True, I think the builtins were necessary where the existing C operators don't map well to a specific SIMD feature (from what I've seen it's mostly "reduce" act

True, I think the builtins were necessary where the existing C operators don't map well to a specific SIMD feature (from what I've seen it's mostly "reduce" actions to reduce SIMD lanes into a single value). Still, a lot can be done without having to pepper the code with builtin functions, and the result is much more readable than purely intrinsic-based code. But a "new" language like Rust would have the freedom to add special language syntax and operators for such things instead of going the C++ way of "just add it to the stdlib" (which IMHO is almost always the wrong place... it should either go into a regular cargo dependency, or into the language itself).