[Bug rtl-optimization/44867] New: 10% runtime regression on Polyhedron channel banchmark from 29. June 2010

["ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

According to [1] and [2], a 10% runtime regression has hit "channel" Polyhedron
benchmark between 29th and 30th of July.

My best uneducated blind shot would be r161570:

        * recog.c (peep2_do_rebuild_jump_labels, peep2_do_cleanup_cfg): New
        static variables.
        (peep2_buf_position): New static function.
        (peep2_regno_dead_p, peep2_reg_dead_p, peep2_find_free_register,
        peephole2_optimize): Use it.
        (peep2_attempt, peep2_update_life): New static functions, broken out
        of peephole2_optimize.
        (peep2_fill_buffer): New static function.
        (peephole2_optimize): Change the main loop to try to fill the buffer
        with the maximum number of insns before matching them against
        peepholes.  Use a forward scan.  Remove special case for targets with
        conditional execution.
        * genrecog.c (change_state): Delete dead code.
        * config/i386/i386.md (peephole2 for arithmetic ops with memory):
        Rewrite so as not to expect the second insn to have had a peephole
        applied yet.

I will try to confirm this via bisection.

[1] http://gcc.opensuse.org/c++bench/polyhedron/polyhedron-summary.txt-2-0.html
[2] http://gcc.opensuse.org/c++bench/polyhedron/polyhedron-summary.txt


-- 
           Summary: 10% runtime regression on Polyhedron channel banchmark
                    from 29. June 2010
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ubizjak at gmail dot com
 GCC build triplet: x86_64-pc-linux-gnu
  GCC host triplet: x86_64-pc-linux-gnu
GCC target triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44867