Leaving a generator via an exception causes it to close

src/arm/full-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 2216 matching lines @@
     Expression *value,
     JSGeneratorObject::ResumeMode resume_mode) {
   // The value stays in r0, and is ultimately read by the resumed generator, as
   // if CallRuntime(Runtime::kSuspendJSGeneratorObject) returned it. Or it
   // is read to throw the value when the resumed generator is already closed.
   // r1 will hold the generator object until the activation has been resumed.
   VisitForStackValue(generator);
   VisitForAccumulatorValue(value);
   __ pop(r1);
 
-  // Check generator state.
-  Label wrong_state, closed_state, done;
-  __ ldr(r3, FieldMemOperand(r1, JSGeneratorObject::kContinuationOffset));
-  STATIC_ASSERT(JSGeneratorObject::kGeneratorExecuting < 0);
-  STATIC_ASSERT(JSGeneratorObject::kGeneratorClosed == 0);
-  __ cmp(r3, Operand(Smi::FromInt(0)));
-  __ b(eq, &closed_state);
-  __ b(lt, &wrong_state);
-
   // Load suspended function and context.
   __ ldr(cp, FieldMemOperand(r1, JSGeneratorObject::kContextOffset));
   __ ldr(r4, FieldMemOperand(r1, JSGeneratorObject::kFunctionOffset));
 
   // Load receiver and store as the first argument.
   __ ldr(r2, FieldMemOperand(r1, JSGeneratorObject::kReceiverOffset));
   __ push(r2);
 
   // Push holes for the rest of the arguments to the generator function.
   __ ldr(r3, FieldMemOperand(r4, JSFunction::kSharedFunctionInfoOffset));
   __ ldr(r3,
          FieldMemOperand(r3, SharedFunctionInfo::kFormalParameterCountOffset));
   __ LoadRoot(r2, Heap::kTheHoleValueRootIndex);
   Label push_argument_holes, push_frame;
   __ bind(&push_argument_holes);
   __ sub(r3, r3, Operand(Smi::FromInt(1)), SetCC);
   __ b(mi, &push_frame);
   __ push(r2);
   __ jmp(&push_argument_holes);
 
   // 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);
   __ bl(&resume_frame);
   __ jmp(&done);
   __ bind(&resume_frame);
   // lr = return address.
   // fp = caller's frame pointer.
   // pp = caller's constant pool (if FLAG_enable_ool_constant_pool),
   // cp = callee's context,
   // r4 = callee's JS function.
   __ PushFixedFrame(r4);
@@ skipping 39 matching lines @@
   __ push(r2);
   __ b(&push_operand_holes);
   __ bind(&call_resume);
   DCHECK(!result_register().is(r1));
   __ Push(r1, result_register());
   __ Push(Smi::FromInt(resume_mode));
   __ CallRuntime(Runtime::kResumeJSGeneratorObject, 3);
   // Not reached: the runtime call returns elsewhere.
   __ stop("not-reached");
 
-  // Reach here when generator is closed.
-  __ bind(&closed_state);
-  if (resume_mode == JSGeneratorObject::NEXT) {
-    // Return completed iterator result when generator is closed.
-    __ LoadRoot(r2, Heap::kUndefinedValueRootIndex);
-    __ push(r2);
-    // Pop value from top-of-stack slot; box result into result register.
-    EmitCreateIteratorResult(true);
-  } else {
-    // Throw the provided value.
-    __ push(r0);
-    __ CallRuntime(Runtime::kThrow, 1);
-  }
-  __ jmp(&done);
-
-  // Throw error if we attempt to operate on a running generator.
-  __ bind(&wrong_state);
-  __ push(r1);
-  __ CallRuntime(Runtime::kThrowGeneratorStateError, 1);
-
   __ bind(&done);
   context()->Plug(result_register());
 }
 
 
 void FullCodeGenerator::EmitCreateIteratorResult(bool done) {
   Label gc_required;
   Label allocated;
 
   const int instance_size = 5 * kPointerSize;
@@ skipping 3008 matching lines @@
 
   DCHECK(interrupt_address ==
          isolate->builtins()->OsrAfterStackCheck()->entry());
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM