From: Szabolcs Nagy <nsz@port70.net>
To: musl@lists.openwall.com
Subject: Re: atomic.h cleanup
Date: Fri, 15 Jan 2016 01:46:38 +0100 [thread overview]
Message-ID: <20160115004638.GI13558@port70.net> (raw)
In-Reply-To: <20160114233223.GA238@brightrain.aerifal.cx>
* Rich Felker <dalias@libc.org> [2016-01-14 18:32:24 -0500]:
> On Thu, Jan 14, 2016 at 11:37:48PM +0100, Jens Gustedt wrote:
> > Am Donnerstag, den 14.01.2016, 17:12 -0500 schrieb Rich Felker:
> > > There are already multiple reasons we don't use the compiler's
> > > atomics, either directly or indirectly via stdatomic.h. They're not
> > > supported in some old/alternative compilers, they generate highly
> > > suboptimal code even on modern compilers for some important archs
> > > (e.g. ARM),
> >
> > I have seen some pretty good assembler when using the
> > __atomic... builtins, so I can't completely follow, here.
>
> It generates "dmb sy" all over the place instead of "dmb ish".
> Synchronizing with external bus devices is NOT something you want to
> happen in thread synchronization primitives.
>
fixed in gcc-6 :)
https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=224317
(not backported to earlier branches though)
next prev parent reply other threads:[~2016-01-15 0:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-10 12:21 Markus Wichmann
2016-01-10 16:57 ` Rich Felker
2016-01-10 17:35 ` Markus Wichmann
2016-01-10 17:50 ` Alexander Monakov
2016-01-11 16:35 ` Markus Wichmann
2016-01-11 17:12 ` Jens Gustedt
2016-01-11 19:03 ` Szabolcs Nagy
2016-01-11 20:56 ` Jens Gustedt
2016-01-14 22:12 ` Rich Felker
2016-01-14 22:37 ` Jens Gustedt
2016-01-14 23:32 ` Rich Felker
2016-01-15 0:46 ` Szabolcs Nagy [this message]
2016-01-10 17:37 ` Markus Wichmann
2016-01-22 0:09 ` Rich Felker
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