[Bug lto/51635] [4.7 regression] ICE in in dwarf2out_finish, at dwarf2out.c:22494 when building Firefox's libxul

["markus at trippelsdorf dot de" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51635

--- Comment #5 from Markus Trippelsdorf <markus at trippelsdorf dot de> 2011-12-20 15:31:47 UTC ---
(In reply to comment #4)
> Doesn't work.  Instead testing a similar
> 
> Index: gcc/lto/lto.c
> ===================================================================
> --- gcc/lto/lto.c       (revision 182525)
> +++ gcc/lto/lto.c       (working copy)
> @@ -845,6 +845,14 @@ uniquify_nodes (struct data_in *data_in,
>                     if (ix < i)
>                       lto_fixup_types (f2);
>                     streamer_tree_cache_insert_at (cache, f1, ix);
> +                   /* Make sure that the type of a TYPE_DECL refers
> +                      to the type decl that prevails in the prevailing
> +                      record or union type.  */
> +                   if (TREE_CODE (f1) == TYPE_DECL)
> +                     {
> +                       tree f1t = gimple_register_type (TREE_TYPE (f1));
> +                       TYPE_NAME (f1t) = f1;
> +                     }
>                   }
>             }

This one is extremely slow. lto1 has already used 12min of CPU time when
linking libxul and is still running... (3min is normal)

"perf top" shows:
 27.92%  lto1                           [.] lto_read_decls
 14.79%  lto1                           [.] htab_find_slot_with_hash
  9.37%  lto1                           [.] gimple_type_eq
  6.39%  libc-2.14.90.so                [.] _int_malloc
  5.60%  [kernel]                       [k] 0xffffffff81037d72
  4.80%  lto1                           [.] gtc_visit
  3.68%  libc-2.14.90.so                [.] memset