Use new bitmask intrinsics with byte arrays

Author: calebzulawski

crates/core_simd/src/lane_count.rs

@@ -15,34 +15,25 @@ impl<const LANES: usize> LaneCount<LANES> {
 pub trait SupportedLaneCount: Sealed {
     #[doc(hidden)]
     type BitMask: Copy + Default + AsRef<[u8]> + AsMut<[u8]>;
-
-    #[doc(hidden)]
-    type IntBitMask;
 }
 
 impl<const LANES: usize> Sealed for LaneCount<LANES> {}
 
 impl SupportedLaneCount for LaneCount<1> {
     type BitMask = [u8; 1];
-    type IntBitMask = u8;
 }
 impl SupportedLaneCount for LaneCount<2> {
     type BitMask = [u8; 1];
-    type IntBitMask = u8;
 }
 impl SupportedLaneCount for LaneCount<4> {
     type BitMask = [u8; 1];
-    type IntBitMask = u8;
 }
 impl SupportedLaneCount for LaneCount<8> {
     type BitMask = [u8; 1];
-    type IntBitMask = u8;
 }
 impl SupportedLaneCount for LaneCount<16> {
     type BitMask = [u8; 2];
-    type IntBitMask = u16;
 }
 impl SupportedLaneCount for LaneCount<32> {
     type BitMask = [u8; 4];
-    type IntBitMask = u32;
 }

crates/core_simd/src/masks/bitmask.rs

@@ -97,10 +97,8 @@ where
     #[inline]
     pub fn to_int(self) -> Simd<T, LANES> {
         unsafe {
-            let mask: <LaneCount<LANES> as SupportedLaneCount>::IntBitMask =
-                core::mem::transmute_copy(&self);
             crate::intrinsics::simd_select_bitmask(
-                mask,
+                self.0,
                 Simd::splat(T::TRUE),
                 Simd::splat(T::FALSE),
             )
@@ -109,14 +107,7 @@ where
 
     #[inline]
     pub unsafe fn from_int_unchecked(value: Simd<T, LANES>) -> Self {
-        // TODO remove the transmute when rustc is more flexible
-        assert_eq!(
-            core::mem::size_of::<<LaneCount::<LANES> as SupportedLaneCount>::BitMask>(),
-            core::mem::size_of::<<LaneCount::<LANES> as SupportedLaneCount>::IntBitMask>(),
-        );
-        let mask: <LaneCount<LANES> as SupportedLaneCount>::IntBitMask =
-            crate::intrinsics::simd_bitmask(value);
-        Self(core::mem::transmute_copy(&mask), PhantomData)
+        Self(crate::intrinsics::simd_bitmask(value), PhantomData)
     }
 
     #[cfg(feature = "generic_const_exprs")]

crates/core_simd/src/masks/full_masks.rs

@@ -105,15 +105,8 @@ where
     #[inline]
     pub fn to_bitmask(self) -> [u8; LaneCount::<LANES>::BITMASK_LEN] {
         unsafe {
-            // TODO remove the transmute when rustc can use arrays of u8 as bitmasks
-            assert_eq!(
-                core::mem::size_of::<<LaneCount::<LANES> as SupportedLaneCount>::IntBitMask>(),
-                LaneCount::<LANES>::BITMASK_LEN,
-            );
-            let bitmask: <LaneCount<LANES> as SupportedLaneCount>::IntBitMask =
-                crate::intrinsics::simd_bitmask(self.0);
             let mut bitmask: [u8; LaneCount::<LANES>::BITMASK_LEN] =
-                core::mem::transmute_copy(&bitmask);
+                crate::intrinsics::simd_bitmask(self.0);
 
             // There is a bug where LLVM appears to implement this operation with the wrong
             // bit order.
@@ -141,14 +134,6 @@ where
                 }
             }
 
-            // TODO remove the transmute when rustc can use arrays of u8 as bitmasks
-            assert_eq!(
-                core::mem::size_of::<<LaneCount::<LANES> as SupportedLaneCount>::IntBitMask>(),
-                LaneCount::<LANES>::BITMASK_LEN,
-            );
-            let bitmask: <LaneCount<LANES> as SupportedLaneCount>::IntBitMask =
-                core::mem::transmute_copy(&bitmask);
-
             Self::from_int_unchecked(crate::intrinsics::simd_select_bitmask(
                 bitmask,
                 Self::splat(true).to_int(),