safe_unaligned_simd

Safe wrappers for unaligned SIMD load and store operations.

The goal of this crate is to remove the need for "unnecessary unsafe" code when using vector intrinsics to access memory, with no alignment requirements.

Platform-intrinsics that take raw pointers have been wrapped in functions that receive Rust reference types as arguments.

MSRV: 1.88

Why use this crate?

This crate is compatible with runtime feature detection.

Unlike some other safe architecture intrinsic wrappers, this crate does not lock the user into #[cfg()]-gating SIMD code behind compile-time CPU target feature declaration.

Supported target architectures

x86 / x86_64

• sse, sse2, avx, avx512f, avx512vl, avx512bw, avx512vbmi2

Some functions have variants that are generic over Cell array types, which allow for mutation of shared references. See the cell module for an example.

Example function signatures:

#[target_feature(enable = "sse")]
fn _mm_storeu_ps(mem_addr: &mut [f32; 4], a: __m128);
#[target_feature(enable = "sse2")]
fn _mm_store_sd(mem_addr: &mut f64, a: __m128d);
#[target_feature(enable = "avx")]
fn _mm256_loadu2_m128(hiaddr: &[f32; 4], loaddr: &[f32; 4]) -> __m256;

Currently, there is no plan to implement gather/scatter or avx2 masked load/store intrinsics for this platform.

avx512 - AVX-512 intrinsics require rustc 1.89 or later.

aarch64 / arm64ec

• neon

Example function signatures:

#[target_feature(enable = "neon")]
fn vld2_dup_s8(from: &[i8; 2]) -> int8x8x2_t;
#[target_feature(enable = "neon")]
fn vst1q_f64(into: &mut [f64; 2], val: float64x2_t);

wasm32

• simd128

Example function signatures:

#[target_feature(enable = "simd128")]
pub fn v128_load8_splat<T: Is1ByteUnaligned>(t: &T) -> v128;
#[target_feature(enable = "simd128")]
pub fn v128_store<T: Is16BytesUnaligned>(t: &mut T, v: v128);

License

This crate is licensed under either

• the MIT License, or
• the Apache License (Version 2.0)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.