Simplify and compact transitions storage

src/transitions-inl.h

 // Copyright 2012 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.
 
 #ifndef V8_TRANSITIONS_INL_H_
 #define V8_TRANSITIONS_INL_H_
 
 #include "src/transitions.h"
 
 namespace v8 {
 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 IsFullTransitionArray() &&
-      get(kPrototypeTransitionsIndex) != Smi::FromInt(0);
+  return get(kPrototypeTransitionsIndex) != Smi::FromInt(0);
 }
 
 
 FixedArray* TransitionArray::GetPrototypeTransitions() {
-  DCHECK(IsFullTransitionArray());
+  DCHECK(HasPrototypeTransitions());  // Callers must check first.
   Object* prototype_transitions = get(kPrototypeTransitionsIndex);
   return FixedArray::cast(prototype_transitions);
 }
 
 
 void TransitionArray::SetPrototypeTransitions(FixedArray* transitions,
                                               WriteBarrierMode mode) {
-  DCHECK(IsFullTransitionArray());
   DCHECK(transitions->IsFixedArray());
-  Heap* heap = GetHeap();
-  WRITE_FIELD(this, kPrototypeTransitionsOffset, transitions);
-  CONDITIONAL_WRITE_BARRIER(
-      heap, this, kPrototypeTransitionsOffset, transitions, mode);
+  set(kPrototypeTransitionsIndex, transitions, mode);
 }
 
 
 Object** TransitionArray::GetPrototypeTransitionsSlot() {
-  return HeapObject::RawField(reinterpret_cast<HeapObject*>(this),
-                              kPrototypeTransitionsOffset);
+  return RawFieldOfElementAt(kPrototypeTransitionsIndex);
 }
 
 
 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);
 }
 
 
 #ifdef DEBUG
 bool TransitionArray::IsSpecialTransition(Name* name) {
   if (!name->IsSymbol()) return false;
   Heap* heap = name->GetHeap();
   return name == heap->nonextensible_symbol() ||
          name == heap->sealed_symbol() || name == heap->frozen_symbol() ||
@@ skipping 56 matching lines @@
                                                    Name* key,
                                                    Map* target) {
   FixedArray::NoIncrementalWriteBarrierSet(
       this, ToKeyIndex(transition_number), key);
   FixedArray::NoIncrementalWriteBarrierSet(
       this, ToTargetIndex(transition_number), target);
 }
 
 
 void TransitionArray::SetNumberOfTransitions(int number_of_transitions) {
-  if (IsFullTransitionArray()) {
-    DCHECK(number_of_transitions <= number_of_transitions_storage());
-    WRITE_FIELD(this, kTransitionLengthOffset,
-                Smi::FromInt(number_of_transitions));
-  }
+  DCHECK(number_of_transitions <= Capacity(this));
+  set(kTransitionLengthIndex, Smi::FromInt(number_of_transitions));
 }
 
-
-#undef FIELD_ADDR
-#undef WRITE_FIELD
-#undef CONDITIONAL_WRITE_BARRIER
-
-
 } }  // namespace v8::internal
 
 #endif  // V8_TRANSITIONS_INL_H_