Leaving a generator via an exception causes it to close

src/ia32/full-codegen-ia32.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_IA32
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 2146 matching lines @@
     Expression *value,
     JSGeneratorObject::ResumeMode resume_mode) {
   // The value stays in eax, 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.
   // ebx will hold the generator object until the activation has been resumed.
   VisitForStackValue(generator);
   VisitForAccumulatorValue(value);
   __ pop(ebx);
 
-  // Check generator state.
-  Label wrong_state, closed_state, done;
-  STATIC_ASSERT(JSGeneratorObject::kGeneratorExecuting < 0);
-  STATIC_ASSERT(JSGeneratorObject::kGeneratorClosed == 0);
-  __ cmp(FieldOperand(ebx, JSGeneratorObject::kContinuationOffset),
-         Immediate(Smi::FromInt(0)));
-  __ j(equal, &closed_state);
-  __ j(less, &wrong_state);
-
   // Load suspended function and context.
   __ mov(esi, FieldOperand(ebx, JSGeneratorObject::kContextOffset));
   __ mov(edi, FieldOperand(ebx, JSGeneratorObject::kFunctionOffset));
 
   // Push receiver.
   __ push(FieldOperand(ebx, JSGeneratorObject::kReceiverOffset));
 
   // Push holes for arguments to generator function.
   __ mov(edx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
   __ mov(edx,
          FieldOperand(edx, SharedFunctionInfo::kFormalParameterCountOffset));
   __ mov(ecx, isolate()->factory()->the_hole_value());
   Label push_argument_holes, push_frame;
   __ bind(&push_argument_holes);
   __ sub(edx, Immediate(Smi::FromInt(1)));
   __ j(carry, &push_frame);
   __ push(ecx);
   __ 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);
   __ call(&resume_frame);
   __ jmp(&done);
   __ bind(&resume_frame);
   __ push(ebp);  // Caller's frame pointer.
   __ mov(ebp, esp);
   __ push(esi);  // Callee's context.
   __ push(edi);  // Callee's JS Function.
 
   // Load the operand stack size.
@@ skipping 26 matching lines @@
   __ push(ecx);
   __ jmp(&push_operand_holes);
   __ bind(&call_resume);
   __ push(ebx);
   __ push(result_register());
   __ Push(Smi::FromInt(resume_mode));
   __ CallRuntime(Runtime::kResumeJSGeneratorObject, 3);
   // 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.
-    __ push(Immediate(isolate()->factory()->undefined_value()));
-    // Pop value from top-of-stack slot; box result into result register.
-    EmitCreateIteratorResult(true);
-  } else {
-    // Throw the provided value.
-    __ push(eax);
-    __ CallRuntime(Runtime::kThrow, 1);
-  }
-  __ jmp(&done);
-
-  // Throw error if we attempt to operate on a running generator.
-  __ bind(&wrong_state);
-  __ push(ebx);
-  __ 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 2970 matching lines @@
   DCHECK_EQ(isolate->builtins()->OsrAfterStackCheck()->entry(),
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32