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From: "wwwhhhyyy333 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/107676] Nonsensical docs for -mrelax-cmpxchg-loop
Date: Tue, 15 Nov 2022 03:36:42 +0000 [thread overview]
Message-ID: <bug-107676-4-84SHcotfLC@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-107676-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107676
--- Comment #6 from Hongyu Wang <wwwhhhyyy333 at gmail dot com> ---
(In reply to Andrew Pinski from comment #5)
> (In reply to Jonathan Wakely from comment #4)
> > I don't think __atomic_compare_exchange emits such a loop. This is about
> > __atomic_fetch_xor and friends, which do emit cmpxchg loops. But there are
> > four such functions to name.
>
> Oh yes right.
> Then this:
> For compare and exchange loops that are emitted by some __atomic_* builtins
> (e.g. ....), emit an atomic load before the loop and if the value was not
> the expected value, emit a pause instruction. This might reduce execussive
> cache bouncing of the memory.
>
>
> I think that is better wording than it was before. I hope the person who
> added this option can take over this to get it closer to what it should be.
Thanks for all the suggestions, a patch has been posted at
https://gcc.gnu.org/pipermail/gcc-patches/2022-November/606212.html
next prev parent reply other threads:[~2022-11-15 3:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-14 13:32 [Bug target/107676] New: " redi at gcc dot gnu.org
2022-11-14 13:57 ` [Bug target/107676] " redi at gcc dot gnu.org
2022-11-14 14:04 ` redi at gcc dot gnu.org
2022-11-14 17:16 ` pinskia at gcc dot gnu.org
2022-11-14 17:21 ` redi at gcc dot gnu.org
2022-11-14 17:26 ` pinskia at gcc dot gnu.org
2022-11-15 3:36 ` wwwhhhyyy333 at gmail dot com [this message]
2022-11-16 13:42 ` cvs-commit at gcc dot gnu.org
2022-11-16 13:43 ` amonakov at gcc dot gnu.org
2022-11-28 22:23 ` pinskia at gcc dot gnu.org
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