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// 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 "unsafe"
var labelSync uintptr
//go:linkname runtime_setProfLabel runtime..z2fpprof.runtime_setProfLabel
func runtime_setProfLabel(labels unsafe.Pointer) {
// 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 = labels
}
//go:linkname runtime_getProfLabel runtime..z2fpprof.runtime_getProfLabel
func runtime_getProfLabel() unsafe.Pointer {
return getg().labels
}
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