Two years ago there was a Google Summer of Code project to implement these primitives in pure D for various reason. It was concluded the project isn't viable and was abandoned, but there were some interesting learnings. I now stumbled on some new work in C land about these that might be interesting to people that were following the original project so I am sharing it here:

Custom ASM implementation that outperforms libc: https://github.com/nadavrot/memset_benchmark
Paper on automatic implementation of these primitives: https://dl.acm.org/doi/pdf/10.1145/3459898.3463904

On Saturday, 27 November 2021 at 11:15:45 UTC, Igor wrote:

Haven't read yet, but how did they make it portable?

On Saturday, 27 November 2021 at 11:15:45 UTC, Igor wrote:

Also LLVM has intrinsics or special instructions for those libc stuff. I suppose that there are special optimz that are tried and if not possible that falls back to the libc version.

On Saturday, 27 November 2021 at 11:15:45 UTC, Igor wrote:

Additionally, here is the twitter thread from the author: https://twitter.com/nadavrot/status/1464364562409422852

On Saturday, 27 November 2021 at 11:48:02 UTC, Imperatorn wrote:

Regarding custom ASM implementation I think it is only for X64 platform.