nextafterl
extern long double nextafterl(long double x, long double y);
sum.hi = nextafterl(sum.hi, INFINITY * sum.lo);
return (nextafterl(z, 0));
return (nextafterl(z, -INFINITY));
return (nextafterl(z, INFINITY));
sum.hi = nextafterl(sum.hi, INFINITY * sum.lo);
return nextafterl(x, y);