Comment by SkiFire13

> I am curious: we have reference counting and we have Profile guided optimisation. > > Could "reference counting" be compiled into a debug/profiled build and then detect which regions of time we free things in before or after (there is a happens before relation with dropping out of scopes that reference counting needs to run) to detect where to insert frees?

Profile guided optimizations can only gather informations about what's most probable, but they can't give knowledge about things about what will surely happen. For freeing however you most often want that knowledge, because not freeing will result in a memory leak (and freeing too early will result in a use-aftee-free, which you definitely want to avoid so the analysis needs to be conservative!). In the end this can only be an _optimization_ (just like profile guided _optimization_s are just optimizations!) on top of a workflows that is ok with leaking everything.