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From: "rakdver at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/23855] loop header should also be pulled out of the inner loop too
Date: Fri, 07 Apr 2006 13:20:00 -0000	[thread overview]
Message-ID: <20060407132019.2901.qmail@sourceware.org> (raw)
In-Reply-To: <bug-23855-10053@http.gcc.gnu.org/bugzilla/>



------- Comment #14 from rakdver at gcc dot gnu dot org  2006-04-07 13:20 -------
(In reply to comment #11)
> I updated the patch for current mainline, but it still has issues for some
> common uses of loops:
> 
> void foo(int *ie, int *je, double *x)
> {
>   int i, j;
>   for (j=0; j<*je; ++j)
>     for (i=0; i<*ie; ++i)
>       x[i+j] = 0.0;
> }
> 
> After loop header copying we have
> 
>   if (*je > 0)
>     for (j=0; j<*je; ++j)
>       if (*ie > 0)
>         for (i=0; i<*ie; ++i)
>           x[i+j ] = 0.0;
> 
> note how in this form we see the condition *ie > 0 not invariant wrt the
> outer loop (because it does a memory load), but if we would run load-PRE
> between loop header copying and guard hoisting we would get

actually, thinking about it again, it should suffice to teach
invariant_without_guard_p about invariant memory loads, and this should just
work.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23855


  parent reply	other threads:[~2006-04-07 13:20 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-23855-10053@http.gcc.gnu.org/bugzilla/>
2006-01-15 20:08 ` pinskia at gcc dot gnu dot org
2006-01-15 20:12 ` pinskia at gcc dot gnu dot org
2006-01-15 20:15 ` rakdver at gcc dot gnu dot org
2006-01-17 22:28 ` rakdver at gcc dot gnu dot org
2006-01-20 23:57 ` rakdver at gcc dot gnu dot org
2006-02-28 18:23 ` patchapp at dberlin dot org
2006-04-07 11:35 ` rguenth at gcc dot gnu dot org
2006-04-07 12:01 ` rguenth at gcc dot gnu dot org
2006-04-07 12:57 ` rakdver at atrey dot karlin dot mff dot cuni dot cz
2006-04-07 13:20 ` rakdver at gcc dot gnu dot org [this message]
2006-04-09 23:51 ` rakdver at gcc dot gnu dot org
2006-04-10  0:04 ` rakdver at gcc dot gnu dot org
2006-04-10  8:11 ` rguenther at suse dot de
2006-04-10 10:24 ` rakdver at atrey dot karlin dot mff dot cuni dot cz
2006-04-10 11:56 ` rguenth at gcc dot gnu dot org
2006-10-24 13:56 ` rguenth at gcc dot gnu dot org
2006-10-24 13:59 ` rakdver at gcc dot gnu dot org
2006-10-24 14:23 ` dberlin at gcc dot gnu dot org
     [not found] <bug-23855-4@http.gcc.gnu.org/bugzilla/>
2011-10-19 19:11 ` pinskia at gcc dot gnu.org
2011-10-20  7:44 ` rguenther at suse dot de
2012-12-07 10:13 ` rguenth at gcc dot gnu.org
2014-02-05 14:13 ` rguenth at gcc dot gnu.org
2014-02-05 14:14 ` rguenth at gcc dot gnu.org
2014-02-05 14:27 ` rguenth at gcc dot gnu.org
2021-07-26  3:36 ` pinskia at gcc dot gnu.org

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