Two bugfixes for hydrogen-based array constructors

src/objects.cc

 // Copyright 2013 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 8904 matching lines @@
   if (!maybe_maps->To(&maps)) return maybe_maps;
 
   Map* current_map = initial_map;
   ElementsKind kind = current_map->elements_kind();
   ASSERT(kind == GetInitialFastElementsKind());
   maps->set(kind, current_map);
   for (int i = GetSequenceIndexFromFastElementsKind(kind) + 1;
        i < kFastElementsKindCount; ++i) {
     Map* new_map;
     ElementsKind next_kind = GetFastElementsKindFromSequenceIndex(i);
-    MaybeObject* maybe_new_map =
-        current_map->CopyAsElementsKind(next_kind, INSERT_TRANSITION);
-    if (!maybe_new_map->To(&new_map)) return maybe_new_map;
+    if (current_map->HasElementsTransition()) {
+      new_map = current_map->elements_transition_map();
+      ASSERT(new_map->elements_kind() == next_kind);
+    } else {
+      MaybeObject* maybe_new_map =
+          current_map->CopyAsElementsKind(next_kind, INSERT_TRANSITION);
+      if (!maybe_new_map->To(&new_map)) return maybe_new_map;
+    }
     maps->set(next_kind, new_map);
     current_map = new_map;
   }
   native_context->set_js_array_maps(maps);
   return initial_map;
 }
 
 
 Handle<Object> CacheInitialJSArrayMaps(Handle<Context> native_context,
                                        Handle<Map> initial_map) {
@@ skipping 6147 matching lines @@
   set_year(Smi::FromInt(year), SKIP_WRITE_BARRIER);
   set_month(Smi::FromInt(month), SKIP_WRITE_BARRIER);
   set_day(Smi::FromInt(day), SKIP_WRITE_BARRIER);
   set_weekday(Smi::FromInt(weekday), SKIP_WRITE_BARRIER);
   set_hour(Smi::FromInt(hour), SKIP_WRITE_BARRIER);
   set_min(Smi::FromInt(min), SKIP_WRITE_BARRIER);
   set_sec(Smi::FromInt(sec), SKIP_WRITE_BARRIER);
 }
 
 } }  // namespace v8::internal