https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90693
--- Comment #13 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #12)
> (In reply to Piotr Siupa from comment #11)
> > However, I've noticed that:
> > bool foo(unsigned x)
> > {
> > if (x == 0)
> > return true;
> > else
> > return std::has_single_bit(x);
> > }
>
>
> Oh that is because expand does not use flow sensitive ranges/non-zero bits
> there. There is talk about adding the ability for that but nothing has been
> done yet.
Well that also should be transformed into `__builtin_popcount(a) <= 1` which
then gets expanded into `(v & (v - 1)) == 0`. I will be handling both of those
via PR 94787 .
