fearless_simd 0.4.0

Safer and easier SIMD
Documentation 
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// Copyright 2024 the Fearless_SIMD Authors
// SPDX-License-Identifier: Apache-2.0 OR MIT

#![expect(
    missing_docs,
    reason = "TODO: https://github.com/linebender/fearless_simd/issues/40"
)]

use fearless_simd::{Level, dispatch, prelude::*};

// The WithSimd idea is adapted from pulp but is clunky; we
// will probably prefer the `dispatch!` macro.
struct Foo;

impl WithSimd for Foo {
    type Output = f32;

    #[inline(always)]
    fn with_simd<S: Simd>(self, simd: S) -> Self::Output {
        let a = simd.splat_f32x4(42.0);
        let b = a + a;
        b[0]
    }
}

#[inline(always)]
fn foo<S: Simd>(simd: S, x: f32) -> f32 {
    let n = S::f32s::N;
    println!("n = {n}");
    simd.splat_f32x4(x).sqrt()[0]
}

// currently requires `safe_wrappers` feature
fn do_something_on_neon(_level: Level) -> f32 {
    #[cfg(all(feature = "safe_wrappers", target_arch = "aarch64"))]
    if let Some(neon) = _level.as_neon() {
        return neon.vectorize(
            #[inline(always)]
            || {
                let v = neon.neon.vdupq_n_f32(42.0);
                neon.neon.vgetq_lane_f32::<0>(v)
            },
        );
    }
    0.0
}

fn main() {
    let level = Level::new();
    let x = level.dispatch(Foo);
    let y = dispatch!(level, simd => foo(simd, 42.0));
    let z = do_something_on_neon(level);

    println!("level = {level:?}, x = {x}, y = {y}, z = {z}");
}