Store JSGlobalProxy's identity hash directly on the proxy itself

src/factory.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "factory.h"
 
 #include "conversions.h"
 #include "isolate-inl.h"
 #include "macro-assembler.h"
 
@@ skipping 1758 matching lines @@
         object->address() + map->instance_size(), size_difference);
   }
 }
 
 
 void Factory::ReinitializeJSGlobalProxy(Handle<JSGlobalProxy> object,
                                         Handle<JSFunction> constructor) {
   ASSERT(constructor->has_initial_map());
   Handle<Map> map(constructor->initial_map(), isolate());
 
+  // The proxy's hash should be retained across reinitialization.
+  Handle<Object> hash(object->hash(), isolate());
+
   // Check that the already allocated object has the same size and type as
   // objects allocated using the constructor.
   ASSERT(map->instance_size() == object->map()->instance_size());
   ASSERT(map->instance_type() == object->map()->instance_type());
 
   // Allocate the backing storage for the properties.
   int prop_size = map->InitialPropertiesLength();
   Handle<FixedArray> properties = NewFixedArray(prop_size, TENURED);
 
   // In order to keep heap in consistent state there must be no allocations
   // before object re-initialization is finished.
   DisallowHeapAllocation no_allocation;
 
   // Reset the map for the object.
   object->set_map(constructor->initial_map());
 
   Heap* heap = isolate()->heap();
   // Reinitialize the object from the constructor map.
   heap->InitializeJSObjectFromMap(*object, *properties, *map);
+
+  // Restore the saved hash.
+  object->set_hash(*hash);
 }
 
 
 void Factory::BecomeJSObject(Handle<JSReceiver> object) {
   ReinitializeJSReceiver(object, JS_OBJECT_TYPE, JSObject::kHeaderSize);
 }
 
 
 void Factory::BecomeJSFunction(Handle<JSReceiver> object) {
   ReinitializeJSReceiver(object, JS_FUNCTION_TYPE, JSFunction::kSize);
@@ skipping 541 matching lines @@
   return Handle<Object>::null();
 }
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return value ? true_value() : false_value();
 }
 
 
 } }  // namespace v8::internal