[Bug lto/54312] uniquify_nodes takes 12% of Mozilla LTO build

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54312

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-08-20 
07:29:00 UTC ---
I don't see how we can do better.  Or well, we can put in an assert instead
(we stream TYPE_NEXT_VARIANT as NULL).

#ifdef ENABLE_CHECKING
          if (TYPE_MAIN_VARIANT (t) != t)
            {
              tem = TYPE_MAIN_VARIANT (t);
              while (tem && TYPE_NEXT_VARIANT (tem) != t)
                tem = TYPE_NEXT_VARIANT (tem);
              gcc_assert (!tem && !TYPE_NEXT_VARIANT (t));
            }
#endif