Reapply descriptor array sharing.

src/heap.cc

 // 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 2034 matching lines @@
   reinterpret_cast<Map*>(result)->set_map(raw_unchecked_meta_map());
   reinterpret_cast<Map*>(result)->set_instance_type(instance_type);
   reinterpret_cast<Map*>(result)->set_instance_size(instance_size);
   reinterpret_cast<Map*>(result)->set_visitor_id(
         StaticVisitorBase::GetVisitorId(instance_type, instance_size));
   reinterpret_cast<Map*>(result)->set_inobject_properties(0);
   reinterpret_cast<Map*>(result)->set_pre_allocated_property_fields(0);
   reinterpret_cast<Map*>(result)->set_unused_property_fields(0);
   reinterpret_cast<Map*>(result)->set_bit_field(0);
   reinterpret_cast<Map*>(result)->set_bit_field2(0);
-  reinterpret_cast<Map*>(result)->set_bit_field3(0);
+  int bit_field3 = Map::EnumLengthBits::encode(Map::kInvalidEnumCache) |
+                   Map::OwnsDescriptors::encode(true);
+  reinterpret_cast<Map*>(result)->set_bit_field3(bit_field3);
   return result;
 }
 
 
 MaybeObject* Heap::AllocateMap(InstanceType instance_type,
                                int instance_size,
                                ElementsKind elements_kind) {
   Object* result;
   MaybeObject* maybe_result = AllocateRawMap();
   if (!maybe_result->To(&result)) return maybe_result;
 
   Map* map = reinterpret_cast<Map*>(result);
   map->set_map_no_write_barrier(meta_map());
   map->set_instance_type(instance_type);
   map->set_visitor_id(
       StaticVisitorBase::GetVisitorId(instance_type, instance_size));
   map->set_prototype(null_value(), SKIP_WRITE_BARRIER);
   map->set_constructor(null_value(), SKIP_WRITE_BARRIER);
   map->set_instance_size(instance_size);
   map->set_inobject_properties(0);
   map->set_pre_allocated_property_fields(0);
   map->set_code_cache(empty_fixed_array(), SKIP_WRITE_BARRIER);
   map->init_back_pointer(undefined_value());
   map->set_unused_property_fields(0);
   map->set_bit_field(0);
   map->set_bit_field2(1 << Map::kIsExtensible);
-  int bit_field3 = Map::EnumLengthBits::encode(Map::kInvalidEnumCache);
+  int bit_field3 = Map::EnumLengthBits::encode(Map::kInvalidEnumCache) |
+                   Map::OwnsDescriptors::encode(true);
   map->set_bit_field3(bit_field3);
   map->set_elements_kind(elements_kind);
 
   // If the map object is aligned fill the padding area with Smi 0 objects.
   if (Map::kPadStart < Map::kSize) {
     memset(reinterpret_cast<byte*>(map) + Map::kPadStart - kHeapObjectTag,
            0,
            Map::kSize - Map::kPadStart);
   }
   return map;
@@ skipping 5023 matching lines @@
   }
 }
 
 
 void KeyedLookupCache::Clear() {
   for (int index = 0; index < kLength; index++) keys_[index].map = NULL;
 }
 
 
 void DescriptorLookupCache::Clear() {
-  for (int index = 0; index < kLength; index++) keys_[index].array = NULL;
+  for (int index = 0; index < kLength; index++) keys_[index].source = NULL;
 }
 
 
 #ifdef DEBUG
 void Heap::GarbageCollectionGreedyCheck() {
   ASSERT(FLAG_gc_greedy);
   if (isolate_->bootstrapper()->IsActive()) return;
   if (disallow_allocation_failure()) return;
   CollectGarbage(NEW_SPACE);
 }
@@ skipping 178 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   memcpy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   memcpy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal