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Billy Holmes wrote: |
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|
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> Richard Fish wrote: |
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> |
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>> FYI, -mcpu is deprecated, and a synonym for -mtune, which is implied |
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>> by -march. So you can just take it out and get the same effect. |
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> |
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> |
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> I think some ebuilds filter out march, but don't filter out |
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> mcpu/mtune, so you can still get some processor specific optimizations |
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> out of it. |
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A quick grep of /usr/portage shows that many builds will use |
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replace-flags to replace one -march setting with another or with |
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-mtune/-mcpu. |
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There are a few that can filter -march altogether: |
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1. net-firewall/ipsec-tools: filters all "-march=c3" |
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2. media-libs/libvorbis: filters "-march=pentium?". |
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3. dev-lang/squeak: filters all -march, -mtune, -mcpu, and many many |
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other flags. |
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4. dev-libs/libffi: filters -march=k8, -march=athlon64, and march=opteron. |
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5. app-editors/emacs: filters all -march (only in 21.4-r1) |
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6. app-pda/iripdb: filters march=k8, -march=athlon64, and -march=opteron |
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7. media-tv/mythtv: filters all -march, -mtune, and -mcpu. |
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So for #1, 2, 4, 5, and 6, you are correct that mtune/mcpu could have |
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some benefit. However, IMO these are actually bugs...the ebuild should |
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be using replace-flags to set the appropriate -mtune option if it cannot |
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support -march. |
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For #3 & 7, you get no benefit of any march/mtune/mcpu settings. |
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Cheers, |
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-Richard |
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-- |
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