3173a4fc3a
-Use MCRegister::id() for BitVector index. -Replace std::unordered_set<unsigned> with std::set<MCRegister. There are other std::sets for Register. None for MCRegister before this. I'm assuming we can have operator<(MCRegister, MCRegister). This avoids needing to add std::hash<MCRegister>. -Use MCRegister::isValid() to avoid comparing to 0.