[Bug tree-optimization/54200] copyrename generates wrong debuginfo

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54200

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-08-08
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-08-08 
11:37:19 UTC ---
Apart from generic brokeness of copyrename (as it leaks DECL_NAMEs relevant
to debug info to places where another same DECL_NAME could be still live)
this specific issue is here:

          for (i = 0; i < gimple_phi_num_args (phi); i++)
            {
              tree arg = gimple_phi_arg (phi, i)->def;
              if (TREE_CODE (arg) == SSA_NAME)
                updated |= copy_rename_partition_coalesce (map, res, arg,
debug);
            }

copy_rename_partition_coalesce is symmetric, but we only can assign arg
the partition of res this way and at the end, if all args then have the same
partition assign that to res.