🚀 go-pugleaf

I need a program (cross-referencer?) for Prolog programs that can answer
questions like:

- what predicates does predicate X call directly?
- what predicates can be reached from predicate X? (transitive closure)
- what predicates call predicate X directly?
- from what predicates can predicate X be called? (closure again)
- could predicate X eventually call itself? 

These questions translate into common graph algorithms, and I could use 
Quintus Prolog library to write my own corss-referencer. Before I do that,
is there any such program available, either in public domain or commercially?
A Motif interface would be especially nice.

Thanks for help!

-- Milan Richter