The Importance of Performance Profiles in C++

Whether we can eliminate undefined behavior without imposing runtime or heads is indeed an open question. UB has been used in the optimization pipelines, so there's very often not one place you can see that if it did reference a point that we can stop that by looking there and only there. If this is engineering, not math, we'd have the answer. We know that. I think I've never seen a piece of code that couldn't be improved. But it is very hard to take a whole system and fix it at once. It involves quite a few people that works on compilers. And they have constraints. That's where the difficulty is.