Function _mm256_mask_set1_epi8 

pub fn _mm256_mask_set1_epi8(src: __m256i, k: __mmask32, a: i8) -> __m256i

Available on x86 and target feature avx512bw and target feature avx512vl only.

Broadcast 8-bit integer a to all elements of dst using writemask k (elements are copied from src when the corresponding mask bit is not set).

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