Re: native targets
And both are designed with adding new CPUs in mind.
Yes. I have actually DONE it. xmega32e5 is one of them. The gnu tools people are really happy when you give them a quality set of patches for new CPUs. I haven't done LLVM yet but might need to some day, and the same for gcc, if I stay cutting edge with microcontrollers.
You know, it might be REALLY COOL if Micros~1 were to make their windows build tools compatible with either LLVM _or_ GCC (including MAKE FILES), or maybe BOTH, and then simply made headers and "binutils" tools and 'import' libs available, and THEN switch their build environments to use THEM instead. The LLVM and gcc compilers and binutils very well may have advanced better than Micros~1's compilers and tools, and could be more widely accepted given the additional CPU support.
They could also submit patches for 'ld' to do Micros~1 stuff, like debug info, resources, manifests, DLL support, whatever. "Developers Developers Developers Developers".