explicit arrays and limit checks

[Stephen Weeks]

> Anyways, regressions passed fine with one outstanding but with
> mlton.word.sml -- I see you added Word32_{add,mul}Check which use the
> carry flag to signal overflow.  That's fine, but the peephole optimization
> that turns adds with an immediate of 1 into an inc instruction is not
> valid in this case, because the inc instruction does not set the CF flag;
> I just need to add enough checks to make sure subsequent instructions
> aren't checking the CF flag.

Yeah, that's why I put that test in there.  I meant to mention that
bug.

> Checked in.  I'll try to get to the peephole bug later tonight or
> tomorrow.

Cool.  Thanks a lot.  I'll merge into the main line soon.