Use the initial map of the Object function for empty object literals

src/bootstrapper.cc

 // Copyright 2014 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.
 
 #include "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
 #include "src/extensions/free-buffer-extension.h"
@@ skipping 465 matching lines @@
   // This map is installed in MakeFunctionInstancePrototypeWritable.
   sloppy_function_map_writable_prototype_ =
       CreateFunctionMap(FUNCTION_WITH_WRITEABLE_PROTOTYPE);
 
   Factory* factory = isolate->factory();
 
   Handle<String> object_name = factory->Object_string();
 
   {  // --- O b j e c t ---
     Handle<JSFunction> object_fun = factory->NewFunction(object_name);
+    int unused = JSObject::kInitialGlobalObjectUnusedPropertiesCount;
+    int instance_size = JSObject::kHeaderSize + kPointerSize * unused;
     Handle<Map> object_function_map =
-        factory->NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
+        factory->NewMap(JS_OBJECT_TYPE, instance_size);
+    object_function_map->set_inobject_properties(unused);
     JSFunction::SetInitialMap(object_fun, object_function_map,
                               isolate->factory()->null_value());
-    object_function_map->set_unused_property_fields(
-        JSObject::kInitialGlobalObjectUnusedPropertiesCount);
+    object_function_map->set_unused_property_fields(unused);
 
     native_context()->set_object_function(*object_fun);
 
     // Allocate a new prototype for the object function.
     Handle<JSObject> prototype = factory->NewJSObject(
         isolate->object_function(),
         TENURED);
     Handle<Map> map = Map::Copy(handle(prototype->map()));
     map->set_is_prototype_map(true);
     prototype->set_map(*map);
@@ skipping 644 matching lines @@
   InstallFunction(global, "Map", JS_MAP_TYPE, JSMap::kSize,
                   isolate->initial_object_prototype(), Builtins::kIllegal);
 
   // -- S e t
   InstallFunction(global, "Set", JS_SET_TYPE, JSSet::kSize,
                   isolate->initial_object_prototype(), Builtins::kIllegal);
 
   {  // Set up the iterator result object
     STATIC_ASSERT(JSGeneratorObject::kResultPropertyCount == 2);
     Handle<JSFunction> object_function(native_context()->object_function());
-    DCHECK(object_function->initial_map()->inobject_properties() == 0);
     Handle<Map> iterator_result_map =
         Map::Create(object_function, JSGeneratorObject::kResultPropertyCount);
-    DCHECK(iterator_result_map->inobject_properties() ==
-           JSGeneratorObject::kResultPropertyCount);
     Map::EnsureDescriptorSlack(iterator_result_map,
                                JSGeneratorObject::kResultPropertyCount);
 
     FieldDescriptor value_descr(factory->value_string(),
                                 JSGeneratorObject::kResultValuePropertyIndex,
                                 NONE, Representation::Tagged());
     iterator_result_map->AppendDescriptor(&value_descr);
 
     FieldDescriptor done_descr(factory->done_string(),
                                JSGeneratorObject::kResultDonePropertyIndex,
                                NONE, Representation::Tagged());
     iterator_result_map->AppendDescriptor(&done_descr);
 
+    iterator_result_map->set_instance_size(JSGeneratorObject::kResultSize);
     iterator_result_map->set_unused_property_fields(0);
+    iterator_result_map->set_inobject_properties(
+        JSGeneratorObject::kResultPropertyCount);
+    iterator_result_map->set_pre_allocated_property_fields(
+        JSGeneratorObject::kResultPropertyCount);
     DCHECK_EQ(JSGeneratorObject::kResultSize,
               iterator_result_map->instance_size());
     native_context()->set_iterator_result_map(*iterator_result_map);
   }
 
   // -- W e a k M a p
   InstallFunction(global, "WeakMap", JS_WEAK_MAP_TYPE, JSWeakMap::kSize,
                   isolate->initial_object_prototype(), Builtins::kIllegal);
   // -- W e a k S e t
   InstallFunction(global, "WeakSet", JS_WEAK_SET_TYPE, JSWeakSet::kSize,
@@ skipping 1544 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 } }  // namespace v8::internal