Function _mm256_undefined_ph 

pub fn _mm256_undefined_ph() -> __m256h

Available on x86 and target feature avx512fp16 and target feature avx512vl only.

Return vector of type __m256h with indetermination elements. Despite using the word “undefined” (following Intel’s naming scheme), this non-deterministically picks some valid value and is not equivalent to mem::MaybeUninit. In practice, this is typically equivalent to mem::zeroed.

Intel’s documentation