pub unsafe fn _mm256_shrdi_epi64(
    a: __m256i,
    b: __m256i,
    const IMM8: i32
) -> __m256i
🔬 This is a nightly-only experimental API. (stdsimd #48556)
Available on x86 and target feature avx512vbmi2,avx512vl only.
Expand description

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.

Intel’s documentation