Am Freitag 20 Juli 2007 20:16 schrieb Kenneth Prugh: > Andrew Gaydenko wrote: > > I have noticed, the official portage tree has included gcc 4.2. Now for > > Core 2 Duo CPU (amd64 Gentoo arch) I use in make.conf file: > > > > CFLAGS="-O2 -march=nocona -pipe" > > > > gcc' changelog has this note: > > > > -------------------- > > ... > > IA-32/x86-64 > > > > * -mtune=generic can now be used to generate code running well on > > common x86 chips. This includes AMD Athlon, AMD Opteron, Intel Pentium-M, > > Intel Pentium 4 and Intel Core 2. > > * -mtune=native and -march=native will produce code optimized for the > > host architecture as detected using the cpuid instruction. > > ... > > -------------------- > > > > The question is: must I replace '-march=nocona' with '-mtune=native and > > -march=native'? > > I have a Core2 Duo E6600 and use these CFLAGS with GCC 4.2: > > CFLAGS="-Os -march=native -mtune=native -fomit-frame-pointer -pipe -mmmx > -msse2 -msse3" > > Native works fine here.
I don't think that you need -msse3 -msse2 and -mmmx because -march takes care of that (refer to "man gcc", one notable exeption: -march=athlon64 does not pull -msse3 in because not all Athlons support it). -fomit-frame-pointer is unneccessary on AMD64 (refer to "man gcc", again).
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