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Change bitmasks to use less opaque type

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This commit is contained in:
Caleb Zulawski 2021-07-29 04:55:28 +00:00
parent 9ab050796f
commit cca9102429
4 changed files with 19 additions and 12 deletions
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7
crates/core_simd/src/lane_count.rs
View File

@ -6,9 +6,14 @@ pub trait Sealed {}
/// A type representing a vector lane count.
pub struct LaneCount<const LANES: usize>;
impl<const LANES: usize> LaneCount<LANES> {
/// The number of bytes in a bitmask with this many lanes.
pub const BITMASK_LEN: usize = (LANES + 7) / 8;
}
/// Helper trait for vector lane counts.
pub trait SupportedLaneCount: Sealed {
/// The bitmask representation of a mask.
#[doc(hidden)]
type BitMask: Copy + Default + AsRef<[u8]> + AsMut<[u8]>;
#[doc(hidden)]

4
crates/core_simd/src/masks.rs
View File

@ -160,12 +160,12 @@ pub fn set(&mut self, lane: usize, value: bool) {
}
/// Convert this mask to a bitmask, with one bit set per lane.
pub fn to_bitmask(self) -> <crate::LaneCount<LANES> as crate::SupportedLaneCount>::BitMask {
pub fn to_bitmask(self) -> [u8; crate::LaneCount::<LANES>::BITMASK_LEN] {
self.0.to_bitmask()
}
/// Convert a bitmask to a mask.
pub fn from_bitmask(bitmask: <crate::LaneCount<LANES> as crate::SupportedLaneCount>::BitMask) -> Self {
pub fn from_bitmask(bitmask: [u8; crate::LaneCount::<LANES>::BITMASK_LEN]) -> Self {
Self(<$inner_ty>::from_bitmask(bitmask))
}
}

10
crates/core_simd/src/masks/bitmask.rs
View File

@ -128,13 +128,15 @@ pub unsafe fn from_int_unchecked<V>(value: V) -> Self
}
#[inline]
pub fn to_bitmask(self) -> <LaneCount<LANES> as SupportedLaneCount>::BitMask {
self.0
pub fn to_bitmask(self) -> [u8; LaneCount::<LANES>::BITMASK_LEN] {
// Safety: these are the same type and we are laundering the generic
unsafe { core::mem::transmute_copy(&self.0) }
}
#[inline]
pub fn from_bitmask(bitmask: <LaneCount<LANES> as SupportedLaneCount>::BitMask) -> Self {
Self(bitmask)
pub fn from_bitmask(bitmask: [u8; LaneCount::<LANES>::BITMASK_LEN]) -> Self {
// Safety: these are the same type and we are laundering the generic
Self(unsafe { core::mem::transmute_copy(&bitmask) })
}
#[inline]

10
crates/core_simd/src/masks/full_masks.rs
View File

@ -103,15 +103,15 @@ pub unsafe fn from_int_unchecked(value: crate::$type<LANES>) -> Self {
}
#[inline]
pub fn to_bitmask(self) -> <crate::LaneCount::<LANES> as crate::SupportedLaneCount>::BitMask {
pub fn to_bitmask(self) -> [u8; crate::LaneCount::<LANES>::BITMASK_LEN] {
unsafe {
// TODO remove the transmute when rustc can use arrays of u8 as bitmasks
assert_eq!(
core::mem::size_of::<<crate::LaneCount::<LANES> as crate::SupportedLaneCount>::BitMask>(),
core::mem::size_of::<<crate::LaneCount::<LANES> as crate::SupportedLaneCount>::IntBitMask>(),
crate::LaneCount::<LANES>::BITMASK_LEN,
);
let bitmask: <crate::LaneCount::<LANES> as crate::SupportedLaneCount>::IntBitMask = crate::intrinsics::simd_bitmask(self.0);
let mut bitmask: <crate::LaneCount::<LANES> as crate::SupportedLaneCount>::BitMask = core::mem::transmute_copy(&bitmask);
let mut bitmask: [u8; crate::LaneCount::<LANES>::BITMASK_LEN] = core::mem::transmute_copy(&bitmask);
// There is a bug where LLVM appears to implement this operation with the wrong
// bit order.
@ -127,7 +127,7 @@ pub fn to_bitmask(self) -> <crate::LaneCount::<LANES> as crate::SupportedLaneCou
}
#[inline]
pub fn from_bitmask(mut bitmask: <crate::LaneCount::<LANES> as crate::SupportedLaneCount>::BitMask) -> Self {
pub fn from_bitmask(mut bitmask: [u8; crate::LaneCount::<LANES>::BITMASK_LEN]) -> Self {
unsafe {
// There is a bug where LLVM appears to implement this operation with the wrong
// bit order.
@ -140,8 +140,8 @@ pub fn from_bitmask(mut bitmask: <crate::LaneCount::<LANES> as crate::SupportedL
// TODO remove the transmute when rustc can use arrays of u8 as bitmasks
assert_eq!(
core::mem::size_of::<<crate::LaneCount::<LANES> as crate::SupportedLaneCount>::BitMask>(),
core::mem::size_of::<<crate::LaneCount::<LANES> as crate::SupportedLaneCount>::IntBitMask>(),
crate::LaneCount::<LANES>::BITMASK_LEN,
);
let bitmask: <crate::LaneCount::<LANES> as crate::SupportedLaneCount>::IntBitMask = core::mem::transmute_copy(&bitmask);