pub unsafe fn _mm512_mask_popcnt_epi64(
    src: __m512i,
    k: __mmask8,
    a: __m512i
) -> __m512i
🔬 This is a nightly-only experimental API. (stdsimd #48556)
Available on x86-64 and target feature avx512vpopcntdq only.
Expand description

For each packed 64-bit integer maps the value to the number of logical 1 bits.

Uses the writemask in k - elements are copied from src if the corresponding mask bit is not set. Otherwise the computation result is written into the result.

Intel’s documentation