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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/31317 Reviewed-by: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
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@ -145,36 +145,21 @@ func instrumentnode(np **Node, init *Nodes, wr int, skip int) {
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goto ret
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case OBLOCK:
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var out []*Node
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ls := n.List.Slice()
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for i := 0; i < len(ls); i++ {
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switch ls[i].Op {
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case OCALLFUNC, OCALLMETH, OCALLINTER:
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instrumentnode(&ls[i], &ls[i].Ninit, 0, 0)
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out = append(out, ls[i])
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// Scan past OAS nodes copying results off stack.
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// Those must not be instrumented, because the
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// instrumentation calls will smash the results.
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// The assignments are to temporaries, so they cannot
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// be involved in races and need not be instrumented.
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for i+1 < len(ls) && ls[i+1].Op == OAS && iscallret(ls[i+1].Right) {
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i++
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out = append(out, ls[i])
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}
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default:
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var outn Nodes
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outn.Set(out)
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instrumentnode(&ls[i], &outn, 0, 0)
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if ls[i].Op != OAS && ls[i].Op != OASWB && ls[i].Op != OAS2FUNC || ls[i].Ninit.Len() == 0 {
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out = append(outn.Slice(), ls[i])
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} else {
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// Splice outn onto end of ls[i].Ninit
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ls[i].Ninit.AppendNodes(&outn)
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out = append(out, ls[i])
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}
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afterCall := false
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for i := range ls {
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op := ls[i].Op
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// Scan past OAS nodes copying results off stack.
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// Those must not be instrumented, because the
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// instrumentation calls will smash the results.
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// The assignments are to temporaries, so they cannot
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// be involved in races and need not be instrumented.
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if afterCall && op == OAS && iscallret(ls[i].Right) {
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continue
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}
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instrumentnode(&ls[i], &ls[i].Ninit, 0, 0)
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afterCall = (op == OCALLFUNC || op == OCALLMETH || op == OCALLINTER)
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}
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n.List.Set(out)
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goto ret
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case ODEFER:
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34
test/fixedbugs/issue17449.go
Normal file
34
test/fixedbugs/issue17449.go
Normal file
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@ -0,0 +1,34 @@
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// errorcheck -0 -race
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Issue 17449: race instrumentation copies over previous instrumented nodes from parents block into child's Ninit block.
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// This code surfaces the duplication at compile time because of generated inline labels.
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package master
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type PriorityList struct {
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elems []interface{}
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}
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func (x *PriorityList) Len() int { return len(x.elems) }
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func (l *PriorityList) remove(i int) interface{} {
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elem := l.elems[i]
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l.elems = append(l.elems[:i], l.elems[i+1:]...)
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return elem
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}
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func (l *PriorityList) Next() interface{} {
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return l.remove(l.Len() - 1)
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}
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var l *PriorityList
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func Foo() {
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// It would fail here if instrumented code (including inline-label) was copied.
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for elem := l.Next(); elem != nil; elem = l.Next() {
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}
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}
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