diff options
Diffstat (limited to 'vendor/packed_simd_2/src/api/slice/from_slice.rs')
| -rw-r--r-- | vendor/packed_simd_2/src/api/slice/from_slice.rs | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/vendor/packed_simd_2/src/api/slice/from_slice.rs b/vendor/packed_simd_2/src/api/slice/from_slice.rs new file mode 100644 index 000000000..25082d1e6 --- /dev/null +++ b/vendor/packed_simd_2/src/api/slice/from_slice.rs @@ -0,0 +1,218 @@ +//! Implements methods to read a vector type from a slice. + +macro_rules! impl_slice_from_slice { + ([$elem_ty:ident; $elem_count:expr]: $id:ident | $test_tt:tt) => { + impl $id { + /// Instantiates a new vector with the values of the `slice`. + /// + /// # Panics + /// + /// If `slice.len() < Self::lanes()` or `&slice[0]` is not aligned + /// to an `align_of::<Self>()` boundary. + #[inline] + pub fn from_slice_aligned(slice: &[$elem_ty]) -> Self { + unsafe { + assert!(slice.len() >= $elem_count); + let target_ptr = slice.get_unchecked(0) as *const $elem_ty; + assert_eq!( + target_ptr + .align_offset(crate::mem::align_of::<Self>()), + 0 + ); + Self::from_slice_aligned_unchecked(slice) + } + } + + /// Instantiates a new vector with the values of the `slice`. + /// + /// # Panics + /// + /// If `slice.len() < Self::lanes()`. + #[inline] + pub fn from_slice_unaligned(slice: &[$elem_ty]) -> Self { + unsafe { + assert!(slice.len() >= $elem_count); + Self::from_slice_unaligned_unchecked(slice) + } + } + + /// Instantiates a new vector with the values of the `slice`. + /// + /// # Safety + /// + /// If `slice.len() < Self::lanes()` or `&slice[0]` is not aligned + /// to an `align_of::<Self>()` boundary, the behavior is undefined. + #[inline] + pub unsafe fn from_slice_aligned_unchecked( + slice: &[$elem_ty], + ) -> Self { + debug_assert!(slice.len() >= $elem_count); + let target_ptr = slice.get_unchecked(0) as *const $elem_ty; + debug_assert_eq!( + target_ptr.align_offset(crate::mem::align_of::<Self>()), + 0 + ); + + #[allow(clippy::cast_ptr_alignment)] + *(target_ptr as *const Self) + } + + /// Instantiates a new vector with the values of the `slice`. + /// + /// # Safety + /// + /// If `slice.len() < Self::lanes()` the behavior is undefined. + #[inline] + pub unsafe fn from_slice_unaligned_unchecked( + slice: &[$elem_ty], + ) -> Self { + use crate::mem::size_of; + debug_assert!(slice.len() >= $elem_count); + let target_ptr = + slice.get_unchecked(0) as *const $elem_ty as *const u8; + let mut x = Self::splat(0 as $elem_ty); + let self_ptr = &mut x as *mut Self as *mut u8; + crate::ptr::copy_nonoverlapping( + target_ptr, + self_ptr, + size_of::<Self>(), + ); + x + } + } + + test_if! { + $test_tt: + paste::item! { + // Comparisons use integer casts within mantissa^1 range. + #[allow(clippy::float_cmp)] + pub mod [<$id _slice_from_slice>] { + use super::*; + use crate::iter::Iterator; + + #[cfg_attr(not(target_arch = "wasm32"), test)] + #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)] + fn from_slice_unaligned() { + let mut unaligned = [42 as $elem_ty; $id::lanes() + 1]; + unaligned[0] = 0 as $elem_ty; + let vec = $id::from_slice_unaligned(&unaligned[1..]); + for (index, &b) in unaligned.iter().enumerate() { + if index == 0 { + assert_eq!(b, 0 as $elem_ty); + } else { + assert_eq!(b, 42 as $elem_ty); + assert_eq!(b, vec.extract(index - 1)); + } + } + } + + // FIXME: wasm-bindgen-test does not support #[should_panic] + // #[cfg_attr(not(target_arch = "wasm32"), test)] + // #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)] + #[cfg(not(target_arch = "wasm32"))] + #[test] + #[should_panic] + fn from_slice_unaligned_fail() { + let mut unaligned = [42 as $elem_ty; $id::lanes() + 1]; + unaligned[0] = 0 as $elem_ty; + // the slice is not large enough => panic + let _vec = $id::from_slice_unaligned(&unaligned[2..]); + } + + union A { + data: [$elem_ty; 2 * $id::lanes()], + _vec: $id, + } + + #[cfg_attr(not(target_arch = "wasm32"), test)] + #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)] + fn from_slice_aligned() { + let mut aligned = A { + data: [0 as $elem_ty; 2 * $id::lanes()], + }; + for i in $id::lanes()..(2 * $id::lanes()) { + unsafe { + aligned.data[i] = 42 as $elem_ty; + } + } + + let vec = unsafe { + $id::from_slice_aligned( + &aligned.data[$id::lanes()..] + ) + }; + for (index, &b) in + unsafe { aligned.data.iter().enumerate() } { + if index < $id::lanes() { + assert_eq!(b, 0 as $elem_ty); + } else { + assert_eq!(b, 42 as $elem_ty); + assert_eq!( + b, vec.extract(index - $id::lanes()) + ); + } + } + } + + // FIXME: wasm-bindgen-test does not support #[should_panic] + // #[cfg_attr(not(target_arch = "wasm32"), test)] + // #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)] + #[cfg(not(target_arch = "wasm32"))] + #[test] + #[should_panic] + fn from_slice_aligned_fail_lanes() { + let aligned = A { + data: [0 as $elem_ty; 2 * $id::lanes()], + }; + let _vec = unsafe { + $id::from_slice_aligned( + &aligned.data[2 * $id::lanes()..] + ) + }; + } + + // FIXME: wasm-bindgen-test does not support #[should_panic] + // #[cfg_attr(not(target_arch = "wasm32"), test)] + // #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)] + #[cfg(not(target_arch = "wasm32"))] + #[test] + #[should_panic] + fn from_slice_aligned_fail_align() { + unsafe { + let aligned = A { + data: [0 as $elem_ty; 2 * $id::lanes()], + }; + + // get a pointer to the front of data + let ptr: *const $elem_ty = aligned.data.as_ptr() + as *const $elem_ty; + // offset pointer by one element + let ptr = ptr.wrapping_add(1); + + if ptr.align_offset( + crate::mem::align_of::<$id>() + ) == 0 { + // the pointer is properly aligned, so + // from_slice_aligned won't fail here (e.g. this + // can happen for i128x1). So we panic to make + // the "should_fail" test pass: + panic!("ok"); + } + + // create a slice - this is safe, because the + // elements of the slice exist, are properly + // initialized, and properly aligned: + let s: &[$elem_ty] = slice::from_raw_parts( + ptr, $id::lanes() + ); + // this should always panic because the slice + // alignment does not match the alignment + // requirements for the vector type: + let _vec = $id::from_slice_aligned(s); + } + } + } + } + } + }; +} |