SSA simplify passes

[Stephen Weeks]

> Not quite sure what you mean here -- rerun the whole set of simplifier
> passes?  Another option might be a fast set of passes that could be
> repeatedly applied according to some heuristics.  Mostly to take care of
> the "obvious cases" like the above -- if there are any really really small
> functions, run the inliner.

Sounds good.  With the exception of inlining, I think all of the
passes are guaranteed to not increase the size of the program.  Hence,
it might make sense to run to fixed-point with a more conservative
inliner.

> > constants.  Because of that, I don't think that's a good benchmark, so
> > I changed it so that the array is nonconstant.
> 
> Did you check in a change?  I haven't seen it.  But, I agree that that
> makes the benchmark more useful.

Sorry, I thought I did.  It's in now.