[LookupIterator] Optimize the path that writes to fields.

src/lookup.cc

 // Copyright 2014 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/lookup.h"
 
 #include "src/bootstrapper.h"
 #include "src/deoptimizer.h"
 #include "src/elements.h"
 #include "src/field-type.h"
@@ skipping 499 matching lines @@
 }
 
 
 void LookupIterator::WriteDataValue(Handle<Object> value) {
   DCHECK_EQ(DATA, state_);
   Handle<JSReceiver> holder = GetHolder<JSReceiver>();
   if (IsElement()) {
     Handle<JSObject> object = Handle<JSObject>::cast(holder);
     ElementsAccessor* accessor = object->GetElementsAccessor();
     accessor->Set(object, number_, *value);
+  } else if (holder->HasFastProperties()) {
+    if (property_details_.type() == v8::internal::DATA) {
+      JSObject::cast(*holder)->WriteToField(descriptor_number(),
+                                            property_details_, *value);
+    } else {
+      DCHECK_EQ(v8::internal::DATA_CONSTANT, property_details_.type());
+    }
   } else if (holder->IsJSGlobalObject()) {
     Handle<GlobalDictionary> property_dictionary =
         handle(JSObject::cast(*holder)->global_dictionary());
     PropertyCell::UpdateCell(property_dictionary, dictionary_entry(), value,
                              property_details_);
-  } else if (!holder->HasFastProperties()) {
+  } else {
     NameDictionary* property_dictionary = holder->property_dictionary();
     property_dictionary->ValueAtPut(dictionary_entry(), *value);
-  } else if (property_details_.type() == v8::internal::DATA) {
-    JSObject::cast(*holder)->WriteToField(descriptor_number(), *value);
-  } else {
-    DCHECK_EQ(v8::internal::DATA_CONSTANT, property_details_.type());
   }
 }
 
 
 bool LookupIterator::HasInterceptor(Map* map) const {
   if (IsElement()) return map->has_indexed_interceptor();
   return map->has_named_interceptor();
 }
 
 
@@ skipping 132 matching lines @@
     // Fall through.
     default:
       return NOT_FOUND;
   }
   UNREACHABLE();
   return state_;
 }
 
 }  // namespace internal
 }  // namespace v8