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// run
// Copyright 2018 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"
)
// linked list up the stack, to test lots of stack objects.
type T struct {
// points to a heap object. Test will make sure it isn't freed.
data *int64
// next pointer for a linked list of stack objects
next *T
// duplicate of next, to stress test the pointer buffers
// used during stack tracing.
next2 *T
}
func main() {
makelist(nil, 10000)
}
func makelist(x *T, n int64) {
if n%2 != 0 {
panic("must be multiple of 2")
}
if n == 0 {
runtime.GC()
i := int64(1)
for ; x != nil; x, i = x.next, i+1 {
// Make sure x.data hasn't been collected.
if got := *x.data; got != i {
panic(fmt.Sprintf("bad data want %d, got %d", i, got))
}
}
return
}
// Put 2 objects in each frame, to test intra-frame pointers.
// Use both orderings to ensure the linked list isn't always in address order.
var a, b T
if n%3 == 0 {
a.data = newInt(n)
a.next = x
a.next2 = x
b.data = newInt(n - 1)
b.next = &a
b.next2 = &a
x = &b
} else {
b.data = newInt(n)
b.next = x
b.next2 = x
a.data = newInt(n - 1)
a.next = &b
a.next2 = &b
x = &a
}
makelist(x, n-2)
}
// big enough and pointer-y enough to not be tinyalloc'd
type NotTiny struct {
n int64
p *byte
}
// newInt allocates n on the heap and returns a pointer to it.
func newInt(n int64) *int64 {
h := &NotTiny{n: n}
p := &h.n
escape = p
return p
}
var escape *int64