Is there an option in the Eclipse PDT to display each call to the selected function. Now, if you select some function and press the F3 key, you will see the definition of the selected function.
Open the search menu, select "Search ..." and go to the PHP tab, then
Find Usage Methods http://img217.imageshack.us/img217/83/eclipsepdtfindmethodusa.png
We have a plugin for this ... nWire for PHP . This is a comprehensive PHP code analyzer that presents all your code associations, calls included in one quick and easy to use view. It can also represent associations associatively.