Function _mm_cmpunord_sd
#[target_feature(enable = "sse2")]
pub fn _mm_cmpunord_sd(a: __m128d, b: __m128d) -> __m128dReturns a new vector with the low element of a replaced by the result of
comparing both of the lower elements of a and b to NaN. If either is
equal to NaN then 0xFFFFFFFFFFFFFFFF is used and 0 otherwise.