I am just interested in a small maintainable C compiler which can easily be adopted to bootstrap a new platform or cpu (on FPGA). I consider such a tiny C compiler just a convenient assembler to implement basic things on new platforms.
I know GCC and Clang/LLVM but those tool chains are really big, and I guess it requires a lot of work to support a new platform and to polish all things so that everything works properly.
A portable tiny GCC/LLVM replacement for small embedded systems would be really nice. GCC and Clang are great for powerful systems but I consider them overkill for small systems.
It is a full-blown C compiler with enough extensions to compile the Linux kernel (and boot to it directly - look at the "tccboot" project). But it's also small enough and simple enough to retarget in a few days work (make that a few month if you want optimizations ... but you don't seem to).