If your language has pointers or aliases, precise call graphs are exceedingly expensive (for large programs), because you need a precise pointer or alias analysis. Do you have a link to a publication about the technique you describe?
There are meatier technical presentations around about the formal bounds, but I always recommend Manuel Serrano's early work, which is much more accessible than more modern presentations (my own included):
A good survey of many of the tricks used in practice (and the formal techniques, as well) is available in Jan Midtgaard's tome, which was finally published in the last year or so:
