# Portable SIMD 2021-05-24 Meeting

###### tags: `Portable SIMD` `Minutes`

[Last Meeting] | [This Meeting's Chat] | [Next Meeting]

[Last Meeting]: https://hackmd.io/bk7HHiZeSaC7r1tnwFtZhA
[This Meeting's Chat]: https://rust-lang.zulipchat.com/#narrow/stream/257879-project-portable-simd/topic/Meeting.202021-05-24
[Next Meeting]: https://hackmd.io/K-qO8F32TEKjUSrbiimNtw

## Agenda
From last week's notes:

0. are we ready to open a PR to land on nightly?
1. what did wg-llvm say?
a. libmvec idea seems technically feasible
b. wg-llvm says it is less maintainable to add this to the rust fork, it should be pushed to upstream ideally.
2. have we added `scatter`, `gather`, `{to,from}_ne_bytes`?
3. we need to draft the RFC?
4. schedule vector-of-pointers for review someday, somewhere :rainbow:
5. schedule cranelift review for someday
6. rustc stability attributes status?
7. simd_fsqrt!
8. trig and/or approximation functions!
- Andy offered some code!

## Resolutions

0. No!
1. Jacob will follow up on the mailing list.
a. we should probably add a FAQ about this somewhere
2. have we added `scatter`, `gather`, `{to,from}_ne_bytes`?
a. no
b. no
c. there is a PR open for it https://github.com/rust-lang/stdsimd/pull/121. merged!
3. some [draft notes](https://hackmd.io/u-XfyDs7QDm4H4zjFFXgAg) were scraped together, PR them to repo?
4. schedule vector-of-pointers for review someday, somewhere :rainbow: ...asynchronously.
5. cranelift!
a. also could use a FAQ
b. no progress, itemize it and post an issue?
- https://github.com/bjorn3/rustc_codegen_cranelift/issues/171
- https://github.com/bytecodealliance/wasmtime/tree/main/cranelift
- https://github.com/bjorn3/rustc_codegen_cranelift/issues/1175
6. stability attrs: no progress yet
- Jubilee will try to take care of this
- followup: add rustc stability attrs to fn/items, mostly?
7. PR: https://github.com/rust-lang/stdsimd/pull/120
- followup: Caleb was pinged
- Jacob is working on a vector fsqrt version
8. trig functions! more questions than answers:
- do we care about matching scalar f32/f64?
- how many ulps do we care about?
- alternatively: how much max error do we care about?
- what kind of performance gains do we care about?

## Next Time, on Dragon Ball Z
- Jacob: what did llvm-dev say?
- Jubilee: stability annotations?
- bjorn3: cranelift?
- scatter/gather?
- do we know more about what we want from trig?
- to-nightly PR status?
- RFC draft status?
- vector of pointers?