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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108482] [13 Regression] ice in
 expand_LOOP_DIST_ALIAS with -O3 -ftrivial-auto-var-init=zero
Date: Sat, 21 Jan 2023 20:13:04 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: ice-on-valid-code, missed-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108482

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is just a latent bug exposed by Richi's copyprop improvement.


Folding statement: ivtmp_37 =3D ivtmp_38 - 1;
gimple_simplified to ivtmp_37 =3D 1;
Folded into: ivtmp_37 =3D 1;

Folding statement: if (ivtmp_37 !=3D 0)
Not folded

While trunk (GCC 13):
Folding statement: ivtmp_9 =3D ivtmp_39 - 1;
Queued stmt for removal.  Folds to: 1
Folding statement: if (ivtmp_9 !=3D 0)
gimple_simplified to if (1 !=3D 0)
Folded into: if (1 !=3D 0)

Which is the correct thing to do and removes an branch earlier.
Which then removes a few extra loops.
Except now LOOP_DIST_ALIAS is not conditionalizing two loops any more.=