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Introduce trait-driven arithmetic #191

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6b93a89
Introduce trait-driven arithmetic
workingjubilee Nov 14, 2021
4c99aa4
Collapse reductions in docs using traits
workingjubilee Nov 17, 2021
b5687de
Add #[must_use] annotations
workingjubilee Nov 17, 2021
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307 changes: 154 additions & 153 deletions crates/core_simd/src/math.rs
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Original file line number Diff line number Diff line change
@@ -1,159 +1,160 @@
use crate::simd::intrinsics::{simd_saturating_add, simd_saturating_sub};
use crate::simd::{LaneCount, Simd, SupportedLaneCount};

macro_rules! impl_uint_arith {
($($ty:ty),+) => {
$( impl<const LANES: usize> Simd<$ty, LANES> where LaneCount<LANES>: SupportedLaneCount {

/// Lanewise saturating add.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
#[doc = concat!("# use core::", stringify!($ty), "::MAX;")]
/// let x = Simd::from_array([2, 1, 0, MAX]);
/// let max = Simd::splat(MAX);
/// let unsat = x + max;
/// let sat = x.saturating_add(max);
/// assert_eq!(x - 1, unsat);
/// assert_eq!(sat, max);
/// ```
#[inline]
pub fn saturating_add(self, second: Self) -> Self {
unsafe { simd_saturating_add(self, second) }
}

/// Lanewise saturating subtract.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
#[doc = concat!("# use core::", stringify!($ty), "::MAX;")]
/// let x = Simd::from_array([2, 1, 0, MAX]);
/// let max = Simd::splat(MAX);
/// let unsat = x - max;
/// let sat = x.saturating_sub(max);
/// assert_eq!(unsat, x + 1);
/// assert_eq!(sat, Simd::splat(0));
#[inline]
pub fn saturating_sub(self, second: Self) -> Self {
unsafe { simd_saturating_sub(self, second) }
}
})+
use crate::simd::intrinsics;
use crate::simd::{LaneCount, Simd, SimdElement, SupportedLaneCount};

mod sealed {
pub trait Sealed {}
}
use sealed::Sealed;
impl<T, const LANES: usize> Sealed for Simd<T, LANES>
where
T: SimdElement,
LaneCount<LANES>: SupportedLaneCount,
{
}

impl<T, const LANES: usize> Simd<T, LANES>
where
T: Int,
LaneCount<LANES>: SupportedLaneCount,
{
/// Lanewise saturating add.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
/// let x = Simd::from_array([i32::MIN, 0, 1, i32::MAX]);
/// let max = Simd::splat(i32::MAX);
/// let unsat = x + max;
/// let sat = x.saturating_add(max);
/// assert_eq!(unsat, Simd::from_array([-1, i32::MAX, i32::MIN, -2]));
/// assert_eq!(sat, Simd::from_array([-1, i32::MAX, i32::MAX, i32::MAX]));
/// ```
#[inline]
#[must_use = "method returns a new vector and does not mutate the original value"]
pub fn saturating_add(self, other: Self) -> Self {
unsafe { intrinsics::simd_saturating_add(self, other) }
}

/// Lanewise saturating subtract.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
/// let x = Simd::from_array([i32::MIN, -2, -1, i32::MAX]);
/// let max = Simd::splat(i32::MAX);
/// let unsat = x - max;
/// let sat = x.saturating_sub(max);
/// assert_eq!(unsat, Simd::from_array([1, i32::MAX, i32::MIN, 0]));
/// assert_eq!(sat, Simd::from_array([i32::MIN, i32::MIN, i32::MIN, 0]));
#[inline]
#[must_use = "method returns a new vector and does not mutate the original value"]
pub fn saturating_sub(self, other: Self) -> Self {
unsafe { intrinsics::simd_saturating_sub(self, other) }
}
}

pub trait Int: SimdElement + PartialOrd {
const BITS: u32;
}

impl Int for u8 {
const BITS: u32 = 8;
}

impl Int for i8 {
const BITS: u32 = 8;
}

impl Int for u16 {
const BITS: u32 = 16;
}

impl Int for i16 {
const BITS: u32 = 16;
}

impl Int for u32 {
const BITS: u32 = 32;
}

impl Int for i32 {
const BITS: u32 = 32;
}

impl Int for u64 {
const BITS: u32 = 64;
}

impl Int for i64 {
const BITS: u32 = 64;
}

impl Int for usize {
const BITS: u32 = usize::BITS;
}

macro_rules! impl_int_arith {
($($ty:ty),+) => {
$( impl<const LANES: usize> Simd<$ty, LANES> where LaneCount<LANES>: SupportedLaneCount {

/// Lanewise saturating add.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
#[doc = concat!("# use core::", stringify!($ty), "::{MIN, MAX};")]
/// let x = Simd::from_array([MIN, 0, 1, MAX]);
/// let max = Simd::splat(MAX);
/// let unsat = x + max;
/// let sat = x.saturating_add(max);
/// assert_eq!(unsat, Simd::from_array([-1, MAX, MIN, -2]));
/// assert_eq!(sat, Simd::from_array([-1, MAX, MAX, MAX]));
/// ```
#[inline]
pub fn saturating_add(self, second: Self) -> Self {
unsafe { simd_saturating_add(self, second) }
}

/// Lanewise saturating subtract.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
#[doc = concat!("# use core::", stringify!($ty), "::{MIN, MAX};")]
/// let x = Simd::from_array([MIN, -2, -1, MAX]);
/// let max = Simd::splat(MAX);
/// let unsat = x - max;
/// let sat = x.saturating_sub(max);
/// assert_eq!(unsat, Simd::from_array([1, MAX, MIN, 0]));
/// assert_eq!(sat, Simd::from_array([MIN, MIN, MIN, 0]));
#[inline]
pub fn saturating_sub(self, second: Self) -> Self {
unsafe { simd_saturating_sub(self, second) }
}

/// Lanewise absolute value, implemented in Rust.
/// Every lane becomes its absolute value.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
#[doc = concat!("# use core::", stringify!($ty), "::{MIN, MAX};")]
/// let xs = Simd::from_array([MIN, MIN +1, -5, 0]);
/// assert_eq!(xs.abs(), Simd::from_array([MIN, MAX, 5, 0]));
/// ```
#[inline]
pub fn abs(self) -> Self {
const SHR: $ty = <$ty>::BITS as $ty - 1;
let m = self >> SHR;
(self^m) - m
}

/// Lanewise saturating absolute value, implemented in Rust.
/// As abs(), except the MIN value becomes MAX instead of itself.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
#[doc = concat!("# use core::", stringify!($ty), "::{MIN, MAX};")]
/// let xs = Simd::from_array([MIN, -2, 0, 3]);
/// let unsat = xs.abs();
/// let sat = xs.saturating_abs();
/// assert_eq!(unsat, Simd::from_array([MIN, 2, 0, 3]));
/// assert_eq!(sat, Simd::from_array([MAX, 2, 0, 3]));
/// ```
#[inline]
pub fn saturating_abs(self) -> Self {
// arith shift for -1 or 0 mask based on sign bit, giving 2s complement
const SHR: $ty = <$ty>::BITS as $ty - 1;
let m = self >> SHR;
(self^m).saturating_sub(m)
}

/// Lanewise saturating negation, implemented in Rust.
/// As neg(), except the MIN value becomes MAX instead of itself.
///
/// # Examples
/// ```
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
#[doc = concat!("# use core::", stringify!($ty), "::{MIN, MAX};")]
/// let x = Simd::from_array([MIN, -2, 3, MAX]);
/// let unsat = -x;
/// let sat = x.saturating_neg();
/// assert_eq!(unsat, Simd::from_array([MIN, 2, -3, MIN + 1]));
/// assert_eq!(sat, Simd::from_array([MAX, 2, -3, MIN + 1]));
/// ```
#[inline]
pub fn saturating_neg(self) -> Self {
Self::splat(0).saturating_sub(self)
}
})+
impl Int for isize {
const BITS: u32 = isize::BITS;
}

pub trait SimdSignum: Sealed {
fn signum(self) -> Self;
}

impl<T, const LANES: usize> Simd<T, LANES>
where
Self: SimdSignum,
T: SimdElement,
LaneCount<LANES>: SupportedLaneCount,
{
/// Replaces each lane with a number that represents its sign.
///
/// For floats:
/// * `1.0` if the number is positive, `+0.0`, or `INFINITY`
/// * `-1.0` if the number is negative, `-0.0`, or `NEG_INFINITY`
/// * `NAN` if the number is `NAN`
///
/// For signed integers:
/// * `0` if the number is zero
/// * `1` if the number is positive
/// * `-1` if the number is negative
#[inline]
#[must_use = "method returns a new vector and does not mutate the original value"]
pub fn signum(self) -> Self {
<Self as SimdSignum>::signum(self)
}
}

impl_uint_arith! { u8, u16, u32, u64, usize }
impl_int_arith! { i8, i16, i32, i64, isize }
pub trait SimdAbs: Sealed {
/// Returns a vector where every lane has the absolute value of the
/// equivalent index in `self`.
fn abs(self) -> Self;
}

impl<T, const LANES: usize> Simd<T, LANES>
where
Self: SimdAbs,
T: SimdElement,
LaneCount<LANES>: SupportedLaneCount,
{
/// Returns a vector where every lane has the absolute value of the
/// equivalent index in `self`.
///
/// # Examples
/// ```rust
/// # #![feature(portable_simd)]
/// # #[cfg(feature = "std")] use core_simd::Simd;
/// # #[cfg(not(feature = "std"))] use core::simd::Simd;
/// let xs = Simd::from_array([i32::MIN, i32::MIN +1, -5, 0]);
/// assert_eq!(xs.abs(), Simd::from_array([i32::MIN, i32::MAX, 5, 0]));
/// ```
#[inline]
#[must_use = "method returns a new vector and does not mutate the original value"]
pub fn abs(self) -> Self {
<Self as SimdAbs>::abs(self)
}
}
3 changes: 2 additions & 1 deletion crates/core_simd/src/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ mod reduction;
mod swizzle;

pub(crate) mod intrinsics;
pub(crate) mod math;

#[cfg(feature = "generic_const_exprs")]
mod to_bytes;
Expand All @@ -14,7 +15,6 @@ mod fmt;
mod iter;
mod lane_count;
mod masks;
mod math;
mod ops;
mod round;
mod select;
Expand All @@ -24,6 +24,7 @@ mod vendor;
#[doc = include_str!("core_simd_docs.md")]
pub mod simd {
pub(crate) use crate::core_simd::intrinsics;
pub(crate) use crate::core_simd::math::*;

pub use crate::core_simd::lane_count::{LaneCount, SupportedLaneCount};
pub use crate::core_simd::masks::*;
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