Simd<[T; N]>

Implementation of Rust RFC #2366: std::simd

![Latest Version] ![docs]

WARNING: this crate only supports the most recent nightly Rust toolchain and will be superseded by #![feature(portable_simd)].

Documentation

• API docs (master branch)
• Performance guide
• API docs (docs.rs)
• RFC2366 std::simd: - contains motivation, design rationale, discussion, etc.

Examples

Most of the examples come with both a scalar and a vectorized implementation.

• aobench
• fannkuch_redux
• matrix inverse
• mandelbrot
• n-body
• options_pricing
• spectral_norm
• triangle transform
• stencil
• vector 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/ directory, where packed_simd+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 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) 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/ 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 (LICENSE-APACHE)

• MIT License (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.