Rewrite main loop in cc1
Rewrite main loop in cc1

The original loop was a bit ugly because the three parts of
the for were totally unrelated, so it was an abuse of the for
loop, where it helps if the three parts are concerned about
some common thing.

8l/scc,k0gaMSX/scc,k0gaMSX/scc,k0gaMSX/scc,k0gaMSX/kcc,8l/scc,8l/scc,k0gaMSX/kcc