minisimd.rs

//! Auxiliary crate for tests that need SIMD types.
//!
//! Historically the tests just made their own, but projections into simd types
//! was banned by <https://github.com/rust-lang/compiler-team/issues/838>, which
//! breaks `derive(Clone)`, so this exists to give easily-usable types that can
//! be used without copy-pasting the definitions of the helpers everywhere.
//!
//! This makes no attempt to guard against ICEs.  Using it with proper types
//! and such is your responsibility in the tests you write.

#![allow(unused)]
#![allow(non_camel_case_types)]
// FIXME: `cfg(minisimd_const)` is used to toggle use of const trait impls, which require a few
// nightly features. Remove this when `const_trait_impls`, `const_cmp` and `const_index` are
// stablilized.
#![allow(unexpected_cfgs)]

// The field is currently left `pub` for convenience in porting tests, many of
// which attempt to just construct it directly. That still works; it's just the
// `.0` projection that doesn't.
#[repr(simd)]
#[derive(Copy, Eq)]
pub struct Simd<T, const N: usize>(pub [T; N]);

impl<T: Copy, const N: usize> Clone for Simd<T, N> {
    fn clone(&self) -> Self {
        *self
    }
}

impl<T: core::fmt::Debug, const N: usize> core::fmt::Debug for Simd<T, N> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> Result<(), core::fmt::Error> {
        <[T; N] as core::fmt::Debug>::fmt(self.as_array(), f)
    }
}

impl<T, const N: usize> Simd<T, N> {
    pub const fn from_array(a: [T; N]) -> Self {
        Simd(a)
    }
    pub const fn as_array(&self) -> &[T; N] {
        let p: *const Self = self;
        unsafe { &*p.cast::<[T; N]>() }
    }
    pub const fn into_array(self) -> [T; N]
    where
        T: Copy,
    {
        *self.as_array()
    }
    pub const fn splat(a: T) -> Self
    where
        T: Copy,
    {
        Self([a; N])
    }
}

pub type u8x2 = Simd<u8, 2>;
pub type u8x4 = Simd<u8, 4>;
pub type u8x8 = Simd<u8, 8>;
pub type u8x16 = Simd<u8, 16>;
pub type u8x32 = Simd<u8, 32>;
pub type u8x64 = Simd<u8, 64>;

pub type u16x2 = Simd<u16, 2>;
pub type u16x4 = Simd<u16, 4>;
pub type u16x8 = Simd<u16, 8>;
pub type u16x16 = Simd<u16, 16>;
pub type u16x32 = Simd<u16, 32>;

pub type u32x2 = Simd<u32, 2>;
pub type u32x4 = Simd<u32, 4>;
pub type u32x8 = Simd<u32, 8>;
pub type u32x16 = Simd<u32, 16>;

pub type u64x2 = Simd<u64, 2>;
pub type u64x4 = Simd<u64, 4>;
pub type u64x8 = Simd<u64, 8>;

pub type u128x2 = Simd<u128, 2>;
pub type u128x4 = Simd<u128, 4>;

pub type i8x2 = Simd<i8, 2>;
pub type i8x4 = Simd<i8, 4>;
pub type i8x8 = Simd<i8, 8>;
pub type i8x16 = Simd<i8, 16>;
pub type i8x32 = Simd<i8, 32>;
pub type i8x64 = Simd<i8, 64>;

pub type i16x2 = Simd<i16, 2>;
pub type i16x4 = Simd<i16, 4>;
pub type i16x8 = Simd<i16, 8>;
pub type i16x16 = Simd<i16, 16>;
pub type i16x32 = Simd<i16, 32>;

pub type i32x2 = Simd<i32, 2>;
pub type i32x4 = Simd<i32, 4>;
pub type i32x8 = Simd<i32, 8>;
pub type i32x16 = Simd<i32, 16>;

pub type i64x2 = Simd<i64, 2>;
pub type i64x4 = Simd<i64, 4>;
pub type i64x8 = Simd<i64, 8>;

pub type i128x2 = Simd<i128, 2>;
pub type i128x4 = Simd<i128, 4>;

pub type usizex2 = Simd<usize, 2>;
pub type usizex4 = Simd<usize, 4>;
pub type usizex8 = Simd<usize, 8>;

pub type isizex2 = Simd<isize, 2>;
pub type isizex4 = Simd<isize, 4>;
pub type isizex8 = Simd<isize, 8>;

pub type f32x2 = Simd<f32, 2>;
pub type f32x4 = Simd<f32, 4>;
pub type f32x8 = Simd<f32, 8>;
pub type f32x16 = Simd<f32, 16>;

pub type f64x2 = Simd<f64, 2>;
pub type f64x4 = Simd<f64, 4>;
pub type f64x8 = Simd<f64, 8>;

// The field is currently left `pub` for convenience in porting tests, many of
// which attempt to just construct it directly. That still works; it's just the
// `.0` projection that doesn't.
#[repr(simd, packed)]
#[derive(Copy, Eq)]
pub struct PackedSimd<T, const N: usize>(pub [T; N]);

impl<T: Copy, const N: usize> Clone for PackedSimd<T, N> {
    fn clone(&self) -> Self {
        *self
    }
}

impl<T: core::fmt::Debug, const N: usize> core::fmt::Debug for PackedSimd<T, N> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> Result<(), core::fmt::Error> {
        <[T; N] as core::fmt::Debug>::fmt(self.as_array(), f)
    }
}

impl<T, const N: usize> PackedSimd<T, N> {
    pub const fn from_array(a: [T; N]) -> Self {
        PackedSimd(a)
    }
    pub const fn as_array(&self) -> &[T; N] {
        let p: *const Self = self;
        unsafe { &*p.cast::<[T; N]>() }
    }
    pub const fn into_array(self) -> [T; N]
    where
        T: Copy,
    {
        *self.as_array()
    }
    pub const fn splat(a: T) -> Self
    where
        T: Copy,
    {
        Self([a; N])
    }
}

// As `const_trait_impl` is a language feature with specialized syntax, we have to use them in a way
// such that it doesn't get parsed as Rust code unless `cfg(minisimd_const)` is on. The easiest way
// for that is a macro

macro_rules! impl_traits {
    ($($const_:ident)?) => {
        impl<T: $([$const_])? PartialEq, const N: usize> $($const_)? PartialEq for Simd<T, N> {
            fn eq(&self, other: &Self) -> bool {
                self.as_array() == other.as_array()
            }
        }

        impl<T, const N: usize> $($const_)? core::ops::Index<usize> for Simd<T, N> {
            type Output = T;
            fn index(&self, i: usize) -> &T {
                &self.as_array()[i]
            }
        }

        impl<T: $([$const_])? PartialEq, const N: usize> $($const_)? PartialEq for PackedSimd<T, N>
        {
            fn eq(&self, other: &Self) -> bool {
                self.as_array() == other.as_array()
            }
        }
    };
}

#[cfg(minisimd_const)]
impl_traits!(const);

#[cfg(not(minisimd_const))]
impl_traits!();

/// Version of `assert_eq` that ignores fancy runtime printing in const context.
/// FIXME: Remove once <https://github.com/rust-lang/rust/issues/119826> is fixed.
#[cfg(minisimd_const)]
#[macro_export]
macro_rules! assert_eq {
    ($left:expr, $right:expr $(,)?) => {
        assert_eq!(
            $left,
            $right,
            concat!("`", stringify!($left), "` == `", stringify!($right), "`")
        );
    };
    ($left:expr, $right:expr$(, $($arg:tt)+)?) => {
        {
            let left = $left;
            let right = $right;
            // type inference works better with the concrete type on the
            // left, but humans work better with the expected on the
            // right
            assert!(right == left, $($($arg)*),*);
        }
    };
}

#[cfg(minisimd_const)]
use assert_eq;