# `Simd<[T; N]>` ## Implementation of [Rust RFC #2366: `std::simd`][rfc2366] [![Latest Version]][crates.io] [![docs]][master_docs] **WARNING**: this crate only supports the most recent nightly Rust toolchain and will be superseded by [`#![feature(portable_simd)]`](https://github.com/rust-lang/portable-simd). ## Documentation * [API docs (`master` branch)][master_docs] * [Performance guide][perf_guide] * [API docs (`docs.rs`)][docs.rs] * [RFC2366 `std::simd`][rfc2366]: - contains motivation, design rationale, discussion, etc. ## Examples Most of the examples come with both a scalar and a vectorized implementation. * [`aobench`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/aobench) * [`fannkuch_redux`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/fannkuch_redux) * [`matrix inverse`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/matrix_inverse) * [`mandelbrot`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/mandelbrot) * [`n-body`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/nbody) * [`options_pricing`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/options_pricing) * [`spectral_norm`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/spectral_norm) * [`triangle transform`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/triangle_xform) * [`stencil`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/stencil) * [`vector dot product`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/dot_product) ## Cargo features * `into_bits` (default: disabled): enables `FromBits`/`IntoBits` trait implementations for the vector types. These allow reinterpreting the bits of a vector type as those of another vector type safely by just using the `.into_bits()` method. ## Performance The following [ISPC] examples are also part of `packed_simd`'s [`examples/`](https://github.com/rust-lang-nursery/packed_simd/tree/master/examples/) directory, where `packed_simd`+[`rayon`][rayon] are used to emulate [ISPC]'s Single-Program-Multiple-Data (SPMD) programming model. The performance results on different hardware is shown in the `readme.md` of each example. The following table summarizes the performance ranges, where `+` means speed-up and `-` slowdown: * `aobench`: `[-1.02x, +1.53x]`, * `stencil`: `[+1.06x, +1.72x]`, * `mandelbrot`: `[-1.74x, +1.2x]`, * `options_pricing`: * `black_scholes`: `+1.0x` * `binomial_put`: `+1.4x` While SPMD is not the intended use case for `packed_simd`, it is possible to combine the library with [`rayon`][rayon] to poorly emulate [ISPC]'s SPMD programming model in Rust. Writing performant code is not as straightforward as with [ISPC], but with some care (e.g. see the [Performance Guide][perf_guide]) one can easily match and often out-perform [ISPC]'s "default performance". ## Platform support The following table describes the supported platforms: `build` shows whether the library compiles without issues for a given target, while `run` shows whether the test suite passes for a given target. | **Linux** | **build** | **run** | |---------------------------------------|-----------|---------| | `i586-unknown-linux-gnu` | ✓ | ✗ | | `i686-unknown-linux-gnu` | ✓ | ✗ | | `x86_64-unknown-linux-gnu` | ✓ | ✓ | | `arm-unknown-linux-gnueabihf` | ✓ | ✓ | | `armv7-unknown-linux-gnueabi` | ✓ | ✓ | | `aarch64-unknown-linux-gnu` | ✓ | ✓ | | `powerpc-unknown-linux-gnu` | ✓ | ✗ | | `powerpc64-unknown-linux-gnu` | ✓ | ✗ | | `powerpc64le-unknown-linux-gnu` | ✓ | ✓ | | `s390x-unknown-linux-gnu` | ✓ | ✗ | | `sparc64-unknown-linux-gnu` | ✓ | ✗ | | `thumbv7neon-unknown-linux-gnueabihf` | ✓ | ✓ | | **MacOSX** | **build** | **run** | | `x86_64-apple-darwin` | ✓ | ✓ | | **Android** | **build** | **run** | | `x86_64-linux-android` | ✓ | ✓ | | `armv7-linux-androideabi` | ✓ | ✗ | | `aarch64-linux-android` | ✓ | ✗ | | `thumbv7neon-linux-androideabi` | ✓ | ✗ | | **iOS** | **build** | **run** | | `x86_64-apple-ios` | ✗ | ✗ | | `aarch64-apple-ios` | ✗ | ✗ | ## Machine code verification The [`verify/`](https://github.com/rust-lang-nursery/packed_simd/tree/master/verify) crate tests disassembles the portable packed vector APIs at run-time and compares the generated machine code against the desired one to make sure that this crate remains efficient. ## License This project is licensed under either of * [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0) ([LICENSE-APACHE](LICENSE-APACHE)) * [MIT License](http://opensource.org/licenses/MIT) ([LICENSE-MIT](LICENSE-MIT)) at your option. ## Contributing We welcome all people who want to contribute. Please see the [contributing instructions] for more information. Contributions in any form (issues, pull requests, etc.) to this project must adhere to Rust's [Code of Conduct]. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in `packed_simd` by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions. [travis]: https://travis-ci.com/rust-lang/packed_simd [Travis-CI Status]: https://travis-ci.com/rust-lang/packed_simd.svg?branch=master [appveyor]: https://ci.appveyor.com/project/gnzlbg/packed-simd [Appveyor Status]: https://ci.appveyor.com/api/projects/status/hd7v9dvr442hgdix?svg=true [Latest Version]: https://img.shields.io/crates/v/packed_simd.svg [crates.io]: https://crates.io/crates/packed_simd [docs]: https://docs.rs/packed_simd/badge.svg [docs.rs]: https://docs.rs/packed_simd [master_docs]: https://rust-lang-nursery.github.io/packed_simd/packed_simd/ [perf_guide]: https://rust-lang-nursery.github.io/packed_simd/perf-guide/ [rfc2366]: https://github.com/rust-lang/rfcs/pull/2366 [ISPC]: https://ispc.github.io/ [rayon]: https://crates.io/crates/rayon [boost_license]: https://www.boost.org/LICENSE_1_0.txt [SLEEF]: https://sleef.org/ [sleef_sys]: https://crates.io/crates/sleef-sys [contributing instructions]: contributing.md [Code of Conduct]: https://www.rust-lang.org/en-US/conduct.html