porting-advisor VS sse2neon

Another tool which may be useful is aarch64 Porting Advisor. It is a quick way to identify architecture specific code. Porting Advisor is not needed for the simple example presented above, but if there are architecture specific intrinsics hiding deep in a larger project it can help find them.

The sse2neon project is a quick way to get C/C++ applications compiling and running on Graviton. The sse2neon header file provides NEON implementations for x64 intrinsics so no source code changes are needed. Each function call (intrinsic) is simply replaced with NEON instructions and will just work on Graviton.

To continue our collaboration I contributed some small changes to KasmVNC on GitHub to use sse2neon for a performance critical part of the application which uses SSE intrinsics and needed to be changed to NEON intrinsics.

I think the talk is very clearly laid out as an incremental journey, and each stepping stone involves contextual decision-making. I don't think Andreas is saying "you must end up with the SSE2 implementation at the end". Using machine-specific intrinsics is another dependency decision very similar to deciding to use a given library. I would have loved the talk and probably still thought of it and posted it, even if it ended before the intrinsics (but I think he does an excellent job at that part too).

And porting SSE2 to Neon is actually pretty easy -- if you use https://github.com/DLTcollab/sse2neon, IME it's very easy to do incrementally (or avoid or postpone indefinitely, depending on your needs).

I have a private cross-platform port, I’m waiting on the resolution of his latest GitHub issue to submit my changes. sse2neon (https://github.com/DLTcollab/sse2neon) was a big help - I also wrote a very primitive sse2scalar for raspbian builds where neon is unavailable. Honestly SIMD doesn’t help much, as you’re usually memory bound under SWGL. The biggest perf win is any amount of asynchronous execution - running off the main thread is good enough and could be applied to your library externally through a command buffer without any changes to your code.

You should go to /include/simd and download sse2neon.h into the folder. Replace appearing in any source files in that directory with "sse2neon.h". You will still encounter errors; remove the lines causing problems, typically containing the phrase ZERO_MODE. ARM processors does not require it.