[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.h"
 #include "src/api-arguments.h"
 #include "src/api-natives.h"
 #include "src/base/once.h"
@@ skipping 2308 matching lines @@
 void Builtins::Generate_MathTrunc(compiler::CodeStubAssembler* assembler) {
   Generate_MathRoundingOperation(assembler,
                                  &compiler::CodeStubAssembler::Float64Trunc);
 }
 
 // -----------------------------------------------------------------------------
 // ES6 section 25.3 Generator Objects
 
 namespace {
 
+enum class ResumeType { Generator, Async };
+
 void Generate_GeneratorPrototypeResume(
     compiler::CodeStubAssembler* assembler,
-    JSGeneratorObject::ResumeMode resume_mode, char const* const method_name) {

[caitp (gmail), 2016/04/16 18:20:20]

None of these changes are really needed, admittedly. will probably remove these
before landing

+    JSGeneratorObject::ResumeMode resume_mode, char const* const method_name,
+    ResumeType type) {
   typedef compiler::CodeStubAssembler::Label Label;
   typedef compiler::Node Node;
 
-  Node* receiver = assembler->Parameter(0);
-  Node* value = assembler->Parameter(1);
-  Node* context = assembler->Parameter(4);
+  Node* receiver = nullptr;
+  Node* value = nullptr;
+  Node* context = nullptr;
   Node* zero = assembler->SmiConstant(Smi::FromInt(0));
 
+  switch (type) {
+    case ResumeType::Generator:
+      receiver = assembler->Parameter(0);
+      value = assembler->Parameter(1);
+      context = assembler->Parameter(4);
+      break;
+    case ResumeType::Async:
+      receiver = assembler->Parameter(1);
+      value = assembler->Parameter(2);
+      context = assembler->Parameter(5);
+      break;
+  }
+
   // Check if the {receiver} is actually a JSGeneratorObject.
   Label if_receiverisincompatible(assembler, Label::kDeferred);
-  assembler->GotoIf(assembler->WordIsSmi(receiver), &if_receiverisincompatible);
-  Node* receiver_instance_type = assembler->LoadInstanceType(receiver);
-  assembler->GotoUnless(assembler->Word32Equal(
-                            receiver_instance_type,
-                            assembler->Int32Constant(JS_GENERATOR_OBJECT_TYPE)),
-                        &if_receiverisincompatible);
+  if (type == ResumeType::Generator || FLAG_debug_code) {
+    assembler->GotoIf(assembler->WordIsSmi(receiver),
+                      &if_receiverisincompatible);
+    Node* receiver_instance_type = assembler->LoadInstanceType(receiver);
+    assembler->GotoUnless(assembler->Word32Equal(receiver_instance_type,
+                                                 assembler->Int32Constant(
+                                                     JS_GENERATOR_OBJECT_TYPE)),
+                          &if_receiverisincompatible);
+  }
 
   // Check if the {receiver} is running or already closed.
-  Node* receiver_continuation = assembler->LoadObjectField(
-      receiver, JSGeneratorObject::kContinuationOffset);
   Label if_receiverisclosed(assembler, Label::kDeferred),
       if_receiverisrunning(assembler, Label::kDeferred);
-  assembler->GotoIf(assembler->SmiEqual(receiver_continuation, zero),
-                    &if_receiverisclosed);
-  assembler->GotoIf(assembler->SmiLessThan(receiver_continuation, zero),
-                    &if_receiverisrunning);
+  if (type == ResumeType::Generator || FLAG_debug_code) {
+    Node* receiver_continuation = assembler->LoadObjectField(
+        receiver, JSGeneratorObject::kContinuationOffset);
+    assembler->GotoIf(assembler->SmiEqual(receiver_continuation, zero),
+                      &if_receiverisclosed);
+    assembler->GotoIf(assembler->SmiLessThan(receiver_continuation, zero),
+                      &if_receiverisrunning);
+  }
 
   // Resume the {receiver} using our trampoline.
   Node* result = assembler->CallStub(
       CodeFactory::ResumeGenerator(assembler->isolate()), context, value,
       receiver, assembler->SmiConstant(Smi::FromInt(resume_mode)));
   assembler->Return(result);
 
   assembler->Bind(&if_receiverisincompatible);
-  {
+  if (type == ResumeType::Generator || FLAG_debug_code) {
     // The {receiver} is not a valid JSGeneratorObject.
     Node* result = assembler->CallRuntime(
         Runtime::kThrowIncompatibleMethodReceiver, context,
         assembler->HeapConstant(assembler->factory()->NewStringFromAsciiChecked(
             method_name, TENURED)),
         receiver);
     assembler->Return(result);  // Never reached.
   }
 
-  assembler->Bind(&if_receiverisclosed);
-  {
+  if (type == ResumeType::Generator || FLAG_debug_code) {
+    assembler->Bind(&if_receiverisclosed);
     // The {receiver} is closed already.
     Node* result = nullptr;
     switch (resume_mode) {
       case JSGeneratorObject::kNext:
         result = assembler->CallRuntime(Runtime::kCreateIterResultObject,
                                         context, assembler->UndefinedConstant(),
                                         assembler->BooleanConstant(true));
         break;
       case JSGeneratorObject::kReturn:
         result =
             assembler->CallRuntime(Runtime::kCreateIterResultObject, context,
                                    value, assembler->BooleanConstant(true));
         break;
       case JSGeneratorObject::kThrow:
         result = assembler->CallRuntime(Runtime::kThrow, context, value);
         break;
     }
     assembler->Return(result);
   }
 
-  assembler->Bind(&if_receiverisrunning);
-  {
+  if (type == ResumeType::Generator || FLAG_debug_code) {
+    assembler->Bind(&if_receiverisrunning);
     Node* result =
         assembler->CallRuntime(Runtime::kThrowGeneratorRunning, context);
     assembler->Return(result);  // Never reached.
   }
 }
 
 }  // namespace
 
 // ES6 section 25.3.1.2 Generator.prototype.next ( value )
 void Builtins::Generate_GeneratorPrototypeNext(
     compiler::CodeStubAssembler* assembler) {
   Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kNext,
-                                    "[Generator].prototype.next");
+                                    "[Generator].prototype.next",
+                                    ResumeType::Generator);
 }
 
 // ES6 section 25.3.1.3 Generator.prototype.return ( value )
 void Builtins::Generate_GeneratorPrototypeReturn(
     compiler::CodeStubAssembler* assembler) {
   Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kReturn,
-                                    "[Generator].prototype.return");
+                                    "[Generator].prototype.return",
+                                    ResumeType::Generator);
 }
 
 // ES6 section 25.3.1.4 Generator.prototype.throw ( exception )
 void Builtins::Generate_GeneratorPrototypeThrow(
     compiler::CodeStubAssembler* assembler) {
   Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kThrow,
-                                    "[Generator].prototype.throw");
+                                    "[Generator].prototype.throw",
+                                    ResumeType::Generator);
+}
+
+void Builtins::Generate_AsyncFunctionNext(
+    compiler::CodeStubAssembler* assembler) {
+  Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kNext,
+                                    "[AsyncFunction].next", ResumeType::Async);
+}
+
+void Builtins::Generate_AsyncFunctionThrow(
+    compiler::CodeStubAssembler* assembler) {
+  Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kThrow,
+                                    "[AsyncFunction].throw", ResumeType::Async);
 }
 
 // -----------------------------------------------------------------------------
 // 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);
@@ skipping 2874 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