[Bug rtl-optimization/22563] [3.4/4.0/4.1 Regression] performance regression for gcc newer than 2.95

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

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-19 19:53 -------
There are a couple problems here, first we don't move the store to b_rec out side of the loop.  Doing 
that on the mainline, we remove the loop as it is now unswitchable and really just empty.

In fact that will not really be what you wantted but hey fast empty loops :).

The other issue is that we don't constant prop the constants as we have a BIT_FIELD_REF which is most 
likely the cause of the orginal regression in the first place though BIT_FIELD_REF was there in 2.95.3.

We can reduce your testcase down to stores really but that might not help the orginal code (except for 
the fact this is just a benchmark which is really useless).

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |missed-optimization
      Known to fail|                            |3.3.3 3.0.4 3.2.3 3.4.0
      Known to work|                            |2.95.3
   Last reconfirmed|0000-00-00 00:00:00         |2005-07-19 19:53:16
               date|                            |
            Summary|performance regression for  |[3.4/4.0/4.1 Regression]
                   |gcc newer than 2.95         |performance regression for
                   |                            |gcc newer than 2.95
   Target Milestone|---                         |3.4.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22563