mirror of
https://github.com/golang/go
synced 2024-11-05 11:56:12 -07:00
519b469795
If we don't mark them as needzero, we have a live pointer variable containing possible garbage, which will baffle the GC. Fixes #16249. Change-Id: I7c423ceaca199ddd46fc2c23e5965e7973f07584 Reviewed-on: https://go-review.googlesource.com/24715 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
59 lines
1.3 KiB
Go
59 lines
1.3 KiB
Go
// run
|
|
|
|
// 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.
|
|
|
|
// Liveness calculations were wrong for a result parameter pushed onto
|
|
// the heap in a function that used defer. Program would crash with
|
|
// runtime: bad pointer in frame main.A at 0xc4201e6838: 0x1
|
|
|
|
package main
|
|
|
|
import "errors"
|
|
|
|
var sink interface{}
|
|
|
|
//go:noinline
|
|
func f(err *error) {
|
|
if err != nil {
|
|
sink = err
|
|
}
|
|
}
|
|
|
|
//go:noinline
|
|
func A(n, m int64) (res int64, err error) {
|
|
defer f(&err) // output parameter's address escapes to a defer.
|
|
if n < 0 {
|
|
err = errors.New("No negative")
|
|
return
|
|
}
|
|
if n <= 1 {
|
|
res = n
|
|
return
|
|
}
|
|
res = B(m) // This call to B drizzles a little junk on the stack.
|
|
res, err = A(n-1, m)
|
|
res++
|
|
return
|
|
}
|
|
|
|
// B does a little bit of recursion dribbling not-zero onto the stack.
|
|
//go:noinline
|
|
func B(n int64) (res int64) {
|
|
if n <= 1 { // Prefer to leave a 1 on the stack.
|
|
return n
|
|
}
|
|
return 1 + B(n-1)
|
|
}
|
|
|
|
func main() {
|
|
x, e := A(0, 0)
|
|
for j := 0; j < 4; j++ { // j controls amount of B's stack dribble
|
|
for i := 0; i < 1000; i++ { // try more and more recursion until stack growth occurs in newobject in prologue
|
|
x, e = A(int64(i), int64(j))
|
|
}
|
|
}
|
|
_, _ = x, e
|
|
}
|