Another option, that I'm curious what people might think of, that
might alleviate some performance woes of multiple calls to much
simpler MMX instruction wrappers:

A runtime code generator, that's typed by ocaml. Basically, create a
code block from multiple instructions, which is turned into machine
code, then executed through a C function.

You'd still get type safety, but performance should hopefully be a bit
better. The idea is that you commonly execute a set of MMX
instructions at a time, rather than single instructions.

Ideas on whether this is a good design, and what would probably be the
best way to do this are welcome =)

Jonathan