Sure I'm not saying profiling is perfect. I was just taking exception to the statement that profiling is nothing but a poor man's substitute for a cost model.

Sure I'm not saying profiling is perfect. I was just taking exception to the statement that profiling is nothing but a poor man's substitute for a cost model. Explicit annotations for hot/cold paths are useful, I agree. I would probably be more excited about them except last time I actually tried them with GCC, they slowed my code down (admittedly this was five years ago or so). But that's just an implementation problem, the concept is sound.