Revert of Simplify and compact transitions storage

src/transitions-inl.h

Index: src/transitions-inl.h
diff --git a/src/transitions-inl.h b/src/transitions-inl.h
index f31eff96ba19e6e8e1dca0f1a4b3ee0c7c654a53..fd8eb8b0b652a463365591b3a0b7a9f00e3bb9a4 100644
--- a/src/transitions-inl.h
+++ b/src/transitions-inl.h
@@ -11,19 +11,55 @@
 namespace internal {
 
 
+#define FIELD_ADDR(p, offset) \
+  (reinterpret_cast<byte*>(p) + offset - kHeapObjectTag)
+
+#define WRITE_FIELD(p, offset, value) \
+  (*reinterpret_cast<Object**>(FIELD_ADDR(p, offset)) = value)
+
+#define CONDITIONAL_WRITE_BARRIER(heap, object, offset, value, mode)    \
+  if (mode == UPDATE_WRITE_BARRIER) {                                   \
+    heap->incremental_marking()->RecordWrite(                           \
+      object, HeapObject::RawField(object, offset), value);             \
+    if (heap->InNewSpace(value)) {                                      \
+      heap->RecordWrite(object->address(), offset);                     \
+    }                                                                   \
+  }
+
+
 TransitionArray* TransitionArray::cast(Object* object) {
   DCHECK(object->IsTransitionArray());
   return reinterpret_cast<TransitionArray*>(object);
 }
 
 
+bool TransitionArray::HasElementsTransition() {
+  return SearchSpecial(GetHeap()->elements_transition_symbol()) != kNotFound;
+}
+
+
+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(
+      heap, this, kBackPointerStorageOffset, back_pointer, mode);
+}
+
+
 bool TransitionArray::HasPrototypeTransitions() {
-  return get(kPrototypeTransitionsIndex) != Smi::FromInt(0);
+  return IsFullTransitionArray() &&
+      get(kPrototypeTransitionsIndex) != Smi::FromInt(0);
 }
 
 
 FixedArray* TransitionArray::GetPrototypeTransitions() {
-  DCHECK(HasPrototypeTransitions());  // Callers must check first.
+  DCHECK(IsFullTransitionArray());
   Object* prototype_transitions = get(kPrototypeTransitionsIndex);
   return FixedArray::cast(prototype_transitions);
 }
@@ -31,68 +67,88 @@
 
 void TransitionArray::SetPrototypeTransitions(FixedArray* transitions,
                                               WriteBarrierMode mode) {
+  DCHECK(IsFullTransitionArray());
   DCHECK(transitions->IsFixedArray());
-  set(kPrototypeTransitionsIndex, transitions, mode);
+  Heap* heap = GetHeap();
+  WRITE_FIELD(this, kPrototypeTransitionsOffset, transitions);
+  CONDITIONAL_WRITE_BARRIER(
+      heap, this, kPrototypeTransitionsOffset, transitions, mode);
 }
 
 
 Object** TransitionArray::GetPrototypeTransitionsSlot() {
-  return RawFieldOfElementAt(kPrototypeTransitionsIndex);
+  return HeapObject::RawField(reinterpret_cast<HeapObject*>(this),
+                              kPrototypeTransitionsOffset);
 }
 
 
 Object** TransitionArray::GetKeySlot(int transition_number) {
+  DCHECK(!IsSimpleTransition());
   DCHECK(transition_number < number_of_transitions());
   return RawFieldOfElementAt(ToKeyIndex(transition_number));
 }
 
 
 Name* TransitionArray::GetKey(int transition_number) {
+  if (IsSimpleTransition()) {
+    Map* target = GetTarget(kSimpleTransitionIndex);
+    int descriptor = target->LastAdded();
+    Name* key = target->instance_descriptors()->GetKey(descriptor);
+    return key;
+  }
   DCHECK(transition_number < number_of_transitions());
   return Name::cast(get(ToKeyIndex(transition_number)));
 }
 
 
-Name* TransitionArray::GetKey(Object* raw_transitions, int transition_number) {
-  if (IsSimpleTransition(raw_transitions)) {
-    DCHECK(transition_number == 0);
-    return GetSimpleTransitionKey(GetSimpleTransition(raw_transitions));
-  }
-  DCHECK(IsFullTransitionArray(raw_transitions));
-  return TransitionArray::cast(raw_transitions)->GetKey(transition_number);
-}
-
-
 void TransitionArray::SetKey(int transition_number, Name* key) {
+  DCHECK(!IsSimpleTransition());
   DCHECK(transition_number < number_of_transitions());
   set(ToKeyIndex(transition_number), key);
 }
 
 
 Map* TransitionArray::GetTarget(int transition_number) {
+  if (IsSimpleTransition()) {
+    DCHECK(transition_number == kSimpleTransitionIndex);
+    return Map::cast(get(kSimpleTransitionTarget));
+  }
   DCHECK(transition_number < number_of_transitions());
   return Map::cast(get(ToTargetIndex(transition_number)));
 }
 
 
-Map* TransitionArray::GetTarget(Object* raw_transitions,
-                                int transition_number) {
-  if (IsSimpleTransition(raw_transitions)) {
-    DCHECK(transition_number == 0);
-    return GetSimpleTransition(raw_transitions);
-  }
-  DCHECK(IsFullTransitionArray(raw_transitions));
-  return TransitionArray::cast(raw_transitions)->GetTarget(transition_number);
-}
-
-
 void TransitionArray::SetTarget(int transition_number, Map* value) {
+  if (IsSimpleTransition()) {
+    DCHECK(transition_number == kSimpleTransitionIndex);
+    return set(kSimpleTransitionTarget, value);
+  }
   DCHECK(transition_number < number_of_transitions());
   set(ToTargetIndex(transition_number), value);
 }
 
 
+PropertyDetails TransitionArray::GetTargetDetails(int transition_number) {
+  Map* map = GetTarget(transition_number);
+  return map->GetLastDescriptorDetails();
+}
+
+
+Object* TransitionArray::GetTargetValue(int transition_number) {
+  Map* map = GetTarget(transition_number);
+  return map->instance_descriptors()->GetValue(map->LastAdded());
+}
+
+
 int TransitionArray::SearchName(Name* name, int* out_insertion_index) {
+  if (IsSimpleTransition()) {
+    Name* key = GetKey(kSimpleTransitionIndex);
+    if (key->Equals(name)) return kSimpleTransitionIndex;
+    if (out_insertion_index != NULL) {
+      *out_insertion_index = key->Hash() > name->Hash() ? 0 : 1;
+    }
+    return kNotFound;
+  }
   return internal::Search<ALL_ENTRIES>(this, name, 0, out_insertion_index);
 }
 
@@ -169,9 +225,18 @@
 
 
 void TransitionArray::SetNumberOfTransitions(int number_of_transitions) {
-  DCHECK(number_of_transitions <= Capacity(this));
-  set(kTransitionLengthIndex, Smi::FromInt(number_of_transitions));
-}
+  if (IsFullTransitionArray()) {
+    DCHECK(number_of_transitions <= number_of_transitions_storage());
+    WRITE_FIELD(this, kTransitionLengthOffset,
+                Smi::FromInt(number_of_transitions));
+  }
+}
+
+
+#undef FIELD_ADDR
+#undef WRITE_FIELD
+#undef CONDITIONAL_WRITE_BARRIER
+
 
 } }  // namespace v8::internal