[Bug tree-optimization/36038] New: miscompiled loop in perlbmk for -Os

[janis at gcc dot gnu dot org]

Test 253.perlbmk from SPEC CPU2000 gets wrong answers with current trunk on
powerpc64-unknown-linux-gnu when compiled with "-m64 -Os" due to wrong code
generated for this loop:

  while (--count)
    *dst-- = *src--;

where dst and src are of type "struct sv **".  I'll attach a simplified
testcase
 in which dst and src are of type "long long *".

The failure begins with this patch:

    http://gcc.gnu.org/viewcvs?view=rev&rev=133102

    r133102 | rguenth | 2008-03-11 09:36:51 +0000 (Tue, 11 Mar 2008)


-- 
           Summary: miscompiled loop in perlbmk for -Os
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: janis at gcc dot gnu dot org
GCC target triplet: powerpc64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36038