RETURN1
RETURN1(rp, 0); /* log(1) = +0 in all rounding modes */
RETURN1(rp, -1 / zero); /* log(+-0) = -Inf */
RETURN1(rp, (x - x) / zero);
RETURN1(rp, x + x); /* log(Inf or NaN) = Inf or qNaN */
RETURN1(rp, 0); /* log(1) = +0 in all rounding modes */
RETURN1(rp, -1 / zero); /* log(+-0) = -Inf */
RETURN1(rp, (x - x) / zero);
RETURN1(rp, x + x); /* log(Inf or NaN) = Inf or qNaN */