This part is definitely wrong: > I may compile a C code to Bitcode and have LLVM generate a running binary for x86 CPUs in the end. If I save the Bitcode, howe

This part is definitely wrong: > I may compile a C code to Bitcode and have LLVM generate a running binary for x86 CPUs in the end. If I save the Bitcode, however, I can later on tell LLVM to also create a running binary for an ARM CPU from that Bitcode, without having to compile anything and without access to the original C code. And the generated ARM code will be as good as if I had compiled to ARM from the very start. There is some other stuff in the answer that is interesting (eg. that Apple apparently never actually used Bitcode for iOS, despite what they implied) My guess is that they planned to use Bitcode to do minor optimisations for new generations of their chips, but it turned out to not work in practice, and so they scrapped it.