Robert Crawford wrote:
On Sun December 4 2005 4:11 am, Kristian Poul Herkild wrote:
-mfpmath=sse is not a good idea, the consensus is it actually lowers
performance. -msse -mmmx -m3dnow are redundant (implied by
-march=athlon-xp), and should be removed from your cflags line, but SHOULD be
placed in your USE= line, wthout the - sign, like this:
USE="mmx 3dnow sse"
If you use gcc-3.4.4, these flags should work fine (I've used them for a long
time- no problems).
CFLAGS="-march=athlon-xp -O3 -pipe -fomit-frame-pointer -fweb -ftracer
-fprefetch-loop-arrays -ffast-math -falign-functions=64 -fno-ident"
CXXFLAGS="${CFLAGS} -fvisibility-inlines-hidden"
Hmm... according to this thread
http://forums.gentoo.org/viewtopic.php?t=43648 and the GCC manual -march
does not imply -mmx -msse -m3dnow, nor does it imply mfpmath=sse. I know
of no consensus of -mfpmath=sse lowering performance. Actually, I only
know of the opposite from the LFS-community as well as Gentoo Wiki.
I don't want to start a flamewar on this, so if you have other and more
correct information than me, then please share it :)
-Kristian Poul Herkild
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