Move package sync to third_party

PiperOrigin-RevId: 231889261
Change-Id: I482f1df055bcedf4edb9fe3fe9b8e9c80085f1a0

1 files changed, 23 insertions, 0 deletions

diff --git a/third_party/gvsync/memmove_unsafe.go b/third_party/gvsync/memmove_unsafe.go
new file mode 100644
index 000000000..d483fc739
--- /dev/null
+++ b/third_party/gvsync/memmove_unsafe.go
@@ -0,0 +1,23 @@
+// Copyright 2019 Google LLC
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gvsync
+
+import (
+	"unsafe"
+)
+
+// Memmove is exported for SeqAtomicLoad/SeqAtomicTryLoad<T>, which can't
+// define it because go_generics can't update the go:linkname annotation.
+// Furthermore, go:linkname silently doesn't work if the local name is exported
+// (this is of course undocumented), which is why this indirection is
+// necessary.
+func Memmove(to, from unsafe.Pointer, n uintptr) {
+	memmove(to, from, n)
+}
+
+//go:linkname memmove runtime.memmove
+//go:noescape
+func memmove(to, from unsafe.Pointer, n uintptr)