cmd/compile,cmd/link: introduce generic interface call relocations
To capture the fact that a method was called on a generic interface,
so we can make sure the linker doesn't throw away any implementations
that might be the method called.
See the comment in reflect.go for details.
Fixes #49049
Change-Id: I0be74b6e727c1ecefedae072b149f59d539dc1e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/357835
Trust: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
diff --git a/src/cmd/compile/internal/reflectdata/reflect.go b/src/cmd/compile/internal/reflectdata/reflect.go
index 27e6188a..369ee75 100644
--- a/src/cmd/compile/internal/reflectdata/reflect.go
+++ b/src/cmd/compile/internal/reflectdata/reflect.go
@@ -18,6 +18,7 @@
"cmd/compile/internal/inline"
"cmd/compile/internal/ir"
"cmd/compile/internal/objw"
+ "cmd/compile/internal/staticdata"
"cmd/compile/internal/typebits"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
@@ -1995,8 +1996,33 @@
dot := n.X.(*ir.SelectorExpr)
ityp := dot.X.Type()
if ityp.HasShape() {
- base.Fatalf("marking method of shape type used %+v %s", ityp, dot.Sel.Name)
+ // Here we're calling a method on a generic interface. Something like:
+ //
+ // type I[T any] interface { foo() T }
+ // func f[T any](x I[T]) {
+ // ... = x.foo()
+ // }
+ // f[int](...)
+ // f[string](...)
+ //
+ // In this case, in f we're calling foo on a generic interface.
+ // Which method could that be? Normally we could match the method
+ // both by name and by type. But in this case we don't really know
+ // the type of the method we're calling. It could be func()int
+ // or func()string. So we match on just the function name, instead
+ // of both the name and the type used for the non-generic case below.
+ // TODO: instantiations at least know the shape of the instantiated
+ // type, and the linker could do more complicated matching using
+ // some sort of fuzzy shape matching. For now, only use the name
+ // of the method for matching.
+ r := obj.Addrel(ir.CurFunc.LSym)
+ // We use a separate symbol just to tell the linker the method name.
+ // (The symbol itself is not needed in the final binary.)
+ r.Sym = staticdata.StringSym(src.NoXPos, dot.Sel.Name)
+ r.Type = objabi.R_USEGENERICIFACEMETHOD
+ return
}
+
tsym := TypeLinksym(ityp)
r := obj.Addrel(ir.CurFunc.LSym)
r.Sym = tsym
diff --git a/src/cmd/compile/internal/walk/expr.go b/src/cmd/compile/internal/walk/expr.go
index c452cec..e5bf6cf 100644
--- a/src/cmd/compile/internal/walk/expr.go
+++ b/src/cmd/compile/internal/walk/expr.go
@@ -506,17 +506,7 @@
usemethod(n)
}
if n.Op() == ir.OCALLINTER {
- if n.X.(*ir.SelectorExpr).X.Type().HasShape() {
- // There should be an entry in n.KeepAlive to keep the
- // dictionary alive (added in ../noder/transformCall).
- // The dictionary in turn marks the method as used.
- if len(n.KeepAlive) == 0 {
- // TODO(khr): this fails for issue44688.go.
- //base.Fatalf("KeepAlive of dictionary arg missing")
- }
- } else {
- reflectdata.MarkUsedIfaceMethod(n)
- }
+ reflectdata.MarkUsedIfaceMethod(n)
}
if n.Op() == ir.OCALLFUNC && n.X.Op() == ir.OCLOSURE {
diff --git a/src/cmd/internal/objabi/reloctype.go b/src/cmd/internal/objabi/reloctype.go
index 0cc60fb..a9c3030 100644
--- a/src/cmd/internal/objabi/reloctype.go
+++ b/src/cmd/internal/objabi/reloctype.go
@@ -93,6 +93,11 @@
// This is a marker relocation (0-sized), for the linker's reachabililty
// analysis.
R_USEIFACEMETHOD
+ // Similar to R_USEIFACEMETHOD, except instead of indicating a type +
+ // method offset with Sym+Add, Sym points to a symbol containing the name
+ // of the method being called. See the description in
+ // cmd/compile/internal/reflectdata/reflect.go:MarkUsedIfaceMethod for details.
+ R_USEGENERICIFACEMETHOD
// R_METHODOFF resolves to a 32-bit offset from the beginning of the section
// holding the data being relocated to the referenced symbol.
// It is a variant of R_ADDROFF used when linking from the uncommonType of a
diff --git a/src/cmd/internal/objabi/reloctype_string.go b/src/cmd/internal/objabi/reloctype_string.go
index f2e06a5..d1b15b5 100644
--- a/src/cmd/internal/objabi/reloctype_string.go
+++ b/src/cmd/internal/objabi/reloctype_string.go
@@ -32,48 +32,49 @@
_ = x[R_USETYPE-22]
_ = x[R_USEIFACE-23]
_ = x[R_USEIFACEMETHOD-24]
- _ = x[R_METHODOFF-25]
- _ = x[R_KEEP-26]
- _ = x[R_POWER_TOC-27]
- _ = x[R_GOTPCREL-28]
- _ = x[R_JMPMIPS-29]
- _ = x[R_DWARFSECREF-30]
- _ = x[R_DWARFFILEREF-31]
- _ = x[R_ARM64_TLS_LE-32]
- _ = x[R_ARM64_TLS_IE-33]
- _ = x[R_ARM64_GOTPCREL-34]
- _ = x[R_ARM64_GOT-35]
- _ = x[R_ARM64_PCREL-36]
- _ = x[R_ARM64_LDST8-37]
- _ = x[R_ARM64_LDST16-38]
- _ = x[R_ARM64_LDST32-39]
- _ = x[R_ARM64_LDST64-40]
- _ = x[R_ARM64_LDST128-41]
- _ = x[R_POWER_TLS_LE-42]
- _ = x[R_POWER_TLS_IE-43]
- _ = x[R_POWER_TLS-44]
- _ = x[R_ADDRPOWER_DS-45]
- _ = x[R_ADDRPOWER_GOT-46]
- _ = x[R_ADDRPOWER_PCREL-47]
- _ = x[R_ADDRPOWER_TOCREL-48]
- _ = x[R_ADDRPOWER_TOCREL_DS-49]
- _ = x[R_RISCV_CALL-50]
- _ = x[R_RISCV_CALL_TRAMP-51]
- _ = x[R_RISCV_PCREL_ITYPE-52]
- _ = x[R_RISCV_PCREL_STYPE-53]
- _ = x[R_RISCV_TLS_IE_ITYPE-54]
- _ = x[R_RISCV_TLS_IE_STYPE-55]
- _ = x[R_PCRELDBL-56]
- _ = x[R_ADDRMIPSU-57]
- _ = x[R_ADDRMIPSTLS-58]
- _ = x[R_ADDRCUOFF-59]
- _ = x[R_WASMIMPORT-60]
- _ = x[R_XCOFFREF-61]
+ _ = x[R_USEGENERICIFACEMETHOD-25]
+ _ = x[R_METHODOFF-26]
+ _ = x[R_KEEP-27]
+ _ = x[R_POWER_TOC-28]
+ _ = x[R_GOTPCREL-29]
+ _ = x[R_JMPMIPS-30]
+ _ = x[R_DWARFSECREF-31]
+ _ = x[R_DWARFFILEREF-32]
+ _ = x[R_ARM64_TLS_LE-33]
+ _ = x[R_ARM64_TLS_IE-34]
+ _ = x[R_ARM64_GOTPCREL-35]
+ _ = x[R_ARM64_GOT-36]
+ _ = x[R_ARM64_PCREL-37]
+ _ = x[R_ARM64_LDST8-38]
+ _ = x[R_ARM64_LDST16-39]
+ _ = x[R_ARM64_LDST32-40]
+ _ = x[R_ARM64_LDST64-41]
+ _ = x[R_ARM64_LDST128-42]
+ _ = x[R_POWER_TLS_LE-43]
+ _ = x[R_POWER_TLS_IE-44]
+ _ = x[R_POWER_TLS-45]
+ _ = x[R_ADDRPOWER_DS-46]
+ _ = x[R_ADDRPOWER_GOT-47]
+ _ = x[R_ADDRPOWER_PCREL-48]
+ _ = x[R_ADDRPOWER_TOCREL-49]
+ _ = x[R_ADDRPOWER_TOCREL_DS-50]
+ _ = x[R_RISCV_CALL-51]
+ _ = x[R_RISCV_CALL_TRAMP-52]
+ _ = x[R_RISCV_PCREL_ITYPE-53]
+ _ = x[R_RISCV_PCREL_STYPE-54]
+ _ = x[R_RISCV_TLS_IE_ITYPE-55]
+ _ = x[R_RISCV_TLS_IE_STYPE-56]
+ _ = x[R_PCRELDBL-57]
+ _ = x[R_ADDRMIPSU-58]
+ _ = x[R_ADDRMIPSTLS-59]
+ _ = x[R_ADDRCUOFF-60]
+ _ = x[R_WASMIMPORT-61]
+ _ = x[R_XCOFFREF-62]
}
-const _RelocType_name = "R_ADDRR_ADDRPOWERR_ADDRARM64R_ADDRMIPSR_ADDROFFR_SIZER_CALLR_CALLARMR_CALLARM64R_CALLINDR_CALLPOWERR_CALLMIPSR_CONSTR_PCRELR_TLS_LER_TLS_IER_GOTOFFR_PLT0R_PLT1R_PLT2R_USEFIELDR_USETYPER_USEIFACER_USEIFACEMETHODR_METHODOFFR_KEEPR_POWER_TOCR_GOTPCRELR_JMPMIPSR_DWARFSECREFR_DWARFFILEREFR_ARM64_TLS_LER_ARM64_TLS_IER_ARM64_GOTPCRELR_ARM64_GOTR_ARM64_PCRELR_ARM64_LDST8R_ARM64_LDST16R_ARM64_LDST32R_ARM64_LDST64R_ARM64_LDST128R_POWER_TLS_LER_POWER_TLS_IER_POWER_TLSR_ADDRPOWER_DSR_ADDRPOWER_GOTR_ADDRPOWER_PCRELR_ADDRPOWER_TOCRELR_ADDRPOWER_TOCREL_DSR_RISCV_CALLR_RISCV_CALL_TRAMPR_RISCV_PCREL_ITYPER_RISCV_PCREL_STYPER_RISCV_TLS_IE_ITYPER_RISCV_TLS_IE_STYPER_PCRELDBLR_ADDRMIPSUR_ADDRMIPSTLSR_ADDRCUOFFR_WASMIMPORTR_XCOFFREF"
+const _RelocType_name = "R_ADDRR_ADDRPOWERR_ADDRARM64R_ADDRMIPSR_ADDROFFR_SIZER_CALLR_CALLARMR_CALLARM64R_CALLINDR_CALLPOWERR_CALLMIPSR_CONSTR_PCRELR_TLS_LER_TLS_IER_GOTOFFR_PLT0R_PLT1R_PLT2R_USEFIELDR_USETYPER_USEIFACER_USEIFACEMETHODR_USEGENERICIFACEMETHODR_METHODOFFR_KEEPR_POWER_TOCR_GOTPCRELR_JMPMIPSR_DWARFSECREFR_DWARFFILEREFR_ARM64_TLS_LER_ARM64_TLS_IER_ARM64_GOTPCRELR_ARM64_GOTR_ARM64_PCRELR_ARM64_LDST8R_ARM64_LDST16R_ARM64_LDST32R_ARM64_LDST64R_ARM64_LDST128R_POWER_TLS_LER_POWER_TLS_IER_POWER_TLSR_ADDRPOWER_DSR_ADDRPOWER_GOTR_ADDRPOWER_PCRELR_ADDRPOWER_TOCRELR_ADDRPOWER_TOCREL_DSR_RISCV_CALLR_RISCV_CALL_TRAMPR_RISCV_PCREL_ITYPER_RISCV_PCREL_STYPER_RISCV_TLS_IE_ITYPER_RISCV_TLS_IE_STYPER_PCRELDBLR_ADDRMIPSUR_ADDRMIPSTLSR_ADDRCUOFFR_WASMIMPORTR_XCOFFREF"
-var _RelocType_index = [...]uint16{0, 6, 17, 28, 38, 47, 53, 59, 68, 79, 88, 99, 109, 116, 123, 131, 139, 147, 153, 159, 165, 175, 184, 194, 210, 221, 227, 238, 248, 257, 270, 284, 298, 312, 328, 339, 352, 365, 379, 393, 407, 422, 436, 450, 461, 475, 490, 507, 525, 546, 558, 576, 595, 614, 634, 654, 664, 675, 688, 699, 711, 721}
+var _RelocType_index = [...]uint16{0, 6, 17, 28, 38, 47, 53, 59, 68, 79, 88, 99, 109, 116, 123, 131, 139, 147, 153, 159, 165, 175, 184, 194, 210, 233, 244, 250, 261, 271, 280, 293, 307, 321, 335, 351, 362, 375, 388, 402, 416, 430, 445, 459, 473, 484, 498, 513, 530, 548, 569, 581, 599, 618, 637, 657, 677, 687, 698, 711, 722, 734, 744}
func (i RelocType) String() string {
i -= 1
diff --git a/src/cmd/link/internal/ld/deadcode.go b/src/cmd/link/internal/ld/deadcode.go
index 79acd73..7b57a85 100644
--- a/src/cmd/link/internal/ld/deadcode.go
+++ b/src/cmd/link/internal/ld/deadcode.go
@@ -22,10 +22,11 @@
ldr *loader.Loader
wq heap // work queue, using min-heap for better locality
- ifaceMethod map[methodsig]bool // methods declared in reached interfaces
- markableMethods []methodref // methods of reached types
- reflectSeen bool // whether we have seen a reflect method call
- dynlink bool
+ ifaceMethod map[methodsig]bool // methods called from reached interface call sites
+ genericIfaceMethod map[string]bool // names of methods called from reached generic interface call sites
+ markableMethods []methodref // methods of reached types
+ reflectSeen bool // whether we have seen a reflect method call
+ dynlink bool
methodsigstmp []methodsig // scratch buffer for decoding method signatures
}
@@ -33,6 +34,7 @@
func (d *deadcodePass) init() {
d.ldr.InitReachable()
d.ifaceMethod = make(map[methodsig]bool)
+ d.genericIfaceMethod = make(map[string]bool)
if buildcfg.Experiment.FieldTrack {
d.ldr.Reachparent = make([]loader.Sym, d.ldr.NSym())
}
@@ -197,6 +199,13 @@
}
d.ifaceMethod[m] = true
continue
+ case objabi.R_USEGENERICIFACEMETHOD:
+ name := d.decodeGenericIfaceMethod(d.ldr, r.Sym())
+ if d.ctxt.Debugvlog > 1 {
+ d.ctxt.Logf("reached generic iface method: %s\n", name)
+ }
+ d.genericIfaceMethod[name] = true
+ continue // don't mark referenced symbol - it is not needed in the final binary.
}
rs := r.Sym()
if isgotype && usedInIface && d.ldr.IsGoType(rs) && !d.ldr.AttrUsedInIface(rs) {
@@ -352,7 +361,7 @@
// in the last pass.
rem := d.markableMethods[:0]
for _, m := range d.markableMethods {
- if (d.reflectSeen && m.isExported()) || d.ifaceMethod[m.m] {
+ if (d.reflectSeen && m.isExported()) || d.ifaceMethod[m.m] || d.genericIfaceMethod[m.m.name] {
d.markMethod(m)
} else {
rem = append(rem, m)
@@ -425,6 +434,11 @@
return m
}
+// Decode the method name stored in symbol symIdx. The symbol should contain just the bytes of a method name.
+func (d *deadcodePass) decodeGenericIfaceMethod(ldr *loader.Loader, symIdx loader.Sym) string {
+ return string(ldr.Data(symIdx))
+}
+
func (d *deadcodePass) decodetypeMethods(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym, relocs *loader.Relocs) []methodsig {
p := ldr.Data(symIdx)
if !decodetypeHasUncommon(arch, p) {
diff --git a/test/typeparam/issue49049.go b/test/typeparam/issue49049.go
new file mode 100644
index 0000000..f4fdd05
--- /dev/null
+++ b/test/typeparam/issue49049.go
@@ -0,0 +1,27 @@
+// 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 A[T any] interface {
+ m()
+}
+
+type Z struct {
+ a,b int
+}
+
+func (z *Z) m() {
+}
+
+func test[T any]() {
+ var a A[T] = &Z{}
+ f := a.m
+ f()
+}
+func main() {
+ test[string]()
+}
