Generators return boxed values

src/bootstrapper.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 1367 matching lines @@
     native_context()->set_strict_mode_generator_function_map(
         *strict_mode_generator_function_map);
 
     Handle<Map> object_map(native_context()->object_function()->initial_map());
     Handle<Map> generator_object_prototype_map = factory()->CopyMap(
         object_map, 0);
     generator_object_prototype_map->set_prototype(
         *generator_object_prototype);
     native_context()->set_generator_object_prototype_map(
         *generator_object_prototype_map);
+
+    // Create a map for iterator result objects.
+    ASSERT(object_map->inobject_properties() == 0);
+    STATIC_ASSERT(JSGeneratorObject::kResultPropertyCount == 2);
+    Handle<Map> iterator_result_map = factory()->CopyMap(object_map, 2);
+    ASSERT(iterator_result_map->inobject_properties() == 2);
+
+    Handle<DescriptorArray> descriptors = factory()->NewDescriptorArray(0, 2);
+    DescriptorArray::WhitenessWitness witness(*descriptors);
+    iterator_result_map->set_instance_descriptors(*descriptors);
+
+    STATIC_ASSERT(JSGeneratorObject::kResultValuePropertyIndex == 0);

[Michael Starzinger, 2013/05/06 11:22:32]

Is there a particular reason why cannot use the index constant in the calls
below instead of using static-asserts and hard-coded constants? Same applies for
the second index below and the count above.

+    Handle<String> value_string = factory()->InternalizeOneByteString(
+        STATIC_ASCII_VECTOR("value"));
+    FieldDescriptor value_descriptor(*value_string, 0, NONE,
+                                     Representation::Tagged());
+    iterator_result_map->AppendDescriptor(&value_descriptor, witness);
+
+    STATIC_ASSERT(JSGeneratorObject::kResultDonePropertyIndex == 1);
+    Handle<String> done_string = factory()->InternalizeOneByteString(
+        STATIC_ASCII_VECTOR("done"));
+    FieldDescriptor done_descriptor(*done_string, 1, NONE,
+                                    Representation::Tagged());
+    iterator_result_map->AppendDescriptor(&done_descriptor, witness);
+
+    iterator_result_map->set_unused_property_fields(0);
+    native_context()->set_iterator_result_map(*iterator_result_map);
   }
 }
 
 
 bool Genesis::CompileBuiltin(Isolate* isolate, int index) {
   Vector<const char> name = Natives::GetScriptName(index);
   Handle<String> source_code =
       isolate->bootstrapper()->NativesSourceLookup(index);
   return CompileNative(isolate, name, source_code);
 }
@@ skipping 1180 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   ASSERT(!IsActive());
 }
 
 } }  // namespace v8::internal