Function safe_arch::copy_replace_low_f64_m128d

#[must_use]pub fn copy_replace_low_f64_m128d(a: m128d, b: m128d) -> m128d

This is supported with target feature sse2 only.

Copies the a value and replaces the low lane with the low b value.

let a = m128d::from([1.0, 2.0]);
let b = m128d::from([3.0, 4.0]);
let c = copy_replace_low_f64_m128d(a, b);
assert_eq!(c.to_array(), [3.0, 2.0]);