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On Freitag, 20. Juli 2007, 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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first of all: using mtune AND march is stupid |
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Second, that 'feature' means that gcc looks at your CHOST and use that for the |
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march/mtune setting. |
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So no, don't change anything at all. march=nocona is fine. Don't touch it. |
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-- |
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