Generator objects can suspend

src/x64/full-codegen-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1889 matching lines @@
     case NAMED_PROPERTY:
       EmitNamedPropertyAssignment(expr);
       break;
     case KEYED_PROPERTY:
       EmitKeyedPropertyAssignment(expr);
       break;
   }
 }
 
 
+void FullCodeGenerator::VisitYield(Yield* expr) {
+  Comment cmnt(masm_, "[ Yield");
+  // Evaluate yielded value first; the initial iterator definition depends on
+  // this.  It stays on the stack while we update the iterator.
+  VisitForStackValue(expr->expression());
+
+  switch (expr->yield_kind()) {
+    case Yield::INITIAL:
+    case Yield::SUSPEND: {
+      VisitForStackValue(expr->generator_object());
+      __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
+      __ movq(context_register(),
+              Operand(rbp, StandardFrameConstants::kContextOffset));
+
+      Label resume;
+      __ CompareRoot(result_register(), Heap::kTheHoleValueRootIndex);
+      __ j(not_equal, &resume);
+      __ pop(result_register());
+      if (expr->yield_kind() == Yield::SUSPEND) {
+        // TODO(wingo): Box into { value: VALUE, done: false }.
+      }
+      EmitReturnSequence();
+
+      __ bind(&resume);
+      context()->Plug(result_register());
+      break;
+    }
+
+    case Yield::FINAL: {
+      VisitForAccumulatorValue(expr->generator_object());
+      __ Move(FieldOperand(result_register(),
+                           JSGeneratorObject::kContinuationOffset),
+              Smi::FromInt(JSGeneratorObject::kGeneratorClosed));
+      __ pop(result_register());
+      // TODO(wingo): Box into { value: VALUE, done: true }.
+
+      // Exit all nested statements.
+      NestedStatement* current = nesting_stack_;
+      int stack_depth = 0;
+      int context_length = 0;
+      while (current != NULL) {
+        current = current->Exit(&stack_depth, &context_length);
+      }
+      __ Drop(stack_depth);
+      EmitReturnSequence();
+      break;
+    }
+
+    case Yield::DELEGATING:
+      UNIMPLEMENTED();
+  }
+}
+
+
 void FullCodeGenerator::EmitNamedPropertyLoad(Property* prop) {
   SetSourcePosition(prop->position());
   Literal* key = prop->key()->AsLiteral();
   __ Move(rcx, key->handle());
   Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
   CallIC(ic, RelocInfo::CODE_TARGET, prop->PropertyFeedbackId());
 }
 
 
 void FullCodeGenerator::EmitKeyedPropertyLoad(Property* prop) {
@@ skipping 2639 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64