From: Torvald Riegel <triegel@redhat.com>
To: Alexander Monakov <amonakov@ispras.ru>
Cc: Ruslan Nikolaev <nruslan_devel@yahoo.com>, gcc@gcc.gnu.org
Subject: Re: GCC interpretation of C11 atomics (DR 459)
Date: Mon, 26 Feb 2018 18:56:00 -0000 [thread overview]
Message-ID: <1519671348.15077.665.camel@redhat.com> (raw)
In-Reply-To: <alpine.LNX.2.20.13.1802260817550.8765@monopod.intra.ispras.ru>
On Mon, 2018-02-26 at 08:50 +0300, Alexander Monakov wrote:
> > For these reasons, it may be a good idea if GCC folks reconsider past
> > decision. And just to clarify: if mcx16 (x86-64) is not specified during
> > compilation, it is totally OK to redirect to libatomic, and there make the
> > final decision if target CPU supports a given instruction or not. But if it is
> > specified, it makes sense for performance reasons and lock-freedom guarantees
> > to always generate it directly.
>
> You don't mention it directly, so just to make it clear for readers: on systems
> where GNU IFUNC extension is available (i.e. on Glibc), libatomic tries to do
> exactly that: test for cmpxchg16b availability and redirect 128-bit atomics to
> lock-free RMW implementations if so. (I don't like this solution)
I thought we had fixed that to not use the wide CAS?
next prev parent reply other threads:[~2018-02-26 18:56 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1615980330.4453149.1519617655582.ref@mail.yahoo.com>
2018-02-26 4:01 ` Ruslan Nikolaev via gcc
2018-02-26 5:50 ` Alexander Monakov
2018-02-26 7:24 ` Fw: " Ruslan Nikolaev via gcc
2018-02-26 8:20 ` Alexander Monakov
2018-02-26 8:43 ` Ruslan Nikolaev via gcc
2018-02-26 19:07 ` Torvald Riegel
2018-02-26 19:43 ` Ruslan Nikolaev via gcc
2018-02-26 22:49 ` Ruslan Nikolaev via gcc
2018-02-27 3:33 ` Ruslan Nikolaev via gcc
2018-02-27 10:34 ` Ramana Radhakrishnan
2018-02-27 11:14 ` Torvald Riegel
2018-02-27 12:39 ` Torvald Riegel
2018-02-27 13:04 ` Ruslan Nikolaev via gcc
2018-02-27 13:08 ` Szabolcs Nagy
2018-02-27 13:17 ` Ruslan Nikolaev via gcc
2018-02-27 16:40 ` Torvald Riegel
2018-02-27 17:07 ` Ruslan Nikolaev via gcc
2018-02-27 16:21 ` Torvald Riegel
2018-02-27 16:16 ` Torvald Riegel
2018-02-27 16:46 ` Simon Wright
2018-02-27 16:52 ` Florian Weimer
2018-02-27 17:30 ` Torvald Riegel
2018-02-27 17:33 ` Ruslan Nikolaev via gcc
2018-02-27 19:32 ` Torvald Riegel
2018-02-27 17:59 ` Simon Wright
2018-02-27 10:40 ` Fw: " Torvald Riegel
2018-02-26 18:56 ` Torvald Riegel [this message]
2018-02-26 12:30 ` Szabolcs Nagy
2018-02-26 13:57 ` Alexander Monakov
2018-02-26 14:51 ` Szabolcs Nagy
2018-02-26 14:53 ` Ruslan Nikolaev via gcc
2018-02-26 18:35 ` Torvald Riegel
2018-02-26 18:59 ` Ruslan Nikolaev via gcc
2018-02-26 19:20 ` Torvald Riegel
2018-02-26 18:16 ` Florian Weimer
2018-02-26 18:34 ` Ruslan Nikolaev via gcc
2018-02-26 18:36 ` Janne Blomqvist
2018-02-27 10:22 ` Florian Weimer
[not found] <886227277.5611063.1519759959364.ref@mail.yahoo.com>
2018-02-27 20:20 ` Ruslan Nikolaev via gcc
2018-02-27 22:19 ` Torvald Riegel
2018-02-28 1:46 ` Ruslan Nikolaev via gcc
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