Add missing ARM64 instructions to Go ASM

[Clement-Jean]

After finally learning how to add instructions to Go ASM, I want to contribute to adding missing instructions for ARM64.

I'm aware of some of them missing in the SIMD land (e.g. #41092) but I'm also open to suggestions from people.

If there is any objection, let me know and I will stop working on this.

To follow the work you can check: https://github.com/Clement-Jean/go/tree/missing_arm64_instructions

[seankhliao]

this doesn't look like a concrete bug.

[Clement-Jean]

@seankhliao the goal wasn't about reporting a bug but checking if the team is OK getting help to implement the instructions. I made this issue out of courtesy.

Does this mean this is not needed and I should stop working on this?

[randall77]

This is probably a duplicate of #44734.
There was a bunch of work on that issue, but if I understand correctly progress has stalled. Maybe you could help out on that design if you were up for it.

[Clement-Jean]

This is not a duplicate per se because I was just thinking about adding the instructions and tests like it has been done up until now. However, I can see the appeal to redesign the framework for arm64 assembler to also support SVE and easier maintenance.

Let me read about it more, and I'll get back to you.

[Clement-Jean]

@randall77 while this seems very interesting, the redesign seems to be something for people who have more expertise in the ISA design (maybe people at Arm) and that have more time to spend on this than me. If you still want, I can try to add the instructions that are mentioned in the related issues but otherwise, I'll stop working on this.

[randall77]

I think it would be ok to add particular instructions to the existing assembler if there is a need for them.
But I'd rather not just add all the missing instructions to the existing assembler. It is difficult enough to maintain as it is.