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// 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.
package main
import (
"fmt"
"runtime"
)
var sink *[20]byte
func f() (x [20]byte) {
// Initialize x.
for i := range x {
x[i] = byte(i)
}
// Force x to be allocated on the heap.
sink = &x
sink = nil
// Go to deferreturn after the panic below.
defer func() {
recover()
}()
// This call collects the heap-allocated version of x (oops!)
runtime.GC()
// Allocate that same object again and clobber it.
y := new([20]byte)
for i := 0; i < 20; i++ {
y[i] = 99
}
// Make sure y is heap allocated.
sink = y
panic(nil)
// After the recover we reach the deferreturn, which
// copies the heap version of x back to the stack.
// It gets the pointer to x from a stack slot that was
// not marked as live during the call to runtime.GC().
}
var sinkint int
func g(p *int) (x [20]byte) {
// Initialize x.
for i := range x {
x[i] = byte(i)
}
// Force x to be allocated on the heap.
sink = &x
sink = nil
// Go to deferreturn after the panic below.
defer func() {
recover()
}()
// This call collects the heap-allocated version of x (oops!)
runtime.GC()
// Allocate that same object again and clobber it.
y := new([20]byte)
for i := 0; i < 20; i++ {
y[i] = 99
}
// Make sure y is heap allocated.
sink = y
// panic with a non-call (with no fallthrough)
for {
sinkint = *p
}
// After the recover we reach the deferreturn, which
// copies the heap version of x back to the stack.
// It gets the pointer to x from a stack slot that was
// not marked as live during the call to runtime.GC().
}
func main() {
x := f()
for i, v := range x {
if v != byte(i) {
fmt.Printf("%v\n", x)
panic("bad f")
}
}
x = g(nil)
for i, v := range x {
if v != byte(i) {
fmt.Printf("%v\n", x)
panic("bad g")
}
}
}
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