Currently in stdc there is an experimental extension for wrapping SIMD (https://en.cppreference.com/w/cpp/experimental/simd/simd). It is part of the ISO/IEC TS 19570:2018 Section 9 “Data-Parallel Types”. The wrapper allows to use vectorizations independent of the platform it can be used to optimize for (SSE/AVX/AVX512). It uses CPP templates to do this. For an introduction please check https://www.youtube.com/watch?v=8khWb-Bhhvs
Having access to a library already implementing this standard would benefit us as it makes it easier to optimize parts of our code base. Currently we have several places where we implement a section twice (non SSE and SSE supported). Having these wrappers we would still need to implement these twice (non SIMD and SIMD), but the SIMD versions would be more readable and support more hardware platforms than only SSE. There are also a few implementations that implement the ISO Standard.
My proposal is to add a
BLI_simd.hh that wraps one of the available implementations. When it becomes available in the future we could simply migrate over by including the right SIMD.
Side note: SIMD isn’t a magic bullet. It needs to go hand in hand with address locality for best performance. Striving for Address locality can be difficult in certain areas of blender and SIMD would not add any benefits.
Areas where I would like to use it is to optimize the modifier. What is lacking in this proposal is the selection of the library to use, but that will be done in a follow-up proposal.