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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/64491] [5 Regression] incorrect warning: loop exit may only be reached after undefined behavior
Date: Wed, 18 Feb 2015 16:28:00 -0000	[thread overview]
Message-ID: <bug-64491-4-kIpTw6M9LV@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-64491-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64491

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Andrew Stubbs from comment #8)
> Just silencing the warning may not be enough. The compiler may optimize away
> loop exit conditions based on this analysis. The warning mirrors the logic
> rather than shares it (due to the way the logic is distributed) so this may
> not actually be a problem, in this case, but I'd have to look closer.

Sure, it is desirable if the compiler optimizes away the loop exit test, it
really is dead, because the loop will always be exit through the other loop
exit earlier.  But there is no user bug in there, so you shouldn't emit a false
positive.


  parent reply	other threads:[~2015-02-18 16:28 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-04 20:24 [Bug c++/64491] New: " stuwph at live dot de
2015-01-04 20:46 ` [Bug c++/64491] " redi at gcc dot gnu.org
2015-01-10 15:58 ` joona.kiiski at iki dot fi
2015-01-10 16:04 ` joona.kiiski at iki dot fi
2015-01-10 16:49 ` [Bug c++/64491] [5 Regression] incorrect " Joost.VandeVondele at mat dot ethz.ch
2015-01-11 22:10 ` [Bug middle-end/64491] " joona.kiiski at gmail dot com
2015-01-12  7:18 ` Joost.VandeVondele at mat dot ethz.ch
2015-02-09  0:06 ` pinskia at gcc dot gnu.org
2015-02-18 13:57 ` jakub at gcc dot gnu.org
2015-02-18 16:25 ` ams at gcc dot gnu.org
2015-02-18 16:28 ` jakub at gcc dot gnu.org [this message]
2015-02-20 11:28 ` ams at gcc dot gnu.org
2015-02-24 17:01 ` ams at gcc dot gnu.org
2015-02-24 19:18 ` jakub at gcc dot gnu.org
2015-03-18 12:50 ` rguenth at gcc dot gnu.org
2015-03-18 12:53 ` jakub at gcc dot gnu.org
2015-03-18 14:27 ` ams at gcc dot gnu.org
2015-03-18 14:29 ` ams at gcc dot gnu.org

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