# Portable SIMD 2020-11-09 Meeting ###### tags: `Portable SIMD` `Minutes` [Last Week] | [This Week's Chat] | [Next Week] [Last Week]: https://hackmd.io/Am3uOG2mSBmG6R7TtwucgQ [This Week's Chat]: https://rust-lang.zulipchat.com/#narrow/stream/257879-project-portable-simd/topic/Meeting.202020-11-09 [Next Week]: https://hackmd.io/z_gTcq9CSyegzgclNrlRzg ## Agenda - Anything blocking comparisons? https://github.com/rust-lang/stdsimd/pull/44 - MCP for more `extern "platform-intrinsic"` and for fallback implementations: https://github.com/rust-lang/compiler-team/issues/381 - Allow `#[repr(simd)]` with `[T; N]` https://github.com/rust-lang/rust/pull/78863 ## Outcomes - See whether we can dispel currently used direct LLVM intrinsics from `core_simd`. If that solves our compilation issue on RISCV then we can consider that no longer a blocker. - Review the PR for masks and merge if we're happy with the approach. - Get more feedback on the MCP for fallback intrinsics. ## Summary ### Masks https://github.com/rust-lang/stdsimd/pull/44 - There are some compilation errors in the tests right now to fix up. - We spent a while before opening the PR discussing designs for the masks API. This PR uses opaque types to represent them. - We might want to come up with alternatives based on the experience of using this approach. ### Wiring up backend-agnostic intrinsics https://github.com/rust-lang/compiler-team/issues/381 - MCP is updated with some more detail and is ready for more `t-compiler` input. - We're generally happy with the approach, even if it uses more concrete machinery than we'd really like. Alternatives have big open design spaces to explore, where this is fairly well constrained. ### Allowing `#[repr(simd)]` on `A([T; N])` https://github.com/rust-lang/rust/pull/78863 - The original PR has been rebased. - There are some codegen issues that we might need to spend some time investigating. ### `packed_simd` - No obvious issues that need to be raised right now.