Is there unused code in GHC source?

Dear devs, I'm trying to dig into GHC code and one thing is wondering me. Does the source contain old fragments of code that are not used anymore? Well, for such a big project the answer will probably be 'yes', but I'm wondering what the scale of this might be. I thought that such leftovers could be a bit misleading and I want to know if I should stay alert :) Janek