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Date: Tue, 09 Sep 2008 22:04:00 -0000
Subject: [Bug rtl-optimization/37451]  New: Extra addition for doloop in some cases
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Simple testcase:
/* { dg-do compile } */
/* { dg-options "-O2" } */

int f(int l, int *a)
{
  int i;
  for(i = 0;i < l; i++)
    a[i] = i;
  return l;
}

/* We should be able to do this loop without adding -1 to the l
   to get the number of iterations with this loop still doing a do-loop. */
/* The place where we were getting an extra -1 is when converting from 32bits
   to 64bits as the ctr register is used as 64bits on powerpc64. */
/* { dg-final { scan-assembler-not "-1" } } */
/* { dg-final { scan-assembler "bdnz" } } */
/* { dg-final { scan-assembler-times "mtctr" 1 } } */

---- CUT ---
The issue is that we zero extend before correcting the count of the iterations.


-- 
           Summary: Extra addition for doloop in some cases
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
GCC target triplet: powerpc64-*-*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37451