golang issue16515 代码
文件路径：/test/fixedbugs/issue16515.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.
/ issue 16515: spilled Duff-adjusted address may be invalid
package main
import "runtime"
type T [62]int / DUFFZERO with non-zero adjustment on AMD64
var sink interface{}
/go:noinline
func zero(x *T) {
/ Two DUFFZEROs on the same address with a function call in between.
/ Duff-adjusted address will be spilled and loaded
*x = T{} / DUFFZERO
runtime.GC()
(*x)[0] = 1
g() / call a function with large frame, trigger a stack move
*x = T{} / DUFFZERO again
}
/go:noinline
/ a function with large frame
func g() {
var x [1000]int
_ = x
}
func main() {
var s struct { a T; b [8192-62]int } / allocate 64K, hopefully it's in a new span and a few bytes before it is garbage
sink = &s / force heap allocation
s.a[0] = 2
zero(&s.a)
if s.a[0] != 0 {
println("s.a[0] =", s.a[0])
panic("zeroing failed")
}
var a T / on stack
a[0] = 2
zero(&a)
if a[0] != 0 {
println("a[0] =", a[0])
panic("zeroing failed")
}
}