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From: "changpeng.fang at amd dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/43657] [4.3/4.4/4.5/4.6 Regression] -ftree-loop-linear causes FAIL: gcc.dg/vect/vect-cond-5.c execution test
Date: Tue, 19 Oct 2010 21:28:00 -0000	[thread overview]
Message-ID: <20101019212800.zFzkmzRGgGqElY4kdfxMecBqpYV04QG28uIzxi3cl24@z> (raw)
In-Reply-To: <bug-43657-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43657

--- Comment #4 from Changpeng Fang <changpeng.fang at amd dot com> 2010-10-19 21:27:46 UTC ---
 for (k = 0; k < 32; k++)
    {
      res = 0;
      for (j = 0; j < 32; j++) 
        for (i = 0; i < 32; i++)
          { 
            next = a[i][j]; 
            res = c > cond_array[i+k][j] ? next : res;
          }

      out[k] = res;
    }


gcc interchanges i and j loops, which is not legal in this case.
Apparently, res takes the last value of a[i][j] that satisfies the 
condition c > cond_array[i+k][j]. As a result, change in the 
reference order will get a different value for res.

Anyone knows where to do this legality check?

What about the interchange in Graphite for this case?


       reply	other threads:[~2010-10-19 21:28 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-43657-4@http.gcc.gnu.org/bugzilla/>
2010-10-19 21:28 ` changpeng.fang at amd dot com [this message]
2011-01-16 12:29 ` aoliva at gcc dot gnu.org
2011-01-16 13:23 ` aoliva at gcc dot gnu.org
2011-01-18 20:56 ` spop at gcc dot gnu.org
2011-01-18 20:59 ` spop at gcc dot gnu.org
2011-01-25 21:29 ` spop at gcc dot gnu.org
2011-01-25 21:30 ` spop at gcc dot gnu.org
2011-02-02 18:03 ` dnovillo at gcc dot gnu.org
2010-04-05 23:00 [Bug tree-optimization/43657] New: [4.3/4.4/4.5 " zsojka at seznam dot cz
2010-04-09 13:00 ` [Bug tree-optimization/43657] [4.3/4.4/4.5/4.6 " rguenth at gcc dot gnu dot org
2010-05-22 18:36 ` rguenth at gcc dot gnu dot org
2010-05-26 11:15 ` jakub at gcc dot gnu dot org

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