我的网站使用什么php模块？

I have to move fairly complex PHP website (which was not developed by me) to another server, but I'm quite sure it uses some non-default PHP modules. Is it possible to find out what those modules are without drilling through thousands of lines of code? I can get the whole list of PHP modules on current server ("php -m"), but I only need those used by my website.I have to move fairly complex PHP website (whic