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// 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
}
}
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