TransitionArray now uses <is_data_property, name, attributes> tuple as a key, which allows to have …

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 {
@@ skipping 16 matching lines @@
   }
 
 
 TransitionArray* TransitionArray::cast(Object* object) {
   DCHECK(object->IsTransitionArray());
   return reinterpret_cast<TransitionArray*>(object);
 }
 
 
 bool TransitionArray::HasElementsTransition() {
-  return Search(GetHeap()->elements_transition_symbol()) != kNotFound;
+  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) {
@@ skipping 85 matching lines @@
   return map->GetLastDescriptorDetails();
 }
 
 
 Object* TransitionArray::GetTargetValue(int transition_number) {
   Map* map = GetTarget(transition_number);
   return map->instance_descriptors()->GetValue(map->LastAdded());
 }
 
 
-int TransitionArray::Search(Name* name, int* out_insertion_index) {
+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->frozen_symbol() ||
+         name == heap->elements_transition_symbol() ||
+         name == heap->observed_symbol();
+}
+#endif
+
+
+int TransitionArray::CompareKeys(Name* key1, uint32_t hash1,
+                                 bool is_data_property1,
+                                 PropertyAttributes attributes1, Name* key2,
+                                 uint32_t hash2, bool is_data_property2,
+                                 PropertyAttributes attributes2) {
+  int cmp = CompareNames(key1, hash1, key2, hash2);
+  if (cmp != 0) return cmp;
+
+  return CompareDetails(is_data_property1, attributes1, is_data_property2,
+                        attributes2);
+}
+
+
+int TransitionArray::CompareNames(Name* key1, uint32_t hash1, Name* key2,
+                                  uint32_t hash2) {
+  if (key1 != key2) {
+    // In case of hash collisions key1 is always "less" than key2.
+    return hash1 <= hash2 ? -1 : 1;
+  }
+
+  return 0;
+}
+
+
+int TransitionArray::CompareDetails(bool is_data_property1,
+                                    PropertyAttributes attributes1,
+                                    bool is_data_property2,
+                                    PropertyAttributes attributes2) {
+  if (is_data_property1 != is_data_property2) {
+    return static_cast<int>(is_data_property1) <
+                   static_cast<int>(is_data_property2)
+               ? -1
+               : 1;
+  }
+
+  if (attributes1 != attributes2) {
+    return static_cast<int>(attributes1) < static_cast<int>(attributes2) ? -1
+                                                                         : 1;
+  }
+
+  return 0;
+}
+
+
+PropertyDetails TransitionArray::GetTargetDetails(Name* name, Map* target) {
+  DCHECK(!IsSpecialTransition(name));
+  int descriptor = target->LastAdded();
+  DescriptorArray* descriptors = target->instance_descriptors();
+  if (!descriptors->GetKey(descriptor)->Equals(name)) {
+    descriptor = descriptors->SearchWithCache(name, target);
+    DCHECK_NE(kNotFound, descriptor);

[Toon Verwaest, 2014/11/04 10:50:50]

Mmh, this doesn't seem necessary. We shouldn't need to compare details ever when
you can't find it at the end. This is only true if you added a setter/getter to
an existing setter/getter. In such case, that's the only possible transition
under that name. If we are fetching such details, we're probably computing too
much stuff.

[Igor Sheludko, 2014/11/04 16:44:16]

Done. Now transitions always created for last added property. I had to disabl
the ability to reconfigure non-last accessor property. I'll address
reconfiguration in next CL.

+  }
+  return descriptors->GetDetails(descriptor);
+}
+
+
 void TransitionArray::NoIncrementalWriteBarrierSet(int transition_number,
                                                    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));
   }
 }
 
 
 #undef FIELD_ADDR
 #undef WRITE_FIELD
 #undef CONDITIONAL_WRITE_BARRIER
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TRANSITIONS_INL_H_