Keep prototype maps in dictionary mode until ICs see them

src/objects-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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 1094 matching lines @@
   LookupIterator it(isolate, object, index);
   MAYBE_RETURN_NULL(
       SetProperty(&it, value, language_mode, MAY_BE_STORE_FROM_KEYED));
   return value;
 }
 
 MaybeHandle<Object> JSReceiver::GetPrototype(Isolate* isolate,
                                              Handle<JSReceiver> receiver) {
   // We don't expect access checks to be needed on JSProxy objects.
   DCHECK(!receiver->IsAccessCheckNeeded() || receiver->IsJSObject());
-  PrototypeIterator iter(isolate, receiver,
-                         PrototypeIterator::START_AT_RECEIVER,
+  PrototypeIterator iter(isolate, receiver, kStartAtReceiver,
                          PrototypeIterator::END_AT_NON_HIDDEN);
   do {
     if (!iter.AdvanceFollowingProxies()) return MaybeHandle<Object>();
   } while (!iter.IsAtEnd());
   return PrototypeIterator::GetCurrent(iter);
 }
 
 MaybeHandle<Object> JSReceiver::GetProperty(Isolate* isolate,
                                             Handle<JSReceiver> receiver,
                                             const char* name) {
@@ skipping 3442 matching lines @@
 
 
 void Map::set_is_prototype_map(bool value) {
   set_bit_field2(IsPrototypeMapBits::update(bit_field2(), value));
 }
 
 bool Map::is_prototype_map() const {
   return IsPrototypeMapBits::decode(bit_field2());
 }
 
+bool Map::should_be_fast_prototype_map() const {
+  if (!prototype_info()->IsPrototypeInfo()) return false;
+  return PrototypeInfo::cast(prototype_info())->should_be_fast_map();
+}
 
 void Map::set_elements_kind(ElementsKind elements_kind) {
   DCHECK(static_cast<int>(elements_kind) < kElementsKindCount);
   DCHECK(kElementsKindCount <= (1 << Map::ElementsKindBits::kSize));
   set_bit_field2(Map::ElementsKindBits::update(bit_field2(), elements_kind));
   DCHECK(this->elements_kind() == elements_kind);
 }
 
 
 ElementsKind Map::elements_kind() {
@@ skipping 915 matching lines @@
 ACCESSORS(AccessorInfo, getter, Object, kGetterOffset)
 ACCESSORS(AccessorInfo, setter, Object, kSetterOffset)
 ACCESSORS(AccessorInfo, js_getter, Object, kJsGetterOffset)
 ACCESSORS(AccessorInfo, data, Object, kDataOffset)
 
 ACCESSORS(Box, value, Object, kValueOffset)
 
 ACCESSORS(PrototypeInfo, prototype_users, Object, kPrototypeUsersOffset)
 SMI_ACCESSORS(PrototypeInfo, registry_slot, kRegistrySlotOffset)
 ACCESSORS(PrototypeInfo, validity_cell, Object, kValidityCellOffset)
+SMI_ACCESSORS(PrototypeInfo, bit_field, kBitFieldOffset)
+BOOL_ACCESSORS(PrototypeInfo, bit_field, should_be_fast_map, kShouldBeFastBit)
 
 ACCESSORS(SloppyBlockWithEvalContextExtension, scope_info, ScopeInfo,
           kScopeInfoOffset)
 ACCESSORS(SloppyBlockWithEvalContextExtension, extension, JSObject,
           kExtensionOffset)
 
 ACCESSORS(AccessorPair, getter, Object, kGetterOffset)
 ACCESSORS(AccessorPair, setter, Object, kSetterOffset)
 
 ACCESSORS(AccessCheckInfo, named_callback, Object, kNamedCallbackOffset)
@@ skipping 2405 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_