mirror of
https://github.com/Lokathor/bytemuck.git
synced 2024-11-21 22:32:23 +00:00
9b81537c5f
These are gated under a new feature flag `nightly_float`. Fixes: <https://github.com/Lokathor/bytemuck/issues/250>
170 lines
6.3 KiB
Rust
170 lines
6.3 KiB
Rust
use super::*;
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/// Marker trait for "plain old data".
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///
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/// The point of this trait is that once something is marked "plain old data"
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/// you can really go to town with the bit fiddling and bit casting. Therefore,
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/// it's a relatively strong claim to make about a type. Do not add this to your
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/// type casually.
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///
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/// **Reminder:** The results of casting around bytes between data types are
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/// _endian dependant_. Little-endian machines are the most common, but
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/// big-endian machines do exist (and big-endian is also used for "network
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/// order" bytes).
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///
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/// ## Safety
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///
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/// * The type must be inhabited (eg: no
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/// [Infallible](core::convert::Infallible)).
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/// * The type must allow any bit pattern (eg: no `bool` or `char`, which have
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/// illegal bit patterns).
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/// * The type must not contain any uninit (or padding) bytes, either in the
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/// middle or on the end (eg: no `#[repr(C)] struct Foo(u8, u16)`, which has
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/// padding in the middle, and also no `#[repr(C)] struct Foo(u16, u8)`, which
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/// has padding on the end).
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/// * The type needs to have all fields also be `Pod`.
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/// * The type needs to be `repr(C)` or `repr(transparent)`. In the case of
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/// `repr(C)`, the `packed` and `align` repr modifiers can be used as long as
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/// all other rules end up being followed.
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/// * It is disallowed for types to contain pointer types, `Cell`, `UnsafeCell`,
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/// atomics, and any other forms of interior mutability.
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/// * More precisely: A shared reference to the type must allow reads, and
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/// *only* reads. RustBelt's separation logic is based on the notion that a
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/// type is allowed to define a sharing predicate, its own invariant that must
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/// hold for shared references, and this predicate is the reasoning that allow
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/// it to deal with atomic and cells etc. We require the sharing predicate to
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/// be trivial and permit only read-only access.
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pub unsafe trait Pod: Zeroable + Copy + 'static {}
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unsafe impl Pod for () {}
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unsafe impl Pod for u8 {}
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unsafe impl Pod for i8 {}
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unsafe impl Pod for u16 {}
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unsafe impl Pod for i16 {}
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unsafe impl Pod for u32 {}
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unsafe impl Pod for i32 {}
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unsafe impl Pod for u64 {}
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unsafe impl Pod for i64 {}
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unsafe impl Pod for usize {}
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unsafe impl Pod for isize {}
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unsafe impl Pod for u128 {}
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unsafe impl Pod for i128 {}
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#[cfg(feature = "nightly_float")]
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unsafe impl Pod for f16 {}
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unsafe impl Pod for f32 {}
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unsafe impl Pod for f64 {}
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#[cfg(feature = "nightly_float")]
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unsafe impl Pod for f128 {}
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unsafe impl<T: Pod> Pod for Wrapping<T> {}
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#[cfg(feature = "unsound_ptr_pod_impl")]
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#[cfg_attr(
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feature = "nightly_docs",
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doc(cfg(feature = "unsound_ptr_pod_impl"))
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)]
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unsafe impl<T: 'static> Pod for *mut T {}
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#[cfg(feature = "unsound_ptr_pod_impl")]
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#[cfg_attr(
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feature = "nightly_docs",
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doc(cfg(feature = "unsound_ptr_pod_impl"))
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)]
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unsafe impl<T: 'static> Pod for *const T {}
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#[cfg(feature = "unsound_ptr_pod_impl")]
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#[cfg_attr(
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feature = "nightly_docs",
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doc(cfg(feature = "unsound_ptr_pod_impl"))
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)]
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unsafe impl<T: 'static> PodInOption for NonNull<T> {}
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unsafe impl<T: ?Sized + 'static> Pod for PhantomData<T> {}
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unsafe impl Pod for PhantomPinned {}
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unsafe impl<T: Pod> Pod for core::mem::ManuallyDrop<T> {}
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// Note(Lokathor): MaybeUninit can NEVER be Pod.
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#[cfg(feature = "min_const_generics")]
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#[cfg_attr(feature = "nightly_docs", doc(cfg(feature = "min_const_generics")))]
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unsafe impl<T, const N: usize> Pod for [T; N] where T: Pod {}
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#[cfg(not(feature = "min_const_generics"))]
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impl_unsafe_marker_for_array!(
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Pod, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
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20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 48, 64, 96, 128, 256,
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512, 1024, 2048, 4096
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);
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impl_unsafe_marker_for_simd!(
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#[cfg(all(target_arch = "wasm32", feature = "wasm_simd"))]
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unsafe impl Pod for wasm32::{v128}
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);
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impl_unsafe_marker_for_simd!(
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#[cfg(all(target_arch = "aarch64", feature = "aarch64_simd"))]
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unsafe impl Pod for aarch64::{
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float32x2_t, float32x2x2_t, float32x2x3_t, float32x2x4_t, float32x4_t,
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float32x4x2_t, float32x4x3_t, float32x4x4_t, float64x1_t, float64x1x2_t,
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float64x1x3_t, float64x1x4_t, float64x2_t, float64x2x2_t, float64x2x3_t,
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float64x2x4_t, int16x4_t, int16x4x2_t, int16x4x3_t, int16x4x4_t, int16x8_t,
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int16x8x2_t, int16x8x3_t, int16x8x4_t, int32x2_t, int32x2x2_t, int32x2x3_t,
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int32x2x4_t, int32x4_t, int32x4x2_t, int32x4x3_t, int32x4x4_t, int64x1_t,
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int64x1x2_t, int64x1x3_t, int64x1x4_t, int64x2_t, int64x2x2_t, int64x2x3_t,
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int64x2x4_t, int8x16_t, int8x16x2_t, int8x16x3_t, int8x16x4_t, int8x8_t,
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int8x8x2_t, int8x8x3_t, int8x8x4_t, poly16x4_t, poly16x4x2_t, poly16x4x3_t,
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poly16x4x4_t, poly16x8_t, poly16x8x2_t, poly16x8x3_t, poly16x8x4_t,
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poly64x1_t, poly64x1x2_t, poly64x1x3_t, poly64x1x4_t, poly64x2_t,
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poly64x2x2_t, poly64x2x3_t, poly64x2x4_t, poly8x16_t, poly8x16x2_t,
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poly8x16x3_t, poly8x16x4_t, poly8x8_t, poly8x8x2_t, poly8x8x3_t, poly8x8x4_t,
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uint16x4_t, uint16x4x2_t, uint16x4x3_t, uint16x4x4_t, uint16x8_t,
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uint16x8x2_t, uint16x8x3_t, uint16x8x4_t, uint32x2_t, uint32x2x2_t,
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uint32x2x3_t, uint32x2x4_t, uint32x4_t, uint32x4x2_t, uint32x4x3_t,
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uint32x4x4_t, uint64x1_t, uint64x1x2_t, uint64x1x3_t, uint64x1x4_t,
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uint64x2_t, uint64x2x2_t, uint64x2x3_t, uint64x2x4_t, uint8x16_t,
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uint8x16x2_t, uint8x16x3_t, uint8x16x4_t, uint8x8_t, uint8x8x2_t,
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uint8x8x3_t, uint8x8x4_t,
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}
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);
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impl_unsafe_marker_for_simd!(
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#[cfg(target_arch = "x86")]
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unsafe impl Pod for x86::{
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__m128i, __m128, __m128d,
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__m256i, __m256, __m256d,
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}
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);
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impl_unsafe_marker_for_simd!(
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#[cfg(target_arch = "x86_64")]
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unsafe impl Pod for x86_64::{
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__m128i, __m128, __m128d,
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__m256i, __m256, __m256d,
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}
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);
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#[cfg(feature = "nightly_portable_simd")]
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#[cfg_attr(
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feature = "nightly_docs",
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doc(cfg(feature = "nightly_portable_simd"))
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)]
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unsafe impl<T, const N: usize> Pod for core::simd::Simd<T, N>
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where
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T: core::simd::SimdElement + Pod,
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core::simd::LaneCount<N>: core::simd::SupportedLaneCount,
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{
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}
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impl_unsafe_marker_for_simd!(
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#[cfg(all(target_arch = "x86", feature = "nightly_stdsimd"))]
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unsafe impl Pod for x86::{
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__m128bh, __m256bh, __m512,
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__m512bh, __m512d, __m512i,
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}
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);
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impl_unsafe_marker_for_simd!(
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#[cfg(all(target_arch = "x86_64", feature = "nightly_stdsimd"))]
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unsafe impl Pod for x86_64::{
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__m128bh, __m256bh, __m512,
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__m512bh, __m512d, __m512i,
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}
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);
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