On Fri, Jun 16, 2023 at 4:14 PM Andrew Pinski <pins...@gmail.com> wrote:
>
> On Fri, Jun 16, 2023 at 4:46 AM Richard Biener via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > The following adds two patterns simplifying comparisons,
> > uns < (typeof uns)(uns != 0) is always false and x != (typeof x)(x == 0)
> > is always true.
>
> A few more that should be done (I will file a bug in a few minutes):
> `x == (typeof x)(x == 0)` is always false.
> `x == (typeof x)(x != 0)` is `(unsigned_type)x <= 1`
> `x != (typeof x)(x != 0)` is `(unsigned_type)x > 1`
> `uns <= (typeof uns)(uns != 0)` -> `uns <= 1`
> `uns > (typeof uns)(uns != 0)` is `uns > 1`
> `uns >= (typeof uns)(uns != 0)` is always true
>
> That should be all of them I think and I think I did it correctly.
Filed as PR 110293 .
Thanks,
Andrew
>
> >
> > Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
> >
> > PR tree-optimization/110278
> > * match.pd (uns < (typeof uns)(uns != 0) -> false): New.
> > (x != (typeof x)(x == 0) -> true): Likewise.
> > ---
> > gcc/match.pd | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index 264f9cb8a40..48b76e6a051 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -6410,6 +6410,17 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> > (if (cmp == GT_EXPR)
> > (lt (view_convert:st @0) { build_zero_cst (st); })))))))))))
> >
> > +/* unsigned < (typeof unsigned)(unsigned != 0) is always false. */
> > +(simplify
> > + (lt:c @0 (convert (ne @0 integer_zerop)))
> > + (if (TYPE_UNSIGNED (TREE_TYPE (@0)))
> > + { constant_boolean_node (false, type); }))
> > +
> > +/* x != (typeof x)(x == 0) is always true. */
> > +(simplify
> > + (ne:c @0 (convert (eq @0 integer_zerop)))
> > + { constant_boolean_node (true, type); })
> > +
> > (for cmp (unordered ordered unlt unle ungt unge uneq ltgt)
> > /* If the second operand is NaN, the result is constant. */
> > (simplify
> > --
> > 2.35.3
