old comment-functions.php

I am preparing to upgrade to 2.1.2 and as usual, bringing forward my edits to the new files before I do so.

I used to make a change to comment-functions.php so that if I switched comments off on a particular post, no text would appear at all. This file no longer exists (I think) in 2.1.2 and I was wondering if someone could tell me where the relevant code is now hidden, to save me trawling through every comments file.

Thanks for your help