- Added fast case for extending the JSObject properties storage....

src/ic.cc

 // Copyright 2006-2008 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 856 matching lines @@
   // stub cache.
   Object* code = NULL;
   switch (type) {
     case FIELD: {
       code = StubCache::ComputeStoreField(*name, *receiver,
                                           lookup->GetFieldIndex());
       break;
     }
     case MAP_TRANSITION: {
       if (lookup->GetAttributes() != NONE) return;
-      if (receiver->map()->unused_property_fields() == 0) return;
       HandleScope scope;
-      ASSERT(type == MAP_TRANSITION &&
-             (receiver->map()->unused_property_fields() > 0));
+      ASSERT(type == MAP_TRANSITION);
       Handle<Map> transition(lookup->GetTransitionMap());
       int index = transition->PropertyIndexFor(*name);
       code = StubCache::ComputeStoreField(*name, *receiver, index, *transition);
       break;
     }
     case CALLBACKS: {
       if (!lookup->GetCallbackObject()->IsAccessorInfo()) return;
       AccessorInfo* callback = AccessorInfo::cast(lookup->GetCallbackObject());
       if (v8::ToCData<Address>(callback->setter()) == 0) return;
       code = StubCache::ComputeStoreCallback(*name, *receiver, callback);
       break;
     }
     case INTERCEPTOR: {
       code = StubCache::ComputeStoreInterceptor(*name, *receiver);
       break;
     }
     default:
       return;
   }
 
   // If we're unable to compute the stub (not enough memory left), we
   // simply avoid updating the caches.
   if (code->IsFailure()) return;
 
   // Patch the call site depending on the state of the cache.
   if (state == UNINITIALIZED || state == MONOMORPHIC_PROTOTYPE_FAILURE) {
     set_target(Code::cast(code));
   } else if (state == MONOMORPHIC) {
-    set_target(megamorphic_stub());
+    // Only move to mega morphic if the target changes.
+    if (target() != Code::cast(code)) set_target(megamorphic_stub());
   }
 
 #ifdef DEBUG
   TraceIC("StoreIC", name, state, target());
 #endif
 }
 
 
 Object* KeyedStoreIC::Store(State state,
                             Handle<Object> object,
@@ skipping 69 matching lines @@
   Object* code = NULL;
 
   switch (type) {
     case FIELD: {
       code = StubCache::ComputeKeyedStoreField(*name, *receiver,
                                                lookup->GetFieldIndex());
       break;
     }
     case MAP_TRANSITION: {
       if (lookup->GetAttributes() == NONE) {
-        if (receiver->map()->unused_property_fields() == 0) return;
         HandleScope scope;
-        ASSERT(type == MAP_TRANSITION &&
-               (receiver->map()->unused_property_fields() > 0));
+        ASSERT(type == MAP_TRANSITION);
         Handle<Map> transition(lookup->GetTransitionMap());
         int index = transition->PropertyIndexFor(*name);
         code = StubCache::ComputeKeyedStoreField(*name, *receiver,
                                                  index, *transition);
         break;
       }
       // fall through.
     }
     default: {
       // Always rewrite to the generic case so that we do not
@@ skipping 95 matching lines @@
 Object* StoreIC_Miss(Arguments args) {
   NoHandleAllocation na;
   ASSERT(args.length() == 3);
   StoreIC ic;
   IC::State state = IC::StateFrom(ic.target(), args[0]);
   return ic.Store(state, args.at<Object>(0), args.at<String>(1),
                   args.at<Object>(2));
 }
 
 
+// Extend storage is called in a store inline cache when
+// it is necessary to extend the properties array of a
+// JSObject.
+Object* StoreIC_ExtendStorage(Arguments args) {
+  NoHandleAllocation na;
+  ASSERT(args.length() == 3);
+
+  // Convert the parameters
+  JSObject* object = JSObject::cast(args[0]);
+  Map* transition = Map::cast(args[1]);
+  Object* value = args[2];
+
+  // Check the object has run out out property space.
+  ASSERT(object->HasFastProperties());
+  ASSERT(object->map()->unused_property_fields() == 0);
+
+  // Expand the properties array.
+  FixedArray* old_storage = object->properties();
+  int new_unused = transition->unused_property_fields();
+  int  new_size = old_storage->length() + new_unused + 1;

[Mads Ager (chromium), 2008/10/03 09:12:45]

Please remove extra space between type and name.

+  Object* result = old_storage->CopySize(new_size);
+  if (result->IsFailure()) return result;
+  FixedArray* new_storage = FixedArray::cast(result);
+  new_storage->set(old_storage->length(), value);
+
+  // Set the new property value and do the map tranistion.
+  object->set_properties(new_storage);
+  object->set_map(transition);
+
+  // Return the stored value.
+  return value;
+}
+
+
 void StoreIC::GenerateInitialize(MacroAssembler* masm) {
   Generate(masm, ExternalReference(IC_Utility(kStoreIC_Miss)));
 }
 
 
 void StoreIC::GenerateMiss(MacroAssembler* masm) {
   Generate(masm, ExternalReference(IC_Utility(kStoreIC_Miss)));
 }
 
 
@@ skipping 25 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal