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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] Status of AVX support
- From: Rohit Garg <rpg.314@xxxxxxxxx>
- Date: Wed, 7 Dec 2011 12:05:20 -0500
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If you compile with -mavx, there will be no SSE code generated by GCC.
The SSE intrinsics will compile to corresponding AVX intrinsics. So
this penalty is not much of a bother.
On Wed, Dec 7, 2011 at 11:23 AM, Rhys Ulerich <rhys.ulerich@xxxxxxxxx> wrote:
>> W.r.t porting to AVX: Be aware that there might be some pitfalls with
>> AVX-performance:
>> http://www.agner.org/optimize/blog/read.php?i=142
>
> Interesting tidbit from that link "If the programmer inadvertently
> mixes AVX and non-AVX vector instructions in the same code then there
> is a penalty of 70 clock cycles for each transition between the two
> forms."
>
> Thank you for the pointer to the blog,
> Rhys
>
>
--
Rohit Garg
http://rpg-314.blogspot.com/
Graduate Student
Applied and Engineering Physics
Cornell University