[Bug tree-optimization/122271] `(b ? nonnull : null) != null` should be converted to just `b`

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122271

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>Seems like something which phiopt could handle for f case at -O1.

Or phiprop.