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* [Bug tree-optimization/18754] New: unrolling happens too late/SRA does not happen late enough
@ 2004-12-01 14:39 pinskia at gcc dot gnu dot org
  2004-12-06  5:01 ` [Bug tree-optimization/18754] " pinskia at gcc dot gnu dot org
                   ` (9 more replies)
  0 siblings, 10 replies; 17+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-12-01 14:39 UTC (permalink / raw)
  To: gcc-bugs

Take the following code:
struct X { float array[4]; };

X a,b;

float foobar () {
  float s = 0;
  X c;
  for (unsigned int d=0; d<4; ++d)
    c.array[d] = a.array[d] * b.array[d];
  for (unsigned int d=0; d<4; ++d)
    s+=c.array[d];
  return s;
}

With -O3 -funroll-loops -fno-ivopts -ffast-math (the fno-ivopts is because there are some ADDR_EXPR 
which we don't mark as invariant/constant which I will file in another bug) we get in .vars:
  c.array[0] = a.array[0] * b.array[0];
  c.array[1] = a.array[1] * b.array[1];
  c.array[2] = a.array[2] * b.array[2];
  D.1572 = a.array[3] * b.array[3];
  c.array[3] = D.1572;
  return D.1572 + c.array[0] + c.array[1] + c.array[2];

Note how we could SRA c.array.

-- 
           Summary: unrolling happens too late/SRA does not happen late
                    enough
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, TREE
          Severity: enhancement
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18754


^ permalink raw reply	[flat|nested] 17+ messages in thread
end of thread, other threads:[~2008-04-27 17:17 UTC | newest]

Thread overview: 17+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
     [not found] <bug-18754-6528@http.gcc.gnu.org/bugzilla/>
2006-03-05 21:27 ` [Bug tree-optimization/18754] unrolling happens too late/SRA does not happen late enough pinskia at gcc dot gnu dot org
2006-03-06 14:30 ` rguenth at gcc dot gnu dot org
2007-02-10  9:40 ` pinskia at gcc dot gnu dot org
2007-08-12 16:59 ` belyshev at depni dot sinp dot msu dot ru
2008-04-22  9:32 ` rguenth at gcc dot gnu dot org
2008-04-27 16:28 ` rguenth at gcc dot gnu dot org
2008-04-27 17:17 ` rguenth at gcc dot gnu dot org
2004-12-01 14:39 [Bug tree-optimization/18754] New: " pinskia at gcc dot gnu dot org
2004-12-06  5:01 ` [Bug tree-optimization/18754] " pinskia at gcc dot gnu dot org
2004-12-16 17:09 ` rguenth at tat dot physik dot uni-tuebingen dot de
2005-01-20 10:57 ` rguenth at tat dot physik dot uni-tuebingen dot de
2005-01-20 14:49 ` pinskia at gcc dot gnu dot org
2005-01-20 14:57 ` rguenth at tat dot physik dot uni-tuebingen dot de
2005-01-20 15:06 ` dberlin at dberlin dot org
2005-01-20 15:07 ` pinskia at gcc dot gnu dot org
2005-01-20 15:15 ` rguenth at tat dot physik dot uni-tuebingen dot de
2005-01-21 16:08 ` rguenth at tat dot physik dot uni-tuebingen dot de
2005-05-07 21:00 ` pinskia at gcc dot gnu dot org

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