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Subject: [Bug tree-optimization/100492] [10/11/12 Regression] wrong code at
 -O3 (generated code hangs)
Date: Mon, 10 May 2021 11:06:10 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100492

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:60af2db18013a0339302928ba98fee893ccc1957

commit r12-661-g60af2db18013a0339302928ba98fee893ccc1957
Author: Richard Biener <rguenther@suse.de>
Date:   Mon May 10 11:37:27 2021 +0200

    tree-optimization/100492 - avoid irreducible regions in loop distributi=
on

    When we distribute away a condition we rely on the ability to
    change it to either 1 !=3D 0 or 0 !=3D 0 depending on the direction
    of the exit branch in the respective loop.  But when the loop
    contains an irreducible sub-region then for the conditions inside
    this this fails and can lead to infinite loops being generated.

    Avoid distibuting loops with irreducible sub-regions.

    2021-05-10  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/100492
            * tree-loop-distribution.c (find_seed_stmts_for_distribution):
            Find nothing when the loop contains an irreducible region.

            * gcc.dg/torture/pr100492.c: New testcase.=