1 files changed, 93 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/gc/racewalk.go b/src/cmd/compile/internal/gc/racewalk.go
new file mode 100644
index 0000000..3552617
--- /dev/null
+++ b/src/cmd/compile/internal/gc/racewalk.go
@@ -0,0 +1,93 @@
+// Copyright 2012 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 gc
+
+import (
+	"cmd/compile/internal/types"
+	"cmd/internal/src"
+	"cmd/internal/sys"
+)
+
+// The racewalk pass is currently handled in three parts.
+//
+// First, for flag_race, it inserts calls to racefuncenter and
+// racefuncexit at the start and end (respectively) of each
+// function. This is handled below.
+//
+// Second, during buildssa, it inserts appropriate instrumentation
+// calls immediately before each memory load or store. This is handled
+// by the (*state).instrument method in ssa.go, so here we just set
+// the Func.InstrumentBody flag as needed. For background on why this
+// is done during SSA construction rather than a separate SSA pass,
+// see issue #19054.
+//
+// Third we remove calls to racefuncenter and racefuncexit, for leaf
+// functions without instrumented operations. This is done as part of
+// ssa opt pass via special rule.
+
+// TODO(dvyukov): do not instrument initialization as writes:
+// a := make([]int, 10)
+
+// Do not instrument the following packages at all,
+// at best instrumentation would cause infinite recursion.
+var omit_pkgs = []string{
+	"runtime/internal/atomic",
+	"runtime/internal/sys",
+	"runtime/internal/math",
+	"runtime",
+	"runtime/race",
+	"runtime/msan",
+	"internal/cpu",
+}
+
+// Don't insert racefuncenterfp/racefuncexit into the following packages.
+// Memory accesses in the packages are either uninteresting or will cause false positives.
+var norace_inst_pkgs = []string{"sync", "sync/atomic"}
+
+func ispkgin(pkgs []string) bool {
+	if myimportpath != "" {
+		for _, p := range pkgs {
+			if myimportpath == p {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+func instrument(fn *Node) {
+	if fn.Func.Pragma&Norace != 0 {
+		return
+	}
+
+	if !flag_race || !ispkgin(norace_inst_pkgs) {
+		fn.Func.SetInstrumentBody(true)
+	}
+
+	if flag_race {
+		lno := lineno
+		lineno = src.NoXPos
+
+		if thearch.LinkArch.Arch.Family != sys.AMD64 {
+			fn.Func.Enter.Prepend(mkcall("racefuncenterfp", nil, nil))
+			fn.Func.Exit.Append(mkcall("racefuncexit", nil, nil))
+		} 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 := nodfp.copy()
+			nodpc.Type = types.Types[TUINTPTR]
+			nodpc.Xoffset = int64(-Widthptr)
+			fn.Func.Dcl = append(fn.Func.Dcl, nodpc)
+			fn.Func.Enter.Prepend(mkcall("racefuncenter", nil, nil, nodpc))
+			fn.Func.Exit.Append(mkcall("racefuncexit", nil, nil))
+		}
+		lineno = lno
+	}
+}