[stubs] Implement fast TF Builtin for Object.create

src/runtime/runtime-object.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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 189 matching lines @@
             ? index < static_cast<uint32_t>(String::cast(*object)->length())
             : key->Equals(isolate->heap()->length_string()));
   } else if (object->IsNull(isolate) || object->IsUndefined(isolate)) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewTypeError(MessageTemplate::kUndefinedOrNullToObject));
   }
 
   return isolate->heap()->false_value();
 }
 
+// ES6 section 19.1.2.2 Object.create ( O [ , Properties ] )
+// TODO(verwaest): Support the common cases with precached map directly in
+// an Object.create stub.
+RUNTIME_FUNCTION(Runtime_ObjectCreate) {
+  HandleScope scope(isolate);
+  Handle<Object> prototype = args.at<Object>(0);
+  if (!prototype->IsNull(isolate) && !prototype->IsJSReceiver()) {
+    THROW_NEW_ERROR_RETURN_FAILURE(
+        isolate, NewTypeError(MessageTemplate::kProtoObjectOrNull, prototype));
+  }
+
+  // Generate the map with the specified {prototype} based on the Object
+  // function's initial map from the current native context.
+  // TODO(bmeurer): Use a dedicated cache for Object.create; think about
+  // slack tracking for Object.create.
+  Handle<Map> map(isolate->native_context()->object_function()->initial_map(),
+                  isolate);
+  if (map->prototype() != *prototype) {
+    if (prototype->IsNull(isolate)) {
+      map = isolate->object_with_null_prototype_map();
+    } else if (prototype->IsJSObject()) {
+      Handle<JSObject> js_prototype = Handle<JSObject>::cast(prototype);
+      if (!js_prototype->map()->is_prototype_map()) {
+        JSObject::OptimizeAsPrototype(js_prototype, FAST_PROTOTYPE);
+      }
+      Handle<PrototypeInfo> info =
+          Map::GetOrCreatePrototypeInfo(js_prototype, isolate);
+      // TODO(verwaest): Use inobject slack tracking for this map.
+      if (info->HasObjectCreateMap()) {
+        map = handle(info->ObjectCreateMap(), isolate);
+      } else {
+        map = Map::CopyInitialMap(map);
+        Map::SetPrototype(map, prototype, FAST_PROTOTYPE);
+        PrototypeInfo::SetObjectCreateMap(info, map);
+      }
+    } else {
+      map = Map::TransitionToPrototype(map, prototype, REGULAR_PROTOTYPE);
+    }
+  }
+
+  // Actually allocate the object.
+  Handle<JSObject> object = isolate->factory()->NewJSObjectFromMap(map);
+
+  // Define the properties if properties was specified and is not undefined.
+  Handle<Object> properties = args.at<Object>(1);
+  if (!properties->IsUndefined(isolate)) {
+    RETURN_FAILURE_ON_EXCEPTION(
+        isolate, JSReceiver::DefineProperties(isolate, object, properties));
+  }
+
+  return *object;
+}
+
 MaybeHandle<Object> Runtime::SetObjectProperty(Isolate* isolate,
                                                Handle<Object> object,
                                                Handle<Object> key,
                                                Handle<Object> value,
                                                LanguageMode language_mode) {
   if (object->IsUndefined(isolate) || object->IsNull(isolate)) {
     THROW_NEW_ERROR(
         isolate,
         NewTypeError(MessageTemplate::kNonObjectPropertyStore, key, object),
         Object);
@@ skipping 662 matching lines @@
   if (!success) return isolate->heap()->exception();
   MAYBE_RETURN(
       JSReceiver::CreateDataProperty(&it, value, Object::THROW_ON_ERROR),
       isolate->heap()->exception());
   return *value;
 }
 
 
 }  // namespace internal
 }  // namespace v8