[Bug tree-optimization/107342] Optimization opportunity where integer '/' corresponds to '>>'

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107342

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Aldy Hernandez <aldyh@gcc.gnu.org>:

https://gcc.gnu.org/g:679be32e66428f0ba81d1c1b55f7bd47f01cb295

commit r13-3688-g679be32e66428f0ba81d1c1b55f7bd47f01cb295
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Fri Nov 4 10:20:46 2022 +0100

    Set nonzero bits for multiplication and divisions by a power of 2.

    We're missing a lot of TLC in keeping track of nonzero bits across
    range-ops.  It isn't an oversight, but just limited amount of hours to
    implement stuff.

    This patch keeps better track of the nonzero mask (really
    maybe_nonzero bits as discussed) across multiplication and division
    when the RHS is a power of 2.

    It fixes PR107342 and also touches on PR55157.  In the latter, the
    nonzero mask is being set quite late (CCP2) but could be set by evrp
    time if we enhanced range-ops.  I have added tests from both PRs.

    Tested

            PR tree-optimization/107342

    gcc/ChangeLog:

            * range-op.cc (operator_mult::fold_range): New.
            (operator_div::fold_range): New.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/vrp122.c: New test.
            * gcc.dg/tree-ssa/vrp123.c: New test.