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Am 02.05.2015 um 14:06 schrieb Nikos Chantziaras: |
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> On 02/05/15 14:37, Volker Armin Hemmann wrote: |
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>> Am 02.05.2015 um 13:25 schrieb Nikos Chantziaras: |
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>>>>> |
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>>>>> The kernel uses -O2 and several -march variants (e.g. -march=core2). |
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>>>>> Several other options are used to prevent GCC from generating |
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>>>>> unsuitable code. |
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>>>>> |
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>>>>> Specifying another -march variant does not affect the optimizer |
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>>>>> though. It only affects the code generator. If you don't modify the |
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>>>>> other CFLAGS and only change -march, you will not get FP instructions |
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>>>>> unless you use FP in the code. |
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>>>> |
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>>>> http://www.agner.org/optimize/calling_conventions.pdf |
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>>> |
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>>> Not sure what you're trying to say. |
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>>> |
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>> |
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>> that simd is not save in kernel if not carefully guarded. |
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>> |
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>> Really people, just don't fuck around with the cflags. |
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> |
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> I still fail to see the relevance. Unless you mean using a different |
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> -O level. In that case, yes. You shouldn't. But I was talking about |
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> -march. |
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> |
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|
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you said this |
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> |
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> (note that SIMD is not FP and is perfectly fine in the kernel.) |
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and I have shown you that you are wrong. |
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