6.7 KiB
Simd<[T; N]>
Implementation of Rust RFC #2366: std::simd
WARNING: this crate only supports the most recent nightly Rust toolchain
and will be superseded by #![feature(portable_simd)].
Documentation
- API docs (
masterbranch) - 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.
aobenchfannkuch_reduxmatrix inversemandelbrotn-bodyoptions_pricingspectral_normtriangle transformstencilvector dot product
Cargo features
into_bits(default: disabled): enablesFromBits/IntoBitstrait 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:+1.0xbinomial_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
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.