Minimize uses of lazy initialization by adding explicit initialization functions.

src/platform-macos.cc

Index: src/platform-macos.cc
diff --git a/src/platform-macos.cc b/src/platform-macos.cc
index dbcd80e9f21222faab02df1aab68f3958f7b27f4..afcd80affff3812b0622e6735c118b2a811e1870 100644
--- a/src/platform-macos.cc
+++ b/src/platform-macos.cc
@@ -94,18 +94,8 @@ double ceiling(double x) {
 static Mutex* limit_mutex = NULL;
 
 
-void OS::SetUp() {
-  // Seed the random number generator. We preserve microsecond resolution.
-  uint64_t seed = Ticks() ^ (getpid() << 16);
-  srandom(static_cast<unsigned int>(seed));
-  limit_mutex = CreateMutex();
-}
-
-
 void OS::PostSetUp() {
-  // Math functions depend on CPU features therefore they are initialized after
-  // CPU.
-  MathSetup();
+  POSIXPostSetUp();
 }
 
 
@@ -753,8 +743,14 @@ class SamplerThread : public Thread {
       : Thread(Thread::Options("SamplerThread", kSamplerThreadStackSize)),
         interval_(interval) {}
 
+  static void SetUp() {
+    if (!mutex_) {
+      mutex_ = OS::CreateMutex();
+    }
+  }
+
   static void AddActiveSampler(Sampler* sampler) {
-    ScopedLock lock(mutex_.Pointer());
+    ScopedLock lock(mutex_);
     SamplerRegistry::AddActiveSampler(sampler);
     if (instance_ == NULL) {
       instance_ = new SamplerThread(sampler->interval());
@@ -765,7 +761,7 @@ class SamplerThread : public Thread {
   }
 
   static void RemoveActiveSampler(Sampler* sampler) {
-    ScopedLock lock(mutex_.Pointer());
+    ScopedLock lock(mutex_);
     SamplerRegistry::RemoveActiveSampler(sampler);
     if (SamplerRegistry::GetState() == SamplerRegistry::HAS_NO_SAMPLERS) {
       RuntimeProfiler::StopRuntimeProfilerThreadBeforeShutdown(instance_);
@@ -862,7 +858,7 @@ class SamplerThread : public Thread {
   RuntimeProfilerRateLimiter rate_limiter_;
 
   // Protects the process wide state below.
-  static LazyMutex mutex_;
+  static Mutex* mutex_;
   static SamplerThread* instance_;
 
  private:
@@ -872,10 +868,19 @@ class SamplerThread : public Thread {
 #undef REGISTER_FIELD
 
 
-LazyMutex SamplerThread::mutex_ = LAZY_MUTEX_INITIALIZER;
+Mutex* SamplerThread::mutex_ = NULL;
 SamplerThread* SamplerThread::instance_ = NULL;
 
 
+void OS::SetUp() {
+  // Seed the random number generator. We preserve microsecond resolution.
+  uint64_t seed = Ticks() ^ (getpid() << 16);
+  srandom(static_cast<unsigned int>(seed));
+  limit_mutex = CreateMutex();
+  SamplerThread::SetUp();
+}
+
+
 Sampler::Sampler(Isolate* isolate, int interval)
     : isolate_(isolate),
       interval_(interval),