[Bug tree-optimization/94921] Failure to optimize nots with sub into single add

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94921

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

https://gcc.gnu.org/g:a7b76d574b19190da190a60c065f347f40bab59e

commit r11-132-ga7b76d574b19190da190a60c065f347f40bab59e
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed May 6 11:20:20 2020 +0200

    match.pd: Optimize ~(~X +- Y) into (X -+ Y) [PR94921]

    According to my verification proglet, this transformation for signed types
    with undefined overflow doesn't introduce nor remove any UB cases, so
should
    be valid even for signed integral types.
    Not using a for because of the :c on plus which can't be there on minus.

    2020-05-06  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/94921
            * match.pd (~(~X - Y) -> X + Y, ~(~X + Y) -> X - Y): New
            simplifications.

            * gcc.dg/tree-ssa/pr94921.c: New test.