Function _mm_cmp_sd 

pub fn _mm_cmp_sd(a: __m128d, b: __m128d, const IMM5: i32) -> __m128d

Available on x86 and target feature avx only.

Compares the lower double-precision (64-bit) floating-point element in a and b based on the comparison operand specified by IMM5, store the result in the lower element of returned vector, and copies the upper element from a to the upper element of returned vector.

Intel’s documentation