Function _mm512_mask_compressstoreu_pd 

pub unsafe fn _mm512_mask_compressstoreu_pd(
    base_addr: *mut f64,
    k: __mmask8,
    a: __m512d,
)

Available on x86-64 and target feature avx512f only.

Contiguously store the active double-precision (64-bit) floating-point elements in a (those with their respective bit set in writemask k) to unaligned memory at base_addr.

Intel’s documentation