Function _mm256_shrdv_epi64 

pub fn _mm256_shrdv_epi64(a: __m256i, b: __m256i, c: __m256i) -> __m256i

Available on x86-64 and target feature avx512vbmi2 and target feature avx512vl only.

Concatenate packed 64-bit integers in b and a producing an intermediate 128-bit result. Shift the result right by the amount specified in the corresponding element of c, and store the lower 64-bits in dst.

Intel’s documentation