[Bug tree-optimization/37416] New: Failure to return number of loop iterations

["irar at il dot ibm dot com" <gcc-bugzilla at gcc dot gnu dot org>]

For the loop in testcase of pr36630:

void
foo (unsigned char *x, short y)
{
  short i;

  i = 2;
  while (i < y)
    {
      x[i - 1] = x[i];
      i = i + 1;
    }
}

we used to get 
# of iterations (short unsigned int) y_3(D) + 65533, bounded by 32764
and now we get scev_not_known.

Also Sebastian noticed (from pr36630):

> I also have remarked on one of the graphite testcases scop-matmult.c
> that we had a regression in the precision of the number of iterations from
> last graphite merge till yesterday's merge, i.e. from 138275 to 139870
> We used to have a symbolic number of iterations, but now the result
> is scev_dont_know.  I have not yet tracked this down to the patch that
> produced this regression.
> 
> Sebastian


-- 
           Summary: Failure to return number of  loop iterations
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: irar at il dot ibm dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37416