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());
+  VisitForStackValue(expr->generator_object());
+
+  if (expr->kind() == Yield::FINAL) {
+    // TODO(wingo): Mark the iterator as closed.
+  } else {
+    __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
+    __ movq(context_register(),
+            Operand(rbp, StandardFrameConstants::kContextOffset));
+  }
+
+  Label resume;
+  __ CompareRoot(result_register(), Heap::kTheHoleValueRootIndex);
+  __ j(not_equal, &resume);
+  switch (expr->kind()) {
+    case Yield::INITIAL:
+      __ pop(result_register());
+      break;
+    case Yield::SUSPEND:
+      // TODO(wingo): Box into { value: VALUE, done: false }.
+      __ pop(result_register());
+      break;
+    case Yield::FINAL:
+      // TODO(wingo): Box into { value: VALUE, done: true }.
+      __ pop(result_register());
+      break;
+    case Yield::DELEGATING:
+      UNIMPLEMENTED();
+  }
+  EmitReturnSequence();
+
+  __ bind(&resume);
+  context()->Plug(result_register());
+}
+
+
 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