Moving prototype transitions into the header of the transition array.

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 64 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);
 }
 
 
+bool TransitionArray::HasPrototypeTransitions() {
+  Object* prototype_transitions = get(kPrototypeTransitionsIndex);
+  return prototype_transitions != Smi::FromInt(0);
+}
+
+
+FixedArray* TransitionArray::prototype_transitions() {
+  Object* prototype_transitions = get(kPrototypeTransitionsIndex);
+  return FixedArray::cast(prototype_transitions);
+}
+
+
+HeapObject* TransitionArray::unchecked_prototype_transitions() {
+  Object* prototype_transitions = get(kPrototypeTransitionsIndex);
+  if (prototype_transitions == Smi::FromInt(0)) return NULL;
+  return reinterpret_cast<HeapObject*>(prototype_transitions);
+}
+
+
+void TransitionArray::set_prototype_transitions(FixedArray* transitions,
+                                                WriteBarrierMode mode) {
+  ASSERT(this != NULL);
+  ASSERT(transitions->IsFixedArray());
+  Heap* heap = GetHeap();
+  WRITE_FIELD(this, kPrototypeTransitionsOffset, transitions);
+  CONDITIONAL_WRITE_BARRIER(
+      heap, this, kPrototypeTransitionsOffset, transitions, mode);
+}
+
+
+Object** TransitionArray::GetPrototypeTransitionsSlot() {
+  return HeapObject::RawField(reinterpret_cast<HeapObject*>(this),
+                              kPrototypeTransitionsOffset);
+}
+
+
 Object** TransitionArray::GetKeySlot(int transition_number) {
   ASSERT(transition_number < number_of_transitions());
   return HeapObject::RawField(
       reinterpret_cast<HeapObject*>(this),
       OffsetOfElementAt(ToKeyIndex(transition_number)));
 }
 
 
 String* TransitionArray::GetKey(int transition_number) {
   ASSERT(transition_number < number_of_transitions());
@@ skipping 78 matching lines @@
 
 
 #undef FIELD_ADDR
 #undef WRITE_FIELD
 #undef CONDITIONAL_WRITE_BARRIER
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TRANSITIONS_INL_H_