Re: [boost] interest in structure of arrays container?

On 10/25/2016 11:07 PM, Michael Marcin wrote:

On 10/25/2016 8:23 PM, Larry Evans wrote:

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At the very least support for the basic SSE 16 byte alignment of subarrays is crucial.

My best idea so far is some magic wrapper type that gets special treatment. Like: using data_t = soa_block< float3, soa_align, bool >;

Something like:

template struct alignas(Alignment) soa_align { T data; };

Have you tried that yet. If not, I might try.

The issue is you don't want to overalign all elements of the array, just the first element.

But aligning the first soa_align is all that's needed because sizeof(soa_align)%A == 0, hence, all subsequent elements would be aligned. At least that's my understanding. Am I missing something?

I have a working solution (using Peter Dimov's mp11 library as I'm not well-versed in post cpp03 metaprogramming).

I'm just trying to play around with implementation ideas at the moment.

Basically it'd be a nice to store only a single pointer and cheap constant time member sub-array access.

But with alignment concerns all I've managed so far are two implementations.

1. 1 pointer with linear time member array access 2. n-pointers with constant time member array access

I feel like there should exist implementation that trades a bit of dynamic allocation size for a single pointer and constant time member array access.

I intended soa_block to fill that need (after all the tasks shown in the **TODO** comments were done). If you see some flaw in the code, of course, I love to hear about it. **TODO** -regards, Larry