[generators] Decouple generator resume from fullcodegen.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index d19f71a332bad9e9fc5b50dae22f230fc90a96bb..53085c3e0037a30bb1df6f991b493697be4fe7a7 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -2313,8 +2313,112 @@ void Builtins::Generate_MathTrunc(compiler::CodeStubAssembler* assembler) {
 }
 
 // -----------------------------------------------------------------------------
-// ES6 section 26.1 The Reflect Object
+// ES6 section 25.3 Generator Objects
+
+namespace {
+
+void Generate_GeneratorPrototypeResume(
+    compiler::CodeStubAssembler* assembler,
+    JSGeneratorObject::ResumeMode resume_mode, char const* const method_name) {
+  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* zero = assembler->SmiConstant(Smi::FromInt(0));
+
+  // 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);
+
+  // 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);
+
+  // 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);
+  {
+    // 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);
+  {
+    // 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);
+  {
+    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");
+}
+
+// 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");
+}
+
+// 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");
+}
+
+// -----------------------------------------------------------------------------
+// ES6 section 26.1 The Reflect Object
 
 // ES6 section 26.1.3 Reflect.defineProperty
 BUILTIN(ReflectDefineProperty) {