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cmd/gc: don't believe that variables mentioned 256 times are unused.

Such variables would be put at 0(SP), leading to serious
corruptions at zero initialization.
Fixes #3084.

R=golang-dev, r
CC=golang-dev, remy
https://golang.org/cl/5683052
This commit is contained in:
Rémy Oudompheng 2012-02-21 16:38:01 +11:00 committed by Rob Pike
parent c9bb042287
commit f2ad374ae6
4 changed files with 283 additions and 6 deletions

View File

@ -29,10 +29,10 @@ markautoused(Prog* p)
{
for (; p; p = p->link) {
if (p->from.name == D_AUTO && p->from.node)
p->from.node->used++;
p->from.node->used = 1;
if (p->to.name == D_AUTO && p->to.node)
p->to.node->used++;
p->to.node->used = 1;
}
}

View File

@ -26,10 +26,10 @@ markautoused(Prog* p)
{
for (; p; p = p->link) {
if (p->from.type == D_AUTO && p->from.node)
p->from.node->used++;
p->from.node->used = 1;
if (p->to.type == D_AUTO && p->to.node)
p->to.node->used++;
p->to.node->used = 1;
}
}

View File

@ -28,10 +28,10 @@ markautoused(Prog* p)
{
for (; p; p = p->link) {
if (p->from.type == D_AUTO && p->from.node)
p->from.node->used++;
p->from.node->used = 1;
if (p->to.type == D_AUTO && p->to.node)
p->to.node->used++;
p->to.node->used = 1;
}
}

277
test/fixedbugs/bug423.go Normal file
View File

@ -0,0 +1,277 @@
// run
// 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.
// gc used to overflow a counter when a variable was
// mentioned 256 times, and generate stack corruption.
package main
func main() {
F(1)
}
func F(arg int) {
var X int64
_ = X // used once
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0 // used 32 times
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0 // used 64 times
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0 // used 96 times
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0 // used 128 times
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0 // used 200 times
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0
X = 0 // used 256 times
if arg != 0 {
panic("argument was changed")
}
}