Re: [gentoo-dev] [PATCH 1/2] profiles/desc: descriptions for CPU_FLAGS_PPC use_expand

[Georgy Yakovlev <gyakovlev@gentoo.org>]

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On 8/30/19 11:29 PM, Michał Górny wrote:
> On Sat, 2019-08-31 at 00:19 -0700, Georgy Yakovlev wrote:
>> On 8/30/19 11:11 PM, Michał Górny wrote:
>>> On Sat, 2019-08-31 at 00:03 -0700, Georgy Yakovlev wrote:
>> <snip>
>>>> +altivec - Use the AltiVec instruction set
>>>> +vsx - Use the Vector Scalar Extension instruction set (POWER7 and later)
>>>> +vsx3 - Use the Vector Scalar Extension v.3 instruction set (POWER9 and later)
>>>
>>> Do all those flags have real use cases in ::gentoo?  I'd really prefer
>>> not having more 'unused flag' warnings ;-).
>>>
>>
>> yeah, I have mentioned possible users above and there are plenty I
>> haven't identified yet. patches to ebuilds will follow, I promise =)
>>
>> for example x264 if built with proper flags gives a noticeable boost,
>> (at least 2x at encoding), totally worth it.
>>
>> ppc will not have a lot of flags like on arm or x86, maybe a couple
>> more, but that's it for now.
>>
> 
> Just to be clear: we're not talking about -m compiler flags, are we? 
> 'cause those should be handled via CFLAGS.
> 

of course not just compiler flags, that's clear.

for example libpng has --enable-powerpc-vsx ./configure flag, and build
system will do it's black magic with intrinsics if it's passed.


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