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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/80878] -mcx16 (enable 128 bit CAS) on x86_64 seems not to work on 7.1.0
Date: Thu, 03 Nov 2022 10:04:10 +0000 [thread overview]
Message-ID: <bug-80878-4-DJKbOwD32x@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-80878-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80878
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #38 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Please see PR104688 . We got a response from Intel, where they guaranteed
atomicity of certain 16-byte load instructions for Intel CPUs with AVX support.
AFAIK we didn't get similar guarantee from AMD.
The current state is that on the libatomic side when ifuncs are possible we use
those atomic loads etc. on Intel with AVX, and do what we used to do before for
other CPUs.
We haven't changed what the compiler emits, I think we'd need to introduce some
new option for it (guarantee code will run only on Intel CPUs) and imply that
from -march= listing Intel CPUs (with AVX). If AMD would give a similar
guarantee, it would be much easier, we could just emit that whenever -mavx.
next prev parent reply other threads:[~2022-11-03 10:04 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-80878-4@http.gcc.gnu.org/bugzilla/>
2020-04-18 17:14 ` avi@cloudius-systems.com
2020-04-18 17:23 ` fw at gcc dot gnu.org
2020-04-18 17:31 ` avi@cloudius-systems.com
2020-04-18 17:40 ` fw at gcc dot gnu.org
2020-04-18 18:13 ` avi@cloudius-systems.com
2020-04-18 18:18 ` avi@cloudius-systems.com
2020-04-18 18:41 ` fw at gcc dot gnu.org
2021-03-14 3:21 ` wuyongwei at gmail dot com
2021-03-14 3:46 ` wuyongwei at gmail dot com
2021-03-16 16:02 ` wuyongwei at gmail dot com
2021-05-06 17:50 ` s_gccbugzilla at nedprod dot com
2021-05-06 19:32 ` pinskia at gcc dot gnu.org
2021-05-06 20:53 ` liblfds_gccbz at winterflaw dot net
2021-05-07 12:27 ` s_gccbugzilla at nedprod dot com
2021-05-07 14:07 ` redi at gcc dot gnu.org
2021-05-07 14:44 ` s_gccbugzilla at nedprod dot com
2022-11-03 9:55 ` lh_mouse at 126 dot com
2022-11-03 10:04 ` jakub at gcc dot gnu.org [this message]
2022-11-03 10:32 ` fw at gcc dot gnu.org
2022-11-03 11:16 ` admin_public at liblfds dot org
2023-11-16 1:33 ` lh_mouse at 126 dot com
2023-12-10 9:54 ` lh_mouse at 126 dot com
2023-12-10 10:32 ` admin_public at liblfds dot org
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