I seem to recall that LCC was also used, at least on 10th Ed. Am I
imagining things, or was that real?
Some of the earliest work on lcc was done in 1127; Chris
Fraser worked for the Labs for some years, Dave Hanson
collaborated from his appointment at Princeton. I believe
there was a /usr/bin/lcc. Some programs used it, either
because they needed some part of the ISO syntax (pcc2 was
pre-ISO) or just because.
I don't think that version of lcc used Reiser's c2 optimizer;
it generated reasonably good code by itself, including
emitting auto-increment/decrement instructions. Later
versions of lcc (such as that I later adopted as cc in
my personal V10 world) couldn't do that any more, so I
had to keep c2, and in fact to modify it to turn
(or maybe it was addl2 $4,p, I forget)
But that's another story which I'll tell only if asked,
and nothing to do with the original question.