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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/43716] [4.6/4.7/4.8 Regression] Revision 158105 miscompiles doduc.f90
Date: Mon, 23 Jul 2012 08:13:00 -0000	[thread overview]
Message-ID: <bug-43716-4-WncG4TMG2V@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-43716-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43716

--- Comment #40 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-07-23 08:12:55 UTC ---
tree if-conversion happily executes both arms of the conditional
unconditionally
with -ffast-math, so for example

  if (x != 0)
    tem = y / x;
  else
    tem = 0.;
  ... do sth with tem ...

will execute y / x unconditionally based on the fact that it cannot trap.
So simply generation of NaNs is not what you should check for, but
"usage" of 'tem' with NaN in the above should be (it shouldn't be used
if x is zero).


  parent reply	other threads:[~2012-07-23  8:13 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-43716-4@http.gcc.gnu.org/bugzilla/>
2012-07-21 10:42 ` ubizjak at gmail dot com
2012-07-21 10:45 ` ubizjak at gmail dot com
2012-07-21 10:49 ` ubizjak at gmail dot com
2012-07-21 11:31 ` ubizjak at gmail dot com
2012-07-21 12:17 ` ubizjak at gmail dot com
2012-07-21 12:35 ` ubizjak at gmail dot com
2012-07-21 13:40 ` dominiq at lps dot ens.fr
2012-07-21 13:52 ` ubizjak at gmail dot com
2012-07-21 14:43 ` dominiq at lps dot ens.fr
2012-07-22 10:48 ` dominiq at lps dot ens.fr
2012-07-23  8:13 ` rguenth at gcc dot gnu.org [this message]
2012-12-07  9:21 ` rguenth at gcc dot gnu.org
2012-12-07 13:40 ` dominiq at lps dot ens.fr
2012-12-07 14:29 ` rguenth at gcc dot gnu.org
2012-12-18  9:14 ` jakub at gcc dot gnu.org
2012-12-18 10:24 ` jakub at gcc dot gnu.org
2013-01-08 18:26 ` dominiq at lps dot ens.fr
2013-01-08 19:24 ` ubizjak at gmail dot com
2013-01-08 19:53 ` dominiq at lps dot ens.fr
2013-01-09  8:52 ` richard.guenther at gmail dot com

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