Implement [Generator].prototype.return.

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index 68bb6498a1112deb49a9ff8a5eadd72b0914b334..56eca5d8b0d089ed5f73c3272f8bc6877e9fb6bc 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -1860,8 +1860,17 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
 
       __ jmp(&suspend);
       __ bind(&continuation);
+      // When we arrive here, the stack top is the resume mode and
+      // result_register() holds the input value (the argument given to the
+      // respective resume operation).
       __ RecordGeneratorContinuation();
-      __ jmp(&resume);
+      __ Pop(rbx);
+      __ SmiCompare(rbx, Smi::FromInt(JSGeneratorObject::RETURN));
+      __ j(not_equal, &resume);
+      __ Push(result_register());
+      EmitCreateIteratorResult(true);
+      EmitUnwindBeforeReturn();
+      EmitReturnSequence();
 
       __ bind(&suspend);
       VisitForAccumulatorValue(expr->generator_object());
@@ -1891,9 +1900,6 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
 
     case Yield::kFinal: {
       VisitForAccumulatorValue(expr->generator_object());
-      __ Move(FieldOperand(result_register(),
-                           JSGeneratorObject::kContinuationOffset),
-              Smi::FromInt(JSGeneratorObject::kGeneratorClosed));
       // Pop value from top-of-stack slot, box result into result register.
       EmitCreateIteratorResult(true);
       EmitUnwindBeforeReturn();
@@ -1938,6 +1944,10 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
       __ jmp(&l_suspend);
       __ bind(&l_continuation);
       __ RecordGeneratorContinuation();
+      __ Pop(rbx);
+      // TODO(neis): Ignoring the resume mode here is clearly wrong.  Currently,
+      // return is not supported for yield*.  The planned desugaring of yield*
+      // using do-expressions will naturally solve this.
       __ jmp(&l_resume);
 
       __ bind(&l_suspend);
@@ -2013,8 +2023,8 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
 }
 
 
-void FullCodeGenerator::EmitGeneratorResume(Expression *generator,
-    Expression *value,
+void FullCodeGenerator::EmitGeneratorResume(
+    Expression* generator, Expression* value,
     JSGeneratorObject::ResumeMode resume_mode) {
   // The value stays in rax, and is ultimately read by the resumed generator, as
   // if CallRuntime(Runtime::kSuspendJSGeneratorObject) returned it. Or it
@@ -2072,6 +2082,7 @@ void FullCodeGenerator::EmitGeneratorResume(Expression *generator,
     __ addp(rdx, rcx);
     __ Move(FieldOperand(rbx, JSGeneratorObject::kContinuationOffset),
             Smi::FromInt(JSGeneratorObject::kGeneratorExecuting));
+    __ Push(Smi::FromInt(resume_mode));  // Consumed in continuation.
     __ jmp(rdx);
     __ bind(&slow_resume);
   }
@@ -2085,6 +2096,7 @@ void FullCodeGenerator::EmitGeneratorResume(Expression *generator,
   __ Push(rcx);
   __ jmp(&push_operand_holes);
   __ bind(&call_resume);
+  __ Push(Smi::FromInt(resume_mode));  // Consumed in continuation.
   __ Push(rbx);
   __ Push(result_register());
   __ Push(Smi::FromInt(resume_mode));