cmd/compile: use getcallerpc for racefuncentry

Currently, when instrumenting for the race detector, the compiler
inserts racefuncentry/racefuncentryfp at the entry of instrumented
functions. racefuncentry takes the caller's PC. On AMD64, we synthesize
a node which points to -8(FP) which is where the return address is
stored. Later this node turns to a special Arg in SSA that is not
really an argument. This causes problems in the new ABI work so that
special node has to be special-cased.

This CL changes the special node to a call to getcallerpc, which lowers
to an intrinsic in SSA. This also unifies AMD64 code path and LR machine
code path, as getcallerpc works on all platforms.

Change-Id: I1377e140b91e0473cfcadfda221f26870c1b124d
Reviewed-on: https://go-review.googlesource.com/c/go/+/297929
Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>

src/cmd/compile/internal/base/base.go

@@ -70,6 +70,6 @@ var NoInstrumentPkgs = []string{
 	"internal/cpu",
 }
 
-// Don't insert racefuncenterfp/racefuncexit into the following packages.
+// Don't insert racefuncenter/racefuncexit into the following packages.
 // Memory accesses in the packages are either uninteresting or will cause false positives.
 var NoRacePkgs = []string{"sync", "sync/atomic"}

src/cmd/compile/internal/ssa/rewrite.go

@@ -1612,18 +1612,18 @@ func needRaceCleanup(sym *AuxCall, v *Value) bool {
 	if !f.Config.Race {
 		return false
 	}
-	if !isSameCall(sym, "runtime.racefuncenter") && !isSameCall(sym, "runtime.racefuncenterfp") && !isSameCall(sym, "runtime.racefuncexit") {
+	if !isSameCall(sym, "runtime.racefuncenter") && !isSameCall(sym, "runtime.racefuncexit") {
 		return false
 	}
 	for _, b := range f.Blocks {
 		for _, v := range b.Values {
 			switch v.Op {
 			case OpStaticCall, OpStaticLECall:
-				// Check for racefuncenter/racefuncenterfp will encounter racefuncexit and vice versa.
+				// Check for racefuncenter will encounter racefuncexit and vice versa.
 				// Allow calls to panic*
 				s := v.Aux.(*AuxCall).Fn.String()
 				switch s {
-				case "runtime.racefuncenter", "runtime.racefuncenterfp", "runtime.racefuncexit",
+				case "runtime.racefuncenter", "runtime.racefuncexit",
 					"runtime.panicdivide", "runtime.panicwrap",
 					"runtime.panicshift":
 					continue

src/cmd/compile/internal/ssagen/ssa.go

@@ -4564,6 +4564,9 @@ func findIntrinsic(sym *types.Sym) intrinsicBuilder {
 	if sym.Pkg == types.LocalPkg {
 		pkg = base.Ctxt.Pkgpath
 	}
+	if sym.Pkg == ir.Pkgs.Runtime {
+		pkg = "runtime"
+	}
 	if base.Flag.Race && pkg == "sync/atomic" {
 		// The race detector needs to be able to intercept these calls.
 		// We can't intrinsify them.

src/cmd/compile/internal/typecheck/builtin.go

@@ -177,26 +177,26 @@ var runtimeDecls = [...]struct {
 	{"uint64tofloat64", funcTag, 116},
 	{"uint32tofloat64", funcTag, 117},
 	{"complex128div", funcTag, 118},
+	{"getcallerpc", funcTag, 119},
 	{"racefuncenter", funcTag, 31},
-	{"racefuncenterfp", funcTag, 9},
 	{"racefuncexit", funcTag, 9},
 	{"raceread", funcTag, 31},
 	{"racewrite", funcTag, 31},
-	{"racereadrange", funcTag, 119},
-	{"racewriterange", funcTag, 119},
-	{"msanread", funcTag, 119},
-	{"msanwrite", funcTag, 119},
-	{"msanmove", funcTag, 120},
-	{"checkptrAlignment", funcTag, 121},
-	{"checkptrArithmetic", funcTag, 123},
-	{"libfuzzerTraceCmp1", funcTag, 125},
-	{"libfuzzerTraceCmp2", funcTag, 127},
-	{"libfuzzerTraceCmp4", funcTag, 128},
-	{"libfuzzerTraceCmp8", funcTag, 129},
-	{"libfuzzerTraceConstCmp1", funcTag, 125},
-	{"libfuzzerTraceConstCmp2", funcTag, 127},
-	{"libfuzzerTraceConstCmp4", funcTag, 128},
-	{"libfuzzerTraceConstCmp8", funcTag, 129},
+	{"racereadrange", funcTag, 120},
+	{"racewriterange", funcTag, 120},
+	{"msanread", funcTag, 120},
+	{"msanwrite", funcTag, 120},
+	{"msanmove", funcTag, 121},
+	{"checkptrAlignment", funcTag, 122},
+	{"checkptrArithmetic", funcTag, 124},
+	{"libfuzzerTraceCmp1", funcTag, 126},
+	{"libfuzzerTraceCmp2", funcTag, 128},
+	{"libfuzzerTraceCmp4", funcTag, 129},
+	{"libfuzzerTraceCmp8", funcTag, 130},
+	{"libfuzzerTraceConstCmp1", funcTag, 126},
+	{"libfuzzerTraceConstCmp2", funcTag, 128},
+	{"libfuzzerTraceConstCmp4", funcTag, 129},
+	{"libfuzzerTraceConstCmp8", funcTag, 130},
 	{"x86HasPOPCNT", varTag, 6},
 	{"x86HasSSE41", varTag, 6},
 	{"x86HasFMA", varTag, 6},
@@ -219,7 +219,7 @@ func params(tlist ...*types.Type) []*types.Field {
 }
 
 func runtimeTypes() []*types.Type {
-	var typs [130]*types.Type
+	var typs [131]*types.Type
 	typs[0] = types.ByteType
 	typs[1] = types.NewPtr(typs[0])
 	typs[2] = types.Types[types.TANY]
@@ -339,16 +339,17 @@ func runtimeTypes() []*types.Type {
 	typs[116] = newSig(params(typs[24]), params(typs[20]))
 	typs[117] = newSig(params(typs[65]), params(typs[20]))
 	typs[118] = newSig(params(typs[26], typs[26]), params(typs[26]))
-	typs[119] = newSig(params(typs[5], typs[5]), nil)
-	typs[120] = newSig(params(typs[5], typs[5], typs[5]), nil)
-	typs[121] = newSig(params(typs[7], typs[1], typs[5]), nil)
-	typs[122] = types.NewSlice(typs[7])
-	typs[123] = newSig(params(typs[7], typs[122]), nil)
-	typs[124] = types.Types[types.TUINT8]
-	typs[125] = newSig(params(typs[124], typs[124]), nil)
-	typs[126] = types.Types[types.TUINT16]
-	typs[127] = newSig(params(typs[126], typs[126]), nil)
-	typs[128] = newSig(params(typs[65], typs[65]), nil)
-	typs[129] = newSig(params(typs[24], typs[24]), nil)
+	typs[119] = newSig(nil, params(typs[5]))
+	typs[120] = newSig(params(typs[5], typs[5]), nil)
+	typs[121] = newSig(params(typs[5], typs[5], typs[5]), nil)
+	typs[122] = newSig(params(typs[7], typs[1], typs[5]), nil)
+	typs[123] = types.NewSlice(typs[7])
+	typs[124] = newSig(params(typs[7], typs[123]), nil)
+	typs[125] = types.Types[types.TUINT8]
+	typs[126] = newSig(params(typs[125], typs[125]), nil)
+	typs[127] = types.Types[types.TUINT16]
+	typs[128] = newSig(params(typs[127], typs[127]), nil)
+	typs[129] = newSig(params(typs[65], typs[65]), nil)
+	typs[130] = newSig(params(typs[24], typs[24]), nil)
 	return typs[:]
 }

src/cmd/compile/internal/typecheck/builtin/runtime.go

@@ -6,6 +6,7 @@
 // to update builtin.go. This is not done automatically
 // to avoid depending on having a working compiler binary.
 
+//go:build ignore
 // +build ignore
 
 package runtime
@@ -224,9 +225,10 @@ func uint32tofloat64(uint32) float64
 
 func complex128div(num complex128, den complex128) (quo complex128)
 
+func getcallerpc() uintptr
+
 // race detection
 func racefuncenter(uintptr)
-func racefuncenterfp()
 func racefuncexit()
 func raceread(uintptr)
 func racewrite(uintptr)

src/cmd/compile/internal/walk/race.go

@@ -7,11 +7,8 @@ package walk
 import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
-	"cmd/compile/internal/ssagen"
-	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
 	"cmd/internal/src"
-	"cmd/internal/sys"
 )
 
 func instrument(fn *ir.Func) {
@@ -26,26 +23,12 @@ func instrument(fn *ir.Func) {
 	if base.Flag.Race {
 		lno := base.Pos
 		base.Pos = src.NoXPos
-		if ssagen.Arch.LinkArch.Arch.Family != sys.AMD64 {
-			fn.Enter.Prepend(mkcallstmt("racefuncenterfp"))
-			fn.Exit.Append(mkcallstmt("racefuncexit"))
-		} else {
-
-			// nodpc is the PC of the caller as extracted by
-			// getcallerpc. We use -widthptr(FP) for x86.
-			// This only works for amd64. This will not
-			// work on arm or others that might support
-			// race in the future.
-
-			nodpc := ir.NewNameAt(src.NoXPos, typecheck.Lookup(".fp"))
-			nodpc.Class = ir.PPARAM
-			nodpc.SetUsed(true)
-			nodpc.SetType(types.Types[types.TUINTPTR])
-			nodpc.SetFrameOffset(int64(-types.PtrSize))
-			fn.Dcl = append(fn.Dcl, nodpc)
-			fn.Enter.Prepend(mkcallstmt("racefuncenter", nodpc))
-			fn.Exit.Append(mkcallstmt("racefuncexit"))
+		var init ir.Nodes
+		fn.Enter.Prepend(mkcallstmt("racefuncenter", mkcall("getcallerpc", types.Types[types.TUINTPTR], &init)))
+		if len(init) != 0 {
+			base.Fatalf("race walk: unexpected init for getcallerpc")
 		}
+		fn.Exit.Append(mkcallstmt("racefuncexit"))
 		base.Pos = lno
 	}
 }