Reland "Track field types.".

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 1213 matching lines @@
 
   // If the value that's being stored does not fit in the field that the
   // instance would transition to, create a new transition that fits the value.
   // This has to be done before generating the IC, since that IC will embed the
   // transition target.
   // Ensure the instance and its map were migrated before trying to update the
   // transition target.
   ASSERT(!receiver->map()->is_deprecated());
   if (!lookup->CanHoldValue(value)) {
     Handle<Map> target(lookup->GetTransitionTarget());
+    Representation field_representation = value->OptimalRepresentation();
+    Handle<HeapType> field_type = value->OptimalType(
+        lookup->isolate(), field_representation);
     Map::GeneralizeRepresentation(
         target, target->LastAdded(),
-        value->OptimalRepresentation(), FORCE_FIELD);
+        field_representation, field_type, FORCE_FIELD);
     // Lookup the transition again since the transition tree may have changed
     // entirely by the migration above.
     receiver->map()->LookupTransition(*holder, *name, lookup);
     if (!lookup->IsTransition()) return false;
     return ic->TryMarkMonomorphicPrototypeFailure(name);
   }
 
   return true;
 }
 
@@ skipping 1696 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal