Selfie
An educational software system of a tiny self-compiling C compiler
... of compilers, libraries, operating systems, and even virtual machine monitors. The common theme is to identify and resolve self-reference in systems code which is seen as the key challenge when teaching systems engineering, hence the name. Selfie is implemented in a single (!) file and kept minimal for simplicity. There is also a simple in-memory linker, a RISC-U disassembler, a garbage collector, L1 instruction and data caches, a profiler, and a debugger with replay.