Commit 8b3194ac authored by Dhananjay Nakrani's avatar Dhananjay Nakrani Committed by Matthew Dempsky

cmd/compile: fix code duplication in race-instrumentation

instrumentnode() accidentally copies parent's already-instrumented nodes
into child's Ninit block. This generates repeated code in race-instrumentation.
This case surfaces only when it duplicates inline-labels, because of
compile time error. In other cases, it silently generates incorrect
instrumented code. This change prevents it from doing so.

Fixes #17449.

Change-Id: Icddf2198990442166307e176b7e20aa0cf6c171c
Reviewed-on: https://go-review.googlesource.com/31317Reviewed-by: default avatarMatthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
parent 2b687a7d
......@@ -145,36 +145,21 @@ func instrumentnode(np **Node, init *Nodes, wr int, skip int) {
goto ret
case OBLOCK:
var out []*Node
ls := n.List.Slice()
for i := 0; i < len(ls); i++ {
switch ls[i].Op {
case OCALLFUNC, OCALLMETH, OCALLINTER:
instrumentnode(&ls[i], &ls[i].Ninit, 0, 0)
out = append(out, ls[i])
// Scan past OAS nodes copying results off stack.
// Those must not be instrumented, because the
// instrumentation calls will smash the results.
// The assignments are to temporaries, so they cannot
// be involved in races and need not be instrumented.
for i+1 < len(ls) && ls[i+1].Op == OAS && iscallret(ls[i+1].Right) {
i++
out = append(out, ls[i])
}
default:
var outn Nodes
outn.Set(out)
instrumentnode(&ls[i], &outn, 0, 0)
if ls[i].Op != OAS && ls[i].Op != OASWB && ls[i].Op != OAS2FUNC || ls[i].Ninit.Len() == 0 {
out = append(outn.Slice(), ls[i])
} else {
// Splice outn onto end of ls[i].Ninit
ls[i].Ninit.AppendNodes(&outn)
out = append(out, ls[i])
}
afterCall := false
for i := range ls {
op := ls[i].Op
// Scan past OAS nodes copying results off stack.
// Those must not be instrumented, because the
// instrumentation calls will smash the results.
// The assignments are to temporaries, so they cannot
// be involved in races and need not be instrumented.
if afterCall && op == OAS && iscallret(ls[i].Right) {
continue
}
instrumentnode(&ls[i], &ls[i].Ninit, 0, 0)
afterCall = (op == OCALLFUNC || op == OCALLMETH || op == OCALLINTER)
}
n.List.Set(out)
goto ret
case ODEFER:
......
// errorcheck -0 -race
// Copyright 2016 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.
// Issue 17449: race instrumentation copies over previous instrumented nodes from parents block into child's Ninit block.
// This code surfaces the duplication at compile time because of generated inline labels.
package master
type PriorityList struct {
elems []interface{}
}
func (x *PriorityList) Len() int { return len(x.elems) }
func (l *PriorityList) remove(i int) interface{} {
elem := l.elems[i]
l.elems = append(l.elems[:i], l.elems[i+1:]...)
return elem
}
func (l *PriorityList) Next() interface{} {
return l.remove(l.Len() - 1)
}
var l *PriorityList
func Foo() {
// It would fail here if instrumented code (including inline-label) was copied.
for elem := l.Next(); elem != nil; elem = l.Next() {
}
}
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