[Bug target/70314] AVX512 not using kandw to combine comparison results

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70314

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Marc Glisse <glisse@gcc.gnu.org>:

https://gcc.gnu.org/g:229752afe3156a3990dacaedb94c76846cebf132

commit r11-2577-g229752afe3156a3990dacaedb94c76846cebf132
Author: Marc Glisse <marc.glisse@inria.fr>
Date:   Wed Aug 5 16:45:33 2020 +0200

    VEC_COND_EXPR optimizations

    When vector comparisons were forced to use vec_cond_expr, we lost a number
of optimizations (my fault for not adding enough testcases to
    prevent that). This patch tries to unwrap vec_cond_expr a bit so some
optimizations can still happen.

    I wasn't planning to add all those transformations together, but adding one
caused a regression, whose fix introduced a second regression,
    etc.

    Restricting to constant folding would not be sufficient, we also need at
least things like X|0 or X&X. The transformations are quite
    conservative with :s and folding only if everything simplifies, we may want
to relax this later. And of course we are going to miss things
    like a?b:c + a?c:b -> b+c.

    In terms of number of operations, some transformations turning 2
VEC_COND_EXPR into VEC_COND_EXPR + BIT_IOR_EXPR + BIT_NOT_EXPR might not look
    like a gain... I expect the bit_not disappears in most cases, and
VEC_COND_EXPR looks more costly than a simpler BIT_IOR_EXPR.

    2020-08-05  Marc Glisse  <marc.glisse@inria.fr>

            PR tree-optimization/95906
            PR target/70314
            * match.pd ((c ? a : b) op d, (c ? a : b) op (c ? d : e),
            (v ? w : 0) ? a : b, c1 ? c2 ? a : b : b): New transformations.
            (op (c ? a : b)): Update to match the new transformations.

            * gcc.dg/tree-ssa/andnot-2.c: New file.
            * gcc.dg/tree-ssa/pr95906.c: Likewise.
            * gcc.target/i386/pr70314.c: Likewise.