chan int
+	~map[rune]string | ~chan int
 }
 
 type Bms interface {
-	type map[string]int, []int
+	~map[string]int | ~[]int
 }
 
 type Bcs interface {
-	type chan bool, []float64
+	~chan bool | ~[]float64
 }
 
 type Bss interface {
-	type []int, []string
+	~[]int | ~[]string
 }
 
-func _[T any] () {
-	_ = make(T /* ERROR invalid argument */ )
-	_ = make(T /* ERROR invalid argument */ , 10)
-	_ = make(T /* ERROR invalid argument */ , 10, 20)
+func _[T any]() {
+	_ = make(T /* ERROR invalid argument */)
+	_ = make(T /* ERROR invalid argument */, 10)
+	_ = make(T /* ERROR invalid argument */, 10, 20)
 }
 
-func _[T Bmc] () {
+func _[T Bmc]() {
 	_ = make(T)
 	_ = make(T, 10)
 	_ = make /* ERROR expects 1 or 2 arguments */ (T, 10, 20)
 }
 
-func _[T Bms] () {
+func _[T Bms]() {
 	_ = make /* ERROR expects 2 arguments */ (T)
 	_ = make(T, 10)
 	_ = make /* ERROR expects 2 arguments */ (T, 10, 20)
 }
 
-func _[T Bcs] () {
+func _[T Bcs]() {
 	_ = make /* ERROR expects 2 arguments */ (T)
 	_ = make(T, 10)
 	_ = make /* ERROR expects 2 arguments */ (T, 10, 20)
 }
 
-func _[T Bss] () {
+func _[T Bss]() {
 	_ = make /* ERROR expects 2 or 3 arguments */ (T)
 	_ = make(T, 10)
 	_ = make(T, 10, 20)
 }
+
+// unsafe.Alignof
+
+func _[T comparable]() {
+	var (
+		b int64
+		a [10]T
+		s struct{ f T }
+		p *T
+		l []T
+		f func(T)
+		i interface{ m() T }
+		c chan T
+		m map[T]T
+		t T
+	)
+
+	const bb = unsafe.Alignof(b)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Alignof(p)
+	assert(pp == 8)
+	const ll = unsafe.Alignof(l)
+	assert(ll == 8)
+	const ff = unsafe.Alignof(f)
+	assert(ff == 8)
+	const ii = unsafe.Alignof(i)
+	assert(ii == 8)
+	const cc = unsafe.Alignof(c)
+	assert(cc == 8)
+	const mm = unsafe.Alignof(m)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
+
+// unsafe.Offsetof
+
+func _[T comparable]() {
+	var (
+		b struct{ _, f int64 }
+		a struct{ _, f [10]T }
+		s struct{ _, f struct{ f T } }
+		p struct{ _, f *T }
+		l struct{ _, f []T }
+		f struct{ _, f func(T) }
+		i struct{ _, f interface{ m() T } }
+		c struct{ _, f chan T }
+		m struct{ _, f map[T]T }
+		t struct{ _, f T }
+	)
+
+	const bb = unsafe.Offsetof(b.f)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Offsetof(p.f)
+	assert(pp == 8)
+	const ll = unsafe.Offsetof(l.f)
+	assert(ll == 24)
+	const ff = unsafe.Offsetof(f.f)
+	assert(ff == 8)
+	const ii = unsafe.Offsetof(i.f)
+	assert(ii == 16)
+	const cc = unsafe.Offsetof(c.f)
+	assert(cc == 8)
+	const mm = unsafe.Offsetof(m.f)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
+
+// unsafe.Sizeof
+
+func _[T comparable]() {
+	var (
+		b int64
+		a [10]T
+		s struct{ f T }
+		p *T
+		l []T
+		f func(T)
+		i interface{ m() T }
+		c chan T
+		m map[T]T
+		t T
+	)
+
+	const bb = unsafe.Sizeof(b)
+	assert(bb == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(a)
+	const _ = unsafe /* ERROR not constant */ .Alignof(s)
+	const pp = unsafe.Sizeof(p)
+	assert(pp == 8)
+	const ll = unsafe.Sizeof(l)
+	assert(ll == 24)
+	const ff = unsafe.Sizeof(f)
+	assert(ff == 8)
+	const ii = unsafe.Sizeof(i)
+	assert(ii == 16)
+	const cc = unsafe.Sizeof(c)
+	assert(cc == 8)
+	const mm = unsafe.Sizeof(m)
+	assert(mm == 8)
+	const _ = unsafe /* ERROR not constant */ .Alignof(t)
+}
diff --git a/src/go/types/testdata/check/builtins.src b/src/go/types/testdata/check/builtins.src
index 3707528..7fd6a4b 100644
--- a/src/go/types/testdata/check/builtins.src
+++ b/src/go/types/testdata/check/builtins.src
@@ -144,7 +144,7 @@
 	var r <-chan int
 	close() // ERROR not enough arguments
 	close(1, 2) // ERROR too many arguments
-	close(42 /* ERROR not a channel */)
+	close(42 /* ERROR cannot close non-channel */)
 	close(r /* ERROR receive-only channel */)
 	close(c)
 	_ = close /* ERROR used as value */ (c)
diff --git a/src/go/types/testdata/check/const0.src b/src/go/types/testdata/check/const0.src
index 5608b15..3cffdf9 100644
--- a/src/go/types/testdata/check/const0.src
+++ b/src/go/types/testdata/check/const0.src
@@ -27,7 +27,7 @@
 	ub1 = true
 	ub2 = 2 < 1
 	ub3 = ui1 == uf1
-	ub4 = true /* ERROR "cannot convert" */ == 0
+	ub4 = true /* ERROR "mismatched types untyped bool and untyped int" */ == 0
 
 	// integer values
 	ui0 = 0
diff --git a/src/go/types/testdata/check/cycles4.src b/src/go/types/testdata/check/cycles4.src
index 445babc..924aabf 100644
--- a/src/go/types/testdata/check/cycles4.src
+++ b/src/go/types/testdata/check/cycles4.src
@@ -4,6 +4,8 @@
 
 package p
 
+import "unsafe"
+
 // Check that all methods of T are collected before
 // determining the result type of m (which embeds
 // all methods of T).
@@ -13,7 +15,7 @@
 	E
 }
 
-var _ = T.m(nil).m().e()
+var _ int = T.m(nil).m().e()
 
 type E interface {
 	e() int
@@ -22,7 +24,7 @@
 // Check that unresolved forward chains are followed
 // (see also comment in resolver.go, checker.typeDecl).
 
-var _ = C.m(nil).m().e()
+var _ int = C.m(nil).m().e()
 
 type A B
 
@@ -108,3 +110,12 @@
 type Event interface {
 	Target() Element
 }
+
+// Check that accessing an interface method too early doesn't lead
+// to follow-on errors due to an incorrectly computed type set.
+
+type T8 interface {
+	m() [unsafe.Sizeof(T8.m /* ERROR undefined */ )]int
+}
+
+var _ = T8.m // no error expected here
diff --git a/src/go/types/testdata/check/decls0.src b/src/go/types/testdata/check/decls0.src
index 5ad8f53..1224e46 100644
--- a/src/go/types/testdata/check/decls0.src
+++ b/src/go/types/testdata/check/decls0.src
@@ -4,7 +4,7 @@
 
 // type declarations
 
-package decls0
+package go1_17 // don't permit non-interface elements in interfaces
 
 import "unsafe"
 
@@ -187,10 +187,10 @@
 // TODO(#43215) this should be detected as a cycle error
 func f5([unsafe.Sizeof(f5)]int) {}
 
-func (S0) m1 (x S0 /* ERROR value .* is not a type */ .m1) {}
-func (S0) m2 (x *S0 /* ERROR value .* is not a type */ .m2) {}
-func (S0) m3 () (x S0 /* ERROR value .* is not a type */ .m3) { return }
-func (S0) m4 () (x *S0 /* ERROR value .* is not a type */ .m4) { return }
+func (S0) m1 (x S0 /* ERROR illegal cycle in method declaration */ .m1) {}
+func (S0) m2 (x *S0 /* ERROR illegal cycle in method declaration */ .m2) {}
+func (S0) m3 () (x S0 /* ERROR illegal cycle in method declaration */ .m3) { return }
+func (S0) m4 () (x *S0 /* ERROR illegal cycle in method declaration */ .m4) { return }
 
 // interfaces may not have any blank methods
 type BlankI interface {
diff --git a/src/go/types/testdata/check/decls1.src b/src/go/types/testdata/check/decls1.src
index f4d2eab..6fe349b 100644
--- a/src/go/types/testdata/check/decls1.src
+++ b/src/go/types/testdata/check/decls1.src
@@ -83,7 +83,7 @@
 
 // Constant expression initializations
 var (
-	v1 = 1 /* ERROR "cannot convert" */ + "foo"
+	v1 = 1 /* ERROR "mismatched types untyped int and untyped string" */ + "foo"
 	v2 = c + 255
 	v3 = c + 256 /* ERROR "overflows" */
 	v4 = r + 2147483647
diff --git a/src/go/types/testdata/check/expr1.src b/src/go/types/testdata/check/expr1.src
index 4ead815..42b95fb 100644
--- a/src/go/types/testdata/check/expr1.src
+++ b/src/go/types/testdata/check/expr1.src
@@ -111,10 +111,10 @@
 func _(x, y string, z mystring) {
 	x = x + "foo"
 	x = x /* ERROR not defined */ - "foo"
-	x = x + 1 // ERROR cannot convert
+	x = x /* ERROR mismatched types string and untyped int */ + 1
 	x = x + y
 	x = x /* ERROR not defined */ - y
-	x = x * 10 // ERROR cannot convert
+	x = x /* ERROR mismatched types string and untyped int */* 10
 }
 
 func f() (a, b int) { return }
diff --git a/src/go/types/testdata/check/expr2.src b/src/go/types/testdata/check/expr2.src
index 0c959e8..f9726b5 100644
--- a/src/go/types/testdata/check/expr2.src
+++ b/src/go/types/testdata/check/expr2.src
@@ -10,7 +10,7 @@
 	const t = true == true
 	const f = true == false
 	_ = t /* ERROR "cannot compare" */ < f
-	_ = 0 /* ERROR "cannot convert" */ == t
+	_ = 0 /* ERROR "mismatched types untyped int and untyped bool" */ == t
 	var b bool
 	var x, y float32
 	b = x < y
diff --git a/src/go/types/testdata/check/expr3.src b/src/go/types/testdata/check/expr3.src
index 0525a5a..3ab3678 100644
--- a/src/go/types/testdata/check/expr3.src
+++ b/src/go/types/testdata/check/expr3.src
@@ -103,7 +103,7 @@
 	var ok mybool
 	_, ok = m["bar"]
 	_ = ok
-	_ = m[0 /* ERROR "cannot use 0" */ ] + "foo" // ERROR "cannot convert"
+	_ = m/* ERROR "mismatched types int and untyped string" */[0 /* ERROR "cannot use 0" */ ] + "foo"
 
 	var t string
 	_ = t[- /* ERROR "negative" */ 1]
diff --git a/src/go/types/testdata/check/issues.go2 b/src/go/types/testdata/check/issues.go2
index 8994164..6a1a10a 100644
--- a/src/go/types/testdata/check/issues.go2
+++ b/src/go/types/testdata/check/issues.go2
@@ -24,22 +24,20 @@
 	eql[io.Reader](nil, nil)
 }
 
-// If we have a receiver of pointer type (below: *T) we must ignore
-// the pointer in the implementation of the method lookup because
-// the type bound of T is an interface and pointer to interface types
-// have no methods and then the lookup would fail.
+// If we have a receiver of pointer to type parameter type (below: *T)
+// we don't have any methods, like for interfaces.
 type C[T any] interface {
     m()
 }
 
 // using type bound C
 func _[T C[T]](x *T) {
-	x.m()
+	x.m  /* ERROR x\.m undefined */ ()
 }
 
 // using an interface literal as bound
 func _[T interface{ m() }](x *T) {
-	x.m()
+	x.m  /* ERROR x\.m undefined */ ()
 }
 
 // In a generic function body all method calls will be pointer method calls.
@@ -64,15 +62,15 @@
 // type with a type list constraint, all of the type argument's types in its
 // bound, but at least one (!), must be in the type list of the bound of the
 // corresponding parameterized type's type parameter.
-type T1[P interface{type uint}] struct{}
+type T1[P interface{~uint}] struct{}
 
 func _[P any]() {
-    _ = T1[P /* ERROR P has no type constraints */ ]{}
+    _ = T1[P /* ERROR P has no constraints */ ]{}
 }
 
 // This is the original (simplified) program causing the same issue.
 type Unsigned interface {
-	type uint
+	~uint
 }
 
 type T2[U Unsigned] struct {
@@ -83,8 +81,8 @@
     return u.s + 1
 }
 
-func NewT2[U any]() T2[U /* ERROR U has no type constraints */ ] {
-    return T2[U /* ERROR U has no type constraints */ ]{}
+func NewT2[U any]() T2[U /* ERROR U has no constraints */ ] {
+    return T2[U /* ERROR U has no constraints */ ]{}
 }
 
 func _() {
@@ -163,7 +161,7 @@
 // predicate disjunction in the implementation was wrong because if a type list
 // contains both an integer and a floating-point type, the type parameter is
 // neither an integer or a floating-point number.
-func convert[T1, T2 interface{type int, uint, float32}](v T1) T2 {
+func convert[T1, T2 interface{~int | ~uint | ~float32}](v T1) T2 {
 	return T2(v)
 }
 
@@ -175,12 +173,12 @@
 // both numeric, or both strings. The implementation had the same problem
 // with this check as the conversion issue above (issue #39623).
 
-func issue39623[T interface{type int, string}](x, y T) T {
+func issue39623[T interface{~int | ~string}](x, y T) T {
 	return x + y
 }
 
 // Simplified, from https://go2goplay.golang.org/p/efS6x6s-9NI:
-func Sum[T interface{type int, string}](s []T) (sum T) {
+func Sum[T interface{~int | ~string}](s []T) (sum T) {
 	for _, v := range s {
 		sum += v
 	}
@@ -189,19 +187,19 @@
 
 // Assignability of an unnamed pointer type to a type parameter that
 // has a matching underlying type.
-func _[T interface{}, PT interface{type *T}] (x T) PT {
+func _[T interface{}, PT interface{~*T}] (x T) PT {
     return &x
 }
 
 // Indexing of generic types containing type parameters in their type list:
-func at[T interface{ type []E }, E interface{}](x T, i int) E {
+func at[T interface{ ~[]E }, E interface{}](x T, i int) E {
         return x[i]
 }
 
 // A generic type inside a function acts like a named type. Its underlying
 // type is itself, its "operational type" is defined by the type list in
 // the tybe bound, if any.
-func _[T interface{type int}](x T) {
+func _[T interface{~int}](x T) {
 	type myint int
 	var _ int = int(x)
 	var _ T = 42
@@ -210,24 +208,24 @@
 
 // Indexing a generic type with an array type bound checks length.
 // (Example by mdempsky@.)
-func _[T interface { type [10]int }](x T) {
+func _[T interface { ~[10]int }](x T) {
 	_ = x[9] // ok
 	_ = x[20 /* ERROR out of bounds */ ]
 }
 
 // Pointer indirection of a generic type.
-func _[T interface{ type *int }](p T) int {
+func _[T interface{ ~*int }](p T) int {
 	return *p
 }
 
 // Channel sends and receives on generic types.
-func _[T interface{ type chan int }](ch T) int {
+func _[T interface{ ~chan int }](ch T) int {
 	ch <- 0
 	return <- ch
 }
 
 // Calling of a generic variable.
-func _[T interface{ type func() }](f T) {
+func _[T interface{ ~func() }](f T) {
 	f()
 	go f()
 }
@@ -239,9 +237,9 @@
 // type parameter that was substituted with a defined type.
 // Test case from an (originally) failing example.
 
-type sliceOf[E any] interface{ type []E }
+type sliceOf[E any] interface{ ~[]E }
 
-func append[T interface{}, S sliceOf[T], T2 interface{ type T }](s S, t ...T2) S
+func append[T interface{}, S sliceOf[T], T2 interface{}](s S, t ...T2) S
 
 var f           func()
 var cancelSlice []context.CancelFunc
diff --git a/src/go/types/testdata/check/issues.src b/src/go/types/testdata/check/issues.src
index 55fe220..ef17373 100644
--- a/src/go/types/testdata/check/issues.src
+++ b/src/go/types/testdata/check/issues.src
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package issues
+package go1_17 // don't permit non-interface elements in interfaces
 
 import (
 	"fmt"
diff --git a/src/go/types/testdata/check/linalg.go2 b/src/go/types/testdata/check/linalg.go2
index 0d27603..efc090a 100644
--- a/src/go/types/testdata/check/linalg.go2
+++ b/src/go/types/testdata/check/linalg.go2
@@ -9,10 +9,10 @@
 // Numeric is type bound that matches any numeric type.
 // It would likely be in a constraints package in the standard library.
 type Numeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		complex64, complex128
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~complex64 | ~complex128
 }
 
 func DotProduct[T Numeric](s1, s2 []T) T {
@@ -42,14 +42,14 @@
 
 // OrderedNumeric is a type bound that matches numeric types that support the < operator.
 type OrderedNumeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
 }
 
 // Complex is a type bound that matches the two complex types, which do not have a < operator.
 type Complex interface {
-	type complex64, complex128
+	~complex64 | ~complex128
 }
 
 // OrderedAbs is a helper type that defines an Abs method for
diff --git a/src/go/types/testdata/check/stmt0.src b/src/go/types/testdata/check/stmt0.src
index 76b6e70..15df377 100644
--- a/src/go/types/testdata/check/stmt0.src
+++ b/src/go/types/testdata/check/stmt0.src
@@ -49,18 +49,18 @@
 	b = true
 
 	i += 1
-	i += "foo" /* ERROR "cannot convert.*int" */
+	i /* ERROR "mismatched types int and untyped string" */+= "foo"
 
 	f -= 1
 	f /= 0
 	f = float32(0)/0 /* ERROR "division by zero" */
-	f -= "foo" /* ERROR "cannot convert.*float64" */
+	f /* ERROR "mismatched types float64 and untyped string" */-= "foo"
 
 	c *= 1
 	c /= 0
 
 	s += "bar"
-	s += 1 /* ERROR "cannot convert.*string" */
+	s /* ERROR "mismatched types string and untyped int" */+= 1
 
 	var u64 uint64
 	u64 += 1<<u64
@@ -937,13 +937,13 @@
 // errors reported).
 func issue10148() {
 	for y /* ERROR declared but not used */ := range "" {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int */ + 1
 	}
 	for range 1 /* ERROR cannot range over 1 */ {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int */ + 1
 	}
 	for y := range 1 /* ERROR cannot range over 1 */ {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int */ + 1
 	}
 }
 
diff --git a/src/go/types/testdata/check/tinference.go2 b/src/go/types/testdata/check/tinference.go2
index 31338b3..44e8dc0 100644
--- a/src/go/types/testdata/check/tinference.go2
+++ b/src/go/types/testdata/check/tinference.go2
@@ -11,36 +11,38 @@
 // TODO(rFindley) the below partially applied function types should probably
 //                not be permitted (spec question).
 
-func f0[A any, B interface{type C}, C interface{type D}, D interface{type A}](A, B, C, D)
-func _() {
-	f := f0[string]
-	f("a", "b", "c", "d")
-	f0("a", "b", "c", "d")
-}
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+// func f0[A any, B interface{~C}, C interface{~D}, D interface{~A}](A, B, C, D)
+// func _() {
+// 	f := f0[string]
+// 	f("a", "b", "c", "d")
+// 	f0("a", "b", "c", "d")
+// }
+//
+// func f1[A any, B interface{~A}](A, B)
+// func _() {
+// 	f := f1[int]
+// 	f(int(0), int(0))
+// 	f1(int(0), int(0))
+// }
 
-func f1[A any, B interface{type A}](A, B)
-func _() {
-	f := f1[int]
-	f(int(0), int(0))
-	f1(int(0), int(0))
-}
-
-func f2[A any, B interface{type []A}](A, B)
+func f2[A any, B interface{~[]A}](A, B)
 func _() {
 	f := f2[byte]
 	f(byte(0), []byte{})
 	f2(byte(0), []byte{})
 }
 
-func f3[A any, B interface{type C}, C interface{type *A}](A, B, C)
-func _() {
-	f := f3[int]
-	var x int
-	f(x, &x, &x)
-	f3(x, &x, &x)
-}
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+// func f3[A any, B interface{~C}, C interface{~*A}](A, B, C)
+// func _() {
+// 	f := f3[int]
+// 	var x int
+// 	f(x, &x, &x)
+// 	f3(x, &x, &x)
+// }
 
-func f4[A any, B interface{type []C}, C interface{type *A}](A, B, C)
+func f4[A any, B interface{~[]C}, C interface{~*A}](A, B, C)
 func _() {
 	f := f4[int]
 	var x int
@@ -48,14 +50,14 @@
 	f4(x, []*int{}, &x)
 }
 
-func f5[A interface{type struct{b B; c C}}, B any, C interface{type *B}](x B) A
+func f5[A interface{~struct{b B; c C}}, B any, C interface{~*B}](x B) A
 func _() {
 	x := f5(1.2)
 	var _ float64 = x.b
 	var _ float64 = *x.c
 }
 
-func f6[A any, B interface{type struct{f []A}}](B) A
+func f6[A any, B interface{~struct{f []A}}](B) A
 func _() {
 	x := f6(struct{f []string}{})
 	var _ string = x
@@ -63,11 +65,11 @@
 
 // TODO(gri) Need to flag invalid recursive constraints. At the
 // moment these cause infinite recursions and stack overflow.
-// func f7[A interface{type B}, B interface{type A}]()
+// func f7[A interface{type B}, B interface{~A}]()
 
 // More realistic examples
 
-func Double[S interface{ type []E }, E interface{ type int, int8, int16, int32, int64 }](s S) S {
+func Double[S interface{ ~[]E }, E interface{ ~int | ~int8 | ~int16 | ~int32 | ~int64 }](s S) S {
 	r := make(S, len(s))
 	for i, v := range s {
 		r[i] = v + v
@@ -83,7 +85,7 @@
 
 type Setter[B any] interface {
 	Set(string)
-	type *B
+	~*B
 }
 
 func FromStrings[T interface{}, PT Setter[T]](s []string) []T {
diff --git a/src/go/types/testdata/check/tmp.go2 b/src/go/types/testdata/check/tmp.go2
deleted file mode 100644
index dae78ca..0000000
--- a/src/go/types/testdata/check/tmp.go2
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// This file is meant as "dumping ground" for debugging code.
-
-package p
-
-// fun test case
-type C[P interface{m()}] P
-
-func (r C[P]) m() { r.m() }
-
-func f[T interface{m(); n()}](x T) {
-	y := C[T](x)
-	y.m()
-}
diff --git a/src/go/types/testdata/check/typeinst.go2 b/src/go/types/testdata/check/typeinst.go2
index 3184a4b..069bd3b 100644
--- a/src/go/types/testdata/check/typeinst.go2
+++ b/src/go/types/testdata/check/typeinst.go2
@@ -33,11 +33,11 @@
 var x int
 type _ x /* ERROR not a type */ [int]
 
-type _ int /* ERROR not a generic type */ []
-type _ myInt /* ERROR not a generic type */ []
+type _ int /* ERROR not a generic type */ [] // ERROR expected type argument list
+type _ myInt /* ERROR not a generic type */ [] // ERROR expected type argument list
 
 // TODO(gri) better error messages
-type _ T1 /* ERROR got 0 arguments but 1 type parameters */ []
+type _ T1[] // ERROR expected type argument list
 type _ T1[x /* ERROR not a type */ ]
 type _ T1 /* ERROR got 2 arguments but 1 type parameters */ [int, float32]
 
diff --git a/src/go/types/testdata/check/typeinst2.go2 b/src/go/types/testdata/check/typeinst2.go2
index 6e2104a..ab56cca 100644
--- a/src/go/types/testdata/check/typeinst2.go2
+++ b/src/go/types/testdata/check/typeinst2.go2
@@ -148,15 +148,15 @@
 	p.pm()
 }
 
-// An interface can (explicitly) declare at most one type list.
+// It is ok to have multiple embedded unions.
 type _ interface {
 	m0()
-	type int, string, bool
-	type /* ERROR multiple type lists */ float32, float64
+	~int | ~string | ~bool
+	~float32 | ~float64
 	m1()
 	m2()
-	type /* ERROR multiple type lists */ complex64, complex128
-	type /* ERROR multiple type lists */ rune
+	~complex64 | ~complex128
+	~rune
 }
 
 // Interface type lists may contain each type at most once.
@@ -164,23 +164,24 @@
 // for them to be all in a single list, and we report the error
 // as well.)
 type _ interface {
-	type int, int /* ERROR duplicate type int */
-	type /* ERROR multiple type lists */ int /* ERROR duplicate type int */
+	~int|~ /* ERROR duplicate term int */ int
+	~int|int /* ERROR duplicate term int */
+	int|int /* ERROR duplicate term int */
 }
 
 type _ interface {
-	type struct{f int}, struct{g int}, struct /* ERROR duplicate type */ {f int}
+	~struct{f int} | ~struct{g int} | ~ /* ERROR duplicate term */ struct{f int}
 }
 
 // Interface type lists can contain any type, incl. *Named types.
 // Verify that we use the underlying type to compute the operational type.
 type MyInt int
-func add1[T interface{type MyInt}](x T) T {
+func add1[T interface{MyInt}](x T) T {
 	return x + 1
 }
 
 type MyString string
-func double[T interface{type MyInt, MyString}](x T) T {
+func double[T interface{MyInt|MyString}](x T) T {
 	return x + x
 }
 
@@ -189,15 +190,15 @@
 // type lists.
 
 type E0 interface {
-	type int, bool, string
+	~int | ~bool | ~string
 }
 
 type E1 interface {
-	type int, float64, string
+	~int | ~float64 | ~string
 }
 
 type E2 interface {
-	type float64
+	~float64
 }
 
 type I0 interface {
@@ -246,7 +247,7 @@
 
 type I0_ interface {
 	E0
-	type int
+	~int
 }
 
 func f0_[T I0_]()
diff --git a/src/go/types/testdata/check/typeparams.go2 b/src/go/types/testdata/check/typeparams.go2
index d95e02e..77cd65d 100644
--- a/src/go/types/testdata/check/typeparams.go2
+++ b/src/go/types/testdata/check/typeparams.go2
@@ -6,11 +6,11 @@
 
 // import "io" // for type assertion tests
 
-// The predeclared identifier "any" is only visible as a constraint
+// The predeclared identifier "any" can only be used as a constraint
 // in a type parameter list.
-var _ any // ERROR undeclared
-func _[_ any /* ok here */ , _ interface{any /* ERROR undeclared */ }](any /* ERROR undeclared */ ) {
-        var _ any /* ERROR undeclared */
+var _ any // ERROR cannot use any outside constraint position
+func _[_ any /* ok here */ , _ interface{any /* ERROR constraint */ }](any /* ERROR constraint */ ) {
+        var _ any /* ERROR constraint */
 }
 
 func identity[T any](x T) T { return x }
@@ -52,22 +52,22 @@
 
 type F[A, B any] func(A, B) (B, A)
 
-func min[T interface{ type int }](x, y T) T {
+func min[T interface{ ~int }](x, y T) T {
         if x < y {
                 return x
         }
         return y
 }
 
-func _[T interface{type int, float32}](x, y T) bool { return x < y }
+func _[T interface{~int | ~float32}](x, y T) bool { return x < y }
 func _[T any](x, y T) bool { return x /* ERROR cannot compare */ < y }
-func _[T interface{type int, float32, bool}](x, y T) bool { return x /* ERROR cannot compare */ < y }
+func _[T interface{~int | ~float32 | ~bool}](x, y T) bool { return x /* ERROR cannot compare */ < y }
 
 func _[T C1[T]](x, y T) bool { return x /* ERROR cannot compare */ < y }
 func _[T C2[T]](x, y T) bool { return x < y }
 
 type C1[T any] interface{}
-type C2[T any] interface{ type int, float32 }
+type C2[T any] interface{ ~int | ~float32 }
 
 func new[T any]() *T {
         var x T
@@ -79,11 +79,11 @@
 
 func _[T any](map[T /* ERROR incomparable map key type T \(missing comparable constraint\) */]int) // w/o constraint we don't know if T is comparable
 
-func f1[T1 any](struct{T1}) int
+func f1[T1 any](struct{T1 /* ERROR cannot be a .* type parameter */ }) int
 var _ = f1[int](struct{T1}{})
 type T1 = int
 
-func f2[t1 any](struct{t1; x float32}) int
+func f2[t1 any](struct{t1 /* ERROR cannot be a .* type parameter */ ; x float32}) int
 var _ = f2[t1](struct{t1; x float32}{})
 type t1 = int
 
@@ -95,48 +95,53 @@
 // indexing
 
 func _[T any] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type int }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type string }] (x T, i int) { _ = x[i] }
-func _[T interface{ type []int }] (x T, i int) { _ = x[i] }
-func _[T interface{ type [10]int, *[20]int, map[int]int }] (x T, i int) { _ = x[i] }
-func _[T interface{ type string, []byte }] (x T, i int) { _ = x[i] }
-func _[T interface{ type []int, [1]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
-func _[T interface{ type string, []rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~int }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~string }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[]int }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[10]int | ~*[20]int | ~map[int]int }] (x T, i int) { _ = x /* ERROR cannot index */ [i] } // map and non-map types
+func _[T interface{ ~string | ~[]byte }] (x T, i int) { _ = x[i] }
+func _[T interface{ ~[]int | ~[1]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
+func _[T interface{ ~string | ~[]rune }] (x T, i int) { _ = x /* ERROR "cannot index" */ [i] }
 
-// indexing with various combinations of map types in type lists (see issue #42616)
-func _[T interface{ type []E, map[int]E }, E any](x T, i int) { _ = x[i] }
-func _[T interface{ type []E }, E any](x T, i int) { _ = &x[i] }
-func _[T interface{ type map[int]E }, E any](x T, i int) { _, _ = x[i] } // comma-ok permitted
-func _[T interface{ type []E, map[int]E }, E any](x T, i int) { _ = &x /* ERROR cannot take address */ [i] }
-func _[T interface{ type []E, map[int]E, map[uint]E }, E any](x T, i int) { _ = x /* ERROR cannot index */ [i] } // different map element types
-func _[T interface{ type []E, map[string]E }, E any](x T, i int) { _ = x[i /* ERROR cannot use i */ ] }
+// indexing with various combinations of map types in type sets (see issue #42616)
+func _[T interface{ ~[]E | ~map[int]E }, E any](x T, i int) { _ = x /* ERROR cannot index */ [i] } // map and non-map types
+func _[T interface{ ~[]E }, E any](x T, i int) { _ = &x[i] }
+func _[T interface{ ~map[int]E }, E any](x T, i int) { _, _ = x[i] } // comma-ok permitted
+func _[T interface{ ~map[int]E }, E any](x T, i int) { _ = &x /* ERROR cannot take address */ [i] }
+func _[T interface{ ~map[int]E | ~map[uint]E }, E any](x T, i int) { _ = x /* ERROR cannot index */ [i] } // different map element types
+func _[T interface{ ~[]E | ~map[string]E }, E any](x T, i int) { _ = x /* ERROR cannot index */ [i] } // map and non-map types
+
+// indexing with various combinations of array and other types in type sets
+func _[T interface{ [10]int }](x T, i int) { _ = x[i]; _ = x[9]; _ = x[10 /* ERROR out of bounds */ ] }
+func _[T interface{ [10]byte | string }](x T, i int) { _ = x[i]; _ = x[9]; _ = x[10 /* ERROR out of bounds */ ] }
+func _[T interface{ [10]int | *[20]int | []int }](x T, i int) { _ = x[i]; _ = x[9]; _ = x[10 /* ERROR out of bounds */ ] }
 
 // slicing
 // TODO(gri) implement this
 
-func _[T interface{ type string }] (x T, i, j, k int) { _ = x /* ERROR invalid operation */ [i:j:k] }
+func _[T interface{ ~string }] (x T, i, j, k int) { _ = x /* ERROR generic slice expressions not yet implemented */ [i:j:k] }
 
 // len/cap built-ins
 
 func _[T any](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string, []byte, int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string }](x T) { _ = len(x) }
-func _[T interface{ type [10]int }](x T) { _ = len(x) }
-func _[T interface{ type []byte }](x T) { _ = len(x) }
-func _[T interface{ type map[int]int }](x T) { _ = len(x) }
-func _[T interface{ type chan int }](x T) { _ = len(x) }
-func _[T interface{ type string, []byte, chan int }](x T) { _ = len(x) }
+func _[T interface{ ~int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string | ~[]byte | ~int }](x T) { _ = len(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string }](x T) { _ = len(x) }
+func _[T interface{ ~[10]int }](x T) { _ = len(x) }
+func _[T interface{ ~[]byte }](x T) { _ = len(x) }
+func _[T interface{ ~map[int]int }](x T) { _ = len(x) }
+func _[T interface{ ~chan int }](x T) { _ = len(x) }
+func _[T interface{ ~string | ~[]byte | ~chan int }](x T) { _ = len(x) }
 
 func _[T any](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string, []byte, int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type string }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type [10]int }](x T) { _ = cap(x) }
-func _[T interface{ type []byte }](x T) { _ = cap(x) }
-func _[T interface{ type map[int]int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
-func _[T interface{ type chan int }](x T) { _ = cap(x) }
-func _[T interface{ type []byte, chan int }](x T) { _ = cap(x) }
+func _[T interface{ ~int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string | ~[]byte | ~int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~string }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~[10]int }](x T) { _ = cap(x) }
+func _[T interface{ ~[]byte }](x T) { _ = cap(x) }
+func _[T interface{ ~map[int]int }](x T) { _ = cap(x /* ERROR invalid argument */ ) }
+func _[T interface{ ~chan int }](x T) { _ = cap(x) }
+func _[T interface{ ~[]byte | ~chan int }](x T) { _ = cap(x) }
 
 // range iteration
 
@@ -144,7 +149,7 @@
         for range x /* ERROR cannot range */ {}
 }
 
-func _[T interface{ type string, []string }](x T) {
+func _[T interface{ ~string | ~[]string }](x T) {
         for range x {}
         for i := range x { _ = i }
         for i, _ := range x { _ = i }
@@ -156,23 +161,23 @@
 }
 
 
-func _[T interface{ type string, []rune, map[int]rune }](x T) {
+func _[T interface{ ~string | ~[]rune | ~map[int]rune }](x T) {
         for _, e := range x { _ = e }
         for i, e := range x { _ = i; _ = e }
 }
 
-func _[T interface{ type string, []rune, map[string]rune }](x T) {
+func _[T interface{ ~string | ~[]rune | ~map[string]rune }](x T) {
         for _, e := range x { _ = e }
         for i, e := range x /* ERROR must have the same key type */ { _ = e }
 }
 
-func _[T interface{ type string, chan int }](x T) {
+func _[T interface{ ~string | ~chan int }](x T) {
         for range x {}
         for i := range x { _ = i }
         for i, _ := range x { _ = i } // TODO(gri) should get an error here: channels only return one value
 }
 
-func _[T interface{ type string, chan<-int }](x T) {
+func _[T interface{ ~string | ~chan<-int }](x T) {
         for i := range x /* ERROR send-only channel */ { _ = i }
 }
 
@@ -399,7 +404,7 @@
 	}
 }
 
-func _[T interface{type int}](x T) {
+func _[T interface{~int}](x T) {
 	_ = x /* ERROR not an interface */ .(int)
 	switch x /* ERROR not an interface */ .(type) {
 	}
diff --git a/src/go/types/testdata/examples/constraints.go2 b/src/go/types/testdata/examples/constraints.go2
new file mode 100644
index 0000000..28aa19b
--- /dev/null
+++ b/src/go/types/testdata/examples/constraints.go2
@@ -0,0 +1,60 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file shows some examples of generic constraint interfaces.
+
+package p
+
+type (
+	// Type lists are processed as unions but an error is reported.
+	// TODO(gri) remove this once the parser doesn't accept type lists anymore.
+	_ interface{
+		type /* ERROR use generalized embedding syntax instead of a type list */ int
+	}
+	_ interface{
+		type /* ERROR use generalized embedding syntax instead of a type list */ int
+		type float32
+	}
+)
+
+type (
+	// Arbitrary types may be embedded like interfaces.
+	_ interface{int}
+	_ interface{~int}
+
+	// Types may be combined into a union.
+	_ interface{int|~string}
+
+	// Union terms must be unique independent of whether they are ~ or not.
+	_ interface{int|int /* ERROR duplicate term int */ }
+	_ interface{int|~ /* ERROR duplicate term int */ int }
+	_ interface{~int|~ /* ERROR duplicate term int */ int }
+
+	// For now we do not permit interfaces with methods in unions.
+	_ interface{~ /* ERROR invalid use of ~ */ interface{}}
+	_ interface{int|interface /* ERROR cannot use .* in union */ { m() }}
+)
+
+type (
+	// Tilde is not permitted on defined types or interfaces.
+	foo int
+	bar interface{}
+	_ interface{foo}
+	_ interface{~ /* ERROR invalid use of ~ */ foo }
+	_ interface{~ /* ERROR invalid use of ~ */ bar }
+)
+
+// Multiple embedded union elements are intersected. The order in which they
+// appear in the interface doesn't matter since intersection is a symmetric
+// operation.
+
+type myInt1 int
+type myInt2 int
+
+func _[T interface{ myInt1|myInt2; ~int }]() T { return T(0) }
+func _[T interface{ ~int; myInt1|myInt2 }]() T { return T(0) }
+
+// Here the intersections are empty - there's no type that's in the type set of T.
+func _[T interface{ myInt1|myInt2; int }]() T { return T(0 /* ERROR cannot convert */ ) }
+func _[T interface{ int; myInt1|myInt2 }]() T { return T(0 /* ERROR cannot convert */ ) }
diff --git a/src/go/types/testdata/examples/functions.go2 b/src/go/types/testdata/examples/functions.go2
index a053471..81b9d34 100644
--- a/src/go/types/testdata/examples/functions.go2
+++ b/src/go/types/testdata/examples/functions.go2
@@ -98,7 +98,7 @@
 // Here's an example of a recursive function call with variadic
 // arguments and type inference inferring the type parameter of
 // the caller (i.e., itself).
-func max[T interface{ type int }](x ...T) T {
+func max[T interface{ ~int }](x ...T) T {
 	var x0 T
 	if len(x) > 0 {
 		x0 = x[0]
diff --git a/src/go/types/testdata/examples/inference.go2 b/src/go/types/testdata/examples/inference.go2
index b4f3369..1142e56 100644
--- a/src/go/types/testdata/examples/inference.go2
+++ b/src/go/types/testdata/examples/inference.go2
@@ -7,7 +7,7 @@
 package p
 
 type Ordered interface {
-	type int, float64, string
+	~int|~float64|~string
 }
 
 func min[T Ordered](x, y T) T
@@ -54,7 +54,7 @@
 	mixed[int, string](1.1 /* ERROR cannot use 1.1 */ , "", false)
 }
 
-func related1[Slice interface{type []Elem}, Elem any](s Slice, e Elem)
+func related1[Slice interface{~[]Elem}, Elem any](s Slice, e Elem)
 
 func _() {
 	// related1 can be called with explicit instantiation.
@@ -78,7 +78,7 @@
 	related1(si, "foo" /* ERROR cannot use "foo" */ )
 }
 
-func related2[Elem any, Slice interface{type []Elem}](e Elem, s Slice)
+func related2[Elem any, Slice interface{~[]Elem}](e Elem, s Slice)
 
 func _() {
 	// related2 can be called with explicit instantiation.
diff --git a/src/go/types/testdata/examples/methods.go2 b/src/go/types/testdata/examples/methods.go2
index 76c6539..4e87041 100644
--- a/src/go/types/testdata/examples/methods.go2
+++ b/src/go/types/testdata/examples/methods.go2
@@ -6,6 +6,8 @@
 
 package p
 
+import "unsafe"
+
 // Parameterized types may have methods.
 type T1[A any] struct{ a A }
 
@@ -94,3 +96,18 @@
 type T0 struct{}
 func (T0) _() {}
 func (T1[A]) _() {}
+
+// A generic receiver type may constrain its type parameter such
+// that it must be a pointer type. Such receiver types are not
+// permitted.
+type T3a[P interface{ ~int | ~string | ~float64 }] P
+
+func (T3a[_]) m() {} // this is ok
+
+type T3b[P interface{ ~unsafe.Pointer }] P
+
+func (T3b /* ERROR invalid receiver */ [_]) m() {}
+
+type T3c[P interface{ *int | *string }] P
+
+func (T3c /* ERROR invalid receiver */ [_]) m() {}
diff --git a/src/go/types/testdata/examples/operations.go2 b/src/go/types/testdata/examples/operations.go2
new file mode 100644
index 0000000..18e4d60
--- /dev/null
+++ b/src/go/types/testdata/examples/operations.go2
@@ -0,0 +1,29 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// indirection
+
+func _[P any](p P) {
+        _ = *p // ERROR cannot indirect p
+}
+
+func _[P interface{ int }](p P) {
+        _ = *p // ERROR cannot indirect p
+}
+
+func _[P interface{ *int }](p P) {
+        _ = *p
+}
+
+func _[P interface{ *int | *string }](p P) {
+        _ = *p // ERROR must have identical base types
+}
+
+type intPtr *int
+
+func _[P interface{ *int | intPtr } ](p P) {
+        var _ int = *p
+}
diff --git a/src/go/types/testdata/examples/types.go2 b/src/go/types/testdata/examples/types.go2
index 59c8804..a7544f7 100644
--- a/src/go/types/testdata/examples/types.go2
+++ b/src/go/types/testdata/examples/types.go2
@@ -161,30 +161,40 @@
 	* /* ERROR List redeclared */ List[int]
 }
 
+// Issue #45639: We don't allow this anymore. Keep this code
+//               in case we decide to revisit this decision.
+//
 // It's possible to declare local types whose underlying types
 // are type parameters. As with ordinary type definitions, the
 // types underlying properties are "inherited" but the methods
 // are not.
-func _[T interface{ m(); type int }]() {
-	type L T
-	var x L
+//func _[T interface{ m(); ~int }]() {
+//	type L T
+//	var x L
+//
+//	// m is not defined on L (it is not "inherited" from
+//	// its underlying type).
+//	x.m /* ERROR x.m undefined */ ()
+//
+//	// But the properties of T, such that as that it supports
+//	// the operations of the types given by its type bound,
+//	// are also the properties of L.
+//	x++
+//	_ = x - x
+//
+//	// On the other hand, if we define a local alias for T,
+//	// that alias stands for T as expected.
+//	type A = T
+//	var y A
+//	y.m()
+//	_ = y < 0
+//}
 
-	// m is not defined on L (it is not "inherited" from
-	// its underlying type).
-	x.m /* ERROR x.m undefined */ ()
-
-	// But the properties of T, such that as that it supports
-	// the operations of the types given by its type bound,
-	// are also the properties of L.
-	x++
-	_ = x - x
-
-	// On the other hand, if we define a local alias for T,
-	// that alias stands for T as expected.
-	type A = T
-	var y A
-	y.m()
-	_ = y < 0
+// It is not permitted to declare a local type whose underlying
+// type is a type parameters not declared by that type declaration.
+func _[T any]() {
+	type _ T         // ERROR cannot use function type parameter T as RHS in type declaration
+	type _ [_ any] T // ERROR cannot use function type parameter T as RHS in type declaration
 }
 
 // As a special case, an explicit type argument may be omitted
@@ -238,11 +248,11 @@
 // The type of variables (incl. parameters and return values) cannot
 // be an interface with type constraints or be/embed comparable.
 type I interface {
-	type int
+	~int
 }
 
 var (
-	_ interface /* ERROR contains type constraints */ {type int}
+	_ interface /* ERROR contains type constraints */ {~int}
 	_ I /* ERROR contains type constraints */
 )
 
@@ -273,7 +283,7 @@
 // (If a type list contains just a single const type, we could
 // allow it, but such type lists don't make much sense in the
 // first place.)
-func _[T interface { type int, float64 }]() {
+func _[T interface {~int|~float64}]() {
 	// not valid
 	const _ = T /* ERROR not constant */ (0)
 	const _ T /* ERROR invalid constant type T */ = 1
diff --git a/src/go/types/testdata/fixedbugs/issue28251.src b/src/go/types/testdata/fixedbugs/issue28251.src
index cd79e0e..ef5e61d 100644
--- a/src/go/types/testdata/fixedbugs/issue28251.src
+++ b/src/go/types/testdata/fixedbugs/issue28251.src
@@ -60,6 +60,6 @@
         T11 = T
 )
 
-func (T9 /* ERROR invalid receiver \*\*T */ ) m9() {}
+func (T9 /* ERROR invalid receiver type \*\*T */ ) m9() {}
 func _() { (T{}).m9 /* ERROR has no field or method m9 */ () }
 func _() { (&T{}).m9 /* ERROR has no field or method m9 */ () }
diff --git a/src/go/types/testdata/fixedbugs/issue39634.go2 b/src/go/types/testdata/fixedbugs/issue39634.go2
index a13ed13..aec404e 100644
--- a/src/go/types/testdata/fixedbugs/issue39634.go2
+++ b/src/go/types/testdata/fixedbugs/issue39634.go2
@@ -31,13 +31,14 @@
 func main7() { var _ foo7 = x7[int]{} }
 
 // crash 8
-type foo8[A any] interface { type A }
-func bar8[A foo8[A]](a A) {}
-func main8() {}
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+// type foo8[A any] interface { ~A }
+// func bar8[A foo8[A]](a A) {}
+// func main8() {}
 
 // crash 9
-type foo9[A any] interface { type foo9 /* ERROR interface contains type constraints */ [A] }
-func _() { var _ = new(foo9 /* ERROR interface contains type constraints */ [int]) }
+type foo9[A any] interface { foo9 /* ERROR illegal cycle */ [A] }
+func _() { var _ = new(foo9 /* ERROR illegal cycle */ [int]) }
 
 // crash 12
 var u /* ERROR cycle */ , i [func /* ERROR used as value */ /* ERROR used as value */ (u, c /* ERROR undeclared */ /* ERROR undeclared */ ) {}(0, len /* ERROR must be called */ /* ERROR must be called */ )]c /* ERROR undeclared */ /* ERROR undeclared */
diff --git a/src/go/types/testdata/fixedbugs/issue39680.go2 b/src/go/types/testdata/fixedbugs/issue39680.go2
index 9bc26f3..e56bc35 100644
--- a/src/go/types/testdata/fixedbugs/issue39680.go2
+++ b/src/go/types/testdata/fixedbugs/issue39680.go2
@@ -4,16 +4,19 @@
 
 package p
 
+// Embedding stand-alone type parameters is not permitted for now. Disabled.
+
+/*
 import "fmt"
 
 // Minimal test case.
-func _[T interface{type T}](x T) T{
+func _[T interface{~T}](x T) T{
 	return x
 }
 
 // Test case from issue.
 type constr[T any] interface {
-	type T
+	~T
 }
 
 func Print[T constr[T]](s []T) {
@@ -25,3 +28,4 @@
 func f() {
 	Print([]string{"Hello, ", "playground\n"})
 }
+*/
diff --git a/src/go/types/testdata/fixedbugs/issue39693.go2 b/src/go/types/testdata/fixedbugs/issue39693.go2
index 316ab19..ec76419 100644
--- a/src/go/types/testdata/fixedbugs/issue39693.go2
+++ b/src/go/types/testdata/fixedbugs/issue39693.go2
@@ -4,11 +4,20 @@
 
 package p
 
-type Number interface {
-	int     /* ERROR int is not an interface */
-	float64 /* ERROR float64 is not an interface */
+type Number1 interface {
+	// embedding non-interface types is permitted
+	int
+	float64
 }
 
-func Add[T Number](a, b T) T {
+func Add[T Number1](a, b T) T {
 	return a /* ERROR not defined */ + b
 }
+
+type Number2 interface {
+	int|float64
+}
+
+func Add2[T Number2](a, b T) T {
+	return a + b
+}
diff --git a/src/go/types/testdata/fixedbugs/issue39699.go2 b/src/go/types/testdata/fixedbugs/issue39699.go2
index 75491e7..72f8399 100644
--- a/src/go/types/testdata/fixedbugs/issue39699.go2
+++ b/src/go/types/testdata/fixedbugs/issue39699.go2
@@ -8,7 +8,7 @@
 }
 
 type T1 interface{
-	type int
+	~int
 }
 
 type T2 interface{
diff --git a/src/go/types/testdata/fixedbugs/issue39711.go2 b/src/go/types/testdata/fixedbugs/issue39711.go2
index df621a4..cf1f905 100644
--- a/src/go/types/testdata/fixedbugs/issue39711.go2
+++ b/src/go/types/testdata/fixedbugs/issue39711.go2
@@ -7,5 +7,7 @@
 // Do not report a duplicate type error for this type list.
 // (Check types after interfaces have been completed.)
 type _ interface {
-	type interface{ Error() string }, interface{ String() string }
+	// TODO(rfindley) Once we have full type sets we can enable this again.
+	// Fow now we don't permit interfaces in type lists.
+	// type interface{ Error() string }, interface{ String() string }
 }
diff --git a/src/go/types/testdata/fixedbugs/issue39723.go2 b/src/go/types/testdata/fixedbugs/issue39723.go2
index 55464e6..367b3f1 100644
--- a/src/go/types/testdata/fixedbugs/issue39723.go2
+++ b/src/go/types/testdata/fixedbugs/issue39723.go2
@@ -6,4 +6,4 @@
 
 // A constraint must be an interface; it cannot
 // be a type parameter, for instance.
-func _[A interface{ type interface{} }, B A /* ERROR not an interface */ ]()
+func _[A interface{ ~int }, B A /* ERROR not an interface */ ]()
diff --git a/src/go/types/testdata/fixedbugs/issue39755.go2 b/src/go/types/testdata/fixedbugs/issue39755.go2
index b7ab688..257b73a 100644
--- a/src/go/types/testdata/fixedbugs/issue39755.go2
+++ b/src/go/types/testdata/fixedbugs/issue39755.go2
@@ -4,14 +4,14 @@
 
 package p
 
-func _[T interface{type map[string]int}](x T) {
+func _[T interface{~map[string]int}](x T) {
 	_ = x == nil
 }
 
 // simplified test case from issue
 
 type PathParamsConstraint interface {
-        type map[string]string, []struct{key, value string}
+        ~map[string]string | ~[]struct{key, value string}
 }
 
 type PathParams[T PathParamsConstraint] struct {
diff --git a/src/go/types/testdata/fixedbugs/issue39938.go2 b/src/go/types/testdata/fixedbugs/issue39938.go2
index 76e7e36..0da6e10 100644
--- a/src/go/types/testdata/fixedbugs/issue39938.go2
+++ b/src/go/types/testdata/fixedbugs/issue39938.go2
@@ -8,8 +8,8 @@
 
 type E0[P any] P
 type E1[P any] *P
-type E2[P any] struct{ P }
-type E3[P any] struct{ *P }
+type E2[P any] struct{ _ P }
+type E3[P any] struct{ _ *P }
 
 type T0 /* ERROR illegal cycle */ struct {
         _ E0[T0]
diff --git a/src/go/types/testdata/fixedbugs/issue39948.go2 b/src/go/types/testdata/fixedbugs/issue39948.go2
index c2b4609..e38e572 100644
--- a/src/go/types/testdata/fixedbugs/issue39948.go2
+++ b/src/go/types/testdata/fixedbugs/issue39948.go2
@@ -5,5 +5,5 @@
 package p
 
 type T[P any] interface{
-	P // ERROR P is a type parameter, not an interface
+	P // ERROR cannot embed a type parameter
 }
diff --git a/src/go/types/testdata/fixedbugs/issue40301.go2 b/src/go/types/testdata/fixedbugs/issue40301.go2
index 5d97855..c78f9a1 100644
--- a/src/go/types/testdata/fixedbugs/issue40301.go2
+++ b/src/go/types/testdata/fixedbugs/issue40301.go2
@@ -7,6 +7,6 @@
 import "unsafe"
 
 func _[T any](x T) {
-	_ = unsafe /* ERROR undefined */ .Alignof(x)
-	_ = unsafe /* ERROR undefined */ .Sizeof(x)
+	_ = unsafe.Alignof(x)
+	_ = unsafe.Sizeof(x)
 }
diff --git a/src/go/types/testdata/fixedbugs/issue40789.go2 b/src/go/types/testdata/fixedbugs/issue40789.go2
new file mode 100644
index 0000000..9eea4ad
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue40789.go2
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+func main() {
+	m := map[string]int{
+		"a": 6,
+		"b": 7,
+	}
+	fmt.Println(copyMap[map[string]int, string, int](m))
+}
+
+type Map[K comparable, V any] interface {
+	map[K] V
+}
+
+func copyMap[M Map[K, V], K comparable, V any](m M) M {
+	m1 := make(M)
+	for k, v := range m {
+		m1[k] = v
+	}
+	return m1
+}
+
+// simpler test case from the same issue
+
+type A[X comparable] interface {
+	[]X
+}
+
+func f[B A[X], X comparable]() B {
+	return nil
+}
diff --git a/src/go/types/testdata/fixedbugs/issue41124.go2 b/src/go/types/testdata/fixedbugs/issue41124.go2
index 61f766b..ab53504 100644
--- a/src/go/types/testdata/fixedbugs/issue41124.go2
+++ b/src/go/types/testdata/fixedbugs/issue41124.go2
@@ -7,7 +7,7 @@
 // Test case from issue.
 
 type Nat interface {
-	type Zero, Succ
+	Zero|Succ
 }
 
 type Zero struct{}
@@ -22,7 +22,7 @@
 }
 
 type I2 interface {
-	type int
+	~int
 }
 
 type I3 interface {
diff --git a/src/go/types/testdata/fixedbugs/issue42758.go2 b/src/go/types/testdata/fixedbugs/issue42758.go2
index 698cb8a..bf0031f 100644
--- a/src/go/types/testdata/fixedbugs/issue42758.go2
+++ b/src/go/types/testdata/fixedbugs/issue42758.go2
@@ -17,7 +17,7 @@
 }
 
 type constraint interface {
-	type int
+	~int
 }
 
 func _[T constraint](x interface{}){
diff --git a/src/go/types/testdata/fixedbugs/issue43671.go2 b/src/go/types/testdata/fixedbugs/issue43671.go2
new file mode 100644
index 0000000..6cc3801
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue43671.go2
@@ -0,0 +1,58 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | <-chan T }
+
+func _[T any](ch T) {
+	<-ch // ERROR cannot receive from non-channel
+}
+
+func _[T C0](ch T) {
+	<-ch // ERROR cannot receive from non-channel
+}
+
+func _[T C1](ch T) {
+	<-ch
+}
+
+func _[T C2](ch T) {
+	<-ch
+}
+
+func _[T C3](ch T) {
+	<-ch // ERROR channels of ch .* must have the same element type
+}
+
+func _[T C4](ch T) {
+	<-ch // ERROR cannot receive from send-only channel
+}
+
+func _[T C5[X], X any](ch T, x X) {
+	x = <-ch
+}
+
+// test case from issue, slightly modified
+type RecvChan[T any] interface {
+	~chan T | ~<-chan T
+}
+
+func _[T any, C RecvChan[T]](ch C) T {
+	return <-ch
+}
+
+func f[T any, C interface{ chan T }](ch C) T {
+	return <-ch
+}
+
+func _(ch chan int) {
+	var x int = f(ch) // test constraint type inference for this case
+	_ = x
+}
diff --git a/src/go/types/testdata/fixedbugs/issue45548.go2 b/src/go/types/testdata/fixedbugs/issue45548.go2
index b1e4249..b8ba0ad 100644
--- a/src/go/types/testdata/fixedbugs/issue45548.go2
+++ b/src/go/types/testdata/fixedbugs/issue45548.go2
@@ -4,7 +4,7 @@
 
 package p
 
-func f[F interface{type *Q}, G interface{type *R}, Q, R any](q Q, r R) {}
+func f[F interface{~*Q}, G interface{~*R}, Q, R any](q Q, r R) {}
 
 func _() {
 	f[*float64, *int](1, 2)
diff --git a/src/go/types/testdata/fixedbugs/issue45635.go2 b/src/go/types/testdata/fixedbugs/issue45635.go2
index 3e2ccec..fc50797 100644
--- a/src/go/types/testdata/fixedbugs/issue45635.go2
+++ b/src/go/types/testdata/fixedbugs/issue45635.go2
@@ -10,10 +10,10 @@
 
 type N[T any] struct{}
 
-var _ N /* ERROR "0 arguments but 1 type parameters" */ []
+var _ N [] // ERROR expected type argument list
 
 type I interface {
-	type map[int]int, []int
+	~[]int
 }
 
 func _[T I](i, j int) {
@@ -27,6 +27,5 @@
 	_ = s[i, j /* ERROR "more than one index" */ ]
 
 	var t T
-	// TODO(rFindley) Fix the duplicate error below.
-	_ = t[i, j /* ERROR "more than one index" */ /* ERROR "more than one index" */ ]
+	_ = t[i, j /* ERROR "more than one index" */ ]
 }
diff --git a/src/go/types/testdata/fixedbugs/issue45639.go2 b/src/go/types/testdata/fixedbugs/issue45639.go2
new file mode 100644
index 0000000..441fb4c
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue45639.go2
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package P
+
+// It is not permitted to declare a local type whose underlying
+// type is a type parameters not declared by that type declaration.
+func _[T any]() {
+	type _ T         // ERROR cannot use function type parameter T as RHS in type declaration
+	type _ [_ any] T // ERROR cannot use function type parameter T as RHS in type declaration
+}
diff --git a/src/go/types/testdata/fixedbugs/issue45985.go2 b/src/go/types/testdata/fixedbugs/issue45985.go2
index 550b9c6..6e42dbb 100644
--- a/src/go/types/testdata/fixedbugs/issue45985.go2
+++ b/src/go/types/testdata/fixedbugs/issue45985.go2
@@ -5,7 +5,7 @@
 package issue45985
 
 // TODO(rFindley): this error should be on app[int] below.
-func app[S /* ERROR "type S = S does not match" */ interface{ type []T }, T any](s S, e T) S {
+func app[S /* ERROR "type S = S does not match" */ interface{ ~[]T }, T any](s S, e T) S {
     return append(s, e)
 }
 
diff --git a/src/go/types/testdata/fixedbugs/issue46090.go2 b/src/go/types/testdata/fixedbugs/issue46090.go2
new file mode 100644
index 0000000..81b3197
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue46090.go2
@@ -0,0 +1,9 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The predeclared type comparable is not visible before Go 1.18.
+
+package go1_17
+
+type _ comparable // ERROR undeclared
diff --git a/src/go/types/testdata/fixedbugs/issue46275.go2 b/src/go/types/testdata/fixedbugs/issue46275.go2
new file mode 100644
index 0000000..0ebde31
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue46275.go2
@@ -0,0 +1,27 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package issue46275
+
+type N[T any] struct {
+        *N[T]
+        t T
+}
+
+func (n *N[T]) Elem() T {
+        return n.t
+}
+
+type I interface {
+        Elem() string
+}
+
+func _() {
+        var n1 *N[string]
+        var _ I = n1
+        type NS N[string]
+        var n2 *NS
+        var _ I = n2
+}
+
diff --git a/src/go/types/testdata/fixedbugs/issue47031.go2 b/src/go/types/testdata/fixedbugs/issue47031.go2
new file mode 100644
index 0000000..b184f9b
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47031.go2
@@ -0,0 +1,20 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type Mer interface { M() }
+
+func F[T Mer](p *T) {
+	p.M /* ERROR p\.M undefined */ ()
+}
+
+type MyMer int
+
+func (MyMer) M() {}
+
+func _() {
+	F(new(MyMer))
+	F[Mer](nil)
+}
diff --git a/src/go/types/testdata/fixedbugs/issue47115.go2 b/src/go/types/testdata/fixedbugs/issue47115.go2
new file mode 100644
index 0000000..6694219
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47115.go2
@@ -0,0 +1,40 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+	ch <- /* ERROR cannot send to non-channel */ 0
+}
+
+func _[T C0](ch T) {
+	ch <- /* ERROR cannot send to non-channel */ 0
+}
+
+func _[T C1](ch T) {
+	ch <- 0
+}
+
+func _[T C2](ch T) {
+	ch  <-/* ERROR cannot send to receive-only channel */ 0
+}
+
+func _[T C3](ch T) {
+	ch <- /* ERROR channels of ch .* must have the same element type */ 0
+}
+
+func _[T C4](ch T) {
+	ch <- 0
+}
+
+func _[T C5[X], X any](ch T, x X) {
+	ch <- x
+}
diff --git a/src/go/types/testdata/fixedbugs/issue47127.go2 b/src/go/types/testdata/fixedbugs/issue47127.go2
new file mode 100644
index 0000000..387c946
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47127.go2
@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Embedding of stand-alone type parameters is not permitted.
+
+package p
+
+type (
+        _[P any] interface{ *P | []P | chan P | map[string]P }
+        _[P any] interface{ P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+        _[P any] interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+)
+
+func _[P any]() {
+        type (
+                _[P any] interface{ *P | []P | chan P | map[string]P }
+                _[P any] interface{ P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+                _[P any] interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+
+                _ interface{ *P | []P | chan P | map[string]P }
+                _ interface{ P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ ~P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ int | P /* ERROR "cannot embed a type parameter" */ }
+                _ interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }
+        )
+}
+
+func _[P any, Q interface{ *P | []P | chan P | map[string]P }]()
+func _[P any, Q interface{ P /* ERROR "cannot embed a type parameter" */ }]()
+func _[P any, Q interface{ ~P /* ERROR "cannot embed a type parameter" */ }]()
+func _[P any, Q interface{ int | P /* ERROR "cannot embed a type parameter" */ }]()
+func _[P any, Q interface{ int | ~P /* ERROR "cannot embed a type parameter" */ }]()
diff --git a/src/go/types/testdata/fixedbugs/issue47411.go2 b/src/go/types/testdata/fixedbugs/issue47411.go2
new file mode 100644
index 0000000..7326205
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue47411.go2
@@ -0,0 +1,26 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f[_ comparable]()
+func g[_ interface{interface{comparable; ~int|~string}}]()
+
+func _[P comparable,
+        Q interface{ comparable; ~int|~string },
+        R any,                               // not comparable
+        S interface{ comparable; ~func() },  // not comparable
+]() {
+        _ = f[int]
+        _ = f[P]
+        _ = f[Q]
+        _ = f[func /* ERROR does not satisfy comparable */ ()]
+        _ = f[R /* ERROR R has no constraints */ ]
+
+        _ = g[int]
+        _ = g[P /* ERROR P has no type constraints */ ]
+        _ = g[Q]
+        _ = g[func /* ERROR does not satisfy comparable */()]
+        _ = g[R /* ERROR R has no constraints */ ]
+}
diff --git a/src/go/types/testdata/manual.go2 b/src/go/types/testdata/manual.go2
new file mode 100644
index 0000000..25e6f22
--- /dev/null
+++ b/src/go/types/testdata/manual.go2
@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file is tested when running "go test -run Manual"
+// without source arguments. Use for one-off debugging.
+
+package p
+
diff --git a/src/go/types/tuple.go b/src/go/types/tuple.go
new file mode 100644
index 0000000..16d28bc
--- /dev/null
+++ b/src/go/types/tuple.go
@@ -0,0 +1,36 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
+// Tuples are used as components of signatures and to represent the type of multiple
+// assignments; they are not first class types of Go.
+type Tuple struct {
+	vars []*Var
+}
+
+// NewTuple returns a new tuple for the given variables.
+func NewTuple(x ...*Var) *Tuple {
+	if len(x) > 0 {
+		return &Tuple{vars: x}
+	}
+	// TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer;
+	//           it's too subtle and causes problems.
+	return nil
+}
+
+// Len returns the number variables of tuple t.
+func (t *Tuple) Len() int {
+	if t != nil {
+		return len(t.vars)
+	}
+	return 0
+}
+
+// At returns the i'th variable of tuple t.
+func (t *Tuple) At(i int) *Var { return t.vars[i] }
+
+func (t *Tuple) Underlying() Type { return t }
+func (t *Tuple) String() string   { return TypeString(t, nil) }
diff --git a/src/go/types/type.go b/src/go/types/type.go
index 2660ce4..5819dd2 100644
--- a/src/go/types/type.go
+++ b/src/go/types/type.go
@@ -4,12 +4,6 @@
 
 package types
 
-import (
-	"fmt"
-	"go/token"
-	"sync/atomic"
-)
-
 // A Type represents a type of Go.
 // All types implement the Type interface.
 type Type interface {
@@ -22,753 +16,31 @@
 	String() string
 }
 
-// BasicKind describes the kind of basic type.
-type BasicKind int
+// top represents the top of the type lattice.
+// It is the underlying type of a type parameter that
+// can be satisfied by any type (ignoring methods),
+// because its type constraint contains no restrictions
+// besides methods.
+type top struct{}
 
-const (
-	Invalid BasicKind = iota // type is invalid
+// theTop is the singleton top type.
+var theTop = &top{}
 
-	// predeclared types
-	Bool
-	Int
-	Int8
-	Int16
-	Int32
-	Int64
-	Uint
-	Uint8
-	Uint16
-	Uint32
-	Uint64
-	Uintptr
-	Float32
-	Float64
-	Complex64
-	Complex128
-	String
-	UnsafePointer
+func (t *top) Underlying() Type { return t }
+func (t *top) String() string   { return TypeString(t, nil) }
 
-	// types for untyped values
-	UntypedBool
-	UntypedInt
-	UntypedRune
-	UntypedFloat
-	UntypedComplex
-	UntypedString
-	UntypedNil
-
-	// aliases
-	Byte = Uint8
-	Rune = Int32
-)
-
-// BasicInfo is a set of flags describing properties of a basic type.
-type BasicInfo int
-
-// Properties of basic types.
-const (
-	IsBoolean BasicInfo = 1 << iota
-	IsInteger
-	IsUnsigned
-	IsFloat
-	IsComplex
-	IsString
-	IsUntyped
-
-	IsOrdered   = IsInteger | IsFloat | IsString
-	IsNumeric   = IsInteger | IsFloat | IsComplex
-	IsConstType = IsBoolean | IsNumeric | IsString
-)
-
-// A Basic represents a basic type.
-type Basic struct {
-	kind BasicKind
-	info BasicInfo
-	name string
-}
-
-// Kind returns the kind of basic type b.
-func (b *Basic) Kind() BasicKind { return b.kind }
-
-// Info returns information about properties of basic type b.
-func (b *Basic) Info() BasicInfo { return b.info }
-
-// Name returns the name of basic type b.
-func (b *Basic) Name() string { return b.name }
-
-// An Array represents an array type.
-type Array struct {
-	len  int64
-	elem Type
-}
-
-// NewArray returns a new array type for the given element type and length.
-// A negative length indicates an unknown length.
-func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} }
-
-// Len returns the length of array a.
-// A negative result indicates an unknown length.
-func (a *Array) Len() int64 { return a.len }
-
-// Elem returns element type of array a.
-func (a *Array) Elem() Type { return a.elem }
-
-// A Slice represents a slice type.
-type Slice struct {
-	elem Type
-}
-
-// NewSlice returns a new slice type for the given element type.
-func NewSlice(elem Type) *Slice { return &Slice{elem: elem} }
-
-// Elem returns the element type of slice s.
-func (s *Slice) Elem() Type { return s.elem }
-
-// A Struct represents a struct type.
-type Struct struct {
-	fields []*Var
-	tags   []string // field tags; nil if there are no tags
-}
-
-// NewStruct returns a new struct with the given fields and corresponding field tags.
-// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
-// only as long as required to hold the tag with the largest index i. Consequently,
-// if no field has a tag, tags may be nil.
-func NewStruct(fields []*Var, tags []string) *Struct {
-	var fset objset
-	for _, f := range fields {
-		if f.name != "_" && fset.insert(f) != nil {
-			panic("multiple fields with the same name")
-		}
+// under returns the true expanded underlying type.
+// If it doesn't exist, the result is Typ[Invalid].
+// under must only be called when a type is known
+// to be fully set up.
+func under(t Type) Type {
+	// TODO(gri) is this correct for *Union?
+	if n := asNamed(t); n != nil {
+		return n.under()
 	}
-	if len(tags) > len(fields) {
-		panic("more tags than fields")
-	}
-	return &Struct{fields: fields, tags: tags}
-}
-
-// NumFields returns the number of fields in the struct (including blank and embedded fields).
-func (s *Struct) NumFields() int { return len(s.fields) }
-
-// Field returns the i'th field for 0 <= i < NumFields().
-func (s *Struct) Field(i int) *Var { return s.fields[i] }
-
-// Tag returns the i'th field tag for 0 <= i < NumFields().
-func (s *Struct) Tag(i int) string {
-	if i < len(s.tags) {
-		return s.tags[i]
-	}
-	return ""
-}
-
-// A Pointer represents a pointer type.
-type Pointer struct {
-	base Type // element type
-}
-
-// NewPointer returns a new pointer type for the given element (base) type.
-func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
-
-// Elem returns the element type for the given pointer p.
-func (p *Pointer) Elem() Type { return p.base }
-
-// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
-// Tuples are used as components of signatures and to represent the type of multiple
-// assignments; they are not first class types of Go.
-type Tuple struct {
-	vars []*Var
-}
-
-// NewTuple returns a new tuple for the given variables.
-func NewTuple(x ...*Var) *Tuple {
-	if len(x) > 0 {
-		return &Tuple{vars: x}
-	}
-	// TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer;
-	//           it's too subtle and causes problems.
-	return nil
-}
-
-// Len returns the number variables of tuple t.
-func (t *Tuple) Len() int {
-	if t != nil {
-		return len(t.vars)
-	}
-	return 0
-}
-
-// At returns the i'th variable of tuple t.
-func (t *Tuple) At(i int) *Var { return t.vars[i] }
-
-// A Signature represents a (non-builtin) function or method type.
-// The receiver is ignored when comparing signatures for identity.
-type Signature struct {
-	// We need to keep the scope in Signature (rather than passing it around
-	// and store it in the Func Object) because when type-checking a function
-	// literal we call the general type checker which returns a general Type.
-	// We then unpack the *Signature and use the scope for the literal body.
-	rparams  []*TypeName // receiver type parameters from left to right, or nil
-	tparams  []*TypeName // type parameters from left to right, or nil
-	scope    *Scope      // function scope, present for package-local signatures
-	recv     *Var        // nil if not a method
-	params   *Tuple      // (incoming) parameters from left to right; or nil
-	results  *Tuple      // (outgoing) results from left to right; or nil
-	variadic bool        // true if the last parameter's type is of the form ...T (or string, for append built-in only)
-}
-
-// NewSignature returns a new function type for the given receiver, parameters,
-// and results, either of which may be nil. If variadic is set, the function
-// is variadic, it must have at least one parameter, and the last parameter
-// must be of unnamed slice type.
-func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
-	if variadic {
-		n := params.Len()
-		if n == 0 {
-			panic("types.NewSignature: variadic function must have at least one parameter")
-		}
-		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
-			panic("types.NewSignature: variadic parameter must be of unnamed slice type")
-		}
-	}
-	return &Signature{recv: recv, params: params, results: results, variadic: variadic}
-}
-
-// Recv returns the receiver of signature s (if a method), or nil if a
-// function. It is ignored when comparing signatures for identity.
-//
-// For an abstract method, Recv returns the enclosing interface either
-// as a *Named or an *Interface. Due to embedding, an interface may
-// contain methods whose receiver type is a different interface.
-func (s *Signature) Recv() *Var { return s.recv }
-
-// _TParams returns the type parameters of signature s, or nil.
-func (s *Signature) _TParams() []*TypeName { return s.tparams }
-
-// _SetTParams sets the type parameters of signature s.
-func (s *Signature) _SetTParams(tparams []*TypeName) { s.tparams = tparams }
-
-// Params returns the parameters of signature s, or nil.
-func (s *Signature) Params() *Tuple { return s.params }
-
-// Results returns the results of signature s, or nil.
-func (s *Signature) Results() *Tuple { return s.results }
-
-// Variadic reports whether the signature s is variadic.
-func (s *Signature) Variadic() bool { return s.variadic }
-
-// A _Sum represents a set of possible types.
-// Sums are currently used to represent type lists of interfaces
-// and thus the underlying types of type parameters; they are not
-// first class types of Go.
-type _Sum struct {
-	types []Type // types are unique
-}
-
-// _NewSum returns a new Sum type consisting of the provided
-// types if there are more than one. If there is exactly one
-// type, it returns that type. If the list of types is empty
-// the result is nil.
-func _NewSum(types []Type) Type {
-	if len(types) == 0 {
-		return nil
-	}
-
-	// What should happen if types contains a sum type?
-	// Do we flatten the types list? For now we check
-	// and panic. This should not be possible for the
-	// current use case of type lists.
-	// TODO(gri) Come up with the rules for sum types.
-	for _, t := range types {
-		if _, ok := t.(*_Sum); ok {
-			panic("sum type contains sum type - unimplemented")
-		}
-	}
-
-	if len(types) == 1 {
-		return types[0]
-	}
-	return &_Sum{types: types}
-}
-
-// is reports whether all types in t satisfy pred.
-func (s *_Sum) is(pred func(Type) bool) bool {
-	if s == nil {
-		return false
-	}
-	for _, t := range s.types {
-		if !pred(t) {
-			return false
-		}
-	}
-	return true
-}
-
-// An Interface represents an interface type.
-type Interface struct {
-	methods   []*Func // ordered list of explicitly declared methods
-	types     Type    // (possibly a Sum) type declared with a type list (TODO(gri) need better field name)
-	embeddeds []Type  // ordered list of explicitly embedded types
-
-	allMethods []*Func // ordered list of methods declared with or embedded in this interface (TODO(gri): replace with mset)
-	allTypes   Type    // intersection of all embedded and locally declared types  (TODO(gri) need better field name)
-
-	obj Object // type declaration defining this interface; or nil (for better error messages)
-}
-
-// unpack unpacks a type into a list of types.
-// TODO(gri) Try to eliminate the need for this function.
-func unpackType(typ Type) []Type {
-	if typ == nil {
-		return nil
-	}
-	if sum := asSum(typ); sum != nil {
-		return sum.types
-	}
-	return []Type{typ}
-}
-
-// is reports whether interface t represents types that all satisfy pred.
-func (t *Interface) is(pred func(Type) bool) bool {
-	if t.allTypes == nil {
-		return false // we must have at least one type! (was bug)
-	}
-	for _, t := range unpackType(t.allTypes) {
-		if !pred(t) {
-			return false
-		}
-	}
-	return true
-}
-
-// emptyInterface represents the empty (completed) interface
-var emptyInterface = Interface{allMethods: markComplete}
-
-// markComplete is used to mark an empty interface as completely
-// set up by setting the allMethods field to a non-nil empty slice.
-var markComplete = make([]*Func, 0)
-
-// NewInterface returns a new (incomplete) interface for the given methods and embedded types.
-// Each embedded type must have an underlying type of interface type.
-// NewInterface takes ownership of the provided methods and may modify their types by setting
-// missing receivers. To compute the method set of the interface, Complete must be called.
-//
-// Deprecated: Use NewInterfaceType instead which allows any (even non-defined) interface types
-// to be embedded. This is necessary for interfaces that embed alias type names referring to
-// non-defined (literal) interface types.
-func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
-	tnames := make([]Type, len(embeddeds))
-	for i, t := range embeddeds {
-		tnames[i] = t
-	}
-	return NewInterfaceType(methods, tnames)
-}
-
-// NewInterfaceType returns a new (incomplete) interface for the given methods and embedded types.
-// Each embedded type must have an underlying type of interface type (this property is not
-// verified for defined types, which may be in the process of being set up and which don't
-// have a valid underlying type yet).
-// NewInterfaceType takes ownership of the provided methods and may modify their types by setting
-// missing receivers. To compute the method set of the interface, Complete must be called.
-func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
-	if len(methods) == 0 && len(embeddeds) == 0 {
-		return &emptyInterface
-	}
-
-	// set method receivers if necessary
-	typ := new(Interface)
-	for _, m := range methods {
-		if sig := m.typ.(*Signature); sig.recv == nil {
-			sig.recv = NewVar(m.pos, m.pkg, "", typ)
-		}
-	}
-
-	// All embedded types should be interfaces; however, defined types
-	// may not yet be fully resolved. Only verify that non-defined types
-	// are interfaces. This matches the behavior of the code before the
-	// fix for #25301 (issue #25596).
-	for _, t := range embeddeds {
-		if _, ok := t.(*Named); !ok && !IsInterface(t) {
-			panic("embedded type is not an interface")
-		}
-	}
-
-	// sort for API stability
-	sortMethods(methods)
-	sortTypes(embeddeds)
-
-	typ.methods = methods
-	typ.embeddeds = embeddeds
-	return typ
-}
-
-// NumExplicitMethods returns the number of explicitly declared methods of interface t.
-func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
-
-// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
-// The methods are ordered by their unique Id.
-func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
-
-// NumEmbeddeds returns the number of embedded types in interface t.
-func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
-
-// Embedded returns the i'th embedded defined (*Named) type of interface t for 0 <= i < t.NumEmbeddeds().
-// The result is nil if the i'th embedded type is not a defined type.
-//
-// Deprecated: Use EmbeddedType which is not restricted to defined (*Named) types.
-func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named); return tname }
-
-// EmbeddedType returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
-func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
-
-// NumMethods returns the total number of methods of interface t.
-// The interface must have been completed.
-func (t *Interface) NumMethods() int { t.assertCompleteness(); return len(t.allMethods) }
-
-func (t *Interface) assertCompleteness() {
-	if t.allMethods == nil {
-		panic("interface is incomplete")
-	}
-}
-
-// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
-// The methods are ordered by their unique Id.
-// The interface must have been completed.
-func (t *Interface) Method(i int) *Func { t.assertCompleteness(); return t.allMethods[i] }
-
-// Empty reports whether t is the empty interface.
-func (t *Interface) Empty() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		// A non-nil allTypes may still be empty and represents the bottom type.
-		return len(t.allMethods) == 0 && t.allTypes == nil
-	}
-	return !t.iterate(func(t *Interface) bool {
-		return len(t.methods) > 0 || t.types != nil
-	}, nil)
-}
-
-// _HasTypeList reports whether interface t has a type list, possibly from an embedded type.
-func (t *Interface) _HasTypeList() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		return t.allTypes != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		return t.types != nil
-	}, nil)
-}
-
-// _IsComparable reports whether interface t is or embeds the predeclared interface "comparable".
-func (t *Interface) _IsComparable() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		_, m := lookupMethod(t.allMethods, nil, "==")
-		return m != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		_, m := lookupMethod(t.methods, nil, "==")
-		return m != nil
-	}, nil)
-}
-
-// _IsConstraint reports t.HasTypeList() || t.IsComparable().
-func (t *Interface) _IsConstraint() bool {
-	if t.allMethods != nil {
-		// interface is complete - quick test
-		if t.allTypes != nil {
-			return true
-		}
-		_, m := lookupMethod(t.allMethods, nil, "==")
-		return m != nil
-	}
-
-	return t.iterate(func(t *Interface) bool {
-		if t.types != nil {
-			return true
-		}
-		_, m := lookupMethod(t.methods, nil, "==")
-		return m != nil
-	}, nil)
-}
-
-// iterate calls f with t and then with any embedded interface of t, recursively, until f returns true.
-// iterate reports whether any call to f returned true.
-func (t *Interface) iterate(f func(*Interface) bool, seen map[*Interface]bool) bool {
-	if f(t) {
-		return true
-	}
-	for _, e := range t.embeddeds {
-		// e should be an interface but be careful (it may be invalid)
-		if e := asInterface(e); e != nil {
-			// Cyclic interfaces such as "type E interface { E }" are not permitted
-			// but they are still constructed and we need to detect such cycles.
-			if seen[e] {
-				continue
-			}
-			if seen == nil {
-				seen = make(map[*Interface]bool)
-			}
-			seen[e] = true
-			if e.iterate(f, seen) {
-				return true
-			}
-		}
-	}
-	return false
-}
-
-// isSatisfiedBy reports whether interface t's type list is satisfied by the type typ.
-// If the type list is empty (absent), typ trivially satisfies the interface.
-// TODO(gri) This is not a great name. Eventually, we should have a more comprehensive
-//           "implements" predicate.
-func (t *Interface) isSatisfiedBy(typ Type) bool {
-	t.Complete()
-	if t.allTypes == nil {
-		return true
-	}
-	types := unpackType(t.allTypes)
-	return includes(types, typ) || includes(types, under(typ))
-}
-
-// Complete computes the interface's method set. It must be called by users of
-// NewInterfaceType and NewInterface after the interface's embedded types are
-// fully defined and before using the interface type in any way other than to
-// form other types. The interface must not contain duplicate methods or a
-// panic occurs. Complete returns the receiver.
-func (t *Interface) Complete() *Interface {
-	// TODO(gri) consolidate this method with Checker.completeInterface
-	if t.allMethods != nil {
-		return t
-	}
-
-	t.allMethods = markComplete // avoid infinite recursion
-
-	var todo []*Func
-	var methods []*Func
-	var seen objset
-	addMethod := func(m *Func, explicit bool) {
-		switch other := seen.insert(m); {
-		case other == nil:
-			methods = append(methods, m)
-		case explicit:
-			panic("duplicate method " + m.name)
-		default:
-			// check method signatures after all locally embedded interfaces are computed
-			todo = append(todo, m, other.(*Func))
-		}
-	}
-
-	for _, m := range t.methods {
-		addMethod(m, true)
-	}
-
-	allTypes := t.types
-
-	for _, typ := range t.embeddeds {
-		utyp := under(typ)
-		etyp := asInterface(utyp)
-		if etyp == nil {
-			if utyp != Typ[Invalid] {
-				panic(fmt.Sprintf("%s is not an interface", typ))
-			}
-			continue
-		}
-		etyp.Complete()
-		for _, m := range etyp.allMethods {
-			addMethod(m, false)
-		}
-		allTypes = intersect(allTypes, etyp.allTypes)
-	}
-
-	for i := 0; i < len(todo); i += 2 {
-		m := todo[i]
-		other := todo[i+1]
-		if !Identical(m.typ, other.typ) {
-			panic("duplicate method " + m.name)
-		}
-	}
-
-	if methods != nil {
-		sortMethods(methods)
-		t.allMethods = methods
-	}
-	t.allTypes = allTypes
-
 	return t
 }
 
-// A Map represents a map type.
-type Map struct {
-	key, elem Type
-}
-
-// NewMap returns a new map for the given key and element types.
-func NewMap(key, elem Type) *Map {
-	return &Map{key: key, elem: elem}
-}
-
-// Key returns the key type of map m.
-func (m *Map) Key() Type { return m.key }
-
-// Elem returns the element type of map m.
-func (m *Map) Elem() Type { return m.elem }
-
-// A Chan represents a channel type.
-type Chan struct {
-	dir  ChanDir
-	elem Type
-}
-
-// A ChanDir value indicates a channel direction.
-type ChanDir int
-
-// The direction of a channel is indicated by one of these constants.
-const (
-	SendRecv ChanDir = iota
-	SendOnly
-	RecvOnly
-)
-
-// NewChan returns a new channel type for the given direction and element type.
-func NewChan(dir ChanDir, elem Type) *Chan {
-	return &Chan{dir: dir, elem: elem}
-}
-
-// Dir returns the direction of channel c.
-func (c *Chan) Dir() ChanDir { return c.dir }
-
-// Elem returns the element type of channel c.
-func (c *Chan) Elem() Type { return c.elem }
-
-// A Named represents a named (defined) type.
-type Named struct {
-	check      *Checker    // for Named.under implementation; nilled once under has been called
-	info       typeInfo    // for cycle detection
-	obj        *TypeName   // corresponding declared object
-	orig       Type        // type (on RHS of declaration) this *Named type is derived of (for cycle reporting)
-	underlying Type        // possibly a *Named during setup; never a *Named once set up completely
-	tparams    []*TypeName // type parameters, or nil
-	targs      []Type      // type arguments (after instantiation), or nil
-	methods    []*Func     // methods declared for this type (not the method set of this type); signatures are type-checked lazily
-}
-
-// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
-// If the given type name obj doesn't have a type yet, its type is set to the returned named type.
-// The underlying type must not be a *Named.
-func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
-	if _, ok := underlying.(*Named); ok {
-		panic("types.NewNamed: underlying type must not be *Named")
-	}
-	return (*Checker)(nil).newNamed(obj, underlying, methods)
-}
-
-func (check *Checker) newNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
-	typ := &Named{check: check, obj: obj, orig: underlying, underlying: underlying, methods: methods}
-	if obj.typ == nil {
-		obj.typ = typ
-	}
-	// Ensure that typ is always expanded, at which point the check field can be
-	// nilled out.
-	//
-	// Note that currently we cannot nil out check inside typ.under(), because
-	// it's possible that typ is expanded multiple times.
-	//
-	// TODO(rFindley): clean this up so that under is the only function mutating
-	//                 named types.
-	if check != nil {
-		check.later(func() {
-			switch typ.under().(type) {
-			case *Named, *instance:
-				panic("internal error: unexpanded underlying type")
-			}
-			typ.check = nil
-		})
-	}
-	return typ
-}
-
-// Obj returns the type name for the named type t.
-func (t *Named) Obj() *TypeName { return t.obj }
-
-// TODO(gri) Come up with a better representation and API to distinguish
-//           between parameterized instantiated and non-instantiated types.
-
-// _TParams returns the type parameters of the named type t, or nil.
-// The result is non-nil for an (originally) parameterized type even if it is instantiated.
-func (t *Named) _TParams() []*TypeName { return t.tparams }
-
-// _TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated.
-func (t *Named) _TArgs() []Type { return t.targs }
-
-// _SetTArgs sets the type arguments of Named.
-func (t *Named) _SetTArgs(args []Type) { t.targs = args }
-
-// NumMethods returns the number of explicit methods whose receiver is named type t.
-func (t *Named) NumMethods() int { return len(t.methods) }
-
-// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
-func (t *Named) Method(i int) *Func { return t.methods[i] }
-
-// SetUnderlying sets the underlying type and marks t as complete.
-func (t *Named) SetUnderlying(underlying Type) {
-	if underlying == nil {
-		panic("types.Named.SetUnderlying: underlying type must not be nil")
-	}
-	if _, ok := underlying.(*Named); ok {
-		panic("types.Named.SetUnderlying: underlying type must not be *Named")
-	}
-	t.underlying = underlying
-}
-
-// AddMethod adds method m unless it is already in the method list.
-func (t *Named) AddMethod(m *Func) {
-	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
-		t.methods = append(t.methods, m)
-	}
-}
-
-// Note: This is a uint32 rather than a uint64 because the
-// respective 64 bit atomic instructions are not available
-// on all platforms.
-var lastId uint32
-
-// nextId returns a value increasing monotonically by 1 with
-// each call, starting with 1. It may be called concurrently.
-func nextId() uint64 { return uint64(atomic.AddUint32(&lastId, 1)) }
-
-// A _TypeParam represents a type parameter type.
-type _TypeParam struct {
-	check *Checker  // for lazy type bound completion
-	id    uint64    // unique id
-	obj   *TypeName // corresponding type name
-	index int       // parameter index
-	bound Type      // *Named or *Interface; underlying type is always *Interface
-}
-
-// newTypeParam returns a new TypeParam.
-func (check *Checker) newTypeParam(obj *TypeName, index int, bound Type) *_TypeParam {
-	assert(bound != nil)
-	typ := &_TypeParam{check: check, id: nextId(), obj: obj, index: index, bound: bound}
-	if obj.typ == nil {
-		obj.typ = typ
-	}
-	return typ
-}
-
-func (t *_TypeParam) Bound() *Interface {
-	iface := asInterface(t.bound)
-	// use the type bound position if we have one
-	pos := token.NoPos
-	if n, _ := t.bound.(*Named); n != nil {
-		pos = n.obj.pos
-	}
-	// TODO(rFindley) switch this to an unexported method on Checker.
-	t.check.completeInterface(pos, iface)
-	return iface
-}
-
 // optype returns a type's operational type. Except for
 // type parameters, the operational type is the same
 // as the underlying type (as returned by under). For
@@ -784,130 +56,22 @@
 		// for a type parameter list of the form:
 		// (type T interface { type T }).
 		// See also issue #39680.
-		if u := t.Bound().allTypes; u != nil && u != typ {
-			// u != typ and u is a type parameter => under(u) != typ, so this is ok
-			return under(u)
+		if a := t.iface().typeSet().types; a != nil && a != typ {
+			// If we have a union with a single entry, ignore
+			// any tilde because under(~t) == under(t).
+			if u, _ := a.(*Union); u != nil && u.NumTerms() == 1 {
+				a, _ = u.Term(0)
+			}
+			if a != typ {
+				// a != typ and a is a type parameter => under(a) != typ, so this is ok
+				return under(a)
+			}
 		}
 		return theTop
 	}
 	return under(typ)
 }
 
-// An instance represents an instantiated generic type syntactically
-// (without expanding the instantiation). Type instances appear only
-// during type-checking and are replaced by their fully instantiated
-// (expanded) types before the end of type-checking.
-type instance struct {
-	check   *Checker    // for lazy instantiation
-	pos     token.Pos   // position of type instantiation; for error reporting only
-	base    *Named      // parameterized type to be instantiated
-	targs   []Type      // type arguments
-	poslist []token.Pos // position of each targ; for error reporting only
-	value   Type        // base(targs...) after instantiation or Typ[Invalid]; nil if not yet set
-}
-
-// expand returns the instantiated (= expanded) type of t.
-// The result is either an instantiated *Named type, or
-// Typ[Invalid] if there was an error.
-func (t *instance) expand() Type {
-	v := t.value
-	if v == nil {
-		v = t.check.instantiate(t.pos, t.base, t.targs, t.poslist)
-		if v == nil {
-			v = Typ[Invalid]
-		}
-		t.value = v
-	}
-	// After instantiation we must have an invalid or a *Named type.
-	if debug && v != Typ[Invalid] {
-		_ = v.(*Named)
-	}
-	return v
-}
-
-// expand expands a type instance into its instantiated
-// type and leaves all other types alone. expand does
-// not recurse.
-func expand(typ Type) Type {
-	if t, _ := typ.(*instance); t != nil {
-		return t.expand()
-	}
-	return typ
-}
-
-// expandf is set to expand.
-// Call expandf when calling expand causes compile-time cycle error.
-var expandf func(Type) Type
-
-func init() { expandf = expand }
-
-// bottom represents the bottom of the type lattice.
-// It is the underlying type of a type parameter that
-// cannot be satisfied by any type, usually because
-// the intersection of type constraints left nothing).
-type bottom struct{}
-
-// theBottom is the singleton bottom type.
-var theBottom = &bottom{}
-
-// top represents the top of the type lattice.
-// It is the underlying type of a type parameter that
-// can be satisfied by any type (ignoring methods),
-// usually because the type constraint has no type
-// list.
-type top struct{}
-
-// theTop is the singleton top type.
-var theTop = &top{}
-
-// Type-specific implementations of Underlying.
-func (t *Basic) Underlying() Type      { return t }
-func (t *Array) Underlying() Type      { return t }
-func (t *Slice) Underlying() Type      { return t }
-func (t *Struct) Underlying() Type     { return t }
-func (t *Pointer) Underlying() Type    { return t }
-func (t *Tuple) Underlying() Type      { return t }
-func (t *Signature) Underlying() Type  { return t }
-func (t *_Sum) Underlying() Type       { return t }
-func (t *Interface) Underlying() Type  { return t }
-func (t *Map) Underlying() Type        { return t }
-func (t *Chan) Underlying() Type       { return t }
-func (t *Named) Underlying() Type      { return t.underlying }
-func (t *_TypeParam) Underlying() Type { return t }
-func (t *instance) Underlying() Type   { return t }
-func (t *bottom) Underlying() Type     { return t }
-func (t *top) Underlying() Type        { return t }
-
-// Type-specific implementations of String.
-func (t *Basic) String() string      { return TypeString(t, nil) }
-func (t *Array) String() string      { return TypeString(t, nil) }
-func (t *Slice) String() string      { return TypeString(t, nil) }
-func (t *Struct) String() string     { return TypeString(t, nil) }
-func (t *Pointer) String() string    { return TypeString(t, nil) }
-func (t *Tuple) String() string      { return TypeString(t, nil) }
-func (t *Signature) String() string  { return TypeString(t, nil) }
-func (t *_Sum) String() string       { return TypeString(t, nil) }
-func (t *Interface) String() string  { return TypeString(t, nil) }
-func (t *Map) String() string        { return TypeString(t, nil) }
-func (t *Chan) String() string       { return TypeString(t, nil) }
-func (t *Named) String() string      { return TypeString(t, nil) }
-func (t *_TypeParam) String() string { return TypeString(t, nil) }
-func (t *instance) String() string   { return TypeString(t, nil) }
-func (t *bottom) String() string     { return TypeString(t, nil) }
-func (t *top) String() string        { return TypeString(t, nil) }
-
-// under returns the true expanded underlying type.
-// If it doesn't exist, the result is Typ[Invalid].
-// under must only be called when a type is known
-// to be fully set up.
-func under(t Type) Type {
-	// TODO(gri) is this correct for *Sum?
-	if n := asNamed(t); n != nil {
-		return n.under()
-	}
-	return t
-}
-
 // Converters
 //
 // A converter must only be called when a type is
@@ -941,46 +105,26 @@
 	return op
 }
 
-func asTuple(t Type) *Tuple {
-	op, _ := optype(t).(*Tuple)
-	return op
-}
-
 func asSignature(t Type) *Signature {
 	op, _ := optype(t).(*Signature)
 	return op
 }
 
-func asSum(t Type) *_Sum {
-	op, _ := optype(t).(*_Sum)
-	return op
-}
+// If the argument to asInterface, asNamed, or asTypeParam is of the respective type
+// (possibly after expanding an instance type), these methods return that type.
+// Otherwise the result is nil.
 
 func asInterface(t Type) *Interface {
 	op, _ := optype(t).(*Interface)
 	return op
 }
 
-func asMap(t Type) *Map {
-	op, _ := optype(t).(*Map)
-	return op
-}
-
-func asChan(t Type) *Chan {
-	op, _ := optype(t).(*Chan)
-	return op
-}
-
-// If the argument to asNamed and asTypeParam is of the respective types
-// (possibly after expanding an instance type), these methods return that type.
-// Otherwise the result is nil.
-
 func asNamed(t Type) *Named {
 	e, _ := expand(t).(*Named)
 	return e
 }
 
-func asTypeParam(t Type) *_TypeParam {
-	u, _ := under(t).(*_TypeParam)
+func asTypeParam(t Type) *TypeParam {
+	u, _ := under(t).(*TypeParam)
 	return u
 }
diff --git a/src/go/types/typeparam.go b/src/go/types/typeparam.go
new file mode 100644
index 0000000..33a516c
--- /dev/null
+++ b/src/go/types/typeparam.go
@@ -0,0 +1,136 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/token"
+	"sync/atomic"
+)
+
+// Note: This is a uint32 rather than a uint64 because the
+// respective 64 bit atomic instructions are not available
+// on all platforms.
+var lastID uint32
+
+// nextID returns a value increasing monotonically by 1 with
+// each call, starting with 1. It may be called concurrently.
+func nextID() uint64 { return uint64(atomic.AddUint32(&lastID, 1)) }
+
+// A TypeParam represents a type parameter type.
+type TypeParam struct {
+	check *Checker  // for lazy type bound completion
+	id    uint64    // unique id, for debugging only
+	obj   *TypeName // corresponding type name
+	index int       // type parameter index in source order, starting at 0
+	// TODO(rfindley): this could also be Typ[Invalid]. Verify that this is handled correctly.
+	bound Type // *Named or *Interface; underlying type is always *Interface
+}
+
+// NewTypeParam returns a new TypeParam. Type parameters may be set on a Named
+// or Signature type by calling SetTParams. Setting a type parameter on more
+// than one type will result in a panic.
+//
+// The bound argument can be nil, and set later via SetBound.
+func (check *Checker) NewTypeParam(obj *TypeName, bound Type) *TypeParam {
+	// Always increment lastID, even if it is not used.
+	id := nextID()
+	if check != nil {
+		check.nextID++
+		id = check.nextID
+	}
+	typ := &TypeParam{check: check, id: id, obj: obj, index: -1, bound: bound}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	return typ
+}
+
+// TODO(rfindley): remove or export these placeholder APIs.
+
+// Index returns the index of the type param within its param list.
+func (t *TypeParam) _Index() int {
+	return t.index
+}
+
+// SetId sets the unique id of a type param. Should only be used for type params
+// in imported generic types.
+func (t *TypeParam) _SetId(id uint64) {
+	t.id = id
+}
+
+// Constraint returns the type constraint specified for t.
+func (t *TypeParam) Constraint() Type {
+	// compute the type set if possible (we may not have an interface)
+	if iface, _ := under(t.bound).(*Interface); iface != nil {
+		// use the type bound position if we have one
+		pos := token.NoPos
+		if n, _ := t.bound.(*Named); n != nil {
+			pos = n.obj.pos
+		}
+		computeTypeSet(t.check, pos, iface)
+	}
+	return t.bound
+}
+
+// SetConstraint sets the type constraint for t.
+func (t *TypeParam) SetConstraint(bound Type) {
+	if bound == nil {
+		panic("types2.TypeParam.SetConstraint: bound must not be nil")
+	}
+	t.bound = bound
+}
+
+// iface returns the constraint interface of t.
+func (t *TypeParam) iface() *Interface {
+	if iface, _ := under(t.Constraint()).(*Interface); iface != nil {
+		return iface
+	}
+	return &emptyInterface
+}
+
+func (t *TypeParam) Underlying() Type { return t }
+func (t *TypeParam) String() string   { return TypeString(t, nil) }
+
+// TypeParams holds a list of type parameters bound to a type.
+type TypeParams struct{ tparams []*TypeName }
+
+// Len returns the number of type parameters in the list.
+// It is safe to call on a nil receiver.
+func (tps *TypeParams) Len() int {
+	return len(tps.list())
+}
+
+// At returns the i'th type parameter in the list.
+func (tps *TypeParams) At(i int) *TypeName {
+	return tps.list()[i]
+}
+
+func (tps *TypeParams) list() []*TypeName {
+	if tps == nil {
+		return nil
+	}
+	return tps.tparams
+}
+
+func bindTParams(list []*TypeName) *TypeParams {
+	if len(list) == 0 {
+		return nil
+	}
+	for i, tp := range list {
+		typ := tp.Type().(*TypeParam)
+		if typ.index >= 0 {
+			panic("internal error: type parameter bound more than once")
+		}
+		typ.index = i
+	}
+	return &TypeParams{tparams: list}
+}
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+func (t *TypeParam) underIs(f func(Type) bool) bool {
+	return t.iface().typeSet().underIs(f)
+}
diff --git a/src/go/types/types_test.go b/src/go/types/types_test.go
index 25cd996..f2358c6 100644
--- a/src/go/types/types_test.go
+++ b/src/go/types/types_test.go
@@ -4,16 +4,5 @@
 
 package types
 
-import "sync/atomic"
-
-// Upon calling ResetId, nextId starts with 1 again.
-// It may be called concurrently. This is only needed
-// for tests where we may want to have a consistent
-// numbering for each individual test case.
-func ResetId() { atomic.StoreUint32(&lastId, 0) }
-
-// SetGoVersion sets the unexported goVersion field on config, so that tests
-// which assert on behavior for older Go versions can set it.
-func SetGoVersion(config *Config, goVersion string) {
-	config.goVersion = goVersion
-}
+// Debug is set if go/types is built with debug mode enabled.
+const Debug = debug
diff --git a/src/go/types/typeset.go b/src/go/types/typeset.go
new file mode 100644
index 0000000..836f930
--- /dev/null
+++ b/src/go/types/typeset.go
@@ -0,0 +1,298 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"bytes"
+	"fmt"
+	"go/token"
+	"sort"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A _TypeSet represents the type set of an interface.
+type _TypeSet struct {
+	comparable bool // if set, the interface is or embeds comparable
+	// TODO(gri) consider using a set for the methods for faster lookup
+	methods []*Func // all methods of the interface; sorted by unique ID
+	types   Type    // typically a *Union; nil means no type restrictions
+}
+
+// IsTop reports whether type set s is the top type set (corresponding to the empty interface).
+func (s *_TypeSet) IsTop() bool { return !s.comparable && len(s.methods) == 0 && s.types == nil }
+
+// IsMethodSet reports whether the type set s is described by a single set of methods.
+func (s *_TypeSet) IsMethodSet() bool { return !s.comparable && s.types == nil }
+
+// IsComparable reports whether each type in the set is comparable.
+// TODO(gri) this is not correct - there may be s.types values containing non-comparable types
+func (s *_TypeSet) IsComparable() bool {
+	if s.types == nil {
+		return s.comparable
+	}
+	tcomparable := s.underIs(func(u Type) bool {
+		return Comparable(u)
+	})
+	if !s.comparable {
+		return tcomparable
+	}
+	return s.comparable && tcomparable
+}
+
+// TODO(gri) IsTypeSet is not a great name. Find a better one.
+
+// IsTypeSet reports whether the type set s is represented by a finite set of underlying types.
+func (s *_TypeSet) IsTypeSet() bool {
+	return !s.comparable && len(s.methods) == 0
+}
+
+// NumMethods returns the number of methods available.
+func (s *_TypeSet) NumMethods() int { return len(s.methods) }
+
+// Method returns the i'th method of type set s for 0 <= i < s.NumMethods().
+// The methods are ordered by their unique ID.
+func (s *_TypeSet) Method(i int) *Func { return s.methods[i] }
+
+// LookupMethod returns the index of and method with matching package and name, or (-1, nil).
+func (s *_TypeSet) LookupMethod(pkg *Package, name string) (int, *Func) {
+	// TODO(gri) s.methods is sorted - consider binary search
+	return lookupMethod(s.methods, pkg, name)
+}
+
+func (s *_TypeSet) String() string {
+	if s.IsTop() {
+		return "⊤"
+	}
+
+	var buf bytes.Buffer
+	buf.WriteByte('{')
+	if s.comparable {
+		buf.WriteString(" comparable")
+		if len(s.methods) > 0 || s.types != nil {
+			buf.WriteByte(';')
+		}
+	}
+	for i, m := range s.methods {
+		if i > 0 {
+			buf.WriteByte(';')
+		}
+		buf.WriteByte(' ')
+		buf.WriteString(m.String())
+	}
+	if len(s.methods) > 0 && s.types != nil {
+		buf.WriteByte(';')
+	}
+	if s.types != nil {
+		buf.WriteByte(' ')
+		writeType(&buf, s.types, nil, nil)
+	}
+
+	buf.WriteString(" }") // there was a least one method or type
+	return buf.String()
+}
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+// underIs reports whether f returned true for the underlying types of the
+// enumerable types in the type set s. If the type set comprises all types
+// f is called once with the top type; if the type set is empty, the result
+// is false.
+func (s *_TypeSet) underIs(f func(Type) bool) bool {
+	switch t := s.types.(type) {
+	case nil:
+		return f(theTop)
+	default:
+		return f(t)
+	case *Union:
+		return t.underIs(f)
+	}
+}
+
+// topTypeSet may be used as type set for the empty interface.
+var topTypeSet _TypeSet
+
+// computeTypeSet may be called with check == nil.
+func computeTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_TypeSet {
+	if ityp.tset != nil {
+		return ityp.tset
+	}
+
+	// If the interface is not fully set up yet, the type set will
+	// not be complete, which may lead to errors when using the the
+	// type set (e.g. missing method). Don't compute a partial type
+	// set (and don't store it!), so that we still compute the full
+	// type set eventually. Instead, return the top type set and
+	// let any follow-on errors play out.
+	//
+	// TODO(gri) Consider recording when this happens and reporting
+	// it as an error (but only if there were no other errors so to
+	// to not have unnecessary follow-on errors).
+	if !ityp.complete {
+		return &topTypeSet
+	}
+
+	if check != nil && trace {
+		// Types don't generally have position information.
+		// If we don't have a valid pos provided, try to use
+		// one close enough.
+		if !pos.IsValid() && len(ityp.methods) > 0 {
+			pos = ityp.methods[0].pos
+		}
+
+		check.trace(pos, "type set for %s", ityp)
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(pos, "=> %s ", ityp.typeSet())
+		}()
+	}
+
+	// An infinitely expanding interface (due to a cycle) is detected
+	// elsewhere (Checker.validType), so here we simply assume we only
+	// have valid interfaces. Mark the interface as complete to avoid
+	// infinite recursion if the validType check occurs later for some
+	// reason.
+	ityp.tset = new(_TypeSet) // TODO(gri) is this sufficient?
+
+	// Methods of embedded interfaces are collected unchanged; i.e., the identity
+	// of a method I.m's Func Object of an interface I is the same as that of
+	// the method m in an interface that embeds interface I. On the other hand,
+	// if a method is embedded via multiple overlapping embedded interfaces, we
+	// don't provide a guarantee which "original m" got chosen for the embedding
+	// interface. See also issue #34421.
+	//
+	// If we don't care to provide this identity guarantee anymore, instead of
+	// reusing the original method in embeddings, we can clone the method's Func
+	// Object and give it the position of a corresponding embedded interface. Then
+	// we can get rid of the mpos map below and simply use the cloned method's
+	// position.
+
+	var todo []*Func
+	var seen objset
+	var methods []*Func
+	mpos := make(map[*Func]token.Pos) // method specification or method embedding position, for good error messages
+	addMethod := func(pos token.Pos, m *Func, explicit bool) {
+		switch other := seen.insert(m); {
+		case other == nil:
+			methods = append(methods, m)
+			mpos[m] = pos
+		case explicit:
+			if check == nil {
+				panic(fmt.Sprintf("%v: duplicate method %s", m.pos, m.name))
+			}
+			// check != nil
+			check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
+			check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
+		default:
+			// We have a duplicate method name in an embedded (not explicitly declared) method.
+			// Check method signatures after all types are computed (issue #33656).
+			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
+			// error here as well (even though we could do it eagerly) because it's the same
+			// error message.
+			if check == nil {
+				// check method signatures after all locally embedded interfaces are computed
+				todo = append(todo, m, other.(*Func))
+				break
+			}
+			// check != nil
+			check.later(func() {
+				if !check.allowVersion(m.pkg, 1, 14) || !Identical(m.typ, other.Type()) {
+					check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
+					check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
+				}
+			})
+		}
+	}
+
+	for _, m := range ityp.methods {
+		addMethod(m.pos, m, true)
+	}
+
+	// collect embedded elements
+	var allTypes Type
+	for i, typ := range ityp.embeddeds {
+		// The embedding position is nil for imported interfaces
+		// and also for interface copies after substitution (but
+		// in that case we don't need to report errors again).
+		var pos token.Pos // embedding position
+		if ityp.embedPos != nil {
+			pos = (*ityp.embedPos)[i]
+		}
+		var types Type
+		switch t := under(typ).(type) {
+		case *Interface:
+			tset := computeTypeSet(check, pos, t)
+			if tset.comparable {
+				ityp.tset.comparable = true
+			}
+			for _, m := range tset.methods {
+				addMethod(pos, m, false) // use embedding position pos rather than m.pos
+
+			}
+			types = tset.types
+		case *Union:
+			// TODO(gri) combine with default case once we have
+			//           converted all tests to new notation and we
+			//           can report an error when we don't have an
+			//           interface before go1.18.
+			types = typ
+		case *TypeParam:
+			// Embedding stand-alone type parameters is not permitted for now.
+			// This case is handled during union parsing.
+			unreachable()
+		default:
+			if typ == Typ[Invalid] {
+				continue
+			}
+			if check != nil && !check.allowVersion(check.pkg, 1, 18) {
+				check.errorf(atPos(pos), _InvalidIfaceEmbed, "%s is not an interface", typ)
+				continue
+			}
+			types = typ
+		}
+		allTypes = intersect(allTypes, types)
+	}
+	ityp.embedPos = nil // not needed anymore (errors have been reported)
+
+	// process todo's (this only happens if check == nil)
+	for i := 0; i < len(todo); i += 2 {
+		m := todo[i]
+		other := todo[i+1]
+		if !Identical(m.typ, other.typ) {
+			panic(fmt.Sprintf("%v: duplicate method %s", m.pos, m.name))
+		}
+	}
+
+	if methods != nil {
+		sort.Sort(byUniqueMethodName(methods))
+		ityp.tset.methods = methods
+	}
+	ityp.tset.types = allTypes
+
+	return ityp.tset
+}
+
+func sortMethods(list []*Func) {
+	sort.Sort(byUniqueMethodName(list))
+}
+
+func assertSortedMethods(list []*Func) {
+	if !debug {
+		panic("internal error: assertSortedMethods called outside debug mode")
+	}
+	if !sort.IsSorted(byUniqueMethodName(list)) {
+		panic("internal error: methods not sorted")
+	}
+}
+
+// byUniqueMethodName method lists can be sorted by their unique method names.
+type byUniqueMethodName []*Func
+
+func (a byUniqueMethodName) Len() int           { return len(a) }
+func (a byUniqueMethodName) Less(i, j int) bool { return a[i].Id() < a[j].Id() }
+func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
diff --git a/src/go/types/typestring.go b/src/go/types/typestring.go
index fe27f0f..c0c6962 100644
--- a/src/go/types/typestring.go
+++ b/src/go/types/typestring.go
@@ -158,12 +158,19 @@
 		buf.WriteString("func")
 		writeSignature(buf, t, qf, visited)
 
-	case *_Sum:
-		for i, t := range t.types {
+	case *Union:
+		if t.IsEmpty() {
+			buf.WriteString("⊥")
+			break
+		}
+		for i, t := range t.terms {
 			if i > 0 {
-				buf.WriteString(", ")
+				buf.WriteByte('|')
 			}
-			writeType(buf, t, qf, visited)
+			if t.tilde {
+				buf.WriteByte('~')
+			}
+			writeType(buf, t.typ, qf, visited)
 		}
 
 	case *Interface:
@@ -183,7 +190,8 @@
 		if gcCompatibilityMode {
 			// print flattened interface
 			// (useful to compare against gc-generated interfaces)
-			for i, m := range t.allMethods {
+			tset := t.typeSet()
+			for i, m := range tset.methods {
 				if i > 0 {
 					buf.WriteString("; ")
 				}
@@ -191,12 +199,12 @@
 				writeSignature(buf, m.typ.(*Signature), qf, visited)
 				empty = false
 			}
-			if !empty && t.allTypes != nil {
+			if !empty && tset.types != nil {
 				buf.WriteString("; ")
 			}
-			if t.allTypes != nil {
+			if tset.types != nil {
 				buf.WriteString("type ")
-				writeType(buf, t.allTypes, qf, visited)
+				writeType(buf, tset.types, qf, visited)
 			}
 		} else {
 			// print explicit interface methods and embedded types
@@ -208,14 +216,6 @@
 				writeSignature(buf, m.typ.(*Signature), qf, visited)
 				empty = false
 			}
-			if !empty && t.types != nil {
-				buf.WriteString("; ")
-			}
-			if t.types != nil {
-				buf.WriteString("type ")
-				writeType(buf, t.types, qf, visited)
-				empty = false
-			}
 			if !empty && len(t.embeddeds) > 0 {
 				buf.WriteString("; ")
 			}
@@ -227,7 +227,9 @@
 				empty = false
 			}
 		}
-		if t.allMethods == nil || len(t.methods) > len(t.allMethods) {
+		// print /* incomplete */ if needed to satisfy existing tests
+		// TODO(gri) get rid of this eventually
+		if debug && t.tset == nil {
 			if !empty {
 				buf.WriteByte(' ')
 			}
@@ -268,39 +270,40 @@
 		}
 
 	case *Named:
+		if t.instance != nil {
+			buf.WriteByte(instanceMarker)
+		}
 		writeTypeName(buf, t.obj, qf)
 		if t.targs != nil {
 			// instantiated type
 			buf.WriteByte('[')
 			writeTypeList(buf, t.targs, qf, visited)
 			buf.WriteByte(']')
-		} else if t.tparams != nil {
+		} else if t.TParams().Len() != 0 {
 			// parameterized type
-			writeTParamList(buf, t.tparams, qf, visited)
+			writeTParamList(buf, t.TParams().list(), qf, visited)
 		}
 
-	case *_TypeParam:
+	case *TypeParam:
 		s := "?"
 		if t.obj != nil {
+			// Optionally write out package for typeparams (like Named).
+			// TODO(rfindley): this is required for import/export, so
+			// we maybe need a separate function that won't be changed
+			// for debugging purposes.
+			if t.obj.pkg != nil {
+				writePackage(buf, t.obj.pkg, qf)
+			}
 			s = t.obj.name
 		}
 		buf.WriteString(s + subscript(t.id))
 
-	case *instance:
-		buf.WriteByte(instanceMarker) // indicate "non-evaluated" syntactic instance
-		writeTypeName(buf, t.base.obj, qf)
-		buf.WriteByte('[')
-		writeTypeList(buf, t.targs, qf, visited)
-		buf.WriteByte(']')
-
-	case *bottom:
-		buf.WriteString("⊥")
-
 	case *top:
 		buf.WriteString("⊤")
 
 	default:
 		// For externally defined implementations of Type.
+		// Note: In this case cycles won't be caught.
 		buf.WriteString(t.String())
 	}
 }
@@ -321,7 +324,7 @@
 	for i, p := range list {
 		// TODO(rFindley) support 'any' sugar here.
 		var b Type = &emptyInterface
-		if t, _ := p.typ.(*_TypeParam); t != nil && t.bound != nil {
+		if t, _ := p.typ.(*TypeParam); t != nil && t.bound != nil {
 			b = t.bound
 		}
 		if i > 0 {
@@ -334,7 +337,7 @@
 		}
 		prev = b
 
-		if t, _ := p.typ.(*_TypeParam); t != nil {
+		if t, _ := p.typ.(*TypeParam); t != nil {
 			writeType(buf, t, qf, visited)
 		} else {
 			buf.WriteString(p.name)
@@ -348,17 +351,38 @@
 }
 
 func writeTypeName(buf *bytes.Buffer, obj *TypeName, qf Qualifier) {
-	s := "<Named w/o object>"
-	if obj != nil {
-		if obj.pkg != nil {
-			writePackage(buf, obj.pkg, qf)
-		}
-		// TODO(gri): function-local named types should be displayed
-		// differently from named types at package level to avoid
-		// ambiguity.
-		s = obj.name
+	if obj == nil {
+		buf.WriteString("<Named w/o object>")
+		return
 	}
-	buf.WriteString(s)
+	if obj.pkg != nil {
+		writePackage(buf, obj.pkg, qf)
+	}
+	buf.WriteString(obj.name)
+
+	if instanceHashing != 0 {
+		// For local defined types, use the (original!) TypeName's scope
+		// numbers to disambiguate.
+		typ := obj.typ.(*Named)
+		// TODO(gri) Figure out why typ.orig != typ.orig.orig sometimes
+		//           and whether the loop can iterate more than twice.
+		//           (It seems somehow connected to instance types.)
+		for typ.orig != typ {
+			typ = typ.orig
+		}
+		writeScopeNumbers(buf, typ.obj.parent)
+	}
+}
+
+// writeScopeNumbers writes the number sequence for this scope to buf
+// in the form ".i.j.k" where i, j, k, etc. stand for scope numbers.
+// If a scope is nil or has no parent (such as a package scope), nothing
+// is written.
+func writeScopeNumbers(buf *bytes.Buffer, s *Scope) {
+	if s != nil && s.number > 0 {
+		writeScopeNumbers(buf, s.parent)
+		fmt.Fprintf(buf, ".%d", s.number)
+	}
 }
 
 func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visited []Type) {
@@ -403,8 +427,8 @@
 }
 
 func writeSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier, visited []Type) {
-	if sig.tparams != nil {
-		writeTParamList(buf, sig.tparams, qf, visited)
+	if sig.TParams().Len() != 0 {
+		writeTParamList(buf, sig.TParams().list(), qf, visited)
 	}
 
 	writeTuple(buf, sig.params, sig.variadic, qf, visited)
diff --git a/src/go/types/typestring_test.go b/src/go/types/typestring_test.go
index b16529d..f02c0d9 100644
--- a/src/go/types/typestring_test.go
+++ b/src/go/types/typestring_test.go
@@ -95,6 +95,8 @@
 	dup("interface{}"),
 	dup("interface{m()}"),
 	dup(`interface{String() string; m(int) float32}`),
+	dup("interface{int|float32|complex128}"),
+	dup("interface{int|~float32|~complex128}"),
 
 	// TODO(rFindley) uncomment this once this AST is accepted, and add more test
 	// cases.
@@ -143,6 +145,10 @@
 }
 
 func TestIncompleteInterfaces(t *testing.T) {
+	if !Debug {
+		t.Skip("requires type checker to be compiled with debug = true")
+	}
+
 	sig := NewSignature(nil, nil, nil, false)
 	m := NewFunc(token.NoPos, nil, "m", sig)
 	for _, test := range []struct {
diff --git a/src/go/types/typeterm.go b/src/go/types/typeterm.go
new file mode 100644
index 0000000..dbd055a
--- /dev/null
+++ b/src/go/types/typeterm.go
@@ -0,0 +1,166 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+// TODO(gri) use a different symbol instead of ⊤ for the set of all types
+//           (⊤ is hard to distinguish from T in some fonts)
+
+// A term describes elementary type sets:
+//
+//   ∅:  (*term)(nil)     == ∅                      // set of no types (empty set)
+//   ⊤:  &term{}          == ⊤                      // set of all types
+//   T:  &term{false, T}  == {T}                    // set of type T
+//  ~t:  &term{true, t}   == {t' | under(t') == t}  // set of types with underlying type t
+//
+type term struct {
+	tilde bool // valid if typ != nil
+	typ   Type
+}
+
+func (x *term) String() string {
+	switch {
+	case x == nil:
+		return "∅"
+	case x.typ == nil:
+		return "⊤"
+	case x.tilde:
+		return "~" + x.typ.String()
+	default:
+		return x.typ.String()
+	}
+}
+
+// equal reports whether x and y represent the same type set.
+func (x *term) equal(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return x == y
+	case x.typ == nil || y.typ == nil:
+		return x.typ == y.typ
+	}
+	// ∅ ⊂ x, y ⊂ ⊤
+
+	return x.tilde == y.tilde && Identical(x.typ, y.typ)
+}
+
+// union returns the union x ∪ y: zero, one, or two non-nil terms.
+func (x *term) union(y *term) (_, _ *term) {
+	// easy cases
+	switch {
+	case x == nil && y == nil:
+		return nil, nil // ∅ ∪ ∅ == ∅
+	case x == nil:
+		return y, nil // ∅ ∪ y == y
+	case y == nil:
+		return x, nil // x ∪ ∅ == x
+	case x.typ == nil:
+		return x, nil // ⊤ ∪ y == ⊤
+	case y.typ == nil:
+		return y, nil // x ∪ ⊤ == ⊤
+	}
+	// ∅ ⊂ x, y ⊂ ⊤
+
+	if x.disjoint(y) {
+		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∪ ~t == ~t
+	// ~t ∪  T == ~t
+	//  T ∪ ~t == ~t
+	//  T ∪  T ==  T
+	if x.tilde || !y.tilde {
+		return x, nil
+	}
+	return y, nil
+}
+
+// intersect returns the intersection x ∩ y.
+func (x *term) intersect(y *term) *term {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
+	case x.typ == nil:
+		return y // ⊤ ∩ y == y
+	case y.typ == nil:
+		return x // x ∩ ⊤ == x
+	}
+	// ∅ ⊂ x, y ⊂ ⊤
+
+	if x.disjoint(y) {
+		return nil // x ∩ y == ∅ if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∩ ~t == ~t
+	// ~t ∩  T ==  T
+	//  T ∩ ~t ==  T
+	//  T ∩  T ==  T
+	if !x.tilde || y.tilde {
+		return x
+	}
+	return y
+}
+
+// includes reports whether t ∈ x.
+func (x *term) includes(t Type) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return false // t ∈ ∅ == false
+	case x.typ == nil:
+		return true // t ∈ ⊤ == true
+	}
+	// ∅ ⊂ x ⊂ ⊤
+
+	u := t
+	if x.tilde {
+		u = under(u)
+	}
+	return Identical(x.typ, u)
+}
+
+// subsetOf reports whether x ⊆ y.
+func (x *term) subsetOf(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return true // ∅ ⊆ y == true
+	case y == nil:
+		return false // x ⊆ ∅ == false since x != ∅
+	case y.typ == nil:
+		return true // x ⊆ ⊤ == true
+	case x.typ == nil:
+		return false // ⊤ ⊆ y == false since y != ⊤
+	}
+	// ∅ ⊂ x, y ⊂ ⊤
+
+	if x.disjoint(y) {
+		return false // x ⊆ y == false if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ⊆ ~t == true
+	// ~t ⊆ T == false
+	//  T ⊆ ~t == true
+	//  T ⊆  T == true
+	return !x.tilde || y.tilde
+}
+
+// disjoint reports whether x ∩ y == ∅.
+// x.typ and y.typ must not be nil.
+func (x *term) disjoint(y *term) bool {
+	ux := x.typ
+	if y.tilde {
+		ux = under(ux)
+	}
+	uy := y.typ
+	if x.tilde {
+		uy = under(uy)
+	}
+	return !Identical(ux, uy)
+}
diff --git a/src/go/types/typeterm_test.go b/src/go/types/typeterm_test.go
new file mode 100644
index 0000000..391ff3e
--- /dev/null
+++ b/src/go/types/typeterm_test.go
@@ -0,0 +1,205 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"strings"
+	"testing"
+)
+
+var testTerms = map[string]*term{
+	"∅":       nil,
+	"⊤":       {},
+	"int":     {false, Typ[Int]},
+	"~int":    {true, Typ[Int]},
+	"string":  {false, Typ[String]},
+	"~string": {true, Typ[String]},
+	// TODO(gri) add a defined type
+}
+
+func TestTermString(t *testing.T) {
+	for want, x := range testTerms {
+		if got := x.String(); got != want {
+			t.Errorf("%v.String() == %v; want %v", x, got, want)
+		}
+	}
+}
+
+func split(s string, n int) []string {
+	r := strings.Split(s, " ")
+	if len(r) != n {
+		panic("invalid test case: " + s)
+	}
+	return r
+}
+
+func testTerm(name string) *term {
+	r, ok := testTerms[name]
+	if !ok {
+		panic("invalid test argument: " + name)
+	}
+	return r
+}
+
+func TestTermEqual(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ T",
+		"⊤ ⊤ T",
+		"int int T",
+		"~int ~int T",
+		"∅ ⊤ F",
+		"∅ int F",
+		"∅ ~int F",
+		"⊤ int F",
+		"⊤ ~int F",
+		"int ~int F",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.equal(y); got != want {
+			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
+		}
+		// equal is symmetric
+		x, y = y, x
+		if got := x.equal(y); got != want {
+			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermUnion(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ ∅ ∅",
+		"∅ ⊤ ⊤ ∅",
+		"∅ int int ∅",
+		"∅ ~int ~int ∅",
+		"⊤ ⊤ ⊤ ∅",
+		"⊤ int ⊤ ∅",
+		"⊤ ~int ⊤ ∅",
+		"int int int ∅",
+		"int ~int ~int ∅",
+		"int string int string",
+		"int ~string int ~string",
+		"~int ~string ~int ~string",
+
+		// union is symmetric, but the result order isn't - repeat symmetric cases explictly
+		"⊤ ∅ ⊤ ∅",
+		"int ∅ int ∅",
+		"~int ∅ ~int ∅",
+		"int ⊤ ⊤ ∅",
+		"~int ⊤ ⊤ ∅",
+		"~int int ~int ∅",
+		"string int string int",
+		"~string int ~string int",
+		"~string ~int ~string ~int",
+	} {
+		args := split(test, 4)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want1 := testTerm(args[2])
+		want2 := testTerm(args[3])
+		if got1, got2 := x.union(y); !got1.equal(want1) || !got2.equal(want2) {
+			t.Errorf("%v.union(%v) = %v, %v; want %v, %v", x, y, got1, got2, want1, want2)
+		}
+	}
+}
+
+func TestTermIntersection(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ ∅",
+		"∅ ⊤ ∅",
+		"∅ int ∅",
+		"∅ ~int ∅",
+		"⊤ ⊤ ⊤",
+		"⊤ int int",
+		"⊤ ~int ~int",
+		"int int int",
+		"int ~int int",
+		"int string ∅",
+		"int ~string ∅",
+		"~int ~string ∅",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := testTerm(args[2])
+		if got := x.intersect(y); !got.equal(want) {
+			t.Errorf("%v.intersect(%v) = %v; want %v", x, y, got, want)
+		}
+		// intersect is symmetric
+		x, y = y, x
+		if got := x.intersect(y); !got.equal(want) {
+			t.Errorf("%v.intersect(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermIncludes(t *testing.T) {
+	for _, test := range []string{
+		"∅ int F",
+		"⊤ int T",
+		"int int T",
+		"~int int T",
+		"string int F",
+		"~string int F",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1]).typ
+		want := args[2] == "T"
+		if got := x.includes(y); got != want {
+			t.Errorf("%v.includes(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermSubsetOf(t *testing.T) {
+	for _, test := range []string{
+		"∅ ∅ T",
+		"⊤ ⊤ T",
+		"int int T",
+		"~int ~int T",
+		"∅ ⊤ T",
+		"∅ int T",
+		"∅ ~int T",
+		"⊤ int F",
+		"⊤ ~int F",
+		"int ~int T",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.subsetOf(y); got != want {
+			t.Errorf("%v.subsetOf(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
+
+func TestTermDisjoint(t *testing.T) {
+	for _, test := range []string{
+		"int int F",
+		"~int ~int F",
+		"int ~int F",
+		"int string T",
+		"int ~string T",
+		"~int ~string T",
+	} {
+		args := split(test, 3)
+		x := testTerm(args[0])
+		y := testTerm(args[1])
+		want := args[2] == "T"
+		if got := x.disjoint(y); got != want {
+			t.Errorf("%v.disjoint(%v) = %v; want %v", x, y, got, want)
+		}
+		// disjoint is symmetric
+		x, y = y, x
+		if got := x.disjoint(y); got != want {
+			t.Errorf("%v.disjoint(%v) = %v; want %v", x, y, got, want)
+		}
+	}
+}
diff --git a/src/go/types/typexpr.go b/src/go/types/typexpr.go
index 1738d86..a812ba6 100644
--- a/src/go/types/typexpr.go
+++ b/src/go/types/typexpr.go
@@ -12,8 +12,6 @@
 	"go/constant"
 	"go/internal/typeparams"
 	"go/token"
-	"sort"
-	"strconv"
 	"strings"
 )
 
@@ -29,13 +27,24 @@
 	// Note that we cannot use check.lookup here because the returned scope
 	// may be different from obj.Parent(). See also Scope.LookupParent doc.
 	scope, obj := check.scope.LookupParent(e.Name, check.pos)
-	if obj == nil {
+	switch obj {
+	case nil:
 		if e.Name == "_" {
-			check.errorf(e, _InvalidBlank, "cannot use _ as value or type")
+			check.error(e, _InvalidBlank, "cannot use _ as value or type")
 		} else {
 			check.errorf(e, _UndeclaredName, "undeclared name: %s", e.Name)
 		}
 		return
+	case universeAny, universeComparable:
+		if !check.allowVersion(check.pkg, 1, 18) {
+			check.errorf(e, _UndeclaredName, "undeclared name: %s (requires version go1.18 or later)", e.Name)
+			return
+		}
+		// If we allow "any" for general use, this if-statement can be removed (issue #33232).
+		if obj == universeAny {
+			check.error(e, _Todo, "cannot use any outside constraint position")
+			return
+		}
 	}
 	check.recordUse(e, obj)
 
@@ -58,7 +67,7 @@
 	// If so, mark the respective package as used.
 	// (This code is only needed for dot-imports. Without them,
 	// we only have to mark variables, see *Var case below).
-	if pkgName := check.dotImportMap[dotImportKey{scope, obj}]; pkgName != nil {
+	if pkgName := check.dotImportMap[dotImportKey{scope, obj.Name()}]; pkgName != nil {
 		pkgName.used = true
 	}
 
@@ -142,12 +151,12 @@
 	// type-checking.
 	check.later(func() {
 		if t := asInterface(typ); t != nil {
-			check.completeInterface(pos.Pos(), t) // TODO(gri) is this the correct position?
-			if t.allTypes != nil {
-				check.softErrorf(pos, _Todo, "interface contains type constraints (%s)", t.allTypes)
+			tset := computeTypeSet(check, pos.Pos(), t) // TODO(gri) is this the correct position?
+			if tset.types != nil {
+				check.softErrorf(pos, _Todo, "interface contains type constraints (%s)", tset.types)
 				return
 			}
-			if t._IsComparable() {
+			if tset.IsComparable() {
 				check.softErrorf(pos, _Todo, "interface is (or embeds) comparable")
 			}
 		}
@@ -194,205 +203,6 @@
 	return typ
 }
 
-// isubst returns an x with identifiers substituted per the substitution map smap.
-// isubst only handles the case of (valid) method receiver type expressions correctly.
-func isubst(x ast.Expr, smap map[*ast.Ident]*ast.Ident) ast.Expr {
-	switch n := x.(type) {
-	case *ast.Ident:
-		if alt := smap[n]; alt != nil {
-			return alt
-		}
-	case *ast.StarExpr:
-		X := isubst(n.X, smap)
-		if X != n.X {
-			new := *n
-			new.X = X
-			return &new
-		}
-	case *ast.IndexExpr:
-		elems := typeparams.UnpackExpr(n.Index)
-		var newElems []ast.Expr
-		for i, elem := range elems {
-			new := isubst(elem, smap)
-			if new != elem {
-				if newElems == nil {
-					newElems = make([]ast.Expr, len(elems))
-					copy(newElems, elems)
-				}
-				newElems[i] = new
-			}
-		}
-		if newElems != nil {
-			index := typeparams.PackExpr(newElems)
-			new := *n
-			new.Index = index
-			return &new
-		}
-	case *ast.ParenExpr:
-		return isubst(n.X, smap) // no need to keep parentheses
-	default:
-		// Other receiver type expressions are invalid.
-		// It's fine to ignore those here as they will
-		// be checked elsewhere.
-	}
-	return x
-}
-
-// funcType type-checks a function or method type.
-func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast.FuncType) {
-	check.openScope(ftyp, "function")
-	check.scope.isFunc = true
-	check.recordScope(ftyp, check.scope)
-	sig.scope = check.scope
-	defer check.closeScope()
-
-	var recvTyp ast.Expr // rewritten receiver type; valid if != nil
-	if recvPar != nil && len(recvPar.List) > 0 {
-		// collect generic receiver type parameters, if any
-		// - a receiver type parameter is like any other type parameter, except that it is declared implicitly
-		// - the receiver specification acts as local declaration for its type parameters, which may be blank
-		_, rname, rparams := check.unpackRecv(recvPar.List[0].Type, true)
-		if len(rparams) > 0 {
-			// Blank identifiers don't get declared and regular type-checking of the instantiated
-			// parameterized receiver type expression fails in Checker.collectParams of receiver.
-			// Identify blank type parameters and substitute each with a unique new identifier named
-			// "n_" (where n is the parameter index) and which cannot conflict with any user-defined
-			// name.
-			var smap map[*ast.Ident]*ast.Ident // substitution map from "_" to "n_" identifiers
-			for i, p := range rparams {
-				if p.Name == "_" {
-					new := *p
-					new.Name = fmt.Sprintf("%d_", i)
-					rparams[i] = &new // use n_ identifier instead of _ so it can be looked up
-					if smap == nil {
-						smap = make(map[*ast.Ident]*ast.Ident)
-					}
-					smap[p] = &new
-				}
-			}
-			if smap != nil {
-				// blank identifiers were found => use rewritten receiver type
-				recvTyp = isubst(recvPar.List[0].Type, smap)
-			}
-			sig.rparams = check.declareTypeParams(nil, rparams)
-			// determine receiver type to get its type parameters
-			// and the respective type parameter bounds
-			var recvTParams []*TypeName
-			if rname != nil {
-				// recv should be a Named type (otherwise an error is reported elsewhere)
-				// Also: Don't report an error via genericType since it will be reported
-				//       again when we type-check the signature.
-				// TODO(gri) maybe the receiver should be marked as invalid instead?
-				if recv := asNamed(check.genericType(rname, false)); recv != nil {
-					recvTParams = recv.tparams
-				}
-			}
-			// provide type parameter bounds
-			// - only do this if we have the right number (otherwise an error is reported elsewhere)
-			if len(sig.rparams) == len(recvTParams) {
-				// We have a list of *TypeNames but we need a list of Types.
-				list := make([]Type, len(sig.rparams))
-				for i, t := range sig.rparams {
-					list[i] = t.typ
-				}
-				smap := makeSubstMap(recvTParams, list)
-				for i, tname := range sig.rparams {
-					bound := recvTParams[i].typ.(*_TypeParam).bound
-					// bound is (possibly) parameterized in the context of the
-					// receiver type declaration. Substitute parameters for the
-					// current context.
-					// TODO(gri) should we assume now that bounds always exist?
-					//           (no bound == empty interface)
-					if bound != nil {
-						bound = check.subst(tname.pos, bound, smap)
-						tname.typ.(*_TypeParam).bound = bound
-					}
-				}
-			}
-		}
-	}
-
-	if tparams := typeparams.Get(ftyp); tparams != nil {
-		sig.tparams = check.collectTypeParams(tparams)
-		// Always type-check method type parameters but complain that they are not allowed.
-		// (A separate check is needed when type-checking interface method signatures because
-		// they don't have a receiver specification.)
-		if recvPar != nil {
-			check.errorf(tparams, _Todo, "methods cannot have type parameters")
-		}
-	}
-
-	// Value (non-type) parameters' scope starts in the function body. Use a temporary scope for their
-	// declarations and then squash that scope into the parent scope (and report any redeclarations at
-	// that time).
-	scope := NewScope(check.scope, token.NoPos, token.NoPos, "function body (temp. scope)")
-	recvList, _ := check.collectParams(scope, recvPar, recvTyp, false) // use rewritten receiver type, if any
-	params, variadic := check.collectParams(scope, ftyp.Params, nil, true)
-	results, _ := check.collectParams(scope, ftyp.Results, nil, false)
-	scope.squash(func(obj, alt Object) {
-		check.errorf(obj, _DuplicateDecl, "%s redeclared in this block", obj.Name())
-		check.reportAltDecl(alt)
-	})
-
-	if recvPar != nil {
-		// recv parameter list present (may be empty)
-		// spec: "The receiver is specified via an extra parameter section preceding the
-		// method name. That parameter section must declare a single parameter, the receiver."
-		var recv *Var
-		switch len(recvList) {
-		case 0:
-			// error reported by resolver
-			recv = NewParam(0, nil, "", Typ[Invalid]) // ignore recv below
-		default:
-			// more than one receiver
-			check.error(recvList[len(recvList)-1], _BadRecv, "method must have exactly one receiver")
-			fallthrough // continue with first receiver
-		case 1:
-			recv = recvList[0]
-		}
-
-		// TODO(gri) We should delay rtyp expansion to when we actually need the
-		//           receiver; thus all checks here should be delayed to later.
-		rtyp, _ := deref(recv.typ)
-		rtyp = expand(rtyp)
-
-		// spec: "The receiver type must be of the form T or *T where T is a type name."
-		// (ignore invalid types - error was reported before)
-		if t := rtyp; t != Typ[Invalid] {
-			var err string
-			if T := asNamed(t); T != nil {
-				// spec: "The type denoted by T is called the receiver base type; it must not
-				// be a pointer or interface type and it must be declared in the same package
-				// as the method."
-				if T.obj.pkg != check.pkg {
-					err = "type not defined in this package"
-				} else {
-					switch u := optype(T).(type) {
-					case *Basic:
-						// unsafe.Pointer is treated like a regular pointer
-						if u.kind == UnsafePointer {
-							err = "unsafe.Pointer"
-						}
-					case *Pointer, *Interface:
-						err = "pointer or interface type"
-					}
-				}
-			} else {
-				err = "basic or unnamed type"
-			}
-			if err != "" {
-				check.errorf(recv, _InvalidRecv, "invalid receiver %s (%s)", recv.typ, err)
-				// ok to continue
-			}
-		}
-		sig.recv = recv
-	}
-
-	sig.params = NewTuple(params...)
-	sig.results = NewTuple(results...)
-	sig.variadic = variadic
-}
-
 // goTypeName returns the Go type name for typ and
 // removes any occurrences of "types." from that name.
 func goTypeName(typ Type) string {
@@ -462,13 +272,10 @@
 			check.errorf(&x, _NotAType, "%s is not a type", &x)
 		}
 
-	case *ast.IndexExpr:
-		if typeparams.Enabled {
-			exprs := typeparams.UnpackExpr(e.Index)
-			return check.instantiatedType(e.X, exprs, def)
-		}
-		check.errorf(e0, _NotAType, "%s is not a type", e0)
-		check.use(e.X)
+	case *ast.IndexExpr, *ast.MultiIndexExpr:
+		ix := typeparams.UnpackIndexExpr(e)
+		// TODO(rfindley): type instantiation should require go1.18
+		return check.instantiatedType(ix.X, ix.Indices, def)
 
 	case *ast.ParenExpr:
 		// Generic types must be instantiated before they can be used in any form.
@@ -604,43 +411,32 @@
 	return Typ[Invalid]
 }
 
-func (check *Checker) instantiatedType(x ast.Expr, targs []ast.Expr, def *Named) Type {
-	b := check.genericType(x, true) // TODO(gri) what about cycles?
-	if b == Typ[Invalid] {
-		return b // error already reported
-	}
-	base := asNamed(b)
-	if base == nil {
-		unreachable() // should have been caught by genericType
+func (check *Checker) instantiatedType(x ast.Expr, targsx []ast.Expr, def *Named) Type {
+	base := check.genericType(x, true)
+	if base == Typ[Invalid] {
+		return base // error already reported
 	}
 
-	// create a new type instance rather than instantiate the type
-	// TODO(gri) should do argument number check here rather than
-	//           when instantiating the type?
-	typ := new(instance)
-	def.setUnderlying(typ)
-
-	typ.check = check
-	typ.pos = x.Pos()
-	typ.base = base
-
-	// evaluate arguments (always)
-	typ.targs = check.typeList(targs)
-	if typ.targs == nil {
+	// evaluate arguments
+	targs := check.typeList(targsx)
+	if targs == nil {
 		def.setUnderlying(Typ[Invalid]) // avoid later errors due to lazy instantiation
 		return Typ[Invalid]
 	}
 
-	// determine argument positions (for error reporting)
-	typ.poslist = make([]token.Pos, len(targs))
-	for i, arg := range targs {
-		typ.poslist[i] = arg.Pos()
+	// determine argument positions
+	posList := make([]token.Pos, len(targs))
+	for i, arg := range targsx {
+		posList[i] = arg.Pos()
 	}
 
+	typ := check.InstantiateLazy(x.Pos(), base, targs, posList, true)
+	def.setUnderlying(typ)
+
 	// make sure we check instantiation works at least once
 	// and that the resulting type is valid
 	check.later(func() {
-		t := typ.expand()
+		t := expand(typ)
 		check.validType(t, nil)
 	})
 
@@ -689,518 +485,3 @@
 	}
 	return res
 }
-
-// collectParams declares the parameters of list in scope and returns the corresponding
-// variable list. If type0 != nil, it is used instead of the first type in list.
-func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, type0 ast.Expr, variadicOk bool) (params []*Var, variadic bool) {
-	if list == nil {
-		return
-	}
-
-	var named, anonymous bool
-	for i, field := range list.List {
-		ftype := field.Type
-		if i == 0 && type0 != nil {
-			ftype = type0
-		}
-		if t, _ := ftype.(*ast.Ellipsis); t != nil {
-			ftype = t.Elt
-			if variadicOk && i == len(list.List)-1 && len(field.Names) <= 1 {
-				variadic = true
-			} else {
-				check.softErrorf(t, _MisplacedDotDotDot, "can only use ... with final parameter in list")
-				// ignore ... and continue
-			}
-		}
-		typ := check.varType(ftype)
-		// The parser ensures that f.Tag is nil and we don't
-		// care if a constructed AST contains a non-nil tag.
-		if len(field.Names) > 0 {
-			// named parameter
-			for _, name := range field.Names {
-				if name.Name == "" {
-					check.invalidAST(name, "anonymous parameter")
-					// ok to continue
-				}
-				par := NewParam(name.Pos(), check.pkg, name.Name, typ)
-				check.declare(scope, name, par, scope.pos)
-				params = append(params, par)
-			}
-			named = true
-		} else {
-			// anonymous parameter
-			par := NewParam(ftype.Pos(), check.pkg, "", typ)
-			check.recordImplicit(field, par)
-			params = append(params, par)
-			anonymous = true
-		}
-	}
-
-	if named && anonymous {
-		check.invalidAST(list, "list contains both named and anonymous parameters")
-		// ok to continue
-	}
-
-	// For a variadic function, change the last parameter's type from T to []T.
-	// Since we type-checked T rather than ...T, we also need to retro-actively
-	// record the type for ...T.
-	if variadic {
-		last := params[len(params)-1]
-		last.typ = &Slice{elem: last.typ}
-		check.recordTypeAndValue(list.List[len(list.List)-1].Type, typexpr, last.typ, nil)
-	}
-
-	return
-}
-
-func (check *Checker) declareInSet(oset *objset, pos token.Pos, obj Object) bool {
-	if alt := oset.insert(obj); alt != nil {
-		check.errorf(atPos(pos), _DuplicateDecl, "%s redeclared", obj.Name())
-		check.reportAltDecl(alt)
-		return false
-	}
-	return true
-}
-
-func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, def *Named) {
-	var tlist *ast.Ident // "type" name of first entry in a type list declaration
-	var types []ast.Expr
-	for _, f := range iface.Methods.List {
-		if len(f.Names) > 0 {
-			// We have a method with name f.Names[0], or a type
-			// of a type list (name.Name == "type").
-			// (The parser ensures that there's only one method
-			// and we don't care if a constructed AST has more.)
-			name := f.Names[0]
-			if name.Name == "_" {
-				check.errorf(name, _BlankIfaceMethod, "invalid method name _")
-				continue // ignore
-			}
-
-			if name.Name == "type" {
-				// Always collect all type list entries, even from
-				// different type lists, under the assumption that
-				// the author intended to include all types.
-				types = append(types, f.Type)
-				if tlist != nil && tlist != name {
-					check.errorf(name, _Todo, "cannot have multiple type lists in an interface")
-				}
-				tlist = name
-				continue
-			}
-
-			typ := check.typ(f.Type)
-			sig, _ := typ.(*Signature)
-			if sig == nil {
-				if typ != Typ[Invalid] {
-					check.invalidAST(f.Type, "%s is not a method signature", typ)
-				}
-				continue // ignore
-			}
-
-			// Always type-check method type parameters but complain if they are not enabled.
-			// (This extra check is needed here because interface method signatures don't have
-			// a receiver specification.)
-			if sig.tparams != nil {
-				var at positioner = f.Type
-				if tparams := typeparams.Get(f.Type); tparams != nil {
-					at = tparams
-				}
-				check.errorf(at, _Todo, "methods cannot have type parameters")
-			}
-
-			// use named receiver type if available (for better error messages)
-			var recvTyp Type = ityp
-			if def != nil {
-				recvTyp = def
-			}
-			sig.recv = NewVar(name.Pos(), check.pkg, "", recvTyp)
-
-			m := NewFunc(name.Pos(), check.pkg, name.Name, sig)
-			check.recordDef(name, m)
-			ityp.methods = append(ityp.methods, m)
-		} else {
-			// We have an embedded type. completeInterface will
-			// eventually verify that we have an interface.
-			ityp.embeddeds = append(ityp.embeddeds, check.typ(f.Type))
-			check.posMap[ityp] = append(check.posMap[ityp], f.Type.Pos())
-		}
-	}
-
-	// type constraints
-	ityp.types = _NewSum(check.collectTypeConstraints(iface.Pos(), types))
-
-	if len(ityp.methods) == 0 && ityp.types == nil && len(ityp.embeddeds) == 0 {
-		// empty interface
-		ityp.allMethods = markComplete
-		return
-	}
-
-	// sort for API stability
-	sortMethods(ityp.methods)
-	sortTypes(ityp.embeddeds)
-
-	check.later(func() { check.completeInterface(iface.Pos(), ityp) })
-}
-
-func (check *Checker) completeInterface(pos token.Pos, ityp *Interface) {
-	if ityp.allMethods != nil {
-		return
-	}
-
-	// completeInterface may be called via the LookupFieldOrMethod,
-	// MissingMethod, Identical, or IdenticalIgnoreTags external API
-	// in which case check will be nil. In this case, type-checking
-	// must be finished and all interfaces should have been completed.
-	if check == nil {
-		panic("internal error: incomplete interface")
-	}
-
-	if trace {
-		// Types don't generally have position information.
-		// If we don't have a valid pos provided, try to use
-		// one close enough.
-		if !pos.IsValid() && len(ityp.methods) > 0 {
-			pos = ityp.methods[0].pos
-		}
-
-		check.trace(pos, "complete %s", ityp)
-		check.indent++
-		defer func() {
-			check.indent--
-			check.trace(pos, "=> %s (methods = %v, types = %v)", ityp, ityp.allMethods, ityp.allTypes)
-		}()
-	}
-
-	// An infinitely expanding interface (due to a cycle) is detected
-	// elsewhere (Checker.validType), so here we simply assume we only
-	// have valid interfaces. Mark the interface as complete to avoid
-	// infinite recursion if the validType check occurs later for some
-	// reason.
-	ityp.allMethods = markComplete
-
-	// Methods of embedded interfaces are collected unchanged; i.e., the identity
-	// of a method I.m's Func Object of an interface I is the same as that of
-	// the method m in an interface that embeds interface I. On the other hand,
-	// if a method is embedded via multiple overlapping embedded interfaces, we
-	// don't provide a guarantee which "original m" got chosen for the embedding
-	// interface. See also issue #34421.
-	//
-	// If we don't care to provide this identity guarantee anymore, instead of
-	// reusing the original method in embeddings, we can clone the method's Func
-	// Object and give it the position of a corresponding embedded interface. Then
-	// we can get rid of the mpos map below and simply use the cloned method's
-	// position.
-
-	var seen objset
-	var methods []*Func
-	mpos := make(map[*Func]token.Pos) // method specification or method embedding position, for good error messages
-	addMethod := func(pos token.Pos, m *Func, explicit bool) {
-		switch other := seen.insert(m); {
-		case other == nil:
-			methods = append(methods, m)
-			mpos[m] = pos
-		case explicit:
-			check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
-			check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
-		default:
-			// We have a duplicate method name in an embedded (not explicitly declared) method.
-			// Check method signatures after all types are computed (issue #33656).
-			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
-			// error here as well (even though we could do it eagerly) because it's the same
-			// error message.
-			check.later(func() {
-				if !check.allowVersion(m.pkg, 1, 14) || !check.identical(m.typ, other.Type()) {
-					check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
-					check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
-				}
-			})
-		}
-	}
-
-	for _, m := range ityp.methods {
-		addMethod(m.pos, m, true)
-	}
-
-	// collect types
-	allTypes := ityp.types
-
-	posList := check.posMap[ityp]
-	for i, typ := range ityp.embeddeds {
-		pos := posList[i] // embedding position
-		utyp := under(typ)
-		etyp := asInterface(utyp)
-		if etyp == nil {
-			if utyp != Typ[Invalid] {
-				var format string
-				if _, ok := utyp.(*_TypeParam); ok {
-					format = "%s is a type parameter, not an interface"
-				} else {
-					format = "%s is not an interface"
-				}
-				// TODO: correct error code.
-				check.errorf(atPos(pos), _InvalidIfaceEmbed, format, typ)
-			}
-			continue
-		}
-		check.completeInterface(pos, etyp)
-		for _, m := range etyp.allMethods {
-			addMethod(pos, m, false) // use embedding position pos rather than m.pos
-		}
-		allTypes = intersect(allTypes, etyp.allTypes)
-	}
-
-	if methods != nil {
-		sort.Sort(byUniqueMethodName(methods))
-		ityp.allMethods = methods
-	}
-	ityp.allTypes = allTypes
-}
-
-// intersect computes the intersection of the types x and y.
-// Note: A incomming nil type stands for the top type. A top
-// type result is returned as nil.
-func intersect(x, y Type) (r Type) {
-	defer func() {
-		if r == theTop {
-			r = nil
-		}
-	}()
-
-	switch {
-	case x == theBottom || y == theBottom:
-		return theBottom
-	case x == nil || x == theTop:
-		return y
-	case y == nil || x == theTop:
-		return x
-	}
-
-	xtypes := unpackType(x)
-	ytypes := unpackType(y)
-	// Compute the list rtypes which includes only
-	// types that are in both xtypes and ytypes.
-	// Quadratic algorithm, but good enough for now.
-	// TODO(gri) fix this
-	var rtypes []Type
-	for _, x := range xtypes {
-		if includes(ytypes, x) {
-			rtypes = append(rtypes, x)
-		}
-	}
-
-	if rtypes == nil {
-		return theBottom
-	}
-	return _NewSum(rtypes)
-}
-
-func sortTypes(list []Type) {
-	sort.Stable(byUniqueTypeName(list))
-}
-
-// byUniqueTypeName named type lists can be sorted by their unique type names.
-type byUniqueTypeName []Type
-
-func (a byUniqueTypeName) Len() int           { return len(a) }
-func (a byUniqueTypeName) Less(i, j int) bool { return sortName(a[i]) < sortName(a[j]) }
-func (a byUniqueTypeName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-
-func sortName(t Type) string {
-	if named := asNamed(t); named != nil {
-		return named.obj.Id()
-	}
-	return ""
-}
-
-func sortMethods(list []*Func) {
-	sort.Sort(byUniqueMethodName(list))
-}
-
-func assertSortedMethods(list []*Func) {
-	if !debug {
-		panic("internal error: assertSortedMethods called outside debug mode")
-	}
-	if !sort.IsSorted(byUniqueMethodName(list)) {
-		panic("internal error: methods not sorted")
-	}
-}
-
-// byUniqueMethodName method lists can be sorted by their unique method names.
-type byUniqueMethodName []*Func
-
-func (a byUniqueMethodName) Len() int           { return len(a) }
-func (a byUniqueMethodName) Less(i, j int) bool { return a[i].Id() < a[j].Id() }
-func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
-
-func (check *Checker) tag(t *ast.BasicLit) string {
-	if t != nil {
-		if t.Kind == token.STRING {
-			if val, err := strconv.Unquote(t.Value); err == nil {
-				return val
-			}
-		}
-		check.invalidAST(t, "incorrect tag syntax: %q", t.Value)
-	}
-	return ""
-}
-
-func (check *Checker) structType(styp *Struct, e *ast.StructType) {
-	list := e.Fields
-	if list == nil {
-		return
-	}
-
-	// struct fields and tags
-	var fields []*Var
-	var tags []string
-
-	// for double-declaration checks
-	var fset objset
-
-	// current field typ and tag
-	var typ Type
-	var tag string
-	add := func(ident *ast.Ident, embedded bool, pos token.Pos) {
-		if tag != "" && tags == nil {
-			tags = make([]string, len(fields))
-		}
-		if tags != nil {
-			tags = append(tags, tag)
-		}
-
-		name := ident.Name
-		fld := NewField(pos, check.pkg, name, typ, embedded)
-		// spec: "Within a struct, non-blank field names must be unique."
-		if name == "_" || check.declareInSet(&fset, pos, fld) {
-			fields = append(fields, fld)
-			check.recordDef(ident, fld)
-		}
-	}
-
-	// addInvalid adds an embedded field of invalid type to the struct for
-	// fields with errors; this keeps the number of struct fields in sync
-	// with the source as long as the fields are _ or have different names
-	// (issue #25627).
-	addInvalid := func(ident *ast.Ident, pos token.Pos) {
-		typ = Typ[Invalid]
-		tag = ""
-		add(ident, true, pos)
-	}
-
-	for _, f := range list.List {
-		typ = check.varType(f.Type)
-		tag = check.tag(f.Tag)
-		if len(f.Names) > 0 {
-			// named fields
-			for _, name := range f.Names {
-				add(name, false, name.Pos())
-			}
-		} else {
-			// embedded field
-			// spec: "An embedded type must be specified as a type name T or as a
-			// pointer to a non-interface type name *T, and T itself may not be a
-			// pointer type."
-			pos := f.Type.Pos()
-			name := embeddedFieldIdent(f.Type)
-			if name == nil {
-				// TODO(rFindley): using invalidAST here causes test failures (all
-				//                 errors should have codes). Clean this up.
-				check.errorf(f.Type, _Todo, "invalid AST: embedded field type %s has no name", f.Type)
-				name = ast.NewIdent("_")
-				name.NamePos = pos
-				addInvalid(name, pos)
-				continue
-			}
-			add(name, true, pos)
-
-			// Because we have a name, typ must be of the form T or *T, where T is the name
-			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
-			// We must delay this check to the end because we don't want to instantiate
-			// (via under(t)) a possibly incomplete type.
-
-			// for use in the closure below
-			embeddedTyp := typ
-			embeddedPos := f.Type
-
-			check.later(func() {
-				t, isPtr := deref(embeddedTyp)
-				switch t := optype(t).(type) {
-				case *Basic:
-					if t == Typ[Invalid] {
-						// error was reported before
-						return
-					}
-					// unsafe.Pointer is treated like a regular pointer
-					if t.kind == UnsafePointer {
-						check.errorf(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be unsafe.Pointer")
-					}
-				case *Pointer:
-					check.errorf(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a pointer")
-				case *Interface:
-					if isPtr {
-						check.errorf(embeddedPos, _InvalidPtrEmbed, "embedded field type cannot be a pointer to an interface")
-					}
-				}
-			})
-		}
-	}
-
-	styp.fields = fields
-	styp.tags = tags
-}
-
-func embeddedFieldIdent(e ast.Expr) *ast.Ident {
-	switch e := e.(type) {
-	case *ast.Ident:
-		return e
-	case *ast.StarExpr:
-		// *T is valid, but **T is not
-		if _, ok := e.X.(*ast.StarExpr); !ok {
-			return embeddedFieldIdent(e.X)
-		}
-	case *ast.SelectorExpr:
-		return e.Sel
-	case *ast.IndexExpr:
-		return embeddedFieldIdent(e.X)
-	}
-	return nil // invalid embedded field
-}
-
-func (check *Checker) collectTypeConstraints(pos token.Pos, types []ast.Expr) []Type {
-	list := make([]Type, 0, len(types)) // assume all types are correct
-	for _, texpr := range types {
-		if texpr == nil {
-			check.invalidAST(atPos(pos), "missing type constraint")
-			continue
-		}
-		list = append(list, check.varType(texpr))
-	}
-
-	// Ensure that each type is only present once in the type list.  Types may be
-	// interfaces, which may not be complete yet. It's ok to do this check at the
-	// end because it's not a requirement for correctness of the code.
-	// Note: This is a quadratic algorithm, but type lists tend to be short.
-	check.later(func() {
-		for i, t := range list {
-			if t := asInterface(t); t != nil {
-				check.completeInterface(types[i].Pos(), t)
-			}
-			if includes(list[:i], t) {
-				check.softErrorf(types[i], _Todo, "duplicate type %s in type list", t)
-			}
-		}
-	})
-
-	return list
-}
-
-// includes reports whether typ is in list.
-func includes(list []Type, typ Type) bool {
-	for _, e := range list {
-		if Identical(typ, e) {
-			return true
-		}
-	}
-	return false
-}
diff --git a/src/go/types/unify.go b/src/go/types/unify.go
index db06e21..90a5cf7 100644
--- a/src/go/types/unify.go
+++ b/src/go/types/unify.go
@@ -8,7 +8,7 @@
 
 import (
 	"bytes"
-	"go/token"
+	"fmt"
 	"sort"
 )
 
@@ -38,7 +38,6 @@
 // and the respective types inferred for each type parameter.
 // A unifier is created by calling newUnifier.
 type unifier struct {
-	check *Checker
 	exact bool
 	x, y  tparamsList // x and y must initialized via tparamsList.init
 	types []Type      // inferred types, shared by x and y
@@ -49,8 +48,8 @@
 // exactly. If exact is not set, a named type's underlying type
 // is considered if unification would fail otherwise, and the
 // direction of channels is ignored.
-func newUnifier(check *Checker, exact bool) *unifier {
-	u := &unifier{check: check, exact: exact}
+func newUnifier(exact bool) *unifier {
+	u := &unifier{exact: exact}
 	u.x.unifier = u
 	u.y.unifier = u
 	return u
@@ -100,7 +99,7 @@
 	}
 	if debug {
 		for i, tpar := range tparams {
-			assert(i == tpar.typ.(*_TypeParam).index)
+			assert(i == tpar.typ.(*TypeParam).index)
 		}
 	}
 	d.tparams = tparams
@@ -148,10 +147,17 @@
 // If typ is a type parameter of d, index returns the type parameter index.
 // Otherwise, the result is < 0.
 func (d *tparamsList) index(typ Type) int {
-	if t, ok := typ.(*_TypeParam); ok {
-		if i := t.index; i < len(d.tparams) && d.tparams[i].typ == t {
-			return i
-		}
+	if tpar, ok := typ.(*TypeParam); ok {
+		return tparamIndex(d.tparams, tpar)
+	}
+	return -1
+}
+
+// If tpar is a type parameter in list, tparamIndex returns the type parameter index.
+// Otherwise, the result is < 0. tpar must not be nil.
+func tparamIndex(list []*TypeName, tpar *TypeParam) int {
+	if i := tpar.index; i < len(list) && list[i].typ == tpar {
+		return i
 	}
 	return -1
 }
@@ -352,25 +358,21 @@
 				u.nify(x.results, y.results, p)
 		}
 
-	case *_Sum:
-		// This should not happen with the current internal use of sum types.
-		panic("type inference across sum types not implemented")
+	case *Union:
+		panic("unimplemented: unification with type sets described by types")
 
 	case *Interface:
 		// Two interface types are identical if they have the same set of methods with
 		// the same names and identical function types. Lower-case method names from
 		// different packages are always different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			// If identical0 is called (indirectly) via an external API entry point
-			// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
-			// that case, interfaces are expected to be complete and lazy completion
-			// here is not needed.
-			if u.check != nil {
-				u.check.completeInterface(token.NoPos, x)
-				u.check.completeInterface(token.NoPos, y)
+			xset := x.typeSet()
+			yset := y.typeSet()
+			if !Identical(xset.types, yset.types) {
+				return false
 			}
-			a := x.allMethods
-			b := y.allMethods
+			a := xset.methods
+			b := yset.methods
 			if len(a) == len(b) {
 				// Interface types are the only types where cycles can occur
 				// that are not "terminated" via named types; and such cycles
@@ -448,21 +450,17 @@
 			}
 		}
 
-	case *_TypeParam:
+	case *TypeParam:
 		// Two type parameters (which are not part of the type parameters of the
 		// enclosing type as those are handled in the beginning of this function)
 		// are identical if they originate in the same declaration.
 		return x == y
 
-	// case *instance:
-	//	unreachable since types are expanded
-
 	case nil:
 		// avoid a crash in case of nil type
 
 	default:
-		u.check.dump("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams)
-		unreachable()
+		panic(fmt.Sprintf("### u.nify(%s, %s), u.x.tparams = %s", x, y, u.x.tparams))
 	}
 
 	return false
diff --git a/src/go/types/union.go b/src/go/types/union.go
new file mode 100644
index 0000000..a56f9d2
--- /dev/null
+++ b/src/go/types/union.go
@@ -0,0 +1,271 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package types
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// ----------------------------------------------------------------------------
+// API
+
+// A Union represents a union of terms.
+type Union struct {
+	terms []*term
+}
+
+// NewUnion returns a new Union type with the given terms (types[i], tilde[i]).
+// The lengths of both arguments must match. An empty union represents the set
+// of no types.
+func NewUnion(types []Type, tilde []bool) *Union { return newUnion(types, tilde) }
+
+func (u *Union) IsEmpty() bool           { return len(u.terms) == 0 }
+func (u *Union) NumTerms() int           { return len(u.terms) }
+func (u *Union) Term(i int) (Type, bool) { t := u.terms[i]; return t.typ, t.tilde }
+
+func (u *Union) Underlying() Type { return u }
+func (u *Union) String() string   { return TypeString(u, nil) }
+
+// ----------------------------------------------------------------------------
+// Implementation
+
+var emptyUnion = new(Union)
+
+func newUnion(types []Type, tilde []bool) *Union {
+	assert(len(types) == len(tilde))
+	if len(types) == 0 {
+		return emptyUnion
+	}
+	t := new(Union)
+	t.terms = make([]*term, len(types))
+	for i, typ := range types {
+		t.terms[i] = &term{tilde[i], typ}
+	}
+	return t
+}
+
+// is reports whether f returns true for all terms of u.
+func (u *Union) is(f func(*term) bool) bool {
+	if u.IsEmpty() {
+		return false
+	}
+	for _, t := range u.terms {
+		if !f(t) {
+			return false
+		}
+	}
+	return true
+}
+
+// underIs reports whether f returned true for the underlying types of all terms of u.
+func (u *Union) underIs(f func(Type) bool) bool {
+	if u.IsEmpty() {
+		return false
+	}
+	for _, t := range u.terms {
+		if !f(under(t.typ)) {
+			return false
+		}
+	}
+	return true
+}
+
+func parseUnion(check *Checker, tlist []ast.Expr) Type {
+	var types []Type
+	var tilde []bool
+	for _, x := range tlist {
+		t, d := parseTilde(check, x)
+		if len(tlist) == 1 && !d {
+			return t // single type
+		}
+		types = append(types, t)
+		tilde = append(tilde, d)
+	}
+
+	// Ensure that each type is only present once in the type list.
+	// It's ok to do this check later because it's not a requirement
+	// for correctness of the code.
+	// Note: This is a quadratic algorithm, but unions tend to be short.
+	check.later(func() {
+		for i, t := range types {
+			t := expand(t)
+			if t == Typ[Invalid] {
+				continue
+			}
+
+			x := tlist[i]
+			pos := x.Pos()
+			// We may not know the position of x if it was a typechecker-
+			// introduced ~T term for a type list entry T. Use the position
+			// of T instead.
+			// TODO(rfindley) remove this test once we don't support type lists anymore
+			if !pos.IsValid() {
+				if op, _ := x.(*ast.UnaryExpr); op != nil {
+					pos = op.X.Pos()
+				}
+			}
+
+			u := under(t)
+			f, _ := u.(*Interface)
+			if tilde[i] {
+				if f != nil {
+					check.errorf(x, _Todo, "invalid use of ~ (%s is an interface)", t)
+					continue // don't report another error for t
+				}
+
+				if !Identical(u, t) {
+					check.errorf(x, _Todo, "invalid use of ~ (underlying type of %s is %s)", t, u)
+					continue // don't report another error for t
+				}
+			}
+
+			// Stand-alone embedded interfaces are ok and are handled by the single-type case
+			// in the beginning. Embedded interfaces with tilde are excluded above. If we reach
+			// here, we must have at least two terms in the union.
+			if f != nil && !f.typeSet().IsTypeSet() {
+				check.errorf(atPos(pos), _Todo, "cannot use %s in union (interface contains methods)", t)
+				continue // don't report another error for t
+			}
+
+			// Complain about duplicate entries a|a, but also a|~a, and ~a|~a.
+			// TODO(gri) We should also exclude myint|~int since myint is included in ~int.
+			if includes(types[:i], t) {
+				// TODO(rfindley) this currently doesn't print the ~ if present
+				check.softErrorf(atPos(pos), _Todo, "duplicate term %s in union element", t)
+			}
+		}
+	})
+
+	return newUnion(types, tilde)
+}
+
+func parseTilde(check *Checker, x ast.Expr) (typ Type, tilde bool) {
+	if op, _ := x.(*ast.UnaryExpr); op != nil && op.Op == token.TILDE {
+		x = op.X
+		tilde = true
+	}
+	typ = check.anyType(x)
+	// embedding stand-alone type parameters is not permitted (issue #47127).
+	if _, ok := under(typ).(*TypeParam); ok {
+		check.error(x, _Todo, "cannot embed a type parameter")
+		typ = Typ[Invalid]
+	}
+	return
+}
+
+// intersect computes the intersection of the types x and y,
+// A nil type stands for the set of all types; an empty union
+// stands for the set of no types.
+func intersect(x, y Type) (r Type) {
+	// If one of the types is nil (no restrictions)
+	// the result is the other type.
+	switch {
+	case x == nil:
+		return y
+	case y == nil:
+		return x
+	}
+
+	// Compute the terms which are in both x and y.
+	// TODO(gri) This is not correct as it may not always compute
+	//           the "largest" intersection. For instance, for
+	//           x = myInt|~int, y = ~int
+	//           we get the result myInt but we should get ~int.
+	xu, _ := x.(*Union)
+	yu, _ := y.(*Union)
+	switch {
+	case xu != nil && yu != nil:
+		return &Union{intersectTerms(xu.terms, yu.terms)}
+
+	case xu != nil:
+		if r, _ := xu.intersect(y, false); r != nil {
+			return y
+		}
+
+	case yu != nil:
+		if r, _ := yu.intersect(x, false); r != nil {
+			return x
+		}
+
+	default: // xu == nil && yu == nil
+		if Identical(x, y) {
+			return x
+		}
+	}
+
+	return emptyUnion
+}
+
+// includes reports whether typ is in list.
+func includes(list []Type, typ Type) bool {
+	for _, e := range list {
+		if Identical(typ, e) {
+			return true
+		}
+	}
+	return false
+}
+
+// intersect computes the intersection of the union u and term (y, yt)
+// and returns the intersection term, if any. Otherwise the result is
+// (nil, false).
+// TODO(gri) this needs to cleaned up/removed once we switch to lazy
+//           union type set computation.
+func (u *Union) intersect(y Type, yt bool) (Type, bool) {
+	under_y := under(y)
+	for _, x := range u.terms {
+		xt := x.tilde
+		// determine which types xx, yy to compare
+		xx := x.typ
+		if yt {
+			xx = under(xx)
+		}
+		yy := y
+		if xt {
+			yy = under_y
+		}
+		if Identical(xx, yy) {
+			//  T ∩  T =  T
+			//  T ∩ ~t =  T
+			// ~t ∩  T =  T
+			// ~t ∩ ~t = ~t
+			return xx, xt && yt
+		}
+	}
+	return nil, false
+}
+
+func identicalTerms(list1, list2 []*term) bool {
+	if len(list1) != len(list2) {
+		return false
+	}
+	// Every term in list1 must be in list2.
+	// Quadratic algorithm, but probably good enough for now.
+	// TODO(gri) we need a fast quick type ID/hash for all types.
+L:
+	for _, x := range list1 {
+		for _, y := range list2 {
+			if x.equal(y) {
+				continue L // x is in list2
+			}
+		}
+		return false
+	}
+	return true
+}
+
+func intersectTerms(list1, list2 []*term) (list []*term) {
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	for _, x := range list1 {
+		for _, y := range list2 {
+			if r := x.intersect(y); r != nil {
+				list = append(list, r)
+			}
+		}
+	}
+	return
+}
diff --git a/src/go/types/universe.go b/src/go/types/universe.go
index d7feb2c..83c54c8 100644
--- a/src/go/types/universe.go
+++ b/src/go/types/universe.go
@@ -8,7 +8,6 @@
 
 import (
 	"go/constant"
-	"go/internal/typeparams"
 	"go/token"
 	"strings"
 )
@@ -22,11 +21,12 @@
 var Unsafe *Package
 
 var (
-	universeIota  *Const
-	universeByte  *Basic // uint8 alias, but has name "byte"
-	universeRune  *Basic // int32 alias, but has name "rune"
-	universeAny   *Interface
-	universeError *Named
+	universeIota       Object
+	universeByte       Type // uint8 alias, but has name "byte"
+	universeRune       Type // int32 alias, but has name "rune"
+	universeAny        Object
+	universeError      Type
+	universeComparable Object
 )
 
 // Typ contains the predeclared *Basic types indexed by their
@@ -79,20 +79,30 @@
 		def(NewTypeName(token.NoPos, nil, t.name, t))
 	}
 
-	// any
-	// (Predeclared and entered into universe scope so we do all the
-	// usual checks; but removed again from scope later since it's
-	// only visible as constraint in a type parameter list.)
+	// type any = interface{}
 	def(NewTypeName(token.NoPos, nil, "any", &emptyInterface))
 
-	// Error has a nil package in its qualified name since it is in no package
+	// type error interface{ Error() string }
 	{
+		obj := NewTypeName(token.NoPos, nil, "error", nil)
+		obj.setColor(black)
 		res := NewVar(token.NoPos, nil, "", Typ[String])
-		sig := &Signature{results: NewTuple(res)}
+		sig := NewSignature(nil, nil, NewTuple(res), false)
 		err := NewFunc(token.NoPos, nil, "Error", sig)
-		typ := &Named{underlying: NewInterfaceType([]*Func{err}, nil).Complete()}
+		ityp := &Interface{obj, []*Func{err}, nil, nil, true, nil}
+		computeTypeSet(nil, token.NoPos, ityp) // prevent races due to lazy computation of tset
+		typ := NewNamed(obj, ityp, nil)
 		sig.recv = NewVar(token.NoPos, nil, "", typ)
-		def(NewTypeName(token.NoPos, nil, "error", typ))
+		def(obj)
+	}
+
+	// type comparable interface{ /* type set marked comparable */ }
+	{
+		obj := NewTypeName(token.NoPos, nil, "comparable", nil)
+		obj.setColor(black)
+		ityp := &Interface{obj, nil, nil, nil, true, &_TypeSet{true, nil, nil}}
+		NewNamed(obj, ityp, nil)
+		def(obj)
 	}
 }
 
@@ -202,33 +212,6 @@
 	def(newBuiltin(_Trace))
 }
 
-func defPredeclaredComparable() {
-	// The "comparable" interface can be imagined as defined like
-	//
-	// type comparable interface {
-	//         == () untyped bool
-	//         != () untyped bool
-	// }
-	//
-	// == and != cannot be user-declared but we can declare
-	// a magic method == and check for its presence when needed.
-
-	// Define interface { == () }. We don't care about the signature
-	// for == so leave it empty except for the receiver, which is
-	// set up later to match the usual interface method assumptions.
-	sig := new(Signature)
-	eql := NewFunc(token.NoPos, nil, "==", sig)
-	iface := NewInterfaceType([]*Func{eql}, nil).Complete()
-
-	// set up the defined type for the interface
-	obj := NewTypeName(token.NoPos, nil, "comparable", nil)
-	named := NewNamed(obj, iface, nil)
-	obj.color_ = black
-	sig.recv = NewVar(token.NoPos, nil, "", named) // complete == signature
-
-	def(obj)
-}
-
 func init() {
 	Universe = NewScope(nil, token.NoPos, token.NoPos, "universe")
 	Unsafe = NewPackage("unsafe", "unsafe")
@@ -238,18 +221,13 @@
 	defPredeclaredConsts()
 	defPredeclaredNil()
 	defPredeclaredFuncs()
-	if typeparams.Enabled {
-		defPredeclaredComparable()
-	}
 
-	universeIota = Universe.Lookup("iota").(*Const)
-	universeByte = Universe.Lookup("byte").(*TypeName).typ.(*Basic)
-	universeRune = Universe.Lookup("rune").(*TypeName).typ.(*Basic)
-	universeAny = Universe.Lookup("any").(*TypeName).typ.(*Interface)
-	universeError = Universe.Lookup("error").(*TypeName).typ.(*Named)
-
-	// "any" is only visible as constraint in a type parameter list
-	delete(Universe.elems, "any")
+	universeIota = Universe.Lookup("iota")
+	universeByte = Universe.Lookup("byte").Type()
+	universeRune = Universe.Lookup("rune").Type()
+	universeAny = Universe.Lookup("any")
+	universeError = Universe.Lookup("error").Type()
+	universeComparable = Universe.Lookup("comparable")
 }
 
 // Objects with names containing blanks are internal and not entered into
diff --git a/src/internal/abi/abi.go b/src/internal/abi/abi.go
index aaff9ce..eadff24 100644
--- a/src/internal/abi/abi.go
+++ b/src/internal/abi/abi.go
@@ -4,7 +4,10 @@
 
 package abi
 
-import "unsafe"
+import (
+	"internal/goarch"
+	"unsafe"
+)
 
 // RegArgs is a struct that has space for each argument
 // and return value register on the current architecture.
@@ -33,6 +36,46 @@
 	ReturnIsPtr IntArgRegBitmap
 }
 
+// IntRegArgAddr returns a pointer inside of r.Ints[reg] that is appropriately
+// offset for an argument of size argSize.
+//
+// argSize must be non-zero, fit in a register, and a power-of-two.
+//
+// This method is a helper for dealing with the endianness of different CPU
+// architectures, since sub-word-sized arguments in big endian architectures
+// need to be "aligned" to the upper edge of the register to be interpreted
+// by the CPU correctly.
+func (r *RegArgs) IntRegArgAddr(reg int, argSize uintptr) unsafe.Pointer {
+	if argSize > goarch.PtrSize || argSize == 0 || argSize&(argSize-1) != 0 {
+		panic("invalid argSize")
+	}
+	offset := uintptr(0)
+	if goarch.BigEndian {
+		offset = goarch.PtrSize - argSize
+	}
+	return unsafe.Pointer(uintptr(unsafe.Pointer(&r.Ints[reg])) + offset)
+}
+
+// FloatRegArgAddr returns a pointer inside of r.Floats[reg] that is appropriately
+// offset for an argument of size argSize.
+//
+// argSize must be non-zero, fit in a register, and a power-of-two.
+//
+// This method is a helper for dealing with the endianness of different CPU
+// architectures, since sub-word-sized arguments in big endian architectures
+// need to be "aligned" to the upper edge of the register to be interpreted
+// by the CPU correctly.
+func (r *RegArgs) FloatRegArgAddr(reg int, argSize uintptr) unsafe.Pointer {
+	if argSize > EffectiveFloatRegSize || argSize == 0 || argSize&(argSize-1) != 0 {
+		panic("invalid argSize")
+	}
+	offset := uintptr(0)
+	if goarch.BigEndian {
+		offset = EffectiveFloatRegSize - argSize
+	}
+	return unsafe.Pointer(uintptr(unsafe.Pointer(&r.Floats[reg])) + offset)
+}
+
 // IntArgRegBitmap is a bitmap large enough to hold one bit per
 // integer argument/return register.
 type IntArgRegBitmap [(IntArgRegs + 7) / 8]uint8
diff --git a/src/internal/abi/abi_amd64.go b/src/internal/abi/abi_amd64.go
index aff71f6..d3c5678 100644
--- a/src/internal/abi/abi_amd64.go
+++ b/src/internal/abi/abi_amd64.go
@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build goexperiment.regabireflect
-// +build goexperiment.regabireflect
-
 package abi
 
 const (
diff --git a/src/internal/abi/abi_arm64.go b/src/internal/abi/abi_arm64.go
new file mode 100644
index 0000000..7544d75
--- /dev/null
+++ b/src/internal/abi/abi_arm64.go
@@ -0,0 +1,20 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build goexperiment.regabireflect
+// +build goexperiment.regabireflect
+
+package abi
+
+const (
+	// See abi_generic.go.
+
+	// R0 - R15.
+	IntArgRegs = 16
+
+	// F0 - F15.
+	FloatArgRegs = 16
+
+	EffectiveFloatRegSize = 8
+)
diff --git a/src/internal/abi/abi_generic.go b/src/internal/abi/abi_generic.go
index 69400f9..e8f94f8 100644
--- a/src/internal/abi/abi_generic.go
+++ b/src/internal/abi/abi_generic.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !goexperiment.regabireflect
-// +build !goexperiment.regabireflect
+//go:build !goexperiment.regabireflect && !amd64
+// +build !goexperiment.regabireflect,!amd64
 
 package abi
 
diff --git a/src/internal/buildcfg/exp.go b/src/internal/buildcfg/exp.go
index 9a60253..384f2f9 100644
--- a/src/internal/buildcfg/exp.go
+++ b/src/internal/buildcfg/exp.go
@@ -46,13 +46,11 @@
 //
 // TODO(mdempsky): Move to internal/goexperiment.
 func ParseGOEXPERIMENT(goos, goarch, goexp string) (flags, baseline goexperiment.Flags, err error) {
-	regabiSupported := goarch == "amd64" && (goos == "android" || goos == "linux" || goos == "darwin" || goos == "windows")
+	regabiSupported := goarch == "amd64" || goarch == "arm64"
 
 	baseline = goexperiment.Flags{
 		RegabiWrappers: regabiSupported,
-		RegabiG:        regabiSupported,
 		RegabiReflect:  regabiSupported,
-		RegabiDefer:    regabiSupported,
 		RegabiArgs:     regabiSupported,
 	}
 
@@ -78,9 +76,7 @@
 		// do the right thing.
 		names["regabi"] = func(v bool) {
 			flags.RegabiWrappers = v
-			flags.RegabiG = v
 			flags.RegabiReflect = v
-			flags.RegabiDefer = v
 			flags.RegabiArgs = v
 		}
 
@@ -109,20 +105,20 @@
 		}
 	}
 
-	// regabi is only supported on amd64.
-	if goarch != "amd64" {
-		flags.RegabiWrappers = false
-		flags.RegabiG = false
+	// regabi is always enabled on amd64.
+	if goarch == "amd64" {
+		flags.RegabiWrappers = true
+		flags.RegabiReflect = true
+		flags.RegabiArgs = true
+	}
+	// regabi is only supported on amd64 and arm64.
+	if goarch != "amd64" && goarch != "arm64" {
 		flags.RegabiReflect = false
-		flags.RegabiDefer = false
 		flags.RegabiArgs = false
 	}
 	// Check regabi dependencies.
-	if flags.RegabiG && !flags.RegabiWrappers {
-		err = fmt.Errorf("GOEXPERIMENT regabig requires regabiwrappers")
-	}
-	if flags.RegabiArgs && !(flags.RegabiWrappers && flags.RegabiG && flags.RegabiReflect && flags.RegabiDefer) {
-		err = fmt.Errorf("GOEXPERIMENT regabiargs requires regabiwrappers,regabig,regabireflect,regabidefer")
+	if flags.RegabiArgs && !(flags.RegabiWrappers && flags.RegabiReflect) {
+		err = fmt.Errorf("GOEXPERIMENT regabiargs requires regabiwrappers,regabireflect")
 	}
 	return
 }
diff --git a/src/internal/bytealg/compare_amd64.s b/src/internal/bytealg/compare_amd64.s
index 8295acb..4ccaca5 100644
--- a/src/internal/bytealg/compare_amd64.s
+++ b/src/internal/bytealg/compare_amd64.s
@@ -6,7 +6,6 @@
 #include "textflag.h"
 
 TEXT ·Compare<ABIInternal>(SB),NOSPLIT,$0-56
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a_base (want in SI)
 	// BX = a_len  (want in BX)
 	// CX = a_cap  (unused)
@@ -15,17 +14,9 @@
 	// R8 = b_cap  (unused)
 	MOVQ	SI, DX
 	MOVQ	AX, SI
-#else
-	MOVQ	a_base+0(FP), SI
-	MOVQ	a_len+8(FP), BX
-	MOVQ	b_base+24(FP), DI
-	MOVQ	b_len+32(FP), DX
-	LEAQ	ret+48(FP), R9
-#endif
 	JMP	cmpbody<>(SB)
 
 TEXT runtime·cmpstring<ABIInternal>(SB),NOSPLIT,$0-40
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a_base (want in SI)
 	// BX = a_len  (want in BX)
 	// CX = b_base (want in DI)
@@ -33,13 +24,6 @@
 	MOVQ	AX, SI
 	MOVQ	DI, DX
 	MOVQ	CX, DI
-#else
-	MOVQ	a_base+0(FP), SI
-	MOVQ	a_len+8(FP), BX
-	MOVQ	b_base+16(FP), DI
-	MOVQ	b_len+24(FP), DX
-	LEAQ	ret+32(FP), R9
-#endif
 	JMP	cmpbody<>(SB)
 
 // input:
@@ -47,12 +31,8 @@
 //   DI = b
 //   BX = alen
 //   DX = blen
-#ifndef GOEXPERIMENT_regabiargs
-//   R9 = address of output word (stores -1/0/1 here)
-#else
 // output:
 //   AX = output (-1/0/1)
-#endif
 TEXT cmpbody<>(SB),NOSPLIT,$0-0
 	CMPQ	SI, DI
 	JEQ	allsame
@@ -100,9 +80,6 @@
 	CMPB	CX, (DI)(BX*1)
 	SETHI	AX
 	LEAQ	-1(AX*2), AX	// convert 1/0 to +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// 0 through 16 bytes left, alen>=8, blen>=8
@@ -128,9 +105,6 @@
 	SHRQ	CX, AX	// move a's bit to bottom
 	ANDQ	$1, AX	// mask bit
 	LEAQ	-1(AX*2), AX // 1/0 => +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// 0-7 bytes in common
@@ -169,9 +143,6 @@
 	SHRQ	CX, SI	// move a's bit to bottom
 	ANDQ	$1, SI	// mask bit
 	LEAQ	-1(SI*2), AX // 1/0 => +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 allsame:
@@ -181,9 +152,6 @@
 	SETGT	AX	// 1 if alen > blen
 	SETEQ	CX	// 1 if alen == blen
 	LEAQ	-1(CX)(AX*2), AX	// 1,0,-1 result
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// this works for >= 64 bytes of data.
diff --git a/src/internal/bytealg/compare_arm64.s b/src/internal/bytealg/compare_arm64.s
index 56d56f2..5a80207 100644
--- a/src/internal/bytealg/compare_arm64.s
+++ b/src/internal/bytealg/compare_arm64.s
@@ -5,65 +5,88 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-TEXT ·Compare(SB),NOSPLIT|NOFRAME,$0-56
-	MOVD	a_base+0(FP), R2
-	MOVD	a_len+8(FP), R0
-	MOVD	b_base+24(FP), R3
-	MOVD	b_len+32(FP), R1
+TEXT ·Compare<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-56
+#ifdef GOEXPERIMENT_regabiargs
+	// R0 = a_base (want in R0)
+	// R1 = a_len  (want in R1)
+	// R2 = a_cap  (unused)
+	// R3 = b_base (want in R2)
+	// R4 = b_len  (want in R3)
+	// R5 = b_cap  (unused)
+	MOVD	R3, R2
+	MOVD	R4, R3
+#else
+	MOVD	a_base+0(FP), R0
+	MOVD	a_len+8(FP), R1
+	MOVD	b_base+24(FP), R2
+	MOVD	b_len+32(FP), R3
 	MOVD	$ret+48(FP), R7
+#endif
 	B	cmpbody<>(SB)
 
-TEXT runtime·cmpstring(SB),NOSPLIT|NOFRAME,$0-40
-	MOVD	a_base+0(FP), R2
-	MOVD	a_len+8(FP), R0
-	MOVD	b_base+16(FP), R3
-	MOVD	b_len+24(FP), R1
+TEXT runtime·cmpstring<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-40
+#ifdef GOEXPERIMENT_regabiargs
+	// R0 = a_base
+	// R1 = a_len
+	// R2 = b_base
+	// R3 = b_len
+#else
+	MOVD	a_base+0(FP), R0
+	MOVD	a_len+8(FP), R1
+	MOVD	b_base+16(FP), R2
+	MOVD	b_len+24(FP), R3
 	MOVD	$ret+32(FP), R7
+#endif
 	B	cmpbody<>(SB)
 
 // On entry:
-// R0 is the length of a
-// R1 is the length of b
-// R2 points to the start of a
-// R3 points to the start of b
+// R0 points to the start of a
+// R1 is the length of a
+// R2 points to the start of b
+// R3 is the length of b
+#ifndef GOEXPERIMENT_regabiargs
 // R7 points to return value (-1/0/1 will be written here)
+#endif
 //
 // On exit:
+#ifdef GOEXPERIMENT_regabiargs
+// R0 is the result
+#endif
 // R4, R5, R6, R8, R9 and R10 are clobbered
 TEXT cmpbody<>(SB),NOSPLIT|NOFRAME,$0-0
-	CMP	R2, R3
+	CMP	R0, R2
 	BEQ	samebytes         // same starting pointers; compare lengths
-	CMP	R0, R1
-	CSEL	LT, R1, R0, R6    // R6 is min(R0, R1)
+	CMP	R1, R3
+	CSEL	LT, R3, R1, R6    // R6 is min(R1, R3)
 
 	CBZ	R6, samebytes
 	BIC	$0xf, R6, R10
 	CBZ	R10, small        // length < 16
-	ADD	R2, R10           // end of chunk16
+	ADD	R0, R10           // end of chunk16
 	// length >= 16
 chunk16_loop:
-	LDP.P	16(R2), (R4, R8)
-	LDP.P	16(R3), (R5, R9)
+	LDP.P	16(R0), (R4, R8)
+	LDP.P	16(R2), (R5, R9)
 	CMP	R4, R5
 	BNE	cmp
 	CMP	R8, R9
 	BNE	cmpnext
-	CMP	R10, R2
+	CMP	R10, R0
 	BNE	chunk16_loop
 	AND	$0xf, R6, R6
 	CBZ	R6, samebytes
 	SUBS	$8, R6
 	BLT	tail
 	// the length of tail > 8 bytes
-	MOVD.P	8(R2), R4
-	MOVD.P	8(R3), R5
+	MOVD.P	8(R0), R4
+	MOVD.P	8(R2), R5
 	CMP	R4, R5
 	BNE	cmp
 	SUB	$8, R6
 	// compare last 8 bytes
 tail:
-	MOVD	(R2)(R6), R4
-	MOVD	(R3)(R6), R5
+	MOVD	(R0)(R6), R4
+	MOVD	(R2)(R6), R5
 	CMP	R4, R5
 	BEQ	samebytes
 cmp:
@@ -71,52 +94,56 @@
 	REV	R5, R5
 	CMP	R4, R5
 ret:
-	MOVD	$1, R4
-	CNEG	HI, R4, R4
-	MOVD	R4, (R7)
+	MOVD	$1, R0
+	CNEG	HI, R0, R0
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	R0, (R7)
+#endif
 	RET
 small:
 	TBZ	$3, R6, lt_8
-	MOVD	(R2), R4
-	MOVD	(R3), R5
+	MOVD	(R0), R4
+	MOVD	(R2), R5
 	CMP	R4, R5
 	BNE	cmp
 	SUBS	$8, R6
 	BEQ	samebytes
+	ADD	$8, R0
 	ADD	$8, R2
-	ADD	$8, R3
 	SUB	$8, R6
 	B	tail
 lt_8:
 	TBZ	$2, R6, lt_4
-	MOVWU	(R2), R4
-	MOVWU	(R3), R5
+	MOVWU	(R0), R4
+	MOVWU	(R2), R5
 	CMPW	R4, R5
 	BNE	cmp
 	SUBS	$4, R6
 	BEQ	samebytes
+	ADD	$4, R0
 	ADD	$4, R2
-	ADD	$4, R3
 lt_4:
 	TBZ	$1, R6, lt_2
-	MOVHU	(R2), R4
-	MOVHU	(R3), R5
+	MOVHU	(R0), R4
+	MOVHU	(R2), R5
 	CMPW	R4, R5
 	BNE	cmp
+	ADD	$2, R0
 	ADD	$2, R2
-	ADD	$2, R3
 lt_2:
 	TBZ	$0, R6, samebytes
 one:
-	MOVBU	(R2), R4
-	MOVBU	(R3), R5
+	MOVBU	(R0), R4
+	MOVBU	(R2), R5
 	CMPW	R4, R5
 	BNE	ret
 samebytes:
-	CMP	R1, R0
-	CSET	NE, R4
-	CNEG	LO, R4, R4
-	MOVD	R4, (R7)
+	CMP	R3, R1
+	CSET	NE, R0
+	CNEG	LO, R0, R0
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	R0, (R7)
+#endif
 	RET
 cmpnext:
 	REV	R8, R4
diff --git a/src/internal/bytealg/equal_amd64.s b/src/internal/bytealg/equal_amd64.s
index 6f12d2a..dd46e2e 100644
--- a/src/internal/bytealg/equal_amd64.s
+++ b/src/internal/bytealg/equal_amd64.s
@@ -7,7 +7,6 @@
 
 // memequal(a, b unsafe.Pointer, size uintptr) bool
 TEXT runtime·memequal<ABIInternal>(SB),NOSPLIT,$0-25
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a    (want in SI)
 	// BX = b    (want in DI)
 	// CX = size (want in BX)
@@ -20,22 +19,9 @@
 	MOVQ	BX, DI
 	MOVQ	CX, BX
 	JMP	memeqbody<>(SB)
-#else
-	MOVQ	a+0(FP), SI
-	MOVQ	b+8(FP), DI
-	CMPQ	SI, DI
-	JEQ	eq
-	MOVQ	size+16(FP), BX
-	LEAQ	ret+24(FP), AX
-	JMP	memeqbody<>(SB)
-eq:
-	MOVB	$1, ret+24(FP)
-	RET
-#endif
 
 // memequal_varlen(a, b unsafe.Pointer) bool
 TEXT runtime·memequal_varlen<ABIInternal>(SB),NOSPLIT,$0-17
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a       (want in SI)
 	// BX = b       (want in DI)
 	// 8(DX) = size (want in BX)
@@ -48,29 +34,13 @@
 	MOVQ	BX, DI
 	MOVQ	8(DX), BX    // compiler stores size at offset 8 in the closure
 	JMP	memeqbody<>(SB)
-#else
-	MOVQ	a+0(FP), SI
-	MOVQ	b+8(FP), DI
-	CMPQ	SI, DI
-	JEQ	eq
-	MOVQ	8(DX), BX    // compiler stores size at offset 8 in the closure
-	LEAQ	ret+16(FP), AX
-	JMP	memeqbody<>(SB)
-eq:
-	MOVB	$1, ret+16(FP)
-	RET
-#endif
 
 // Input:
 //   a in SI
 //   b in DI
 //   count in BX
-#ifndef GOEXPERIMENT_regabiargs
-//   address of result byte in AX
-#else
 // Output:
 //   result in AX
-#endif
 TEXT memeqbody<>(SB),NOSPLIT,$0-0
 	CMPQ	BX, $8
 	JB	small
@@ -104,11 +74,7 @@
 	SUBQ	$64, BX
 	CMPL	DX, $0xffff
 	JEQ	hugeloop
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 	// 64 bytes at a time using ymm registers
@@ -129,11 +95,7 @@
 	CMPL	DX, $0xffffffff
 	JEQ	hugeloop_avx2
 	VZEROUPPER
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 bigloop_avx2:
@@ -150,11 +112,7 @@
 	SUBQ	$8, BX
 	CMPQ	CX, DX
 	JEQ	bigloop
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 	// remaining 0-8 bytes
@@ -162,11 +120,7 @@
 	MOVQ	-8(SI)(BX*1), CX
 	MOVQ	-8(DI)(BX*1), DX
 	CMPQ	CX, DX
-#ifdef GOEXPERIMENT_regabiargs
 	SETEQ	AX
-#else
-	SETEQ	(AX)
-#endif
 	RET
 
 small:
@@ -201,10 +155,5 @@
 	SUBQ	SI, DI
 	SHLQ	CX, DI
 equal:
-#ifdef GOEXPERIMENT_regabiargs
 	SETEQ	AX
-#else
-	SETEQ	(AX)
-#endif
 	RET
-
diff --git a/src/internal/bytealg/equal_arm64.s b/src/internal/bytealg/equal_arm64.s
index 01aa7b7..cf5cf54 100644
--- a/src/internal/bytealg/equal_arm64.s
+++ b/src/internal/bytealg/equal_arm64.s
@@ -6,58 +6,70 @@
 #include "textflag.h"
 
 // memequal(a, b unsafe.Pointer, size uintptr) bool
-TEXT runtime·memequal(SB),NOSPLIT|NOFRAME,$0-25
-	MOVD	size+16(FP), R1
+TEXT runtime·memequal<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-25
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	size+16(FP), R2
+#endif
 	// short path to handle 0-byte case
-	CBZ	R1, equal
+	CBZ	R2, equal
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	a+0(FP), R0
-	MOVD	b+8(FP), R2
+	MOVD	b+8(FP), R1
 	MOVD	$ret+24(FP), R8
+#endif
 	B	memeqbody<>(SB)
 equal:
 	MOVD	$1, R0
+#ifndef GOEXPERIMENT_regabiargs
 	MOVB	R0, ret+24(FP)
+#endif
 	RET
 
 // memequal_varlen(a, b unsafe.Pointer) bool
-TEXT runtime·memequal_varlen(SB),NOSPLIT,$40-17
-	MOVD	a+0(FP), R3
-	MOVD	b+8(FP), R4
-	CMP	R3, R4
+TEXT runtime·memequal_varlen<ABIInternal>(SB),NOSPLIT,$0-17
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	a+0(FP), R0
+	MOVD	b+8(FP), R1
+#endif
+	CMP	R0, R1
 	BEQ	eq
-	MOVD	8(R26), R5    // compiler stores size at offset 8 in the closure
-	CBZ	R5, eq
-	MOVD	R3, 8(RSP)
-	MOVD	R4, 16(RSP)
-	MOVD	R5, 24(RSP)
-	BL	runtime·memequal(SB)
-	MOVBU	32(RSP), R3
-	MOVB	R3, ret+16(FP)
-	RET
+	MOVD	8(R26), R2    // compiler stores size at offset 8 in the closure
+	CBZ	R2, eq
+#ifndef GOEXPERIMENT_regabiargs
+	MOVD	$ret+16(FP), R8
+#endif
+	B	memeqbody<>(SB)
 eq:
-	MOVD	$1, R3
-	MOVB	R3, ret+16(FP)
+	MOVD	$1, R0
+#ifndef GOEXPERIMENT_regabiargs
+	MOVB	R0, ret+16(FP)
+#endif
 	RET
 
 // input:
 // R0: pointer a
-// R1: data len
-// R2: pointer b
+// R1: pointer b
+// R2: data len
+#ifdef GOEXPERIMENT_regabiargs
+// at return: result in R0
+#else
 // R8: address to put result
+#endif
+
 TEXT memeqbody<>(SB),NOSPLIT,$0
-	CMP	$1, R1
+	CMP	$1, R2
 	// handle 1-byte special case for better performance
 	BEQ	one
-	CMP	$16, R1
+	CMP	$16, R2
 	// handle specially if length < 16
 	BLO	tail
-	BIC	$0x3f, R1, R3
+	BIC	$0x3f, R2, R3
 	CBZ	R3, chunk16
 	// work with 64-byte chunks
 	ADD	R3, R0, R6	// end of chunks
 chunk64_loop:
 	VLD1.P	(R0), [V0.D2, V1.D2, V2.D2, V3.D2]
-	VLD1.P	(R2), [V4.D2, V5.D2, V6.D2, V7.D2]
+	VLD1.P	(R1), [V4.D2, V5.D2, V6.D2, V7.D2]
 	VCMEQ	V0.D2, V4.D2, V8.D2
 	VCMEQ	V1.D2, V5.D2, V9.D2
 	VCMEQ	V2.D2, V6.D2, V10.D2
@@ -71,66 +83,72 @@
 	CBZ	R4, not_equal
 	CBZ	R5, not_equal
 	BNE	chunk64_loop
-	AND	$0x3f, R1, R1
-	CBZ	R1, equal
+	AND	$0x3f, R2, R2
+	CBZ	R2, equal
 chunk16:
 	// work with 16-byte chunks
-	BIC	$0xf, R1, R3
+	BIC	$0xf, R2, R3
 	CBZ	R3, tail
 	ADD	R3, R0, R6	// end of chunks
 chunk16_loop:
 	LDP.P	16(R0), (R4, R5)
-	LDP.P	16(R2), (R7, R9)
+	LDP.P	16(R1), (R7, R9)
 	EOR	R4, R7
 	CBNZ	R7, not_equal
 	EOR	R5, R9
 	CBNZ	R9, not_equal
 	CMP	R0, R6
 	BNE	chunk16_loop
-	AND	$0xf, R1, R1
-	CBZ	R1, equal
+	AND	$0xf, R2, R2
+	CBZ	R2, equal
 tail:
 	// special compare of tail with length < 16
-	TBZ	$3, R1, lt_8
+	TBZ	$3, R2, lt_8
 	MOVD	(R0), R4
-	MOVD	(R2), R5
+	MOVD	(R1), R5
 	EOR	R4, R5
 	CBNZ	R5, not_equal
-	SUB	$8, R1, R6	// offset of the last 8 bytes
+	SUB	$8, R2, R6	// offset of the last 8 bytes
 	MOVD	(R0)(R6), R4
-	MOVD	(R2)(R6), R5
+	MOVD	(R1)(R6), R5
 	EOR	R4, R5
 	CBNZ	R5, not_equal
 	B	equal
 lt_8:
-	TBZ	$2, R1, lt_4
+	TBZ	$2, R2, lt_4
 	MOVWU	(R0), R4
-	MOVWU	(R2), R5
+	MOVWU	(R1), R5
 	EOR	R4, R5
 	CBNZ	R5, not_equal
-	SUB	$4, R1, R6	// offset of the last 4 bytes
+	SUB	$4, R2, R6	// offset of the last 4 bytes
 	MOVWU	(R0)(R6), R4
-	MOVWU	(R2)(R6), R5
+	MOVWU	(R1)(R6), R5
 	EOR	R4, R5
 	CBNZ	R5, not_equal
 	B	equal
 lt_4:
-	TBZ	$1, R1, lt_2
+	TBZ	$1, R2, lt_2
 	MOVHU.P	2(R0), R4
-	MOVHU.P	2(R2), R5
+	MOVHU.P	2(R1), R5
 	CMP	R4, R5
 	BNE	not_equal
 lt_2:
-	TBZ	$0, R1, equal
+	TBZ	$0, R2, equal
 one:
 	MOVBU	(R0), R4
-	MOVBU	(R2), R5
+	MOVBU	(R1), R5
 	CMP	R4, R5
 	BNE	not_equal
 equal:
 	MOVD	$1, R0
+#ifndef GOEXPERIMENT_regabiargs
 	MOVB	R0, (R8)
+#endif
 	RET
 not_equal:
+#ifdef GOEXPERIMENT_regabiargs
+	MOVB	ZR, R0
+#else
 	MOVB	ZR, (R8)
+#endif
 	RET
diff --git a/src/internal/goarch/gengoarch.go b/src/internal/goarch/gengoarch.go
new file mode 100644
index 0000000..af15518
--- /dev/null
+++ b/src/internal/goarch/gengoarch.go
@@ -0,0 +1,59 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+// +build ignore
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+var goarches []string
+
+func main() {
+	data, err := os.ReadFile("../../go/build/syslist.go")
+	if err != nil {
+		log.Fatal(err)
+	}
+	const goarchPrefix = `const goarchList = `
+	for _, line := range strings.Split(string(data), "\n") {
+		if strings.HasPrefix(line, goarchPrefix) {
+			text, err := strconv.Unquote(strings.TrimPrefix(line, goarchPrefix))
+			if err != nil {
+				log.Fatalf("parsing goarchList: %v", err)
+			}
+			goarches = strings.Fields(text)
+		}
+	}
+
+	for _, target := range goarches {
+		if target == "amd64p32" {
+			continue
+		}
+		var buf bytes.Buffer
+		fmt.Fprintf(&buf, "// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.\n\n")
+		fmt.Fprintf(&buf, "//go:build %s\n", target)
+		fmt.Fprintf(&buf, "// +build %s\n\n", target) // must explicitly include target for bootstrapping purposes
+		fmt.Fprintf(&buf, "package goarch\n\n")
+		fmt.Fprintf(&buf, "const GOARCH = `%s`\n\n", target)
+		for _, goarch := range goarches {
+			value := 0
+			if goarch == target {
+				value = 1
+			}
+			fmt.Fprintf(&buf, "const Is%s = %d\n", strings.Title(goarch), value)
+		}
+		err := os.WriteFile("zgoarch_"+target+".go", buf.Bytes(), 0666)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+}
diff --git a/src/runtime/internal/sys/arch.go b/src/internal/goarch/goarch.go
similarity index 74%
rename from src/runtime/internal/sys/arch.go
rename to src/internal/goarch/goarch.go
index 3c99a2f..921f5a2 100644
--- a/src/runtime/internal/sys/arch.go
+++ b/src/internal/goarch/goarch.go
@@ -1,8 +1,15 @@
-// Copyright 2014 The Go Authors. All rights reserved.
+// Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+// package goarch contains GOARCH-specific constants.
+package goarch
+
+// The next line makes 'go generate' write the zgoarch*.go files with
+// per-arch information, including constants named $GOARCH for every
+// GOARCH. The constant is 1 on the current system, 0 otherwise; multiplying
+// by them is useful for defining GOARCH-specific constants.
+//go:generate go run gengoarch.go
 
 type ArchFamilyType int
 
@@ -23,14 +30,11 @@
 // It is also the size of the machine's native word size (that is, 4 on 32-bit systems, 8 on 64-bit).
 const PtrSize = 4 << (^uintptr(0) >> 63)
 
-// AIX requires a larger stack for syscalls.
-const StackGuardMultiplier = StackGuardMultiplierDefault*(1-GoosAix) + 2*GoosAix
-
 // ArchFamily is the architecture family (AMD64, ARM, ...)
 const ArchFamily ArchFamilyType = _ArchFamily
 
 // BigEndian reports whether the architecture is big-endian.
-const BigEndian = GoarchArmbe|GoarchArm64be|GoarchMips|GoarchMips64|GoarchPpc|GoarchPpc64|GoarchS390|GoarchS390x|GoarchSparc|GoarchSparc64 == 1
+const BigEndian = IsArmbe|IsArm64be|IsMips|IsMips64|IsPpc|IsPpc64|IsS390|IsS390x|IsSparc|IsSparc64 == 1
 
 // DefaultPhysPageSize is the default physical page size.
 const DefaultPhysPageSize = _DefaultPhysPageSize
diff --git a/src/runtime/internal/sys/arch_386.go b/src/internal/goarch/goarch_386.go
similarity index 94%
rename from src/runtime/internal/sys/arch_386.go
rename to src/internal/goarch/goarch_386.go
index 1ebce34..c621421 100644
--- a/src/runtime/internal/sys/arch_386.go
+++ b/src/internal/goarch/goarch_386.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = I386
diff --git a/src/runtime/internal/sys/arch_amd64.go b/src/internal/goarch/goarch_amd64.go
similarity index 94%
rename from src/runtime/internal/sys/arch_amd64.go
rename to src/internal/goarch/goarch_amd64.go
index 7f003d0..911e3e7 100644
--- a/src/runtime/internal/sys/arch_amd64.go
+++ b/src/internal/goarch/goarch_amd64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = AMD64
diff --git a/src/runtime/internal/sys/arch_arm.go b/src/internal/goarch/goarch_arm.go
similarity index 94%
rename from src/runtime/internal/sys/arch_arm.go
rename to src/internal/goarch/goarch_arm.go
index ef2048b..a659171 100644
--- a/src/runtime/internal/sys/arch_arm.go
+++ b/src/internal/goarch/goarch_arm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = ARM
diff --git a/src/runtime/internal/sys/arch_arm64.go b/src/internal/goarch/goarch_arm64.go
similarity index 94%
rename from src/runtime/internal/sys/arch_arm64.go
rename to src/internal/goarch/goarch_arm64.go
index b9f2f7b..85d0b47 100644
--- a/src/runtime/internal/sys/arch_arm64.go
+++ b/src/internal/goarch/goarch_arm64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = ARM64
diff --git a/src/runtime/internal/sys/arch_mips.go b/src/internal/goarch/goarch_mips.go
similarity index 94%
rename from src/runtime/internal/sys/arch_mips.go
rename to src/internal/goarch/goarch_mips.go
index 4cb0eeb..59f3995 100644
--- a/src/runtime/internal/sys/arch_mips.go
+++ b/src/internal/goarch/goarch_mips.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = MIPS
diff --git a/src/runtime/internal/sys/arch_mips64.go b/src/internal/goarch/goarch_mips64.go
similarity index 94%
rename from src/runtime/internal/sys/arch_mips64.go
rename to src/internal/goarch/goarch_mips64.go
index 57636ac..9e4f827 100644
--- a/src/runtime/internal/sys/arch_mips64.go
+++ b/src/internal/goarch/goarch_mips64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = MIPS64
diff --git a/src/runtime/internal/sys/arch_mips64.go b/src/internal/goarch/goarch_mips64le.go
similarity index 94%
copy from src/runtime/internal/sys/arch_mips64.go
copy to src/internal/goarch/goarch_mips64le.go
index 57636ac..9e4f827 100644
--- a/src/runtime/internal/sys/arch_mips64.go
+++ b/src/internal/goarch/goarch_mips64le.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = MIPS64
diff --git a/src/runtime/internal/sys/arch_mipsle.go b/src/internal/goarch/goarch_mipsle.go
similarity index 94%
rename from src/runtime/internal/sys/arch_mipsle.go
rename to src/internal/goarch/goarch_mipsle.go
index 4240f5c..3e6642b 100644
--- a/src/runtime/internal/sys/arch_mipsle.go
+++ b/src/internal/goarch/goarch_mipsle.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = MIPS
diff --git a/src/runtime/internal/sys/arch_ppc64.go b/src/internal/goarch/goarch_ppc64.go
similarity index 94%
rename from src/runtime/internal/sys/arch_ppc64.go
rename to src/internal/goarch/goarch_ppc64.go
index 1869213..60cc846 100644
--- a/src/runtime/internal/sys/arch_ppc64.go
+++ b/src/internal/goarch/goarch_ppc64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = PPC64
diff --git a/src/runtime/internal/sys/arch_ppc64.go b/src/internal/goarch/goarch_ppc64le.go
similarity index 94%
copy from src/runtime/internal/sys/arch_ppc64.go
copy to src/internal/goarch/goarch_ppc64le.go
index 1869213..60cc846 100644
--- a/src/runtime/internal/sys/arch_ppc64.go
+++ b/src/internal/goarch/goarch_ppc64le.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = PPC64
diff --git a/src/runtime/internal/sys/arch_riscv64.go b/src/internal/goarch/goarch_riscv64.go
similarity index 94%
rename from src/runtime/internal/sys/arch_riscv64.go
rename to src/internal/goarch/goarch_riscv64.go
index 360d236..3b6da1e 100644
--- a/src/runtime/internal/sys/arch_riscv64.go
+++ b/src/internal/goarch/goarch_riscv64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = RISCV64
diff --git a/src/runtime/internal/sys/arch_s390x.go b/src/internal/goarch/goarch_s390x.go
similarity index 94%
rename from src/runtime/internal/sys/arch_s390x.go
rename to src/internal/goarch/goarch_s390x.go
index e33e0b7..20c5705 100644
--- a/src/runtime/internal/sys/arch_s390x.go
+++ b/src/internal/goarch/goarch_s390x.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = S390X
diff --git a/src/runtime/internal/sys/arch_wasm.go b/src/internal/goarch/goarch_wasm.go
similarity index 94%
rename from src/runtime/internal/sys/arch_wasm.go
rename to src/internal/goarch/goarch_wasm.go
index ee919ff..98618d6 100644
--- a/src/runtime/internal/sys/arch_wasm.go
+++ b/src/internal/goarch/goarch_wasm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package sys
+package goarch
 
 const (
 	_ArchFamily          = WASM
diff --git a/src/internal/goarch/zgoarch_386.go b/src/internal/goarch/zgoarch_386.go
new file mode 100644
index 0000000..2395b80
--- /dev/null
+++ b/src/internal/goarch/zgoarch_386.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build 386
+// +build 386
+
+package goarch
+
+const GOARCH = `386`
+
+const Is386 = 1
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_amd64.go b/src/internal/goarch/zgoarch_amd64.go
new file mode 100644
index 0000000..c301d27
--- /dev/null
+++ b/src/internal/goarch/zgoarch_amd64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build amd64
+// +build amd64
+
+package goarch
+
+const GOARCH = `amd64`
+
+const Is386 = 0
+const IsAmd64 = 1
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_arm.go b/src/internal/goarch/zgoarch_arm.go
new file mode 100644
index 0000000..4a5ff37
--- /dev/null
+++ b/src/internal/goarch/zgoarch_arm.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build arm
+// +build arm
+
+package goarch
+
+const GOARCH = `arm`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 1
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_arm64.go b/src/internal/goarch/zgoarch_arm64.go
new file mode 100644
index 0000000..840e280
--- /dev/null
+++ b/src/internal/goarch/zgoarch_arm64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build arm64
+// +build arm64
+
+package goarch
+
+const GOARCH = `arm64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 1
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_arm64be.go b/src/internal/goarch/zgoarch_arm64be.go
new file mode 100644
index 0000000..bdbe5fa
--- /dev/null
+++ b/src/internal/goarch/zgoarch_arm64be.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build arm64be
+// +build arm64be
+
+package goarch
+
+const GOARCH = `arm64be`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 1
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_armbe.go b/src/internal/goarch/zgoarch_armbe.go
new file mode 100644
index 0000000..36be514
--- /dev/null
+++ b/src/internal/goarch/zgoarch_armbe.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build armbe
+// +build armbe
+
+package goarch
+
+const GOARCH = `armbe`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 1
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_loong64.go b/src/internal/goarch/zgoarch_loong64.go
new file mode 100644
index 0000000..9465cf5
--- /dev/null
+++ b/src/internal/goarch/zgoarch_loong64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build loong64
+// +build loong64
+
+package goarch
+
+const GOARCH = `loong64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 1
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips.go b/src/internal/goarch/zgoarch_mips.go
new file mode 100644
index 0000000..e1458c0
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips
+// +build mips
+
+package goarch
+
+const GOARCH = `mips`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 1
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips64.go b/src/internal/goarch/zgoarch_mips64.go
new file mode 100644
index 0000000..7de345e
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips64
+// +build mips64
+
+package goarch
+
+const GOARCH = `mips64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 1
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips64le.go b/src/internal/goarch/zgoarch_mips64le.go
new file mode 100644
index 0000000..96b1c3c
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips64le.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips64le
+// +build mips64le
+
+package goarch
+
+const GOARCH = `mips64le`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 1
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips64p32.go b/src/internal/goarch/zgoarch_mips64p32.go
new file mode 100644
index 0000000..91d1f3c
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips64p32.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips64p32
+// +build mips64p32
+
+package goarch
+
+const GOARCH = `mips64p32`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 1
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mips64p32le.go b/src/internal/goarch/zgoarch_mips64p32le.go
new file mode 100644
index 0000000..18f2ef2
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mips64p32le.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mips64p32le
+// +build mips64p32le
+
+package goarch
+
+const GOARCH = `mips64p32le`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 1
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_mipsle.go b/src/internal/goarch/zgoarch_mipsle.go
new file mode 100644
index 0000000..4551de1
--- /dev/null
+++ b/src/internal/goarch/zgoarch_mipsle.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build mipsle
+// +build mipsle
+
+package goarch
+
+const GOARCH = `mipsle`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 1
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_ppc.go b/src/internal/goarch/zgoarch_ppc.go
new file mode 100644
index 0000000..ffed58c
--- /dev/null
+++ b/src/internal/goarch/zgoarch_ppc.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build ppc
+// +build ppc
+
+package goarch
+
+const GOARCH = `ppc`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 1
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_ppc64.go b/src/internal/goarch/zgoarch_ppc64.go
new file mode 100644
index 0000000..c369c74
--- /dev/null
+++ b/src/internal/goarch/zgoarch_ppc64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build ppc64
+// +build ppc64
+
+package goarch
+
+const GOARCH = `ppc64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 1
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_ppc64le.go b/src/internal/goarch/zgoarch_ppc64le.go
new file mode 100644
index 0000000..de5bae2
--- /dev/null
+++ b/src/internal/goarch/zgoarch_ppc64le.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build ppc64le
+// +build ppc64le
+
+package goarch
+
+const GOARCH = `ppc64le`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 1
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_riscv.go b/src/internal/goarch/zgoarch_riscv.go
new file mode 100644
index 0000000..07c9d81
--- /dev/null
+++ b/src/internal/goarch/zgoarch_riscv.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build riscv
+// +build riscv
+
+package goarch
+
+const GOARCH = `riscv`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 1
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_riscv64.go b/src/internal/goarch/zgoarch_riscv64.go
new file mode 100644
index 0000000..24e6ef3
--- /dev/null
+++ b/src/internal/goarch/zgoarch_riscv64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build riscv64
+// +build riscv64
+
+package goarch
+
+const GOARCH = `riscv64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 1
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_s390.go b/src/internal/goarch/zgoarch_s390.go
new file mode 100644
index 0000000..429206d
--- /dev/null
+++ b/src/internal/goarch/zgoarch_s390.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build s390
+// +build s390
+
+package goarch
+
+const GOARCH = `s390`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 1
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_s390x.go b/src/internal/goarch/zgoarch_s390x.go
new file mode 100644
index 0000000..0c59005
--- /dev/null
+++ b/src/internal/goarch/zgoarch_s390x.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build s390x
+// +build s390x
+
+package goarch
+
+const GOARCH = `s390x`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 1
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_sparc.go b/src/internal/goarch/zgoarch_sparc.go
new file mode 100644
index 0000000..83a356e
--- /dev/null
+++ b/src/internal/goarch/zgoarch_sparc.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build sparc
+// +build sparc
+
+package goarch
+
+const GOARCH = `sparc`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 1
+const IsSparc64 = 0
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_sparc64.go b/src/internal/goarch/zgoarch_sparc64.go
new file mode 100644
index 0000000..7c9d409
--- /dev/null
+++ b/src/internal/goarch/zgoarch_sparc64.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build sparc64
+// +build sparc64
+
+package goarch
+
+const GOARCH = `sparc64`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 1
+const IsWasm = 0
diff --git a/src/internal/goarch/zgoarch_wasm.go b/src/internal/goarch/zgoarch_wasm.go
new file mode 100644
index 0000000..5aac1df
--- /dev/null
+++ b/src/internal/goarch/zgoarch_wasm.go
@@ -0,0 +1,33 @@
+// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.
+
+//go:build wasm
+// +build wasm
+
+package goarch
+
+const GOARCH = `wasm`
+
+const Is386 = 0
+const IsAmd64 = 0
+const IsAmd64p32 = 0
+const IsArm = 0
+const IsArmbe = 0
+const IsArm64 = 0
+const IsArm64be = 0
+const IsPpc64 = 0
+const IsPpc64le = 0
+const IsLoong64 = 0
+const IsMips = 0
+const IsMipsle = 0
+const IsMips64 = 0
+const IsMips64le = 0
+const IsMips64p32 = 0
+const IsMips64p32le = 0
+const IsPpc = 0
+const IsRiscv = 0
+const IsRiscv64 = 0
+const IsS390 = 0
+const IsS390x = 0
+const IsSparc = 0
+const IsSparc64 = 0
+const IsWasm = 1
diff --git a/src/internal/goexperiment/exp_regabi_off.go b/src/internal/goexperiment/exp_regabi_off.go
deleted file mode 100644
index 5d88238..0000000
--- a/src/internal/goexperiment/exp_regabi_off.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build !goexperiment.regabi
-// +build !goexperiment.regabi
-
-package goexperiment
-
-const Regabi = false
-const RegabiInt = 0
diff --git a/src/internal/goexperiment/exp_regabi_on.go b/src/internal/goexperiment/exp_regabi_on.go
deleted file mode 100644
index c08d58e..0000000
--- a/src/internal/goexperiment/exp_regabi_on.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build goexperiment.regabi
-// +build goexperiment.regabi
-
-package goexperiment
-
-const Regabi = true
-const RegabiInt = 1
diff --git a/src/internal/goexperiment/exp_regabidefer_off.go b/src/internal/goexperiment/exp_regabidefer_off.go
deleted file mode 100644
index b47c0c2..0000000
--- a/src/internal/goexperiment/exp_regabidefer_off.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build !goexperiment.regabidefer
-// +build !goexperiment.regabidefer
-
-package goexperiment
-
-const RegabiDefer = false
-const RegabiDeferInt = 0
diff --git a/src/internal/goexperiment/exp_regabidefer_on.go b/src/internal/goexperiment/exp_regabidefer_on.go
deleted file mode 100644
index bbf2f6c..0000000
--- a/src/internal/goexperiment/exp_regabidefer_on.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build goexperiment.regabidefer
-// +build goexperiment.regabidefer
-
-package goexperiment
-
-const RegabiDefer = true
-const RegabiDeferInt = 1
diff --git a/src/internal/goexperiment/exp_regabig_off.go b/src/internal/goexperiment/exp_regabig_off.go
deleted file mode 100644
index 1b37d45..0000000
--- a/src/internal/goexperiment/exp_regabig_off.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build !goexperiment.regabig
-// +build !goexperiment.regabig
-
-package goexperiment
-
-const RegabiG = false
-const RegabiGInt = 0
diff --git a/src/internal/goexperiment/exp_regabig_on.go b/src/internal/goexperiment/exp_regabig_on.go
deleted file mode 100644
index 7e5b162..0000000
--- a/src/internal/goexperiment/exp_regabig_on.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Code generated by mkconsts.go. DO NOT EDIT.
-
-//go:build goexperiment.regabig
-// +build goexperiment.regabig
-
-package goexperiment
-
-const RegabiG = true
-const RegabiGInt = 1
diff --git a/src/internal/goexperiment/exp_unified_off.go b/src/internal/goexperiment/exp_unified_off.go
new file mode 100644
index 0000000..4c16fd8
--- /dev/null
+++ b/src/internal/goexperiment/exp_unified_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.unified
+// +build !goexperiment.unified
+
+package goexperiment
+
+const Unified = false
+const UnifiedInt = 0
diff --git a/src/internal/goexperiment/exp_unified_on.go b/src/internal/goexperiment/exp_unified_on.go
new file mode 100644
index 0000000..2b17ba3
--- /dev/null
+++ b/src/internal/goexperiment/exp_unified_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.unified
+// +build goexperiment.unified
+
+package goexperiment
+
+const Unified = true
+const UnifiedInt = 1
diff --git a/src/internal/goexperiment/flags.go b/src/internal/goexperiment/flags.go
index cd4c178..0a61a0e 100644
--- a/src/internal/goexperiment/flags.go
+++ b/src/internal/goexperiment/flags.go
@@ -59,6 +59,10 @@
 	PreemptibleLoops  bool
 	StaticLockRanking bool
 
+	// Unified enables the compiler's unified IR construction
+	// experiment.
+	Unified bool
+
 	// Regabi is split into several sub-experiments that can be
 	// enabled individually. Not all combinations work.
 	// The "regabi" GOEXPERIMENT is an alias for all "working"
@@ -68,26 +72,15 @@
 	// ABI0 and ABIInternal functions. Without this, the ABIs are
 	// assumed to be identical so cross-ABI calls are direct.
 	RegabiWrappers bool
-	// RegabiG enables dedicated G and zero registers in
-	// ABIInternal.
-	//
-	// Requires wrappers because it makes the ABIs incompatible.
-	RegabiG bool
 	// RegabiReflect enables the register-passing paths in
 	// reflection calls. This is also gated by intArgRegs in
 	// reflect and runtime (which are disabled by default) so it
 	// can be used in targeted tests.
 	RegabiReflect bool
-	// RegabiDefer enables desugaring defer and go calls
-	// into argument-less closures.
-	RegabiDefer bool
 	// RegabiArgs enables register arguments/results in all
 	// compiled Go functions.
 	//
-	// Requires wrappers (to do ABI translation), g (because
-	// runtime assembly that's been ported to ABIInternal uses the
-	// G register), reflect (so reflection calls use registers),
-	// and defer (because the runtime doesn't support passing
-	// register arguments to defer/go).
+	// Requires wrappers (to do ABI translation), and reflect (so
+	// reflection calls use registers).
 	RegabiArgs bool
 }
diff --git a/src/internal/goos/gengoos.go b/src/internal/goos/gengoos.go
new file mode 100644
index 0000000..1860cd7
--- /dev/null
+++ b/src/internal/goos/gengoos.go
@@ -0,0 +1,70 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+// +build ignore
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+var gooses []string
+
+func main() {
+	data, err := os.ReadFile("../../go/build/syslist.go")
+	if err != nil {
+		log.Fatal(err)
+	}
+	const goosPrefix = `const goosList = `
+	for _, line := range strings.Split(string(data), "\n") {
+		if strings.HasPrefix(line, goosPrefix) {
+			text, err := strconv.Unquote(strings.TrimPrefix(line, goosPrefix))
+			if err != nil {
+				log.Fatalf("parsing goosList: %v", err)
+			}
+			gooses = strings.Fields(text)
+		}
+	}
+
+	for _, target := range gooses {
+		if target == "nacl" {
+			continue
+		}
+		var tags []string
+		if target == "linux" {
+			tags = append(tags, "!android") // must explicitly exclude android for linux
+		}
+		if target == "solaris" {
+			tags = append(tags, "!illumos") // must explicitly exclude illumos for solaris
+		}
+		if target == "darwin" {
+			tags = append(tags, "!ios") // must explicitly exclude ios for darwin
+		}
+		tags = append(tags, target) // must explicitly include target for bootstrapping purposes
+		var buf bytes.Buffer
+		fmt.Fprintf(&buf, "// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.\n\n")
+		fmt.Fprintf(&buf, "//go:build %s\n", strings.Join(tags, " && "))
+		fmt.Fprintf(&buf, "// +build %s\n\n", strings.Join(tags, ","))
+		fmt.Fprintf(&buf, "package goos\n\n")
+		fmt.Fprintf(&buf, "const GOOS = `%s`\n\n", target)
+		for _, goos := range gooses {
+			value := 0
+			if goos == target {
+				value = 1
+			}
+			fmt.Fprintf(&buf, "const Is%s = %d\n", strings.Title(goos), value)
+		}
+		err := os.WriteFile("zgoos_"+target+".go", buf.Bytes(), 0666)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+}
diff --git a/src/internal/goos/goos.go b/src/internal/goos/goos.go
new file mode 100644
index 0000000..ebb521f
--- /dev/null
+++ b/src/internal/goos/goos.go
@@ -0,0 +1,12 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// package goos contains GOOS-specific constants.
+package goos
+
+// The next line makes 'go generate' write the zgoos*.go files with
+// per-OS information, including constants named Is$GOOS for every
+// known GOOS. The constant is 1 on the current system, 0 otherwise;
+// multiplying by them is useful for defining GOOS-specific constants.
+//go:generate go run gengoos.go
diff --git a/src/internal/goos/zgoos_aix.go b/src/internal/goos/zgoos_aix.go
new file mode 100644
index 0000000..063e698
--- /dev/null
+++ b/src/internal/goos/zgoos_aix.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build aix
+// +build aix
+
+package goos
+
+const GOOS = `aix`
+
+const IsAix = 1
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_android.go b/src/internal/goos/zgoos_android.go
new file mode 100644
index 0000000..e9e4864
--- /dev/null
+++ b/src/internal/goos/zgoos_android.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build android
+// +build android
+
+package goos
+
+const GOOS = `android`
+
+const IsAix = 0
+const IsAndroid = 1
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_darwin.go b/src/internal/goos/zgoos_darwin.go
new file mode 100644
index 0000000..309d6a2
--- /dev/null
+++ b/src/internal/goos/zgoos_darwin.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build !ios && darwin
+// +build !ios,darwin
+
+package goos
+
+const GOOS = `darwin`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 1
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_dragonfly.go b/src/internal/goos/zgoos_dragonfly.go
new file mode 100644
index 0000000..4e8711b
--- /dev/null
+++ b/src/internal/goos/zgoos_dragonfly.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build dragonfly
+// +build dragonfly
+
+package goos
+
+const GOOS = `dragonfly`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 1
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_freebsd.go b/src/internal/goos/zgoos_freebsd.go
new file mode 100644
index 0000000..f312bd1
--- /dev/null
+++ b/src/internal/goos/zgoos_freebsd.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build freebsd
+// +build freebsd
+
+package goos
+
+const GOOS = `freebsd`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 1
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_hurd.go b/src/internal/goos/zgoos_hurd.go
new file mode 100644
index 0000000..0f0dd28
--- /dev/null
+++ b/src/internal/goos/zgoos_hurd.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build hurd
+// +build hurd
+
+package goos
+
+const GOOS = `hurd`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 1
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_illumos.go b/src/internal/goos/zgoos_illumos.go
new file mode 100644
index 0000000..17e7c53
--- /dev/null
+++ b/src/internal/goos/zgoos_illumos.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build illumos
+// +build illumos
+
+package goos
+
+const GOOS = `illumos`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 1
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_ios.go b/src/internal/goos/zgoos_ios.go
new file mode 100644
index 0000000..e4745ca
--- /dev/null
+++ b/src/internal/goos/zgoos_ios.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build ios
+// +build ios
+
+package goos
+
+const GOOS = `ios`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 1
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_js.go b/src/internal/goos/zgoos_js.go
new file mode 100644
index 0000000..bd2417e
--- /dev/null
+++ b/src/internal/goos/zgoos_js.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build js
+// +build js
+
+package goos
+
+const GOOS = `js`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 1
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_linux.go b/src/internal/goos/zgoos_linux.go
new file mode 100644
index 0000000..476702f
--- /dev/null
+++ b/src/internal/goos/zgoos_linux.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build !android && linux
+// +build !android,linux
+
+package goos
+
+const GOOS = `linux`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 1
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_netbsd.go b/src/internal/goos/zgoos_netbsd.go
new file mode 100644
index 0000000..97b7564
--- /dev/null
+++ b/src/internal/goos/zgoos_netbsd.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build netbsd
+// +build netbsd
+
+package goos
+
+const GOOS = `netbsd`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 1
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_openbsd.go b/src/internal/goos/zgoos_openbsd.go
new file mode 100644
index 0000000..384a964
--- /dev/null
+++ b/src/internal/goos/zgoos_openbsd.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build openbsd
+// +build openbsd
+
+package goos
+
+const GOOS = `openbsd`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 1
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_plan9.go b/src/internal/goos/zgoos_plan9.go
new file mode 100644
index 0000000..fcc279a
--- /dev/null
+++ b/src/internal/goos/zgoos_plan9.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build plan9
+// +build plan9
+
+package goos
+
+const GOOS = `plan9`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 1
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_solaris.go b/src/internal/goos/zgoos_solaris.go
new file mode 100644
index 0000000..3f366cf
--- /dev/null
+++ b/src/internal/goos/zgoos_solaris.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build !illumos && solaris
+// +build !illumos,solaris
+
+package goos
+
+const GOOS = `solaris`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 1
+const IsWindows = 0
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_windows.go b/src/internal/goos/zgoos_windows.go
new file mode 100644
index 0000000..dfa5533
--- /dev/null
+++ b/src/internal/goos/zgoos_windows.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build windows
+// +build windows
+
+package goos
+
+const GOOS = `windows`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 1
+const IsZos = 0
diff --git a/src/internal/goos/zgoos_zos.go b/src/internal/goos/zgoos_zos.go
new file mode 100644
index 0000000..714f249
--- /dev/null
+++ b/src/internal/goos/zgoos_zos.go
@@ -0,0 +1,26 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build zos
+// +build zos
+
+package goos
+
+const GOOS = `zos`
+
+const IsAix = 0
+const IsAndroid = 0
+const IsDarwin = 0
+const IsDragonfly = 0
+const IsFreebsd = 0
+const IsHurd = 0
+const IsIllumos = 0
+const IsIos = 0
+const IsJs = 0
+const IsLinux = 0
+const IsNacl = 0
+const IsNetbsd = 0
+const IsOpenbsd = 0
+const IsPlan9 = 0
+const IsSolaris = 0
+const IsWindows = 0
+const IsZos = 1
diff --git a/src/internal/reflectlite/swapper.go b/src/internal/reflectlite/swapper.go
index 6330ab2..ac081d4 100644
--- a/src/internal/reflectlite/swapper.go
+++ b/src/internal/reflectlite/swapper.go
@@ -5,6 +5,7 @@
 package reflectlite
 
 import (
+	"internal/goarch"
 	"internal/unsafeheader"
 	"unsafe"
 )
@@ -36,7 +37,7 @@
 
 	// Some common & small cases, without using memmove:
 	if hasPtr {
-		if size == ptrSize {
+		if size == goarch.PtrSize {
 			ps := *(*[]unsafe.Pointer)(v.ptr)
 			return func(i, j int) { ps[i], ps[j] = ps[j], ps[i] }
 		}
diff --git a/src/internal/reflectlite/value.go b/src/internal/reflectlite/value.go
index 0365eee..1362738 100644
--- a/src/internal/reflectlite/value.go
+++ b/src/internal/reflectlite/value.go
@@ -5,13 +5,12 @@
 package reflectlite
 
 import (
+	"internal/goarch"
 	"internal/unsafeheader"
 	"runtime"
 	"unsafe"
 )
 
-const ptrSize = 4 << (^uintptr(0) >> 63) // unsafe.Sizeof(uintptr(0)) but an ideal const
-
 // Value is the reflection interface to a Go value.
 //
 // Not all methods apply to all kinds of values. Restrictions,
@@ -90,7 +89,7 @@
 // pointer returns the underlying pointer represented by v.
 // v.Kind() must be Ptr, Map, Chan, Func, or UnsafePointer
 func (v Value) pointer() unsafe.Pointer {
-	if v.typ.size != ptrSize || !v.typ.pointers() {
+	if v.typ.size != goarch.PtrSize || !v.typ.pointers() {
 		panic("can't call pointer on a non-pointer Value")
 	}
 	if v.flag&flagIndir != 0 {
diff --git a/src/reflect/abi.go b/src/reflect/abi.go
index 17b79a8..9ddde3a 100644
--- a/src/reflect/abi.go
+++ b/src/reflect/abi.go
@@ -6,6 +6,7 @@
 
 import (
 	"internal/abi"
+	"internal/goarch"
 	"internal/goexperiment"
 	"unsafe"
 )
@@ -167,7 +168,7 @@
 	a.valueStart = append(a.valueStart, len(a.steps))
 	var ok, ptr bool
 	if ifaceIndir(rcvr) || rcvr.pointers() {
-		ok = a.assignIntN(0, ptrSize, 1, 0b1)
+		ok = a.assignIntN(0, goarch.PtrSize, 1, 0b1)
 		ptr = true
 	} else {
 		// TODO(mknyszek): Is this case even possible?
@@ -176,11 +177,11 @@
 		// in the reflect package which only conditionally added
 		// a pointer bit to the reflect.(Value).Call stack frame's
 		// GC bitmap.
-		ok = a.assignIntN(0, ptrSize, 1, 0b0)
+		ok = a.assignIntN(0, goarch.PtrSize, 1, 0b0)
 		ptr = false
 	}
 	if !ok {
-		a.stackAssign(ptrSize, ptrSize)
+		a.stackAssign(goarch.PtrSize, goarch.PtrSize)
 		return &a.steps[len(a.steps)-1], ptr
 	}
 	return nil, ptr
@@ -202,7 +203,7 @@
 	case Bool, Int, Uint, Int8, Uint8, Int16, Uint16, Int32, Uint32, Uintptr:
 		return a.assignIntN(offset, t.size, 1, 0b0)
 	case Int64, Uint64:
-		switch ptrSize {
+		switch goarch.PtrSize {
 		case 4:
 			return a.assignIntN(offset, 4, 2, 0b0)
 		case 8:
@@ -215,11 +216,11 @@
 	case Complex128:
 		return a.assignFloatN(offset, 8, 2)
 	case String:
-		return a.assignIntN(offset, ptrSize, 2, 0b01)
+		return a.assignIntN(offset, goarch.PtrSize, 2, 0b01)
 	case Interface:
-		return a.assignIntN(offset, ptrSize, 2, 0b10)
+		return a.assignIntN(offset, goarch.PtrSize, 2, 0b10)
 	case Slice:
-		return a.assignIntN(offset, ptrSize, 3, 0b001)
+		return a.assignIntN(offset, goarch.PtrSize, 3, 0b001)
 	case Array:
 		tt := (*arrayType)(unsafe.Pointer(t))
 		switch tt.len {
@@ -262,7 +263,7 @@
 	if n > 8 || n < 0 {
 		panic("invalid n")
 	}
-	if ptrMap != 0 && size != ptrSize {
+	if ptrMap != 0 && size != goarch.PtrSize {
 		panic("non-empty pointer map passed for non-pointer-size values")
 	}
 	if a.iregs+n > intArgRegs {
@@ -413,7 +414,7 @@
 				stackPtrs.append(0)
 			}
 		} else {
-			spill += ptrSize
+			spill += goarch.PtrSize
 		}
 	}
 	for i, arg := range t.in() {
@@ -430,12 +431,12 @@
 			}
 		}
 	}
-	spill = align(spill, ptrSize)
+	spill = align(spill, goarch.PtrSize)
 
 	// From the input parameters alone, we now know
 	// the stackCallArgsSize and retOffset.
 	stackCallArgsSize := in.stackBytes
-	retOffset := align(in.stackBytes, ptrSize)
+	retOffset := align(in.stackBytes, goarch.PtrSize)
 
 	// Compute the stack frame pointer bitmap and register
 	// pointer bitmap for return values.
diff --git a/src/reflect/abi_test.go b/src/reflect/abi_test.go
index 5a0130f..2b247d1 100644
--- a/src/reflect/abi_test.go
+++ b/src/reflect/abi_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build goexperiment.regabireflect
-// +build goexperiment.regabireflect
+//go:build goexperiment.regabireflect && goexperiment.regabiargs
+// +build goexperiment.regabireflect,goexperiment.regabiargs
 
 package reflect_test
 
diff --git a/src/reflect/all_test.go b/src/reflect/all_test.go
index eac27e8..5e5e4c1 100644
--- a/src/reflect/all_test.go
+++ b/src/reflect/all_test.go
@@ -10,6 +10,7 @@
 	"flag"
 	"fmt"
 	"go/token"
+	"internal/goarch"
 	"io"
 	"math"
 	"math/rand"
@@ -6466,10 +6467,10 @@
 
 func TestFuncLayout(t *testing.T) {
 	align := func(x uintptr) uintptr {
-		return (x + PtrSize - 1) &^ (PtrSize - 1)
+		return (x + goarch.PtrSize - 1) &^ (goarch.PtrSize - 1)
 	}
 	var r []byte
-	if PtrSize == 4 {
+	if goarch.PtrSize == 4 {
 		r = []byte{0, 0, 0, 1}
 	} else {
 		r = []byte{0, 0, 1}
@@ -6490,56 +6491,56 @@
 	tests := []test{
 		{
 			typ:       ValueOf(func(a, b string) string { return "" }).Type(),
-			size:      6 * PtrSize,
-			argsize:   4 * PtrSize,
-			retOffset: 4 * PtrSize,
+			size:      6 * goarch.PtrSize,
+			argsize:   4 * goarch.PtrSize,
+			retOffset: 4 * goarch.PtrSize,
 			stack:     []byte{1, 0, 1, 0, 1},
 			gc:        []byte{1, 0, 1, 0, 1},
 		},
 		{
 			typ:       ValueOf(func(a, b, c uint32, p *byte, d uint16) {}).Type(),
-			size:      align(align(3*4) + PtrSize + 2),
-			argsize:   align(3*4) + PtrSize + 2,
-			retOffset: align(align(3*4) + PtrSize + 2),
+			size:      align(align(3*4) + goarch.PtrSize + 2),
+			argsize:   align(3*4) + goarch.PtrSize + 2,
+			retOffset: align(align(3*4) + goarch.PtrSize + 2),
 			stack:     r,
 			gc:        r,
 		},
 		{
 			typ:       ValueOf(func(a map[int]int, b uintptr, c interface{}) {}).Type(),
-			size:      4 * PtrSize,
-			argsize:   4 * PtrSize,
-			retOffset: 4 * PtrSize,
+			size:      4 * goarch.PtrSize,
+			argsize:   4 * goarch.PtrSize,
+			retOffset: 4 * goarch.PtrSize,
 			stack:     []byte{1, 0, 1, 1},
 			gc:        []byte{1, 0, 1, 1},
 		},
 		{
 			typ:       ValueOf(func(a S) {}).Type(),
-			size:      4 * PtrSize,
-			argsize:   4 * PtrSize,
-			retOffset: 4 * PtrSize,
+			size:      4 * goarch.PtrSize,
+			argsize:   4 * goarch.PtrSize,
+			retOffset: 4 * goarch.PtrSize,
 			stack:     []byte{0, 0, 1, 1},
 			gc:        []byte{0, 0, 1, 1},
 		},
 		{
 			rcvr:      ValueOf((*byte)(nil)).Type(),
 			typ:       ValueOf(func(a uintptr, b *int) {}).Type(),
-			size:      3 * PtrSize,
-			argsize:   3 * PtrSize,
-			retOffset: 3 * PtrSize,
+			size:      3 * goarch.PtrSize,
+			argsize:   3 * goarch.PtrSize,
+			retOffset: 3 * goarch.PtrSize,
 			stack:     []byte{1, 0, 1},
 			gc:        []byte{1, 0, 1},
 		},
 		{
 			typ:       ValueOf(func(a uintptr) {}).Type(),
-			size:      PtrSize,
-			argsize:   PtrSize,
-			retOffset: PtrSize,
+			size:      goarch.PtrSize,
+			argsize:   goarch.PtrSize,
+			retOffset: goarch.PtrSize,
 			stack:     []byte{},
 			gc:        []byte{},
 		},
 		{
 			typ:       ValueOf(func() uintptr { return 0 }).Type(),
-			size:      PtrSize,
+			size:      goarch.PtrSize,
 			argsize:   0,
 			retOffset: 0,
 			stack:     []byte{},
@@ -6548,9 +6549,9 @@
 		{
 			rcvr:      ValueOf(uintptr(0)).Type(),
 			typ:       ValueOf(func(a uintptr) {}).Type(),
-			size:      2 * PtrSize,
-			argsize:   2 * PtrSize,
-			retOffset: 2 * PtrSize,
+			size:      2 * goarch.PtrSize,
+			argsize:   2 * goarch.PtrSize,
+			retOffset: 2 * goarch.PtrSize,
 			stack:     []byte{1},
 			gc:        []byte{1},
 			// Note: this one is tricky, as the receiver is not a pointer. But we
@@ -6756,7 +6757,7 @@
 	verifyGCBits(t, TypeOf(([][10000]Xscalar)(nil)), lit(1))
 	verifyGCBits(t, SliceOf(ArrayOf(10000, Tscalar)), lit(1))
 
-	hdr := make([]byte, 8/PtrSize)
+	hdr := make([]byte, 8/goarch.PtrSize)
 
 	verifyMapBucket := func(t *testing.T, k, e Type, m interface{}, want []byte) {
 		verifyGCBits(t, MapBucketOf(k, e), want)
@@ -6772,7 +6773,7 @@
 		join(hdr, rep(8, lit(0, 1)), rep(8, lit(1)), lit(1)))
 	verifyMapBucket(t, Tint64, Tptr,
 		map[int64]Xptr(nil),
-		join(hdr, rep(8, rep(8/PtrSize, lit(0))), rep(8, lit(1)), lit(1)))
+		join(hdr, rep(8, rep(8/goarch.PtrSize, lit(0))), rep(8, lit(1)), lit(1)))
 	verifyMapBucket(t,
 		Tscalar, Tscalar,
 		map[Xscalar]Xscalar(nil),
@@ -6782,20 +6783,20 @@
 		map[[2]Xscalarptr][3]Xptrscalar(nil),
 		join(hdr, rep(8*2, lit(0, 1)), rep(8*3, lit(1, 0)), lit(1)))
 	verifyMapBucket(t,
-		ArrayOf(64/PtrSize, Tscalarptr), ArrayOf(64/PtrSize, Tptrscalar),
-		map[[64 / PtrSize]Xscalarptr][64 / PtrSize]Xptrscalar(nil),
-		join(hdr, rep(8*64/PtrSize, lit(0, 1)), rep(8*64/PtrSize, lit(1, 0)), lit(1)))
+		ArrayOf(64/goarch.PtrSize, Tscalarptr), ArrayOf(64/goarch.PtrSize, Tptrscalar),
+		map[[64 / goarch.PtrSize]Xscalarptr][64 / goarch.PtrSize]Xptrscalar(nil),
+		join(hdr, rep(8*64/goarch.PtrSize, lit(0, 1)), rep(8*64/goarch.PtrSize, lit(1, 0)), lit(1)))
 	verifyMapBucket(t,
-		ArrayOf(64/PtrSize+1, Tscalarptr), ArrayOf(64/PtrSize, Tptrscalar),
-		map[[64/PtrSize + 1]Xscalarptr][64 / PtrSize]Xptrscalar(nil),
-		join(hdr, rep(8, lit(1)), rep(8*64/PtrSize, lit(1, 0)), lit(1)))
+		ArrayOf(64/goarch.PtrSize+1, Tscalarptr), ArrayOf(64/goarch.PtrSize, Tptrscalar),
+		map[[64/goarch.PtrSize + 1]Xscalarptr][64 / goarch.PtrSize]Xptrscalar(nil),
+		join(hdr, rep(8, lit(1)), rep(8*64/goarch.PtrSize, lit(1, 0)), lit(1)))
 	verifyMapBucket(t,
-		ArrayOf(64/PtrSize, Tscalarptr), ArrayOf(64/PtrSize+1, Tptrscalar),
-		map[[64 / PtrSize]Xscalarptr][64/PtrSize + 1]Xptrscalar(nil),
-		join(hdr, rep(8*64/PtrSize, lit(0, 1)), rep(8, lit(1)), lit(1)))
+		ArrayOf(64/goarch.PtrSize, Tscalarptr), ArrayOf(64/goarch.PtrSize+1, Tptrscalar),
+		map[[64 / goarch.PtrSize]Xscalarptr][64/goarch.PtrSize + 1]Xptrscalar(nil),
+		join(hdr, rep(8*64/goarch.PtrSize, lit(0, 1)), rep(8, lit(1)), lit(1)))
 	verifyMapBucket(t,
-		ArrayOf(64/PtrSize+1, Tscalarptr), ArrayOf(64/PtrSize+1, Tptrscalar),
-		map[[64/PtrSize + 1]Xscalarptr][64/PtrSize + 1]Xptrscalar(nil),
+		ArrayOf(64/goarch.PtrSize+1, Tscalarptr), ArrayOf(64/goarch.PtrSize+1, Tptrscalar),
+		map[[64/goarch.PtrSize + 1]Xscalarptr][64/goarch.PtrSize + 1]Xptrscalar(nil),
 		join(hdr, rep(8, lit(1)), rep(8, lit(1)), lit(1)))
 }
 
diff --git a/src/reflect/asm_amd64.s b/src/reflect/asm_amd64.s
index facf075..d21d498 100644
--- a/src/reflect/asm_amd64.s
+++ b/src/reflect/asm_amd64.s
@@ -24,15 +24,13 @@
 // See the comment on the declaration of makeFuncStub in makefunc.go
 // for more details.
 // No arg size here; runtime pulls arg map out of the func value.
-// makeFuncStub must be ABIInternal because it is placed directly
-// in function values.
 // This frame contains two locals. See the comment above LOCAL_RETVALID.
-TEXT ·makeFuncStub<ABIInternal>(SB),(NOSPLIT|WRAPPER),$312
+TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$312
 	NO_LOCAL_POINTERS
 	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
 	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
 	LEAQ	LOCAL_REGARGS(SP), R12
-	CALL	runtime·spillArgs<ABIInternal>(SB)
+	CALL	runtime·spillArgs(SB)
 	MOVQ	DX, 24(SP) // outside of moveMakeFuncArgPtrs's arg area
 	MOVQ	DX, 0(SP)
 	MOVQ	R12, 8(SP)
@@ -48,22 +46,20 @@
 	MOVQ	AX, 24(SP)
 	CALL	·callReflect(SB)
 	LEAQ	LOCAL_REGARGS(SP), R12
-	CALL	runtime·unspillArgs<ABIInternal>(SB)
+	CALL	runtime·unspillArgs(SB)
 	RET
 
 // methodValueCall is the code half of the function returned by makeMethodValue.
 // See the comment on the declaration of methodValueCall in makefunc.go
 // for more details.
 // No arg size here; runtime pulls arg map out of the func value.
-// methodValueCall must be ABIInternal because it is placed directly
-// in function values.
 // This frame contains two locals. See the comment above LOCAL_RETVALID.
-TEXT ·methodValueCall<ABIInternal>(SB),(NOSPLIT|WRAPPER),$312
+TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$312
 	NO_LOCAL_POINTERS
 	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
 	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
 	LEAQ	LOCAL_REGARGS(SP), R12
-	CALL	runtime·spillArgs<ABIInternal>(SB)
+	CALL	runtime·spillArgs(SB)
 	MOVQ	DX, 24(SP) // outside of moveMakeFuncArgPtrs's arg area
 	MOVQ	DX, 0(SP)
 	MOVQ	R12, 8(SP)
@@ -79,5 +75,5 @@
 	MOVQ	AX, 24(SP)
 	CALL	·callMethod(SB)
 	LEAQ	LOCAL_REGARGS(SP), R12
-	CALL	runtime·unspillArgs<ABIInternal>(SB)
+	CALL	runtime·unspillArgs(SB)
 	RET
diff --git a/src/reflect/asm_arm64.s b/src/reflect/asm_arm64.s
index 5fe88e2..5b9b357 100644
--- a/src/reflect/asm_arm64.s
+++ b/src/reflect/asm_arm64.s
@@ -5,34 +5,75 @@
 #include "textflag.h"
 #include "funcdata.h"
 
+// The frames of each of the two functions below contain two locals, at offsets
+// that are known to the runtime.
+//
+// The first local is a bool called retValid with a whole pointer-word reserved
+// for it on the stack. The purpose of this word is so that the runtime knows
+// whether the stack-allocated return space contains valid values for stack
+// scanning.
+//
+// The second local is an abi.RegArgs value whose offset is also known to the
+// runtime, so that a stack map for it can be constructed, since it contains
+// pointers visible to the GC.
+#define LOCAL_RETVALID 40
+#define LOCAL_REGARGS 48
+
+// The frame size of the functions below is
+// 32 (args of callReflect) + 8 (bool + padding) + 392 (abi.RegArgs) = 432.
+
 // makeFuncStub is the code half of the function returned by MakeFunc.
 // See the comment on the declaration of makeFuncStub in makefunc.go
 // for more details.
 // No arg size here, runtime pulls arg map out of the func value.
-TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$40
+TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$432
 	NO_LOCAL_POINTERS
+	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
+	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
+	ADD	$LOCAL_REGARGS, RSP, R20
+	CALL	runtime·spillArgs(SB)
+	MOVD	R26, 32(RSP) // outside of moveMakeFuncArgPtrs's arg area
+	MOVD	R26, 8(RSP)
+	MOVD	R20, 16(RSP)
+	CALL	·moveMakeFuncArgPtrs(SB)
+	MOVD	32(RSP), R26
 	MOVD	R26, 8(RSP)
 	MOVD	$argframe+0(FP), R3
 	MOVD	R3, 16(RSP)
-	MOVB	$0, 40(RSP)
-	ADD	$40, RSP, R3
+	MOVB	$0, LOCAL_RETVALID(RSP)
+	ADD	$LOCAL_RETVALID, RSP, R3
 	MOVD	R3, 24(RSP)
-	MOVD	$0, 32(RSP)
-	BL	·callReflect(SB)
+	ADD	$LOCAL_REGARGS, RSP, R3
+	MOVD	R3, 32(RSP)
+	CALL	·callReflect(SB)
+	ADD	$LOCAL_REGARGS, RSP, R20
+	CALL	runtime·unspillArgs(SB)
 	RET
 
 // methodValueCall is the code half of the function returned by makeMethodValue.
 // See the comment on the declaration of methodValueCall in makefunc.go
 // for more details.
 // No arg size here; runtime pulls arg map out of the func value.
-TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$40
+TEXT ·methodValueCall(SB),(NOSPLIT|WRAPPER),$432
 	NO_LOCAL_POINTERS
+	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
+	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
+	ADD	$LOCAL_REGARGS, RSP, R20
+	CALL	runtime·spillArgs(SB)
+	MOVD	R26, 32(RSP) // outside of moveMakeFuncArgPtrs's arg area
+	MOVD	R26, 8(RSP)
+	MOVD	R20, 16(RSP)
+	CALL	·moveMakeFuncArgPtrs(SB)
+	MOVD	32(RSP), R26
 	MOVD	R26, 8(RSP)
 	MOVD	$argframe+0(FP), R3
 	MOVD	R3, 16(RSP)
-	MOVB	$0, 40(RSP)
-	ADD	$40, RSP, R3
+	MOVB	$0, LOCAL_RETVALID(RSP)
+	ADD	$LOCAL_RETVALID, RSP, R3
 	MOVD	R3, 24(RSP)
-	MOVD	$0, 32(RSP)
-	BL	·callMethod(SB)
+	ADD	$LOCAL_REGARGS, RSP, R3
+	MOVD	R3, 32(RSP)
+	CALL	·callMethod(SB)
+	ADD	$LOCAL_REGARGS, RSP, R20
+	CALL	runtime·unspillArgs(SB)
 	RET
diff --git a/src/reflect/export_test.go b/src/reflect/export_test.go
index b6830a9..01749e3 100644
--- a/src/reflect/export_test.go
+++ b/src/reflect/export_test.go
@@ -5,6 +5,7 @@
 package reflect
 
 import (
+	"internal/goarch"
 	"sync"
 	"unsafe"
 )
@@ -22,8 +23,6 @@
 
 var CallGC = &callGC
 
-const PtrSize = ptrSize
-
 // FuncLayout calls funcLayout and returns a subset of the results for testing.
 //
 // Bitmaps like stack, gc, inReg, and outReg are expanded such that each bit
@@ -65,7 +64,7 @@
 	// Expand frame type's GC bitmap into byte-map.
 	ptrs = ft.ptrdata != 0
 	if ptrs {
-		nptrs := ft.ptrdata / ptrSize
+		nptrs := ft.ptrdata / goarch.PtrSize
 		gcdata := ft.gcSlice(0, (nptrs+7)/8)
 		for i := uintptr(0); i < nptrs; i++ {
 			gc = append(gc, gcdata[i/8]>>(i%8)&1)
diff --git a/src/reflect/makefunc.go b/src/reflect/makefunc.go
index d53e68a..588be8b 100644
--- a/src/reflect/makefunc.go
+++ b/src/reflect/makefunc.go
@@ -52,11 +52,7 @@
 	t := typ.common()
 	ftyp := (*funcType)(unsafe.Pointer(t))
 
-	// Indirect Go func value (dummy) to obtain
-	// actual code address. (A Go func value is a pointer
-	// to a C function pointer. https://golang.org/s/go11func.)
-	dummy := makeFuncStub
-	code := **(**uintptr)(unsafe.Pointer(&dummy))
+	code := abi.FuncPCABI0(makeFuncStub)
 
 	// makeFuncImpl contains a stack map for use by the runtime
 	_, _, abi := funcLayout(ftyp, nil)
@@ -111,11 +107,7 @@
 	// v.Type returns the actual type of the method value.
 	ftyp := (*funcType)(unsafe.Pointer(v.Type().(*rtype)))
 
-	// Indirect Go func value (dummy) to obtain
-	// actual code address. (A Go func value is a pointer
-	// to a C function pointer. https://golang.org/s/go11func.)
-	dummy := methodValueCall
-	code := **(**uintptr)(unsafe.Pointer(&dummy))
+	code := abi.FuncPCABI0(methodValueCall)
 
 	// methodValue contains a stack map for use by the runtime
 	_, _, abi := funcLayout(ftyp, nil)
diff --git a/src/reflect/swapper.go b/src/reflect/swapper.go
index 0cf4066..67b7fbe 100644
--- a/src/reflect/swapper.go
+++ b/src/reflect/swapper.go
@@ -5,6 +5,7 @@
 package reflect
 
 import (
+	"internal/goarch"
 	"internal/unsafeheader"
 	"unsafe"
 )
@@ -36,7 +37,7 @@
 
 	// Some common & small cases, without using memmove:
 	if hasPtr {
-		if size == ptrSize {
+		if size == goarch.PtrSize {
 			ps := *(*[]unsafe.Pointer)(v.ptr)
 			return func(i, j int) { ps[i], ps[j] = ps[j], ps[i] }
 		}
diff --git a/src/reflect/type.go b/src/reflect/type.go
index f672a7a..278426d 100644
--- a/src/reflect/type.go
+++ b/src/reflect/type.go
@@ -16,6 +16,7 @@
 package reflect
 
 import (
+	"internal/goarch"
 	"internal/unsafeheader"
 	"strconv"
 	"sync"
@@ -1924,13 +1925,13 @@
 	}
 	mt.flags = 0
 	if ktyp.size > maxKeySize {
-		mt.keysize = uint8(ptrSize)
+		mt.keysize = uint8(goarch.PtrSize)
 		mt.flags |= 1 // indirect key
 	} else {
 		mt.keysize = uint8(ktyp.size)
 	}
 	if etyp.size > maxValSize {
-		mt.valuesize = uint8(ptrSize)
+		mt.valuesize = uint8(goarch.PtrSize)
 		mt.flags |= 2 // indirect value
 	} else {
 		mt.valuesize = uint8(etyp.size)
@@ -2231,31 +2232,31 @@
 	var ptrdata uintptr
 	var overflowPad uintptr
 
-	size := bucketSize*(1+ktyp.size+etyp.size) + overflowPad + ptrSize
+	size := bucketSize*(1+ktyp.size+etyp.size) + overflowPad + goarch.PtrSize
 	if size&uintptr(ktyp.align-1) != 0 || size&uintptr(etyp.align-1) != 0 {
 		panic("reflect: bad size computation in MapOf")
 	}
 
 	if ktyp.ptrdata != 0 || etyp.ptrdata != 0 {
-		nptr := (bucketSize*(1+ktyp.size+etyp.size) + ptrSize) / ptrSize
+		nptr := (bucketSize*(1+ktyp.size+etyp.size) + goarch.PtrSize) / goarch.PtrSize
 		mask := make([]byte, (nptr+7)/8)
-		base := bucketSize / ptrSize
+		base := bucketSize / goarch.PtrSize
 
 		if ktyp.ptrdata != 0 {
 			emitGCMask(mask, base, ktyp, bucketSize)
 		}
-		base += bucketSize * ktyp.size / ptrSize
+		base += bucketSize * ktyp.size / goarch.PtrSize
 
 		if etyp.ptrdata != 0 {
 			emitGCMask(mask, base, etyp, bucketSize)
 		}
-		base += bucketSize * etyp.size / ptrSize
-		base += overflowPad / ptrSize
+		base += bucketSize * etyp.size / goarch.PtrSize
+		base += overflowPad / goarch.PtrSize
 
 		word := base
 		mask[word/8] |= 1 << (word % 8)
 		gcdata = &mask[0]
-		ptrdata = (word + 1) * ptrSize
+		ptrdata = (word + 1) * goarch.PtrSize
 
 		// overflow word must be last
 		if ptrdata != size {
@@ -2264,7 +2265,7 @@
 	}
 
 	b := &rtype{
-		align:   ptrSize,
+		align:   goarch.PtrSize,
 		size:    size,
 		kind:    uint8(Struct),
 		ptrdata: ptrdata,
@@ -2288,8 +2289,8 @@
 	if typ.kind&kindGCProg != 0 {
 		panic("reflect: unexpected GC program")
 	}
-	ptrs := typ.ptrdata / ptrSize
-	words := typ.size / ptrSize
+	ptrs := typ.ptrdata / goarch.PtrSize
+	words := typ.size / goarch.PtrSize
 	mask := typ.gcSlice(0, (ptrs+7)/8)
 	for j := uintptr(0); j < ptrs; j++ {
 		if (mask[j/8]>>(j%8))&1 != 0 {
@@ -2312,7 +2313,7 @@
 	}
 
 	// Element is small with pointer mask; use as literal bits.
-	ptrs := typ.ptrdata / ptrSize
+	ptrs := typ.ptrdata / goarch.PtrSize
 	mask := typ.gcSlice(0, (ptrs+7)/8)
 
 	// Emit 120-bit chunks of full bytes (max is 127 but we avoid using partial bytes).
@@ -2759,7 +2760,7 @@
 			}
 			// Pad to start of this field with zeros.
 			if ft.offset() > off {
-				n := (ft.offset() - off) / ptrSize
+				n := (ft.offset() - off) / goarch.PtrSize
 				prog = append(prog, 0x01, 0x00) // emit a 0 bit
 				if n > 1 {
 					prog = append(prog, 0x81)      // repeat previous bit
@@ -2936,11 +2937,11 @@
 		array.gcdata = typ.gcdata
 		array.ptrdata = typ.ptrdata
 
-	case typ.kind&kindGCProg == 0 && array.size <= maxPtrmaskBytes*8*ptrSize:
+	case typ.kind&kindGCProg == 0 && array.size <= maxPtrmaskBytes*8*goarch.PtrSize:
 		// Element is small with pointer mask; array is still small.
 		// Create direct pointer mask by turning each 1 bit in elem
 		// into length 1 bits in larger mask.
-		mask := make([]byte, (array.ptrdata/ptrSize+7)/8)
+		mask := make([]byte, (array.ptrdata/goarch.PtrSize+7)/8)
 		emitGCMask(mask, 0, typ, array.len)
 		array.gcdata = &mask[0]
 
@@ -2950,8 +2951,8 @@
 		prog := []byte{0, 0, 0, 0} // will be length of prog
 		prog = appendGCProg(prog, typ)
 		// Pad from ptrdata to size.
-		elemPtrs := typ.ptrdata / ptrSize
-		elemWords := typ.size / ptrSize
+		elemPtrs := typ.ptrdata / goarch.PtrSize
+		elemWords := typ.size / goarch.PtrSize
 		if elemPtrs < elemWords {
 			// Emit literal 0 bit, then repeat as needed.
 			prog = append(prog, 0x01, 0x00)
@@ -3063,13 +3064,13 @@
 
 	// build dummy rtype holding gc program
 	x := &rtype{
-		align: ptrSize,
+		align: goarch.PtrSize,
 		// Don't add spill space here; it's only necessary in
 		// reflectcall's frame, not in the allocated frame.
 		// TODO(mknyszek): Remove this comment when register
 		// spill space in the frame is no longer required.
-		size:    align(abi.retOffset+abi.ret.stackBytes, ptrSize),
-		ptrdata: uintptr(abi.stackPtrs.n) * ptrSize,
+		size:    align(abi.retOffset+abi.ret.stackBytes, goarch.PtrSize),
+		ptrdata: uintptr(abi.stackPtrs.n) * goarch.PtrSize,
 	}
 	if abi.stackPtrs.n > 0 {
 		x.gcdata = &abi.stackPtrs.data[0]
@@ -3124,14 +3125,14 @@
 	switch Kind(t.kind & kindMask) {
 	case Chan, Func, Map, Ptr, Slice, String, UnsafePointer:
 		// 1 pointer at start of representation
-		for bv.n < uint32(offset/uintptr(ptrSize)) {
+		for bv.n < uint32(offset/uintptr(goarch.PtrSize)) {
 			bv.append(0)
 		}
 		bv.append(1)
 
 	case Interface:
 		// 2 pointers
-		for bv.n < uint32(offset/uintptr(ptrSize)) {
+		for bv.n < uint32(offset/uintptr(goarch.PtrSize)) {
 			bv.append(0)
 		}
 		bv.append(1)
diff --git a/src/reflect/value.go b/src/reflect/value.go
index 6f878eb..b4b2d2e 100644
--- a/src/reflect/value.go
+++ b/src/reflect/value.go
@@ -6,6 +6,7 @@
 
 import (
 	"internal/abi"
+	"internal/goarch"
 	"internal/itoa"
 	"internal/unsafeheader"
 	"math"
@@ -13,8 +14,6 @@
 	"unsafe"
 )
 
-const ptrSize = 4 << (^uintptr(0) >> 63) // unsafe.Sizeof(uintptr(0)) but an ideal const
-
 // Value is the reflection interface to a Go value.
 //
 // Not all methods apply to all kinds of values. Restrictions,
@@ -94,7 +93,7 @@
 // v.Kind() must be Ptr, Map, Chan, Func, or UnsafePointer
 // if v.Kind() == Ptr, the base type must not be go:notinheap.
 func (v Value) pointer() unsafe.Pointer {
-	if v.typ.size != ptrSize || !v.typ.pointers() {
+	if v.typ.size != goarch.PtrSize || !v.typ.pointers() {
 		panic("can't call pointer on a non-pointer Value")
 	}
 	if v.flag&flagIndir != 0 {
@@ -533,7 +532,7 @@
 	}
 	// TODO(mknyszek): Remove this when we no longer have
 	// caller reserved spill space.
-	frameSize = align(frameSize, ptrSize)
+	frameSize = align(frameSize, goarch.PtrSize)
 	frameSize += abi.spill
 
 	// Mark pointers in registers for the return path.
@@ -958,9 +957,6 @@
 		// 2. Stack -> registers translation.
 		// 3. Registers -> stack translation.
 		// 4. Registers -> registers translation.
-		// TODO(mknyszek): Cases 2 and 3 below only work on little endian
-		// architectures. This is OK for now, but this needs to be fixed
-		// before supporting the register ABI on big endian architectures.
 
 		// If the value ABI passes the value on the stack,
 		// then the method ABI does too, because it has strictly
@@ -986,9 +982,9 @@
 					methodRegs.Ptrs[mStep.ireg] = *(*unsafe.Pointer)(from)
 					fallthrough // We need to make sure this ends up in Ints, too.
 				case abiStepIntReg:
-					memmove(unsafe.Pointer(&methodRegs.Ints[mStep.ireg]), from, mStep.size)
+					memmove(methodRegs.IntRegArgAddr(mStep.ireg, mStep.size), from, mStep.size)
 				case abiStepFloatReg:
-					memmove(unsafe.Pointer(&methodRegs.Floats[mStep.freg]), from, mStep.size)
+					memmove(methodRegs.FloatRegArgAddr(mStep.freg, mStep.size), from, mStep.size)
 				default:
 					panic("unexpected method step")
 				}
@@ -1004,9 +1000,9 @@
 					// Do the pointer copy directly so we get a write barrier.
 					*(*unsafe.Pointer)(to) = valueRegs.Ptrs[vStep.ireg]
 				case abiStepIntReg:
-					memmove(to, unsafe.Pointer(&valueRegs.Ints[vStep.ireg]), vStep.size)
+					memmove(to, valueRegs.IntRegArgAddr(vStep.ireg, vStep.size), vStep.size)
 				case abiStepFloatReg:
-					memmove(to, unsafe.Pointer(&valueRegs.Floats[vStep.freg]), vStep.size)
+					memmove(to, valueRegs.FloatRegArgAddr(vStep.freg, vStep.size), vStep.size)
 				default:
 					panic("unexpected value step")
 				}
@@ -1043,7 +1039,7 @@
 	methodFrameSize := methodFrameType.size
 	// TODO(mknyszek): Remove this when we no longer have
 	// caller reserved spill space.
-	methodFrameSize = align(methodFrameSize, ptrSize)
+	methodFrameSize = align(methodFrameSize, goarch.PtrSize)
 	methodFrameSize += methodABI.spill
 
 	// Mark pointers in registers for the return path.
diff --git a/src/runtime/alg.go b/src/runtime/alg.go
index 39c7426..978a3b8 100644
--- a/src/runtime/alg.go
+++ b/src/runtime/alg.go
@@ -6,13 +6,13 @@
 
 import (
 	"internal/cpu"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
 const (
-	c0 = uintptr((8-sys.PtrSize)/4*2860486313 + (sys.PtrSize-4)/4*33054211828000289)
-	c1 = uintptr((8-sys.PtrSize)/4*3267000013 + (sys.PtrSize-4)/4*23344194077549503)
+	c0 = uintptr((8-goarch.PtrSize)/4*2860486313 + (goarch.PtrSize-4)/4*33054211828000289)
+	c1 = uintptr((8-goarch.PtrSize)/4*3267000013 + (goarch.PtrSize-4)/4*23344194077549503)
 )
 
 func memhash0(p unsafe.Pointer, h uintptr) uintptr {
@@ -300,7 +300,7 @@
 	return interhash(noescape(unsafe.Pointer(&i)), seed)
 }
 
-const hashRandomBytes = sys.PtrSize / 4 * 64
+const hashRandomBytes = goarch.PtrSize / 4 * 64
 
 // used in asm_{386,amd64,arm64}.s to seed the hash function
 var aeskeysched [hashRandomBytes]byte
@@ -321,7 +321,7 @@
 		initAlgAES()
 		return
 	}
-	getRandomData((*[len(hashkey) * sys.PtrSize]byte)(unsafe.Pointer(&hashkey))[:])
+	getRandomData((*[len(hashkey) * goarch.PtrSize]byte)(unsafe.Pointer(&hashkey))[:])
 	hashkey[0] |= 1 // make sure these numbers are odd
 	hashkey[1] |= 1
 	hashkey[2] |= 1
@@ -337,7 +337,7 @@
 // Note: These routines perform the read with a native endianness.
 func readUnaligned32(p unsafe.Pointer) uint32 {
 	q := (*[4]byte)(p)
-	if sys.BigEndian {
+	if goarch.BigEndian {
 		return uint32(q[3]) | uint32(q[2])<<8 | uint32(q[1])<<16 | uint32(q[0])<<24
 	}
 	return uint32(q[0]) | uint32(q[1])<<8 | uint32(q[2])<<16 | uint32(q[3])<<24
@@ -345,7 +345,7 @@
 
 func readUnaligned64(p unsafe.Pointer) uint64 {
 	q := (*[8]byte)(p)
-	if sys.BigEndian {
+	if goarch.BigEndian {
 		return uint64(q[7]) | uint64(q[6])<<8 | uint64(q[5])<<16 | uint64(q[4])<<24 |
 			uint64(q[3])<<32 | uint64(q[2])<<40 | uint64(q[1])<<48 | uint64(q[0])<<56
 	}
diff --git a/src/runtime/asm.s b/src/runtime/asm.s
index 72c7449..0e14fcd 100644
--- a/src/runtime/asm.s
+++ b/src/runtime/asm.s
@@ -13,6 +13,6 @@
 GLOBL runtime·no_pointers_stackmap(SB),RODATA, $8
 
 #ifndef GOARCH_amd64
-TEXT ·sigpanic0<ABIInternal>(SB),NOSPLIT,$0-0
+TEXT ·sigpanic0(SB),NOSPLIT,$0-0
 	JMP	·sigpanic<ABIInternal>(SB)
 #endif
diff --git a/src/runtime/asm_386.s b/src/runtime/asm_386.s
index ec5ea58..11c6030 100644
--- a/src/runtime/asm_386.s
+++ b/src/runtime/asm_386.s
@@ -244,10 +244,8 @@
 
 	// create a new goroutine to start program
 	PUSHL	$runtime·mainPC(SB)	// entry
-	PUSHL	$0	// arg size
 	CALL	runtime·newproc(SB)
 	POPL	AX
-	POPL	AX
 
 	// start this M
 	CALL	runtime·mstart(SB)
@@ -584,26 +582,6 @@
 	// compile barrier.
 	RET
 
-// void jmpdefer(fn, sp);
-// called from deferreturn.
-// 1. pop the caller
-// 2. sub 5 bytes (the length of CALL & a 32 bit displacement) from the callers
-//    return (when building for shared libraries, subtract 16 bytes -- 5 bytes
-//    for CALL & displacement to call __x86.get_pc_thunk.cx, 6 bytes for the
-//    LEAL to load the offset into BX, and finally 5 for the call & displacement)
-// 3. jmp to the argument
-TEXT runtime·jmpdefer(SB), NOSPLIT, $0-8
-	MOVL	fv+0(FP), DX	// fn
-	MOVL	argp+4(FP), BX	// caller sp
-	LEAL	-4(BX), SP	// caller sp after CALL
-#ifdef GOBUILDMODE_shared
-	SUBL	$16, (SP)	// return to CALL again
-#else
-	SUBL	$5, (SP)	// return to CALL again
-#endif
-	MOVL	0(DX), BX
-	JMP	BX	// but first run the deferred function
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index 14f29e1..2083ecb 100644
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -214,10 +214,8 @@
 	// create a new goroutine to start program
 	MOVQ	$runtime·mainPC(SB), AX		// entry
 	PUSHQ	AX
-	PUSHQ	$0			// arg size
 	CALL	runtime·newproc(SB)
 	POPQ	AX
-	POPQ	AX
 
 	// start this M
 	CALL	runtime·mstart(SB)
@@ -279,7 +277,6 @@
 // Switch to m->g0's stack, call fn(g).
 // Fn must never return. It should gogo(&g->sched)
 // to keep running g.
-#ifdef GOEXPERIMENT_regabiargs
 TEXT runtime·mcall<ABIInternal>(SB), NOSPLIT, $0-8
 	MOVQ	AX, DX	// DX = fn
 
@@ -308,38 +305,6 @@
 	POPQ	AX
 	JMP	runtime·badmcall2(SB)
 	RET
-#else
-TEXT runtime·mcall(SB), NOSPLIT, $0-8
-	MOVQ	fn+0(FP), DI
-
-	get_tls(CX)
-	MOVQ	g(CX), AX	// save state in g->sched
-	MOVQ	0(SP), BX	// caller's PC
-	MOVQ	BX, (g_sched+gobuf_pc)(AX)
-	LEAQ	fn+0(FP), BX	// caller's SP
-	MOVQ	BX, (g_sched+gobuf_sp)(AX)
-	MOVQ	BP, (g_sched+gobuf_bp)(AX)
-
-	// switch to m->g0 & its stack, call fn
-	MOVQ	g(CX), BX
-	MOVQ	g_m(BX), BX
-	MOVQ	m_g0(BX), SI
-	CMPQ	SI, AX	// if g == m->g0 call badmcall
-	JNE	3(PC)
-	MOVQ	$runtime·badmcall(SB), AX
-	JMP	AX
-	MOVQ	SI, g(CX)	// g = m->g0
-	MOVQ	SI, R14	// set the g register
-	MOVQ	(g_sched+gobuf_sp)(SI), SP	// sp = m->g0->sched.sp
-	PUSHQ	AX
-	MOVQ	DI, DX
-	MOVQ	0(DI), DI
-	CALL	DI
-	POPQ	AX
-	MOVQ	$runtime·badmcall2(SB), AX
-	JMP	AX
-	RET
-#endif
 
 // systemstack_switch is a dummy routine that systemstack leaves at the bottom
 // of the G stack. We need to distinguish the routine that
@@ -467,9 +432,8 @@
 	MOVL	$0, DX
 	JMP	runtime·morestack(SB)
 
-#ifdef GOEXPERIMENT_regabireflect
 // spillArgs stores return values from registers to a *internal/abi.RegArgs in R12.
-TEXT ·spillArgs<ABIInternal>(SB),NOSPLIT,$0-0
+TEXT ·spillArgs(SB),NOSPLIT,$0-0
 	MOVQ AX, 0(R12)
 	MOVQ BX, 8(R12)
 	MOVQ CX, 16(R12)
@@ -497,7 +461,7 @@
 	RET
 
 // unspillArgs loads args into registers from a *internal/abi.RegArgs in R12.
-TEXT ·unspillArgs<ABIInternal>(SB),NOSPLIT,$0-0
+TEXT ·unspillArgs(SB),NOSPLIT,$0-0
 	MOVQ 0(R12), AX
 	MOVQ 8(R12), BX
 	MOVQ 16(R12), CX
@@ -523,15 +487,6 @@
 	MOVQ 176(R12), X13
 	MOVQ 184(R12), X14
 	RET
-#else
-// spillArgs stores return values from registers to a pointer in R12.
-TEXT ·spillArgs<ABIInternal>(SB),NOSPLIT,$0-0
-	RET
-
-// unspillArgs loads args into registers from a pointer in R12.
-TEXT ·unspillArgs<ABIInternal>(SB),NOSPLIT,$0-0
-	RET
-#endif
 
 // reflectcall: call a function with the given argument list
 // func call(stackArgsType *_type, f *FuncVal, stackArgs *byte, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs).
@@ -588,7 +543,7 @@
 	REP;MOVSB;				\
 	/* set up argument registers */		\
 	MOVQ    regArgs+40(FP), R12;		\
-	CALL    ·unspillArgs<ABIInternal>(SB);		\
+	CALL    ·unspillArgs(SB);		\
 	/* call function */			\
 	MOVQ	f+8(FP), DX;			\
 	PCDATA  $PCDATA_StackMapIndex, $0;	\
@@ -596,7 +551,7 @@
 	CALL	R12;				\
 	/* copy register return values back */		\
 	MOVQ    regArgs+40(FP), R12;		\
-	CALL    ·spillArgs<ABIInternal>(SB);		\
+	CALL    ·spillArgs(SB);		\
 	MOVLQZX	stackArgsSize+24(FP), CX;		\
 	MOVLQZX	stackRetOffset+28(FP), BX;		\
 	MOVQ	stackArgs+16(FP), DI;		\
@@ -664,31 +619,12 @@
 	// compile barrier.
 	RET
 
-// func jmpdefer(fv *funcval, argp uintptr)
-// argp is a caller SP.
-// called from deferreturn.
-// 1. pop the caller
-// 2. sub 5 bytes from the callers return
-// 3. jmp to the argument
-TEXT runtime·jmpdefer(SB), NOSPLIT, $0-16
-	MOVQ	fv+0(FP), DX	// fn
-	MOVQ	argp+8(FP), BX	// caller sp
-	LEAQ	-8(BX), SP	// caller sp after CALL
-	MOVQ	-8(SP), BP	// restore BP as if deferreturn returned (harmless if framepointers not in use)
-	SUBQ	$5, (SP)	// return to CALL again
-	MOVQ	0(DX), BX
-	JMP	BX	// but first run the deferred function
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
 // or else unwinding from systemstack_switch is incorrect.
 // Smashes R9.
 TEXT gosave_systemstack_switch<>(SB),NOSPLIT,$0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R14)
-	MOVQ	g(R14), R14
-#endif
 	MOVQ	$runtime·systemstack_switch(SB), R9
 	MOVQ	R9, (g_sched+gobuf_pc)(R14)
 	LEAQ	8(SP), R9
@@ -1009,61 +945,34 @@
 // func memhash(p unsafe.Pointer, h, s uintptr) uintptr
 // hash function using AES hardware instructions
 TEXT runtime·memhash<ABIInternal>(SB),NOSPLIT,$0-32
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
 	// CX = size
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	s+16(FP), CX	// size
-	LEAQ	ret+24(FP), DX
-#endif
 	JMP	aeshashbody<>(SB)
 noaes:
 	JMP	runtime·memhashFallback<ABIInternal>(SB)
 
 // func strhash(p unsafe.Pointer, h uintptr) uintptr
 TEXT runtime·strhash<ABIInternal>(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to string struct
 	// BX = seed
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	p+0(FP), AX	// ptr to string struct
-#endif
 	MOVQ	8(AX), CX	// length of string
 	MOVQ	(AX), AX	// string data
-#ifndef GOEXPERIMENT_regabiargs
-	LEAQ	ret+16(FP), DX
-#endif
 	JMP	aeshashbody<>(SB)
 noaes:
 	JMP	runtime·strhashFallback<ABIInternal>(SB)
 
 // AX: data
-#ifdef GOEXPERIMENT_regabiargs
 // BX: hash seed
-#else
-// h+8(FP): hash seed
-#endif
 // CX: length
-#ifdef GOEXPERIMENT_regabiargs
 // At return: AX = return value
-#else
-// DX: address to put return value
-#endif
 TEXT aeshashbody<>(SB),NOSPLIT,$0-0
 	// Fill an SSE register with our seeds.
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0				// 64 bits of per-table hash seed
-#else
-	MOVQ	h+8(FP), X0			// 64 bits of per-table hash seed
-#endif
 	PINSRW	$4, CX, X0			// 16 bits of length
 	PSHUFHW $0, X0, X0			// repeat length 4 times total
 	MOVO	X0, X1				// save unscrambled seed
@@ -1100,11 +1009,7 @@
 	AESENC	X1, X1	// scramble combo 3 times
 	AESENC	X1, X1
 	AESENC	X1, X1
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X1, AX	// return X1
-#else
-	MOVQ	X1, (DX)
-#endif
 	RET
 
 endofpage:
@@ -1120,11 +1025,7 @@
 aes0:
 	// Return scrambled input seed
 	AESENC	X0, X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, (DX)
-#endif
 	RET
 
 aes16:
@@ -1154,11 +1055,7 @@
 
 	// combine results
 	PXOR	X3, X2
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X2, AX	// return X2
-#else
-	MOVQ	X2, (DX)
-#endif
 	RET
 
 aes33to64:
@@ -1200,11 +1097,7 @@
 	PXOR	X6, X4
 	PXOR	X7, X5
 	PXOR	X5, X4
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X4, AX	// return X4
-#else
-	MOVQ	X4, (DX)
-#endif
 	RET
 
 aes65to128:
@@ -1286,15 +1179,9 @@
 	PXOR	X10, X8
 	PXOR	X11, X9
 	PXOR	X9, X8
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X8, AX	// return X8
-#else
-	MOVQ	X8, (DX)
-#endif
 	RET
 
 aes129plus:
@@ -1410,41 +1297,24 @@
 	PXOR	X10, X8
 	PXOR	X11, X9
 	PXOR	X9, X8
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X8, AX	// return X8
-#else
-	MOVQ	X8, (DX)
-#endif
 	RET
 
 // func memhash32(p unsafe.Pointer, h uintptr) uintptr
 // ABIInternal for performance.
 TEXT runtime·memhash32<ABIInternal>(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0	// X0 = seed
-#else
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	h+8(FP), X0	// seed
-#endif
 	PINSRD	$2, (AX), X0	// data
 	AESENC	runtime·aeskeysched+0(SB), X0
 	AESENC	runtime·aeskeysched+16(SB), X0
 	AESENC	runtime·aeskeysched+32(SB), X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, ret+16(FP)
-#endif
 	RET
 noaes:
 	JMP	runtime·memhash32Fallback<ABIInternal>(SB)
@@ -1452,28 +1322,16 @@
 // func memhash64(p unsafe.Pointer, h uintptr) uintptr
 // ABIInternal for performance.
 TEXT runtime·memhash64<ABIInternal>(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
-#else
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0	// X0 = seed
-#else
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	h+8(FP), X0	// seed
-#endif
 	PINSRQ	$1, (AX), X0	// data
 	AESENC	runtime·aeskeysched+0(SB), X0
 	AESENC	runtime·aeskeysched+16(SB), X0
 	AESENC	runtime·aeskeysched+32(SB), X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, ret+16(FP)
-#endif
 	RET
 noaes:
 	JMP	runtime·memhash64Fallback<ABIInternal>(SB)
@@ -1596,10 +1454,10 @@
 // This function is injected from the signal handler for panicking
 // signals. It is quite painful to set X15 in the signal context,
 // so we do it here.
-TEXT ·sigpanic0<ABIInternal>(SB),NOSPLIT,$0-0
-#ifdef GOEXPERIMENT_regabig
+TEXT ·sigpanic0(SB),NOSPLIT,$0-0
 	get_tls(R14)
 	MOVQ	g(R14), R14
+#ifndef GOOS_plan9
 	XORPS	X15, X15
 #endif
 	JMP	·sigpanic<ABIInternal>(SB)
@@ -1619,13 +1477,7 @@
 	MOVQ	R13, 104(SP)
 	// TODO: Consider passing g.m.p in as an argument so they can be shared
 	// across a sequence of write barriers.
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), R13
-#else
-	get_tls(R13)
-	MOVQ	g(R13), R13
-	MOVQ	g_m(R13), R13
-#endif
 	MOVQ	m_p(R13), R13
 	MOVQ	(p_wbBuf+wbBuf_next)(R13), R12
 	// Increment wbBuf.next position.
@@ -1956,146 +1808,61 @@
 // The tail call makes these stubs disappear in backtraces.
 // Defined as ABIInternal since they do not use the stack-based Go ABI.
 TEXT runtime·panicIndex<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicIndex<ABIInternal>(SB)
 TEXT runtime·panicIndexU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicIndexU<ABIInternal>(SB)
 TEXT runtime·panicSliceAlen<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAlen<ABIInternal>(SB)
 TEXT runtime·panicSliceAlenU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAlenU<ABIInternal>(SB)
 TEXT runtime·panicSliceAcap<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAcap<ABIInternal>(SB)
 TEXT runtime·panicSliceAcapU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAcapU<ABIInternal>(SB)
 TEXT runtime·panicSliceB<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceB<ABIInternal>(SB)
 TEXT runtime·panicSliceBU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceBU<ABIInternal>(SB)
 TEXT runtime·panicSlice3Alen<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3Alen<ABIInternal>(SB)
 TEXT runtime·panicSlice3AlenU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3AlenU<ABIInternal>(SB)
 TEXT runtime·panicSlice3Acap<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3Acap<ABIInternal>(SB)
 TEXT runtime·panicSlice3AcapU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3AcapU<ABIInternal>(SB)
 TEXT runtime·panicSlice3B<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3B<ABIInternal>(SB)
 TEXT runtime·panicSlice3BU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3BU<ABIInternal>(SB)
 TEXT runtime·panicSlice3C<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3C<ABIInternal>(SB)
 TEXT runtime·panicSlice3CU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3CU<ABIInternal>(SB)
 TEXT runtime·panicSliceConvert<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceConvert<ABIInternal>(SB)
 
 #ifdef GOOS_android
diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s
index 6d3573d..a116478 100644
--- a/src/runtime/asm_arm.s
+++ b/src/runtime/asm_arm.s
@@ -168,14 +168,13 @@
 	BL	runtime·schedinit(SB)
 
 	// create a new goroutine to start program
+	SUB	$8, R13
 	MOVW	$runtime·mainPC(SB), R0
-	MOVW.W	R0, -4(R13)
-	MOVW	$8, R0
-	MOVW.W	R0, -4(R13)
+	MOVW	R0, 4(R13)	// arg 1: fn
 	MOVW	$0, R0
-	MOVW.W	R0, -4(R13)	// push $0 as guard
+	MOVW	R0, 0(R13)	// dummy LR
 	BL	runtime·newproc(SB)
-	MOVW	$12(R13), R13	// pop args and LR
+	ADD	$8, R13	// pop args and LR
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -507,20 +506,6 @@
 CALLFN(·call536870912, 536870912)
 CALLFN(·call1073741824, 1073741824)
 
-// void jmpdefer(fn, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 4 bytes to get back to BL deferreturn
-// 3. B to fn
-TEXT runtime·jmpdefer(SB),NOSPLIT,$0-8
-	MOVW	0(R13), LR
-	MOVW	$-4(LR), LR	// BL deferreturn
-	MOVW	fv+0(FP), R7
-	MOVW	argp+4(FP), R13
-	MOVW	$-4(R13), R13	// SP is 4 below argp, due to saved LR
-	MOVW	0(R7), R1
-	B	(R1)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
diff --git a/src/runtime/asm_arm64.s b/src/runtime/asm_arm64.s
index 2d49539..e51ce2f 100644
--- a/src/runtime/asm_arm64.s
+++ b/src/runtime/asm_arm64.s
@@ -87,14 +87,11 @@
 
 	// create a new goroutine to start program
 	MOVD	$runtime·mainPC(SB), R0		// entry
-	MOVD	RSP, R7
-	MOVD.W	$0, -8(R7)
-	MOVD.W	R0, -8(R7)
-	MOVD.W	$0, -8(R7)
-	MOVD.W	$0, -8(R7)
-	MOVD	R7, RSP
+	SUB	$16, RSP
+	MOVD	R0, 8(RSP) // arg
+	MOVD	$0, 0(RSP) // dummy LR
 	BL	runtime·newproc(SB)
-	ADD	$32, RSP
+	ADD	$16, RSP
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -103,7 +100,7 @@
 	MOVD	R0, (R0)	// boom
 	UNDEF
 
-DATA	runtime·mainPC+0(SB)/8,$runtime·main(SB)
+DATA	runtime·mainPC+0(SB)/8,$runtime·main<ABIInternal>(SB)
 GLOBL	runtime·mainPC(SB),RODATA,$8
 
 TEXT runtime·breakpoint(SB),NOSPLIT|NOFRAME,$0-0
@@ -152,7 +149,13 @@
 // Switch to m->g0's stack, call fn(g).
 // Fn must never return. It should gogo(&g->sched)
 // to keep running g.
-TEXT runtime·mcall(SB), NOSPLIT|NOFRAME, $0-8
+TEXT runtime·mcall<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-8
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R0, R26				// context
+#else
+	MOVD	fn+0(FP), R26			// context
+#endif
+
 	// Save caller state in g->sched
 	MOVD	RSP, R0
 	MOVD	R0, (g_sched+gobuf_sp)(g)
@@ -168,14 +171,18 @@
 	CMP	g, R3
 	BNE	2(PC)
 	B	runtime·badmcall(SB)
-	MOVD	fn+0(FP), R26			// context
-	MOVD	0(R26), R4			// code pointer
+
 	MOVD	(g_sched+gobuf_sp)(g), R0
 	MOVD	R0, RSP	// sp = m->g0->sched.sp
 	MOVD	(g_sched+gobuf_bp)(g), R29
-	MOVD	R3, -8(RSP)
-	MOVD	$0, -16(RSP)
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R3, R0				// arg = g
+#else
+	MOVD	R3, -8(RSP)			// arg = g
+#endif
+	MOVD	$0, -16(RSP)			// dummy LR
 	SUB	$16, RSP
+	MOVD	0(R26), R4			// code pointer
 	BL	(R4)
 	B	runtime·badmcall2(SB)
 
@@ -310,6 +317,86 @@
 	MOVW	$0, R26
 	B runtime·morestack(SB)
 
+#ifdef GOEXPERIMENT_regabireflect
+// spillArgs stores return values from registers to a *internal/abi.RegArgs in R20.
+TEXT ·spillArgs(SB),NOSPLIT,$0-0
+	MOVD	R0, (0*8)(R20)
+	MOVD	R1, (1*8)(R20)
+	MOVD	R2, (2*8)(R20)
+	MOVD	R3, (3*8)(R20)
+	MOVD	R4, (4*8)(R20)
+	MOVD	R5, (5*8)(R20)
+	MOVD	R6, (6*8)(R20)
+	MOVD	R7, (7*8)(R20)
+	MOVD	R8, (8*8)(R20)
+	MOVD	R9, (9*8)(R20)
+	MOVD	R10, (10*8)(R20)
+	MOVD	R11, (11*8)(R20)
+	MOVD	R12, (12*8)(R20)
+	MOVD	R13, (13*8)(R20)
+	MOVD	R14, (14*8)(R20)
+	MOVD	R15, (15*8)(R20)
+	FMOVD	F0, (16*8)(R20)
+	FMOVD	F1, (17*8)(R20)
+	FMOVD	F2, (18*8)(R20)
+	FMOVD	F3, (19*8)(R20)
+	FMOVD	F4, (20*8)(R20)
+	FMOVD	F5, (21*8)(R20)
+	FMOVD	F6, (22*8)(R20)
+	FMOVD	F7, (23*8)(R20)
+	FMOVD	F8, (24*8)(R20)
+	FMOVD	F9, (25*8)(R20)
+	FMOVD	F10, (26*8)(R20)
+	FMOVD	F11, (27*8)(R20)
+	FMOVD	F12, (28*8)(R20)
+	FMOVD	F13, (29*8)(R20)
+	FMOVD	F14, (30*8)(R20)
+	FMOVD	F15, (31*8)(R20)
+	RET
+
+// unspillArgs loads args into registers from a *internal/abi.RegArgs in R20.
+TEXT ·unspillArgs(SB),NOSPLIT,$0-0
+	MOVD	(0*8)(R20), R0
+	MOVD	(1*8)(R20), R1
+	MOVD	(2*8)(R20), R2
+	MOVD	(3*8)(R20), R3
+	MOVD	(4*8)(R20), R4
+	MOVD	(5*8)(R20), R5
+	MOVD	(6*8)(R20), R6
+	MOVD	(7*8)(R20), R7
+	MOVD	(8*8)(R20), R8
+	MOVD	(9*8)(R20), R9
+	MOVD	(10*8)(R20), R10
+	MOVD	(11*8)(R20), R11
+	MOVD	(12*8)(R20), R12
+	MOVD	(13*8)(R20), R13
+	MOVD	(14*8)(R20), R14
+	MOVD	(15*8)(R20), R15
+	FMOVD	(16*8)(R20), F0
+	FMOVD	(17*8)(R20), F1
+	FMOVD	(18*8)(R20), F2
+	FMOVD	(19*8)(R20), F3
+	FMOVD	(20*8)(R20), F4
+	FMOVD	(21*8)(R20), F5
+	FMOVD	(22*8)(R20), F6
+	FMOVD	(23*8)(R20), F7
+	FMOVD	(24*8)(R20), F8
+	FMOVD	(25*8)(R20), F9
+	FMOVD	(26*8)(R20), F10
+	FMOVD	(27*8)(R20), F11
+	FMOVD	(28*8)(R20), F12
+	FMOVD	(29*8)(R20), F13
+	FMOVD	(30*8)(R20), F14
+	FMOVD	(31*8)(R20), F15
+	RET
+#else
+TEXT ·spillArgs(SB),NOSPLIT,$0-0
+	RET
+
+TEXT ·unspillArgs(SB),NOSPLIT,$0-0
+	RET
+#endif
+
 // reflectcall: call a function with the given argument list
 // func call(stackArgsType *_type, f *FuncVal, stackArgs *byte, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs).
 // we don't have variable-sized frames, so we use a small number
@@ -381,12 +468,17 @@
 	MOVBU.P	R7, 1(R5);			\
 	CMP	R5, R6;				\
 	BNE	-3(PC);				\
+	/* set up argument registers */		\
+	MOVD	regArgs+40(FP), R20;		\
+	CALL	·unspillArgs(SB);		\
 	/* call function */			\
 	MOVD	f+8(FP), R26;			\
-	MOVD	(R26), R0;			\
-	PCDATA  $PCDATA_StackMapIndex, $0;	\
-	BL	(R0);				\
+	MOVD	(R26), R20;			\
+	PCDATA	$PCDATA_StackMapIndex, $0;	\
+	BL	(R20);				\
 	/* copy return values back */		\
+	MOVD	regArgs+40(FP), R20;		\
+	CALL	·spillArgs(SB);		\
 	MOVD	stackArgsType+0(FP), R7;		\
 	MOVD	stackArgs+16(FP), R3;			\
 	MOVWU	stackArgsSize+24(FP), R4;			\
@@ -403,11 +495,12 @@
 // to reflectcallmove. It does not follow the Go ABI; it expects its
 // arguments in registers.
 TEXT callRet<>(SB), NOSPLIT, $48-0
+	NO_LOCAL_POINTERS
 	MOVD	R7, 8(RSP)
 	MOVD	R3, 16(RSP)
 	MOVD	R5, 24(RSP)
 	MOVD	R4, 32(RSP)
-	MOVD	$0, 40(RSP)
+	MOVD	R20, 40(RSP)
 	BL	runtime·reflectcallmove(SB)
 	RET
 
@@ -440,12 +533,14 @@
 CALLFN(·call1073741824, 1073741824)
 
 // func memhash32(p unsafe.Pointer, h uintptr) uintptr
-TEXT runtime·memhash32(SB),NOSPLIT|NOFRAME,$0-24
-	MOVB	runtime·useAeshash(SB), R0
-	CBZ	R0, noaes
+TEXT runtime·memhash32<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-24
+	MOVB	runtime·useAeshash(SB), R10
+	CBZ	R10, noaes
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	p+0(FP), R0
 	MOVD	h+8(FP), R1
 	MOVD	$ret+16(FP), R2
+#endif
 	MOVD	$runtime·aeskeysched+0(SB), R3
 
 	VEOR	V0.B16, V0.B16, V0.B16
@@ -459,18 +554,24 @@
 	AESMC	V0.B16, V0.B16
 	AESE	V2.B16, V0.B16
 
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V0.D[0], R0
+#else
 	VST1	[V0.D1], (R2)
+#endif
 	RET
 noaes:
-	B	runtime·memhash32Fallback(SB)
+	B	runtime·memhash32Fallback<ABIInternal>(SB)
 
 // func memhash64(p unsafe.Pointer, h uintptr) uintptr
-TEXT runtime·memhash64(SB),NOSPLIT|NOFRAME,$0-24
-	MOVB	runtime·useAeshash(SB), R0
-	CBZ	R0, noaes
+TEXT runtime·memhash64<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-24
+	MOVB	runtime·useAeshash(SB), R10
+	CBZ	R10, noaes
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	p+0(FP), R0
 	MOVD	h+8(FP), R1
 	MOVD	$ret+16(FP), R2
+#endif
 	MOVD	$runtime·aeskeysched+0(SB), R3
 
 	VEOR	V0.B16, V0.B16, V0.B16
@@ -484,75 +585,89 @@
 	AESMC	V0.B16, V0.B16
 	AESE	V2.B16, V0.B16
 
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V0.D[0], R0
+#else
 	VST1	[V0.D1], (R2)
+#endif
 	RET
 noaes:
-	B	runtime·memhash64Fallback(SB)
+	B	runtime·memhash64Fallback<ABIInternal>(SB)
 
 // func memhash(p unsafe.Pointer, h, size uintptr) uintptr
-TEXT runtime·memhash(SB),NOSPLIT|NOFRAME,$0-32
-	MOVB	runtime·useAeshash(SB), R0
-	CBZ	R0, noaes
+TEXT runtime·memhash<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-32
+	MOVB	runtime·useAeshash(SB), R10
+	CBZ	R10, noaes
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	p+0(FP), R0
-	MOVD	s+16(FP), R1
-	MOVD	h+8(FP), R3
-	MOVD	$ret+24(FP), R2
+	MOVD	h+8(FP), R1
+	MOVD	s+16(FP), R2
+	MOVD	$ret+24(FP), R8
+#endif
 	B	aeshashbody<>(SB)
 noaes:
-	B	runtime·memhashFallback(SB)
+	B	runtime·memhashFallback<ABIInternal>(SB)
 
 // func strhash(p unsafe.Pointer, h uintptr) uintptr
-TEXT runtime·strhash(SB),NOSPLIT|NOFRAME,$0-24
-	MOVB	runtime·useAeshash(SB), R0
-	CBZ	R0, noaes
-	MOVD	p+0(FP), R10 // string pointer
-	LDP	(R10), (R0, R1) //string data/ length
-	MOVD	h+8(FP), R3
-	MOVD	$ret+16(FP), R2 // return adddress
+TEXT runtime·strhash<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-24
+	MOVB	runtime·useAeshash(SB), R10
+	CBZ	R10, noaes
+#ifdef GOEXPERIMENT_regabiargs
+	LDP	(R0), (R0, R2)	// string data / length
+#else
+	MOVD	p+0(FP), R10	// string pointer
+	LDP	(R10), (R0, R2)	// string data / length
+	MOVD	h+8(FP), R1
+	MOVD	$ret+16(FP), R8	// return adddress
+#endif
 	B	aeshashbody<>(SB)
 noaes:
-	B	runtime·strhashFallback(SB)
+	B	runtime·strhashFallback<ABIInternal>(SB)
 
 // R0: data
-// R1: length
-// R2: address to put return value
-// R3: seed data
+// R1: seed data
+// R2: length
+#ifdef GOEXPERIMENT_regabiargs
+// At return, R0 = return value
+#else
+// R8: address to put return value
+#endif
 TEXT aeshashbody<>(SB),NOSPLIT|NOFRAME,$0
 	VEOR	V30.B16, V30.B16, V30.B16
-	VMOV	R3, V30.D[0]
-	VMOV	R1, V30.D[1] // load length into seed
+	VMOV	R1, V30.D[0]
+	VMOV	R2, V30.D[1] // load length into seed
 
 	MOVD	$runtime·aeskeysched+0(SB), R4
 	VLD1.P	16(R4), [V0.B16]
 	AESE	V30.B16, V0.B16
 	AESMC	V0.B16, V0.B16
-	CMP	$16, R1
+	CMP	$16, R2
 	BLO	aes0to15
 	BEQ	aes16
-	CMP	$32, R1
+	CMP	$32, R2
 	BLS	aes17to32
-	CMP	$64, R1
+	CMP	$64, R2
 	BLS	aes33to64
-	CMP	$128, R1
+	CMP	$128, R2
 	BLS	aes65to128
 	B	aes129plus
 
 aes0to15:
-	CBZ	R1, aes0
+	CBZ	R2, aes0
 	VEOR	V2.B16, V2.B16, V2.B16
-	TBZ	$3, R1, less_than_8
+	TBZ	$3, R2, less_than_8
 	VLD1.P	8(R0), V2.D[0]
 
 less_than_8:
-	TBZ	$2, R1, less_than_4
+	TBZ	$2, R2, less_than_4
 	VLD1.P	4(R0), V2.S[2]
 
 less_than_4:
-	TBZ	$1, R1, less_than_2
+	TBZ	$1, R2, less_than_2
 	VLD1.P	2(R0), V2.H[6]
 
 less_than_2:
-	TBZ	$0, R1, done
+	TBZ	$0, R2, done
 	VLD1	(R0), V2.B[14]
 done:
 	AESE	V0.B16, V2.B16
@@ -561,11 +676,21 @@
 	AESMC	V2.B16, V2.B16
 	AESE	V0.B16, V2.B16
 
-	VST1	[V2.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V2.D[0], R0
+#else
+	VST1	[V2.D1], (R8)
+#endif
 	RET
+
 aes0:
-	VST1	[V0.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V0.D[0], R0
+#else
+	VST1	[V0.D1], (R8)
+#endif
 	RET
+
 aes16:
 	VLD1	(R0), [V2.B16]
 	B	done
@@ -575,7 +700,7 @@
 	VLD1	(R4), [V1.B16]
 	AESE	V30.B16, V1.B16
 	AESMC	V1.B16, V1.B16
-	SUB	$16, R1, R10
+	SUB	$16, R2, R10
 	VLD1.P	(R0)(R10), [V2.B16]
 	VLD1	(R0), [V3.B16]
 
@@ -593,7 +718,11 @@
 	AESE	V1.B16, V3.B16
 
 	VEOR	V3.B16, V2.B16, V2.B16
-	VST1	[V2.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V2.D[0], R0
+#else
+	VST1	[V2.D1], (R8)
+#endif
 	RET
 
 aes33to64:
@@ -604,7 +733,7 @@
 	AESMC	V2.B16, V2.B16
 	AESE	V30.B16, V3.B16
 	AESMC	V3.B16, V3.B16
-	SUB	$32, R1, R10
+	SUB	$32, R2, R10
 
 	VLD1.P	(R0)(R10), [V4.B16, V5.B16]
 	VLD1	(R0), [V6.B16, V7.B16]
@@ -636,7 +765,11 @@
 	VEOR	V7.B16, V5.B16, V5.B16
 	VEOR	V5.B16, V4.B16, V4.B16
 
-	VST1	[V4.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V4.D[0], R0
+#else
+	VST1	[V4.D1], (R8)
+#endif
 	RET
 
 aes65to128:
@@ -657,7 +790,7 @@
 	AESE	V30.B16, V7.B16
 	AESMC	V7.B16, V7.B16
 
-	SUB	$64, R1, R10
+	SUB	$64, R2, R10
 	VLD1.P	(R0)(R10), [V8.B16, V9.B16, V10.B16, V11.B16]
 	VLD1	(R0), [V12.B16, V13.B16, V14.B16, V15.B16]
 	AESE	V0.B16,	 V8.B16
@@ -711,7 +844,11 @@
 	VEOR	V11.B16, V9.B16, V9.B16
 	VEOR	V9.B16, V8.B16, V8.B16
 
-	VST1	[V8.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V8.D[0], R0
+#else
+	VST1	[V8.D1], (R8)
+#endif
 	RET
 
 aes129plus:
@@ -732,12 +869,12 @@
 	AESMC	V6.B16, V6.B16
 	AESE	V30.B16, V7.B16
 	AESMC	V7.B16, V7.B16
-	ADD	R0, R1, R10
+	ADD	R0, R2, R10
 	SUB	$128, R10, R10
 	VLD1.P	64(R10), [V8.B16, V9.B16, V10.B16, V11.B16]
 	VLD1	(R10), [V12.B16, V13.B16, V14.B16, V15.B16]
-	SUB	$1, R1, R1
-	LSR	$7, R1, R1
+	SUB	$1, R2, R2
+	LSR	$7, R2, R2
 
 aesloop:
 	AESE	V8.B16,	 V0.B16
@@ -776,8 +913,8 @@
 	AESMC	V6.B16,  V6.B16
 	AESE	V15.B16, V7.B16
 	AESMC	V7.B16,  V7.B16
-	SUB	$1, R1, R1
-	CBNZ	R1, aesloop
+	SUB	$1, R2, R2
+	CBNZ	R2, aesloop
 
 	AESE	V8.B16,	 V0.B16
 	AESMC	V0.B16,  V0.B16
@@ -830,7 +967,11 @@
 	VEOR	V4.B16, V6.B16, V4.B16
 	VEOR	V4.B16, V0.B16, V0.B16
 
-	VST1	[V0.D1], (R2)
+#ifdef GOEXPERIMENT_regabiargs
+	VMOV	V0.D[0], R0
+#else
+	VST1	[V0.D1], (R8)
+#endif
 	RET
 
 TEXT runtime·procyield(SB),NOSPLIT,$0-0
@@ -841,23 +982,6 @@
 	CBNZ	R0, again
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 4 bytes to get back to BL deferreturn
-// 3. BR to fn
-TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
-	MOVD	0(RSP), R0
-	SUB	$4, R0
-	MOVD	R0, LR
-
-	MOVD	fv+0(FP), R26
-	MOVD	argp+8(FP), R0
-	MOVD	R0, RSP
-	SUB	$8, RSP
-	MOVD	0(R26), R3
-	B	(R3)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
@@ -1052,7 +1176,8 @@
 	MOVD	R1, 8(RSP)
 	MOVD	R2, 16(RSP)
 	MOVD	R3, 24(RSP)
-	BL	runtime·cgocallbackg(SB)
+	MOVD	$runtime·cgocallbackg(SB), R0
+	CALL	(R0) // indirect call to bypass nosplit check. We're on a different stack now.
 
 	// Restore g->sched (== m->curg->sched) from saved values.
 	MOVD	0(RSP), R5
@@ -1158,7 +1283,10 @@
 // It does not clobber any general-purpose registers,
 // but may clobber others (e.g., floating point registers)
 // The act of CALLing gcWriteBarrier will clobber R30 (LR).
-TEXT runtime·gcWriteBarrier(SB),NOSPLIT,$200
+//
+// Defined as ABIInternal since the compiler generates ABIInternal
+// calls to it directly and it does not use the stack-based Go ABI.
+TEXT runtime·gcWriteBarrier<ABIInternal>(SB),NOSPLIT,$200
 	// Save the registers clobbered by the fast path.
 	MOVD	R0, 184(RSP)
 	MOVD	R1, 192(RSP)
@@ -1250,71 +1378,129 @@
 // in the caller's stack frame. These stubs write the args into that stack space and
 // then tail call to the corresponding runtime handler.
 // The tail call makes these stubs disappear in backtraces.
-TEXT runtime·panicIndex(SB),NOSPLIT,$0-16
+//
+// Defined as ABIInternal since the compiler generates ABIInternal
+// calls to it directly and it does not use the stack-based Go ABI.
+TEXT runtime·panicIndex<ABIInternal>(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicIndex(SB)
-TEXT runtime·panicIndexU(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicIndex<ABIInternal>(SB)
+TEXT runtime·panicIndexU<ABIInternal>(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicIndexU(SB)
-TEXT runtime·panicSliceAlen(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicIndexU<ABIInternal>(SB)
+TEXT runtime·panicSliceAlen<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSliceAlen(SB)
-TEXT runtime·panicSliceAlenU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSliceAlen<ABIInternal>(SB)
+TEXT runtime·panicSliceAlenU<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSliceAlenU(SB)
-TEXT runtime·panicSliceAcap(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSliceAlenU<ABIInternal>(SB)
+TEXT runtime·panicSliceAcap<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSliceAcap(SB)
-TEXT runtime·panicSliceAcapU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSliceAcap<ABIInternal>(SB)
+TEXT runtime·panicSliceAcapU<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSliceAcapU(SB)
-TEXT runtime·panicSliceB(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSliceAcapU<ABIInternal>(SB)
+TEXT runtime·panicSliceB<ABIInternal>(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicSliceB(SB)
-TEXT runtime·panicSliceBU(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicSliceB<ABIInternal>(SB)
+TEXT runtime·panicSliceBU<ABIInternal>(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicSliceBU(SB)
-TEXT runtime·panicSlice3Alen(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicSliceBU<ABIInternal>(SB)
+TEXT runtime·panicSlice3Alen<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSlice3Alen(SB)
-TEXT runtime·panicSlice3AlenU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3Alen<ABIInternal>(SB)
+TEXT runtime·panicSlice3AlenU<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSlice3AlenU(SB)
-TEXT runtime·panicSlice3Acap(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3AlenU<ABIInternal>(SB)
+TEXT runtime·panicSlice3Acap<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSlice3Acap(SB)
-TEXT runtime·panicSlice3AcapU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3Acap<ABIInternal>(SB)
+TEXT runtime·panicSlice3AcapU<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSlice3AcapU(SB)
-TEXT runtime·panicSlice3B(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3AcapU<ABIInternal>(SB)
+TEXT runtime·panicSlice3B<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSlice3B(SB)
-TEXT runtime·panicSlice3BU(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3B<ABIInternal>(SB)
+TEXT runtime·panicSlice3BU<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R0
+	MOVD	R2, R1
+#else
 	MOVD	R1, x+0(FP)
 	MOVD	R2, y+8(FP)
-	JMP	runtime·goPanicSlice3BU(SB)
-TEXT runtime·panicSlice3C(SB),NOSPLIT,$0-16
+#endif
+	JMP	runtime·goPanicSlice3BU<ABIInternal>(SB)
+TEXT runtime·panicSlice3C<ABIInternal>(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicSlice3C(SB)
-TEXT runtime·panicSlice3CU(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicSlice3C<ABIInternal>(SB)
+TEXT runtime·panicSlice3CU<ABIInternal>(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
-	JMP	runtime·goPanicSlice3CU(SB)
-TEXT runtime·panicSliceConvert(SB),NOSPLIT,$0-16
+	JMP	runtime·goPanicSlice3CU<ABIInternal>(SB)
+TEXT runtime·panicSliceConvert<ABIInternal>(SB),NOSPLIT,$0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R2, R0
+	MOVD	R3, R1
+#else
 	MOVD	R2, x+0(FP)
 	MOVD	R3, y+8(FP)
-	JMP	runtime·goPanicSliceConvert(SB)
+#endif
+	JMP	runtime·goPanicSliceConvert<ABIInternal>(SB)
diff --git a/src/runtime/asm_mips64x.s b/src/runtime/asm_mips64x.s
index d4d2280..b2e2384 100644
--- a/src/runtime/asm_mips64x.s
+++ b/src/runtime/asm_mips64x.s
@@ -63,12 +63,11 @@
 
 	// create a new goroutine to start program
 	MOVV	$runtime·mainPC(SB), R1		// entry
-	ADDV	$-24, R29
-	MOVV	R1, 16(R29)
-	MOVV	R0, 8(R29)
+	ADDV	$-16, R29
+	MOVV	R1, 8(R29)
 	MOVV	R0, 0(R29)
 	JAL	runtime·newproc(SB)
-	ADDV	$24, R29
+	ADDV	$16, R29
 
 	// start this M
 	JAL	runtime·mstart(SB)
@@ -385,22 +384,6 @@
 TEXT runtime·procyield(SB),NOSPLIT,$0-0
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 8 bytes to get back to JAL deferreturn
-// 3. JMP to fn
-TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
-	MOVV	0(R29), R31
-	ADDV	$-8, R31
-
-	MOVV	fv+0(FP), REGCTXT
-	MOVV	argp+8(FP), R29
-	ADDV	$-8, R29
-	NOR	R0, R0	// prevent scheduling
-	MOVV	0(REGCTXT), R4
-	JMP	(R4)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
diff --git a/src/runtime/asm_mipsx.s b/src/runtime/asm_mipsx.s
index ea7edf2..87a1344 100644
--- a/src/runtime/asm_mipsx.s
+++ b/src/runtime/asm_mipsx.s
@@ -64,12 +64,11 @@
 
 	// create a new goroutine to start program
 	MOVW	$runtime·mainPC(SB), R1	// entry
-	ADDU	$-12, R29
-	MOVW	R1, 8(R29)
-	MOVW	R0, 4(R29)
+	ADDU	$-8, R29
+	MOVW	R1, 4(R29)
 	MOVW	R0, 0(R29)
 	JAL	runtime·newproc(SB)
-	ADDU	$12, R29
+	ADDU	$8, R29
 
 	// start this M
 	JAL	runtime·mstart(SB)
@@ -383,22 +382,6 @@
 TEXT runtime·procyield(SB),NOSPLIT,$0-4
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 8 bytes to get back to JAL deferreturn
-// 3. JMP to fn
-TEXT runtime·jmpdefer(SB),NOSPLIT,$0-8
-	MOVW	0(R29), R31
-	ADDU	$-8, R31
-
-	MOVW	fv+0(FP), REGCTXT
-	MOVW	argp+4(FP), R29
-	ADDU	$-4, R29
-	NOR	R0, R0	// prevent scheduling
-	MOVW	0(REGCTXT), R4
-	JMP	(R4)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
diff --git a/src/runtime/asm_ppc64x.s b/src/runtime/asm_ppc64x.s
index 942cc14..5dc96c5 100644
--- a/src/runtime/asm_ppc64x.s
+++ b/src/runtime/asm_ppc64x.s
@@ -94,9 +94,8 @@
 	MOVDU	R0, -8(R1)
 	MOVDU	R0, -8(R1)
 	MOVDU	R0, -8(R1)
-	MOVDU	R0, -8(R1)
 	BL	runtime·newproc(SB)
-	ADD	$(16+FIXED_FRAME), R1
+	ADD	$(8+FIXED_FRAME), R1
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -504,34 +503,6 @@
 	OR	R6, R6, R6	// Set PPR priority back to medium-low
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 8 bytes to get back to either nop or toc reload before deferreturn
-// 3. BR to fn
-// When dynamically linking Go, it is not sufficient to rewind to the BL
-// deferreturn -- we might be jumping between modules and so we need to reset
-// the TOC pointer in r2. To do this, codegen inserts MOVD 24(R1), R2 *before*
-// the BL deferreturn and jmpdefer rewinds to that.
-TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
-	MOVD	0(R1), R31
-	SUB     $8, R31
-	MOVD	R31, LR
-
-	MOVD	fv+0(FP), R11
-	MOVD	argp+8(FP), R1
-	SUB	$FIXED_FRAME, R1
-#ifdef GOOS_aix
-	// AIX won't trigger a SIGSEGV if R11 = nil
-	// So it manually triggers it
-	CMP	R0, R11
-	BNE	2(PC)
-	MOVD	R0, 0(R0)
-#endif
-	MOVD	0(R11), R12
-	MOVD	R12, CTR
-	BR	(CTR)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
diff --git a/src/runtime/asm_riscv64.s b/src/runtime/asm_riscv64.s
index ef7af4e..9927a81 100644
--- a/src/runtime/asm_riscv64.s
+++ b/src/runtime/asm_riscv64.s
@@ -57,12 +57,11 @@
 
 	// create a new goroutine to start program
 	MOV	$runtime·mainPC(SB), T0		// entry
-	ADD	$-24, X2
-	MOV	T0, 16(X2)
-	MOV	ZERO, 8(X2)
+	ADD	$-16, X2
+	MOV	T0, 8(X2)
 	MOV	ZERO, 0(X2)
 	CALL	runtime·newproc(SB)
-	ADD	$24, X2
+	ADD	$16, X2
 
 	// start this M
 	CALL	runtime·mstart(SB)
@@ -249,21 +248,6 @@
 	MOV	gobuf_pc(T0), T0
 	JALR	ZERO, T0
 
-// func jmpdefer(fv *funcval, argp uintptr)
-// called from deferreturn
-// 1. grab stored return address from the caller's frame
-// 2. sub 8 bytes to get back to JAL deferreturn
-// 3. JMP to fn
-TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
-	MOV	0(X2), RA
-	ADD	$-8, RA
-
-	MOV	fv+0(FP), CTXT
-	MOV	argp+8(FP), X2
-	ADD	$-8, X2
-	MOV	0(CTXT), T0
-	JALR	ZERO, T0
-
 // func procyield(cycles uint32)
 TEXT runtime·procyield(SB),NOSPLIT,$0-0
 	RET
diff --git a/src/runtime/asm_s390x.s b/src/runtime/asm_s390x.s
index fb38271..d4110d5 100644
--- a/src/runtime/asm_s390x.s
+++ b/src/runtime/asm_s390x.s
@@ -147,12 +147,11 @@
 
 	// create a new goroutine to start program
 	MOVD	$runtime·mainPC(SB), R2		// entry
-	SUB     $24, R15
-	MOVD 	R2, 16(R15)
-	MOVD 	$0, 8(R15)
+	SUB     $16, R15
+	MOVD 	R2, 8(R15)
 	MOVD 	$0, 0(R15)
 	BL	runtime·newproc(SB)
-	ADD	$24, R15
+	ADD	$16, R15
 
 	// start this M
 	BL	runtime·mstart(SB)
@@ -481,21 +480,6 @@
 TEXT runtime·procyield(SB),NOSPLIT,$0-0
 	RET
 
-// void jmpdefer(fv, sp);
-// called from deferreturn.
-// 1. grab stored LR for caller
-// 2. sub 6 bytes to get back to BL deferreturn (size of BRASL instruction)
-// 3. BR to fn
-TEXT runtime·jmpdefer(SB),NOSPLIT|NOFRAME,$0-16
-	MOVD	0(R15), R1
-	SUB	$6, R1, LR
-
-	MOVD	fv+0(FP), R12
-	MOVD	argp+8(FP), R15
-	SUB	$8, R15
-	MOVD	0(R12), R3
-	BR	(R3)
-
 // Save state of caller into g->sched,
 // but using fake PC from systemstack_switch.
 // Must only be called from functions with no locals ($0)
diff --git a/src/runtime/asm_wasm.s b/src/runtime/asm_wasm.s
index 33c335b..d885da6 100644
--- a/src/runtime/asm_wasm.s
+++ b/src/runtime/asm_wasm.s
@@ -18,8 +18,7 @@
 	CALLNORESUME runtime·args(SB)
 	CALLNORESUME runtime·osinit(SB)
 	CALLNORESUME runtime·schedinit(SB)
-	MOVD $0, 0(SP)
-	MOVD $runtime·mainPC(SB), 8(SP)
+	MOVD $runtime·mainPC(SB), 0(SP)
 	CALLNORESUME runtime·newproc(SB)
 	CALL runtime·mstart(SB) // WebAssembly stack will unwind when switching to another goroutine
 	UNDEF
@@ -194,35 +193,6 @@
 	MOVD $0, RET0
 	RET
 
-TEXT runtime·jmpdefer(SB), NOSPLIT, $0-16
-	MOVD fv+0(FP), CTXT
-
-	Get CTXT
-	I64Eqz
-	If
-		CALLNORESUME runtime·sigpanic<ABIInternal>(SB)
-	End
-
-	// caller sp after CALL
-	I64Load argp+8(FP)
-	I64Const $8
-	I64Sub
-	I32WrapI64
-	Set SP
-
-	// decrease PC_B by 1 to CALL again
-	Get SP
-	I32Load16U (SP)
-	I32Const $1
-	I32Sub
-	I32Store16 $0
-
-	// but first run the deferred function
-	Get CTXT
-	I32WrapI64
-	I64Load $0
-	JMP
-
 TEXT runtime·asminit(SB), NOSPLIT, $0-0
 	// No per-thread init.
 	RET
diff --git a/src/runtime/cgocall.go b/src/runtime/cgocall.go
index 2626216..2f3c609 100644
--- a/src/runtime/cgocall.go
+++ b/src/runtime/cgocall.go
@@ -85,6 +85,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -480,7 +481,7 @@
 		if inheap(uintptr(unsafe.Pointer(it))) {
 			panic(errorString(msg))
 		}
-		p = *(*unsafe.Pointer)(add(p, sys.PtrSize))
+		p = *(*unsafe.Pointer)(add(p, goarch.PtrSize))
 		if !cgoIsGoPointer(p) {
 			return
 		}
@@ -560,7 +561,7 @@
 		}
 		hbits := heapBitsForAddr(base)
 		n := span.elemsize
-		for i = uintptr(0); i < n; i += sys.PtrSize {
+		for i = uintptr(0); i < n; i += goarch.PtrSize {
 			if !hbits.morePointers() {
 				// No more possible pointers.
 				break
diff --git a/src/runtime/cgocheck.go b/src/runtime/cgocheck.go
index 516045c..3acbadf 100644
--- a/src/runtime/cgocheck.go
+++ b/src/runtime/cgocheck.go
@@ -8,7 +8,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -151,7 +151,7 @@
 	// src must be in the regular heap.
 
 	hbits := heapBitsForAddr(uintptr(src))
-	for i := uintptr(0); i < off+size; i += sys.PtrSize {
+	for i := uintptr(0); i < off+size; i += goarch.PtrSize {
 		bits := hbits.bits()
 		if i >= off && bits&bitPointer != 0 {
 			v := *(*unsafe.Pointer)(add(src, i))
@@ -169,22 +169,22 @@
 //go:nosplit
 //go:nowritebarrier
 func cgoCheckBits(src unsafe.Pointer, gcbits *byte, off, size uintptr) {
-	skipMask := off / sys.PtrSize / 8
-	skipBytes := skipMask * sys.PtrSize * 8
+	skipMask := off / goarch.PtrSize / 8
+	skipBytes := skipMask * goarch.PtrSize * 8
 	ptrmask := addb(gcbits, skipMask)
 	src = add(src, skipBytes)
 	off -= skipBytes
 	size += off
 	var bits uint32
-	for i := uintptr(0); i < size; i += sys.PtrSize {
-		if i&(sys.PtrSize*8-1) == 0 {
+	for i := uintptr(0); i < size; i += goarch.PtrSize {
+		if i&(goarch.PtrSize*8-1) == 0 {
 			bits = uint32(*ptrmask)
 			ptrmask = addb(ptrmask, 1)
 		} else {
 			bits >>= 1
 		}
 		if off > 0 {
-			off -= sys.PtrSize
+			off -= goarch.PtrSize
 		} else {
 			if bits&1 != 0 {
 				v := *(*unsafe.Pointer)(add(src, i))
diff --git a/src/runtime/chan.go b/src/runtime/chan.go
index f2a75b3..3cdb5dc 100644
--- a/src/runtime/chan.go
+++ b/src/runtime/chan.go
@@ -18,6 +18,7 @@
 //  c.qcount < c.dataqsiz implies that c.sendq is empty.
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"runtime/internal/math"
 	"unsafe"
@@ -169,7 +170,7 @@
 	}
 
 	if raceenabled {
-		racereadpc(c.raceaddr(), callerpc, funcPC(chansend))
+		racereadpc(c.raceaddr(), callerpc, abi.FuncPCABIInternal(chansend))
 	}
 
 	// Fast path: check for failed non-blocking operation without acquiring the lock.
@@ -365,7 +366,7 @@
 
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(c.raceaddr(), callerpc, funcPC(closechan))
+		racewritepc(c.raceaddr(), callerpc, abi.FuncPCABIInternal(closechan))
 		racerelease(c.raceaddr())
 	}
 
diff --git a/src/runtime/cpuprof.go b/src/runtime/cpuprof.go
index e5d0193..c81ab71 100644
--- a/src/runtime/cpuprof.go
+++ b/src/runtime/cpuprof.go
@@ -13,6 +13,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -166,8 +167,8 @@
 	if p.lostExtra > 0 {
 		hdr := [1]uint64{p.lostExtra}
 		lostStk := [2]uintptr{
-			funcPC(_LostExternalCode) + sys.PCQuantum,
-			funcPC(_ExternalCode) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_LostExternalCode) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_ExternalCode) + sys.PCQuantum,
 		}
 		p.log.write(nil, 0, hdr[:], lostStk[:])
 		p.lostExtra = 0
@@ -176,8 +177,8 @@
 	if p.lostAtomic > 0 {
 		hdr := [1]uint64{p.lostAtomic}
 		lostStk := [2]uintptr{
-			funcPC(_LostSIGPROFDuringAtomic64) + sys.PCQuantum,
-			funcPC(_System) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_LostSIGPROFDuringAtomic64) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_System) + sys.PCQuantum,
 		}
 		p.log.write(nil, 0, hdr[:], lostStk[:])
 		p.lostAtomic = 0
diff --git a/src/runtime/debugcall.go b/src/runtime/debugcall.go
index faddf59..ad66a18 100644
--- a/src/runtime/debugcall.go
+++ b/src/runtime/debugcall.go
@@ -112,7 +112,7 @@
 		// closure and start the goroutine with that closure, but the compiler disallows
 		// implicit closure allocation in the runtime.
 		fn := debugCallWrap1
-		newg := newproc1(*(**funcval)(unsafe.Pointer(&fn)), nil, 0, gp, callerpc)
+		newg := newproc1(*(**funcval)(unsafe.Pointer(&fn)), gp, callerpc)
 		args := &debugCallWrapArgs{
 			dispatch: dispatch,
 			callingG: gp,
diff --git a/src/runtime/defs_plan9_386.go b/src/runtime/defs_plan9_386.go
index 49129b3..428044d 100644
--- a/src/runtime/defs_plan9_386.go
+++ b/src/runtime/defs_plan9_386.go
@@ -61,4 +61,4 @@
 	print("gs    ", hex(u.gs), "\n")
 }
 
-func sigpanictramp() {}
+func sigpanictramp()
diff --git a/src/runtime/defs_plan9_amd64.go b/src/runtime/defs_plan9_amd64.go
index 0099563..15a27fc 100644
--- a/src/runtime/defs_plan9_amd64.go
+++ b/src/runtime/defs_plan9_amd64.go
@@ -78,4 +78,4 @@
 	print("gs    ", hex(u.gs), "\n")
 }
 
-func sigpanictramp() {}
+func sigpanictramp()
diff --git a/src/runtime/duff_arm64.s b/src/runtime/duff_arm64.s
index 128b076..33c4905 100644
--- a/src/runtime/duff_arm64.s
+++ b/src/runtime/duff_arm64.s
@@ -4,7 +4,7 @@
 
 #include "textflag.h"
 
-TEXT runtime·duffzero(SB), NOSPLIT|NOFRAME, $0-0
+TEXT runtime·duffzero<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-0
 	STP.P	(ZR, ZR), 16(R20)
 	STP.P	(ZR, ZR), 16(R20)
 	STP.P	(ZR, ZR), 16(R20)
@@ -71,7 +71,7 @@
 	STP	(ZR, ZR), (R20)
 	RET
 
-TEXT runtime·duffcopy(SB), NOSPLIT|NOFRAME, $0-0
+TEXT runtime·duffcopy<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-0
 	LDP.P	16(R20), (R26, R27)
 	STP.P	(R26, R27), 16(R21)
 
diff --git a/src/runtime/export_debug_test.go b/src/runtime/export_debug_test.go
index fe4c904..a2cef02 100644
--- a/src/runtime/export_debug_test.go
+++ b/src/runtime/export_debug_test.go
@@ -9,7 +9,7 @@
 
 import (
 	"internal/abi"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -115,7 +115,7 @@
 			return false
 		}
 		// Push current PC on the stack.
-		rsp := ctxt.rsp() - sys.PtrSize
+		rsp := ctxt.rsp() - goarch.PtrSize
 		*(*uint64)(unsafe.Pointer(uintptr(rsp))) = ctxt.rip()
 		ctxt.set_rsp(rsp)
 		// Write the argument frame size.
@@ -125,7 +125,7 @@
 		h.savedFP = *h.savedRegs.fpstate
 		h.savedRegs.fpstate = nil
 		// Set PC to debugCallV2.
-		ctxt.set_rip(uint64(funcPC(debugCallV2)))
+		ctxt.set_rip(uint64(abi.FuncPCABIInternal(debugCallV2)))
 		// Call injected. Switch to the debugCall protocol.
 		testSigtrap = h.handleF
 	case _Grunnable:
@@ -166,7 +166,7 @@
 			storeRegArgs(ctxt.regs(), h.regArgs)
 		}
 		// Push return PC.
-		sp -= sys.PtrSize
+		sp -= goarch.PtrSize
 		ctxt.set_rsp(sp)
 		*(*uint64)(unsafe.Pointer(uintptr(sp))) = ctxt.rip()
 		// Set PC to call and context register.
@@ -182,7 +182,7 @@
 	case 2:
 		// Function panicked. Copy panic out.
 		sp := ctxt.rsp()
-		memmove(unsafe.Pointer(&h.panic), unsafe.Pointer(uintptr(sp)), 2*sys.PtrSize)
+		memmove(unsafe.Pointer(&h.panic), unsafe.Pointer(uintptr(sp)), 2*goarch.PtrSize)
 	case 8:
 		// Call isn't safe. Get the reason.
 		sp := ctxt.rsp()
diff --git a/src/runtime/export_test.go b/src/runtime/export_test.go
index c8d01fb..e727956 100644
--- a/src/runtime/export_test.go
+++ b/src/runtime/export_test.go
@@ -7,6 +7,8 @@
 package runtime
 
 import (
+	"internal/goarch"
+	"internal/goos"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -27,8 +29,6 @@
 var LockedOSThread = lockedOSThread
 var Xadduintptr = atomic.Xadduintptr
 
-var FuncPC = funcPC
-
 var Fastlog2 = fastlog2
 
 var Atoi = atoi
@@ -147,40 +147,28 @@
 	}
 }
 
-// Temporary to enable register ABI bringup.
-// TODO(register args): convert back to local variables in RunSchedLocalQueueEmptyTest that
-// get passed to the "go" stmts there.
-var RunSchedLocalQueueEmptyState struct {
-	done  chan bool
-	ready *uint32
-	p     *p
-}
-
 func RunSchedLocalQueueEmptyTest(iters int) {
 	// Test that runq is not spuriously reported as empty.
 	// Runq emptiness affects scheduling decisions and spurious emptiness
 	// can lead to underutilization (both runnable Gs and idle Ps coexist
 	// for arbitrary long time).
 	done := make(chan bool, 1)
-	RunSchedLocalQueueEmptyState.done = done
 	p := new(p)
-	RunSchedLocalQueueEmptyState.p = p
 	gs := make([]g, 2)
 	ready := new(uint32)
-	RunSchedLocalQueueEmptyState.ready = ready
 	for i := 0; i < iters; i++ {
 		*ready = 0
 		next0 := (i & 1) == 0
 		next1 := (i & 2) == 0
 		runqput(p, &gs[0], next0)
 		go func() {
-			for atomic.Xadd(RunSchedLocalQueueEmptyState.ready, 1); atomic.Load(RunSchedLocalQueueEmptyState.ready) != 2; {
+			for atomic.Xadd(ready, 1); atomic.Load(ready) != 2; {
 			}
-			if runqempty(RunSchedLocalQueueEmptyState.p) {
-				//println("next:", next0, next1)
+			if runqempty(p) {
+				println("next:", next0, next1)
 				throw("queue is empty")
 			}
-			RunSchedLocalQueueEmptyState.done <- true
+			done <- true
 		}()
 		for atomic.Xadd(ready, 1); atomic.Load(ready) != 2; {
 		}
@@ -228,8 +216,6 @@
 func Envs() []string     { return envs }
 func SetEnvs(e []string) { envs = e }
 
-var BigEndian = sys.BigEndian
-
 // For benchmarking.
 
 func BenchSetType(n int, x interface{}) {
@@ -259,7 +245,7 @@
 	})
 }
 
-const PtrSize = sys.PtrSize
+const PtrSize = goarch.PtrSize
 
 var ForceGCPeriod = &forcegcperiod
 
@@ -1066,7 +1052,7 @@
 //
 // This should not be higher than 0x100*pallocChunkBytes to support
 // mips and mipsle, which only have 31-bit address spaces.
-var BaseChunkIdx = ChunkIdx(chunkIndex(((0xc000*pageAlloc64Bit + 0x100*pageAlloc32Bit) * pallocChunkBytes) + arenaBaseOffset*sys.GoosAix))
+var BaseChunkIdx = ChunkIdx(chunkIndex(((0xc000*pageAlloc64Bit + 0x100*pageAlloc32Bit) * pallocChunkBytes) + arenaBaseOffset*goos.IsAix))
 
 // PageBase returns an address given a chunk index and a page index
 // relative to that chunk.
diff --git a/src/runtime/extern.go b/src/runtime/extern.go
index 48e1e66..eca4062 100644
--- a/src/runtime/extern.go
+++ b/src/runtime/extern.go
@@ -186,7 +186,10 @@
 */
 package runtime
 
-import "runtime/internal/sys"
+import (
+	"internal/goarch"
+	"internal/goos"
+)
 
 // Caller reports file and line number information about function invocations on
 // the calling goroutine's stack. The argument skip is the number of stack frames
@@ -260,8 +263,8 @@
 // GOOS is the running program's operating system target:
 // one of darwin, freebsd, linux, and so on.
 // To view possible combinations of GOOS and GOARCH, run "go tool dist list".
-const GOOS string = sys.GOOS
+const GOOS string = goos.GOOS
 
 // GOARCH is the running program's architecture target:
 // one of 386, amd64, arm, s390x, and so on.
-const GOARCH string = sys.GOARCH
+const GOARCH string = goarch.GOARCH
diff --git a/src/runtime/gc_test.go b/src/runtime/gc_test.go
index 5e7c6c5..0ec5331 100644
--- a/src/runtime/gc_test.go
+++ b/src/runtime/gc_test.go
@@ -21,6 +21,7 @@
 )
 
 func TestGcSys(t *testing.T) {
+	t.Skip("skipping known-flaky test; golang.org/issue/37331")
 	if os.Getenv("GOGC") == "off" {
 		t.Skip("skipping test; GOGC=off in environment")
 	}
diff --git a/src/runtime/heapdump.go b/src/runtime/heapdump.go
index 934e55f..8fb30d9 100644
--- a/src/runtime/heapdump.go
+++ b/src/runtime/heapdump.go
@@ -12,7 +12,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -247,7 +247,7 @@
 	for i := uintptr(0); i < uintptr(cbv.n); i++ {
 		if cbv.ptrbit(i) == 1 {
 			dumpint(fieldKindPtr)
-			dumpint(uint64(offset + i*sys.PtrSize))
+			dumpint(uint64(offset + i*goarch.PtrSize))
 		}
 	}
 }
@@ -298,7 +298,7 @@
 		dumpbv(&child.args, child.argoff)
 	} else {
 		// conservative - everything might be a pointer
-		for off := child.argoff; off < child.argoff+child.arglen; off += sys.PtrSize {
+		for off := child.argoff; off < child.argoff+child.arglen; off += goarch.PtrSize {
 			dumpint(fieldKindPtr)
 			dumpint(uint64(off))
 		}
@@ -307,21 +307,21 @@
 	// Dump fields in the local vars section
 	if stkmap == nil {
 		// No locals information, dump everything.
-		for off := child.arglen; off < s.varp-s.sp; off += sys.PtrSize {
+		for off := child.arglen; off < s.varp-s.sp; off += goarch.PtrSize {
 			dumpint(fieldKindPtr)
 			dumpint(uint64(off))
 		}
 	} else if stkmap.n < 0 {
 		// Locals size information, dump just the locals.
 		size := uintptr(-stkmap.n)
-		for off := s.varp - size - s.sp; off < s.varp-s.sp; off += sys.PtrSize {
+		for off := s.varp - size - s.sp; off < s.varp-s.sp; off += goarch.PtrSize {
 			dumpint(fieldKindPtr)
 			dumpint(uint64(off))
 		}
 	} else if stkmap.n > 0 {
 		// Locals bitmap information, scan just the pointers in
 		// locals.
-		dumpbv(&bv, s.varp-uintptr(bv.n)*sys.PtrSize-s.sp)
+		dumpbv(&bv, s.varp-uintptr(bv.n)*goarch.PtrSize-s.sp)
 	}
 	dumpint(fieldKindEol)
 
@@ -381,12 +381,13 @@
 		dumpint(uint64(uintptr(unsafe.Pointer(gp))))
 		dumpint(uint64(d.sp))
 		dumpint(uint64(d.pc))
-		dumpint(uint64(uintptr(unsafe.Pointer(d.fn))))
+		fn := *(**funcval)(unsafe.Pointer(&d.fn))
+		dumpint(uint64(uintptr(unsafe.Pointer(fn))))
 		if d.fn == nil {
 			// d.fn can be nil for open-coded defers
 			dumpint(uint64(0))
 		} else {
-			dumpint(uint64(uintptr(unsafe.Pointer(d.fn.fn))))
+			dumpint(uint64(uintptr(unsafe.Pointer(fn.fn))))
 		}
 		dumpint(uint64(uintptr(unsafe.Pointer(d.link))))
 	}
@@ -510,7 +511,7 @@
 	} else {
 		dumpbool(true) // big-endian ptrs
 	}
-	dumpint(sys.PtrSize)
+	dumpint(goarch.PtrSize)
 	var arenaStart, arenaEnd uintptr
 	for i1 := range mheap_.arenas {
 		if mheap_.arenas[i1] == nil {
@@ -531,7 +532,7 @@
 	}
 	dumpint(uint64(arenaStart))
 	dumpint(uint64(arenaEnd))
-	dumpstr(sys.GOARCH)
+	dumpstr(goarch.GOARCH)
 	dumpstr(buildVersion)
 	dumpint(uint64(ncpu))
 }
@@ -725,7 +726,7 @@
 
 func makeheapobjbv(p uintptr, size uintptr) bitvector {
 	// Extend the temp buffer if necessary.
-	nptr := size / sys.PtrSize
+	nptr := size / goarch.PtrSize
 	if uintptr(len(tmpbuf)) < nptr/8+1 {
 		if tmpbuf != nil {
 			sysFree(unsafe.Pointer(&tmpbuf[0]), uintptr(len(tmpbuf)), &memstats.other_sys)
diff --git a/src/runtime/iface.go b/src/runtime/iface.go
index cd5fead..3d1d9d6 100644
--- a/src/runtime/iface.go
+++ b/src/runtime/iface.go
@@ -5,8 +5,9 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -63,7 +64,7 @@
 	}
 
 	// Entry doesn't exist yet. Make a new entry & add it.
-	m = (*itab)(persistentalloc(unsafe.Sizeof(itab{})+uintptr(len(inter.mhdr)-1)*sys.PtrSize, 0, &memstats.other_sys))
+	m = (*itab)(persistentalloc(unsafe.Sizeof(itab{})+uintptr(len(inter.mhdr)-1)*goarch.PtrSize, 0, &memstats.other_sys))
 	m.inter = inter
 	m._type = typ
 	// The hash is used in type switches. However, compiler statically generates itab's
@@ -100,7 +101,7 @@
 	mask := t.size - 1
 	h := itabHashFunc(inter, typ) & mask
 	for i := uintptr(1); ; i++ {
-		p := (**itab)(add(unsafe.Pointer(&t.entries), h*sys.PtrSize))
+		p := (**itab)(add(unsafe.Pointer(&t.entries), h*goarch.PtrSize))
 		// Use atomic read here so if we see m != nil, we also see
 		// the initializations of the fields of m.
 		// m := *p
@@ -133,7 +134,7 @@
 		// t2 = new(itabTableType) + some additional entries
 		// We lie and tell malloc we want pointer-free memory because
 		// all the pointed-to values are not in the heap.
-		t2 := (*itabTableType)(mallocgc((2+2*t.size)*sys.PtrSize, nil, true))
+		t2 := (*itabTableType)(mallocgc((2+2*t.size)*goarch.PtrSize, nil, true))
 		t2.size = t.size * 2
 
 		// Copy over entries.
@@ -161,7 +162,7 @@
 	mask := t.size - 1
 	h := itabHashFunc(m.inter, m._type) & mask
 	for i := uintptr(1); ; i++ {
-		p := (**itab)(add(unsafe.Pointer(&t.entries), h*sys.PtrSize))
+		p := (**itab)(add(unsafe.Pointer(&t.entries), h*goarch.PtrSize))
 		m2 := *p
 		if m2 == m {
 			// A given itab may be used in more than one module
@@ -315,26 +316,36 @@
 // The convXXX functions succeed on a nil input, whereas the assertXXX
 // functions fail on a nil input.
 
-func convT2E(t *_type, elem unsafe.Pointer) (e eface) {
+// convT converts a value of type t, which is pointed to by v, to a pointer that can
+// be used as the second word of an interface value.
+func convT(t *_type, v unsafe.Pointer) unsafe.Pointer {
 	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2E))
+		raceReadObjectPC(t, v, getcallerpc(), abi.FuncPCABIInternal(convT))
 	}
 	if msanenabled {
-		msanread(elem, t.size)
+		msanread(v, t.size)
 	}
 	x := mallocgc(t.size, t, true)
-	// TODO: We allocate a zeroed object only to overwrite it with actual data.
-	// Figure out how to avoid zeroing. Also below in convT2Eslice, convT2I, convT2Islice.
-	typedmemmove(t, x, elem)
-	e._type = t
-	e.data = x
-	return
+	typedmemmove(t, x, v)
+	return x
+}
+func convTnoptr(t *_type, v unsafe.Pointer) unsafe.Pointer {
+	// TODO: maybe take size instead of type?
+	if raceenabled {
+		raceReadObjectPC(t, v, getcallerpc(), abi.FuncPCABIInternal(convTnoptr))
+	}
+	if msanenabled {
+		msanread(v, t.size)
+	}
+	x := mallocgc(t.size, t, false)
+	memmove(x, v, t.size)
+	return x
 }
 
 func convT16(val uint16) (x unsafe.Pointer) {
 	if val < uint16(len(staticuint64s)) {
 		x = unsafe.Pointer(&staticuint64s[val])
-		if sys.BigEndian {
+		if goarch.BigEndian {
 			x = add(x, 6)
 		}
 	} else {
@@ -347,7 +358,7 @@
 func convT32(val uint32) (x unsafe.Pointer) {
 	if val < uint32(len(staticuint64s)) {
 		x = unsafe.Pointer(&staticuint64s[val])
-		if sys.BigEndian {
+		if goarch.BigEndian {
 			x = add(x, 4)
 		}
 	} else {
@@ -388,63 +399,16 @@
 	return
 }
 
-func convT2Enoptr(t *_type, elem unsafe.Pointer) (e eface) {
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2Enoptr))
+// convI2I returns the new itab to be used for the destination value
+// when converting a value with itab src to the dst interface.
+func convI2I(dst *interfacetype, src *itab) *itab {
+	if src == nil {
+		return nil
 	}
-	if msanenabled {
-		msanread(elem, t.size)
+	if src.inter == dst {
+		return src
 	}
-	x := mallocgc(t.size, t, false)
-	memmove(x, elem, t.size)
-	e._type = t
-	e.data = x
-	return
-}
-
-func convT2I(tab *itab, elem unsafe.Pointer) (i iface) {
-	t := tab._type
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2I))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
-	x := mallocgc(t.size, t, true)
-	typedmemmove(t, x, elem)
-	i.tab = tab
-	i.data = x
-	return
-}
-
-func convT2Inoptr(tab *itab, elem unsafe.Pointer) (i iface) {
-	t := tab._type
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2Inoptr))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
-	x := mallocgc(t.size, t, false)
-	memmove(x, elem, t.size)
-	i.tab = tab
-	i.data = x
-	return
-}
-
-func convI2I(inter *interfacetype, i iface) (r iface) {
-	tab := i.tab
-	if tab == nil {
-		return
-	}
-	if tab.inter == inter {
-		r.tab = tab
-		r.data = i.data
-		return
-	}
-	r.tab = getitab(inter, tab._type, false)
-	r.data = i.data
-	return
+	return getitab(dst, src._type, false)
 }
 
 func assertI2I(inter *interfacetype, tab *itab) *itab {
@@ -511,7 +475,7 @@
 	// so no other locks/atomics needed.
 	t := itabTable
 	for i := uintptr(0); i < t.size; i++ {
-		m := *(**itab)(add(unsafe.Pointer(&t.entries), i*sys.PtrSize))
+		m := *(**itab)(add(unsafe.Pointer(&t.entries), i*goarch.PtrSize))
 		if m != nil {
 			fn(m)
 		}
diff --git a/src/runtime/internal/atomic/atomic_test.go b/src/runtime/internal/atomic/atomic_test.go
index c9c2eba..2ae60b8 100644
--- a/src/runtime/internal/atomic/atomic_test.go
+++ b/src/runtime/internal/atomic/atomic_test.go
@@ -5,9 +5,9 @@
 package atomic_test
 
 import (
+	"internal/goarch"
 	"runtime"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"testing"
 	"unsafe"
 )
@@ -56,7 +56,7 @@
 // Tests that xadduintptr correctly updates 64-bit values. The place where
 // we actually do so is mstats.go, functions mSysStat{Inc,Dec}.
 func TestXadduintptrOnUint64(t *testing.T) {
-	if sys.BigEndian {
+	if goarch.BigEndian {
 		// On big endian architectures, we never use xadduintptr to update
 		// 64-bit values and hence we skip the test.  (Note that functions
 		// mSysStat{Inc,Dec} in mstats.go have explicit checks for
diff --git a/src/runtime/internal/math/math.go b/src/runtime/internal/math/math.go
index b6bd12d..c3fac36 100644
--- a/src/runtime/internal/math/math.go
+++ b/src/runtime/internal/math/math.go
@@ -4,14 +4,14 @@
 
 package math
 
-import "runtime/internal/sys"
+import "internal/goarch"
 
 const MaxUintptr = ^uintptr(0)
 
 // MulUintptr returns a * b and whether the multiplication overflowed.
 // On supported platforms this is an intrinsic lowered by the compiler.
 func MulUintptr(a, b uintptr) (uintptr, bool) {
-	if a|b < 1<<(4*sys.PtrSize) || a == 0 {
+	if a|b < 1<<(4*goarch.PtrSize) || a == 0 {
 		return a * b, false
 	}
 	overflow := b > MaxUintptr/a
diff --git a/src/runtime/internal/sys/arch_mips64le.go b/src/runtime/internal/sys/arch_mips64le.go
deleted file mode 100644
index 57636ac..0000000
--- a/src/runtime/internal/sys/arch_mips64le.go
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package sys
-
-const (
-	_ArchFamily          = MIPS64
-	_DefaultPhysPageSize = 16384
-	_PCQuantum           = 4
-	_MinFrameSize        = 8
-	_StackAlign          = PtrSize
-)
diff --git a/src/runtime/internal/sys/arch_ppc64le.go b/src/runtime/internal/sys/arch_ppc64le.go
deleted file mode 100644
index 1869213..0000000
--- a/src/runtime/internal/sys/arch_ppc64le.go
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2014 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package sys
-
-const (
-	_ArchFamily          = PPC64
-	_DefaultPhysPageSize = 65536
-	_PCQuantum           = 4
-	_MinFrameSize        = 32
-	_StackAlign          = 16
-)
diff --git a/src/runtime/internal/sys/consts.go b/src/runtime/internal/sys/consts.go
new file mode 100644
index 0000000..fffcf81
--- /dev/null
+++ b/src/runtime/internal/sys/consts.go
@@ -0,0 +1,34 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sys
+
+import (
+	"internal/goarch"
+	"internal/goos"
+)
+
+// AIX requires a larger stack for syscalls.
+const StackGuardMultiplier = StackGuardMultiplierDefault*(1-goos.IsAix) + 2*goos.IsAix
+
+// DefaultPhysPageSize is the default physical page size.
+const DefaultPhysPageSize = goarch.DefaultPhysPageSize
+
+// PCQuantum is the minimal unit for a program counter (1 on x86, 4 on most other systems).
+// The various PC tables record PC deltas pre-divided by PCQuantum.
+const PCQuantum = goarch.PCQuantum
+
+// Int64Align is the required alignment for a 64-bit integer (4 on 32-bit systems, 8 on 64-bit).
+const Int64Align = goarch.PtrSize
+
+// MinFrameSize is the size of the system-reserved words at the bottom
+// of a frame (just above the architectural stack pointer).
+// It is zero on x86 and PtrSize on most non-x86 (LR-based) systems.
+// On PowerPC it is larger, to cover three more reserved words:
+// the compiler word, the link editor word, and the TOC save word.
+const MinFrameSize = goarch.MinFrameSize
+
+// StackAlign is the required alignment of the SP register.
+// The stack must be at least word aligned, but some architectures require more.
+const StackAlign = goarch.StackAlign
diff --git a/src/runtime/internal/sys/gengoos.go b/src/runtime/internal/sys/gengoos.go
deleted file mode 100644
index ffe962f..0000000
--- a/src/runtime/internal/sys/gengoos.go
+++ /dev/null
@@ -1,103 +0,0 @@
-// Copyright 2014 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build ignore
-// +build ignore
-
-package main
-
-import (
-	"bytes"
-	"fmt"
-	"log"
-	"os"
-	"strconv"
-	"strings"
-)
-
-var gooses, goarches []string
-
-func main() {
-	data, err := os.ReadFile("../../../go/build/syslist.go")
-	if err != nil {
-		log.Fatal(err)
-	}
-	const (
-		goosPrefix   = `const goosList = `
-		goarchPrefix = `const goarchList = `
-	)
-	for _, line := range strings.Split(string(data), "\n") {
-		if strings.HasPrefix(line, goosPrefix) {
-			text, err := strconv.Unquote(strings.TrimPrefix(line, goosPrefix))
-			if err != nil {
-				log.Fatalf("parsing goosList: %v", err)
-			}
-			gooses = strings.Fields(text)
-		}
-		if strings.HasPrefix(line, goarchPrefix) {
-			text, err := strconv.Unquote(strings.TrimPrefix(line, goarchPrefix))
-			if err != nil {
-				log.Fatalf("parsing goarchList: %v", err)
-			}
-			goarches = strings.Fields(text)
-		}
-	}
-
-	for _, target := range gooses {
-		if target == "nacl" {
-			continue
-		}
-		var tags []string
-		if target == "linux" {
-			tags = append(tags, "!android") // must explicitly exclude android for linux
-		}
-		if target == "solaris" {
-			tags = append(tags, "!illumos") // must explicitly exclude illumos for solaris
-		}
-		if target == "darwin" {
-			tags = append(tags, "!ios") // must explicitly exclude ios for darwin
-		}
-		tags = append(tags, target) // must explicitly include target for bootstrapping purposes
-		var buf bytes.Buffer
-		fmt.Fprintf(&buf, "// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.\n\n")
-		fmt.Fprintf(&buf, "//go:build %s\n", strings.Join(tags, " && "))
-		fmt.Fprintf(&buf, "// +build %s\n\n", strings.Join(tags, ","))
-		fmt.Fprintf(&buf, "package sys\n\n")
-		fmt.Fprintf(&buf, "const GOOS = `%s`\n\n", target)
-		for _, goos := range gooses {
-			value := 0
-			if goos == target {
-				value = 1
-			}
-			fmt.Fprintf(&buf, "const Goos%s = %d\n", strings.Title(goos), value)
-		}
-		err := os.WriteFile("zgoos_"+target+".go", buf.Bytes(), 0666)
-		if err != nil {
-			log.Fatal(err)
-		}
-	}
-
-	for _, target := range goarches {
-		if target == "amd64p32" {
-			continue
-		}
-		var buf bytes.Buffer
-		fmt.Fprintf(&buf, "// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.\n\n")
-		fmt.Fprintf(&buf, "//go:build %s\n", target)
-		fmt.Fprintf(&buf, "// +build %s\n\n", target) // must explicitly include target for bootstrapping purposes
-		fmt.Fprintf(&buf, "package sys\n\n")
-		fmt.Fprintf(&buf, "const GOARCH = `%s`\n\n", target)
-		for _, goarch := range goarches {
-			value := 0
-			if goarch == target {
-				value = 1
-			}
-			fmt.Fprintf(&buf, "const Goarch%s = %d\n", strings.Title(goarch), value)
-		}
-		err := os.WriteFile("zgoarch_"+target+".go", buf.Bytes(), 0666)
-		if err != nil {
-			log.Fatal(err)
-		}
-	}
-}
diff --git a/src/runtime/internal/sys/sys.go b/src/runtime/internal/sys/sys.go
index 9d9ac45..694101d 100644
--- a/src/runtime/internal/sys/sys.go
+++ b/src/runtime/internal/sys/sys.go
@@ -5,11 +5,3 @@
 // package sys contains system- and configuration- and architecture-specific
 // constants used by the runtime.
 package sys
-
-// The next line makes 'go generate' write the zgo*.go files with
-// per-OS and per-arch information, including constants
-// named Goos$GOOS and Goarch$GOARCH for every
-// known GOOS and GOARCH. The constant is 1 on the
-// current system, 0 otherwise; multiplying by them is
-// useful for defining GOOS- or GOARCH-specific constants.
-//go:generate go run gengoos.go
diff --git a/src/runtime/internal/sys/zgoarch_386.go b/src/runtime/internal/sys/zgoarch_386.go
deleted file mode 100644
index 5b189e7..0000000
--- a/src/runtime/internal/sys/zgoarch_386.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build 386
-// +build 386
-
-package sys
-
-const GOARCH = `386`
-
-const Goarch386 = 1
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_amd64.go b/src/runtime/internal/sys/zgoarch_amd64.go
deleted file mode 100644
index 312977d..0000000
--- a/src/runtime/internal/sys/zgoarch_amd64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build amd64
-// +build amd64
-
-package sys
-
-const GOARCH = `amd64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 1
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_arm.go b/src/runtime/internal/sys/zgoarch_arm.go
deleted file mode 100644
index 5781870..0000000
--- a/src/runtime/internal/sys/zgoarch_arm.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build arm
-// +build arm
-
-package sys
-
-const GOARCH = `arm`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 1
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_arm64.go b/src/runtime/internal/sys/zgoarch_arm64.go
deleted file mode 100644
index f72a1f2..0000000
--- a/src/runtime/internal/sys/zgoarch_arm64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build arm64
-// +build arm64
-
-package sys
-
-const GOARCH = `arm64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 1
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_arm64be.go b/src/runtime/internal/sys/zgoarch_arm64be.go
deleted file mode 100644
index e805646..0000000
--- a/src/runtime/internal/sys/zgoarch_arm64be.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build arm64be
-// +build arm64be
-
-package sys
-
-const GOARCH = `arm64be`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 1
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_armbe.go b/src/runtime/internal/sys/zgoarch_armbe.go
deleted file mode 100644
index d8d4e56..0000000
--- a/src/runtime/internal/sys/zgoarch_armbe.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build armbe
-// +build armbe
-
-package sys
-
-const GOARCH = `armbe`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 1
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_loong64.go b/src/runtime/internal/sys/zgoarch_loong64.go
deleted file mode 100644
index 6f35eb4..0000000
--- a/src/runtime/internal/sys/zgoarch_loong64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build loong64
-// +build loong64
-
-package sys
-
-const GOARCH = `loong64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 1
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips.go b/src/runtime/internal/sys/zgoarch_mips.go
deleted file mode 100644
index bd58a92..0000000
--- a/src/runtime/internal/sys/zgoarch_mips.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips
-// +build mips
-
-package sys
-
-const GOARCH = `mips`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 1
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips64.go b/src/runtime/internal/sys/zgoarch_mips64.go
deleted file mode 100644
index 8e4a3dc..0000000
--- a/src/runtime/internal/sys/zgoarch_mips64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips64
-// +build mips64
-
-package sys
-
-const GOARCH = `mips64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 1
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips64le.go b/src/runtime/internal/sys/zgoarch_mips64le.go
deleted file mode 100644
index d8e0033..0000000
--- a/src/runtime/internal/sys/zgoarch_mips64le.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips64le
-// +build mips64le
-
-package sys
-
-const GOARCH = `mips64le`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 1
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips64p32.go b/src/runtime/internal/sys/zgoarch_mips64p32.go
deleted file mode 100644
index 8549cc0..0000000
--- a/src/runtime/internal/sys/zgoarch_mips64p32.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips64p32
-// +build mips64p32
-
-package sys
-
-const GOARCH = `mips64p32`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 1
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mips64p32le.go b/src/runtime/internal/sys/zgoarch_mips64p32le.go
deleted file mode 100644
index 667b6fe..0000000
--- a/src/runtime/internal/sys/zgoarch_mips64p32le.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mips64p32le
-// +build mips64p32le
-
-package sys
-
-const GOARCH = `mips64p32le`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 1
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_mipsle.go b/src/runtime/internal/sys/zgoarch_mipsle.go
deleted file mode 100644
index 8bedb2b..0000000
--- a/src/runtime/internal/sys/zgoarch_mipsle.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build mipsle
-// +build mipsle
-
-package sys
-
-const GOARCH = `mipsle`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 1
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_ppc.go b/src/runtime/internal/sys/zgoarch_ppc.go
deleted file mode 100644
index fe2196a..0000000
--- a/src/runtime/internal/sys/zgoarch_ppc.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build ppc
-// +build ppc
-
-package sys
-
-const GOARCH = `ppc`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 1
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_ppc64.go b/src/runtime/internal/sys/zgoarch_ppc64.go
deleted file mode 100644
index bd7cc43..0000000
--- a/src/runtime/internal/sys/zgoarch_ppc64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build ppc64
-// +build ppc64
-
-package sys
-
-const GOARCH = `ppc64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 1
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_ppc64le.go b/src/runtime/internal/sys/zgoarch_ppc64le.go
deleted file mode 100644
index e101892..0000000
--- a/src/runtime/internal/sys/zgoarch_ppc64le.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build ppc64le
-// +build ppc64le
-
-package sys
-
-const GOARCH = `ppc64le`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 1
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_riscv.go b/src/runtime/internal/sys/zgoarch_riscv.go
deleted file mode 100644
index 559f860..0000000
--- a/src/runtime/internal/sys/zgoarch_riscv.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build riscv
-// +build riscv
-
-package sys
-
-const GOARCH = `riscv`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 1
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_riscv64.go b/src/runtime/internal/sys/zgoarch_riscv64.go
deleted file mode 100644
index 8485a94..0000000
--- a/src/runtime/internal/sys/zgoarch_riscv64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build riscv64
-// +build riscv64
-
-package sys
-
-const GOARCH = `riscv64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 1
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_s390.go b/src/runtime/internal/sys/zgoarch_s390.go
deleted file mode 100644
index 4c4569e..0000000
--- a/src/runtime/internal/sys/zgoarch_s390.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build s390
-// +build s390
-
-package sys
-
-const GOARCH = `s390`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 1
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_s390x.go b/src/runtime/internal/sys/zgoarch_s390x.go
deleted file mode 100644
index e50d2ed..0000000
--- a/src/runtime/internal/sys/zgoarch_s390x.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build s390x
-// +build s390x
-
-package sys
-
-const GOARCH = `s390x`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 1
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_sparc.go b/src/runtime/internal/sys/zgoarch_sparc.go
deleted file mode 100644
index 0d08752..0000000
--- a/src/runtime/internal/sys/zgoarch_sparc.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build sparc
-// +build sparc
-
-package sys
-
-const GOARCH = `sparc`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 1
-const GoarchSparc64 = 0
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_sparc64.go b/src/runtime/internal/sys/zgoarch_sparc64.go
deleted file mode 100644
index ba405bb..0000000
--- a/src/runtime/internal/sys/zgoarch_sparc64.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build sparc64
-// +build sparc64
-
-package sys
-
-const GOARCH = `sparc64`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 1
-const GoarchWasm = 0
diff --git a/src/runtime/internal/sys/zgoarch_wasm.go b/src/runtime/internal/sys/zgoarch_wasm.go
deleted file mode 100644
index 7c3e5af..0000000
--- a/src/runtime/internal/sys/zgoarch_wasm.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build wasm
-// +build wasm
-
-package sys
-
-const GOARCH = `wasm`
-
-const Goarch386 = 0
-const GoarchAmd64 = 0
-const GoarchAmd64p32 = 0
-const GoarchArm = 0
-const GoarchArmbe = 0
-const GoarchArm64 = 0
-const GoarchArm64be = 0
-const GoarchPpc64 = 0
-const GoarchPpc64le = 0
-const GoarchLoong64 = 0
-const GoarchMips = 0
-const GoarchMipsle = 0
-const GoarchMips64 = 0
-const GoarchMips64le = 0
-const GoarchMips64p32 = 0
-const GoarchMips64p32le = 0
-const GoarchPpc = 0
-const GoarchRiscv = 0
-const GoarchRiscv64 = 0
-const GoarchS390 = 0
-const GoarchS390x = 0
-const GoarchSparc = 0
-const GoarchSparc64 = 0
-const GoarchWasm = 1
diff --git a/src/runtime/internal/sys/zgoos_aix.go b/src/runtime/internal/sys/zgoos_aix.go
deleted file mode 100644
index f3b9074..0000000
--- a/src/runtime/internal/sys/zgoos_aix.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build aix
-// +build aix
-
-package sys
-
-const GOOS = `aix`
-
-const GoosAix = 1
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_android.go b/src/runtime/internal/sys/zgoos_android.go
deleted file mode 100644
index e28baf7..0000000
--- a/src/runtime/internal/sys/zgoos_android.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build android
-// +build android
-
-package sys
-
-const GOOS = `android`
-
-const GoosAix = 0
-const GoosAndroid = 1
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_darwin.go b/src/runtime/internal/sys/zgoos_darwin.go
deleted file mode 100644
index 3c7f7b5..0000000
--- a/src/runtime/internal/sys/zgoos_darwin.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build !ios && darwin
-// +build !ios,darwin
-
-package sys
-
-const GOOS = `darwin`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 1
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_dragonfly.go b/src/runtime/internal/sys/zgoos_dragonfly.go
deleted file mode 100644
index f844d29..0000000
--- a/src/runtime/internal/sys/zgoos_dragonfly.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build dragonfly
-// +build dragonfly
-
-package sys
-
-const GOOS = `dragonfly`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 1
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_freebsd.go b/src/runtime/internal/sys/zgoos_freebsd.go
deleted file mode 100644
index 8999a27..0000000
--- a/src/runtime/internal/sys/zgoos_freebsd.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build freebsd
-// +build freebsd
-
-package sys
-
-const GOOS = `freebsd`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 1
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_hurd.go b/src/runtime/internal/sys/zgoos_hurd.go
deleted file mode 100644
index a546488..0000000
--- a/src/runtime/internal/sys/zgoos_hurd.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build hurd
-// +build hurd
-
-package sys
-
-const GOOS = `hurd`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 1
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_illumos.go b/src/runtime/internal/sys/zgoos_illumos.go
deleted file mode 100644
index 02a4ca0..0000000
--- a/src/runtime/internal/sys/zgoos_illumos.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build illumos
-// +build illumos
-
-package sys
-
-const GOOS = `illumos`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 1
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_ios.go b/src/runtime/internal/sys/zgoos_ios.go
deleted file mode 100644
index 033eec6..0000000
--- a/src/runtime/internal/sys/zgoos_ios.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build ios
-// +build ios
-
-package sys
-
-const GOOS = `ios`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 1
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_js.go b/src/runtime/internal/sys/zgoos_js.go
deleted file mode 100644
index 28226ad..0000000
--- a/src/runtime/internal/sys/zgoos_js.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build js
-// +build js
-
-package sys
-
-const GOOS = `js`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 1
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_linux.go b/src/runtime/internal/sys/zgoos_linux.go
deleted file mode 100644
index 01546e4..0000000
--- a/src/runtime/internal/sys/zgoos_linux.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build !android && linux
-// +build !android,linux
-
-package sys
-
-const GOOS = `linux`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 1
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_netbsd.go b/src/runtime/internal/sys/zgoos_netbsd.go
deleted file mode 100644
index 9d658b2..0000000
--- a/src/runtime/internal/sys/zgoos_netbsd.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build netbsd
-// +build netbsd
-
-package sys
-
-const GOOS = `netbsd`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 1
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_openbsd.go b/src/runtime/internal/sys/zgoos_openbsd.go
deleted file mode 100644
index 0f55454..0000000
--- a/src/runtime/internal/sys/zgoos_openbsd.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build openbsd
-// +build openbsd
-
-package sys
-
-const GOOS = `openbsd`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 1
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_plan9.go b/src/runtime/internal/sys/zgoos_plan9.go
deleted file mode 100644
index d034746..0000000
--- a/src/runtime/internal/sys/zgoos_plan9.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build plan9
-// +build plan9
-
-package sys
-
-const GOOS = `plan9`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 1
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_solaris.go b/src/runtime/internal/sys/zgoos_solaris.go
deleted file mode 100644
index 05c3007..0000000
--- a/src/runtime/internal/sys/zgoos_solaris.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build !illumos && solaris
-// +build !illumos,solaris
-
-package sys
-
-const GOOS = `solaris`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 1
-const GoosWindows = 0
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_windows.go b/src/runtime/internal/sys/zgoos_windows.go
deleted file mode 100644
index 7d07fa3..0000000
--- a/src/runtime/internal/sys/zgoos_windows.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build windows
-// +build windows
-
-package sys
-
-const GOOS = `windows`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 1
-const GoosZos = 0
diff --git a/src/runtime/internal/sys/zgoos_zos.go b/src/runtime/internal/sys/zgoos_zos.go
deleted file mode 100644
index d6e5b9b..0000000
--- a/src/runtime/internal/sys/zgoos_zos.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
-
-//go:build zos
-// +build zos
-
-package sys
-
-const GOOS = `zos`
-
-const GoosAix = 0
-const GoosAndroid = 0
-const GoosDarwin = 0
-const GoosDragonfly = 0
-const GoosFreebsd = 0
-const GoosHurd = 0
-const GoosIllumos = 0
-const GoosIos = 0
-const GoosJs = 0
-const GoosLinux = 0
-const GoosNacl = 0
-const GoosNetbsd = 0
-const GoosOpenbsd = 0
-const GoosPlan9 = 0
-const GoosSolaris = 0
-const GoosWindows = 0
-const GoosZos = 1
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index cc22b0f..f8d5d48 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -101,6 +101,8 @@
 package runtime
 
 import (
+	"internal/goarch"
+	"internal/goos"
 	"runtime/internal/atomic"
 	"runtime/internal/math"
 	"runtime/internal/sys"
@@ -150,7 +152,7 @@
 	//   windows/32       | 4KB        | 3
 	//   windows/64       | 8KB        | 2
 	//   plan9            | 4KB        | 3
-	_NumStackOrders = 4 - sys.PtrSize/4*sys.GoosWindows - 1*sys.GoosPlan9
+	_NumStackOrders = 4 - goarch.PtrSize/4*goos.IsWindows - 1*goos.IsPlan9
 
 	// heapAddrBits is the number of bits in a heap address. On
 	// amd64, addresses are sign-extended beyond heapAddrBits. On
@@ -207,7 +209,7 @@
 	// arenaBaseOffset to offset into the top 4 GiB.
 	//
 	// WebAssembly currently has a limit of 4GB linear memory.
-	heapAddrBits = (_64bit*(1-sys.GoarchWasm)*(1-sys.GoosIos*sys.GoarchArm64))*48 + (1-_64bit+sys.GoarchWasm)*(32-(sys.GoarchMips+sys.GoarchMipsle)) + 33*sys.GoosIos*sys.GoarchArm64
+	heapAddrBits = (_64bit*(1-goarch.IsWasm)*(1-goos.IsIos*goarch.IsArm64))*48 + (1-_64bit+goarch.IsWasm)*(32-(goarch.IsMips+goarch.IsMipsle)) + 33*goos.IsIos*goarch.IsArm64
 
 	// maxAlloc is the maximum size of an allocation. On 64-bit,
 	// it's theoretically possible to allocate 1<<heapAddrBits bytes. On
@@ -248,10 +250,10 @@
 	// logHeapArenaBytes is log_2 of heapArenaBytes. For clarity,
 	// prefer using heapArenaBytes where possible (we need the
 	// constant to compute some other constants).
-	logHeapArenaBytes = (6+20)*(_64bit*(1-sys.GoosWindows)*(1-sys.GoarchWasm)*(1-sys.GoosIos*sys.GoarchArm64)) + (2+20)*(_64bit*sys.GoosWindows) + (2+20)*(1-_64bit) + (2+20)*sys.GoarchWasm + (2+20)*sys.GoosIos*sys.GoarchArm64
+	logHeapArenaBytes = (6+20)*(_64bit*(1-goos.IsWindows)*(1-goarch.IsWasm)*(1-goos.IsIos*goarch.IsArm64)) + (2+20)*(_64bit*goos.IsWindows) + (2+20)*(1-_64bit) + (2+20)*goarch.IsWasm + (2+20)*goos.IsIos*goarch.IsArm64
 
 	// heapArenaBitmapBytes is the size of each heap arena's bitmap.
-	heapArenaBitmapBytes = heapArenaBytes / (sys.PtrSize * 8 / 2)
+	heapArenaBitmapBytes = heapArenaBytes / (goarch.PtrSize * 8 / 2)
 
 	pagesPerArena = heapArenaBytes / pageSize
 
@@ -268,7 +270,7 @@
 	// We use the L1 map on 64-bit Windows because the arena size
 	// is small, but the address space is still 48 bits, and
 	// there's a high cost to having a large L2.
-	arenaL1Bits = 6 * (_64bit * sys.GoosWindows)
+	arenaL1Bits = 6 * (_64bit * goos.IsWindows)
 
 	// arenaL2Bits is the number of bits of the arena number
 	// covered by the second level arena index.
@@ -303,7 +305,7 @@
 	//
 	// On other platforms, the user address space is contiguous
 	// and starts at 0, so no offset is necessary.
-	arenaBaseOffset = 0xffff800000000000*sys.GoarchAmd64 + 0x0a00000000000000*sys.GoosAix
+	arenaBaseOffset = 0xffff800000000000*goarch.IsAmd64 + 0x0a00000000000000*goos.IsAix
 	// A typed version of this constant that will make it into DWARF (for viewcore).
 	arenaBaseOffsetUintptr = uintptr(arenaBaseOffset)
 
@@ -420,8 +422,6 @@
 		throw("bad TinySizeClass")
 	}
 
-	testdefersizes()
-
 	if heapArenaBitmapBytes&(heapArenaBitmapBytes-1) != 0 {
 		// heapBits expects modular arithmetic on bitmap
 		// addresses to work.
@@ -485,7 +485,7 @@
 	lockInit(&globalAlloc.mutex, lockRankGlobalAlloc)
 
 	// Create initial arena growth hints.
-	if sys.PtrSize == 8 {
+	if goarch.PtrSize == 8 {
 		// On a 64-bit machine, we pick the following hints
 		// because:
 		//
@@ -732,7 +732,7 @@
 		l2 := h.arenas[ri.l1()]
 		if l2 == nil {
 			// Allocate an L2 arena map.
-			l2 = (*[1 << arenaL2Bits]*heapArena)(persistentalloc(unsafe.Sizeof(*l2), sys.PtrSize, nil))
+			l2 = (*[1 << arenaL2Bits]*heapArena)(persistentalloc(unsafe.Sizeof(*l2), goarch.PtrSize, nil))
 			if l2 == nil {
 				throw("out of memory allocating heap arena map")
 			}
@@ -743,9 +743,9 @@
 			throw("arena already initialized")
 		}
 		var r *heapArena
-		r = (*heapArena)(h.heapArenaAlloc.alloc(unsafe.Sizeof(*r), sys.PtrSize, &memstats.gcMiscSys))
+		r = (*heapArena)(h.heapArenaAlloc.alloc(unsafe.Sizeof(*r), goarch.PtrSize, &memstats.gcMiscSys))
 		if r == nil {
-			r = (*heapArena)(persistentalloc(unsafe.Sizeof(*r), sys.PtrSize, &memstats.gcMiscSys))
+			r = (*heapArena)(persistentalloc(unsafe.Sizeof(*r), goarch.PtrSize, &memstats.gcMiscSys))
 			if r == nil {
 				throw("out of memory allocating heap arena metadata")
 			}
@@ -753,16 +753,16 @@
 
 		// Add the arena to the arenas list.
 		if len(h.allArenas) == cap(h.allArenas) {
-			size := 2 * uintptr(cap(h.allArenas)) * sys.PtrSize
+			size := 2 * uintptr(cap(h.allArenas)) * goarch.PtrSize
 			if size == 0 {
 				size = physPageSize
 			}
-			newArray := (*notInHeap)(persistentalloc(size, sys.PtrSize, &memstats.gcMiscSys))
+			newArray := (*notInHeap)(persistentalloc(size, goarch.PtrSize, &memstats.gcMiscSys))
 			if newArray == nil {
 				throw("out of memory allocating allArenas")
 			}
 			oldSlice := h.allArenas
-			*(*notInHeapSlice)(unsafe.Pointer(&h.allArenas)) = notInHeapSlice{newArray, len(h.allArenas), int(size / sys.PtrSize)}
+			*(*notInHeapSlice)(unsafe.Pointer(&h.allArenas)) = notInHeapSlice{newArray, len(h.allArenas), int(size / goarch.PtrSize)}
 			copy(h.allArenas, oldSlice)
 			// Do not free the old backing array because
 			// there may be concurrent readers. Since we
@@ -1017,7 +1017,7 @@
 			// Align tiny pointer for required (conservative) alignment.
 			if size&7 == 0 {
 				off = alignUp(off, 8)
-			} else if sys.PtrSize == 4 && size == 12 {
+			} else if goarch.PtrSize == 4 && size == 12 {
 				// Conservatively align 12-byte objects to 8 bytes on 32-bit
 				// systems so that objects whose first field is a 64-bit
 				// value is aligned to 8 bytes and does not cause a fault on
@@ -1088,15 +1088,6 @@
 
 	var scanSize uintptr
 	if !noscan {
-		// If allocating a defer+arg block, now that we've picked a malloc size
-		// large enough to hold everything, cut the "asked for" size down to
-		// just the defer header, so that the GC bitmap will record the arg block
-		// as containing nothing at all (as if it were unused space at the end of
-		// a malloc block caused by size rounding).
-		// The defer arg areas are scanned as part of scanstack.
-		if typ == deferType {
-			dataSize = unsafe.Sizeof(_defer{})
-		}
 		heapBitsSetType(uintptr(x), size, dataSize, typ)
 		if dataSize > typ.size {
 			// Array allocation. If there are any
@@ -1419,7 +1410,7 @@
 				break
 			}
 		}
-		persistent.off = alignUp(sys.PtrSize, align)
+		persistent.off = alignUp(goarch.PtrSize, align)
 	}
 	p := persistent.base.add(persistent.off)
 	persistent.off += size
diff --git a/src/runtime/map.go b/src/runtime/map.go
index 111db56..0cad1a3 100644
--- a/src/runtime/map.go
+++ b/src/runtime/map.go
@@ -54,9 +54,10 @@
 // before the table grows. Typical tables will be somewhat less loaded.
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/math"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -103,7 +104,7 @@
 	sameSizeGrow = 8 // the current map growth is to a new map of the same size
 
 	// sentinel bucket ID for iterator checks
-	noCheck = 1<<(8*sys.PtrSize) - 1
+	noCheck = 1<<(8*goarch.PtrSize) - 1
 )
 
 // isEmpty reports whether the given tophash array entry represents an empty bucket entry.
@@ -182,7 +183,7 @@
 // bucketShift returns 1<<b, optimized for code generation.
 func bucketShift(b uint8) uintptr {
 	// Masking the shift amount allows overflow checks to be elided.
-	return uintptr(1) << (b & (sys.PtrSize*8 - 1))
+	return uintptr(1) << (b & (goarch.PtrSize*8 - 1))
 }
 
 // bucketMask returns 1<<b - 1, optimized for code generation.
@@ -192,7 +193,7 @@
 
 // tophash calculates the tophash value for hash.
 func tophash(hash uintptr) uint8 {
-	top := uint8(hash >> (sys.PtrSize*8 - 8))
+	top := uint8(hash >> (goarch.PtrSize*8 - 8))
 	if top < minTopHash {
 		top += minTopHash
 	}
@@ -205,11 +206,11 @@
 }
 
 func (b *bmap) overflow(t *maptype) *bmap {
-	return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-sys.PtrSize))
+	return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-goarch.PtrSize))
 }
 
 func (b *bmap) setoverflow(t *maptype, ovf *bmap) {
-	*(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-sys.PtrSize)) = ovf
+	*(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-goarch.PtrSize)) = ovf
 }
 
 func (b *bmap) keys() unsafe.Pointer {
@@ -394,7 +395,7 @@
 func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		pc := funcPC(mapaccess1)
+		pc := abi.FuncPCABIInternal(mapaccess1)
 		racereadpc(unsafe.Pointer(h), callerpc, pc)
 		raceReadObjectPC(t.key, key, callerpc, pc)
 	}
@@ -452,7 +453,7 @@
 func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		pc := funcPC(mapaccess2)
+		pc := abi.FuncPCABIInternal(mapaccess2)
 		racereadpc(unsafe.Pointer(h), callerpc, pc)
 		raceReadObjectPC(t.key, key, callerpc, pc)
 	}
@@ -574,7 +575,7 @@
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		pc := funcPC(mapassign)
+		pc := abi.FuncPCABIInternal(mapassign)
 		racewritepc(unsafe.Pointer(h), callerpc, pc)
 		raceReadObjectPC(t.key, key, callerpc, pc)
 	}
@@ -685,7 +686,7 @@
 func mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		pc := funcPC(mapdelete)
+		pc := abi.FuncPCABIInternal(mapdelete)
 		racewritepc(unsafe.Pointer(h), callerpc, pc)
 		raceReadObjectPC(t.key, key, callerpc, pc)
 	}
@@ -802,14 +803,14 @@
 func mapiterinit(t *maptype, h *hmap, it *hiter) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapiterinit))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapiterinit))
 	}
 
 	if h == nil || h.count == 0 {
 		return
 	}
 
-	if unsafe.Sizeof(hiter{})/sys.PtrSize != 12 {
+	if unsafe.Sizeof(hiter{})/goarch.PtrSize != 12 {
 		throw("hash_iter size incorrect") // see cmd/compile/internal/reflectdata/reflect.go
 	}
 	it.t = t
@@ -852,7 +853,7 @@
 	h := it.h
 	if raceenabled {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapiternext))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapiternext))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map iteration and map write")
@@ -978,7 +979,7 @@
 func mapclear(t *maptype, h *hmap) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		pc := funcPC(mapclear)
+		pc := abi.FuncPCABIInternal(mapclear)
 		racewritepc(unsafe.Pointer(h), callerpc, pc)
 	}
 
@@ -1280,11 +1281,11 @@
 	if t.key.equal == nil {
 		throw("runtime.reflect_makemap: unsupported map key type")
 	}
-	if t.key.size > maxKeySize && (!t.indirectkey() || t.keysize != uint8(sys.PtrSize)) ||
+	if t.key.size > maxKeySize && (!t.indirectkey() || t.keysize != uint8(goarch.PtrSize)) ||
 		t.key.size <= maxKeySize && (t.indirectkey() || t.keysize != uint8(t.key.size)) {
 		throw("key size wrong")
 	}
-	if t.elem.size > maxElemSize && (!t.indirectelem() || t.elemsize != uint8(sys.PtrSize)) ||
+	if t.elem.size > maxElemSize && (!t.indirectelem() || t.elemsize != uint8(goarch.PtrSize)) ||
 		t.elem.size <= maxElemSize && (t.indirectelem() || t.elemsize != uint8(t.elem.size)) {
 		throw("elem size wrong")
 	}
@@ -1363,7 +1364,7 @@
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(reflect_maplen))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(reflect_maplen))
 	}
 	return h.count
 }
@@ -1375,7 +1376,7 @@
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(reflect_maplen))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(reflect_maplen))
 	}
 	return h.count
 }
diff --git a/src/runtime/map_fast32.go b/src/runtime/map_fast32.go
index 8d52dad..e80caee 100644
--- a/src/runtime/map_fast32.go
+++ b/src/runtime/map_fast32.go
@@ -5,14 +5,15 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
 func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_fast32))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_fast32))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0])
@@ -52,7 +53,7 @@
 func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_fast32))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_fast32))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0]), false
@@ -95,7 +96,7 @@
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_fast32))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_fast32))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -185,7 +186,7 @@
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_fast32))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_fast32))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -272,7 +273,7 @@
 func mapdelete_fast32(t *maptype, h *hmap, key uint32) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapdelete_fast32))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapdelete_fast32))
 	}
 	if h == nil || h.count == 0 {
 		return
@@ -301,7 +302,7 @@
 			// Only clear key if there are pointers in it.
 			// This can only happen if pointers are 32 bit
 			// wide as 64 bit pointers do not fit into a 32 bit key.
-			if sys.PtrSize == 4 && t.key.ptrdata != 0 {
+			if goarch.PtrSize == 4 && t.key.ptrdata != 0 {
 				// The key must be a pointer as we checked pointers are
 				// 32 bits wide and the key is 32 bits wide also.
 				*(*unsafe.Pointer)(k) = nil
@@ -427,7 +428,7 @@
 				dst.b.tophash[dst.i&(bucketCnt-1)] = top // mask dst.i as an optimization, to avoid a bounds check
 
 				// Copy key.
-				if sys.PtrSize == 4 && t.key.ptrdata != 0 && writeBarrier.enabled {
+				if goarch.PtrSize == 4 && t.key.ptrdata != 0 && writeBarrier.enabled {
 					// Write with a write barrier.
 					*(*unsafe.Pointer)(dst.k) = *(*unsafe.Pointer)(k)
 				} else {
diff --git a/src/runtime/map_fast64.go b/src/runtime/map_fast64.go
index f1368dc..69d8872 100644
--- a/src/runtime/map_fast64.go
+++ b/src/runtime/map_fast64.go
@@ -5,14 +5,15 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
 func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_fast64))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_fast64))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0])
@@ -52,7 +53,7 @@
 func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_fast64))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_fast64))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0]), false
@@ -95,7 +96,7 @@
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_fast64))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_fast64))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -185,7 +186,7 @@
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_fast64))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_fast64))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -272,7 +273,7 @@
 func mapdelete_fast64(t *maptype, h *hmap, key uint64) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapdelete_fast64))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapdelete_fast64))
 	}
 	if h == nil || h.count == 0 {
 		return
@@ -300,7 +301,7 @@
 			}
 			// Only clear key if there are pointers in it.
 			if t.key.ptrdata != 0 {
-				if sys.PtrSize == 8 {
+				if goarch.PtrSize == 8 {
 					*(*unsafe.Pointer)(k) = nil
 				} else {
 					// There are three ways to squeeze at one ore more 32 bit pointers into 64 bits.
@@ -430,7 +431,7 @@
 
 				// Copy key.
 				if t.key.ptrdata != 0 && writeBarrier.enabled {
-					if sys.PtrSize == 8 {
+					if goarch.PtrSize == 8 {
 						// Write with a write barrier.
 						*(*unsafe.Pointer)(dst.k) = *(*unsafe.Pointer)(k)
 					} else {
diff --git a/src/runtime/map_faststr.go b/src/runtime/map_faststr.go
index 0673dd3..4dca882 100644
--- a/src/runtime/map_faststr.go
+++ b/src/runtime/map_faststr.go
@@ -5,14 +5,15 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
 func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_faststr))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_faststr))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0])
@@ -26,7 +27,7 @@
 		b := (*bmap)(h.buckets)
 		if key.len < 32 {
 			// short key, doing lots of comparisons is ok
-			for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+			for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 				k := (*stringStruct)(kptr)
 				if k.len != key.len || isEmpty(b.tophash[i]) {
 					if b.tophash[i] == emptyRest {
@@ -35,14 +36,14 @@
 					continue
 				}
 				if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
-					return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
+					return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize))
 				}
 			}
 			return unsafe.Pointer(&zeroVal[0])
 		}
 		// long key, try not to do more comparisons than necessary
 		keymaybe := uintptr(bucketCnt)
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || isEmpty(b.tophash[i]) {
 				if b.tophash[i] == emptyRest {
@@ -51,7 +52,7 @@
 				continue
 			}
 			if k.str == key.str {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize))
 			}
 			// check first 4 bytes
 			if *((*[4]byte)(key.str)) != *((*[4]byte)(k.str)) {
@@ -68,9 +69,9 @@
 			keymaybe = i
 		}
 		if keymaybe != bucketCnt {
-			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*sys.PtrSize))
+			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*goarch.PtrSize))
 			if memequal(k.str, key.str, uintptr(key.len)) {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.elemsize))
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+keymaybe*uintptr(t.elemsize))
 			}
 		}
 		return unsafe.Pointer(&zeroVal[0])
@@ -91,13 +92,13 @@
 	}
 	top := tophash(hash)
 	for ; b != nil; b = b.overflow(t) {
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || b.tophash[i] != top {
 				continue
 			}
 			if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize))
 			}
 		}
 	}
@@ -107,7 +108,7 @@
 func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_faststr))
+		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_faststr))
 	}
 	if h == nil || h.count == 0 {
 		return unsafe.Pointer(&zeroVal[0]), false
@@ -121,7 +122,7 @@
 		b := (*bmap)(h.buckets)
 		if key.len < 32 {
 			// short key, doing lots of comparisons is ok
-			for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+			for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 				k := (*stringStruct)(kptr)
 				if k.len != key.len || isEmpty(b.tophash[i]) {
 					if b.tophash[i] == emptyRest {
@@ -130,14 +131,14 @@
 					continue
 				}
 				if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
-					return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
+					return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize)), true
 				}
 			}
 			return unsafe.Pointer(&zeroVal[0]), false
 		}
 		// long key, try not to do more comparisons than necessary
 		keymaybe := uintptr(bucketCnt)
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || isEmpty(b.tophash[i]) {
 				if b.tophash[i] == emptyRest {
@@ -146,7 +147,7 @@
 				continue
 			}
 			if k.str == key.str {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize)), true
 			}
 			// check first 4 bytes
 			if *((*[4]byte)(key.str)) != *((*[4]byte)(k.str)) {
@@ -163,9 +164,9 @@
 			keymaybe = i
 		}
 		if keymaybe != bucketCnt {
-			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*sys.PtrSize))
+			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*goarch.PtrSize))
 			if memequal(k.str, key.str, uintptr(key.len)) {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.elemsize)), true
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+keymaybe*uintptr(t.elemsize)), true
 			}
 		}
 		return unsafe.Pointer(&zeroVal[0]), false
@@ -186,13 +187,13 @@
 	}
 	top := tophash(hash)
 	for ; b != nil; b = b.overflow(t) {
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || b.tophash[i] != top {
 				continue
 			}
 			if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
-				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
+				return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize)), true
 			}
 		}
 	}
@@ -205,7 +206,7 @@
 	}
 	if raceenabled {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_faststr))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapassign_faststr))
 	}
 	if h.flags&hashWriting != 0 {
 		throw("concurrent map writes")
@@ -245,7 +246,7 @@
 				}
 				continue
 			}
-			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+i*2*sys.PtrSize))
+			k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+i*2*goarch.PtrSize))
 			if k.len != key.len {
 				continue
 			}
@@ -283,13 +284,13 @@
 	}
 	insertb.tophash[inserti&(bucketCnt-1)] = top // mask inserti to avoid bounds checks
 
-	insertk = add(unsafe.Pointer(insertb), dataOffset+inserti*2*sys.PtrSize)
+	insertk = add(unsafe.Pointer(insertb), dataOffset+inserti*2*goarch.PtrSize)
 	// store new key at insert position
 	*((*stringStruct)(insertk)) = *key
 	h.count++
 
 done:
-	elem := add(unsafe.Pointer(insertb), dataOffset+bucketCnt*2*sys.PtrSize+inserti*uintptr(t.elemsize))
+	elem := add(unsafe.Pointer(insertb), dataOffset+bucketCnt*2*goarch.PtrSize+inserti*uintptr(t.elemsize))
 	if h.flags&hashWriting == 0 {
 		throw("concurrent map writes")
 	}
@@ -300,7 +301,7 @@
 func mapdelete_faststr(t *maptype, h *hmap, ky string) {
 	if raceenabled && h != nil {
 		callerpc := getcallerpc()
-		racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapdelete_faststr))
+		racewritepc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapdelete_faststr))
 	}
 	if h == nil || h.count == 0 {
 		return
@@ -324,7 +325,7 @@
 	top := tophash(hash)
 search:
 	for ; b != nil; b = b.overflow(t) {
-		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
+		for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*goarch.PtrSize) {
 			k := (*stringStruct)(kptr)
 			if k.len != key.len || b.tophash[i] != top {
 				continue
@@ -334,7 +335,7 @@
 			}
 			// Clear key's pointer.
 			k.str = nil
-			e := add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
+			e := add(unsafe.Pointer(b), dataOffset+bucketCnt*2*goarch.PtrSize+i*uintptr(t.elemsize))
 			if t.elem.ptrdata != 0 {
 				memclrHasPointers(e, t.elem.size)
 			} else {
@@ -410,7 +411,7 @@
 		x := &xy[0]
 		x.b = (*bmap)(add(h.buckets, oldbucket*uintptr(t.bucketsize)))
 		x.k = add(unsafe.Pointer(x.b), dataOffset)
-		x.e = add(x.k, bucketCnt*2*sys.PtrSize)
+		x.e = add(x.k, bucketCnt*2*goarch.PtrSize)
 
 		if !h.sameSizeGrow() {
 			// Only calculate y pointers if we're growing bigger.
@@ -418,13 +419,13 @@
 			y := &xy[1]
 			y.b = (*bmap)(add(h.buckets, (oldbucket+newbit)*uintptr(t.bucketsize)))
 			y.k = add(unsafe.Pointer(y.b), dataOffset)
-			y.e = add(y.k, bucketCnt*2*sys.PtrSize)
+			y.e = add(y.k, bucketCnt*2*goarch.PtrSize)
 		}
 
 		for ; b != nil; b = b.overflow(t) {
 			k := add(unsafe.Pointer(b), dataOffset)
-			e := add(k, bucketCnt*2*sys.PtrSize)
-			for i := 0; i < bucketCnt; i, k, e = i+1, add(k, 2*sys.PtrSize), add(e, uintptr(t.elemsize)) {
+			e := add(k, bucketCnt*2*goarch.PtrSize)
+			for i := 0; i < bucketCnt; i, k, e = i+1, add(k, 2*goarch.PtrSize), add(e, uintptr(t.elemsize)) {
 				top := b.tophash[i]
 				if isEmpty(top) {
 					b.tophash[i] = evacuatedEmpty
@@ -450,7 +451,7 @@
 					dst.b = h.newoverflow(t, dst.b)
 					dst.i = 0
 					dst.k = add(unsafe.Pointer(dst.b), dataOffset)
-					dst.e = add(dst.k, bucketCnt*2*sys.PtrSize)
+					dst.e = add(dst.k, bucketCnt*2*goarch.PtrSize)
 				}
 				dst.b.tophash[dst.i&(bucketCnt-1)] = top // mask dst.i as an optimization, to avoid a bounds check
 
@@ -463,7 +464,7 @@
 				// key or elem arrays.  That's ok, as we have the overflow pointer
 				// at the end of the bucket to protect against pointing past the
 				// end of the bucket.
-				dst.k = add(dst.k, 2*sys.PtrSize)
+				dst.k = add(dst.k, 2*goarch.PtrSize)
 				dst.e = add(dst.e, uintptr(t.elemsize))
 			}
 		}
diff --git a/src/runtime/map_test.go b/src/runtime/map_test.go
index 302b3c2..24556b4 100644
--- a/src/runtime/map_test.go
+++ b/src/runtime/map_test.go
@@ -6,10 +6,10 @@
 
 import (
 	"fmt"
+	"internal/goarch"
 	"math"
 	"reflect"
 	"runtime"
-	"runtime/internal/sys"
 	"sort"
 	"strconv"
 	"strings"
@@ -21,7 +21,7 @@
 	// The structure of hmap is defined in runtime/map.go
 	// and in cmd/compile/internal/gc/reflect.go and must be in sync.
 	// The size of hmap should be 48 bytes on 64 bit and 28 bytes on 32 bit platforms.
-	var hmapSize = uintptr(8 + 5*sys.PtrSize)
+	var hmapSize = uintptr(8 + 5*goarch.PtrSize)
 	if runtime.RuntimeHmapSize != hmapSize {
 		t.Errorf("sizeof(runtime.hmap{})==%d, want %d", runtime.RuntimeHmapSize, hmapSize)
 	}
diff --git a/src/runtime/mbarrier.go b/src/runtime/mbarrier.go
index 4994347..3fd1cca 100644
--- a/src/runtime/mbarrier.go
+++ b/src/runtime/mbarrier.go
@@ -15,7 +15,7 @@
 
 import (
 	"internal/abi"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -177,8 +177,8 @@
 //go:linkname reflect_typedmemmove reflect.typedmemmove
 func reflect_typedmemmove(typ *_type, dst, src unsafe.Pointer) {
 	if raceenabled {
-		raceWriteObjectPC(typ, dst, getcallerpc(), funcPC(reflect_typedmemmove))
-		raceReadObjectPC(typ, src, getcallerpc(), funcPC(reflect_typedmemmove))
+		raceWriteObjectPC(typ, dst, getcallerpc(), abi.FuncPCABIInternal(reflect_typedmemmove))
+		raceReadObjectPC(typ, src, getcallerpc(), abi.FuncPCABIInternal(reflect_typedmemmove))
 	}
 	if msanenabled {
 		msanwrite(dst, typ.size)
@@ -197,11 +197,11 @@
 // off must be a multiple of sys.PtrSize.
 //go:linkname reflect_typedmemmovepartial reflect.typedmemmovepartial
 func reflect_typedmemmovepartial(typ *_type, dst, src unsafe.Pointer, off, size uintptr) {
-	if writeBarrier.needed && typ.ptrdata > off && size >= sys.PtrSize {
-		if off&(sys.PtrSize-1) != 0 {
+	if writeBarrier.needed && typ.ptrdata > off && size >= goarch.PtrSize {
+		if off&(goarch.PtrSize-1) != 0 {
 			panic("reflect: internal error: misaligned offset")
 		}
-		pwsize := alignDown(size, sys.PtrSize)
+		pwsize := alignDown(size, goarch.PtrSize)
 		if poff := typ.ptrdata - off; pwsize > poff {
 			pwsize = poff
 		}
@@ -225,7 +225,7 @@
 //
 //go:nosplit
 func reflectcallmove(typ *_type, dst, src unsafe.Pointer, size uintptr, regs *abi.RegArgs) {
-	if writeBarrier.needed && typ != nil && typ.ptrdata != 0 && size >= sys.PtrSize {
+	if writeBarrier.needed && typ != nil && typ.ptrdata != 0 && size >= goarch.PtrSize {
 		bulkBarrierPreWrite(uintptr(dst), uintptr(src), size)
 	}
 	memmove(dst, src, size)
@@ -254,7 +254,7 @@
 	// code and needs its own instrumentation.
 	if raceenabled {
 		callerpc := getcallerpc()
-		pc := funcPC(slicecopy)
+		pc := abi.FuncPCABIInternal(slicecopy)
 		racewriterangepc(dstPtr, uintptr(n)*typ.size, callerpc, pc)
 		racereadrangepc(srcPtr, uintptr(n)*typ.size, callerpc, pc)
 	}
diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
index 32b8db7..9363409 100644
--- a/src/runtime/mbitmap.go
+++ b/src/runtime/mbitmap.go
@@ -46,6 +46,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -326,8 +327,8 @@
 		// we expect to crash in the caller.
 		return
 	}
-	h.bitp = &ha.bitmap[(addr/(sys.PtrSize*4))%heapArenaBitmapBytes]
-	h.shift = uint32((addr / sys.PtrSize) & 3)
+	h.bitp = &ha.bitmap[(addr/(goarch.PtrSize*4))%heapArenaBitmapBytes]
+	h.shift = uint32((addr / goarch.PtrSize) & 3)
 	h.arena = uint32(arena)
 	h.last = &ha.bitmap[len(ha.bitmap)-1]
 	return
@@ -386,10 +387,10 @@
 	// If s is nil, the virtual address has never been part of the heap.
 	// This pointer may be to some mmap'd region, so we allow it.
 	if s == nil {
-		if GOARCH == "amd64" && p == clobberdeadPtr && debug.invalidptr != 0 {
-			// Crash if clobberdeadPtr is seen. Only on AMD64 for now, as
-			// it is the only platform where compiler's clobberdead mode is
-			// implemented. On AMD64 clobberdeadPtr cannot be a valid address.
+		if (GOARCH == "amd64" || GOARCH == "arm64") && p == clobberdeadPtr && debug.invalidptr != 0 {
+			// Crash if clobberdeadPtr is seen. Only on AMD64 and ARM64 for now,
+			// as they are the only platform where compiler's clobberdead mode is
+			// implemented. On these platforms clobberdeadPtr cannot be a valid address.
 			badPointer(s, p, refBase, refOff)
 		}
 		return
@@ -557,7 +558,7 @@
 //
 //go:nosplit
 func bulkBarrierPreWrite(dst, src, size uintptr) {
-	if (dst|src|size)&(sys.PtrSize-1) != 0 {
+	if (dst|src|size)&(goarch.PtrSize-1) != 0 {
 		throw("bulkBarrierPreWrite: unaligned arguments")
 	}
 	if !writeBarrier.needed {
@@ -592,7 +593,7 @@
 	buf := &getg().m.p.ptr().wbBuf
 	h := heapBitsForAddr(dst)
 	if src == 0 {
-		for i := uintptr(0); i < size; i += sys.PtrSize {
+		for i := uintptr(0); i < size; i += goarch.PtrSize {
 			if h.isPointer() {
 				dstx := (*uintptr)(unsafe.Pointer(dst + i))
 				if !buf.putFast(*dstx, 0) {
@@ -602,7 +603,7 @@
 			h = h.next()
 		}
 	} else {
-		for i := uintptr(0); i < size; i += sys.PtrSize {
+		for i := uintptr(0); i < size; i += goarch.PtrSize {
 			if h.isPointer() {
 				dstx := (*uintptr)(unsafe.Pointer(dst + i))
 				srcx := (*uintptr)(unsafe.Pointer(src + i))
@@ -625,7 +626,7 @@
 // created and zeroed with malloc.
 //go:nosplit
 func bulkBarrierPreWriteSrcOnly(dst, src, size uintptr) {
-	if (dst|src|size)&(sys.PtrSize-1) != 0 {
+	if (dst|src|size)&(goarch.PtrSize-1) != 0 {
 		throw("bulkBarrierPreWrite: unaligned arguments")
 	}
 	if !writeBarrier.needed {
@@ -633,7 +634,7 @@
 	}
 	buf := &getg().m.p.ptr().wbBuf
 	h := heapBitsForAddr(dst)
-	for i := uintptr(0); i < size; i += sys.PtrSize {
+	for i := uintptr(0); i < size; i += goarch.PtrSize {
 		if h.isPointer() {
 			srcx := (*uintptr)(unsafe.Pointer(src + i))
 			if !buf.putFast(0, *srcx) {
@@ -653,17 +654,17 @@
 //
 //go:nosplit
 func bulkBarrierBitmap(dst, src, size, maskOffset uintptr, bits *uint8) {
-	word := maskOffset / sys.PtrSize
+	word := maskOffset / goarch.PtrSize
 	bits = addb(bits, word/8)
 	mask := uint8(1) << (word % 8)
 
 	buf := &getg().m.p.ptr().wbBuf
-	for i := uintptr(0); i < size; i += sys.PtrSize {
+	for i := uintptr(0); i < size; i += goarch.PtrSize {
 		if mask == 0 {
 			bits = addb(bits, 1)
 			if *bits == 0 {
 				// Skip 8 words.
-				i += 7 * sys.PtrSize
+				i += 7 * goarch.PtrSize
 				continue
 			}
 			mask = 1
@@ -720,8 +721,8 @@
 	ptrmask := typ.gcdata
 	buf := &getg().m.p.ptr().wbBuf
 	var bits uint32
-	for i := uintptr(0); i < typ.ptrdata; i += sys.PtrSize {
-		if i&(sys.PtrSize*8-1) == 0 {
+	for i := uintptr(0); i < typ.ptrdata; i += goarch.PtrSize {
+		if i&(goarch.PtrSize*8-1) == 0 {
 			bits = uint32(*ptrmask)
 			ptrmask = addb(ptrmask, 1)
 		} else {
@@ -751,14 +752,14 @@
 // Otherwise, it initializes all words to scalar/dead.
 func (h heapBits) initSpan(s *mspan) {
 	// Clear bits corresponding to objects.
-	nw := (s.npages << _PageShift) / sys.PtrSize
+	nw := (s.npages << _PageShift) / goarch.PtrSize
 	if nw%wordsPerBitmapByte != 0 {
 		throw("initSpan: unaligned length")
 	}
 	if h.shift != 0 {
 		throw("initSpan: unaligned base")
 	}
-	isPtrs := sys.PtrSize == 8 && s.elemsize == sys.PtrSize
+	isPtrs := goarch.PtrSize == 8 && s.elemsize == goarch.PtrSize
 	for nw > 0 {
 		hNext, anw := h.forwardOrBoundary(nw)
 		nbyte := anw / wordsPerBitmapByte
@@ -836,7 +837,7 @@
 	// The checks for size == sys.PtrSize and size == 2*sys.PtrSize can therefore
 	// assume that dataSize == size without checking it explicitly.
 
-	if sys.PtrSize == 8 && size == sys.PtrSize {
+	if goarch.PtrSize == 8 && size == goarch.PtrSize {
 		// It's one word and it has pointers, it must be a pointer.
 		// Since all allocated one-word objects are pointers
 		// (non-pointers are aggregated into tinySize allocations),
@@ -862,8 +863,8 @@
 	// objects are at least 4 words long and that their bitmaps start either at the beginning
 	// of a bitmap byte, or half-way in (h.shift of 0 and 2 respectively).
 
-	if size == 2*sys.PtrSize {
-		if typ.size == sys.PtrSize {
+	if size == 2*goarch.PtrSize {
+		if typ.size == goarch.PtrSize {
 			// We're allocating a block big enough to hold two pointers.
 			// On 64-bit, that means the actual object must be two pointers,
 			// or else we'd have used the one-pointer-sized block.
@@ -872,7 +873,7 @@
 			// just the smallest block available. Distinguish by checking dataSize.
 			// (In general the number of instances of typ being allocated is
 			// dataSize/typ.size.)
-			if sys.PtrSize == 4 && dataSize == sys.PtrSize {
+			if goarch.PtrSize == 4 && dataSize == goarch.PtrSize {
 				// 1 pointer object. On 32-bit machines clear the bit for the
 				// unused second word.
 				*h.bitp &^= (bitPointer | bitScan | (bitPointer|bitScan)<<heapBitsShift) << h.shift
@@ -886,38 +887,38 @@
 		// Otherwise typ.size must be 2*sys.PtrSize,
 		// and typ.kind&kindGCProg == 0.
 		if doubleCheck {
-			if typ.size != 2*sys.PtrSize || typ.kind&kindGCProg != 0 {
+			if typ.size != 2*goarch.PtrSize || typ.kind&kindGCProg != 0 {
 				print("runtime: heapBitsSetType size=", size, " but typ.size=", typ.size, " gcprog=", typ.kind&kindGCProg != 0, "\n")
 				throw("heapBitsSetType")
 			}
 		}
 		b := uint32(*ptrmask)
 		hb := b & 3
-		hb |= bitScanAll & ((bitScan << (typ.ptrdata / sys.PtrSize)) - 1)
+		hb |= bitScanAll & ((bitScan << (typ.ptrdata / goarch.PtrSize)) - 1)
 		// Clear the bits for this object so we can set the
 		// appropriate ones.
 		*h.bitp &^= (bitPointer | bitScan | ((bitPointer | bitScan) << heapBitsShift)) << h.shift
 		*h.bitp |= uint8(hb << h.shift)
 		return
-	} else if size == 3*sys.PtrSize {
+	} else if size == 3*goarch.PtrSize {
 		b := uint8(*ptrmask)
 		if doubleCheck {
 			if b == 0 {
 				println("runtime: invalid type ", typ.string())
 				throw("heapBitsSetType: called with non-pointer type")
 			}
-			if sys.PtrSize != 8 {
+			if goarch.PtrSize != 8 {
 				throw("heapBitsSetType: unexpected 3 pointer wide size class on 32 bit")
 			}
 			if typ.kind&kindGCProg != 0 {
 				throw("heapBitsSetType: unexpected GC prog for 3 pointer wide size class")
 			}
-			if typ.size == 2*sys.PtrSize {
+			if typ.size == 2*goarch.PtrSize {
 				print("runtime: heapBitsSetType size=", size, " but typ.size=", typ.size, "\n")
 				throw("heapBitsSetType: inconsistent object sizes")
 			}
 		}
-		if typ.size == sys.PtrSize {
+		if typ.size == goarch.PtrSize {
 			// The type contains a pointer otherwise heapBitsSetType wouldn't have been called.
 			// Since the type is only 1 pointer wide and contains a pointer, its gcdata must be exactly 1.
 			if doubleCheck && *typ.gcdata != 1 {
@@ -1063,8 +1064,8 @@
 		// Filling in bits for an array of typ.
 		// Set up for repetition of ptrmask during main loop.
 		// Note that ptrmask describes only a prefix of
-		const maxBits = sys.PtrSize*8 - 7
-		if typ.ptrdata/sys.PtrSize <= maxBits {
+		const maxBits = goarch.PtrSize*8 - 7
+		if typ.ptrdata/goarch.PtrSize <= maxBits {
 			// Entire ptrmask fits in uintptr with room for a byte fragment.
 			// Load into pbits and never read from ptrmask again.
 			// This is especially important when the ptrmask has
@@ -1075,12 +1076,12 @@
 			// Accumulate ptrmask into b.
 			// ptrmask is sized to describe only typ.ptrdata, but we record
 			// it as describing typ.size bytes, since all the high bits are zero.
-			nb = typ.ptrdata / sys.PtrSize
+			nb = typ.ptrdata / goarch.PtrSize
 			for i := uintptr(0); i < nb; i += 8 {
 				b |= uintptr(*p) << i
 				p = add1(p)
 			}
-			nb = typ.size / sys.PtrSize
+			nb = typ.size / goarch.PtrSize
 
 			// Replicate ptrmask to fill entire pbits uintptr.
 			// Doubling and truncating is fewer steps than
@@ -1091,7 +1092,7 @@
 			pbits = b
 			endnb = nb
 			if nb+nb <= maxBits {
-				for endnb <= sys.PtrSize*8 {
+				for endnb <= goarch.PtrSize*8 {
 					pbits |= pbits << endnb
 					endnb += endnb
 				}
@@ -1110,9 +1111,9 @@
 			endp = nil
 		} else {
 			// Ptrmask is larger. Read it multiple times.
-			n := (typ.ptrdata/sys.PtrSize+7)/8 - 1
+			n := (typ.ptrdata/goarch.PtrSize+7)/8 - 1
 			endp = addb(ptrmask, n)
-			endnb = typ.size/sys.PtrSize - n*8
+			endnb = typ.size/goarch.PtrSize - n*8
 		}
 	}
 	if p != nil {
@@ -1123,12 +1124,12 @@
 
 	if typ.size == dataSize {
 		// Single entry: can stop once we reach the non-pointer data.
-		nw = typ.ptrdata / sys.PtrSize
+		nw = typ.ptrdata / goarch.PtrSize
 	} else {
 		// Repeated instances of typ in an array.
 		// Have to process first N-1 entries in full, but can stop
 		// once we reach the non-pointer data in the final entry.
-		nw = ((dataSize/typ.size-1)*typ.size + typ.ptrdata) / sys.PtrSize
+		nw = ((dataSize/typ.size-1)*typ.size + typ.ptrdata) / goarch.PtrSize
 	}
 	if nw == 0 {
 		// No pointers! Caller was supposed to check.
@@ -1291,7 +1292,7 @@
 	}
 
 	// Change nw from counting possibly-pointer words to total words in allocation.
-	nw = size / sys.PtrSize
+	nw = size / goarch.PtrSize
 
 	// Write whole bitmap bytes.
 	// The first is hb, the rest are zero.
@@ -1325,7 +1326,7 @@
 		h := heapBitsForAddr(x)
 		// cnw is the number of heap words, or bit pairs
 		// remaining (like nw above).
-		cnw := size / sys.PtrSize
+		cnw := size / goarch.PtrSize
 		src := (*uint8)(unsafe.Pointer(x))
 		// We know the first and last byte of the bitmap are
 		// not the same, but it's still possible for small
@@ -1390,7 +1391,7 @@
 	if doubleCheck {
 		// x+size may not point to the heap, so back up one
 		// word and then advance it the way we do above.
-		end := heapBitsForAddr(x + size - sys.PtrSize)
+		end := heapBitsForAddr(x + size - goarch.PtrSize)
 		if outOfPlace {
 			// In out-of-place copying, we just advance
 			// using next.
@@ -1417,11 +1418,11 @@
 		// Double-check that bits to be written were written correctly.
 		// Does not check that other bits were not written, unfortunately.
 		h := heapBitsForAddr(x)
-		nptr := typ.ptrdata / sys.PtrSize
-		ndata := typ.size / sys.PtrSize
+		nptr := typ.ptrdata / goarch.PtrSize
+		ndata := typ.size / goarch.PtrSize
 		count := dataSize / typ.size
-		totalptr := ((count-1)*typ.size + typ.ptrdata) / sys.PtrSize
-		for i := uintptr(0); i < size/sys.PtrSize; i++ {
+		totalptr := ((count-1)*typ.size + typ.ptrdata) / goarch.PtrSize
+		for i := uintptr(0); i < size/goarch.PtrSize; i++ {
 			j := i % ndata
 			var have, want uint8
 			have = (*h.bitp >> h.shift) & (bitPointer | bitScan)
@@ -1446,7 +1447,7 @@
 				print("initial bits h0.bitp=", h0.bitp, " h0.shift=", h0.shift, "\n")
 				print("current bits h.bitp=", h.bitp, " h.shift=", h.shift, " *h.bitp=", hex(*h.bitp), "\n")
 				print("ptrmask=", ptrmask, " p=", p, " endp=", endp, " endnb=", endnb, " pbits=", hex(pbits), " b=", hex(b), " nb=", nb, "\n")
-				println("at word", i, "offset", i*sys.PtrSize, "have", hex(have), "want", hex(want))
+				println("at word", i, "offset", i*goarch.PtrSize, "have", hex(have), "want", hex(want))
 				if typ.kind&kindGCProg != 0 {
 					println("GC program:")
 					dumpGCProg(addb(typ.gcdata, 4))
@@ -1477,14 +1478,14 @@
 // so that the relevant bitmap bytes are not shared with surrounding
 // objects.
 func heapBitsSetTypeGCProg(h heapBits, progSize, elemSize, dataSize, allocSize uintptr, prog *byte) {
-	if sys.PtrSize == 8 && allocSize%(4*sys.PtrSize) != 0 {
+	if goarch.PtrSize == 8 && allocSize%(4*goarch.PtrSize) != 0 {
 		// Alignment will be wrong.
 		throw("heapBitsSetTypeGCProg: small allocation")
 	}
 	var totalBits uintptr
 	if elemSize == dataSize {
 		totalBits = runGCProg(prog, nil, h.bitp, 2)
-		if totalBits*sys.PtrSize != progSize {
+		if totalBits*goarch.PtrSize != progSize {
 			println("runtime: heapBitsSetTypeGCProg: total bits", totalBits, "but progSize", progSize)
 			throw("heapBitsSetTypeGCProg: unexpected bit count")
 		}
@@ -1499,7 +1500,7 @@
 		// repeats that first element to fill the array.
 		var trailer [40]byte // 3 varints (max 10 each) + some bytes
 		i := 0
-		if n := elemSize/sys.PtrSize - progSize/sys.PtrSize; n > 0 {
+		if n := elemSize/goarch.PtrSize - progSize/goarch.PtrSize; n > 0 {
 			// literal(0)
 			trailer[i] = 0x01
 			i++
@@ -1521,7 +1522,7 @@
 		// repeat(elemSize/ptrSize, count-1)
 		trailer[i] = 0x80
 		i++
-		n := elemSize / sys.PtrSize
+		n := elemSize / goarch.PtrSize
 		for ; n >= 0x80; n >>= 7 {
 			trailer[i] = byte(n | 0x80)
 			i++
@@ -1545,10 +1546,10 @@
 		// last element. This will cause the code below to
 		// memclr the dead section of the final array element,
 		// so that scanobject can stop early in the final element.
-		totalBits = (elemSize*(count-1) + progSize) / sys.PtrSize
+		totalBits = (elemSize*(count-1) + progSize) / goarch.PtrSize
 	}
 	endProg := unsafe.Pointer(addb(h.bitp, (totalBits+3)/4))
-	endAlloc := unsafe.Pointer(addb(h.bitp, allocSize/sys.PtrSize/wordsPerBitmapByte))
+	endAlloc := unsafe.Pointer(addb(h.bitp, allocSize/goarch.PtrSize/wordsPerBitmapByte))
 	memclrNoHeapPointers(endProg, uintptr(endAlloc)-uintptr(endProg))
 }
 
@@ -1556,7 +1557,7 @@
 // size the size of the region described by prog, in bytes.
 // The resulting bitvector will have no more than size/sys.PtrSize bits.
 func progToPointerMask(prog *byte, size uintptr) bitvector {
-	n := (size/sys.PtrSize + 7) / 8
+	n := (size/goarch.PtrSize + 7) / 8
 	x := (*[1 << 30]byte)(persistentalloc(n+1, 1, &memstats.buckhash_sys))[:n+1]
 	x[len(x)-1] = 0xa1 // overflow check sentinel
 	n = runGCProg(prog, nil, &x[0], 1)
@@ -1691,7 +1692,7 @@
 		// the pattern to a bit buffer holding at most 7 bits (a partial byte)
 		// it will not overflow.
 		src := dst
-		const maxBits = sys.PtrSize*8 - 7
+		const maxBits = goarch.PtrSize*8 - 7
 		if n <= maxBits {
 			// Start with bits in output buffer.
 			pattern := bits
@@ -1744,7 +1745,7 @@
 				nb := npattern
 				if nb+nb <= maxBits {
 					// Double pattern until the whole uintptr is filled.
-					for nb <= sys.PtrSize*8 {
+					for nb <= goarch.PtrSize*8 {
 						b |= b << nb
 						nb += nb
 					}
@@ -1872,7 +1873,7 @@
 // The result must be deallocated with dematerializeGCProg.
 func materializeGCProg(ptrdata uintptr, prog *byte) *mspan {
 	// Each word of ptrdata needs one bit in the bitmap.
-	bitmapBytes := divRoundUp(ptrdata, 8*sys.PtrSize)
+	bitmapBytes := divRoundUp(ptrdata, 8*goarch.PtrSize)
 	// Compute the number of pages needed for bitmapBytes.
 	pages := divRoundUp(bitmapBytes, pageSize)
 	s := mheap_.allocManual(pages, spanAllocPtrScalarBits)
@@ -1945,7 +1946,7 @@
 func reflect_gcbits(x interface{}) []byte {
 	ret := getgcmask(x)
 	typ := (*ptrtype)(unsafe.Pointer(efaceOf(&x)._type)).elem
-	nptr := typ.ptrdata / sys.PtrSize
+	nptr := typ.ptrdata / goarch.PtrSize
 	for uintptr(len(ret)) > nptr && ret[len(ret)-1] == 0 {
 		ret = ret[:len(ret)-1]
 	}
@@ -1965,10 +1966,10 @@
 		if datap.data <= uintptr(p) && uintptr(p) < datap.edata {
 			bitmap := datap.gcdatamask.bytedata
 			n := (*ptrtype)(unsafe.Pointer(t)).elem.size
-			mask = make([]byte, n/sys.PtrSize)
-			for i := uintptr(0); i < n; i += sys.PtrSize {
-				off := (uintptr(p) + i - datap.data) / sys.PtrSize
-				mask[i/sys.PtrSize] = (*addb(bitmap, off/8) >> (off % 8)) & 1
+			mask = make([]byte, n/goarch.PtrSize)
+			for i := uintptr(0); i < n; i += goarch.PtrSize {
+				off := (uintptr(p) + i - datap.data) / goarch.PtrSize
+				mask[i/goarch.PtrSize] = (*addb(bitmap, off/8) >> (off % 8)) & 1
 			}
 			return
 		}
@@ -1977,10 +1978,10 @@
 		if datap.bss <= uintptr(p) && uintptr(p) < datap.ebss {
 			bitmap := datap.gcbssmask.bytedata
 			n := (*ptrtype)(unsafe.Pointer(t)).elem.size
-			mask = make([]byte, n/sys.PtrSize)
-			for i := uintptr(0); i < n; i += sys.PtrSize {
-				off := (uintptr(p) + i - datap.bss) / sys.PtrSize
-				mask[i/sys.PtrSize] = (*addb(bitmap, off/8) >> (off % 8)) & 1
+			mask = make([]byte, n/goarch.PtrSize)
+			for i := uintptr(0); i < n; i += goarch.PtrSize {
+				off := (uintptr(p) + i - datap.bss) / goarch.PtrSize
+				mask[i/goarch.PtrSize] = (*addb(bitmap, off/8) >> (off % 8)) & 1
 			}
 			return
 		}
@@ -1990,13 +1991,13 @@
 	if base, s, _ := findObject(uintptr(p), 0, 0); base != 0 {
 		hbits := heapBitsForAddr(base)
 		n := s.elemsize
-		mask = make([]byte, n/sys.PtrSize)
-		for i := uintptr(0); i < n; i += sys.PtrSize {
+		mask = make([]byte, n/goarch.PtrSize)
+		for i := uintptr(0); i < n; i += goarch.PtrSize {
 			if hbits.isPointer() {
-				mask[i/sys.PtrSize] = 1
+				mask[i/goarch.PtrSize] = 1
 			}
 			if !hbits.morePointers() {
-				mask = mask[:i/sys.PtrSize]
+				mask = mask[:i/goarch.PtrSize]
 				break
 			}
 			hbits = hbits.next()
@@ -2015,12 +2016,12 @@
 			if locals.n == 0 {
 				return
 			}
-			size := uintptr(locals.n) * sys.PtrSize
+			size := uintptr(locals.n) * goarch.PtrSize
 			n := (*ptrtype)(unsafe.Pointer(t)).elem.size
-			mask = make([]byte, n/sys.PtrSize)
-			for i := uintptr(0); i < n; i += sys.PtrSize {
-				off := (uintptr(p) + i - frame.varp + size) / sys.PtrSize
-				mask[i/sys.PtrSize] = locals.ptrbit(off)
+			mask = make([]byte, n/goarch.PtrSize)
+			for i := uintptr(0); i < n; i += goarch.PtrSize {
+				off := (uintptr(p) + i - frame.varp + size) / goarch.PtrSize
+				mask[i/goarch.PtrSize] = locals.ptrbit(off)
 			}
 		}
 		return
diff --git a/src/runtime/mcheckmark.go b/src/runtime/mcheckmark.go
index ba80ac1..1dd2858 100644
--- a/src/runtime/mcheckmark.go
+++ b/src/runtime/mcheckmark.go
@@ -13,8 +13,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -24,7 +24,7 @@
 // allocation.
 //
 //go:notinheap
-type checkmarksMap [heapArenaBytes / sys.PtrSize / 8]uint8
+type checkmarksMap [heapArenaBytes / goarch.PtrSize / 8]uint8
 
 // If useCheckmark is true, marking of an object uses the checkmark
 // bits instead of the standard mark bits.
diff --git a/src/runtime/memclr_amd64.s b/src/runtime/memclr_amd64.s
index a10f57b..918a4b9 100644
--- a/src/runtime/memclr_amd64.s
+++ b/src/runtime/memclr_amd64.s
@@ -13,14 +13,9 @@
 // func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
 // ABIInternal for performance.
 TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB), NOSPLIT, $0-16
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr
 	// BX = n
 	MOVQ	AX, DI	// DI = ptr
-#else
-	MOVQ	ptr+0(FP), DI
-	MOVQ	n+8(FP), BX
-#endif
 	XORQ	AX, AX
 
 	// MOVOU seems always faster than REP STOSQ.
@@ -37,9 +32,6 @@
 	JE	_8
 	CMPQ	BX, $16
 	JBE	_9through16
-#ifndef GOEXPERIMENT_regabig
-	PXOR	X15, X15
-#endif
 	CMPQ	BX, $32
 	JBE	_17through32
 	CMPQ	BX, $64
diff --git a/src/runtime/memclr_arm64.s b/src/runtime/memclr_arm64.s
index c1a0dce..b80cca6 100644
--- a/src/runtime/memclr_arm64.s
+++ b/src/runtime/memclr_arm64.s
@@ -8,9 +8,11 @@
 
 // func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
 // Also called from assembly in sys_windows_arm64.s without g (but using Go stack convention).
-TEXT runtime·memclrNoHeapPointers(SB),NOSPLIT,$0-16
+TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB),NOSPLIT,$0-16
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	ptr+0(FP), R0
 	MOVD	n+8(FP), R1
+#endif
 
 	CMP	$16, R1
 	// If n is equal to 16 bytes, use zero_exact_16 to zero
diff --git a/src/runtime/memmove_amd64.s b/src/runtime/memmove_amd64.s
index 24c6529..fa0c0e4 100644
--- a/src/runtime/memmove_amd64.s
+++ b/src/runtime/memmove_amd64.s
@@ -34,18 +34,12 @@
 // func memmove(to, from unsafe.Pointer, n uintptr)
 // ABIInternal for performance.
 TEXT runtime·memmove<ABIInternal>(SB), NOSPLIT, $0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = to
 	// BX = from
 	// CX = n
 	MOVQ	AX, DI
 	MOVQ	BX, SI
 	MOVQ	CX, BX
-#else
-	MOVQ	to+0(FP), DI
-	MOVQ	from+8(FP), SI
-	MOVQ	n+16(FP), BX
-#endif
 
 	// REP instructions have a high startup cost, so we handle small sizes
 	// with some straightline code. The REP MOVSQ instruction is really fast
@@ -254,10 +248,8 @@
 	MOVOU	X13, -48(DI)(BX*1)
 	MOVOU	X14, -32(DI)(BX*1)
 	MOVOU	X15, -16(DI)(BX*1)
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
 	RET
 move_256through2048:
 	SUBQ	$256, BX
@@ -297,10 +289,8 @@
 	LEAQ	256(SI), SI
 	LEAQ	256(DI), DI
 	JGE	move_256through2048
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
 	JMP	tail
 
 avxUnaligned:
diff --git a/src/runtime/memmove_arm64.s b/src/runtime/memmove_arm64.s
index 43d2762..bee3b00 100644
--- a/src/runtime/memmove_arm64.s
+++ b/src/runtime/memmove_arm64.s
@@ -26,10 +26,12 @@
 // The loop tail is handled by always copying 64 bytes from the end.
 
 // func memmove(to, from unsafe.Pointer, n uintptr)
-TEXT runtime·memmove(SB), NOSPLIT|NOFRAME, $0-24
+TEXT runtime·memmove<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-24
+#ifndef GOEXPERIMENT_regabiargs
 	MOVD	to+0(FP), R0
 	MOVD	from+8(FP), R1
 	MOVD	n+16(FP), R2
+#endif
 	CBZ	R2, copy0
 
 	// Small copies: 1..16 bytes
diff --git a/src/runtime/mfinal.go b/src/runtime/mfinal.go
index c134a0f..3cdb81e 100644
--- a/src/runtime/mfinal.go
+++ b/src/runtime/mfinal.go
@@ -8,8 +8,8 @@
 
 import (
 	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -26,14 +26,14 @@
 	next    *finblock
 	cnt     uint32
 	_       int32
-	fin     [(_FinBlockSize - 2*sys.PtrSize - 2*4) / unsafe.Sizeof(finalizer{})]finalizer
+	fin     [(_FinBlockSize - 2*goarch.PtrSize - 2*4) / unsafe.Sizeof(finalizer{})]finalizer
 }
 
 var finlock mutex  // protects the following variables
 var fing *g        // goroutine that runs finalizers
 var finq *finblock // list of finalizers that are to be executed
 var finc *finblock // cache of free blocks
-var finptrmask [_FinBlockSize / sys.PtrSize / 8]byte
+var finptrmask [_FinBlockSize / goarch.PtrSize / 8]byte
 var fingwait bool
 var fingwake bool
 var allfin *finblock // list of all blocks
@@ -95,12 +95,12 @@
 			if finptrmask[0] == 0 {
 				// Build pointer mask for Finalizer array in block.
 				// Check assumptions made in finalizer1 array above.
-				if (unsafe.Sizeof(finalizer{}) != 5*sys.PtrSize ||
+				if (unsafe.Sizeof(finalizer{}) != 5*goarch.PtrSize ||
 					unsafe.Offsetof(finalizer{}.fn) != 0 ||
-					unsafe.Offsetof(finalizer{}.arg) != sys.PtrSize ||
-					unsafe.Offsetof(finalizer{}.nret) != 2*sys.PtrSize ||
-					unsafe.Offsetof(finalizer{}.fint) != 3*sys.PtrSize ||
-					unsafe.Offsetof(finalizer{}.ot) != 4*sys.PtrSize) {
+					unsafe.Offsetof(finalizer{}.arg) != goarch.PtrSize ||
+					unsafe.Offsetof(finalizer{}.nret) != 2*goarch.PtrSize ||
+					unsafe.Offsetof(finalizer{}.fint) != 3*goarch.PtrSize ||
+					unsafe.Offsetof(finalizer{}.ot) != 4*goarch.PtrSize) {
 					throw("finalizer out of sync")
 				}
 				for i := range finptrmask {
@@ -432,7 +432,7 @@
 	for _, t := range ft.out() {
 		nret = alignUp(nret, uintptr(t.align)) + uintptr(t.size)
 	}
-	nret = alignUp(nret, sys.PtrSize)
+	nret = alignUp(nret, goarch.PtrSize)
 
 	// make sure we have a finalizer goroutine
 	createfing()
diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index 4585663..34b5b48 100644
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -167,22 +167,17 @@
 	lockInit(&work.wbufSpans.lock, lockRankWbufSpans)
 }
 
-// Temporary in order to enable register ABI work.
-// TODO(register args): convert back to local chan in gcenabled, passed to "go" stmts.
-var gcenable_setup chan int
-
 // gcenable is called after the bulk of the runtime initialization,
 // just before we're about to start letting user code run.
 // It kicks off the background sweeper goroutine, the background
 // scavenger goroutine, and enables GC.
 func gcenable() {
 	// Kick off sweeping and scavenging.
-	gcenable_setup = make(chan int, 2)
-	go bgsweep()
-	go bgscavenge()
-	<-gcenable_setup
-	<-gcenable_setup
-	gcenable_setup = nil
+	c := make(chan int, 2)
+	go bgsweep(c)
+	go bgscavenge(c)
+	<-c
+	<-c
 	memstats.enablegc = true // now that runtime is initialized, GC is okay
 }
 
@@ -1563,19 +1558,17 @@
 	sched.sudogcache = nil
 	unlock(&sched.sudoglock)
 
-	// Clear central defer pools.
+	// Clear central defer pool.
 	// Leave per-P pools alone, they have strictly bounded size.
 	lock(&sched.deferlock)
-	for i := range sched.deferpool {
-		// disconnect cached list before dropping it on the floor,
-		// so that a dangling ref to one entry does not pin all of them.
-		var d, dlink *_defer
-		for d = sched.deferpool[i]; d != nil; d = dlink {
-			dlink = d.link
-			d.link = nil
-		}
-		sched.deferpool[i] = nil
+	// disconnect cached list before dropping it on the floor,
+	// so that a dangling ref to one entry does not pin all of them.
+	var d, dlink *_defer
+	for d = sched.deferpool; d != nil; d = dlink {
+		dlink = d.link
+		d.link = nil
 	}
+	sched.deferpool = nil
 	unlock(&sched.deferlock)
 }
 
diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index 1fd0732..874d910 100644
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -7,8 +7,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -245,7 +245,7 @@
 //
 //go:nowritebarrier
 func markrootBlock(b0, n0 uintptr, ptrmask0 *uint8, gcw *gcWork, shard int) {
-	if rootBlockBytes%(8*sys.PtrSize) != 0 {
+	if rootBlockBytes%(8*goarch.PtrSize) != 0 {
 		// This is necessary to pick byte offsets in ptrmask0.
 		throw("rootBlockBytes must be a multiple of 8*ptrSize")
 	}
@@ -258,7 +258,7 @@
 		return
 	}
 	b := b0 + off
-	ptrmask := (*uint8)(add(unsafe.Pointer(ptrmask0), uintptr(shard)*(rootBlockBytes/(8*sys.PtrSize))))
+	ptrmask := (*uint8)(add(unsafe.Pointer(ptrmask0), uintptr(shard)*(rootBlockBytes/(8*goarch.PtrSize))))
 	n := uintptr(rootBlockBytes)
 	if off+n > n0 {
 		n = n0 - off
@@ -372,7 +372,7 @@
 				scanobject(p, gcw)
 
 				// The special itself is a root.
-				scanblock(uintptr(unsafe.Pointer(&spf.fn)), sys.PtrSize, &oneptrmask[0], gcw, nil)
+				scanblock(uintptr(unsafe.Pointer(&spf.fn)), goarch.PtrSize, &oneptrmask[0], gcw, nil)
 			}
 			unlock(&s.speciallock)
 		}
@@ -737,7 +737,7 @@
 	// register that gets moved back and forth between the
 	// register and sched.ctxt without a write barrier.
 	if gp.sched.ctxt != nil {
-		scanblock(uintptr(unsafe.Pointer(&gp.sched.ctxt)), sys.PtrSize, &oneptrmask[0], gcw, &state)
+		scanblock(uintptr(unsafe.Pointer(&gp.sched.ctxt)), goarch.PtrSize, &oneptrmask[0], gcw, &state)
 	}
 
 	// Scan the stack. Accumulate a list of stack objects.
@@ -750,26 +750,23 @@
 	// Find additional pointers that point into the stack from the heap.
 	// Currently this includes defers and panics. See also function copystack.
 
-	// Find and trace all defer arguments.
-	tracebackdefers(gp, scanframe, nil)
-
 	// Find and trace other pointers in defer records.
 	for d := gp._defer; d != nil; d = d.link {
 		if d.fn != nil {
-			// tracebackdefers above does not scan the func value, which could
-			// be a stack allocated closure. See issue 30453.
-			scanblock(uintptr(unsafe.Pointer(&d.fn)), sys.PtrSize, &oneptrmask[0], gcw, &state)
+			// Scan the func value, which could be a stack allocated closure.
+			// See issue 30453.
+			scanblock(uintptr(unsafe.Pointer(&d.fn)), goarch.PtrSize, &oneptrmask[0], gcw, &state)
 		}
 		if d.link != nil {
 			// The link field of a stack-allocated defer record might point
 			// to a heap-allocated defer record. Keep that heap record live.
-			scanblock(uintptr(unsafe.Pointer(&d.link)), sys.PtrSize, &oneptrmask[0], gcw, &state)
+			scanblock(uintptr(unsafe.Pointer(&d.link)), goarch.PtrSize, &oneptrmask[0], gcw, &state)
 		}
 		// Retain defers records themselves.
 		// Defer records might not be reachable from the G through regular heap
 		// tracing because the defer linked list might weave between the stack and the heap.
 		if d.heap {
-			scanblock(uintptr(unsafe.Pointer(&d)), sys.PtrSize, &oneptrmask[0], gcw, &state)
+			scanblock(uintptr(unsafe.Pointer(&d)), goarch.PtrSize, &oneptrmask[0], gcw, &state)
 		}
 	}
 	if gp._panic != nil {
@@ -913,13 +910,13 @@
 
 	// Scan local variables if stack frame has been allocated.
 	if locals.n > 0 {
-		size := uintptr(locals.n) * sys.PtrSize
+		size := uintptr(locals.n) * goarch.PtrSize
 		scanblock(frame.varp-size, size, locals.bytedata, gcw, state)
 	}
 
 	// Scan arguments.
 	if args.n > 0 {
-		scanblock(frame.argp, uintptr(args.n)*sys.PtrSize, args.bytedata, gcw, state)
+		scanblock(frame.argp, uintptr(args.n)*goarch.PtrSize, args.bytedata, gcw, state)
 	}
 
 	// Add all stack objects to the stack object list.
@@ -1172,9 +1169,9 @@
 
 	for i := uintptr(0); i < n; {
 		// Find bits for the next word.
-		bits := uint32(*addb(ptrmask, i/(sys.PtrSize*8)))
+		bits := uint32(*addb(ptrmask, i/(goarch.PtrSize*8)))
 		if bits == 0 {
-			i += sys.PtrSize * 8
+			i += goarch.PtrSize * 8
 			continue
 		}
 		for j := 0; j < 8 && i < n; j++ {
@@ -1190,7 +1187,7 @@
 				}
 			}
 			bits >>= 1
-			i += sys.PtrSize
+			i += goarch.PtrSize
 		}
 	}
 }
@@ -1251,7 +1248,7 @@
 	}
 
 	var i uintptr
-	for i = 0; i < n; i, hbits = i+sys.PtrSize, hbits.next() {
+	for i = 0; i < n; i, hbits = i+goarch.PtrSize, hbits.next() {
 		// Load bits once. See CL 22712 and issue 16973 for discussion.
 		bits := hbits.bits()
 		if bits&bitScan == 0 {
@@ -1300,7 +1297,7 @@
 		print("conservatively scanning [", hex(b), ",", hex(b+n), ")\n")
 		hexdumpWords(b, b+n, func(p uintptr) byte {
 			if ptrmask != nil {
-				word := (p - b) / sys.PtrSize
+				word := (p - b) / goarch.PtrSize
 				bits := *addb(ptrmask, word/8)
 				if (bits>>(word%8))&1 == 0 {
 					return '$'
@@ -1325,9 +1322,9 @@
 		printunlock()
 	}
 
-	for i := uintptr(0); i < n; i += sys.PtrSize {
+	for i := uintptr(0); i < n; i += goarch.PtrSize {
 		if ptrmask != nil {
-			word := i / sys.PtrSize
+			word := i / goarch.PtrSize
 			bits := *addb(ptrmask, word/8)
 			if bits == 0 {
 				// Skip 8 words (the loop increment will do the 8th)
@@ -1336,10 +1333,10 @@
 				// seen this word of ptrmask, so i
 				// must be 8-word-aligned, but check
 				// our reasoning just in case.
-				if i%(sys.PtrSize*8) != 0 {
+				if i%(goarch.PtrSize*8) != 0 {
 					throw("misaligned mask")
 				}
-				i += sys.PtrSize*8 - sys.PtrSize
+				i += goarch.PtrSize*8 - goarch.PtrSize
 				continue
 			}
 			if (bits>>(word%8))&1 == 0 {
@@ -1401,7 +1398,7 @@
 //go:nowritebarrierrec
 func greyobject(obj, base, off uintptr, span *mspan, gcw *gcWork, objIndex uintptr) {
 	// obj should be start of allocation, and so must be at least pointer-aligned.
-	if obj&(sys.PtrSize-1) != 0 {
+	if obj&(goarch.PtrSize-1) != 0 {
 		throw("greyobject: obj not pointer-aligned")
 	}
 	mbits := span.markBitsForIndex(objIndex)
@@ -1473,13 +1470,13 @@
 		// We're printing something from a stack frame. We
 		// don't know how big it is, so just show up to an
 		// including off.
-		size = off + sys.PtrSize
+		size = off + goarch.PtrSize
 	}
-	for i := uintptr(0); i < size; i += sys.PtrSize {
+	for i := uintptr(0); i < size; i += goarch.PtrSize {
 		// For big objects, just print the beginning (because
 		// that usually hints at the object's type) and the
 		// fields around off.
-		if !(i < 128*sys.PtrSize || off-16*sys.PtrSize < i && i < off+16*sys.PtrSize) {
+		if !(i < 128*goarch.PtrSize || off-16*goarch.PtrSize < i && i < off+16*goarch.PtrSize) {
 			skipped = true
 			continue
 		}
diff --git a/src/runtime/mgcscavenge.go b/src/runtime/mgcscavenge.go
index 7578129..2bb1998 100644
--- a/src/runtime/mgcscavenge.go
+++ b/src/runtime/mgcscavenge.go
@@ -56,6 +56,7 @@
 package runtime
 
 import (
+	"internal/goos"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -90,7 +91,7 @@
 	//
 	// This ratio is used as part of multiplicative factor to help the scavenger account
 	// for the additional costs of using scavenged memory in its pacing.
-	scavengeCostRatio = 0.7 * (sys.GoosDarwin + sys.GoosIos)
+	scavengeCostRatio = 0.7 * (goos.IsDarwin + goos.IsIos)
 
 	// scavengeReservationShards determines the amount of memory the scavenger
 	// should reserve for scavenging at a time. Specifically, the amount of
@@ -249,7 +250,7 @@
 // The background scavenger maintains the RSS of the application below
 // the line described by the proportional scavenging statistics in
 // the mheap struct.
-func bgscavenge() {
+func bgscavenge(c chan int) {
 	scavenge.g = getg()
 
 	lockInit(&scavenge.lock, lockRankScavenge)
@@ -261,7 +262,7 @@
 		wakeScavenger()
 	}
 
-	gcenable_setup <- 1
+	c <- 1
 	goparkunlock(&scavenge.lock, waitReasonGCScavengeWait, traceEvGoBlock, 1)
 
 	// Exponentially-weighted moving average of the fraction of time this
diff --git a/src/runtime/mgcstack.go b/src/runtime/mgcstack.go
index 92d5848..49dc54e 100644
--- a/src/runtime/mgcstack.go
+++ b/src/runtime/mgcstack.go
@@ -95,7 +95,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -107,7 +107,7 @@
 //go:notinheap
 type stackWorkBuf struct {
 	stackWorkBufHdr
-	obj [(_WorkbufSize - unsafe.Sizeof(stackWorkBufHdr{})) / sys.PtrSize]uintptr
+	obj [(_WorkbufSize - unsafe.Sizeof(stackWorkBufHdr{})) / goarch.PtrSize]uintptr
 }
 
 // Header declaration must come after the buf declaration above, because of issue #14620.
diff --git a/src/runtime/mgcsweep.go b/src/runtime/mgcsweep.go
index 8fe3a65..1812644 100644
--- a/src/runtime/mgcsweep.go
+++ b/src/runtime/mgcsweep.go
@@ -153,13 +153,13 @@
 	nextMarkBitArenaEpoch()
 }
 
-func bgsweep() {
+func bgsweep(c chan int) {
 	sweep.g = getg()
 
 	lockInit(&sweep.lock, lockRankSweep)
 	lock(&sweep.lock)
 	sweep.parked = true
-	gcenable_setup <- 1
+	c <- 1
 	goparkunlock(&sweep.lock, waitReasonGCSweepWait, traceEvGoBlock, 1)
 
 	for {
diff --git a/src/runtime/mgcwork.go b/src/runtime/mgcwork.go
index 667c7af..8787d93 100644
--- a/src/runtime/mgcwork.go
+++ b/src/runtime/mgcwork.go
@@ -5,8 +5,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -322,7 +322,7 @@
 type workbuf struct {
 	workbufhdr
 	// account for the above fields
-	obj [(_WorkbufSize - unsafe.Sizeof(workbufhdr{})) / sys.PtrSize]uintptr
+	obj [(_WorkbufSize - unsafe.Sizeof(workbufhdr{})) / goarch.PtrSize]uintptr
 }
 
 // workbuf factory routines. These funcs are used to manage the
diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
index 84c00ce..b78f752 100644
--- a/src/runtime/mheap.go
+++ b/src/runtime/mheap.go
@@ -10,8 +10,8 @@
 
 import (
 	"internal/cpu"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -497,13 +497,13 @@
 	assertLockHeld(&h.lock)
 
 	if len(h.allspans) >= cap(h.allspans) {
-		n := 64 * 1024 / sys.PtrSize
+		n := 64 * 1024 / goarch.PtrSize
 		if n < cap(h.allspans)*3/2 {
 			n = cap(h.allspans) * 3 / 2
 		}
 		var new []*mspan
 		sp := (*slice)(unsafe.Pointer(&new))
-		sp.array = sysAlloc(uintptr(n)*sys.PtrSize, &memstats.other_sys)
+		sp.array = sysAlloc(uintptr(n)*goarch.PtrSize, &memstats.other_sys)
 		if sp.array == nil {
 			throw("runtime: cannot allocate memory")
 		}
@@ -1822,7 +1822,7 @@
 			scanobject(base, gcw)
 			// Mark the finalizer itself, since the
 			// special isn't part of the GC'd heap.
-			scanblock(uintptr(unsafe.Pointer(&s.fn)), sys.PtrSize, &oneptrmask[0], gcw, nil)
+			scanblock(uintptr(unsafe.Pointer(&s.fn)), goarch.PtrSize, &oneptrmask[0], gcw, nil)
 			releasem(mp)
 		}
 		return true
diff --git a/src/runtime/mkduff.go b/src/runtime/mkduff.go
index da191cc..f036745 100644
--- a/src/runtime/mkduff.go
+++ b/src/runtime/mkduff.go
@@ -154,7 +154,7 @@
 	// ZR: always zero
 	// R20: ptr to memory to be zeroed
 	// On return, R20 points to the last zeroed dword.
-	fmt.Fprintln(w, "TEXT runtime·duffzero(SB), NOSPLIT|NOFRAME, $0-0")
+	fmt.Fprintln(w, "TEXT runtime·duffzero<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-0")
 	for i := 0; i < 63; i++ {
 		fmt.Fprintln(w, "\tSTP.P\t(ZR, ZR), 16(R20)")
 	}
@@ -167,7 +167,7 @@
 	// R21: ptr to destination memory
 	// R26, R27 (aka REGTMP): scratch space
 	// R20 and R21 are updated as a side effect
-	fmt.Fprintln(w, "TEXT runtime·duffcopy(SB), NOSPLIT|NOFRAME, $0-0")
+	fmt.Fprintln(w, "TEXT runtime·duffcopy<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-0")
 
 	for i := 0; i < 64; i++ {
 		fmt.Fprintln(w, "\tLDP.P\t16(R20), (R26, R27)")
diff --git a/src/runtime/mkpreempt.go b/src/runtime/mkpreempt.go
index 6c98054..f2b9030 100644
--- a/src/runtime/mkpreempt.go
+++ b/src/runtime/mkpreempt.go
@@ -128,8 +128,7 @@
 	}
 	fmt.Fprintf(out, "#include \"go_asm.h\"\n")
 	fmt.Fprintf(out, "#include \"textflag.h\"\n\n")
-	fmt.Fprintf(out, "// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.\n")
-	fmt.Fprintf(out, "TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0\n")
+	fmt.Fprintf(out, "TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0\n")
 }
 
 func p(f string, args ...interface{}) {
diff --git a/src/runtime/mprof.go b/src/runtime/mprof.go
index 5235b89..0ba415b 100644
--- a/src/runtime/mprof.go
+++ b/src/runtime/mprof.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -621,7 +622,7 @@
 	r.AllocObjects = int64(mp.active.allocs)
 	r.FreeObjects = int64(mp.active.frees)
 	if raceenabled {
-		racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), funcPC(MemProfile))
+		racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), abi.FuncPCABIInternal(MemProfile))
 	}
 	if msanenabled {
 		msanwrite(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0))
@@ -674,7 +675,7 @@
 			}
 			r.Cycles = bp.cycles
 			if raceenabled {
-				racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), funcPC(BlockProfile))
+				racewriterangepc(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0), getcallerpc(), abi.FuncPCABIInternal(BlockProfile))
 			}
 			if msanenabled {
 				msanwrite(unsafe.Pointer(&r.Stack0[0]), unsafe.Sizeof(r.Stack0))
diff --git a/src/runtime/mranges.go b/src/runtime/mranges.go
index 84a2c06..e0be1e1 100644
--- a/src/runtime/mranges.go
+++ b/src/runtime/mranges.go
@@ -10,7 +10,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -167,7 +167,7 @@
 	ranges := (*notInHeapSlice)(unsafe.Pointer(&a.ranges))
 	ranges.len = 0
 	ranges.cap = 16
-	ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), sys.PtrSize, sysStat))
+	ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), goarch.PtrSize, sysStat))
 	a.sysStat = sysStat
 	a.totalBytes = 0
 }
@@ -294,7 +294,7 @@
 			ranges := (*notInHeapSlice)(unsafe.Pointer(&a.ranges))
 			ranges.len = len(oldRanges) + 1
 			ranges.cap = cap(oldRanges) * 2
-			ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), sys.PtrSize, a.sysStat))
+			ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), goarch.PtrSize, a.sysStat))
 
 			// Copy in the old array, but make space for the new range.
 			copy(a.ranges[:i], oldRanges[:i])
@@ -364,7 +364,7 @@
 		ranges := (*notInHeapSlice)(unsafe.Pointer(&b.ranges))
 		ranges.len = 0
 		ranges.cap = cap(a.ranges)
-		ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), sys.PtrSize, b.sysStat))
+		ranges.array = (*notInHeap)(persistentalloc(unsafe.Sizeof(addrRange{})*uintptr(ranges.cap), goarch.PtrSize, b.sysStat))
 	}
 	b.ranges = b.ranges[:len(a.ranges)]
 	b.totalBytes = a.totalBytes
diff --git a/src/runtime/mspanset.go b/src/runtime/mspanset.go
index 10d2596..29f1491 100644
--- a/src/runtime/mspanset.go
+++ b/src/runtime/mspanset.go
@@ -6,8 +6,8 @@
 
 import (
 	"internal/cpu"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -82,7 +82,7 @@
 retry:
 	if top < spineLen {
 		spine := atomic.Loadp(unsafe.Pointer(&b.spine))
-		blockp := add(spine, sys.PtrSize*top)
+		blockp := add(spine, goarch.PtrSize*top)
 		block = (*spanSetBlock)(atomic.Loadp(blockp))
 	} else {
 		// Add a new block to the spine, potentially growing
@@ -102,11 +102,11 @@
 			if newCap == 0 {
 				newCap = spanSetInitSpineCap
 			}
-			newSpine := persistentalloc(newCap*sys.PtrSize, cpu.CacheLineSize, &memstats.gcMiscSys)
+			newSpine := persistentalloc(newCap*goarch.PtrSize, cpu.CacheLineSize, &memstats.gcMiscSys)
 			if b.spineCap != 0 {
 				// Blocks are allocated off-heap, so
 				// no write barriers.
-				memmove(newSpine, b.spine, b.spineCap*sys.PtrSize)
+				memmove(newSpine, b.spine, b.spineCap*goarch.PtrSize)
 			}
 			// Spine is allocated off-heap, so no write barrier.
 			atomic.StorepNoWB(unsafe.Pointer(&b.spine), newSpine)
@@ -124,7 +124,7 @@
 		block = spanSetBlockPool.alloc()
 
 		// Add it to the spine.
-		blockp := add(b.spine, sys.PtrSize*top)
+		blockp := add(b.spine, goarch.PtrSize*top)
 		// Blocks are allocated off-heap, so no write barrier.
 		atomic.StorepNoWB(blockp, unsafe.Pointer(block))
 		atomic.Storeuintptr(&b.spineLen, spineLen+1)
@@ -181,7 +181,7 @@
 	// grows monotonically and we've already verified it, we'll definitely
 	// be reading from a valid block.
 	spine := atomic.Loadp(unsafe.Pointer(&b.spine))
-	blockp := add(spine, sys.PtrSize*uintptr(top))
+	blockp := add(spine, goarch.PtrSize*uintptr(top))
 
 	// Given that the spine length is correct, we know we will never
 	// see a nil block here, since the length is always updated after
@@ -241,7 +241,7 @@
 		// since it may be pushed into again. In order to avoid leaking
 		// memory since we're going to reset the head and tail, clean
 		// up such a block now, if it exists.
-		blockp := (**spanSetBlock)(add(b.spine, sys.PtrSize*uintptr(top)))
+		blockp := (**spanSetBlock)(add(b.spine, goarch.PtrSize*uintptr(top)))
 		block := *blockp
 		if block != nil {
 			// Sanity check the popped value.
diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go
index eeb2a7b..341ba9a 100644
--- a/src/runtime/mstats.go
+++ b/src/runtime/mstats.go
@@ -7,8 +7,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -713,7 +713,7 @@
 
 	// Add a uint32 to ensure this struct is a multiple of 8 bytes in size.
 	// Only necessary on 32-bit platforms.
-	_ [(sys.PtrSize / 4) % 2]uint32
+	_ [(goarch.PtrSize / 4) % 2]uint32
 }
 
 // merge adds in the deltas from b into a.
diff --git a/src/runtime/mwbbuf.go b/src/runtime/mwbbuf.go
index 6efc000..78d9382 100644
--- a/src/runtime/mwbbuf.go
+++ b/src/runtime/mwbbuf.go
@@ -23,8 +23,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -145,7 +145,7 @@
 	p := (*[2]uintptr)(unsafe.Pointer(b.next))
 	p[0] = old
 	p[1] = new
-	b.next += 2 * sys.PtrSize
+	b.next += 2 * goarch.PtrSize
 	return b.next != b.end
 }
 
diff --git a/src/runtime/norace_linux_test.go b/src/runtime/norace_linux_test.go
index 94b7c7a..b199aa6 100644
--- a/src/runtime/norace_linux_test.go
+++ b/src/runtime/norace_linux_test.go
@@ -9,6 +9,7 @@
 package runtime_test
 
 import (
+	"internal/abi"
 	"runtime"
 	"testing"
 	"time"
@@ -25,7 +26,7 @@
 // Can't be run with -race because it inserts calls into newOSProcCreated()
 // that require a valid G/M.
 func TestNewOSProc0(t *testing.T) {
-	runtime.NewOSProc0(0x800000, unsafe.Pointer(runtime.FuncPC(newOSProcCreated)))
+	runtime.NewOSProc0(0x800000, unsafe.Pointer(abi.FuncPCABIInternal(newOSProcCreated)))
 	check := time.NewTicker(100 * time.Millisecond)
 	defer check.Stop()
 	end := time.After(5 * time.Second)
diff --git a/src/runtime/os3_plan9.go b/src/runtime/os3_plan9.go
index c5dc23d..a06d74e 100644
--- a/src/runtime/os3_plan9.go
+++ b/src/runtime/os3_plan9.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -92,15 +93,15 @@
 			if usesLR {
 				c.setlr(pc)
 			} else {
-				sp -= sys.PtrSize
+				sp -= goarch.PtrSize
 				*(*uintptr)(unsafe.Pointer(sp)) = pc
 				c.setsp(sp)
 			}
 		}
 		if usesLR {
-			c.setpc(funcPC(sigpanictramp))
+			c.setpc(abi.FuncPCABI0(sigpanictramp))
 		} else {
-			c.setpc(funcPC(sigpanic0))
+			c.setpc(abi.FuncPCABI0(sigpanic0))
 		}
 		return _NCONT
 	}
diff --git a/src/runtime/os3_solaris.go b/src/runtime/os3_solaris.go
index 39ef831..84194a3 100644
--- a/src/runtime/os3_solaris.go
+++ b/src/runtime/os3_solaris.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -172,7 +173,7 @@
 	// Disable signals during create, so that the new thread starts
 	// with signals disabled. It will enable them in minit.
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	ret = pthread_create(&tid, &attr, funcPC(tstart_sysvicall), unsafe.Pointer(mp))
+	ret = pthread_create(&tid, &attr, abi.FuncPCABI0(tstart_sysvicall), unsafe.Pointer(mp))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 	if ret != 0 {
 		print("runtime: failed to create new OS thread (have ", mcount(), " already; errno=", ret, ")\n")
@@ -215,7 +216,7 @@
 // Called to initialize a new m (including the bootstrap m).
 // Called on the new thread, cannot allocate memory.
 func minit() {
-	asmcgocall(unsafe.Pointer(funcPC(miniterrno)), unsafe.Pointer(&libc____errno))
+	asmcgocall(unsafe.Pointer(abi.FuncPCABI0(miniterrno)), unsafe.Pointer(&libc____errno))
 
 	minitSignals()
 
@@ -241,8 +242,8 @@
 
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	*((*uintptr)(unsafe.Pointer(&sa._funcptr))) = fn
 	sigaction(i, &sa, nil)
@@ -390,6 +391,7 @@
 }
 
 //go:nosplit
+//go:cgo_unsafe_args
 func doMmap(addr, n, prot, flags, fd, off uintptr) (uintptr, uintptr) {
 	var libcall libcall
 	libcall.fn = uintptr(unsafe.Pointer(&libc_mmap))
@@ -598,7 +600,7 @@
 	n++
 
 	// now argv+n is auxv
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	sysauxv(auxv[:])
 }
 
diff --git a/src/runtime/os_aix.go b/src/runtime/os_aix.go
index 4fb1c8e..478dde2 100644
--- a/src/runtime/os_aix.go
+++ b/src/runtime/os_aix.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"unsafe"
 )
 
@@ -267,7 +268,7 @@
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
 		fn = uintptr(unsafe.Pointer(&sigtramp))
 	}
 	sa.sa_handler = fn
diff --git a/src/runtime/os_darwin.go b/src/runtime/os_darwin.go
index 079be10..ca61f20 100644
--- a/src/runtime/os_darwin.go
+++ b/src/runtime/os_darwin.go
@@ -369,7 +369,7 @@
 	var sa usigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = ^uint32(0)
-	if fn == funcPC(sighandler) { // funcPC(sighandler) matches the callers in signal_unix.go
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
 		if iscgo {
 			fn = abi.FuncPCABI0(cgoSigtramp)
 		} else {
diff --git a/src/runtime/os_dragonfly.go b/src/runtime/os_dragonfly.go
index 5c688a3..191a560 100644
--- a/src/runtime/os_dragonfly.go
+++ b/src/runtime/os_dragonfly.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -147,14 +148,14 @@
 func newosproc(mp *m) {
 	stk := unsafe.Pointer(mp.g0.stack.hi)
 	if false {
-		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " lwp_start=", funcPC(lwp_start), " id=", mp.id, " ostk=", &mp, "\n")
+		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " lwp_start=", abi.FuncPCABI0(lwp_start), " id=", mp.id, " ostk=", &mp, "\n")
 	}
 
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
 
 	params := lwpparams{
-		start_func: funcPC(lwp_start),
+		start_func: abi.FuncPCABI0(lwp_start),
 		arg:        unsafe.Pointer(mp),
 		stack:      uintptr(stk),
 		tid1:       nil, // minit will record tid
@@ -226,8 +227,8 @@
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	sa.sa_sigaction = fn
 	sigaction(i, &sa, nil)
@@ -278,7 +279,7 @@
 	// skip NULL separator
 	n++
 
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	sysauxv(auxv[:])
 }
 
diff --git a/src/runtime/os_freebsd.go b/src/runtime/os_freebsd.go
index 09dd50c..5a8121a 100644
--- a/src/runtime/os_freebsd.go
+++ b/src/runtime/os_freebsd.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -116,8 +117,8 @@
 	}
 
 	maskSize := int(maxcpus+7) / 8
-	if maskSize < sys.PtrSize {
-		maskSize = sys.PtrSize
+	if maskSize < goarch.PtrSize {
+		maskSize = goarch.PtrSize
 	}
 	if maskSize > len(mask) {
 		maskSize = len(mask)
@@ -197,11 +198,11 @@
 func newosproc(mp *m) {
 	stk := unsafe.Pointer(mp.g0.stack.hi)
 	if false {
-		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " thr_start=", funcPC(thr_start), " id=", mp.id, " ostk=", &mp, "\n")
+		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " thr_start=", abi.FuncPCABI0(thr_start), " id=", mp.id, " ostk=", &mp, "\n")
 	}
 
 	param := thrparam{
-		start_func: funcPC(thr_start),
+		start_func: abi.FuncPCABI0(thr_start),
 		arg:        unsafe.Pointer(mp),
 		stack_base: mp.g0.stack.lo,
 		stack_size: uintptr(stk) - mp.g0.stack.lo,
@@ -236,7 +237,7 @@
 	// However, newosproc0 is currently unreachable because builds
 	// utilizing c-shared/c-archive force external linking.
 	param := thrparam{
-		start_func: funcPC(fn),
+		start_func: uintptr(fn),
 		arg:        nil,
 		stack_base: uintptr(stack), //+stacksize?
 		stack_size: stacksize,
@@ -391,7 +392,7 @@
 	n++
 
 	// now argv+n is auxv
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	sysauxv(auxv[:])
 }
 
diff --git a/src/runtime/os_freebsd2.go b/src/runtime/os_freebsd2.go
index fde6fbf..7e266dc 100644
--- a/src/runtime/os_freebsd2.go
+++ b/src/runtime/os_freebsd2.go
@@ -7,14 +7,16 @@
 
 package runtime
 
+import "internal/abi"
+
 //go:nosplit
 //go:nowritebarrierrec
 func setsig(i uint32, fn uintptr) {
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	sa.sa_handler = fn
 	sigaction(i, &sa, nil)
diff --git a/src/runtime/os_freebsd_amd64.go b/src/runtime/os_freebsd_amd64.go
index dc0bb9f..b179383 100644
--- a/src/runtime/os_freebsd_amd64.go
+++ b/src/runtime/os_freebsd_amd64.go
@@ -4,6 +4,8 @@
 
 package runtime
 
+import "internal/abi"
+
 func cgoSigtramp()
 
 //go:nosplit
@@ -12,11 +14,11 @@
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
 		if iscgo {
-			fn = funcPC(cgoSigtramp)
+			fn = abi.FuncPCABI0(cgoSigtramp)
 		} else {
-			fn = funcPC(sigtramp)
+			fn = abi.FuncPCABI0(sigtramp)
 		}
 	}
 	sa.sa_handler = fn
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
index c8b29e3..88c16f7 100644
--- a/src/runtime/os_linux.go
+++ b/src/runtime/os_linux.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -142,14 +143,14 @@
 	 * note: strace gets confused if we use CLONE_PTRACE here.
 	 */
 	if false {
-		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " clone=", funcPC(clone), " id=", mp.id, " ostk=", &mp, "\n")
+		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " clone=", abi.FuncPCABI0(clone), " id=", mp.id, " ostk=", &mp, "\n")
 	}
 
 	// Disable signals during clone, so that the new thread starts
 	// with signals disabled. It will enable them in minit.
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	ret := clone(cloneFlags, stk, unsafe.Pointer(mp), unsafe.Pointer(mp.g0), unsafe.Pointer(funcPC(mstart)))
+	ret := clone(cloneFlags, stk, unsafe.Pointer(mp), unsafe.Pointer(mp.g0), unsafe.Pointer(abi.FuncPCABI0(mstart)))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 
 	if ret < 0 {
@@ -205,7 +206,7 @@
 	n++
 
 	// now argv+n is auxv
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	if sysauxv(auxv[:]) != 0 {
 		return
 	}
@@ -429,13 +430,13 @@
 	// should not be used". x86_64 kernel requires it. Only use it on
 	// x86.
 	if GOARCH == "386" || GOARCH == "amd64" {
-		sa.sa_restorer = funcPC(sigreturn)
+		sa.sa_restorer = abi.FuncPCABI0(sigreturn)
 	}
-	if fn == funcPC(sighandler) {
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
 		if iscgo {
-			fn = funcPC(cgoSigtramp)
+			fn = abi.FuncPCABI0(cgoSigtramp)
 		} else {
-			fn = funcPC(sigtramp)
+			fn = abi.FuncPCABI0(sigtramp)
 		}
 	}
 	sa.sa_handler = fn
diff --git a/src/runtime/os_netbsd.go b/src/runtime/os_netbsd.go
index 6fbb3aa..2c20ee2 100644
--- a/src/runtime/os_netbsd.go
+++ b/src/runtime/os_netbsd.go
@@ -5,8 +5,9 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -215,7 +216,7 @@
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
 
-	lwp_mcontext_init(&uc.uc_mcontext, stk, mp, mp.g0, funcPC(netbsdMstart))
+	lwp_mcontext_init(&uc.uc_mcontext, stk, mp, mp.g0, abi.FuncPCABI0(netbsdMstart))
 
 	ret := lwp_create(unsafe.Pointer(&uc), _LWP_DETACHED, unsafe.Pointer(&mp.procid))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
@@ -318,8 +319,8 @@
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = sigset_all
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	sa.sa_sigaction = fn
 	sigaction(i, &sa, nil)
@@ -371,7 +372,7 @@
 	n++
 
 	// now argv+n is auxv
-	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
+	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
 	sysauxv(auxv[:])
 }
 
diff --git a/src/runtime/os_netbsd_386.go b/src/runtime/os_netbsd_386.go
index 037f7e3..ac89b98 100644
--- a/src/runtime/os_netbsd_386.go
+++ b/src/runtime/os_netbsd_386.go
@@ -4,11 +4,14 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
 	// Machine dependent mcontext initialisation for LWP.
-	mc.__gregs[_REG_EIP] = uint32(funcPC(lwp_tramp))
+	mc.__gregs[_REG_EIP] = uint32(abi.FuncPCABI0(lwp_tramp))
 	mc.__gregs[_REG_UESP] = uint32(uintptr(stk))
 	mc.__gregs[_REG_EBX] = uint32(uintptr(unsafe.Pointer(mp)))
 	mc.__gregs[_REG_EDX] = uint32(uintptr(unsafe.Pointer(gp)))
diff --git a/src/runtime/os_netbsd_amd64.go b/src/runtime/os_netbsd_amd64.go
index 5118b0c..74eea0c 100644
--- a/src/runtime/os_netbsd_amd64.go
+++ b/src/runtime/os_netbsd_amd64.go
@@ -4,11 +4,14 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
 	// Machine dependent mcontext initialisation for LWP.
-	mc.__gregs[_REG_RIP] = uint64(funcPC(lwp_tramp))
+	mc.__gregs[_REG_RIP] = uint64(abi.FuncPCABI0(lwp_tramp))
 	mc.__gregs[_REG_RSP] = uint64(uintptr(stk))
 	mc.__gregs[_REG_R8] = uint64(uintptr(unsafe.Pointer(mp)))
 	mc.__gregs[_REG_R9] = uint64(uintptr(unsafe.Pointer(gp)))
diff --git a/src/runtime/os_netbsd_arm.go b/src/runtime/os_netbsd_arm.go
index b5ec23e..5fb4e08 100644
--- a/src/runtime/os_netbsd_arm.go
+++ b/src/runtime/os_netbsd_arm.go
@@ -4,11 +4,14 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
 	// Machine dependent mcontext initialisation for LWP.
-	mc.__gregs[_REG_R15] = uint32(funcPC(lwp_tramp))
+	mc.__gregs[_REG_R15] = uint32(abi.FuncPCABI0(lwp_tramp))
 	mc.__gregs[_REG_R13] = uint32(uintptr(stk))
 	mc.__gregs[_REG_R0] = uint32(uintptr(unsafe.Pointer(mp)))
 	mc.__gregs[_REG_R1] = uint32(uintptr(unsafe.Pointer(gp)))
diff --git a/src/runtime/os_netbsd_arm64.go b/src/runtime/os_netbsd_arm64.go
index 8d21b0a..2dda9c9 100644
--- a/src/runtime/os_netbsd_arm64.go
+++ b/src/runtime/os_netbsd_arm64.go
@@ -4,11 +4,14 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
 	// Machine dependent mcontext initialisation for LWP.
-	mc.__gregs[_REG_ELR] = uint64(funcPC(lwp_tramp))
+	mc.__gregs[_REG_ELR] = uint64(abi.FuncPCABI0(lwp_tramp))
 	mc.__gregs[_REG_X31] = uint64(uintptr(stk))
 	mc.__gregs[_REG_X0] = uint64(uintptr(unsafe.Pointer(mp)))
 	mc.__gregs[_REG_X1] = uint64(uintptr(unsafe.Pointer(mp.g0)))
diff --git a/src/runtime/os_openbsd.go b/src/runtime/os_openbsd.go
index 6259b96..54f36c6 100644
--- a/src/runtime/os_openbsd.go
+++ b/src/runtime/os_openbsd.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -191,8 +192,8 @@
 	var sa sigactiont
 	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
 	sa.sa_mask = uint32(sigset_all)
-	if fn == funcPC(sighandler) {
-		fn = funcPC(sigtramp)
+	if fn == abi.FuncPCABIInternal(sighandler) { // abi.FuncPCABIInternal(sighandler) matches the callers in signal_unix.go
+		fn = abi.FuncPCABI0(sigtramp)
 	}
 	sa.sa_sigaction = fn
 	sigaction(i, &sa, nil)
diff --git a/src/runtime/os_openbsd_libc.go b/src/runtime/os_openbsd_libc.go
index 0a342e5..981e498 100644
--- a/src/runtime/os_openbsd_libc.go
+++ b/src/runtime/os_openbsd_libc.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"unsafe"
 )
 
@@ -48,7 +49,7 @@
 	// setup and then calls mstart.
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	err := pthread_create(&attr, funcPC(mstart_stub), unsafe.Pointer(mp))
+	err := pthread_create(&attr, abi.FuncPCABI0(mstart_stub), unsafe.Pointer(mp))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 	if err != 0 {
 		write(2, unsafe.Pointer(&failThreadCreate[0]), int32(len(failThreadCreate)))
diff --git a/src/runtime/os_openbsd_syscall.go b/src/runtime/os_openbsd_syscall.go
index 3cdcb6c..1ddee18 100644
--- a/src/runtime/os_openbsd_syscall.go
+++ b/src/runtime/os_openbsd_syscall.go
@@ -8,7 +8,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -28,12 +29,12 @@
 	param := tforkt{
 		tf_tcb:   unsafe.Pointer(&mp.tls[0]),
 		tf_tid:   nil, // minit will record tid
-		tf_stack: uintptr(stk) - sys.PtrSize,
+		tf_stack: uintptr(stk) - goarch.PtrSize,
 	}
 
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	ret := tfork(&param, unsafe.Sizeof(param), mp, mp.g0, funcPC(mstart))
+	ret := tfork(&param, unsafe.Sizeof(param), mp, mp.g0, abi.FuncPCABI0(mstart))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 
 	if ret < 0 {
diff --git a/src/runtime/os_plan9.go b/src/runtime/os_plan9.go
index 4d42834..975d460 100644
--- a/src/runtime/os_plan9.go
+++ b/src/runtime/os_plan9.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -346,7 +347,7 @@
 
 func initsig(preinit bool) {
 	if !preinit {
-		notify(unsafe.Pointer(funcPC(sigtramp)))
+		notify(unsafe.Pointer(abi.FuncPCABI0(sigtramp)))
 	}
 }
 
diff --git a/src/runtime/os_solaris.go b/src/runtime/os_solaris.go
index 89129e5..8ac1b08 100644
--- a/src/runtime/os_solaris.go
+++ b/src/runtime/os_solaris.go
@@ -179,6 +179,7 @@
 }
 
 //go:nosplit
+//go:cgo_unsafe_args
 func sysvicall4(fn *libcFunc, a1, a2, a3, a4 uintptr) uintptr {
 	// Leave caller's PC/SP around for traceback.
 	gp := getg()
@@ -208,6 +209,7 @@
 }
 
 //go:nosplit
+//go:cgo_unsafe_args
 func sysvicall5(fn *libcFunc, a1, a2, a3, a4, a5 uintptr) uintptr {
 	// Leave caller's PC/SP around for traceback.
 	gp := getg()
@@ -237,6 +239,7 @@
 }
 
 //go:nosplit
+//go:cgo_unsafe_args
 func sysvicall6(fn *libcFunc, a1, a2, a3, a4, a5, a6 uintptr) uintptr {
 	// Leave caller's PC/SP around for traceback.
 	gp := getg()
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index f093526..648239f 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -5,8 +5,9 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -543,7 +544,7 @@
 }
 
 func osinit() {
-	asmstdcallAddr = unsafe.Pointer(funcPC(asmstdcall))
+	asmstdcallAddr = unsafe.Pointer(abi.FuncPCABI0(asmstdcall))
 
 	setBadSignalMsg()
 
@@ -906,7 +907,7 @@
 func newosproc(mp *m) {
 	// We pass 0 for the stack size to use the default for this binary.
 	thandle := stdcall6(_CreateThread, 0, 0,
-		funcPC(tstart_stdcall), uintptr(unsafe.Pointer(mp)),
+		abi.FuncPCABI0(tstart_stdcall), uintptr(unsafe.Pointer(mp)),
 		0, 0)
 
 	if thandle == 0 {
@@ -1385,14 +1386,14 @@
 	if gp != nil && wantAsyncPreempt(gp) {
 		if ok, newpc := isAsyncSafePoint(gp, c.ip(), c.sp(), c.lr()); ok {
 			// Inject call to asyncPreempt
-			targetPC := funcPC(asyncPreempt)
+			targetPC := abi.FuncPCABI0(asyncPreempt)
 			switch GOARCH {
 			default:
 				throw("unsupported architecture")
 			case "386", "amd64":
 				// Make it look like the thread called targetPC.
 				sp := c.sp()
-				sp -= sys.PtrSize
+				sp -= goarch.PtrSize
 				*(*uintptr)(unsafe.Pointer(sp)) = newpc
 				c.set_sp(sp)
 				c.set_ip(targetPC)
diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index f6c38aa..e4bdceb3 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -5,8 +5,7 @@
 package runtime
 
 import (
-	"internal/abi"
-	"internal/goexperiment"
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -31,7 +30,7 @@
 // pc should be the program counter of the compiler-generated code that
 // triggered this panic.
 func panicCheck1(pc uintptr, msg string) {
-	if sys.GoarchWasm == 0 && hasPrefix(funcname(findfunc(pc)), "runtime.") {
+	if goarch.IsWasm == 0 && hasPrefix(funcname(findfunc(pc)), "runtime.") {
 		// Note: wasm can't tail call, so we can't get the original caller's pc.
 		throw(msg)
 	}
@@ -226,47 +225,27 @@
 	panic(errorAddressString{msg: "invalid memory address or nil pointer dereference", addr: addr})
 }
 
-// Create a new deferred function fn with siz bytes of arguments.
+// Create a new deferred function fn, which has no arguments and results.
 // The compiler turns a defer statement into a call to this.
-//go:nosplit
-func deferproc(siz int32, fn *funcval) { // arguments of fn follow fn
+func deferproc(fn func()) {
 	gp := getg()
 	if gp.m.curg != gp {
 		// go code on the system stack can't defer
 		throw("defer on system stack")
 	}
 
-	if goexperiment.RegabiDefer && siz != 0 {
-		// TODO: Make deferproc just take a func().
-		throw("defer with non-empty frame")
-	}
-
-	// the arguments of fn are in a perilous state. The stack map
-	// for deferproc does not describe them. So we can't let garbage
-	// collection or stack copying trigger until we've copied them out
-	// to somewhere safe. The memmove below does that.
-	// Until the copy completes, we can only call nosplit routines.
-	sp := getcallersp()
-	argp := uintptr(unsafe.Pointer(&fn)) + unsafe.Sizeof(fn)
-	callerpc := getcallerpc()
-
-	d := newdefer(siz)
+	d := newdefer()
 	if d._panic != nil {
 		throw("deferproc: d.panic != nil after newdefer")
 	}
 	d.link = gp._defer
 	gp._defer = d
 	d.fn = fn
-	d.pc = callerpc
-	d.sp = sp
-	switch siz {
-	case 0:
-		// Do nothing.
-	case sys.PtrSize:
-		*(*uintptr)(deferArgs(d)) = *(*uintptr)(unsafe.Pointer(argp))
-	default:
-		memmove(deferArgs(d), unsafe.Pointer(argp), uintptr(siz))
-	}
+	d.pc = getcallerpc()
+	// We must not be preempted between calling getcallersp and
+	// storing it to d.sp because getcallersp's result is a
+	// uintptr stack pointer.
+	d.sp = getcallersp()
 
 	// deferproc returns 0 normally.
 	// a deferred func that stops a panic
@@ -280,12 +259,10 @@
 }
 
 // deferprocStack queues a new deferred function with a defer record on the stack.
-// The defer record must have its siz and fn fields initialized.
+// The defer record must have its fn field initialized.
 // All other fields can contain junk.
-// The defer record must be immediately followed in memory by
-// the arguments of the defer.
-// Nosplit because the arguments on the stack won't be scanned
-// until the defer record is spliced into the gp._defer list.
+// Nosplit because of the uninitialized pointer fields on the stack.
+//
 //go:nosplit
 func deferprocStack(d *_defer) {
 	gp := getg()
@@ -293,10 +270,7 @@
 		// go code on the system stack can't defer
 		throw("defer on system stack")
 	}
-	if goexperiment.RegabiDefer && d.siz != 0 {
-		throw("defer with non-empty frame")
-	}
-	// siz and fn are already set.
+	// fn is already set.
 	// The other fields are junk on entry to deferprocStack and
 	// are initialized here.
 	d.started = false
@@ -327,132 +301,37 @@
 	// been set and must not be clobbered.
 }
 
-// Small malloc size classes >= 16 are the multiples of 16: 16, 32, 48, 64, 80, 96, 112, 128, 144, ...
-// Each P holds a pool for defers with small arg sizes.
-// Assign defer allocations to pools by rounding to 16, to match malloc size classes.
-
-const (
-	deferHeaderSize = unsafe.Sizeof(_defer{})
-	minDeferAlloc   = (deferHeaderSize + 15) &^ 15
-	minDeferArgs    = minDeferAlloc - deferHeaderSize
-)
-
-// defer size class for arg size sz
-//go:nosplit
-func deferclass(siz uintptr) uintptr {
-	if siz <= minDeferArgs {
-		return 0
-	}
-	return (siz - minDeferArgs + 15) / 16
-}
-
-// total size of memory block for defer with arg size sz
-func totaldefersize(siz uintptr) uintptr {
-	if siz <= minDeferArgs {
-		return minDeferAlloc
-	}
-	return deferHeaderSize + siz
-}
-
-// Ensure that defer arg sizes that map to the same defer size class
-// also map to the same malloc size class.
-func testdefersizes() {
-	var m [len(p{}.deferpool)]int32
-
-	for i := range m {
-		m[i] = -1
-	}
-	for i := uintptr(0); ; i++ {
-		defersc := deferclass(i)
-		if defersc >= uintptr(len(m)) {
-			break
-		}
-		siz := roundupsize(totaldefersize(i))
-		if m[defersc] < 0 {
-			m[defersc] = int32(siz)
-			continue
-		}
-		if m[defersc] != int32(siz) {
-			print("bad defer size class: i=", i, " siz=", siz, " defersc=", defersc, "\n")
-			throw("bad defer size class")
-		}
-	}
-}
-
-// The arguments associated with a deferred call are stored
-// immediately after the _defer header in memory.
-//go:nosplit
-func deferArgs(d *_defer) unsafe.Pointer {
-	if d.siz == 0 {
-		// Avoid pointer past the defer allocation.
-		return nil
-	}
-	return add(unsafe.Pointer(d), unsafe.Sizeof(*d))
-}
-
-// deferFunc returns d's deferred function. This is temporary while we
-// support both modes of GOEXPERIMENT=regabidefer. Once we commit to
-// that experiment, we should change the type of d.fn.
-//go:nosplit
-func deferFunc(d *_defer) func() {
-	if !goexperiment.RegabiDefer {
-		throw("requires GOEXPERIMENT=regabidefer")
-	}
-	var fn func()
-	*(**funcval)(unsafe.Pointer(&fn)) = d.fn
-	return fn
-}
-
-var deferType *_type // type of _defer struct
-
-func init() {
-	var x interface{}
-	x = (*_defer)(nil)
-	deferType = (*(**ptrtype)(unsafe.Pointer(&x))).elem
-}
+// Each P holds a pool for defers.
 
 // Allocate a Defer, usually using per-P pool.
 // Each defer must be released with freedefer.  The defer is not
 // added to any defer chain yet.
-//
-// This must not grow the stack because there may be a frame without
-// stack map information when this is called.
-//
-//go:nosplit
-func newdefer(siz int32) *_defer {
+func newdefer() *_defer {
 	var d *_defer
-	sc := deferclass(uintptr(siz))
-	gp := getg()
-	if sc < uintptr(len(p{}.deferpool)) {
-		pp := gp.m.p.ptr()
-		if len(pp.deferpool[sc]) == 0 && sched.deferpool[sc] != nil {
-			// Take the slow path on the system stack so
-			// we don't grow newdefer's stack.
-			systemstack(func() {
-				lock(&sched.deferlock)
-				for len(pp.deferpool[sc]) < cap(pp.deferpool[sc])/2 && sched.deferpool[sc] != nil {
-					d := sched.deferpool[sc]
-					sched.deferpool[sc] = d.link
-					d.link = nil
-					pp.deferpool[sc] = append(pp.deferpool[sc], d)
-				}
-				unlock(&sched.deferlock)
-			})
+	mp := acquirem()
+	pp := mp.p.ptr()
+	if len(pp.deferpool) == 0 && sched.deferpool != nil {
+		lock(&sched.deferlock)
+		for len(pp.deferpool) < cap(pp.deferpool)/2 && sched.deferpool != nil {
+			d := sched.deferpool
+			sched.deferpool = d.link
+			d.link = nil
+			pp.deferpool = append(pp.deferpool, d)
 		}
-		if n := len(pp.deferpool[sc]); n > 0 {
-			d = pp.deferpool[sc][n-1]
-			pp.deferpool[sc][n-1] = nil
-			pp.deferpool[sc] = pp.deferpool[sc][:n-1]
-		}
+		unlock(&sched.deferlock)
 	}
+	if n := len(pp.deferpool); n > 0 {
+		d = pp.deferpool[n-1]
+		pp.deferpool[n-1] = nil
+		pp.deferpool = pp.deferpool[:n-1]
+	}
+	releasem(mp)
+	mp, pp = nil, nil
+
 	if d == nil {
-		// Allocate new defer+args.
-		systemstack(func() {
-			total := roundupsize(totaldefersize(uintptr(siz)))
-			d = (*_defer)(mallocgc(total, deferType, true))
-		})
+		// Allocate new defer.
+		d = new(_defer)
 	}
-	d.siz = siz
 	d.heap = true
 	return d
 }
@@ -460,11 +339,16 @@
 // Free the given defer.
 // The defer cannot be used after this call.
 //
-// This must not grow the stack because there may be a frame without a
-// stack map when this is called.
+// This is nosplit because the incoming defer is in a perilous state.
+// It's not on any defer list, so stack copying won't adjust stack
+// pointers in it (namely, d.link). Hence, if we were to copy the
+// stack, d could then contain a stale pointer.
 //
 //go:nosplit
 func freedefer(d *_defer) {
+	d.link = nil
+	// After this point we can copy the stack.
+
 	if d._panic != nil {
 		freedeferpanic()
 	}
@@ -474,53 +358,36 @@
 	if !d.heap {
 		return
 	}
-	sc := deferclass(uintptr(d.siz))
-	if sc >= uintptr(len(p{}.deferpool)) {
-		return
-	}
-	pp := getg().m.p.ptr()
-	if len(pp.deferpool[sc]) == cap(pp.deferpool[sc]) {
+
+	mp := acquirem()
+	pp := mp.p.ptr()
+	if len(pp.deferpool) == cap(pp.deferpool) {
 		// Transfer half of local cache to the central cache.
-		//
-		// Take this slow path on the system stack so
-		// we don't grow freedefer's stack.
-		systemstack(func() {
-			var first, last *_defer
-			for len(pp.deferpool[sc]) > cap(pp.deferpool[sc])/2 {
-				n := len(pp.deferpool[sc])
-				d := pp.deferpool[sc][n-1]
-				pp.deferpool[sc][n-1] = nil
-				pp.deferpool[sc] = pp.deferpool[sc][:n-1]
-				if first == nil {
-					first = d
-				} else {
-					last.link = d
-				}
-				last = d
+		var first, last *_defer
+		for len(pp.deferpool) > cap(pp.deferpool)/2 {
+			n := len(pp.deferpool)
+			d := pp.deferpool[n-1]
+			pp.deferpool[n-1] = nil
+			pp.deferpool = pp.deferpool[:n-1]
+			if first == nil {
+				first = d
+			} else {
+				last.link = d
 			}
-			lock(&sched.deferlock)
-			last.link = sched.deferpool[sc]
-			sched.deferpool[sc] = first
-			unlock(&sched.deferlock)
-		})
+			last = d
+		}
+		lock(&sched.deferlock)
+		last.link = sched.deferpool
+		sched.deferpool = first
+		unlock(&sched.deferlock)
 	}
 
-	// These lines used to be simply `*d = _defer{}` but that
-	// started causing a nosplit stack overflow via typedmemmove.
-	d.siz = 0
-	d.started = false
-	d.openDefer = false
-	d.sp = 0
-	d.pc = 0
-	d.framepc = 0
-	d.varp = 0
-	d.fd = nil
-	// d._panic and d.fn must be nil already.
-	// If not, we would have called freedeferpanic or freedeferfn above,
-	// both of which throw.
-	d.link = nil
+	*d = _defer{}
 
-	pp.deferpool[sc] = append(pp.deferpool[sc], d)
+	pp.deferpool = append(pp.deferpool, d)
+
+	releasem(mp)
+	mp, pp = nil, nil
 }
 
 // Separate function so that it can split stack.
@@ -535,66 +402,39 @@
 	throw("freedefer with d.fn != nil")
 }
 
-// Run a deferred function if there is one.
+// deferreturn runs deferred functions for the caller's frame.
 // The compiler inserts a call to this at the end of any
 // function which calls defer.
-// If there is a deferred function, this will call runtime·jmpdefer,
-// which will jump to the deferred function such that it appears
-// to have been called by the caller of deferreturn at the point
-// just before deferreturn was called. The effect is that deferreturn
-// is called again and again until there are no more deferred functions.
-//
-// Declared as nosplit, because the function should not be preempted once we start
-// modifying the caller's frame in order to reuse the frame to call the deferred
-// function.
-//
-//go:nosplit
 func deferreturn() {
 	gp := getg()
-	d := gp._defer
-	if d == nil {
-		return
-	}
-	sp := getcallersp()
-	if d.sp != sp {
-		return
-	}
-	if d.openDefer {
-		done := runOpenDeferFrame(gp, d)
-		if !done {
-			throw("unfinished open-coded defers in deferreturn")
+	for {
+		d := gp._defer
+		if d == nil {
+			return
 		}
+		sp := getcallersp()
+		if d.sp != sp {
+			return
+		}
+		if d.openDefer {
+			done := runOpenDeferFrame(gp, d)
+			if !done {
+				throw("unfinished open-coded defers in deferreturn")
+			}
+			gp._defer = d.link
+			freedefer(d)
+			// If this frame uses open defers, then this
+			// must be the only defer record for the
+			// frame, so we can just return.
+			return
+		}
+
+		fn := d.fn
+		d.fn = nil
 		gp._defer = d.link
 		freedefer(d)
-		return
+		fn()
 	}
-
-	// Moving arguments around.
-	//
-	// Everything called after this point must be recursively
-	// nosplit because the garbage collector won't know the form
-	// of the arguments until the jmpdefer can flip the PC over to
-	// fn.
-	argp := getcallersp() + sys.MinFrameSize
-	switch d.siz {
-	case 0:
-		// Do nothing.
-	case sys.PtrSize:
-		*(*uintptr)(unsafe.Pointer(argp)) = *(*uintptr)(deferArgs(d))
-	default:
-		memmove(unsafe.Pointer(argp), deferArgs(d), uintptr(d.siz))
-	}
-	fn := d.fn
-	d.fn = nil
-	gp._defer = d.link
-	freedefer(d)
-	// If the defer function pointer is nil, force the seg fault to happen
-	// here rather than in jmpdefer. gentraceback() throws an error if it is
-	// called with a callback on an LR architecture and jmpdefer is on the
-	// stack, because the stack trace can be incorrect in that case - see
-	// issue #8153).
-	_ = fn.fn
-	jmpdefer(fn, argp)
 }
 
 // Goexit terminates the goroutine that calls it. No other goroutine is affected.
@@ -655,15 +495,9 @@
 				addOneOpenDeferFrame(gp, 0, nil)
 			}
 		} else {
-			if goexperiment.RegabiDefer {
-				// Save the pc/sp in deferCallSave(), so we can "recover" back to this
-				// loop if necessary.
-				deferCallSave(&p, deferFunc(d))
-			} else {
-				// Save the pc/sp in reflectcallSave(), so we can "recover" back to this
-				// loop if necessary.
-				reflectcallSave(&p, unsafe.Pointer(d.fn), deferArgs(d), uint32(d.siz))
-			}
+			// Save the pc/sp in deferCallSave(), so we can "recover" back to this
+			// loop if necessary.
+			deferCallSave(&p, d.fn)
 		}
 		if p.aborted {
 			// We had a recursive panic in the defer d we started, and
@@ -783,8 +617,7 @@
 					throw("missing deferreturn")
 				}
 
-				maxargsize, _ := readvarintUnsafe(fd)
-				d1 := newdefer(int32(maxargsize))
+				d1 := newdefer()
 				d1.openDefer = true
 				d1._panic = nil
 				// These are the pc/sp to set after we've
@@ -845,57 +678,29 @@
 	done := true
 	fd := d.fd
 
-	// Skip the maxargsize
-	_, fd = readvarintUnsafe(fd)
 	deferBitsOffset, fd := readvarintUnsafe(fd)
 	nDefers, fd := readvarintUnsafe(fd)
 	deferBits := *(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset)))
 
 	for i := int(nDefers) - 1; i >= 0; i-- {
 		// read the funcdata info for this defer
-		var argWidth, closureOffset, nArgs uint32
-		argWidth, fd = readvarintUnsafe(fd)
+		var closureOffset uint32
 		closureOffset, fd = readvarintUnsafe(fd)
-		nArgs, fd = readvarintUnsafe(fd)
-		if goexperiment.RegabiDefer && argWidth != 0 {
-			throw("defer with non-empty frame")
-		}
 		if deferBits&(1<<i) == 0 {
-			for j := uint32(0); j < nArgs; j++ {
-				_, fd = readvarintUnsafe(fd)
-				_, fd = readvarintUnsafe(fd)
-				_, fd = readvarintUnsafe(fd)
-			}
 			continue
 		}
-		closure := *(**funcval)(unsafe.Pointer(d.varp - uintptr(closureOffset)))
+		closure := *(*func())(unsafe.Pointer(d.varp - uintptr(closureOffset)))
 		d.fn = closure
-		deferArgs := deferArgs(d)
-		// If there is an interface receiver or method receiver, it is
-		// described/included as the first arg.
-		for j := uint32(0); j < nArgs; j++ {
-			var argOffset, argLen, argCallOffset uint32
-			argOffset, fd = readvarintUnsafe(fd)
-			argLen, fd = readvarintUnsafe(fd)
-			argCallOffset, fd = readvarintUnsafe(fd)
-			memmove(unsafe.Pointer(uintptr(deferArgs)+uintptr(argCallOffset)),
-				unsafe.Pointer(d.varp-uintptr(argOffset)),
-				uintptr(argLen))
-		}
 		deferBits = deferBits &^ (1 << i)
 		*(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset))) = deferBits
 		p := d._panic
-		if goexperiment.RegabiDefer {
-			deferCallSave(p, deferFunc(d))
-		} else {
-			reflectcallSave(p, unsafe.Pointer(closure), deferArgs, argWidth)
-		}
+		// Call the defer. Note that this can change d.varp if
+		// the stack moves.
+		deferCallSave(p, d.fn)
 		if p != nil && p.aborted {
 			break
 		}
 		d.fn = nil
-		// These args are just a copy, so can be cleared immediately
-		memclrNoHeapPointers(deferArgs, uintptr(argWidth))
 		if d._panic != nil && d._panic.recovered {
 			done = deferBits == 0
 			break
@@ -905,32 +710,6 @@
 	return done
 }
 
-// reflectcallSave calls reflectcall after saving the caller's pc and sp in the
-// panic record. This allows the runtime to return to the Goexit defer processing
-// loop, in the unusual case where the Goexit may be bypassed by a successful
-// recover.
-//
-// This is marked as a wrapper by the compiler so it doesn't appear in
-// tracebacks.
-func reflectcallSave(p *_panic, fn, arg unsafe.Pointer, argsize uint32) {
-	if goexperiment.RegabiDefer {
-		throw("not allowed with GOEXPERIMENT=regabidefer")
-	}
-	if p != nil {
-		p.argp = unsafe.Pointer(getargp())
-		p.pc = getcallerpc()
-		p.sp = unsafe.Pointer(getcallersp())
-	}
-	// Pass a dummy RegArgs since we'll only take this path if
-	// we're not using the register ABI.
-	var regs abi.RegArgs
-	reflectcall(nil, fn, arg, argsize, argsize, argsize, &regs)
-	if p != nil {
-		p.pc = 0
-		p.sp = unsafe.Pointer(nil)
-	}
-}
-
 // deferCallSave calls fn() after saving the caller's pc and sp in the
 // panic record. This allows the runtime to return to the Goexit defer
 // processing loop, in the unusual case where the Goexit may be
@@ -939,9 +718,6 @@
 // This is marked as a wrapper by the compiler so it doesn't appear in
 // tracebacks.
 func deferCallSave(p *_panic, fn func()) {
-	if !goexperiment.RegabiDefer {
-		throw("only allowed with GOEXPERIMENT=regabidefer")
-	}
 	if p != nil {
 		p.argp = unsafe.Pointer(getargp())
 		p.pc = getcallerpc()
@@ -1041,16 +817,7 @@
 			}
 		} else {
 			p.argp = unsafe.Pointer(getargp())
-
-			if goexperiment.RegabiDefer {
-				fn := deferFunc(d)
-				fn()
-			} else {
-				// Pass a dummy RegArgs since we'll only take this path if
-				// we're not using the register ABI.
-				var regs abi.RegArgs
-				reflectcall(nil, unsafe.Pointer(d.fn), deferArgs(d), uint32(d.siz), uint32(d.siz), uint32(d.siz), &regs)
-			}
+			d.fn()
 		}
 		p.argp = nil
 
diff --git a/src/runtime/pprof/pprof.go b/src/runtime/pprof/pprof.go
index 99eda10..000abf9 100644
--- a/src/runtime/pprof/pprof.go
+++ b/src/runtime/pprof/pprof.go
@@ -76,6 +76,7 @@
 	"bufio"
 	"bytes"
 	"fmt"
+	"internal/abi"
 	"io"
 	"runtime"
 	"sort"
@@ -289,7 +290,7 @@
 	stk = stk[:n]
 	if len(stk) == 0 {
 		// The value for skip is too large, and there's no stack trace to record.
-		stk = []uintptr{funcPC(lostProfileEvent)}
+		stk = []uintptr{abi.FuncPCABIInternal(lostProfileEvent)}
 	}
 
 	p.mu.Lock()
diff --git a/src/runtime/pprof/pprof_test.go b/src/runtime/pprof/pprof_test.go
index 7c71d82..e0d32a0 100644
--- a/src/runtime/pprof/pprof_test.go
+++ b/src/runtime/pprof/pprof_test.go
@@ -11,6 +11,7 @@
 	"bytes"
 	"context"
 	"fmt"
+	"internal/abi"
 	"internal/profile"
 	"internal/testenv"
 	"io"
@@ -116,7 +117,7 @@
 // findInlinedCall returns the PC of an inlined function call within
 // the function body for the function f if any.
 func findInlinedCall(f interface{}, maxBytes int) (pc uint64, found bool) {
-	fFunc := runtime.FuncForPC(uintptr(funcPC(f)))
+	fFunc := runtime.FuncForPC(uintptr(abi.FuncPCABIInternal(f)))
 	if fFunc == nil || fFunc.Entry() == 0 {
 		panic("failed to locate function entry")
 	}
diff --git a/src/runtime/pprof/proto.go b/src/runtime/pprof/proto.go
index bdb4454..6862513 100644
--- a/src/runtime/pprof/proto.go
+++ b/src/runtime/pprof/proto.go
@@ -8,6 +8,7 @@
 	"bytes"
 	"compress/gzip"
 	"fmt"
+	"internal/abi"
 	"io"
 	"os"
 	"runtime"
@@ -21,11 +22,6 @@
 // (The name shows up in the pprof graphs.)
 func lostProfileEvent() { lostProfileEvent() }
 
-// funcPC returns the PC for the func value f.
-func funcPC(f interface{}) uintptr {
-	return *(*[2]*uintptr)(unsafe.Pointer(&f))[1]
-}
-
 // A profileBuilder writes a profile incrementally from a
 // stream of profile samples delivered by the runtime.
 type profileBuilder struct {
@@ -325,7 +321,7 @@
 				// gentraceback guarantees that PCs in the
 				// stack can be unconditionally decremented and
 				// still be valid, so we must do the same.
-				uint64(funcPC(lostProfileEvent) + 1),
+				uint64(abi.FuncPCABIInternal(lostProfileEvent) + 1),
 			}
 		}
 		b.m.lookup(stk, tag).count += int64(count)
diff --git a/src/runtime/pprof/proto_test.go b/src/runtime/pprof/proto_test.go
index 5eb1aab..d052b9f 100644
--- a/src/runtime/pprof/proto_test.go
+++ b/src/runtime/pprof/proto_test.go
@@ -8,6 +8,7 @@
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"internal/abi"
 	"internal/profile"
 	"internal/testenv"
 	"os"
@@ -97,11 +98,11 @@
 		map2 = mprof.Mapping[1]
 		map2.BuildID, _ = elfBuildID(map2.File)
 	case "js":
-		addr1 = uint64(funcPC(f1))
-		addr2 = uint64(funcPC(f2))
+		addr1 = uint64(abi.FuncPCABIInternal(f1))
+		addr2 = uint64(abi.FuncPCABIInternal(f2))
 	default:
-		addr1 = uint64(funcPC(f1))
-		addr2 = uint64(funcPC(f2))
+		addr1 = uint64(abi.FuncPCABIInternal(f1))
+		addr2 = uint64(abi.FuncPCABIInternal(f2))
 		// Fake mapping - HasFunctions will be true because two PCs from Go
 		// will be fully symbolized.
 		fake := &profile.Mapping{ID: 1, HasFunctions: true}
diff --git a/src/runtime/preempt.go b/src/runtime/preempt.go
index 1d5aae1..a38ab79 100644
--- a/src/runtime/preempt.go
+++ b/src/runtime/preempt.go
@@ -53,8 +53,9 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -315,12 +316,12 @@
 var asyncPreemptStack = ^uintptr(0)
 
 func init() {
-	f := findfunc(funcPC(asyncPreempt))
+	f := findfunc(abi.FuncPCABI0(asyncPreempt))
 	total := funcMaxSPDelta(f)
-	f = findfunc(funcPC(asyncPreempt2))
+	f = findfunc(abi.FuncPCABIInternal(asyncPreempt2))
 	total += funcMaxSPDelta(f)
 	// Add some overhead for return PCs, etc.
-	asyncPreemptStack = uintptr(total) + 8*sys.PtrSize
+	asyncPreemptStack = uintptr(total) + 8*goarch.PtrSize
 	if asyncPreemptStack > _StackLimit {
 		// We need more than the nosplit limit. This isn't
 		// unsafe, but it may limit asynchronous preemption.
diff --git a/src/runtime/preempt_386.s b/src/runtime/preempt_386.s
index a803b24..c3a5fa1 100644
--- a/src/runtime/preempt_386.s
+++ b/src/runtime/preempt_386.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	PUSHFL
 	ADJSP $156
 	NOP SP
diff --git a/src/runtime/preempt_amd64.s b/src/runtime/preempt_amd64.s
index dc7af80..31f7c8b 100644
--- a/src/runtime/preempt_amd64.s
+++ b/src/runtime/preempt_amd64.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	PUSHQ BP
 	MOVQ SP, BP
 	// Save flags before clobbering them
diff --git a/src/runtime/preempt_arm.s b/src/runtime/preempt_arm.s
index bbc9fbb..8f243c0 100644
--- a/src/runtime/preempt_arm.s
+++ b/src/runtime/preempt_arm.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVW.W R14, -188(R13)
 	MOVW R0, 4(R13)
 	MOVW R1, 8(R13)
diff --git a/src/runtime/preempt_arm64.s b/src/runtime/preempt_arm64.s
index 2b70a28..36ee132 100644
--- a/src/runtime/preempt_arm64.s
+++ b/src/runtime/preempt_arm64.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVD R30, -496(RSP)
 	SUB $496, RSP
 	#ifdef GOOS_linux
diff --git a/src/runtime/preempt_mips64x.s b/src/runtime/preempt_mips64x.s
index b755425..c1249e3 100644
--- a/src/runtime/preempt_mips64x.s
+++ b/src/runtime/preempt_mips64x.s
@@ -6,8 +6,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVV R31, -488(R29)
 	SUBV $488, R29
 	MOVV R1, 8(R29)
diff --git a/src/runtime/preempt_mipsx.s b/src/runtime/preempt_mipsx.s
index c1bff60..70b79e0 100644
--- a/src/runtime/preempt_mipsx.s
+++ b/src/runtime/preempt_mipsx.s
@@ -6,8 +6,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVW R31, -244(R29)
 	SUB $244, R29
 	MOVW R1, 4(R29)
diff --git a/src/runtime/preempt_ppc64x.s b/src/runtime/preempt_ppc64x.s
index 70bd919..7ed4021 100644
--- a/src/runtime/preempt_ppc64x.s
+++ b/src/runtime/preempt_ppc64x.s
@@ -6,8 +6,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOVD R31, -488(R1)
 	MOVD LR, R31
 	MOVDU R31, -520(R1)
diff --git a/src/runtime/preempt_riscv64.s b/src/runtime/preempt_riscv64.s
index d4f9cc2..eb68dcb 100644
--- a/src/runtime/preempt_riscv64.s
+++ b/src/runtime/preempt_riscv64.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	MOV X1, -472(X2)
 	ADD $-472, X2
 	MOV X3, 8(X2)
diff --git a/src/runtime/preempt_s390x.s b/src/runtime/preempt_s390x.s
index c6f1157..ca9e47c 100644
--- a/src/runtime/preempt_s390x.s
+++ b/src/runtime/preempt_s390x.s
@@ -3,8 +3,7 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	IPM R10
 	MOVD R14, -248(R15)
 	ADD $-248, R15
diff --git a/src/runtime/preempt_wasm.s b/src/runtime/preempt_wasm.s
index da90e8a..0cf57d3 100644
--- a/src/runtime/preempt_wasm.s
+++ b/src/runtime/preempt_wasm.s
@@ -3,7 +3,6 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// Note: asyncPreempt doesn't use the internal ABI, but we must be able to inject calls to it from the signal handler, so Go code has to see the PC of this function literally.
-TEXT ·asyncPreempt<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
 	// No async preemption on wasm
 	UNDEF
diff --git a/src/runtime/print.go b/src/runtime/print.go
index f15296c..59a9120 100644
--- a/src/runtime/print.go
+++ b/src/runtime/print.go
@@ -5,8 +5,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -271,7 +271,7 @@
 	var markbuf [1]byte
 	markbuf[0] = ' '
 	minhexdigits = int(unsafe.Sizeof(uintptr(0)) * 2)
-	for i := uintptr(0); p+i < end; i += sys.PtrSize {
+	for i := uintptr(0); p+i < end; i += goarch.PtrSize {
 		if i%16 == 0 {
 			if i != 0 {
 				println()
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 7bc2a92..ec4be31 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -7,7 +7,7 @@
 import (
 	"internal/abi"
 	"internal/cpu"
-	"internal/goexperiment"
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -152,7 +152,7 @@
 	// Max stack size is 1 GB on 64-bit, 250 MB on 32-bit.
 	// Using decimal instead of binary GB and MB because
 	// they look nicer in the stack overflow failure message.
-	if sys.PtrSize == 8 {
+	if goarch.PtrSize == 8 {
 		maxstacksize = 1000000000
 	} else {
 		maxstacksize = 250000000
@@ -466,18 +466,6 @@
 	releasem(mp)
 }
 
-// funcPC returns the entry PC of the function f.
-// It assumes that f is a func value. Otherwise the behavior is undefined.
-// CAREFUL: In programs with plugins, funcPC can return different values
-// for the same function (because there are actually multiple copies of
-// the same function in the address space). To be safe, don't use the
-// results of this function in any == expression. It is only safe to
-// use the result as an address at which to start executing code.
-//go:nosplit
-func funcPC(f interface{}) uintptr {
-	return *(*uintptr)(efaceOf(&f).data)
-}
-
 // called from assembly
 func badmcall(fn func(*g)) {
 	throw("runtime: mcall called on m->g0 stack")
@@ -568,7 +556,7 @@
 
 // atomicAllGIndex returns ptr[i] with the allgptr returned from atomicAllG.
 func atomicAllGIndex(ptr **g, i uintptr) *g {
-	return *(**g)(add(unsafe.Pointer(ptr), i*sys.PtrSize))
+	return *(**g)(add(unsafe.Pointer(ptr), i*goarch.PtrSize))
 }
 
 // forEachG calls fn on every G from allgs.
@@ -2027,7 +2015,7 @@
 	gp := malg(4096)
 	gp.sched.pc = abi.FuncPCABI0(goexit) + sys.PCQuantum
 	gp.sched.sp = gp.stack.hi
-	gp.sched.sp -= 4 * sys.PtrSize // extra space in case of reads slightly beyond frame
+	gp.sched.sp -= 4 * goarch.PtrSize // extra space in case of reads slightly beyond frame
 	gp.sched.lr = 0
 	gp.sched.g = guintptr(unsafe.Pointer(gp))
 	gp.syscallpc = gp.sched.pc
@@ -2045,7 +2033,7 @@
 	gp.lockedm.set(mp)
 	gp.goid = int64(atomic.Xadd64(&sched.goidgen, 1))
 	if raceenabled {
-		gp.racectx = racegostart(funcPC(newextram) + sys.PCQuantum)
+		gp.racectx = racegostart(abi.FuncPCABIInternal(newextram) + sys.PCQuantum)
 	}
 	// put on allg for garbage collector
 	allgadd(gp)
@@ -2238,7 +2226,7 @@
 		}
 		ts.g.set(mp.g0)
 		ts.tls = (*uint64)(unsafe.Pointer(&mp.tls[0]))
-		ts.fn = unsafe.Pointer(funcPC(mstart))
+		ts.fn = unsafe.Pointer(abi.FuncPCABI0(mstart))
 		if msanenabled {
 			msanwrite(unsafe.Pointer(&ts), unsafe.Sizeof(ts))
 		}
@@ -4232,27 +4220,14 @@
 	return newg
 }
 
-// Create a new g running fn with siz bytes of arguments.
+// Create a new g running fn.
 // Put it on the queue of g's waiting to run.
 // The compiler turns a go statement into a call to this.
-//
-// The stack layout of this call is unusual: it assumes that the
-// arguments to pass to fn are on the stack sequentially immediately
-// after &fn. Hence, they are logically part of newproc's argument
-// frame, even though they don't appear in its signature (and can't
-// because their types differ between call sites).
-//
-// This must be nosplit because this stack layout means there are
-// untyped arguments in newproc's argument frame. Stack copies won't
-// be able to adjust them and stack splits won't be able to copy them.
-//
-//go:nosplit
-func newproc(siz int32, fn *funcval) {
-	argp := add(unsafe.Pointer(&fn), sys.PtrSize)
+func newproc(fn *funcval) {
 	gp := getg()
 	pc := getcallerpc()
 	systemstack(func() {
-		newg := newproc1(fn, argp, siz, gp, pc)
+		newg := newproc1(fn, gp, pc)
 
 		_p_ := getg().m.p.ptr()
 		runqput(_p_, newg, true)
@@ -4263,24 +4238,10 @@
 	})
 }
 
-// Create a new g in state _Grunnable, starting at fn, with narg bytes
-// of arguments starting at argp. callerpc is the address of the go
-// statement that created this. The caller is responsible for adding
-// the new g to the scheduler.
-//
-// This must run on the system stack because it's the continuation of
-// newproc, which cannot split the stack.
-//
-//go:systemstack
-func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerpc uintptr) *g {
-	if goexperiment.RegabiDefer && narg != 0 {
-		// TODO: When we commit to GOEXPERIMENT=regabidefer,
-		// rewrite the comments for newproc and newproc1.
-		// newproc will no longer have a funny stack layout or
-		// need to be nosplit.
-		throw("go with non-empty frame")
-	}
-
+// Create a new g in state _Grunnable, starting at fn. callerpc is the
+// address of the go statement that created this. The caller is responsible
+// for adding the new g to the scheduler.
+func newproc1(fn *funcval, callergp *g, callerpc uintptr) *g {
 	_g_ := getg()
 
 	if fn == nil {
@@ -4288,16 +4249,6 @@
 		throw("go of nil func value")
 	}
 	acquirem() // disable preemption because it can be holding p in a local var
-	siz := narg
-	siz = (siz + 7) &^ 7
-
-	// We could allocate a larger initial stack if necessary.
-	// Not worth it: this is almost always an error.
-	// 4*PtrSize: extra space added below
-	// PtrSize: caller's LR (arm) or return address (x86, in gostartcall).
-	if siz >= _StackMin-4*sys.PtrSize-sys.PtrSize {
-		throw("newproc: function arguments too large for new goroutine")
-	}
 
 	_p_ := _g_.m.p.ptr()
 	newg := gfget(_p_)
@@ -4314,8 +4265,8 @@
 		throw("newproc1: new g is not Gdead")
 	}
 
-	totalSize := 4*sys.PtrSize + uintptr(siz) + sys.MinFrameSize // extra space in case of reads slightly beyond frame
-	totalSize += -totalSize & (sys.StackAlign - 1)               // align to StackAlign
+	totalSize := uintptr(4*goarch.PtrSize + sys.MinFrameSize) // extra space in case of reads slightly beyond frame
+	totalSize = alignUp(totalSize, sys.StackAlign)
 	sp := newg.stack.hi - totalSize
 	spArg := sp
 	if usesLR {
@@ -4324,24 +4275,6 @@
 		prepGoExitFrame(sp)
 		spArg += sys.MinFrameSize
 	}
-	if narg > 0 {
-		memmove(unsafe.Pointer(spArg), argp, uintptr(narg))
-		// This is a stack-to-stack copy. If write barriers
-		// are enabled and the source stack is grey (the
-		// destination is always black), then perform a
-		// barrier copy. We do this *after* the memmove
-		// because the destination stack may have garbage on
-		// it.
-		if writeBarrier.needed && !_g_.m.curg.gcscandone {
-			f := findfunc(fn.fn)
-			stkmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
-			if stkmap.nbit > 0 {
-				// We're in the prologue, so it's always stack map index 0.
-				bv := stackmapdata(stkmap, 0)
-				bulkBarrierBitmap(spArg, spArg, uintptr(bv.n)*sys.PtrSize, 0, bv.bytedata)
-			}
-		}
-	}
 
 	memclrNoHeapPointers(unsafe.Pointer(&newg.sched), unsafe.Sizeof(newg.sched))
 	newg.sched.sp = sp
@@ -4751,16 +4684,16 @@
 			// If all of the above has failed, account it against abstract "System" or "GC".
 			n = 2
 			if inVDSOPage(pc) {
-				pc = funcPC(_VDSO) + sys.PCQuantum
+				pc = abi.FuncPCABIInternal(_VDSO) + sys.PCQuantum
 			} else if pc > firstmoduledata.etext {
 				// "ExternalCode" is better than "etext".
-				pc = funcPC(_ExternalCode) + sys.PCQuantum
+				pc = abi.FuncPCABIInternal(_ExternalCode) + sys.PCQuantum
 			}
 			stk[0] = pc
 			if mp.preemptoff != "" {
-				stk[1] = funcPC(_GC) + sys.PCQuantum
+				stk[1] = abi.FuncPCABIInternal(_GC) + sys.PCQuantum
 			} else {
-				stk[1] = funcPC(_System) + sys.PCQuantum
+				stk[1] = abi.FuncPCABIInternal(_System) + sys.PCQuantum
 			}
 		}
 	}
@@ -4804,7 +4737,7 @@
 	if prof.hz != 0 {
 		stk := []uintptr{
 			pc,
-			funcPC(_ExternalCode) + sys.PCQuantum,
+			abi.FuncPCABIInternal(_ExternalCode) + sys.PCQuantum,
 		}
 		cpuprof.addNonGo(stk)
 	}
@@ -4854,9 +4787,7 @@
 	pp.id = id
 	pp.status = _Pgcstop
 	pp.sudogcache = pp.sudogbuf[:0]
-	for i := range pp.deferpool {
-		pp.deferpool[i] = pp.deferpoolbuf[i][:0]
-	}
+	pp.deferpool = pp.deferpoolbuf[:0]
 	pp.wbBuf.reset()
 	if pp.mcache == nil {
 		if id == 0 {
@@ -4933,12 +4864,10 @@
 		pp.sudogbuf[i] = nil
 	}
 	pp.sudogcache = pp.sudogbuf[:0]
-	for i := range pp.deferpool {
-		for j := range pp.deferpoolbuf[i] {
-			pp.deferpoolbuf[i][j] = nil
-		}
-		pp.deferpool[i] = pp.deferpoolbuf[i][:0]
+	for j := range pp.deferpoolbuf {
+		pp.deferpoolbuf[j] = nil
 	}
+	pp.deferpool = pp.deferpoolbuf[:0]
 	systemstack(func() {
 		for i := 0; i < pp.mspancache.len; i++ {
 			// Safe to call since the world is stopped.
@@ -6463,7 +6392,7 @@
 		t.state = 1 // initialization in progress
 
 		for i := uintptr(0); i < t.ndeps; i++ {
-			p := add(unsafe.Pointer(t), (3+i)*sys.PtrSize)
+			p := add(unsafe.Pointer(t), (3+i)*goarch.PtrSize)
 			t2 := *(**initTask)(p)
 			doInit(t2)
 		}
@@ -6484,9 +6413,9 @@
 			before = inittrace
 		}
 
-		firstFunc := add(unsafe.Pointer(t), (3+t.ndeps)*sys.PtrSize)
+		firstFunc := add(unsafe.Pointer(t), (3+t.ndeps)*goarch.PtrSize)
 		for i := uintptr(0); i < t.nfns; i++ {
-			p := add(firstFunc, i*sys.PtrSize)
+			p := add(firstFunc, i*goarch.PtrSize)
 			f := *(*func())(unsafe.Pointer(&p))
 			f()
 		}
@@ -6496,7 +6425,8 @@
 			// Load stats non-atomically since tracinit is updated only by this init goroutine.
 			after := inittrace
 
-			pkg := funcpkgpath(findfunc(funcPC(firstFunc)))
+			f := *(*func())(unsafe.Pointer(&firstFunc))
+			pkg := funcpkgpath(findfunc(abi.FuncPCABIInternal(f)))
 
 			var sbuf [24]byte
 			print("init ", pkg, " @")
diff --git a/src/runtime/race.go b/src/runtime/race.go
index ce6b5b5..7eaa9d2 100644
--- a/src/runtime/race.go
+++ b/src/runtime/race.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"unsafe"
 )
 
@@ -361,7 +362,7 @@
 		throw("raceinit: race build must use cgo")
 	}
 
-	racecall(&__tsan_init, uintptr(unsafe.Pointer(&gctx)), uintptr(unsafe.Pointer(&pctx)), funcPC(racecallbackthunk), 0)
+	racecall(&__tsan_init, uintptr(unsafe.Pointer(&gctx)), uintptr(unsafe.Pointer(&pctx)), abi.FuncPCABI0(racecallbackthunk), 0)
 
 	// Round data segment to page boundaries, because it's used in mmap().
 	start := ^uintptr(0)
diff --git a/src/runtime/race/output_test.go b/src/runtime/race/output_test.go
index 9905207..63fcd84 100644
--- a/src/runtime/race/output_test.go
+++ b/src/runtime/race/output_test.go
@@ -148,7 +148,7 @@
 package main
 func main() {
 	done := make(chan bool)
-	x := 0
+	x := 0; _ = x
 	go func() {
 		x = 42
 		done <- true
@@ -162,7 +162,7 @@
 package main
 func main() {
 	done := make(chan bool)
-	x := 0
+	x := 0; _ = x
 	go func() {
 		x = 42
 		done <- true
@@ -178,7 +178,7 @@
 package main
 func main() {
 	done := make(chan bool)
-	x := 0
+	x := 0; _ = x
 	go func() {
 		x = 42
 		done <- true
diff --git a/src/runtime/race_amd64.s b/src/runtime/race_amd64.s
index 8d4813e..d42e415d 100644
--- a/src/runtime/race_amd64.s
+++ b/src/runtime/race_amd64.s
@@ -46,11 +46,7 @@
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·raceread<ABIInternal>(SB), NOSPLIT, $0-8
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
-#else
-	MOVQ	addr+0(FP), RARG1
-#endif
 	MOVQ	(SP), RARG2
 	// void __tsan_read(ThreadState *thr, void *addr, void *pc);
 	MOVQ	$__tsan_read(SB), AX
@@ -76,11 +72,7 @@
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·racewrite<ABIInternal>(SB), NOSPLIT, $0-8
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
-#else
-	MOVQ	addr+0(FP), RARG1
-#endif
 	MOVQ	(SP), RARG2
 	// void __tsan_write(ThreadState *thr, void *addr, void *pc);
 	MOVQ	$__tsan_write(SB), AX
@@ -131,13 +123,8 @@
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·racewriterange<ABIInternal>(SB), NOSPLIT, $0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
 	MOVQ	BX, RARG2
-#else
-	MOVQ	addr+0(FP), RARG1
-	MOVQ	size+8(FP), RARG2
-#endif
 	MOVQ	(SP), RARG3
 	// void __tsan_write_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVQ	$__tsan_write_range(SB), AX
@@ -161,10 +148,6 @@
 // If addr (RARG1) is out of range, do nothing.
 // Otherwise, setup goroutine context and invoke racecall. Other arguments already set.
 TEXT	racecalladdr<>(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	// Check that addr is within [arenastart, arenaend) or within [racedatastart, racedataend).
 	CMPQ	RARG1, runtime·racearenastart(SB)
@@ -192,10 +175,6 @@
 // R11 = caller's return address
 TEXT	racefuncenter<>(SB), NOSPLIT, $0-0
 	MOVQ	DX, BX		// save function entry context (for closures)
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	MOVQ	R11, RARG1
 	// void __tsan_func_enter(ThreadState *thr, void *pc);
@@ -208,10 +187,6 @@
 // func runtime·racefuncexit()
 // Called from instrumented code.
 TEXT	runtime·racefuncexit(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	// void __tsan_func_exit(ThreadState *thr);
 	MOVQ	$__tsan_func_exit(SB), AX
@@ -370,10 +345,6 @@
 	JAE	racecallatomic_ignore
 racecallatomic_ok:
 	// Addr is within the good range, call the atomic function.
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	MOVQ	8(SP), RARG1	// caller pc
 	MOVQ	(SP), RARG2	// pc
@@ -385,10 +356,6 @@
 	// An attempt to synchronize on the address would cause crash.
 	MOVQ	AX, BX	// remember the original function
 	MOVQ	$__tsan_go_ignore_sync_begin(SB), AX
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	CALL	racecall<>(SB)
 	MOVQ	BX, AX	// restore the original function
@@ -416,10 +383,6 @@
 
 // Switches SP to g0 stack and calls (AX). Arguments already set.
 TEXT	racecall<>(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_m(R14), R13
 	// Switch to g0 stack.
 	MOVQ	SP, R12		// callee-saved, preserved across the CALL
@@ -441,9 +404,7 @@
 // The overall effect of Go->C->Go call chain is similar to that of mcall.
 // RARG0 contains command code. RARG1 contains command-specific context.
 // See racecallback for command codes.
-// Defined as ABIInternal so as to avoid introducing a wrapper,
-// because its address is passed to C via funcPC.
-TEXT	runtime·racecallbackthunk<ABIInternal>(SB), NOSPLIT, $0-0
+TEXT	runtime·racecallbackthunk(SB), NOSPLIT, $0-0
 	// Handle command raceGetProcCmd (0) here.
 	// First, code below assumes that we are on curg, while raceGetProcCmd
 	// can be executed on g0. Second, it is called frequently, so will
diff --git a/src/runtime/race_arm64.s b/src/runtime/race_arm64.s
index c6d5b91..2b2413b 100644
--- a/src/runtime/race_arm64.s
+++ b/src/runtime/race_arm64.s
@@ -43,8 +43,14 @@
 
 // func runtime·raceread(addr uintptr)
 // Called from instrumented code.
-TEXT	runtime·raceread(SB), NOSPLIT, $0-8
+// Defined as ABIInternal so as to avoid introducing a wrapper,
+// which would make caller's PC ineffective.
+TEXT	runtime·raceread<ABIInternal>(SB), NOSPLIT, $0-8
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R0, R1	// addr
+#else
 	MOVD	addr+0(FP), R1
+#endif
 	MOVD	LR, R2
 	// void __tsan_read(ThreadState *thr, void *addr, void *pc);
 	MOVD	$__tsan_read(SB), R9
@@ -66,8 +72,14 @@
 
 // func runtime·racewrite(addr uintptr)
 // Called from instrumented code.
-TEXT	runtime·racewrite(SB), NOSPLIT, $0-8
+// Defined as ABIInternal so as to avoid introducing a wrapper,
+// which would make caller's PC ineffective.
+TEXT	runtime·racewrite<ABIInternal>(SB), NOSPLIT, $0-8
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R0, R1	// addr
+#else
 	MOVD	addr+0(FP), R1
+#endif
 	MOVD	LR, R2
 	// void __tsan_write(ThreadState *thr, void *addr, void *pc);
 	MOVD	$__tsan_write(SB), R9
@@ -89,9 +101,16 @@
 
 // func runtime·racereadrange(addr, size uintptr)
 // Called from instrumented code.
-TEXT	runtime·racereadrange(SB), NOSPLIT, $0-16
+// Defined as ABIInternal so as to avoid introducing a wrapper,
+// which would make caller's PC ineffective.
+TEXT	runtime·racereadrange<ABIInternal>(SB), NOSPLIT, $0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R2	// size
+	MOVD	R0, R1	// addr
+#else
 	MOVD	addr+0(FP), R1
 	MOVD	size+8(FP), R2
+#endif
 	MOVD	LR, R3
 	// void __tsan_read_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVD	$__tsan_read_range(SB), R9
@@ -114,9 +133,16 @@
 
 // func runtime·racewriterange(addr, size uintptr)
 // Called from instrumented code.
-TEXT	runtime·racewriterange(SB), NOSPLIT, $0-16
+// Defined as ABIInternal so as to avoid introducing a wrapper,
+// which would make caller's PC ineffective.
+TEXT	runtime·racewriterange<ABIInternal>(SB), NOSPLIT, $0-16
+#ifdef GOEXPERIMENT_regabiargs
+	MOVD	R1, R2	// size
+	MOVD	R0, R1	// addr
+#else
 	MOVD	addr+0(FP), R1
 	MOVD	size+8(FP), R2
+#endif
 	MOVD	LR, R3
 	// void __tsan_write_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVD	$__tsan_write_range(SB), R9
diff --git a/src/runtime/runtime1.go b/src/runtime/runtime1.go
index b238da8..b6c3cbf 100644
--- a/src/runtime/runtime1.go
+++ b/src/runtime/runtime1.go
@@ -6,8 +6,8 @@
 
 import (
 	"internal/bytealg"
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -55,7 +55,7 @@
 // nosplit for use in linux startup sysargs
 //go:nosplit
 func argv_index(argv **byte, i int32) *byte {
-	return *(**byte)(add(unsafe.Pointer(argv), uintptr(i)*sys.PtrSize))
+	return *(**byte)(add(unsafe.Pointer(argv), uintptr(i)*goarch.PtrSize))
 }
 
 func args(c int32, v **byte) {
@@ -190,10 +190,10 @@
 	if unsafe.Sizeof(j) != 8 {
 		throw("bad j")
 	}
-	if unsafe.Sizeof(k) != sys.PtrSize {
+	if unsafe.Sizeof(k) != goarch.PtrSize {
 		throw("bad k")
 	}
-	if unsafe.Sizeof(l) != sys.PtrSize {
+	if unsafe.Sizeof(l) != goarch.PtrSize {
 		throw("bad l")
 	}
 	if unsafe.Sizeof(x1) != 1 {
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 5051ec4..e4e9ee5 100644
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -5,8 +5,8 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -505,7 +505,7 @@
 	// tlsSlots is the number of pointer-sized slots reserved for TLS on some platforms,
 	// like Windows.
 	tlsSlots = 6
-	tlsSize  = tlsSlots * sys.PtrSize
+	tlsSize  = tlsSlots * goarch.PtrSize
 )
 
 type m struct {
@@ -613,8 +613,8 @@
 	pcache      pageCache
 	raceprocctx uintptr
 
-	deferpool    [5][]*_defer // pool of available defer structs of different sizes (see panic.go)
-	deferpoolbuf [5][32]*_defer
+	deferpool    []*_defer // pool of available defer structs (see panic.go)
+	deferpoolbuf [32]*_defer
 
 	// Cache of goroutine ids, amortizes accesses to runtime·sched.goidgen.
 	goidcache    uint64
@@ -795,9 +795,9 @@
 	sudoglock  mutex
 	sudogcache *sudog
 
-	// Central pool of available defer structs of different sizes.
+	// Central pool of available defer structs.
 	deferlock mutex
-	deferpool [5]*_defer
+	deferpool *_defer
 
 	// freem is the list of m's waiting to be freed when their
 	// m.exited is set. Linked through m.freelink.
@@ -924,7 +924,7 @@
 			w = 16
 		}
 		h := memhash(unsafe.Pointer(&r[n-w]), uintptr(nanotime()), uintptr(w))
-		for i := 0; i < sys.PtrSize && n < len(r); i++ {
+		for i := 0; i < goarch.PtrSize && n < len(r); i++ {
 			r[n] = byte(h)
 			n++
 			h >>= 8
@@ -934,25 +934,24 @@
 
 // A _defer holds an entry on the list of deferred calls.
 // If you add a field here, add code to clear it in freedefer and deferProcStack
-// This struct must match the code in cmd/compile/internal/reflectdata/reflect.go:deferstruct
-// and cmd/compile/internal/gc/ssa.go:(*state).call.
+// This struct must match the code in cmd/compile/internal/ssagen/ssa.go:deferstruct
+// and cmd/compile/internal/ssagen/ssa.go:(*state).call.
 // Some defers will be allocated on the stack and some on the heap.
 // All defers are logically part of the stack, so write barriers to
 // initialize them are not required. All defers must be manually scanned,
 // and for heap defers, marked.
 type _defer struct {
-	siz     int32 // includes both arguments and results
 	started bool
 	heap    bool
 	// openDefer indicates that this _defer is for a frame with open-coded
 	// defers. We have only one defer record for the entire frame (which may
 	// currently have 0, 1, or more defers active).
 	openDefer bool
-	sp        uintptr  // sp at time of defer
-	pc        uintptr  // pc at time of defer
-	fn        *funcval // can be nil for open-coded defers
-	_panic    *_panic  // panic that is running defer
-	link      *_defer
+	sp        uintptr // sp at time of defer
+	pc        uintptr // pc at time of defer
+	fn        func()  // can be nil for open-coded defers
+	_panic    *_panic // panic that is running defer
+	link      *_defer // next defer on G; can point to either heap or stack!
 
 	// If openDefer is true, the fields below record values about the stack
 	// frame and associated function that has the open-coded defer(s). sp
diff --git a/src/runtime/select.go b/src/runtime/select.go
index 06edb69..ee1f95f 100644
--- a/src/runtime/select.go
+++ b/src/runtime/select.go
@@ -7,6 +7,7 @@
 // This file contains the implementation of Go select statements.
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -22,8 +23,8 @@
 }
 
 var (
-	chansendpc = funcPC(chansend)
-	chanrecvpc = funcPC(chanrecv)
+	chansendpc = abi.FuncPCABIInternal(chansend)
+	chanrecvpc = abi.FuncPCABIInternal(chanrecv)
 )
 
 func selectsetpc(pc *uintptr) {
diff --git a/src/runtime/signal_386.go b/src/runtime/signal_386.go
index 5824ead..69a59e6 100644
--- a/src/runtime/signal_386.go
+++ b/src/runtime/signal_386.go
@@ -8,7 +8,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -42,17 +43,17 @@
 	sp := uintptr(c.esp())
 
 	if shouldPushSigpanic(gp, pc, *(*uintptr)(unsafe.Pointer(sp))) {
-		c.pushCall(funcPC(sigpanic), pc)
+		c.pushCall(abi.FuncPCABIInternal(sigpanic), pc)
 	} else {
 		// Not safe to push the call. Just clobber the frame.
-		c.set_eip(uint32(funcPC(sigpanic)))
+		c.set_eip(uint32(abi.FuncPCABIInternal(sigpanic)))
 	}
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
 	// Make it look like we called target at resumePC.
 	sp := uintptr(c.esp())
-	sp -= sys.PtrSize
+	sp -= goarch.PtrSize
 	*(*uintptr)(unsafe.Pointer(sp)) = resumePC
 	c.set_esp(uint32(sp))
 	c.set_eip(uint32(targetPC))
diff --git a/src/runtime/signal_aix_ppc64.go b/src/runtime/signal_aix_ppc64.go
index a0becd4..5999d9d 100644
--- a/src/runtime/signal_aix_ppc64.go
+++ b/src/runtime/signal_aix_ppc64.go
@@ -8,7 +8,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -82,5 +82,5 @@
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_amd64.go b/src/runtime/signal_amd64.go
index e45fbb4..20490cf 100644
--- a/src/runtime/signal_amd64.go
+++ b/src/runtime/signal_amd64.go
@@ -9,7 +9,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -70,17 +71,17 @@
 	// Go special registers. We inject sigpanic0 (instead of sigpanic),
 	// which takes care of that.
 	if shouldPushSigpanic(gp, pc, *(*uintptr)(unsafe.Pointer(sp))) {
-		c.pushCall(funcPC(sigpanic0), pc)
+		c.pushCall(abi.FuncPCABI0(sigpanic0), pc)
 	} else {
 		// Not safe to push the call. Just clobber the frame.
-		c.set_rip(uint64(funcPC(sigpanic0)))
+		c.set_rip(uint64(abi.FuncPCABI0(sigpanic0)))
 	}
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
 	// Make it look like we called target at resumePC.
 	sp := uintptr(c.rsp())
-	sp -= sys.PtrSize
+	sp -= goarch.PtrSize
 	*(*uintptr)(unsafe.Pointer(sp)) = resumePC
 	c.set_rsp(uint64(sp))
 	c.set_rip(uint64(targetPC))
diff --git a/src/runtime/signal_arm.go b/src/runtime/signal_arm.go
index 4d9c622..a078078 100644
--- a/src/runtime/signal_arm.go
+++ b/src/runtime/signal_arm.go
@@ -7,7 +7,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 func dumpregs(c *sigctxt) {
 	print("trap    ", hex(c.trap()), "\n")
@@ -61,7 +64,7 @@
 
 	// In case we are panicking from external C code
 	c.set_r10(uint32(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint32(funcPC(sigpanic)))
+	c.set_pc(uint32(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_arm64.go b/src/runtime/signal_arm64.go
index f047500..9d4a8b8 100644
--- a/src/runtime/signal_arm64.go
+++ b/src/runtime/signal_arm64.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -77,7 +78,7 @@
 
 	// In case we are panicking from external C code
 	c.set_r28(uint64(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint64(funcPC(sigpanic)))
+	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_linux_386.go b/src/runtime/signal_linux_386.go
index 13d9df4..321518c 100644
--- a/src/runtime/signal_linux_386.go
+++ b/src/runtime/signal_linux_386.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -42,5 +42,5 @@
 func (c *sigctxt) set_esp(x uint32)     { c.regs().esp = x }
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint32) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_amd64.go b/src/runtime/signal_linux_amd64.go
index 210e896..573b118 100644
--- a/src/runtime/signal_linux_amd64.go
+++ b/src/runtime/signal_linux_amd64.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -52,5 +52,5 @@
 func (c *sigctxt) set_rsp(x uint64)     { c.regs().rsp = x }
 func (c *sigctxt) set_sigcode(x uint64) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_arm.go b/src/runtime/signal_linux_arm.go
index 876b505..eb107d6 100644
--- a/src/runtime/signal_linux_arm.go
+++ b/src/runtime/signal_linux_arm.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -54,5 +54,5 @@
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint32) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_arm64.go b/src/runtime/signal_linux_arm64.go
index 2075f25..4ccc030 100644
--- a/src/runtime/signal_linux_arm64.go
+++ b/src/runtime/signal_linux_arm64.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -67,5 +67,5 @@
 func (c *sigctxt) set_r28(x uint64) { c.regs().regs[28] = x }
 
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_mips64x.go b/src/runtime/signal_linux_mips64x.go
index f0a75ac..e62d6a9 100644
--- a/src/runtime/signal_linux_mips64x.go
+++ b/src/runtime/signal_linux_mips64x.go
@@ -9,7 +9,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -75,5 +75,5 @@
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_ppc64x.go b/src/runtime/signal_linux_ppc64x.go
index d9d3e55..d2eeb39 100644
--- a/src/runtime/signal_linux_ppc64x.go
+++ b/src/runtime/signal_linux_ppc64x.go
@@ -9,7 +9,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -79,5 +79,5 @@
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_riscv64.go b/src/runtime/signal_linux_riscv64.go
index 9f68e5c..b26450d 100644
--- a/src/runtime/signal_linux_riscv64.go
+++ b/src/runtime/signal_linux_riscv64.go
@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -64,5 +64,5 @@
 
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
diff --git a/src/runtime/signal_linux_s390x.go b/src/runtime/signal_linux_s390x.go
index 12d5c31..18c3b11 100644
--- a/src/runtime/signal_linux_s390x.go
+++ b/src/runtime/signal_linux_s390x.go
@@ -5,6 +5,8 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -53,7 +55,7 @@
 func (c *sigctxt) set_pc(x uint64)      { c.regs().psw_addr = x }
 func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
 func (c *sigctxt) set_sigaddr(x uint64) {
-	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
 }
 
 func dumpregs(c *sigctxt) {
@@ -107,7 +109,7 @@
 	// In case we are panicking from external C code
 	c.set_r0(0)
 	c.set_r13(uint64(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint64(funcPC(sigpanic)))
+	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_mips64x.go b/src/runtime/signal_mips64x.go
index 1616b57..87dfa72 100644
--- a/src/runtime/signal_mips64x.go
+++ b/src/runtime/signal_mips64x.go
@@ -9,7 +9,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -68,7 +69,7 @@
 	// functions are correctly handled. This smashes
 	// the stack frame but we're not going back there
 	// anyway.
-	sp := c.sp() - sys.PtrSize
+	sp := c.sp() - goarch.PtrSize
 	c.set_sp(sp)
 	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
 
@@ -80,7 +81,7 @@
 	}
 
 	// In case we are panicking from external C code
-	sigpanicPC := uint64(funcPC(sigpanic))
+	sigpanicPC := uint64(abi.FuncPCABIInternal(sigpanic))
 	c.set_r28(sigpanicPC >> 32 << 32) // RSB register
 	c.set_r30(uint64(uintptr(unsafe.Pointer(gp))))
 	c.set_pc(sigpanicPC)
diff --git a/src/runtime/signal_mipsx.go b/src/runtime/signal_mipsx.go
index dcc7f1e..5067799 100644
--- a/src/runtime/signal_mipsx.go
+++ b/src/runtime/signal_mipsx.go
@@ -9,6 +9,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -78,7 +79,7 @@
 
 	// In case we are panicking from external C code
 	c.set_r30(uint32(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint32(funcPC(sigpanic)))
+	c.set_pc(uint32(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_ppc64x.go b/src/runtime/signal_ppc64x.go
index f2225da..8a39d59 100644
--- a/src/runtime/signal_ppc64x.go
+++ b/src/runtime/signal_ppc64x.go
@@ -9,6 +9,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -83,8 +84,8 @@
 	// In case we are panicking from external C code
 	c.set_r0(0)
 	c.set_r30(uint64(uintptr(unsafe.Pointer(gp))))
-	c.set_r12(uint64(funcPC(sigpanic)))
-	c.set_pc(uint64(funcPC(sigpanic)))
+	c.set_r12(uint64(abi.FuncPCABIInternal(sigpanic)))
+	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
diff --git a/src/runtime/signal_riscv64.go b/src/runtime/signal_riscv64.go
index e6b1b14..8a24e4e 100644
--- a/src/runtime/signal_riscv64.go
+++ b/src/runtime/signal_riscv64.go
@@ -8,7 +8,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -63,7 +64,7 @@
 	// functions are correctly handled. This smashes
 	// the stack frame but we're not going back there
 	// anyway.
-	sp := c.sp() - sys.PtrSize
+	sp := c.sp() - goarch.PtrSize
 	c.set_sp(sp)
 	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.ra()
 
@@ -76,7 +77,7 @@
 
 	// In case we are panicking from external C code
 	c.set_gp(uint64(uintptr(unsafe.Pointer(gp))))
-	c.set_pc(uint64(funcPC(sigpanic)))
+	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
 }
 
 func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
@@ -84,7 +85,7 @@
 	// push the call. The function being pushed is responsible
 	// for restoring the LR and setting the SP back.
 	// This extra slot is known to gentraceback.
-	sp := c.sp() - sys.PtrSize
+	sp := c.sp() - goarch.PtrSize
 	c.set_sp(sp)
 	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.ra()
 	// Set up PC and LR to pretend the function being signaled
diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index 6096760..8117582 100644
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -8,6 +8,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -143,7 +144,7 @@
 		}
 
 		handlingSig[i] = 1
-		setsig(i, funcPC(sighandler))
+		setsig(i, abi.FuncPCABIInternal(sighandler))
 	}
 }
 
@@ -194,7 +195,7 @@
 		<-maskUpdatedChan
 		if atomic.Cas(&handlingSig[sig], 0, 1) {
 			atomic.Storeuintptr(&fwdSig[sig], getsig(sig))
-			setsig(sig, funcPC(sighandler))
+			setsig(sig, abi.FuncPCABIInternal(sighandler))
 		}
 	}
 }
@@ -271,7 +272,7 @@
 		// Enable the Go signal handler if not enabled.
 		if atomic.Cas(&handlingSig[_SIGPROF], 0, 1) {
 			atomic.Storeuintptr(&fwdSig[_SIGPROF], getsig(_SIGPROF))
-			setsig(_SIGPROF, funcPC(sighandler))
+			setsig(_SIGPROF, abi.FuncPCABIInternal(sighandler))
 		}
 
 		var it itimerval
@@ -329,7 +330,7 @@
 	if wantAsyncPreempt(gp) {
 		if ok, newpc := isAsyncSafePoint(gp, ctxt.sigpc(), ctxt.sigsp(), ctxt.siglr()); ok {
 			// Adjust the PC and inject a call to asyncPreempt.
-			ctxt.pushCall(funcPC(asyncPreempt), newpc)
+			ctxt.pushCall(abi.FuncPCABI0(asyncPreempt), newpc)
 		}
 	}
 
@@ -843,7 +844,7 @@
 	// We may receive another instance of the signal before we
 	// restore the Go handler, but that is not so bad: we know
 	// that the Go program has been ignoring the signal.
-	setsig(sig, funcPC(sighandler))
+	setsig(sig, abi.FuncPCABIInternal(sighandler))
 }
 
 //go:nosplit
diff --git a/src/runtime/signal_windows.go b/src/runtime/signal_windows.go
index b720ddc..3fe352e 100644
--- a/src/runtime/signal_windows.go
+++ b/src/runtime/signal_windows.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -27,15 +28,15 @@
 func lastcontinuetramp()
 
 func initExceptionHandler() {
-	stdcall2(_AddVectoredExceptionHandler, 1, funcPC(exceptiontramp))
+	stdcall2(_AddVectoredExceptionHandler, 1, abi.FuncPCABI0(exceptiontramp))
 	if _AddVectoredContinueHandler == nil || GOARCH == "386" {
 		// use SetUnhandledExceptionFilter for windows-386 or
 		// if VectoredContinueHandler is unavailable.
 		// note: SetUnhandledExceptionFilter handler won't be called, if debugging.
-		stdcall1(_SetUnhandledExceptionFilter, funcPC(lastcontinuetramp))
+		stdcall1(_SetUnhandledExceptionFilter, abi.FuncPCABI0(lastcontinuetramp))
 	} else {
-		stdcall2(_AddVectoredContinueHandler, 1, funcPC(firstcontinuetramp))
-		stdcall2(_AddVectoredContinueHandler, 0, funcPC(lastcontinuetramp))
+		stdcall2(_AddVectoredContinueHandler, 1, abi.FuncPCABI0(firstcontinuetramp))
+		stdcall2(_AddVectoredContinueHandler, 0, abi.FuncPCABI0(lastcontinuetramp))
 	}
 }
 
@@ -133,7 +134,7 @@
 	// The exception is not from asyncPreempt, so not to push a
 	// sigpanic call to make it look like that. Instead, just
 	// overwrite the PC. (See issue #35773)
-	if r.ip() != 0 && r.ip() != funcPC(asyncPreempt) {
+	if r.ip() != 0 && r.ip() != abi.FuncPCABI0(asyncPreempt) {
 		sp := unsafe.Pointer(r.sp())
 		delta := uintptr(sys.StackAlign)
 		sp = add(sp, -delta)
@@ -145,7 +146,7 @@
 			*((*uintptr)(sp)) = r.ip()
 		}
 	}
-	r.set_ip(funcPC(sigpanic0))
+	r.set_ip(abi.FuncPCABI0(sigpanic0))
 	return _EXCEPTION_CONTINUE_EXECUTION
 }
 
diff --git a/src/runtime/slice.go b/src/runtime/slice.go
index 01cdcae..e8267be 100644
--- a/src/runtime/slice.go
+++ b/src/runtime/slice.go
@@ -5,6 +5,8 @@
 package runtime
 
 import (
+	"internal/abi"
+	"internal/goarch"
 	"runtime/internal/math"
 	"runtime/internal/sys"
 	"unsafe"
@@ -68,7 +70,7 @@
 
 	if raceenabled {
 		callerpc := getcallerpc()
-		pc := funcPC(makeslicecopy)
+		pc := abi.FuncPCABIInternal(makeslicecopy)
 		racereadrangepc(from, copymem, callerpc, pc)
 	}
 	if msanenabled {
@@ -162,7 +164,7 @@
 func growslice(et *_type, old slice, cap int) slice {
 	if raceenabled {
 		callerpc := getcallerpc()
-		racereadrangepc(old.array, uintptr(old.len*int(et.size)), callerpc, funcPC(growslice))
+		racereadrangepc(old.array, uintptr(old.len*int(et.size)), callerpc, abi.FuncPCABIInternal(growslice))
 	}
 	if msanenabled {
 		msanread(old.array, uintptr(old.len*int(et.size)))
@@ -212,15 +214,15 @@
 		capmem = roundupsize(uintptr(newcap))
 		overflow = uintptr(newcap) > maxAlloc
 		newcap = int(capmem)
-	case et.size == sys.PtrSize:
-		lenmem = uintptr(old.len) * sys.PtrSize
-		newlenmem = uintptr(cap) * sys.PtrSize
-		capmem = roundupsize(uintptr(newcap) * sys.PtrSize)
-		overflow = uintptr(newcap) > maxAlloc/sys.PtrSize
-		newcap = int(capmem / sys.PtrSize)
+	case et.size == goarch.PtrSize:
+		lenmem = uintptr(old.len) * goarch.PtrSize
+		newlenmem = uintptr(cap) * goarch.PtrSize
+		capmem = roundupsize(uintptr(newcap) * goarch.PtrSize)
+		overflow = uintptr(newcap) > maxAlloc/goarch.PtrSize
+		newcap = int(capmem / goarch.PtrSize)
 	case isPowerOfTwo(et.size):
 		var shift uintptr
-		if sys.PtrSize == 8 {
+		if goarch.PtrSize == 8 {
 			// Mask shift for better code generation.
 			shift = uintptr(sys.Ctz64(uint64(et.size))) & 63
 		} else {
@@ -298,7 +300,7 @@
 	size := uintptr(n) * width
 	if raceenabled {
 		callerpc := getcallerpc()
-		pc := funcPC(slicecopy)
+		pc := abi.FuncPCABIInternal(slicecopy)
 		racereadrangepc(fromPtr, size, callerpc, pc)
 		racewriterangepc(toPtr, size, callerpc, pc)
 	}
diff --git a/src/runtime/softfloat64.go b/src/runtime/softfloat64.go
index 13bee6c..084aa13 100644
--- a/src/runtime/softfloat64.go
+++ b/src/runtime/softfloat64.go
@@ -562,36 +562,38 @@
 	return val
 }
 
-func f64touint64(x float64) uint64 {
-	if x < float64(1<<63) {
-		return uint64(int64(x))
+func f64touint64(x uint64) uint64 {
+	var m uint64 = 0x43e0000000000000 // float64 1<<63
+	if fgt64(m, x) {
+		return uint64(f64toint64(x))
 	}
-	y := x - float64(1<<63)
-	z := uint64(int64(y))
+	y := fadd64(x, -m)
+	z := uint64(f64toint64(y))
 	return z | (1 << 63)
 }
 
-func f32touint64(x float32) uint64 {
-	if x < float32(1<<63) {
-		return uint64(int64(x))
+func f32touint64(x uint32) uint64 {
+	var m uint32 = 0x5f000000 // float32 1<<63
+	if fgt32(m, x) {
+		return uint64(f32toint64(x))
 	}
-	y := x - float32(1<<63)
-	z := uint64(int64(y))
+	y := fadd32(x, -m)
+	z := uint64(f32toint64(y))
 	return z | (1 << 63)
 }
 
-func fuint64to64(x uint64) float64 {
+func fuint64to64(x uint64) uint64 {
 	if int64(x) >= 0 {
-		return float64(int64(x))
+		return fint64to64(int64(x))
 	}
-	// See ../cmd/compile/internal/gc/ssa.go:uint64Tofloat
+	// See ../cmd/compile/internal/ssagen/ssa.go:uint64Tofloat
 	y := x & 1
 	z := x >> 1
 	z = z | y
-	r := float64(int64(z))
-	return r + r
+	r := fint64to64(int64(z))
+	return fadd64(r, r)
 }
 
-func fuint64to32(x uint64) float32 {
-	return float32(fuint64to64(x))
+func fuint64to32(x uint64) uint32 {
+	return f64to32(fuint64to64(x))
 }
diff --git a/src/runtime/stack.go b/src/runtime/stack.go
index 6e0d157..54ad66d 100644
--- a/src/runtime/stack.go
+++ b/src/runtime/stack.go
@@ -7,6 +7,8 @@
 import (
 	"internal/abi"
 	"internal/cpu"
+	"internal/goarch"
+	"internal/goos"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -67,7 +69,7 @@
 	// to each stack below the usual guard area for OS-specific
 	// purposes like signal handling. Used on Windows, Plan 9,
 	// and iOS because they do not use a separate stack.
-	_StackSystem = sys.GoosWindows*512*sys.PtrSize + sys.GoosPlan9*512 + sys.GoosIos*sys.GoarchArm64*1024
+	_StackSystem = goos.IsWindows*512*goarch.PtrSize + goos.IsPlan9*512 + goos.IsIos*goarch.IsArm64*1024
 
 	// The minimum size of stack used by Go code
 	_StackMin = 2048
@@ -125,7 +127,7 @@
 )
 
 const (
-	uintptrMask = 1<<(8*sys.PtrSize) - 1
+	uintptrMask = 1<<(8*goarch.PtrSize) - 1
 
 	// The values below can be stored to g.stackguard0 to force
 	// the next stack check to fail.
@@ -599,14 +601,14 @@
 	for i := uintptr(0); i < num; i += 8 {
 		if stackDebug >= 4 {
 			for j := uintptr(0); j < 8; j++ {
-				print("        ", add(scanp, (i+j)*sys.PtrSize), ":", ptrnames[bv.ptrbit(i+j)], ":", hex(*(*uintptr)(add(scanp, (i+j)*sys.PtrSize))), " # ", i, " ", *addb(bv.bytedata, i/8), "\n")
+				print("        ", add(scanp, (i+j)*goarch.PtrSize), ":", ptrnames[bv.ptrbit(i+j)], ":", hex(*(*uintptr)(add(scanp, (i+j)*goarch.PtrSize))), " # ", i, " ", *addb(bv.bytedata, i/8), "\n")
 			}
 		}
 		b := *(addb(bv.bytedata, i/8))
 		for b != 0 {
 			j := uintptr(sys.Ctz8(b))
 			b &= b - 1
-			pp := (*uintptr)(add(scanp, (i+j)*sys.PtrSize))
+			pp := (*uintptr)(add(scanp, (i+j)*goarch.PtrSize))
 		retry:
 			p := *pp
 			if f.valid() && 0 < p && p < minLegalPointer && debug.invalidptr != 0 {
@@ -655,13 +657,13 @@
 
 	// Adjust local variables if stack frame has been allocated.
 	if locals.n > 0 {
-		size := uintptr(locals.n) * sys.PtrSize
+		size := uintptr(locals.n) * goarch.PtrSize
 		adjustpointers(unsafe.Pointer(frame.varp-size), &locals, adjinfo, f)
 	}
 
 	// Adjust saved base pointer if there is one.
 	// TODO what about arm64 frame pointer adjustment?
-	if sys.ArchFamily == sys.AMD64 && frame.argp-frame.varp == 2*sys.PtrSize {
+	if goarch.ArchFamily == goarch.AMD64 && frame.argp-frame.varp == 2*goarch.PtrSize {
 		if stackDebug >= 3 {
 			print("      saved bp\n")
 		}
@@ -710,8 +712,8 @@
 				s = materializeGCProg(ptrdata, gcdata)
 				gcdata = (*byte)(unsafe.Pointer(s.startAddr))
 			}
-			for i := uintptr(0); i < ptrdata; i += sys.PtrSize {
-				if *addb(gcdata, i/(8*sys.PtrSize))>>(i/sys.PtrSize&7)&1 != 0 {
+			for i := uintptr(0); i < ptrdata; i += goarch.PtrSize {
+				if *addb(gcdata, i/(8*goarch.PtrSize))>>(i/goarch.PtrSize&7)&1 != 0 {
 					adjustpointer(adjinfo, unsafe.Pointer(p+i))
 				}
 			}
@@ -753,11 +755,6 @@
 		adjustpointer(adjinfo, unsafe.Pointer(&d.varp))
 		adjustpointer(adjinfo, unsafe.Pointer(&d.fd))
 	}
-
-	// Adjust defer argument blocks the same way we adjust active stack frames.
-	// Note: this code is after the loop above, so that if a defer record is
-	// stack allocated, we work on the copy in the new stack.
-	tracebackdefers(gp, adjustframe, noescape(unsafe.Pointer(adjinfo)))
 }
 
 func adjustpanics(gp *g, adjinfo *adjustinfo) {
@@ -1017,9 +1014,9 @@
 		throw("missing stack in newstack")
 	}
 	sp := gp.sched.sp
-	if sys.ArchFamily == sys.AMD64 || sys.ArchFamily == sys.I386 || sys.ArchFamily == sys.WASM {
+	if goarch.ArchFamily == goarch.AMD64 || goarch.ArchFamily == goarch.I386 || goarch.ArchFamily == goarch.WASM {
 		// The call to morestack cost a word.
-		sp -= sys.PtrSize
+		sp -= goarch.PtrSize
 	}
 	if stackDebug >= 1 || sp < gp.stack.lo {
 		print("runtime: newstack sp=", hex(sp), " stack=[", hex(gp.stack.lo), ", ", hex(gp.stack.hi), "]\n",
@@ -1114,7 +1111,7 @@
 	if fv != nil {
 		fn = unsafe.Pointer(fv.fn)
 	} else {
-		fn = unsafe.Pointer(funcPC(nilfunc))
+		fn = unsafe.Pointer(abi.FuncPCABIInternal(nilfunc))
 	}
 	gostartcall(gobuf, fn, unsafe.Pointer(fv))
 }
@@ -1262,8 +1259,8 @@
 	// Local variables.
 	size := frame.varp - frame.sp
 	var minsize uintptr
-	switch sys.ArchFamily {
-	case sys.ARM64:
+	switch goarch.ArchFamily {
+	case goarch.ARM64:
 		minsize = sys.StackAlign
 	default:
 		minsize = sys.MinFrameSize
@@ -1298,7 +1295,7 @@
 			// In this case, arglen specifies how much of the args section is actually live.
 			// (It could be either all the args + results, or just the args.)
 			args = *frame.argmap
-			n := int32(frame.arglen / sys.PtrSize)
+			n := int32(frame.arglen / goarch.PtrSize)
 			if n < args.n {
 				args.n = n // Don't use more of the arguments than arglen.
 			}
@@ -1320,17 +1317,17 @@
 	}
 
 	// stack objects.
-	if GOARCH == "amd64" && unsafe.Sizeof(abi.RegArgs{}) > 0 && frame.argmap != nil {
+	if (GOARCH == "amd64" || GOARCH == "arm64") && unsafe.Sizeof(abi.RegArgs{}) > 0 && frame.argmap != nil {
 		// argmap is set when the function is reflect.makeFuncStub or reflect.methodValueCall.
 		// We don't actually use argmap in this case, but we need to fake the stack object
-		// record for these frames which contain an internal/abi.RegArgs at a hard-coded offset
-		// on amd64.
+		// record for these frames which contain an internal/abi.RegArgs at a hard-coded offset.
+		// This offset matches the assembly code on amd64 and arm64.
 		objs = methodValueCallFrameObjs
 	} else {
 		p := funcdata(f, _FUNCDATA_StackObjects)
 		if p != nil {
 			n := *(*uintptr)(p)
-			p = add(p, sys.PtrSize)
+			p = add(p, goarch.PtrSize)
 			*(*slice)(unsafe.Pointer(&objs)) = slice{array: noescape(p), len: int(n), cap: int(n)}
 			// Note: the noescape above is needed to keep
 			// getStackMap from "leaking param content:
diff --git a/src/runtime/string.go b/src/runtime/string.go
index d6030a1..d6990da 100644
--- a/src/runtime/string.go
+++ b/src/runtime/string.go
@@ -5,8 +5,9 @@
 package runtime
 
 import (
+	"internal/abi"
 	"internal/bytealg"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -88,14 +89,14 @@
 		racereadrangepc(unsafe.Pointer(ptr),
 			uintptr(n),
 			getcallerpc(),
-			funcPC(slicebytetostring))
+			abi.FuncPCABIInternal(slicebytetostring))
 	}
 	if msanenabled {
 		msanread(unsafe.Pointer(ptr), uintptr(n))
 	}
 	if n == 1 {
 		p := unsafe.Pointer(&staticuint64s[*ptr])
-		if sys.BigEndian {
+		if goarch.BigEndian {
 			p = add(p, 7)
 		}
 		stringStructOf(&str).str = p
@@ -152,7 +153,7 @@
 		racereadrangepc(unsafe.Pointer(ptr),
 			uintptr(n),
 			getcallerpc(),
-			funcPC(slicebytetostringtmp))
+			abi.FuncPCABIInternal(slicebytetostringtmp))
 	}
 	if msanenabled && n > 0 {
 		msanread(unsafe.Pointer(ptr), uintptr(n))
@@ -203,7 +204,7 @@
 		racereadrangepc(unsafe.Pointer(&a[0]),
 			uintptr(len(a))*unsafe.Sizeof(a[0]),
 			getcallerpc(),
-			funcPC(slicerunetostring))
+			abi.FuncPCABIInternal(slicerunetostring))
 	}
 	if msanenabled && len(a) > 0 {
 		msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 16d7583..8a520d7 100644
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -6,6 +6,7 @@
 
 import (
 	"internal/abi"
+	"internal/goarch"
 	"internal/goexperiment"
 	"unsafe"
 )
@@ -176,8 +177,6 @@
 
 func gogo(buf *gobuf)
 
-//go:noescape
-func jmpdefer(fv *funcval, argp uintptr)
 func asminit()
 func setg(gg *g)
 func breakpoint()
@@ -421,12 +420,5 @@
 // structure that is at least large enough to hold the
 // registers the system supports.
 //
-// Currently it's set to zero because using the actual
-// constant will break every part of the toolchain that
-// uses finalizers or Windows callbacks to call functions
-// The value that is currently commented out there should be
-// the actual value once we're ready to use the register ABI
-// everywhere.
-//
 // Protected by finlock.
-var intArgRegs = abi.IntArgRegs * goexperiment.RegabiArgsInt
+var intArgRegs = abi.IntArgRegs * (goexperiment.RegabiArgsInt | goarch.IsAmd64)
diff --git a/src/runtime/stubs_arm64.go b/src/runtime/stubs_arm64.go
index f5e3bb4..bd0533d 100644
--- a/src/runtime/stubs_arm64.go
+++ b/src/runtime/stubs_arm64.go
@@ -14,3 +14,10 @@
 func asmcgocall_no_g(fn, arg unsafe.Pointer)
 
 func emptyfunc()
+
+// Used by reflectcall and the reflect package.
+//
+// Spills/loads arguments in registers to/from an internal/abi.RegArgs
+// respectively. Does not follow the Go ABI.
+func spillArgs()
+func unspillArgs()
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index 999300a..d08aa0b 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -330,7 +331,6 @@
 	funcID_gogo
 	funcID_gopanic
 	funcID_handleAsyncEvent
-	funcID_jmpdefer
 	funcID_mcall
 	funcID_morestack
 	funcID_mstart
@@ -568,7 +568,7 @@
 func moduledataverify1(datap *moduledata) {
 	// Check that the pclntab's format is valid.
 	hdr := datap.pcHeader
-	if hdr.magic != 0xfffffffa || hdr.pad1 != 0 || hdr.pad2 != 0 || hdr.minLC != sys.PCQuantum || hdr.ptrSize != sys.PtrSize {
+	if hdr.magic != 0xfffffffa || hdr.pad1 != 0 || hdr.pad2 != 0 || hdr.minLC != sys.PCQuantum || hdr.ptrSize != goarch.PtrSize {
 		print("runtime: function symbol table header:", hex(hdr.magic), hex(hdr.pad1), hex(hdr.pad2), hex(hdr.minLC), hex(hdr.ptrSize))
 		if datap.pluginpath != "" {
 			print(", plugin:", datap.pluginpath)
@@ -786,7 +786,7 @@
 // For now, align to sys.PtrSize and reduce mod the number of entries.
 // In practice, this appears to be fairly randomly and evenly distributed.
 func pcvalueCacheKey(targetpc uintptr) uintptr {
-	return (targetpc / sys.PtrSize) % uintptr(len(pcvalueCache{}.entries))
+	return (targetpc / goarch.PtrSize) % uintptr(len(pcvalueCache{}.entries))
 }
 
 // Returns the PCData value, and the PC where this value starts.
@@ -955,7 +955,7 @@
 
 func funcspdelta(f funcInfo, targetpc uintptr, cache *pcvalueCache) int32 {
 	x, _ := pcvalue(f, f.pcsp, targetpc, cache, true)
-	if x&(sys.PtrSize-1) != 0 {
+	if x&(goarch.PtrSize-1) != 0 {
 		print("invalid spdelta ", funcname(f), " ", hex(f.entry), " ", hex(targetpc), " ", hex(f.pcsp), " ", x, "\n")
 	}
 	return x
@@ -1014,13 +1014,13 @@
 		return nil
 	}
 	p := add(unsafe.Pointer(&f.nfuncdata), unsafe.Sizeof(f.nfuncdata)+uintptr(f.npcdata)*4)
-	if sys.PtrSize == 8 && uintptr(p)&4 != 0 {
+	if goarch.PtrSize == 8 && uintptr(p)&4 != 0 {
 		if uintptr(unsafe.Pointer(f._func))&4 != 0 {
 			println("runtime: misaligned func", f._func)
 		}
 		p = add(p, 4)
 	}
-	return *(*unsafe.Pointer)(add(p, uintptr(i)*sys.PtrSize))
+	return *(*unsafe.Pointer)(add(p, uintptr(i)*goarch.PtrSize))
 }
 
 // step advances to the next pc, value pair in the encoded table.
diff --git a/src/runtime/sys_darwin_arm64.go b/src/runtime/sys_darwin_arm64.go
index 9c14f33..e6d4c1b 100644
--- a/src/runtime/sys_darwin_arm64.go
+++ b/src/runtime/sys_darwin_arm64.go
@@ -5,7 +5,8 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/abi"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -14,14 +15,14 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func g0_pthread_key_create(k *pthreadkey, destructor uintptr) int32 {
-	return asmcgocall(unsafe.Pointer(funcPC(pthread_key_create_trampoline)), unsafe.Pointer(&k))
+	return asmcgocall(unsafe.Pointer(abi.FuncPCABI0(pthread_key_create_trampoline)), unsafe.Pointer(&k))
 }
 func pthread_key_create_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func g0_pthread_setspecific(k pthreadkey, value uintptr) int32 {
-	return asmcgocall(unsafe.Pointer(funcPC(pthread_setspecific_trampoline)), unsafe.Pointer(&k))
+	return asmcgocall(unsafe.Pointer(abi.FuncPCABI0(pthread_setspecific_trampoline)), unsafe.Pointer(&k))
 }
 func pthread_setspecific_trampoline()
 
@@ -53,7 +54,7 @@
 
 	for i, x := range tlsbase {
 		if x == magic {
-			*tlsg = uintptr(i * sys.PtrSize)
+			*tlsg = uintptr(i * goarch.PtrSize)
 			g0_pthread_setspecific(k, 0)
 			return
 		}
diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index 33cc670..64ddc23 100644
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -215,13 +215,7 @@
 
 	MOVQ	SP, R12	// Save old SP; R12 unchanged by C code.
 
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), BX // BX unchanged by C code.
-#else
-	get_tls(CX)
-	MOVQ	g(CX), AX
-	MOVQ	g_m(AX), BX // BX unchanged by C code.
-#endif
 
 	// Set vdsoPC and vdsoSP for SIGPROF traceback.
 	// Save the old values on stack and restore them on exit,
@@ -236,11 +230,7 @@
 	MOVQ	CX, m_vdsoPC(BX)
 	MOVQ	DX, m_vdsoSP(BX)
 
-#ifdef GOEXPERIMENT_regabig
 	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
-#else
-	CMPQ	AX, m_curg(BX)	// Only switch if on curg.
-#endif
 	JNE	noswitch
 
 	MOVQ	m_g0(BX), DX
@@ -328,9 +318,8 @@
 	POPQ	BP
 	RET
 
-// Defined as ABIInternal since it does not use the stack-based Go ABI.
 // Called using C ABI.
-TEXT runtime·sigtramp<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·sigtramp(SB),NOSPLIT,$0
 	// Transition from C ABI to Go ABI.
 	PUSH_REGS_HOST_TO_ABI0()
 
@@ -348,8 +337,7 @@
 
 // Used instead of sigtramp in programs that use cgo.
 // Arguments from kernel are in DI, SI, DX.
-// Defined as ABIInternal since it does not use the stack-based Go ABI.
-TEXT runtime·cgoSigtramp<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
 	// If no traceback function, do usual sigtramp.
 	MOVQ	runtime·cgoTraceback(SB), AX
 	TESTQ	AX, AX
@@ -392,12 +380,12 @@
 	// The first three arguments, and the fifth, are already in registers.
 	// Set the two remaining arguments now.
 	MOVQ	runtime·cgoTraceback(SB), CX
-	MOVQ	$runtime·sigtramp<ABIInternal>(SB), R9
+	MOVQ	$runtime·sigtramp(SB), R9
 	MOVQ	_cgo_callers(SB), AX
 	JMP	AX
 
 sigtramp:
-	JMP	runtime·sigtramp<ABIInternal>(SB)
+	JMP	runtime·sigtramp(SB)
 
 sigtrampnog:
 	// Signal arrived on a non-Go thread. If this is SIGPROF, get a
@@ -428,8 +416,7 @@
 // https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/x86_64/sigaction.c
 // The code that cares about the precise instructions used is:
 // https://gcc.gnu.org/viewcvs/gcc/trunk/libgcc/config/i386/linux-unwind.h?revision=219188&view=markup
-// Defined as ABIInternal since it does not use the stack-based Go ABI.
-TEXT runtime·sigreturn<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·sigreturn(SB),NOSPLIT,$0
 	MOVQ	$SYS_rt_sigreturn, AX
 	SYSCALL
 	INT $3	// not reached
diff --git a/src/runtime/sys_openbsd.go b/src/runtime/sys_openbsd.go
index ab31495..1588861 100644
--- a/src/runtime/sys_openbsd.go
+++ b/src/runtime/sys_openbsd.go
@@ -7,7 +7,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 // The *_trampoline functions convert from the Go calling convention to the C calling convention
 // and then call the underlying libc function. These are defined in sys_openbsd_$ARCH.s.
@@ -15,35 +18,35 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_attr_init(attr *pthreadattr) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_attr_init_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_attr_init_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_attr_init_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_attr_destroy(attr *pthreadattr) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_attr_destroy_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_attr_destroy_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_attr_destroy_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_attr_getstacksize(attr *pthreadattr, size *uintptr) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_attr_getstacksize_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_attr_getstacksize_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_attr_getstacksize_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_attr_setdetachstate(attr *pthreadattr, state int) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_attr_setdetachstate_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_attr_setdetachstate_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_attr_setdetachstate_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func pthread_create(attr *pthreadattr, start uintptr, arg unsafe.Pointer) int32 {
-	return libcCall(unsafe.Pointer(funcPC(pthread_create_trampoline)), unsafe.Pointer(&attr))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(pthread_create_trampoline)), unsafe.Pointer(&attr))
 }
 func pthread_create_trampoline()
 
diff --git a/src/runtime/sys_openbsd1.go b/src/runtime/sys_openbsd1.go
index cb5d358..b4e9f54 100644
--- a/src/runtime/sys_openbsd1.go
+++ b/src/runtime/sys_openbsd1.go
@@ -7,31 +7,34 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 //go:nosplit
 //go:cgo_unsafe_args
 func thrsleep(ident uintptr, clock_id int32, tsp *timespec, lock uintptr, abort *uint32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(thrsleep_trampoline)), unsafe.Pointer(&ident))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(thrsleep_trampoline)), unsafe.Pointer(&ident))
 }
 func thrsleep_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func thrwakeup(ident uintptr, n int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(thrwakeup_trampoline)), unsafe.Pointer(&ident))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(thrwakeup_trampoline)), unsafe.Pointer(&ident))
 }
 func thrwakeup_trampoline()
 
 //go:nosplit
 func osyield() {
-	libcCall(unsafe.Pointer(funcPC(sched_yield_trampoline)), unsafe.Pointer(nil))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(sched_yield_trampoline)), unsafe.Pointer(nil))
 }
 func sched_yield_trampoline()
 
 //go:nosplit
 func osyield_no_g() {
-	asmcgocall_no_g(unsafe.Pointer(funcPC(sched_yield_trampoline)), unsafe.Pointer(nil))
+	asmcgocall_no_g(unsafe.Pointer(abi.FuncPCABI0(sched_yield_trampoline)), unsafe.Pointer(nil))
 }
 
 //go:cgo_import_dynamic libc_thrsleep __thrsleep "libc.so"
diff --git a/src/runtime/sys_openbsd2.go b/src/runtime/sys_openbsd2.go
index cd1a4e8..190ee47 100644
--- a/src/runtime/sys_openbsd2.go
+++ b/src/runtime/sys_openbsd2.go
@@ -7,21 +7,24 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 // This is exported via linkname to assembly in runtime/cgo.
 //go:linkname exit
 //go:nosplit
 //go:cgo_unsafe_args
 func exit(code int32) {
-	libcCall(unsafe.Pointer(funcPC(exit_trampoline)), unsafe.Pointer(&code))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(exit_trampoline)), unsafe.Pointer(&code))
 }
 func exit_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func getthrid() (tid int32) {
-	libcCall(unsafe.Pointer(funcPC(getthrid_trampoline)), unsafe.Pointer(&tid))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(getthrid_trampoline)), unsafe.Pointer(&tid))
 	return
 }
 func getthrid_trampoline()
@@ -29,14 +32,14 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func raiseproc(sig uint32) {
-	libcCall(unsafe.Pointer(funcPC(raiseproc_trampoline)), unsafe.Pointer(&sig))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(raiseproc_trampoline)), unsafe.Pointer(&sig))
 }
 func raiseproc_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func thrkill(tid int32, sig int) {
-	libcCall(unsafe.Pointer(funcPC(thrkill_trampoline)), unsafe.Pointer(&tid))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(thrkill_trampoline)), unsafe.Pointer(&tid))
 }
 func thrkill_trampoline()
 
@@ -53,7 +56,7 @@
 		ret1            unsafe.Pointer
 		ret2            int
 	}{addr, n, prot, flags, fd, off, nil, 0}
-	libcCall(unsafe.Pointer(funcPC(mmap_trampoline)), unsafe.Pointer(&args))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(mmap_trampoline)), unsafe.Pointer(&args))
 	return args.ret1, args.ret2
 }
 func mmap_trampoline()
@@ -61,42 +64,42 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func munmap(addr unsafe.Pointer, n uintptr) {
-	libcCall(unsafe.Pointer(funcPC(munmap_trampoline)), unsafe.Pointer(&addr))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(munmap_trampoline)), unsafe.Pointer(&addr))
 }
 func munmap_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func madvise(addr unsafe.Pointer, n uintptr, flags int32) {
-	libcCall(unsafe.Pointer(funcPC(madvise_trampoline)), unsafe.Pointer(&addr))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(madvise_trampoline)), unsafe.Pointer(&addr))
 }
 func madvise_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func open(name *byte, mode, perm int32) (ret int32) {
-	return libcCall(unsafe.Pointer(funcPC(open_trampoline)), unsafe.Pointer(&name))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(open_trampoline)), unsafe.Pointer(&name))
 }
 func open_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func closefd(fd int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(close_trampoline)), unsafe.Pointer(&fd))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(close_trampoline)), unsafe.Pointer(&fd))
 }
 func close_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func read(fd int32, p unsafe.Pointer, n int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(read_trampoline)), unsafe.Pointer(&fd))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(read_trampoline)), unsafe.Pointer(&fd))
 }
 func read_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func write1(fd uintptr, p unsafe.Pointer, n int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(write_trampoline)), unsafe.Pointer(&fd))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(write_trampoline)), unsafe.Pointer(&fd))
 }
 func write_trampoline()
 
@@ -110,7 +113,7 @@
 		p     unsafe.Pointer
 		flags int32
 	}{noescape(unsafe.Pointer(&p)), flags}
-	errno = libcCall(unsafe.Pointer(funcPC(pipe2_trampoline)), unsafe.Pointer(&args))
+	errno = libcCall(unsafe.Pointer(abi.FuncPCABI0(pipe2_trampoline)), unsafe.Pointer(&args))
 	return p[0], p[1], errno
 }
 func pipe2_trampoline()
@@ -118,34 +121,34 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func setitimer(mode int32, new, old *itimerval) {
-	libcCall(unsafe.Pointer(funcPC(setitimer_trampoline)), unsafe.Pointer(&mode))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(setitimer_trampoline)), unsafe.Pointer(&mode))
 }
 func setitimer_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func usleep(usec uint32) {
-	libcCall(unsafe.Pointer(funcPC(usleep_trampoline)), unsafe.Pointer(&usec))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(usleep_trampoline)), unsafe.Pointer(&usec))
 }
 func usleep_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func usleep_no_g(usec uint32) {
-	asmcgocall_no_g(unsafe.Pointer(funcPC(usleep_trampoline)), unsafe.Pointer(&usec))
+	asmcgocall_no_g(unsafe.Pointer(abi.FuncPCABI0(usleep_trampoline)), unsafe.Pointer(&usec))
 }
 
 //go:nosplit
 //go:cgo_unsafe_args
 func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, ndst uintptr) int32 {
-	return libcCall(unsafe.Pointer(funcPC(sysctl_trampoline)), unsafe.Pointer(&mib))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(sysctl_trampoline)), unsafe.Pointer(&mib))
 }
 func sysctl_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func fcntl(fd, cmd, arg int32) int32 {
-	return libcCall(unsafe.Pointer(funcPC(fcntl_trampoline)), unsafe.Pointer(&fd))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(fcntl_trampoline)), unsafe.Pointer(&fd))
 }
 func fcntl_trampoline()
 
@@ -156,7 +159,7 @@
 		clock_id int32
 		tp       unsafe.Pointer
 	}{_CLOCK_MONOTONIC, unsafe.Pointer(&ts)}
-	libcCall(unsafe.Pointer(funcPC(clock_gettime_trampoline)), unsafe.Pointer(&args))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args))
 	return ts.tv_sec*1e9 + int64(ts.tv_nsec)
 }
 func clock_gettime_trampoline()
@@ -168,42 +171,42 @@
 		clock_id int32
 		tp       unsafe.Pointer
 	}{_CLOCK_REALTIME, unsafe.Pointer(&ts)}
-	libcCall(unsafe.Pointer(funcPC(clock_gettime_trampoline)), unsafe.Pointer(&args))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args))
 	return ts.tv_sec, int32(ts.tv_nsec)
 }
 
 //go:nosplit
 //go:cgo_unsafe_args
 func kqueue() int32 {
-	return libcCall(unsafe.Pointer(funcPC(kqueue_trampoline)), nil)
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(kqueue_trampoline)), nil)
 }
 func kqueue_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func kevent(kq int32, ch *keventt, nch int32, ev *keventt, nev int32, ts *timespec) int32 {
-	return libcCall(unsafe.Pointer(funcPC(kevent_trampoline)), unsafe.Pointer(&kq))
+	return libcCall(unsafe.Pointer(abi.FuncPCABI0(kevent_trampoline)), unsafe.Pointer(&kq))
 }
 func kevent_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func sigaction(sig uint32, new *sigactiont, old *sigactiont) {
-	libcCall(unsafe.Pointer(funcPC(sigaction_trampoline)), unsafe.Pointer(&sig))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(sigaction_trampoline)), unsafe.Pointer(&sig))
 }
 func sigaction_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func sigprocmask(how uint32, new *sigset, old *sigset) {
-	libcCall(unsafe.Pointer(funcPC(sigprocmask_trampoline)), unsafe.Pointer(&how))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(sigprocmask_trampoline)), unsafe.Pointer(&how))
 }
 func sigprocmask_trampoline()
 
 //go:nosplit
 //go:cgo_unsafe_args
 func sigaltstack(new *stackt, old *stackt) {
-	libcCall(unsafe.Pointer(funcPC(sigaltstack_trampoline)), unsafe.Pointer(&new))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(sigaltstack_trampoline)), unsafe.Pointer(&new))
 }
 func sigaltstack_trampoline()
 
diff --git a/src/runtime/sys_openbsd3.go b/src/runtime/sys_openbsd3.go
index 8d77a4b..a917ebd 100644
--- a/src/runtime/sys_openbsd3.go
+++ b/src/runtime/sys_openbsd3.go
@@ -7,7 +7,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 // The X versions of syscall expect the libc call to return a 64-bit result.
 // Otherwise (the non-X version) expects a 32-bit result.
@@ -20,7 +23,7 @@
 //go:cgo_unsafe_args
 func syscall_syscall(fn, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -31,7 +34,7 @@
 //go:cgo_unsafe_args
 func syscall_syscallX(fn, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscallX)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscallX)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -42,7 +45,7 @@
 //go:cgo_unsafe_args
 func syscall_syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall6)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall6)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -53,7 +56,7 @@
 //go:cgo_unsafe_args
 func syscall_syscall6X(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall6X)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall6X)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -64,7 +67,7 @@
 //go:cgo_unsafe_args
 func syscall_syscall10(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall10)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall10)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -75,7 +78,7 @@
 //go:cgo_unsafe_args
 func syscall_syscall10X(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10 uintptr) (r1, r2, err uintptr) {
 	entersyscall()
-	libcCall(unsafe.Pointer(funcPC(syscall10X)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall10X)), unsafe.Pointer(&fn))
 	exitsyscall()
 	return
 }
@@ -85,7 +88,7 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func syscall_rawSyscall(fn, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
-	libcCall(unsafe.Pointer(funcPC(syscall)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall)), unsafe.Pointer(&fn))
 	return
 }
 
@@ -93,7 +96,7 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func syscall_rawSyscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
-	libcCall(unsafe.Pointer(funcPC(syscall6)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall6)), unsafe.Pointer(&fn))
 	return
 }
 
@@ -101,7 +104,7 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func syscall_rawSyscall6X(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
-	libcCall(unsafe.Pointer(funcPC(syscall6X)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall6X)), unsafe.Pointer(&fn))
 	return
 }
 
@@ -109,6 +112,6 @@
 //go:nosplit
 //go:cgo_unsafe_args
 func syscall_rawSyscall10X(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10 uintptr) (r1, r2, err uintptr) {
-	libcCall(unsafe.Pointer(funcPC(syscall10X)), unsafe.Pointer(&fn))
+	libcCall(unsafe.Pointer(abi.FuncPCABI0(syscall10X)), unsafe.Pointer(&fn))
 	return
 }
diff --git a/src/runtime/sys_openbsd_amd64.s b/src/runtime/sys_openbsd_amd64.s
index 522e98c..fc89ee6 100644
--- a/src/runtime/sys_openbsd_amd64.s
+++ b/src/runtime/sys_openbsd_amd64.s
@@ -58,7 +58,7 @@
 	RET
 
 // Called using C ABI.
-TEXT runtime·sigtramp<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·sigtramp(SB),NOSPLIT,$0
 	// Transition from C ABI to Go ABI.
 	PUSH_REGS_HOST_TO_ABI0()
 
diff --git a/src/runtime/sys_plan9_386.s b/src/runtime/sys_plan9_386.s
index b3d2f13..bdcb98e 100644
--- a/src/runtime/sys_plan9_386.s
+++ b/src/runtime/sys_plan9_386.s
@@ -250,3 +250,7 @@
 	MOVL	0(SP), AX
 	MOVL	AX, ret_base+0(FP)
 	RET
+
+// never called on this platform
+TEXT ·sigpanictramp(SB),NOSPLIT,$0-0
+	UNDEF
diff --git a/src/runtime/sys_plan9_amd64.s b/src/runtime/sys_plan9_amd64.s
index 731306a..39fc4c6 100644
--- a/src/runtime/sys_plan9_amd64.s
+++ b/src/runtime/sys_plan9_amd64.s
@@ -251,3 +251,7 @@
 	MOVQ	0(SP), AX
 	MOVQ	AX, ret_base+0(FP)
 	RET
+
+// never called on this platform
+TEXT ·sigpanictramp(SB),NOSPLIT,$0-0
+	UNDEF
diff --git a/src/runtime/sys_wasm.go b/src/runtime/sys_wasm.go
index 057ed4c..e6e7f47 100644
--- a/src/runtime/sys_wasm.go
+++ b/src/runtime/sys_wasm.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -30,7 +31,7 @@
 // and then stopped before the first instruction in fn.
 func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
 	sp := buf.sp
-	sp -= sys.PtrSize
+	sp -= goarch.PtrSize
 	*(*uintptr)(unsafe.Pointer(sp)) = buf.pc
 	buf.sp = sp
 	buf.pc = uintptr(fn)
diff --git a/src/runtime/sys_windows_386.s b/src/runtime/sys_windows_386.s
index 0b39335..cf3a439 100644
--- a/src/runtime/sys_windows_386.s
+++ b/src/runtime/sys_windows_386.s
@@ -8,7 +8,7 @@
 #include "time_windows.h"
 
 // void runtime·asmstdcall(void *c);
-TEXT runtime·asmstdcall<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·asmstdcall(SB),NOSPLIT,$0
 	MOVL	fn+0(FP), BX
 
 	// SetLastError(0).
@@ -147,21 +147,21 @@
 	BYTE $0xC2; WORD $4
 	RET // unreached; make assembler happy
 
-TEXT runtime·exceptiontramp<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·exceptiontramp(SB),NOSPLIT,$0
 	MOVL	$runtime·exceptionhandler(SB), AX
 	JMP	sigtramp<>(SB)
 
-TEXT runtime·firstcontinuetramp<ABIInternal>(SB),NOSPLIT,$0-0
+TEXT runtime·firstcontinuetramp(SB),NOSPLIT,$0-0
 	// is never called
 	INT	$3
 
-TEXT runtime·lastcontinuetramp<ABIInternal>(SB),NOSPLIT,$0-0
+TEXT runtime·lastcontinuetramp(SB),NOSPLIT,$0-0
 	MOVL	$runtime·lastcontinuehandler(SB), AX
 	JMP	sigtramp<>(SB)
 
 GLOBL runtime·cbctxts(SB), NOPTR, $4
 
-TEXT runtime·callbackasm1<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·callbackasm1(SB),NOSPLIT,$0
   	MOVL	0(SP), AX	// will use to find our callback context
 
 	// remove return address from stack, we are not returning to callbackasm, but to its caller.
@@ -180,7 +180,7 @@
 	CLD
 
 	// determine index into runtime·cbs table
-	SUBL	$runtime·callbackasm<ABIInternal>(SB), AX
+	SUBL	$runtime·callbackasm(SB), AX
 	MOVL	$0, DX
 	MOVL	$5, BX	// divide by 5 because each call instruction in runtime·callbacks is 5 bytes long
 	DIVL	BX
@@ -250,7 +250,7 @@
 	RET
 
 // uint32 tstart_stdcall(M *newm);
-TEXT runtime·tstart_stdcall<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·tstart_stdcall(SB),NOSPLIT,$0
 	MOVL	newm+0(FP), BX
 
 	PUSHL	BX
diff --git a/src/runtime/sys_windows_amd64.s b/src/runtime/sys_windows_amd64.s
index e778284..6cc5bba 100644
--- a/src/runtime/sys_windows_amd64.s
+++ b/src/runtime/sys_windows_amd64.s
@@ -13,7 +13,7 @@
 #define maxargs 18
 
 // void runtime·asmstdcall(void *c);
-TEXT runtime·asmstdcall<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
 	// asmcgocall will put first argument into CX.
 	PUSHQ	CX			// save for later
 	MOVQ	libcall_fn(CX), AX
@@ -179,15 +179,15 @@
 
 	RET
 
-TEXT runtime·exceptiontramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
 	MOVQ	$runtime·exceptionhandler(SB), AX
 	JMP	sigtramp<>(SB)
 
-TEXT runtime·firstcontinuetramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
 	MOVQ	$runtime·firstcontinuehandler(SB), AX
 	JMP	sigtramp<>(SB)
 
-TEXT runtime·lastcontinuetramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
+TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0-0
 	MOVQ	$runtime·lastcontinuehandler(SB), AX
 	JMP	sigtramp<>(SB)
 
@@ -212,7 +212,7 @@
 	ADDQ	$8, SP
 
 	// determine index into runtime·cbs table
-	MOVQ	$runtime·callbackasm<ABIInternal>(SB), DX
+	MOVQ	$runtime·callbackasm(SB), DX
 	SUBQ	DX, AX
 	MOVQ	$0, DX
 	MOVQ	$5, CX	// divide by 5 because each call instruction in runtime·callbacks is 5 bytes long
@@ -245,7 +245,7 @@
 	RET
 
 // uint32 tstart_stdcall(M *newm);
-TEXT runtime·tstart_stdcall<ABIInternal>(SB),NOSPLIT,$0
+TEXT runtime·tstart_stdcall(SB),NOSPLIT,$0
 	// Switch from the host ABI to the Go ABI.
 	PUSH_REGS_HOST_TO_ABI0()
 
diff --git a/src/runtime/sys_windows_arm.s b/src/runtime/sys_windows_arm.s
index 48f8c7d..c9e96cb 100644
--- a/src/runtime/sys_windows_arm.s
+++ b/src/runtime/sys_windows_arm.s
@@ -10,7 +10,7 @@
 // Note: For system ABI, R0-R3 are args, R4-R11 are callee-save.
 
 // void runtime·asmstdcall(void *c);
-TEXT runtime·asmstdcall<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
 	MOVM.DB.W [R4, R5, R14], (R13)	// push {r4, r5, lr}
 	MOVW	R0, R4			// put libcall * in r4
 	MOVW	R13, R5			// save stack pointer in r5
@@ -222,21 +222,21 @@
 	MOVW	R0, R13
 	B	(R1)
 
-TEXT runtime·exceptiontramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
 	MOVW	$runtime·exceptionhandler(SB), R1
 	B	sigtramp<>(SB)
 
-TEXT runtime·firstcontinuetramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0
 	MOVW	$runtime·firstcontinuehandler(SB), R1
 	B	sigtramp<>(SB)
 
-TEXT runtime·lastcontinuetramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0
 	MOVW	$runtime·lastcontinuehandler(SB), R1
 	B	sigtramp<>(SB)
 
 GLOBL runtime·cbctxts(SB), NOPTR, $4
 
-TEXT runtime·callbackasm1<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm1(SB),NOSPLIT|NOFRAME,$0
 	// On entry, the trampoline in zcallback_windows_arm.s left
 	// the callback index in R12 (which is volatile in the C ABI).
 
@@ -275,7 +275,7 @@
 	B	(R12)	// return
 
 // uint32 tstart_stdcall(M *newm);
-TEXT runtime·tstart_stdcall<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·tstart_stdcall(SB),NOSPLIT|NOFRAME,$0
 	MOVM.DB.W [R4-R11, R14], (R13)		// push {r4-r11, lr}
 
 	MOVW	m_g0(R0), g
diff --git a/src/runtime/sys_windows_arm64.s b/src/runtime/sys_windows_arm64.s
index 7a2e11f..44145c5 100644
--- a/src/runtime/sys_windows_arm64.s
+++ b/src/runtime/sys_windows_arm64.s
@@ -18,7 +18,7 @@
 // load_g and save_g (in tls_arm64.s) clobber R27 (REGTMP) and R0.
 
 // void runtime·asmstdcall(void *c);
-TEXT runtime·asmstdcall<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
 	STP.W	(R29, R30), -32(RSP)	// allocate C ABI stack frame
 	STP	(R19, R20), 16(RSP) // save old R19, R20
 	MOVD	R0, R19	// save libcall pointer
@@ -290,21 +290,21 @@
 	MOVD	R0, RSP
 	B	(R1)
 
-TEXT runtime·exceptiontramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
-	MOVD	$runtime·exceptionhandler<ABIInternal>(SB), R1
+TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
+	MOVD	$runtime·exceptionhandler(SB), R1
 	B	sigtramp<>(SB)
 
-TEXT runtime·firstcontinuetramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
-	MOVD	$runtime·firstcontinuehandler<ABIInternal>(SB), R1
+TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0
+	MOVD	$runtime·firstcontinuehandler(SB), R1
 	B	sigtramp<>(SB)
 
 TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0
-	MOVD	$runtime·lastcontinuehandler<ABIInternal>(SB), R1
+	MOVD	$runtime·lastcontinuehandler(SB), R1
 	B	sigtramp<>(SB)
 
 GLOBL runtime·cbctxts(SB), NOPTR, $4
 
-TEXT runtime·callbackasm1<ABIInternal>(SB),NOSPLIT,$208-0
+TEXT runtime·callbackasm1(SB),NOSPLIT,$208-0
 	NO_LOCAL_POINTERS
 
 	// On entry, the trampoline in zcallback_windows_arm64.s left
@@ -339,7 +339,7 @@
 	MOVD	R0, callbackArgs_result(R13)	// result
 
 	// Call cgocallback, which will call callbackWrap(frame).
-	MOVD	$·callbackWrap(SB), R0	// PC of function to call
+	MOVD	$·callbackWrap<ABIInternal>(SB), R0	// PC of function to call, cgocallback takes an ABIInternal entry-point
 	MOVD	R13, R1	// frame (&callbackArgs{...})
 	MOVD	$0, R2	// context
 	MOVD	R0, (1*8)(RSP)
@@ -356,7 +356,7 @@
 	RET
 
 // uint32 tstart_stdcall(M *newm);
-TEXT runtime·tstart_stdcall<ABIInternal>(SB),NOSPLIT,$96-0
+TEXT runtime·tstart_stdcall(SB),NOSPLIT,$96-0
 	SAVE_R19_TO_R28(-10*8)
 
 	MOVD	m_g0(R0), g
diff --git a/src/runtime/sys_x86.go b/src/runtime/sys_x86.go
index 0866e31..856c73a 100644
--- a/src/runtime/sys_x86.go
+++ b/src/runtime/sys_x86.go
@@ -8,7 +8,7 @@
 package runtime
 
 import (
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -16,7 +16,7 @@
 // and then stopped before the first instruction in fn.
 func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
 	sp := buf.sp
-	sp -= sys.PtrSize
+	sp -= goarch.PtrSize
 	*(*uintptr)(unsafe.Pointer(sp)) = buf.pc
 	buf.sp = sp
 	buf.pc = uintptr(fn)
diff --git a/src/runtime/syscall_solaris.go b/src/runtime/syscall_solaris.go
index 0945169..15be8e1c 100644
--- a/src/runtime/syscall_solaris.go
+++ b/src/runtime/syscall_solaris.go
@@ -35,6 +35,7 @@
 
 //go:nosplit
 //go:linkname syscall_sysvicall6
+//go:cgo_unsafe_args
 func syscall_sysvicall6(fn, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
 	call := libcall{
 		fn:   fn,
@@ -49,6 +50,7 @@
 
 //go:nosplit
 //go:linkname syscall_rawsysvicall6
+//go:cgo_unsafe_args
 func syscall_rawsysvicall6(fn, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
 	call := libcall{
 		fn:   fn,
@@ -104,6 +106,7 @@
 
 //go:nosplit
 //go:linkname syscall_execve
+//go:cgo_unsafe_args
 func syscall_execve(path, argv, envp uintptr) (err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_execve)),
@@ -123,6 +126,7 @@
 
 //go:nosplit
 //go:linkname syscall_fcntl
+//go:cgo_unsafe_args
 func syscall_fcntl(fd, cmd, arg uintptr) (val, err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_fcntl)),
@@ -181,6 +185,7 @@
 
 //go:nosplit
 //go:linkname syscall_ioctl
+//go:cgo_unsafe_args
 func syscall_ioctl(fd, req, arg uintptr) (err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_ioctl)),
@@ -234,6 +239,7 @@
 
 //go:nosplit
 //go:linkname syscall_setgroups
+//go:cgo_unsafe_args
 func syscall_setgroups(ngid, gid uintptr) (err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_setgroups)),
@@ -270,6 +276,7 @@
 
 //go:nosplit
 //go:linkname syscall_setpgid
+//go:cgo_unsafe_args
 func syscall_setpgid(pid, pgid uintptr) (err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_setpgid)),
@@ -281,6 +288,7 @@
 }
 
 //go:linkname syscall_syscall
+//go:cgo_unsafe_args
 func syscall_syscall(trap, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_syscall)),
@@ -294,6 +302,7 @@
 }
 
 //go:linkname syscall_wait4
+//go:cgo_unsafe_args
 func syscall_wait4(pid uintptr, wstatus *uint32, options uintptr, rusage unsafe.Pointer) (wpid int, err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_wait4)),
@@ -308,6 +317,7 @@
 
 //go:nosplit
 //go:linkname syscall_write
+//go:cgo_unsafe_args
 func syscall_write(fd, buf, nbyte uintptr) (n, err uintptr) {
 	call := libcall{
 		fn:   uintptr(unsafe.Pointer(&libc_write)),
diff --git a/src/runtime/syscall_windows.go b/src/runtime/syscall_windows.go
index 4763a44..e872d74 100644
--- a/src/runtime/syscall_windows.go
+++ b/src/runtime/syscall_windows.go
@@ -6,7 +6,7 @@
 
 import (
 	"internal/abi"
-	"runtime/internal/sys"
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -73,7 +73,7 @@
 }
 
 func (p *abiDesc) assignArg(t *_type) {
-	if t.size > sys.PtrSize {
+	if t.size > goarch.PtrSize {
 		// We don't support this right now. In
 		// stdcall/cdecl, 64-bit ints and doubles are
 		// passed as two words (little endian); and
@@ -146,7 +146,7 @@
 
 	// cdecl, stdcall, fastcall, and arm pad arguments to word size.
 	// TODO(rsc): On arm and arm64 do we need to skip the caller's saved LR?
-	p.srcStackSize += sys.PtrSize
+	p.srcStackSize += goarch.PtrSize
 }
 
 // tryRegAssignArg tries to register-assign a value of type t.
@@ -162,7 +162,7 @@
 		return p.assignReg(t.size, offset)
 	case kindInt64, kindUint64:
 		// Only register-assign if the registers are big enough.
-		if sys.PtrSize == 8 {
+		if goarch.PtrSize == 8 {
 			return p.assignReg(t.size, offset)
 		}
 	case kindArray:
@@ -232,10 +232,10 @@
 		// followed by a branch instruction
 		entrySize = 8
 	}
-	return funcPC(callbackasm) + uintptr(i*entrySize)
+	return abi.FuncPCABI0(callbackasm) + uintptr(i*entrySize)
 }
 
-const callbackMaxFrame = 64 * sys.PtrSize
+const callbackMaxFrame = 64 * goarch.PtrSize
 
 // compileCallback converts a Go function fn into a C function pointer
 // that can be passed to Windows APIs.
@@ -263,13 +263,13 @@
 	}
 	// The Go ABI aligns the result to the word size. src is
 	// already aligned.
-	abiMap.dstStackSize = alignUp(abiMap.dstStackSize, sys.PtrSize)
+	abiMap.dstStackSize = alignUp(abiMap.dstStackSize, goarch.PtrSize)
 	abiMap.retOffset = abiMap.dstStackSize
 
 	if len(ft.out()) != 1 {
 		panic("compileCallback: expected function with one uintptr-sized result")
 	}
-	if ft.out()[0].size != sys.PtrSize {
+	if ft.out()[0].size != goarch.PtrSize {
 		panic("compileCallback: expected function with one uintptr-sized result")
 	}
 	if k := ft.out()[0].kind & kindMask; k == kindFloat32 || k == kindFloat64 {
@@ -282,12 +282,12 @@
 		// Make room for the uintptr-sized result.
 		// If there are argument registers, the return value will
 		// be passed in the first register.
-		abiMap.dstStackSize += sys.PtrSize
+		abiMap.dstStackSize += goarch.PtrSize
 	}
 
 	// TODO(mknyszek): Remove dstSpill from this calculation when we no longer have
 	// caller reserved spill space.
-	frameSize := alignUp(abiMap.dstStackSize, sys.PtrSize)
+	frameSize := alignUp(abiMap.dstStackSize, goarch.PtrSize)
 	frameSize += abiMap.dstSpill
 	if frameSize > callbackMaxFrame {
 		panic("compileCallback: function argument frame too large")
@@ -370,7 +370,7 @@
 
 	// TODO(mknyszek): Remove this when we no longer have
 	// caller reserved spill space.
-	frameSize := alignUp(c.abiMap.dstStackSize, sys.PtrSize)
+	frameSize := alignUp(c.abiMap.dstStackSize, goarch.PtrSize)
 	frameSize += c.abiMap.dstSpill
 
 	// Even though this is copying back results, we can pass a nil
diff --git a/src/runtime/time.go b/src/runtime/time.go
index 666b242..ad267c3 100644
--- a/src/runtime/time.go
+++ b/src/runtime/time.go
@@ -7,6 +7,7 @@
 package runtime
 
 import (
+	"internal/abi"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -819,7 +820,7 @@
 	if raceenabled {
 		ppcur := getg().m.p.ptr()
 		if ppcur.timerRaceCtx == 0 {
-			ppcur.timerRaceCtx = racegostart(funcPC(runtimer) + sys.PCQuantum)
+			ppcur.timerRaceCtx = racegostart(abi.FuncPCABIInternal(runtimer) + sys.PCQuantum)
 		}
 		raceacquirectx(ppcur.timerRaceCtx, unsafe.Pointer(t))
 	}
diff --git a/src/runtime/time_linux_amd64.s b/src/runtime/time_linux_amd64.s
index 0dd7919..c88e92b 100644
--- a/src/runtime/time_linux_amd64.s
+++ b/src/runtime/time_linux_amd64.s
@@ -15,13 +15,7 @@
 TEXT time·now(SB),NOSPLIT,$16-24
 	MOVQ	SP, R12 // Save old SP; R12 unchanged by C code.
 
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), BX // BX unchanged by C code.
-#else
-	get_tls(CX)
-	MOVQ	g(CX), AX
-	MOVQ	g_m(AX), BX // BX unchanged by C code.
-#endif
 
 	// Store CLOCK_REALTIME results directly to return space.
 	LEAQ	sec+0(FP), SI
@@ -38,11 +32,7 @@
 	MOVQ	CX, m_vdsoPC(BX)
 	MOVQ	SI, m_vdsoSP(BX)
 
-#ifdef GOEXPERIMENT_regabig
 	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
-#else
-	CMPQ	AX, m_curg(BX)	// Only switch if on curg.
-#endif
 	JNE	noswitch
 
 	MOVQ	m_g0(BX), DX
diff --git a/src/runtime/trace.go b/src/runtime/trace.go
index 1530178..00544e4 100644
--- a/src/runtime/trace.go
+++ b/src/runtime/trace.go
@@ -13,6 +13,7 @@
 package runtime
 
 import (
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -85,7 +86,7 @@
 	// and ppc64le.
 	// Tracing won't work reliably for architectures where cputicks is emulated
 	// by nanotime, so the value doesn't matter for those architectures.
-	traceTickDiv = 16 + 48*(sys.Goarch386|sys.GoarchAmd64)
+	traceTickDiv = 16 + 48*(goarch.Is386|goarch.IsAmd64)
 	// Maximum number of PCs in a single stack trace.
 	// Since events contain only stack id rather than whole stack trace,
 	// we can allow quite large values here.
@@ -829,7 +830,7 @@
 
 // newStack allocates a new stack of size n.
 func (tab *traceStackTable) newStack(n int) *traceStack {
-	return (*traceStack)(tab.mem.alloc(unsafe.Sizeof(traceStack{}) + uintptr(n)*sys.PtrSize))
+	return (*traceStack)(tab.mem.alloc(unsafe.Sizeof(traceStack{}) + uintptr(n)*goarch.PtrSize))
 }
 
 // allFrames returns all of the Frames corresponding to pcs.
@@ -929,7 +930,7 @@
 //go:notinheap
 type traceAllocBlock struct {
 	next traceAllocBlockPtr
-	data [64<<10 - sys.PtrSize]byte
+	data [64<<10 - goarch.PtrSize]byte
 }
 
 // TODO: Since traceAllocBlock is now go:notinheap, this isn't necessary.
@@ -940,7 +941,7 @@
 
 // alloc allocates n-byte block.
 func (a *traceAlloc) alloc(n uintptr) unsafe.Pointer {
-	n = alignUp(n, sys.PtrSize)
+	n = alignUp(n, goarch.PtrSize)
 	if a.head == 0 || a.off+n > uintptr(len(a.head.ptr().data)) {
 		if n > uintptr(len(a.head.ptr().data)) {
 			throw("trace: alloc too large")
diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go
index 814c323..addfa6f 100644
--- a/src/runtime/traceback.go
+++ b/src/runtime/traceback.go
@@ -6,6 +6,7 @@
 
 import (
 	"internal/bytealg"
+	"internal/goarch"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -21,41 +22,6 @@
 
 const usesLR = sys.MinFrameSize > 0
 
-// Traceback over the deferred function calls.
-// Report them like calls that have been invoked but not started executing yet.
-func tracebackdefers(gp *g, callback func(*stkframe, unsafe.Pointer) bool, v unsafe.Pointer) {
-	var frame stkframe
-	for d := gp._defer; d != nil; d = d.link {
-		fn := d.fn
-		if fn == nil {
-			// Defer of nil function. Args don't matter.
-			frame.pc = 0
-			frame.fn = funcInfo{}
-			frame.argp = 0
-			frame.arglen = 0
-			frame.argmap = nil
-		} else {
-			frame.pc = fn.fn
-			f := findfunc(frame.pc)
-			if !f.valid() {
-				print("runtime: unknown pc in defer ", hex(frame.pc), "\n")
-				throw("unknown pc")
-			}
-			frame.fn = f
-			frame.argp = uintptr(deferArgs(d))
-			var ok bool
-			frame.arglen, frame.argmap, ok = getArgInfoFast(f, true)
-			if !ok {
-				frame.arglen, frame.argmap = getArgInfo(&frame, f, true, fn)
-			}
-		}
-		frame.continpc = frame.pc
-		if !callback((*stkframe)(noescape(unsafe.Pointer(&frame))), v) {
-			return
-		}
-	}
-}
-
 // Generic traceback. Handles runtime stack prints (pcbuf == nil),
 // the runtime.Callers function (pcbuf != nil), as well as the garbage
 // collector (callback != nil).  A little clunky to merge these, but avoids
@@ -126,7 +92,7 @@
 			frame.lr = 0
 		} else {
 			frame.pc = uintptr(*(*uintptr)(unsafe.Pointer(frame.sp)))
-			frame.sp += sys.PtrSize
+			frame.sp += goarch.PtrSize
 		}
 	}
 
@@ -207,7 +173,7 @@
 			frame.fp = frame.sp + uintptr(funcspdelta(f, frame.pc, &cache))
 			if !usesLR {
 				// On x86, call instruction pushes return PC before entering new function.
-				frame.fp += sys.PtrSize
+				frame.fp += goarch.PtrSize
 			}
 		}
 		var flr funcInfo
@@ -248,7 +214,7 @@
 				}
 			} else {
 				if frame.lr == 0 {
-					lrPtr = frame.fp - sys.PtrSize
+					lrPtr = frame.fp - goarch.PtrSize
 					frame.lr = uintptr(*(*uintptr)(unsafe.Pointer(lrPtr)))
 				}
 			}
@@ -279,7 +245,7 @@
 		frame.varp = frame.fp
 		if !usesLR {
 			// On x86, call instruction pushes return PC before entering new function.
-			frame.varp -= sys.PtrSize
+			frame.varp -= goarch.PtrSize
 		}
 
 		// For architectures with frame pointers, if there's
@@ -300,7 +266,7 @@
 		// And it happens to end up mimicking the x86 layout.
 		// Other architectures may make different decisions.
 		if frame.varp > frame.sp && framepointer_enabled {
-			frame.varp -= sys.PtrSize
+			frame.varp -= goarch.PtrSize
 		}
 
 		// Derive size of arguments.
@@ -603,7 +569,7 @@
 		// mask out irrelavant bits
 		if sz < 8 {
 			shift := 64 - sz*8
-			if sys.BigEndian {
+			if goarch.BigEndian {
 				x = x >> shift
 			} else {
 				x = x << shift >> shift
@@ -700,16 +666,16 @@
 				// Figure out whether the return values are valid.
 				// Reflect will update this value after it copies
 				// in the return values.
-				retValid = *(*bool)(unsafe.Pointer(arg0 + 4*sys.PtrSize))
+				retValid = *(*bool)(unsafe.Pointer(arg0 + 4*goarch.PtrSize))
 			}
 			if mv.fn != f.entry {
 				print("runtime: confused by ", funcname(f), "\n")
 				throw("reflect mismatch")
 			}
 			bv := mv.stack
-			arglen = uintptr(bv.n * sys.PtrSize)
+			arglen = uintptr(bv.n * goarch.PtrSize)
 			if !retValid {
-				arglen = uintptr(mv.argLen) &^ (sys.PtrSize - 1)
+				arglen = uintptr(mv.argLen) &^ (goarch.PtrSize - 1)
 			}
 			argmap = bv
 		}
@@ -1045,8 +1011,8 @@
 // for debugging purposes. If the address bad is included in the
 // hexdumped range, it will mark it as well.
 func tracebackHexdump(stk stack, frame *stkframe, bad uintptr) {
-	const expand = 32 * sys.PtrSize
-	const maxExpand = 256 * sys.PtrSize
+	const expand = 32 * goarch.PtrSize
+	const maxExpand = 256 * goarch.PtrSize
 	// Start around frame.sp.
 	lo, hi := frame.sp, frame.sp
 	// Expand to include frame.fp.
diff --git a/src/runtime/type.go b/src/runtime/type.go
index 4039273..ad01d50 100644
--- a/src/runtime/type.go
+++ b/src/runtime/type.go
@@ -6,7 +6,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/abi"
+	"unsafe"
+)
 
 // tflag is documented in reflect/type.go.
 //
@@ -262,7 +265,7 @@
 	if off == -1 {
 		// -1 is the sentinel value for unreachable code.
 		// See cmd/link/internal/ld/data.go:relocsym.
-		return unsafe.Pointer(funcPC(unreachableMethod))
+		return unsafe.Pointer(abi.FuncPCABIInternal(unreachableMethod))
 	}
 	base := uintptr(unsafe.Pointer(t))
 	var md *moduledata
diff --git a/src/runtime/wincallback.go b/src/runtime/wincallback.go
index a7a787d..73f1e56 100644
--- a/src/runtime/wincallback.go
+++ b/src/runtime/wincallback.go
@@ -33,7 +33,7 @@
 // CALL instruction in runtime·callbackasm. This determines
 // which Go callback function is executed later on.
 
-TEXT runtime·callbackasm<ABIInternal>(SB),7,$0
+TEXT runtime·callbackasm(SB),7,$0
 `)
 	for i := 0; i < maxCallback; i++ {
 		buf.WriteString("\tCALL\truntime·callbackasm1(SB)\n")
@@ -61,7 +61,7 @@
 // It then calls the Go implementation for that callback.
 #include "textflag.h"
 
-TEXT runtime·callbackasm<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
 `)
 	for i := 0; i < maxCallback; i++ {
 		buf.WriteString(fmt.Sprintf("\tMOVW\t$%d, R12\n", i))
@@ -89,7 +89,7 @@
 // It then calls the Go implementation for that callback.
 #include "textflag.h"
 
-TEXT runtime·callbackasm<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
 `)
 	for i := 0; i < maxCallback; i++ {
 		buf.WriteString(fmt.Sprintf("\tMOVD\t$%d, R12\n", i))
diff --git a/src/runtime/zcallback_windows.s b/src/runtime/zcallback_windows.s
index e451c2b9..561527c 100644
--- a/src/runtime/zcallback_windows.s
+++ b/src/runtime/zcallback_windows.s
@@ -11,7 +11,7 @@
 // CALL instruction in runtime·callbackasm. This determines
 // which Go callback function is executed later on.
 
-TEXT runtime·callbackasm<ABIInternal>(SB),7,$0
+TEXT runtime·callbackasm(SB),7,$0
 	CALL	runtime·callbackasm1(SB)
 	CALL	runtime·callbackasm1(SB)
 	CALL	runtime·callbackasm1(SB)
diff --git a/src/runtime/zcallback_windows_arm.s b/src/runtime/zcallback_windows_arm.s
index a73a813..f943d84 100644
--- a/src/runtime/zcallback_windows_arm.s
+++ b/src/runtime/zcallback_windows_arm.s
@@ -9,7 +9,7 @@
 // It then calls the Go implementation for that callback.
 #include "textflag.h"
 
-TEXT runtime·callbackasm<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
 	MOVW	$0, R12
 	B	runtime·callbackasm1(SB)
 	MOVW	$1, R12
diff --git a/src/runtime/zcallback_windows_arm64.s b/src/runtime/zcallback_windows_arm64.s
index 2a6bda0..69fb057 100644
--- a/src/runtime/zcallback_windows_arm64.s
+++ b/src/runtime/zcallback_windows_arm64.s
@@ -9,7 +9,7 @@
 // It then calls the Go implementation for that callback.
 #include "textflag.h"
 
-TEXT runtime·callbackasm<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
 	MOVD	$0, R12
 	B	runtime·callbackasm1(SB)
 	MOVD	$1, R12
diff --git a/test/chan/perm.go b/test/chan/perm.go
index 4c94ab7..0404672 100644
--- a/test/chan/perm.go
+++ b/test/chan/perm.go
@@ -66,5 +66,5 @@
 	close(c)
 	close(cs)
 	close(cr) // ERROR "receive"
-	close(n)  // ERROR "invalid operation.*non-chan type|must be channel|not a channel"
+	close(n)  // ERROR "invalid operation.*non-chan type|must be channel|non-channel"
 }
diff --git a/test/codegen/arithmetic.go b/test/codegen/arithmetic.go
index a27a17f..eb0f338 100644
--- a/test/codegen/arithmetic.go
+++ b/test/codegen/arithmetic.go
@@ -202,7 +202,7 @@
 
 	// amd64:"MOVQ\t[$]-1085102592571150095","IMULQ",-"IDIVQ"
 	// 386:"MOVL\t[$]-252645135","IMULL",-"IDIVL"
-	// arm64:`MOVD`,`SMULH`,-`DIV`
+	// arm64:`SMULH`,-`DIV`
 	// arm:`MOVW`,`MUL`,-`.*udiv`
 	b := n2 / 17 // signed
 
@@ -266,7 +266,7 @@
 
 	// amd64:"MOVQ\t[$]-1085102592571150095","IMULQ",-"IDIVQ"
 	// 386:"MOVL\t[$]-252645135","IMULL",-"IDIVL"
-	// arm64:`MOVD`,`SMULH`,-`DIV`
+	// arm64:`SMULH`,-`DIV`
 	// arm:`MOVW`,`MUL`,-`.*udiv`
 	b := n2 % 17 // signed
 
diff --git a/test/codegen/clobberdead.go b/test/codegen/clobberdead.go
index f8d964c..c490790 100644
--- a/test/codegen/clobberdead.go
+++ b/test/codegen/clobberdead.go
@@ -1,6 +1,6 @@
 // asmcheck -gcflags=-clobberdead
 
-// +build amd64
+// +build amd64 arm64
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -13,15 +13,18 @@
 var p1, p2, p3 T
 
 func F() {
-	// 3735936685 is 0xdeaddead
+	// 3735936685 is 0xdeaddead. On ARM64 R27 is REGTMP.
 	// clobber x, y at entry. not clobber z (stack object).
 	// amd64:`MOVL\t\$3735936685, ""\.x`, `MOVL\t\$3735936685, ""\.y`, -`MOVL\t\$3735936685, ""\.z`
+	// arm64:`MOVW\tR27, ""\.x`, `MOVW\tR27, ""\.y`, -`MOVW\tR27, ""\.z`
 	x, y, z := p1, p2, p3
 	addrTaken(&z)
 	// x is dead at the call (the value of x is loaded before the CALL), y is not
 	// amd64:`MOVL\t\$3735936685, ""\.x`, -`MOVL\t\$3735936685, ""\.y`
+	// arm64:`MOVW\tR27, ""\.x`, -`MOVW\tR27, ""\.y`
 	use(x)
 	// amd64:`MOVL\t\$3735936685, ""\.x`, `MOVL\t\$3735936685, ""\.y`
+	// arm64:`MOVW\tR27, ""\.x`, `MOVW\tR27, ""\.y`
 	use(y)
 }
 
diff --git a/test/complit1.go b/test/complit1.go
index 7c2a4e2..8cbcd63 100644
--- a/test/complit1.go
+++ b/test/complit1.go
@@ -46,20 +46,20 @@
 	_ = &T{0, 0, "", nil}               // ok
 	_ = &T{i: 0, f: 0, s: "", next: {}} // ERROR "missing type in composite literal|omit types within composite literal"
 	_ = &T{0, 0, "", {}}                // ERROR "missing type in composite literal|omit types within composite literal"
-	_ = TP{i: 0, f: 0, s: "", next: {}} // ERROR "invalid composite literal type TP|omit types within composite literal"
+	_ = TP{i: 0, f: 0, s: ""}           // ERROR "invalid composite literal type TP"
 	_ = &Ti{}                           // ERROR "invalid composite literal type Ti|expected.*type for composite literal"
 )
 
 type M map[T]T
 
 var (
-	_ = M{{i:1}: {i:2}}
-	_ = M{T{i:1}: {i:2}}
-	_ = M{{i:1}: T{i:2}}
-	_ = M{T{i:1}: T{i:2}}
+	_ = M{{i: 1}: {i: 2}}
+	_ = M{T{i: 1}: {i: 2}}
+	_ = M{{i: 1}: T{i: 2}}
+	_ = M{T{i: 1}: T{i: 2}}
 )
 
-type S struct { s [1]*M1 }
+type S struct{ s [1]*M1 }
 type M1 map[S]int
-var _ = M1{{s:[1]*M1{&M1{{}:1}}}:2}
 
+var _ = M1{{s: [1]*M1{&M1{{}: 1}}}: 2}
diff --git a/test/ddd1.go b/test/ddd1.go
index ad49b34..f7381b7 100644
--- a/test/ddd1.go
+++ b/test/ddd1.go
@@ -17,8 +17,8 @@
 	_ = sum(1, 2, 3)
 	_ = sum()
 	_ = sum(1.0, 2.0)
-	_ = sum(1.5)      // ERROR "integer"
-	_ = sum("hello")  // ERROR ".hello. .type untyped string. as type int|incompatible"
+	_ = sum(1.5)      // ERROR "1\.5 .untyped float constant. as int|integer"
+	_ = sum("hello")  // ERROR ".hello. (.untyped string constant. as int|.type untyped string. as type int)|incompatible"
 	_ = sum([]int{1}) // ERROR "\[\]int{...}.*as type int|incompatible"
 )
 
@@ -27,9 +27,9 @@
 
 var (
 	_ = sum(tuple())
-	_ = sum(tuple()...) // ERROR "multiple-value"
+	_ = sum(tuple()...) // ERROR "\.{3} with 3-valued|multiple-value"
 	_ = sum3(tuple())
-	_ = sum3(tuple()...) // ERROR "multiple-value" ERROR "invalid use of .*[.][.][.]"
+	_ = sum3(tuple()...) // ERROR "\.{3} in call to non-variadic|multiple-value|invalid use of .*[.][.][.]"
 )
 
 type T []T
@@ -60,5 +60,5 @@
 	_ = [...]byte("foo") // ERROR "[.][.][.]"
 	_ = [...][...]int{{1,2,3},{4,5,6}}	// ERROR "[.][.][.]"
 
-	Foo(x...) // ERROR "invalid use of .*[.][.][.]"
+	Foo(x...) // ERROR "\.{3} in call to non-variadic|invalid use of .*[.][.][.]"
 }
diff --git a/test/devirt.go b/test/devirt.go
index e0149d8..d5c8152 100644
--- a/test/devirt.go
+++ b/test/devirt.go
@@ -31,9 +31,8 @@
 		panic("not 3")
 	}
 
-	// Can't do types that aren't "direct" interfaces (yet).
 	r = indirectiface{3, 4, 5}
-	if r.Value() != 12 {
+	if r.Value() != 12 { // ERROR "de-virtualizing call$"
 		panic("not 12")
 	}
 }
diff --git a/test/escape2.go b/test/escape2.go
index b9b723d..e3e5904 100644
--- a/test/escape2.go
+++ b/test/escape2.go
@@ -59,7 +59,7 @@
 	return *xx
 }
 
-func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r2 level=0$" "leaking param: yy to result ~r2 level=0$"
+func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r0 level=0$" "leaking param: yy to result ~r0 level=0$"
 	xx = yy
 	return xx
 }
@@ -343,11 +343,11 @@
 	return &x
 }
 
-func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return *&x
 }
 
-func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return *(**int)(unsafe.Pointer(&x))
 }
 
@@ -374,11 +374,11 @@
 	return (*uint64)(unsafe.Pointer(&f))
 }
 
-func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r1 level=0$"
+func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r0 level=0$"
 	return (*uint64)(unsafe.Pointer(f))
 }
 
-func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	switch val := i.(type) {
 	case *int:
 		return val
@@ -389,7 +389,7 @@
 	return nil
 }
 
-func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	switch j := i; *j + 110 {
 	case 12:
 		return j
@@ -401,7 +401,7 @@
 }
 
 // assigning to an array element is like assigning to the array
-func foo60(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func foo60(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	var a [12]*int
 	a[0] = i
 	return a[1]
@@ -414,7 +414,7 @@
 }
 
 // assigning to a struct field  is like assigning to the struct
-func foo61(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func foo61(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	type S struct {
 		a, b *int
 	}
@@ -611,11 +611,11 @@
 	}
 }
 
-func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r2 level=0$" "x does not escape$"
+func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r0 level=0$" "x does not escape$"
 	return y
 }
 
-func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r2 level=0$" "y does not escape$"
+func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r0 level=0$" "y does not escape$"
 	return &x[0]
 }
 
@@ -667,13 +667,13 @@
 func foo76f() {
 	for {
 		// TODO: This one really only escapes its scope, but we don't distinguish yet.
-		defer myprint(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
+		defer myprint(nil, 1, 2, 3) // ERROR "... argument does not escape$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
 	}
 }
 
 func foo76g() {
 	for {
-		defer myprint1(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
+		defer myprint1(nil, 1, 2, 3) // ERROR "... argument does not escape$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
 	}
 }
 
@@ -770,7 +770,7 @@
 	return map[*int]*int{x: nil} // ERROR "map\[\*int\]\*int{...} escapes to heap$"
 }
 
-func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return [2]*int{x, nil}
 }
 
@@ -783,7 +783,7 @@
 }
 
 // does not leak m
-func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r2 level=1"
+func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	for k, v := range m {
 		if b {
 			return k
@@ -799,12 +799,12 @@
 }
 
 // does not leak m but does leak content
-func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
+func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	return m[0]
 }
 
 // does leak m
-func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r0 level=0$"
 	return m[0]
 }
 
@@ -814,12 +814,12 @@
 }
 
 // does leak m
-func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r0 level=0$"
 	return m[:]
 }
 
 // does not leak m
-func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
+func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	for _, v := range m {
 		return v
 	}
@@ -827,7 +827,7 @@
 }
 
 // does leak m
-func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r0 level=0$"
 	for _, v := range m {
 		return v
 	}
@@ -890,27 +890,27 @@
 	return m[nil]
 }
 
-func foo111(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0"
+func foo111(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0"
 	m := []*int{x} // ERROR "\[\]\*int{...} does not escape$"
 	return m[0]
 }
 
-func foo112(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo112(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := [1]*int{x}
 	return m[0]
 }
 
-func foo113(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo113(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := Bar{ii: x}
 	return m.ii
 }
 
-func foo114(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo114(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := &Bar{ii: x} // ERROR "&Bar{...} does not escape$"
 	return m.ii
 }
 
-func foo115(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo115(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return (*int)(unsafe.Pointer(uintptr(unsafe.Pointer(x)) + 1))
 }
 
@@ -1148,16 +1148,16 @@
 
 func foo121() {
 	for i := 0; i < 10; i++ {
-		defer myprint(nil, i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
-		go myprint(nil, i)    // ERROR "... argument escapes to heap$" "i escapes to heap$"
+		defer myprint(nil, i) // ERROR "... argument does not escape$" "i escapes to heap$"
+		go myprint(nil, i)    // ERROR "... argument does not escape$" "i escapes to heap$"
 	}
 }
 
 // same as foo121 but check across import
 func foo121b() {
 	for i := 0; i < 10; i++ {
-		defer fmt.Printf("%d", i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
-		go fmt.Printf("%d", i)    // ERROR "... argument escapes to heap$" "i escapes to heap$"
+		defer fmt.Printf("%d", i) // ERROR "... argument does not escape$" "i escapes to heap$"
+		go fmt.Printf("%d", i)    // ERROR "... argument does not escape$" "i escapes to heap$"
 	}
 }
 
diff --git a/test/escape2n.go b/test/escape2n.go
index 7c8208a..57cc1a01 100644
--- a/test/escape2n.go
+++ b/test/escape2n.go
@@ -59,7 +59,7 @@
 	return *xx
 }
 
-func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r2 level=0$" "leaking param: yy to result ~r2 level=0$"
+func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r0 level=0$" "leaking param: yy to result ~r0 level=0$"
 	xx = yy
 	return xx
 }
@@ -343,11 +343,11 @@
 	return &x
 }
 
-func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return *&x
 }
 
-func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return *(**int)(unsafe.Pointer(&x))
 }
 
@@ -374,11 +374,11 @@
 	return (*uint64)(unsafe.Pointer(&f))
 }
 
-func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r1 level=0$"
+func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r0 level=0$"
 	return (*uint64)(unsafe.Pointer(f))
 }
 
-func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	switch val := i.(type) {
 	case *int:
 		return val
@@ -389,7 +389,7 @@
 	return nil
 }
 
-func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	switch j := i; *j + 110 {
 	case 12:
 		return j
@@ -401,7 +401,7 @@
 }
 
 // assigning to an array element is like assigning to the array
-func foo60(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func foo60(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	var a [12]*int
 	a[0] = i
 	return a[1]
@@ -414,7 +414,7 @@
 }
 
 // assigning to a struct field  is like assigning to the struct
-func foo61(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
+func foo61(i *int) *int { // ERROR "leaking param: i to result ~r0 level=0$"
 	type S struct {
 		a, b *int
 	}
@@ -611,11 +611,11 @@
 	}
 }
 
-func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r2 level=0$" "x does not escape$"
+func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r0 level=0$" "x does not escape$"
 	return y
 }
 
-func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r2 level=0$" "y does not escape$"
+func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r0 level=0$" "y does not escape$"
 	return &x[0]
 }
 
@@ -667,13 +667,13 @@
 func foo76f() {
 	for {
 		// TODO: This one really only escapes its scope, but we don't distinguish yet.
-		defer myprint(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
+		defer myprint(nil, 1, 2, 3) // ERROR "... argument does not escape$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
 	}
 }
 
 func foo76g() {
 	for {
-		defer myprint1(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
+		defer myprint1(nil, 1, 2, 3) // ERROR "... argument does not escape$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
 	}
 }
 
@@ -770,7 +770,7 @@
 	return map[*int]*int{x: nil} // ERROR "map\[\*int\]\*int{...} escapes to heap$"
 }
 
-func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return [2]*int{x, nil}
 }
 
@@ -783,7 +783,7 @@
 }
 
 // does not leak m
-func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r2 level=1"
+func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	for k, v := range m {
 		if b {
 			return k
@@ -799,12 +799,12 @@
 }
 
 // does not leak m but does leak content
-func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
+func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	return m[0]
 }
 
 // does leak m
-func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r0 level=0$"
 	return m[0]
 }
 
@@ -814,12 +814,12 @@
 }
 
 // does leak m
-func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r0 level=0$"
 	return m[:]
 }
 
 // does not leak m
-func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
+func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r0 level=1"
 	for _, v := range m {
 		return v
 	}
@@ -827,7 +827,7 @@
 }
 
 // does leak m
-func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
+func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r0 level=0$"
 	for _, v := range m {
 		return v
 	}
@@ -890,27 +890,27 @@
 	return m[nil]
 }
 
-func foo111(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0"
+func foo111(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0"
 	m := []*int{x} // ERROR "\[\]\*int{...} does not escape$"
 	return m[0]
 }
 
-func foo112(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo112(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := [1]*int{x}
 	return m[0]
 }
 
-func foo113(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo113(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := Bar{ii: x}
 	return m.ii
 }
 
-func foo114(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo114(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	m := &Bar{ii: x} // ERROR "&Bar{...} does not escape$"
 	return m.ii
 }
 
-func foo115(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo115(x *int) *int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return (*int)(unsafe.Pointer(uintptr(unsafe.Pointer(x)) + 1))
 }
 
@@ -1148,16 +1148,16 @@
 
 func foo121() {
 	for i := 0; i < 10; i++ {
-		defer myprint(nil, i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
-		go myprint(nil, i)    // ERROR "... argument escapes to heap$" "i escapes to heap$"
+		defer myprint(nil, i) // ERROR "... argument does not escape$" "i escapes to heap$"
+		go myprint(nil, i)    // ERROR "... argument does not escape$" "i escapes to heap$"
 	}
 }
 
 // same as foo121 but check across import
 func foo121b() {
 	for i := 0; i < 10; i++ {
-		defer fmt.Printf("%d", i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
-		go fmt.Printf("%d", i)    // ERROR "... argument escapes to heap$" "i escapes to heap$"
+		defer fmt.Printf("%d", i) // ERROR "... argument does not escape$" "i escapes to heap$"
+		go fmt.Printf("%d", i)    // ERROR "... argument does not escape$" "i escapes to heap$"
 	}
 }
 
diff --git a/test/escape5.go b/test/escape5.go
index 82be2c3..089130d 100644
--- a/test/escape5.go
+++ b/test/escape5.go
@@ -22,19 +22,19 @@
 	return p
 }
 
-func leaktoret2(p *int) (*int, *int) { // ERROR "leaking param: p to result ~r1" "leaking param: p to result ~r2"
+func leaktoret2(p *int) (*int, *int) { // ERROR "leaking param: p to result ~r0" "leaking param: p to result ~r1"
 	return p, p
 }
 
-func leaktoret22(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r2" "leaking param: q to result ~r3"
+func leaktoret22(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r0" "leaking param: q to result ~r1"
 	return p, q
 }
 
-func leaktoret22b(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r3" "leaking param: q to result ~r2"
+func leaktoret22b(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r1" "leaking param: q to result ~r0"
 	return leaktoret22(q, p)
 }
 
-func leaktoret22c(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r3" "leaking param: q to result ~r2"
+func leaktoret22c(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r1" "leaking param: q to result ~r0"
 	r, s := leaktoret22(q, p)
 	return r, s
 }
@@ -173,15 +173,14 @@
 func (*U) M()   {}
 func (_ *U) N() {}
 
-func _() {
+func fbad24305a() {
 	var u U
 	u.M()
 	u.N()
 }
 
-func fbad24305() {
-	// BAD u should not be heap allocated
-	var u U // ERROR "moved to heap: u"
+func fbad24305b() {
+	var u U
 	(*U).M(&u)
 	(*U).N(&u)
 }
diff --git a/test/escape_array.go b/test/escape_array.go
index 0d07fd8..83062c9 100644
--- a/test/escape_array.go
+++ b/test/escape_array.go
@@ -12,15 +12,15 @@
 
 type U [2]*string
 
-func bar(a, b *string) U { // ERROR "leaking param: a to result ~r2 level=0$" "leaking param: b to result ~r2 level=0$"
+func bar(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
 	return U{a, b}
 }
 
-func foo(x U) U { // ERROR "leaking param: x to result ~r1 level=0$"
+func foo(x U) U { // ERROR "leaking param: x to result ~r0 level=0$"
 	return U{x[1], x[0]}
 }
 
-func bff(a, b *string) U { // ERROR "leaking param: a to result ~r2 level=0$" "leaking param: b to result ~r2 level=0$"
+func bff(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
 	return foo(foo(bar(a, b)))
 }
 
@@ -41,27 +41,27 @@
 	return u[1]
 }
 
-func car(x U) *string { // ERROR "leaking param: x to result ~r1 level=0$"
+func car(x U) *string { // ERROR "leaking param: x to result ~r0 level=0$"
 	return x[0]
 }
 
 // BAD: need fine-grained analysis to track x[0] and x[1] differently.
-func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r2 level=0$" "leaking param: y to result ~r2 level=0$"
+func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=0$" "leaking param: y to result ~r0 level=0$"
 	x[0] = y
 	return x[1]
 }
 
-func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param: y$"
+func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param: y$"
 	x[0] = y // leaking y to heap is intended
 	return x[1]
 }
 
-func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param content: y$"
+func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
 	x[0] = *y
 	return x[1]
 }
 
-func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param content: y$"
+func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
 	x[0] = y[0]
 	return x[1]
 }
diff --git a/test/escape_calls.go b/test/escape_calls.go
index 9e1db54..aa7c7f5 100644
--- a/test/escape_calls.go
+++ b/test/escape_calls.go
@@ -11,7 +11,7 @@
 
 package foo
 
-func f(buf []byte) []byte { // ERROR "leaking param: buf to result ~r1 level=0$"
+func f(buf []byte) []byte { // ERROR "leaking param: buf to result ~r0 level=0$"
 	return buf
 }
 
diff --git a/test/escape_closure.go b/test/escape_closure.go
index 9152319..bd6c025 100644
--- a/test/escape_closure.go
+++ b/test/escape_closure.go
@@ -44,7 +44,7 @@
 
 func ClosureCallArgs4() {
 	x := 0
-	_ = func(p *int) *int { // ERROR "leaking param: p to result ~r1" "func literal does not escape"
+	_ = func(p *int) *int { // ERROR "leaking param: p to result ~r0" "func literal does not escape"
 		return p
 	}(&x)
 }
@@ -111,7 +111,7 @@
 
 func ClosureCallArgs12() {
 	x := 0
-	defer func(p *int) *int { // ERROR "leaking param: p to result ~r1" "func literal does not escape"
+	defer func(p *int) *int { // ERROR "leaking param: p to result ~r0" "func literal does not escape"
 		return p
 	}(&x)
 }
@@ -126,7 +126,7 @@
 func ClosureCallArgs14() {
 	x := 0
 	p := &x
-	_ = func(p **int) *int { // ERROR "leaking param: p to result ~r1 level=1" "func literal does not escape"
+	_ = func(p **int) *int { // ERROR "leaking param: p to result ~r0 level=1" "func literal does not escape"
 		return *p
 	}(&p)
 }
@@ -145,7 +145,7 @@
 }
 
 // See #14409 -- returning part of captured var leaks it.
-func ClosureLeak1a(a ...string) string { // ERROR "leaking param: a to result ~r1 level=1$"
+func ClosureLeak1a(a ...string) string { // ERROR "leaking param: a to result ~r0 level=1$"
 	return func() string { // ERROR "func literal does not escape"
 		return a[0]
 	}()
diff --git a/test/escape_goto.go b/test/escape_goto.go
index f024a9a..90da5a2 100644
--- a/test/escape_goto.go
+++ b/test/escape_goto.go
@@ -10,7 +10,7 @@
 
 var x bool
 
-func _() {
+func f1() {
 	var p *int
 loop:
 	if x {
@@ -22,7 +22,7 @@
 	_ = p
 }
 
-func _() {
+func f2() {
 	var p *int
 	if x {
 	loop:
@@ -33,7 +33,7 @@
 	_ = p
 }
 
-func _() {
+func f3() {
 	var p *int
 	if x {
 	loop:
diff --git a/test/escape_param.go b/test/escape_param.go
index dc93f68..b630bae 100644
--- a/test/escape_param.go
+++ b/test/escape_param.go
@@ -16,7 +16,7 @@
 var sink interface{}
 
 // in -> out
-func param0(p *int) *int { // ERROR "leaking param: p to result ~r1"
+func param0(p *int) *int { // ERROR "leaking param: p to result ~r0"
 	return p
 }
 
@@ -31,7 +31,7 @@
 }
 
 // in, in -> out, out
-func param1(p1, p2 *int) (*int, *int) { // ERROR "leaking param: p1 to result ~r2" "leaking param: p2 to result ~r3"
+func param1(p1, p2 *int) (*int, *int) { // ERROR "leaking param: p1 to result ~r0" "leaking param: p2 to result ~r1"
 	return p1, p2
 }
 
@@ -222,7 +222,7 @@
 }
 
 // *in -> out
-func param9(p ***int) **int { // ERROR "leaking param: p to result ~r1 level=1"
+func param9(p ***int) **int { // ERROR "leaking param: p to result ~r0 level=1"
 	return *p
 }
 
@@ -241,7 +241,7 @@
 }
 
 // **in -> out
-func param10(p ***int) *int { // ERROR "leaking param: p to result ~r1 level=2"
+func param10(p ***int) *int { // ERROR "leaking param: p to result ~r0 level=2"
 	return **p
 }
 
@@ -436,6 +436,6 @@
 
 // Convert to a direct interface, does not need an allocation.
 // So x only leaks to result.
-func param14b(x *int) interface{} { // ERROR "leaking param: x to result ~r1 level=0"
+func param14b(x *int) interface{} { // ERROR "leaking param: x to result ~r0 level=0"
 	return x
 }
diff --git a/test/escape_runtime_atomic.go b/test/escape_runtime_atomic.go
index 62e8fed..30d1d0c 100644
--- a/test/escape_runtime_atomic.go
+++ b/test/escape_runtime_atomic.go
@@ -13,8 +13,8 @@
 	"unsafe"
 )
 
-// BAD: should always be "leaking param: addr to result ~r1 level=1$".
-func Loadp(addr unsafe.Pointer) unsafe.Pointer { // ERROR "leaking param: addr( to result ~r1 level=1)?$"
+// BAD: should always be "leaking param: addr to result ~r0 level=1$".
+func Loadp(addr unsafe.Pointer) unsafe.Pointer { // ERROR "leaking param: addr( to result ~r0 level=1)?$"
 	return atomic.Loadp(addr)
 }
 
diff --git a/test/escape_slice.go b/test/escape_slice.go
index d604147..055b60b 100644
--- a/test/escape_slice.go
+++ b/test/escape_slice.go
@@ -101,7 +101,7 @@
 	_ = s
 }
 
-func slice12(x []int) *[1]int { // ERROR "leaking param: x to result ~r1 level=0$"
+func slice12(x []int) *[1]int { // ERROR "leaking param: x to result ~r0 level=0$"
 	return (*[1]int)(x)
 }
 
@@ -110,7 +110,7 @@
 	return mergeEnvLists([]string{"PWD=" + dir}, env) // ERROR ".PWD=. \+ dir escapes to heap" "\[\]string{...} does not escape"
 }
 
-func mergeEnvLists(in, out []string) []string { // ERROR "leaking param content: in" "leaking param content: out" "leaking param: out to result ~r2 level=0"
+func mergeEnvLists(in, out []string) []string { // ERROR "leaking param content: in" "leaking param content: out" "leaking param: out to result ~r0 level=0"
 NextVar:
 	for _, inkv := range in {
 		k := strings.SplitAfterN(inkv, "=", 2)[0]
diff --git a/test/escape_struct_return.go b/test/escape_struct_return.go
index 222ef8b..a42ae1e 100644
--- a/test/escape_struct_return.go
+++ b/test/escape_struct_return.go
@@ -15,11 +15,11 @@
 	_spp **string
 }
 
-func A(sp *string, spp **string) U { // ERROR "leaking param: sp to result ~r2 level=0$" "leaking param: spp to result ~r2 level=0$"
+func A(sp *string, spp **string) U { // ERROR "leaking param: sp to result ~r0 level=0$" "leaking param: spp to result ~r0 level=0$"
 	return U{sp, spp}
 }
 
-func B(spp **string) U { // ERROR "leaking param: spp to result ~r1 level=0$"
+func B(spp **string) U { // ERROR "leaking param: spp to result ~r0 level=0$"
 	return U{*spp, spp}
 }
 
diff --git a/test/escape_unsafe.go b/test/escape_unsafe.go
index b34beac..cec6674 100644
--- a/test/escape_unsafe.go
+++ b/test/escape_unsafe.go
@@ -15,7 +15,7 @@
 
 // (1) Conversion of a *T1 to Pointer to *T2.
 
-func convert(p *float64) *uint64 { // ERROR "leaking param: p to result ~r1 level=0$"
+func convert(p *float64) *uint64 { // ERROR "leaking param: p to result ~r0 level=0$"
 	return (*uint64)(unsafe.Pointer(p))
 }
 
@@ -39,12 +39,12 @@
 // (5) Conversion of the result of reflect.Value.Pointer or
 // reflect.Value.UnsafeAddr from uintptr to Pointer.
 
-// BAD: should be "leaking param: p to result ~r1 level=0$"
+// BAD: should be "leaking param: p to result ~r0 level=0$"
 func valuePointer(p *int) unsafe.Pointer { // ERROR "leaking param: p$"
 	return unsafe.Pointer(reflect.ValueOf(p).Pointer())
 }
 
-// BAD: should be "leaking param: p to result ~r1 level=0$"
+// BAD: should be "leaking param: p to result ~r0 level=0$"
 func valueUnsafeAddr(p *int) unsafe.Pointer { // ERROR "leaking param: p$"
 	return unsafe.Pointer(reflect.ValueOf(p).Elem().UnsafeAddr())
 }
@@ -52,11 +52,11 @@
 // (6) Conversion of a reflect.SliceHeader or reflect.StringHeader
 // Data field to or from Pointer.
 
-func fromSliceData(s []int) unsafe.Pointer { // ERROR "leaking param: s to result ~r1 level=0$"
+func fromSliceData(s []int) unsafe.Pointer { // ERROR "leaking param: s to result ~r0 level=0$"
 	return unsafe.Pointer((*reflect.SliceHeader)(unsafe.Pointer(&s)).Data)
 }
 
-func fromStringData(s string) unsafe.Pointer { // ERROR "leaking param: s to result ~r1 level=0$"
+func fromStringData(s string) unsafe.Pointer { // ERROR "leaking param: s to result ~r0 level=0$"
 	return unsafe.Pointer((*reflect.StringHeader)(unsafe.Pointer(&s)).Data)
 }
 
diff --git a/test/fixedbugs/bug195.go b/test/fixedbugs/bug195.go
index 94f61ff..6d8578d 100644
--- a/test/fixedbugs/bug195.go
+++ b/test/fixedbugs/bug195.go
@@ -1,4 +1,4 @@
-// errorcheck
+// errorcheck -lang=go1.17
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/bug248.dir/bug2.go b/test/fixedbugs/bug248.dir/bug2.go
index c0fdecf..92a7974 100644
--- a/test/fixedbugs/bug248.dir/bug2.go
+++ b/test/fixedbugs/bug248.dir/bug2.go
@@ -50,8 +50,8 @@
 func foobar() {
 	// check that cannot assign one to the other,
 	// but can convert.
-	v0 = v1 // ERROR "assign"
-	v1 = v0 // ERROR "assign"
+	v0 = v1 // ERROR "assign|cannot use"
+	v1 = v0 // ERROR "assign|cannot use"
 
 	v0 = p0.T(v1)
 	v1 = p1.T(v0)
diff --git a/test/fixedbugs/bug267.go b/test/fixedbugs/bug267.go
index cf8bf84..b61216a 100644
--- a/test/fixedbugs/bug267.go
+++ b/test/fixedbugs/bug267.go
@@ -10,7 +10,7 @@
 
 var a []bool
 
-func _() {
+func f1() {
 	if a[T{42}[0]] {
 	}
 	// if (a[T{42}[0]]) {}  // this compiles
diff --git a/test/fixedbugs/bug345.dir/main.go b/test/fixedbugs/bug345.dir/main.go
index b77a2fa..a53d3e8 100644
--- a/test/fixedbugs/bug345.dir/main.go
+++ b/test/fixedbugs/bug345.dir/main.go
@@ -23,7 +23,7 @@
 	// main.go:27: cannot use &x (type *"io".SectionReader) as type *"/Users/rsc/g/go/test/fixedbugs/bug345.dir/io".SectionReader in function argument
 
 	var w io.Writer
-	bufio.NewWriter(w) // ERROR "[\w.]+[^.]/io|has incompatible type"
+	bufio.NewWriter(w) // ERROR "[\w.]+[^.]/io|has incompatible type|cannot use"
 	var x goio.SectionReader
-	io.SR(&x) // ERROR "[\w.]+[^.]/io|has incompatible type"
+	io.SR(&x) // ERROR "[\w.]+[^.]/io|has incompatible type|cannot use"
 }
diff --git a/test/fixedbugs/bug460.dir/b.go b/test/fixedbugs/bug460.dir/b.go
index ef64694..5d388fc 100644
--- a/test/fixedbugs/bug460.dir/b.go
+++ b/test/fixedbugs/bug460.dir/b.go
@@ -9,9 +9,9 @@
 var x a.Foo
 
 func main() {
-	x.int = 20    // ERROR "unexported field"
-	x.int8 = 20   // ERROR "unexported field"
-	x.error = nil // ERROR "unexported field"
-	x.rune = 'a'  // ERROR "unexported field"
-	x.byte = 20   // ERROR "unexported field"
+	x.int = 20    // ERROR "unexported field|undefined"
+	x.int8 = 20   // ERROR "unexported field|undefined"
+	x.error = nil // ERROR "unexported field|undefined"
+	x.rune = 'a'  // ERROR "unexported field|undefined"
+	x.byte = 20   // ERROR "unexported field|undefined"
 }
diff --git a/test/fixedbugs/issue10975.go b/test/fixedbugs/issue10975.go
index 89ef23c..876ea58 100644
--- a/test/fixedbugs/issue10975.go
+++ b/test/fixedbugs/issue10975.go
@@ -1,4 +1,4 @@
-// errorcheck
+// errorcheck -lang=go1.17
 
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue11614.go b/test/fixedbugs/issue11614.go
index de15f98..6ea463b 100644
--- a/test/fixedbugs/issue11614.go
+++ b/test/fixedbugs/issue11614.go
@@ -1,4 +1,4 @@
-// errorcheck
+// errorcheck -lang=go1.17
 
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue12006.go b/test/fixedbugs/issue12006.go
index 0a2ef8d..e878bc4 100644
--- a/test/fixedbugs/issue12006.go
+++ b/test/fixedbugs/issue12006.go
@@ -87,7 +87,7 @@
 	FooI(a, b, c) // ERROR "a escapes to heap" "b escapes to heap" "... argument does not escape"
 }
 
-func FooJ(args ...interface{}) *int32 { // ERROR "leaking param: args to result ~r1 level=1"
+func FooJ(args ...interface{}) *int32 { // ERROR "leaking param: args to result ~r0 level=1"
 	for i := 0; i < len(args); i++ {
 		switch x := args[i].(type) {
 		case nil:
@@ -123,7 +123,7 @@
 	a *[4]interface{}
 }
 
-func FooK(args fakeSlice) *int32 { // ERROR "leaking param: args to result ~r1 level=1"
+func FooK(args fakeSlice) *int32 { // ERROR "leaking param: args to result ~r0 level=1"
 	for i := 0; i < args.l; i++ {
 		switch x := (*args.a)[i].(type) {
 		case nil:
@@ -148,7 +148,7 @@
 	isink = FooK(fs)
 }
 
-func FooL(args []interface{}) *int32 { // ERROR "leaking param: args to result ~r1 level=1"
+func FooL(args []interface{}) *int32 { // ERROR "leaking param: args to result ~r0 level=1"
 	for i := 0; i < len(args); i++ {
 		switch x := args[i].(type) {
 		case nil:
diff --git a/test/fixedbugs/issue12588.go b/test/fixedbugs/issue12588.go
index 950ef36..dc81111 100644
--- a/test/fixedbugs/issue12588.go
+++ b/test/fixedbugs/issue12588.go
@@ -35,7 +35,7 @@
 	return 0
 }
 
-func h(a *B) *uint64 { // ERROR "leaking param: a to result ~r1 level=1"
+func h(a *B) *uint64 { // ERROR "leaking param: a to result ~r0 level=1"
 	for i, x := range &a.b {
 		if i == 0 {
 			return x
@@ -44,7 +44,7 @@
 	return nil
 }
 
-func h2(a *B) *uint64 { // ERROR "leaking param: a to result ~r1 level=1"
+func h2(a *B) *uint64 { // ERROR "leaking param: a to result ~r0 level=1"
 	p := &a.b
 	for i, x := range p {
 		if i == 0 {
@@ -55,7 +55,7 @@
 }
 
 // Seems like below should be level=1, not 0.
-func k(a B) *uint64 { // ERROR "leaking param: a to result ~r1 level=0"
+func k(a B) *uint64 { // ERROR "leaking param: a to result ~r0 level=0"
 	for i, x := range &a.b {
 		if i == 0 {
 			return x
diff --git a/test/fixedbugs/issue14652.go b/test/fixedbugs/issue14652.go
index d53b412..14a2239 100644
--- a/test/fixedbugs/issue14652.go
+++ b/test/fixedbugs/issue14652.go
@@ -6,4 +6,4 @@
 
 package p
 
-var x any // ERROR "undefined: any|undefined type .*any.*"
+var x any // ERROR "undefined: any|undefined type .*any.*|cannot use any outside constraint position"
diff --git a/test/fixedbugs/issue14999.go b/test/fixedbugs/issue14999.go
index b648441..a25a50e 100644
--- a/test/fixedbugs/issue14999.go
+++ b/test/fixedbugs/issue14999.go
@@ -7,11 +7,11 @@
 package p
 
 func f(x int) func(int) int {
-	return func(y int) int { return x + y } // ERROR "heap-allocated closure, not allowed in runtime"
+	return func(y int) int { return x + y } // ERROR "heap-allocated closure f\.func1, not allowed in runtime"
 }
 
 func g(x int) func(int) int { // ERROR "x escapes to heap, not allowed in runtime"
-	return func(y int) int { // ERROR "heap-allocated closure, not allowed in runtime"
+	return func(y int) int { // ERROR "heap-allocated closure g\.func1, not allowed in runtime"
 		x += y
 		return x + y
 	}
diff --git a/test/fixedbugs/issue20250.go b/test/fixedbugs/issue20250.go
index 1a513be..aed7b25 100644
--- a/test/fixedbugs/issue20250.go
+++ b/test/fixedbugs/issue20250.go
@@ -17,7 +17,7 @@
 func f(a T) { // ERROR "live at entry to f: a"
 	var e interface{} // ERROR "stack object e interface \{\}$"
 	func() {          // ERROR "live at entry to f.func1: a &e"
-		e = a.s // ERROR "live at call to convT2E: &e" "stack object a T$"
+		e = a.s // ERROR "live at call to convT: &e" "stack object a T$"
 	}()
 	// Before the fix, both a and e were live at the previous line.
 	_ = e
diff --git a/test/fixedbugs/issue22076.go b/test/fixedbugs/issue22076.go
index 5d628b9..b383a67 100644
--- a/test/fixedbugs/issue22076.go
+++ b/test/fixedbugs/issue22076.go
@@ -13,12 +13,12 @@
 
 var _ Reader // use "bytes" import
 
-func _() {
+func f1() {
 	Buffer := 0
 	_ = Buffer
 }
 
-func _() {
+func f2() {
 	for Buffer := range []int{} {
 		_ = Buffer
 	}
diff --git a/test/fixedbugs/issue24651a.go b/test/fixedbugs/issue24651a.go
index 6c7bf30..1bfe8ac 100644
--- a/test/fixedbugs/issue24651a.go
+++ b/test/fixedbugs/issue24651a.go
@@ -21,5 +21,5 @@
 //go:noinline Provide a clean, constant reason for not inlining main
 func main() { // ERROR "cannot inline main: marked go:noinline$"
 	println("Foo(", x, ")=", Foo(x))
-	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
+	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar"
 }
diff --git a/test/fixedbugs/issue24651b.go b/test/fixedbugs/issue24651b.go
index aa88a67..2af54fc 100644
--- a/test/fixedbugs/issue24651b.go
+++ b/test/fixedbugs/issue24651b.go
@@ -19,6 +19,6 @@
 
 //go:noinline Provide a clean, constant reason for not inlining main
 func main() { // ERROR "cannot inline main: marked go:noinline$"
-	println("Foo(", x, ")=", Foo(x)) // ERROR "inlining call to Foo func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
-	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
+	println("Foo(", x, ")=", Foo(x)) // ERROR "inlining call to Foo"
+	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar"
 }
diff --git a/test/fixedbugs/issue26163.go b/test/fixedbugs/issue26163.go
index d141a27..3f3d778 100644
--- a/test/fixedbugs/issue26163.go
+++ b/test/fixedbugs/issue26163.go
@@ -1,4 +1,4 @@
-// compile -N -d=softfloat -goexperiment noregabiargs
+// compile -N -d=softfloat
 
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue27557.go b/test/fixedbugs/issue27557.go
index e35ab5a..f609b27 100644
--- a/test/fixedbugs/issue27557.go
+++ b/test/fixedbugs/issue27557.go
@@ -8,19 +8,19 @@
 
 var sink interface{}
 
-func _() {
+func f1() {
 	var t T
 	f := t.noescape // ERROR "t.noescape does not escape"
 	f()
 }
 
-func _() {
+func f2() {
 	var t T       // ERROR "moved to heap"
 	f := t.escape // ERROR "t.escape does not escape"
 	f()
 }
 
-func _() {
+func f3() {
 	var t T        // ERROR "moved to heap"
 	f := t.returns // ERROR "t.returns does not escape"
 	sink = f()
diff --git a/test/fixedbugs/issue28688.go b/test/fixedbugs/issue28688.go
index 8ef0802..0d2000e 100644
--- a/test/fixedbugs/issue28688.go
+++ b/test/fixedbugs/issue28688.go
@@ -1,4 +1,4 @@
-// run -gcflags=-d=softfloat -goexperiment noregabiargs
+// run -gcflags=-d=softfloat
 
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue30862.dir/a.go b/test/fixedbugs/issue30862.dir/a/a.go
similarity index 100%
rename from test/fixedbugs/issue30862.dir/a.go
rename to test/fixedbugs/issue30862.dir/a/a.go
diff --git a/test/fixedbugs/issue30862.dir/b.go b/test/fixedbugs/issue30862.dir/b/b.go
similarity index 95%
rename from test/fixedbugs/issue30862.dir/b.go
rename to test/fixedbugs/issue30862.dir/b/b.go
index 3e501bb..230221d 100644
--- a/test/fixedbugs/issue30862.dir/b.go
+++ b/test/fixedbugs/issue30862.dir/b/b.go
@@ -4,7 +4,7 @@
 
 package b
 
-import "./a"
+import "issue30862.dir/a"
 
 type EmbedImported struct {
 	a.NoitfStruct
diff --git a/test/fixedbugs/issue30862.dir/main.go b/test/fixedbugs/issue30862.dir/main.go
index 80db0e1..1489c5a 100644
--- a/test/fixedbugs/issue30862.dir/main.go
+++ b/test/fixedbugs/issue30862.dir/main.go
@@ -8,7 +8,7 @@
 	"fmt"
 	"os"
 
-	"./b"
+	"issue30862.dir/b"
 )
 
 // Test case for issue 30862.
diff --git a/test/fixedbugs/issue30862.go b/test/fixedbugs/issue30862.go
index ba122cc..acac71e 100644
--- a/test/fixedbugs/issue30862.go
+++ b/test/fixedbugs/issue30862.go
@@ -1,4 +1,4 @@
-// rundir
+// runindir -goexperiment fieldtrack
 
 // Copyright 2019 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -9,6 +9,4 @@
 // is set when building it, whereas gccgo has field tracking
 // enabled by default (hence the build tag below).
 
-// +build gccgo
-
 package ignored
diff --git a/test/fixedbugs/issue30898.go b/test/fixedbugs/issue30898.go
index b6376d3..c7f6f2d 100644
--- a/test/fixedbugs/issue30898.go
+++ b/test/fixedbugs/issue30898.go
@@ -15,5 +15,5 @@
 
 func bar() { // ERROR "can inline bar"
 	value := 10
-	debugf("value is %d", value) // ERROR "inlining call to debugf" "value does not escape" "\[\]interface {}{...} does not escape"
+	debugf("value is %d", value) // ERROR "inlining call to debugf" "value does not escape" "\.\.\. argument does not escape"
 }
diff --git a/test/fixedbugs/issue31573.go b/test/fixedbugs/issue31573.go
index 005910e..eaab563 100644
--- a/test/fixedbugs/issue31573.go
+++ b/test/fixedbugs/issue31573.go
@@ -19,31 +19,31 @@
 	defer f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} does not escape$" "new\(int\) does not escape$"
 
 	go f()
-	go f(new(int))           // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
-	go f(new(int), new(int)) // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
+	go f(new(int))           // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
+	go f(new(int), new(int)) // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
 
 	go f(nil...)
-	go f([]*int{}...)                   // ERROR "\[\]\*int{} escapes to heap$"
-	go f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
-	go f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
+	go f([]*int{}...)                   // ERROR "\[\]\*int{} does not escape$"
+	go f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
+	go f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
 
 	for {
 		defer f()
-		defer f(new(int))           // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
-		defer f(new(int), new(int)) // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
+		defer f(new(int))           // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
+		defer f(new(int), new(int)) // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
 
 		defer f(nil...)
-		defer f([]*int{}...)                   // ERROR "\[\]\*int{} escapes to heap$"
-		defer f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
-		defer f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
+		defer f([]*int{}...)                   // ERROR "\[\]\*int{} does not escape$"
+		defer f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
+		defer f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
 
 		go f()
-		go f(new(int))           // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
-		go f(new(int), new(int)) // ERROR "... argument escapes to heap$" "new\(int\) escapes to heap$"
+		go f(new(int))           // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
+		go f(new(int), new(int)) // ERROR "... argument does not escape$" "new\(int\) escapes to heap$"
 
 		go f(nil...)
-		go f([]*int{}...)                   // ERROR "\[\]\*int{} escapes to heap$"
-		go f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
-		go f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} escapes to heap$" "new\(int\) escapes to heap$"
+		go f([]*int{}...)                   // ERROR "\[\]\*int{} does not escape$"
+		go f([]*int{new(int)}...)           // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
+		go f([]*int{new(int), new(int)}...) // ERROR "\[\]\*int{...} does not escape$" "new\(int\) escapes to heap$"
 	}
 }
diff --git a/test/fixedbugs/issue41500.go b/test/fixedbugs/issue41500.go
index 3ec23a0..b0ae7cf 100644
--- a/test/fixedbugs/issue41500.go
+++ b/test/fixedbugs/issue41500.go
@@ -13,8 +13,8 @@
 func f() {
 	var x *s
 
-	_ = x == nil || len(x.slice) // ERROR "invalid operation: .+ \(operator \|\| not defined on int\)|incompatible types|cannot convert"
-	_ = len(x.slice) || x == nil // ERROR "invalid operation: .+ \(operator \|\| not defined on int\)|incompatible types|cannot convert"
-	_ = x == nil && len(x.slice) // ERROR "invalid operation: .+ \(operator && not defined on int\)|incompatible types|cannot convert"
-	_ = len(x.slice) && x == nil // ERROR "invalid operation: .+ \(operator && not defined on int\)|incompatible types|cannot convert"
+	_ = x == nil || len(x.slice) // ERROR "invalid operation: .+ \(operator \|\| not defined on int\)|incompatible types|mismatched types untyped bool and int"
+	_ = len(x.slice) || x == nil // ERROR "invalid operation: .+ \(operator \|\| not defined on int\)|incompatible types|mismatched types int and untyped bool"
+	_ = x == nil && len(x.slice) // ERROR "invalid operation: .+ \(operator && not defined on int\)|incompatible types|mismatched types untyped bool and int"
+	_ = len(x.slice) && x == nil // ERROR "invalid operation: .+ \(operator && not defined on int\)|incompatible types|mismatched types int and untyped bool"
 }
diff --git a/test/fixedbugs/issue42284.dir/a.go b/test/fixedbugs/issue42284.dir/a.go
index ffe9310..f7fd80b 100644
--- a/test/fixedbugs/issue42284.dir/a.go
+++ b/test/fixedbugs/issue42284.dir/a.go
@@ -13,7 +13,7 @@
 	return T(0) // ERROR "T\(0\) escapes to heap"
 }
 
-func F(i I) I { // ERROR "can inline F" "leaking param: i to result ~r1 level=0"
+func F(i I) I { // ERROR "can inline F" "leaking param: i to result ~r0 level=0"
 	i = nil
 	return i
 }
diff --git a/test/fixedbugs/issue43762.go b/test/fixedbugs/issue43762.go
index 9f7682a..bf950c8 100644
--- a/test/fixedbugs/issue43762.go
+++ b/test/fixedbugs/issue43762.go
@@ -6,6 +6,6 @@
 
 package p
 
-var _ = true == '\\' // ERROR "invalid operation: true == '\\\\'|cannot convert true"
-var _ = true == '\'' // ERROR "invalid operation: true == '\\''|cannot convert true"
-var _ = true == '\n' // ERROR "invalid operation: true == '\\n'|cannot convert true"
+var _ = true == '\\' // ERROR "invalid operation: (cannot compare true)|(true) == '\\\\' \(mismatched types untyped bool and untyped rune\)"
+var _ = true == '\'' // ERROR "invalid operation: (cannot compare true)|(true) == '\\'' \(mismatched types untyped bool and untyped rune\)"
+var _ = true == '\n' // ERROR "invalid operation: (cannot compare true)|(true) == '\\n' \(mismatched types untyped bool and untyped rune\)"
diff --git a/test/fixedbugs/issue44432.go b/test/fixedbugs/issue44432.go
index c5fb67e..eec53f3 100644
--- a/test/fixedbugs/issue44432.go
+++ b/test/fixedbugs/issue44432.go
@@ -8,6 +8,6 @@
 
 var m = map[string]int{
 	"a": 1,
-	1:   1, // ERROR "cannot use 1.*as type string in map key"
-	2:   2, // ERROR "cannot use 2.*as type string in map key"
+	1:   1, // ERROR "cannot use 1.*as.*string.*in map"
+	2:   2, // ERROR "cannot use 2.*as.*string.*in map"
 }
diff --git a/test/fixedbugs/issue45258.go b/test/fixedbugs/issue45258.go
index f4d6fcc..b026c0c 100644
--- a/test/fixedbugs/issue45258.go
+++ b/test/fixedbugs/issue45258.go
@@ -22,7 +22,7 @@
 
 func (r *impl) Bar() {}
 
-func _() {
+func f1() {
 	var r Fooer = &impl{}
 	r.Foo().Bar()
 }
diff --git a/test/fixedbugs/issue46556.go b/test/fixedbugs/issue46556.go
new file mode 100644
index 0000000..b159f61
--- /dev/null
+++ b/test/fixedbugs/issue46556.go
@@ -0,0 +1,16 @@
+// compile
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type A = interface{}
+type B interface{}
+
+// Test that embedding both anonymous and defined types is supported.
+type C interface {
+	A
+	B
+}
diff --git a/test/fixedbugs/issue46749.go b/test/fixedbugs/issue46749.go
index 63ed197..faf1f88 100644
--- a/test/fixedbugs/issue46749.go
+++ b/test/fixedbugs/issue46749.go
@@ -14,13 +14,13 @@
 var (
 	_ = "" + b   // ERROR "invalid operation.*mismatched types.*untyped string and bool"
 	_ = "" + i   // ERROR "invalid operation.*mismatched types.*untyped string and int"
-	_ = "" + nil // ERROR "invalid operation.*mismatched types.*untyped string and nil"
+	_ = "" + nil // ERROR "invalid operation.*mismatched types.*untyped string and nil|(untyped nil)"
 )
 
 var (
 	_ = s + false // ERROR "invalid operation.*mismatched types.*string and untyped bool"
 	_ = s + 1     // ERROR "invalid operation.*mismatched types.*string and untyped int"
-	_ = s + nil   // ERROR "invalid operation.*mismatched types.*string and nil"
+	_ = s + nil   // ERROR "invalid operation.*mismatched types.*string and nil|(untyped nil)"
 )
 
 var (
@@ -31,7 +31,7 @@
 var (
 	_ = b + 1         // ERROR "invalid operation.*mismatched types.*bool and untyped int"
 	_ = i + false     // ERROR "invalid operation.*mismatched types.*int and untyped bool"
-	_ = iface + 1     // ERROR "invalid operation.*mismatched types.*interface {} and int"
-	_ = iface + 1.0   // ERROR "invalid operation.*mismatched types.*interface {} and float64"
-	_ = iface + false // ERROR "invalid operation.*mismatched types.*interface {} and bool"
+	_ = iface + 1     // ERROR "invalid operation.*mismatched types.*interface *{} and int"
+	_ = iface + 1.0   // ERROR "invalid operation.*mismatched types.*interface *{} and float64"
+	_ = iface + false // ERROR "invalid operation.*mismatched types.*interface *{} and bool"
 )
diff --git a/test/fixedbugs/issue46903.go b/test/fixedbugs/issue46903.go
new file mode 100644
index 0000000..3237a58
--- /dev/null
+++ b/test/fixedbugs/issue46903.go
@@ -0,0 +1,32 @@
+// run
+//go:build goexperiment.unified
+// +build goexperiment.unified
+
+// TODO(mdempsky): Enable test unconditionally. This test should pass
+// for non-unified mode too.
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+//go:notinheap
+type A struct{ B }
+type B struct{ x byte }
+type I interface{ M() *B }
+
+func (p *B) M() *B { return p }
+
+var (
+	a A
+	i I = &a
+)
+
+func main() {
+	got, want := i.M(), &a.B
+	if got != want {
+		println(got, "!=", want)
+		panic("FAIL")
+	}
+}
diff --git a/test/fixedbugs/issue47227.go b/test/fixedbugs/issue47227.go
new file mode 100644
index 0000000..a14efc9
--- /dev/null
+++ b/test/fixedbugs/issue47227.go
@@ -0,0 +1,23 @@
+// run fake-arg-to-force-use-of-go-run
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build cgo
+// +build cgo
+
+package main
+
+// void f(int *p) { *p = 0x12345678; }
+import "C"
+
+func main() {
+	var x C.int
+	func() {
+		defer C.f(&x)
+	}()
+	if x != 0x12345678 {
+		panic("FAIL")
+	}
+}
diff --git a/test/fixedbugs/issue4909b.go b/test/fixedbugs/issue4909b.go
index 0f594e3..7d792270 100644
--- a/test/fixedbugs/issue4909b.go
+++ b/test/fixedbugs/issue4909b.go
@@ -73,7 +73,7 @@
 		}
 		fmt.Print(")")
 		if isIndirect {
-			fmt.Print(` // ERROR "indirection"`)
+			fmt.Print(` // ERROR "indirection|embedded via a pointer"`)
 		}
 		fmt.Print("\n")
 	}
diff --git a/test/fixedbugs/issue8042.go b/test/fixedbugs/issue8042.go
index 5639f97..be15ef0 100644
--- a/test/fixedbugs/issue8042.go
+++ b/test/fixedbugs/issue8042.go
@@ -9,7 +9,7 @@
 
 package p
 
-func _() {
+func f1() {
 	goto L1
 	const x = 0
 L1:
@@ -18,7 +18,7 @@
 L2:
 }
 
-func _() {
+func f2() {
 	{
 		goto L1
 	}
@@ -31,7 +31,7 @@
 L2:
 }
 
-func _(d int) {
+func f3(d int) {
 	if d > 0 {
 		goto L1
 	} else {
diff --git a/test/fixedbugs/issue8761.go b/test/fixedbugs/issue8761.go
index 7f458f7..e5130e1 100644
--- a/test/fixedbugs/issue8761.go
+++ b/test/fixedbugs/issue8761.go
@@ -10,17 +10,17 @@
 
 package p
 
-func _() {
+func f1() {
 	type C chan int
 	_ = [1][]C{[]C{make(chan int)}}
 }
 
-func _() {
+func f2() {
 	type C interface{}
 	_ = [1][]C{[]C{recover()}}
 }
 
-func _() {
+func f3() {
 	type C *int
 	_ = [1][]C{[]C{new(int)}}
 }
diff --git a/test/inline.go b/test/inline.go
index 472a941..a73c0ba 100644
--- a/test/inline.go
+++ b/test/inline.go
@@ -1,4 +1,4 @@
-// errorcheck -0 -m -d=inlfuncswithclosures=1
+// errorcheckwithauto -0 -m -d=inlfuncswithclosures=1
 
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -49,7 +49,7 @@
 	}
 }
 
-func _() int { // ERROR "can inline _"
+func f2() int { // ERROR "can inline f2"
 	tmp1 := h
 	tmp2 := tmp1
 	return tmp2(0) // ERROR "inlining call to h"
@@ -167,8 +167,9 @@
 
 func k() (T, int, int) { return T{}, 0, 0 } // ERROR "can inline k"
 
-func _() { // ERROR "can inline _"
+func f3() { // ERROR "can inline f3"
 	T.meth(k()) // ERROR "inlining call to k" "inlining call to T.meth"
+	// ERRORAUTO "inlining call to T.meth"
 }
 
 func small1() { // ERROR "can inline small1"
@@ -232,12 +233,13 @@
 // Issue #18493 - make sure we can do inlining of functions with a method value
 type T1 struct{}
 
-func (a T1) meth(val int) int { // ERROR "can inline T1.meth" "inlining call to T1.meth"
+func (a T1) meth(val int) int { // ERROR "can inline T1.meth"
 	return val + 5
 }
 
 func getMeth(t1 T1) func(int) int { // ERROR "can inline getMeth"
 	return t1.meth // ERROR "t1.meth escapes to heap"
+	// ERRORAUTO "inlining call to T1.meth"
 }
 
 func ii() { // ERROR "can inline ii"
diff --git a/test/inline_big.go b/test/inline_big.go
index 68e1101..8367275 100644
--- a/test/inline_big.go
+++ b/test/inline_big.go
@@ -1023,7 +1023,7 @@
 	a[997] = 0
 	a[998] = 0
 	a[999] = 0
-	x := small(a)  // ERROR "inlining call to small .*"
+	x := small(a)  // ERROR "inlining call to small"
 	y := medium(a) // The crux of this test: medium is not inlined.
 	return x + y
 }
diff --git a/test/inline_variadic.go b/test/inline_variadic.go
index 687048a..49483d7 100644
--- a/test/inline_variadic.go
+++ b/test/inline_variadic.go
@@ -14,6 +14,6 @@
 }
 
 func f() string { // ERROR "can inline f"
-	x := head("hello", "world") // ERROR "inlining call to head" "\[\]string{...} does not escape"
+	x := head("hello", "world") // ERROR "inlining call to head" "\.\.\. argument does not escape"
 	return x
 }
diff --git a/test/live.go b/test/live.go
index bc7b384..6130f7f 100644
--- a/test/live.go
+++ b/test/live.go
@@ -1,5 +1,5 @@
 // errorcheckwithauto -0 -l -live -wb=0 -d=ssa/insert_resched_checks/off
-// +build !ppc64,!ppc64le,!goexperiment.regabi,!goexperiment.regabidefer
+// +build !ppc64,!ppc64le,!goexperiment.regabiargs
 
 // ppc64 needs a better tighten pass to make f18 pass
 // rescheduling checks need to be turned off because there are some live variables across the inserted check call
@@ -144,8 +144,8 @@
 func f9() bool {
 	g8()
 	x := i9
-	y := interface{}(g18()) // ERROR "live at call to convT2E: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
-	i9 = y                  // make y escape so the line above has to call convT2E
+	y := interface{}(g18()) // ERROR "live at call to convT: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
+	i9 = y                  // make y escape so the line above has to call convT
 	return x != y
 }
 
@@ -424,7 +424,7 @@
 	}
 	defer call27(func() { x++ }) // ERROR "stack object .autotmp_[0-9]+ struct \{"
 	printnl()                    // ERROR "live at call to printnl: .autotmp_[0-9]+ .autotmp_[0-9]+"
-	return                       // ERROR "live at call to call27: .autotmp_[0-9]+"
+	return                       // ERROR "live at indirect call: .autotmp_[0-9]+"
 }
 
 // and newproc (go) escapes to the heap
@@ -432,9 +432,9 @@
 func f27go(b bool) {
 	x := 0
 	if b {
-		go call27(func() { x++ }) // ERROR "live at call to newobject: &x$" "live at call to newproc: &x$"
+		go call27(func() { x++ }) // ERROR "live at call to newobject: &x$" "live at call to newobject: &x .autotmp_[0-9]+$" "live at call to newproc: &x$" // allocate two closures, the func literal, and the wrapper for go
 	}
-	go call27(func() { x++ }) // ERROR "live at call to newobject: &x$"
+	go call27(func() { x++ }) // ERROR "live at call to newobject: &x$" "live at call to newobject: .autotmp_[0-9]+$" // allocate two closures, the func literal, and the wrapper for go
 	printnl()
 }
 
@@ -503,7 +503,7 @@
 		g31(g18()) // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
 	}
 	if b2 {
-		h31(g18()) // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
+		h31(g18()) // ERROR "live at call to convT: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
 	}
 	if b3 {
 		panic(g18())
@@ -688,7 +688,7 @@
 
 func (*T) Foo(ptr *int) {}
 
-type R struct{ *T } // ERRORAUTO "live at entry to \(\*R\)\.Foo: \.this ptr" "live at entry to R\.Foo: \.this ptr"
+type R struct{ *T }
 
 // issue 18860: output arguments must be live all the time if there is a defer.
 // In particular, at printint r must be live.
diff --git a/test/live_regabi.go b/test/live_regabi.go
index 2b0278e..2883b83 100644
--- a/test/live_regabi.go
+++ b/test/live_regabi.go
@@ -1,5 +1,5 @@
 // errorcheckwithauto -0 -l -live -wb=0 -d=ssa/insert_resched_checks/off
-// +build amd64,goexperiment.regabidefer,goexperiment.regabiargs
+// +build amd64,goexperiment.regabiargs
 
 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -139,8 +139,8 @@
 func f9() bool {
 	g8()
 	x := i9
-	y := interface{}(g18()) // ERROR "live at call to convT2E: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
-	i9 = y                  // make y escape so the line above has to call convT2E
+	y := interface{}(g18()) // ERROR "live at call to convT: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
+	i9 = y                  // make y escape so the line above has to call convT
 	return x != y
 }
 
@@ -498,7 +498,7 @@
 		g31(g18()) // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
 	}
 	if b2 {
-		h31(g18()) // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
+		h31(g18()) // ERROR "live at call to convT: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
 	}
 	if b3 {
 		panic(g18())
@@ -683,7 +683,7 @@
 
 func (*T) Foo(ptr *int) {}
 
-type R struct{ *T } // ERRORAUTO "live at entry to \(\*R\)\.Foo: \.this ptr" "live at entry to R\.Foo: \.this ptr"
+type R struct{ *T }
 
 // issue 18860: output arguments must be live all the time if there is a defer.
 // In particular, at printint r must be live.
diff --git a/test/reflectmethod8.go b/test/reflectmethod8.go
new file mode 100644
index 0000000..482163b
--- /dev/null
+++ b/test/reflectmethod8.go
@@ -0,0 +1,26 @@
+// compile
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Make sure that the compiler can analyze non-reflect
+// Type.{Method,MethodByName} calls.
+
+package p
+
+type I interface {
+	MethodByName(string)
+	Method(int)
+}
+
+type M struct{}
+
+func (M) MethodByName(string) {}
+func (M) Method(int)          {}
+
+func f() {
+	var m M
+	I.MethodByName(m, "")
+	I.Method(m, 42)
+}
diff --git a/test/run.go b/test/run.go
index d7f5d02..6296234 100644
--- a/test/run.go
+++ b/test/run.go
@@ -9,6 +9,7 @@
 
 import (
 	"bytes"
+	"encoding/json"
 	"errors"
 	"flag"
 	"fmt"
@@ -42,11 +43,55 @@
 	linkshared     = flag.Bool("linkshared", false, "")
 	updateErrors   = flag.Bool("update_errors", false, "update error messages in test file based on compiler output")
 	runoutputLimit = flag.Int("l", defaultRunOutputLimit(), "number of parallel runoutput tests to run")
+	force          = flag.Bool("f", false, "ignore expected-failure test lists")
+	generics       = flag.String("G", defaultGLevels, "a comma-separated list of -G compiler flags to test with")
 
 	shard  = flag.Int("shard", 0, "shard index to run. Only applicable if -shards is non-zero.")
 	shards = flag.Int("shards", 0, "number of shards. If 0, all tests are run. This is used by the continuous build.")
 )
 
+type envVars struct {
+	GOOS         string
+	GOARCH       string
+	GOEXPERIMENT string
+	CGO_ENABLED  string
+}
+
+var env = func() (res envVars) {
+	cmd := exec.Command("go", "env", "-json")
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		log.Fatal("StdoutPipe:", err)
+	}
+	if err := cmd.Start(); err != nil {
+		log.Fatal("Start:", err)
+	}
+	if err := json.NewDecoder(stdout).Decode(&res); err != nil {
+		log.Fatal("Decode:", err)
+	}
+	if err := cmd.Wait(); err != nil {
+		log.Fatal("Wait:", err)
+	}
+	return
+}()
+
+var unifiedEnabled, defaultGLevels = func() (bool, string) {
+	// TODO(mdempsky): This will give false negatives if the unified
+	// experiment is enabled by default, but presumably at that point we
+	// won't need to disable tests for it anymore anyway.
+	enabled := strings.Contains(","+env.GOEXPERIMENT+",", ",unified,")
+
+	// Normal test runs should test with both -G=0 and -G=3 for types2
+	// coverage. But the unified experiment always uses types2, so
+	// testing with -G=3 is redundant.
+	glevels := "0,3"
+	if enabled {
+		glevels = "0"
+	}
+
+	return enabled, glevels
+}()
+
 // defaultAllCodeGen returns the default value of the -all_codegen
 // flag. By default, we prefer to be fast (returning false), except on
 // the linux-amd64 builder that's already very fast, so we get more
@@ -56,12 +101,13 @@
 }
 
 var (
-	goos, goarch string
-	cgoEnabled   bool
+	goos          = env.GOOS
+	goarch        = env.GOARCH
+	cgoEnabled, _ = strconv.ParseBool(env.CGO_ENABLED)
 
 	// dirs are the directories to look for *.go files in.
 	// TODO(bradfitz): just use all directories?
-	dirs = []string{".", "ken", "chan", "interface", "syntax", "dwarf", "fixedbugs", "codegen", "runtime", "abi", "typeparam"}
+	dirs = []string{".", "ken", "chan", "interface", "syntax", "dwarf", "fixedbugs", "codegen", "runtime", "abi", "typeparam", "typeparam/mdempsky"}
 
 	// ratec controls the max number of tests running at a time.
 	ratec chan bool
@@ -82,11 +128,13 @@
 func main() {
 	flag.Parse()
 
-	goos = getenv("GOOS", runtime.GOOS)
-	goarch = getenv("GOARCH", runtime.GOARCH)
-	cgoEnv, err := exec.Command(goTool(), "env", "CGO_ENABLED").Output()
-	if err == nil {
-		cgoEnabled, _ = strconv.ParseBool(strings.TrimSpace(string(cgoEnv)))
+	var glevels []int
+	for _, s := range strings.Split(*generics, ",") {
+		glevel, err := strconv.Atoi(s)
+		if err != nil {
+			log.Fatalf("invalid -G flag: %v", err)
+		}
+		glevels = append(glevels, glevel)
 	}
 
 	findExecCmd()
@@ -113,11 +161,11 @@
 			}
 			if fi, err := os.Stat(arg); err == nil && fi.IsDir() {
 				for _, baseGoFile := range goFiles(arg) {
-					tests = append(tests, startTest(arg, baseGoFile))
+					tests = append(tests, startTests(arg, baseGoFile, glevels)...)
 				}
 			} else if strings.HasSuffix(arg, ".go") {
 				dir, file := filepath.Split(arg)
-				tests = append(tests, startTest(dir, file))
+				tests = append(tests, startTests(dir, file, glevels)...)
 			} else {
 				log.Fatalf("can't yet deal with non-directory and non-go file %q", arg)
 			}
@@ -125,7 +173,7 @@
 	} else {
 		for _, dir := range dirs {
 			for _, baseGoFile := range goFiles(dir) {
-				tests = append(tests, startTest(dir, baseGoFile))
+				tests = append(tests, startTests(dir, baseGoFile, glevels)...)
 			}
 		}
 	}
@@ -142,8 +190,15 @@
 			status = "FAIL"
 		}
 		if test.err != nil {
-			status = "FAIL"
 			errStr = test.err.Error()
+			if test.expectFail {
+				errStr += " (expected)"
+			} else {
+				status = "FAIL"
+			}
+		} else if test.expectFail {
+			status = "FAIL"
+			errStr = "unexpected success"
 		}
 		if status == "FAIL" {
 			failed = true
@@ -151,7 +206,8 @@
 		resCount[status]++
 		dt := fmt.Sprintf("%.3fs", test.dt.Seconds())
 		if status == "FAIL" {
-			fmt.Printf("# go run run.go -- %s\n%s\nFAIL\t%s\t%s\n",
+			fmt.Printf("# go run run.go -G=%v %s\n%s\nFAIL\t%s\t%s\n",
+				test.glevel,
 				path.Join(test.dir, test.gofile),
 				errStr, test.goFileName(), dt)
 			continue
@@ -270,30 +326,73 @@
 	dir, gofile string
 	donec       chan bool // closed when done
 	dt          time.Duration
+	glevel      int // what -G level this test should use
 
 	src string
 
 	tempDir string
 	err     error
+
+	// expectFail indicates whether the (overall) test recipe is
+	// expected to fail under the current test configuration (e.g., -G=3
+	// or GOEXPERIMENT=unified).
+	expectFail bool
 }
 
-// startTest
-func startTest(dir, gofile string) *test {
-	t := &test{
-		dir:    dir,
-		gofile: gofile,
-		donec:  make(chan bool, 1),
+// initExpectFail initializes t.expectFail based on the build+test
+// configuration. It should only be called for tests known to use
+// types2.
+func (t *test) initExpectFail() {
+	if *force {
+		return
 	}
-	if toRun == nil {
-		toRun = make(chan *test, maxTests)
-		go runTests()
+
+	failureSets := []map[string]bool{types2Failures}
+
+	// Note: gccgo supports more 32-bit architectures than this, but
+	// hopefully the 32-bit failures are fixed before this matters.
+	switch goarch {
+	case "386", "arm", "mips", "mipsle":
+		failureSets = append(failureSets, types2Failures32Bit)
 	}
-	select {
-	case toRun <- t:
-	default:
-		panic("toRun buffer size (maxTests) is too small")
+
+	if unifiedEnabled {
+		failureSets = append(failureSets, unifiedFailures)
+	} else {
+		failureSets = append(failureSets, g3Failures)
 	}
-	return t
+
+	filename := strings.Replace(t.goFileName(), "\\", "/", -1) // goFileName() uses \ on Windows
+
+	for _, set := range failureSets {
+		if set[filename] {
+			t.expectFail = true
+			return
+		}
+	}
+}
+
+func startTests(dir, gofile string, glevels []int) []*test {
+	tests := make([]*test, len(glevels))
+	for i, glevel := range glevels {
+		t := &test{
+			dir:    dir,
+			gofile: gofile,
+			glevel: glevel,
+			donec:  make(chan bool, 1),
+		}
+		if toRun == nil {
+			toRun = make(chan *test, maxTests)
+			go runTests()
+		}
+		select {
+		case toRun <- t:
+		default:
+			panic("toRun buffer size (maxTests) is too small")
+		}
+		tests[i] = t
+	}
+	return tests
 }
 
 // runTests runs tests in parallel, but respecting the order they
@@ -480,12 +579,16 @@
 // This must match the flags used for building the standard library,
 // or else the commands will rebuild any needed packages (like runtime)
 // over and over.
-func goGcflags() string {
-	return "-gcflags=all=" + os.Getenv("GO_GCFLAGS")
+func (t *test) goGcflags() string {
+	flags := os.Getenv("GO_GCFLAGS")
+	if t.glevel != 0 {
+		flags = fmt.Sprintf("%s -G=%v", flags, t.glevel)
+	}
+	return "-gcflags=all=" + flags
 }
 
-func goGcflagsIsEmpty() bool {
-	return "" == os.Getenv("GO_GCFLAGS")
+func (t *test) goGcflagsIsEmpty() bool {
+	return "" == os.Getenv("GO_GCFLAGS") && t.glevel == 0
 }
 
 var errTimeout = errors.New("command exceeded time limit")
@@ -541,7 +644,11 @@
 	singlefilepkgs := false
 	setpkgpaths := false
 	localImports := true
-	f := strings.Fields(action)
+	f, err := splitQuoted(action)
+	if err != nil {
+		t.err = fmt.Errorf("invalid test recipe: %v", err)
+		return
+	}
 	if len(f) > 0 {
 		action = f[0]
 		args = f[1:]
@@ -569,6 +676,8 @@
 		return
 	}
 
+	goexp := env.GOEXPERIMENT
+
 	// collect flags
 	for len(args) > 0 && strings.HasPrefix(args[0], "-") {
 		switch args[0] {
@@ -595,7 +704,11 @@
 			}
 		case "-goexperiment": // set GOEXPERIMENT environment
 			args = args[1:]
-			runenv = append(runenv, "GOEXPERIMENT="+args[0])
+			if goexp != "" {
+				goexp += ","
+			}
+			goexp += args[0]
+			runenv = append(runenv, "GOEXPERIMENT="+goexp)
 
 		default:
 			flags = append(flags, args[0])
@@ -616,6 +729,63 @@
 		}
 	}
 
+	type Tool int
+
+	const (
+		_ Tool = iota
+		AsmCheck
+		Build
+		Run
+		Compile
+	)
+
+	// validForGLevel reports whether the current test is valid to run
+	// at the specified -G level. If so, it may update flags as
+	// necessary to test with -G.
+	validForGLevel := func(tool Tool) bool {
+		hasGFlag := false
+		for _, flag := range flags {
+			if strings.Contains(flag, "-G") {
+				hasGFlag = true
+			}
+		}
+
+		if hasGFlag && t.glevel != 0 {
+			// test provides explicit -G flag already; don't run again
+			if *verbose {
+				fmt.Printf("excl\t%s\n", t.goFileName())
+			}
+			return false
+		}
+
+		if t.glevel == 0 && !hasGFlag && !unifiedEnabled {
+			// tests should always pass when run w/o types2 (i.e., using the
+			// legacy typechecker).
+			return true
+		}
+
+		t.initExpectFail()
+
+		switch tool {
+		case Build, Run:
+			// ok; handled in goGcflags
+
+		case Compile:
+			if !hasGFlag {
+				flags = append(flags, fmt.Sprintf("-G=%v", t.glevel))
+			}
+
+		default:
+			// we don't know how to add -G for this test yet
+			if *verbose {
+				fmt.Printf("excl\t%s\n", t.goFileName())
+			}
+			return false
+		}
+
+		return true
+	}
+
 	t.makeTempDir()
 	if !*keep {
 		defer os.RemoveAll(t.tempDir)
@@ -692,6 +862,10 @@
 		t.err = fmt.Errorf("unimplemented action %q", action)
 
 	case "asmcheck":
+		if !validForGLevel(AsmCheck) {
+			return
+		}
+
 		// Compile Go file and match the generated assembly
 		// against a set of regexps in comments.
 		ops := t.wantedAsmOpcodes(long)
@@ -746,6 +920,10 @@
 		return
 
 	case "errorcheck":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		// Compile Go file.
 		// Fail if wantError is true and compilation was successful and vice versa.
 		// Match errors produced by gc against errors in comments.
@@ -774,72 +952,20 @@
 			t.updateErrors(string(out), long)
 		}
 		t.err = t.errorCheck(string(out), wantAuto, long, t.gofile)
-		if t.err != nil {
-			return // don't hide error if run below succeeds
-		}
-
-		// The following is temporary scaffolding to get types2 typechecker
-		// up and running against the existing test cases. The explicitly
-		// listed files don't pass yet, usually because the error messages
-		// are slightly different (this list is not complete). Any errorcheck
-		// tests that require output from analysis phases past initial type-
-		// checking are also excluded since these phases are not running yet.
-		// We can get rid of this code once types2 is fully plugged in.
-
-		// For now we're done when we can't handle the file or some of the flags.
-		// The first goal is to eliminate the excluded list; the second goal is to
-		// eliminate the flag list.
-
-		// Excluded files.
-		filename := strings.Replace(t.goFileName(), "\\", "/", -1) // goFileName() uses \ on Windows
-		if excluded[filename] {
-			if *verbose {
-				fmt.Printf("excl\t%s\n", filename)
-			}
-			return // cannot handle file yet
-		}
-
-		// Excluded flags.
-		for _, flag := range flags {
-			for _, pattern := range []string{
-				"-m",
-			} {
-				if strings.Contains(flag, pattern) {
-					if *verbose {
-						fmt.Printf("excl\t%s\t%s\n", filename, flags)
-					}
-					return // cannot handle flag
-				}
-			}
-		}
-
-		// Run errorcheck again with -G option (new typechecker).
-		cmdline = []string{goTool(), "tool", "compile", "-G=3", "-C", "-e", "-o", "a.o"}
-		// No need to add -dynlink even if linkshared if we're just checking for errors...
-		cmdline = append(cmdline, flags...)
-		cmdline = append(cmdline, long)
-		out, err = runcmd(cmdline...)
-		if wantError {
-			if err == nil {
-				t.err = fmt.Errorf("compilation succeeded unexpectedly\n%s", out)
-				return
-			}
-		} else {
-			if err != nil {
-				t.err = err
-				return
-			}
-		}
-		if *updateErrors {
-			t.updateErrors(string(out), long)
-		}
-		t.err = t.errorCheck(string(out), wantAuto, long, t.gofile)
 
 	case "compile":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		// Compile Go file.
 		_, t.err = compileFile(runcmd, long, flags)
 
 	case "compiledir":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		// Compile all files in the directory as packages in lexicographic order.
 		longdir := filepath.Join(cwd, t.goDirName())
 		pkgs, err := goDirPackages(longdir, singlefilepkgs)
@@ -855,6 +981,10 @@
 		}
 
 	case "errorcheckdir", "errorcheckandrundir":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		flags = append(flags, "-d=panic")
 		// Compile and errorCheck all files in the directory as packages in lexicographic order.
 		// If errorcheckdir and wantError, compilation of the last package must fail.
@@ -900,6 +1030,10 @@
 		fallthrough
 
 	case "rundir":
+		if !validForGLevel(Run) {
+			return
+		}
+
 		// Compile all files in the directory as packages in lexicographic order.
 		// In case of errorcheckandrundir, ignore failed compilation of the package before the last.
 		// Link as if the last file is the main package, run it.
@@ -958,6 +1092,10 @@
 		}
 
 	case "runindir":
+		if !validForGLevel(Run) {
+			return
+		}
+
 		// Make a shallow copy of t.goDirName() in its own module and GOPATH, and
 		// run "go run ." in it. The module path (and hence import path prefix) of
 		// the copy is equal to the basename of the source directory.
@@ -983,7 +1121,7 @@
 			return
 		}
 
-		cmd := []string{goTool(), "run", goGcflags()}
+		cmd := []string{goTool(), "run", t.goGcflags()}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -997,13 +1135,21 @@
 		t.checkExpectedOutput(out)
 
 	case "build":
+		if !validForGLevel(Build) {
+			return
+		}
+
 		// Build Go file.
-		_, err := runcmd(goTool(), "build", goGcflags(), "-o", "a.exe", long)
+		_, err := runcmd(goTool(), "build", t.goGcflags(), "-o", "a.exe", long)
 		if err != nil {
 			t.err = err
 		}
 
 	case "builddir", "buildrundir":
+		if !validForGLevel(Build) {
+			return
+		}
+
 		// Build an executable from all the .go and .s files in a subdirectory.
 		// Run it and verify its output in the buildrundir case.
 		longdir := filepath.Join(cwd, t.goDirName())
@@ -1083,10 +1229,14 @@
 		}
 
 	case "buildrun":
+		if !validForGLevel(Build) {
+			return
+		}
+
 		// Build an executable from Go file, then run it, verify its output.
 		// Useful for timeout tests where failure mode is infinite loop.
 		// TODO: not supported on NaCl
-		cmd := []string{goTool(), "build", goGcflags(), "-o", "a.exe"}
+		cmd := []string{goTool(), "build", t.goGcflags(), "-o", "a.exe"}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -1108,13 +1258,17 @@
 		t.checkExpectedOutput(out)
 
 	case "run":
+		if !validForGLevel(Run) {
+			return
+		}
+
 		// Run Go file if no special go command flags are provided;
 		// otherwise build an executable and run it.
 		// Verify the output.
 		runInDir = ""
 		var out []byte
 		var err error
-		if len(flags)+len(args) == 0 && goGcflagsIsEmpty() && !*linkshared && goarch == runtime.GOARCH && goos == runtime.GOOS {
+		if len(flags)+len(args) == 0 && t.goGcflagsIsEmpty() && !*linkshared && goarch == runtime.GOARCH && goos == runtime.GOOS && goexp == env.GOEXPERIMENT {
 			// If we're not using special go command flags,
 			// skip all the go command machinery.
 			// This avoids any time the go command would
@@ -1136,7 +1290,7 @@
 			}
 			out, err = runcmd(append([]string{exe}, args...)...)
 		} else {
-			cmd := []string{goTool(), "run", goGcflags()}
+			cmd := []string{goTool(), "run", t.goGcflags()}
 			if *linkshared {
 				cmd = append(cmd, "-linkshared")
 			}
@@ -1151,6 +1305,10 @@
 		t.checkExpectedOutput(out)
 
 	case "runoutput":
+		if !validForGLevel(Run) {
+			return
+		}
+
 		// Run Go file and write its output into temporary Go file.
 		// Run generated Go file and verify its output.
 		rungatec <- true
@@ -1158,7 +1316,7 @@
 			<-rungatec
 		}()
 		runInDir = ""
-		cmd := []string{goTool(), "run", goGcflags()}
+		cmd := []string{goTool(), "run", t.goGcflags()}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -1173,7 +1331,7 @@
 			t.err = fmt.Errorf("write tempfile:%s", err)
 			return
 		}
-		cmd = []string{goTool(), "run", goGcflags()}
+		cmd = []string{goTool(), "run", t.goGcflags()}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -1186,10 +1344,14 @@
 		t.checkExpectedOutput(out)
 
 	case "errorcheckoutput":
+		if !validForGLevel(Compile) {
+			return
+		}
+
 		// Run Go file and write its output into temporary Go file.
 		// Compile and errorCheck generated Go file.
 		runInDir = ""
-		cmd := []string{goTool(), "run", goGcflags()}
+		cmd := []string{goTool(), "run", t.goGcflags()}
 		if *linkshared {
 			cmd = append(cmd, "-linkshared")
 		}
@@ -1941,66 +2103,165 @@
 	})
 }
 
+// The following is temporary scaffolding to get types2 typechecker
+// up and running against the existing test cases. The explicitly
+// listed files don't pass yet, usually because the error messages
+// are slightly different (this list is not complete). Any errorcheck
+// tests that require output from analysis phases past initial type-
+// checking are also excluded since these phases are not running yet.
+// We can get rid of this code once types2 is fully plugged in.
+
 // List of files that the compiler cannot errorcheck with the new typechecker (compiler -G option).
 // Temporary scaffolding until we pass all the tests at which point this map can be removed.
-var excluded = map[string]bool{
-	"complit1.go":     true, // types2 reports extra errors
-	"const2.go":       true, // types2 not run after syntax errors
-	"ddd1.go":         true, // issue #42987
-	"directive.go":    true, // misplaced compiler directive checks
-	"float_lit3.go":   true, // types2 reports extra errors
-	"import1.go":      true, // types2 reports extra errors
-	"import5.go":      true, // issue #42988
-	"import6.go":      true, // issue #43109
-	"initializerr.go": true, // types2 reports extra errors
-	"linkname2.go":    true, // error reported by noder (not running for types2 errorcheck test)
-	"notinheap.go":    true, // types2 doesn't report errors about conversions that are invalid due to //go:notinheap
-	"shift1.go":       true, // issue #42989
-	"typecheck.go":    true, // invalid function is not causing errors when called
-	"writebarrier.go": true, // correct diagnostics, but different lines (probably irgen's fault)
+var types2Failures = setOf(
+	"directive.go",    // misplaced compiler directive checks
+	"float_lit3.go",   // types2 reports extra errors
+	"import1.go",      // types2 reports extra errors
+	"import6.go",      // issue #43109
+	"initializerr.go", // types2 reports extra errors
+	"linkname2.go",    // error reported by noder (not running for types2 errorcheck test)
+	"notinheap.go",    // types2 doesn't report errors about conversions that are invalid due to //go:notinheap
+	"shift1.go",       // issue #42989
+	"typecheck.go",    // invalid function is not causing errors when called
 
-	"fixedbugs/bug176.go":    true, // types2 reports all errors (pref: types2)
-	"fixedbugs/bug195.go":    true, // types2 reports slightly different (but correct) bugs
-	"fixedbugs/bug228.go":    true, // types2 not run after syntax errors
-	"fixedbugs/bug231.go":    true, // types2 bug? (same error reported twice)
-	"fixedbugs/bug255.go":    true, // types2 reports extra errors
-	"fixedbugs/bug351.go":    true, // types2 reports extra errors
-	"fixedbugs/bug374.go":    true, // types2 reports extra errors
-	"fixedbugs/bug385_32.go": true, // types2 doesn't produce missing error "type .* too large" (32-bit specific)
-	"fixedbugs/bug388.go":    true, // types2 not run due to syntax errors
-	"fixedbugs/bug412.go":    true, // types2 produces a follow-on error
+	"interface/private.go", // types2 phrases errors differently (doesn't use non-spec "private" term)
 
-	"fixedbugs/issue11590.go":  true, // types2 doesn't report a follow-on error (pref: types2)
-	"fixedbugs/issue11610.go":  true, // types2 not run after syntax errors
-	"fixedbugs/issue11614.go":  true, // types2 reports an extra error
-	"fixedbugs/issue13415.go":  true, // declared but not used conflict
-	"fixedbugs/issue14520.go":  true, // missing import path error by types2
-	"fixedbugs/issue16428.go":  true, // types2 reports two instead of one error
-	"fixedbugs/issue17038.go":  true, // types2 doesn't report a follow-on error (pref: types2)
-	"fixedbugs/issue17645.go":  true, // multiple errors on same line
-	"fixedbugs/issue18331.go":  true, // missing error about misuse of //go:noescape (irgen needs code from noder)
-	"fixedbugs/issue18393.go":  true, // types2 not run after syntax errors
-	"fixedbugs/issue19012.go":  true, // multiple errors on same line
-	"fixedbugs/issue20233.go":  true, // types2 reports two instead of one error (pref: compiler)
-	"fixedbugs/issue20245.go":  true, // types2 reports two instead of one error (pref: compiler)
-	"fixedbugs/issue20250.go":  true, // correct diagnostics, but different lines (probably irgen's fault)
-	"fixedbugs/issue21979.go":  true, // types2 doesn't report a follow-on error (pref: types2)
-	"fixedbugs/issue23732.go":  true, // types2 reports different (but ok) line numbers
-	"fixedbugs/issue25958.go":  true, // types2 doesn't report a follow-on error (pref: types2)
-	"fixedbugs/issue28079b.go": true, // types2 reports follow-on errors
-	"fixedbugs/issue28268.go":  true, // types2 reports follow-on errors
-	"fixedbugs/issue33460.go":  true, // types2 reports alternative positions in separate error
-	"fixedbugs/issue41575.go":  true, // types2 reports alternative positions in separate error
-	"fixedbugs/issue42058a.go": true, // types2 doesn't report "channel element type too large"
-	"fixedbugs/issue42058b.go": true, // types2 doesn't report "channel element type too large"
-	"fixedbugs/issue4232.go":   true, // types2 reports (correct) extra errors
-	"fixedbugs/issue4452.go":   true, // types2 reports (correct) extra errors
-	"fixedbugs/issue5609.go":   true, // types2 needs a better error message
-	"fixedbugs/issue6889.go":   true, // types2 can handle this without constant overflow
-	"fixedbugs/issue7525.go":   true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue7525b.go":  true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue7525c.go":  true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue7525d.go":  true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue7525e.go":  true, // types2 reports init cycle error on different line - ok otherwise
-	"fixedbugs/issue46749.go":  true, // types2 reports can not convert error instead of type mismatched
+	"fixedbugs/bug176.go", // types2 reports all errors (pref: types2)
+	"fixedbugs/bug195.go", // types2 reports slightly different (but correct) bugs
+	"fixedbugs/bug228.go", // types2 doesn't run when there are syntax errors
+	"fixedbugs/bug231.go", // types2 bug? (same error reported twice)
+	"fixedbugs/bug255.go", // types2 reports extra errors
+	"fixedbugs/bug374.go", // types2 reports extra errors
+	"fixedbugs/bug388.go", // types2 not run due to syntax errors
+	"fixedbugs/bug412.go", // types2 produces a follow-on error
+
+	"fixedbugs/issue10700.go",  // types2 reports ok hint, but does not match regexp
+	"fixedbugs/issue11590.go",  // types2 doesn't report a follow-on error (pref: types2)
+	"fixedbugs/issue11610.go",  // types2 not run after syntax errors
+	"fixedbugs/issue11614.go",  // types2 reports an extra error
+	"fixedbugs/issue14520.go",  // missing import path error by types2
+	"fixedbugs/issue16428.go",  // types2 reports two instead of one error
+	"fixedbugs/issue17038.go",  // types2 doesn't report a follow-on error (pref: types2)
+	"fixedbugs/issue17645.go",  // multiple errors on same line
+	"fixedbugs/issue18331.go",  // missing error about misuse of //go:noescape (irgen needs code from noder)
+	"fixedbugs/issue18419.go",  // types2 reports
+	"fixedbugs/issue19012.go",  // multiple errors on same line
+	"fixedbugs/issue20233.go",  // types2 reports two instead of one error (pref: compiler)
+	"fixedbugs/issue20245.go",  // types2 reports two instead of one error (pref: compiler)
+	"fixedbugs/issue21979.go",  // types2 doesn't report a follow-on error (pref: types2)
+	"fixedbugs/issue23732.go",  // types2 reports different (but ok) line numbers
+	"fixedbugs/issue25958.go",  // types2 doesn't report a follow-on error (pref: types2)
+	"fixedbugs/issue28079b.go", // types2 reports follow-on errors
+	"fixedbugs/issue28268.go",  // types2 reports follow-on errors
+	"fixedbugs/issue31053.go",  // types2 reports "unknown field" instead of "cannot refer to unexported field"
+	"fixedbugs/issue33460.go",  // types2 reports alternative positions in separate error
+	"fixedbugs/issue42058a.go", // types2 doesn't report "channel element type too large"
+	"fixedbugs/issue42058b.go", // types2 doesn't report "channel element type too large"
+	"fixedbugs/issue4232.go",   // types2 reports (correct) extra errors
+	"fixedbugs/issue4452.go",   // types2 reports (correct) extra errors
+	"fixedbugs/issue4510.go",   // types2 reports different (but ok) line numbers
+	"fixedbugs/issue47201.go",  // types2 spells the error message differently
+	"fixedbugs/issue5609.go",   // types2 needs a better error message
+	"fixedbugs/issue7525b.go",  // types2 reports init cycle error on different line - ok otherwise
+	"fixedbugs/issue7525c.go",  // types2 reports init cycle error on different line - ok otherwise
+	"fixedbugs/issue7525d.go",  // types2 reports init cycle error on different line - ok otherwise
+	"fixedbugs/issue7525e.go",  // types2 reports init cycle error on different line - ok otherwise
+	"fixedbugs/issue7525.go",   // types2 reports init cycle error on different line - ok otherwise
+)
+
+var types2Failures32Bit = setOf(
+	"printbig.go",             // large untyped int passed to print (32-bit)
+	"fixedbugs/bug114.go",     // large untyped int passed to println (32-bit)
+	"fixedbugs/issue23305.go", // large untyped int passed to println (32-bit)
+	"fixedbugs/bug385_32.go",  // types2 doesn't produce missing error "type .* too large" (32-bit specific)
+)
+
+var g3Failures = setOf(
+	"writebarrier.go", // correct diagnostics, but different lines (probably irgen's fault)
+
+	"fixedbugs/issue30862.go", // -G=3 doesn't handle //go:nointerface
+
+	"typeparam/nested.go", // -G=3 doesn't support function-local types with generics
+
+	"typeparam/mdempsky/4.go",  // -G=3 can't export functions with labeled breaks in loops
+	"typeparam/mdempsky/15.go", // ICE in (*irgen).buildClosure
+)
+
+var unifiedFailures = setOf(
+	"closure3.go", // unified IR numbers closures differently than -d=inlfuncswithclosures
+	"escape4.go",  // unified IR can inline f5 and f6; test doesn't expect this
+	"inline.go",   // unified IR reports function literal diagnostics on different lines than -d=inlfuncswithclosures
+
+	"fixedbugs/issue42284.go", // prints "T(0) does not escape", but test expects "a.I(a.T(0)) does not escape"
+	"fixedbugs/issue7921.go",  // prints "… escapes to heap", but test expects "string(…) escapes to heap"
+)
+
+func setOf(keys ...string) map[string]bool {
+	m := make(map[string]bool, len(keys))
+	for _, key := range keys {
+		m[key] = true
+	}
+	return m
+}
+
+// splitQuoted splits the string s around each instance of one or more consecutive
+// white space characters while taking into account quotes and escaping, and
+// returns an array of substrings of s or an empty list if s contains only white space.
+// Single quotes and double quotes are recognized to prevent splitting within the
+// quoted region, and are removed from the resulting substrings. If a quote in s
+// isn't closed err will be set and r will have the unclosed argument as the
+// last element. The backslash is used for escaping.
+//
+// For example, the following string:
+//
+//     a b:"c d" 'e''f'  "g\""
+//
+// Would be parsed as:
+//
+//     []string{"a", "b:c d", "ef", `g"`}
+//
+// [copied from src/go/build/build.go]
+func splitQuoted(s string) (r []string, err error) {
+	var args []string
+	arg := make([]rune, len(s))
+	escaped := false
+	quoted := false
+	quote := '\x00'
+	i := 0
+	for _, rune := range s {
+		switch {
+		case escaped:
+			escaped = false
+		case rune == '\\':
+			escaped = true
+			continue
+		case quote != '\x00':
+			if rune == quote {
+				quote = '\x00'
+				continue
+			}
+		case rune == '"' || rune == '\'':
+			quoted = true
+			quote = rune
+			continue
+		case unicode.IsSpace(rune):
+			if quoted || i > 0 {
+				quoted = false
+				args = append(args, string(arg[:i]))
+				i = 0
+			}
+			continue
+		}
+		arg[i] = rune
+		i++
+	}
+	if quoted || i > 0 {
+		args = append(args, string(arg[:i]))
+	}
+	if quote != 0 {
+		err = errors.New("unclosed quote")
+	} else if escaped {
+		err = errors.New("unfinished escaping")
+	}
+	return args, err
 }
diff --git a/test/typeparam/absdiff.go b/test/typeparam/absdiff.go
index 1381d7c..cad6e84 100644
--- a/test/typeparam/absdiff.go
+++ b/test/typeparam/absdiff.go
@@ -12,10 +12,10 @@
 )
 
 type Numeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		complex64, complex128
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~complex64 | ~complex128
 }
 
 // numericAbs matches numeric types with an Abs method.
@@ -33,14 +33,14 @@
 
 // orderedNumeric matches numeric types that support the < operator.
 type orderedNumeric interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
 }
 
 // Complex matches the two complex types, which do not have a < operator.
 type Complex interface {
-	type complex64, complex128
+	~complex64 | ~complex128
 }
 
 // orderedAbs is a helper type that defines an Abs method for
@@ -48,8 +48,7 @@
 type orderedAbs[T orderedNumeric] T
 
 func (a orderedAbs[T]) Abs() orderedAbs[T] {
-	// TODO(danscales): orderedAbs[T] conversion shouldn't be needed
-	if a < orderedAbs[T](0) {
+	if a < 0 {
 		return -a
 	}
 	return a
@@ -62,7 +61,7 @@
 func (a complexAbs[T]) Abs() complexAbs[T] {
 	r := float64(real(a))
 	i := float64(imag(a))
-	d := math.Sqrt(r * r + i * i)
+	d := math.Sqrt(r*r + i*i)
 	return complexAbs[T](complex(d, 0))
 }
 
@@ -89,10 +88,10 @@
 		panic(fmt.Sprintf("got = %v, want = %v", got, want))
 	}
 
-	if got, want := complexAbsDifference(5.0 + 2.0i, 2.0 - 2.0i), 5+0i; got != want {
+	if got, want := complexAbsDifference(5.0+2.0i, 2.0-2.0i), 5+0i; got != want {
 		panic(fmt.Sprintf("got = %v, want = %v", got, want))
 	}
-	if got, want := complexAbsDifference(2.0 - 2.0i, 5.0 + 2.0i), 5+0i; got != want {
+	if got, want := complexAbsDifference(2.0-2.0i, 5.0+2.0i), 5+0i; got != want {
 		panic(fmt.Sprintf("got = %v, want = %v", got, want))
 	}
 }
diff --git a/test/typeparam/absdiffimp.dir/a.go b/test/typeparam/absdiffimp.dir/a.go
new file mode 100644
index 0000000..7b5bfbe
--- /dev/null
+++ b/test/typeparam/absdiffimp.dir/a.go
@@ -0,0 +1,75 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+import (
+	"math"
+)
+
+type Numeric interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~complex64 | ~complex128
+}
+
+// numericAbs matches numeric types with an Abs method.
+type numericAbs[T any] interface {
+	Numeric
+	Abs() T
+}
+
+// AbsDifference computes the absolute value of the difference of
+// a and b, where the absolute value is determined by the Abs method.
+func absDifference[T numericAbs[T]](a, b T) T {
+	d := a - b
+	return d.Abs()
+}
+
+// orderedNumeric matches numeric types that support the < operator.
+type orderedNumeric interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
+}
+
+// Complex matches the two complex types, which do not have a < operator.
+type Complex interface {
+	~complex64 | ~complex128
+}
+
+// orderedAbs is a helper type that defines an Abs method for
+// ordered numeric types.
+type orderedAbs[T orderedNumeric] T
+
+func (a orderedAbs[T]) Abs() orderedAbs[T] {
+	if a < 0 {
+		return -a
+	}
+	return a
+}
+
+// complexAbs is a helper type that defines an Abs method for
+// complex types.
+type complexAbs[T Complex] T
+
+func (a complexAbs[T]) Abs() complexAbs[T] {
+	r := float64(real(a))
+	i := float64(imag(a))
+	d := math.Sqrt(r*r + i*i)
+	return complexAbs[T](complex(d, 0))
+}
+
+// OrderedAbsDifference returns the absolute value of the difference
+// between a and b, where a and b are of an ordered type.
+func OrderedAbsDifference[T orderedNumeric](a, b T) T {
+	return T(absDifference(orderedAbs[T](a), orderedAbs[T](b)))
+}
+
+// ComplexAbsDifference returns the absolute value of the difference
+// between a and b, where a and b are of a complex type.
+func ComplexAbsDifference[T Complex](a, b T) T {
+	return T(absDifference(complexAbs[T](a), complexAbs[T](b)))
+}
diff --git a/test/typeparam/absdiffimp.dir/main.go b/test/typeparam/absdiffimp.dir/main.go
new file mode 100644
index 0000000..8eefdbd
--- /dev/null
+++ b/test/typeparam/absdiffimp.dir/main.go
@@ -0,0 +1,29 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	if got, want := a.OrderedAbsDifference(1.0, -2.0), 3.0; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+	if got, want := a.OrderedAbsDifference(-1.0, 2.0), 3.0; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+	if got, want := a.OrderedAbsDifference(-20, 15), 35; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+
+	if got, want := a.ComplexAbsDifference(5.0+2.0i, 2.0-2.0i), 5+0i; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+	if got, want := a.ComplexAbsDifference(2.0-2.0i, 5.0+2.0i), 5+0i; got != want {
+		panic(fmt.Sprintf("got = %v, want = %v", got, want))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/absdiffimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/absdiffimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/absdiffimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/adder.go b/test/typeparam/adder.go
index 0c25ad4..79319bd 100644
--- a/test/typeparam/adder.go
+++ b/test/typeparam/adder.go
@@ -11,19 +11,19 @@
 )
 
 type AddType interface {
-	type int, int64, string
+	int | int64 | string
 }
 
-// _Add can add numbers or strings
-func _Add[T AddType](a, b T) T {
+// Add can add numbers or strings
+func Add[T AddType](a, b T) T {
 	return a + b
 }
 
 func main() {
-	if got, want := _Add(5, 3), 8; got != want {
+	if got, want := Add(5, 3), 8; got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
-	if got, want := _Add("ab", "cd"), "abcd"; got != want {
+	if got, want := Add("ab", "cd"), "abcd"; got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 }
diff --git a/test/typeparam/aliasimp.dir/a.go b/test/typeparam/aliasimp.dir/a.go
new file mode 100644
index 0000000..c64e87c
--- /dev/null
+++ b/test/typeparam/aliasimp.dir/a.go
@@ -0,0 +1,9 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Rimp[T any] struct {
+	F T
+}
diff --git a/test/typeparam/aliasimp.dir/main.go b/test/typeparam/aliasimp.dir/main.go
new file mode 100644
index 0000000..221a6c7
--- /dev/null
+++ b/test/typeparam/aliasimp.dir/main.go
@@ -0,0 +1,38 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "a"
+
+type R[T any] struct {
+	F T
+}
+
+type S = R
+
+type Sint = R[int]
+
+type Simp = a.Rimp
+
+type SimpString Simp[string]
+
+func main() {
+	var s S[int]
+	if s.F != 0 {
+		panic(s.F)
+	}
+	var s2 Sint
+	if s2.F != 0 {
+		panic(s2.F)
+	}
+	var s3 Simp[string]
+	if s3.F != "" {
+		panic(s3.F)
+	}
+	var s4 SimpString
+	if s4.F != "" {
+		panic(s4.F)
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/aliasimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/aliasimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/aliasimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/boundmethod.go b/test/typeparam/boundmethod.go
new file mode 100644
index 0000000..22f4164
--- /dev/null
+++ b/test/typeparam/boundmethod.go
@@ -0,0 +1,106 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This test illustrates how a type bound method (String below) can be implemented
+// either by a concrete type (myint below) or a instantiated generic type
+// (StringInt[myint] below).
+
+package main
+
+import (
+	"fmt"
+	"reflect"
+	"strconv"
+)
+
+type myint int
+
+//go:noinline
+func (m myint) String() string {
+	return strconv.Itoa(int(m))
+}
+
+type Stringer interface {
+	String() string
+}
+
+func stringify[T Stringer](s []T) (ret []string) {
+	for _, v := range s {
+		// Test normal bounds method call on type param
+		x1 := v.String()
+
+		// Test converting type param to its bound interface first
+		v1 := Stringer(v)
+		x2 := v1.String()
+
+		// Test method expression with type param type
+		f1 := T.String
+		x3 := f1(v)
+
+		// Test creating and calling closure equivalent to the method expression
+		f2 := func(v1 T) string {
+			return Stringer(v1).String()
+		}
+		x4 := f2(v)
+
+		if x1 != x2 || x2 != x3 || x3 != x4 {
+			panic(fmt.Sprintf("Mismatched values %v, %v, %v, %v\n", x1, x2, x3, x4))
+		}
+
+		ret = append(ret, v.String())
+	}
+	return ret
+}
+
+type Ints interface {
+	~int32 | ~int
+}
+
+type StringInt[T Ints] T
+
+//go:noinline
+func (m StringInt[T]) String() string {
+	return strconv.Itoa(int(m))
+}
+
+type StringStruct[T Ints] struct {
+	f T
+}
+
+func (m StringStruct[T]) String() string {
+	return strconv.Itoa(int(m.f))
+}
+
+func main() {
+	x := []myint{myint(1), myint(2), myint(3)}
+
+	// stringify on a normal type, whose bound method is associated with the base type.
+	got := stringify(x)
+	want := []string{"1", "2", "3"}
+	if !reflect.DeepEqual(got, want) {
+		panic(fmt.Sprintf("got %s, want %s", got, want))
+	}
+
+	x2 := []StringInt[myint]{StringInt[myint](5), StringInt[myint](7), StringInt[myint](6)}
+
+	// stringify on an instantiated type, whose bound method is associated with
+	// the generic type StringInt[T], which maps directly to T.
+	got2 := stringify(x2)
+	want2 := []string{ "5", "7", "6" }
+	if !reflect.DeepEqual(got2, want2) {
+		panic(fmt.Sprintf("got %s, want %s", got2, want2))
+	}
+
+	// stringify on an instantiated type, whose bound method is associated with
+	// the generic type StringStruct[T], which maps to a struct containing T.
+	x3 := []StringStruct[myint]{StringStruct[myint]{f: 11}, StringStruct[myint]{f: 10}, StringStruct[myint]{f: 9}}
+
+	got3 := stringify(x3)
+	want3 := []string{ "11", "10", "9" }
+	if !reflect.DeepEqual(got3, want3) {
+		panic(fmt.Sprintf("got %s, want %s", got3, want3))
+	}
+}
diff --git a/test/typeparam/builtins.go b/test/typeparam/builtins.go
new file mode 100644
index 0000000..844cdae
--- /dev/null
+++ b/test/typeparam/builtins.go
@@ -0,0 +1,111 @@
+// compile -G=3
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file tests built-in calls on generic types.
+
+// derived and expanded from cmd/compile/internal/types2/testdata/check/builtins.go2
+
+package builtins
+
+// close
+
+type C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func f1[T C1](ch T) {
+	close(ch)
+}
+
+func f2[T C3](ch T) {
+	close(ch)
+}
+
+func f3[T C4](ch T) {
+	close(ch)
+}
+
+func f4[T C5[X], X any](ch T) {
+	close(ch)
+}
+
+// delete
+
+type M0 interface{ int }
+type M1 interface{ map[string]int }
+type M2 interface {
+	map[string]int | map[string]float64
+}
+type M3 interface{ map[string]int | map[rune]int }
+type M4[K comparable, V any] interface{ map[K]V | map[rune]V }
+
+func g1[T M1](m T) {
+	delete(m, "foo")
+}
+
+func g2[T M2](m T) {
+	delete(m, "foo")
+}
+
+func g3[T M4[rune, V], V any](m T) {
+	delete(m, 'k')
+}
+
+// make
+
+func m1[
+	S1 interface{ []int },
+	S2 interface{ []int | chan int },
+
+	M1 interface{ map[string]int },
+	M2 interface{ map[string]int | chan int },
+
+	C1 interface{ chan int },
+	C2 interface{ chan int | chan string },
+]() {
+	type S0 []int
+	_ = make([]int, 10)
+	_ = make(S0, 10)
+	_ = make(S1, 10)
+	_ = make(S1, 10, 20)
+
+	type M0 map[string]int
+	_ = make(map[string]int)
+	_ = make(M0)
+	_ = make(M1)
+	_ = make(M1, 10)
+
+	type C0 chan int
+	_ = make(chan int)
+	_ = make(C0)
+	_ = make(C1)
+	_ = make(C1, 10)
+}
+
+// len/cap
+
+type Slice[T any] interface {
+	[]T
+}
+
+func c1[T any, S Slice[T]]() {
+	x := make(S, 5, 10)
+	_ = len(x)
+	_ = cap(x)
+}
+
+// append
+
+func a1[T any, S Slice[T]]() {
+	x := make(S, 5)
+	y := make(S, 2)
+	var z T
+	_ = append(x, y...)
+	_ = append(x, z)
+}
diff --git a/test/typeparam/chans.go b/test/typeparam/chans.go
index 2fcd4af..c30c21c 100644
--- a/test/typeparam/chans.go
+++ b/test/typeparam/chans.go
@@ -183,7 +183,7 @@
 		values: c,
 		done:   d,
 	}
-	r := &_Receiver[Elem] {
+	r := &_Receiver[Elem]{
 		values: c,
 		done:   d,
 	}
diff --git a/test/typeparam/chansimp.dir/a.go b/test/typeparam/chansimp.dir/a.go
new file mode 100644
index 0000000..7321992
--- /dev/null
+++ b/test/typeparam/chansimp.dir/a.go
@@ -0,0 +1,232 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+import (
+	"context"
+	"runtime"
+)
+
+// Equal reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// ReadAll reads from c until the channel is closed or the context is
+// canceled, returning all the values read.
+func ReadAll[Elem any](ctx context.Context, c <-chan Elem) []Elem {
+	var r []Elem
+	for {
+		select {
+		case <-ctx.Done():
+			return r
+		case v, ok := <-c:
+			if !ok {
+				return r
+			}
+			r = append(r, v)
+		}
+	}
+}
+
+// Merge merges two channels into a single channel.
+// This will leave a goroutine running until either both channels are closed
+// or the context is canceled, at which point the returned channel is closed.
+func Merge[Elem any](ctx context.Context, c1, c2 <-chan Elem) <-chan Elem {
+	r := make(chan Elem)
+	go func(ctx context.Context, c1, c2 <-chan Elem, r chan<- Elem) {
+		defer close(r)
+		for c1 != nil || c2 != nil {
+			select {
+			case <-ctx.Done():
+				return
+			case v1, ok := <-c1:
+				if ok {
+					r <- v1
+				} else {
+					c1 = nil
+				}
+			case v2, ok := <-c2:
+				if ok {
+					r <- v2
+				} else {
+					c2 = nil
+				}
+			}
+		}
+	}(ctx, c1, c2, r)
+	return r
+}
+
+// Filter calls f on each value read from c. If f returns true the value
+// is sent on the returned channel. This will leave a goroutine running
+// until c is closed or the context is canceled, at which point the
+// returned channel is closed.
+func Filter[Elem any](ctx context.Context, c <-chan Elem, f func(Elem) bool) <-chan Elem {
+	r := make(chan Elem)
+	go func(ctx context.Context, c <-chan Elem, f func(Elem) bool, r chan<- Elem) {
+		defer close(r)
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case v, ok := <-c:
+				if !ok {
+					return
+				}
+				if f(v) {
+					r <- v
+				}
+			}
+		}
+	}(ctx, c, f, r)
+	return r
+}
+
+// Sink returns a channel that discards all values sent to it.
+// This will leave a goroutine running until the context is canceled
+// or the returned channel is closed.
+func Sink[Elem any](ctx context.Context) chan<- Elem {
+	r := make(chan Elem)
+	go func(ctx context.Context, r <-chan Elem) {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case _, ok := <-r:
+				if !ok {
+					return
+				}
+			}
+		}
+	}(ctx, r)
+	return r
+}
+
+// An Exclusive is a value that may only be used by a single goroutine
+// at a time. This is implemented using channels rather than a mutex.
+type Exclusive[Val any] struct {
+	c chan Val
+}
+
+// MakeExclusive makes an initialized exclusive value.
+func MakeExclusive[Val any](initial Val) *Exclusive[Val] {
+	r := &Exclusive[Val]{
+		c: make(chan Val, 1),
+	}
+	r.c <- initial
+	return r
+}
+
+// Acquire acquires the exclusive value for private use.
+// It must be released using the Release method.
+func (e *Exclusive[Val]) Acquire() Val {
+	return <-e.c
+}
+
+// TryAcquire attempts to acquire the value. The ok result reports whether
+// the value was acquired. If the value is acquired, it must be released
+// using the Release method.
+func (e *Exclusive[Val]) TryAcquire() (v Val, ok bool) {
+	select {
+	case r := <-e.c:
+		return r, true
+	default:
+		return v, false
+	}
+}
+
+// Release updates and releases the value.
+// This method panics if the value has not been acquired.
+func (e *Exclusive[Val]) Release(v Val) {
+	select {
+	case e.c <- v:
+	default:
+		panic("Exclusive Release without Acquire")
+	}
+}
+
+// Ranger returns a Sender and a Receiver. The Receiver provides a
+// Next method to retrieve values. The Sender provides a Send method
+// to send values and a Close method to stop sending values. The Next
+// method indicates when the Sender has been closed, and the Send
+// method indicates when the Receiver has been freed.
+//
+// This is a convenient way to exit a goroutine sending values when
+// the receiver stops reading them.
+func Ranger[Elem any]() (*Sender[Elem], *Receiver[Elem]) {
+	c := make(chan Elem)
+	d := make(chan struct{})
+	s := &Sender[Elem]{
+		values: c,
+		done:   d,
+	}
+	r := &Receiver[Elem]{
+		values: c,
+		done:   d,
+	}
+	runtime.SetFinalizer(r, (*Receiver[Elem]).finalize)
+	return s, r
+}
+
+// A Sender is used to send values to a Receiver.
+type Sender[Elem any] struct {
+	values chan<- Elem
+	done   <-chan struct{}
+}
+
+// Send sends a value to the receiver. It reports whether the value was sent.
+// The value will not be sent if the context is closed or the receiver
+// is freed.
+func (s *Sender[Elem]) Send(ctx context.Context, v Elem) bool {
+	select {
+	case <-ctx.Done():
+		return false
+	case s.values <- v:
+		return true
+	case <-s.done:
+		return false
+	}
+}
+
+// Close tells the receiver that no more values will arrive.
+// After Close is called, the Sender may no longer be used.
+func (s *Sender[Elem]) Close() {
+	close(s.values)
+}
+
+// A Receiver receives values from a Sender.
+type Receiver[Elem any] struct {
+	values <-chan Elem
+	done   chan<- struct{}
+}
+
+// Next returns the next value from the channel. The bool result indicates
+// whether the value is valid.
+func (r *Receiver[Elem]) Next(ctx context.Context) (v Elem, ok bool) {
+	select {
+	case <-ctx.Done():
+	case v, ok = <-r.values:
+	}
+	return v, ok
+}
+
+// finalize is a finalizer for the receiver.
+func (r *Receiver[Elem]) finalize() {
+	close(r.done)
+}
diff --git a/test/typeparam/chansimp.dir/main.go b/test/typeparam/chansimp.dir/main.go
new file mode 100644
index 0000000..ca27167
--- /dev/null
+++ b/test/typeparam/chansimp.dir/main.go
@@ -0,0 +1,189 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"context"
+	"fmt"
+	"runtime"
+	"sort"
+	"sync"
+	"time"
+)
+
+func TestReadAll() {
+	c := make(chan int)
+	go func() {
+		c <- 4
+		c <- 2
+		c <- 5
+		close(c)
+	}()
+	got := a.ReadAll(context.Background(), c)
+	want := []int{4, 2, 5}
+	if !a.SliceEqual(got, want) {
+		panic(fmt.Sprintf("ReadAll returned %v, want %v", got, want))
+	}
+}
+
+func TestMerge() {
+	c1 := make(chan int)
+	c2 := make(chan int)
+	go func() {
+		c1 <- 1
+		c1 <- 3
+		c1 <- 5
+		close(c1)
+	}()
+	go func() {
+		c2 <- 2
+		c2 <- 4
+		c2 <- 6
+		close(c2)
+	}()
+	ctx := context.Background()
+	got := a.ReadAll(ctx, a.Merge(ctx, c1, c2))
+	sort.Ints(got)
+	want := []int{1, 2, 3, 4, 5, 6}
+	if !a.SliceEqual(got, want) {
+		panic(fmt.Sprintf("Merge returned %v, want %v", got, want))
+	}
+}
+
+func TestFilter() {
+	c := make(chan int)
+	go func() {
+		c <- 1
+		c <- 2
+		c <- 3
+		close(c)
+	}()
+	even := func(i int) bool { return i%2 == 0 }
+	ctx := context.Background()
+	got := a.ReadAll(ctx, a.Filter(ctx, c, even))
+	want := []int{2}
+	if !a.SliceEqual(got, want) {
+		panic(fmt.Sprintf("Filter returned %v, want %v", got, want))
+	}
+}
+
+func TestSink() {
+	c := a.Sink[int](context.Background())
+	after := time.NewTimer(time.Minute)
+	defer after.Stop()
+	send := func(v int) {
+		select {
+		case c <- v:
+		case <-after.C:
+			panic("timed out sending to Sink")
+		}
+	}
+	send(1)
+	send(2)
+	send(3)
+	close(c)
+}
+
+func TestExclusive() {
+	val := 0
+	ex := a.MakeExclusive(&val)
+
+	var wg sync.WaitGroup
+	f := func() {
+		defer wg.Done()
+		for i := 0; i < 10; i++ {
+			p := ex.Acquire()
+			(*p)++
+			ex.Release(p)
+		}
+	}
+
+	wg.Add(2)
+	go f()
+	go f()
+
+	wg.Wait()
+	if val != 20 {
+		panic(fmt.Sprintf("after Acquire/Release loop got %d, want 20", val))
+	}
+}
+
+func TestExclusiveTry() {
+	s := ""
+	ex := a.MakeExclusive(&s)
+	p, ok := ex.TryAcquire()
+	if !ok {
+		panic("TryAcquire failed")
+	}
+	*p = "a"
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_, ok := ex.TryAcquire()
+		if ok {
+			panic(fmt.Sprintf("TryAcquire succeeded unexpectedly"))
+		}
+	}()
+	wg.Wait()
+
+	ex.Release(p)
+
+	p, ok = ex.TryAcquire()
+	if !ok {
+		panic(fmt.Sprintf("TryAcquire failed"))
+	}
+}
+
+func TestRanger() {
+	s, r := a.Ranger[int]()
+
+	ctx := context.Background()
+	go func() {
+		// Receive one value then exit.
+		v, ok := r.Next(ctx)
+		if !ok {
+			panic(fmt.Sprintf("did not receive any values"))
+		} else if v != 1 {
+			panic(fmt.Sprintf("received %d, want 1", v))
+		}
+	}()
+
+	c1 := make(chan bool)
+	c2 := make(chan bool)
+	go func() {
+		defer close(c2)
+		if !s.Send(ctx, 1) {
+			panic(fmt.Sprintf("Send failed unexpectedly"))
+		}
+		close(c1)
+		if s.Send(ctx, 2) {
+			panic(fmt.Sprintf("Send succeeded unexpectedly"))
+		}
+	}()
+
+	<-c1
+
+	// Force a garbage collection to try to get the finalizers to run.
+	runtime.GC()
+
+	select {
+	case <-c2:
+	case <-time.After(time.Minute):
+		panic("Ranger Send should have failed, but timed out")
+	}
+}
+
+func main() {
+	TestReadAll()
+	TestMerge()
+	TestFilter()
+	TestSink()
+	TestExclusive()
+	TestExclusiveTry()
+	TestRanger()
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/chansimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/chansimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/chansimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/combine.go b/test/typeparam/combine.go
index d4a2988..5dfdb78 100644
--- a/test/typeparam/combine.go
+++ b/test/typeparam/combine.go
@@ -10,56 +10,56 @@
 	"fmt"
 )
 
-type _Gen[A any] func() (A, bool)
+type Gen[A any] func() (A, bool)
 
-func combine[T1, T2, T any](g1 _Gen[T1], g2 _Gen[T2], join func(T1, T2) T) _Gen[T] {
-    return func() (T, bool) {
-        var t T
-        t1, ok := g1()
-        if !ok {
-            return t, false
-        }
-        t2, ok := g2()
-        if !ok {
-            return t, false
-        }
-        return join(t1, t2), true
-    }
+func Combine[T1, T2, T any](g1 Gen[T1], g2 Gen[T2], join func(T1, T2) T) Gen[T] {
+	return func() (T, bool) {
+		var t T
+		t1, ok := g1()
+		if !ok {
+			return t, false
+		}
+		t2, ok := g2()
+		if !ok {
+			return t, false
+		}
+		return join(t1, t2), true
+	}
 }
 
-type _Pair[A, B any] struct {
+type Pair[A, B any] struct {
 	A A
 	B B
 }
 
-func _NewPair[A, B any](a A, b B) _Pair[A, B] {
-	return _Pair[A, B]{a, b}
+func _NewPair[A, B any](a A, b B) Pair[A, B] {
+	return Pair[A, B]{a, b}
 }
 
-func _Combine2[A, B any](ga _Gen[A], gb _Gen[B]) _Gen[_Pair[A, B]] {
-    return combine(ga, gb, _NewPair[A, B])
+func Combine2[A, B any](ga Gen[A], gb Gen[B]) Gen[Pair[A, B]] {
+	return Combine(ga, gb, _NewPair[A, B])
 }
 
 func main() {
-	var g1 _Gen[int] = func() (int, bool) { return 3, true }
-	var g2 _Gen[string] = func() (string, bool) { return "x", false }
-	var g3 _Gen[string] = func() (string, bool) { return "y", true }
+	var g1 Gen[int] = func() (int, bool) { return 3, true }
+	var g2 Gen[string] = func() (string, bool) { return "x", false }
+	var g3 Gen[string] = func() (string, bool) { return "y", true }
 
-	gc := combine(g1, g2, _NewPair[int, string])
+	gc := Combine(g1, g2, _NewPair[int, string])
 	if got, ok := gc(); ok {
 		panic(fmt.Sprintf("got %v, %v, wanted -/false", got, ok))
 	}
-	gc2 := _Combine2(g1, g2)
+	gc2 := Combine2(g1, g2)
 	if got, ok := gc2(); ok {
 		panic(fmt.Sprintf("got %v, %v, wanted -/false", got, ok))
 	}
 
-	gc3 := combine(g1, g3, _NewPair[int, string])
+	gc3 := Combine(g1, g3, _NewPair[int, string])
 	if got, ok := gc3(); !ok || got.A != 3 || got.B != "y" {
 		panic(fmt.Sprintf("got %v, %v, wanted {3, y}, true", got, ok))
 	}
-	gc4 := _Combine2(g1, g3)
+	gc4 := Combine2(g1, g3)
 	if got, ok := gc4(); !ok || got.A != 3 || got.B != "y" {
-		panic (fmt.Sprintf("got %v, %v, wanted {3, y}, true", got, ok))
+		panic(fmt.Sprintf("got %v, %v, wanted {3, y}, true", got, ok))
 	}
 }
diff --git a/test/typeparam/cons.go b/test/typeparam/cons.go
index 8d255eb..4750392 100644
--- a/test/typeparam/cons.go
+++ b/test/typeparam/cons.go
@@ -12,7 +12,7 @@
 // argument
 type any interface{}
 
-type _Function[a, b any] interface {
+type Function[a, b any] interface {
 	Apply(x a) b
 }
 
@@ -29,8 +29,8 @@
 }
 
 type compose[a, b, c any] struct {
-	f _Function[a, b]
-	g _Function[b, c]
+	f Function[a, b]
+	g Function[b, c]
 }
 
 func (this compose[a, b, c]) Apply(x a) c {
@@ -47,52 +47,52 @@
 	return int(this) == that
 }
 
-type _List[a any] interface {
-	Match(casenil _Function[_Nil[a], any], casecons _Function[_Cons[a], any]) any
+type List[a any] interface {
+	Match(casenil Function[Nil[a], any], casecons Function[Cons[a], any]) any
 }
 
-type _Nil[a any] struct{
+type Nil[a any] struct {
 }
 
-func (xs _Nil[a]) Match(casenil _Function[_Nil[a], any], casecons _Function[_Cons[a], any]) any {
+func (xs Nil[a]) Match(casenil Function[Nil[a], any], casecons Function[Cons[a], any]) any {
 	return casenil.Apply(xs)
 }
 
-type _Cons[a any] struct {
+type Cons[a any] struct {
 	Head a
-	Tail _List[a]
+	Tail List[a]
 }
 
-func (xs _Cons[a]) Match(casenil _Function[_Nil[a], any], casecons _Function[_Cons[a], any]) any {
+func (xs Cons[a]) Match(casenil Function[Nil[a], any], casecons Function[Cons[a], any]) any {
 	return casecons.Apply(xs)
 }
 
-type mapNil[a, b any] struct{
+type mapNil[a, b any] struct {
 }
 
-func (m mapNil[a, b]) Apply(_ _Nil[a]) any {
-	return _Nil[b]{}
+func (m mapNil[a, b]) Apply(_ Nil[a]) any {
+	return Nil[b]{}
 }
 
 type mapCons[a, b any] struct {
-	f _Function[a, b]
+	f Function[a, b]
 }
 
-func (m mapCons[a, b]) Apply(xs _Cons[a]) any {
-	return _Cons[b]{m.f.Apply(xs.Head), _Map[a, b](m.f, xs.Tail)}
+func (m mapCons[a, b]) Apply(xs Cons[a]) any {
+	return Cons[b]{m.f.Apply(xs.Head), Map[a, b](m.f, xs.Tail)}
 }
 
-func _Map[a, b any](f _Function[a, b], xs _List[a]) _List[b] {
-	return xs.Match(mapNil[a, b]{}, mapCons[a, b]{f}).(_List[b])
+func Map[a, b any](f Function[a, b], xs List[a]) List[b] {
+	return xs.Match(mapNil[a, b]{}, mapCons[a, b]{f}).(List[b])
 }
 
 func main() {
-	var xs _List[int] = _Cons[int]{3, _Cons[int]{6, _Nil[int]{}}}
-	var ys _List[int] = _Map[int, int](incr{-5}, xs)
-	var xz _List[bool] = _Map[int, bool](pos{}, ys)
-	cs1 := xz.(_Cons[bool])
-	cs2 := cs1.Tail.(_Cons[bool])
-	_, ok := cs2.Tail.(_Nil[bool])
+	var xs List[int] = Cons[int]{3, Cons[int]{6, Nil[int]{}}}
+	var ys List[int] = Map[int, int](incr{-5}, xs)
+	var xz List[bool] = Map[int, bool](pos{}, ys)
+	cs1 := xz.(Cons[bool])
+	cs2 := cs1.Tail.(Cons[bool])
+	_, ok := cs2.Tail.(Nil[bool])
 	if cs1.Head != false || cs2.Head != true || !ok {
 		panic(fmt.Sprintf("got %v, %v, %v, expected false, true, true",
 			cs1.Head, cs2.Head, ok))
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/dedup.dir/a.go
similarity index 62%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/dedup.dir/a.go
index 10641a7..f5cb6dc 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/dedup.dir/a.go
@@ -2,11 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
-
-func init() {
-	typeParamsEnabled = true
+//go:noinline
+func F[T comparable](a, b T) bool {
+	return a == b
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/dedup.dir/b.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/dedup.dir/b.go
index 10641a7..ce037e2 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/dedup.dir/b.go
@@ -2,11 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package b
 
-package main
+import "a"
 
-func init() {
-	typeParamsEnabled = true
+func B() {
+	var x int64
+	println(a.F(&x, &x))
+	var y int32
+	println(a.F(&y, &y))
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/dedup.dir/c.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/dedup.dir/c.go
index 10641a7..11a5d97 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/dedup.dir/c.go
@@ -2,11 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package c
 
-package main
+import "a"
 
-func init() {
-	typeParamsEnabled = true
+func C() {
+	var x int64
+	println(a.F(&x, &x))
+	var y int32
+	println(a.F(&y, &y))
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/dedup.dir/main.go
similarity index 67%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/dedup.dir/main.go
index 10641a7..dc3ff6f 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/dedup.dir/main.go
@@ -2,11 +2,14 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
 package main
 
-func init() {
-	typeParamsEnabled = true
+import (
+	"b"
+	"c"
+)
+
+func main() {
+	b.B()
+	c.C()
 }
diff --git a/test/typeparam/dedup.go b/test/typeparam/dedup.go
new file mode 100644
index 0000000..dca4cf3
--- /dev/null
+++ b/test/typeparam/dedup.go
@@ -0,0 +1,12 @@
+// rundir -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Note: this doesn't really test the deduplication of
+// instantiations. It just provides an easy mechanism to build a
+// binary that you can then check with objdump manually to make sure
+// deduplication is happening. TODO: automate this somehow?
+
+package ignored
diff --git a/test/typeparam/dedup.out b/test/typeparam/dedup.out
new file mode 100644
index 0000000..1140ff5
--- /dev/null
+++ b/test/typeparam/dedup.out
@@ -0,0 +1,4 @@
+true
+true
+true
+true
diff --git a/test/typeparam/dictionaryCapture-noinline.go b/test/typeparam/dictionaryCapture-noinline.go
new file mode 100644
index 0000000..ad5bfa0
--- /dev/null
+++ b/test/typeparam/dictionaryCapture-noinline.go
@@ -0,0 +1,126 @@
+// run -gcflags="-G=3 -l"
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test situations where functions/methods are not
+// immediately called and we need to capture the dictionary
+// required for later invocation.
+
+package main
+
+func main() {
+	functions()
+	methodExpressions()
+	methodValues()
+	interfaceMethods()
+	globals()
+}
+
+func g0[T any](x T) {
+}
+func g1[T any](x T) T {
+	return x
+}
+func g2[T any](x T) (T, T) {
+	return x, x
+}
+
+func functions() {
+	f0 := g0[int]
+	f0(7)
+	f1 := g1[int]
+	is7(f1(7))
+	f2 := g2[int]
+	is77(f2(7))
+}
+
+func is7(x int) {
+	if x != 7 {
+		println(x)
+		panic("assertion failed")
+	}
+}
+func is77(x, y int) {
+	if x != 7 || y != 7 {
+		println(x, y)
+		panic("assertion failed")
+	}
+}
+
+type s[T any] struct {
+	a T
+}
+
+func (x s[T]) g0() {
+}
+func (x s[T]) g1() T {
+	return x.a
+}
+func (x s[T]) g2() (T, T) {
+	return x.a, x.a
+}
+
+func methodExpressions() {
+	x := s[int]{a: 7}
+	f0 := s[int].g0
+	f0(x)
+	f1 := s[int].g1
+	is7(f1(x))
+	f2 := s[int].g2
+	is77(f2(x))
+}
+
+func methodValues() {
+	x := s[int]{a: 7}
+	f0 := x.g0
+	f0()
+	f1 := x.g1
+	is7(f1())
+	f2 := x.g2
+	is77(f2())
+}
+
+var x interface {
+	g0()
+	g1() int
+	g2() (int, int)
+} = s[int]{a: 7}
+var y interface{} = s[int]{a: 7}
+
+func interfaceMethods() {
+	x.g0()
+	is7(x.g1())
+	is77(x.g2())
+	y.(interface{ g0() }).g0()
+	is7(y.(interface{ g1() int }).g1())
+	is77(y.(interface{ g2() (int, int) }).g2())
+}
+
+// Also check for instantiations outside functions.
+var gg0 = g0[int]
+var gg1 = g1[int]
+var gg2 = g2[int]
+
+var hh0 = s[int].g0
+var hh1 = s[int].g1
+var hh2 = s[int].g2
+
+var xtop = s[int]{a: 7}
+var ii0 = x.g0
+var ii1 = x.g1
+var ii2 = x.g2
+
+func globals() {
+	gg0(7)
+	is7(gg1(7))
+	is77(gg2(7))
+	x := s[int]{a: 7}
+	hh0(x)
+	is7(hh1(x))
+	is77(hh2(x))
+	ii0()
+	is7(ii1())
+	is77(ii2())
+}
diff --git a/test/typeparam/dictionaryCapture.go b/test/typeparam/dictionaryCapture.go
new file mode 100644
index 0000000..7c79481
--- /dev/null
+++ b/test/typeparam/dictionaryCapture.go
@@ -0,0 +1,203 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test situations where functions/methods are not
+// immediately called and we need to capture the dictionary
+// required for later invocation.
+
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	functions()
+	methodExpressions()
+	genMethodExpressions[int](7)
+	methodValues()
+	genMethodValues[int](7)
+	interfaceMethods()
+	globals()
+	recursive()
+}
+
+func g0[T any](x T) {
+}
+func g1[T any](x T) T {
+	return x
+}
+func g2[T any](x T) (T, T) {
+	return x, x
+}
+
+func functions() {
+	f0 := g0[int]
+	f0(7)
+	f1 := g1[int]
+	is7(f1(7))
+	f2 := g2[int]
+	is77(f2(7))
+}
+
+func is7(x int) {
+	if x != 7 {
+		println(x)
+		panic("assertion failed")
+	}
+}
+func is77(x, y int) {
+	if x != 7 || y != 7 {
+		println(x, y)
+		panic("assertion failed")
+	}
+}
+
+type s[T any] struct {
+	a T
+}
+
+func (x s[T]) g0() {
+}
+func (x s[T]) g1() T {
+	return x.a
+}
+func (x s[T]) g2() (T, T) {
+	return x.a, x.a
+}
+
+func methodExpressions() {
+	x := s[int]{a: 7}
+	f0 := s[int].g0
+	f0(x)
+	f0p := (*s[int]).g0
+	f0p(&x)
+	f1 := s[int].g1
+	is7(f1(x))
+	f1p := (*s[int]).g1
+	is7(f1p(&x))
+	f2 := s[int].g2
+	is77(f2(x))
+	f2p := (*s[int]).g2
+	is77(f2p(&x))
+}
+
+func genMethodExpressions[T comparable](want T) {
+	x := s[T]{a: want}
+	f0 := s[T].g0
+	f0(x)
+	f0p := (*s[T]).g0
+	f0p(&x)
+	f1 := s[T].g1
+	if got := f1(x); got != want {
+		panic(fmt.Sprintf("f1(x) == %d, want %d", got, want))
+	}
+	f1p := (*s[T]).g1
+	if got := f1p(&x); got != want {
+		panic(fmt.Sprintf("f1p(&x) == %d, want %d", got, want))
+	}
+	f2 := s[T].g2
+	if got1, got2 := f2(x); got1 != want || got2 != want {
+		panic(fmt.Sprintf("f2(x) == %d, %d, want %d, %d", got1, got2, want, want))
+	}
+}
+
+func methodValues() {
+	x := s[int]{a: 7}
+	f0 := x.g0
+	f0()
+	f1 := x.g1
+	is7(f1())
+	f2 := x.g2
+	is77(f2())
+}
+
+func genMethodValues[T comparable](want T) {
+	x := s[T]{a: want}
+	f0 := x.g0
+	f0()
+	f1 := x.g1
+	if got := f1(); got != want {
+		panic(fmt.Sprintf("f1() == %d, want %d", got, want))
+	}
+	f2 := x.g2
+	if got1, got2 := f2(); got1 != want || got2 != want {
+		panic(fmt.Sprintf("f2() == %d, %d, want %d, %d", got1, got2, want, want))
+	}
+}
+
+var x interface {
+	g0()
+	g1() int
+	g2() (int, int)
+} = s[int]{a: 7}
+var y interface{} = s[int]{a: 7}
+
+func interfaceMethods() {
+	x.g0()
+	is7(x.g1())
+	is77(x.g2())
+	y.(interface{ g0() }).g0()
+	is7(y.(interface{ g1() int }).g1())
+	is77(y.(interface{ g2() (int, int) }).g2())
+}
+
+// Also check for instantiations outside functions.
+var gg0 = g0[int]
+var gg1 = g1[int]
+var gg2 = g2[int]
+
+var hh0 = s[int].g0
+var hh1 = s[int].g1
+var hh2 = s[int].g2
+
+var xtop = s[int]{a: 7}
+var ii0 = x.g0
+var ii1 = x.g1
+var ii2 = x.g2
+
+func globals() {
+	gg0(7)
+	is7(gg1(7))
+	is77(gg2(7))
+	x := s[int]{a: 7}
+	hh0(x)
+	is7(hh1(x))
+	is77(hh2(x))
+	ii0()
+	is7(ii1())
+	is77(ii2())
+}
+
+func recursive() {
+	if got, want := recur1[int](5), 110; got != want {
+		panic(fmt.Sprintf("recur1[int](5) = %d, want = %d", got, want))
+	}
+}
+
+type Integer interface {
+	int | int32 | int64
+}
+
+func recur1[T Integer](n T) T {
+	if n == 0 || n == 1 {
+		return T(1)
+	} else {
+		return n * recur2(n-1)
+	}
+}
+
+func recur2[T Integer](n T) T {
+	list := make([]T, n)
+	for i, _ := range list {
+		list[i] = T(i + 1)
+	}
+	var sum T
+	for _, elt := range list {
+		sum += elt
+	}
+	return sum + recur1(n-1)
+}
diff --git a/test/typeparam/dottype.go b/test/typeparam/dottype.go
new file mode 100644
index 0000000..c9c900c
--- /dev/null
+++ b/test/typeparam/dottype.go
@@ -0,0 +1,86 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[T any](x interface{}) T {
+	return x.(T)
+}
+func f2[T any](x interface{}) (T, bool) {
+	t, ok := x.(T)
+	return t, ok
+}
+
+type I interface {
+	foo()
+}
+
+type myint int
+
+func (myint) foo() {
+}
+
+type myfloat float64
+
+func (myfloat) foo() {
+}
+
+func g[T I](x I) T {
+	return x.(T)
+}
+func g2[T I](x I) (T, bool) {
+	t, ok := x.(T)
+	return t, ok
+}
+
+func h[T any](x interface{}) struct{ a, b T } {
+	return x.(struct{ a, b T })
+}
+
+func k[T any](x interface{}) interface{ bar() T } {
+	return x.(interface{ bar() T })
+}
+
+type mybar int
+
+func (x mybar) bar() int {
+	return int(x)
+}
+
+func main() {
+	var i interface{} = int(3)
+	var j I = myint(3)
+	var x interface{} = float64(3)
+	var y I = myfloat(3)
+
+	println(f[int](i))
+	shouldpanic(func() { f[int](x) })
+	println(f2[int](i))
+	println(f2[int](x))
+
+	println(g[myint](j))
+	shouldpanic(func() { g[myint](y) })
+	println(g2[myint](j))
+	println(g2[myint](y))
+
+	println(h[int](struct{ a, b int }{3, 5}).a)
+
+	println(k[int](mybar(3)).bar())
+
+	type large struct {a,b,c,d,e,f int}
+	println(f[large](large{}).a)
+	l2, ok := f2[large](large{})
+	println(l2.a, ok)
+}
+func shouldpanic(x func()) {
+	defer func() {
+		e := recover()
+		if e == nil {
+			panic("didn't panic")
+		}
+	}()
+	x()
+}
diff --git a/test/typeparam/dottype.out b/test/typeparam/dottype.out
new file mode 100644
index 0000000..8e6a3c2
--- /dev/null
+++ b/test/typeparam/dottype.out
@@ -0,0 +1,10 @@
+3
+3 true
+0 false
+3
+3 true
+0 false
+3
+3
+0
+0 true
diff --git a/test/typeparam/double.go b/test/typeparam/double.go
index ce78ec9..6ddb6b2 100644
--- a/test/typeparam/double.go
+++ b/test/typeparam/double.go
@@ -12,7 +12,7 @@
 )
 
 type Number interface {
-	type int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, uintptr, float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr | ~float32 | ~float64
 }
 
 type MySlice []int
@@ -44,29 +44,29 @@
 	want := MySlice{2, 4, 6}
 	got := _DoubleElems[MySlice, int](arg)
 	if !reflect.DeepEqual(got, want) {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 
 	// constraint type inference
 	got = _DoubleElems[MySlice](arg)
 	if !reflect.DeepEqual(got, want) {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 
 	got = _DoubleElems(arg)
 	if !reflect.DeepEqual(got, want) {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 
 	farg := MyFloatSlice{1.2, 2.0, 3.5}
 	fwant := MyFloatSlice{2.4, 4.0, 7.0}
 	fgot := _DoubleElems(farg)
 	if !reflect.DeepEqual(fgot, fwant) {
-                panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
+		panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
 	}
 
 	fgot = _DoubleElems2(farg)
 	if !reflect.DeepEqual(fgot, fwant) {
-                panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
+		panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
 	}
 }
diff --git a/test/typeparam/equal.go b/test/typeparam/equal.go
new file mode 100644
index 0000000..a1d3e8a
--- /dev/null
+++ b/test/typeparam/equal.go
@@ -0,0 +1,69 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// comparisons of type parameters to interfaces
+
+package main
+
+func f[T comparable](t, u T) bool {
+	// Comparing two type parameters directly.
+	// (Not really testing comparisons to interfaces, but just 'cause we're here.)
+	return t == u
+}
+
+func g[T comparable](t T, i interface{}) bool {
+	// Compare type parameter value to empty interface.
+	return t == i
+}
+
+type I interface {
+	foo()
+}
+
+type C interface {
+	comparable
+	I
+}
+
+func h[T C](t T, i I) bool {
+	// Compare type parameter value to nonempty interface.
+	return t == i
+}
+
+type myint int
+
+func (x myint) foo() {
+}
+
+func k[T comparable](t T, i interface{}) bool {
+	// Compare derived type value to interface.
+	return struct{ a, b T }{t, t} == i
+}
+
+func main() {
+	assert(f(3, 3))
+	assert(!f(3, 5))
+	assert(g(3, 3))
+	assert(!g(3, 5))
+	assert(h(myint(3), myint(3)))
+	assert(!h(myint(3), myint(5)))
+
+	type S struct{ a, b float64 }
+
+	assert(f(S{3, 5}, S{3, 5}))
+	assert(!f(S{3, 5}, S{4, 6}))
+	assert(g(S{3, 5}, S{3, 5}))
+	assert(!g(S{3, 5}, S{4, 6}))
+
+	assert(k(3, struct{ a, b int }{3, 3}))
+	assert(!k(3, struct{ a, b int }{3, 4}))
+}
+
+func assert(b bool) {
+	if !b {
+		panic("assertion failed")
+	}
+}
diff --git a/test/typeparam/fact.go b/test/typeparam/fact.go
index 16b2adf..e19cfe6 100644
--- a/test/typeparam/fact.go
+++ b/test/typeparam/fact.go
@@ -8,11 +8,11 @@
 
 import "fmt"
 
-func fact[T interface { type int, int64, float64 }](n T) T {
-	if n == T(1) {
-		return T(1)
+func fact[T interface{ ~int | ~int64 | ~float64 }](n T) T {
+	if n == 1 {
+		return 1
 	}
-	return n * fact(n - T(1))
+	return n * fact(n-1)
 }
 
 func main() {
diff --git a/test/typeparam/factimp.dir/a.go b/test/typeparam/factimp.dir/a.go
new file mode 100644
index 0000000..0bd73a8
--- /dev/null
+++ b/test/typeparam/factimp.dir/a.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func Fact[T interface{ int | int64 | float64 }](n T) T {
+	if n == 1 {
+		return 1
+	}
+	return n * Fact(n-1)
+}
diff --git a/test/typeparam/factimp.dir/main.go b/test/typeparam/factimp.dir/main.go
new file mode 100644
index 0000000..c223800
--- /dev/null
+++ b/test/typeparam/factimp.dir/main.go
@@ -0,0 +1,26 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	const want = 120
+
+	if got := a.Fact(5); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Fact[int64](5); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Fact(5.0); got != want {
+		panic(fmt.Sprintf("got %f, want %f", got, want))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/factimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/factimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/factimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/graph.go b/test/typeparam/graph.go
index f2a2630..cecf349 100644
--- a/test/typeparam/graph.go
+++ b/test/typeparam/graph.go
@@ -225,7 +225,6 @@
 	}
 }
 
-
 func main() {
 	TestShortestPath()
 }
diff --git a/test/typeparam/ifaceconv.go b/test/typeparam/ifaceconv.go
new file mode 100644
index 0000000..ee3a9e0
--- /dev/null
+++ b/test/typeparam/ifaceconv.go
@@ -0,0 +1,83 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that we can convert type parameters to both empty
+// and nonempty interfaces, and named and nonnamed versions
+// thereof.
+
+package main
+
+import "fmt"
+
+type E interface{}
+
+func f[T any](x T) interface{} {
+	var i interface{} = x
+	return i
+}
+
+func fs[T any](x T) interface{} {
+	y := []T{x}
+	var i interface{} = y
+	return i
+}
+
+func g[T any](x T) E {
+	var i E = x
+	return i
+}
+
+type C interface {
+	foo() int
+}
+
+type myInt int
+
+func (x myInt) foo() int {
+	return int(x + 1)
+}
+
+func h[T C](x T) interface{ foo() int } {
+	var i interface{ foo() int } = x
+	return i
+}
+func i[T C](x T) C {
+	var i C = x // conversion in assignment
+	return i
+}
+
+func j[T C](t T) C {
+	return C(t) // explicit conversion
+}
+
+func js[T any](x T) interface{} {
+	y := []T{x}
+	return interface{}(y)
+}
+
+func main() {
+	if got, want := f[int](7), 7; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := fs[int](7), []int{7}; got.([]int)[0] != want[0] {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := g[int](7), 7; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := h[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := i[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := j[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := js[int](7), []int{7}; got.([]int)[0] != want[0] {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+}
diff --git a/test/typeparam/index.go b/test/typeparam/index.go
index 83e65ac..906f76d 100644
--- a/test/typeparam/index.go
+++ b/test/typeparam/index.go
@@ -11,7 +11,7 @@
 )
 
 // Index returns the index of x in s, or -1 if not found.
-func index[T comparable](s []T, x T) int {
+func Index[T comparable](s []T, x T) int {
 	for i, v := range s {
 		// v and x are type T, which has the comparable
 		// constraint, so we can use == here.
@@ -26,21 +26,56 @@
 	x int
 }
 
+type obj2 struct {
+	x int8
+	y float64
+}
+
+type obj3 struct {
+	x int64
+	y int8
+}
+
+type inner struct {
+	y int64
+	z int32
+}
+
+type obj4 struct {
+	x int32
+	s inner
+}
+
 func main() {
 	want := 2
 
 	vec1 := []string{"ab", "cd", "ef"}
-	if got := index(vec1, "ef"); got != want {
+	if got := Index(vec1, "ef"); got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	vec2 := []byte{'c', '6', '@'}
-	if got := index(vec2, '@'); got != want {
+	if got := Index(vec2, '@'); got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	vec3 := []*obj{&obj{2}, &obj{42}, &obj{1}}
-	if got := index(vec3, vec3[2]); got != want {
+	if got := Index(vec3, vec3[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec4 := []obj2{obj2{2, 3.0}, obj2{3, 4.0}, obj2{4, 5.0}}
+	if got := Index(vec4, vec4[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec5 := []obj3{obj3{2, 3}, obj3{3, 4}, obj3{4, 5}}
+	if got := Index(vec5, vec5[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec6 := []obj4{obj4{2, inner{3, 4}}, obj4{3, inner{4, 5}}, obj4{4, inner{5, 6}}}
+	if got := Index(vec6, vec6[2]); got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 }
diff --git a/test/typeparam/interfacearg.go b/test/typeparam/interfacearg.go
index e2d85e3..28ea3e3 100644
--- a/test/typeparam/interfacearg.go
+++ b/test/typeparam/interfacearg.go
@@ -9,23 +9,25 @@
 type I interface{}
 
 type _S[T any] struct {
-	*T
+	x *T
 }
 
 // F is a non-generic function, but has a type _S[I] which is instantiated from a
 // generic type. Test that _S[I] is successfully exported.
 func F() {
 	v := _S[I]{}
-	if v.T != nil {
+	if v.x != nil {
 		panic(v)
 	}
 }
 
 // Testing the various combinations of method expressions.
 type S1 struct{}
+
 func (*S1) M() {}
 
 type S2 struct{}
+
 func (S2) M() {}
 
 func _F1[T interface{ M() }](t T) {
@@ -33,9 +35,9 @@
 }
 
 func F2() {
-        _F1(&S1{})
-        _F1(S2{})
-        _F1(&S2{})
+	_F1(&S1{})
+	_F1(S2{})
+	_F1(&S2{})
 }
 
 func main() {
diff --git a/test/typeparam/issue39755.go b/test/typeparam/issue39755.go
new file mode 100644
index 0000000..c4b6902
--- /dev/null
+++ b/test/typeparam/issue39755.go
@@ -0,0 +1,27 @@
+// compile -G=3
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// copied from cmd/compile/internal/types2/testdata/fixedbugs/issue39755.go
+
+package p
+
+func _[T interface{ ~map[string]int }](x T) {
+	_ = x == nil
+}
+
+// simplified test case from issue
+
+type PathParamsConstraint interface {
+	~map[string]string | ~[]struct{ key, value string }
+}
+
+type PathParams[T PathParamsConstraint] struct {
+	t T
+}
+
+func (pp *PathParams[T]) IsNil() bool {
+	return pp.t == nil // this must succeed
+}
diff --git a/test/typeparam/issue44688.go b/test/typeparam/issue44688.go
new file mode 100644
index 0000000..5ebce72
--- /dev/null
+++ b/test/typeparam/issue44688.go
@@ -0,0 +1,148 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// derived & expanded from cmd/compile/internal/types2/testdata/fixedbugs/issue44688.go2
+
+package main
+
+type A1[T any] struct {
+	val T
+}
+
+func (p *A1[T]) m1(val T) {
+	p.val = val
+}
+
+type A2[T any] interface {
+	m2(T)
+}
+
+type B1[T any] struct {
+	filler int
+	*A1[T]
+	A2[T]
+}
+
+type B2[T any] interface {
+	A2[T]
+}
+
+type ImpA2[T any] struct {
+	f T
+}
+
+func (a2 *ImpA2[T]) m2(s T) {
+	a2.f = s
+}
+
+type C[T any] struct {
+	filler1 int
+	filler2 int
+	B1[T]
+}
+
+type D[T any] struct {
+	filler1 int
+	filler2 int
+	filler3 int
+	C[T]
+}
+
+func test1[T any](arg T) {
+	// calling embedded methods
+	var b1 B1[T]
+	b1.A1 = &A1[T]{}
+	b1.A2 = &ImpA2[T]{}
+
+	b1.A1.m1(arg)
+	b1.m1(arg)
+
+	b1.A2.m2(arg)
+	b1.m2(arg)
+
+	var b2 B2[T]
+	b2 = &ImpA2[T]{}
+	b2.m2(arg)
+
+	// a deeper nesting
+	var d D[T]
+	d.C.B1.A1 = &A1[T]{}
+	d.C.B1.A2 = &ImpA2[T]{}
+	d.m1(arg)
+	d.m2(arg)
+
+	// calling method expressions
+	m1x := B1[T].m1
+	m1x(b1, arg)
+	m2x := B2[T].m2
+	m2x(b2, arg)
+
+	// calling method values
+	m1v := b1.m1
+	m1v(arg)
+	m2v := b1.m2
+	m2v(arg)
+	b2v := b2.m2
+	b2v(arg)
+}
+
+func test2() {
+	// calling embedded methods
+	var b1 B1[string]
+	b1.A1 = &A1[string]{}
+	b1.A2 = &ImpA2[string]{}
+
+	b1.A1.m1("")
+	b1.m1("")
+
+	b1.A2.m2("")
+	b1.m2("")
+
+	var b2 B2[string]
+	b2 = &ImpA2[string]{}
+	b2.m2("")
+
+	// a deeper nesting
+	var d D[string]
+	d.C.B1.A1 = &A1[string]{}
+	d.C.B1.A2 = &ImpA2[string]{}
+	d.m1("")
+	d.m2("")
+
+	// calling method expressions
+	m1x := B1[string].m1
+	m1x(b1, "")
+	m2x := B2[string].m2
+	m2x(b2, "")
+
+	// calling method values
+	m1v := b1.m1
+	m1v("")
+	m2v := b1.m2
+	m2v("")
+	b2v := b2.m2
+	b2v("")
+}
+
+// actual test case from issue
+
+type A[T any] struct{}
+
+func (*A[T]) f(T) {}
+
+type B[T any] struct{ A[T] }
+
+func test3() {
+	var b B[string]
+	b.A.f("")
+	b.f("")
+}
+
+func main() {
+	test1[string]("")
+	test2()
+	test3()
+}
diff --git a/test/typeparam/issue45547.go b/test/typeparam/issue45547.go
index 0a08d66..b354d4d 100644
--- a/test/typeparam/issue45547.go
+++ b/test/typeparam/issue45547.go
@@ -11,7 +11,7 @@
 // Tests for generic function instantiation on the right hande side of multi-value
 // assignments.
 
-func _() {
+func g() {
 	// Multi-value assignment within a function
 	var _, _ = f[int]()
 }
diff --git a/test/typeparam/issue45817.go b/test/typeparam/issue45817.go
new file mode 100644
index 0000000..1efee3b
--- /dev/null
+++ b/test/typeparam/issue45817.go
@@ -0,0 +1,26 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+)
+
+type s[T any] struct {
+	a T
+}
+
+func (x s[T]) f() T {
+	return x.a
+}
+func main() {
+	x := s[int]{a: 7}
+	f := x.f
+	if got, want := f(), 7; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+}
diff --git a/test/typeparam/issue46472.go b/test/typeparam/issue46472.go
new file mode 100644
index 0000000..cd4d923
--- /dev/null
+++ b/test/typeparam/issue46472.go
@@ -0,0 +1,20 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func foo[T any](d T) {
+	switch v := interface{}(d).(type) {
+	case string:
+		if v != "x" {
+			panic("unexpected v: " + v)
+		}
+	}
+
+}
+func main() {
+	foo("x")
+}
diff --git a/test/typeparam/issue47258.go b/test/typeparam/issue47258.go
new file mode 100644
index 0000000..7173294
--- /dev/null
+++ b/test/typeparam/issue47258.go
@@ -0,0 +1,32 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+)
+
+type Numeric interface {
+	int32 | int64 | float64 | complex64
+}
+
+//go:noline
+func inc[T Numeric](x T) T {
+	x++
+	return x
+}
+func main() {
+	if got, want := inc(int32(5)), int32(6); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	if got, want := inc(float64(5)), float64(6.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	if got, want := inc(complex64(5)), complex64(6.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+}
diff --git a/test/typeparam/issue47514.go b/test/typeparam/issue47514.go
new file mode 100644
index 0000000..947f254
--- /dev/null
+++ b/test/typeparam/issue47514.go
@@ -0,0 +1,20 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that closures inside a generic function are not exported,
+// even though not themselves generic.
+
+package main
+
+func Do[T any]() {
+	_ = func() string {
+		return ""
+	}
+}
+
+func main() {
+	Do[int]()
+}
diff --git a/test/typeparam/issue47514b.go b/test/typeparam/issue47514b.go
new file mode 100644
index 0000000..5428a0e
--- /dev/null
+++ b/test/typeparam/issue47514b.go
@@ -0,0 +1,19 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func Do[T any](do func() (T, string)) {
+	_ = func() (T, string) {
+		return do()
+	}
+}
+
+func main() {
+	Do[int](func() (int, string) {
+		return 3, "3"
+	})
+}
diff --git a/test/typeparam/list.go b/test/typeparam/list.go
index 579078f..adfe72f 100644
--- a/test/typeparam/list.go
+++ b/test/typeparam/list.go
@@ -11,10 +11,10 @@
 )
 
 type Ordered interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr,
-                float32, float64,
-                string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
 // _List is a linked list of ordered values of type T.
@@ -34,9 +34,9 @@
 }
 
 type OrderedNum interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr,
-                float32, float64
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
 }
 
 // _ListNum is a linked _List of ordered numeric values of type T.
@@ -64,40 +64,40 @@
 	i2 := &_List[int]{i3, 3}
 	i1 := &_List[int]{i2, 2}
 	if got, want := i1.Largest(), 3; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	b3 := &_List[byte]{nil, byte(1)}
 	b2 := &_List[byte]{b3, byte(3)}
 	b1 := &_List[byte]{b2, byte(2)}
 	if got, want := b1.Largest(), byte(3); got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	f3 := &_List[float64]{nil, 13.5}
 	f2 := &_List[float64]{f3, 1.2}
 	f1 := &_List[float64]{f2, 4.5}
 	if got, want := f1.Largest(), 13.5; got != want {
-                panic(fmt.Sprintf("got %f, want %f", got, want))
+		panic(fmt.Sprintf("got %f, want %f", got, want))
 	}
 
 	s3 := &_List[string]{nil, "dd"}
 	s2 := &_List[string]{s3, "aa"}
 	s1 := &_List[string]{s2, "bb"}
 	if got, want := s1.Largest(), "dd"; got != want {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 
 	j3 := &_ListNum[int]{nil, 1}
 	j2 := &_ListNum[int]{j3, 32}
 	j1 := &_ListNum[int]{j2, 2}
 	if got, want := j1.ClippedLargest(), 2; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 	g3 := &_ListNum[float64]{nil, 13.5}
 	g2 := &_ListNum[float64]{g3, 1.2}
 	g1 := &_ListNum[float64]{g2, 4.5}
 	if got, want := g1.ClippedLargest(), 4.5; got != want {
-                panic(fmt.Sprintf("got %f, want %f", got, want))
+		panic(fmt.Sprintf("got %f, want %f", got, want))
 	}
 }
diff --git a/test/typeparam/list2.go b/test/typeparam/list2.go
index 385193d..e7f346c 100644
--- a/test/typeparam/list2.go
+++ b/test/typeparam/list2.go
@@ -50,7 +50,7 @@
 // The zero value for _List is an empty list ready to use.
 type _List[T any] struct {
 	root _Element[T] // sentinel list element, only &root, root.prev, and root.next are used
-	len  int     // current list length excluding (this) sentinel element
+	len  int         // current list length excluding (this) sentinel element
 }
 
 // Init initializes or clears list l.
@@ -594,8 +594,15 @@
 	checkList(l2, []interface{}{"1", "2"})
 }
 
-
 func main() {
 	TestList()
+	TestExtending()
+	TestRemove()
+	TestIssue4103()
+	TestIssue6349()
+	TestMove()
+	TestZeroList()
+	TestInsertBeforeUnknownMark()
+	TestInsertAfterUnknownMark()
+	TestTransform()
 }
-
diff --git a/test/typeparam/listimp.dir/a.go b/test/typeparam/listimp.dir/a.go
new file mode 100644
index 0000000..bf1641a
--- /dev/null
+++ b/test/typeparam/listimp.dir/a.go
@@ -0,0 +1,53 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Ordered interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
+}
+
+// List is a linked list of ordered values of type T.
+type List[T Ordered] struct {
+	Next *List[T]
+	Val  T
+}
+
+func (l *List[T]) Largest() T {
+	var max T
+	for p := l; p != nil; p = p.Next {
+		if p.Val > max {
+			max = p.Val
+		}
+	}
+	return max
+}
+
+type OrderedNum interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64
+}
+
+// ListNum is a linked _List of ordered numeric values of type T.
+type ListNum[T OrderedNum] struct {
+	Next *ListNum[T]
+	Val  T
+}
+
+const Clip = 5
+
+// clippedLargest returns the largest in the list of OrderNums, but a max of 5.
+func (l *ListNum[T]) ClippedLargest() T {
+	var max T
+	for p := l; p != nil; p = p.Next {
+		if p.Val > max && p.Val < Clip {
+			max = p.Val
+		}
+	}
+	return max
+}
diff --git a/test/typeparam/listimp.dir/main.go b/test/typeparam/listimp.dir/main.go
new file mode 100644
index 0000000..985ff59
--- /dev/null
+++ b/test/typeparam/listimp.dir/main.go
@@ -0,0 +1,52 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	i3 := &a.List[int]{nil, 1}
+	i2 := &a.List[int]{i3, 3}
+	i1 := &a.List[int]{i2, 2}
+	if got, want := i1.Largest(), 3; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	b3 := &a.List[byte]{nil, byte(1)}
+	b2 := &a.List[byte]{b3, byte(3)}
+	b1 := &a.List[byte]{b2, byte(2)}
+	if got, want := b1.Largest(), byte(3); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	f3 := &a.List[float64]{nil, 13.5}
+	f2 := &a.List[float64]{f3, 1.2}
+	f1 := &a.List[float64]{f2, 4.5}
+	if got, want := f1.Largest(), 13.5; got != want {
+		panic(fmt.Sprintf("got %f, want %f", got, want))
+	}
+
+	s3 := &a.List[string]{nil, "dd"}
+	s2 := &a.List[string]{s3, "aa"}
+	s1 := &a.List[string]{s2, "bb"}
+	if got, want := s1.Largest(), "dd"; got != want {
+		panic(fmt.Sprintf("got %s, want %s", got, want))
+	}
+	j3 := &a.ListNum[int]{nil, 1}
+	j2 := &a.ListNum[int]{j3, 32}
+	j1 := &a.ListNum[int]{j2, 2}
+	if got, want := j1.ClippedLargest(), 2; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+	g3 := &a.ListNum[float64]{nil, 13.5}
+	g2 := &a.ListNum[float64]{g3, 1.2}
+	g1 := &a.ListNum[float64]{g2, 4.5}
+	if got, want := g1.ClippedLargest(), 4.5; got != want {
+		panic(fmt.Sprintf("got %f, want %f", got, want))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/listimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/listimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/listimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/listimp2.dir/a.go b/test/typeparam/listimp2.dir/a.go
new file mode 100644
index 0000000..3a7dfc3
--- /dev/null
+++ b/test/typeparam/listimp2.dir/a.go
@@ -0,0 +1,298 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+import (
+	"fmt"
+)
+
+// Element is an element of a linked list.
+type Element[T any] struct {
+	// Next and previous pointers in the doubly-linked list of elements.
+	// To simplify the implementation, internally a list l is implemented
+	// as a ring, such that &l.root is both the next element of the last
+	// list element (l.Back()) and the previous element of the first list
+	// element (l.Front()).
+	next, prev *Element[T]
+
+	// The list to which this element belongs.
+	list *List[T]
+
+	// The value stored with this element.
+	Value T
+}
+
+// Next returns the next list element or nil.
+func (e *Element[T]) Next() *Element[T] {
+	if p := e.next; e.list != nil && p != &e.list.root {
+		return p
+	}
+	return nil
+}
+
+// Prev returns the previous list element or nil.
+func (e *Element[T]) Prev() *Element[T] {
+	if p := e.prev; e.list != nil && p != &e.list.root {
+		return p
+	}
+	return nil
+}
+
+// List represents a doubly linked list.
+// The zero value for List is an empty list ready to use.
+type List[T any] struct {
+	root Element[T] // sentinel list element, only &root, root.prev, and root.next are used
+	len  int        // current list length excluding (this) sentinel element
+}
+
+// Init initializes or clears list l.
+func (l *List[T]) Init() *List[T] {
+	l.root.next = &l.root
+	l.root.prev = &l.root
+	l.len = 0
+	return l
+}
+
+// New returns an initialized list.
+func New[T any]() *List[T] { return new(List[T]).Init() }
+
+// Len returns the number of elements of list l.
+// The complexity is O(1).
+func (l *List[_]) Len() int { return l.len }
+
+// Front returns the first element of list l or nil if the list is empty.
+func (l *List[T]) Front() *Element[T] {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.next
+}
+
+// Back returns the last element of list l or nil if the list is empty.
+func (l *List[T]) Back() *Element[T] {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.prev
+}
+
+// lazyInit lazily initializes a zero List value.
+func (l *List[_]) lazyInit() {
+	if l.root.next == nil {
+		l.Init()
+	}
+}
+
+// insert inserts e after at, increments l.len, and returns e.
+func (l *List[T]) insert(e, at *Element[T]) *Element[T] {
+	e.prev = at
+	e.next = at.next
+	e.prev.next = e
+	e.next.prev = e
+	e.list = l
+	l.len++
+	return e
+}
+
+// insertValue is a convenience wrapper for insert(&Element[T]{Value: v}, at).
+func (l *List[T]) insertValue(v T, at *Element[T]) *Element[T] {
+	return l.insert(&Element[T]{Value: v}, at)
+}
+
+// remove removes e from its list, decrements l.len, and returns e.
+func (l *List[T]) remove(e *Element[T]) *Element[T] {
+	e.prev.next = e.next
+	e.next.prev = e.prev
+	e.next = nil // avoid memory leaks
+	e.prev = nil // avoid memory leaks
+	e.list = nil
+	l.len--
+	return e
+}
+
+// move moves e to next to at and returns e.
+func (l *List[T]) move(e, at *Element[T]) *Element[T] {
+	if e == at {
+		return e
+	}
+	e.prev.next = e.next
+	e.next.prev = e.prev
+
+	e.prev = at
+	e.next = at.next
+	e.prev.next = e
+	e.next.prev = e
+
+	return e
+}
+
+// Remove removes e from l if e is an element of list l.
+// It returns the element value e.Value.
+// The element must not be nil.
+func (l *List[T]) Remove(e *Element[T]) T {
+	if e.list == l {
+		// if e.list == l, l must have been initialized when e was inserted
+		// in l or l == nil (e is a zero Element) and l.remove will crash
+		l.remove(e)
+	}
+	return e.Value
+}
+
+// PushFront inserts a new element e with value v at the front of list l and returns e.
+func (l *List[T]) PushFront(v T) *Element[T] {
+	l.lazyInit()
+	return l.insertValue(v, &l.root)
+}
+
+// PushBack inserts a new element e with value v at the back of list l and returns e.
+func (l *List[T]) PushBack(v T) *Element[T] {
+	l.lazyInit()
+	return l.insertValue(v, l.root.prev)
+}
+
+// InsertBefore inserts a new element e with value v immediately before mark and returns e.
+// If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
+func (l *List[T]) InsertBefore(v T, mark *Element[T]) *Element[T] {
+	if mark.list != l {
+		return nil
+	}
+	// see comment in List.Remove about initialization of l
+	return l.insertValue(v, mark.prev)
+}
+
+// InsertAfter inserts a new element e with value v immediately after mark and returns e.
+// If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
+func (l *List[T]) InsertAfter(v T, mark *Element[T]) *Element[T] {
+	if mark.list != l {
+		return nil
+	}
+	// see comment in List.Remove about initialization of l
+	return l.insertValue(v, mark)
+}
+
+// MoveToFront moves element e to the front of list l.
+// If e is not an element of l, the list is not modified.
+// The element must not be nil.
+func (l *List[T]) MoveToFront(e *Element[T]) {
+	if e.list != l || l.root.next == e {
+		return
+	}
+	// see comment in List.Remove about initialization of l
+	l.move(e, &l.root)
+}
+
+// MoveToBack moves element e to the back of list l.
+// If e is not an element of l, the list is not modified.
+// The element must not be nil.
+func (l *List[T]) MoveToBack(e *Element[T]) {
+	if e.list != l || l.root.prev == e {
+		return
+	}
+	// see comment in List.Remove about initialization of l
+	l.move(e, l.root.prev)
+}
+
+// MoveBefore moves element e to its new position before mark.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
+func (l *List[T]) MoveBefore(e, mark *Element[T]) {
+	if e.list != l || e == mark || mark.list != l {
+		return
+	}
+	l.move(e, mark.prev)
+}
+
+// MoveAfter moves element e to its new position after mark.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
+func (l *List[T]) MoveAfter(e, mark *Element[T]) {
+	if e.list != l || e == mark || mark.list != l {
+		return
+	}
+	l.move(e, mark)
+}
+
+// PushBackList inserts a copy of an other list at the back of list l.
+// The lists l and other may be the same. They must not be nil.
+func (l *List[T]) PushBackList(other *List[T]) {
+	l.lazyInit()
+	for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() {
+		l.insertValue(e.Value, l.root.prev)
+	}
+}
+
+// PushFrontList inserts a copy of an other list at the front of list l.
+// The lists l and other may be the same. They must not be nil.
+func (l *List[T]) PushFrontList(other *List[T]) {
+	l.lazyInit()
+	for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() {
+		l.insertValue(e.Value, &l.root)
+	}
+}
+
+// Transform runs a transform function on a list returning a new list.
+func Transform[TElem1, TElem2 any](lst *List[TElem1], f func(TElem1) TElem2) *List[TElem2] {
+	ret := New[TElem2]()
+	for p := lst.Front(); p != nil; p = p.Next() {
+		ret.PushBack(f(p.Value))
+	}
+	return ret
+}
+
+func CheckListLen[T any](l *List[T], len int) bool {
+	if n := l.Len(); n != len {
+		panic(fmt.Sprintf("l.Len() = %d, want %d", n, len))
+		return false
+	}
+	return true
+}
+
+func CheckListPointers[T any](l *List[T], es []*Element[T]) {
+	root := &l.root
+
+	if !CheckListLen(l, len(es)) {
+		return
+	}
+
+	// zero length lists must be the zero value or properly initialized (sentinel circle)
+	if len(es) == 0 {
+		if l.root.next != nil && l.root.next != root || l.root.prev != nil && l.root.prev != root {
+			panic(fmt.Sprintf("l.root.next = %p, l.root.prev = %p; both should both be nil or %p", l.root.next, l.root.prev, root))
+		}
+		return
+	}
+	// len(es) > 0
+
+	// check internal and external prev/next connections
+	for i, e := range es {
+		prev := root
+		Prev := (*Element[T])(nil)
+		if i > 0 {
+			prev = es[i-1]
+			Prev = prev
+		}
+		if p := e.prev; p != prev {
+			panic(fmt.Sprintf("elt[%d](%p).prev = %p, want %p", i, e, p, prev))
+		}
+		if p := e.Prev(); p != Prev {
+			panic(fmt.Sprintf("elt[%d](%p).Prev() = %p, want %p", i, e, p, Prev))
+		}
+
+		next := root
+		Next := (*Element[T])(nil)
+		if i < len(es)-1 {
+			next = es[i+1]
+			Next = next
+		}
+		if n := e.next; n != next {
+			panic(fmt.Sprintf("elt[%d](%p).next = %p, want %p", i, e, n, next))
+		}
+		if n := e.Next(); n != Next {
+			panic(fmt.Sprintf("elt[%d](%p).Next() = %p, want %p", i, e, n, Next))
+		}
+	}
+}
diff --git a/test/typeparam/listimp2.dir/main.go b/test/typeparam/listimp2.dir/main.go
new file mode 100644
index 0000000..226e1a9
--- /dev/null
+++ b/test/typeparam/listimp2.dir/main.go
@@ -0,0 +1,315 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"strconv"
+)
+
+func TestList() {
+	l := a.New[string]()
+	a.CheckListPointers(l, []*(a.Element[string]){})
+
+	// Single element list
+	e := l.PushFront("a")
+	a.CheckListPointers(l, []*(a.Element[string]){e})
+	l.MoveToFront(e)
+	a.CheckListPointers(l, []*(a.Element[string]){e})
+	l.MoveToBack(e)
+	a.CheckListPointers(l, []*(a.Element[string]){e})
+	l.Remove(e)
+	a.CheckListPointers(l, []*(a.Element[string]){})
+
+	// Bigger list
+	l2 := a.New[int]()
+	e2 := l2.PushFront(2)
+	e1 := l2.PushFront(1)
+	e3 := l2.PushBack(3)
+	e4 := l2.PushBack(600)
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e2, e3, e4})
+
+	l2.Remove(e2)
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e3, e4})
+
+	l2.MoveToFront(e3) // move from middle
+	a.CheckListPointers(l2, []*(a.Element[int]){e3, e1, e4})
+
+	l2.MoveToFront(e1)
+	l2.MoveToBack(e3) // move from middle
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e3})
+
+	l2.MoveToFront(e3) // move from back
+	a.CheckListPointers(l2, []*(a.Element[int]){e3, e1, e4})
+	l2.MoveToFront(e3) // should be no-op
+	a.CheckListPointers(l2, []*(a.Element[int]){e3, e1, e4})
+
+	l2.MoveToBack(e3) // move from front
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e3})
+	l2.MoveToBack(e3) // should be no-op
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e3})
+
+	e2 = l2.InsertBefore(2, e1) // insert before front
+	a.CheckListPointers(l2, []*(a.Element[int]){e2, e1, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertBefore(2, e4) // insert before middle
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e2, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertBefore(2, e3) // insert before back
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e2, e3})
+	l2.Remove(e2)
+
+	e2 = l2.InsertAfter(2, e1) // insert after front
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e2, e4, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertAfter(2, e4) // insert after middle
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e2, e3})
+	l2.Remove(e2)
+	e2 = l2.InsertAfter(2, e3) // insert after back
+	a.CheckListPointers(l2, []*(a.Element[int]){e1, e4, e3, e2})
+	l2.Remove(e2)
+
+	// Check standard iteration.
+	sum := 0
+	for e := l2.Front(); e != nil; e = e.Next() {
+		sum += e.Value
+	}
+	if sum != 604 {
+		panic(fmt.Sprintf("sum over l = %d, want 604", sum))
+	}
+
+	// Clear all elements by iterating
+	var next *a.Element[int]
+	for e := l2.Front(); e != nil; e = next {
+		next = e.Next()
+		l2.Remove(e)
+	}
+	a.CheckListPointers(l2, []*(a.Element[int]){})
+}
+
+func checkList[T comparable](l *a.List[T], es []interface{}) {
+	if !a.CheckListLen(l, len(es)) {
+		return
+	}
+
+	i := 0
+	for e := l.Front(); e != nil; e = e.Next() {
+		le := e.Value
+		// Comparison between a generically-typed variable le and an interface.
+		if le != es[i] {
+			panic(fmt.Sprintf("elt[%d].Value = %v, want %v", i, le, es[i]))
+		}
+		i++
+	}
+}
+
+func TestExtending() {
+	l1 := a.New[int]()
+	l2 := a.New[int]()
+
+	l1.PushBack(1)
+	l1.PushBack(2)
+	l1.PushBack(3)
+
+	l2.PushBack(4)
+	l2.PushBack(5)
+
+	l3 := a.New[int]()
+	l3.PushBackList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushBackList(l2)
+	checkList(l3, []interface{}{1, 2, 3, 4, 5})
+
+	l3 = a.New[int]()
+	l3.PushFrontList(l2)
+	checkList(l3, []interface{}{4, 5})
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1, 2, 3, 4, 5})
+
+	checkList(l1, []interface{}{1, 2, 3})
+	checkList(l2, []interface{}{4, 5})
+
+	l3 = a.New[int]()
+	l3.PushBackList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushBackList(l3)
+	checkList(l3, []interface{}{1, 2, 3, 1, 2, 3})
+
+	l3 = a.New[int]()
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1, 2, 3})
+	l3.PushFrontList(l3)
+	checkList(l3, []interface{}{1, 2, 3, 1, 2, 3})
+
+	l3 = a.New[int]()
+	l1.PushBackList(l3)
+	checkList(l1, []interface{}{1, 2, 3})
+	l1.PushFrontList(l3)
+	checkList(l1, []interface{}{1, 2, 3})
+}
+
+func TestRemove() {
+	l := a.New[int]()
+	e1 := l.PushBack(1)
+	e2 := l.PushBack(2)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2})
+	e := l.Front()
+	l.Remove(e)
+	a.CheckListPointers(l, []*(a.Element[int]){e2})
+	l.Remove(e)
+	a.CheckListPointers(l, []*(a.Element[int]){e2})
+}
+
+func TestIssue4103() {
+	l1 := a.New[int]()
+	l1.PushBack(1)
+	l1.PushBack(2)
+
+	l2 := a.New[int]()
+	l2.PushBack(3)
+	l2.PushBack(4)
+
+	e := l1.Front()
+	l2.Remove(e) // l2 should not change because e is not an element of l2
+	if n := l2.Len(); n != 2 {
+		panic(fmt.Sprintf("l2.Len() = %d, want 2", n))
+	}
+
+	l1.InsertBefore(8, e)
+	if n := l1.Len(); n != 3 {
+		panic(fmt.Sprintf("l1.Len() = %d, want 3", n))
+	}
+}
+
+func TestIssue6349() {
+	l := a.New[int]()
+	l.PushBack(1)
+	l.PushBack(2)
+
+	e := l.Front()
+	l.Remove(e)
+	if e.Value != 1 {
+		panic(fmt.Sprintf("e.value = %d, want 1", e.Value))
+	}
+	if e.Next() != nil {
+		panic(fmt.Sprintf("e.Next() != nil"))
+	}
+	if e.Prev() != nil {
+		panic(fmt.Sprintf("e.Prev() != nil"))
+	}
+}
+
+func TestMove() {
+	l := a.New[int]()
+	e1 := l.PushBack(1)
+	e2 := l.PushBack(2)
+	e3 := l.PushBack(3)
+	e4 := l.PushBack(4)
+
+	l.MoveAfter(e3, e3)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2, e3, e4})
+	l.MoveBefore(e2, e2)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2, e3, e4})
+
+	l.MoveAfter(e3, e2)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2, e3, e4})
+	l.MoveBefore(e2, e3)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e2, e3, e4})
+
+	l.MoveBefore(e2, e4)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e3, e2, e4})
+	e2, e3 = e3, e2
+
+	l.MoveBefore(e4, e1)
+	a.CheckListPointers(l, []*(a.Element[int]){e4, e1, e2, e3})
+	e1, e2, e3, e4 = e4, e1, e2, e3
+
+	l.MoveAfter(e4, e1)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e4, e2, e3})
+	e2, e3, e4 = e4, e2, e3
+
+	l.MoveAfter(e2, e3)
+	a.CheckListPointers(l, []*(a.Element[int]){e1, e3, e2, e4})
+	e2, e3 = e3, e2
+}
+
+// Test PushFront, PushBack, PushFrontList, PushBackList with uninitialized a.List
+func TestZeroList() {
+	var l1 = new(a.List[int])
+	l1.PushFront(1)
+	checkList(l1, []interface{}{1})
+
+	var l2 = new(a.List[int])
+	l2.PushBack(1)
+	checkList(l2, []interface{}{1})
+
+	var l3 = new(a.List[int])
+	l3.PushFrontList(l1)
+	checkList(l3, []interface{}{1})
+
+	var l4 = new(a.List[int])
+	l4.PushBackList(l2)
+	checkList(l4, []interface{}{1})
+}
+
+// Test that a list l is not modified when calling InsertBefore with a mark that is not an element of l.
+func TestInsertBeforeUnknownMark() {
+	var l a.List[int]
+	l.PushBack(1)
+	l.PushBack(2)
+	l.PushBack(3)
+	l.InsertBefore(1, new(a.Element[int]))
+	checkList(&l, []interface{}{1, 2, 3})
+}
+
+// Test that a list l is not modified when calling InsertAfter with a mark that is not an element of l.
+func TestInsertAfterUnknownMark() {
+	var l a.List[int]
+	l.PushBack(1)
+	l.PushBack(2)
+	l.PushBack(3)
+	l.InsertAfter(1, new(a.Element[int]))
+	checkList(&l, []interface{}{1, 2, 3})
+}
+
+// Test that a list l is not modified when calling MoveAfter or MoveBefore with a mark that is not an element of l.
+func TestMoveUnknownMark() {
+	var l1 a.List[int]
+	e1 := l1.PushBack(1)
+
+	var l2 a.List[int]
+	e2 := l2.PushBack(2)
+
+	l1.MoveAfter(e1, e2)
+	checkList(&l1, []interface{}{1})
+	checkList(&l2, []interface{}{2})
+
+	l1.MoveBefore(e1, e2)
+	checkList(&l1, []interface{}{1})
+	checkList(&l2, []interface{}{2})
+}
+
+// Test the Transform function.
+func TestTransform() {
+	l1 := a.New[int]()
+	l1.PushBack(1)
+	l1.PushBack(2)
+	l2 := a.Transform(l1, strconv.Itoa)
+	checkList(l2, []interface{}{"1", "2"})
+}
+
+func main() {
+	TestList()
+	TestExtending()
+	TestRemove()
+	TestIssue4103()
+	TestIssue6349()
+	TestMove()
+	TestZeroList()
+	TestInsertBeforeUnknownMark()
+	TestInsertAfterUnknownMark()
+	TestTransform()
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/listimp2.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/listimp2.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/listimp2.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/lockable.go b/test/typeparam/lockable.go
index d538175..9b20d87 100644
--- a/test/typeparam/lockable.go
+++ b/test/typeparam/lockable.go
@@ -8,29 +8,29 @@
 
 import "sync"
 
-// A _Lockable is a value that may be safely simultaneously accessed
+// A Lockable is a value that may be safely simultaneously accessed
 // from multiple goroutines via the Get and Set methods.
-type _Lockable[T any] struct {
-	T
+type Lockable[T any] struct {
+	x  T
 	mu sync.Mutex
 }
 
-// Get returns the value stored in a _Lockable.
-func (l *_Lockable[T]) get() T {
+// Get returns the value stored in a Lockable.
+func (l *Lockable[T]) get() T {
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	return l.T
+	return l.x
 }
 
-// set sets the value in a _Lockable.
-func (l *_Lockable[T]) set(v T) {
+// set sets the value in a Lockable.
+func (l *Lockable[T]) set(v T) {
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	l.T = v
+	l.x = v
 }
 
 func main() {
-	sl := _Lockable[string]{T: "a"}
+	sl := Lockable[string]{x: "a"}
 	if got := sl.get(); got != "a" {
 		panic(got)
 	}
@@ -39,7 +39,7 @@
 		panic(got)
 	}
 
-	il := _Lockable[int]{T: 1}
+	il := Lockable[int]{x: 1}
 	if got := il.get(); got != 1 {
 		panic(got)
 	}
diff --git a/test/typeparam/mapimp.dir/a.go b/test/typeparam/mapimp.dir/a.go
new file mode 100644
index 0000000..cbfa80a
--- /dev/null
+++ b/test/typeparam/mapimp.dir/a.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+// Map calls the function f on every element of the slice s,
+// returning a new slice of the results.
+func Mapper[F, T any](s []F, f func(F) T) []T {
+	r := make([]T, len(s))
+	for i, v := range s {
+		r[i] = f(v)
+	}
+	return r
+}
diff --git a/test/typeparam/mapimp.dir/main.go b/test/typeparam/mapimp.dir/main.go
new file mode 100644
index 0000000..4d4a4d9
--- /dev/null
+++ b/test/typeparam/mapimp.dir/main.go
@@ -0,0 +1,28 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"reflect"
+	"strconv"
+)
+
+func main() {
+	got := a.Mapper([]int{1, 2, 3}, strconv.Itoa)
+	want := []string{"1", "2", "3"}
+	if !reflect.DeepEqual(got, want) {
+		panic(fmt.Sprintf("got %s, want %s", got, want))
+	}
+
+	fgot := a.Mapper([]float64{2.5, 2.3, 3.5}, func(f float64) string {
+		return strconv.FormatFloat(f, 'f', -1, 64)
+	})
+	fwant := []string{"2.5", "2.3", "3.5"}
+	if !reflect.DeepEqual(fgot, fwant) {
+		panic(fmt.Sprintf("got %s, want %s", fgot, fwant))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mapimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mapimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mapimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/mapsimp.dir/a.go b/test/typeparam/mapsimp.dir/a.go
new file mode 100644
index 0000000..696e2a5
--- /dev/null
+++ b/test/typeparam/mapsimp.dir/a.go
@@ -0,0 +1,108 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+// SliceEqual reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// Keys returns the keys of the map m.
+// The keys will be an indeterminate order.
+func Keys[K comparable, V any](m map[K]V) []K {
+	r := make([]K, 0, len(m))
+	for k := range m {
+		r = append(r, k)
+	}
+	return r
+}
+
+// Values returns the values of the map m.
+// The values will be in an indeterminate order.
+func Values[K comparable, V any](m map[K]V) []V {
+	r := make([]V, 0, len(m))
+	for _, v := range m {
+		r = append(r, v)
+	}
+	return r
+}
+
+// Equal reports whether two maps contain the same key/value pairs.
+// Values are compared using ==.
+func Equal[K, V comparable](m1, m2 map[K]V) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[k]; !ok || v1 != v2 {
+			return false
+		}
+	}
+	return true
+}
+
+// Copy returns a copy of m.
+func Copy[K comparable, V any](m map[K]V) map[K]V {
+	r := make(map[K]V, len(m))
+	for k, v := range m {
+		r[k] = v
+	}
+	return r
+}
+
+// Add adds all key/value pairs in m2 to m1. Keys in m2 that are already
+// present in m1 will be overwritten with the value in m2.
+func Add[K comparable, V any](m1, m2 map[K]V) {
+	for k, v := range m2 {
+		m1[k] = v
+	}
+}
+
+// Sub removes all keys in m2 from m1. Keys in m2 that are not present
+// in m1 are ignored. The values in m2 are ignored.
+func Sub[K comparable, V any](m1, m2 map[K]V) {
+	for k := range m2 {
+		delete(m1, k)
+	}
+}
+
+// Intersect removes all keys from m1 that are not present in m2.
+// Keys in m2 that are not in m1 are ignored. The values in m2 are ignored.
+func Intersect[K comparable, V any](m1, m2 map[K]V) {
+	for k := range m1 {
+		if _, ok := m2[k]; !ok {
+			delete(m1, k)
+		}
+	}
+}
+
+// Filter deletes any key/value pairs from m for which f returns false.
+func Filter[K comparable, V any](m map[K]V, f func(K, V) bool) {
+	for k, v := range m {
+		if !f(k, v) {
+			delete(m, k)
+		}
+	}
+}
+
+// TransformValues applies f to each value in m. The keys remain unchanged.
+func TransformValues[K comparable, V any](m map[K]V, f func(V) V) {
+	for k, v := range m {
+		m[k] = f(v)
+	}
+}
diff --git a/test/typeparam/mapsimp.dir/main.go b/test/typeparam/mapsimp.dir/main.go
new file mode 100644
index 0000000..873660e
--- /dev/null
+++ b/test/typeparam/mapsimp.dir/main.go
@@ -0,0 +1,156 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"math"
+	"sort"
+)
+
+var m1 = map[int]int{1: 2, 2: 4, 4: 8, 8: 16}
+var m2 = map[int]string{1: "2", 2: "4", 4: "8", 8: "16"}
+
+func TestKeys() {
+	want := []int{1, 2, 4, 8}
+
+	got1 := a.Keys(m1)
+	sort.Ints(got1)
+	if !a.SliceEqual(got1, want) {
+		panic(fmt.Sprintf("a.Keys(%v) = %v, want %v", m1, got1, want))
+	}
+
+	got2 := a.Keys(m2)
+	sort.Ints(got2)
+	if !a.SliceEqual(got2, want) {
+		panic(fmt.Sprintf("a.Keys(%v) = %v, want %v", m2, got2, want))
+	}
+}
+
+func TestValues() {
+	got1 := a.Values(m1)
+	want1 := []int{2, 4, 8, 16}
+	sort.Ints(got1)
+	if !a.SliceEqual(got1, want1) {
+		panic(fmt.Sprintf("a.Values(%v) = %v, want %v", m1, got1, want1))
+	}
+
+	got2 := a.Values(m2)
+	want2 := []string{"16", "2", "4", "8"}
+	sort.Strings(got2)
+	if !a.SliceEqual(got2, want2) {
+		panic(fmt.Sprintf("a.Values(%v) = %v, want %v", m2, got2, want2))
+	}
+}
+
+func TestEqual() {
+	if !a.Equal(m1, m1) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", m1, m1))
+	}
+	if a.Equal(m1, nil) {
+		panic(fmt.Sprintf("a.Equal(%v, nil) = true, want false", m1))
+	}
+	if a.Equal(nil, m1) {
+		panic(fmt.Sprintf("a.Equal(nil, %v) = true, want false", m1))
+	}
+	if !a.Equal[int, int](nil, nil) {
+		panic("a.Equal(nil, nil) = false, want true")
+	}
+	if ms := map[int]int{1: 2}; a.Equal(m1, ms) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", m1, ms))
+	}
+
+	// Comparing NaN for equality is expected to fail.
+	mf := map[int]float64{1: 0, 2: math.NaN()}
+	if a.Equal(mf, mf) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", mf, mf))
+	}
+}
+
+func TestCopy() {
+	m2 := a.Copy(m1)
+	if !a.Equal(m1, m2) {
+		panic(fmt.Sprintf("a.Copy(%v) = %v, want %v", m1, m2, m1))
+	}
+	m2[16] = 32
+	if a.Equal(m1, m2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", m1, m2))
+	}
+}
+
+func TestAdd() {
+	mc := a.Copy(m1)
+	a.Add(mc, mc)
+	if !a.Equal(mc, m1) {
+		panic(fmt.Sprintf("a.Add(%v, %v) = %v, want %v", m1, m1, mc, m1))
+	}
+	a.Add(mc, map[int]int{16: 32})
+	want := map[int]int{1: 2, 2: 4, 4: 8, 8: 16, 16: 32}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.Add result = %v, want %v", mc, want))
+	}
+}
+
+func TestSub() {
+	mc := a.Copy(m1)
+	a.Sub(mc, mc)
+	if len(mc) > 0 {
+		panic(fmt.Sprintf("a.Sub(%v, %v) = %v, want empty map", m1, m1, mc))
+	}
+	mc = a.Copy(m1)
+	a.Sub(mc, map[int]int{1: 0})
+	want := map[int]int{2: 4, 4: 8, 8: 16}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.Sub result = %v, want %v", mc, want))
+	}
+}
+
+func TestIntersect() {
+	mc := a.Copy(m1)
+	a.Intersect(mc, mc)
+	if !a.Equal(mc, m1) {
+		panic(fmt.Sprintf("a.Intersect(%v, %v) = %v, want %v", m1, m1, mc, m1))
+	}
+	a.Intersect(mc, map[int]int{1: 0, 2: 0})
+	want := map[int]int{1: 2, 2: 4}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.Intersect result = %v, want %v", mc, want))
+	}
+}
+
+func TestFilter() {
+	mc := a.Copy(m1)
+	a.Filter(mc, func(int, int) bool { return true })
+	if !a.Equal(mc, m1) {
+		panic(fmt.Sprintf("a.Filter(%v, true) = %v, want %v", m1, mc, m1))
+	}
+	a.Filter(mc, func(k, v int) bool { return k < 3 })
+	want := map[int]int{1: 2, 2: 4}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.Filter result = %v, want %v", mc, want))
+	}
+}
+
+func TestTransformValues() {
+	mc := a.Copy(m1)
+	a.TransformValues(mc, func(i int) int { return i / 2 })
+	want := map[int]int{1: 1, 2: 2, 4: 4, 8: 8}
+	if !a.Equal(mc, want) {
+		panic(fmt.Sprintf("a.TransformValues result = %v, want %v", mc, want))
+	}
+}
+
+func main() {
+	TestKeys()
+	TestValues()
+	TestEqual()
+	TestCopy()
+	TestAdd()
+	TestSub()
+	TestIntersect()
+	TestFilter()
+	TestTransformValues()
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mapsimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mapsimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mapsimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/1.dir/a.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/1.dir/a.go
index 10641a7..a668eb5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/1.dir/a.go
@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
+type T[_ any] int
 
-func init() {
-	typeParamsEnabled = true
-}
+func F() { _ = new(T[int]) }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/1.dir/b.go
similarity index 66%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/1.dir/b.go
index 10641a7..af6fef3 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/1.dir/b.go
@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
 package main
 
-func init() {
-	typeParamsEnabled = true
-}
+import "./a"
+
+func main() { a.F() }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/1.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/1.go
index 10641a7..87b4ff4 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/1.go
@@ -1,12 +1,7 @@
+// compiledir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/10.dir/a.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/10.dir/a.go
index 10641a7..95e111d 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/10.dir/a.go
@@ -2,11 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+type I[T any] interface{ M() T }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/10.dir/b.go
similarity index 66%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/10.dir/b.go
index 10641a7..0ef28fd 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/10.dir/b.go
@@ -2,11 +2,16 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
 package main
 
-func init() {
-	typeParamsEnabled = true
+import "./a"
+
+var m = a.I[int].M
+
+var never bool
+
+func main() {
+	if never {
+		m(nil)
+	}
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/10.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/10.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/10.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/mdempsky/11.go b/test/typeparam/mdempsky/11.go
new file mode 100644
index 0000000..e86c038
--- /dev/null
+++ b/test/typeparam/mdempsky/11.go
@@ -0,0 +1,16 @@
+// errorcheck
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Reported by Cuong Manh Le.
+
+package p
+
+type a struct{}
+
+//go:notinheap
+type b a
+
+var _ = (*b)(new(a)) // ERROR "cannot convert"
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/12.dir/a.go
similarity index 62%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/12.dir/a.go
index 10641a7..ee8be93 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/12.dir/a.go
@@ -2,11 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
-
-func init() {
-	typeParamsEnabled = true
+type S[T any] struct {
+	F T
 }
+
+var X = S[int]{}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/12.dir/main.go
similarity index 67%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/12.dir/main.go
index 10641a7..2891322 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/12.dir/main.go
@@ -2,11 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
 package main
 
-func init() {
-	typeParamsEnabled = true
+import (
+	"./a"
+)
+
+func main() {
+	_ = a.X
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/12.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/12.go
index 10641a7..a2dc4da 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/12.go
@@ -1,12 +1,9 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+// Reported by Cuong Manh Le.
 
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/mdempsky/13.go b/test/typeparam/mdempsky/13.go
new file mode 100644
index 0000000..b492774
--- /dev/null
+++ b/test/typeparam/mdempsky/13.go
@@ -0,0 +1,84 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// Interface which will be used as a regular interface type and as a type bound.
+type Mer interface{
+	M()
+}
+
+// Interface that is a superset of Mer.
+type Mer2 interface {
+	M()
+	String() string
+}
+
+func F[T Mer](t T) {
+	T.M(t)
+	t.M()
+}
+
+type MyMer int
+
+func (MyMer) M() {}
+func (MyMer) String() string {
+	return "aa"
+}
+
+// Parameterized interface
+type Abs[T any] interface {
+	Abs() T
+}
+
+func G[T Abs[U], U any](t T) {
+	T.Abs(t)
+	t.Abs()
+}
+
+type MyInt int
+func (m MyInt) Abs() MyInt {
+	if m < 0 {
+		return -m
+	}
+	return m
+}
+
+type Abs2 interface {
+	Abs() MyInt
+}
+
+
+func main() {
+	mm := MyMer(3)
+	ms := struct{ Mer }{Mer: mm }
+
+	// Testing F with an interface type arg: Mer and Mer2
+	F[Mer](mm)
+	F[Mer2](mm)
+	F[struct{ Mer }](ms)
+	F[*struct{ Mer }](&ms)
+
+	ms2 := struct { MyMer }{MyMer: mm}
+	ms3 := struct { *MyMer }{MyMer: &mm}
+
+	// Testing F with a concrete type arg
+	F[MyMer](mm)
+	F[*MyMer](&mm)
+	F[struct{ MyMer }](ms2)
+	F[struct{ *MyMer }](ms3)
+	F[*struct{ MyMer }](&ms2)
+	F[*struct{ *MyMer }](&ms3)
+
+	// Testing G with a concrete type args
+	mi := MyInt(-3)
+	G[MyInt,MyInt](mi)
+
+	// Interface Abs[MyInt] holding an mi.
+	intMi := Abs[MyInt](mi)
+	// First type arg here is Abs[MyInt], an interface type.
+	G[Abs[MyInt],MyInt](intMi)
+}
diff --git a/test/typeparam/mdempsky/14.go b/test/typeparam/mdempsky/14.go
new file mode 100644
index 0000000..ba685bc
--- /dev/null
+++ b/test/typeparam/mdempsky/14.go
@@ -0,0 +1,40 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// Zero returns the zero value of T
+func Zero[T any]() (_ T) {
+	return
+}
+
+type AnyInt[X any] int
+
+func (AnyInt[X]) M() {
+	var have interface{} = Zero[X]()
+	var want interface{} = Zero[MyInt]()
+
+	if have != want {
+		println("FAIL")
+	}
+}
+
+type I interface{ M() }
+
+type MyInt int
+type U = AnyInt[MyInt]
+
+var x = U(0)
+var i I = x
+
+func main() {
+	x.M()
+	U.M(x)
+	(*U).M(&x)
+
+	i.M()
+	I.M(x)
+}
diff --git a/test/typeparam/mdempsky/15.go b/test/typeparam/mdempsky/15.go
new file mode 100644
index 0000000..4899fc7
--- /dev/null
+++ b/test/typeparam/mdempsky/15.go
@@ -0,0 +1,69 @@
+// run -goexperiment fieldtrack -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that generics, promoted methods, and //go:nointerface
+// interoperate as expected.
+
+package main
+
+import (
+	"reflect"
+)
+
+func TypeString[T any]() string {
+	return reflect.TypeOf(new(T)).Elem().String()
+}
+
+func Test[T, Bad, Good any]() {
+	switch interface{}(new(T)).(type) {
+	case Bad:
+		println("FAIL:", TypeString[T](), "matched", TypeString[Bad]())
+	case Good:
+		// ok
+	default:
+		println("FAIL:", TypeString[T](), "did not match", TypeString[Good]())
+	}
+}
+
+func TestE[T any]() { Test[T, interface{ EBad() }, interface{ EGood() }]() }
+func TestX[T any]() { Test[T, interface{ XBad() }, interface{ XGood() }]() }
+
+type E struct{}
+
+//go:nointerface
+func (E) EBad()  {}
+func (E) EGood() {}
+
+type X[T any] struct{ E }
+
+//go:nointerface
+func (X[T]) XBad()  {}
+func (X[T]) XGood() {}
+
+type W struct{ X[int] }
+
+func main() {
+	_ = E.EGood
+	_ = E.EBad
+
+	TestE[E]()
+
+	_ = X[int].EGood
+	_ = X[int].EBad
+	_ = X[int].XGood
+	_ = X[int].XBad
+
+	TestE[X[int]]()
+	TestX[X[int]]()
+
+	_ = W.EGood
+	_ = W.EBad
+	_ = W.XGood
+	_ = W.XBad
+
+	TestE[W]()
+	TestX[W]()
+}
diff --git a/test/typeparam/mdempsky/2.go b/test/typeparam/mdempsky/2.go
new file mode 100644
index 0000000..f09730f
--- /dev/null
+++ b/test/typeparam/mdempsky/2.go
@@ -0,0 +1,20 @@
+// compile -G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type T[A, B, C any] int
+
+func (T[A, B, C]) m(x int) {
+	if x <= 0 {
+		return
+	}
+	T[B, C, A](0).m(x - 1)
+}
+
+func main() {
+	T[int8, int16, int32](0).m(3)
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/3.dir/a.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/3.dir/a.go
index 10641a7..cf456e8 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/3.dir/a.go
@@ -2,11 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+func F[T interface{ chan int }](c T) {}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/3.dir/b.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/3.dir/b.go
index 10641a7..0cfd142 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/3.dir/b.go
@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package b
 
-package main
+import "./a"
 
-func init() {
-	typeParamsEnabled = true
-}
+func g() { a.F(make(chan int)) }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/3.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/3.go
index 10641a7..87b4ff4 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/3.go
@@ -1,12 +1,7 @@
+// compiledir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/4.dir/a.go
similarity index 62%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/4.dir/a.go
index 10641a7..cb67294 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/4.dir/a.go
@@ -2,11 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
-
-func init() {
-	typeParamsEnabled = true
+func F[T any](T) {
+Loop:
+	for {
+		break Loop
+	}
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/4.dir/b.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/4.dir/b.go
index 10641a7..e1fb0e7 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/4.dir/b.go
@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package b
 
-package main
+import "./a"
 
-func init() {
-	typeParamsEnabled = true
-}
+func f() { a.F(0) }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/4.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/4.go
index 10641a7..87b4ff4 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/4.go
@@ -1,12 +1,7 @@
+// compiledir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/5.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/5.go
index 10641a7..0d1ad39 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/5.go
@@ -1,12 +1,15 @@
+// compile -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
+type X[T any] int
 
-func init() {
-	typeParamsEnabled = true
+func (X[T]) F(T) {}
+
+func x() {
+	X[interface{}](0).F(0)
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/6.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/6.go
index 10641a7..a26ff62 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/6.go
@@ -1,12 +1,11 @@
+// compile -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
+type I[T any] interface{ M() T }
 
-func init() {
-	typeParamsEnabled = true
-}
+var _ = I[int].M
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/7.dir/a.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/7.dir/a.go
index 10641a7..59c5995 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/7.dir/a.go
@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
+type I[T any] interface{ M() T }
 
-func init() {
-	typeParamsEnabled = true
-}
+var X I[int]
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/7.dir/b.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/7.dir/b.go
index 10641a7..9f70530 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/7.dir/b.go
@@ -2,11 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package b
 
-package main
+import "./a"
 
-func init() {
-	typeParamsEnabled = true
-}
+var _ = a.X
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/7.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/7.go
index 10641a7..87b4ff4 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/7.go
@@ -1,12 +1,7 @@
+// compiledir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/8.dir/a.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/8.dir/a.go
index 10641a7..607fe5e 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/8.dir/a.go
@@ -2,11 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+func F[T interface{ comparable }]() {}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/8.dir/b.go
similarity index 67%
rename from src/cmd/gofmt/gofmt_typeparams_test.go
rename to test/typeparam/mdempsky/8.dir/b.go
index 10641a7..ef2637b 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/8.dir/b.go
@@ -2,11 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package b
 
-package main
+import "./a"
 
 func init() {
-	typeParamsEnabled = true
+	a.F[func()]() // ERROR "does not satisfy comparable"
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/8.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/8.go
index 10641a7..32cf4b8 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/8.go
@@ -1,12 +1,7 @@
+// errorcheckdir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mdempsky/9.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mdempsky/9.go
index 10641a7..b72516c 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mdempsky/9.go
@@ -1,12 +1,11 @@
+// compile -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
+func f[V any]() []V { return []V{0: *new(V)} }
 
-func init() {
-	typeParamsEnabled = true
-}
+func g() { f[int]() }
diff --git a/test/typeparam/min.go b/test/typeparam/min.go
index a3e4464..d6c65d6 100644
--- a/test/typeparam/min.go
+++ b/test/typeparam/min.go
@@ -11,7 +11,7 @@
 )
 
 type Ordered interface {
-	type int, int64, float64
+	~int | ~int64 | ~float64 | ~string
 }
 
 func min[T Ordered](x, y T) T {
@@ -38,4 +38,13 @@
 	if got := min(3.5, 2.0); got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
+
+	const want2 = "ay"
+	if got := min[string]("bb", "ay"); got != want2 {
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+
+	if got := min("bb", "ay"); got != want2 {
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
 }
diff --git a/test/typeparam/mincheck.dir/a.go b/test/typeparam/mincheck.dir/a.go
new file mode 100644
index 0000000..fa0f249
--- /dev/null
+++ b/test/typeparam/mincheck.dir/a.go
@@ -0,0 +1,16 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Ordered interface {
+	int | int64 | float64
+}
+
+func Min[T Ordered](x, y T) T {
+	if x < y {
+		return x
+	}
+	return y
+}
diff --git a/test/typeparam/mincheck.dir/main.go b/test/typeparam/mincheck.dir/main.go
new file mode 100644
index 0000000..9cf2c6b
--- /dev/null
+++ b/test/typeparam/mincheck.dir/main.go
@@ -0,0 +1,38 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	const want = 2
+	if got := a.Min[int](2, 3); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Min(2, 3); got != want {
+		panic(fmt.Sprintf("want %d, got %d", want, got))
+	}
+
+	if got := a.Min[float64](3.5, 2.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Min(3.5, 2.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	const want2 = "ay"
+	if got := a.Min[string]("bb", "ay"); got != want2 { // ERROR "string does not satisfy"
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+
+	if got := a.Min("bb", "ay"); got != want2 { // ERROR "string does not satisfy"
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mincheck.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mincheck.go
index 10641a7..32cf4b8 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mincheck.go
@@ -1,12 +1,7 @@
+// errorcheckdir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/minimp.dir/a.go b/test/typeparam/minimp.dir/a.go
new file mode 100644
index 0000000..fabde62
--- /dev/null
+++ b/test/typeparam/minimp.dir/a.go
@@ -0,0 +1,16 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Ordered interface {
+	~int | ~int64 | ~float64 | ~string
+}
+
+func Min[T Ordered](x, y T) T {
+	if x < y {
+		return x
+	}
+	return y
+}
diff --git a/test/typeparam/minimp.dir/main.go b/test/typeparam/minimp.dir/main.go
new file mode 100644
index 0000000..509f5aa
--- /dev/null
+++ b/test/typeparam/minimp.dir/main.go
@@ -0,0 +1,38 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	const want = 2
+	if got := a.Min[int](2, 3); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Min(2, 3); got != want {
+		panic(fmt.Sprintf("want %d, got %d", want, got))
+	}
+
+	if got := a.Min[float64](3.5, 2.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := a.Min(3.5, 2.0); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	const want2 = "ay"
+	if got := a.Min[string]("bb", "ay"); got != want2 {
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+
+	if got := a.Min("bb", "ay"); got != want2 {
+		panic(fmt.Sprintf("got %d, want %d", got, want2))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/minimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/minimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/minimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/mutualimp.dir/a.go b/test/typeparam/mutualimp.dir/a.go
new file mode 100644
index 0000000..5b924d3
--- /dev/null
+++ b/test/typeparam/mutualimp.dir/a.go
@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type X int
+
+func (x X) M() X { return x }
+
+func F[T interface{ M() U }, U interface{ M() T }]() {}
+func G()                                             { F[X, X]() }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mutualimp.dir/b.go
similarity index 62%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mutualimp.dir/b.go
index 10641a7..83cc3af 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mutualimp.dir/b.go
@@ -2,11 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package b
 
-package main
+import "./a"
 
-func init() {
-	typeParamsEnabled = true
+func H() {
+	a.F[a.X, a.X]()
+	a.G()
 }
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/mutualimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/mutualimp.go
index 10641a7..87b4ff4 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/mutualimp.go
@@ -1,12 +1,7 @@
+// compiledir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/nested.go b/test/typeparam/nested.go
new file mode 100644
index 0000000..c0037a3
--- /dev/null
+++ b/test/typeparam/nested.go
@@ -0,0 +1,134 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This test case stress tests a number of subtle cases involving
+// nested type-parameterized declarations. At a high-level, it
+// declares a generic function that contains a generic type
+// declaration:
+//
+//	func F[A intish]() {
+//		type T[B intish] struct{}
+//
+//		// store reflect.Type tuple (A, B, F[A].T[B]) in tests
+//	}
+//
+// It then instantiates this function with a variety of type arguments
+// for A and B. Particularly tricky things like shadowed types.
+//
+// From this data it tests two things:
+//
+// 1. Given tuples (A, B, F[A].T[B]) and (A', B', F[A'].T[B']),
+//    F[A].T[B] should be identical to F[A'].T[B'] iff (A, B) is
+//    identical to (A', B').
+//
+// 2. A few of the instantiations are constructed to be identical, and
+//    it tests that exactly these pairs are duplicated (by golden
+//    output comparison to nested.out).
+//
+// In both cases, we're effectively using the compiler's existing
+// runtime.Type handling (which is well tested) of type identity of A
+// and B as a way to help bootstrap testing and validate its new
+// runtime.Type handling of F[A].T[B].
+//
+// This isn't perfect, but it smoked out a handful of issues in
+// gotypes2 and unified IR.
+
+package main
+
+import (
+	"fmt"
+	"reflect"
+)
+
+type test struct {
+	TArgs    [2]reflect.Type
+	Instance reflect.Type
+}
+
+var tests []test
+
+type intish interface{ ~int }
+
+type Int int
+type GlobalInt = Int // allow access to global Int, even when shadowed
+
+func F[A intish]() {
+	add := func(B, T interface{}) {
+		tests = append(tests, test{
+			TArgs: [2]reflect.Type{
+				reflect.TypeOf(A(0)),
+				reflect.TypeOf(B),
+			},
+			Instance: reflect.TypeOf(T),
+		})
+	}
+
+	type Int int
+
+	type T[B intish] struct{}
+
+	add(int(0), T[int]{})
+	add(Int(0), T[Int]{})
+	add(GlobalInt(0), T[GlobalInt]{})
+	add(A(0), T[A]{}) // NOTE: intentionally dups with int and GlobalInt
+
+	type U[_ any] int
+	type V U[int]
+	type W V
+
+	add(U[int](0), T[U[int]]{})
+	add(U[Int](0), T[U[Int]]{})
+	add(U[GlobalInt](0), T[U[GlobalInt]]{})
+	add(U[A](0), T[U[A]]{}) // NOTE: intentionally dups with U[int] and U[GlobalInt]
+	add(V(0), T[V]{})
+	add(W(0), T[W]{})
+}
+
+func main() {
+	type Int int
+
+	F[int]()
+	F[Int]()
+	F[GlobalInt]()
+
+	type U[_ any] int
+	type V U[int]
+	type W V
+
+	F[U[int]]()
+	F[U[Int]]()
+	F[U[GlobalInt]]()
+	F[V]()
+	F[W]()
+
+	type X[A any] U[X[A]]
+
+	F[X[int]]()
+	F[X[Int]]()
+	F[X[GlobalInt]]()
+
+	for j, tj := range tests {
+		for i, ti := range tests[:j+1] {
+			if (ti.TArgs == tj.TArgs) != (ti.Instance == tj.Instance) {
+				fmt.Printf("FAIL: %d,%d: %s, but %s\n", i, j, eq(ti.TArgs, tj.TArgs), eq(ti.Instance, tj.Instance))
+			}
+
+			// The test is constructed so we should see a few identical types.
+			// See "NOTE" comments above.
+			if i != j && ti.Instance == tj.Instance {
+				fmt.Printf("%d,%d: %v\n", i, j, ti.Instance)
+			}
+		}
+	}
+}
+
+func eq(a, b interface{}) string {
+	op := "=="
+	if a != b {
+		op = "!="
+	}
+	return fmt.Sprintf("%v %s %v", a, op, b)
+}
diff --git a/test/typeparam/nested.out b/test/typeparam/nested.out
new file mode 100644
index 0000000..9110518
--- /dev/null
+++ b/test/typeparam/nested.out
@@ -0,0 +1,4 @@
+0,3: main.T·2[int;int]
+4,7: main.T·2[int;"".U·3[int;int]]
+22,23: main.T·2["".Int;"".Int]
+26,27: main.T·2["".Int;"".U·3["".Int;"".Int]]
diff --git a/test/typeparam/ordered.go b/test/typeparam/ordered.go
index 448db68..0f539d6 100644
--- a/test/typeparam/ordered.go
+++ b/test/typeparam/ordered.go
@@ -13,15 +13,15 @@
 )
 
 type Ordered interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
 type orderedSlice[Elem Ordered] []Elem
 
-func (s orderedSlice[Elem]) Len() int           { return len(s) }
+func (s orderedSlice[Elem]) Len() int { return len(s) }
 func (s orderedSlice[Elem]) Less(i, j int) bool {
 	if s[i] < s[j] {
 		return true
@@ -32,7 +32,7 @@
 	}
 	return false
 }
-func (s orderedSlice[Elem]) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+func (s orderedSlice[Elem]) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
 
 func _OrderedSlice[Elem Ordered](s []Elem) {
 	sort.Sort(orderedSlice[Elem](s))
@@ -68,7 +68,7 @@
 	}
 	for i := len(s1) - 1; i > 0; i-- {
 		if s1[i] < s1[i-1] {
-			fmt.Printf("%s: element %d (%v) < element %d (%v)", name, i, s1[i], i - 1, s1[i - 1])
+			fmt.Printf("%s: element %d (%v) < element %d (%v)", name, i, s1[i], i-1, s1[i-1])
 			ok = false
 		}
 	}
diff --git a/test/typeparam/orderedmap.go b/test/typeparam/orderedmap.go
index db1b374..1f07733 100644
--- a/test/typeparam/orderedmap.go
+++ b/test/typeparam/orderedmap.go
@@ -15,10 +15,10 @@
 )
 
 type Ordered interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr,
-                float32, float64,
-                string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
 // _Map is an ordered map.
@@ -230,7 +230,7 @@
 		values: c,
 		done:   d,
 	}
-	r := &_Receiver[Elem] {
+	r := &_Receiver[Elem]{
 		values: c,
 		done:   d,
 	}
diff --git a/test/typeparam/orderedmapsimp.dir/a.go b/test/typeparam/orderedmapsimp.dir/a.go
new file mode 100644
index 0000000..d6a2de5
--- /dev/null
+++ b/test/typeparam/orderedmapsimp.dir/a.go
@@ -0,0 +1,226 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+import (
+	"context"
+	"runtime"
+)
+
+type Ordered interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
+}
+
+// Map is an ordered map.
+type Map[K, V any] struct {
+	root    *node[K, V]
+	compare func(K, K) int
+}
+
+// node is the type of a node in the binary tree.
+type node[K, V any] struct {
+	key         K
+	val         V
+	left, right *node[K, V]
+}
+
+// New returns a new map. It takes a comparison function that compares two
+// keys and returns < 0 if the first is less, == 0 if they are equal,
+// > 0 if the first is greater.
+func New[K, V any](compare func(K, K) int) *Map[K, V] {
+	return &Map[K, V]{compare: compare}
+}
+
+// NewOrdered returns a new map whose key is an ordered type.
+// This is like New, but does not require providing a compare function.
+// The map compare function uses the obvious key ordering.
+func NewOrdered[K Ordered, V any]() *Map[K, V] {
+	return New[K, V](func(k1, k2 K) int {
+		switch {
+		case k1 < k2:
+			return -1
+		case k1 > k2:
+			return 1
+		default:
+			return 0
+		}
+	})
+}
+
+// find looks up key in the map, returning either a pointer to the slot of the
+// node holding key, or a pointer to the slot where a node would go.
+func (m *Map[K, V]) find(key K) **node[K, V] {
+	pn := &m.root
+	for *pn != nil {
+		switch cmp := m.compare(key, (*pn).key); {
+		case cmp < 0:
+			pn = &(*pn).left
+		case cmp > 0:
+			pn = &(*pn).right
+		default:
+			return pn
+		}
+	}
+	return pn
+}
+
+// Insert inserts a new key/value into the map.
+// If the key is already present, the value is replaced.
+// Reports whether this is a new key.
+func (m *Map[K, V]) Insert(key K, val V) bool {
+	pn := m.find(key)
+	if *pn != nil {
+		(*pn).val = val
+		return false
+	}
+	*pn = &node[K, V]{key: key, val: val}
+	return true
+}
+
+// Find returns the value associated with a key, or the zero value
+// if not present. The second result reports whether the key was found.
+func (m *Map[K, V]) Find(key K) (V, bool) {
+	pn := m.find(key)
+	if *pn == nil {
+		var zero V
+		return zero, false
+	}
+	return (*pn).val, true
+}
+
+// keyValue is a pair of key and value used while iterating.
+type keyValue[K, V any] struct {
+	key K
+	val V
+}
+
+// iterate returns an iterator that traverses the map.
+func (m *Map[K, V]) Iterate() *Iterator[K, V] {
+	sender, receiver := Ranger[keyValue[K, V]]()
+	var f func(*node[K, V]) bool
+	f = func(n *node[K, V]) bool {
+		if n == nil {
+			return true
+		}
+		// Stop the traversal if Send fails, which means that
+		// nothing is listening to the receiver.
+		return f(n.left) &&
+			sender.Send(context.Background(), keyValue[K, V]{n.key, n.val}) &&
+			f(n.right)
+	}
+	go func() {
+		f(m.root)
+		sender.Close()
+	}()
+	return &Iterator[K, V]{receiver}
+}
+
+// Iterator is used to iterate over the map.
+type Iterator[K, V any] struct {
+	r *Receiver[keyValue[K, V]]
+}
+
+// Next returns the next key and value pair, and a boolean that reports
+// whether they are valid. If not valid, we have reached the end of the map.
+func (it *Iterator[K, V]) Next() (K, V, bool) {
+	keyval, ok := it.r.Next(context.Background())
+	if !ok {
+		var zerok K
+		var zerov V
+		return zerok, zerov, false
+	}
+	return keyval.key, keyval.val, true
+}
+
+// Equal reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// Ranger returns a Sender and a Receiver. The Receiver provides a
+// Next method to retrieve values. The Sender provides a Send method
+// to send values and a Close method to stop sending values. The Next
+// method indicates when the Sender has been closed, and the Send
+// method indicates when the Receiver has been freed.
+//
+// This is a convenient way to exit a goroutine sending values when
+// the receiver stops reading them.
+func Ranger[Elem any]() (*Sender[Elem], *Receiver[Elem]) {
+	c := make(chan Elem)
+	d := make(chan struct{})
+	s := &Sender[Elem]{
+		values: c,
+		done:   d,
+	}
+	r := &Receiver[Elem]{
+		values: c,
+		done:   d,
+	}
+	runtime.SetFinalizer(r, (*Receiver[Elem]).finalize)
+	return s, r
+}
+
+// A Sender is used to send values to a Receiver.
+type Sender[Elem any] struct {
+	values chan<- Elem
+	done   <-chan struct{}
+}
+
+// Send sends a value to the receiver. It reports whether the value was sent.
+// The value will not be sent if the context is closed or the receiver
+// is freed.
+func (s *Sender[Elem]) Send(ctx context.Context, v Elem) bool {
+	select {
+	case <-ctx.Done():
+		return false
+	case s.values <- v:
+		return true
+	case <-s.done:
+		return false
+	}
+}
+
+// Close tells the receiver that no more values will arrive.
+// After Close is called, the Sender may no longer be used.
+func (s *Sender[Elem]) Close() {
+	close(s.values)
+}
+
+// A Receiver receives values from a Sender.
+type Receiver[Elem any] struct {
+	values <-chan Elem
+	done   chan<- struct{}
+}
+
+// Next returns the next value from the channel. The bool result indicates
+// whether the value is valid.
+func (r *Receiver[Elem]) Next(ctx context.Context) (v Elem, ok bool) {
+	select {
+	case <-ctx.Done():
+	case v, ok = <-r.values:
+	}
+	return v, ok
+}
+
+// finalize is a finalizer for the receiver.
+func (r *Receiver[Elem]) finalize() {
+	close(r.done)
+}
diff --git a/test/typeparam/orderedmapsimp.dir/main.go b/test/typeparam/orderedmapsimp.dir/main.go
new file mode 100644
index 0000000..978f1e7
--- /dev/null
+++ b/test/typeparam/orderedmapsimp.dir/main.go
@@ -0,0 +1,64 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"bytes"
+	"fmt"
+)
+
+func TestMap() {
+	m := a.New[[]byte, int](bytes.Compare)
+
+	if _, found := m.Find([]byte("a")); found {
+		panic(fmt.Sprintf("unexpectedly found %q in empty map", []byte("a")))
+	}
+
+	for _, c := range []int{'a', 'c', 'b'} {
+		if !m.Insert([]byte(string(c)), c) {
+			panic(fmt.Sprintf("key %q unexpectedly already present", []byte(string(c))))
+		}
+	}
+	if m.Insert([]byte("c"), 'x') {
+		panic(fmt.Sprintf("key %q unexpectedly not present", []byte("c")))
+	}
+
+	if v, found := m.Find([]byte("a")); !found {
+		panic(fmt.Sprintf("did not find %q", []byte("a")))
+	} else if v != 'a' {
+		panic(fmt.Sprintf("key %q returned wrong value %c, expected %c", []byte("a"), v, 'a'))
+	}
+	if v, found := m.Find([]byte("c")); !found {
+		panic(fmt.Sprintf("did not find %q", []byte("c")))
+	} else if v != 'x' {
+		panic(fmt.Sprintf("key %q returned wrong value %c, expected %c", []byte("c"), v, 'x'))
+	}
+
+	if _, found := m.Find([]byte("d")); found {
+		panic(fmt.Sprintf("unexpectedly found %q", []byte("d")))
+	}
+
+	gather := func(it *a.Iterator[[]byte, int]) []int {
+		var r []int
+		for {
+			_, v, ok := it.Next()
+			if !ok {
+				return r
+			}
+			r = append(r, v)
+		}
+	}
+	got := gather(m.Iterate())
+	want := []int{'a', 'b', 'x'}
+	if !a.SliceEqual(got, want) {
+		panic(fmt.Sprintf("Iterate returned %v, want %v", got, want))
+	}
+
+}
+
+func main() {
+	TestMap()
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/orderedmapsimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/orderedmapsimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/orderedmapsimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/pair.go b/test/typeparam/pair.go
index 7faf083..c1427b9 100644
--- a/test/typeparam/pair.go
+++ b/test/typeparam/pair.go
@@ -24,7 +24,11 @@
 	if got, want := unsafe.Sizeof(p.f2), uintptr(8); got != want {
 		panic(fmt.Sprintf("unexpected f2 size == %d, want %d", got, want))
 	}
-	type mypair struct { f1 int32; f2 int64 }
+
+	type mypair struct {
+		f1 int32
+		f2 int64
+	}
 	mp := mypair(p)
 	if mp.f1 != 1 || mp.f2 != 2 {
 		panic(fmt.Sprintf("mp == %#v, want %#v", mp, mypair{1, 2}))
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/pairimp.dir/a.go
similarity index 62%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/pairimp.dir/a.go
index 10641a7..a984fba 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/pairimp.dir/a.go
@@ -2,11 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
+package a
 
-package main
-
-func init() {
-	typeParamsEnabled = true
+type Pair[F1, F2 any] struct {
+	Field1 F1
+	Field2 F2
 }
diff --git a/test/typeparam/pairimp.dir/main.go b/test/typeparam/pairimp.dir/main.go
new file mode 100644
index 0000000..027fdd9
--- /dev/null
+++ b/test/typeparam/pairimp.dir/main.go
@@ -0,0 +1,30 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"unsafe"
+)
+
+func main() {
+	p := a.Pair[int32, int64]{1, 2}
+	if got, want := unsafe.Sizeof(p.Field1), uintptr(4); got != want {
+		panic(fmt.Sprintf("unexpected f1 size == %d, want %d", got, want))
+	}
+	if got, want := unsafe.Sizeof(p.Field2), uintptr(8); got != want {
+		panic(fmt.Sprintf("unexpected f2 size == %d, want %d", got, want))
+	}
+
+	type mypair struct {
+		Field1 int32
+		Field2 int64
+	}
+	mp := mypair(p)
+	if mp.Field1 != 1 || mp.Field2 != 2 {
+		panic(fmt.Sprintf("mp == %#v, want %#v", mp, mypair{1, 2}))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/pairimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/pairimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/pairimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/sets.go b/test/typeparam/sets.go
index 2585144..4f07b59 100644
--- a/test/typeparam/sets.go
+++ b/test/typeparam/sets.go
@@ -160,7 +160,7 @@
 	vals := s1.Values()
 	sort.Ints(vals)
 	w1 := []int{1, 2, 3, 4}
-	if !_SliceEqual(vals,  w1) {
+	if !_SliceEqual(vals, w1) {
 		panic(fmt.Sprintf("(%v).Values() == %v, want %v", s1, vals, w1))
 	}
 }
diff --git a/test/typeparam/setsimp.dir/a.go b/test/typeparam/setsimp.dir/a.go
new file mode 100644
index 0000000..92449ce
--- /dev/null
+++ b/test/typeparam/setsimp.dir/a.go
@@ -0,0 +1,128 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+// SliceEqual reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func SliceEqual[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// A Set is a set of elements of some type.
+type Set[Elem comparable] struct {
+	m map[Elem]struct{}
+}
+
+// Make makes a new set.
+func Make[Elem comparable]() Set[Elem] {
+	return Set[Elem]{m: make(map[Elem]struct{})}
+}
+
+// Add adds an element to a set.
+func (s Set[Elem]) Add(v Elem) {
+	s.m[v] = struct{}{}
+}
+
+// Delete removes an element from a set. If the element is not present
+// in the set, this does nothing.
+func (s Set[Elem]) Delete(v Elem) {
+	delete(s.m, v)
+}
+
+// Contains reports whether v is in the set.
+func (s Set[Elem]) Contains(v Elem) bool {
+	_, ok := s.m[v]
+	return ok
+}
+
+// Len returns the number of elements in the set.
+func (s Set[Elem]) Len() int {
+	return len(s.m)
+}
+
+// Values returns the values in the set.
+// The values will be in an indeterminate order.
+func (s Set[Elem]) Values() []Elem {
+	r := make([]Elem, 0, len(s.m))
+	for v := range s.m {
+		r = append(r, v)
+	}
+	return r
+}
+
+// Equal reports whether two sets contain the same elements.
+func Equal[Elem comparable](s1, s2 Set[Elem]) bool {
+	if len(s1.m) != len(s2.m) {
+		return false
+	}
+	for v1 := range s1.m {
+		if !s2.Contains(v1) {
+			return false
+		}
+	}
+	return true
+}
+
+// Copy returns a copy of s.
+func (s Set[Elem]) Copy() Set[Elem] {
+	r := Set[Elem]{m: make(map[Elem]struct{}, len(s.m))}
+	for v := range s.m {
+		r.m[v] = struct{}{}
+	}
+	return r
+}
+
+// AddSet adds all the elements of s2 to s.
+func (s Set[Elem]) AddSet(s2 Set[Elem]) {
+	for v := range s2.m {
+		s.m[v] = struct{}{}
+	}
+}
+
+// SubSet removes all elements in s2 from s.
+// Values in s2 that are not in s are ignored.
+func (s Set[Elem]) SubSet(s2 Set[Elem]) {
+	for v := range s2.m {
+		delete(s.m, v)
+	}
+}
+
+// Intersect removes all elements from s that are not present in s2.
+// Values in s2 that are not in s are ignored.
+func (s Set[Elem]) Intersect(s2 Set[Elem]) {
+	for v := range s.m {
+		if !s2.Contains(v) {
+			delete(s.m, v)
+		}
+	}
+}
+
+// Iterate calls f on every element in the set.
+func (s Set[Elem]) Iterate(f func(Elem)) {
+	for v := range s.m {
+		f(v)
+	}
+}
+
+// Filter deletes any elements from s for which f returns false.
+func (s Set[Elem]) Filter(f func(Elem) bool) {
+	for v := range s.m {
+		if !f(v) {
+			delete(s.m, v)
+		}
+	}
+}
diff --git a/test/typeparam/setsimp.dir/main.go b/test/typeparam/setsimp.dir/main.go
new file mode 100644
index 0000000..8fd1657
--- /dev/null
+++ b/test/typeparam/setsimp.dir/main.go
@@ -0,0 +1,156 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"sort"
+)
+
+func TestSet() {
+	s1 := a.Make[int]()
+	if got := s1.Len(); got != 0 {
+		panic(fmt.Sprintf("Len of empty set = %d, want 0", got))
+	}
+	s1.Add(1)
+	s1.Add(1)
+	s1.Add(1)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	s1.Add(2)
+	s1.Add(3)
+	s1.Add(4)
+	if got := s1.Len(); got != 4 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 4", s1, got))
+	}
+	if !s1.Contains(1) {
+		panic(fmt.Sprintf("(%v).Contains(1) == false, want true", s1))
+	}
+	if s1.Contains(5) {
+		panic(fmt.Sprintf("(%v).Contains(5) == true, want false", s1))
+	}
+	vals := s1.Values()
+	sort.Ints(vals)
+	w1 := []int{1, 2, 3, 4}
+	if !a.SliceEqual(vals, w1) {
+		panic(fmt.Sprintf("(%v).Values() == %v, want %v", s1, vals, w1))
+	}
+}
+
+func TestEqual() {
+	s1 := a.Make[string]()
+	s2 := a.Make[string]()
+	if !a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s1.Add("hello")
+	s1.Add("world")
+	if got := s1.Len(); got != 2 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 2", s1, got))
+	}
+	if a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", s1, s2))
+	}
+}
+
+func TestCopy() {
+	s1 := a.Make[float64]()
+	s1.Add(0)
+	s2 := s1.Copy()
+	if !a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s1.Add(1)
+	if a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", s1, s2))
+	}
+}
+
+func TestAddSet() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := a.Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.AddSet(s2)
+	if got := s1.Len(); got != 3 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 3", s1, got))
+	}
+	s2.Add(1)
+	if !a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s2))
+	}
+}
+
+func TestSubSet() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := a.Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.SubSet(s2)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	if vals, want := s1.Values(), []int{1}; !a.SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after SubSet got %v, want %v", vals, want))
+	}
+}
+
+func TestIntersect() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s2 := a.Make[int]()
+	s2.Add(2)
+	s2.Add(3)
+	s1.Intersect(s2)
+	if got := s1.Len(); got != 1 {
+		panic(fmt.Sprintf("(%v).Len() == %d, want 1", s1, got))
+	}
+	if vals, want := s1.Values(), []int{2}; !a.SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after Intersect got %v, want %v", vals, want))
+	}
+}
+
+func TestIterate() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s1.Add(3)
+	s1.Add(4)
+	tot := 0
+	s1.Iterate(func(i int) { tot += i })
+	if tot != 10 {
+		panic(fmt.Sprintf("total of %v == %d, want 10", s1, tot))
+	}
+}
+
+func TestFilter() {
+	s1 := a.Make[int]()
+	s1.Add(1)
+	s1.Add(2)
+	s1.Add(3)
+	s1.Filter(func(v int) bool { return v%2 == 0 })
+	if vals, want := s1.Values(), []int{2}; !a.SliceEqual(vals, want) {
+		panic(fmt.Sprintf("after Filter got %v, want %v", vals, want))
+	}
+
+}
+
+func main() {
+	TestSet()
+	TestEqual()
+	TestCopy()
+	TestAddSet()
+	TestSubSet()
+	TestIntersect()
+	TestIterate()
+	TestFilter()
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/setsimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/setsimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/setsimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/settable.go b/test/typeparam/settable.go
index 588166d..99455e9 100644
--- a/test/typeparam/settable.go
+++ b/test/typeparam/settable.go
@@ -13,13 +13,13 @@
 
 // Various implementations of fromStrings().
 
-type _Setter[B any] interface {
+type Setter[B any] interface {
 	Set(string)
 	type *B
 }
 
 // Takes two type parameters where PT = *T
-func fromStrings1[T any, PT _Setter[T]](s []string) []T {
+func fromStrings1[T any, PT Setter[T]](s []string) []T {
 	result := make([]T, len(s))
 	for i, v := range s {
 		// The type of &result[i] is *T which is in the type list
@@ -31,7 +31,7 @@
 	return result
 }
 
-func fromStrings1a[T any, PT _Setter[T]](s []string) []PT {
+func fromStrings1a[T any, PT Setter[T]](s []string) []PT {
 	result := make([]PT, len(s))
 	for i, v := range s {
 		// The type new(T) is *T which is in the type list
@@ -44,7 +44,6 @@
 	return result
 }
 
-
 // Takes one type parameter and a set function
 func fromStrings2[T any](s []string, set func(*T, string)) []T {
 	results := make([]T, len(s))
@@ -54,12 +53,12 @@
 	return results
 }
 
-type _Setter2 interface {
+type Setter2 interface {
 	Set(string)
 }
 
 // Takes only one type parameter, but causes a panic (see below)
-func fromStrings3[T _Setter2](s []string) []T {
+func fromStrings3[T Setter2](s []string) []T {
 	results := make([]T, len(s))
 	for i, v := range s {
 		// Panics if T is a pointer type because receiver is T(nil).
diff --git a/test/typeparam/shape1.go b/test/typeparam/shape1.go
new file mode 100644
index 0000000..de1ea65
--- /dev/null
+++ b/test/typeparam/shape1.go
@@ -0,0 +1,50 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type I interface {
+	foo() int
+}
+
+// There should be one instantiation of f for both squarer and doubler.
+// Similarly, there should be one instantiation of f for both *incrementer and *decrementer.
+func f[T I](x T) int {
+	return x.foo()
+}
+
+type squarer int
+
+func (x squarer) foo() int {
+	return int(x*x)
+}
+
+type doubler int
+
+func (x doubler) foo() int {
+	return int(2*x)
+}
+
+type incrementer int16
+
+func (x *incrementer) foo() int {
+	return int(*x+1)
+}
+
+type decrementer int32
+
+func (x *decrementer) foo() int{
+	return int(*x-1)
+}
+
+func main() {
+	println(f(squarer(5)))
+	println(f(doubler(5)))
+	var i incrementer = 5
+	println(f(&i))
+	var d decrementer = 5
+	println(f(&d))
+}
diff --git a/test/typeparam/shape1.out b/test/typeparam/shape1.out
new file mode 100644
index 0000000..da9a12d
--- /dev/null
+++ b/test/typeparam/shape1.out
@@ -0,0 +1,4 @@
+25
+10
+6
+4
diff --git a/test/typeparam/sliceimp.dir/a.go b/test/typeparam/sliceimp.dir/a.go
new file mode 100644
index 0000000..da12e9f
--- /dev/null
+++ b/test/typeparam/sliceimp.dir/a.go
@@ -0,0 +1,141 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Ordered interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
+}
+
+// Max returns the maximum of two values of some ordered type.
+func Max[T Ordered](a, b T) T {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+// Min returns the minimum of two values of some ordered type.
+func Min[T Ordered](a, b T) T {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+// Equal reports whether two slices are equal: the same length and all
+// elements equal. All floating point NaNs are considered equal.
+func Equal[Elem comparable](s1, s2 []Elem) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if v1 != v2 {
+			isNaN := func(f Elem) bool { return f != f }
+			if !isNaN(v1) || !isNaN(v2) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// EqualFn reports whether two slices are equal using a comparision
+// function on each element.
+func EqualFn[Elem any](s1, s2 []Elem, eq func(Elem, Elem) bool) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i, v1 := range s1 {
+		v2 := s2[i]
+		if !eq(v1, v2) {
+			return false
+		}
+	}
+	return true
+}
+
+// Map turns a []Elem1 to a []Elem2 using a mapping function.
+func Map[Elem1, Elem2 any](s []Elem1, f func(Elem1) Elem2) []Elem2 {
+	r := make([]Elem2, len(s))
+	for i, v := range s {
+		r[i] = f(v)
+	}
+	return r
+}
+
+// Reduce reduces a []Elem1 to a single value of type Elem2 using
+// a reduction function.
+func Reduce[Elem1, Elem2 any](s []Elem1, initializer Elem2, f func(Elem2, Elem1) Elem2) Elem2 {
+	r := initializer
+	for _, v := range s {
+		r = f(r, v)
+	}
+	return r
+}
+
+// Filter filters values from a slice using a filter function.
+func Filter[Elem any](s []Elem, f func(Elem) bool) []Elem {
+	var r []Elem
+	for _, v := range s {
+		if f(v) {
+			r = append(r, v)
+		}
+	}
+	return r
+}
+
+// Max returns the maximum element in a slice of some ordered type.
+// If the slice is empty it returns the zero value of the element type.
+func SliceMax[Elem Ordered](s []Elem) Elem {
+	if len(s) == 0 {
+		var zero Elem
+		return zero
+	}
+	return Reduce(s[1:], s[0], Max[Elem])
+}
+
+// Min returns the minimum element in a slice of some ordered type.
+// If the slice is empty it returns the zero value of the element type.
+func SliceMin[Elem Ordered](s []Elem) Elem {
+	if len(s) == 0 {
+		var zero Elem
+		return zero
+	}
+	return Reduce(s[1:], s[0], Min[Elem])
+}
+
+// Append adds values to the end of a slice, returning a new slice.
+// This is like the predeclared append function; it's an example
+// of how to write it using generics. We used to write code like
+// this before append was added to the language, but we had to write
+// a separate copy for each type.
+func Append[T any](s []T, t ...T) []T {
+	lens := len(s)
+	tot := lens + len(t)
+	if tot <= cap(s) {
+		s = s[:tot]
+	} else {
+		news := make([]T, tot, tot+tot/2)
+		Copy(news, s)
+		s = news
+	}
+	Copy(s[lens:tot], t)
+	return s
+}
+
+// Copy copies values from t to s, stopping when either slice is full,
+// returning the number of values copied. This is like the predeclared
+// copy function; it's an example of how to write it using generics.
+func Copy[T any](s, t []T) int {
+	i := 0
+	for ; i < len(s) && i < len(t); i++ {
+		s[i] = t[i]
+	}
+	return i
+}
diff --git a/test/typeparam/sliceimp.dir/main.go b/test/typeparam/sliceimp.dir/main.go
new file mode 100644
index 0000000..0f79e10
--- /dev/null
+++ b/test/typeparam/sliceimp.dir/main.go
@@ -0,0 +1,179 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"math"
+	"strings"
+)
+
+type Integer interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
+}
+
+func TestEqual() {
+	s1 := []int{1, 2, 3}
+	if !a.Equal(s1, s1) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s1))
+	}
+	s2 := []int{1, 2, 3}
+	if !a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s2 = append(s2, 4)
+	if a.Equal(s1, s2) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = true, want false", s1, s2))
+	}
+
+	s3 := []float64{1, 2, math.NaN()}
+	if !a.Equal(s3, s3) {
+		panic(fmt.Sprintf("a.Equal(%v, %v) = false, want true", s3, s3))
+	}
+
+	if a.Equal(s1, nil) {
+		panic(fmt.Sprintf("a.Equal(%v, nil) = true, want false", s1))
+	}
+	if a.Equal(nil, s1) {
+		panic(fmt.Sprintf("a.Equal(nil, %v) = true, want false", s1))
+	}
+	if !a.Equal(s1[:0], nil) {
+		panic(fmt.Sprintf("a.Equal(%v, nil = false, want true", s1[:0]))
+	}
+}
+
+func offByOne[Elem Integer](a, b Elem) bool {
+	return a == b+1 || a == b-1
+}
+
+func TestEqualFn() {
+	s1 := []int{1, 2, 3}
+	s2 := []int{2, 3, 4}
+	if a.EqualFn(s1, s1, offByOne[int]) {
+		panic(fmt.Sprintf("a.EqualFn(%v, %v, offByOne) = true, want false", s1, s1))
+	}
+	if !a.EqualFn(s1, s2, offByOne[int]) {
+		panic(fmt.Sprintf("a.EqualFn(%v, %v, offByOne) = false, want true", s1, s2))
+	}
+
+	if !a.EqualFn(s1[:0], nil, offByOne[int]) {
+		panic(fmt.Sprintf("a.EqualFn(%v, nil, offByOne) = false, want true", s1[:0]))
+	}
+
+	s3 := []string{"a", "b", "c"}
+	s4 := []string{"A", "B", "C"}
+	if !a.EqualFn(s3, s4, strings.EqualFold) {
+		panic(fmt.Sprintf("a.EqualFn(%v, %v, strings.EqualFold) = false, want true", s3, s4))
+	}
+}
+
+func TestMap() {
+	s1 := []int{1, 2, 3}
+	s2 := a.Map(s1, func(i int) float64 { return float64(i) * 2.5 })
+	if want := []float64{2.5, 5, 7.5}; !a.Equal(s2, want) {
+		panic(fmt.Sprintf("a.Map(%v, ...) = %v, want %v", s1, s2, want))
+	}
+
+	s3 := []string{"Hello", "World"}
+	s4 := a.Map(s3, strings.ToLower)
+	if want := []string{"hello", "world"}; !a.Equal(s4, want) {
+		panic(fmt.Sprintf("a.Map(%v, strings.ToLower) = %v, want %v", s3, s4, want))
+	}
+
+	s5 := a.Map(nil, func(i int) int { return i })
+	if len(s5) != 0 {
+		panic(fmt.Sprintf("a.Map(nil, identity) = %v, want empty slice", s5))
+	}
+}
+
+func TestReduce() {
+	s1 := []int{1, 2, 3}
+	r := a.Reduce(s1, 0, func(f float64, i int) float64 { return float64(i)*2.5 + f })
+	if want := 15.0; r != want {
+		panic(fmt.Sprintf("a.Reduce(%v, 0, ...) = %v, want %v", s1, r, want))
+	}
+
+	if got := a.Reduce(nil, 0, func(i, j int) int { return i + j }); got != 0 {
+		panic(fmt.Sprintf("a.Reduce(nil, 0, add) = %v, want 0", got))
+	}
+}
+
+func TestFilter() {
+	s1 := []int{1, 2, 3}
+	s2 := a.Filter(s1, func(i int) bool { return i%2 == 0 })
+	if want := []int{2}; !a.Equal(s2, want) {
+		panic(fmt.Sprintf("a.Filter(%v, even) = %v, want %v", s1, s2, want))
+	}
+
+	if s3 := a.Filter(s1[:0], func(i int) bool { return true }); len(s3) > 0 {
+		panic(fmt.Sprintf("a.Filter(%v, identity) = %v, want empty slice", s1[:0], s3))
+	}
+}
+
+func TestMax() {
+	s1 := []int{1, 2, 3, -5}
+	if got, want := a.SliceMax(s1), 3; got != want {
+		panic(fmt.Sprintf("a.Max(%v) = %d, want %d", s1, got, want))
+	}
+
+	s2 := []string{"aaa", "a", "aa", "aaaa"}
+	if got, want := a.SliceMax(s2), "aaaa"; got != want {
+		panic(fmt.Sprintf("a.Max(%v) = %q, want %q", s2, got, want))
+	}
+
+	if got, want := a.SliceMax(s2[:0]), ""; got != want {
+		panic(fmt.Sprintf("a.Max(%v) = %q, want %q", s2[:0], got, want))
+	}
+}
+
+func TestMin() {
+	s1 := []int{1, 2, 3, -5}
+	if got, want := a.SliceMin(s1), -5; got != want {
+		panic(fmt.Sprintf("a.Min(%v) = %d, want %d", s1, got, want))
+	}
+
+	s2 := []string{"aaa", "a", "aa", "aaaa"}
+	if got, want := a.SliceMin(s2), "a"; got != want {
+		panic(fmt.Sprintf("a.Min(%v) = %q, want %q", s2, got, want))
+	}
+
+	if got, want := a.SliceMin(s2[:0]), ""; got != want {
+		panic(fmt.Sprintf("a.Min(%v) = %q, want %q", s2[:0], got, want))
+	}
+}
+
+func TestAppend() {
+	s := []int{1, 2, 3}
+	s = a.Append(s, 4, 5, 6)
+	want := []int{1, 2, 3, 4, 5, 6}
+	if !a.Equal(s, want) {
+		panic(fmt.Sprintf("after a.Append got %v, want %v", s, want))
+	}
+}
+
+func TestCopy() {
+	s1 := []int{1, 2, 3}
+	s2 := []int{4, 5}
+	if got := a.Copy(s1, s2); got != 2 {
+		panic(fmt.Sprintf("a.Copy returned %d, want 2", got))
+	}
+	want := []int{4, 5, 3}
+	if !a.Equal(s1, want) {
+		panic(fmt.Sprintf("after a.Copy got %v, want %v", s1, want))
+	}
+}
+func main() {
+	TestEqual()
+	TestEqualFn()
+	TestMap()
+	TestReduce()
+	TestFilter()
+	TestMax()
+	TestMin()
+	TestAppend()
+	TestCopy()
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/sliceimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/sliceimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/sliceimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/slices.go b/test/typeparam/slices.go
index 149199e..b5e8e0c 100644
--- a/test/typeparam/slices.go
+++ b/test/typeparam/slices.go
@@ -15,31 +15,31 @@
 )
 
 type Ordered interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr,
-                float32, float64,
-                string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
 type Integer interface {
-        type int, int8, int16, int32, int64,
-                uint, uint8, uint16, uint32, uint64, uintptr
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
 }
 
 // Max returns the maximum of two values of some ordered type.
 func _Max[T Ordered](a, b T) T {
-        if a > b {
-                return a
-        }
-        return b
+	if a > b {
+		return a
+	}
+	return b
 }
 
 // Min returns the minimum of two values of some ordered type.
 func _Min[T Ordered](a, b T) T {
-        if a < b {
-                return a
-        }
-        return b
+	if a < b {
+		return a
+	}
+	return b
 }
 
 // _Equal reports whether two slices are equal: the same length and all
@@ -136,7 +136,7 @@
 	if tot <= cap(s) {
 		s = s[:tot]
 	} else {
-		news := make([]T, tot, tot + tot/2)
+		news := make([]T, tot, tot+tot/2)
 		_Copy(news, s)
 		s = news
 	}
@@ -156,37 +156,37 @@
 }
 
 func TestEqual() {
-        s1 := []int{1, 2, 3}
-        if !_Equal(s1, s1) {
-                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s1))
-        }
-        s2 := []int{1, 2, 3}
-        if !_Equal(s1, s2) {
-                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s2))
-        }
-        s2 = append(s2, 4)
-        if _Equal(s1, s2) {
-                panic(fmt.Sprintf("_Equal(%v, %v) = true, want false", s1, s2))
-        }
+	s1 := []int{1, 2, 3}
+	if !_Equal(s1, s1) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s1))
+	}
+	s2 := []int{1, 2, 3}
+	if !_Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s1, s2))
+	}
+	s2 = append(s2, 4)
+	if _Equal(s1, s2) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = true, want false", s1, s2))
+	}
 
-        s3 := []float64{1, 2, math.NaN()}
-        if !_Equal(s3, s3) {
-                panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s3, s3))
-        }
+	s3 := []float64{1, 2, math.NaN()}
+	if !_Equal(s3, s3) {
+		panic(fmt.Sprintf("_Equal(%v, %v) = false, want true", s3, s3))
+	}
 
-        if _Equal(s1, nil) {
-                panic(fmt.Sprintf("_Equal(%v, nil) = true, want false", s1))
-        }
-        if _Equal(nil, s1) {
-                panic(fmt.Sprintf("_Equal(nil, %v) = true, want false", s1))
-        }
-        if !_Equal(s1[:0], nil) {
-                panic(fmt.Sprintf("_Equal(%v, nil = false, want true", s1[:0]))
-        }
+	if _Equal(s1, nil) {
+		panic(fmt.Sprintf("_Equal(%v, nil) = true, want false", s1))
+	}
+	if _Equal(nil, s1) {
+		panic(fmt.Sprintf("_Equal(nil, %v) = true, want false", s1))
+	}
+	if !_Equal(s1[:0], nil) {
+		panic(fmt.Sprintf("_Equal(%v, nil = false, want true", s1[:0]))
+	}
 }
 
 func offByOne[Elem Integer](a, b Elem) bool {
-	return a == b + 1 || a == b - 1
+	return a == b+1 || a == b-1
 }
 
 func TestEqualFn() {
@@ -231,12 +231,12 @@
 
 func TestReduce() {
 	s1 := []int{1, 2, 3}
-	r := _Reduce(s1, 0, func(f float64, i int) float64 { return float64(i) * 2.5 + f })
+	r := _Reduce(s1, 0, func(f float64, i int) float64 { return float64(i)*2.5 + f })
 	if want := 15.0; r != want {
 		panic(fmt.Sprintf("_Reduce(%v, 0, ...) = %v, want %v", s1, r, want))
 	}
 
-	if got := _Reduce(nil, 0, func(i, j int) int { return i + j}); got != 0 {
+	if got := _Reduce(nil, 0, func(i, j int) int { return i + j }); got != 0 {
 		panic(fmt.Sprintf("_Reduce(nil, 0, add) = %v, want 0", got))
 	}
 }
diff --git a/test/typeparam/smallest.go b/test/typeparam/smallest.go
index 63dd9dd..af1d72d 100644
--- a/test/typeparam/smallest.go
+++ b/test/typeparam/smallest.go
@@ -11,13 +11,13 @@
 )
 
 type Ordered interface {
-	type int, int8, int16, int32, int64,
-		uint, uint8, uint16, uint32, uint64, uintptr,
-		float32, float64,
-		string
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
+		~float32 | ~float64 |
+		~string
 }
 
-func smallest[T Ordered](s []T) T {
+func Smallest[T Ordered](s []T) T {
 	r := s[0] // panics if slice is empty
 	for _, v := range s[1:] {
 		if v < r {
@@ -32,11 +32,11 @@
 	vec2 := []string{"abc", "def", "aaa"}
 
 	want1 := 1.2
-	if got := smallest(vec1); got != want1 {
+	if got := Smallest(vec1); got != want1 {
 		panic(fmt.Sprintf("got %d, want %d", got, want1))
 	}
 	want2 := "aaa"
-	if got := smallest(vec2); got != want2 {
+	if got := Smallest(vec2); got != want2 {
 		panic(fmt.Sprintf("got %d, want %d", got, want2))
 	}
 }
diff --git a/test/typeparam/smoketest.go b/test/typeparam/smoketest.go
index b7d6201..5243dc5 100644
--- a/test/typeparam/smoketest.go
+++ b/test/typeparam/smoketest.go
@@ -9,9 +9,9 @@
 package smoketest
 
 // type parameters for functions
-func f1[P any]()
-func f2[P1, P2 any, P3 any]()
-func f3[P interface{}](x P, y T1[int])
+func f1[P any]() {}
+func f2[P1, P2 any, P3 any]() {}
+func f3[P interface{}](x P, y T1[int]) {}
 
 // function instantiations
 var _ = f1[int]
@@ -29,15 +29,15 @@
 type _ T3[bool]
 
 // methods
-func (T1[P]) m1() {}
-func (T1[_]) m2() {}
+func (T1[P]) m1()           {}
+func (T1[_]) m2()           {}
 func (x T2[P1, P2, P3]) m() {}
 
 // type lists
 type _ interface {
 	m1()
 	m2()
-	type int, float32, string
+	int | float32 | string
 	m3()
 }
 
diff --git a/test/typeparam/stringable.go b/test/typeparam/stringable.go
index 9340a3b1..855a1ed 100644
--- a/test/typeparam/stringable.go
+++ b/test/typeparam/stringable.go
@@ -16,11 +16,11 @@
 	String() string
 }
 
-// stringableList is a slice of some type, where the type
+// StringableList is a slice of some type, where the type
 // must have a String method.
-type stringableList[T Stringer] []T
+type StringableList[T Stringer] []T
 
-func (s stringableList[T]) String() string {
+func (s StringableList[T]) String() string {
 	var sb strings.Builder
 	for i, v := range s {
 		if i > 0 {
@@ -38,9 +38,9 @@
 }
 
 func main() {
-	v := stringableList[myint]{ myint(1), myint(2) }
+	v := StringableList[myint]{myint(1), myint(2)}
 
 	if got, want := v.String(), "1, 2"; got != want {
-                panic(fmt.Sprintf("got %s, want %s", got, want))
+		panic(fmt.Sprintf("got %s, want %s", got, want))
 	}
 }
diff --git a/test/typeparam/stringerimp.dir/a.go b/test/typeparam/stringerimp.dir/a.go
new file mode 100644
index 0000000..3f70937
--- /dev/null
+++ b/test/typeparam/stringerimp.dir/a.go
@@ -0,0 +1,16 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Stringer interface {
+	String() string
+}
+
+func Stringify[T Stringer](s []T) (ret []string) {
+	for _, v := range s {
+		ret = append(ret, v.String())
+	}
+	return ret
+}
diff --git a/test/typeparam/stringerimp.dir/main.go b/test/typeparam/stringerimp.dir/main.go
new file mode 100644
index 0000000..e30bdf1
--- /dev/null
+++ b/test/typeparam/stringerimp.dir/main.go
@@ -0,0 +1,38 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+	"reflect"
+	"strconv"
+)
+
+type myint int
+
+func (i myint) String() string {
+	return strconv.Itoa(int(i))
+}
+
+func main() {
+	x := []myint{myint(1), myint(2), myint(3)}
+
+	got := a.Stringify(x)
+	want := []string{"1", "2", "3"}
+	if !reflect.DeepEqual(got, want) {
+		panic(fmt.Sprintf("got %s, want %s", got, want))
+	}
+
+	m1 := myint(1)
+	m2 := myint(2)
+	m3 := myint(3)
+	y := []*myint{&m1, &m2, &m3}
+	got2 := a.Stringify(y)
+	want2 := []string{"1", "2", "3"}
+	if !reflect.DeepEqual(got2, want2) {
+		panic(fmt.Sprintf("got %s, want %s", got2, want2))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/stringerimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/stringerimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/stringerimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/struct.go b/test/typeparam/struct.go
index 98f0fcd..ad1b41d 100644
--- a/test/typeparam/struct.go
+++ b/test/typeparam/struct.go
@@ -10,40 +10,40 @@
 	"fmt"
 )
 
-type _E[T any] struct {
+type E[T any] struct {
 	v T
 }
 
-type _S1 struct {
-	_E[int]
+type S1 struct {
+	E[int]
 	v string
 }
 
-type _Eint = _E[int]
-type _Ebool = _E[bool]
+type Eint = E[int]
+type Ebool = E[bool]
 
-type _S2 struct {
-	_Eint
-	_Ebool
+type S2 struct {
+	Eint
+	Ebool
 	v string
 }
 
-type _S3 struct {
-	*_E[int]
+type S3 struct {
+	*E[int]
 }
 
 func main() {
-	s1 := _S1{_Eint{2}, "foo"}
-	if got, want := s1._E.v, 2; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+	s1 := S1{Eint{2}, "foo"}
+	if got, want := s1.E.v, 2; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
-	s2 := _S2{_Eint{3}, _Ebool{true}, "foo"}
-	if got, want := s2._Eint.v, 3; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+	s2 := S2{Eint{3}, Ebool{true}, "foo"}
+	if got, want := s2.Eint.v, 3; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
-	var s3 _S3
-	s3._E = &_Eint{4}
-	if got, want := s3._E.v, 4; got != want {
-                panic(fmt.Sprintf("got %d, want %d", got, want))
+	var s3 S3
+	s3.E = &Eint{4}
+	if got, want := s3.E.v, 4; got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 }
diff --git a/test/typeparam/subdict.go b/test/typeparam/subdict.go
new file mode 100644
index 0000000..b4e84ba
--- /dev/null
+++ b/test/typeparam/subdict.go
@@ -0,0 +1,41 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test cases where a main dictionary is needed inside a generic function/method, because
+// we are calling a method on a fully-instantiated type or a fully-instantiated function.
+// (probably not common situations, of course)
+
+package main
+
+import (
+	"fmt"
+)
+
+type value[T comparable] struct {
+	val T
+}
+
+func (v *value[T]) test(def T) bool {
+	return (v.val == def)
+}
+
+func (v *value[T]) get(def T) T {
+	var c value[int]
+	if c.test(32) {
+		return def
+	} else if v.test(def) {
+		return def
+	} else {
+		return v.val
+	}
+}
+
+func main() {
+	var s value[string]
+	if got, want := s.get("ab"), ""; got != want {
+		panic(fmt.Sprintf("get() == %d, want %d", got, want))
+	}
+}
diff --git a/test/typeparam/sum.go b/test/typeparam/sum.go
index f0f5e6a..d444e00 100644
--- a/test/typeparam/sum.go
+++ b/test/typeparam/sum.go
@@ -10,7 +10,7 @@
 	"fmt"
 )
 
-func sum[T interface{ type int, float64 }](vec []T) T {
+func Sum[T interface{ int | float64 }](vec []T) T {
 	var sum T
 	for _, elt := range vec {
 		sum = sum + elt
@@ -18,7 +18,7 @@
 	return sum
 }
 
-func abs(f float64) float64 {
+func Abs(f float64) float64 {
 	if f < 0.0 {
 		return -f
 	}
@@ -28,23 +28,23 @@
 func main() {
 	vec1 := []int{3, 4}
 	vec2 := []float64{5.8, 9.6}
-	got := sum[int](vec1)
+	got := Sum[int](vec1)
 	want := vec1[0] + vec1[1]
 	if got != want {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
-	got = sum(vec1)
+	got = Sum(vec1)
 	if want != got {
 		panic(fmt.Sprintf("got %d, want %d", got, want))
 	}
 
 	fwant := vec2[0] + vec2[1]
-	fgot := sum[float64](vec2)
-	if abs(fgot - fwant) > 1e-10 {
+	fgot := Sum[float64](vec2)
+	if Abs(fgot-fwant) > 1e-10 {
 		panic(fmt.Sprintf("got %f, want %f", fgot, fwant))
 	}
-	fgot = sum(vec2)
-	if abs(fgot - fwant) > 1e-10 {
+	fgot = Sum(vec2)
+	if Abs(fgot-fwant) > 1e-10 {
 		panic(fmt.Sprintf("got %f, want %f", fgot, fwant))
 	}
 }
diff --git a/test/typeparam/tparam1.go b/test/typeparam/tparam1.go
index 7043933..698877a 100644
--- a/test/typeparam/tparam1.go
+++ b/test/typeparam/tparam1.go
@@ -10,33 +10,33 @@
 
 // The predeclared identifier "any" is only visible as a constraint
 // in a type parameter list.
-var _ any // ERROR "undefined"
-func _(_ any) // ERROR "undefined"
-type _[_ any /* ok here */ ] struct{}
+var _ any     // ERROR "cannot use any outside constraint position"
+func _(_ any) // ERROR "cannot use any outside constraint position"
+type _[_ any /* ok here */] struct{}
 
 const N = 10
 
 type (
-        _[] struct{} // slice
-        _[N] struct{} // array
-        _[T any] struct{}
-        _[T, T any] struct{} // ERROR "T redeclared"
-        _[T1, T2 any, T3 any] struct{}
+	_                     []struct{}  // slice
+	_                     [N]struct{} // array
+	_[T any]              struct{}
+	_[T, T any]           struct{} // ERROR "T redeclared"
+	_[T1, T2 any, T3 any] struct{}
 )
 
-func _[T any]()
-func _[T, T any]() // ERROR "T redeclared"
-func _[T1, T2 any](x T1) T2
+func _[T any]() {}
+func _[T, T any]() {} // ERROR "T redeclared"
+func _[T1, T2 any](x T1) T2 { panic(0) }
 
 // Type parameters are visible from opening [ to end of function.
 type C interface{}
 
-func _[T interface{}]()
-func _[T C]()
-func _[T struct{}]() // ERROR "not an interface"
-func _[T interface{ m() T }]()
+func _[T interface{}]() {}
+func _[T C]() {}
+func _[T struct{}]() {}// ERROR "not an interface"
+func _[T interface{ m() T }]() {}
 func _[T1 interface{ m() T2 }, T2 interface{ m() T1 }]() {
-        var _ T1
+	var _ T1
 }
 
 // TODO(gri) expand this
diff --git a/test/typeparam/typelist.go b/test/typeparam/typelist.go
index bd90d86..5ba1426 100644
--- a/test/typeparam/typelist.go
+++ b/test/typeparam/typelist.go
@@ -10,19 +10,19 @@
 
 // Assignability of an unnamed pointer type to a type parameter that
 // has a matching underlying type.
-func _[T interface{}, PT interface{type *T}] (x T) PT {
-    return &x
+func _[T interface{}, PT interface{ type *T }](x T) PT {
+	return &x
 }
 
 // Indexing of generic types containing type parameters in their type list:
 func at[T interface{ type []E }, E any](x T, i int) E {
-        return x[i]
+	return x[i]
 }
 
 // A generic type inside a function acts like a named type. Its underlying
 // type is itself, its "operational type" is defined by the type list in
 // the tybe bound, if any.
-func _[T interface{type int}](x T) {
+func _[T interface{ type int }](x T) {
 	type myint int
 	var _ int = int(x)
 	var _ T = 42
@@ -30,7 +30,7 @@
 }
 
 // Indexing a generic type which has a structural contraints to be an array.
-func _[T interface { type [10]int }](x T) {
+func _[T interface{ type [10]int }](x T) {
 	_ = x[9] // ok
 }
 
@@ -44,7 +44,7 @@
 func _[T interface{ type chan int }](ch T) int {
 	// This would deadlock if executed (but ok for a compile test)
 	ch <- 0
-	return <- ch
+	return <-ch
 }
 
 // Calling of a generic type which has a structural constraint to be a function.
@@ -59,32 +59,34 @@
 }
 
 // Map access of a generic type which has a structural constraint to be a map.
-func _[V any, T interface { type map[string]V }](p T) V {
+func _[V any, T interface{ type map[string]V }](p T) V {
 	return p["test"]
 }
 
-
 // Testing partial and full type inference, including the case where the types can
 // be inferred without needing the types of the function arguments.
 
+// Cannot embed stand-alone type parameters. Disabled for now.
+/*
 func f0[A any, B interface{type C}, C interface{type D}, D interface{type A}](A, B, C, D)
-func _() {
+func f0x() {
         f := f0[string]
         f("a", "b", "c", "d")
         f0("a", "b", "c", "d")
 }
 
 func f1[A any, B interface{type A}](A, B)
-func _() {
+func f1x() {
         f := f1[int]
         f(int(0), int(0))
         f1(int(0), int(0))
         f(0, 0)
         f1(0, 0)
 }
+*/
 
-func f2[A any, B interface{type []A}](_ A, _ B)
-func _() {
+func f2[A any, B interface{ type []A }](_ A, _ B) {}
+func f2x() {
 	f := f2[byte]
 	f(byte(0), []byte{})
 	f2(byte(0), []byte{})
@@ -92,31 +94,39 @@
 	// f2(0, []byte{}) - this one doesn't work
 }
 
+// Cannot embed stand-alone type parameters. Disabled for now.
+/*
 func f3[A any, B interface{type C}, C interface{type *A}](a A, _ B, c C)
-func _() {
+func f3x() {
 	f := f3[int]
 	var x int
 	f(x, &x, &x)
 	f3(x, &x, &x)
 }
+*/
 
-func f4[A any, B interface{type []C}, C interface{type *A}](_ A, _ B, c C)
-func _() {
+func f4[A any, B interface{ type []C }, C interface{ type *A }](_ A, _ B, c C) {}
+func f4x() {
 	f := f4[int]
 	var x int
 	f(x, []*int{}, &x)
 	f4(x, []*int{}, &x)
 }
 
-func f5[A interface{type struct{b B; c C}}, B any, C interface{type *B}](x B) A
-func _() {
+func f5[A interface {
+	type struct {
+		b B
+		c C
+	}
+}, B any, C interface{ type *B }](x B) A { panic(0) }
+func f5x() {
 	x := f5(1.2)
 	var _ float64 = x.b
 	var _ float64 = *x.c
 }
 
-func f6[A any, B interface{type struct{f []A}}](B) A
-func _() {
-	x := f6(struct{f []string}{})
+func f6[A any, B interface{ type struct{ f []A } }](B) A { panic(0) }
+func f6x() {
+	x := f6(struct{ f []string }{})
 	var _ string = x
 }
diff --git a/test/typeparam/typeswitch1.go b/test/typeparam/typeswitch1.go
new file mode 100644
index 0000000..27161b3
--- /dev/null
+++ b/test/typeparam/typeswitch1.go
@@ -0,0 +1,29 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[T any](i interface{}) {
+	switch i.(type) {
+	case T:
+		println("T")
+	case int:
+		println("int")
+	case int32, int16:
+		println("int32/int16")
+	case struct { a, b T }:
+		println("struct{T,T}")
+	default:
+		println("other")
+	}
+}
+func main() {
+	f[float64](float64(6))
+	f[float64](int(7))
+	f[float64](int32(8))
+	f[float64](struct{a, b float64}{a:1, b:2})
+	f[float64](int8(9))
+}
diff --git a/test/typeparam/typeswitch1.out b/test/typeparam/typeswitch1.out
new file mode 100644
index 0000000..4bdbccf
--- /dev/null
+++ b/test/typeparam/typeswitch1.out
@@ -0,0 +1,5 @@
+T
+int
+int32/int16
+struct{T,T}
+other
diff --git a/test/typeparam/typeswitch2.go b/test/typeparam/typeswitch2.go
new file mode 100644
index 0000000..913c563
--- /dev/null
+++ b/test/typeparam/typeswitch2.go
@@ -0,0 +1,31 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "reflect"
+
+func f[T any](i interface{}) {
+	switch x := i.(type) {
+	case T:
+		println("T", x)
+	case int:
+		println("int", x)
+	case int32, int16:
+		println("int32/int16", reflect.ValueOf(x).Int())
+	case struct { a, b T }:
+		println("struct{T,T}", x.a, x.b)
+	default:
+		println("other", reflect.ValueOf(x).Int())
+	}
+}
+func main() {
+	f[float64](float64(6))
+	f[float64](int(7))
+	f[float64](int32(8))
+	f[float64](struct{a, b float64}{a:1, b:2})
+	f[float64](int8(9))
+}
diff --git a/test/typeparam/typeswitch2.out b/test/typeparam/typeswitch2.out
new file mode 100644
index 0000000..944cc04
--- /dev/null
+++ b/test/typeparam/typeswitch2.out
@@ -0,0 +1,5 @@
+T +6.000000e+000
+int 7
+int32/int16 8
+struct{T,T} +1.000000e+000 +2.000000e+000
+other 9
diff --git a/test/typeparam/typeswitch3.go b/test/typeparam/typeswitch3.go
new file mode 100644
index 0000000..6ab0301
--- /dev/null
+++ b/test/typeparam/typeswitch3.go
@@ -0,0 +1,35 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type I interface { foo() int }
+
+type myint int
+
+func (x myint) foo() int { return int(x) }
+
+type myfloat float64
+func (x myfloat) foo() int { return int(x) }
+
+type myint32 int32
+func (x myint32) foo() int { return int(x) }
+
+func f[T I](i I) {
+	switch x := i.(type) {
+	case T:
+		println("T", x.foo())
+	case myint:
+		println("myint", x.foo())
+	default:
+		println("other", x.foo())
+	}
+}
+func main() {
+	f[myfloat](myint(6))
+	f[myfloat](myfloat(7))
+	f[myfloat](myint32(8))
+}
diff --git a/test/typeparam/typeswitch3.out b/test/typeparam/typeswitch3.out
new file mode 100644
index 0000000..2c69c72
--- /dev/null
+++ b/test/typeparam/typeswitch3.out
@@ -0,0 +1,3 @@
+myint 6
+T 7
+other 8
diff --git a/test/typeparam/typeswitch4.go b/test/typeparam/typeswitch4.go
new file mode 100644
index 0000000..6113026
--- /dev/null
+++ b/test/typeparam/typeswitch4.go
@@ -0,0 +1,33 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type I interface { foo() int }
+
+type myint int
+
+func (x myint) foo() int {return int(x)}
+
+type myfloat float64
+func (x myfloat) foo() int {return int(x)}
+
+type myint32 int32
+func (x myint32) foo() int { return int(x) }
+
+func f[T I](i I) {
+	switch x := i.(type) {
+	case T, myint32:
+		println("T/myint32", x.foo())
+	default:
+		println("other", x.foo())
+	}
+}
+func main() {
+	f[myfloat](myint(6))
+	f[myfloat](myfloat(7))
+	f[myfloat](myint32(8))
+}
diff --git a/test/typeparam/typeswitch4.out b/test/typeparam/typeswitch4.out
new file mode 100644
index 0000000..b0d5407
--- /dev/null
+++ b/test/typeparam/typeswitch4.out
@@ -0,0 +1,3 @@
+other 6
+T/myint32 7
+T/myint32 8
diff --git a/test/typeparam/typeswitch5.go b/test/typeparam/typeswitch5.go
new file mode 100644
index 0000000..1fc6e0a
--- /dev/null
+++ b/test/typeparam/typeswitch5.go
@@ -0,0 +1,28 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type myint int
+func (x myint) foo() int {return int(x)}
+
+type myfloat float64
+func (x myfloat) foo() float64 {return float64(x) }
+
+func f[T any](i interface{}) {
+	switch x := i.(type) {
+	case interface { foo() T }:
+		println("fooer", x.foo())
+	default:
+		println("other")
+	}
+}
+func main() {
+	f[int](myint(6))
+	f[int](myfloat(7))
+	f[float64](myint(8))
+	f[float64](myfloat(9))
+}
diff --git a/test/typeparam/typeswitch5.out b/test/typeparam/typeswitch5.out
new file mode 100644
index 0000000..6b4cb44
--- /dev/null
+++ b/test/typeparam/typeswitch5.out
@@ -0,0 +1,4 @@
+fooer 6
+other
+other
+fooer +9.000000e+000
diff --git a/test/typeparam/typeswitch6.go b/test/typeparam/typeswitch6.go
new file mode 100644
index 0000000..574f4aa
--- /dev/null
+++ b/test/typeparam/typeswitch6.go
@@ -0,0 +1,30 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[T any](i interface{}) {
+	switch i.(type) {
+	case T:
+		println("T")
+	case int:
+		println("int")
+	default:
+		println("other")
+	}
+}
+
+type myint int
+func (myint) foo() {
+}
+
+func main() {
+	f[interface{}](nil)
+	f[interface{}](6)
+	f[interface{foo()}](nil)
+	f[interface{foo()}](7)
+	f[interface{foo()}](myint(8))
+}
diff --git a/test/typeparam/typeswitch6.out b/test/typeparam/typeswitch6.out
new file mode 100644
index 0000000..441add5
--- /dev/null
+++ b/test/typeparam/typeswitch6.out
@@ -0,0 +1,5 @@
+other
+T
+other
+int
+T
diff --git a/test/typeparam/typeswitch7.go b/test/typeparam/typeswitch7.go
new file mode 100644
index 0000000..f2e1279
--- /dev/null
+++ b/test/typeparam/typeswitch7.go
@@ -0,0 +1,37 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f[T any](i interface{foo()}) {
+	switch i.(type) {
+	case interface{bar() T}:
+		println("barT")
+	case myint:
+		println("myint")
+	case myfloat:
+		println("myfloat")
+	default:
+		println("other")
+	}
+}
+
+type myint int
+func (myint) foo() {
+}
+func (x myint) bar() int {
+	return int(x)
+}
+
+type myfloat float64
+func (myfloat) foo() {
+}
+
+func main() {
+	f[int](nil)
+	f[int](myint(6))
+	f[int](myfloat(7))
+}
diff --git a/test/typeparam/typeswitch7.out b/test/typeparam/typeswitch7.out
new file mode 100644
index 0000000..d7fcad4
--- /dev/null
+++ b/test/typeparam/typeswitch7.out
@@ -0,0 +1,3 @@
+other
+barT
+myfloat
diff --git a/test/typeparam/valimp.dir/a.go b/test/typeparam/valimp.dir/a.go
new file mode 100644
index 0000000..2ed0063
--- /dev/null
+++ b/test/typeparam/valimp.dir/a.go
@@ -0,0 +1,32 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+type Value[T any] struct {
+	val T
+}
+
+// The noinline directive should survive across import, and prevent instantiations
+// of these functions from being inlined.
+
+//go:noinline
+func Get[T any](v *Value[T]) T {
+	return v.val
+}
+
+//go:noinline
+func Set[T any](v *Value[T], val T) {
+	v.val = val
+}
+
+//go:noinline
+func (v *Value[T]) Set(val T) {
+	v.val = val
+}
+
+//go:noinline
+func (v *Value[T]) Get() T {
+	return v.val
+}
diff --git a/test/typeparam/valimp.dir/main.go b/test/typeparam/valimp.dir/main.go
new file mode 100644
index 0000000..606ff22
--- /dev/null
+++ b/test/typeparam/valimp.dir/main.go
@@ -0,0 +1,55 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"fmt"
+)
+
+func main() {
+	var v1 a.Value[int]
+
+	a.Set(&v1, 1)
+	if got, want := a.Get(&v1), 1; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+	v1.Set(2)
+	if got, want := v1.Get(), 2; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+	v1p := new(a.Value[int])
+	a.Set(v1p, 3)
+	if got, want := a.Get(v1p), 3; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+
+	v1p.Set(4)
+	if got, want := v1p.Get(), 4; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+
+	var v2 a.Value[string]
+	a.Set(&v2, "a")
+	if got, want := a.Get(&v2), "a"; got != want {
+		panic(fmt.Sprintf("Get() == %q, want %q", got, want))
+	}
+
+	v2.Set("b")
+	if got, want := a.Get(&v2), "b"; got != want {
+		panic(fmt.Sprintf("Get() == %q, want %q", got, want))
+	}
+
+	v2p := new(a.Value[string])
+	a.Set(v2p, "c")
+	if got, want := a.Get(v2p), "c"; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+
+	v2p.Set("d")
+	if got, want := v2p.Get(), "d"; got != want {
+		panic(fmt.Sprintf("Get() == %d, want %d", got, want))
+	}
+}
diff --git a/src/cmd/gofmt/gofmt_typeparams_test.go b/test/typeparam/valimp.go
similarity index 61%
copy from src/cmd/gofmt/gofmt_typeparams_test.go
copy to test/typeparam/valimp.go
index 10641a7..76930e5 100644
--- a/src/cmd/gofmt/gofmt_typeparams_test.go
+++ b/test/typeparam/valimp.go
@@ -1,12 +1,7 @@
+// rundir -G=3
+
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams
-// +build typeparams
-
-package main
-
-func init() {
-	typeParamsEnabled = true
-}
+package ignored
diff --git a/test/typeparam/value.go b/test/typeparam/value.go
index 5dd7449..6c6dabc 100644
--- a/test/typeparam/value.go
+++ b/test/typeparam/value.go
@@ -12,7 +12,7 @@
 	val T
 }
 
-func get[T2 any](v *value[T2]) T2 {
+func get[T any](v *value[T]) T {
 	return v.val
 }
 
@@ -20,11 +20,11 @@
 	v.val = val
 }
 
-func (v *value[T2]) set(val T2) {
+func (v *value[T]) set(val T) {
 	v.val = val
 }
 
-func (v *value[T2]) get() T2 {
+func (v *value[T]) get() T {
 	return v.val
 }
 
diff --git a/test/uintptrescapes2.go b/test/uintptrescapes2.go
index 3ff1d94..656286c 100644
--- a/test/uintptrescapes2.go
+++ b/test/uintptrescapes2.go
@@ -30,7 +30,7 @@
 func (T) M1(a uintptr) {} // ERROR "escaping uintptr"
 
 //go:uintptrescapes
-func (T) M2(a ...uintptr) {} // ERROR "escaping ...uintptr" "leaking param: a"
+func (T) M2(a ...uintptr) {} // ERROR "escaping ...uintptr"
 
 func TestF1() {
 	var t int                        // ERROR "moved to heap"