Alternatives for representing a reverse postorder numbering

[Norman Ramsey]

 > Which I guess mostly depends on how much mileage we get out of the
 > numbering... I rarely have lost sleep over the overhead of looking
 > things up in IntMaps.

Thank you!!  I found your analysis very helpful.  I will stick with
the IntMaps until and unless things reach a stage where they look
really ugly.

 > There is no invariant that Cmm control flow is reducible. So we
 > can't always rely on this being the case.

Good to know.  I would still like to have a simple Haskell example
that generates an irreducible control-flow graph, but for now I can
just write them by hand using .cmm files.

BTW *every* control-flow graph has at least one reverse-postorder
numbering, whether it is reducible or not.


Norman