[Bug tree-optimization/110949] ((cast)cmp) - 1 should be tranformed into -(cast)cmp` where cmp` is the inverse of cmp

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110949

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Andrew Pinski <pins...@gcc.gnu.org>:

https://gcc.gnu.org/g:fa099f248e2462ecd5ab8b0cadd348aaf11bb093

commit r16-2392-gfa099f248e2462ecd5ab8b0cadd348aaf11bb093
Author: Andrew Pinski <quic_apin...@quicinc.com>
Date:   Sun Jul 20 11:21:08 2025 -0700

    match: Add `cmp - 1` simplification to `-icmp` [PR110949]

    I have seen this a few places though the testcase from PR 95906
    is an obvious place where this shows up for sure.
    This convert `cmp - 1` into `-icmp` as that form is more useful
    in many cases.

    Changes since v1:
    * v2: Add check for outer type's precision being greater than 1.

    Bootstrapped and tested on x86_64-linux-gnu.

            PR tree-optimization/110949
            PR tree-optimization/95906

    gcc/ChangeLog:

            * match.pd (cmp - 1): New pattern.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/cmp-2.c: New test.
            * gcc.dg/tree-ssa/max-bitcmp-1.c: New test.

    Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>