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

Michael, the latest revision of the code, when run, aborts when running the SSEopt_vec method, as detailed here: https://github.com/cppljevans/soa/blob/master/soa_compare.benchmark.cpp#L953 Would you have some idea what's causing that? On 10/28/2016 09:40 PM, Michael Marcin wrote:

On 10/28/2016 9:09 AM, Larry Evans wrote:

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On 10/26/2016 10:00 AM, Michael Marcin wrote: [snip]

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The sse emitter test used an aligned_allocator to guarantee 16 byte alignment for the std::vector data.

template< typename T > using sse_vector = vector >;

I assume that vector<T>'s data is allocated with new, and new, IIUC, guarantees maximum alignment; hence, boost::alignment::is_aligned(std::vector<T>::data(),16) should always be true. What am I missing?

Yes operator new isn't going to guarantee a 16 byte alignment on any platform I'm aware of.

From n4606 [snip] Detailed reference to standard Docs correcting my assumptions.

Thanks for the [snipped] detailed reference to standard Docs correcting my assumptions :) It must have taken a lot of detailed reading!

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BTW, see the new push:

https://github.com/cppljevans/soa/commit/ea28ff814c8c1ea879fa5ac2453c12fc382...

I've *not tested* it in:

https://github.com/cppljevans/soa/blob/master/soa_compare.benchmark.cpp

but I think it should work.

Since that post, I've actually tested with the benchmark, and it ran. That run was done with the previous revision, the one with: https://github.com/cppljevans/soa/commit/02791e47080bf51ac3a467ed89e7cb91abf... Strangely, that one ran the SSEopt_vec method OK, in constrast to the current SSEopt_vec method.

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IOW, instead of:

sse_vector<float> position_x; sse_vector<float> position_y; sse_vector<float> position_z; sse_vector<float> velocity_x; sse_vector<float> velocity_y; sse_vector<float> velocity_z; sse_vector<float> acceleration_x; sse_vector<float> acceleration_y; sse_vector<float> acceleration_z; vector<float2> size; vector<float4> color; sse_vector<float> energy; vector<char> alive;

I think you could use:

soa_block < type_align,// position_x; type_align,// position_y; type_align,// position_z; type_align,// velocity_x; type_align,// velocity_y; type_align,// velocity_z; type_align,// acceleration_x; type_align,// acceleration_y; type_align,// acceleration_z; float2_t,// size; float4_t,// color; type_align,// energy; char// alive; > particles;

where type_align is found here:

https://github.com/cppljevans/soa/blob/master/vec_offsets.hpp#L14

That's quite similar to what I have in one of my potential implementations.

Would you post that somewhere? I'd be curious about how it differs. -regards, Larry