Disallow dereferencing deferred handles when generating optimized code.

src/handles.h

Index: src/handles.h
diff --git a/src/handles.h b/src/handles.h
index 8e9404cb9d105024578fa92b18e140a2a15d0dc0..e5a6c2796ec7c91204b7f688d49abbdd0ec88772 100644
--- a/src/handles.h
+++ b/src/handles.h
@@ -73,8 +73,8 @@ class Handle {
   INLINE(T** location() const);
 
   template <class S> static Handle<T> cast(Handle<S> that) {
-    T::cast(*that);
-    return Handle<T>(reinterpret_cast<T**>(that.location()));
+    T::cast(*reinterpret_cast<T**>(that.location_));
+    return Handle<T>(reinterpret_cast<T**>(that.location_));
   }
 
   static Handle<T> null() { return Handle<T>(); }
@@ -84,6 +84,10 @@ class Handle {
   // implementation in api.h.
   inline Handle<T> EscapeFrom(v8::HandleScope* scope);
 
+#ifdef DEBUG
+  bool IsDereferenceAllowed(bool allow_deferred) const;
+#endif  // DEBUG
+
  private:
   T** location_;
 
@@ -341,7 +345,7 @@ class NoHandleAllocation BASE_EMBEDDED {
 
 class HandleDereferenceGuard BASE_EMBEDDED {
  public:
-  enum State { ALLOW, DISALLOW };
+  enum State { ALLOW, DISALLOW, DISALLOW_DEFERRED };
 #ifndef DEBUG
   HandleDereferenceGuard(Isolate* isolate, State state) { }
   ~HandleDereferenceGuard() { }
@@ -350,10 +354,18 @@ class HandleDereferenceGuard BASE_EMBEDDED {
   inline ~HandleDereferenceGuard();
  private:
   Isolate* isolate_;
-  bool old_state_;
+  State old_state_;
 #endif
 };
 
+#ifdef DEBUG
+#define ALLOW_HANDLE_DEREF(why_this_is_safe)                                   \
+  HandleDereferenceGuard allow(Isolate::Current(),                             \

[Sven Panne, 2013/04/23 06:42:13]

Please do *not* introduce any new Isolate::Current() calls, this function is
really on death row. Adding another parameter to the macro is probably the
easiest way for this, the right Isolate is probably easily available at all call
sites, anyway.

+                               HandleDereferenceGuard::ALLOW);
+#else
+#define ALLOW_HANDLE_DEREF(why_this_is_safe)
+#endif  // DEBUG
+
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_H_