Re: Q: access to subprogram

[jsa@organon.com (Jon S Anthony)]

In article <dewar.836962533@schonberg> dewar@cs.nyu.edu (Robert Dewar) writes:

> Jon Anthony says
> 
> "I don't see how, as most programs will not have _any_ nesting.
> Period.  So displays or static links are irrelevant for nearly all
> cases.  So, the issue is irrelevant to [probably not even hyperbole
> here] 99+% of subprogram calls.  Which means that there really is no
> distributed overhead (at least not as I understand the term)."
> 
> This is wildly overstated. I would say that any large program that has
> no nested procedures at all is poorly written, and I have seen very
> few large program (actually none in Ada) that had no nesting at all.

I can agree with this (even the "wildly" bit :-))

> On the other hand, I have *quite* often seen programs using nesting
> *very* extensively, where the program was divided into large procedures,
> containing many nested procedures, where the majority of calls are to
> procedures contained within other procedures.

And I would say that these are examples where "poorly written" would
equally apply.


> I don't believe Jon's figure of 99+% of subprogram calls being to library
> level subprograms is anywhere near right, and I would guess it is just
> a rhetorical guess rather than any kind of measurement. Across an

Yes, no real data - only anecdotal evidence. Hence the "hyperbole
caveat".

> admitedly small sample of large programs that I was involved in measuring,
> we saw over 80% of the calls being to procedures that were nested inside
> other procedures.

I find that a little surprising, but facts is facts.  I would also say
that this is very likely an indication that something has gone wrong.
Not in the measurement, but in the programs.


> In any case, I agree it is probably not a critical point. gcc uses static

Check!


/Jon
-- 
Jon Anthony
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