Generators can resume

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 f9651f01efad26a02bbdf1e86df2745c1b943258..86dd4e10a4f3d32d1b487a5121500537cc1bb871 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -1961,6 +1961,99 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
 }
 
 
+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 the CallRuntime(Runtime::kSuspendJSGeneratorObject) returned it.  rbx
+  // will hold the generator object until the activation has been resumed.
+  VisitForStackValue(generator);
+  VisitForAccumulatorValue(value);
+  __ pop(rbx);
+
+  // Check generator state.
+  Label wrong_state, done;
+  STATIC_ASSERT(JSGeneratorObject::kGeneratorExecuting <= 0);
+  STATIC_ASSERT(JSGeneratorObject::kGeneratorClosed <= 0);
+  __ SmiCompare(FieldOperand(rbx, JSGeneratorObject::kContinuationOffset),
+                Smi::FromInt(0));
+  __ j(less_equal, &wrong_state);
+
+  // Load suspended function and context.
+  __ movq(rsi, FieldOperand(rbx, JSGeneratorObject::kContextOffset));
+  __ movq(rdi, FieldOperand(rbx, JSGeneratorObject::kFunctionOffset));
+
+  // Push holes for arguments to generator function.
+  __ movq(rdx, FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
+  __ movsxlq(rdx,
+             FieldOperand(rdx,
+                          SharedFunctionInfo::kFormalParameterCountOffset));
+  __ LoadRoot(rcx, Heap::kTheHoleValueRootIndex);
+  Label push_argument_holes;
+  __ bind(&push_argument_holes);
+  __ push(rcx);
+  __ subq(rdx, Immediate(1));
+  __ j(not_carry, &push_argument_holes);
+
+  // Enter a new JavaScript frame, and initialize its slots as they were when
+  // the generator was suspended.
+  Label push_frame, resume_frame;
+  __ bind(&push_frame);
+  __ call(&resume_frame);
+  __ jmp(&done);
+  __ bind(&resume_frame);
+  __ push(rbp);  // Caller's frame pointer.
+  __ movq(rbp, rsp);
+  __ push(rsi);  // Callee's context.
+  __ push(rdi);  // Callee's JS Function.
+
+  // Load the operand stack size.
+  __ movq(rdx, FieldOperand(rbx, JSGeneratorObject::kOperandStackOffset));
+  __ movq(rdx, FieldOperand(rdx, FixedArray::kLengthOffset));
+  __ SmiToInteger32(rdx, rdx);
+
+  // If we are sending a value and there is no operand stack, we can jump back
+  // in directly.
+  if (resume_mode == JSGeneratorObject::SEND) {
+    Label slow_resume;
+    __ cmpq(rdx, Immediate(0));
+    __ j(not_zero, &slow_resume);
+    __ movq(rdx, FieldOperand(rdi, JSFunction::kCodeEntryOffset));
+    __ SmiToInteger64(rcx,
+        FieldOperand(rbx, JSGeneratorObject::kContinuationOffset));
+    __ addq(rdx, rcx);
+    __ Move(FieldOperand(rbx, JSGeneratorObject::kContinuationOffset),
+            Smi::FromInt(JSGeneratorObject::kGeneratorExecuting));
+    __ jmp(rdx);
+    __ bind(&slow_resume);
+  }
+
+  // Otherwise, we push holes for the operand stack and call the runtime to fix
+  // up the stack and the handlers.
+  Label push_operand_holes, call_resume;
+  __ bind(&push_operand_holes);
+  __ subq(rdx, Immediate(1));
+  __ j(carry, &call_resume);
+  __ push(rcx);
+  __ jmp(&push_operand_holes);
+  __ bind(&call_resume);
+  __ push(rbx);
+  __ push(result_register());
+  __ Push(Smi::FromInt(resume_mode));
+  __ CallRuntime(Runtime::kResumeJSGeneratorObject, 3);
+  // Not reached: the runtime call returns elsewhere.
+  __ Abort("Generator failed to resume.");
+
+  // 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());
+}
+
+
 void FullCodeGenerator::EmitNamedPropertyLoad(Property* prop) {
   SetSourcePosition(prop->position());
   Literal* key = prop->key()->AsLiteral();