Manual SIMD intrinsics is getting there, not sure how far it has come by now: https://github.com/rust-lang/rust/pull/27169 I'm sure LLVM does a fair bit of vectorization under the hood too of course, but not sure whether better knowledge of aliasing lets it do more or whether less undefined behavior sloppyness in Rust lets it do less of it than for C++.

Branch hint intrinsic: an accepted RFC but not yet implemented https://github.com/rust-lang/rust/issues/26179

Prefetch intrinsic: Looks like a rejected rfc https://github.com/rust-lang/rfcs/pull/125

Inlining: As far as I understand the attributes are #[inline(always)] and #[inline(never)] respectively.