Fix braindead Handle::is_identical_to

src/handles-inl.h

 // Copyright 2006-2008 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 36 matching lines @@
 template<typename T>
 Handle<T>::Handle(T* obj, Isolate* isolate) {
   ASSERT(!obj->IsFailure());
   location_ = HandleScope::CreateHandle(isolate, obj);
 }
 
 
 template <typename T>
 inline bool Handle<T>::is_identical_to(const Handle<T> other) const {
   ASSERT(location_ == NULL ||
          reinterpret_cast<Address>(*location_) != kZapValue);

[Michael Starzinger, 2013/05/07 11:58:37]

As discussed offline: This should actually check against kHandleZapValue here.
Let's change it to catch all failures (i.e. with IsFailure).

[rossberg, 2013/05/07 12:00:25]

Done (here and elsewhere).

+  if (location_ == other.location_) return true;
+  if (location_ == NULL || other.location_ == NULL) return false;
   // Dereferencing deferred handles to check object equality is safe.
   SLOW_ASSERT(IsDereferenceAllowed(true) && other.IsDereferenceAllowed(true));
   return *location_ == *other.location_;
 }
 
 
 template <typename T>
 inline T* Handle<T>::operator*() const {
   ASSERT(location_ != NULL);
   ASSERT(reinterpret_cast<Address>(*location_) != kHandleZapValue);
   SLOW_ASSERT(IsDereferenceAllowed(false));
   return *BitCast<T**>(location_);
 }
 
 template <typename T>
 inline T** Handle<T>::location() const {
   ASSERT(location_ == NULL ||
          reinterpret_cast<Address>(*location_) != kZapValue);
-  SLOW_ASSERT(IsDereferenceAllowed(false));
+  SLOW_ASSERT(location_ == NULL || IsDereferenceAllowed(false));
   return location_;
 }
 
 #ifdef DEBUG
 template <typename T>
 bool Handle<T>::IsDereferenceAllowed(bool allow_deferred) const {
-  if (location_ == NULL) return true;
+  ASSERT(location_ != NULL);
   Object* object = *BitCast<T**>(location_);
   if (object->IsSmi()) return true;
   HeapObject* heap_object = HeapObject::cast(object);
   Isolate* isolate = heap_object->GetIsolate();
   Object** handle = reinterpret_cast<Object**>(location_);
   Object** roots_array_start = isolate->heap()->roots_array_start();
   if (roots_array_start <= handle &&
       handle < roots_array_start + Heap::kStrongRootListLength) {
     return true;
   }
@@ skipping 123 matching lines @@
 
 HandleDereferenceGuard::~HandleDereferenceGuard() {
   isolate_->SetHandleDereferenceGuardState(old_state_);
 }
 
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_INL_H_