Leaving a generator via an exception causes it to close

src/arm64/full-codegen-arm64.cc

 // Copyright 2013 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_ARM64
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 4915 matching lines @@
       break;
     }
   }
 }
 
 
 void FullCodeGenerator::EmitGeneratorResume(Expression *generator,
     Expression *value,
     JSGeneratorObject::ResumeMode resume_mode) {
   ASM_LOCATION("FullCodeGenerator::EmitGeneratorResume");
-  Register value_reg = x0;
   Register generator_object = x1;
   Register the_hole = x2;
   Register operand_stack_size = w3;
   Register function = x4;
 
   // The value stays in x0, 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. x1
   // will hold the generator object until the activation has been resumed.
   VisitForStackValue(generator);
   VisitForAccumulatorValue(value);
   __ Pop(generator_object);
 
-  // Check generator state.
-  Label wrong_state, closed_state, done;
-  __ Ldr(x10, FieldMemOperand(generator_object,
-                              JSGeneratorObject::kContinuationOffset));
-  STATIC_ASSERT(JSGeneratorObject::kGeneratorExecuting < 0);
-  STATIC_ASSERT(JSGeneratorObject::kGeneratorClosed == 0);
-  __ CompareAndBranch(x10, Smi::FromInt(0), eq, &closed_state);
-  __ CompareAndBranch(x10, Smi::FromInt(0), lt, &wrong_state);
-
   // Load suspended function and context.
   __ Ldr(cp, FieldMemOperand(generator_object,
                              JSGeneratorObject::kContextOffset));
   __ Ldr(function, FieldMemOperand(generator_object,
                                    JSGeneratorObject::kFunctionOffset));
 
   // Load receiver and store as the first argument.
   __ Ldr(x10, FieldMemOperand(generator_object,
                               JSGeneratorObject::kReceiverOffset));
   __ Push(x10);
 
   // Push holes for the rest of the arguments to the generator function.
   __ Ldr(x10, FieldMemOperand(function, JSFunction::kSharedFunctionInfoOffset));
 
   // The number of arguments is stored as an int32_t, and -1 is a marker
   // (SharedFunctionInfo::kDontAdaptArgumentsSentinel), so we need sign
   // extension to correctly handle it. However, in this case, we operate on
   // 32-bit W registers, so extension isn't required.
   __ Ldr(w10, FieldMemOperand(x10,
                               SharedFunctionInfo::kFormalParameterCountOffset));
   __ LoadRoot(the_hole, Heap::kTheHoleValueRootIndex);
   __ PushMultipleTimes(the_hole, w10);
 
   // Enter a new JavaScript frame, and initialize its slots as they were when
   // the generator was suspended.
-  Label resume_frame;
+  Label resume_frame, done;
   __ Bl(&resume_frame);
   __ B(&done);
 
   __ Bind(&resume_frame);
   __ Push(lr,           // Return address.
           fp,           // Caller's frame pointer.
           cp,           // Callee's context.
           function);    // Callee's JS Function.
   __ Add(fp, __ StackPointer(), kPointerSize * 2);
 
@@ skipping 24 matching lines @@
   // Otherwise, we push holes for the operand stack and call the runtime to fix
   // up the stack and the handlers.
   __ PushMultipleTimes(the_hole, operand_stack_size);
 
   __ Mov(x10, Smi::FromInt(resume_mode));
   __ Push(generator_object, result_register(), x10);
   __ CallRuntime(Runtime::kResumeJSGeneratorObject, 3);
   // Not reached: the runtime call returns elsewhere.
   __ Unreachable();
 
-  // Reach here when generator is closed.
-  __ Bind(&closed_state);
-  if (resume_mode == JSGeneratorObject::NEXT) {
-    // Return completed iterator result when generator is closed.
-    __ LoadRoot(x10, Heap::kUndefinedValueRootIndex);
-    __ Push(x10);
-    // Pop value from top-of-stack slot; box result into result register.
-    EmitCreateIteratorResult(true);
-  } else {
-    // Throw the provided value.
-    __ Push(value_reg);
-    __ CallRuntime(Runtime::kThrow, 1);
-  }
-  __ B(&done);
-
-  // Throw error if we attempt to operate on a running generator.
-  __ Bind(&wrong_state);
-  __ Push(generator_object);
-  __ 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 288 matching lines @@
   return previous_;
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64