A couple of years ago I wrote a little script to tell me what called what and so on. It grew and mutated and is a crufty mess (not good for code which is meant to help with making other code more maintainable!) but you might want to take a look. It's on my website. Patches welcome, especially any which make it play nicely with the guts of perltidy. I've spoken at some length with the author about using his code, but lack of tuits has meant I've done nothing about it.