Function _mm_alignr_epi8

pub unsafe fn _mm_alignr_epi8(
    a: __m128i,
    b: __m128i,
    const IMM8: i32,
) -> __m128i

Available on (x86 or x86-64) and target feature ssse3 and x86 only.

Concatenate 16-byte blocks in a and b into a 32-byte temporary result, shift the result right by n bytes, and returns the low 16 bytes.

Intel’s documentation