https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110932
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> So the general rule is:
> (simplify
> (eq:c @0 (convert (cmp @1 @2)))
> (if (bitwise_equal_p (@0, @1))
> (with {
> bool zeroalwaystrue = ...
> bool zeroalwaysfalse = ...
> bool onealwaystrue = ...
> bool onealwaysfalse = ...
> }
> (switch
> (if (zeroalwaystrue && onealwaystrue)
> (le @0:unsigned { one(unsigned); } )) // @0 == 0 | @0 == 1
> (if (zeroalwaysfalse && onealwaysfalse )
> { false_bool; }) // false
> (if (zeroalwaystrue && onealwaysfalse)
> (eq @0 { zero(TREE_TYPE(@0)); })) // @0 == 0
> (if (onealwaystrue && onealwaysfalse)
> (eq @0 { one(TREE_TYPE(@0)); })) // @0 == 1
If we want to do this only in VRP, we could just use match to match the
sequence and then handle the comparison there ...
