Re: [eigen] Eigen containers cannot be vectorized

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On Dec 8, 2016, at 3:21 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:

Interesting analysis!
I would draw a different conclusion from it though: compiler auto-vectorization is hopeless :-)
Which is why explicitly-vectorized code like Eigen exists :-)


Hi Benoit.

Automatic vectorization is difficult, but not hopeless. I agree that the compiler needs help from time to time, especially in C/C++ because of pointer aliasing. But Intel compilers do a lot with automatic vectorization. Since you look french, here is a video I have done for Intel showing the optimization of a code that relies completely on automatic vectorization : . Sorry, I don’t have any english version yet.

François Fayard
Founder & Consultant - Inside Loop
Applied Mathematics & High Performance Computing
Tel: +33 (0)6 01 44 06 93

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