Hello rust-dev! I implemented OpenCL-style[0] accessors for SIMD types in Rust[1], the code quality isn't near /merge-worthy yet, but I wanted some input.
For some code-examples, go to https://github.com/jensnockert/rust/tree/simd/src/test/run-pass/simd-test and check it out, you should be able to get the idea of how they work. Note that I didn't add any actual syntax for vector types yet (since it would be highly controversial and I don't know what would be the best option), so I just added a simd!(name: T * n) syntax extension that declares a new type that maps down to a LLVM <n * T>. My preference for syntax right now would be simd!(n x T) if I can get that to parse, or simd!(T, ..n). And then you would declare a type with type f32x4 = simd(4 x f32); and it would magically work. Another option would be some variant of the [T, ..n] syntax used for fixed-length vectors. Introducing a new t, ty_simd_vec(t, uint), instead of using the current #[simd] struct { … }, is yet another thing that is controversial about the patch and this needs a bit of explanation of the problem with #[simd] struct { … }. To be able to make these accessors work, you unfortunately need to be able to generate anonymous types in the compiler, x.even for example (take the even-indexed elements of a vector) may be a type that is undeclared. And if you want to be able to pretty-print that, you need to be able to generate a type without a name, which makes #[simd] struct { … } impossible. You could just pre-declare all possible options up to 256-bit long, which probably would only be a hundred types or so, but would feel a bit silly. There are also other operations that could generate (possibly) unnamed types, like a == b, which should generate a i1-vector, or a shufflevector intrinsic that could generate vectors of any length. Ps. I didn't think of #[simd] (T, T, T, T) &c. before implementing (sanxiyn gave me that idea), but I still think that is probably a worse idea than adding SIMD as an additional type with actual syntax. [0]: http://www.khronos.org/files/opencl-quick-reference-card.pdf, page 2, "Vector Component Addressing" [1]: https://github.com/jensnockert/rust/tree/simd _______________________________________________ Rust-dev mailing list Rust-dev@mozilla.org https://mail.mozilla.org/listinfo/rust-dev
