I have fond memories of implementing an optimizing compiler for the CS241 compiler course offered back then by Prof Michael Franz who was a student of Niklaus Wirth, probably the most exhilarating course during my time at UC Irvine. This was in 2009 so my memory is vague but I recall he provided a virtual machine for a simple architecture called DLX and the compiler was to generate byte code for it.

Google search points me to https://github.com/cesarghali/PL241-Compiler/blob/master/DLX... for a description of the architecture and possibly https://bernsteinbear.com/assets/img/linear-scan-ra-context-... for the register allocation algorithm