[Bug tree-optimization/120231] GCC fails to notice that (double)u64 is non-negative

[acoplan at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120231

--- Comment #6 from Alex Coplan <acoplan at gcc dot gnu.org> ---
I suppose that example boils down to whether code like:

_Bool f(_Float16 a) {
    return a * a >= 0;
}
_Bool g(float a) {
    return a * a >= 0;
}

can be optimised to return true.  We currently do it with -ffast-math but not
without.