Sharing of descriptor arrays.

src/transitions-inl.h

 // Copyright 2012 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 65 matching lines @@
 void TransitionArray::set_elements_transition(Map* transition_map,
                                               WriteBarrierMode mode) {
   Heap* heap = GetHeap();
   WRITE_FIELD(this, kElementsTransitionOffset, transition_map);
   CONDITIONAL_WRITE_BARRIER(
       heap, this, kElementsTransitionOffset, transition_map, mode);
 }
 
 
 DescriptorArray* TransitionArray::descriptors() {
-  return DescriptorArray::cast(get(kDescriptorsIndex));
+  return DescriptorArray::cast(descriptors_pointer()->value());
 }
 
 
-void TransitionArray::set_descriptors(DescriptorArray* descriptors,
-                                      WriteBarrierMode mode) {
-  Heap* heap = GetHeap();
-  WRITE_FIELD(this, kDescriptorsOffset, descriptors);
-  CONDITIONAL_WRITE_BARRIER(
-      heap, this, kDescriptorsOffset, descriptors, mode);
+void TransitionArray::set_descriptors(DescriptorArray* descriptors) {
+  ASSERT(!this->descriptors()->IsDescriptorArray() ||
+         descriptors->number_of_descriptors() == 0 ||
+         descriptors->HasEnumCache() ||
+         !this->descriptors()->HasEnumCache());
+  descriptors_pointer()->set_value(descriptors);
 }
 
 
-Object** TransitionArray::GetDescriptorsSlot() {
-  return HeapObject::RawField(reinterpret_cast<HeapObject*>(this),
-                              kDescriptorsOffset);
+JSGlobalPropertyCell* TransitionArray::descriptors_pointer() {
+  return JSGlobalPropertyCell::cast(get(kDescriptorsPointerIndex));
 }
 
 
+void TransitionArray::set_descriptors_pointer(JSGlobalPropertyCell* pointer) {
+  set(kDescriptorsPointerIndex, pointer);
+}
+
+
 Object* TransitionArray::back_pointer_storage() {
   return get(kBackPointerStorageIndex);
 }
 
 
 void TransitionArray::set_back_pointer_storage(Object* back_pointer,
                                                WriteBarrierMode mode) {
   Heap* heap = GetHeap();
   WRITE_FIELD(this, kBackPointerStorageOffset, back_pointer);
   CONDITIONAL_WRITE_BARRIER(
@@ skipping 70 matching lines @@
 
 PropertyDetails TransitionArray::GetTargetDetails(int transition_number) {
   Map* map = GetTarget(transition_number);
   DescriptorArray* descriptors = map->instance_descriptors();
   int descriptor = map->LastAdded();
   return descriptors->GetDetails(descriptor);
 }
 
 
 int TransitionArray::Search(String* name) {
-  return internal::Search(this, name);
+  return internal::Search<ALL_ENTRIES>(this, name);
 }
 
 
 void TransitionArray::Set(int transition_number,
                           String* key,
                           Map* target,
                           const WhitenessWitness&) {
   NoIncrementalWriteBarrierSet(this,
                                ToKeyIndex(transition_number),
                                key);
   NoIncrementalWriteBarrierSet(this,
                                ToTargetIndex(transition_number),
                                target);
 }
 
 
 #undef FIELD_ADDR
 #undef WRITE_FIELD
 #undef CONDITIONAL_WRITE_BARRIER
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TRANSITIONS_INL_H_