Frank Neuhaus wrote: > On Fri, Jun 26, 2009 at 8:36 PM, Andrew Haley<aph@xxxxxxxxxx> wrote: > >> If gcc inlines Image::resize, it knows that pixels does not escape, and whatever >> is in pixels cannot have any effect elsewhere. >> >> To learn more, compile with -fdump-tree-all and look at x.cc.*t.optimized. >> You may find it interesting. > > Hm ok that indeed looks interesting. However as i see it it only shows > me the way the optimizer laid things out, not the reason for why it is > this way, right? > > I still don't precisely understand the reason for this behavior. Well, I did tell you. :-) No, that's not it. gcc doesn't look inside resize() when it's compiling main(). So, it doesn't know what resize() does. > Also what would happen if resize was called somewhere else in a > complex function that can't be inlined for some reason? Then even > inlining wouldn't help right? Would -O3 always do the trick or are > there cases where I still need to be afraid that this happens? I have no idea what you might be afraid of. But the more the compiler inlines, the more it can do, because the more it can see. Andrew.
