1 files changed, 114 insertions, 0 deletions
diff --git a/src/runtime/atomic_pointer.go b/src/runtime/atomic_pointer.go
new file mode 100644
index 0000000..b61bf0b
--- /dev/null
+++ b/src/runtime/atomic_pointer.go
@@ -0,0 +1,114 @@
+// Copyright 2009 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 (
+	"internal/goexperiment"
+	"runtime/internal/atomic"
+	"unsafe"
+)
+
+// These functions cannot have go:noescape annotations,
+// because while ptr does not escape, new does.
+// If new is marked as not escaping, the compiler will make incorrect
+// escape analysis decisions about the pointer value being stored.
+
+// atomicwb performs a write barrier before an atomic pointer write.
+// The caller should guard the call with "if writeBarrier.enabled".
+//
+//go:nosplit
+func atomicwb(ptr *unsafe.Pointer, new unsafe.Pointer) {
+	slot := (*uintptr)(unsafe.Pointer(ptr))
+	buf := getg().m.p.ptr().wbBuf.get2()
+	buf[0] = *slot
+	buf[1] = uintptr(new)
+}
+
+// atomicstorep performs *ptr = new atomically and invokes a write barrier.
+//
+//go:nosplit
+func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer) {
+	if writeBarrier.enabled {
+		atomicwb((*unsafe.Pointer)(ptr), new)
+	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite((*unsafe.Pointer)(ptr), new)
+	}
+	atomic.StorepNoWB(noescape(ptr), new)
+}
+
+// atomic_storePointer is the implementation of runtime/internal/UnsafePointer.Store
+// (like StoreNoWB but with the write barrier).
+//
+//go:nosplit
+//go:linkname atomic_storePointer runtime/internal/atomic.storePointer
+func atomic_storePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
+	atomicstorep(unsafe.Pointer(ptr), new)
+}
+
+// atomic_casPointer is the implementation of runtime/internal/UnsafePointer.CompareAndSwap
+// (like CompareAndSwapNoWB but with the write barrier).
+//
+//go:nosplit
+//go:linkname atomic_casPointer runtime/internal/atomic.casPointer
+func atomic_casPointer(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
+	if writeBarrier.enabled {
+		atomicwb(ptr, new)
+	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite(ptr, new)
+	}
+	return atomic.Casp1(ptr, old, new)
+}
+
+// Like above, but implement in terms of sync/atomic's uintptr operations.
+// We cannot just call the runtime routines, because the race detector expects
+// to be able to intercept the sync/atomic forms but not the runtime forms.
+
+//go:linkname sync_atomic_StoreUintptr sync/atomic.StoreUintptr
+func sync_atomic_StoreUintptr(ptr *uintptr, new uintptr)
+
+//go:linkname sync_atomic_StorePointer sync/atomic.StorePointer
+//go:nosplit
+func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
+	if writeBarrier.enabled {
+		atomicwb(ptr, new)
+	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite(ptr, new)
+	}
+	sync_atomic_StoreUintptr((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
+}
+
+//go:linkname sync_atomic_SwapUintptr sync/atomic.SwapUintptr
+func sync_atomic_SwapUintptr(ptr *uintptr, new uintptr) uintptr
+
+//go:linkname sync_atomic_SwapPointer sync/atomic.SwapPointer
+//go:nosplit
+func sync_atomic_SwapPointer(ptr *unsafe.Pointer, new unsafe.Pointer) unsafe.Pointer {
+	if writeBarrier.enabled {
+		atomicwb(ptr, new)
+	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite(ptr, new)
+	}
+	old := unsafe.Pointer(sync_atomic_SwapUintptr((*uintptr)(noescape(unsafe.Pointer(ptr))), uintptr(new)))
+	return old
+}
+
+//go:linkname sync_atomic_CompareAndSwapUintptr sync/atomic.CompareAndSwapUintptr
+func sync_atomic_CompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool
+
+//go:linkname sync_atomic_CompareAndSwapPointer sync/atomic.CompareAndSwapPointer
+//go:nosplit
+func sync_atomic_CompareAndSwapPointer(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
+	if writeBarrier.enabled {
+		atomicwb(ptr, new)
+	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite(ptr, new)
+	}
+	return sync_atomic_CompareAndSwapUintptr((*uintptr)(noescape(unsafe.Pointer(ptr))), uintptr(old), uintptr(new))
+}