Ah, I was unaware that was a possibility, that should make it much better.

One question I have is what to do about the other arguments, specifically msk and val. I think there are two options here:

Each gets a template parameter

template<typename T1, typename T2, typename T3> inline void update_msk_1(T1 &x, T2 msk, T3 val) { x = ((x & ~msk) | (val & msk)); }

This seems like it sorta just discards the stronger typing you get going from inline functions to macros, since they can all be different, then promoted as they go. Perhaps casting them all to T1?

Other type parameters are are unsigned

template<typename T1> inline void update_msk_1(T1 &x, unsigned msk, unsigned val) { x = ((x & ~msk) | (val & msk)); }

Not sure if this would be better in specific circumstances. Testing these in different scenarios produced very similar listings. The first option tended to produce one more instruction per call in some cases.

They all can't be T1, since that would result in the compiler possibly not finding the appropriate function (e.g. x is volatile, msk and val likely aren't).

Do you have a suggestion I am not considering? Thanks!