Function _mm256_shrdi_epi64 

pub fn _mm256_shrdi_epi64(a: __m256i, b: __m256i, const IMM8: i32) -> __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 imm8 bits, and store the lower 64-bits in dst.

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