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go/test/escape_sync_atomic.go
Matthew Dempsky 9dce58d30d runtime/internal/atomic: remove bad go:noescape annotations on Loadp
The //go:noescape directive says that arguments don't leak at all,
which is too aggressive of a claim for functions that return pointers
derived from their parameters.

Remove the directive for now. Long term fix will require a new
directive that allows more fine-grained control over escape analysis
information supplied for functions implemented in assembly.

Also, update the BAD comments in the test cases for Loadp: we really
want that *ptr leaks to the result parameter, not that *ptr leaks to
the heap.

Updates #31525.

Change-Id: Ibfa61f2b70daa7ed3223056b57eeee777eef2e31
Reviewed-on: https://go-review.googlesource.com/c/go/+/172578
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
2019-04-17 19:09:15 +00:00

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Go

// errorcheck -0 -m -l
// 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.
// Test escape analysis for sync/atomic.
package escape
import (
"sync/atomic"
"unsafe"
)
// BAD: should be "leaking param: addr to result ~r1 level=1$".
func LoadPointer(addr *unsafe.Pointer) unsafe.Pointer { // ERROR "leaking param: addr$"
return atomic.LoadPointer(addr)
}
var ptr unsafe.Pointer
func StorePointer() {
var x int // ERROR "moved to heap: x"
atomic.StorePointer(&ptr, unsafe.Pointer(&x))
}
func SwapPointer() {
var x int // ERROR "moved to heap: x"
atomic.SwapPointer(&ptr, unsafe.Pointer(&x))
}
func CompareAndSwapPointer() {
// BAD: x doesn't need to be heap allocated
var x int // ERROR "moved to heap: x"
var y int // ERROR "moved to heap: y"
atomic.CompareAndSwapPointer(&ptr, unsafe.Pointer(&x), unsafe.Pointer(&y))
}