In-place shrinking of descriptor arrays with non-live transitions.

src/profile-generator.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 2202 matching lines @@
                                    setter, "set-%s");
             }
           }
           break;
         }
         case NORMAL:  // only in slow mode
         case HANDLER:  // only in lookup results, not in descriptors
         case INTERCEPTOR:  // only in lookup results, not in descriptors
         case MAP_TRANSITION:  // we do not care about transitions here...
         case CONSTANT_TRANSITION:
-        case NULL_DESCRIPTOR:  // ... and not about "holes"
+          break;
+        case NONEXISTENT:
+          UNREACHABLE();
           break;
       }
     }
   } else {
     StringDictionary* dictionary = js_obj->property_dictionary();
     int length = dictionary->Capacity();
     for (int i = 0; i < length; ++i) {
       Object* k = dictionary->KeyAt(i);
       if (dictionary->IsKey(k)) {
         Object* target = dictionary->ValueAt(i);
@@ skipping 1327 matching lines @@
 
 
 void HeapSnapshotJSONSerializer::SortHashMap(
     HashMap* map, List<HashMap::Entry*>* sorted_entries) {
   for (HashMap::Entry* p = map->Start(); p != NULL; p = map->Next(p))
     sorted_entries->Add(p);
   sorted_entries->Sort(SortUsingEntryValue);
 }
 
 } }  // namespace v8::internal