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Since Eigen matrices and vectors use SSE and therefore require a

2010/10/14 <lfrfly@icqmail.com>: particular

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alignment, Eigen requires that when these types (specifically, the compile-time sized versions) are within a struct or class, that struct be given the EIGEN_MAKE_ALIGNED_OPERATOR_NEW macro.

What we do require is that e.g. Vector4f's be created at 16 byte aligned locations. EIGEN_MAKE_ALIGNED_OPERATOR_NEW is just one way of doing that.

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But here's the problem. What if that struct is allocated by a boost::pool_allocator<T>? Is there any way to enforce alignment then?

That's a question for boost::pool_allocator, not for us; if this allocator doesn't give you 16 byte alignment, then you need a different allocator (or just modify this allocator to meet this criterion).

The allocator is what gives you an address. If it's giving non-16-byte-aligned addresses, then it can't be used.

Benoit

It's now clear that this question belongs firmly on the Boost.Pool side of the fence, so here it is---I'm wondering why boost::pool_allocator isn't designed to work with a standard-compliant allocator as its second template parameter? I tried creating a boost::fast_pool_allocator<T, Eigen::aligned_allocator<T>>, but this failed with a compile error----apparently fast_pool_allocator has an unusual notion of what concept a UserAllocator should satisfy, requiring the methods malloc() and free(). Why does it not accept any standard allocator, which will instead provide allocate() and deallocate()? This seems like a serious shortcoming.