Fix performance regressions due to lazy initialization.

src/platform-win32.cc

 // Copyright 2012 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 186 matching lines @@
 #endif  // _WIN64
 
 
 #define UNARY_MATH_FUNCTION(name, generator)             \
 static UnaryMathFunction fast_##name##_function = NULL;  \
 V8_DECLARE_ONCE(fast_##name##_init_once);                \
 void init_fast_##name##_function() {                     \
   fast_##name##_function = generator;                    \
 }                                                        \
 double fast_##name(double x) {                           \
-  CallOnce(&fast_##name##_init_once,                     \
-           &init_fast_##name##_function);                \
+  if (!fast_##name##_function ) {                        \
+    CallOnce(&fast_##name##_init_once,                   \
+             &init_fast_##name##_function);              \
+  }                                                      \
   return (*fast_##name##_function)(x);                   \
 }
 
 UNARY_MATH_FUNCTION(sin, CreateTranscendentalFunction(TranscendentalCache::SIN))
 UNARY_MATH_FUNCTION(cos, CreateTranscendentalFunction(TranscendentalCache::COS))
 UNARY_MATH_FUNCTION(tan, CreateTranscendentalFunction(TranscendentalCache::TAN))
 UNARY_MATH_FUNCTION(log, CreateTranscendentalFunction(TranscendentalCache::LOG))
 UNARY_MATH_FUNCTION(sqrt, CreateSqrtFunction())
 
 #undef MATH_FUNCTION
@@ skipping 1868 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal