On Tue, Feb 10, 2004 at 12:14:46PM -0800, Roop Nanuwa wrote: > Part of my current /etc/make.conf on my 5.2-CURRENT box looks like: > > CPUTYPE= athlon-xp > CFLAGS= -O2 -pipe -fomit-frame-pointer -mmmx -msse -m3dnow -mfpmath=sse > COPTFLAGS= -O -pipe > > Now what I'm wondering is if those extras like mmmx msse actually do > anything. The > only reason they're in there is because I saw them on a website about > what people > use to optimize gentoo. I had nothing better to do so I recompiled the > world with > them. I didn't really notice anything good or bad happening after that. > I did have > to mess around with a couple of makefiles to get around the > strict-aliasing problem > that O2 introduces. Besides that, though, are there any advantages or > disadvantages > to compiling with those optimizations and switches? > > Does -mfpmath=sse actually do anything relevent for the FreeBSD world? I > know > what the GCC manual says about it but I'd rather hear some real world info. > > An enquiring mind wants to know.
That's superfluous, because gcc already uses all available opcodes when you tell it to optimize for your CPU type with CPUTYPE=athlon-xp. Using -O2 is recommended against, though - see the sample make.conf file. Kris
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