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Date: Tue, 29 Jun 2010 09:11:00 -0000
Subject: [Bug tree-optimization/44710]  New: If-conversion generates redundant statements
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From: "irar at il dot ibm dot com" <gcc-bugzilla@gcc.gnu.org>
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Starting from revision 160625
(http://gcc.gnu.org/ml/gcc-patches/2010-06/msg01155.html) if-conversion
generates redundant statements for 

  for (i = 0; i < N; i++)
    if (arr[i] < limit)
      {
        pos = i + 1;
        limit = arr[i];
      }


  # pos_22 = PHI <pos_1(4), 1(2)>
  # i_23 = PHI <prephitmp.8_2(4), 0(2)>
  # limit_24 = PHI <limit_4(4), 1.28e+2(2)>
  # ivtmp.9_18 = PHI <ivtmp.9_17(4), 64(2)>
  limit_9 = arr[i_23];
  pos_10 = i_23 + 1;
  D.4534_12 = limit_9 < limit_24;                       <-----
  pretmp.7_3 = i_23 + 1;
  D.4535_20 = limit_9 >= limit_24;                      <-----
  pos_1 = [cond_expr] limit_9 >= limit_24 ? pos_22 : pos_10;
  limit_4 = [cond_expr] limit_9 >= limit_24 ? limit_24 : limit_9;
  prephitmp.8_2 = [cond_expr] limit_9 >= limit_24 ? pretmp.7_3 : pos_10;
  ivtmp.9_17 = ivtmp.9_18 - 1;
  D.4536_19 = D.4534_12 || D.4535_20;                   <-----
  if (ivtmp.9_17 != 0)
    goto <bb 4>;
  else
    goto <bb 5>;

The statements are removed by later dce pass, but they interfere with my
attempts to vectorize this loop.


-- 
           Summary: If-conversion generates redundant statements
           Product: gcc
           Version: 4.6.0
            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=44710