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From: "rguenth 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: Tue, 15 Oct 2013 09:05:00 -0000 [thread overview]
Message-ID: <bug-58143-4-WMP8n0aSgG@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
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
--- Comment #19 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 31008
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31008&action=edit
untested patch
This is the alternative approach, re-writing stmts to a variant that does not
exhibit undefined signed overflow.
Division is not covered, neither is ABS_EXPR (or __builtin_abs ()). For
both I cannot see an easy way to rewrite them but make their execution
conditional (that requires more infrastructure changes in LIM though).
The patch should cover usual cases though, a testcase showing the issue
remaining with division and ABS_EXPR is appreciated (as SCEV analysis
only can do sensible stuff with +- and * it shouldn't be possible to
trigger a bug with the unrolling code - but clearly VRP could be
tricked into some invalid transform as it also handles division and
absolute).
POINTER_PLUS_EXPR handling also needs to be added, though that's one that
will eventually exhibit code generation regressions. But who knows ...
(testcase for POINTER_PLUS_EXPR also welcome).
next prev parent reply other threads:[~2013-10-15 9:05 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
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 [this message]
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 ` rguenth at gcc dot gnu.org
2013-10-15 11:54 ` rguenther at suse dot de
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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