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From: "wbrana at gmail dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug math/14412] Removal of sysdeps/x86_64/fpu/s_sincos.S causes regressions
Date: Fri, 26 Apr 2013 15:20:00 -0000 [thread overview]
Message-ID: <bug-14412-131-Ovt6kdaBKY@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-14412-131@http.sourceware.org/bugzilla/>
http://sourceware.org/bugzilla/show_bug.cgi?id=14412
--- Comment #24 from wbrana at gmail dot com 2013-04-26 15:20:54 UTC ---
(In reply to comment #10)
> If we fix sinf to be fast again it will be imprecise which is a critical bug
> for another class of users. There is no implementation that can satisfy all
> requirements from all users. At the very least the precise implementation is at
> least correct if slow. Therefore this is an enhancement request to make the
> implementation fast.
>
> We are working on the possibility of having 3 libm variants, fast, default, and
> precise. At that point -ffast-math will select the fast variant and provide a
> fast but imprecise implementation.
>
http://sourceware.org/bugzilla/show_bug.cgi?id=13658
impreciseness of fast sincos can't be critical bug because it took 15 years
(1997-2012)
to report this bug which means s_sincos.S is precise enough for 99% of apps.
s_sincos.S should be restored because slow sincos can break many apps
because most open source apps aren't properly tested and app devs aren't aware
that sincos is 50% slower since 2.16.
Only users will notice than e.g. new Ubuntu is slow but users usually can't
submit proper bug report like this one to app devs.
App devs won't know that they should add -ffast-math to restore performance.
Very few apps are using -ffast-math in present.
-ffast-math can add new bugs to apps which aren't broken by fast sincos.
New function named e.g. sincos_precise should be added to glibc for 1% apps
which are affected by impreciseness of fast sincos.
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next prev parent reply other threads:[~2013-04-26 15:20 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-26 21:08 [Bug math/14412] New: Removal of sysdeps/x86_64/fpu/s_sincos.S causes pdf rendering time regression markus at trippelsdorf dot de
2012-07-26 21:09 ` [Bug math/14412] " markus at trippelsdorf dot de
2012-07-26 21:14 ` markus at trippelsdorf dot de
2012-07-27 6:44 ` aj at suse dot de
2012-07-27 7:18 ` markus at trippelsdorf dot de
2012-07-27 12:33 ` markus at trippelsdorf dot de
2012-07-28 22:15 ` bugdal at aerifal dot cx
2012-08-03 3:51 ` carlos_odonell at mentor dot com
2012-08-09 10:14 ` markus at trippelsdorf dot de
2012-08-19 9:31 ` markus at trippelsdorf dot de
2012-08-19 9:37 ` [Bug math/14412] Removal of sysdeps/x86_64/fpu/s_sincos.S causes regressions markus at trippelsdorf dot de
2012-12-03 22:13 ` davem at davemloft dot net
2012-12-04 0:00 ` carlos at systemhalted dot org
2013-04-25 21:48 ` wbrana at gmail dot com
2013-04-25 23:35 ` carlos at redhat dot com
2013-04-25 23:58 ` bugdal at aerifal dot cx
2013-04-26 0:14 ` bugdal at aerifal dot cx
2013-04-26 2:55 ` siddhesh at redhat dot com
2013-04-26 3:08 ` bugdal at aerifal dot cx
2013-04-26 3:50 ` siddhesh at redhat dot com
2013-04-26 6:29 ` markus at trippelsdorf dot de
2013-04-26 6:40 ` jakub at redhat dot com
2013-04-26 10:00 ` siddhesh at redhat dot com
2013-04-26 11:31 ` joseph at codesourcery dot com
2013-04-26 11:33 ` joseph at codesourcery dot com
2013-04-26 11:42 ` siddhesh at redhat dot com
2013-04-26 13:52 ` bugdal at aerifal dot cx
2013-04-26 13:55 ` bugdal at aerifal dot cx
2013-04-26 15:07 ` joseph at codesourcery dot com
2013-04-26 15:20 ` wbrana at gmail dot com [this message]
2013-04-29 10:29 ` siddhesh at redhat dot com
2013-04-29 10:50 ` wbrana at gmail dot com
2013-04-29 11:55 ` bugdal at aerifal dot cx
2013-04-29 12:32 ` wbrana at gmail dot com
2013-04-29 13:21 ` Ondřej Bílka
2013-04-29 13:21 ` neleai at seznam dot cz
2013-04-29 13:28 ` bugdal at aerifal dot cx
2013-04-29 14:04 ` Ondřej Bílka
2013-04-29 13:32 ` bugdal at aerifal dot cx
2013-04-29 13:36 ` wbrana at gmail dot com
2013-04-29 13:44 ` siddhesh at redhat dot com
2013-04-29 13:51 ` bugdal at aerifal dot cx
2013-04-29 14:04 ` neleai at seznam dot cz
2013-04-29 14:19 ` siddhesh at redhat dot com
2013-04-29 14:29 ` markus at trippelsdorf dot de
2013-04-29 14:48 ` bugdal at aerifal dot cx
2013-04-29 16:29 ` Ondřej Bílka
2013-04-29 16:29 ` neleai at seznam dot cz
2013-04-29 17:30 ` bugdal at aerifal dot cx
2013-04-29 20:58 ` joseph at codesourcery dot com
2013-04-30 5:41 ` siddhesh at redhat dot com
2013-04-30 21:37 ` bugdal at aerifal dot cx
2013-05-01 22:25 ` bugdal at aerifal dot cx
2013-07-16 20:08 ` nshmyrev at yandex dot ru
2013-09-07 6:55 ` carlos at redhat dot com
2014-02-06 18:31 ` jsm28 at gcc dot gnu.org
2014-06-17 18:55 ` fweimer at redhat dot com
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