V6 [PATCH] x86: Add <sys/platform/x86.h>

[Florian Weimer]

* H. J. Lu:

> On 10/25/18, Florian Weimer <fweimer@redhat.com> wrote:
>> * H. J. Lu:
>>
>>
>>> Here is the patch with CPU_FEATURE_USABLE only.  OK for master
>>> branch?
>>
>> Thanks.  Recently, the matter of special-casing code inside target
>> clones came up on the glibc list:
>
> I am going to check it in.
>
>>   <https://gcc.gnu.org/ml/gcc-help/2018-10/msg00118.html>
>>
>> Do you think it might be possible to eventually turn some results for
>> CPU_FEATURE_USABLE in target clones into compile-time constants because
>> the compiler knows the results of the feature selection in the
>> automatically generated IFUNC resolver?
>
> By definition, CPU_FEATURE_USABLE is evaluated at run-time.
> Can GCC be extended to allow intrinsics in target_clone.

I am wondering if we can tweak CPU_FEATURE_USABLE in such a way that it
can be easily compatible with future intrinsics.

Thanks,
Florian