Not sure what you're saying here. The ‘GC’ refers to garbage collector, not GCC. It is true that you can write a compiler frontend targeting a generic backend

Not sure what you're saying here. The ‘GC’ refers to garbage collector, not GCC. It is true that you can write a compiler frontend targeting a generic backend (like GCC), and take advantage of existing optimizations. Truffle's somewhat unique value prop is that you can write a basic interpreter (not compiler) and get performance approaching that of a top-end JIT.