#[target_feature]-annotated functions can be marked #[inline] and will only be inlined if
the target features match (as well as all of the other inlining heuristics). #[inline(always)]
will always inline regardless of matching target features, which can result in errors from LLVM.
However, it is desirable to be able to always annotate certain functions (e.g. SIMD intrinsics)
as #[inline(always)] but check the target features match in Rust to avoid the LLVM errors.