New software for a 50 year old computer doesn't appear every day. A full B compiler should be too much to ask. But despite the minimal hardware, Robert Clausecker managed this feat, and as opposed to C, the simpler B suits the 8 very well.

Details are here (PDF) & here; a video presentation is here: (link).

It's a great introduction to the PDP-8 instruction set, and how to build a compiler for it.