core/intrinsics/

simd.rs

//! SIMD compiler intrinsics.
//!
//! In this module, a "vector" is any `repr(simd)` type.

#[cfg(not(feature = "ferrocene_subset"))]
use crate::marker::ConstParamTy;

/// Inserts an element into a vector, returning the updated vector.
///
/// `T` must be a vector with element type `U`, and `idx` must be `const`.
///
/// # Safety
///
/// `idx` must be in-bounds of the vector.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_insert<T, U>(x: T, idx: u32, val: U) -> T;

/// Extracts an element from a vector.
///
/// `T` must be a vector with element type `U`, and `idx` must be `const`.
///
/// # Safety
///
/// `idx` must be const and in-bounds of the vector.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_extract<T, U>(x: T, idx: u32) -> U;

/// Inserts an element into a vector, returning the updated vector.
///
/// `T` must be a vector with element type `U`.
///
/// If the index is `const`, [`simd_insert`] may emit better assembly.
///
/// # Safety
///
/// `idx` must be in-bounds of the vector.
#[rustc_nounwind]
#[rustc_intrinsic]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_insert_dyn<T, U>(x: T, idx: u32, val: U) -> T;

/// Extracts an element from a vector.
///
/// `T` must be a vector with element type `U`.
///
/// If the index is `const`, [`simd_extract`] may emit better assembly.
///
/// # Safety
///
/// `idx` must be in-bounds of the vector.
#[rustc_nounwind]
#[rustc_intrinsic]
pub const unsafe fn simd_extract_dyn<T, U>(x: T, idx: u32) -> U;

/// Creates a vector where every lane has the provided value.
///
/// `T` must be a vector with element type `U`.
#[rustc_nounwind]
#[rustc_intrinsic]
pub const unsafe fn simd_splat<T, U>(value: U) -> T;

/// Adds two simd vectors elementwise.
///
/// `T` must be a vector of integers or floats.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_add<T>(x: T, y: T) -> T;

/// Subtracts `rhs` from `lhs` elementwise.
///
/// `T` must be a vector of integers or floats.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_sub<T>(lhs: T, rhs: T) -> T;

/// Multiplies two simd vectors elementwise.
///
/// `T` must be a vector of integers or floats.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_mul<T>(x: T, y: T) -> T;

/// Divides `lhs` by `rhs` elementwise.
///
/// `T` must be a vector of integers or floats.
///
/// # Safety
/// For integers, `rhs` must not contain any zero elements.
/// Additionally for signed integers, `<int>::MIN / -1` is undefined behavior.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_div<T>(lhs: T, rhs: T) -> T;

/// Returns remainder of two vectors elementwise.
///
/// `T` must be a vector of integers or floats.
///
/// # Safety
/// For integers, `rhs` must not contain any zero elements.
/// Additionally for signed integers, `<int>::MIN / -1` is undefined behavior.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_rem<T>(lhs: T, rhs: T) -> T;

/// Shifts vector left elementwise, with UB on overflow.
///
/// Shifts `lhs` left by `rhs`, shifting in sign bits for signed types.
///
/// `T` must be a vector of integers.
///
/// # Safety
///
/// Each element of `rhs` must be less than `<int>::BITS`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_shl<T>(lhs: T, rhs: T) -> T;

/// Shifts vector right elementwise, with UB on overflow.
///
/// `T` must be a vector of integers.
///
/// Shifts `lhs` right by `rhs`, shifting in sign bits for signed types.
///
/// # Safety
///
/// Each element of `rhs` must be less than `<int>::BITS`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_shr<T>(lhs: T, rhs: T) -> T;

/// Funnel Shifts vector left elementwise, with UB on overflow.
///
/// Concatenates `a` and `b` elementwise (with `a` in the most significant half),
/// creating a vector of the same length, but with each element being twice as
/// wide. Then shift this vector left elementwise by `shift`, shifting in zeros,
/// and extract the most significant half of each of the elements. If `a` and `b`
/// are the same, this is equivalent to an elementwise rotate left operation.
///
/// `T` must be a vector of integers.
///
/// # Safety
///
/// Each element of `shift` must be less than `<int>::BITS`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_funnel_shl<T>(a: T, b: T, shift: T) -> T;

/// Funnel Shifts vector right elementwise, with UB on overflow.
///
/// Concatenates `a` and `b` elementwise (with `a` in the most significant half),
/// creating a vector of the same length, but with each element being twice as
/// wide. Then shift this vector right elementwise by `shift`, shifting in zeros,
/// and extract the least significant half of each of the elements. If `a` and `b`
/// are the same, this is equivalent to an elementwise rotate right operation.
///
/// `T` must be a vector of integers.
///
/// # Safety
///
/// Each element of `shift` must be less than `<int>::BITS`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_funnel_shr<T>(a: T, b: T, shift: T) -> T;

/// Compute the carry-less product.
///
/// This is similar to long multiplication except that the carry is discarded.
///
/// This operation can be used to model multiplication in `GF(2)[X]`, the polynomial
/// ring over `GF(2)`.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
pub unsafe fn simd_carryless_mul<T>(a: T, b: T) -> T;

/// "And"s vectors elementwise.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_and<T>(x: T, y: T) -> T;

/// "Ors" vectors elementwise.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_or<T>(x: T, y: T) -> T;

/// "Exclusive ors" vectors elementwise.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_xor<T>(x: T, y: T) -> T;

/// Numerically casts a vector, elementwise.
///
/// `T` and `U` must be vectors of integers or floats, and must have the same length.
///
/// When casting floats to integers, the result is truncated. Out-of-bounds result lead to UB.
/// When casting integers to floats, the result is rounded.
/// Otherwise, truncates or extends the value, maintaining the sign for signed integers.
///
/// # Safety
/// Casting from integer types is always safe.
/// Casting between two float types is also always safe.
///
/// Casting floats to integers truncates, following the same rules as `to_int_unchecked`.
/// Specifically, each element must:
/// * Not be `NaN`
/// * Not be infinite
/// * Be representable in the return type, after truncating off its fractional part
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_cast<T, U>(x: T) -> U;

/// Numerically casts a vector, elementwise.
///
/// `T` and `U` be a vectors of integers or floats, and must have the same length.
///
/// Like `simd_cast`, but saturates float-to-integer conversions (NaN becomes 0).
/// This matches regular `as` and is always safe.
///
/// When casting floats to integers, the result is truncated.
/// When casting integers to floats, the result is rounded.
/// Otherwise, truncates or extends the value, maintaining the sign for signed integers.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_as<T, U>(x: T) -> U;

/// Negates a vector elementwise.
///
/// `T` must be a vector of integers or floats.
///
/// Rust panics for `-<int>::Min` due to overflow, but it is not UB with this intrinsic.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_neg<T>(x: T) -> T;

/// Returns absolute value of a vector, elementwise.
///
/// `T` must be a vector of floating-point primitive types.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_fabs<T>(x: T) -> T;

/// Returns the minimum of two vectors, elementwise.
///
/// `T` must be a vector of floating-point primitive types.
///
/// Follows IEEE-754 `minNum` semantics.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_fmin<T>(x: T, y: T) -> T;

/// Returns the maximum of two vectors, elementwise.
///
/// `T` must be a vector of floating-point primitive types.
///
/// Follows IEEE-754 `maxNum` semantics.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_fmax<T>(x: T, y: T) -> T;

/// Tests elementwise equality of two vectors.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be a vector of integers with the same number of elements and element size as `T`.
///
/// Returns `0` for false and `!0` for true.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_eq<T, U>(x: T, y: T) -> U;

/// Tests elementwise inequality equality of two vectors.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be a vector of integers with the same number of elements and element size as `T`.
///
/// Returns `0` for false and `!0` for true.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_ne<T, U>(x: T, y: T) -> U;

/// Tests if `x` is less than `y`, elementwise.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be a vector of integers with the same number of elements and element size as `T`.
///
/// Returns `0` for false and `!0` for true.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_lt<T, U>(x: T, y: T) -> U;

/// Tests if `x` is less than or equal to `y`, elementwise.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be a vector of integers with the same number of elements and element size as `T`.
///
/// Returns `0` for false and `!0` for true.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_le<T, U>(x: T, y: T) -> U;

/// Tests if `x` is greater than `y`, elementwise.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be a vector of integers with the same number of elements and element size as `T`.
///
/// Returns `0` for false and `!0` for true.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_gt<T, U>(x: T, y: T) -> U;

/// Tests if `x` is greater than or equal to `y`, elementwise.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be a vector of integers with the same number of elements and element size as `T`.
///
/// Returns `0` for false and `!0` for true.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_ge<T, U>(x: T, y: T) -> U;

/// Shuffles two vectors by const indices.
///
/// `T` must be a vector.
///
/// `U` must be a **const** vector of `u32`s. This means it must either refer to a named
/// const or be given as an inline const expression (`const { ... }`).
///
/// `V` must be a vector with the same element type as `T` and the same length as `U`.
///
/// Returns a new vector such that element `i` is selected from `xy[idx[i]]`, where `xy`
/// is the concatenation of `x` and `y`. It is a compile-time error if `idx[i]` is out-of-bounds
/// of `xy`.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_shuffle<T, U, V>(x: T, y: T, idx: U) -> V;

/// Reads a vector of pointers.
///
/// `T` must be a vector.
///
/// `U` must be a vector of pointers to the element type of `T`, with the same length as `T`.
///
/// `V` must be a vector of integers with the same length as `T` (but any element size).
///
/// For each pointer in `ptr`, if the corresponding value in `mask` is `!0`, read the pointer.
/// Otherwise if the corresponding value in `mask` is `0`, return the corresponding value from
/// `val`.
///
/// # Safety
/// Unmasked values in `T` must be readable as if by `<ptr>::read` (e.g. aligned to the element
/// type).
///
/// `mask` must only contain `0` or `!0` values.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_gather<T, U, V>(val: T, ptr: U, mask: V) -> T;

/// Writes to a vector of pointers.
///
/// `T` must be a vector.
///
/// `U` must be a vector of pointers to the element type of `T`, with the same length as `T`.
///
/// `V` must be a vector of integers with the same length as `T` (but any element size).
///
/// For each pointer in `ptr`, if the corresponding value in `mask` is `!0`, write the
/// corresponding value in `val` to the pointer.
/// Otherwise if the corresponding value in `mask` is `0`, do nothing.
///
/// The stores happen in left-to-right order.
/// (This is relevant in case two of the stores overlap.)
///
/// # Safety
/// Unmasked values in `T` must be writeable as if by `<ptr>::write` (e.g. aligned to the element
/// type).
///
/// `mask` must only contain `0` or `!0` values.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_scatter<T, U, V>(val: T, ptr: U, mask: V);

/// A type for alignment options for SIMD masked load/store intrinsics.
#[derive(Debug, ConstParamTy, PartialEq, Eq)]
#[cfg(not(feature = "ferrocene_subset"))]
pub enum SimdAlign {
    // These values must match the compiler's `SimdAlign` defined in
    // `rustc_middle/src/ty/consts/int.rs`!
    /// No alignment requirements on the pointer
    Unaligned = 0,
    /// The pointer must be aligned to the element type of the SIMD vector
    Element = 1,
    /// The pointer must be aligned to the SIMD vector type
    Vector = 2,
}

/// Reads a vector of pointers.
///
/// `T` must be a vector.
///
/// `U` must be a pointer to the element type of `T`
///
/// `V` must be a vector of integers with the same length as `T` (but any element size).
///
/// For each element, if the corresponding value in `mask` is `!0`, read the corresponding
/// pointer offset from `ptr`.
/// The first element is loaded from `ptr`, the second from `ptr.wrapping_offset(1)` and so on.
/// Otherwise if the corresponding value in `mask` is `0`, return the corresponding value from
/// `val`.
///
/// # Safety
/// `ptr` must be aligned according to the `ALIGN` parameter, see [`SimdAlign`] for details.
///
/// `mask` must only contain `0` or `!0` values.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_masked_load<V, U, T, const ALIGN: SimdAlign>(mask: V, ptr: U, val: T)
-> T;

/// Writes to a vector of pointers.
///
/// `T` must be a vector.
///
/// `U` must be a pointer to the element type of `T`
///
/// `V` must be a vector of integers with the same length as `T` (but any element size).
///
/// For each element, if the corresponding value in `mask` is `!0`, write the corresponding
/// value in `val` to the pointer offset from `ptr`.
/// The first element is written to `ptr`, the second to `ptr.wrapping_offset(1)` and so on.
/// Otherwise if the corresponding value in `mask` is `0`, do nothing.
///
/// # Safety
/// `ptr` must be aligned according to the `ALIGN` parameter, see [`SimdAlign`] for details.
///
/// `mask` must only contain `0` or `!0` values.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_masked_store<V, U, T, const ALIGN: SimdAlign>(mask: V, ptr: U, val: T);

/// Adds two simd vectors elementwise, with saturation.
///
/// `T` must be a vector of integer primitive types.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_saturating_add<T>(x: T, y: T) -> T;

/// Subtracts two simd vectors elementwise, with saturation.
///
/// `T` must be a vector of integer primitive types.
///
/// Subtract `rhs` from `lhs`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_saturating_sub<T>(lhs: T, rhs: T) -> T;

/// Adds elements within a vector from left to right.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
///
/// Starting with the value `y`, add the elements of `x` and accumulate.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_add_ordered<T, U>(x: T, y: U) -> U;

/// Adds elements within a vector in arbitrary order. May also be re-associated with
/// unordered additions on the inputs/outputs.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_reduce_add_unordered<T, U>(x: T) -> U;

/// Multiplies elements within a vector from left to right.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
///
/// Starting with the value `y`, multiply the elements of `x` and accumulate.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_mul_ordered<T, U>(x: T, y: U) -> U;

/// Multiplies elements within a vector in arbitrary order. May also be re-associated with
/// unordered additions on the inputs/outputs.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_reduce_mul_unordered<T, U>(x: T) -> U;

/// Checks if all mask values are true.
///
/// `T` must be a vector of integer primitive types.
///
/// # Safety
/// `x` must contain only `0` or `!0`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_all<T>(x: T) -> bool;

/// Checks if any mask value is true.
///
/// `T` must be a vector of integer primitive types.
///
/// # Safety
/// `x` must contain only `0` or `!0`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_any<T>(x: T) -> bool;

/// Returns the maximum element of a vector.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
///
/// For floating-point values, uses IEEE-754 `maxNum`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_max<T, U>(x: T) -> U;

/// Returns the minimum element of a vector.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
///
/// For floating-point values, uses IEEE-754 `minNum`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_min<T, U>(x: T) -> U;

/// Logical "and"s all elements together.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_and<T, U>(x: T) -> U;

/// Logical "ors" all elements together.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_or<T, U>(x: T) -> U;

/// Logical "exclusive ors" all elements together.
///
/// `T` must be a vector of integers or floats.
///
/// `U` must be the element type of `T`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_reduce_xor<T, U>(x: T) -> U;

/// Truncates an integer vector to a bitmask.
///
/// `T` must be an integer vector.
///
/// `U` must be either the smallest unsigned integer with at least as many bits as the length
/// of `T`, or the smallest array of `u8` with at least as many bits as the length of `T`.
///
/// Each element is truncated to a single bit and packed into the result.
///
/// No matter whether the output is an array or an unsigned integer, it is treated as a single
/// contiguous list of bits. The bitmask is always packed on the least-significant side of the
/// output, and padded with 0s in the most-significant bits. The order of the bits depends on
/// endianness:
///
/// * On little endian, the least significant bit corresponds to the first vector element.
/// * On big endian, the least significant bit corresponds to the last vector element.
///
/// For example, `[!0, 0, !0, !0]` packs to
/// - `0b1101u8` or `[0b1101]` on little endian, and
/// - `0b1011u8` or `[0b1011]` on big endian.
///
/// To consider a larger example,
/// `[!0, 0, 0, 0, 0, 0, 0, 0, !0, !0, 0, 0, 0, 0, !0, 0]` packs to
/// - `0b0100001100000001u16` or `[0b00000001, 0b01000011]` on little endian, and
/// - `0b1000000011000010u16` or `[0b10000000, 0b11000010]` on big endian.
///
/// And finally, a non-power-of-2 example with multiple bytes:
/// `[!0, !0, 0, !0, 0, 0, !0, 0, !0, 0]` packs to
/// - `0b0101001011u16` or `[0b01001011, 0b01]` on little endian, and
/// - `0b1101001010u16` or `[0b11, 0b01001010]` on big endian.
///
/// # Safety
/// `x` must contain only `0` and `!0`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_bitmask<T, U>(x: T) -> U;

/// Selects elements from a mask.
///
/// `T` must be a vector.
///
/// `M` must be an integer vector with the same length as `T` (but any element size).
///
/// For each element, if the corresponding value in `mask` is `!0`, select the element from
/// `if_true`.  If the corresponding value in `mask` is `0`, select the element from
/// `if_false`.
///
/// # Safety
/// `mask` must only contain `0` and `!0`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_select<M, T>(mask: M, if_true: T, if_false: T) -> T;

/// Selects elements from a bitmask.
///
/// `M` must be an unsigned integer or array of `u8`, matching `simd_bitmask`.
///
/// `T` must be a vector.
///
/// For each element, if the bit in `mask` is `1`, select the element from
/// `if_true`.  If the corresponding bit in `mask` is `0`, select the element from
/// `if_false`.
/// The remaining bits of the mask are ignored.
///
/// The bitmask bit order matches `simd_bitmask`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_select_bitmask<M, T>(m: M, yes: T, no: T) -> T;

/// Calculates the offset from a pointer vector elementwise, potentially
/// wrapping.
///
/// `T` must be a vector of pointers.
///
/// `U` must be a vector of `isize` or `usize` with the same number of elements as `T`.
///
/// Operates as if by `<ptr>::wrapping_offset`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_arith_offset<T, U>(ptr: T, offset: U) -> T;

/// Casts a vector of pointers.
///
/// `T` and `U` must be vectors of pointers with the same number of elements.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_cast_ptr<T, U>(ptr: T) -> U;

/// Exposes a vector of pointers as a vector of addresses.
///
/// `T` must be a vector of pointers.
///
/// `U` must be a vector of `usize` with the same length as `T`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_expose_provenance<T, U>(ptr: T) -> U;

/// Creates a vector of pointers from a vector of addresses.
///
/// `T` must be a vector of `usize`.
///
/// `U` must be a vector of pointers, with the same length as `T`.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_with_exposed_provenance<T, U>(addr: T) -> U;

/// Swaps bytes of each element.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_bswap<T>(x: T) -> T;

/// Reverses bits of each element.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_bitreverse<T>(x: T) -> T;

/// Counts the leading zeros of each element.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_ctlz<T>(x: T) -> T;

/// Counts the number of ones in each element.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_ctpop<T>(x: T) -> T;

/// Counts the trailing zeros of each element.
///
/// `T` must be a vector of integers.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_cttz<T>(x: T) -> T;

/// Rounds up each element to the next highest integer-valued float.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_ceil<T>(x: T) -> T;

/// Rounds down each element to the next lowest integer-valued float.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_floor<T>(x: T) -> T;

/// Rounds each element to the closest integer-valued float.
/// Ties are resolved by rounding away from 0.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_round<T>(x: T) -> T;

/// Rounds each element to the closest integer-valued float.
/// Ties are resolved by rounding to the number with an even least significant digit
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_round_ties_even<T>(x: T) -> T;

/// Returns the integer part of each element as an integer-valued float.
/// In other words, non-integer values are truncated towards zero.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_trunc<T>(x: T) -> T;

/// Takes the square root of each element.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_fsqrt<T>(x: T) -> T;

/// Computes `(x*y) + z` for each element, but without any intermediate rounding.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
pub const unsafe fn simd_fma<T>(x: T, y: T, z: T) -> T;

/// Computes `(x*y) + z` for each element, non-deterministically executing either
/// a fused multiply-add or two operations with rounding of the intermediate result.
///
/// The operation is fused if the code generator determines that target instruction
/// set has support for a fused operation, and that the fused operation is more efficient
/// than the equivalent, separate pair of mul and add instructions. It is unspecified
/// whether or not a fused operation is selected, and that may depend on optimization
/// level and context, for example. It may even be the case that some SIMD lanes get fused
/// and others do not.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub const unsafe fn simd_relaxed_fma<T>(x: T, y: T, z: T) -> T;

// Computes the sine of each element.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_fsin<T>(a: T) -> T;

// Computes the cosine of each element.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_fcos<T>(a: T) -> T;

// Computes the exponential function of each element.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_fexp<T>(a: T) -> T;

// Computes 2 raised to the power of each element.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_fexp2<T>(a: T) -> T;

// Computes the base 10 logarithm of each element.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_flog10<T>(a: T) -> T;

// Computes the base 2 logarithm of each element.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_flog2<T>(a: T) -> T;

// Computes the natural logarithm of each element.
///
/// `T` must be a vector of floats.
#[rustc_intrinsic]
#[rustc_nounwind]
#[cfg(not(feature = "ferrocene_subset"))]
pub unsafe fn simd_flog<T>(a: T) -> T;