Re: [eigen] STL Vectors and Alignment |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] STL Vectors and Alignment*From*: Gabriel <gnuetzi@xxxxxxxxx>*Date*: Wed, 26 Nov 2014 17:39:02 +0100*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type; bh=oiCYWVi32WhjzhhkvHiDGG9Z14Pb1D9ohcBnAPWHNUI=; b=Hak60CFDmVEpulW4hj5KRQW30JyQOe5yo5o67ykjdS43K9wMWWAy6DKN+cD4m35hqv /vVQAdoSijIN/t33i6GVWfEax5TwfiVQjLYrJbYOuyczuCjcbh1cuhQqr2fMK53PDggf +IPBvPJKQ4GTjOMPE6Wm92S4K338k+k6TLHhym9vD5UIdMlJW+zqXENNG/qV2EYA3A8M ygXaNoylM4ihfkr13NVgMINqqy1/RC731sezQ2eAJKMXXrAl6rTNUyCkp7HEnKrZiuWe c28LFMk1iDnfaEXEA0Mz6fvhB0OjPH846gq/WE/gqT5apjLkSIvNhoMx3UX9Rn4+TXC9 IwwA==

Thanks for the answer! Sorry again for my unclear phrasing! Just to be absolutely sure: Lets say we have: struct A{ Eigen::Vector2d t; }; If we use A locally: A a; a.t is a.t aligned on the Stack, (how does alignment work on the stack) If we use A on the heap: A * a = new A; then as "a" is not aligned , also a.t is not aligned If we use EIGEN_MAKE_ALLOCATOR_NEW inside A , then "a" is aligned , and BUT what happens in this example: struct B{ A a; }; struct C{ B b; }; std::vector< C , Eigen::aligned_allocator<C> > vec(1); Is vec[0].b.a.t now aligned in memory? which does NOT
result in a segfault if Eigen uses SIMD internally?If we use locally lets say: C c; c.b.a.t do something with t is c.b.a.t aligned on the Stack? Or on the heap: C * c = new C; c might not be aligned => c.b might not be aligned => c.b.a => might not bealigned => c.b.a.t might not be aligned => SEGFAULT for usage of c.b.a.t How do I need to correct the above example such that in the cases above, vector A::t is always aligned to 16bytes? Thanks for the help! Gabriel On 11/26/2014 04:40 PM, Christoph
Hertzberg wrote:
On 26.11.2014 16:17, Gabriel wrote: |

**Follow-Ups**:**Re: [eigen] STL Vectors and Alignment***From:*Christoph Hertzberg

**References**:**[eigen] Block sparse matrices and std vector compilation error***From:*Hilario Tomé

**[eigen] STL Vectors and Alignment***From:*Gabriel

**[eigen] STL Vectors and Alignment***From:*Gabriel

**Re: [eigen] STL Vectors and Alignment***From:*Christoph Hertzberg

**Re: [eigen] STL Vectors and Alignment***From:*Gabriel

**Re: [eigen] STL Vectors and Alignment***From:*Christoph Hertzberg

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