bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Update comments per review feedback

Browse source
This commit is contained in:
Scott McMurray 2021-12-14 15:48:46 -08:00
parent 92c8317d2a
commit e4c44c5df7
1 changed files with 46 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

56
library/core/src/slice/mod.rs
View file

@ -3436,12 +3436,30 @@ impl<T> [T] {
}
}
/// Split a slice into a prefix, a middle of aligned simd types, and a suffix.
/// Split a slice into a prefix, a middle of aligned SIMD types, and a suffix.
///
/// This is a safe wrapper around [`slice::align_to`], so has the same weak
/// preconditions as that method. Notably, you must not assume any particular
/// split between the three parts: it's legal for the middle slice to be
/// empty even if the input slice is longer than `3 * LANES`.
/// postconditions as that method. You're only assured that
/// `self.len() == prefix.len() + middle.len() * LANES + suffix.len()`.
///
/// Notably, all of the following are possible:
/// - `prefix.len() >= LANES`.
/// - `middle.is_empty()` despite `self.len() >= 3 * LANES`.
/// - `suffix.len() >= LANES`.
///
/// That said, this is a safe method, so if you're only writing safe code,
/// then this can at most cause incorrect logic, not unsoundness.
///
/// # Panics
///
/// This will panic if the size of the SIMD type is different from
/// `LANES` times that of the scalar.
///
/// At the time of writing, the trait restrictions on `Simd<T, LANES>` keeps
/// that from ever happening, as only power-of-two numbers of lanes are
/// supported. It's possible that, in the future, those restrictions might
/// be lifted in a way that would make it possible to see panics from this
/// method for something like `LANES == 3`.
///
/// # Examples
///
@ -3491,14 +3509,32 @@ impl<T> [T] {
unsafe { self.align_to() }
}
/// Split a slice into a prefix, a middle of aligned simd types, and a suffix.
/// Split a slice into a prefix, a middle of aligned SIMD types, and a suffix.
///
/// This is a safe wrapper around [`slice::align_to`], so has the same weak
/// preconditions as that method. Notably, you must not assume any particular
/// split between the three parts: it's legal for the middle slice to be
/// empty even if the input slice is longer than `3 * LANES`.
/// This is a safe wrapper around [`slice::align_to_mut`], so has the same weak
/// postconditions as that method. You're only assured that
/// `self.len() == prefix.len() + middle.len() * LANES + suffix.len()`.
///
/// This is the mutable version of [`slice::as_simd`]; see that for more.
/// Notably, all of the following are possible:
/// - `prefix.len() >= LANES`.
/// - `middle.is_empty()` despite `self.len() >= 3 * LANES`.
/// - `suffix.len() >= LANES`.
///
/// That said, this is a safe method, so if you're only writing safe code,
/// then this can at most cause incorrect logic, not unsoundness.
///
/// This is the mutable version of [`slice::as_simd`]; see that for examples.
///
/// # Panics
///
/// This will panic if the size of the SIMD type is different from
/// `LANES` times that of the scalar.
///
/// At the time of writing, the trait restrictions on `Simd<T, LANES>` keeps
/// that from ever happening, as only power-of-two numbers of lanes are
/// supported. It's possible that, in the future, those restrictions might
/// be lifted in a way that would make it possible to see panics from this
/// method for something like `LANES == 3`.
#[unstable(feature = "portable_simd", issue = "86656")]
#[cfg(not(miri))] // Miri does not support all SIMD intrinsics
pub fn as_simd_mut<const LANES: usize>(&mut self) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T])