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//! Compiler intrinsics. //! //! The corresponding definitions are in `compiler/rustc_codegen_llvm/src/intrinsic.rs`. //! The corresponding const implementations are in `compiler/rustc_mir/src/interpret/intrinsics.rs` //! //! # Const intrinsics //! //! Note: any changes to the constness of intrinsics should be discussed with the language team. //! This includes changes in the stability of the constness. //! //! In order to make an intrinsic usable at compile-time, one needs to copy the implementation //! from <https://github.com/rust-lang/miri/blob/master/src/shims/intrinsics.rs> to //! `compiler/rustc_mir/src/interpret/intrinsics.rs` and add a //! `#[rustc_const_unstable(feature = "foo", issue = "01234")]` to the intrinsic. //! //! If an intrinsic is supposed to be used from a `const fn` with a `rustc_const_stable` attribute, //! the intrinsic's attribute must be `rustc_const_stable`, too. Such a change should not be done //! without T-lang consultation, because it bakes a feature into the language that cannot be //! replicated in user code without compiler support. //! //! # Volatiles //! //! The volatile intrinsics provide operations intended to act on I/O //! memory, which are guaranteed to not be reordered by the compiler //! across other volatile intrinsics. See the LLVM documentation on //! [[volatile]]. //! //! [volatile]: http://llvm.org/docs/LangRef.html#volatile-memory-accesses //! //! # Atomics //! //! The atomic intrinsics provide common atomic operations on machine //! words, with multiple possible memory orderings. They obey the same //! semantics as C++11. See the LLVM documentation on [[atomics]]. //! //! [atomics]: http://llvm.org/docs/Atomics.html //! //! A quick refresher on memory ordering: //! //! * Acquire - a barrier for acquiring a lock. Subsequent reads and writes //! take place after the barrier. //! * Release - a barrier for releasing a lock. Preceding reads and writes //! take place before the barrier. //! * Sequentially consistent - sequentially consistent operations are //! guaranteed to happen in order. This is the standard mode for working //! with atomic types and is equivalent to Java's `volatile`. #![unstable( feature = "core_intrinsics", reason = "intrinsics are unlikely to ever be stabilized, instead \ they should be used through stabilized interfaces \ in the rest of the standard library", issue = "none" )] #![allow(missing_docs)] use crate::marker::DiscriminantKind; use crate::mem; // These imports are used for simplifying intra-doc links #[allow(unused_imports)] #[cfg(all(target_has_atomic = "8", target_has_atomic = "32", target_has_atomic = "ptr"))] use crate::sync::atomic::{self, AtomicBool, AtomicI32, AtomicIsize, AtomicU32, Ordering}; #[stable(feature = "drop_in_place", since = "1.8.0")] #[rustc_deprecated( reason = "no longer an intrinsic - use `ptr::drop_in_place` directly", since = "1.18.0" )] pub use crate::ptr::drop_in_place; extern "rust-intrinsic" { // N.B., these intrinsics take raw pointers because they mutate aliased // memory, which is not valid for either `&` or `&mut`. /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::SeqCst`] as both the `success` and `failure` parameters. /// For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::Acquire`] as both the `success` and `failure` parameters. /// For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg_acq<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::Release`] as the `success` and [`Ordering::Relaxed`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg_rel<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::AcqRel`] as the `success` and [`Ordering::Acquire`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg_acqrel<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::Relaxed`] as both the `success` and `failure` parameters. /// For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::SeqCst`] as the `success` and [`Ordering::Relaxed`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg_failrelaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::SeqCst`] as the `success` and [`Ordering::Acquire`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg_failacq<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::Acquire`] as the `success` and [`Ordering::Relaxed`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg_acq_failrelaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange` method by passing /// [`Ordering::AcqRel`] as the `success` and [`Ordering::Relaxed`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange`]. pub fn atomic_cxchg_acqrel_failrelaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::SeqCst`] as both the `success` and `failure` parameters. /// For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::Acquire`] as both the `success` and `failure` parameters. /// For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak_acq<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::Release`] as the `success` and [`Ordering::Relaxed`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak_rel<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::AcqRel`] as the `success` and [`Ordering::Acquire`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak_acqrel<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::Relaxed`] as both the `success` and `failure` parameters. /// For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::SeqCst`] as the `success` and [`Ordering::Relaxed`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak_failrelaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::SeqCst`] as the `success` and [`Ordering::Acquire`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak_failacq<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::Acquire`] as the `success` and [`Ordering::Relaxed`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak_acq_failrelaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Stores a value if the current value is the same as the `old` value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `compare_exchange_weak` method by passing /// [`Ordering::AcqRel`] as the `success` and [`Ordering::Relaxed`] as the /// `failure` parameters. For example, [`AtomicBool::compare_exchange_weak`]. pub fn atomic_cxchgweak_acqrel_failrelaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); /// Loads the current value of the pointer. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `load` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::load`]. pub fn atomic_load<T: Copy>(src: *const T) -> T; /// Loads the current value of the pointer. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `load` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::load`]. pub fn atomic_load_acq<T: Copy>(src: *const T) -> T; /// Loads the current value of the pointer. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `load` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::load`]. pub fn atomic_load_relaxed<T: Copy>(src: *const T) -> T; pub fn atomic_load_unordered<T: Copy>(src: *const T) -> T; /// Stores the value at the specified memory location. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `store` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::store`]. pub fn atomic_store<T: Copy>(dst: *mut T, val: T); /// Stores the value at the specified memory location. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `store` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::store`]. pub fn atomic_store_rel<T: Copy>(dst: *mut T, val: T); /// Stores the value at the specified memory location. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `store` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::store`]. pub fn atomic_store_relaxed<T: Copy>(dst: *mut T, val: T); pub fn atomic_store_unordered<T: Copy>(dst: *mut T, val: T); /// Stores the value at the specified memory location, returning the old value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `swap` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::swap`]. pub fn atomic_xchg<T: Copy>(dst: *mut T, src: T) -> T; /// Stores the value at the specified memory location, returning the old value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `swap` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::swap`]. pub fn atomic_xchg_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Stores the value at the specified memory location, returning the old value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `swap` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::swap`]. pub fn atomic_xchg_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Stores the value at the specified memory location, returning the old value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `swap` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::swap`]. pub fn atomic_xchg_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Stores the value at the specified memory location, returning the old value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `swap` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::swap`]. pub fn atomic_xchg_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Adds to the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_add` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicIsize::fetch_add`]. pub fn atomic_xadd<T: Copy>(dst: *mut T, src: T) -> T; /// Adds to the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_add` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicIsize::fetch_add`]. pub fn atomic_xadd_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Adds to the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_add` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicIsize::fetch_add`]. pub fn atomic_xadd_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Adds to the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_add` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicIsize::fetch_add`]. pub fn atomic_xadd_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Adds to the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_add` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicIsize::fetch_add`]. pub fn atomic_xadd_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Subtract from the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_sub` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. pub fn atomic_xsub<T: Copy>(dst: *mut T, src: T) -> T; /// Subtract from the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_sub` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. pub fn atomic_xsub_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Subtract from the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_sub` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. pub fn atomic_xsub_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Subtract from the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_sub` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. pub fn atomic_xsub_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Subtract from the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_sub` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. pub fn atomic_xsub_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise and with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_and` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_and`]. pub fn atomic_and<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise and with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_and` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_and`]. pub fn atomic_and_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise and with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_and` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_and`]. pub fn atomic_and_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise and with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_and` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_and`]. pub fn atomic_and_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise and with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_and` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_and`]. pub fn atomic_and_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise nand with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`AtomicBool`] type via the `fetch_nand` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_nand`]. pub fn atomic_nand<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise nand with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`AtomicBool`] type via the `fetch_nand` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_nand`]. pub fn atomic_nand_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise nand with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`AtomicBool`] type via the `fetch_nand` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_nand`]. pub fn atomic_nand_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise nand with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`AtomicBool`] type via the `fetch_nand` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_nand`]. pub fn atomic_nand_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise nand with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`AtomicBool`] type via the `fetch_nand` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_nand`]. pub fn atomic_nand_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise or with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_or` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_or`]. pub fn atomic_or<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise or with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_or` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_or`]. pub fn atomic_or_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise or with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_or` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_or`]. pub fn atomic_or_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise or with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_or` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_or`]. pub fn atomic_or_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise or with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_or` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_or`]. pub fn atomic_or_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise xor with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_xor` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_xor`]. pub fn atomic_xor<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise xor with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_xor` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_xor`]. pub fn atomic_xor_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise xor with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_xor` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_xor`]. pub fn atomic_xor_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise xor with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_xor` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_xor`]. pub fn atomic_xor_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Bitwise xor with the current value, returning the previous value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] types via the `fetch_xor` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_xor`]. pub fn atomic_xor_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_max` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicI32::fetch_max`]. pub fn atomic_max<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_max` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicI32::fetch_max`]. pub fn atomic_max_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_max` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicI32::fetch_max`]. pub fn atomic_max_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_max` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicI32::fetch_max`]. pub fn atomic_max_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_max` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicI32::fetch_max`]. pub fn atomic_max_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_min` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicI32::fetch_min`]. pub fn atomic_min<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_min` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicI32::fetch_min`]. pub fn atomic_min_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_min` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicI32::fetch_min`]. pub fn atomic_min_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_min` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicI32::fetch_min`]. pub fn atomic_min_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using a signed comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] signed integer types via the `fetch_min` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicI32::fetch_min`]. pub fn atomic_min_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_min` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicU32::fetch_min`]. pub fn atomic_umin<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_min` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicU32::fetch_min`]. pub fn atomic_umin_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_min` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicU32::fetch_min`]. pub fn atomic_umin_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_min` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicU32::fetch_min`]. pub fn atomic_umin_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Minimum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_min` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicU32::fetch_min`]. pub fn atomic_umin_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_max` method by passing /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicU32::fetch_max`]. pub fn atomic_umax<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_max` method by passing /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicU32::fetch_max`]. pub fn atomic_umax_acq<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_max` method by passing /// [`Ordering::Release`] as the `order`. For example, [`AtomicU32::fetch_max`]. pub fn atomic_umax_rel<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_max` method by passing /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicU32::fetch_max`]. pub fn atomic_umax_acqrel<T: Copy>(dst: *mut T, src: T) -> T; /// Maximum with the current value using an unsigned comparison. /// /// The stabilized version of this intrinsic is available on the /// [`atomic`] unsigned integer types via the `fetch_max` method by passing /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicU32::fetch_max`]. pub fn atomic_umax_relaxed<T: Copy>(dst: *mut T, src: T) -> T; /// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction /// if supported; otherwise, it is a no-op. /// Prefetches have no effect on the behavior of the program but can change its performance /// characteristics. /// /// The `locality` argument must be a constant integer and is a temporal locality specifier /// ranging from (0) - no locality, to (3) - extremely local keep in cache. /// /// This intrinsic does not have a stable counterpart. pub fn prefetch_read_data<T>(data: *const T, locality: i32); /// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction /// if supported; otherwise, it is a no-op. /// Prefetches have no effect on the behavior of the program but can change its performance /// characteristics. /// /// The `locality` argument must be a constant integer and is a temporal locality specifier /// ranging from (0) - no locality, to (3) - extremely local keep in cache. /// /// This intrinsic does not have a stable counterpart. pub fn prefetch_write_data<T>(data: *const T, locality: i32); /// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction /// if supported; otherwise, it is a no-op. /// Prefetches have no effect on the behavior of the program but can change its performance /// characteristics. /// /// The `locality` argument must be a constant integer and is a temporal locality specifier /// ranging from (0) - no locality, to (3) - extremely local keep in cache. /// /// This intrinsic does not have a stable counterpart. pub fn prefetch_read_instruction<T>(data: *const T, locality: i32); /// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction /// if supported; otherwise, it is a no-op. /// Prefetches have no effect on the behavior of the program but can change its performance /// characteristics. /// /// The `locality` argument must be a constant integer and is a temporal locality specifier /// ranging from (0) - no locality, to (3) - extremely local keep in cache. /// /// This intrinsic does not have a stable counterpart. pub fn prefetch_write_instruction<T>(data: *const T, locality: i32); } extern "rust-intrinsic" { /// An atomic fence. /// /// The stabilized version of this intrinsic is available in /// [`atomic::fence`] by passing [`Ordering::SeqCst`] /// as the `order`. pub fn atomic_fence(); /// An atomic fence. /// /// The stabilized version of this intrinsic is available in /// [`atomic::fence`] by passing [`Ordering::Acquire`] /// as the `order`. pub fn atomic_fence_acq(); /// An atomic fence. /// /// The stabilized version of this intrinsic is available in /// [`atomic::fence`] by passing [`Ordering::Release`] /// as the `order`. pub fn atomic_fence_rel(); /// An atomic fence. /// /// The stabilized version of this intrinsic is available in /// [`atomic::fence`] by passing [`Ordering::AcqRel`] /// as the `order`. pub fn atomic_fence_acqrel(); /// A compiler-only memory barrier. /// /// Memory accesses will never be reordered across this barrier by the /// compiler, but no instructions will be emitted for it. This is /// appropriate for operations on the same thread that may be preempted, /// such as when interacting with signal handlers. /// /// The stabilized version of this intrinsic is available in /// [`atomic::compiler_fence`] by passing [`Ordering::SeqCst`] /// as the `order`. pub fn atomic_singlethreadfence(); /// A compiler-only memory barrier. /// /// Memory accesses will never be reordered across this barrier by the /// compiler, but no instructions will be emitted for it. This is /// appropriate for operations on the same thread that may be preempted, /// such as when interacting with signal handlers. /// /// The stabilized version of this intrinsic is available in /// [`atomic::compiler_fence`] by passing [`Ordering::Acquire`] /// as the `order`. pub fn atomic_singlethreadfence_acq(); /// A compiler-only memory barrier. /// /// Memory accesses will never be reordered across this barrier by the /// compiler, but no instructions will be emitted for it. This is /// appropriate for operations on the same thread that may be preempted, /// such as when interacting with signal handlers. /// /// The stabilized version of this intrinsic is available in /// [`atomic::compiler_fence`] by passing [`Ordering::Release`] /// as the `order`. pub fn atomic_singlethreadfence_rel(); /// A compiler-only memory barrier. /// /// Memory accesses will never be reordered across this barrier by the /// compiler, but no instructions will be emitted for it. This is /// appropriate for operations on the same thread that may be preempted, /// such as when interacting with signal handlers. /// /// The stabilized version of this intrinsic is available in /// [`atomic::compiler_fence`] by passing [`Ordering::AcqRel`] /// as the `order`. pub fn atomic_singlethreadfence_acqrel(); /// Magic intrinsic that derives its meaning from attributes /// attached to the function. /// /// For example, dataflow uses this to inject static assertions so /// that `rustc_peek(potentially_uninitialized)` would actually /// double-check that dataflow did indeed compute that it is /// uninitialized at that point in the control flow. /// /// This intrinsic should not be used outside of the compiler. pub fn rustc_peek<T>(_: T) -> T; /// Aborts the execution of the process. /// /// A more user-friendly and stable version of this operation is /// [`std::process::abort`](../../std/process/fn.abort.html). pub fn abort() -> !; /// Informs the optimizer that this point in the code is not reachable, /// enabling further optimizations. /// /// N.B., this is very different from the `unreachable!()` macro: Unlike the /// macro, which panics when it is executed, it is *undefined behavior* to /// reach code marked with this function. /// /// The stabilized version of this intrinsic is [`core::hint::unreachable_unchecked`](crate::hint::unreachable_unchecked). #[rustc_const_unstable(feature = "const_unreachable_unchecked", issue = "53188")] pub fn unreachable() -> !; /// Informs the optimizer that a condition is always true. /// If the condition is false, the behavior is undefined. /// /// No code is generated for this intrinsic, but the optimizer will try /// to preserve it (and its condition) between passes, which may interfere /// with optimization of surrounding code and reduce performance. It should /// not be used if the invariant can be discovered by the optimizer on its /// own, or if it does not enable any significant optimizations. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_assume", issue = "76972")] pub fn assume(b: bool); /// Hints to the compiler that branch condition is likely to be true. /// Returns the value passed to it. /// /// Any use other than with `if` statements will probably not have an effect. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_likely", issue = "none")] pub fn likely(b: bool) -> bool; /// Hints to the compiler that branch condition is likely to be false. /// Returns the value passed to it. /// /// Any use other than with `if` statements will probably not have an effect. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_likely", issue = "none")] pub fn unlikely(b: bool) -> bool; /// Executes a breakpoint trap, for inspection by a debugger. /// /// This intrinsic does not have a stable counterpart. pub fn breakpoint(); /// The size of a type in bytes. /// /// More specifically, this is the offset in bytes between successive /// items of the same type, including alignment padding. /// /// The stabilized version of this intrinsic is [`core::mem::size_of`](crate::mem::size_of). #[rustc_const_stable(feature = "const_size_of", since = "1.40.0")] pub fn size_of<T>() -> usize; /// The minimum alignment of a type. /// /// The stabilized version of this intrinsic is [`core::mem::align_of`](crate::mem::align_of). #[rustc_const_stable(feature = "const_min_align_of", since = "1.40.0")] pub fn min_align_of<T>() -> usize; /// The preferred alignment of a type. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_pref_align_of", issue = "none")] pub fn pref_align_of<T>() -> usize; /// The size of the referenced value in bytes. /// /// The stabilized version of this intrinsic is [`mem::size_of_val`]. #[rustc_const_unstable(feature = "const_size_of_val", issue = "46571")] pub fn size_of_val<T: ?Sized>(_: *const T) -> usize; /// The required alignment of the referenced value. /// /// The stabilized version of this intrinsic is [`core::mem::align_of_val`](crate::mem::align_of_val). #[rustc_const_unstable(feature = "const_align_of_val", issue = "46571")] pub fn min_align_of_val<T: ?Sized>(_: *const T) -> usize; /// Gets a static string slice containing the name of a type. /// /// The stabilized version of this intrinsic is [`core::any::type_name`](crate::any::type_name). #[rustc_const_unstable(feature = "const_type_name", issue = "63084")] pub fn type_name<T: ?Sized>() -> &'static str; /// Gets an identifier which is globally unique to the specified type. This /// function will return the same value for a type regardless of whichever /// crate it is invoked in. /// /// The stabilized version of this intrinsic is [`core::any::TypeId::of`](crate::any::TypeId::of). #[rustc_const_unstable(feature = "const_type_id", issue = "77125")] pub fn type_id<T: ?Sized + 'static>() -> u64; /// A guard for unsafe functions that cannot ever be executed if `T` is uninhabited: /// This will statically either panic, or do nothing. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_assert_type", issue = "none")] pub fn assert_inhabited<T>(); /// A guard for unsafe functions that cannot ever be executed if `T` does not permit /// zero-initialization: This will statically either panic, or do nothing. /// /// This intrinsic does not have a stable counterpart. pub fn assert_zero_valid<T>(); /// A guard for unsafe functions that cannot ever be executed if `T` has invalid /// bit patterns: This will statically either panic, or do nothing. /// /// This intrinsic does not have a stable counterpart. pub fn assert_uninit_valid<T>(); /// Gets a reference to a static `Location` indicating where it was called. /// /// Consider using [`core::panic::Location::caller`](crate::panic::Location::caller) instead. #[rustc_const_unstable(feature = "const_caller_location", issue = "76156")] pub fn caller_location() -> &'static crate::panic::Location<'static>; /// Moves a value out of scope without running drop glue. /// /// This exists solely for [`mem::forget_unsized`]; normal `forget` uses /// `ManuallyDrop` instead. #[rustc_const_unstable(feature = "const_intrinsic_forget", issue = "none")] pub fn forget<T: ?Sized>(_: T); /// Reinterprets the bits of a value of one type as another type. /// /// Both types must have the same size. Neither the original, nor the result, /// may be an [invalid value](../../nomicon/what-unsafe-does.html). /// /// `transmute` is semantically equivalent to a bitwise move of one type /// into another. It copies the bits from the source value into the /// destination value, then forgets the original. It's equivalent to C's /// `memcpy` under the hood, just like `transmute_copy`. /// /// `transmute` is **incredibly** unsafe. There are a vast number of ways to /// cause [undefined behavior][ub] with this function. `transmute` should be /// the absolute last resort. /// /// The [nomicon](../../nomicon/transmutes.html) has additional /// documentation. /// /// [ub]: ../../reference/behavior-considered-undefined.html /// /// # Examples /// /// There are a few things that `transmute` is really useful for. /// /// Turning a pointer into a function pointer. This is *not* portable to /// machines where function pointers and data pointers have different sizes. /// /// ``` /// fn foo() -> i32 { /// 0 /// } /// let pointer = foo as *const (); /// let function = unsafe { /// std::mem::transmute::<*const (), fn() -> i32>(pointer) /// }; /// assert_eq!(function(), 0); /// ``` /// /// Extending a lifetime, or shortening an invariant lifetime. This is /// advanced, very unsafe Rust! /// /// ``` /// struct R<'a>(&'a i32); /// unsafe fn extend_lifetime<'b>(r: R<'b>) -> R<'static> { /// std::mem::transmute::<R<'b>, R<'static>>(r) /// } /// /// unsafe fn shorten_invariant_lifetime<'b, 'c>(r: &'b mut R<'static>) /// -> &'b mut R<'c> { /// std::mem::transmute::<&'b mut R<'static>, &'b mut R<'c>>(r) /// } /// ``` /// /// # Alternatives /// /// Don't despair: many uses of `transmute` can be achieved through other means. /// Below are common applications of `transmute` which can be replaced with safer /// constructs. /// /// Turning raw bytes(`&[u8]`) to `u32`, `f64`, etc.: /// /// ``` /// let raw_bytes = [0x78, 0x56, 0x34, 0x12]; /// /// let num = unsafe { /// std::mem::transmute::<[u8; 4], u32>(raw_bytes) /// }; /// /// // use `u32::from_ne_bytes` instead /// let num = u32::from_ne_bytes(raw_bytes); /// // or use `u32::from_le_bytes` or `u32::from_be_bytes` to specify the endianness /// let num = u32::from_le_bytes(raw_bytes); /// assert_eq!(num, 0x12345678); /// let num = u32::from_be_bytes(raw_bytes); /// assert_eq!(num, 0x78563412); /// ``` /// /// Turning a pointer into a `usize`: /// /// ``` /// let ptr = &0; /// let ptr_num_transmute = unsafe { /// std::mem::transmute::<&i32, usize>(ptr) /// }; /// /// // Use an `as` cast instead /// let ptr_num_cast = ptr as *const i32 as usize; /// ``` /// /// Turning a `*mut T` into an `&mut T`: /// /// ``` /// let ptr: *mut i32 = &mut 0; /// let ref_transmuted = unsafe { /// std::mem::transmute::<*mut i32, &mut i32>(ptr) /// }; /// /// // Use a reborrow instead /// let ref_casted = unsafe { &mut *ptr }; /// ``` /// /// Turning an `&mut T` into an `&mut U`: /// /// ``` /// let ptr = &mut 0; /// let val_transmuted = unsafe { /// std::mem::transmute::<&mut i32, &mut u32>(ptr) /// }; /// /// // Now, put together `as` and reborrowing - note the chaining of `as` /// // `as` is not transitive /// let val_casts = unsafe { &mut *(ptr as *mut i32 as *mut u32) }; /// ``` /// /// Turning an `&str` into an `&[u8]`: /// /// ``` /// // this is not a good way to do this. /// let slice = unsafe { std::mem::transmute::<&str, &[u8]>("Rust") }; /// assert_eq!(slice, &[82, 117, 115, 116]); /// /// // You could use `str::as_bytes` /// let slice = "Rust".as_bytes(); /// assert_eq!(slice, &[82, 117, 115, 116]); /// /// // Or, just use a byte string, if you have control over the string /// // literal /// assert_eq!(b"Rust", &[82, 117, 115, 116]); /// ``` /// /// Turning a `Vec<&T>` into a `Vec<Option<&T>>`: /// /// ``` /// let store = [0, 1, 2, 3]; /// let v_orig = store.iter().collect::<Vec<&i32>>(); /// /// // clone the vector as we will reuse them later /// let v_clone = v_orig.clone(); /// /// // Using transmute: this relies on the unspecified data layout of `Vec`, which is a /// // bad idea and could cause Undefined Behavior. /// // However, it is no-copy. /// let v_transmuted = unsafe { /// std::mem::transmute::<Vec<&i32>, Vec<Option<&i32>>>(v_clone) /// }; /// /// let v_clone = v_orig.clone(); /// /// // This is the suggested, safe way. /// // It does copy the entire vector, though, into a new array. /// let v_collected = v_clone.into_iter() /// .map(Some) /// .collect::<Vec<Option<&i32>>>(); /// /// let v_clone = v_orig.clone(); /// /// // The no-copy, unsafe way, still using transmute, but not relying on the data layout. /// // Like the first approach, this reuses the `Vec` internals. /// // Therefore, the new inner type must have the /// // exact same size, *and the same alignment*, as the old type. /// // The same caveats exist for this method as transmute, for /// // the original inner type (`&i32`) to the converted inner type /// // (`Option<&i32>`), so read the nomicon pages linked above and also /// // consult the [`from_raw_parts`] documentation. /// let v_from_raw = unsafe { // FIXME Update this when vec_into_raw_parts is stabilized /// // Ensure the original vector is not dropped. /// let mut v_clone = std::mem::ManuallyDrop::new(v_clone); /// Vec::from_raw_parts(v_clone.as_mut_ptr() as *mut Option<&i32>, /// v_clone.len(), /// v_clone.capacity()) /// }; /// ``` /// /// [`from_raw_parts`]: ../../std/vec/struct.Vec.html#method.from_raw_parts /// /// Implementing `split_at_mut`: /// /// ``` /// use std::{slice, mem}; /// /// // There are multiple ways to do this, and there are multiple problems /// // with the following (transmute) way. /// fn split_at_mut_transmute<T>(slice: &mut [T], mid: usize) /// -> (&mut [T], &mut [T]) { /// let len = slice.len(); /// assert!(mid <= len); /// unsafe { /// let slice2 = mem::transmute::<&mut [T], &mut [T]>(slice); /// // first: transmute is not type safe; all it checks is that T and /// // U are of the same size. Second, right here, you have two /// // mutable references pointing to the same memory. /// (&mut slice[0..mid], &mut slice2[mid..len]) /// } /// } /// /// // This gets rid of the type safety problems; `&mut *` will *only* give /// // you an `&mut T` from an `&mut T` or `*mut T`. /// fn split_at_mut_casts<T>(slice: &mut [T], mid: usize) /// -> (&mut [T], &mut [T]) { /// let len = slice.len(); /// assert!(mid <= len); /// unsafe { /// let slice2 = &mut *(slice as *mut [T]); /// // however, you still have two mutable references pointing to /// // the same memory. /// (&mut slice[0..mid], &mut slice2[mid..len]) /// } /// } /// /// // This is how the standard library does it. This is the best method, if /// // you need to do something like this /// fn split_at_stdlib<T>(slice: &mut [T], mid: usize) /// -> (&mut [T], &mut [T]) { /// let len = slice.len(); /// assert!(mid <= len); /// unsafe { /// let ptr = slice.as_mut_ptr(); /// // This now has three mutable references pointing at the same /// // memory. `slice`, the rvalue ret.0, and the rvalue ret.1. /// // `slice` is never used after `let ptr = ...`, and so one can /// // treat it as "dead", and therefore, you only have two real /// // mutable slices. /// (slice::from_raw_parts_mut(ptr, mid), /// slice::from_raw_parts_mut(ptr.add(mid), len - mid)) /// } /// } /// ``` #[stable(feature = "rust1", since = "1.0.0")] // NOTE: While this makes the intrinsic const stable, we have some custom code in const fn // checks that prevent its use within `const fn`. #[rustc_const_stable(feature = "const_transmute", since = "1.46.0")] #[rustc_diagnostic_item = "transmute"] pub fn transmute<T, U>(e: T) -> U; /// Returns `true` if the actual type given as `T` requires drop /// glue; returns `false` if the actual type provided for `T` /// implements `Copy`. /// /// If the actual type neither requires drop glue nor implements /// `Copy`, then the return value of this function is unspecified. /// /// The stabilized version of this intrinsic is [`mem::needs_drop`](crate::mem::needs_drop). #[rustc_const_stable(feature = "const_needs_drop", since = "1.40.0")] pub fn needs_drop<T>() -> bool; /// Calculates the offset from a pointer. /// /// This is implemented as an intrinsic to avoid converting to and from an /// integer, since the conversion would throw away aliasing information. /// /// # Safety /// /// Both the starting and resulting pointer must be either in bounds or one /// byte past the end of an allocated object. If either pointer is out of /// bounds or arithmetic overflow occurs then any further use of the /// returned value will result in undefined behavior. /// /// The stabilized version of this intrinsic is [`pointer::offset`]. #[must_use = "returns a new pointer rather than modifying its argument"] #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")] pub fn offset<T>(dst: *const T, offset: isize) -> *const T; /// Calculates the offset from a pointer, potentially wrapping. /// /// This is implemented as an intrinsic to avoid converting to and from an /// integer, since the conversion inhibits certain optimizations. /// /// # Safety /// /// Unlike the `offset` intrinsic, this intrinsic does not restrict the /// resulting pointer to point into or one byte past the end of an allocated /// object, and it wraps with two's complement arithmetic. The resulting /// value is not necessarily valid to be used to actually access memory. /// /// The stabilized version of this intrinsic is [`pointer::wrapping_offset`]. #[must_use = "returns a new pointer rather than modifying its argument"] #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")] pub fn arith_offset<T>(dst: *const T, offset: isize) -> *const T; /// Equivalent to the appropriate `llvm.memcpy.p0i8.0i8.*` intrinsic, with /// a size of `count` * `size_of::<T>()` and an alignment of /// `min_align_of::<T>()` /// /// The volatile parameter is set to `true`, so it will not be optimized out /// unless size is equal to zero. /// /// This intrinsic does not have a stable counterpart. pub fn volatile_copy_nonoverlapping_memory<T>(dst: *mut T, src: *const T, count: usize); /// Equivalent to the appropriate `llvm.memmove.p0i8.0i8.*` intrinsic, with /// a size of `count * size_of::<T>()` and an alignment of /// `min_align_of::<T>()` /// /// The volatile parameter is set to `true`, so it will not be optimized out /// unless size is equal to zero. /// /// This intrinsic does not have a stable counterpart. pub fn volatile_copy_memory<T>(dst: *mut T, src: *const T, count: usize); /// Equivalent to the appropriate `llvm.memset.p0i8.*` intrinsic, with a /// size of `count * size_of::<T>()` and an alignment of /// `min_align_of::<T>()`. /// /// The volatile parameter is set to `true`, so it will not be optimized out /// unless size is equal to zero. /// /// This intrinsic does not have a stable counterpart. pub fn volatile_set_memory<T>(dst: *mut T, val: u8, count: usize); /// Performs a volatile load from the `src` pointer. /// /// The stabilized version of this intrinsic is [`core::ptr::read_volatile`](crate::ptr::read_volatile). pub fn volatile_load<T>(src: *const T) -> T; /// Performs a volatile store to the `dst` pointer. /// /// The stabilized version of this intrinsic is [`core::ptr::write_volatile`](crate::ptr::write_volatile). pub fn volatile_store<T>(dst: *mut T, val: T); /// Performs a volatile load from the `src` pointer /// The pointer is not required to be aligned. /// /// This intrinsic does not have a stable counterpart. pub fn unaligned_volatile_load<T>(src: *const T) -> T; /// Performs a volatile store to the `dst` pointer. /// The pointer is not required to be aligned. /// /// This intrinsic does not have a stable counterpart. pub fn unaligned_volatile_store<T>(dst: *mut T, val: T); /// Returns the square root of an `f32` /// /// The stabilized version of this intrinsic is /// [`f32::sqrt`](../../std/primitive.f32.html#method.sqrt) pub fn sqrtf32(x: f32) -> f32; /// Returns the square root of an `f64` /// /// The stabilized version of this intrinsic is /// [`f64::sqrt`](../../std/primitive.f64.html#method.sqrt) pub fn sqrtf64(x: f64) -> f64; /// Raises an `f32` to an integer power. /// /// The stabilized version of this intrinsic is /// [`f32::powi`](../../std/primitive.f32.html#method.powi) pub fn powif32(a: f32, x: i32) -> f32; /// Raises an `f64` to an integer power. /// /// The stabilized version of this intrinsic is /// [`f64::powi`](../../std/primitive.f64.html#method.powi) pub fn powif64(a: f64, x: i32) -> f64; /// Returns the sine of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::sin`](../../std/primitive.f32.html#method.sin) pub fn sinf32(x: f32) -> f32; /// Returns the sine of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::sin`](../../std/primitive.f64.html#method.sin) pub fn sinf64(x: f64) -> f64; /// Returns the cosine of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::cos`](../../std/primitive.f32.html#method.cos) pub fn cosf32(x: f32) -> f32; /// Returns the cosine of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::cos`](../../std/primitive.f64.html#method.cos) pub fn cosf64(x: f64) -> f64; /// Raises an `f32` to an `f32` power. /// /// The stabilized version of this intrinsic is /// [`f32::powf`](../../std/primitive.f32.html#method.powf) pub fn powf32(a: f32, x: f32) -> f32; /// Raises an `f64` to an `f64` power. /// /// The stabilized version of this intrinsic is /// [`f64::powf`](../../std/primitive.f64.html#method.powf) pub fn powf64(a: f64, x: f64) -> f64; /// Returns the exponential of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::exp`](../../std/primitive.f32.html#method.exp) pub fn expf32(x: f32) -> f32; /// Returns the exponential of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::exp`](../../std/primitive.f64.html#method.exp) pub fn expf64(x: f64) -> f64; /// Returns 2 raised to the power of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::exp2`](../../std/primitive.f32.html#method.exp2) pub fn exp2f32(x: f32) -> f32; /// Returns 2 raised to the power of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::exp2`](../../std/primitive.f64.html#method.exp2) pub fn exp2f64(x: f64) -> f64; /// Returns the natural logarithm of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::ln`](../../std/primitive.f32.html#method.ln) pub fn logf32(x: f32) -> f32; /// Returns the natural logarithm of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::ln`](../../std/primitive.f64.html#method.ln) pub fn logf64(x: f64) -> f64; /// Returns the base 10 logarithm of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::log10`](../../std/primitive.f32.html#method.log10) pub fn log10f32(x: f32) -> f32; /// Returns the base 10 logarithm of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::log10`](../../std/primitive.f64.html#method.log10) pub fn log10f64(x: f64) -> f64; /// Returns the base 2 logarithm of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::log2`](../../std/primitive.f32.html#method.log2) pub fn log2f32(x: f32) -> f32; /// Returns the base 2 logarithm of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::log2`](../../std/primitive.f64.html#method.log2) pub fn log2f64(x: f64) -> f64; /// Returns `a * b + c` for `f32` values. /// /// The stabilized version of this intrinsic is /// [`f32::mul_add`](../../std/primitive.f32.html#method.mul_add) pub fn fmaf32(a: f32, b: f32, c: f32) -> f32; /// Returns `a * b + c` for `f64` values. /// /// The stabilized version of this intrinsic is /// [`f64::mul_add`](../../std/primitive.f64.html#method.mul_add) pub fn fmaf64(a: f64, b: f64, c: f64) -> f64; /// Returns the absolute value of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::abs`](../../std/primitive.f32.html#method.abs) pub fn fabsf32(x: f32) -> f32; /// Returns the absolute value of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::abs`](../../std/primitive.f64.html#method.abs) pub fn fabsf64(x: f64) -> f64; /// Returns the minimum of two `f32` values. /// /// The stabilized version of this intrinsic is /// [`f32::min`] pub fn minnumf32(x: f32, y: f32) -> f32; /// Returns the minimum of two `f64` values. /// /// The stabilized version of this intrinsic is /// [`f64::min`] pub fn minnumf64(x: f64, y: f64) -> f64; /// Returns the maximum of two `f32` values. /// /// The stabilized version of this intrinsic is /// [`f32::max`] pub fn maxnumf32(x: f32, y: f32) -> f32; /// Returns the maximum of two `f64` values. /// /// The stabilized version of this intrinsic is /// [`f64::max`] pub fn maxnumf64(x: f64, y: f64) -> f64; /// Copies the sign from `y` to `x` for `f32` values. /// /// The stabilized version of this intrinsic is /// [`f32::copysign`](../../std/primitive.f32.html#method.copysign) pub fn copysignf32(x: f32, y: f32) -> f32; /// Copies the sign from `y` to `x` for `f64` values. /// /// The stabilized version of this intrinsic is /// [`f64::copysign`](../../std/primitive.f64.html#method.copysign) pub fn copysignf64(x: f64, y: f64) -> f64; /// Returns the largest integer less than or equal to an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::floor`](../../std/primitive.f32.html#method.floor) pub fn floorf32(x: f32) -> f32; /// Returns the largest integer less than or equal to an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::floor`](../../std/primitive.f64.html#method.floor) pub fn floorf64(x: f64) -> f64; /// Returns the smallest integer greater than or equal to an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::ceil`](../../std/primitive.f32.html#method.ceil) pub fn ceilf32(x: f32) -> f32; /// Returns the smallest integer greater than or equal to an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::ceil`](../../std/primitive.f64.html#method.ceil) pub fn ceilf64(x: f64) -> f64; /// Returns the integer part of an `f32`. /// /// The stabilized version of this intrinsic is /// [`f32::trunc`](../../std/primitive.f32.html#method.trunc) pub fn truncf32(x: f32) -> f32; /// Returns the integer part of an `f64`. /// /// The stabilized version of this intrinsic is /// [`f64::trunc`](../../std/primitive.f64.html#method.trunc) pub fn truncf64(x: f64) -> f64; /// Returns the nearest integer to an `f32`. May raise an inexact floating-point exception /// if the argument is not an integer. pub fn rintf32(x: f32) -> f32; /// Returns the nearest integer to an `f64`. May raise an inexact floating-point exception /// if the argument is not an integer. pub fn rintf64(x: f64) -> f64; /// Returns the nearest integer to an `f32`. /// /// This intrinsic does not have a stable counterpart. pub fn nearbyintf32(x: f32) -> f32; /// Returns the nearest integer to an `f64`. /// /// This intrinsic does not have a stable counterpart. pub fn nearbyintf64(x: f64) -> f64; /// Returns the nearest integer to an `f32`. Rounds half-way cases away from zero. /// /// The stabilized version of this intrinsic is /// [`f32::round`](../../std/primitive.f32.html#method.round) pub fn roundf32(x: f32) -> f32; /// Returns the nearest integer to an `f64`. Rounds half-way cases away from zero. /// /// The stabilized version of this intrinsic is /// [`f64::round`](../../std/primitive.f64.html#method.round) pub fn roundf64(x: f64) -> f64; /// Float addition that allows optimizations based on algebraic rules. /// May assume inputs are finite. /// /// This intrinsic does not have a stable counterpart. pub fn fadd_fast<T: Copy>(a: T, b: T) -> T; /// Float subtraction that allows optimizations based on algebraic rules. /// May assume inputs are finite. /// /// This intrinsic does not have a stable counterpart. pub fn fsub_fast<T: Copy>(a: T, b: T) -> T; /// Float multiplication that allows optimizations based on algebraic rules. /// May assume inputs are finite. /// /// This intrinsic does not have a stable counterpart. pub fn fmul_fast<T: Copy>(a: T, b: T) -> T; /// Float division that allows optimizations based on algebraic rules. /// May assume inputs are finite. /// /// This intrinsic does not have a stable counterpart. pub fn fdiv_fast<T: Copy>(a: T, b: T) -> T; /// Float remainder that allows optimizations based on algebraic rules. /// May assume inputs are finite. /// /// This intrinsic does not have a stable counterpart. pub fn frem_fast<T: Copy>(a: T, b: T) -> T; /// Convert with LLVM’s fptoui/fptosi, which may return undef for values out of range /// (<https://github.com/rust-lang/rust/issues/10184>) /// /// Stabilized as [`f32::to_int_unchecked`] and [`f64::to_int_unchecked`]. pub fn float_to_int_unchecked<Float: Copy, Int: Copy>(value: Float) -> Int; /// Returns the number of bits set in an integer type `T` /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `count_ones` method. For example, /// [`u32::count_ones`] #[rustc_const_stable(feature = "const_ctpop", since = "1.40.0")] pub fn ctpop<T: Copy>(x: T) -> T; /// Returns the number of leading unset bits (zeroes) in an integer type `T`. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `leading_zeros` method. For example, /// [`u32::leading_zeros`] /// /// # Examples /// /// ``` /// #![feature(core_intrinsics)] /// /// use std::intrinsics::ctlz; /// /// let x = 0b0001_1100_u8; /// let num_leading = ctlz(x); /// assert_eq!(num_leading, 3); /// ``` /// /// An `x` with value `0` will return the bit width of `T`. /// /// ``` /// #![feature(core_intrinsics)] /// /// use std::intrinsics::ctlz; /// /// let x = 0u16; /// let num_leading = ctlz(x); /// assert_eq!(num_leading, 16); /// ``` #[rustc_const_stable(feature = "const_ctlz", since = "1.40.0")] pub fn ctlz<T: Copy>(x: T) -> T; /// Like `ctlz`, but extra-unsafe as it returns `undef` when /// given an `x` with value `0`. /// /// This intrinsic does not have a stable counterpart. /// /// # Examples /// /// ``` /// #![feature(core_intrinsics)] /// /// use std::intrinsics::ctlz_nonzero; /// /// let x = 0b0001_1100_u8; /// let num_leading = unsafe { ctlz_nonzero(x) }; /// assert_eq!(num_leading, 3); /// ``` #[rustc_const_stable(feature = "constctlz", since = "1.50.0")] pub fn ctlz_nonzero<T: Copy>(x: T) -> T; /// Returns the number of trailing unset bits (zeroes) in an integer type `T`. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `trailing_zeros` method. For example, /// [`u32::trailing_zeros`] /// /// # Examples /// /// ``` /// #![feature(core_intrinsics)] /// /// use std::intrinsics::cttz; /// /// let x = 0b0011_1000_u8; /// let num_trailing = cttz(x); /// assert_eq!(num_trailing, 3); /// ``` /// /// An `x` with value `0` will return the bit width of `T`: /// /// ``` /// #![feature(core_intrinsics)] /// /// use std::intrinsics::cttz; /// /// let x = 0u16; /// let num_trailing = cttz(x); /// assert_eq!(num_trailing, 16); /// ``` #[rustc_const_stable(feature = "const_cttz", since = "1.40.0")] pub fn cttz<T: Copy>(x: T) -> T; /// Like `cttz`, but extra-unsafe as it returns `undef` when /// given an `x` with value `0`. /// /// This intrinsic does not have a stable counterpart. /// /// # Examples /// /// ``` /// #![feature(core_intrinsics)] /// /// use std::intrinsics::cttz_nonzero; /// /// let x = 0b0011_1000_u8; /// let num_trailing = unsafe { cttz_nonzero(x) }; /// assert_eq!(num_trailing, 3); /// ``` #[rustc_const_unstable(feature = "const_cttz", issue = "none")] pub fn cttz_nonzero<T: Copy>(x: T) -> T; /// Reverses the bytes in an integer type `T`. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `swap_bytes` method. For example, /// [`u32::swap_bytes`] #[rustc_const_stable(feature = "const_bswap", since = "1.40.0")] pub fn bswap<T: Copy>(x: T) -> T; /// Reverses the bits in an integer type `T`. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `reverse_bits` method. For example, /// [`u32::reverse_bits`] #[rustc_const_stable(feature = "const_bitreverse", since = "1.40.0")] pub fn bitreverse<T: Copy>(x: T) -> T; /// Performs checked integer addition. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `overflowing_add` method. For example, /// [`u32::overflowing_add`] #[rustc_const_stable(feature = "const_int_overflow", since = "1.40.0")] pub fn add_with_overflow<T: Copy>(x: T, y: T) -> (T, bool); /// Performs checked integer subtraction /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `overflowing_sub` method. For example, /// [`u32::overflowing_sub`] #[rustc_const_stable(feature = "const_int_overflow", since = "1.40.0")] pub fn sub_with_overflow<T: Copy>(x: T, y: T) -> (T, bool); /// Performs checked integer multiplication /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `overflowing_mul` method. For example, /// [`u32::overflowing_mul`] #[rustc_const_stable(feature = "const_int_overflow", since = "1.40.0")] pub fn mul_with_overflow<T: Copy>(x: T, y: T) -> (T, bool); /// Performs an exact division, resulting in undefined behavior where /// `x % y != 0` or `y == 0` or `x == T::MIN && y == -1` /// /// This intrinsic does not have a stable counterpart. pub fn exact_div<T: Copy>(x: T, y: T) -> T; /// Performs an unchecked division, resulting in undefined behavior /// where `y == 0` or `x == T::MIN && y == -1` /// /// Safe wrappers for this intrinsic are available on the integer /// primitives via the `checked_div` method. For example, /// [`u32::checked_div`] #[rustc_const_stable(feature = "const_int_unchecked_arith", since = "1.52.0")] pub fn unchecked_div<T: Copy>(x: T, y: T) -> T; /// Returns the remainder of an unchecked division, resulting in /// undefined behavior when `y == 0` or `x == T::MIN && y == -1` /// /// Safe wrappers for this intrinsic are available on the integer /// primitives via the `checked_rem` method. For example, /// [`u32::checked_rem`] #[rustc_const_stable(feature = "const_int_unchecked_arith", since = "1.52.0")] pub fn unchecked_rem<T: Copy>(x: T, y: T) -> T; /// Performs an unchecked left shift, resulting in undefined behavior when /// `y < 0` or `y >= N`, where N is the width of T in bits. /// /// Safe wrappers for this intrinsic are available on the integer /// primitives via the `checked_shl` method. For example, /// [`u32::checked_shl`] #[rustc_const_stable(feature = "const_int_unchecked", since = "1.40.0")] pub fn unchecked_shl<T: Copy>(x: T, y: T) -> T; /// Performs an unchecked right shift, resulting in undefined behavior when /// `y < 0` or `y >= N`, where N is the width of T in bits. /// /// Safe wrappers for this intrinsic are available on the integer /// primitives via the `checked_shr` method. For example, /// [`u32::checked_shr`] #[rustc_const_stable(feature = "const_int_unchecked", since = "1.40.0")] pub fn unchecked_shr<T: Copy>(x: T, y: T) -> T; /// Returns the result of an unchecked addition, resulting in /// undefined behavior when `x + y > T::MAX` or `x + y < T::MIN`. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")] pub fn unchecked_add<T: Copy>(x: T, y: T) -> T; /// Returns the result of an unchecked subtraction, resulting in /// undefined behavior when `x - y > T::MAX` or `x - y < T::MIN`. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")] pub fn unchecked_sub<T: Copy>(x: T, y: T) -> T; /// Returns the result of an unchecked multiplication, resulting in /// undefined behavior when `x * y > T::MAX` or `x * y < T::MIN`. /// /// This intrinsic does not have a stable counterpart. #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")] pub fn unchecked_mul<T: Copy>(x: T, y: T) -> T; /// Performs rotate left. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `rotate_left` method. For example, /// [`u32::rotate_left`] #[rustc_const_stable(feature = "const_int_rotate", since = "1.40.0")] pub fn rotate_left<T: Copy>(x: T, y: T) -> T; /// Performs rotate right. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `rotate_right` method. For example, /// [`u32::rotate_right`] #[rustc_const_stable(feature = "const_int_rotate", since = "1.40.0")] pub fn rotate_right<T: Copy>(x: T, y: T) -> T; /// Returns (a + b) mod 2<sup>N</sup>, where N is the width of T in bits. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `wrapping_add` method. For example, /// [`u32::wrapping_add`] #[rustc_const_stable(feature = "const_int_wrapping", since = "1.40.0")] pub fn wrapping_add<T: Copy>(a: T, b: T) -> T; /// Returns (a - b) mod 2<sup>N</sup>, where N is the width of T in bits. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `wrapping_sub` method. For example, /// [`u32::wrapping_sub`] #[rustc_const_stable(feature = "const_int_wrapping", since = "1.40.0")] pub fn wrapping_sub<T: Copy>(a: T, b: T) -> T; /// Returns (a * b) mod 2<sup>N</sup>, where N is the width of T in bits. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `wrapping_mul` method. For example, /// [`u32::wrapping_mul`] #[rustc_const_stable(feature = "const_int_wrapping", since = "1.40.0")] pub fn wrapping_mul<T: Copy>(a: T, b: T) -> T; /// Computes `a + b`, saturating at numeric bounds. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `saturating_add` method. For example, /// [`u32::saturating_add`] #[rustc_const_stable(feature = "const_int_saturating", since = "1.40.0")] pub fn saturating_add<T: Copy>(a: T, b: T) -> T; /// Computes `a - b`, saturating at numeric bounds. /// /// The stabilized versions of this intrinsic are available on the integer /// primitives via the `saturating_sub` method. For example, /// [`u32::saturating_sub`] #[rustc_const_stable(feature = "const_int_saturating", since = "1.40.0")] pub fn saturating_sub<T: Copy>(a: T, b: T) -> T; /// Returns the value of the discriminant for the variant in 'v'; /// if `T` has no discriminant, returns `0`. /// /// The stabilized version of this intrinsic is [`core::mem::discriminant`](crate::mem::discriminant). #[rustc_const_unstable(feature = "const_discriminant", issue = "69821")] pub fn discriminant_value<T>(v: &T) -> <T as DiscriminantKind>::Discriminant; /// Returns the number of variants of the type `T` cast to a `usize`; /// if `T` has no variants, returns `0`. Uninhabited variants will be counted. /// /// The to-be-stabilized version of this intrinsic is [`mem::variant_count`]. #[rustc_const_unstable(feature = "variant_count", issue = "73662")] pub fn variant_count<T>() -> usize; /// Rust's "try catch" construct which invokes the function pointer `try_fn` /// with the data pointer `data`. /// /// The third argument is a function called if a panic occurs. This function /// takes the data pointer and a pointer to the target-specific exception /// object that was caught. For more information see the compiler's /// source as well as std's catch implementation. pub fn r#try(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32; /// Emits a `!nontemporal` store according to LLVM (see their docs). /// Probably will never become stable. pub fn nontemporal_store<T>(ptr: *mut T, val: T); /// See documentation of `<*const T>::offset_from` for details. #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "41079")] pub fn ptr_offset_from<T>(ptr: *const T, base: *const T) -> isize; /// See documentation of `<*const T>::guaranteed_eq` for details. #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")] pub fn ptr_guaranteed_eq<T>(ptr: *const T, other: *const T) -> bool; /// See documentation of `<*const T>::guaranteed_ne` for details. #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")] pub fn ptr_guaranteed_ne<T>(ptr: *const T, other: *const T) -> bool; /// Allocate at compile time. Should not be called at runtime. #[rustc_const_unstable(feature = "const_heap", issue = "79597")] pub fn const_allocate(size: usize, align: usize) -> *mut u8; /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source /// and destination must *not* overlap. /// /// For regions of memory which might overlap, use [`copy`] instead. /// /// `copy_nonoverlapping` is semantically equivalent to C's [`memcpy`], but /// with the argument order swapped. /// /// [`memcpy`]: https://en.cppreference.com/w/c/string/byte/memcpy /// /// # Safety /// /// Behavior is undefined if any of the following conditions are violated: /// /// * `src` must be [valid] for reads of `count * size_of::<T>()` bytes. /// /// * `dst` must be [valid] for writes of `count * size_of::<T>()` bytes. /// /// * Both `src` and `dst` must be properly aligned. /// /// * The region of memory beginning at `src` with a size of `count * /// size_of::<T>()` bytes must *not* overlap with the region of memory /// beginning at `dst` with the same size. /// /// Like [`read`], `copy_nonoverlapping` creates a bitwise copy of `T`, regardless of /// whether `T` is [`Copy`]. If `T` is not [`Copy`], using *both* the values /// in the region beginning at `*src` and the region beginning at `*dst` can /// [violate memory safety][read-ownership]. /// /// Note that even if the effectively copied size (`count * size_of::<T>()`) is /// `0`, the pointers must be non-NULL and properly aligned. /// /// [`read`]: crate::ptr::read /// [read-ownership]: crate::ptr::read#ownership-of-the-returned-value /// [valid]: crate::ptr#safety /// /// # Examples /// /// Manually implement [`Vec::append`]: /// /// ``` /// use std::ptr; /// /// /// Moves all the elements of `src` into `dst`, leaving `src` empty. /// fn append<T>(dst: &mut Vec<T>, src: &mut Vec<T>) { /// let src_len = src.len(); /// let dst_len = dst.len(); /// /// // Ensure that `dst` has enough capacity to hold all of `src`. /// dst.reserve(src_len); /// /// unsafe { /// // The call to offset is always safe because `Vec` will never /// // allocate more than `isize::MAX` bytes. /// let dst_ptr = dst.as_mut_ptr().offset(dst_len as isize); /// let src_ptr = src.as_ptr(); /// /// // Truncate `src` without dropping its contents. We do this first, /// // to avoid problems in case something further down panics. /// src.set_len(0); /// /// // The two regions cannot overlap because mutable references do /// // not alias, and two different vectors cannot own the same /// // memory. /// ptr::copy_nonoverlapping(src_ptr, dst_ptr, src_len); /// /// // Notify `dst` that it now holds the contents of `src`. /// dst.set_len(dst_len + src_len); /// } /// } /// /// let mut a = vec!['r']; /// let mut b = vec!['u', 's', 't']; /// /// append(&mut a, &mut b); /// /// assert_eq!(a, &['r', 'u', 's', 't']); /// assert!(b.is_empty()); /// ``` /// /// [`Vec::append`]: ../../std/vec/struct.Vec.html#method.append #[doc(alias = "memcpy")] #[stable(feature = "rust1", since = "1.0.0")] #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")] pub fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize); /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source /// and destination may overlap. /// /// If the source and destination will *never* overlap, /// [`copy_nonoverlapping`] can be used instead. /// /// `copy` is semantically equivalent to C's [`memmove`], but with the argument /// order swapped. Copying takes place as if the bytes were copied from `src` /// to a temporary array and then copied from the array to `dst`. /// /// [`memmove`]: https://en.cppreference.com/w/c/string/byte/memmove /// /// # Safety /// /// Behavior is undefined if any of the following conditions are violated: /// /// * `src` must be [valid] for reads of `count * size_of::<T>()` bytes. /// /// * `dst` must be [valid] for writes of `count * size_of::<T>()` bytes. /// /// * Both `src` and `dst` must be properly aligned. /// /// Like [`read`], `copy` creates a bitwise copy of `T`, regardless of /// whether `T` is [`Copy`]. If `T` is not [`Copy`], using both the values /// in the region beginning at `*src` and the region beginning at `*dst` can /// [violate memory safety][read-ownership]. /// /// Note that even if the effectively copied size (`count * size_of::<T>()`) is /// `0`, the pointers must be non-NULL and properly aligned. /// /// [`read`]: crate::ptr::read /// [read-ownership]: crate::ptr::read#ownership-of-the-returned-value /// [valid]: crate::ptr#safety /// /// # Examples /// /// Efficiently create a Rust vector from an unsafe buffer: /// /// ``` /// use std::ptr; /// /// /// # Safety /// /// /// /// * `ptr` must be correctly aligned for its type and non-zero. /// /// * `ptr` must be valid for reads of `elts` contiguous elements of type `T`. /// /// * Those elements must not be used after calling this function unless `T: Copy`. /// # #[allow(dead_code)] /// unsafe fn from_buf_raw<T>(ptr: *const T, elts: usize) -> Vec<T> { /// let mut dst = Vec::with_capacity(elts); /// /// // SAFETY: Our precondition ensures the source is aligned and valid, /// // and `Vec::with_capacity` ensures that we have usable space to write them. /// ptr::copy(ptr, dst.as_mut_ptr(), elts); /// /// // SAFETY: We created it with this much capacity earlier, /// // and the previous `copy` has initialized these elements. /// dst.set_len(elts); /// dst /// } /// ``` #[doc(alias = "memmove")] #[stable(feature = "rust1", since = "1.0.0")] #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")] pub fn copy<T>(src: *const T, dst: *mut T, count: usize); } // Some functions are defined here because they accidentally got made // available in this module on stable. See <https://github.com/rust-lang/rust/issues/15702>. // (`transmute` also falls into this category, but it cannot be wrapped due to the // check that `T` and `U` have the same size.) /// Checks whether `ptr` is properly aligned with respect to /// `align_of::<T>()`. pub(crate) fn is_aligned_and_not_null<T>(ptr: *const T) -> bool { !ptr.is_null() && ptr as usize % mem::align_of::<T>() == 0 } /// Checks whether the regions of memory starting at `src` and `dst` of size /// `count * size_of::<T>()` do *not* overlap. pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -> bool { let src_usize = src as usize; let dst_usize = dst as usize; let size = mem::size_of::<T>().checked_mul(count).unwrap(); let diff = if src_usize > dst_usize { src_usize - dst_usize } else { dst_usize - src_usize }; // If the absolute distance between the ptrs is at least as big as the size of the buffer, // they do not overlap. diff >= size } /// Sets `count * size_of::<T>()` bytes of memory starting at `dst` to /// `val`. /// /// `write_bytes` is similar to C's [`memset`], but sets `count * /// size_of::<T>()` bytes to `val`. /// /// [`memset`]: https://en.cppreference.com/w/c/string/byte/memset /// /// # Safety /// /// Behavior is undefined if any of the following conditions are violated: /// /// * `dst` must be [valid] for writes of `count * size_of::<T>()` bytes. /// /// * `dst` must be properly aligned. /// /// Additionally, the caller must ensure that writing `count * /// size_of::<T>()` bytes to the given region of memory results in a valid /// value of `T`. Using a region of memory typed as a `T` that contains an /// invalid value of `T` is undefined behavior. /// /// Note that even if the effectively copied size (`count * size_of::<T>()`) is /// `0`, the pointer must be non-NULL and properly aligned. /// /// [valid]: crate::ptr#safety /// /// # Examples /// /// Basic usage: /// /// ``` /// use std::ptr; /// /// let mut vec = vec![0u32; 4]; /// unsafe { /// let vec_ptr = vec.as_mut_ptr(); /// ptr::write_bytes(vec_ptr, 0xfe, 2); /// } /// assert_eq!(vec, [0xfefefefe, 0xfefefefe, 0, 0]); /// ``` /// /// Creating an invalid value: /// /// ``` /// use std::ptr; /// /// let mut v = Box::new(0i32); /// /// unsafe { /// // Leaks the previously held value by overwriting the `Box<T>` with /// // a null pointer. /// ptr::write_bytes(&mut v as *mut Box<i32>, 0, 1); /// } /// /// // At this point, using or dropping `v` results in undefined behavior. /// // drop(v); // ERROR /// /// // Even leaking `v` "uses" it, and hence is undefined behavior. /// // mem::forget(v); // ERROR /// /// // In fact, `v` is invalid according to basic type layout invariants, so *any* /// // operation touching it is undefined behavior. /// // let v2 = v; // ERROR /// /// unsafe { /// // Let us instead put in a valid value /// ptr::write(&mut v as *mut Box<i32>, Box::new(42i32)); /// } /// /// // Now the box is fine /// assert_eq!(*v, 42); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) { extern "rust-intrinsic" { fn write_bytes<T>(dst: *mut T, val: u8, count: usize); } debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer"); // SAFETY: the safety contract for `write_bytes` must be upheld by the caller. unsafe { write_bytes(dst, val, count) } }