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      1 // Copyright 2016 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "src/builtins/builtins.h"
      6 #include "src/builtins/builtins-utils.h"
      7 
      8 #include "src/code-factory.h"
      9 
     10 namespace v8 {
     11 namespace internal {
     12 
     13 namespace {
     14 
     15 void Generate_GeneratorPrototypeResume(
     16     CodeStubAssembler* assembler, JSGeneratorObject::ResumeMode resume_mode,
     17     char const* const method_name) {
     18   typedef CodeStubAssembler::Label Label;
     19   typedef compiler::Node Node;
     20 
     21   Node* receiver = assembler->Parameter(0);
     22   Node* value = assembler->Parameter(1);
     23   Node* context = assembler->Parameter(4);
     24   Node* closed =
     25       assembler->SmiConstant(Smi::FromInt(JSGeneratorObject::kGeneratorClosed));
     26 
     27   // Check if the {receiver} is actually a JSGeneratorObject.
     28   Label if_receiverisincompatible(assembler, Label::kDeferred);
     29   assembler->GotoIf(assembler->TaggedIsSmi(receiver),
     30                     &if_receiverisincompatible);
     31   Node* receiver_instance_type = assembler->LoadInstanceType(receiver);
     32   assembler->GotoUnless(assembler->Word32Equal(
     33                             receiver_instance_type,
     34                             assembler->Int32Constant(JS_GENERATOR_OBJECT_TYPE)),
     35                         &if_receiverisincompatible);
     36 
     37   // Check if the {receiver} is running or already closed.
     38   Node* receiver_continuation = assembler->LoadObjectField(
     39       receiver, JSGeneratorObject::kContinuationOffset);
     40   Label if_receiverisclosed(assembler, Label::kDeferred),
     41       if_receiverisrunning(assembler, Label::kDeferred);
     42   assembler->GotoIf(assembler->SmiEqual(receiver_continuation, closed),
     43                     &if_receiverisclosed);
     44   DCHECK_LT(JSGeneratorObject::kGeneratorExecuting,
     45             JSGeneratorObject::kGeneratorClosed);
     46   assembler->GotoIf(assembler->SmiLessThan(receiver_continuation, closed),
     47                     &if_receiverisrunning);
     48 
     49   // Resume the {receiver} using our trampoline.
     50   Node* result = assembler->CallStub(
     51       CodeFactory::ResumeGenerator(assembler->isolate()), context, value,
     52       receiver, assembler->SmiConstant(Smi::FromInt(resume_mode)));
     53   assembler->Return(result);
     54 
     55   assembler->Bind(&if_receiverisincompatible);
     56   {
     57     // The {receiver} is not a valid JSGeneratorObject.
     58     Node* result = assembler->CallRuntime(
     59         Runtime::kThrowIncompatibleMethodReceiver, context,
     60         assembler->HeapConstant(assembler->factory()->NewStringFromAsciiChecked(
     61             method_name, TENURED)),
     62         receiver);
     63     assembler->Return(result);  // Never reached.
     64   }
     65 
     66   assembler->Bind(&if_receiverisclosed);
     67   {
     68     // The {receiver} is closed already.
     69     Node* result = nullptr;
     70     switch (resume_mode) {
     71       case JSGeneratorObject::kNext:
     72         result = assembler->CallRuntime(Runtime::kCreateIterResultObject,
     73                                         context, assembler->UndefinedConstant(),
     74                                         assembler->BooleanConstant(true));
     75         break;
     76       case JSGeneratorObject::kReturn:
     77         result =
     78             assembler->CallRuntime(Runtime::kCreateIterResultObject, context,
     79                                    value, assembler->BooleanConstant(true));
     80         break;
     81       case JSGeneratorObject::kThrow:
     82         result = assembler->CallRuntime(Runtime::kThrow, context, value);
     83         break;
     84     }
     85     assembler->Return(result);
     86   }
     87 
     88   assembler->Bind(&if_receiverisrunning);
     89   {
     90     Node* result =
     91         assembler->CallRuntime(Runtime::kThrowGeneratorRunning, context);
     92     assembler->Return(result);  // Never reached.
     93   }
     94 }
     95 
     96 }  // anonymous namespace
     97 
     98 // ES6 section 25.3.1.2 Generator.prototype.next ( value )
     99 void Builtins::Generate_GeneratorPrototypeNext(CodeStubAssembler* assembler) {
    100   Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kNext,
    101                                     "[Generator].prototype.next");
    102 }
    103 
    104 // ES6 section 25.3.1.3 Generator.prototype.return ( value )
    105 void Builtins::Generate_GeneratorPrototypeReturn(CodeStubAssembler* assembler) {
    106   Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kReturn,
    107                                     "[Generator].prototype.return");
    108 }
    109 
    110 // ES6 section 25.3.1.4 Generator.prototype.throw ( exception )
    111 void Builtins::Generate_GeneratorPrototypeThrow(CodeStubAssembler* assembler) {
    112   Generate_GeneratorPrototypeResume(assembler, JSGeneratorObject::kThrow,
    113                                     "[Generator].prototype.throw");
    114 }
    115 
    116 }  // namespace internal
    117 }  // namespace v8
    118