Canonicalizatoin of alloc's that only had dealloc's was already supported. This is why the comment here mentioned "no uses" - because the SimplifyDeadDealloc would get rid of all deallocs if those had been the only things besides alloc's, and then the alloc's would have zero uses and disappear. You can remove the SimplifyDeadDealloc pattern now?
I'm sorry this revision never showed up in my "Waiting for review" list for some reason. I did make multiple passes from time to time on my "waiting for my review", but didn't find this.