[Bug middle-end/32044] udivdi3 counterproductive, unwarranted use

[rguenth at gcc dot gnu dot org]

------- Comment #12 from rguenth at gcc dot gnu dot org  2007-05-23 15:13 
-------
So this is now an enhancement request for sccp to honor loop roll count or
basic-block frequency and cost of the replacement.  Note the loop appears to be
peeled twice before sccp already, but peeling doesn't decay probabilities
further.

Testcase:

int rmg(unsigned long long nsec)
{
   int sec = 0;
   nsec++;
   while (__builtin_expect(nsec >= 1000000000UL, 0)) {
      nsec -= 1000000000UL;
      ++sec;
   }
   return sec;
}

note this can be worked around with -fno-tree-scev-cprop as well.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rakdver at gcc dot gnu dot
                   |                            |org
           Severity|normal                      |enhancement
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-05-23 15:13:15
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32044