It's impressive that clang generates the same assembly for both versions: https://godbolt.org/g/yLh1EF https://godbolt.org/g/yLh1EF Note that the assembly for

It's impressive that clang generates the same assembly for both versions: https://godbolt.org/g/yLh1EF https://godbolt.org/g/yLh1EF Note that the assembly for process_message2 calls each function only once even though some appear twice in the body.