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Re: gcc Digest 26 Dec 2014 16:51:42 -0000 Issue 7953


2015-01-13 14:28 GMT+03:00 Jakub Jelinek <jakub@redhat.com>:
> On Tue, Jan 13, 2015 at 02:14:30PM +0300, Andrew Senkevich wrote:
>> >> Consensus is required to commit x86_64 vector math functions by Glibc
>> >> maintainer.
>> >
>> > With the difference that b stands for SSE2, not SSE4, and the fact
>> > that those functions do not use the __regcall calling conventions, but
>> > normal psABI calling conventions after replacing the arguments/return values
>> > with the vectors documented in the 0.9.5 pdf (and/or adding the vector mask
>> > arg) it describes what has been implemented, yes.
>>
>> But which name use for SSE4?
>> Gcc generates the same as for SSE2, and we now have SSE4 implementations.
>
> You probably need to use IFUNC for that.  The problem is that the
> _Z*b* symbol can be called even in code that requires only SSE2 HW, so you
> can't assume that because somebody called you through this symbol you have
> SSE4 available.  You know you have at least SSE2 or higher available.

Ok, we can add SSE2 implementations and IFUNC selection and reflect it
in agreement also.


--
WBR,
Andrew


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