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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/58143] [4.8/4.9 regression] wrong code at -O3
Date: Fri, 23 Aug 2013 12:59:00 -0000	[thread overview]
Message-ID: <bug-58143-4-JJkQG9Mdl1@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-58143-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58143

--- Comment #13 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Because the bug is in lim, so hacking around it in other parts of the compiler
and removing desirable optimizations just to mitigate the bug is not the right
way to fix it.

Either lim shouldn't move the expressions if they are conditional in the loop
body and might trigger undefined behavior in the place where it has been moved
to while it might not trigger undefined behavior originally, or lim should
transform them into expressions that won't trigger undefined behavior while
moving them if it can't prove this will not happen (in this case that would
mean performing the arithmetics in a type that doesn't have undefined behavior
on overflow).


  parent reply	other threads:[~2013-08-23 12:59 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-13  0:05 [Bug middle-end/58143] New: wrong code at -O3 on x86_64-linux-gnu su at cs dot ucdavis.edu
2013-08-13  0:08 ` [Bug middle-end/58143] " pinskia at gcc dot gnu.org
2013-08-13  0:24 ` su at cs dot ucdavis.edu
2013-08-14 21:11 ` mikpe at it dot uu.se
2013-08-20  0:21 ` bernd.edlinger at hotmail dot de
2013-08-20  0:59 ` bernd.edlinger at hotmail dot de
2013-08-20 22:25 ` bernd.edlinger at hotmail dot de
2013-08-21  8:53 ` bernd.edlinger at hotmail dot de
2013-08-21 17:41 ` [Bug tree-optimization/58143] [4.8/4.9 regression] wrong code at -O3 ebotcazou at gcc dot gnu.org
2013-08-21 18:02 ` jakub at gcc dot gnu.org
2013-08-21 21:50 ` bernd.edlinger at hotmail dot de
2013-08-23  9:15 ` bernd.edlinger at hotmail dot de
2013-08-23  9:16 ` jakub at gcc dot gnu.org
2013-08-23 12:08 ` bernd.edlinger at hotmail dot de
2013-08-23 12:59 ` jakub at gcc dot gnu.org [this message]
2013-08-25 22:08 ` bernd.edlinger at hotmail dot de
2013-08-28 21:30 ` bernd.edlinger at hotmail dot de
2013-10-15  8:15 ` rguenth at gcc dot gnu.org
2013-10-15  8:17 ` rguenth at gcc dot gnu.org
2013-10-15  8:39 ` bernd.edlinger at hotmail dot de
2013-10-15  9:05 ` rguenth at gcc dot gnu.org
2013-10-15  9:41 ` rguenth at gcc dot gnu.org
2013-10-15 11:03 ` rguenth at gcc dot gnu.org
2013-10-15 11:45 ` bernd.edlinger at hotmail dot de
2013-10-15 11:54 ` rguenther at suse dot de
2013-10-15 11:54 ` rguenth at gcc dot gnu.org
2013-10-15 13:21 ` bernd.edlinger at hotmail dot de
2013-10-15 13:27 ` rguenther at suse dot de
2013-10-15 13:36 ` mikpelinux at gmail dot com
2013-10-15 13:38 ` bernd.edlinger at hotmail dot de
2013-10-15 13:40 ` rguenther at suse dot de
2013-10-16  9:51 ` jakub at gcc dot gnu.org
2013-10-17  9:59 ` rguenth at gcc dot gnu.org
2013-10-17 10:08 ` [Bug tree-optimization/58143] [4.8 " rguenth at gcc dot gnu.org
2013-11-18 15:14 ` rguenth at gcc dot gnu.org
2013-11-18 15:15 ` rguenth at gcc dot gnu.org

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