[esnext] prototype runtime implementation for async functions

src/builtins.cc

 // 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.
 
 #include "src/builtins.h"
 
 #include "src/api-arguments.h"
 #include "src/api-natives.h"
 #include "src/api.h"
 #include "src/base/once.h"
@@ skipping 2460 matching lines @@
   Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kReturn,
                                     "[Generator].prototype.return");
 }
 
 // ES6 section 25.3.1.4 Generator.prototype.throw ( exception )
 void Builtins::Generate_GeneratorPrototypeThrow(CodeStubAssembler* assembler) {
   Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kThrow,
                                     "[Generator].prototype.throw");
 }
 
+void Builtins::Generate_AsyncFunctionNext(CodeStubAssembler* assembler) {
+  Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kNext,
+                                    "AsyncFunctionNext");
+}
+
+// ES6 section 25.3.1.4 Generator.prototype.throw ( exception )
+void Builtins::Generate_AsyncFunctionThrow(CodeStubAssembler* assembler) {
+  Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kThrow,
+                                    "AsyncFunctionThrow");
+}

[Dan Ehrenberg, 2016/05/04 22:52:36]

Just to make sure I understand, these are separate builtins just so they can be
marked native? Might be good to note in a comment, as our stack trace strategy
could change in the future as the implementation is changed for performance.

[Benedikt Meurer, 2016/05/05 19:04:45]

From my POV, these are separate primarily because they are a temporary
work-around to connect async function resume to promise.js. G.p.next and friends
are frontends for generators. This whole dance is just to find a non-intrusive
way for now to call the ResumeGenerator builtin from promise.js. So separation
helps us to easily remove these unnecessary indirections (also the driver
closures in async-await.js) once we're there.

+
 // -----------------------------------------------------------------------------
 // ES6 section 26.1 The Reflect Object
 
 // ES6 section 26.1.3 Reflect.defineProperty
 BUILTIN(ReflectDefineProperty) {
   HandleScope scope(isolate);
   DCHECK_EQ(4, args.length());
   Handle<Object> target = args.at<Object>(1);
   Handle<Object> key = args.at<Object>(2);
   Handle<Object> attributes = args.at<Object>(3);
@@ skipping 2965 matching lines @@
 BUILTIN_LIST_T(DEFINE_BUILTIN_ACCESSOR_T)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 #undef DEFINE_BUILTIN_ACCESSOR_T
 #undef DEFINE_BUILTIN_ACCESSOR_H
 
 }  // namespace internal
 }  // namespace v8