How to tell which PHP files are actually used and which are not?
dependencies, php
Solution
Take a look at phpxref, It might do what you need.
Cross-references PHP classes, functions, variables, constants and require/include usage.
Problem
I got a large PHP website which I'm now about to take care of. It contains hundreds of separate PHP files, but I suspect only less than a half is really being used. Most of them probably can be deleted. But the last thing I really want to do is going through the code of each file and check whether its linked, included, required...etc. to others or whether it can be safely deleted. Do you know whether there's any tool which is capable of doing this?