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Date: Tue, 26 Jul 2005 13:59:00 -0000
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From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
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Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug tree-optimization/19581] Missed store motion on the tree level
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------- Additional Comments From rguenth at gcc dot gnu dot org  2005-07-26 13:29 -------
For a reduced array with only 4 elements (I know - this should be a --param) we
now get in .vars (with the array aliasing patch):

f (n)
{
  int n.39;
  unsigned int ivtmp.33;
  int lsm_tmp.32;
  int lsm_tmp.31;
  int lsm_tmp.30;
  int lsm_tmp.29;

<bb 0>:
  n.39 = n - 1;
  if (n.39 != 0) goto <L6>; else goto <L2>;

<L6>:;
  lsm_tmp.29 = r[2];
  lsm_tmp.30 = r[1];
  lsm_tmp.31 = r[3];
  lsm_tmp.32 = r[0];
  ivtmp.33 = 0;

<L0>:;
  lsm_tmp.32 = lsm_tmp.32 + lsm_tmp.31;
  lsm_tmp.30 = lsm_tmp.32 + lsm_tmp.30;
  lsm_tmp.29 = lsm_tmp.30 + lsm_tmp.29;
  lsm_tmp.31 = lsm_tmp.31 + lsm_tmp.29;
  ivtmp.33 = ivtmp.33 + 1;
  if (ivtmp.33 != (unsigned int) n.39) goto <L0>; else goto <L10>;

<L10>:;
  r[2] = lsm_tmp.29;
  r[1] = lsm_tmp.30;
  r[3] = lsm_tmp.31;
  r[0] = lsm_tmp.32;

<L2>:;
  return;

}

and the asm loop looks like

.L4:
        addl    %edx, %eax
        incl    %esi
        addl    %eax, %ecx
        addl    %ecx, %ebx
        addl    %ebx, %edx
        cmpl    %edi, %esi
        jne     .L4

as in exactly what you want.  Don't hold your breath for 4.1, though.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-06-09 16:37:28         |2005-07-26 13:29:06
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19581