Add global setup for runtime profiler.

Whether it's enabled or not must not change while we're running. Let's
not waste time recomputing it. This also makes the VM state tracking
code slightly more lightweight.

Review URL: http://codereview.chromium.org/6825054

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7593 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime-profiler.cc

@@ -114,6 +114,11 @@ Atomic32 RuntimeProfiler::state_ = 0;
 Semaphore* RuntimeProfiler::semaphore_ = OS::CreateSemaphore(0);
 #endif
 
+#ifdef DEBUG
+bool RuntimeProfiler::has_been_globally_setup_ = false;
+#endif
+bool RuntimeProfiler::enabled_ = false;
+
 
 RuntimeProfiler::RuntimeProfiler(Isolate* isolate)
     : isolate_(isolate),
@@ -134,8 +139,12 @@ RuntimeProfiler::RuntimeProfiler(Isolate* isolate)
 }
 
 
-bool RuntimeProfiler::IsEnabled() {
-  return V8::UseCrankshaft() && FLAG_opt;
+void RuntimeProfiler::GlobalSetup() {
+  ASSERT(!has_been_globally_setup_);
+  enabled_ = V8::UseCrankshaft() && FLAG_opt;
+#ifdef DEBUG
+  has_been_globally_setup_ = true;
+#endif
 }
 
 
@@ -363,6 +372,7 @@ void RuntimeProfiler::NotifyTick() {
 
 
 void RuntimeProfiler::Setup() {
+  ASSERT(has_been_globally_setup_);
   ClearSampleBuffer();
   // If the ticker hasn't already started, make sure to do so to get
   // the ticks for the runtime profiler.

src/runtime-profiler.h

@@ -44,7 +44,12 @@ class RuntimeProfiler {
  public:
   explicit RuntimeProfiler(Isolate* isolate);
 
-  static bool IsEnabled();
+  static void GlobalSetup();
+
+  static inline bool IsEnabled() {
+    ASSERT(has_been_globally_setup_);
+    return enabled_;
+  }
 
   void OptimizeNow();
   void OptimizeSoon(JSFunction* function);
@@ -143,6 +148,11 @@ class RuntimeProfiler {
   //   0 or positive => the number of isolates running JavaScript code.
   static Atomic32 state_;
   static Semaphore* semaphore_;
+
+#ifdef DEBUG
+  static bool has_been_globally_setup_;
+#endif
+  static bool enabled_;
 };
 
 

src/v8.cc

@@ -204,6 +204,8 @@ void V8::InitializeOncePerProcess() {
     use_crankshaft_ = false;
   }
 
+  RuntimeProfiler::GlobalSetup();
+
   // Peephole optimization might interfere with deoptimization.
   FLAG_peephole_optimization = !use_crankshaft_;
 }