Function core::arch::x86::_mm256_alignr_epi8

pub unsafe fn _mm256_alignr_epi8(
    a: __m256i, 
    b: __m256i, 
    const IMM8: i32
) -> __m256i

This is supported on x86 and target feature avx2 only.

Concatenates pairs of 16-byte blocks in a and b into a 32-byte temporary result, shifts the result right by n bytes, and returns the low 16 bytes.

Intel’s documentation