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 18:22:59 -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=CGDMAliBYt1Z8dp0SwHCWCbWSb0JpufMmx4Sj1RUfZk=; b=WMlFbUz7v5FhALN9K/LIZgCqQQ4TdH2LEPfO/xeL/urHuxJKFw0SfFT/O/9rNfj+Wi BLny2tg0D49xZhNSzUBJdofjeGRnnhF3QvRb++Nw23dqSp7/H/ueutXF8QcDbU1oIqAZ yiErVY2ivc66t4JozcuWB/OcpOMkfxYnCv+BwrXBnmqA68c4nuMeRmISYGL4NrI0mVKV 8CPpMdyWbcUR6c5uqFK/lAdj1TrUqgVgr0S3cu0VpAzzOrhnxhorOyJ9ANUYzlE6IVxJ klAAreYqQB99GCqcuLs2SBpZIRLPSqCR+NEntlHaYYKY4QXI+kkpEyv9eLdnuym1an8u nYXA==

Ouch... you're right. From Macros.h:

#if defined(__AVX__)

#undef EIGEN_ALIGN_BYTES

#define EIGEN_ALIGN_BYTES 32

#endif

#if defined(__AVX__)

#undef EIGEN_ALIGN_BYTES

#define EIGEN_ALIGN_BYTES 32

#endif

2015-01-27 18:19 GMT-05:00 Benoit Jacob <jacob.benoit.1@xxxxxxxxx>:

BenoitOh --- 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

**Follow-Ups**:

**References**:**[eigen] How do you link multiple versions (e.g. AVX vs SSE) of the same Eigen code?***From:*Benoit Jacob

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

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

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