[MLton] MLton HOL

[Matthew Fluet]

> > I gave commonArg a quick look.  The analysis itself is very much like the
> > contification analysis -- create a graph and compute its dominators.
> > There might be an issue with Node.hasEdge, which is linear, since I avoid
> > adding redundant edges to the graph.
>
> That was definitely the problem.  I fixed it by removing the calls to
> Node.hasEdge and adding a call to Graph.removeDuplicateEdges, which
> runs in time proportional to the size of the graph.  After the fix,
> commonArg now runs in 2.5s instead of 348s.
>
> I see that contify.fun and multi.fun also make calls to Node.hasEdge.
> It would be worth seeing if the same fix would work for them, even
> though we haven't yet seen any performance problem there.

I'm almost certain that contify.fun could use the same fix.  I don't
remember about multi.fun, but I'll look into them.