Add ReleaseStore function on OpenBSD.

src/platform-openbsd.cc

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 65 matching lines @@
   // Seed the random number generator.
   // Convert the current time to a 64-bit integer first, before converting it
   // to an unsigned. Going directly can cause an overflow and the seed to be
   // set to all ones. The seed will be identical for different instances that
   // call this setup code within the same millisecond.
   uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
   srandom(static_cast<unsigned int>(seed));
 }
 
 
+void OS::ReleaseStore(volatile AtomicWord* ptr, AtomicWord value) {
+  __asm__ __volatile__("" : : : "memory");
+  *ptr = value;
+}
+
+
 uint64_t OS::CpuFeaturesImpliedByPlatform() {
   return 0;  // OpenBSD runs on anything.
 }
 
 
 int OS::ActivationFrameAlignment() {
   // 16 byte alignment on OpenBSD
   return 16;
 }
 
@@ skipping 511 matching lines @@
   }
 
   // This sampler is no longer the active sampler.
   active_sampler_ = NULL;
   active_ = false;
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal