pub unsafe fn _mm256_cmp_epu64_mask(
    a: __m256i,
    b: __m256i,
    const IMM3: _MM_CMPINT_ENUM
) -> __mmask8
🔬This is a nightly-only experimental API. (stdsimd #48556)
Available on (x86 or x86-64) and target feature avx512f,avx512vl only.
Expand description

Compare packed unsigned 64-bit integers in a and b based on the comparison operand specified by imm8, and store the results in mask vector k.

Intel’s documentation