Elide hole checks on KeyedLoads of holey double arrays.

src/ic.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 2002 matching lines @@
     return StoreIC::Store(state,
                           strict_mode,
                           object,
                           Handle<String>::cast(key),
                           value,
                           JSReceiver::MAY_BE_STORE_FROM_KEYED);
   }
 
   bool use_ic = FLAG_use_ic && !object->IsAccessCheckNeeded() &&
       !(FLAG_harmony_observation && object->IsJSObject() &&
-          JSObject::cast(*object)->map()->is_observed());
+        JSObject::cast(*object)->map()->is_observed());
+  if (use_ic && !object->IsSmi()) {
+    // Don't use ICs for maps of the objects in Array's prototype chain. We
+    // expect to be able to trap element sets to objects with those maps in the
+    // runtime to enable optimization of element hole access.
+    Handle<HeapObject> heap_object = Handle<HeapObject>::cast(object);
+    if (heap_object->map()->IsMapInArrayPrototypeChain()) use_ic = false;
+  }
   ASSERT(!(use_ic && object->IsJSGlobalProxy()));
 
   if (use_ic) {
     Handle<Code> stub = (strict_mode == kStrictMode)
         ? generic_stub_strict()
         : generic_stub();
     if (miss_mode != MISS_FORCE_GENERIC) {
       if (object->IsJSObject()) {
         Handle<JSObject> receiver = Handle<JSObject>::cast(object);
         if (receiver->map()->is_deprecated()) {
@@ skipping 973 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal