Keep IC monomorphic on transition, even if previously not STANDARD_STORE.

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 1853 matching lines @@
         : generic_stub();
   }
 
   // There are several special cases where an IC that is MONOMORPHIC can still
   // transition to a different GetNonTransitioningStoreMode IC that handles a
   // superset of the original IC. Handle those here if the receiver map hasn't
   // changed or it has transitioned to a more general kind.
   KeyedAccessStoreMode old_store_mode =
       Code::GetKeyedAccessStoreMode(target()->extra_ic_state());
   Handle<Map> previous_receiver_map = target_receiver_maps.at(0);
-  if (ic_state == MONOMORPHIC && old_store_mode == STANDARD_STORE) {
+  if (ic_state == MONOMORPHIC) {
       // If the "old" and "new" maps are in the same elements map family, stay
       // MONOMORPHIC and use the map for the most generic ElementsKind.
     Handle<Map> transitioned_receiver_map = receiver_map;
     if (IsTransitionStoreMode(store_mode)) {
       transitioned_receiver_map =
           ComputeTransitionedMap(receiver, store_mode);
     }
     if (IsTransitionedMapOfMonomorphicTarget(*transitioned_receiver_map)) {
       // Element family is the same, use the "worst" case map.
       store_mode = GetNonTransitioningStoreMode(store_mode);
       return isolate()->stub_cache()->ComputeKeyedStoreElement(
           transitioned_receiver_map, strict_mode, store_mode);
-    } else if (*previous_receiver_map == receiver->map()) {
-      if (IsGrowStoreMode(store_mode) ||
-          store_mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS ||
-          store_mode == STORE_NO_TRANSITION_HANDLE_COW) {
-        // A "normal" IC that handles stores can switch to a version that can
-        // grow at the end of the array, handle OOB accesses or copy COW arrays
-        // and still stay MONOMORPHIC.
-        return isolate()->stub_cache()->ComputeKeyedStoreElement(
-            receiver_map, strict_mode, store_mode);
-      }
+    } else if (*previous_receiver_map == receiver->map() &&
+               old_store_mode == STANDARD_STORE &&
+               (IsGrowStoreMode(store_mode) ||
+                store_mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS ||
+                store_mode == STORE_NO_TRANSITION_HANDLE_COW)) {
+      // A "normal" IC that handles stores can switch to a version that can
+      // grow at the end of the array, handle OOB accesses or copy COW arrays
+      // and still stay MONOMORPHIC.
+      return isolate()->stub_cache()->ComputeKeyedStoreElement(
+          receiver_map, strict_mode, store_mode);
     }
   }
 
   ASSERT(ic_state != GENERIC);
 
   bool map_added =
       AddOneReceiverMapIfMissing(&target_receiver_maps, receiver_map);
 
   if (IsTransitionStoreMode(store_mode)) {
     Handle<Map> transitioned_receiver_map =
@@ skipping 1185 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal