I actually reached for these (_mm*_cmpeq_epi8_mask), this morning in my (Rust) code only to find that they are still `unstable` only and therefore unavailable to me, along with so many other SIMD things in Rust.

Portable SIMD aside (which is sitting forever unstable & unavailable), the actual intrinsics I feel should not be. Quite frustrating, and along with missing allocator_api (still!) makes me feel sometimes like 'reverting' back to C++.

https://doc.rust-lang.org/stable/core/arch/x86_64/fn._mm256_...