Preallocate space in descriptor arrays.

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 1888 matching lines @@
 }
 
 
 bool DescriptorArray::IsEmpty() {
   ASSERT(length() >= kFirstIndex ||
          this == HEAP->empty_descriptor_array());
   return length() < kFirstIndex;
 }
 
 
+void DescriptorArray::SetNumberOfDescriptors(int number_of_descriptors) {
+  WRITE_FIELD(
+      this, kDescriptorLengthOffset, Smi::FromInt(number_of_descriptors));
+}
+
+
 // Perform a binary search in a fixed array. Low and high are entry indices. If
 // there are three entries in this array it should be called with low=0 and
 // high=2.
 template<typename T>
 int BinarySearch(T* array, String* name, int low, int high) {
   uint32_t hash = name->Hash();
   int limit = high;
 
   ASSERT(low <= high);
 
@@ skipping 212 matching lines @@
                                desc->GetKey());
   NoIncrementalWriteBarrierSet(this,
                                ToValueIndex(descriptor_number),
                                desc->GetValue());
   NoIncrementalWriteBarrierSet(this,
                                ToDetailsIndex(descriptor_number),
                                desc->GetDetails().AsSmi());
 }
 
 
+void DescriptorArray::Set(int descriptor_number, Descriptor* desc) {
+  // Range check.
+  ASSERT(descriptor_number < number_of_descriptors());
+  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 number_of_set_descriptors) {
-  int descriptor_number = number_of_set_descriptors;
+                             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();
 
   int insertion;
 
   for (insertion = descriptor_number; insertion > 0; --insertion) {
     String* key = GetSortedKey(insertion - 1);
     if (key->Hash() <= hash) break;
     SetSortedKey(insertion, GetSortedKeyIndex(insertion - 1));
   }
 
   SetSortedKey(insertion, descriptor_number);
 }
 
 
+void DescriptorArray::Append(Descriptor* desc) {
+  int descriptor_number = number_of_descriptors();
+  int enumeration_index = descriptor_number + 1;
+  SetNumberOfDescriptors(descriptor_number + 1);
+  desc->SetEnumerationIndex(enumeration_index);
+  Set(descriptor_number, desc);
+
+  uint32_t hash = desc->GetKey()->Hash();
+
+  int insertion;
+
+  for (insertion = descriptor_number; insertion > 0; --insertion) {
+    String* key = GetSortedKey(insertion - 1);
+    if (key->Hash() <= hash) break;
+    SetSortedKey(insertion, GetSortedKeyIndex(insertion - 1));
+  }
+
+  SetSortedKey(insertion, descriptor_number);
+}
+
+
 void DescriptorArray::SwapSortedKeys(int first, int second) {
   int first_key = GetSortedKeyIndex(first);
   SetSortedKey(first, GetSortedKeyIndex(second));
   SetSortedKey(second, first_key);
 }
 
 
 DescriptorArray::WhitenessWitness::WhitenessWitness(FixedArray* array)
     : marking_(array->GetHeap()->incremental_marking()) {
   marking_->EnterNoMarkingScope();
@@ skipping 1426 matching lines @@
   WRITE_FIELD(this, kTransitionsOrBackPointerOffset, back_pointer);
   CONDITIONAL_WRITE_BARRIER(
       heap, this, kTransitionsOrBackPointerOffset, back_pointer, mode);
 }
 
 
 void Map::AppendDescriptor(Descriptor* desc,
                            const DescriptorArray::WhitenessWitness& witness) {
   DescriptorArray* descriptors = instance_descriptors();
   int number_of_own_descriptors = NumberOfOwnDescriptors();
-  ASSERT(number_of_own_descriptors < descriptors->number_of_descriptors());
-  descriptors->Append(desc, witness, number_of_own_descriptors);
+  ASSERT(descriptors->number_of_descriptors() == number_of_own_descriptors);
+  descriptors->Append(desc, witness);
   SetNumberOfOwnDescriptors(number_of_own_descriptors + 1);
 }
 
 
 Object* Map::GetBackPointer() {
   Object* object = READ_FIELD(this, kTransitionsOrBackPointerOffset);
   if (object->IsDescriptorArray()) {
     return TransitionArray::cast(object)->back_pointer_storage();
   } else {
     ASSERT(object->IsMap() || object->IsUndefined());
@@ skipping 1883 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_