[Bug rtl-optimization/51933] [4.7 Regression] Wrong-code due to -free

["ebotcazou at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51933

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-01-21
                 CC|                            |ebotcazou at gcc dot
                   |                            |gnu.org
         AssignedTo|unassigned at gcc dot       |ebotcazou at gcc dot
                   |gnu.org                     |gnu.org
     Ever Confirmed|0                           |1

--- Comment #2 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-01-21 15:44:46 UTC ---
> But then when make_defs_and_copies_lists is called on the QImode -> DImode
> extension, we reach:
>       /* Initialize the work list.  */
>       if (!get_defs (extend_insn, src_reg, &work_list))
>         {
>           VEC_free (rtx, heap, work_list);
>           /* The number of defs being equal to zero can only mean that all the
>              definitions have been previously merged.  */
>           return 2;
>         }
> and because the definition has been changed already.

Yes, this particular return embodies some implicit assumptions...  Will fix.