On Monday 11 May 2009 17:53:59 Tim Soderstrom wrote: > On May 11, 2009, at 10:47 AM, Francesco Riosa wrote: > > On Monday 11 May 2009 16:53:23 Jay Pipes wrote: > >> Francesco Riosa wrote: > >>> gcc -c -Q -O3 --help=optimizers | grep funroll-loops > >>> -funroll-loops [disabled] > >>> > >>> -funroll-loops is the first branch in the root of evil, don't rely > >>> on it, > >>> even force -O3 isn't as good as it seem often. > >> > >> Hehe, yes, I'm aware of the dangers :) /me is not a Gentoo user ;) > > > > No comment, you little anti-gentoo fanboy :) > > Actually, what about -Os (without -funroll-loops)? -Os does more > optimizations than -O2 but fewer than -O3 in an effort to produce a > smaller foot-print. I have not done an extensive test, but did notice > that it made noticeably smaller binaries when I used it.
Actually it does some less: -falign-jumps -falign-labels -falign-loops -finline-functions -freorder-blocks -ftree-ch -ftree-pre -Os is -O2 minus code growing optimizations I did use -Os with mysql 5.1 happily and with a rather noticeable slimmer mysqld, expecially on 64 bit (yes I'm a bit richer too) > I agree, however, for things other than desktop applications that > don't do a lot of context-switching, -funroll-loops is terrible > because it makes the program size so much bigger, which tends to eat > up a lot of cache. Again, I haven't do an extensive test, but that's > what I found out on a high level when I played around with it. > > http://funroll-loops.info/ already in my bookmarks ... since 2005 ;) > 'Nuff Said :) > > Tim S. _______________________________________________ Mailing list: https://launchpad.net/~drizzle-discuss Post to : [email protected] Unsubscribe : https://launchpad.net/~drizzle-discuss More help : https://help.launchpad.net/ListHelp
