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https://github.com/golang/go
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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
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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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// Liveness calculations were wrong for a result parameter pushed onto
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// the heap in a function that used defer. Program would crash with
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// runtime: bad pointer in frame main.A at 0xc4201e6838: 0x1
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package main
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import "errors"
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var sink interface{}
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//go:noinline
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func f(err *error) {
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if err != nil {
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sink = err
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}
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}
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//go:noinline
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func A(n, m int64) (res int64, err error) {
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defer f(&err) // output parameter's address escapes to a defer.
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if n < 0 {
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err = errors.New("No negative")
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return
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}
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if n <= 1 {
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res = n
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return
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}
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res = B(m) // This call to B drizzles a little junk on the stack.
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res, err = A(n-1, m)
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res++
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return
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}
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// B does a little bit of recursion dribbling not-zero onto the stack.
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//go:noinline
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func B(n int64) (res int64) {
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if n <= 1 { // Prefer to leave a 1 on the stack.
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return n
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}
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return 1 + B(n-1)
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}
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func main() {
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x, e := A(0, 0)
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for j := 0; j < 4; j++ { // j controls amount of B's stack dribble
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for i := 0; i < 1000; i++ { // try more and more recursion until stack growth occurs in newobject in prologue
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x, e = A(int64(i), int64(j))
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}
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}
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_, _ = x, e
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}
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