Improved function entry hook coverage

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
old mode 100644
new mode 100755
index 76a5a41e70ab0b32502d10a5c9ed37ad22789985..99e4315863dedb45dcfb6b5132efddc1636e1935
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -549,7 +549,7 @@ class Isolate {
   }
   Context** context_address() { return &thread_local_top_.context_; }
 
-  SaveContext* save_context() {return thread_local_top_.save_context_; }
+  SaveContext* save_context() { return thread_local_top_.save_context_; }
   void set_save_context(SaveContext* save) {
     thread_local_top_.save_context_ = save;
   }
@@ -1053,6 +1053,8 @@ class Isolate {
     context_exit_happened_ = context_exit_happened;
   }
 
+  bool initialized_from_snapshot() { return initialized_from_snapshot_; }
+
   double time_millis_since_init() {
     return OS::TimeCurrentMillis() - time_millis_at_init_;
   }
@@ -1110,6 +1112,16 @@ class Isolate {
   HStatistics* GetHStatistics();
   HTracer* GetHTracer();
 
+  bool HasFunctionEntryHook() {
+    return function_entry_hook_ != NULL &&
+        function_entry_hook_ != NullFunctionEntryHook;
+  }
+  FunctionEntryHook GetFunctionEntryHook();
+  void SetFunctionEntryHook(FunctionEntryHook function_entry_hook);
+  FunctionEntryHook* function_entry_hook_location() {
+    return &function_entry_hook_;
+  }
+
  private:
   Isolate();
 
@@ -1190,6 +1202,12 @@ class Isolate {
   static void SetIsolateThreadLocals(Isolate* isolate,
                                      PerIsolateThreadData* data);
 
+  // This function is used as a NULL sentry for the function entry point
+  // callback. This allows shutting callbacks off per-isolate, even after
+  // callbacks have been emitted into stubs and functions.
+  static void NullFunctionEntryHook(uintptr_t function,
+                                    uintptr_t return_addr_location);
+
   // Allocate and insert PerIsolateThreadData into the ThreadDataTable
   // (regardless of whether such data already exists).
   PerIsolateThreadData* AllocatePerIsolateThreadData(ThreadId thread_id);
@@ -1292,6 +1310,9 @@ class Isolate {
   // that a context was recently exited.
   bool context_exit_happened_;
 
+  // True if this isolate was initialized from a snapshot.
+  bool initialized_from_snapshot_;
+
   // Time stamp at initialization.
   double time_millis_at_init_;
 
@@ -1315,6 +1336,7 @@ class Isolate {
 #endif
   CpuProfiler* cpu_profiler_;
   HeapProfiler* heap_profiler_;
+  FunctionEntryHook function_entry_hook_;
 
 #define GLOBAL_BACKING_STORE(type, name, initialvalue)                         \
   type name##_;