cmd/compile: experiment which clobbers all dead pointer fields
The experiment "clobberdead" clobbers all pointer fields that the
compiler thinks are dead, just before and after every safepoint.
Useful for debugging the generation of live pointer bitmaps.
Helped find the following issues:
Update #15936
Update #16026
Update #16095
Update #18860
Change-Id: Id1d12f86845e3d93bae903d968b1eac61fc461f9
Reviewed-on: https://go-review.googlesource.com/23924
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
diff --git a/src/cmd/compile/internal/amd64/ssa.go b/src/cmd/compile/internal/amd64/ssa.go
index f4be875..7381534 100644
--- a/src/cmd/compile/internal/amd64/ssa.go
+++ b/src/cmd/compile/internal/amd64/ssa.go
@@ -895,6 +895,20 @@
p.To.Type = obj.TYPE_MEM
p.To.Reg = v.Args[0].Reg()
gc.AddAux(&p.To, v)
+ case ssa.OpClobber:
+ p := s.Prog(x86.AMOVL)
+ p.From.Type = obj.TYPE_CONST
+ p.From.Offset = 0xdeaddead
+ p.To.Type = obj.TYPE_MEM
+ p.To.Reg = x86.REG_SP
+ gc.AddAux(&p.To, v)
+ p = s.Prog(x86.AMOVL)
+ p.From.Type = obj.TYPE_CONST
+ p.From.Offset = 0xdeaddead
+ p.To.Type = obj.TYPE_MEM
+ p.To.Reg = x86.REG_SP
+ gc.AddAux(&p.To, v)
+ p.To.Offset += 4
default:
v.Fatalf("genValue not implemented: %s", v.LongString())
}
diff --git a/src/cmd/compile/internal/arm/ssa.go b/src/cmd/compile/internal/arm/ssa.go
index 5d699a8..8faaf0f 100644
--- a/src/cmd/compile/internal/arm/ssa.go
+++ b/src/cmd/compile/internal/arm/ssa.go
@@ -759,6 +759,8 @@
v.Fatalf("Flag* ops should never make it to codegen %v", v.LongString())
case ssa.OpARMInvertFlags:
v.Fatalf("InvertFlags should never make it to codegen %v", v.LongString())
+ case ssa.OpClobber:
+ // TODO: implement for clobberdead experiment. Nop is ok for now.
default:
v.Fatalf("genValue not implemented: %s", v.LongString())
}
diff --git a/src/cmd/compile/internal/arm64/ssa.go b/src/cmd/compile/internal/arm64/ssa.go
index c83deea..7d79276 100644
--- a/src/cmd/compile/internal/arm64/ssa.go
+++ b/src/cmd/compile/internal/arm64/ssa.go
@@ -662,6 +662,8 @@
v.Fatalf("Flag* ops 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:
+ // TODO: implement for clobberdead experiment. Nop is ok for now.
default:
v.Fatalf("genValue not implemented: %s", v.LongString())
}
diff --git a/src/cmd/compile/internal/gc/plive.go b/src/cmd/compile/internal/gc/plive.go
index e53e2b6..4525426 100644
--- a/src/cmd/compile/internal/gc/plive.go
+++ b/src/cmd/compile/internal/gc/plive.go
@@ -18,8 +18,12 @@
"cmd/compile/internal/ssa"
"cmd/compile/internal/types"
"cmd/internal/obj"
+ "cmd/internal/objabi"
+ "cmd/internal/src"
"crypto/md5"
+ "crypto/sha1"
"fmt"
+ "os"
"strings"
)
@@ -121,8 +125,7 @@
// index within the stack maps.
stackMapIndex map[*ssa.Value]int
- // An array with a bit vector for each safe point tracking
- // live variables, indexed by bb.rpo.
+ // An array with a bit vector for each safe point tracking live variables.
livevars []bvec
cache progeffectscache
@@ -795,6 +798,165 @@
}
}
+func (lv *Liveness) clobber() {
+ // The clobberdead experiment inserts code to clobber all the dead variables (locals and args)
+ // before and after every safepoint. This experiment is useful for debugging the generation
+ // of live pointer bitmaps.
+ if objabi.Clobberdead_enabled == 0 {
+ return
+ }
+ var varSize int64
+ for _, n := range lv.vars {
+ varSize += n.Type.Size()
+ }
+ if len(lv.livevars) > 1000 || varSize > 10000 {
+ // Be careful to avoid doing too much work.
+ // Bail if >1000 safepoints or >10000 bytes of variables.
+ // Otherwise, giant functions make this experiment generate too much code.
+ return
+ }
+ if h := os.Getenv("GOCLOBBERDEADHASH"); h != "" {
+ // Clobber only functions where the hash of the function name matches a pattern.
+ // Useful for binary searching for a miscompiled function.
+ hstr := ""
+ for _, b := range sha1.Sum([]byte(lv.fn.Func.Nname.Sym.Name)) {
+ hstr += fmt.Sprintf("%08b", b)
+ }
+ if !strings.HasSuffix(hstr, h) {
+ return
+ }
+ fmt.Printf("\t\t\tCLOBBERDEAD %s\n", lv.fn.Func.Nname.Sym.Name)
+ }
+ if lv.f.Name == "forkAndExecInChild" {
+ // forkAndExecInChild calls vfork (on linux/amd64, anyway).
+ // The code we add here clobbers parts of the stack in the child.
+ // When the parent resumes, it is using the same stack frame. But the
+ // child has clobbered stack variables that the parent needs. Boom!
+ // In particular, the sys argument gets clobbered.
+ // Note to self: GOCLOBBERDEADHASH=011100101110
+ return
+ }
+
+ var oldSched []*ssa.Value
+ for _, b := range lv.f.Blocks {
+ // Copy block's values to a temporary.
+ oldSched = append(oldSched[:0], b.Values...)
+ b.Values = b.Values[:0]
+
+ // Clobber all dead variables at entry.
+ if b == lv.f.Entry {
+ for len(oldSched) > 0 && len(oldSched[0].Args) == 0 {
+ // Skip argless ops. We need to skip at least
+ // the lowered ClosurePtr op, because it
+ // really wants to be first. This will also
+ // skip ops like InitMem and SP, which are ok.
+ b.Values = append(b.Values, oldSched[0])
+ oldSched = oldSched[1:]
+ }
+ clobber(lv, b, lv.livevars[0])
+ }
+
+ // Copy values into schedule, adding clobbering around safepoints.
+ for _, v := range oldSched {
+ if !issafepoint(v) {
+ b.Values = append(b.Values, v)
+ continue
+ }
+ before := true
+ if v.Op.IsCall() && v.Aux != nil && v.Aux.(*obj.LSym) == typedmemmove {
+ // Can't put clobber code before the call to typedmemmove.
+ // The variable to-be-copied is marked as dead
+ // at the callsite. That is ok, though, as typedmemmove
+ // is marked as nosplit, and the first thing it does
+ // is to call memmove (also nosplit), after which
+ // the source value is dead.
+ // See issue 16026.
+ before = false
+ }
+ if before {
+ clobber(lv, b, lv.livevars[lv.stackMapIndex[v]])
+ }
+ b.Values = append(b.Values, v)
+ clobber(lv, b, lv.livevars[lv.stackMapIndex[v]])
+ }
+ }
+}
+
+// clobber generates code to clobber all dead variables (those not marked in live).
+// Clobbering instructions are added to the end of b.Values.
+func clobber(lv *Liveness, b *ssa.Block, live bvec) {
+ for i, n := range lv.vars {
+ if !live.Get(int32(i)) {
+ clobberVar(b, n)
+ }
+ }
+}
+
+// clobberVar generates code to trash the pointers in v.
+// Clobbering instructions are added to the end of b.Values.
+func clobberVar(b *ssa.Block, v *Node) {
+ clobberWalk(b, v, 0, v.Type)
+}
+
+// b = block to which we append instructions
+// v = variable
+// offset = offset of (sub-portion of) variable to clobber (in bytes)
+// t = type of sub-portion of v.
+func clobberWalk(b *ssa.Block, v *Node, offset int64, t *types.Type) {
+ if !types.Haspointers(t) {
+ return
+ }
+ switch t.Etype {
+ case TPTR32,
+ TPTR64,
+ TUNSAFEPTR,
+ TFUNC,
+ TCHAN,
+ TMAP:
+ clobberPtr(b, v, offset)
+
+ case TSTRING:
+ // struct { byte *str; int len; }
+ clobberPtr(b, v, offset)
+
+ case TINTER:
+ // struct { Itab *tab; void *data; }
+ // or, when isnilinter(t)==true:
+ // struct { Type *type; void *data; }
+ clobberPtr(b, v, offset)
+ clobberPtr(b, v, offset+int64(Widthptr))
+
+ case TSLICE:
+ // struct { byte *array; int len; int cap; }
+ clobberPtr(b, v, offset)
+
+ case TARRAY:
+ for i := int64(0); i < t.NumElem(); i++ {
+ clobberWalk(b, v, offset+i*t.Elem().Size(), t.Elem())
+ }
+
+ case TSTRUCT:
+ for _, t1 := range t.Fields().Slice() {
+ clobberWalk(b, v, offset+t1.Offset, t1.Type)
+ }
+
+ default:
+ Fatalf("clobberWalk: unexpected type, %v", t)
+ }
+}
+
+// clobberPtr generates a clobber of the pointer at offset offset in v.
+// The clobber instruction is added at the end of b.
+func clobberPtr(b *ssa.Block, v *Node, offset int64) {
+ var aux interface{}
+ if v.Class == PAUTO {
+ aux = &ssa.AutoSymbol{Node: v}
+ } else {
+ aux = &ssa.ArgSymbol{Node: v}
+ }
+ b.NewValue0IA(src.NoXPos, ssa.OpClobber, ssa.TypeVoid, offset, aux)
+}
+
func (lv *Liveness) avarinitanyall(b *ssa.Block, any, all bvec) {
if len(b.Preds) == 0 {
any.Clear()
@@ -1154,6 +1316,7 @@
livenesssolve(lv)
livenessepilogue(lv)
livenesscompact(lv)
+ lv.clobber()
if debuglive >= 2 {
livenessprintdebug(lv)
}
diff --git a/src/cmd/compile/internal/mips/ssa.go b/src/cmd/compile/internal/mips/ssa.go
index 6d18a5a..3673523 100644
--- a/src/cmd/compile/internal/mips/ssa.go
+++ b/src/cmd/compile/internal/mips/ssa.go
@@ -754,6 +754,8 @@
case ssa.OpMIPSLoweredGetClosurePtr:
// Closure pointer is R22 (mips.REGCTXT).
gc.CheckLoweredGetClosurePtr(v)
+ case ssa.OpClobber:
+ // TODO: implement for clobberdead experiment. Nop is ok for now.
default:
v.Fatalf("genValue not implemented: %s", v.LongString())
}
diff --git a/src/cmd/compile/internal/mips64/ssa.go b/src/cmd/compile/internal/mips64/ssa.go
index fea50e8..487d624 100644
--- a/src/cmd/compile/internal/mips64/ssa.go
+++ b/src/cmd/compile/internal/mips64/ssa.go
@@ -519,6 +519,8 @@
case ssa.OpMIPS64LoweredGetClosurePtr:
// Closure pointer is R22 (mips.REGCTXT).
gc.CheckLoweredGetClosurePtr(v)
+ case ssa.OpClobber:
+ // TODO: implement for clobberdead experiment. Nop is ok for now.
default:
v.Fatalf("genValue not implemented: %s", v.LongString())
}
diff --git a/src/cmd/compile/internal/ppc64/ssa.go b/src/cmd/compile/internal/ppc64/ssa.go
index 62aeee2..4bd69a4 100644
--- a/src/cmd/compile/internal/ppc64/ssa.go
+++ b/src/cmd/compile/internal/ppc64/ssa.go
@@ -1132,7 +1132,8 @@
v.Fatalf("InvertFlags should never make it to codegen %v", v.LongString())
case ssa.OpPPC64FlagEQ, ssa.OpPPC64FlagLT, ssa.OpPPC64FlagGT:
v.Fatalf("Flag* ops should never make it to codegen %v", v.LongString())
-
+ case ssa.OpClobber:
+ // TODO: implement for clobberdead experiment. Nop is ok for now.
default:
v.Fatalf("genValue not implemented: %s", v.LongString())
}
diff --git a/src/cmd/compile/internal/s390x/ssa.go b/src/cmd/compile/internal/s390x/ssa.go
index 3c26dc4..9ccd3c7 100644
--- a/src/cmd/compile/internal/s390x/ssa.go
+++ b/src/cmd/compile/internal/s390x/ssa.go
@@ -732,6 +732,8 @@
bne := s.Prog(s390x.ABNE)
bne.To.Type = obj.TYPE_BRANCH
gc.Patch(bne, cs)
+ case ssa.OpClobber:
+ // TODO: implement for clobberdead experiment. Nop is ok for now.
default:
v.Fatalf("genValue not implemented: %s", v.LongString())
}
diff --git a/src/cmd/compile/internal/ssa/gen/386Ops.go b/src/cmd/compile/internal/ssa/gen/386Ops.go
index b287775..8965d62 100644
--- a/src/cmd/compile/internal/ssa/gen/386Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/386Ops.go
@@ -389,7 +389,7 @@
faultOnNilArg0: true,
},
- {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
+ {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("DX"), 0}, clobbers: callerSave}, aux: "Int64", 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: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64Ops.go b/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
index 76e8273..ed77bb0 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/AMD64Ops.go
@@ -478,7 +478,7 @@
faultOnNilArg0: true,
},
- {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
+ {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("DX"), 0}, clobbers: callerSave}, aux: "Int64", 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: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
diff --git a/src/cmd/compile/internal/ssa/gen/ARM64Ops.go b/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
index be7fa21..832bea2 100644
--- a/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
@@ -318,7 +318,7 @@
{name: "CSELULT0", argLength: 2, reg: gp1flags1, asm: "CSEL"}, // returns arg0 if flags indicates unsigned LT, 0 otherwise, arg1=flags
// function calls
- {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
+ {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // 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: "Int64", 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: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
diff --git a/src/cmd/compile/internal/ssa/gen/ARMOps.go b/src/cmd/compile/internal/ssa/gen/ARMOps.go
index baf0350..40be5d6 100644
--- a/src/cmd/compile/internal/ssa/gen/ARMOps.go
+++ b/src/cmd/compile/internal/ssa/gen/ARMOps.go
@@ -377,7 +377,7 @@
{name: "SRAcond", argLength: 3, reg: gp2flags1, asm: "SRA"}, // arg0 >> 31 if flags indicates HS, arg0 >> arg1 otherwise, signed shift, arg2=flags
// function calls
- {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
+ {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R7"), 0}, clobbers: callerSave}, aux: "Int64", 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: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
diff --git a/src/cmd/compile/internal/ssa/gen/MIPS64Ops.go b/src/cmd/compile/internal/ssa/gen/MIPS64Ops.go
index d5d49f5..b0e6564 100644
--- a/src/cmd/compile/internal/ssa/gen/MIPS64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/MIPS64Ops.go
@@ -264,7 +264,7 @@
{name: "MOVDF", argLength: 1, reg: fp11, asm: "MOVDF"}, // float64 -> float32
// function calls
- {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
+ {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R22"), 0}, clobbers: callerSave}, aux: "Int64", 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: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
diff --git a/src/cmd/compile/internal/ssa/gen/MIPSOps.go b/src/cmd/compile/internal/ssa/gen/MIPSOps.go
index a967969..b632c6b 100644
--- a/src/cmd/compile/internal/ssa/gen/MIPSOps.go
+++ b/src/cmd/compile/internal/ssa/gen/MIPSOps.go
@@ -248,7 +248,7 @@
{name: "MOVDF", argLength: 1, reg: fp11, asm: "MOVDF"}, // float64 -> float32
// function calls
- {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
+ {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R22"), 0}, clobbers: callerSave}, aux: "Int64", 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: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
diff --git a/src/cmd/compile/internal/ssa/gen/PPC64Ops.go b/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
index 6cca77e..f198c13 100644
--- a/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
@@ -309,7 +309,7 @@
// Convert pointer to integer, takes a memory operand for ordering.
{name: "MOVDconvert", argLength: 2, reg: gp11, asm: "MOVD"},
- {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
+ {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gp | sp, ctxt, 0}, clobbers: callerSave}, aux: "Int64", 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: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
diff --git a/src/cmd/compile/internal/ssa/gen/S390XOps.go b/src/cmd/compile/internal/ssa/gen/S390XOps.go
index a207743..a1a5aa2 100644
--- a/src/cmd/compile/internal/ssa/gen/S390XOps.go
+++ b/src/cmd/compile/internal/ssa/gen/S390XOps.go
@@ -413,7 +413,7 @@
{name: "CLEAR", argLength: 2, reg: regInfo{inputs: []regMask{ptr, 0}}, asm: "CLEAR", aux: "SymValAndOff", typ: "Mem", clobberFlags: true, faultOnNilArg0: true, symEffect: "Write"},
- {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*gc.Sym). arg0=mem, auxint=argsize, returns mem
+ {name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"}, // call static function aux.(*obj.LSym). arg0=mem, auxint=argsize, returns mem
{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{ptrsp, buildReg("R12"), 0}, clobbers: callerSave}, aux: "Int64", 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{ptr}, clobbers: callerSave}, aux: "Int64", clobberFlags: true, call: true}, // call fn by pointer. arg0=codeptr, arg1=mem, auxint=argsize, returns mem
diff --git a/src/cmd/compile/internal/ssa/gen/genericOps.go b/src/cmd/compile/internal/ssa/gen/genericOps.go
index 300a545..e9a9096 100644
--- a/src/cmd/compile/internal/ssa/gen/genericOps.go
+++ b/src/cmd/compile/internal/ssa/gen/genericOps.go
@@ -314,7 +314,7 @@
// Return values appear on the stack. The method receiver, if any, is treated
// as a phantom first argument.
{name: "ClosureCall", argLength: 3, aux: "Int64", call: true}, // arg0=code pointer, arg1=context ptr, arg2=memory. auxint=arg size. Returns memory.
- {name: "StaticCall", argLength: 1, aux: "SymOff", call: true, symEffect: "None"}, // call function aux.(*gc.Sym), arg0=memory. auxint=arg size. Returns memory.
+ {name: "StaticCall", argLength: 1, aux: "SymOff", call: true, symEffect: "None"}, // call function aux.(*obj.LSym), arg0=memory. auxint=arg size. Returns memory.
{name: "InterCall", argLength: 2, aux: "Int64", call: true}, // interface call. arg0=code pointer, arg1=memory, auxint=arg size. Returns memory.
// Conversions: signed extensions, zero (unsigned) extensions, truncations
@@ -464,6 +464,9 @@
{name: "AtomicCompareAndSwap64", argLength: 4, typ: "(Bool,Mem)", hasSideEffects: true}, // if *arg0==arg1, then set *arg0=arg2. Returns true iff store happens and new memory.
{name: "AtomicAnd8", argLength: 3, typ: "Mem", hasSideEffects: true}, // *arg0 &= arg1. arg2=memory. Returns memory.
{name: "AtomicOr8", argLength: 3, typ: "Mem", hasSideEffects: true}, // *arg0 |= arg1. arg2=memory. Returns memory.
+
+ // Clobber experiment op
+ {name: "Clobber", argLength: 0, typ: "Void", aux: "SymOff", symEffect: "None"}, // write an invalid pointer value to the given pointer slot of a stack variable
}
// kind control successors implicit exit
diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index a7977fe..47c9dba 100644
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -1926,6 +1926,7 @@
OpAtomicCompareAndSwap64
OpAtomicAnd8
OpAtomicOr8
+ OpClobber
)
var opcodeTable = [...]opInfo{
@@ -22607,6 +22608,13 @@
hasSideEffects: true,
generic: true,
},
+ {
+ name: "Clobber",
+ auxType: auxSymOff,
+ argLen: 0,
+ symEffect: SymNone,
+ generic: true,
+ },
}
func (o Op) Asm() obj.As { return opcodeTable[o].asm }
diff --git a/src/cmd/compile/internal/x86/ssa.go b/src/cmd/compile/internal/x86/ssa.go
index e7fcc97..3822272 100644
--- a/src/cmd/compile/internal/x86/ssa.go
+++ b/src/cmd/compile/internal/x86/ssa.go
@@ -738,6 +738,13 @@
}
case ssa.Op386FCHS:
v.Fatalf("FCHS in non-387 mode")
+ case ssa.OpClobber:
+ p := s.Prog(x86.AMOVL)
+ p.From.Type = obj.TYPE_CONST
+ p.From.Offset = 0xdeaddead
+ p.To.Type = obj.TYPE_MEM
+ p.To.Reg = x86.REG_SP
+ gc.AddAux(&p.To, v)
default:
v.Fatalf("genValue not implemented: %s", v.LongString())
}
