In the film The Dark Knight Rises, Bane wears a mask that covers the bottom half of his face. This obscures his mouth and jaw such that it's pretty hard to tell when the actor is actually speaking. The clarity and audio quality of his speech seemed a little off. During the filming, was he speaking the recorded dialogue, or did they have the actor go back later and rerecord the dialogue which was then added in post-production?
It was added in post. It is well documented that many audience members found his speech inaudible during the opening scene which was shown with M:I 4 - so Nolan went back in and reconfigured the audio. See The Hollywood Reporter article (one of many)
Naturally Hardy would have said his lines during filming so that everyone else could react to them, but it would have always been the intention to dub them afterwards as it is very hard to mic someone wearing a mask of that type.