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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/28685] Multiple comparisons are not simplified
Date: Tue, 25 May 2010 08:12:00 -0000 [thread overview]
Message-ID: <20100525081155.15212.qmail@sourceware.org> (raw)
In-Reply-To: <bug-28685-1649@http.gcc.gnu.org/bugzilla/>
------- Comment #14 from rguenther at suse dot de 2010-05-25 08:11 -------
Subject: Re: Multiple comparisons are not simplified
On Mon, 24 May 2010, sandra at codesourcery dot com wrote:
> ------- Comment #13 from sandra at codesourcery dot com 2010-05-24 13:21 -------
> I'm working on a patch that fixes the test case in comment #5 (originally filed
> as PR 39874) and some other test cases by improving the comparison combination
> logic in both tree-ssa-ifcombine and tree-ssa-reassoc.
>
> The test case in comment #4 is a somewhat different problem -- maybe it is a
> VRP failure? The problem is figuring out the right place to attempt to combine
> the comparisons....
In this case it is probably phiopt that could recognize this (though
it does not do the kind of transformation). It could transform
<bb 2>:
eq_5 = a_2(D) == b_3(D);
if (a_2(D) < b_3(D))
goto <bb 4>;
else
goto <bb 3>;
<bb 3>:
<bb 4>:
# eq_1 = PHI <1(2), eq_5(3)>
return eq_1;
to
<bb 2>:
if (a_2(D) <= b_3(D))
goto <bb 4>;
else
goto <bb 3>;
<bb 3>:
<bb 4>:
# eq_1 = PHI <1(2), 0(3)>
return eq_1;
and eventually further if-convert that.
Richard.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28685
next prev parent reply other threads:[~2010-05-25 8:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-10 18:15 [Bug middle-end/28685] New: " uros at kss-loka dot si
2006-08-10 18:18 ` [Bug middle-end/28685] " pinskia at gcc dot gnu dot org
2008-04-30 15:13 ` rguenth at gcc dot gnu dot org
2008-09-06 16:34 ` ubizjak at gmail dot com
2008-10-12 20:46 ` rguenth at gcc dot gnu dot org
2009-04-24 9:24 ` rguenth at gcc dot gnu dot org
2009-04-24 9:25 ` rguenth at gcc dot gnu dot org
2009-06-24 7:49 ` steven at gcc dot gnu dot org
2009-06-24 9:15 ` rguenth at gcc dot gnu dot org
2009-09-17 10:25 ` ubizjak at gmail dot com
2010-05-07 2:32 ` sandra at codesourcery dot com
2010-05-08 3:44 ` sandra at codesourcery dot com
2010-05-08 15:54 ` sandra at gcc dot gnu dot org
2010-05-24 13:22 ` sandra at codesourcery dot com
2010-05-25 8:12 ` rguenther at suse dot de [this message]
2010-06-01 2:24 ` sandra at codesourcery dot com
2010-06-08 18:16 ` sandra at gcc dot gnu dot org
[not found] <bug-28685-4@http.gcc.gnu.org/bugzilla/>
2012-01-12 1:07 ` pinskia at gcc dot gnu.org
2012-02-05 12:42 ` ubizjak at gmail dot com
2012-02-06 21:37 ` ubizjak at gmail dot com
2012-04-22 12:42 ` ubizjak at gmail dot com
2012-04-22 12:46 ` ubizjak at gmail dot com
2012-04-22 12:48 ` ubizjak at gmail dot com
2014-10-31 4:02 ` pinskia at gcc dot gnu.org
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