Remove descriptors pointer.

src/objects-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 2147 matching lines @@
   ASSERT(desc->GetDetails().descriptor_index() <=
          number_of_descriptors());
   ASSERT(desc->GetDetails().descriptor_index() > 0);
 
   set(ToKeyIndex(descriptor_number), desc->GetKey());
   set(ToValueIndex(descriptor_number), desc->GetValue());
   set(ToDetailsIndex(descriptor_number), desc->GetDetails().AsSmi());
 }
 
 
-void DescriptorArray::EraseDescriptor(Heap* heap, int descriptor_number) {
-  set_null_unchecked(heap, ToKeyIndex(descriptor_number));
-  set_null_unchecked(heap, ToValueIndex(descriptor_number));
-}
-
-
 void DescriptorArray::Append(Descriptor* desc,
                              const WhitenessWitness& witness) {
   int descriptor_number = number_of_descriptors();
   int enumeration_index = descriptor_number + 1;
   SetNumberOfDescriptors(descriptor_number + 1);
   desc->SetEnumerationIndex(enumeration_index);
   Set(descriptor_number, desc, witness);
 
   uint32_t hash = desc->GetKey()->Hash();
 
@@ skipping 1363 matching lines @@
 }
 
 
 void Map::set_prototype(Object* value, WriteBarrierMode mode) {
   ASSERT(value->IsNull() || value->IsJSReceiver());
   WRITE_FIELD(this, kPrototypeOffset, value);
   CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kPrototypeOffset, value, mode);
 }
 
 
-JSGlobalPropertyCell* Map::descriptors_pointer() {
-  ASSERT(HasTransitionArray());
-  return transitions()->descriptors_pointer();
-}
-
-
 DescriptorArray* Map::instance_descriptors() {
   if (HasTransitionArray()) return transitions()->descriptors();
   Object* back_pointer = GetBackPointer();
   if (!back_pointer->IsMap()) return GetHeap()->empty_descriptor_array();
   return Map::cast(back_pointer)->instance_descriptors();
 }
 
 
 enum TransitionsKind { DESCRIPTORS_HOLDER, FULL_TRANSITION_ARRAY };
 
 
 // If the descriptor is using the empty transition array, install a new empty
 // transition array that will have place for an element transition.
 static MaybeObject* EnsureHasTransitionArray(Map* map, TransitionsKind kind) {
   TransitionArray* transitions;
   MaybeObject* maybe_transitions;
-  if (map->HasTransitionArray()) {
-    if (kind != FULL_TRANSITION_ARRAY ||
-        map->transitions()->IsFullTransitionArray()) {
-      return map;
+  if (!map->HasTransitionArray()) {
+    if (kind == FULL_TRANSITION_ARRAY) {
+      maybe_transitions = TransitionArray::Allocate(0);
+    } else {
+      maybe_transitions = TransitionArray::AllocateDescriptorsHolder();
     }
+    if (!maybe_transitions->To(&transitions)) return maybe_transitions;
+    transitions->set_back_pointer_storage(map->GetBackPointer());
+  } else if (kind == FULL_TRANSITION_ARRAY &&
+             !map->transitions()->IsFullTransitionArray()) {
     maybe_transitions = map->transitions()->ExtendToFullTransitionArray();
     if (!maybe_transitions->To(&transitions)) return maybe_transitions;
   } else {
-    JSGlobalPropertyCell* pointer = map->RetrieveDescriptorsPointer();
-    if (kind == FULL_TRANSITION_ARRAY) {
-      maybe_transitions = TransitionArray::Allocate(0, pointer);
-    } else {
-      maybe_transitions = TransitionArray::AllocateDescriptorsHolder(pointer);
-    }
-    if (!maybe_transitions->To(&transitions)) return maybe_transitions;
-    transitions->set_back_pointer_storage(map->GetBackPointer());
+    return map;
   }
   map->set_transitions(transitions);
   return transitions;
 }
 
 
 MaybeObject* Map::SetDescriptors(DescriptorArray* value) {
   ASSERT(!is_shared());
   MaybeObject* maybe_failure =
       EnsureHasTransitionArray(this, DESCRIPTORS_HOLDER);
@@ skipping 89 matching lines @@
 
 
 bool Map::CanHaveMoreTransitions() {
   if (!HasTransitionArray()) return true;
   return FixedArray::SizeFor(transitions()->length() +
                              TransitionArray::kTransitionSize)
       <= Page::kMaxNonCodeHeapObjectSize;
 }
 
 
-JSGlobalPropertyCell* Map::RetrieveDescriptorsPointer() {
-  if (!owns_descriptors()) return NULL;
-  Object* back_pointer = GetBackPointer();
-  if (back_pointer->IsUndefined()) return NULL;
-  Map* map = Map::cast(back_pointer);
-  ASSERT(map->HasTransitionArray());
-  return map->transitions()->descriptors_pointer();
-}
-
-
 MaybeObject* Map::AddTransition(String* key,
                                 Map* target,
                                 SimpleTransitionFlag flag) {
   if (HasTransitionArray()) return transitions()->CopyInsert(key, target);
-  JSGlobalPropertyCell* descriptors_pointer = RetrieveDescriptorsPointer();
   return TransitionArray::NewWith(
-      flag, key, target, descriptors_pointer, GetBackPointer());
+      flag, key, target, instance_descriptors(), GetBackPointer());
 }
 
 
 void Map::SetTransition(int transition_index, Map* target) {
   transitions()->SetTarget(transition_index, target);
 }
 
 
 Map* Map::GetTransition(int transition_index) {
   return transitions()->GetTarget(transition_index);
 }
 
 
 MaybeObject* Map::set_elements_transition_map(Map* transitioned_map) {
+  DescriptorArray* descriptors = instance_descriptors();
   MaybeObject* allow_elements =
       EnsureHasTransitionArray(this, FULL_TRANSITION_ARRAY);
   if (allow_elements->IsFailure()) return allow_elements;
+  transitions()->set_descriptors(descriptors);
   transitions()->set_elements_transition(transitioned_map);
   return this;
 }
 
 
 FixedArray* Map::GetPrototypeTransitions() {
   if (!HasTransitionArray()) return GetHeap()->empty_fixed_array();
   if (!transitions()->HasPrototypeTransitions()) {
     return GetHeap()->empty_fixed_array();
   }
   return transitions()->GetPrototypeTransitions();
 }
 
 
 MaybeObject* Map::SetPrototypeTransitions(FixedArray* proto_transitions) {
+  DescriptorArray* descriptors = instance_descriptors();
   MaybeObject* allow_prototype =
       EnsureHasTransitionArray(this, FULL_TRANSITION_ARRAY);
   if (allow_prototype->IsFailure()) return allow_prototype;
 #ifdef DEBUG
   if (HasPrototypeTransitions()) {
     ASSERT(GetPrototypeTransitions() != proto_transitions);
     ZapPrototypeTransitions();
   }
 #endif
+  transitions()->set_descriptors(descriptors);
   transitions()->SetPrototypeTransitions(proto_transitions);
   return this;
 }
 
 
 bool Map::HasPrototypeTransitions() {
   return HasTransitionArray() && transitions()->HasPrototypeTransitions();
 }
 
 
@@ skipping 1793 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_