May 29, 2025

ARM Neon is the common intrinsics library (there's a newer one but not widely deployed). This usually includes SHA intrinsics, but is limited to 128 bit vectorization. On Intel we get 128, 256, and 512 with newer machines, as well as SHA (which often is not present). The 128 bit vectorization helps when SHA is not present, but it's usually present with Neon. And native SHA is much faster, so more important to get that incorporated. That's a similar process, though the semantics of the intrinsics differ between ARM and Intel, so it's not quite as straightforward to get a clean common implementation.