Leaving a generator via an exception causes it to close

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index cbee082060ee1b99e0d3c61031f885f58071e3da..17f364b2c209b6585b6bcb0f79d87aa3fe7de0df 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -2196,15 +2196,6 @@ void FullCodeGenerator::EmitGeneratorResume(Expression *generator,
   VisitForAccumulatorValue(value);
   __ Pop(rbx);
 
-  // Check generator state.
-  Label wrong_state, closed_state, done;
-  STATIC_ASSERT(JSGeneratorObject::kGeneratorExecuting < 0);
-  STATIC_ASSERT(JSGeneratorObject::kGeneratorClosed == 0);
-  __ SmiCompare(FieldOperand(rbx, JSGeneratorObject::kContinuationOffset),
-                Smi::FromInt(0));
-  __ j(equal, &closed_state);
-  __ j(less, &wrong_state);
-
   // Load suspended function and context.
   __ movp(rsi, FieldOperand(rbx, JSGeneratorObject::kContextOffset));
   __ movp(rdi, FieldOperand(rbx, JSGeneratorObject::kFunctionOffset));
@@ -2226,7 +2217,7 @@ void FullCodeGenerator::EmitGeneratorResume(Expression *generator,
 
   // Enter a new JavaScript frame, and initialize its slots as they were when
   // the generator was suspended.
-  Label resume_frame;
+  Label resume_frame, done;
   __ bind(&push_frame);
   __ call(&resume_frame);
   __ jmp(&done);
@@ -2273,25 +2264,6 @@ void FullCodeGenerator::EmitGeneratorResume(Expression *generator,
   // Not reached: the runtime call returns elsewhere.
   __ Abort(kGeneratorFailedToResume);
 
-  // Reach here when generator is closed.
-  __ bind(&closed_state);
-  if (resume_mode == JSGeneratorObject::NEXT) {
-    // Return completed iterator result when generator is closed.
-    __ PushRoot(Heap::kUndefinedValueRootIndex);
-    // Pop value from top-of-stack slot; box result into result register.
-    EmitCreateIteratorResult(true);
-  } else {
-    // Throw the provided value.
-    __ Push(rax);
-    __ CallRuntime(Runtime::kThrow, 1);
-  }
-  __ jmp(&done);
-
-  // Throw error if we attempt to operate on a running generator.
-  __ bind(&wrong_state);
-  __ Push(rbx);
-  __ CallRuntime(Runtime::kThrowGeneratorStateError, 1);
-
   __ bind(&done);
   context()->Plug(result_register());
 }