To answer your initial question, no one (as far as I know) is already
working on this. If you get something working, we would certainly be
interested in seeing your code changes.
As other replies have said, there are several different approaches you
could take to doing this. If you want to avoid WHIRL changes, which
would simplify things, you could use builtins, or even try to pattern
match within CG (not ideal but could probably work for some cases).
Making the simd stuff visible at whirl level would be more work,
but would also enable more optimization. You should also think about
whether you want to have user-specified directives/attributes that would
tell where to use the simd stuff. That would require front-end changes,
but you could then avoid the need to determine when to use the simd code.
-- Mike Murphy
-- quote of the day:
-- "How can we remember our ignorance, which growth requires,
-- when we are using our knowledge all the time?" (Thoreau)