move to array simd #1422
move to array simd #1422
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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @Amanieu (or someone else) soon. |
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Gah, different architectures cause pain here. |
| pub(crate) const fn new($($elem_name: $elem_ty),*) -> Self { | ||
| $id($($elem_name),*) | ||
| pub(crate) const fn new(val: [$ety; $ecount]) -> Self { | ||
| $id(val) |
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From what I've heard, the plan is to make any direct field accesses (including calling the constructor like this) illegal on #[repr(simd)] types and only allow creation of the type and access to the inner array through transmute or pointer operations, so I think it might make sense to make the struct field private and to do something similar to rust-lang/portable-simd#339 or rust-lang/portable-simd#342 in new and splat.
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I think it'd also be fine for that to be a separate PR, if you prefer.
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direct field accesses (including calling the constructor like this) illegal
Emphasis on plan. This isn't happening with the current MCP, we are just removing the field-style #[repr(simd)]. In the longer term, I think scottmcm and other people have plans for that but not immediately.
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| #[allow(clippy::use_self)] | ||
| impl $id { | ||
| #[inline(always)] | ||
| pub(crate) const fn new($($elem_name: $elem_ty),*) -> Self { |
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That is less ergonomic, shall we consider adding From implementation to support both tuple and array and keep new as it is now?
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Note that this was always pub(crate), so users couldn't call it anyway.
They can only be created using intrinsics (or memory stuff like transmutes) in stable today: https://doc.rust-lang.org/core/arch/x86/struct.__m128i.html.
(The portable-simd types do have nice safe public constructors. But these arch ones intentionally don't.)
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As part of compiler-team/MCP#621, this repo must be updated to use the new-style array fields instead.
Note that a very recent nightly is needed which fixed a bug where inline assembly could not be used with the array style.
Note also that this cannot be pulled to
rust-lang/rustuntil beta updates with the bugfix.cc @scottmcm