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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/105216] [12 regression] 8% regression for
 m-queens compared to gcc11 O2
Date: Mon, 11 Apr 2022 08:38:47 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105216

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #2)
> I suppose it's good again with -fno-tree-vectorize?  With vectorization
> enabled we tame down PRE to avoid creating loop carried dependences the
> vectorizer cannot handle.  For the "important" opportunities we try to
> recover after vectorization with predictive commoning.
>=20
> Hmm, confirmed with -fno-tree-vectorize even.
>=20
> Possibly caused by r12-7389-ge25dce50133405

Nope, reverting that doesn't fix it.

Note it seems the GCC 11 branch head also regressed compared to
r11-8866-g056e324ce46a79 but not as much as trunk.  Note I can reproduce
~2% regression from that 11 branch rev on the branch and ~4% towards trunk
so it's also a bit noisy.=