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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/56888] memcpy implementation optimized as a call to memcpy
Date: Fri, 06 Jun 2014 11:54:00 -0000 [thread overview]
Message-ID: <bug-56888-4-XOMFllef1m@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-56888-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56888
--- Comment #32 from rguenther at suse dot de <rguenther at suse dot de> ---
On Fri, 6 Jun 2014, terra at gnome dot org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56888
>
> M Welinder <terra at gnome dot org> changed:
>
> What |Removed |Added
> ----------------------------------------------------------------------------
> CC| |terra at gnome dot org
>
> --- Comment #31 from M Welinder <terra at gnome dot org> ---
> Extra complication: the C library's memcpy may change errno to any non-zero
> value if it so desires. (C99 section 7.5 #5.)
That's news to me.
> That means that raw calls to memcpy (and friends) cannot be generated anywhere
> where the compiler is unable to prove that the value of errno isn't used.
That's almost impossible.
> Extra code to store and restore errno must be emitted otherwise.
That is not possible.
Note that the compiler emits calls to memcpy for struct copies anyway,
so if there is a problem it is a long-standing one.
next prev parent reply other threads:[~2014-06-06 11:54 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-08 23:40 [Bug middle-end/56888] New: " xanclic at gmail dot com
2013-04-09 9:59 ` [Bug middle-end/56888] " mikpe at it dot uu.se
2013-04-09 10:01 ` jakub at gcc dot gnu.org
2013-04-09 10:01 ` rguenth at gcc dot gnu.org
2013-04-09 13:02 ` xanclic at gmail dot com
2013-04-09 13:17 ` rguenther at suse dot de
2013-04-09 13:20 ` xanclic at gmail dot com
2013-04-11 11:29 ` rguenth at gcc dot gnu.org
2013-06-23 0:01 ` jeff@deseret-tech.com
2013-07-17 7:52 ` paulo@matos-sorge.com
2013-07-17 17:10 ` brooks at gcc dot gnu.org
2013-07-17 17:28 ` xanclic at gmail dot com
2013-07-17 20:36 ` schwab@linux-m68k.org
2013-07-17 20:59 ` xanclic at gmail dot com
2013-07-17 22:31 ` schwab@linux-m68k.org
2013-07-18 0:26 ` xanclic at gmail dot com
2013-07-18 10:35 ` paulo@matos-sorge.com
2013-07-28 3:30 ` bugdal at aerifal dot cx
2013-10-02 7:59 ` bernd.edlinger at hotmail dot de
2013-10-02 8:17 ` rguenth at gcc dot gnu.org
2013-10-02 8:49 ` bernd.edlinger at hotmail dot de
2013-10-02 8:59 ` rguenther at suse dot de
2014-02-17 3:48 ` janosch.rux at web dot de
2014-04-29 13:50 ` rguenth at gcc dot gnu.org
2014-04-29 13:57 ` rguenth at gcc dot gnu.org
2014-04-29 14:47 ` bugdal at aerifal dot cx
2014-05-06 10:51 ` rguenth at gcc dot gnu.org
2014-05-06 10:52 ` rguenth at gcc dot gnu.org
2014-06-06 10:40 ` terra at gnome dot org
2014-06-06 11:54 ` rguenther at suse dot de [this message]
2014-11-03 7:09 ` fd935653 at opayq dot com
2020-08-16 22:51 ` pinskia at gcc dot gnu.org
2022-06-03 6:55 ` pinskia at gcc dot gnu.org
2022-10-26 17:06 ` pinskia at gcc dot gnu.org
2023-12-18 20:59 ` terra at gnome dot org
2023-12-18 21:32 ` david at westcontrol dot com
2023-12-19 2:07 ` terra at gnome dot org
2023-12-19 8:03 ` rguenth at gcc dot gnu.org
2023-12-19 8:06 ` rguenth at gcc dot gnu.org
2023-12-19 8:28 ` david at westcontrol dot com
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