Micro-optimize lookupiterator: faster path for fast-mode objects

src/lookup-inl.h

 // 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.
 
 #ifndef V8_LOOKUP_INL_H_
 #define V8_LOOKUP_INL_H_
 
 #include "src/lookup.h"
 
 #include "src/elements.h"
@@ skipping 60 matching lines @@
           if (js_object->elements() == isolate()->heap()->empty_fixed_array()) {
             return NOT_FOUND;
           }
 
           ElementsAccessor* accessor = js_object->GetElementsAccessor();
           FixedArrayBase* backing_store = js_object->elements();
           number_ = accessor->GetIndexForKey(js_object, backing_store, index_);
           if (number_ == kMaxUInt32) return NOT_FOUND;
           property_details_ = accessor->GetDetails(backing_store, number_);
         }
-      } else if (holder->IsGlobalObject()) {
+      } else if (!map->is_dictionary_map()) {
+        DescriptorArray* descriptors = map->instance_descriptors();
+        int number = descriptors->SearchWithCache(*name_, map);
+        if (number == DescriptorArray::kNotFound) return NOT_FOUND;
+        number_ = static_cast<uint32_t>(number);
+        property_details_ = descriptors->GetDetails(number_);
+      } else if (map->IsGlobalObjectMap()) {
         GlobalDictionary* dict = JSObject::cast(holder)->global_dictionary();
         int number = dict->FindEntry(name_);
         if (number == GlobalDictionary::kNotFound) return NOT_FOUND;
         number_ = static_cast<uint32_t>(number);
         DCHECK(dict->ValueAt(number_)->IsPropertyCell());
         PropertyCell* cell = PropertyCell::cast(dict->ValueAt(number_));
         if (cell->value()->IsTheHole()) return NOT_FOUND;
         property_details_ = cell->property_details();
-      } else if (map->is_dictionary_map()) {
+      } else {
         NameDictionary* dict = JSObject::cast(holder)->property_dictionary();
         int number = dict->FindEntry(name_);
         if (number == NameDictionary::kNotFound) return NOT_FOUND;
         number_ = static_cast<uint32_t>(number);
         property_details_ = dict->DetailsAt(number_);
-      } else {
-        DescriptorArray* descriptors = map->instance_descriptors();
-        int number = descriptors->SearchWithCache(*name_, map);
-        if (number == DescriptorArray::kNotFound) return NOT_FOUND;
-        number_ = static_cast<uint32_t>(number);
-        property_details_ = descriptors->GetDetails(number_);
       }
       has_property_ = true;
       switch (property_details_.kind()) {
         case v8::internal::kData:
           return DATA;
         case v8::internal::kAccessor:
           return ACCESSOR;
       }
     case ACCESSOR:
     case DATA:
@@ skipping 20 matching lines @@
     default:
       return NOT_FOUND;
   }
   UNREACHABLE();
   return state_;
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_LOOKUP_INL_H_