- Add AtomicOperations::CompareAndSwapWord

runtime/vm/atomic.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_ATOMIC_H_
 #define VM_ATOMIC_H_
 
+#include "platform/globals.h"
+
 #include "vm/allocation.h"
 
 namespace dart {
 
 class AtomicOperations : public AllStatic {
  public:
   // Atomically fetch the value at p and increment the value at p.
   // Returns the original value at p.
   static uintptr_t FetchAndIncrement(uintptr_t* p);
+
+  static uword CompareAndSwapWord(uword* ptr, uword old_value, uword new_value);
 };
 
 
 }  // namespace dart
 
+#if defined(TARGET_OS_ANDROID)
+#include "vm/atomic_android.h"
+#elif defined(TARGET_OS_LINUX)
+#include "vm/atomic_linux.h"
+#elif defined(TARGET_OS_MACOS)
+#include "vm/atomic_macos.h"
+#elif defined(TARGET_OS_WINDOWS)
+#include "vm/atomic_win.h"
+#else
+#error Unknown target os.
+#endif
+
 #endif  // VM_ATOMIC_H_