me22 wrote: > 2009/6/26 Frank Neuhaus <dtag00@xxxxxxxxx>: >> Yes I agree that since resize is not inlined, the way pixels changes >> during the resize call is unknown to the optimizer operating on main. >> But _after_ this call to resize, all changes to pixels _have_ to be >> caused by main, and thus are known to the optimizer of the main >> function. That means it should be able to tell that pixels cannot >> possibly change after the execution of resize(*). And more >> specificially that it cannot possibly change during the execution of >> the loop. >> > > What if resize spawns a thread that wakes up periodically to change > the value? The compiler can't assume "well-behaved" functions. Yes, it can and it does. This would be undefined behaviour. Andrew.
