Cheaper thread-safe atomic initialization of static references.

Source/wtf/Atomics.h

 /*
  * Copyright (C) 2007, 2008, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 125 matching lines @@
 #if defined(THREAD_SANITIZER)
 
 ALWAYS_INLINE void releaseStore(volatile int* ptr, int value)
 {
     __tsan_atomic32_store(ptr, value, __tsan_memory_order_release);
 }
 ALWAYS_INLINE void releaseStore(volatile unsigned* ptr, unsigned value)
 {
     __tsan_atomic32_store(reinterpret_cast<volatile int*>(ptr), static_cast<int>(value), __tsan_memory_order_release);
 }
+ALWAYS_INLINE void releaseStore(void* volatile* ptr, void* value)
+{
+#if CPU(64BIT)
+    __tsan_atomic64_store(reinterpret_cast<volatile long*>(ptr), reinterpret_cast<long>(value), __tsan_memory_order_release);
+#else
+    __tsan_atomic32_store(reinterpret_cast<volatile long*>(ptr), reinterpret_cast<long>(value), __tsan_memory_order_release);
+#endif
+}
 
 ALWAYS_INLINE int acquireLoad(volatile const int* ptr)
 {
     return __tsan_atomic32_load(ptr, __tsan_memory_order_acquire);
 }
 ALWAYS_INLINE unsigned acquireLoad(volatile const unsigned* ptr)
 {
     return static_cast<unsigned>(__tsan_atomic32_load(reinterpret_cast<volatile const int*>(ptr), __tsan_memory_order_acquire));
 }
 ALWAYS_INLINE unsigned long acquireLoad(volatile const unsigned long* ptr)
 {
 #if CPU(64BIT)
     return static_cast<unsigned long>(__tsan_atomic64_load(reinterpret_cast<volatile const long*>(ptr), __tsan_memory_order_acquire));
 #else
     return static_cast<unsigned long>(__tsan_atomic32_load(reinterpret_cast<volatile const long*>(ptr), __tsan_memory_order_acquire));
 #endif
 }
+ALWAYS_INLINE void* acquireLoad(void* volatile const* ptr)
+{
+#if CPU(64BIT)
+    return reinterpret_cast<void*>(__tsan_atomic64_load(reinterpret_cast<volatile const long*>(ptr), __tsan_memory_order_acquire));
+#else
+    return reinterpret_cast<void*>(__tsan_atomic32_load(reinterpret_cast<volatile const long*>(ptr), __tsan_memory_order_acquire));
+#endif
+}
 
 #else
 
 #if CPU(X86) || CPU(X86_64)
 // Only compiler barrier is needed.
 #if COMPILER(MSVC)
 // Starting from Visual Studio 2005 compiler guarantees acquire and release
 // semantics for operations on volatile variables. See MSDN entry for
 // MemoryBarrier macro.
 #define MEMORY_BARRIER()
@@ skipping 19 matching lines @@
 ALWAYS_INLINE void releaseStore(volatile int* ptr, int value)
 {
     MEMORY_BARRIER();
     *ptr = value;
 }
 ALWAYS_INLINE void releaseStore(volatile unsigned* ptr, unsigned value)
 {
     MEMORY_BARRIER();
     *ptr = value;
 }
+ALWAYS_INLINE void releaseStore(void* volatile* ptr, void* value)
+{
+    MEMORY_BARRIER();
+    *ptr = value;
+}
 
 ALWAYS_INLINE int acquireLoad(volatile const int* ptr)
 {
     int value = *ptr;
     MEMORY_BARRIER();
     return value;
 }
 ALWAYS_INLINE unsigned acquireLoad(volatile const unsigned* ptr)
 {
     unsigned value = *ptr;
     MEMORY_BARRIER();
     return value;
 }
 ALWAYS_INLINE unsigned long acquireLoad(volatile const unsigned long* ptr)
 {
     unsigned long value = *ptr;
     MEMORY_BARRIER();
     return value;
 }
 ALWAYS_INLINE unsigned long long acquireLoad(volatile const unsigned long long* ptr)
 {
     unsigned long long value = *ptr;
     MEMORY_BARRIER();
     return value;
 }
+ALWAYS_INLINE void* acquireLoad(void* volatile const* ptr)
+{
+    void* value = *ptr;
+    MEMORY_BARRIER();
+    return value;
+}
 
 #if defined(ADDRESS_SANITIZER)
 
 // FIXME: See comment on NO_SANITIZE_ADDRESS in platform/heap/AddressSanitizer.h
 #if !OS(WIN) || COMPILER(CLANG)
 #define NO_SANITIZE_ADDRESS_ATOMICS __attribute__((no_sanitize_address))
 #else
 #define NO_SANITIZE_ADDRESS_ATOMICS
 #endif
 
@@ skipping 43 matching lines @@
 using WTF::acquireLoad;
 using WTF::releaseStore;
 
 // These methods allow loading from and storing to poisoned memory. Only
 // use these methods if you know what you are doing since they will
 // silence use-after-poison errors from ASan.
 using WTF::asanUnsafeAcquireLoad;
 using WTF::asanUnsafeReleaseStore;
 
 #endif // Atomics_h