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