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// run
// Copyright 2019 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 30977: write barrier call clobbers volatile
// value when there are multiple uses of the value.
package main
import "runtime"
type T struct {
a, b, c, d, e string
}
//go:noinline
func g() T {
return T{"a", "b", "c", "d", "e"}
}
//go:noinline
func f() {
// The compiler optimizes this to direct copying
// the call result to both globals, with write
// barriers. The first write barrier call clobbers
// the result of g on stack.
X = g()
Y = X
}
var X, Y T
const N = 1000
func main() {
// Keep GC running so the write barrier is on.
go func() {
for {
runtime.GC()
}
}()
for i := 0; i < N; i++ {
runtime.Gosched()
f()
if X != Y {
panic("FAIL")
}
}
}
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