Re: PR64454: (x % y) % y

[Andrew Pinski <pinskia@gmail.com>]

On Thu, May 14, 2015 at 9:33 AM Marc Glisse <marc.glisse@inria.fr> wrote:
>
> Hello,
>
> after this patch I think I'll close the PR. This was regtested on
> ppc64le-redhat-linux.
>
> Apparently I wrote this patch in a file that already had a trivial hunk:
> -1-A -> ~A is rejected for complex while -A-1 isn't, there is no reason
> for this difference (maybe there was before integer_all_onesp /
> integer_minus_onep was introduced), I hope you don't mind.


So this hunk actually was wrong in the end. PR 104675 is opened for
the reason why it was wrong.
-A-1 should also be rejected for complex types too.

I will also notice the gimple verifiers should be catching BIT_* on
the complex types as they don't make sense really but currently is
not. Though that would be something for GCC 13.

Thanks,
Andrew Pinski

>
> I am wondering if we want some helper (like :c for commutative operations)
> to avoid duplicating patterns for x<y and y>x. We could also, when a
> comparison x<=y doesn't simplify, see if !!(x<=y) simplifies better, but
> that's becoming a bit complicated.
>
> 2015-05-15  Marc Glisse  <marc.glisse@inria.fr>
>
>         PR tree-optimization/64454
> gcc/
>         * match.pd ((X % Y) % Y, (X % Y) < Y): New patterns.
>         (-1 - A -> ~A): Remove unnecessary condition.
> gcc/testsuite/
>         * gcc.dg/modmod.c: New testcase.
>
> --
> Marc Glisse