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From: "rguenth 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 since r12-4526-gd8edfadfc7a9795b
Date: Mon, 09 Jan 2023 12:48:07 +0000
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X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 12.2.0
X-Bugzilla-Keywords: needs-bisection, wrong-code
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108008

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
                 CC|                            |rguenth at gcc dot gnu.org
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=3D107323
      Known to work|                            |13.0
           Keywords|                            |needs-bisection

--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Alexander Monakov from comment #9)
> I think this is tree-ldist placing memset(sameZ, 0, zPlaneCount) after the
> loop, overwriting conditional 'sameZ[i] =3D true' assignments that happen=
 in
> the loop.
>=20
> For the smaller testcase from comment #6, -O2 -ftree-loop-distribution is
> enough, namely:
>=20
> works:
>=20
> gcc-12 -O2 -ftree-loop-distribution -fno-tree-vectorize
> -fno-tree-loop-distribute-patterns
>=20
> breaks:
>=20
> gcc-12 -O2 -ftree-loop-distribution -fno-tree-vectorize

Note I can not reproduce on the branch after r12-8855-g19a9b5e587e87f52,
so maybe that's truly the duplicate.

Bisecting on the branch might reveal that.=