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From: "joseph at codesourcery dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/34678] Optimization generates incorrect code with -frounding-math option (#pragma STDC FENV_ACCESS not implemented) Date: Sun, 06 Jan 2008 16:21:00 -0000 [thread overview] Message-ID: <20080106151254.31117.qmail@sourceware.org> (raw) In-Reply-To: <bug-34678-5307@http.gcc.gnu.org/bugzilla/> ------- Comment #5 from joseph at codesourcery dot com 2008-01-06 15:12 ------- Subject: Re: Optimization generates incorrect code with -frounding-math option (#pragma STDC FENV_ACCESS not implemented) On Sat, 5 Jan 2008, rguenth at gcc dot gnu dot org wrote: > I wouldn't read the language this way. Because that will forcefully disable > all redundancy removing optimizations (which is what happens in this testcase). > What it currently guards is expression rewriting that changes the outcome if > a rounding mode different than round-to-nearest is used. My understanding has always been that -frounding-math should be usable for the code that calls rounding-mode-changing functions, rather than having no way to compile that code safely with GCC, as well as the code that does not call those functions but may execute with non-default rounding modes. The FENV_ACCESS pragma does not distinguish between the two. > The finer-grained control the documentation mentions should not be globbed > to -frounding-math IMHO. The pragma would in effect set -frounding-math for particular regions of code; it isn't more fine-grained regarding whether the code sets the mode or merely runs under a different mode. It is of course possible that -frounding-math should be split into multiple options (more fine-grained than the pragma) as the other related flags have been split over time. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34678
next prev parent reply other threads:[~2008-01-06 15:13 UTC|newest] Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top 2008-01-04 18:56 [Bug c/34678] New: Optimization generates incorrect code with -frounding-math option merkert at comcast dot net 2008-01-05 12:08 ` [Bug middle-end/34678] Optimization generates incorrect code with -frounding-math option (#pragma STDC FENV_ACCESS not implemented) rguenth at gcc dot gnu dot org 2008-01-05 16:48 ` merkert at comcast dot net 2008-01-05 21:00 ` joseph at codesourcery dot com 2008-01-05 21:29 ` rguenth at gcc dot gnu dot org 2008-01-06 16:21 ` joseph at codesourcery dot com [this message] 2008-01-06 17:19 ` rguenth at gcc dot gnu dot org 2008-01-06 18:03 ` joseph at codesourcery dot com 2008-10-15 15:44 ` rguenth at gcc dot gnu dot org 2008-10-15 21:31 ` vincent at vinc17 dot org 2008-10-15 22:15 ` rguenth at gcc dot gnu dot org 2008-10-15 22:35 ` vincent at vinc17 dot org 2008-10-16 9:46 ` rguenth at gcc dot gnu dot org 2008-10-16 11:58 ` merkert at comcast dot net 2008-10-16 14:21 ` vincent at vinc17 dot org 2008-10-16 16:40 ` joseph at codesourcery dot com 2008-10-16 17:41 ` vincent at vinc17 dot org [not found] <bug-34678-4@http.gcc.gnu.org/bugzilla/> 2010-10-26 10:33 ` paolo.carlini at oracle dot com 2011-02-08 2:02 ` pinskia at gcc dot gnu.org 2011-04-01 19:22 ` pinskia at gcc dot gnu.org 2013-11-11 9:30 ` nmm1 at cam dot ac.uk 2013-11-11 13:37 ` vincent-gcc at vinc17 dot net 2013-11-11 16:38 ` joseph at codesourcery dot com 2013-11-11 17:32 ` nmm1 at cam dot ac.uk 2014-01-10 11:40 ` vincent-gcc at vinc17 dot net 2014-01-14 14:58 ` vincent-gcc at vinc17 dot net 2014-01-14 15:13 ` nmm1 at cam dot ac.uk 2014-01-14 15:52 ` vincent-gcc at vinc17 dot net 2014-01-14 17:22 ` nmm1 at cam dot ac.uk 2014-01-14 23:16 ` vincent-gcc at vinc17 dot net 2014-02-16 10:03 ` jackie.rosen at hushmail dot com 2020-04-16 15:35 ` vincent-gcc at vinc17 dot net 2023-01-06 17:29 ` pinskia at gcc dot gnu.org 2023-01-06 17:31 ` pinskia at gcc dot gnu.org 2023-01-06 19:29 ` tkoenig at gcc dot gnu.org 2023-01-06 22:14 ` tkoenig at gcc dot gnu.org 2023-01-07 11:14 ` tkoenig at gcc dot gnu.org 2023-01-07 12:14 ` tkoenig at gcc dot gnu.org
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