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From: "amonakov at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108008] [12 Regression] wrong code with -O3 and posix_memalign
Date: Thu, 08 Dec 2022 08:44:48 +0000	[thread overview]
Message-ID: <bug-108008-4-kVmGNVfw2x@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-108008-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108008

--- Comment #9 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
I think this is tree-ldist placing memset(sameZ, 0, zPlaneCount) after the
loop, overwriting conditional 'sameZ[i] = true' assignments that happen in the
loop.

For the smaller testcase from comment #6, -O2 -ftree-loop-distribution is
enough, namely:

works:

gcc-12 -O2 -ftree-loop-distribution -fno-tree-vectorize
-fno-tree-loop-distribute-patterns

breaks:

gcc-12 -O2 -ftree-loop-distribution -fno-tree-vectorize

  parent reply	other threads:[~2022-12-08  8:44 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-07 14:06 [Bug c++/108008] New: Compiler mis-optimization with posix_memalign hahnjo at hahnjo dot de
2022-12-07 14:43 ` [Bug c++/108008] " amonakov at gcc dot gnu.org
2022-12-07 22:12 ` [Bug tree-optimization/108008] " dhsbz at chaw dot com
2022-12-07 22:24 ` pinskia at gcc dot gnu.org
2022-12-07 22:37 ` pinskia at gcc dot gnu.org
2022-12-07 22:48 ` pinskia at gcc dot gnu.org
2022-12-07 22:58 ` pinskia at gcc dot gnu.org
2022-12-07 23:05 ` [Bug tree-optimization/108008] [12 Regression] " pinskia at gcc dot gnu.org
2022-12-07 23:05 ` pinskia at gcc dot gnu.org
2022-12-08  8:44 ` amonakov at gcc dot gnu.org [this message]
2022-12-12  7:38 ` [Bug tree-optimization/108008] [12 Regression] wrong code with -O3 and posix_memalign amonakov at gcc dot gnu.org
2022-12-27 14:22 ` marxin at gcc dot gnu.org
2022-12-27 14:23 ` [Bug tree-optimization/108008] [12 Regression] wrong code with -O3 and posix_memalign since r12-4526-gd8edfadfc7a9795b marxin at gcc dot gnu.org
2023-01-09 12:48 ` rguenth at gcc dot gnu.org
2023-01-09 15:06 ` marxin at gcc dot gnu.org
2023-01-10  8:00 ` rguenth at gcc dot gnu.org

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