Directly store the transition target on LookupResult in TransitionResult.

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 1116 matching lines @@
     holder = Handle<JSObject>(lookup->holder(), lookup->isolate());
   }
 
   // While normally LookupTransition gets passed the receiver, in this case we
   // pass the holder of the property that we overwrite. This keeps the holder in
   // the LookupResult intact so we can later use it to generate a prototype
   // chain check. This avoids a double lookup, but requires us to pass in the
   // receiver when trying to fetch extra information from the transition.
   receiver->map()->LookupTransition(*holder, *name, lookup);
   if (!lookup->IsTransition()) return false;
-  PropertyDetails target_details =
-      lookup->GetTransitionDetails(receiver->map());
+  PropertyDetails target_details = lookup->GetTransitionDetails();
   if (target_details.IsReadOnly()) return false;
 
   // 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 (!value->FitsRepresentation(target_details.representation())) {
-    Handle<Map> target(lookup->GetTransitionMapFromMap(receiver->map()));
+    Handle<Map> target(lookup->GetTransitionTarget());
     Map::GeneralizeRepresentation(
         target, target->LastAdded(),
         value->OptimalRepresentation(), 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;
     ic->MarkMonomorphicPrototypeFailure();
   }
   return true;
@@ skipping 152 matching lines @@
 
   Handle<JSObject> holder(lookup->holder());
   // Handlers do not use strict mode.
   StoreStubCompiler compiler(isolate(), kNonStrictMode, kind());
   switch (lookup->type()) {
     case FIELD:
       return compiler.CompileStoreField(receiver, lookup, name);
     case TRANSITION: {
       // Explicitly pass in the receiver map since LookupForWrite may have
       // stored something else than the receiver in the holder.
-      Handle<Map> transition(
-          lookup->GetTransitionTarget(receiver->map()), isolate());
-      int descriptor = transition->LastAdded();
-
-      DescriptorArray* target_descriptors = transition->instance_descriptors();
-      PropertyDetails details = target_descriptors->GetDetails(descriptor);
+      Handle<Map> transition(lookup->GetTransitionTarget());
+      PropertyDetails details = transition->GetLastDescriptorDetails();
 
       if (details.type() == CALLBACKS || details.attributes() != NONE) break;
 
       return compiler.CompileStoreTransition(
           receiver, lookup, transition, name);
     }
     case NORMAL:
       if (kind() == Code::KEYED_STORE_IC) break;
       if (receiver->IsJSGlobalProxy() || receiver->IsGlobalObject()) {
         // The stub generated for the global object picks the value directly
@@ skipping 1475 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal