[Bug tree-optimization/94802] Failure to recognize identities with __builtin_clz

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94802

--- Comment #3 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:d2eb616a0f7bea78164912aa438c29fe1ef5774a

commit r11-6378-gd2eb616a0f7bea78164912aa438c29fe1ef5774a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Dec 31 11:09:26 2020 +0100

    match.pd: Add clz(X) == 0 -> (int)X < 0 etc. simpifications [PR94802]

    The following patch adds some clz simplifications.  If
    clz is 0, then the MSB of the argument is set, and if clz is prec-1, then
    the argument is 1.

    2020-12-31  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/94802
            * match.pd (clz(X) == 0 -> (int)X < 0): New simplification.
            (clz(X) == (prec-1) -> X == 1): Likewise.

            * gcc.dg/tree-ssa/pr94802-1.c: New test.