The LLVM backend that exports C is not very well supported. You'd be better off exporting directly to llvm bitcode and then running it under LLVM's JIT compiler or static compile to PPC/x86.
Keep in mind also that this is just an exercise in porting by software algorithm rather than by hand. As the LLVM optimizer codes get better, so will the output codes. Frodo emulates the C64 chipset itself.
