> You typically need a human to rewrite SSE, AVX [...] so that performance stays competitive.
Not true. As I commented a few days ago: There is sse2neon https://github.com/jratcliff63367/sse2neon. For intrinsics it supports, you only need to add a header to automatically map SSE intrinsics to NEON. There is also simde https://github.com/nemequ/simde. It is a larger project and may be more complete. These projects are still immature for sure, but when arm mac becomes a real thing, we will see better libraries that support SIMDs over different architectures.
Not true. As I commented a few days ago: There is sse2neon https://github.com/jratcliff63367/sse2neon. For intrinsics it supports, you only need to add a header to automatically map SSE intrinsics to NEON. There is also simde https://github.com/nemequ/simde. It is a larger project and may be more complete. These projects are still immature for sure, but when arm mac becomes a real thing, we will see better libraries that support SIMDs over different architectures.