Frank Neuhaus <dtag00@xxxxxxxxx> writes: > I would just like to know how the behavior prevents those 'bad' things > from happening i.e.: > How does not caching the pixels pointer in a local variable in front > of the loop prevent pixels from "escaping"? (What does that mean by > the way if a pixel "escapes"?) > How does not caching the pixels pointer, prevent pixels to have > "effects elsewhere"? Or vice versa: How does caching the pixels > pointer cause "effects elsewhere"? (Again: What are those "effects" > that could be caused?) I think you are asking the question the wrong way around. After inlining, gcc compiles a single function at a time (with some exceptions I won't discuss here). If gcc sees every use of the pixels pointer, then it knows that it can cache it locally. If gcc does not see every use--e.g., because it is passed to another function or stored in a global variable--then gcc does not know how it may be changed by code it can not see, and therefore can not cache it locally. Ian
