Copyright 2017 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 runtime

import 

var labelSync uintptr
go:linkname runtime_setProfLabel runtime/pprof.runtime_setProfLabel
Introduce race edge for read-back via profile. This would more properly use &getg().labels as the sync address, but we do the read in a signal handler and can't call the race runtime then. This uses racereleasemerge rather than just racerelease so the acquire in profBuf.read synchronizes with *all* prior setProfLabel operations, not just the most recent one. This is important because profBuf.read will observe different labels set by different setProfLabel operations on different goroutines, so it needs to synchronize with all of them (this wouldn't be an issue if we could synchronize on &getg().labels since we would synchronize with each most-recent labels write separately.) racereleasemerge is like a full read-modify-write on labelSync, rather than just a store-release, so it carries a dependency on the previous racereleasemerge, which ultimately carries forward to the acquire in profBuf.read.
	if raceenabled {
		racereleasemerge(unsafe.Pointer(&labelSync))
	}
	getg().labels = 
}
go:linkname runtime_getProfLabel runtime/pprof.runtime_getProfLabel
func () unsafe.Pointer {
	return getg().labels