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 615eb67ba6459542be354eda2ecab900a787d471..878f2566aef38cbfe21a3fb0eac612dbe7f630a0 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -1871,8 +1871,17 @@ 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());
@@ -1902,9 +1911,6 @@ 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();
@@ -1949,6 +1955,10 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
       __ jmp(&l_suspend);
       __ bind(&l_continuation);
       __ RecordGeneratorContinuation();
+      __ Pop(rbx);
+      // Ignoring the resume mode here is clearly wrong.  Currently, return is

[Jarin, 2016/01/22 13:42:48]

TODO(neis), perhaps?

+      // not supported for yield*.  The planned desugaring of yield* using
+      // do-expressions will naturally solve this.
       __ jmp(&l_resume);
 
       __ bind(&l_suspend);
@@ -2024,8 +2034,8 @@ 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
@@ -2083,6 +2093,7 @@ 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);
   }
@@ -2096,6 +2107,7 @@ 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));