Use AVX/AVX512 selectively

[Victor Rodriguez]

On Thu, Mar 3, 2016 at 8:49 AM, Florian Weimer <fw@deneb.enyo.de> wrote:
> * Victor Rodriguez:
>
>> On Thu, Mar 3, 2016 at 8:31 AM, Florian Weimer <fw@deneb.enyo.de> wrote:
>>> * Victor Rodriguez:
>>>
>>>> What HW are you ussing ?
>>>
>>> Both hardware with amd without avx512f capability.  There is run-time
>>> detection for it, but for it to be effective, most of the program has
>>> to be compiled without -mavx512f, otherwise the program will use
>>> avx512f instructions before getting to the detection code.
>>
>> Have you try Function Multi Versioning ?
>
> According to the GCC documentation, "avx2" and so on are not supported
> as targets in target function attributes.  Perhaps this is incorrect
> and the manual needs fixing?

Yes they are in the latest GCC ( mainline ) or in the Clear Linux GCC
( I added the patches :P )