runtime: round return value address in runtime.equal

Fixes #3866.

R=rsc, r, nigeltao
CC=golang-dev
https://golang.org/cl/6452046
This commit is contained in:
Shenghou Ma 2012-07-31 23:02:46 -04:00
parent f2b8f6b451
commit e07958f7df
2 changed files with 74 additions and 4 deletions

View file

@ -469,10 +469,11 @@ void
runtime·equal(Type *t, ...)
{
byte *x, *y;
bool *ret;
uintptr ret;
x = (byte*)(&t+1);
y = x + t->size;
ret = (bool*)(y + t->size);
t->alg->equal(ret, t->size, x, y);
y = x + ROUND(t->size, t->align);
ret = (uintptr)(y + t->size);
ret = ROUND(ret, Structrnd);
t->alg->equal((bool*)ret, t->size, x, y);
}

69
test/fixedbugs/bug449.go Normal file
View file

@ -0,0 +1,69 @@
// runoutput
// 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.
// Issue 3866
// runtime.equal failed to take padding between arguments and
// return values into account, so in certain cases gc-generated
// code will read a random bool from the stack as the result of
// the comparison.
// This program generates a lot of equality tests and hopes to
// catch this.
// NOTE: this program assumes comparing instance of T and T's
// underlying []byte will make gc emit calls to runtime.equal,
// and if gc optimizes this case, then the test will no longer
// be correct (in the sense that it no longer tests runtime.equal).
package main
import (
"bytes"
"fmt"
"strconv"
"strings"
)
const ntest = 1024
func main() {
var decls, calls bytes.Buffer
for i := 1; i <= ntest; i++ {
s := strconv.Itoa(i)
decls.WriteString(strings.Replace(decl, "$", s, -1))
calls.WriteString(strings.Replace("call(test$)\n\t", "$", s, -1))
}
program = strings.Replace(program, "$DECLS", decls.String(), 1)
program = strings.Replace(program, "$CALLS", calls.String(), 1)
fmt.Print(program)
}
var program = `package main
var count int
func call(f func() bool) {
if f() {
count++
}
}
$DECLS
func main() {
$CALLS
if count != 0 {
println("failed", count, "case(s)")
}
}
`
const decl = `
type T$ [$]uint8
func test$() bool {
v := T${1}
return v == [$]uint8{2} || v != [$]uint8{1}
}`