Optimize the allocation of small, non-nested literal...

bleeding_edge/src/heap.cc

 // Copyright 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 2243 matching lines @@
   // To get fast allocation and map sharing for arguments objects we
   // allocate them based on an arguments boilerplate.
 
   // This calls Copy directly rather than using Heap::AllocateRaw so we
   // duplicate the check here.
   ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC);
 
   JSObject* boilerplate =
       Top::context()->global_context()->arguments_boilerplate();
 
-  // Make the clone.
-  Map* map = boilerplate->map();
-  int object_size = map->instance_size();
-  Object* result = AllocateRaw(object_size, NEW_SPACE, OLD_POINTER_SPACE);
+  // Check that the size of the boilerplate matches our
+  // expectations. The ArgumentsAccessStub::GenerateNewObject relies
+  // on the size being a known constant.
+  ASSERT(kArgumentsObjectSize == boilerplate->map()->instance_size());
+
+  // Do the allocation.
+  Object* result =
+      AllocateRaw(kArgumentsObjectSize, NEW_SPACE, OLD_POINTER_SPACE);
   if (result->IsFailure()) return result;
 
   // Copy the content. The arguments boilerplate doesn't have any
   // fields that point to new space so it's safe to skip the write
   // barrier here.
   CopyBlock(reinterpret_cast<Object**>(HeapObject::cast(result)->address()),
             reinterpret_cast<Object**>(boilerplate->address()),
-            object_size);
+            kArgumentsObjectSize);
 
   // Set the two properties.
   JSObject::cast(result)->InObjectPropertyAtPut(arguments_callee_index,
                                                 callee);
   JSObject::cast(result)->InObjectPropertyAtPut(arguments_length_index,
                                                 Smi::FromInt(length),
                                                 SKIP_WRITE_BARRIER);
 
   // Check the state of the object
   ASSERT(JSObject::cast(result)->HasFastProperties());
@@ skipping 1796 matching lines @@
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 List<Object*> ExternalStringTable::new_space_strings_;
 List<Object*> ExternalStringTable::old_space_strings_;
 
 } }  // namespace v8::internal