CPU profiler: make code events handling scalable.

src/platform-macos.cc

Index: src/platform-macos.cc
diff --git a/src/platform-macos.cc b/src/platform-macos.cc
index 23747c35f5335b068a291e32c3a0528e76403936..47193de7c40498815767e0c80a417e6a178c1408 100644
--- a/src/platform-macos.cc
+++ b/src/platform-macos.cc
@@ -39,6 +39,7 @@
 #include <pthread.h>
 #include <semaphore.h>
 #include <signal.h>
+#include <libkern/OSAtomic.h>
 #include <mach/mach.h>
 #include <mach/semaphore.h>
 #include <mach/task.h>
@@ -259,6 +260,12 @@ int OS::ActivationFrameAlignment() {
 }
 
 
+void OS::ReleaseStore(volatile AtomicWord* ptr, AtomicWord value) {
+  OSMemoryBarrier();
+  *ptr = value;
+}
+
+
 const char* OS::LocalTimezone(double time) {
   if (isnan(time)) return "";
   time_t tv = static_cast<time_t>(floor(time/msPerSecond));