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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/110591] [i386] (Maybe) Missed optimisation: _cmpccxadd sets flags
Date: Mon, 10 Jul 2023 04:27:09 +0000 [thread overview]
Message-ID: <bug-110591-4-WVCW6N0BET@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-110591-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110591
--- Comment #2 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Hongtao.liu from comment #1)
> I guess we can add a peephole for this, middle-end optimizer doesn't know
> cmpccxadd set EFLAGS same as cmp.
We already have a peephole for cmpxchg, for cmpxchg it's only valid for
CCZmode, but for cmpccxadd, it should be ok for all CCmode since it sets EFLAGS
exactly the same as CMP. The _CMPCCX_Z in the intrinsic is used as condition of
updating memory.
next prev parent reply other threads:[~2023-07-10 4:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-07 17:13 [Bug target/110591] New: " thiago at kde dot org
2023-07-10 2:21 ` [Bug target/110591] " crazylht at gmail dot com
2023-07-10 4:27 ` crazylht at gmail dot com [this message]
2023-07-10 6:22 ` crazylht at gmail dot com
2023-07-18 3:31 ` cvs-commit at gcc dot gnu.org
2023-07-18 3:32 ` crazylht at gmail dot com
2023-11-30 10:53 ` liuhongt at gcc dot gnu.org
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