[esnext] prototype runtime implementation for async functions

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/api-natives.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
@@ skipping 145 matching lines @@
   void CreateRoots();
   // Creates the empty function.  Used for creating a context from scratch.
   Handle<JSFunction> CreateEmptyFunction(Isolate* isolate);
   // Creates the ThrowTypeError function. ECMA 5th Ed. 13.2.3
   Handle<JSFunction> GetRestrictedFunctionPropertiesThrower();
   Handle<JSFunction> GetStrictArgumentsPoisonFunction();
   Handle<JSFunction> GetThrowTypeErrorIntrinsic(Builtins::Name builtin_name);
 
   void CreateStrictModeFunctionMaps(Handle<JSFunction> empty);
   void CreateIteratorMaps(Handle<JSFunction> empty);
+  void CreateAsyncFunctionMaps(Handle<JSFunction> empty);
   void CreateJSProxyMaps();
 
   // Make the "arguments" and "caller" properties throw a TypeError on access.
   void AddRestrictedFunctionProperties(Handle<Map> map);
 
   // Creates the global objects using the global proxy and the template passed
   // in through the API.  We call this regardless of whether we are building a
   // context from scratch or using a deserialized one from the partial snapshot
   // but in the latter case we don't use the objects it produces directly, as
   // we have to used the deserialized ones that are linked together with the
@@ skipping 623 matching lines @@
   native_context()->set_strict_generator_function_map(
       *strict_generator_function_map);
 
   Handle<JSFunction> object_function(native_context()->object_function());
   Handle<Map> generator_object_prototype_map = Map::Create(isolate(), 0);
   Map::SetPrototype(generator_object_prototype_map, generator_object_prototype);
   native_context()->set_generator_object_prototype_map(
       *generator_object_prototype_map);
 }
 
+void Genesis::CreateAsyncFunctionMaps(Handle<JSFunction> empty) {
+  // %AsyncFunctionPrototype% intrinsic
+  Handle<JSObject> async_function_prototype =
+      factory()->NewJSObject(isolate()->object_function(), TENURED);
+  SetObjectPrototype(async_function_prototype, empty);
+
+  JSObject::AddProperty(async_function_prototype,
+                        factory()->to_string_tag_symbol(),
+                        factory()->NewStringFromAsciiChecked("AsyncFunction"),
+                        static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
+
+  Handle<Map> strict_function_map(
+      native_context()->strict_function_without_prototype_map());
+  Handle<Map> sloppy_async_function_map =
+      Map::Copy(strict_function_map, "SloppyAsyncFunction");
+  sloppy_async_function_map->set_is_constructor(false);
+  Map::SetPrototype(sloppy_async_function_map, async_function_prototype);
+  native_context()->set_sloppy_async_function_map(*sloppy_async_function_map);
+
+  Handle<Map> strict_async_function_map =
+      Map::Copy(strict_function_map, "StrictAsyncFunction");
+  strict_async_function_map->set_is_constructor(false);
+  Map::SetPrototype(strict_async_function_map, async_function_prototype);
+  native_context()->set_strict_async_function_map(*strict_async_function_map);
+}
+
 void Genesis::CreateJSProxyMaps() {
   // Allocate the different maps for all Proxy types.
   // Next to the default proxy, we need maps indicating callable and
   // constructable proxies.
   Handle<Map> proxy_function_map =
       Map::Copy(isolate()->sloppy_function_without_prototype_map(), "Proxy");
   proxy_function_map->set_is_constructor(true);
   native_context()->set_proxy_function_map(*proxy_function_map);
 
   Handle<Map> proxy_map =
@@ skipping 1613 matching lines @@
     }
 
     Handle<AccessorInfo> script_is_embedder_debug_script =
         Accessors::ScriptIsEmbedderDebugScriptInfo(isolate, attribs);
     {
       AccessorConstantDescriptor d(
           Handle<Name>(Name::cast(script_is_embedder_debug_script->name())),
           script_is_embedder_debug_script, attribs);
       script_map->AppendDescriptor(&d);
     }
+
+    {
+      PrototypeIterator iter(native_context->sloppy_async_function_map());
+      Handle<JSObject> async_function_prototype(iter.GetCurrent<JSObject>());
+
+      static const bool kUseStrictFunctionMap = true;
+      Handle<JSFunction> async_function_constructor = InstallFunction(
+          container, "AsyncFunction", JS_FUNCTION_TYPE, JSFunction::kSize,
+          async_function_prototype, Builtins::kAsyncFunctionConstructor,
+          kUseStrictFunctionMap);
+      async_function_constructor->set_prototype_or_initial_map(
+          native_context->sloppy_async_function_map());
+      async_function_constructor->shared()->DontAdaptArguments();
+      async_function_constructor->shared()->set_construct_stub(
+          *isolate->builtins()->GeneratorFunctionConstructor());
+      async_function_constructor->shared()->set_length(1);
+      InstallWithIntrinsicDefaultProto(isolate, async_function_constructor,
+                                       Context::ASYNC_FUNCTION_FUNCTION_INDEX);
+
+      JSObject::AddProperty(
+          async_function_prototype, factory->constructor_string(),
+          async_function_constructor,
+          static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
+
+      JSFunction::SetPrototype(async_function_constructor,
+                               async_function_prototype);
+
+      Handle<JSFunction> async_function_next =
+          SimpleInstallFunction(container, "AsyncFunctionNext",
+                                Builtins::kAsyncFunctionNext, 2, false);
+      Handle<JSFunction> async_function_throw =
+          SimpleInstallFunction(container, "AsyncFunctionThrow",
+                                Builtins::kAsyncFunctionThrow, 2, false);
+      async_function_next->shared()->set_native(true);
+      async_function_throw->shared()->set_native(true);
+    }
   }
 }
 
 
 void Bootstrapper::ExportExperimentalFromRuntime(Isolate* isolate,
                                                  Handle<JSObject> container) {
   HandleScope scope(isolate);
 
 #define INITIALIZE_FLAG(FLAG)                                         \
   {                                                                   \
@@ skipping 600 matching lines @@
   static const char* harmony_object_own_property_descriptors_natives[] = {
       nullptr};
   static const char* harmony_array_prototype_values_natives[] = {nullptr};
   static const char* harmony_exponentiation_operator_natives[] = {nullptr};
   static const char* harmony_string_padding_natives[] = {
       "native harmony-string-padding.js", nullptr};
 #ifdef V8_I18N_SUPPORT
   static const char* icu_case_mapping_natives[] = {"native icu-case-mapping.js",
                                                    nullptr};
 #endif
-  static const char* harmony_async_await_natives[] = {nullptr};
+  static const char* harmony_async_await_natives[] = {
+      "native harmony-async-await.js", nullptr};
 
   for (int i = ExperimentalNatives::GetDebuggerCount();
        i < ExperimentalNatives::GetBuiltinsCount(); i++) {
 #define INSTALL_EXPERIMENTAL_NATIVES(id, desc)                                \
   if (FLAG_##id) {                                                            \
     for (size_t j = 0; id##_natives[j] != NULL; j++) {                        \
       Vector<const char> script_name = ExperimentalNatives::GetScriptName(i); \
       if (strncmp(script_name.start(), id##_natives[j],                       \
                   script_name.length()) == 0) {                               \
         if (!Bootstrapper::CompileExperimentalBuiltin(isolate(), i)) {        \
@@ skipping 575 matching lines @@
     HookUpGlobalProxy(global_object, global_proxy);
     HookUpGlobalObject(global_object);
 
     if (!ConfigureGlobalObjects(global_proxy_template)) return;
   } else {
     // We get here if there was no context snapshot.
     CreateRoots();
     Handle<JSFunction> empty_function = CreateEmptyFunction(isolate);
     CreateStrictModeFunctionMaps(empty_function);
     CreateIteratorMaps(empty_function);
+    CreateAsyncFunctionMaps(empty_function);
     Handle<JSGlobalObject> global_object =
         CreateNewGlobals(global_proxy_template, global_proxy);
     HookUpGlobalProxy(global_object, global_proxy);
     InitializeGlobal(global_object, empty_function, context_type);
     InitializeNormalizedMapCaches();
 
     if (!InstallNatives(context_type)) return;
 
     MakeFunctionInstancePrototypeWritable();
 
@@ skipping 62 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8