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From: "wilco at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/108659] Suboptimal 128 bit atomics codegen on AArch64 and x64
Date: Fri, 03 Feb 2023 22:45:33 +0000 [thread overview]
Message-ID: <bug-108659-4-TUKq9sXg4G@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-108659-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108659
--- Comment #11 from Wilco <wilco at gcc dot gnu.org> ---
(In reply to Niall Douglas from comment #10)
> (In reply to Jakub Jelinek from comment #9)
> > (In reply to Wilco from comment #8)
> > > Yes that sounds like a reasonable approach.
> >
> > I don't think so. Not all variables on which __atomic_* intrinsics are used
> > are actually _Atomic, the vars can be embedded in const aggregates etc.
>
> I'd have the attribute propagate to enclosing types, like over-alignment.
Yes, a structure with a 128-bit Atomic type in a subfield/union would be forced
to rwdata.
And arbitrary casts (eg. from char* to an atomic type) wouldn't work due to
Atomics requiring strict alignment. A 128-bit atomic type might have a higher
alignment than a 128-bit integer so even casting that seems questionable.
next prev parent reply other threads:[~2023-02-03 22:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-03 15:42 [Bug c++/108659] New: " s_gccbugzilla at nedprod dot com
2023-02-03 16:02 ` [Bug target/108659] " jakub at gcc dot gnu.org
2023-02-03 16:14 ` ktkachov at gcc dot gnu.org
2023-02-03 17:14 ` s_gccbugzilla at nedprod dot com
2023-02-03 17:20 ` pinskia at gcc dot gnu.org
2023-02-03 21:04 ` wilco at gcc dot gnu.org
2023-02-03 21:08 ` pinskia at gcc dot gnu.org
2023-02-03 21:22 ` s_gccbugzilla at nedprod dot com
2023-02-03 21:51 ` wilco at gcc dot gnu.org
2023-02-03 21:58 ` jakub at gcc dot gnu.org
2023-02-03 22:34 ` s_gccbugzilla at nedprod dot com
2023-02-03 22:45 ` wilco at gcc dot gnu.org [this message]
2023-05-31 13:25 ` [Bug target/108659] Suboptimal 128 bit atomics codegen x64 pinskia at gcc dot gnu.org
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