>>682(679 here)
Not really. I've done some messing around as a hobbyist, but most of my recommendations are based around general systems development in C more so than anything which may apply to embedded development specifically.
Presumably, if your compilers don't support the architectures too well, you'll need to do more manual in-line optimizations. Perhaps there's an architecture somewhere badly-supported enough that it's best to just program it entirely in ASM. I mostly touch x86 and ARM systems, which have good optimizing C compilers.