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Subject: [Bug tree-optimization/104992] [missed optimization] x / y * y == x
 not optimized to x % y == 0
Date: Mon, 01 Aug 2022 13:24:48 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104992

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Sam Feifer <sfeifer@gcc.gnu.org>:

https://gcc.gnu.org/g:388fbbd895e72669909173c3003ae65c6483a3c2

commit r13-1916-g388fbbd895e72669909173c3003ae65c6483a3c2
Author: Sam Feifer <sfeifer@redhat.com>
Date:   Fri Jul 29 09:44:48 2022 -0400

    match.pd: Add new division pattern [PR104992]

    This patch fixes a missed optimization in match.pd. It takes the patter=
n,
    x / y * y =3D=3D x, and optimizes it to x % y =3D=3D 0. This produces f=
ewer
    instructions. This simplification does not happen for complex types.

    This patch also adds tests for the optimization rule.

    Bootstrapped/regtested on x86_64-pc-linux-gnu.

            PR tree-optimization/104992

    gcc/ChangeLog:

            * match.pd (x / y * y =3D=3D x): New simplification.

    gcc/testsuite/ChangeLog:

            * g++.dg/pr104992-1.C: New test.
            * gcc.dg/pr104992.c: New test.=