Re: [eigen] How do you link multiple versions (e.g. AVX vs SSE) of the same Eigen code? |

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*To*: eigen <eigen@xxxxxxxxxxxxxxxxxxx>*Subject*: Re: [eigen] How do you link multiple versions (e.g. AVX vs SSE) of the same Eigen code?*From*: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>*Date*: Tue, 27 Jan 2015 18:19:51 -0500*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=JCa05h8VtVJ8zRZi6q8NERTZda19+4iDl8RXweIDWLs=; b=VX8Uqe0ltEQkH55lYbDTUm7OkRy0DHb8lvwh2O+lROoiPmjkt/EINMm8pm2cxUuKl5 4LfiVcAVkYKAbAScGI1hJ2WlGYybIWavsistBodmQ5niW95pHuZvm+pmsYj/gwOJL0Da sRQOi38RZATr1Spnko9L0bPd8C0PgGbeYqx2qMEq5sAxfan14NbwEtYEXen/YfyMSZGm Lvt5qElnvLMFObpSntk+n2fgZLhRos0hACfkxjovjmYK5IeB0Z+eEa9t1xq/tt02luH1 i3WkqqiCDTc3HHwS93bYtCQIv2gIMtowW3rYxPn4VRuNhikSJuPRWdtYmfXQOYVvWER/ 92jQ==

Oh --- I was still living in a world where the Eigen ABI is unaffected by vectorization, which was the case at least until AVX.

Is alignof(Vector4d) actually 32 with AVX by default? So ABI is now dependent on compile flags?2015-01-27 18:17 GMT-05:00 Marc Glisse <marc.glisse@xxxxxxxx>:

On Tue, 27 Jan 2015, Benoit Jacob wrote:

An approach that works is to #define Eigen EigenAVX, but this is very

annoying because you can't anymore pass around Eigen objects, you have to

somehow reinterpret_cast them to EigenAVX objects.

I would expect EigenAVX::Vector4d to have an alignment of 32, and only 16 for EigenSSE::Vector4d (I did not check), which would mean they really are different types and you cannot pass the second one to a function expecting the first. So I am not sure how you intend to "pass around Eigen objects".

--

Marc Glisse

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