Add inline caches for loading non-existing properties.

src/stub-cache.cc

 // Copyright 2006-2009 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 75 matching lines @@
     *secondary = *primary;
   }
 
   // Update primary cache.
   primary->key = name;
   primary->value = code;
   return code;
 }
 
 
+Object* StubCache::ComputeLoadNonExisting(String* name, JSObject* receiver) {
+  // The code stub for loading non-existing properties can be reused
+  // for all names, so we use the empty_string as the name in the map
+  // code cache.
+  Code::Flags flags =
+      Code::ComputeMonomorphicFlags(Code::LOAD_IC, NON_EXISTING);
+  Object* code = receiver->map()->FindInCodeCache(Heap::empty_string(), flags);
+  if (code->IsUndefined()) {
+    LoadStubCompiler compiler;
+    code = compiler.CompileLoadNonExisting(receiver);
+    if (code->IsFailure()) return code;
+    PROFILE(CodeCreateEvent(Logger::LOAD_IC_TAG,
+                            Code::cast(code),
+                            Heap::empty_string()));
+    Object* result = receiver->map()->UpdateCodeCache(Heap::empty_string(),
+                                                      Code::cast(code));
+    if (result->IsFailure()) return result;
+  }
+  return Set(name, receiver->map(), Code::cast(code));
+}
+
+
 Object* StubCache::ComputeLoadField(String* name,
                                     JSObject* receiver,
                                     JSObject* holder,
                                     int field_index) {
   Code::Flags flags = Code::ComputeMonomorphicFlags(Code::LOAD_IC, FIELD);
   Object* code = receiver->map()->FindInCodeCache(name, flags);
   if (code->IsUndefined()) {
     LoadStubCompiler compiler;
     code = compiler.CompileLoadField(receiver, holder, field_index, name);
     if (code->IsFailure()) return code;
@@ skipping 1020 matching lines @@
   if (!result->IsFailure()) {
     Code* code = Code::cast(result);
     USE(code);
     PROFILE(CodeCreateEvent(Logger::STUB_TAG, code, "ConstructStub"));
   }
   return result;
 }
 
 
 } }  // namespace v8::internal