mod.rs source code [crates/core/src/intrinsics/mod.rs]

1	//! Compiler intrinsics.
2	//!
3	//! The corresponding definitions are in <https://github.com/rust-lang/rust/blob/master/compiler/rustc_codegen_llvm/src/intrinsic.rs>.
4	//! The corresponding const implementations are in <https://github.com/rust-lang/rust/blob/master/compiler/rustc_const_eval/src/interpret/intrinsics.rs>.
5	//!
6	//! # Const intrinsics
7	//!
8	//! Note: any changes to the constness of intrinsics should be discussed with the language team.
9	//! This includes changes in the stability of the constness.
10	//!
11	//! In order to make an intrinsic usable at compile-time, it needs to be declared in the "new"
12	//! style, i.e. as a `#[rustc_intrinsic]` function, not inside an `extern` block. Then copy the
13	//! implementation from <https://github.com/rust-lang/miri/blob/master/src/intrinsics> to
14	//! <https://github.com/rust-lang/rust/blob/master/compiler/rustc_const_eval/src/interpret/intrinsics.rs>
15	//! and make the intrinsic declaration a `const fn`.
16	//!
17	//! If an intrinsic is supposed to be used from a `const fn` with a `rustc_const_stable` attribute,
18	//! `#[rustc_intrinsic_const_stable_indirect]` needs to be added to the intrinsic. Such a change requires
19	//! T-lang approval, because it may bake a feature into the language that cannot be replicated in
20	//! user code without compiler support.
21	//!
22	//! # Volatiles
23	//!
24	//! The volatile intrinsics provide operations intended to act on I/O
25	//! memory, which are guaranteed to not be reordered by the compiler
26	//! across other volatile intrinsics. See the LLVM documentation on
27	//! [[volatile]].
28	//!
29	//! [volatile]: https://llvm.org/docs/LangRef.html#volatile-memory-accesses
30	//!
31	//! # Atomics
32	//!
33	//! The atomic intrinsics provide common atomic operations on machine
34	//! words, with multiple possible memory orderings. They obey the same
35	//! semantics as C++11. See the LLVM documentation on [[atomics]].
36	//!
37	//! [atomics]: https://llvm.org/docs/Atomics.html
38	//!
39	//! A quick refresher on memory ordering:
40	//!
41	//! Acquire - a barrier for acquiring a lock. Subsequent reads and writes*
42	//! take place after the barrier.
43	//! Release - a barrier for releasing a lock. Preceding reads and writes*
44	//! take place before the barrier.
45	//! Sequentially consistent - sequentially consistent operations are*
46	//! guaranteed to happen in order. This is the standard mode for working
47	//! with atomic types and is equivalent to Java's `volatile`.
48	//!
49	//! # Unwinding
50	//!
51	//! Rust intrinsics may, in general, unwind. If an intrinsic can never unwind, add the
52	//! `#[rustc_nounwind]` attribute so that the compiler can make use of this fact.
53	//!
54	//! However, even for intrinsics that may unwind, rustc assumes that a Rust intrinsics will never
55	//! initiate a foreign (non-Rust) unwind, and thus for panic=abort we can always assume that these
56	//! intrinsics cannot unwind.
57
58	#![unstable(
59	feature = "core_intrinsics",
60	reason = "intrinsics are unlikely to ever be stabilized, instead \
61	they should be used through stabilized interfaces \
62	in the rest of the standard library",
63	issue = "none"
64	)]
65	#![allow(missing_docs)]
66
67	use crate::marker::{DiscriminantKind, Tuple};
68	use crate::mem::SizedTypeProperties;
69	use crate::{ptr, ub_checks};
70
71	pub mod fallback;
72	pub mod mir;
73	pub mod simd;
74
75	// These imports are used for simplifying intra-doc links
76	#[allow(unused_imports)]
77	#[cfg(all(target_has_atomic = "8", target_has_atomic = "32", target_has_atomic = "ptr"))]
78	use crate::sync::atomic::{self, AtomicBool, AtomicI32, AtomicIsize, AtomicU32, Ordering};
79
80	#[stable(feature = "drop_in_place", since = "1.8.0")]
81	#[rustc_allowed_through_unstable_modules = "import this function via `std::ptr` instead"]
82	#[deprecated(note = "no longer an intrinsic - use `ptr::drop_in_place` directly", since = "1.52.0")]
83	#[inline]
84	pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
85	// SAFETY: see `ptr::drop_in_place`
86	unsafe { crate::ptr::drop_in_place(to_drop) }
87	}
88
89	// N.B., these intrinsics take raw pointers because they mutate aliased
90	// memory, which is not valid for either `&` or `&mut`.
91
92	/// Stores a value if the current value is the same as the `old` value.
93	/// `T` must be an integer or pointer type.
94	///
95	/// The stabilized version of this intrinsic is available on the
96	/// [`atomic`] types via the `compare_exchange` method by passing
97	/// [`Ordering::Relaxed`] as both the success and failure parameters.
98	/// For example, [`AtomicBool::compare_exchange`].
99	#[rustc_intrinsic]
100	#[rustc_nounwind]
101	pub unsafe fn atomic_cxchg_relaxed_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
102	/// Stores a value if the current value is the same as the `old` value.
103	/// `T` must be an integer or pointer type.
104	///
105	/// The stabilized version of this intrinsic is available on the
106	/// [`atomic`] types via the `compare_exchange` method by passing
107	/// [`Ordering::Relaxed`] and [`Ordering::Acquire`] as the success and failure parameters.
108	/// For example, [`AtomicBool::compare_exchange`].
109	#[rustc_intrinsic]
110	#[rustc_nounwind]
111	pub unsafe fn atomic_cxchg_relaxed_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
112	/// Stores a value if the current value is the same as the `old` value.
113	/// `T` must be an integer or pointer type.
114	///
115	/// The stabilized version of this intrinsic is available on the
116	/// [`atomic`] types via the `compare_exchange` method by passing
117	/// [`Ordering::Relaxed`] and [`Ordering::SeqCst`] as the success and failure parameters.
118	/// For example, [`AtomicBool::compare_exchange`].
119	#[rustc_intrinsic]
120	#[rustc_nounwind]
121	pub unsafe fn atomic_cxchg_relaxed_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
122	/// Stores a value if the current value is the same as the `old` value.
123	/// `T` must be an integer or pointer type.
124	///
125	/// The stabilized version of this intrinsic is available on the
126	/// [`atomic`] types via the `compare_exchange` method by passing
127	/// [`Ordering::Acquire`] and [`Ordering::Relaxed`] as the success and failure parameters.
128	/// For example, [`AtomicBool::compare_exchange`].
129	#[rustc_intrinsic]
130	#[rustc_nounwind]
131	pub unsafe fn atomic_cxchg_acquire_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
132	/// Stores a value if the current value is the same as the `old` value.
133	/// `T` must be an integer or pointer type.
134	///
135	/// The stabilized version of this intrinsic is available on the
136	/// [`atomic`] types via the `compare_exchange` method by passing
137	/// [`Ordering::Acquire`] as both the success and failure parameters.
138	/// For example, [`AtomicBool::compare_exchange`].
139	#[rustc_intrinsic]
140	#[rustc_nounwind]
141	pub unsafe fn atomic_cxchg_acquire_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
142	/// Stores a value if the current value is the same as the `old` value.
143	/// `T` must be an integer or pointer type.
144	///
145	/// The stabilized version of this intrinsic is available on the
146	/// [`atomic`] types via the `compare_exchange` method by passing
147	/// [`Ordering::Acquire`] and [`Ordering::SeqCst`] as the success and failure parameters.
148	/// For example, [`AtomicBool::compare_exchange`].
149	#[rustc_intrinsic]
150	#[rustc_nounwind]
151	pub unsafe fn atomic_cxchg_acquire_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
152	/// Stores a value if the current value is the same as the `old` value.
153	/// `T` must be an integer or pointer type.
154	///
155	/// The stabilized version of this intrinsic is available on the
156	/// [`atomic`] types via the `compare_exchange` method by passing
157	/// [`Ordering::Release`] and [`Ordering::Relaxed`] as the success and failure parameters.
158	/// For example, [`AtomicBool::compare_exchange`].
159	#[rustc_intrinsic]
160	#[rustc_nounwind]
161	pub unsafe fn atomic_cxchg_release_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
162	/// Stores a value if the current value is the same as the `old` value.
163	/// `T` must be an integer or pointer type.
164	///
165	/// The stabilized version of this intrinsic is available on the
166	/// [`atomic`] types via the `compare_exchange` method by passing
167	/// [`Ordering::Release`] and [`Ordering::Acquire`] as the success and failure parameters.
168	/// For example, [`AtomicBool::compare_exchange`].
169	#[rustc_intrinsic]
170	#[rustc_nounwind]
171	pub unsafe fn atomic_cxchg_release_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
172	/// Stores a value if the current value is the same as the `old` value.
173	/// `T` must be an integer or pointer type.
174	///
175	/// The stabilized version of this intrinsic is available on the
176	/// [`atomic`] types via the `compare_exchange` method by passing
177	/// [`Ordering::Release`] and [`Ordering::SeqCst`] as the success and failure parameters.
178	/// For example, [`AtomicBool::compare_exchange`].
179	#[rustc_intrinsic]
180	#[rustc_nounwind]
181	pub unsafe fn atomic_cxchg_release_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
182	/// Stores a value if the current value is the same as the `old` value.
183	/// `T` must be an integer or pointer type.
184	///
185	/// The stabilized version of this intrinsic is available on the
186	/// [`atomic`] types via the `compare_exchange` method by passing
187	/// [`Ordering::AcqRel`] and [`Ordering::Relaxed`] as the success and failure parameters.
188	/// For example, [`AtomicBool::compare_exchange`].
189	#[rustc_intrinsic]
190	#[rustc_nounwind]
191	pub unsafe fn atomic_cxchg_acqrel_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
192	/// Stores a value if the current value is the same as the `old` value.
193	/// `T` must be an integer or pointer type.
194	///
195	/// The stabilized version of this intrinsic is available on the
196	/// [`atomic`] types via the `compare_exchange` method by passing
197	/// [`Ordering::AcqRel`] and [`Ordering::Acquire`] as the success and failure parameters.
198	/// For example, [`AtomicBool::compare_exchange`].
199	#[rustc_intrinsic]
200	#[rustc_nounwind]
201	pub unsafe fn atomic_cxchg_acqrel_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
202	/// Stores a value if the current value is the same as the `old` value.
203	/// `T` must be an integer or pointer type.
204	///
205	/// The stabilized version of this intrinsic is available on the
206	/// [`atomic`] types via the `compare_exchange` method by passing
207	/// [`Ordering::AcqRel`] and [`Ordering::SeqCst`] as the success and failure parameters.
208	/// For example, [`AtomicBool::compare_exchange`].
209	#[rustc_intrinsic]
210	#[rustc_nounwind]
211	pub unsafe fn atomic_cxchg_acqrel_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
212	/// Stores a value if the current value is the same as the `old` value.
213	/// `T` must be an integer or pointer type.
214	///
215	/// The stabilized version of this intrinsic is available on the
216	/// [`atomic`] types via the `compare_exchange` method by passing
217	/// [`Ordering::SeqCst`] and [`Ordering::Relaxed`] as the success and failure parameters.
218	/// For example, [`AtomicBool::compare_exchange`].
219	#[rustc_intrinsic]
220	#[rustc_nounwind]
221	pub unsafe fn atomic_cxchg_seqcst_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
222	/// Stores a value if the current value is the same as the `old` value.
223	/// `T` must be an integer or pointer type.
224	///
225	/// The stabilized version of this intrinsic is available on the
226	/// [`atomic`] types via the `compare_exchange` method by passing
227	/// [`Ordering::SeqCst`] and [`Ordering::Acquire`] as the success and failure parameters.
228	/// For example, [`AtomicBool::compare_exchange`].
229	#[rustc_intrinsic]
230	#[rustc_nounwind]
231	pub unsafe fn atomic_cxchg_seqcst_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
232	/// Stores a value if the current value is the same as the `old` value.
233	/// `T` must be an integer or pointer type.
234	///
235	/// The stabilized version of this intrinsic is available on the
236	/// [`atomic`] types via the `compare_exchange` method by passing
237	/// [`Ordering::SeqCst`] as both the success and failure parameters.
238	/// For example, [`AtomicBool::compare_exchange`].
239	#[rustc_intrinsic]
240	#[rustc_nounwind]
241	pub unsafe fn atomic_cxchg_seqcst_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
242
243	/// Stores a value if the current value is the same as the `old` value.
244	/// `T` must be an integer or pointer type.
245	///
246	/// The stabilized version of this intrinsic is available on the
247	/// [`atomic`] types via the `compare_exchange_weak` method by passing
248	/// [`Ordering::Relaxed`] as both the success and failure parameters.
249	/// For example, [`AtomicBool::compare_exchange_weak`].
250	#[rustc_intrinsic]
251	#[rustc_nounwind]
252	pub unsafe fn atomic_cxchgweak_relaxed_relaxed<T: Copy>(
253	_dst: *mut T,
254	_old: T,
255	_src: T,
256	) -> (T, bool);
257	/// Stores a value if the current value is the same as the `old` value.
258	/// `T` must be an integer or pointer type.
259	///
260	/// The stabilized version of this intrinsic is available on the
261	/// [`atomic`] types via the `compare_exchange_weak` method by passing
262	/// [`Ordering::Relaxed`] and [`Ordering::Acquire`] as the success and failure parameters.
263	/// For example, [`AtomicBool::compare_exchange_weak`].
264	#[rustc_intrinsic]
265	#[rustc_nounwind]
266	pub unsafe fn atomic_cxchgweak_relaxed_acquire<T: Copy>(
267	_dst: *mut T,
268	_old: T,
269	_src: T,
270	) -> (T, bool);
271	/// Stores a value if the current value is the same as the `old` value.
272	/// `T` must be an integer or pointer type.
273	///
274	/// The stabilized version of this intrinsic is available on the
275	/// [`atomic`] types via the `compare_exchange_weak` method by passing
276	/// [`Ordering::Relaxed`] and [`Ordering::SeqCst`] as the success and failure parameters.
277	/// For example, [`AtomicBool::compare_exchange_weak`].
278	#[rustc_intrinsic]
279	#[rustc_nounwind]
280	pub unsafe fn atomic_cxchgweak_relaxed_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
281	/// Stores a value if the current value is the same as the `old` value.
282	/// `T` must be an integer or pointer type.
283	///
284	/// The stabilized version of this intrinsic is available on the
285	/// [`atomic`] types via the `compare_exchange_weak` method by passing
286	/// [`Ordering::Acquire`] and [`Ordering::Relaxed`] as the success and failure parameters.
287	/// For example, [`AtomicBool::compare_exchange_weak`].
288	#[rustc_intrinsic]
289	#[rustc_nounwind]
290	pub unsafe fn atomic_cxchgweak_acquire_relaxed<T: Copy>(
291	_dst: *mut T,
292	_old: T,
293	_src: T,
294	) -> (T, bool);
295	/// Stores a value if the current value is the same as the `old` value.
296	/// `T` must be an integer or pointer type.
297	///
298	/// The stabilized version of this intrinsic is available on the
299	/// [`atomic`] types via the `compare_exchange_weak` method by passing
300	/// [`Ordering::Acquire`] as both the success and failure parameters.
301	/// For example, [`AtomicBool::compare_exchange_weak`].
302	#[rustc_intrinsic]
303	#[rustc_nounwind]
304	pub unsafe fn atomic_cxchgweak_acquire_acquire<T: Copy>(
305	_dst: *mut T,
306	_old: T,
307	_src: T,
308	) -> (T, bool);
309	/// Stores a value if the current value is the same as the `old` value.
310	/// `T` must be an integer or pointer type.
311	///
312	/// The stabilized version of this intrinsic is available on the
313	/// [`atomic`] types via the `compare_exchange_weak` method by passing
314	/// [`Ordering::Acquire`] and [`Ordering::SeqCst`] as the success and failure parameters.
315	/// For example, [`AtomicBool::compare_exchange_weak`].
316	#[rustc_intrinsic]
317	#[rustc_nounwind]
318	pub unsafe fn atomic_cxchgweak_acquire_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
319	/// Stores a value if the current value is the same as the `old` value.
320	/// `T` must be an integer or pointer type.
321	///
322	/// The stabilized version of this intrinsic is available on the
323	/// [`atomic`] types via the `compare_exchange_weak` method by passing
324	/// [`Ordering::Release`] and [`Ordering::Relaxed`] as the success and failure parameters.
325	/// For example, [`AtomicBool::compare_exchange_weak`].
326	#[rustc_intrinsic]
327	#[rustc_nounwind]
328	pub unsafe fn atomic_cxchgweak_release_relaxed<T: Copy>(
329	_dst: *mut T,
330	_old: T,
331	_src: T,
332	) -> (T, bool);
333	/// Stores a value if the current value is the same as the `old` value.
334	/// `T` must be an integer or pointer type.
335	///
336	/// The stabilized version of this intrinsic is available on the
337	/// [`atomic`] types via the `compare_exchange_weak` method by passing
338	/// [`Ordering::Release`] and [`Ordering::Acquire`] as the success and failure parameters.
339	/// For example, [`AtomicBool::compare_exchange_weak`].
340	#[rustc_intrinsic]
341	#[rustc_nounwind]
342	pub unsafe fn atomic_cxchgweak_release_acquire<T: Copy>(
343	_dst: *mut T,
344	_old: T,
345	_src: T,
346	) -> (T, bool);
347	/// Stores a value if the current value is the same as the `old` value.
348	/// `T` must be an integer or pointer type.
349	///
350	/// The stabilized version of this intrinsic is available on the
351	/// [`atomic`] types via the `compare_exchange_weak` method by passing
352	/// [`Ordering::Release`] and [`Ordering::SeqCst`] as the success and failure parameters.
353	/// For example, [`AtomicBool::compare_exchange_weak`].
354	#[rustc_intrinsic]
355	#[rustc_nounwind]
356	pub unsafe fn atomic_cxchgweak_release_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
357	/// Stores a value if the current value is the same as the `old` value.
358	/// `T` must be an integer or pointer type.
359	///
360	/// The stabilized version of this intrinsic is available on the
361	/// [`atomic`] types via the `compare_exchange_weak` method by passing
362	/// [`Ordering::AcqRel`] and [`Ordering::Relaxed`] as the success and failure parameters.
363	/// For example, [`AtomicBool::compare_exchange_weak`].
364	#[rustc_intrinsic]
365	#[rustc_nounwind]
366	pub unsafe fn atomic_cxchgweak_acqrel_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
367	/// Stores a value if the current value is the same as the `old` value.
368	/// `T` must be an integer or pointer type.
369	///
370	/// The stabilized version of this intrinsic is available on the
371	/// [`atomic`] types via the `compare_exchange_weak` method by passing
372	/// [`Ordering::AcqRel`] and [`Ordering::Acquire`] as the success and failure parameters.
373	/// For example, [`AtomicBool::compare_exchange_weak`].
374	#[rustc_intrinsic]
375	#[rustc_nounwind]
376	pub unsafe fn atomic_cxchgweak_acqrel_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
377	/// Stores a value if the current value is the same as the `old` value.
378	/// `T` must be an integer or pointer type.
379	///
380	/// The stabilized version of this intrinsic is available on the
381	/// [`atomic`] types via the `compare_exchange_weak` method by passing
382	/// [`Ordering::AcqRel`] and [`Ordering::SeqCst`] as the success and failure parameters.
383	/// For example, [`AtomicBool::compare_exchange_weak`].
384	#[rustc_intrinsic]
385	#[rustc_nounwind]
386	pub unsafe fn atomic_cxchgweak_acqrel_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
387	/// Stores a value if the current value is the same as the `old` value.
388	/// `T` must be an integer or pointer type.
389	///
390	/// The stabilized version of this intrinsic is available on the
391	/// [`atomic`] types via the `compare_exchange_weak` method by passing
392	/// [`Ordering::SeqCst`] and [`Ordering::Relaxed`] as the success and failure parameters.
393	/// For example, [`AtomicBool::compare_exchange_weak`].
394	#[rustc_intrinsic]
395	#[rustc_nounwind]
396	pub unsafe fn atomic_cxchgweak_seqcst_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
397	/// Stores a value if the current value is the same as the `old` value.
398	/// `T` must be an integer or pointer type.
399	///
400	/// The stabilized version of this intrinsic is available on the
401	/// [`atomic`] types via the `compare_exchange_weak` method by passing
402	/// [`Ordering::SeqCst`] and [`Ordering::Acquire`] as the success and failure parameters.
403	/// For example, [`AtomicBool::compare_exchange_weak`].
404	#[rustc_intrinsic]
405	#[rustc_nounwind]
406	pub unsafe fn atomic_cxchgweak_seqcst_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
407	/// Stores a value if the current value is the same as the `old` value.
408	/// `T` must be an integer or pointer type.
409	///
410	/// The stabilized version of this intrinsic is available on the
411	/// [`atomic`] types via the `compare_exchange_weak` method by passing
412	/// [`Ordering::SeqCst`] as both the success and failure parameters.
413	/// For example, [`AtomicBool::compare_exchange_weak`].
414	#[rustc_intrinsic]
415	#[rustc_nounwind]
416	pub unsafe fn atomic_cxchgweak_seqcst_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool);
417
418	/// Loads the current value of the pointer.
419	/// `T` must be an integer or pointer type.
420	///
421	/// The stabilized version of this intrinsic is available on the
422	/// [`atomic`] types via the `load` method by passing
423	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::load`].
424	#[rustc_intrinsic]
425	#[rustc_nounwind]
426	pub unsafe fn atomic_load_seqcst<T: Copy>(src: *const T) -> T;
427	/// Loads the current value of the pointer.
428	/// `T` must be an integer or pointer type.
429	///
430	/// The stabilized version of this intrinsic is available on the
431	/// [`atomic`] types via the `load` method by passing
432	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::load`].
433	#[rustc_intrinsic]
434	#[rustc_nounwind]
435	pub unsafe fn atomic_load_acquire<T: Copy>(src: *const T) -> T;
436	/// Loads the current value of the pointer.
437	/// `T` must be an integer or pointer type.
438	///
439	/// The stabilized version of this intrinsic is available on the
440	/// [`atomic`] types via the `load` method by passing
441	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::load`].
442	#[rustc_intrinsic]
443	#[rustc_nounwind]
444	pub unsafe fn atomic_load_relaxed<T: Copy>(src: *const T) -> T;
445	/// Do NOT use this intrinsic; "unordered" operations do not exist in our memory model!
446	/// In terms of the Rust Abstract Machine, this operation is equivalent to `src.read()`,
447	/// i.e., it performs a non-atomic read.
448	#[rustc_intrinsic]
449	#[rustc_nounwind]
450	pub unsafe fn atomic_load_unordered<T: Copy>(src: *const T) -> T;
451
452	/// Stores the value at the specified memory location.
453	/// `T` must be an integer or pointer type.
454	///
455	/// The stabilized version of this intrinsic is available on the
456	/// [`atomic`] types via the `store` method by passing
457	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::store`].
458	#[rustc_intrinsic]
459	#[rustc_nounwind]
460	pub unsafe fn atomic_store_seqcst<T: Copy>(dst: *mut T, val: T);
461	/// Stores the value at the specified memory location.
462	/// `T` must be an integer or pointer type.
463	///
464	/// The stabilized version of this intrinsic is available on the
465	/// [`atomic`] types via the `store` method by passing
466	/// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::store`].
467	#[rustc_intrinsic]
468	#[rustc_nounwind]
469	pub unsafe fn atomic_store_release<T: Copy>(dst: *mut T, val: T);
470	/// Stores the value at the specified memory location.
471	/// `T` must be an integer or pointer type.
472	///
473	/// The stabilized version of this intrinsic is available on the
474	/// [`atomic`] types via the `store` method by passing
475	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::store`].
476	#[rustc_intrinsic]
477	#[rustc_nounwind]
478	pub unsafe fn atomic_store_relaxed<T: Copy>(dst: *mut T, val: T);
479	/// Do NOT use this intrinsic; "unordered" operations do not exist in our memory model!
480	/// In terms of the Rust Abstract Machine, this operation is equivalent to `dst.write(val)`,
481	/// i.e., it performs a non-atomic write.
482	#[rustc_intrinsic]
483	#[rustc_nounwind]
484	pub unsafe fn atomic_store_unordered<T: Copy>(dst: *mut T, val: T);
485
486	/// Stores the value at the specified memory location, returning the old value.
487	/// `T` must be an integer or pointer type.
488	///
489	/// The stabilized version of this intrinsic is available on the
490	/// [`atomic`] types via the `swap` method by passing
491	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::swap`].
492	#[rustc_intrinsic]
493	#[rustc_nounwind]
494	pub unsafe fn atomic_xchg_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
495	/// Stores the value at the specified memory location, returning the old value.
496	/// `T` must be an integer or pointer type.
497	///
498	/// The stabilized version of this intrinsic is available on the
499	/// [`atomic`] types via the `swap` method by passing
500	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::swap`].
501	#[rustc_intrinsic]
502	#[rustc_nounwind]
503	pub unsafe fn atomic_xchg_acquire<T: Copy>(dst: *mut T, src: T) -> T;
504	/// Stores the value at the specified memory location, returning the old value.
505	/// `T` must be an integer or pointer type.
506	///
507	/// The stabilized version of this intrinsic is available on the
508	/// [`atomic`] types via the `swap` method by passing
509	/// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::swap`].
510	#[rustc_intrinsic]
511	#[rustc_nounwind]
512	pub unsafe fn atomic_xchg_release<T: Copy>(dst: *mut T, src: T) -> T;
513	/// Stores the value at the specified memory location, returning the old value.
514	/// `T` must be an integer or pointer type.
515	///
516	/// The stabilized version of this intrinsic is available on the
517	/// [`atomic`] types via the `swap` method by passing
518	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::swap`].
519	#[rustc_intrinsic]
520	#[rustc_nounwind]
521	pub unsafe fn atomic_xchg_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
522	/// Stores the value at the specified memory location, returning the old value.
523	/// `T` must be an integer or pointer type.
524	///
525	/// The stabilized version of this intrinsic is available on the
526	/// [`atomic`] types via the `swap` method by passing
527	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::swap`].
528	#[rustc_intrinsic]
529	#[rustc_nounwind]
530	pub unsafe fn atomic_xchg_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
531
532	/// Adds to the current value, returning the previous value.
533	/// `T` must be an integer or pointer type.
534	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
535	/// value stored at `dst` will have the provenance of the old value stored there.*
536	///
537	/// The stabilized version of this intrinsic is available on the
538	/// [`atomic`] types via the `fetch_add` method by passing
539	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicIsize::fetch_add`].
540	#[rustc_intrinsic]
541	#[rustc_nounwind]
542	pub unsafe fn atomic_xadd_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
543	/// Adds to the current value, returning the previous value.
544	/// `T` must be an integer or pointer type.
545	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
546	/// value stored at `dst` will have the provenance of the old value stored there.*
547	///
548	/// The stabilized version of this intrinsic is available on the
549	/// [`atomic`] types via the `fetch_add` method by passing
550	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicIsize::fetch_add`].
551	#[rustc_intrinsic]
552	#[rustc_nounwind]
553	pub unsafe fn atomic_xadd_acquire<T: Copy>(dst: *mut T, src: T) -> T;
554	/// Adds to the current value, returning the previous value.
555	/// `T` must be an integer or pointer type.
556	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
557	/// value stored at `dst` will have the provenance of the old value stored there.*
558	///
559	/// The stabilized version of this intrinsic is available on the
560	/// [`atomic`] types via the `fetch_add` method by passing
561	/// [`Ordering::Release`] as the `order`. For example, [`AtomicIsize::fetch_add`].
562	#[rustc_intrinsic]
563	#[rustc_nounwind]
564	pub unsafe fn atomic_xadd_release<T: Copy>(dst: *mut T, src: T) -> T;
565	/// Adds to the current value, returning the previous value.
566	/// `T` must be an integer or pointer type.
567	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
568	/// value stored at `dst` will have the provenance of the old value stored there.*
569	///
570	/// The stabilized version of this intrinsic is available on the
571	/// [`atomic`] types via the `fetch_add` method by passing
572	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicIsize::fetch_add`].
573	#[rustc_intrinsic]
574	#[rustc_nounwind]
575	pub unsafe fn atomic_xadd_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
576	/// Adds to the current value, returning the previous value.
577	/// `T` must be an integer or pointer type.
578	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
579	/// value stored at `dst` will have the provenance of the old value stored there.*
580	///
581	/// The stabilized version of this intrinsic is available on the
582	/// [`atomic`] types via the `fetch_add` method by passing
583	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicIsize::fetch_add`].
584	#[rustc_intrinsic]
585	#[rustc_nounwind]
586	pub unsafe fn atomic_xadd_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
587
588	/// Subtract from the current value, returning the previous value.
589	/// `T` must be an integer or pointer type.
590	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
591	/// value stored at `dst` will have the provenance of the old value stored there.*
592	///
593	/// The stabilized version of this intrinsic is available on the
594	/// [`atomic`] types via the `fetch_sub` method by passing
595	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicIsize::fetch_sub`].
596	#[rustc_intrinsic]
597	#[rustc_nounwind]
598	pub unsafe fn atomic_xsub_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
599	/// Subtract from the current value, returning the previous value.
600	/// `T` must be an integer or pointer type.
601	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
602	/// value stored at `dst` will have the provenance of the old value stored there.*
603	///
604	/// The stabilized version of this intrinsic is available on the
605	/// [`atomic`] types via the `fetch_sub` method by passing
606	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicIsize::fetch_sub`].
607	#[rustc_intrinsic]
608	#[rustc_nounwind]
609	pub unsafe fn atomic_xsub_acquire<T: Copy>(dst: *mut T, src: T) -> T;
610	/// Subtract from the current value, returning the previous value.
611	/// `T` must be an integer or pointer type.
612	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
613	/// value stored at `dst` will have the provenance of the old value stored there.*
614	///
615	/// The stabilized version of this intrinsic is available on the
616	/// [`atomic`] types via the `fetch_sub` method by passing
617	/// [`Ordering::Release`] as the `order`. For example, [`AtomicIsize::fetch_sub`].
618	#[rustc_intrinsic]
619	#[rustc_nounwind]
620	pub unsafe fn atomic_xsub_release<T: Copy>(dst: *mut T, src: T) -> T;
621	/// Subtract from the current value, returning the previous value.
622	/// `T` must be an integer or pointer type.
623	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
624	/// value stored at `dst` will have the provenance of the old value stored there.*
625	///
626	/// The stabilized version of this intrinsic is available on the
627	/// [`atomic`] types via the `fetch_sub` method by passing
628	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicIsize::fetch_sub`].
629	#[rustc_intrinsic]
630	#[rustc_nounwind]
631	pub unsafe fn atomic_xsub_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
632	/// Subtract from the current value, returning the previous value.
633	/// `T` must be an integer or pointer type.
634	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
635	/// value stored at `dst` will have the provenance of the old value stored there.*
636	///
637	/// The stabilized version of this intrinsic is available on the
638	/// [`atomic`] types via the `fetch_sub` method by passing
639	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicIsize::fetch_sub`].
640	#[rustc_intrinsic]
641	#[rustc_nounwind]
642	pub unsafe fn atomic_xsub_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
643
644	/// Bitwise and with the current value, returning the previous value.
645	/// `T` must be an integer or pointer type.
646	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
647	/// value stored at `dst` will have the provenance of the old value stored there.*
648	///
649	/// The stabilized version of this intrinsic is available on the
650	/// [`atomic`] types via the `fetch_and` method by passing
651	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_and`].
652	#[rustc_intrinsic]
653	#[rustc_nounwind]
654	pub unsafe fn atomic_and_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
655	/// Bitwise and with the current value, returning the previous value.
656	/// `T` must be an integer or pointer type.
657	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
658	/// value stored at `dst` will have the provenance of the old value stored there.*
659	///
660	/// The stabilized version of this intrinsic is available on the
661	/// [`atomic`] types via the `fetch_and` method by passing
662	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_and`].
663	#[rustc_intrinsic]
664	#[rustc_nounwind]
665	pub unsafe fn atomic_and_acquire<T: Copy>(dst: *mut T, src: T) -> T;
666	/// Bitwise and with the current value, returning the previous value.
667	/// `T` must be an integer or pointer type.
668	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
669	/// value stored at `dst` will have the provenance of the old value stored there.*
670	///
671	/// The stabilized version of this intrinsic is available on the
672	/// [`atomic`] types via the `fetch_and` method by passing
673	/// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_and`].
674	#[rustc_intrinsic]
675	#[rustc_nounwind]
676	pub unsafe fn atomic_and_release<T: Copy>(dst: *mut T, src: T) -> T;
677	/// Bitwise and with the current value, returning the previous value.
678	/// `T` must be an integer or pointer type.
679	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
680	/// value stored at `dst` will have the provenance of the old value stored there.*
681	///
682	/// The stabilized version of this intrinsic is available on the
683	/// [`atomic`] types via the `fetch_and` method by passing
684	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_and`].
685	#[rustc_intrinsic]
686	#[rustc_nounwind]
687	pub unsafe fn atomic_and_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
688	/// Bitwise and with the current value, returning the previous value.
689	/// `T` must be an integer or pointer type.
690	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
691	/// value stored at `dst` will have the provenance of the old value stored there.*
692	///
693	/// The stabilized version of this intrinsic is available on the
694	/// [`atomic`] types via the `fetch_and` method by passing
695	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_and`].
696	#[rustc_intrinsic]
697	#[rustc_nounwind]
698	pub unsafe fn atomic_and_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
699
700	/// Bitwise nand with the current value, returning the previous value.
701	/// `T` must be an integer or pointer type.
702	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
703	/// value stored at `dst` will have the provenance of the old value stored there.*
704	///
705	/// The stabilized version of this intrinsic is available on the
706	/// [`AtomicBool`] type via the `fetch_nand` method by passing
707	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_nand`].
708	#[rustc_intrinsic]
709	#[rustc_nounwind]
710	pub unsafe fn atomic_nand_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
711	/// Bitwise nand with the current value, returning the previous value.
712	/// `T` must be an integer or pointer type.
713	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
714	/// value stored at `dst` will have the provenance of the old value stored there.*
715	///
716	/// The stabilized version of this intrinsic is available on the
717	/// [`AtomicBool`] type via the `fetch_nand` method by passing
718	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_nand`].
719	#[rustc_intrinsic]
720	#[rustc_nounwind]
721	pub unsafe fn atomic_nand_acquire<T: Copy>(dst: *mut T, src: T) -> T;
722	/// Bitwise nand with the current value, returning the previous value.
723	/// `T` must be an integer or pointer type.
724	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
725	/// value stored at `dst` will have the provenance of the old value stored there.*
726	///
727	/// The stabilized version of this intrinsic is available on the
728	/// [`AtomicBool`] type via the `fetch_nand` method by passing
729	/// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_nand`].
730	#[rustc_intrinsic]
731	#[rustc_nounwind]
732	pub unsafe fn atomic_nand_release<T: Copy>(dst: *mut T, src: T) -> T;
733	/// Bitwise nand with the current value, returning the previous value.
734	/// `T` must be an integer or pointer type.
735	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
736	/// value stored at `dst` will have the provenance of the old value stored there.*
737	///
738	/// The stabilized version of this intrinsic is available on the
739	/// [`AtomicBool`] type via the `fetch_nand` method by passing
740	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_nand`].
741	#[rustc_intrinsic]
742	#[rustc_nounwind]
743	pub unsafe fn atomic_nand_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
744	/// Bitwise nand with the current value, returning the previous value.
745	/// `T` must be an integer or pointer type.
746	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
747	/// value stored at `dst` will have the provenance of the old value stored there.*
748	///
749	/// The stabilized version of this intrinsic is available on the
750	/// [`AtomicBool`] type via the `fetch_nand` method by passing
751	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_nand`].
752	#[rustc_intrinsic]
753	#[rustc_nounwind]
754	pub unsafe fn atomic_nand_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
755
756	/// Bitwise or with the current value, returning the previous value.
757	/// `T` must be an integer or pointer type.
758	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
759	/// value stored at `dst` will have the provenance of the old value stored there.*
760	///
761	/// The stabilized version of this intrinsic is available on the
762	/// [`atomic`] types via the `fetch_or` method by passing
763	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_or`].
764	#[rustc_intrinsic]
765	#[rustc_nounwind]
766	pub unsafe fn atomic_or_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
767	/// Bitwise or with the current value, returning the previous value.
768	/// `T` must be an integer or pointer type.
769	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
770	/// value stored at `dst` will have the provenance of the old value stored there.*
771	///
772	/// The stabilized version of this intrinsic is available on the
773	/// [`atomic`] types via the `fetch_or` method by passing
774	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_or`].
775	#[rustc_intrinsic]
776	#[rustc_nounwind]
777	pub unsafe fn atomic_or_acquire<T: Copy>(dst: *mut T, src: T) -> T;
778	/// Bitwise or with the current value, returning the previous value.
779	/// `T` must be an integer or pointer type.
780	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
781	/// value stored at `dst` will have the provenance of the old value stored there.*
782	///
783	/// The stabilized version of this intrinsic is available on the
784	/// [`atomic`] types via the `fetch_or` method by passing
785	/// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_or`].
786	#[rustc_intrinsic]
787	#[rustc_nounwind]
788	pub unsafe fn atomic_or_release<T: Copy>(dst: *mut T, src: T) -> T;
789	/// Bitwise or with the current value, returning the previous value.
790	/// `T` must be an integer or pointer type.
791	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
792	/// value stored at `dst` will have the provenance of the old value stored there.*
793	///
794	/// The stabilized version of this intrinsic is available on the
795	/// [`atomic`] types via the `fetch_or` method by passing
796	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_or`].
797	#[rustc_intrinsic]
798	#[rustc_nounwind]
799	pub unsafe fn atomic_or_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
800	/// Bitwise or with the current value, returning the previous value.
801	/// `T` must be an integer or pointer type.
802	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
803	/// value stored at `dst` will have the provenance of the old value stored there.*
804	///
805	/// The stabilized version of this intrinsic is available on the
806	/// [`atomic`] types via the `fetch_or` method by passing
807	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_or`].
808	#[rustc_intrinsic]
809	#[rustc_nounwind]
810	pub unsafe fn atomic_or_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
811
812	/// Bitwise xor with the current value, returning the previous value.
813	/// `T` must be an integer or pointer type.
814	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
815	/// value stored at `dst` will have the provenance of the old value stored there.*
816	///
817	/// The stabilized version of this intrinsic is available on the
818	/// [`atomic`] types via the `fetch_xor` method by passing
819	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_xor`].
820	#[rustc_intrinsic]
821	#[rustc_nounwind]
822	pub unsafe fn atomic_xor_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
823	/// Bitwise xor with the current value, returning the previous value.
824	/// `T` must be an integer or pointer type.
825	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
826	/// value stored at `dst` will have the provenance of the old value stored there.*
827	///
828	/// The stabilized version of this intrinsic is available on the
829	/// [`atomic`] types via the `fetch_xor` method by passing
830	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_xor`].
831	#[rustc_intrinsic]
832	#[rustc_nounwind]
833	pub unsafe fn atomic_xor_acquire<T: Copy>(dst: *mut T, src: T) -> T;
834	/// Bitwise xor with the current value, returning the previous value.
835	/// `T` must be an integer or pointer type.
836	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
837	/// value stored at `dst` will have the provenance of the old value stored there.*
838	///
839	/// The stabilized version of this intrinsic is available on the
840	/// [`atomic`] types via the `fetch_xor` method by passing
841	/// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_xor`].
842	#[rustc_intrinsic]
843	#[rustc_nounwind]
844	pub unsafe fn atomic_xor_release<T: Copy>(dst: *mut T, src: T) -> T;
845	/// Bitwise xor with the current value, returning the previous value.
846	/// `T` must be an integer or pointer type.
847	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
848	/// value stored at `dst` will have the provenance of the old value stored there.*
849	///
850	/// The stabilized version of this intrinsic is available on the
851	/// [`atomic`] types via the `fetch_xor` method by passing
852	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_xor`].
853	#[rustc_intrinsic]
854	#[rustc_nounwind]
855	pub unsafe fn atomic_xor_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
856	/// Bitwise xor with the current value, returning the previous value.
857	/// `T` must be an integer or pointer type.
858	/// If `T` is a pointer type, the provenance of `src` is ignored: both the return value and the new
859	/// value stored at `dst` will have the provenance of the old value stored there.*
860	///
861	/// The stabilized version of this intrinsic is available on the
862	/// [`atomic`] types via the `fetch_xor` method by passing
863	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_xor`].
864	#[rustc_intrinsic]
865	#[rustc_nounwind]
866	pub unsafe fn atomic_xor_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
867
868	/// Maximum with the current value using a signed comparison.
869	/// `T` must be a signed integer type.
870	///
871	/// The stabilized version of this intrinsic is available on the
872	/// [`atomic`] signed integer types via the `fetch_max` method by passing
873	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicI32::fetch_max`].
874	#[rustc_intrinsic]
875	#[rustc_nounwind]
876	pub unsafe fn atomic_max_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
877	/// Maximum with the current value using a signed comparison.
878	/// `T` must be a signed integer type.
879	///
880	/// The stabilized version of this intrinsic is available on the
881	/// [`atomic`] signed integer types via the `fetch_max` method by passing
882	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicI32::fetch_max`].
883	#[rustc_intrinsic]
884	#[rustc_nounwind]
885	pub unsafe fn atomic_max_acquire<T: Copy>(dst: *mut T, src: T) -> T;
886	/// Maximum with the current value using a signed comparison.
887	/// `T` must be a signed integer type.
888	///
889	/// The stabilized version of this intrinsic is available on the
890	/// [`atomic`] signed integer types via the `fetch_max` method by passing
891	/// [`Ordering::Release`] as the `order`. For example, [`AtomicI32::fetch_max`].
892	#[rustc_intrinsic]
893	#[rustc_nounwind]
894	pub unsafe fn atomic_max_release<T: Copy>(dst: *mut T, src: T) -> T;
895	/// Maximum with the current value using a signed comparison.
896	/// `T` must be a signed integer type.
897	///
898	/// The stabilized version of this intrinsic is available on the
899	/// [`atomic`] signed integer types via the `fetch_max` method by passing
900	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicI32::fetch_max`].
901	#[rustc_intrinsic]
902	#[rustc_nounwind]
903	pub unsafe fn atomic_max_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
904	/// Maximum with the current value using a signed comparison.
905	/// `T` must be a signed integer type.
906	///
907	/// The stabilized version of this intrinsic is available on the
908	/// [`atomic`] signed integer types via the `fetch_max` method by passing
909	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicI32::fetch_max`].
910	#[rustc_intrinsic]
911	#[rustc_nounwind]
912	pub unsafe fn atomic_max_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
913
914	/// Minimum with the current value using a signed comparison.
915	/// `T` must be a signed integer type.
916	///
917	/// The stabilized version of this intrinsic is available on the
918	/// [`atomic`] signed integer types via the `fetch_min` method by passing
919	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicI32::fetch_min`].
920	#[rustc_intrinsic]
921	#[rustc_nounwind]
922	pub unsafe fn atomic_min_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
923	/// Minimum with the current value using a signed comparison.
924	/// `T` must be a signed integer type.
925	///
926	/// The stabilized version of this intrinsic is available on the
927	/// [`atomic`] signed integer types via the `fetch_min` method by passing
928	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicI32::fetch_min`].
929	#[rustc_intrinsic]
930	#[rustc_nounwind]
931	pub unsafe fn atomic_min_acquire<T: Copy>(dst: *mut T, src: T) -> T;
932	/// Minimum with the current value using a signed comparison.
933	/// `T` must be a signed integer type.
934	///
935	/// The stabilized version of this intrinsic is available on the
936	/// [`atomic`] signed integer types via the `fetch_min` method by passing
937	/// [`Ordering::Release`] as the `order`. For example, [`AtomicI32::fetch_min`].
938	#[rustc_intrinsic]
939	#[rustc_nounwind]
940	pub unsafe fn atomic_min_release<T: Copy>(dst: *mut T, src: T) -> T;
941	/// Minimum with the current value using a signed comparison.
942	/// `T` must be a signed integer type.
943	///
944	/// The stabilized version of this intrinsic is available on the
945	/// [`atomic`] signed integer types via the `fetch_min` method by passing
946	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicI32::fetch_min`].
947	#[rustc_intrinsic]
948	#[rustc_nounwind]
949	pub unsafe fn atomic_min_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
950	/// Minimum with the current value using a signed comparison.
951	/// `T` must be a signed integer type.
952	///
953	/// The stabilized version of this intrinsic is available on the
954	/// [`atomic`] signed integer types via the `fetch_min` method by passing
955	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicI32::fetch_min`].
956	#[rustc_intrinsic]
957	#[rustc_nounwind]
958	pub unsafe fn atomic_min_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
959
960	/// Minimum with the current value using an unsigned comparison.
961	/// `T` must be an unsigned integer type.
962	///
963	/// The stabilized version of this intrinsic is available on the
964	/// [`atomic`] unsigned integer types via the `fetch_min` method by passing
965	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicU32::fetch_min`].
966	#[rustc_intrinsic]
967	#[rustc_nounwind]
968	pub unsafe fn atomic_umin_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
969	/// Minimum with the current value using an unsigned comparison.
970	/// `T` must be an unsigned integer type.
971	///
972	/// The stabilized version of this intrinsic is available on the
973	/// [`atomic`] unsigned integer types via the `fetch_min` method by passing
974	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicU32::fetch_min`].
975	#[rustc_intrinsic]
976	#[rustc_nounwind]
977	pub unsafe fn atomic_umin_acquire<T: Copy>(dst: *mut T, src: T) -> T;
978	/// Minimum with the current value using an unsigned comparison.
979	/// `T` must be an unsigned integer type.
980	///
981	/// The stabilized version of this intrinsic is available on the
982	/// [`atomic`] unsigned integer types via the `fetch_min` method by passing
983	/// [`Ordering::Release`] as the `order`. For example, [`AtomicU32::fetch_min`].
984	#[rustc_intrinsic]
985	#[rustc_nounwind]
986	pub unsafe fn atomic_umin_release<T: Copy>(dst: *mut T, src: T) -> T;
987	/// Minimum with the current value using an unsigned comparison.
988	/// `T` must be an unsigned integer type.
989	///
990	/// The stabilized version of this intrinsic is available on the
991	/// [`atomic`] unsigned integer types via the `fetch_min` method by passing
992	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicU32::fetch_min`].
993	#[rustc_intrinsic]
994	#[rustc_nounwind]
995	pub unsafe fn atomic_umin_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
996	/// Minimum with the current value using an unsigned comparison.
997	/// `T` must be an unsigned integer type.
998	///
999	/// The stabilized version of this intrinsic is available on the
1000	/// [`atomic`] unsigned integer types via the `fetch_min` method by passing
1001	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicU32::fetch_min`].
1002	#[rustc_intrinsic]
1003	#[rustc_nounwind]
1004	pub unsafe fn atomic_umin_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
1005
1006	/// Maximum with the current value using an unsigned comparison.
1007	/// `T` must be an unsigned integer type.
1008	///
1009	/// The stabilized version of this intrinsic is available on the
1010	/// [`atomic`] unsigned integer types via the `fetch_max` method by passing
1011	/// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicU32::fetch_max`].
1012	#[rustc_intrinsic]
1013	#[rustc_nounwind]
1014	pub unsafe fn atomic_umax_seqcst<T: Copy>(dst: *mut T, src: T) -> T;
1015	/// Maximum with the current value using an unsigned comparison.
1016	/// `T` must be an unsigned integer type.
1017	///
1018	/// The stabilized version of this intrinsic is available on the
1019	/// [`atomic`] unsigned integer types via the `fetch_max` method by passing
1020	/// [`Ordering::Acquire`] as the `order`. For example, [`AtomicU32::fetch_max`].
1021	#[rustc_intrinsic]
1022	#[rustc_nounwind]
1023	pub unsafe fn atomic_umax_acquire<T: Copy>(dst: *mut T, src: T) -> T;
1024	/// Maximum with the current value using an unsigned comparison.
1025	/// `T` must be an unsigned integer type.
1026	///
1027	/// The stabilized version of this intrinsic is available on the
1028	/// [`atomic`] unsigned integer types via the `fetch_max` method by passing
1029	/// [`Ordering::Release`] as the `order`. For example, [`AtomicU32::fetch_max`].
1030	#[rustc_intrinsic]
1031	#[rustc_nounwind]
1032	pub unsafe fn atomic_umax_release<T: Copy>(dst: *mut T, src: T) -> T;
1033	/// Maximum with the current value using an unsigned comparison.
1034	/// `T` must be an unsigned integer type.
1035	///
1036	/// The stabilized version of this intrinsic is available on the
1037	/// [`atomic`] unsigned integer types via the `fetch_max` method by passing
1038	/// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicU32::fetch_max`].
1039	#[rustc_intrinsic]
1040	#[rustc_nounwind]
1041	pub unsafe fn atomic_umax_acqrel<T: Copy>(dst: *mut T, src: T) -> T;
1042	/// Maximum with the current value using an unsigned comparison.
1043	/// `T` must be an unsigned integer type.
1044	///
1045	/// The stabilized version of this intrinsic is available on the
1046	/// [`atomic`] unsigned integer types via the `fetch_max` method by passing
1047	/// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicU32::fetch_max`].
1048	#[rustc_intrinsic]
1049	#[rustc_nounwind]
1050	pub unsafe fn atomic_umax_relaxed<T: Copy>(dst: *mut T, src: T) -> T;
1051
1052	/// An atomic fence.
1053	///
1054	/// The stabilized version of this intrinsic is available in
1055	/// [`atomic::fence`] by passing [`Ordering::SeqCst`]
1056	/// as the `order`.
1057	#[rustc_intrinsic]
1058	#[rustc_nounwind]
1059	pub unsafe fn atomic_fence_seqcst();
1060	/// An atomic fence.
1061	///
1062	/// The stabilized version of this intrinsic is available in
1063	/// [`atomic::fence`] by passing [`Ordering::Acquire`]
1064	/// as the `order`.
1065	#[rustc_intrinsic]
1066	#[rustc_nounwind]
1067	pub unsafe fn atomic_fence_acquire();
1068	/// An atomic fence.
1069	///
1070	/// The stabilized version of this intrinsic is available in
1071	/// [`atomic::fence`] by passing [`Ordering::Release`]
1072	/// as the `order`.
1073	#[rustc_intrinsic]
1074	#[rustc_nounwind]
1075	pub unsafe fn atomic_fence_release();
1076	/// An atomic fence.
1077	///
1078	/// The stabilized version of this intrinsic is available in
1079	/// [`atomic::fence`] by passing [`Ordering::AcqRel`]
1080	/// as the `order`.
1081	#[rustc_intrinsic]
1082	#[rustc_nounwind]
1083	pub unsafe fn atomic_fence_acqrel();
1084
1085	/// A compiler-only memory barrier.
1086	///
1087	/// Memory accesses will never be reordered across this barrier by the
1088	/// compiler, but no instructions will be emitted for it. This is
1089	/// appropriate for operations on the same thread that may be preempted,
1090	/// such as when interacting with signal handlers.
1091	///
1092	/// The stabilized version of this intrinsic is available in
1093	/// [`atomic::compiler_fence`] by passing [`Ordering::SeqCst`]
1094	/// as the `order`.
1095	#[rustc_intrinsic]
1096	#[rustc_nounwind]
1097	pub unsafe fn atomic_singlethreadfence_seqcst();
1098	/// A compiler-only memory barrier.
1099	///
1100	/// Memory accesses will never be reordered across this barrier by the
1101	/// compiler, but no instructions will be emitted for it. This is
1102	/// appropriate for operations on the same thread that may be preempted,
1103	/// such as when interacting with signal handlers.
1104	///
1105	/// The stabilized version of this intrinsic is available in
1106	/// [`atomic::compiler_fence`] by passing [`Ordering::Acquire`]
1107	/// as the `order`.
1108	#[rustc_intrinsic]
1109	#[rustc_nounwind]
1110	pub unsafe fn atomic_singlethreadfence_acquire();
1111	/// A compiler-only memory barrier.
1112	///
1113	/// Memory accesses will never be reordered across this barrier by the
1114	/// compiler, but no instructions will be emitted for it. This is
1115	/// appropriate for operations on the same thread that may be preempted,
1116	/// such as when interacting with signal handlers.
1117	///
1118	/// The stabilized version of this intrinsic is available in
1119	/// [`atomic::compiler_fence`] by passing [`Ordering::Release`]
1120	/// as the `order`.
1121	#[rustc_intrinsic]
1122	#[rustc_nounwind]
1123	pub unsafe fn atomic_singlethreadfence_release();
1124	/// A compiler-only memory barrier.
1125	///
1126	/// Memory accesses will never be reordered across this barrier by the
1127	/// compiler, but no instructions will be emitted for it. This is
1128	/// appropriate for operations on the same thread that may be preempted,
1129	/// such as when interacting with signal handlers.
1130	///
1131	/// The stabilized version of this intrinsic is available in
1132	/// [`atomic::compiler_fence`] by passing [`Ordering::AcqRel`]
1133	/// as the `order`.
1134	#[rustc_intrinsic]
1135	#[rustc_nounwind]
1136	pub unsafe fn atomic_singlethreadfence_acqrel();
1137
1138	/// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction
1139	/// if supported; otherwise, it is a no-op.
1140	/// Prefetches have no effect on the behavior of the program but can change its performance
1141	/// characteristics.
1142	///
1143	/// The `locality` argument must be a constant integer and is a temporal locality specifier
1144	/// ranging from (0) - no locality, to (3) - extremely local keep in cache.
1145	///
1146	/// This intrinsic does not have a stable counterpart.
1147	#[rustc_intrinsic]
1148	#[rustc_nounwind]
1149	pub unsafe fn prefetch_read_data<T>(data: *const T, locality: i32);
1150	/// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction
1151	/// if supported; otherwise, it is a no-op.
1152	/// Prefetches have no effect on the behavior of the program but can change its performance
1153	/// characteristics.
1154	///
1155	/// The `locality` argument must be a constant integer and is a temporal locality specifier
1156	/// ranging from (0) - no locality, to (3) - extremely local keep in cache.
1157	///
1158	/// This intrinsic does not have a stable counterpart.
1159	#[rustc_intrinsic]
1160	#[rustc_nounwind]
1161	pub unsafe fn prefetch_write_data<T>(data: *const T, locality: i32);
1162	/// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction
1163	/// if supported; otherwise, it is a no-op.
1164	/// Prefetches have no effect on the behavior of the program but can change its performance
1165	/// characteristics.
1166	///
1167	/// The `locality` argument must be a constant integer and is a temporal locality specifier
1168	/// ranging from (0) - no locality, to (3) - extremely local keep in cache.
1169	///
1170	/// This intrinsic does not have a stable counterpart.
1171	#[rustc_intrinsic]
1172	#[rustc_nounwind]
1173	pub unsafe fn prefetch_read_instruction<T>(data: *const T, locality: i32);
1174	/// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction
1175	/// if supported; otherwise, it is a no-op.
1176	/// Prefetches have no effect on the behavior of the program but can change its performance
1177	/// characteristics.
1178	///
1179	/// The `locality` argument must be a constant integer and is a temporal locality specifier
1180	/// ranging from (0) - no locality, to (3) - extremely local keep in cache.
1181	///
1182	/// This intrinsic does not have a stable counterpart.
1183	#[rustc_intrinsic]
1184	#[rustc_nounwind]
1185	pub unsafe fn prefetch_write_instruction<T>(data: *const T, locality: i32);
1186
1187	/// Executes a breakpoint trap, for inspection by a debugger.
1188	///
1189	/// This intrinsic does not have a stable counterpart.
1190	#[rustc_intrinsic]
1191	#[rustc_nounwind]
1192	pub fn breakpoint();
1193
1194	/// Magic intrinsic that derives its meaning from attributes
1195	/// attached to the function.
1196	///
1197	/// For example, dataflow uses this to inject static assertions so
1198	/// that `rustc_peek(potentially_uninitialized)` would actually
1199	/// double-check that dataflow did indeed compute that it is
1200	/// uninitialized at that point in the control flow.
1201	///
1202	/// This intrinsic should not be used outside of the compiler.
1203	#[rustc_nounwind]
1204	#[rustc_intrinsic]
1205	pub fn rustc_peek<T>(_: T) -> T;
1206
1207	/// Aborts the execution of the process.
1208	///
1209	/// Note that, unlike most intrinsics, this is safe to call;
1210	/// it does not require an `unsafe` block.
1211	/// Therefore, implementations must not require the user to uphold
1212	/// any safety invariants.
1213	///
1214	/// [`std::process::abort`](../../std/process/fn.abort.html) is to be preferred if possible,
1215	/// as its behavior is more user-friendly and more stable.
1216	///
1217	/// The current implementation of `intrinsics::abort` is to invoke an invalid instruction,
1218	/// on most platforms.
1219	/// On Unix, the
1220	/// process will probably terminate with a signal like `SIGABRT`, `SIGILL`, `SIGTRAP`, `SIGSEGV` or
1221	/// `SIGBUS`. The precise behavior is not guaranteed and not stable.
1222	#[rustc_nounwind]
1223	#[rustc_intrinsic]
1224	pub fn abort() -> !;
1225
1226	/// Informs the optimizer that this point in the code is not reachable,
1227	/// enabling further optimizations.
1228	///
1229	/// N.B., this is very different from the `unreachable!()` macro: Unlike the
1230	/// macro, which panics when it is executed, it is undefined behavior* to*
1231	/// reach code marked with this function.
1232	///
1233	/// The stabilized version of this intrinsic is [`core::hint::unreachable_unchecked`].
1234	#[rustc_intrinsic_const_stable_indirect]
1235	#[rustc_nounwind]
1236	#[rustc_intrinsic]
1237	pub const unsafe fn unreachable() -> !;
1238
1239	/// Informs the optimizer that a condition is always true.
1240	/// If the condition is false, the behavior is undefined.
1241	///
1242	/// No code is generated for this intrinsic, but the optimizer will try
1243	/// to preserve it (and its condition) between passes, which may interfere
1244	/// with optimization of surrounding code and reduce performance. It should
1245	/// not be used if the invariant can be discovered by the optimizer on its
1246	/// own, or if it does not enable any significant optimizations.
1247	///
1248	/// The stabilized version of this intrinsic is [`core::hint::assert_unchecked`].
1249	#[rustc_intrinsic_const_stable_indirect]
1250	#[rustc_nounwind]
1251	#[unstable(feature = "core_intrinsics", issue = "none")]
1252	#[rustc_intrinsic]
1253	pub const unsafe fn assume(b: bool) {
1254	if !b {
1255	// SAFETY: the caller must guarantee the argument is never `false`
1256	unsafe { unreachable() }
1257	}
1258	}
1259
1260	/// Hints to the compiler that current code path is cold.
1261	///
1262	/// Note that, unlike most intrinsics, this is safe to call;
1263	/// it does not require an `unsafe` block.
1264	/// Therefore, implementations must not require the user to uphold
1265	/// any safety invariants.
1266	///
1267	/// This intrinsic does not have a stable counterpart.
1268	#[unstable(feature = "core_intrinsics", issue = "none")]
1269	#[rustc_intrinsic]
1270	#[rustc_nounwind]
1271	#[miri::intrinsic_fallback_is_spec]
1272	#[cold]
1273	pub const fn cold_path() {}
1274
1275	/// Hints to the compiler that branch condition is likely to be true.
1276	/// Returns the value passed to it.
1277	///
1278	/// Any use other than with `if` statements will probably not have an effect.
1279	///
1280	/// Note that, unlike most intrinsics, this is safe to call;
1281	/// it does not require an `unsafe` block.
1282	/// Therefore, implementations must not require the user to uphold
1283	/// any safety invariants.
1284	///
1285	/// This intrinsic does not have a stable counterpart.
1286	#[unstable(feature = "core_intrinsics", issue = "none")]
1287	#[rustc_nounwind]
1288	#[inline(always)]
1289	pub const fn likely(b: bool) -> bool {
1290	if b {
1291	`true`
1292	} else {
1293	cold_path();
1294	`false`
1295	}
1296	}
1297
1298	/// Hints to the compiler that branch condition is likely to be false.
1299	/// Returns the value passed to it.
1300	///
1301	/// Any use other than with `if` statements will probably not have an effect.
1302	///
1303	/// Note that, unlike most intrinsics, this is safe to call;
1304	/// it does not require an `unsafe` block.
1305	/// Therefore, implementations must not require the user to uphold
1306	/// any safety invariants.
1307	///
1308	/// This intrinsic does not have a stable counterpart.
1309	#[unstable(feature = "core_intrinsics", issue = "none")]
1310	#[rustc_nounwind]
1311	#[inline(always)]
1312	pub const fn unlikely(b: bool) -> bool {
1313	if b {
1314	cold_path();
1315	`true`
1316	} else {
1317	`false`
1318	}
1319	}
1320
1321	/// Returns either `true_val` or `false_val` depending on condition `b` with a
1322	/// hint to the compiler that this condition is unlikely to be correctly
1323	/// predicted by a CPU's branch predictor (e.g. a binary search).
1324	///
1325	/// This is otherwise functionally equivalent to `if b { true_val } else { false_val }`.
1326	///
1327	/// Note that, unlike most intrinsics, this is safe to call;
1328	/// it does not require an `unsafe` block.
1329	/// Therefore, implementations must not require the user to uphold
1330	/// any safety invariants.
1331	///
1332	/// The public form of this instrinsic is [`bool::select_unpredictable`].
1333	#[unstable(feature = "core_intrinsics", issue = "none")]
1334	#[rustc_intrinsic]
1335	#[rustc_nounwind]
1336	#[miri::intrinsic_fallback_is_spec]
1337	#[inline]
1338	pub fn select_unpredictable<T>(b: bool, true_val: T, false_val: T) -> T {
1339	if b { true_val } else { false_val }
1340	}
1341
1342	/// A guard for unsafe functions that cannot ever be executed if `T` is uninhabited:
1343	/// This will statically either panic, or do nothing.
1344	///
1345	/// This intrinsic does not have a stable counterpart.
1346	#[rustc_intrinsic_const_stable_indirect]
1347	#[rustc_nounwind]
1348	#[rustc_intrinsic]
1349	pub const fn assert_inhabited<T>();
1350
1351	/// A guard for unsafe functions that cannot ever be executed if `T` does not permit
1352	/// zero-initialization: This will statically either panic, or do nothing.
1353	///
1354	/// This intrinsic does not have a stable counterpart.
1355	#[rustc_intrinsic_const_stable_indirect]
1356	#[rustc_nounwind]
1357	#[rustc_intrinsic]
1358	pub const fn assert_zero_valid<T>();
1359
1360	/// A guard for `std::mem::uninitialized`. This will statically either panic, or do nothing.
1361	///
1362	/// This intrinsic does not have a stable counterpart.
1363	#[rustc_intrinsic_const_stable_indirect]
1364	#[rustc_nounwind]
1365	#[rustc_intrinsic]
1366	pub const fn assert_mem_uninitialized_valid<T>();
1367
1368	/// Gets a reference to a static `Location` indicating where it was called.
1369	///
1370	/// Note that, unlike most intrinsics, this is safe to call;
1371	/// it does not require an `unsafe` block.
1372	/// Therefore, implementations must not require the user to uphold
1373	/// any safety invariants.
1374	///
1375	/// Consider using [`core::panic::Location::caller`] instead.
1376	#[rustc_intrinsic_const_stable_indirect]
1377	#[rustc_nounwind]
1378	#[rustc_intrinsic]
1379	pub const fn caller_location() -> &'static crate::panic::Location<'static>;
1380
1381	/// Moves a value out of scope without running drop glue.
1382	///
1383	/// This exists solely for [`crate::mem::forget_unsized`]; normal `forget` uses
1384	/// `ManuallyDrop` instead.
1385	///
1386	/// Note that, unlike most intrinsics, this is safe to call;
1387	/// it does not require an `unsafe` block.
1388	/// Therefore, implementations must not require the user to uphold
1389	/// any safety invariants.
1390	#[rustc_intrinsic_const_stable_indirect]
1391	#[rustc_nounwind]
1392	#[rustc_intrinsic]
1393	pub const fn forget<T: ?Sized>(_: T);
1394
1395	/// Reinterprets the bits of a value of one type as another type.
1396	///
1397	/// Both types must have the same size. Compilation will fail if this is not guaranteed.
1398	///
1399	/// `transmute` is semantically equivalent to a bitwise move of one type
1400	/// into another. It copies the bits from the source value into the
1401	/// destination value, then forgets the original. Note that source and destination
1402	/// are passed by-value, which means if `Src` or `Dst` contain padding, that padding
1403	/// is not* guaranteed to be preserved by `transmute`.*
1404	///
1405	/// Both the argument and the result must be [valid](../../nomicon/what-unsafe-does.html) at
1406	/// their given type. Violating this condition leads to [undefined behavior][ub]. The compiler
1407	/// will generate code assuming that you, the programmer, ensure that there will never be*
1408	/// undefined behavior. It is therefore your responsibility to guarantee that every value*
1409	/// passed to `transmute` is valid at both types `Src` and `Dst`. Failing to uphold this condition
1410	/// may lead to unexpected and unstable compilation results. This makes `transmute` incredibly
1411	/// unsafe. `transmute` should be the absolute last resort.
1412	///
1413	/// Because `transmute` is a by-value operation, alignment of the transmuted values*
1414	/// themselves is not a concern. As with any other function, the compiler already ensures*
1415	/// both `Src` and `Dst` are properly aligned. However, when transmuting values that point*
1416	/// elsewhere (such as pointers, references, boxes…), the caller has to ensure proper*
1417	/// alignment of the pointed-to values.
1418	///
1419	/// The [nomicon](../../nomicon/transmutes.html) has additional documentation.
1420	///
1421	/// [ub]: ../../reference/behavior-considered-undefined.html
1422	///
1423	/// # Transmutation between pointers and integers
1424	///
1425	/// Special care has to be taken when transmuting between pointers and integers, e.g.
1426	/// transmuting between `const ()` and `usize`.*
1427	///
1428	/// Transmuting pointers to integers* in a `const` context is [undefined behavior][ub], unless*
1429	/// the pointer was originally created from* an integer. (That includes this function*
1430	/// specifically, integer-to-pointer casts, and helpers like [`dangling`][crate::ptr::dangling],
1431	/// but also semantically-equivalent conversions such as punning through `repr(C)` union
1432	/// fields.) Any attempt to use the resulting value for integer operations will abort
1433	/// const-evaluation. (And even outside `const`, such transmutation is touching on many
1434	/// unspecified aspects of the Rust memory model and should be avoided. See below for
1435	/// alternatives.)
1436	///
1437	/// Transmuting integers to pointers is a largely unspecified operation. It is likely not
1438	/// equivalent to an `as` cast. Doing non-zero-sized memory accesses with a pointer constructed
1439	/// this way is currently considered undefined behavior.
1440	///
1441	/// All this also applies when the integer is nested inside an array, tuple, struct, or enum.
1442	/// However, `MaybeUninit<usize>` is not considered an integer type for the purpose of this
1443	/// section. Transmuting `const ()` to `MaybeUninit<usize>` is fine---but then calling*
1444	/// `assume_init()` on that result is considered as completing the pointer-to-integer transmute
1445	/// and thus runs into the issues discussed above.
1446	///
1447	/// In particular, doing a pointer-to-integer-to-pointer roundtrip via `transmute` is not* a*
1448	/// lossless process. If you want to round-trip a pointer through an integer in a way that you
1449	/// can get back the original pointer, you need to use `as` casts, or replace the integer type
1450	/// by `MaybeUninit<$int>` (and never call `assume_init()`). If you are looking for a way to
1451	/// store data of arbitrary type, also use `MaybeUninit<T>` (that will also handle uninitialized
1452	/// memory due to padding). If you specifically need to store something that is "either an
1453	/// integer or a pointer", use `mut ()`: integers can be converted to pointers and back without*
1454	/// any loss (via `as` casts or via `transmute`).
1455	///
1456	/// # Examples
1457	///
1458	/// There are a few things that `transmute` is really useful for.
1459	///
1460	/// Turning a pointer into a function pointer. This is not* portable to*
1461	/// machines where function pointers and data pointers have different sizes.
1462	///
1463	/// ```
1464	/// fn foo() -> i32 {
1465	/// `0`
1466	/// }
1467	/// // Crucially, we `as`-cast to a raw pointer before `transmute`ing to a function pointer.
1468	/// // This avoids an integer-to-pointer `transmute`, which can be problematic.
1469	/// // Transmuting between raw pointers and function pointers (i.e., two pointer types) is fine.
1470	/// let pointer = foo as *const ();
1471	/// let function = unsafe {
1472	/// std::mem::transmute::<*const (), fn() -> i32>(pointer)
1473	/// };
1474	/// assert_eq!(function(), `0`);
1475	/// ```
1476	///
1477	/// Extending a lifetime, or shortening an invariant lifetime. This is
1478	/// advanced, very unsafe Rust!
1479	///
1480	/// ```
1481	/// struct R<'a>(&'a i32);
1482	/// unsafe fn extend_lifetime<'b>(r: R<'b>) -> R<'static> {
1483	/// unsafe { std::mem::transmute::<R<'b>, R<'static>>(r) }
1484	/// }
1485	///
1486	/// unsafe fn shorten_invariant_lifetime<'b, 'c>(r: &'b mut R<'static>)
1487	/// -> &'b mut R<'c> {
1488	/// unsafe { std::mem::transmute::<&'b mut R<'static>, &'b mut R<'c>>(r) }
1489	/// }
1490	/// ```
1491	///
1492	/// # Alternatives
1493	///
1494	/// Don't despair: many uses of `transmute` can be achieved through other means.
1495	/// Below are common applications of `transmute` which can be replaced with safer
1496	/// constructs.
1497	///
1498	/// Turning raw bytes (`[u8; SZ]`) into `u32`, `f64`, etc.:
1499	///
1500	/// ```
1501	/// let raw_bytes = [`0x78`, `0x56`, `0x34`, `0x12`];
1502	///
1503	/// let num = unsafe {
1504	/// std::mem::transmute::<[u8; `4`], u32>(raw_bytes)
1505	/// };
1506	///
1507	/// // use `u32::from_ne_bytes` instead
1508	/// let num = u32::from_ne_bytes(raw_bytes);
1509	/// // or use `u32::from_le_bytes` or `u32::from_be_bytes` to specify the endianness
1510	/// let num = u32::from_le_bytes(raw_bytes);
1511	/// assert_eq!(num, `0x12345678`);
1512	/// let num = u32::from_be_bytes(raw_bytes);
1513	/// assert_eq!(num, `0x78563412`);
1514	/// ```
1515	///
1516	/// Turning a pointer into a `usize`:
1517	///
1518	/// ```no_run
1519	/// let ptr = &`0`;
1520	/// let ptr_num_transmute = unsafe {
1521	/// std::mem::transmute::<&i32, usize>(ptr)
1522	/// };
1523	///
1524	/// // Use an `as` cast instead
1525	/// let ptr_num_cast = ptr as *const i32 as usize;
1526	/// ```
1527	///
1528	/// Note that using `transmute` to turn a pointer to a `usize` is (as noted above) [undefined
1529	/// behavior][ub] in `const` contexts. Also outside of consts, this operation might not behave
1530	/// as expected -- this is touching on many unspecified aspects of the Rust memory model.
1531	/// Depending on what the code is doing, the following alternatives are preferable to
1532	/// pointer-to-integer transmutation:
1533	/// - If the code just wants to store data of arbitrary type in some buffer and needs to pick a
1534	/// type for that buffer, it can use [`MaybeUninit`][crate::mem::MaybeUninit].
1535	/// - If the code actually wants to work on the address the pointer points to, it can use `as`
1536	/// casts or [`ptr.addr()`][pointer::addr].
1537	///
1538	/// Turning a `mut T` into a `&mut T`:*
1539	///
1540	/// ```
1541	/// let ptr: *mut i32 = &mut `0`;
1542	/// let ref_transmuted = unsafe {
1543	/// std::mem::transmute::<*mut i32, &mut i32>(ptr)
1544	/// };
1545	///
1546	/// // Use a reborrow instead
1547	/// let ref_casted = unsafe { &mut *ptr };
1548	/// ```
1549	///
1550	/// Turning a `&mut T` into a `&mut U`:
1551	///
1552	/// ```
1553	/// let ptr = &mut `0`;
1554	/// let val_transmuted = unsafe {
1555	/// std::mem::transmute::<&mut i32, &mut u32>(ptr)
1556	/// };
1557	///
1558	/// // Now, put together `as` and reborrowing - note the chaining of `as`
1559	/// // `as` is not transitive
1560	/// let val_casts = unsafe { &mut (ptr as mut i32 as *mut u32) };
1561	/// ```
1562	///
1563	/// Turning a `&str` into a `&[u8]`:
1564	///
1565	/// ```
1566	/// // this is not a good way to do this.
1567	/// let slice = unsafe { std::mem::transmute::<&str, &[u8]>("Rust") };
1568	/// assert_eq!(slice, &[`82`, `117`, `115`, `116`]);
1569	///
1570	/// // You could use `str::as_bytes`
1571	/// let slice = "Rust".as_bytes();
1572	/// assert_eq!(slice, &[`82`, `117`, `115`, `116`]);
1573	///
1574	/// // Or, just use a byte string, if you have control over the string
1575	/// // literal
1576	/// assert_eq!(b"Rust", &[`82`, `117`, `115`, `116`]);
1577	/// ```
1578	///
1579	/// Turning a `Vec<&T>` into a `Vec<Option<&T>>`.
1580	///
1581	/// To transmute the inner type of the contents of a container, you must make sure to not
1582	/// violate any of the container's invariants. For `Vec`, this means that both the size
1583	/// and alignment* of the inner types have to match. Other containers might rely on the*
1584	/// size of the type, alignment, or even the `TypeId`, in which case transmuting wouldn't
1585	/// be possible at all without violating the container invariants.
1586	///
1587	/// ```
1588	/// let store = [`0`, `1`, `2`, `3`];
1589	/// let v_orig = store.iter().collect::<Vec<&i32>>();
1590	///
1591	/// // clone the vector as we will reuse them later
1592	/// let v_clone = v_orig.clone();
1593	///
1594	/// // Using transmute: this relies on the unspecified data layout of `Vec`, which is a
1595	/// // bad idea and could cause Undefined Behavior.
1596	/// // However, it is no-copy.
1597	/// let v_transmuted = unsafe {
1598	/// std::mem::transmute::<Vec<&i32>, Vec<Option<&i32>>>(v_clone)
1599	/// };
1600	///
1601	/// let v_clone = v_orig.clone();
1602	///
1603	/// // This is the suggested, safe way.
1604	/// // It may copy the entire vector into a new one though, but also may not.
1605	/// let v_collected = v_clone.into_iter()
1606	/// .map(Some)
1607	/// .collect::<Vec<Option<&i32>>>();
1608	///
1609	/// let v_clone = v_orig.clone();
1610	///
1611	/// // This is the proper no-copy, unsafe way of "transmuting" a `Vec`, without relying on the
1612	/// // data layout. Instead of literally calling `transmute`, we perform a pointer cast, but
1613	/// // in terms of converting the original inner type (`&i32`) to the new one (`Option<&i32>`),
1614	/// // this has all the same caveats. Besides the information provided above, also consult the
1615	/// // [`from_raw_parts`] documentation.
1616	/// let v_from_raw = unsafe {
1617	// FIXME Update this when vec_into_raw_parts is stabilized
1618	/// // Ensure the original vector is not dropped.
1619	/// let mut v_clone = std::mem::ManuallyDrop::new(v_clone);
1620	/// Vec::from_raw_parts(v_clone.as_mut_ptr() as *mut Option<&i32>,
1621	/// v_clone.len(),
1622	/// v_clone.capacity())
1623	/// };
1624	/// ```
1625	///
1626	/// [`from_raw_parts`]: ../../std/vec/struct.Vec.html#method.from_raw_parts
1627	///
1628	/// Implementing `split_at_mut`:
1629	///
1630	/// ```
1631	/// use std::{slice, mem};
1632	///
1633	/// // There are multiple ways to do this, and there are multiple problems
1634	/// // with the following (transmute) way.
1635	/// fn split_at_mut_transmute<T>(slice: &mut [T], mid: usize)
1636	/// -> (&mut [T], &mut [T]) {
1637	/// let len = slice.len();
1638	/// assert!(mid <= len);
1639	/// unsafe {
1640	/// let slice2 = mem::transmute::<&mut [T], &mut [T]>(slice);
1641	/// // first: transmute is not type safe; all it checks is that T and
1642	/// // U are of the same size. Second, right here, you have two
1643	/// // mutable references pointing to the same memory.
1644	/// (&mut slice[`0`..mid], &mut slice2[mid..len])
1645	/// }
1646	/// }
1647	///
1648	/// // This gets rid of the type safety problems; `&mut ` will only give*
1649	/// // you a `&mut T` from a `&mut T` or `mut T`.*
1650	/// fn split_at_mut_casts<T>(slice: &mut [T], mid: usize)
1651	/// -> (&mut [T], &mut [T]) {
1652	/// let len = slice.len();
1653	/// assert!(mid <= len);
1654	/// unsafe {
1655	/// let slice2 = &mut (slice as mut [T]);
1656	/// // however, you still have two mutable references pointing to
1657	/// // the same memory.
1658	/// (&mut slice[`0`..mid], &mut slice2[mid..len])
1659	/// }
1660	/// }
1661	///
1662	/// // This is how the standard library does it. This is the best method, if
1663	/// // you need to do something like this
1664	/// fn split_at_stdlib<T>(slice: &mut [T], mid: usize)
1665	/// -> (&mut [T], &mut [T]) {
1666	/// let len = slice.len();
1667	/// assert!(mid <= len);
1668	/// unsafe {
1669	/// let ptr = slice.as_mut_ptr();
1670	/// // This now has three mutable references pointing at the same
1671	/// // memory. `slice`, the rvalue ret.0, and the rvalue ret.1.
1672	/// // `slice` is never used after `let ptr = ...`, and so one can
1673	/// // treat it as "dead", and therefore, you only have two real
1674	/// // mutable slices.
1675	/// (slice::from_raw_parts_mut(ptr, mid),
1676	/// slice::from_raw_parts_mut(ptr.add(mid), len - mid))
1677	/// }
1678	/// }
1679	/// ```
1680	#[stable(feature = "rust1", since = "1.0.0")]
1681	#[rustc_allowed_through_unstable_modules = "import this function via `std::mem` instead"]
1682	#[rustc_const_stable(feature = "const_transmute", since = "1.56.0")]
1683	#[rustc_diagnostic_item = "transmute"]
1684	#[rustc_nounwind]
1685	#[rustc_intrinsic]
1686	pub const unsafe fn transmute<Src, Dst>(src: Src) -> Dst;
1687
1688	/// Like [`transmute`], but even less checked at compile-time: rather than
1689	/// giving an error for `size_of::<Src>() != size_of::<Dst>()`, it's
1690	/// Undefined Behavior* at runtime.*
1691	///
1692	/// Prefer normal `transmute` where possible, for the extra checking, since
1693	/// both do exactly the same thing at runtime, if they both compile.
1694	///
1695	/// This is not expected to ever be exposed directly to users, rather it
1696	/// may eventually be exposed through some more-constrained API.
1697	#[rustc_intrinsic_const_stable_indirect]
1698	#[rustc_nounwind]
1699	#[rustc_intrinsic]
1700	pub const unsafe fn transmute_unchecked<Src, Dst>(src: Src) -> Dst;
1701
1702	/// Returns `true` if the actual type given as `T` requires drop
1703	/// glue; returns `false` if the actual type provided for `T`
1704	/// implements `Copy`.
1705	///
1706	/// If the actual type neither requires drop glue nor implements
1707	/// `Copy`, then the return value of this function is unspecified.
1708	///
1709	/// Note that, unlike most intrinsics, this is safe to call;
1710	/// it does not require an `unsafe` block.
1711	/// Therefore, implementations must not require the user to uphold
1712	/// any safety invariants.
1713	///
1714	/// The stabilized version of this intrinsic is [`mem::needs_drop`](crate::mem::needs_drop).
1715	#[rustc_intrinsic_const_stable_indirect]
1716	#[rustc_nounwind]
1717	#[rustc_intrinsic]
1718	pub const fn needs_drop<T: ?Sized>() -> bool;
1719
1720	/// Calculates the offset from a pointer.
1721	///
1722	/// This is implemented as an intrinsic to avoid converting to and from an
1723	/// integer, since the conversion would throw away aliasing information.
1724	///
1725	/// This can only be used with `Ptr` as a raw pointer type (`mut` or `const`)
1726	/// to a `Sized` pointee and with `Delta` as `usize` or `isize`. Any other
1727	/// instantiations may arbitrarily misbehave, and that's not* a compiler bug.*
1728	///
1729	/// # Safety
1730	///
1731	/// If the computed offset is non-zero, then both the starting and resulting pointer must be
1732	/// either in bounds or at the end of an allocated object. If either pointer is out
1733	/// of bounds or arithmetic overflow occurs then this operation is undefined behavior.
1734	///
1735	/// The stabilized version of this intrinsic is [`pointer::offset`].
1736	#[must_use = "returns a new pointer rather than modifying its argument"]
1737	#[rustc_intrinsic_const_stable_indirect]
1738	#[rustc_nounwind]
1739	#[rustc_intrinsic]
1740	pub const unsafe fn offset<Ptr, Delta>(dst: Ptr, offset: Delta) -> Ptr;
1741
1742	/// Calculates the offset from a pointer, potentially wrapping.
1743	///
1744	/// This is implemented as an intrinsic to avoid converting to and from an
1745	/// integer, since the conversion inhibits certain optimizations.
1746	///
1747	/// # Safety
1748	///
1749	/// Unlike the `offset` intrinsic, this intrinsic does not restrict the
1750	/// resulting pointer to point into or at the end of an allocated
1751	/// object, and it wraps with two's complement arithmetic. The resulting
1752	/// value is not necessarily valid to be used to actually access memory.
1753	///
1754	/// The stabilized version of this intrinsic is [`pointer::wrapping_offset`].
1755	#[must_use = "returns a new pointer rather than modifying its argument"]
1756	#[rustc_intrinsic_const_stable_indirect]
1757	#[rustc_nounwind]
1758	#[rustc_intrinsic]
1759	pub const unsafe fn arith_offset<T>(dst: *const T, offset: isize) -> *const T;
1760
1761	/// Masks out bits of the pointer according to a mask.
1762	///
1763	/// Note that, unlike most intrinsics, this is safe to call;
1764	/// it does not require an `unsafe` block.
1765	/// Therefore, implementations must not require the user to uphold
1766	/// any safety invariants.
1767	///
1768	/// Consider using [`pointer::mask`] instead.
1769	#[rustc_nounwind]
1770	#[rustc_intrinsic]
1771	pub fn ptr_mask<T>(ptr: *const T, mask: usize) -> *const T;
1772
1773	/// Equivalent to the appropriate `llvm.memcpy.p0i8.0i8.` intrinsic, with*
1774	/// a size of `count` `size_of::<T>()` and an alignment of*
1775	/// `min_align_of::<T>()`
1776	///
1777	/// This intrinsic does not have a stable counterpart.
1778	/// # Safety
1779	///
1780	/// The safety requirements are consistent with [`copy_nonoverlapping`]
1781	/// while the read and write behaviors are volatile,
1782	/// which means it will not be optimized out unless `_count` or `size_of::<T>()` is equal to zero.
1783	///
1784	/// [`copy_nonoverlapping`]: ptr::copy_nonoverlapping
1785	#[rustc_intrinsic]
1786	#[rustc_nounwind]
1787	pub unsafe fn volatile_copy_nonoverlapping_memory<T>(dst: *mut T, src: *const T, count: usize);
1788	/// Equivalent to the appropriate `llvm.memmove.p0i8.0i8.` intrinsic, with*
1789	/// a size of `count size_of::<T>()` and an alignment of*
1790	/// `min_align_of::<T>()`
1791	///
1792	/// The volatile parameter is set to `true`, so it will not be optimized out
1793	/// unless size is equal to zero.
1794	///
1795	/// This intrinsic does not have a stable counterpart.
1796	#[rustc_intrinsic]
1797	#[rustc_nounwind]
1798	pub unsafe fn volatile_copy_memory<T>(dst: *mut T, src: *const T, count: usize);
1799	/// Equivalent to the appropriate `llvm.memset.p0i8.` intrinsic, with a*
1800	/// size of `count size_of::<T>()` and an alignment of*
1801	/// `min_align_of::<T>()`.
1802	///
1803	/// This intrinsic does not have a stable counterpart.
1804	/// # Safety
1805	///
1806	/// The safety requirements are consistent with [`write_bytes`] while the write behavior is volatile,
1807	/// which means it will not be optimized out unless `_count` or `size_of::<T>()` is equal to zero.
1808	///
1809	/// [`write_bytes`]: ptr::write_bytes
1810	#[rustc_intrinsic]
1811	#[rustc_nounwind]
1812	pub unsafe fn volatile_set_memory<T>(dst: *mut T, val: u8, count: usize);
1813
1814	/// Performs a volatile load from the `src` pointer.
1815	///
1816	/// The stabilized version of this intrinsic is [`core::ptr::read_volatile`].
1817	#[rustc_intrinsic]
1818	#[rustc_nounwind]
1819	pub unsafe fn volatile_load<T>(src: *const T) -> T;
1820	/// Performs a volatile store to the `dst` pointer.
1821	///
1822	/// The stabilized version of this intrinsic is [`core::ptr::write_volatile`].
1823	#[rustc_intrinsic]
1824	#[rustc_nounwind]
1825	pub unsafe fn volatile_store<T>(dst: *mut T, val: T);
1826
1827	/// Performs a volatile load from the `src` pointer
1828	/// The pointer is not required to be aligned.
1829	///
1830	/// This intrinsic does not have a stable counterpart.
1831	#[rustc_intrinsic]
1832	#[rustc_nounwind]
1833	#[rustc_diagnostic_item = "intrinsics_unaligned_volatile_load"]
1834	pub unsafe fn unaligned_volatile_load<T>(src: *const T) -> T;
1835	/// Performs a volatile store to the `dst` pointer.
1836	/// The pointer is not required to be aligned.
1837	///
1838	/// This intrinsic does not have a stable counterpart.
1839	#[rustc_intrinsic]
1840	#[rustc_nounwind]
1841	#[rustc_diagnostic_item = "intrinsics_unaligned_volatile_store"]
1842	pub unsafe fn unaligned_volatile_store<T>(dst: *mut T, val: T);
1843
1844	/// Returns the square root of an `f16`
1845	///
1846	/// The stabilized version of this intrinsic is
1847	/// [`f16::sqrt`](../../std/primitive.f16.html#method.sqrt)
1848	#[rustc_intrinsic]
1849	#[rustc_nounwind]
1850	pub unsafe fn sqrtf16(x: f16) -> f16;
1851	/// Returns the square root of an `f32`
1852	///
1853	/// The stabilized version of this intrinsic is
1854	/// [`f32::sqrt`](../../std/primitive.f32.html#method.sqrt)
1855	#[rustc_intrinsic]
1856	#[rustc_nounwind]
1857	pub unsafe fn sqrtf32(x: f32) -> f32;
1858	/// Returns the square root of an `f64`
1859	///
1860	/// The stabilized version of this intrinsic is
1861	/// [`f64::sqrt`](../../std/primitive.f64.html#method.sqrt)
1862	#[rustc_intrinsic]
1863	#[rustc_nounwind]
1864	pub unsafe fn sqrtf64(x: f64) -> f64;
1865	/// Returns the square root of an `f128`
1866	///
1867	/// The stabilized version of this intrinsic is
1868	/// [`f128::sqrt`](../../std/primitive.f128.html#method.sqrt)
1869	#[rustc_intrinsic]
1870	#[rustc_nounwind]
1871	pub unsafe fn sqrtf128(x: f128) -> f128;
1872
1873	/// Raises an `f16` to an integer power.
1874	///
1875	/// The stabilized version of this intrinsic is
1876	/// [`f16::powi`](../../std/primitive.f16.html#method.powi)
1877	#[rustc_intrinsic]
1878	#[rustc_nounwind]
1879	pub unsafe fn powif16(a: f16, x: i32) -> f16;
1880	/// Raises an `f32` to an integer power.
1881	///
1882	/// The stabilized version of this intrinsic is
1883	/// [`f32::powi`](../../std/primitive.f32.html#method.powi)
1884	#[rustc_intrinsic]
1885	#[rustc_nounwind]
1886	pub unsafe fn powif32(a: f32, x: i32) -> f32;
1887	/// Raises an `f64` to an integer power.
1888	///
1889	/// The stabilized version of this intrinsic is
1890	/// [`f64::powi`](../../std/primitive.f64.html#method.powi)
1891	#[rustc_intrinsic]
1892	#[rustc_nounwind]
1893	pub unsafe fn powif64(a: f64, x: i32) -> f64;
1894	/// Raises an `f128` to an integer power.
1895	///
1896	/// The stabilized version of this intrinsic is
1897	/// [`f128::powi`](../../std/primitive.f128.html#method.powi)
1898	#[rustc_intrinsic]
1899	#[rustc_nounwind]
1900	pub unsafe fn powif128(a: f128, x: i32) -> f128;
1901
1902	/// Returns the sine of an `f16`.
1903	///
1904	/// The stabilized version of this intrinsic is
1905	/// [`f16::sin`](../../std/primitive.f16.html#method.sin)
1906	#[rustc_intrinsic]
1907	#[rustc_nounwind]
1908	pub unsafe fn sinf16(x: f16) -> f16;
1909	/// Returns the sine of an `f32`.
1910	///
1911	/// The stabilized version of this intrinsic is
1912	/// [`f32::sin`](../../std/primitive.f32.html#method.sin)
1913	#[rustc_intrinsic]
1914	#[rustc_nounwind]
1915	pub unsafe fn sinf32(x: f32) -> f32;
1916	/// Returns the sine of an `f64`.
1917	///
1918	/// The stabilized version of this intrinsic is
1919	/// [`f64::sin`](../../std/primitive.f64.html#method.sin)
1920	#[rustc_intrinsic]
1921	#[rustc_nounwind]
1922	pub unsafe fn sinf64(x: f64) -> f64;
1923	/// Returns the sine of an `f128`.
1924	///
1925	/// The stabilized version of this intrinsic is
1926	/// [`f128::sin`](../../std/primitive.f128.html#method.sin)
1927	#[rustc_intrinsic]
1928	#[rustc_nounwind]
1929	pub unsafe fn sinf128(x: f128) -> f128;
1930
1931	/// Returns the cosine of an `f16`.
1932	///
1933	/// The stabilized version of this intrinsic is
1934	/// [`f16::cos`](../../std/primitive.f16.html#method.cos)
1935	#[rustc_intrinsic]
1936	#[rustc_nounwind]
1937	pub unsafe fn cosf16(x: f16) -> f16;
1938	/// Returns the cosine of an `f32`.
1939	///
1940	/// The stabilized version of this intrinsic is
1941	/// [`f32::cos`](../../std/primitive.f32.html#method.cos)
1942	#[rustc_intrinsic]
1943	#[rustc_nounwind]
1944	pub unsafe fn cosf32(x: f32) -> f32;
1945	/// Returns the cosine of an `f64`.
1946	///
1947	/// The stabilized version of this intrinsic is
1948	/// [`f64::cos`](../../std/primitive.f64.html#method.cos)
1949	#[rustc_intrinsic]
1950	#[rustc_nounwind]
1951	pub unsafe fn cosf64(x: f64) -> f64;
1952	/// Returns the cosine of an `f128`.
1953	///
1954	/// The stabilized version of this intrinsic is
1955	/// [`f128::cos`](../../std/primitive.f128.html#method.cos)
1956	#[rustc_intrinsic]
1957	#[rustc_nounwind]
1958	pub unsafe fn cosf128(x: f128) -> f128;
1959
1960	/// Raises an `f16` to an `f16` power.
1961	///
1962	/// The stabilized version of this intrinsic is
1963	/// [`f16::powf`](../../std/primitive.f16.html#method.powf)
1964	#[rustc_intrinsic]
1965	#[rustc_nounwind]
1966	pub unsafe fn powf16(a: f16, x: f16) -> f16;
1967	/// Raises an `f32` to an `f32` power.
1968	///
1969	/// The stabilized version of this intrinsic is
1970	/// [`f32::powf`](../../std/primitive.f32.html#method.powf)
1971	#[rustc_intrinsic]
1972	#[rustc_nounwind]
1973	pub unsafe fn powf32(a: f32, x: f32) -> f32;
1974	/// Raises an `f64` to an `f64` power.
1975	///
1976	/// The stabilized version of this intrinsic is
1977	/// [`f64::powf`](../../std/primitive.f64.html#method.powf)
1978	#[rustc_intrinsic]
1979	#[rustc_nounwind]
1980	pub unsafe fn powf64(a: f64, x: f64) -> f64;
1981	/// Raises an `f128` to an `f128` power.
1982	///
1983	/// The stabilized version of this intrinsic is
1984	/// [`f128::powf`](../../std/primitive.f128.html#method.powf)
1985	#[rustc_intrinsic]
1986	#[rustc_nounwind]
1987	pub unsafe fn powf128(a: f128, x: f128) -> f128;
1988
1989	/// Returns the exponential of an `f16`.
1990	///
1991	/// The stabilized version of this intrinsic is
1992	/// [`f16::exp`](../../std/primitive.f16.html#method.exp)
1993	#[rustc_intrinsic]
1994	#[rustc_nounwind]
1995	pub unsafe fn expf16(x: f16) -> f16;
1996	/// Returns the exponential of an `f32`.
1997	///
1998	/// The stabilized version of this intrinsic is
1999	/// [`f32::exp`](../../std/primitive.f32.html#method.exp)
2000	#[rustc_intrinsic]
2001	#[rustc_nounwind]
2002	pub unsafe fn expf32(x: f32) -> f32;
2003	/// Returns the exponential of an `f64`.
2004	///
2005	/// The stabilized version of this intrinsic is
2006	/// [`f64::exp`](../../std/primitive.f64.html#method.exp)
2007	#[rustc_intrinsic]
2008	#[rustc_nounwind]
2009	pub unsafe fn expf64(x: f64) -> f64;
2010	/// Returns the exponential of an `f128`.
2011	///
2012	/// The stabilized version of this intrinsic is
2013	/// [`f128::exp`](../../std/primitive.f128.html#method.exp)
2014	#[rustc_intrinsic]
2015	#[rustc_nounwind]
2016	pub unsafe fn expf128(x: f128) -> f128;
2017
2018	/// Returns 2 raised to the power of an `f16`.
2019	///
2020	/// The stabilized version of this intrinsic is
2021	/// [`f16::exp2`](../../std/primitive.f16.html#method.exp2)
2022	#[rustc_intrinsic]
2023	#[rustc_nounwind]
2024	pub unsafe fn exp2f16(x: f16) -> f16;
2025	/// Returns 2 raised to the power of an `f32`.
2026	///
2027	/// The stabilized version of this intrinsic is
2028	/// [`f32::exp2`](../../std/primitive.f32.html#method.exp2)
2029	#[rustc_intrinsic]
2030	#[rustc_nounwind]
2031	pub unsafe fn exp2f32(x: f32) -> f32;
2032	/// Returns 2 raised to the power of an `f64`.
2033	///
2034	/// The stabilized version of this intrinsic is
2035	/// [`f64::exp2`](../../std/primitive.f64.html#method.exp2)
2036	#[rustc_intrinsic]
2037	#[rustc_nounwind]
2038	pub unsafe fn exp2f64(x: f64) -> f64;
2039	/// Returns 2 raised to the power of an `f128`.
2040	///
2041	/// The stabilized version of this intrinsic is
2042	/// [`f128::exp2`](../../std/primitive.f128.html#method.exp2)
2043	#[rustc_intrinsic]
2044	#[rustc_nounwind]
2045	pub unsafe fn exp2f128(x: f128) -> f128;
2046
2047	/// Returns the natural logarithm of an `f16`.
2048	///
2049	/// The stabilized version of this intrinsic is
2050	/// [`f16::ln`](../../std/primitive.f16.html#method.ln)
2051	#[rustc_intrinsic]
2052	#[rustc_nounwind]
2053	pub unsafe fn logf16(x: f16) -> f16;
2054	/// Returns the natural logarithm of an `f32`.
2055	///
2056	/// The stabilized version of this intrinsic is
2057	/// [`f32::ln`](../../std/primitive.f32.html#method.ln)
2058	#[rustc_intrinsic]
2059	#[rustc_nounwind]
2060	pub unsafe fn logf32(x: f32) -> f32;
2061	/// Returns the natural logarithm of an `f64`.
2062	///
2063	/// The stabilized version of this intrinsic is
2064	/// [`f64::ln`](../../std/primitive.f64.html#method.ln)
2065	#[rustc_intrinsic]
2066	#[rustc_nounwind]
2067	pub unsafe fn logf64(x: f64) -> f64;
2068	/// Returns the natural logarithm of an `f128`.
2069	///
2070	/// The stabilized version of this intrinsic is
2071	/// [`f128::ln`](../../std/primitive.f128.html#method.ln)
2072	#[rustc_intrinsic]
2073	#[rustc_nounwind]
2074	pub unsafe fn logf128(x: f128) -> f128;
2075
2076	/// Returns the base 10 logarithm of an `f16`.
2077	///
2078	/// The stabilized version of this intrinsic is
2079	/// [`f16::log10`](../../std/primitive.f16.html#method.log10)
2080	#[rustc_intrinsic]
2081	#[rustc_nounwind]
2082	pub unsafe fn log10f16(x: f16) -> f16;
2083	/// Returns the base 10 logarithm of an `f32`.
2084	///
2085	/// The stabilized version of this intrinsic is
2086	/// [`f32::log10`](../../std/primitive.f32.html#method.log10)
2087	#[rustc_intrinsic]
2088	#[rustc_nounwind]
2089	pub unsafe fn log10f32(x: f32) -> f32;
2090	/// Returns the base 10 logarithm of an `f64`.
2091	///
2092	/// The stabilized version of this intrinsic is
2093	/// [`f64::log10`](../../std/primitive.f64.html#method.log10)
2094	#[rustc_intrinsic]
2095	#[rustc_nounwind]
2096	pub unsafe fn log10f64(x: f64) -> f64;
2097	/// Returns the base 10 logarithm of an `f128`.
2098	///
2099	/// The stabilized version of this intrinsic is
2100	/// [`f128::log10`](../../std/primitive.f128.html#method.log10)
2101	#[rustc_intrinsic]
2102	#[rustc_nounwind]
2103	pub unsafe fn log10f128(x: f128) -> f128;
2104
2105	/// Returns the base 2 logarithm of an `f16`.
2106	///
2107	/// The stabilized version of this intrinsic is
2108	/// [`f16::log2`](../../std/primitive.f16.html#method.log2)
2109	#[rustc_intrinsic]
2110	#[rustc_nounwind]
2111	pub unsafe fn log2f16(x: f16) -> f16;
2112	/// Returns the base 2 logarithm of an `f32`.
2113	///
2114	/// The stabilized version of this intrinsic is
2115	/// [`f32::log2`](../../std/primitive.f32.html#method.log2)
2116	#[rustc_intrinsic]
2117	#[rustc_nounwind]
2118	pub unsafe fn log2f32(x: f32) -> f32;
2119	/// Returns the base 2 logarithm of an `f64`.
2120	///
2121	/// The stabilized version of this intrinsic is
2122	/// [`f64::log2`](../../std/primitive.f64.html#method.log2)
2123	#[rustc_intrinsic]
2124	#[rustc_nounwind]
2125	pub unsafe fn log2f64(x: f64) -> f64;
2126	/// Returns the base 2 logarithm of an `f128`.
2127	///
2128	/// The stabilized version of this intrinsic is
2129	/// [`f128::log2`](../../std/primitive.f128.html#method.log2)
2130	#[rustc_intrinsic]
2131	#[rustc_nounwind]
2132	pub unsafe fn log2f128(x: f128) -> f128;
2133
2134	/// Returns `a b + c` for `f16` values.*
2135	///
2136	/// The stabilized version of this intrinsic is
2137	/// [`f16::mul_add`](../../std/primitive.f16.html#method.mul_add)
2138	#[rustc_intrinsic]
2139	#[rustc_nounwind]
2140	pub unsafe fn fmaf16(a: f16, b: f16, c: f16) -> f16;
2141	/// Returns `a b + c` for `f32` values.*
2142	///
2143	/// The stabilized version of this intrinsic is
2144	/// [`f32::mul_add`](../../std/primitive.f32.html#method.mul_add)
2145	#[rustc_intrinsic]
2146	#[rustc_nounwind]
2147	pub unsafe fn fmaf32(a: f32, b: f32, c: f32) -> f32;
2148	/// Returns `a b + c` for `f64` values.*
2149	///
2150	/// The stabilized version of this intrinsic is
2151	/// [`f64::mul_add`](../../std/primitive.f64.html#method.mul_add)
2152	#[rustc_intrinsic]
2153	#[rustc_nounwind]
2154	pub unsafe fn fmaf64(a: f64, b: f64, c: f64) -> f64;
2155	/// Returns `a b + c` for `f128` values.*
2156	///
2157	/// The stabilized version of this intrinsic is
2158	/// [`f128::mul_add`](../../std/primitive.f128.html#method.mul_add)
2159	#[rustc_intrinsic]
2160	#[rustc_nounwind]
2161	pub unsafe fn fmaf128(a: f128, b: f128, c: f128) -> f128;
2162
2163	/// Returns `a b + c` for `f16` values, non-deterministically executing*
2164	/// either a fused multiply-add or two operations with rounding of the
2165	/// intermediate result.
2166	///
2167	/// The operation is fused if the code generator determines that target
2168	/// instruction set has support for a fused operation, and that the fused
2169	/// operation is more efficient than the equivalent, separate pair of mul
2170	/// and add instructions. It is unspecified whether or not a fused operation
2171	/// is selected, and that may depend on optimization level and context, for
2172	/// example.
2173	#[rustc_intrinsic]
2174	#[rustc_nounwind]
2175	pub unsafe fn fmuladdf16(a: f16, b: f16, c: f16) -> f16;
2176	/// Returns `a b + c` for `f32` values, non-deterministically executing*
2177	/// either a fused multiply-add or two operations with rounding of the
2178	/// intermediate result.
2179	///
2180	/// The operation is fused if the code generator determines that target
2181	/// instruction set has support for a fused operation, and that the fused
2182	/// operation is more efficient than the equivalent, separate pair of mul
2183	/// and add instructions. It is unspecified whether or not a fused operation
2184	/// is selected, and that may depend on optimization level and context, for
2185	/// example.
2186	#[rustc_intrinsic]
2187	#[rustc_nounwind]
2188	pub unsafe fn fmuladdf32(a: f32, b: f32, c: f32) -> f32;
2189	/// Returns `a b + c` for `f64` values, non-deterministically executing*
2190	/// either a fused multiply-add or two operations with rounding of the
2191	/// intermediate result.
2192	///
2193	/// The operation is fused if the code generator determines that target
2194	/// instruction set has support for a fused operation, and that the fused
2195	/// operation is more efficient than the equivalent, separate pair of mul
2196	/// and add instructions. It is unspecified whether or not a fused operation
2197	/// is selected, and that may depend on optimization level and context, for
2198	/// example.
2199	#[rustc_intrinsic]
2200	#[rustc_nounwind]
2201	pub unsafe fn fmuladdf64(a: f64, b: f64, c: f64) -> f64;
2202	/// Returns `a b + c` for `f128` values, non-deterministically executing*
2203	/// either a fused multiply-add or two operations with rounding of the
2204	/// intermediate result.
2205	///
2206	/// The operation is fused if the code generator determines that target
2207	/// instruction set has support for a fused operation, and that the fused
2208	/// operation is more efficient than the equivalent, separate pair of mul
2209	/// and add instructions. It is unspecified whether or not a fused operation
2210	/// is selected, and that may depend on optimization level and context, for
2211	/// example.
2212	#[rustc_intrinsic]
2213	#[rustc_nounwind]
2214	pub unsafe fn fmuladdf128(a: f128, b: f128, c: f128) -> f128;
2215
2216	/// Returns the largest integer less than or equal to an `f16`.
2217	///
2218	/// The stabilized version of this intrinsic is
2219	/// [`f16::floor`](../../std/primitive.f16.html#method.floor)
2220	#[rustc_intrinsic]
2221	#[rustc_nounwind]
2222	pub unsafe fn floorf16(x: f16) -> f16;
2223	/// Returns the largest integer less than or equal to an `f32`.
2224	///
2225	/// The stabilized version of this intrinsic is
2226	/// [`f32::floor`](../../std/primitive.f32.html#method.floor)
2227	#[rustc_intrinsic]
2228	#[rustc_nounwind]
2229	pub unsafe fn floorf32(x: f32) -> f32;
2230	/// Returns the largest integer less than or equal to an `f64`.
2231	///
2232	/// The stabilized version of this intrinsic is
2233	/// [`f64::floor`](../../std/primitive.f64.html#method.floor)
2234	#[rustc_intrinsic]
2235	#[rustc_nounwind]
2236	pub unsafe fn floorf64(x: f64) -> f64;
2237	/// Returns the largest integer less than or equal to an `f128`.
2238	///
2239	/// The stabilized version of this intrinsic is
2240	/// [`f128::floor`](../../std/primitive.f128.html#method.floor)
2241	#[rustc_intrinsic]
2242	#[rustc_nounwind]
2243	pub unsafe fn floorf128(x: f128) -> f128;
2244
2245	/// Returns the smallest integer greater than or equal to an `f16`.
2246	///
2247	/// The stabilized version of this intrinsic is
2248	/// [`f16::ceil`](../../std/primitive.f16.html#method.ceil)
2249	#[rustc_intrinsic]
2250	#[rustc_nounwind]
2251	pub unsafe fn ceilf16(x: f16) -> f16;
2252	/// Returns the smallest integer greater than or equal to an `f32`.
2253	///
2254	/// The stabilized version of this intrinsic is
2255	/// [`f32::ceil`](../../std/primitive.f32.html#method.ceil)
2256	#[rustc_intrinsic]
2257	#[rustc_nounwind]
2258	pub unsafe fn ceilf32(x: f32) -> f32;
2259	/// Returns the smallest integer greater than or equal to an `f64`.
2260	///
2261	/// The stabilized version of this intrinsic is
2262	/// [`f64::ceil`](../../std/primitive.f64.html#method.ceil)
2263	#[rustc_intrinsic]
2264	#[rustc_nounwind]
2265	pub unsafe fn ceilf64(x: f64) -> f64;
2266	/// Returns the smallest integer greater than or equal to an `f128`.
2267	///
2268	/// The stabilized version of this intrinsic is
2269	/// [`f128::ceil`](../../std/primitive.f128.html#method.ceil)
2270	#[rustc_intrinsic]
2271	#[rustc_nounwind]
2272	pub unsafe fn ceilf128(x: f128) -> f128;
2273
2274	/// Returns the integer part of an `f16`.
2275	///
2276	/// The stabilized version of this intrinsic is
2277	/// [`f16::trunc`](../../std/primitive.f16.html#method.trunc)
2278	#[rustc_intrinsic]
2279	#[rustc_nounwind]
2280	pub unsafe fn truncf16(x: f16) -> f16;
2281	/// Returns the integer part of an `f32`.
2282	///
2283	/// The stabilized version of this intrinsic is
2284	/// [`f32::trunc`](../../std/primitive.f32.html#method.trunc)
2285	#[rustc_intrinsic]
2286	#[rustc_nounwind]
2287	pub unsafe fn truncf32(x: f32) -> f32;
2288	/// Returns the integer part of an `f64`.
2289	///
2290	/// The stabilized version of this intrinsic is
2291	/// [`f64::trunc`](../../std/primitive.f64.html#method.trunc)
2292	#[rustc_intrinsic]
2293	#[rustc_nounwind]
2294	pub unsafe fn truncf64(x: f64) -> f64;
2295	/// Returns the integer part of an `f128`.
2296	///
2297	/// The stabilized version of this intrinsic is
2298	/// [`f128::trunc`](../../std/primitive.f128.html#method.trunc)
2299	#[rustc_intrinsic]
2300	#[rustc_nounwind]
2301	pub unsafe fn truncf128(x: f128) -> f128;
2302
2303	/// Returns the nearest integer to an `f16`. Rounds half-way cases to the number with an even
2304	/// least significant digit.
2305	///
2306	/// The stabilized version of this intrinsic is
2307	/// [`f16::round_ties_even`](../../std/primitive.f16.html#method.round_ties_even)
2308	#[rustc_intrinsic]
2309	#[rustc_nounwind]
2310	#[cfg(not(bootstrap))]
2311	pub fn round_ties_even_f16(x: f16) -> f16;
2312
2313	/// To be removed on next bootstrap bump.
2314	#[cfg(bootstrap)]
2315	pub fn round_ties_even_f16(x: f16) -> f16 {
2316	#[rustc_intrinsic]
2317	#[rustc_nounwind]
2318	unsafe fn rintf16(x: f16) -> f16;
2319
2320	// SAFETY: this intrinsic isn't actually unsafe
2321	unsafe { rintf16(x) }
2322	}
2323
2324	/// Returns the nearest integer to an `f32`. Rounds half-way cases to the number with an even
2325	/// least significant digit.
2326	///
2327	/// The stabilized version of this intrinsic is
2328	/// [`f32::round_ties_even`](../../std/primitive.f32.html#method.round_ties_even)
2329	#[rustc_intrinsic]
2330	#[rustc_nounwind]
2331	#[cfg(not(bootstrap))]
2332	pub fn round_ties_even_f32(x: f32) -> f32;
2333
2334	/// To be removed on next bootstrap bump.
2335	#[cfg(bootstrap)]
2336	pub fn round_ties_even_f32(x: f32) -> f32 {
2337	#[rustc_intrinsic]
2338	#[rustc_nounwind]
2339	unsafe fn rintf32(x: f32) -> f32;
2340
2341	// SAFETY: this intrinsic isn't actually unsafe
2342	unsafe { rintf32(x) }
2343	}
2344
2345	/// Provided for compatibility with stdarch. DO NOT USE.
2346	#[inline(always)]
2347	pub unsafe fn rintf32(x: f32) -> f32 {
2348	round_ties_even_f32(x)
2349	}
2350
2351	/// Returns the nearest integer to an `f64`. Rounds half-way cases to the number with an even
2352	/// least significant digit.
2353	///
2354	/// The stabilized version of this intrinsic is
2355	/// [`f64::round_ties_even`](../../std/primitive.f64.html#method.round_ties_even)
2356	#[rustc_intrinsic]
2357	#[rustc_nounwind]
2358	#[cfg(not(bootstrap))]
2359	pub fn round_ties_even_f64(x: f64) -> f64;
2360
2361	/// To be removed on next bootstrap bump.
2362	#[cfg(bootstrap)]
2363	pub fn round_ties_even_f64(x: f64) -> f64 {
2364	#[rustc_intrinsic]
2365	#[rustc_nounwind]
2366	unsafe fn rintf64(x: f64) -> f64;
2367
2368	// SAFETY: this intrinsic isn't actually unsafe
2369	unsafe { rintf64(x) }
2370	}
2371
2372	/// Provided for compatibility with stdarch. DO NOT USE.
2373	#[inline(always)]
2374	pub unsafe fn rintf64(x: f64) -> f64 {
2375	round_ties_even_f64(x)
2376	}
2377
2378	/// Returns the nearest integer to an `f128`. Rounds half-way cases to the number with an even
2379	/// least significant digit.
2380	///
2381	/// The stabilized version of this intrinsic is
2382	/// [`f128::round_ties_even`](../../std/primitive.f128.html#method.round_ties_even)
2383	#[rustc_intrinsic]
2384	#[rustc_nounwind]
2385	#[cfg(not(bootstrap))]
2386	pub fn round_ties_even_f128(x: f128) -> f128;
2387
2388	/// To be removed on next bootstrap bump.
2389	#[cfg(bootstrap)]
2390	pub fn round_ties_even_f128(x: f128) -> f128 {
2391	#[rustc_intrinsic]
2392	#[rustc_nounwind]
2393	unsafe fn rintf128(x: f128) -> f128;
2394
2395	// SAFETY: this intrinsic isn't actually unsafe
2396	unsafe { rintf128(x) }
2397	}
2398
2399	/// Returns the nearest integer to an `f16`. Rounds half-way cases away from zero.
2400	///
2401	/// The stabilized version of this intrinsic is
2402	/// [`f16::round`](../../std/primitive.f16.html#method.round)
2403	#[rustc_intrinsic]
2404	#[rustc_nounwind]
2405	pub unsafe fn roundf16(x: f16) -> f16;
2406	/// Returns the nearest integer to an `f32`. Rounds half-way cases away from zero.
2407	///
2408	/// The stabilized version of this intrinsic is
2409	/// [`f32::round`](../../std/primitive.f32.html#method.round)
2410	#[rustc_intrinsic]
2411	#[rustc_nounwind]
2412	pub unsafe fn roundf32(x: f32) -> f32;
2413	/// Returns the nearest integer to an `f64`. Rounds half-way cases away from zero.
2414	///
2415	/// The stabilized version of this intrinsic is
2416	/// [`f64::round`](../../std/primitive.f64.html#method.round)
2417	#[rustc_intrinsic]
2418	#[rustc_nounwind]
2419	pub unsafe fn roundf64(x: f64) -> f64;
2420	/// Returns the nearest integer to an `f128`. Rounds half-way cases away from zero.
2421	///
2422	/// The stabilized version of this intrinsic is
2423	/// [`f128::round`](../../std/primitive.f128.html#method.round)
2424	#[rustc_intrinsic]
2425	#[rustc_nounwind]
2426	pub unsafe fn roundf128(x: f128) -> f128;
2427
2428	/// Float addition that allows optimizations based on algebraic rules.
2429	/// May assume inputs are finite.
2430	///
2431	/// This intrinsic does not have a stable counterpart.
2432	#[rustc_intrinsic]
2433	#[rustc_nounwind]
2434	pub unsafe fn fadd_fast<T: Copy>(a: T, b: T) -> T;
2435
2436	/// Float subtraction that allows optimizations based on algebraic rules.
2437	/// May assume inputs are finite.
2438	///
2439	/// This intrinsic does not have a stable counterpart.
2440	#[rustc_intrinsic]
2441	#[rustc_nounwind]
2442	pub unsafe fn fsub_fast<T: Copy>(a: T, b: T) -> T;
2443
2444	/// Float multiplication that allows optimizations based on algebraic rules.
2445	/// May assume inputs are finite.
2446	///
2447	/// This intrinsic does not have a stable counterpart.
2448	#[rustc_intrinsic]
2449	#[rustc_nounwind]
2450	pub unsafe fn fmul_fast<T: Copy>(a: T, b: T) -> T;
2451
2452	/// Float division that allows optimizations based on algebraic rules.
2453	/// May assume inputs are finite.
2454	///
2455	/// This intrinsic does not have a stable counterpart.
2456	#[rustc_intrinsic]
2457	#[rustc_nounwind]
2458	pub unsafe fn fdiv_fast<T: Copy>(a: T, b: T) -> T;
2459
2460	/// Float remainder that allows optimizations based on algebraic rules.
2461	/// May assume inputs are finite.
2462	///
2463	/// This intrinsic does not have a stable counterpart.
2464	#[rustc_intrinsic]
2465	#[rustc_nounwind]
2466	pub unsafe fn frem_fast<T: Copy>(a: T, b: T) -> T;
2467
2468	/// Converts with LLVM’s fptoui/fptosi, which may return undef for values out of range
2469	/// (<https://github.com/rust-lang/rust/issues/10184>)
2470	///
2471	/// Stabilized as [`f32::to_int_unchecked`] and [`f64::to_int_unchecked`].
2472	#[rustc_intrinsic]
2473	#[rustc_nounwind]
2474	pub unsafe fn float_to_int_unchecked<Float: Copy, Int: Copy>(value: Float) -> Int;
2475
2476	/// Float addition that allows optimizations based on algebraic rules.
2477	///
2478	/// This intrinsic does not have a stable counterpart.
2479	#[rustc_nounwind]
2480	#[rustc_intrinsic]
2481	pub fn fadd_algebraic<T: Copy>(a: T, b: T) -> T;
2482
2483	/// Float subtraction that allows optimizations based on algebraic rules.
2484	///
2485	/// This intrinsic does not have a stable counterpart.
2486	#[rustc_nounwind]
2487	#[rustc_intrinsic]
2488	pub fn fsub_algebraic<T: Copy>(a: T, b: T) -> T;
2489
2490	/// Float multiplication that allows optimizations based on algebraic rules.
2491	///
2492	/// This intrinsic does not have a stable counterpart.
2493	#[rustc_nounwind]
2494	#[rustc_intrinsic]
2495	pub fn fmul_algebraic<T: Copy>(a: T, b: T) -> T;
2496
2497	/// Float division that allows optimizations based on algebraic rules.
2498	///
2499	/// This intrinsic does not have a stable counterpart.
2500	#[rustc_nounwind]
2501	#[rustc_intrinsic]
2502	pub fn fdiv_algebraic<T: Copy>(a: T, b: T) -> T;
2503
2504	/// Float remainder that allows optimizations based on algebraic rules.
2505	///
2506	/// This intrinsic does not have a stable counterpart.
2507	#[rustc_nounwind]
2508	#[rustc_intrinsic]
2509	pub fn frem_algebraic<T: Copy>(a: T, b: T) -> T;
2510
2511	/// Returns the number of bits set in an integer type `T`
2512	///
2513	/// Note that, unlike most intrinsics, this is safe to call;
2514	/// it does not require an `unsafe` block.
2515	/// Therefore, implementations must not require the user to uphold
2516	/// any safety invariants.
2517	///
2518	/// The stabilized versions of this intrinsic are available on the integer
2519	/// primitives via the `count_ones` method. For example,
2520	/// [`u32::count_ones`]
2521	#[rustc_intrinsic_const_stable_indirect]
2522	#[rustc_nounwind]
2523	#[rustc_intrinsic]
2524	pub const fn ctpop<T: Copy>(x: T) -> u32;
2525
2526	/// Returns the number of leading unset bits (zeroes) in an integer type `T`.
2527	///
2528	/// Note that, unlike most intrinsics, this is safe to call;
2529	/// it does not require an `unsafe` block.
2530	/// Therefore, implementations must not require the user to uphold
2531	/// any safety invariants.
2532	///
2533	/// The stabilized versions of this intrinsic are available on the integer
2534	/// primitives via the `leading_zeros` method. For example,
2535	/// [`u32::leading_zeros`]
2536	///
2537	/// # Examples
2538	///
2539	/// ```
2540	/// #![feature(core_intrinsics)]
2541	/// # #![allow(internal_features)]
2542	///
2543	/// use std::intrinsics::ctlz;
2544	///
2545	/// let x = `0b0001_1100_u8`;
2546	/// let num_leading = ctlz(x);
2547	/// assert_eq!(num_leading, `3`);
2548	/// ```
2549	///
2550	/// An `x` with value `0` will return the bit width of `T`.
2551	///
2552	/// ```
2553	/// #![feature(core_intrinsics)]
2554	/// # #![allow(internal_features)]
2555	///
2556	/// use std::intrinsics::ctlz;
2557	///
2558	/// let x = `0u16`;
2559	/// let num_leading = ctlz(x);
2560	/// assert_eq!(num_leading, `16`);
2561	/// ```
2562	#[rustc_intrinsic_const_stable_indirect]
2563	#[rustc_nounwind]
2564	#[rustc_intrinsic]
2565	pub const fn ctlz<T: Copy>(x: T) -> u32;
2566
2567	/// Like `ctlz`, but extra-unsafe as it returns `undef` when
2568	/// given an `x` with value `0`.
2569	///
2570	/// This intrinsic does not have a stable counterpart.
2571	///
2572	/// # Examples
2573	///
2574	/// ```
2575	/// #![feature(core_intrinsics)]
2576	/// # #![allow(internal_features)]
2577	///
2578	/// use std::intrinsics::ctlz_nonzero;
2579	///
2580	/// let x = `0b0001_1100_u8`;
2581	/// let num_leading = unsafe { ctlz_nonzero(x) };
2582	/// assert_eq!(num_leading, `3`);
2583	/// ```
2584	#[rustc_intrinsic_const_stable_indirect]
2585	#[rustc_nounwind]
2586	#[rustc_intrinsic]
2587	pub const unsafe fn ctlz_nonzero<T: Copy>(x: T) -> u32;
2588
2589	/// Returns the number of trailing unset bits (zeroes) in an integer type `T`.
2590	///
2591	/// Note that, unlike most intrinsics, this is safe to call;
2592	/// it does not require an `unsafe` block.
2593	/// Therefore, implementations must not require the user to uphold
2594	/// any safety invariants.
2595	///
2596	/// The stabilized versions of this intrinsic are available on the integer
2597	/// primitives via the `trailing_zeros` method. For example,
2598	/// [`u32::trailing_zeros`]
2599	///
2600	/// # Examples
2601	///
2602	/// ```
2603	/// #![feature(core_intrinsics)]
2604	/// # #![allow(internal_features)]
2605	///
2606	/// use std::intrinsics::cttz;
2607	///
2608	/// let x = `0b0011_1000_u8`;
2609	/// let num_trailing = cttz(x);
2610	/// assert_eq!(num_trailing, `3`);
2611	/// ```
2612	///
2613	/// An `x` with value `0` will return the bit width of `T`:
2614	///
2615	/// ```
2616	/// #![feature(core_intrinsics)]
2617	/// # #![allow(internal_features)]
2618	///
2619	/// use std::intrinsics::cttz;
2620	///
2621	/// let x = `0u16`;
2622	/// let num_trailing = cttz(x);
2623	/// assert_eq!(num_trailing, `16`);
2624	/// ```
2625	#[rustc_intrinsic_const_stable_indirect]
2626	#[rustc_nounwind]
2627	#[rustc_intrinsic]
2628	pub const fn cttz<T: Copy>(x: T) -> u32;
2629
2630	/// Like `cttz`, but extra-unsafe as it returns `undef` when
2631	/// given an `x` with value `0`.
2632	///
2633	/// This intrinsic does not have a stable counterpart.
2634	///
2635	/// # Examples
2636	///
2637	/// ```
2638	/// #![feature(core_intrinsics)]
2639	/// # #![allow(internal_features)]
2640	///
2641	/// use std::intrinsics::cttz_nonzero;
2642	///
2643	/// let x = `0b0011_1000_u8`;
2644	/// let num_trailing = unsafe { cttz_nonzero(x) };
2645	/// assert_eq!(num_trailing, `3`);
2646	/// ```
2647	#[rustc_intrinsic_const_stable_indirect]
2648	#[rustc_nounwind]
2649	#[rustc_intrinsic]
2650	pub const unsafe fn cttz_nonzero<T: Copy>(x: T) -> u32;
2651
2652	/// Reverses the bytes in an integer type `T`.
2653	///
2654	/// Note that, unlike most intrinsics, this is safe to call;
2655	/// it does not require an `unsafe` block.
2656	/// Therefore, implementations must not require the user to uphold
2657	/// any safety invariants.
2658	///
2659	/// The stabilized versions of this intrinsic are available on the integer
2660	/// primitives via the `swap_bytes` method. For example,
2661	/// [`u32::swap_bytes`]
2662	#[rustc_intrinsic_const_stable_indirect]
2663	#[rustc_nounwind]
2664	#[rustc_intrinsic]
2665	pub const fn bswap<T: Copy>(x: T) -> T;
2666
2667	/// Reverses the bits in an integer type `T`.
2668	///
2669	/// Note that, unlike most intrinsics, this is safe to call;
2670	/// it does not require an `unsafe` block.
2671	/// Therefore, implementations must not require the user to uphold
2672	/// any safety invariants.
2673	///
2674	/// The stabilized versions of this intrinsic are available on the integer
2675	/// primitives via the `reverse_bits` method. For example,
2676	/// [`u32::reverse_bits`]
2677	#[rustc_intrinsic_const_stable_indirect]
2678	#[rustc_nounwind]
2679	#[rustc_intrinsic]
2680	pub const fn bitreverse<T: Copy>(x: T) -> T;
2681
2682	/// Does a three-way comparison between the two integer arguments.
2683	///
2684	/// This is included as an intrinsic as it's useful to let it be one thing
2685	/// in MIR, rather than the multiple checks and switches that make its IR
2686	/// large and difficult to optimize.
2687	///
2688	/// The stabilized version of this intrinsic is [`Ord::cmp`].
2689	#[rustc_intrinsic]
2690	pub const fn three_way_compare<T: Copy>(lhs: T, rhss: T) -> crate::cmp::Ordering;
2691
2692	/// Combine two values which have no bits in common.
2693	///
2694	/// This allows the backend to implement it as `a + b` or* `a \| b`,*
2695	/// depending which is easier to implement on a specific target.
2696	///
2697	/// # Safety
2698	///
2699	/// Requires that `(a & b) == 0`, or equivalently that `(a \| b) == (a + b)`.
2700	///
2701	/// Otherwise it's immediate UB.
2702	#[rustc_const_unstable(feature = "disjoint_bitor", issue = "135758")]
2703	#[rustc_nounwind]
2704	#[rustc_intrinsic]
2705	#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
2706	#[miri::intrinsic_fallback_is_spec] // the fallbacks all `assume` to tell Miri
2707	pub const unsafe fn disjoint_bitor<T: ~const fallback::DisjointBitOr>(a: T, b: T) -> T {
2708	// SAFETY: same preconditions as this function.
2709	unsafe { fallback::DisjointBitOr::disjoint_bitor(self:a, other:b) }
2710	}
2711
2712	/// Performs checked integer addition.
2713	///
2714	/// Note that, unlike most intrinsics, this is safe to call;
2715	/// it does not require an `unsafe` block.
2716	/// Therefore, implementations must not require the user to uphold
2717	/// any safety invariants.
2718	///
2719	/// The stabilized versions of this intrinsic are available on the integer
2720	/// primitives via the `overflowing_add` method. For example,
2721	/// [`u32::overflowing_add`]
2722	#[rustc_intrinsic_const_stable_indirect]
2723	#[rustc_nounwind]
2724	#[rustc_intrinsic]
2725	pub const fn add_with_overflow<T: Copy>(x: T, y: T) -> (T, bool);
2726
2727	/// Performs checked integer subtraction
2728	///
2729	/// Note that, unlike most intrinsics, this is safe to call;
2730	/// it does not require an `unsafe` block.
2731	/// Therefore, implementations must not require the user to uphold
2732	/// any safety invariants.
2733	///
2734	/// The stabilized versions of this intrinsic are available on the integer
2735	/// primitives via the `overflowing_sub` method. For example,
2736	/// [`u32::overflowing_sub`]
2737	#[rustc_intrinsic_const_stable_indirect]
2738	#[rustc_nounwind]
2739	#[rustc_intrinsic]
2740	pub const fn sub_with_overflow<T: Copy>(x: T, y: T) -> (T, bool);
2741
2742	/// Performs checked integer multiplication
2743	///
2744	/// Note that, unlike most intrinsics, this is safe to call;
2745	/// it does not require an `unsafe` block.
2746	/// Therefore, implementations must not require the user to uphold
2747	/// any safety invariants.
2748	///
2749	/// The stabilized versions of this intrinsic are available on the integer
2750	/// primitives via the `overflowing_mul` method. For example,
2751	/// [`u32::overflowing_mul`]
2752	#[rustc_intrinsic_const_stable_indirect]
2753	#[rustc_nounwind]
2754	#[rustc_intrinsic]
2755	pub const fn mul_with_overflow<T: Copy>(x: T, y: T) -> (T, bool);
2756
2757	/// Performs full-width multiplication and addition with a carry:
2758	/// `multiplier multiplicand + addend + carry`.*
2759	///
2760	/// This is possible without any overflow. For `uN`:
2761	/// MAX MAX + MAX + MAX*
2762	/// => (2ⁿ-1) × (2ⁿ-1) + (2ⁿ-1) + (2ⁿ-1)
2763	/// => (2²ⁿ - 2ⁿ⁺¹ + 1) + (2ⁿ⁺¹ - 2)
2764	/// => 2²ⁿ - 1
2765	///
2766	/// For `iN`, the upper bound is MIN MIN + MAX + MAX => 2²ⁿ⁻² + 2ⁿ - 2,*
2767	/// and the lower bound is MAX MIN + MIN + MIN => -2²ⁿ⁻² - 2ⁿ + 2ⁿ⁺¹.*
2768	///
2769	/// This currently supports unsigned integers only, no signed ones.
2770	/// The stabilized versions of this intrinsic are available on integers.
2771	#[unstable(feature = "core_intrinsics", issue = "none")]
2772	#[rustc_const_unstable(feature = "const_carrying_mul_add", issue = "85532")]
2773	#[rustc_nounwind]
2774	#[rustc_intrinsic]
2775	#[miri::intrinsic_fallback_is_spec]
2776	pub const fn carrying_mul_add<T: ~const fallback::CarryingMulAdd<Unsigned = U>, U>(
2777	multiplier: T,
2778	multiplicand: T,
2779	addend: T,
2780	carry: T,
2781	) -> (U, T) {
2782	multiplier.carrying_mul_add(multiplicand, addend, carry)
2783	}
2784
2785	/// Performs an exact division, resulting in undefined behavior where
2786	/// `x % y != 0` or `y == 0` or `x == T::MIN && y == -1`
2787	///
2788	/// This intrinsic does not have a stable counterpart.
2789	#[rustc_nounwind]
2790	#[rustc_intrinsic]
2791	pub const unsafe fn exact_div<T: Copy>(x: T, y: T) -> T;
2792
2793	/// Performs an unchecked division, resulting in undefined behavior
2794	/// where `y == 0` or `x == T::MIN && y == -1`
2795	///
2796	/// Safe wrappers for this intrinsic are available on the integer
2797	/// primitives via the `checked_div` method. For example,
2798	/// [`u32::checked_div`]
2799	#[rustc_intrinsic_const_stable_indirect]
2800	#[rustc_nounwind]
2801	#[rustc_intrinsic]
2802	pub const unsafe fn unchecked_div<T: Copy>(x: T, y: T) -> T;
2803	/// Returns the remainder of an unchecked division, resulting in
2804	/// undefined behavior when `y == 0` or `x == T::MIN && y == -1`
2805	///
2806	/// Safe wrappers for this intrinsic are available on the integer
2807	/// primitives via the `checked_rem` method. For example,
2808	/// [`u32::checked_rem`]
2809	#[rustc_intrinsic_const_stable_indirect]
2810	#[rustc_nounwind]
2811	#[rustc_intrinsic]
2812	pub const unsafe fn unchecked_rem<T: Copy>(x: T, y: T) -> T;
2813
2814	/// Performs an unchecked left shift, resulting in undefined behavior when
2815	/// `y < 0` or `y >= N`, where N is the width of T in bits.
2816	///
2817	/// Safe wrappers for this intrinsic are available on the integer
2818	/// primitives via the `checked_shl` method. For example,
2819	/// [`u32::checked_shl`]
2820	#[rustc_intrinsic_const_stable_indirect]
2821	#[rustc_nounwind]
2822	#[rustc_intrinsic]
2823	pub const unsafe fn unchecked_shl<T: Copy, U: Copy>(x: T, y: U) -> T;
2824	/// Performs an unchecked right shift, resulting in undefined behavior when
2825	/// `y < 0` or `y >= N`, where N is the width of T in bits.
2826	///
2827	/// Safe wrappers for this intrinsic are available on the integer
2828	/// primitives via the `checked_shr` method. For example,
2829	/// [`u32::checked_shr`]
2830	#[rustc_intrinsic_const_stable_indirect]
2831	#[rustc_nounwind]
2832	#[rustc_intrinsic]
2833	pub const unsafe fn unchecked_shr<T: Copy, U: Copy>(x: T, y: U) -> T;
2834
2835	/// Returns the result of an unchecked addition, resulting in
2836	/// undefined behavior when `x + y > T::MAX` or `x + y < T::MIN`.
2837	///
2838	/// The stable counterpart of this intrinsic is `unchecked_add` on the various
2839	/// integer types, such as [`u16::unchecked_add`] and [`i64::unchecked_add`].
2840	#[rustc_intrinsic_const_stable_indirect]
2841	#[rustc_nounwind]
2842	#[rustc_intrinsic]
2843	pub const unsafe fn unchecked_add<T: Copy>(x: T, y: T) -> T;
2844
2845	/// Returns the result of an unchecked subtraction, resulting in
2846	/// undefined behavior when `x - y > T::MAX` or `x - y < T::MIN`.
2847	///
2848	/// The stable counterpart of this intrinsic is `unchecked_sub` on the various
2849	/// integer types, such as [`u16::unchecked_sub`] and [`i64::unchecked_sub`].
2850	#[rustc_intrinsic_const_stable_indirect]
2851	#[rustc_nounwind]
2852	#[rustc_intrinsic]
2853	pub const unsafe fn unchecked_sub<T: Copy>(x: T, y: T) -> T;
2854
2855	/// Returns the result of an unchecked multiplication, resulting in
2856	/// undefined behavior when `x y > T::MAX` or `x * y < T::MIN`.*
2857	///
2858	/// The stable counterpart of this intrinsic is `unchecked_mul` on the various
2859	/// integer types, such as [`u16::unchecked_mul`] and [`i64::unchecked_mul`].
2860	#[rustc_intrinsic_const_stable_indirect]
2861	#[rustc_nounwind]
2862	#[rustc_intrinsic]
2863	pub const unsafe fn unchecked_mul<T: Copy>(x: T, y: T) -> T;
2864
2865	/// Performs rotate left.
2866	///
2867	/// Note that, unlike most intrinsics, this is safe to call;
2868	/// it does not require an `unsafe` block.
2869	/// Therefore, implementations must not require the user to uphold
2870	/// any safety invariants.
2871	///
2872	/// The stabilized versions of this intrinsic are available on the integer
2873	/// primitives via the `rotate_left` method. For example,
2874	/// [`u32::rotate_left`]
2875	#[rustc_intrinsic_const_stable_indirect]
2876	#[rustc_nounwind]
2877	#[rustc_intrinsic]
2878	pub const fn rotate_left<T: Copy>(x: T, shift: u32) -> T;
2879
2880	/// Performs rotate right.
2881	///
2882	/// Note that, unlike most intrinsics, this is safe to call;
2883	/// it does not require an `unsafe` block.
2884	/// Therefore, implementations must not require the user to uphold
2885	/// any safety invariants.
2886	///
2887	/// The stabilized versions of this intrinsic are available on the integer
2888	/// primitives via the `rotate_right` method. For example,
2889	/// [`u32::rotate_right`]
2890	#[rustc_intrinsic_const_stable_indirect]
2891	#[rustc_nounwind]
2892	#[rustc_intrinsic]
2893	pub const fn rotate_right<T: Copy>(x: T, shift: u32) -> T;
2894
2895	/// Returns (a + b) mod 2<sup>N</sup>, where N is the width of T in bits.
2896	///
2897	/// Note that, unlike most intrinsics, this is safe to call;
2898	/// it does not require an `unsafe` block.
2899	/// Therefore, implementations must not require the user to uphold
2900	/// any safety invariants.
2901	///
2902	/// The stabilized versions of this intrinsic are available on the integer
2903	/// primitives via the `wrapping_add` method. For example,
2904	/// [`u32::wrapping_add`]
2905	#[rustc_intrinsic_const_stable_indirect]
2906	#[rustc_nounwind]
2907	#[rustc_intrinsic]
2908	pub const fn wrapping_add<T: Copy>(a: T, b: T) -> T;
2909	/// Returns (a - b) mod 2<sup>N</sup>, where N is the width of T in bits.
2910	///
2911	/// Note that, unlike most intrinsics, this is safe to call;
2912	/// it does not require an `unsafe` block.
2913	/// Therefore, implementations must not require the user to uphold
2914	/// any safety invariants.
2915	///
2916	/// The stabilized versions of this intrinsic are available on the integer
2917	/// primitives via the `wrapping_sub` method. For example,
2918	/// [`u32::wrapping_sub`]
2919	#[rustc_intrinsic_const_stable_indirect]
2920	#[rustc_nounwind]
2921	#[rustc_intrinsic]
2922	pub const fn wrapping_sub<T: Copy>(a: T, b: T) -> T;
2923	/// Returns (a b) mod 2<sup>N</sup>, where N is the width of T in bits.*
2924	///
2925	/// Note that, unlike most intrinsics, this is safe to call;
2926	/// it does not require an `unsafe` block.
2927	/// Therefore, implementations must not require the user to uphold
2928	/// any safety invariants.
2929	///
2930	/// The stabilized versions of this intrinsic are available on the integer
2931	/// primitives via the `wrapping_mul` method. For example,
2932	/// [`u32::wrapping_mul`]
2933	#[rustc_intrinsic_const_stable_indirect]
2934	#[rustc_nounwind]
2935	#[rustc_intrinsic]
2936	pub const fn wrapping_mul<T: Copy>(a: T, b: T) -> T;
2937
2938	/// Computes `a + b`, saturating at numeric bounds.
2939	///
2940	/// Note that, unlike most intrinsics, this is safe to call;
2941	/// it does not require an `unsafe` block.
2942	/// Therefore, implementations must not require the user to uphold
2943	/// any safety invariants.
2944	///
2945	/// The stabilized versions of this intrinsic are available on the integer
2946	/// primitives via the `saturating_add` method. For example,
2947	/// [`u32::saturating_add`]
2948	#[rustc_intrinsic_const_stable_indirect]
2949	#[rustc_nounwind]
2950	#[rustc_intrinsic]
2951	pub const fn saturating_add<T: Copy>(a: T, b: T) -> T;
2952	/// Computes `a - b`, saturating at numeric bounds.
2953	///
2954	/// Note that, unlike most intrinsics, this is safe to call;
2955	/// it does not require an `unsafe` block.
2956	/// Therefore, implementations must not require the user to uphold
2957	/// any safety invariants.
2958	///
2959	/// The stabilized versions of this intrinsic are available on the integer
2960	/// primitives via the `saturating_sub` method. For example,
2961	/// [`u32::saturating_sub`]
2962	#[rustc_intrinsic_const_stable_indirect]
2963	#[rustc_nounwind]
2964	#[rustc_intrinsic]
2965	pub const fn saturating_sub<T: Copy>(a: T, b: T) -> T;
2966
2967	/// This is an implementation detail of [`crate::ptr::read`] and should
2968	/// not be used anywhere else. See its comments for why this exists.
2969	///
2970	/// This intrinsic can only* be called where the pointer is a local without*
2971	/// projections (`read_via_copy(ptr)`, not `read_via_copy(ptr)`) so that it*
2972	/// trivially obeys runtime-MIR rules about derefs in operands.
2973	#[rustc_intrinsic_const_stable_indirect]
2974	#[rustc_nounwind]
2975	#[rustc_intrinsic]
2976	pub const unsafe fn read_via_copy<T>(ptr: *const T) -> T;
2977
2978	/// This is an implementation detail of [`crate::ptr::write`] and should
2979	/// not be used anywhere else. See its comments for why this exists.
2980	///
2981	/// This intrinsic can only* be called where the pointer is a local without*
2982	/// projections (`write_via_move(ptr, x)`, not `write_via_move(ptr, x)`) so*
2983	/// that it trivially obeys runtime-MIR rules about derefs in operands.
2984	#[rustc_intrinsic_const_stable_indirect]
2985	#[rustc_nounwind]
2986	#[rustc_intrinsic]
2987	pub const unsafe fn write_via_move<T>(ptr: *mut T, value: T);
2988
2989	/// Returns the value of the discriminant for the variant in 'v';
2990	/// if `T` has no discriminant, returns `0`.
2991	///
2992	/// Note that, unlike most intrinsics, this is safe to call;
2993	/// it does not require an `unsafe` block.
2994	/// Therefore, implementations must not require the user to uphold
2995	/// any safety invariants.
2996	///
2997	/// The stabilized version of this intrinsic is [`core::mem::discriminant`].
2998	#[rustc_intrinsic_const_stable_indirect]
2999	#[rustc_nounwind]
3000	#[rustc_intrinsic]
3001	pub const fn discriminant_value<T>(v: &T) -> <T as DiscriminantKind>::Discriminant;
3002
3003	/// Rust's "try catch" construct for unwinding. Invokes the function pointer `try_fn` with the
3004	/// data pointer `data`, and calls `catch_fn` if unwinding occurs while `try_fn` runs.
3005	/// Returns `1` if unwinding occurred and `catch_fn` was called; returns `0` otherwise.
3006	///
3007	/// `catch_fn` must not unwind.
3008	///
3009	/// The third argument is a function called if an unwind occurs (both Rust `panic` and foreign
3010	/// unwinds). This function takes the data pointer and a pointer to the target- and
3011	/// runtime-specific exception object that was caught.
3012	///
3013	/// Note that in the case of a foreign unwinding operation, the exception object data may not be
3014	/// safely usable from Rust, and should not be directly exposed via the standard library. To
3015	/// prevent unsafe access, the library implementation may either abort the process or present an
3016	/// opaque error type to the user.
3017	///
3018	/// For more information, see the compiler's source, as well as the documentation for the stable
3019	/// version of this intrinsic, `std::panic::catch_unwind`.
3020	#[rustc_intrinsic]
3021	#[rustc_nounwind]
3022	pub unsafe fn catch_unwind(
3023	_try_fn: fn(*mut u8),
3024	_data: *mut u8,
3025	_catch_fn: fn(*mut u8, *mut u8),
3026	) -> i32;
3027
3028	/// Emits a `nontemporal` store, which gives a hint to the CPU that the data should not be held
3029	/// in cache. Except for performance, this is fully equivalent to `ptr.write(val)`.
3030	///
3031	/// Not all architectures provide such an operation. For instance, x86 does not: while `MOVNT`
3032	/// exists, that operation is not* equivalent to `ptr.write(val)` (`MOVNT` writes can be reordered*
3033	/// in ways that are not allowed for regular writes).
3034	#[rustc_intrinsic]
3035	#[rustc_nounwind]
3036	pub unsafe fn nontemporal_store<T>(ptr: *mut T, val: T);
3037
3038	/// See documentation of `<const T>::offset_from` for details.*
3039	#[rustc_intrinsic_const_stable_indirect]
3040	#[rustc_nounwind]
3041	#[rustc_intrinsic]
3042	pub const unsafe fn ptr_offset_from<T>(ptr: *const T, base: *const T) -> isize;
3043
3044	/// See documentation of `<const T>::sub_ptr` for details.*
3045	#[rustc_nounwind]
3046	#[rustc_intrinsic]
3047	#[rustc_intrinsic_const_stable_indirect]
3048	pub const unsafe fn ptr_offset_from_unsigned<T>(ptr: *const T, base: *const T) -> usize;
3049
3050	/// See documentation of `<const T>::guaranteed_eq` for details.*
3051	/// Returns `2` if the result is unknown.
3052	/// Returns `1` if the pointers are guaranteed equal.
3053	/// Returns `0` if the pointers are guaranteed inequal.
3054	#[rustc_intrinsic]
3055	#[rustc_nounwind]
3056	#[rustc_do_not_const_check]
3057	#[inline]
3058	#[miri::intrinsic_fallback_is_spec]
3059	pub const fn ptr_guaranteed_cmp<T>(ptr: *const T, other: *const T) -> u8 {
3060	(ptr == other) as u8
3061	}
3062
3063	/// Determines whether the raw bytes of the two values are equal.
3064	///
3065	/// This is particularly handy for arrays, since it allows things like just
3066	/// comparing `i96`s instead of forcing `alloca`s for `[6 x i16]`.
3067	///
3068	/// Above some backend-decided threshold this will emit calls to `memcmp`,
3069	/// like slice equality does, instead of causing massive code size.
3070	///
3071	/// Since this works by comparing the underlying bytes, the actual `T` is
3072	/// not particularly important. It will be used for its size and alignment,
3073	/// but any validity restrictions will be ignored, not enforced.
3074	///
3075	/// # Safety
3076	///
3077	/// It's UB to call this if any of the bytes* in `a` or `b` are uninitialized.*
3078	/// Note that this is a stricter criterion than just the values* being*
3079	/// fully-initialized: if `T` has padding, it's UB to call this intrinsic.
3080	///
3081	/// At compile-time, it is furthermore UB to call this if any of the bytes
3082	/// in `a` or `b` have provenance.
3083	///
3084	/// (The implementation is allowed to branch on the results of comparisons,
3085	/// which is UB if any of their inputs are `undef`.)
3086	#[rustc_nounwind]
3087	#[rustc_intrinsic]
3088	pub const unsafe fn raw_eq<T>(a: &T, b: &T) -> bool;
3089
3090	/// Lexicographically compare `[left, left + bytes)` and `[right, right + bytes)`
3091	/// as unsigned bytes, returning negative if `left` is less, zero if all the
3092	/// bytes match, or positive if `left` is greater.
3093	///
3094	/// This underlies things like `<[u8]>::cmp`, and will usually lower to `memcmp`.
3095	///
3096	/// # Safety
3097	///
3098	/// `left` and `right` must each be [valid] for reads of `bytes` bytes.
3099	///
3100	/// Note that this applies to the whole range, not just until the first byte
3101	/// that differs. That allows optimizations that can read in large chunks.
3102	///
3103	/// [valid]: crate::ptr#safety
3104	#[rustc_nounwind]
3105	#[rustc_intrinsic]
3106	pub const unsafe fn compare_bytes(left: *const u8, right: *const u8, bytes: usize) -> i32;
3107
3108	/// See documentation of [`std::hint::black_box`] for details.
3109	///
3110	/// [`std::hint::black_box`]: crate::hint::black_box
3111	#[rustc_nounwind]
3112	#[rustc_intrinsic]
3113	#[rustc_intrinsic_const_stable_indirect]
3114	pub const fn black_box<T>(dummy: T) -> T;
3115
3116	/// Selects which function to call depending on the context.
3117	///
3118	/// If this function is evaluated at compile-time, then a call to this
3119	/// intrinsic will be replaced with a call to `called_in_const`. It gets
3120	/// replaced with a call to `called_at_rt` otherwise.
3121	///
3122	/// This function is safe to call, but note the stability concerns below.
3123	///
3124	/// # Type Requirements
3125	///
3126	/// The two functions must be both function items. They cannot be function
3127	/// pointers or closures. The first function must be a `const fn`.
3128	///
3129	/// `arg` will be the tupled arguments that will be passed to either one of
3130	/// the two functions, therefore, both functions must accept the same type of
3131	/// arguments. Both functions must return RET.
3132	///
3133	/// # Stability concerns
3134	///
3135	/// Rust has not yet decided that `const fn` are allowed to tell whether
3136	/// they run at compile-time or at runtime. Therefore, when using this
3137	/// intrinsic anywhere that can be reached from stable, it is crucial that
3138	/// the end-to-end behavior of the stable `const fn` is the same for both
3139	/// modes of execution. (Here, Undefined Behavior is considered "the same"
3140	/// as any other behavior, so if the function exhibits UB at runtime then
3141	/// it may do whatever it wants at compile-time.)
3142	///
3143	/// Here is an example of how this could cause a problem:
3144	/// ```no_run
3145	/// #![feature(const_eval_select)]
3146	/// #![feature(core_intrinsics)]
3147	/// # #![allow(internal_features)]
3148	/// use std::intrinsics::const_eval_select;
3149	///
3150	/// // Standard library
3151	/// pub const fn inconsistent() -> i32 {
3152	/// fn runtime() -> i32 { `1` }
3153	/// const fn compiletime() -> i32 { `2` }
3154	///
3155	/// // ⚠ This code violates the required equivalence of `compiletime`
3156	/// // and `runtime`.
3157	/// const_eval_select((), compiletime, runtime)
3158	/// }
3159	///
3160	/// // User Crate
3161	/// const X: i32 = inconsistent();
3162	/// let x = inconsistent();
3163	/// assert_eq!(x, X);
3164	/// ```
3165	///
3166	/// Currently such an assertion would always succeed; until Rust decides
3167	/// otherwise, that principle should not be violated.
3168	#[rustc_const_unstable(feature = "const_eval_select", issue = "124625")]
3169	#[rustc_intrinsic]
3170	pub const fn const_eval_select<ARG: Tuple, F, G, RET>(
3171	_arg: ARG,
3172	_called_in_const: F,
3173	_called_at_rt: G,
3174	) -> RET
3175	where
3176	G: FnOnce<ARG, Output = RET>,
3177	F: FnOnce<ARG, Output = RET>;
3178
3179	/// A macro to make it easier to invoke const_eval_select. Use as follows:
3180	/// ```rust,ignore (just a macro example)
3181	/// const_eval_select!(
3182	/// @capture { arg1: i32 = some_expr, arg2: T = other_expr } -> U:
3183	/// if const #[attributes_for_const_arm] {
3184	/// // Compile-time code goes here.
3185	/// } else #[attributes_for_runtime_arm] {
3186	/// // Run-time code goes here.
3187	/// }
3188	/// )
3189	/// ```
3190	/// The `@capture` block declares which surrounding variables / expressions can be
3191	/// used inside the `if const`.
3192	/// Note that the two arms of this `if` really each become their own function, which is why the
3193	/// macro supports setting attributes for those functions. The runtime function is always
3194	/// markes as `#[inline]`.
3195	///
3196	/// See [`const_eval_select()`] for the rules and requirements around that intrinsic.
3197	pub(crate) macro const_eval_select {
3198	(
3199	@capture$([$($binders:tt)])? { $($arg:ident : $ty:ty = $val:expr), $(,)? } $( -> $ret:ty )? :
3200	if const
3201	$(#[$compiletime_attr:meta])* $compiletime:block
3202	else
3203	$(#[$runtime_attr:meta])* $runtime:block
3204	) => {
3205	// Use the `noinline` arm, after adding explicit `inline` attributes
3206	$crate::intrinsics::const_eval_select!(
3207	@capture$([$($binders)])? { $($arg : $ty = $val), } $(-> $ret)? :
3208	#[noinline]
3209	if const
3210	#[inline] // prevent codegen on this function
3211	$(#[$compiletime_attr])*
3212	$compiletime
3213	else
3214	#[inline] // avoid the overhead of an extra fn call
3215	$(#[$runtime_attr])*
3216	$runtime
3217	)
3218	},
3219	// With a leading #[noinline], we don't add inline attributes
3220	(
3221	@capture$([$($binders:tt)])? { $($arg:ident : $ty:ty = $val:expr), $(,)? } $( -> $ret:ty )? :
3222	#[noinline]
3223	if const
3224	$(#[$compiletime_attr:meta])* $compiletime:block
3225	else
3226	$(#[$runtime_attr:meta])* $runtime:block
3227	) => {{
3228	$(#[$runtime_attr])*
3229	fn runtime$(<$($binders)>)?($($arg: $ty),) $( -> $ret )? {
3230	$runtime
3231	}
3232
3233	$(#[$compiletime_attr])*
3234	const fn compiletime$(<$($binders)>)?($($arg: $ty),) $( -> $ret )? {
3235	// Don't warn if one of the arguments is unused.
3236	$(let _ = $arg;)*
3237
3238	$compiletime
3239	}
3240
3241	const_eval_select(($($val,)*), compiletime, runtime)
3242	}},
3243	// We support leaving away the `val` expressions for all* arguments*
3244	// (but not for some* arguments, that's too tricky).*
3245	(
3246	@capture$([$($binders:tt)])? { $($arg:ident : $ty:ty), $(,)? } $( -> $ret:ty )? :
3247	if const
3248	$(#[$compiletime_attr:meta])* $compiletime:block
3249	else
3250	$(#[$runtime_attr:meta])* $runtime:block
3251	) => {
3252	$crate::intrinsics::const_eval_select!(
3253	@capture$([$($binders)])? { $($arg : $ty = $arg), } $(-> $ret)? :
3254	if const
3255	$(#[$compiletime_attr])* $compiletime
3256	else
3257	$(#[$runtime_attr])* $runtime
3258	)
3259	},
3260	}
3261
3262	/// Returns whether the argument's value is statically known at
3263	/// compile-time.
3264	///
3265	/// This is useful when there is a way of writing the code that will
3266	/// be faster when some variables have known values, but slower
3267	/// in the general case: an `if is_val_statically_known(var)` can be used
3268	/// to select between these two variants. The `if` will be optimized away
3269	/// and only the desired branch remains.
3270	///
3271	/// Formally speaking, this function non-deterministically returns `true`
3272	/// or `false`, and the caller has to ensure sound behavior for both cases.
3273	/// In other words, the following code has Undefined Behavior:
3274	///
3275	/// ```no_run
3276	/// #![feature(core_intrinsics)]
3277	/// # #![allow(internal_features)]
3278	/// use std::hint::unreachable_unchecked;
3279	/// use std::intrinsics::is_val_statically_known;
3280	///
3281	/// if !is_val_statically_known(`0`) { unsafe { unreachable_unchecked(); } }
3282	/// ```
3283	///
3284	/// This also means that the following code's behavior is unspecified; it
3285	/// may panic, or it may not:
3286	///
3287	/// ```no_run
3288	/// #![feature(core_intrinsics)]
3289	/// # #![allow(internal_features)]
3290	/// use std::intrinsics::is_val_statically_known;
3291	///
3292	/// assert_eq!(is_val_statically_known(`0`), is_val_statically_known(`0`));
3293	/// ```
3294	///
3295	/// Unsafe code may not rely on `is_val_statically_known` returning any
3296	/// particular value, ever. However, the compiler will generally make it
3297	/// return `true` only if the value of the argument is actually known.
3298	///
3299	/// # Stability concerns
3300	///
3301	/// While it is safe to call, this intrinsic may behave differently in
3302	/// a `const` context than otherwise. See the [`const_eval_select()`]
3303	/// documentation for an explanation of the issues this can cause. Unlike
3304	/// `const_eval_select`, this intrinsic isn't guaranteed to behave
3305	/// deterministically even in a `const` context.
3306	///
3307	/// # Type Requirements
3308	///
3309	/// `T` must be either a `bool`, a `char`, a primitive numeric type (e.g. `f32`,
3310	/// but not `NonZeroISize`), or any thin pointer (e.g. `mut String`).*
3311	/// Any other argument types may* cause a compiler error.*
3312	///
3313	/// ## Pointers
3314	///
3315	/// When the input is a pointer, only the pointer itself is
3316	/// ever considered. The pointee has no effect. Currently, these functions
3317	/// behave identically:
3318	///
3319	/// ```
3320	/// #![feature(core_intrinsics)]
3321	/// # #![allow(internal_features)]
3322	/// use std::intrinsics::is_val_statically_known;
3323	///
3324	/// fn foo(x: &i32) -> bool {
3325	/// is_val_statically_known(x)
3326	/// }
3327	///
3328	/// fn bar(x: &i32) -> bool {
3329	/// is_val_statically_known(
3330	/// (x as *const i32).addr()
3331	/// )
3332	/// }
3333	/// # _ = foo(&`5_i32`);
3334	/// # _ = bar(&`5_i32`);
3335	/// ```
3336	#[rustc_const_stable_indirect]
3337	#[rustc_nounwind]
3338	#[unstable(feature = "core_intrinsics", issue = "none")]
3339	#[rustc_intrinsic]
3340	pub const fn is_val_statically_known<T: Copy>(_arg: T) -> bool {
3341	`false`
3342	}
3343
3344	/// Non-overlapping typed* swap of a single value.*
3345	///
3346	/// The codegen backends will replace this with a better implementation when
3347	/// `T` is a simple type that can be loaded and stored as an immediate.
3348	///
3349	/// The stabilized form of this intrinsic is [`crate::mem::swap`].
3350	///
3351	/// # Safety
3352	/// Behavior is undefined if any of the following conditions are violated:
3353	///
3354	/// Both `x` and `y` must be [valid] for both reads and writes.*
3355	///
3356	/// Both `x` and `y` must be properly aligned.*
3357	///
3358	/// The region of memory beginning at `x` must not overlap with the region of memory*
3359	/// beginning at `y`.
3360	///
3361	/// The memory pointed by `x` and `y` must both contain values of type `T`.*
3362	///
3363	/// [valid]: crate::ptr#safety
3364	#[rustc_nounwind]
3365	#[inline]
3366	#[rustc_intrinsic]
3367	#[rustc_intrinsic_const_stable_indirect]
3368	#[rustc_allow_const_fn_unstable(const_swap_nonoverlapping)] // this is anyway not called since CTFE implements the intrinsic
3369	pub const unsafe fn typed_swap_nonoverlapping<T>(x: *mut T, y: *mut T) {
3370	// SAFETY: The caller provided single non-overlapping items behind
3371	// pointers, so swapping them with `count: 1` is fine.
3372	unsafe { ptr::swap_nonoverlapping(x, y, count:`1`) };
3373	}
3374
3375	/// Returns whether we should perform some UB-checking at runtime. This eventually evaluates to
3376	/// `cfg!(ub_checks)`, but behaves different from `cfg!` when mixing crates built with different
3377	/// flags: if the crate has UB checks enabled or carries the `#[rustc_preserve_ub_checks]`
3378	/// attribute, evaluation is delayed until monomorphization (or until the call gets inlined into
3379	/// a crate that does not delay evaluation further); otherwise it can happen any time.
3380	///
3381	/// The common case here is a user program built with ub_checks linked against the distributed
3382	/// sysroot which is built without ub_checks but with `#[rustc_preserve_ub_checks]`.
3383	/// For code that gets monomorphized in the user crate (i.e., generic functions and functions with
3384	/// `#[inline]`), gating assertions on `ub_checks()` rather than `cfg!(ub_checks)` means that
3385	/// assertions are enabled whenever the user crate* has UB checks enabled. However, if the*
3386	/// user has UB checks disabled, the checks will still get optimized out. This intrinsic is
3387	/// primarily used by [`ub_checks::assert_unsafe_precondition`].
3388	#[rustc_intrinsic_const_stable_indirect] // just for UB checks
3389	#[inline(always)]
3390	#[rustc_intrinsic]
3391	pub const fn ub_checks() -> bool {
3392	cfg!(ub_checks)
3393	}
3394
3395	/// Allocates a block of memory at compile time.
3396	/// At runtime, just returns a null pointer.
3397	///
3398	/// # Safety
3399	///
3400	/// - The `align` argument must be a power of two.
3401	/// - At compile time, a compile error occurs if this constraint is violated.
3402	/// - At runtime, it is not checked.
3403	#[rustc_const_unstable(feature = "const_heap", issue = "79597")]
3404	#[rustc_nounwind]
3405	#[rustc_intrinsic]
3406	#[miri::intrinsic_fallback_is_spec]
3407	pub const unsafe fn const_allocate(_size: usize, _align: usize) -> *mut u8 {
3408	// const eval overrides this function, but runtime code for now just returns null pointers.
3409	// See <https://github.com/rust-lang/rust/issues/93935>.
3410	crate::ptr::null_mut()
3411	}
3412
3413	/// Deallocates a memory which allocated by `intrinsics::const_allocate` at compile time.
3414	/// At runtime, does nothing.
3415	///
3416	/// # Safety
3417	///
3418	/// - The `align` argument must be a power of two.
3419	/// - At compile time, a compile error occurs if this constraint is violated.
3420	/// - At runtime, it is not checked.
3421	/// - If the `ptr` is created in an another const, this intrinsic doesn't deallocate it.
3422	/// - If the `ptr` is pointing to a local variable, this intrinsic doesn't deallocate it.
3423	#[rustc_const_unstable(feature = "const_heap", issue = "79597")]
3424	#[unstable(feature = "core_intrinsics", issue = "none")]
3425	#[rustc_nounwind]
3426	#[rustc_intrinsic]
3427	#[miri::intrinsic_fallback_is_spec]
3428	pub const unsafe fn const_deallocate(_ptr: *mut u8, _size: usize, _align: usize) {
3429	// Runtime NOP
3430	}
3431
3432	/// Returns whether we should perform contract-checking at runtime.
3433	///
3434	/// This is meant to be similar to the ub_checks intrinsic, in terms
3435	/// of not prematurely commiting at compile-time to whether contract
3436	/// checking is turned on, so that we can specify contracts in libstd
3437	/// and let an end user opt into turning them on.
3438	#[rustc_const_unstable(feature = "contracts_internals", issue = "128044" / compiler-team#759 /)]
3439	#[unstable(feature = "contracts_internals", issue = "128044" / compiler-team#759 /)]
3440	#[inline(always)]
3441	#[rustc_intrinsic]
3442	pub const fn contract_checks() -> bool {
3443	// FIXME: should this be `false` or `cfg!(contract_checks)`?
3444
3445	// cfg!(contract_checks)
3446	`false`
3447	}
3448
3449	/// Check if the pre-condition `cond` has been met.
3450	///
3451	/// By default, if `contract_checks` is enabled, this will panic with no unwind if the condition
3452	/// returns false.
3453	#[unstable(feature = "contracts_internals", issue = "128044" / compiler-team#759 /)]
3454	#[lang = "contract_check_requires"]
3455	#[rustc_intrinsic]
3456	pub fn contract_check_requires<C: Fn() -> bool>(cond: C) {
3457	if contract_checks() && !cond() {
3458	// Emit no unwind panic in case this was a safety requirement.
3459	crate::panicking::panic_nounwind(expr:"failed requires check");
3460	}
3461	}
3462
3463	/// Check if the post-condition `cond` has been met.
3464	///
3465	/// By default, if `contract_checks` is enabled, this will panic with no unwind if the condition
3466	/// returns false.
3467	#[unstable(feature = "contracts_internals", issue = "128044" / compiler-team#759 /)]
3468	#[rustc_intrinsic]
3469	pub fn contract_check_ensures<'a, Ret, C: Fn(&'a Ret) -> bool>(ret: &'a Ret, cond: C) {
3470	if contract_checks() && !cond(ret) {
3471	crate::panicking::panic_nounwind(expr:"failed ensures check");
3472	}
3473	}
3474
3475	/// The intrinsic will return the size stored in that vtable.
3476	///
3477	/// # Safety
3478	///
3479	/// `ptr` must point to a vtable.
3480	#[rustc_nounwind]
3481	#[unstable(feature = "core_intrinsics", issue = "none")]
3482	#[rustc_intrinsic]
3483	pub unsafe fn vtable_size(ptr: *const ()) -> usize;
3484
3485	/// The intrinsic will return the alignment stored in that vtable.
3486	///
3487	/// # Safety
3488	///
3489	/// `ptr` must point to a vtable.
3490	#[rustc_nounwind]
3491	#[unstable(feature = "core_intrinsics", issue = "none")]
3492	#[rustc_intrinsic]
3493	pub unsafe fn vtable_align(ptr: *const ()) -> usize;
3494
3495	/// The size of a type in bytes.
3496	///
3497	/// Note that, unlike most intrinsics, this is safe to call;
3498	/// it does not require an `unsafe` block.
3499	/// Therefore, implementations must not require the user to uphold
3500	/// any safety invariants.
3501	///
3502	/// More specifically, this is the offset in bytes between successive
3503	/// items of the same type, including alignment padding.
3504	///
3505	/// The stabilized version of this intrinsic is [`size_of`].
3506	#[rustc_nounwind]
3507	#[unstable(feature = "core_intrinsics", issue = "none")]
3508	#[rustc_intrinsic_const_stable_indirect]
3509	#[rustc_intrinsic]
3510	pub const fn size_of<T>() -> usize;
3511
3512	/// The minimum alignment of a type.
3513	///
3514	/// Note that, unlike most intrinsics, this is safe to call;
3515	/// it does not require an `unsafe` block.
3516	/// Therefore, implementations must not require the user to uphold
3517	/// any safety invariants.
3518	///
3519	/// The stabilized version of this intrinsic is [`align_of`].
3520	#[rustc_nounwind]
3521	#[unstable(feature = "core_intrinsics", issue = "none")]
3522	#[rustc_intrinsic_const_stable_indirect]
3523	#[rustc_intrinsic]
3524	pub const fn min_align_of<T>() -> usize;
3525
3526	/// The preferred alignment of a type.
3527	///
3528	/// This intrinsic does not have a stable counterpart.
3529	/// It's "tracking issue" is [#91971](https://github.com/rust-lang/rust/issues/91971).
3530	#[rustc_nounwind]
3531	#[unstable(feature = "core_intrinsics", issue = "none")]
3532	#[rustc_intrinsic]
3533	pub const unsafe fn pref_align_of<T>() -> usize;
3534
3535	/// Returns the number of variants of the type `T` cast to a `usize`;
3536	/// if `T` has no variants, returns `0`. Uninhabited variants will be counted.
3537	///
3538	/// Note that, unlike most intrinsics, this is safe to call;
3539	/// it does not require an `unsafe` block.
3540	/// Therefore, implementations must not require the user to uphold
3541	/// any safety invariants.
3542	///
3543	/// The to-be-stabilized version of this intrinsic is [`crate::mem::variant_count`].
3544	#[rustc_nounwind]
3545	#[unstable(feature = "core_intrinsics", issue = "none")]
3546	#[rustc_intrinsic]
3547	pub const fn variant_count<T>() -> usize;
3548
3549	/// The size of the referenced value in bytes.
3550	///
3551	/// The stabilized version of this intrinsic is [`size_of_val`].
3552	///
3553	/// # Safety
3554	///
3555	/// See [`crate::mem::size_of_val_raw`] for safety conditions.
3556	#[rustc_nounwind]
3557	#[unstable(feature = "core_intrinsics", issue = "none")]
3558	#[rustc_intrinsic]
3559	#[rustc_intrinsic_const_stable_indirect]
3560	pub const unsafe fn size_of_val<T: ?Sized>(ptr: *const T) -> usize;
3561
3562	/// The required alignment of the referenced value.
3563	///
3564	/// The stabilized version of this intrinsic is [`align_of_val`].
3565	///
3566	/// # Safety
3567	///
3568	/// See [`crate::mem::align_of_val_raw`] for safety conditions.
3569	#[rustc_nounwind]
3570	#[unstable(feature = "core_intrinsics", issue = "none")]
3571	#[rustc_intrinsic]
3572	#[rustc_intrinsic_const_stable_indirect]
3573	pub const unsafe fn min_align_of_val<T: ?Sized>(ptr: *const T) -> usize;
3574
3575	/// Gets a static string slice containing the name of a type.
3576	///
3577	/// Note that, unlike most intrinsics, this is safe to call;
3578	/// it does not require an `unsafe` block.
3579	/// Therefore, implementations must not require the user to uphold
3580	/// any safety invariants.
3581	///
3582	/// The stabilized version of this intrinsic is [`core::any::type_name`].
3583	#[rustc_nounwind]
3584	#[unstable(feature = "core_intrinsics", issue = "none")]
3585	#[rustc_intrinsic]
3586	pub const fn type_name<T: ?Sized>() -> &'static str;
3587
3588	/// Gets an identifier which is globally unique to the specified type. This
3589	/// function will return the same value for a type regardless of whichever
3590	/// crate it is invoked in.
3591	///
3592	/// Note that, unlike most intrinsics, this is safe to call;
3593	/// it does not require an `unsafe` block.
3594	/// Therefore, implementations must not require the user to uphold
3595	/// any safety invariants.
3596	///
3597	/// The stabilized version of this intrinsic is [`core::any::TypeId::of`].
3598	#[rustc_nounwind]
3599	#[unstable(feature = "core_intrinsics", issue = "none")]
3600	#[rustc_intrinsic]
3601	pub const fn type_id<T: ?Sized + 'static>() -> u128;
3602
3603	/// Lowers in MIR to `Rvalue::Aggregate` with `AggregateKind::RawPtr`.
3604	///
3605	/// This is used to implement functions like `slice::from_raw_parts_mut` and
3606	/// `ptr::from_raw_parts` in a way compatible with the compiler being able to
3607	/// change the possible layouts of pointers.
3608	#[rustc_nounwind]
3609	#[unstable(feature = "core_intrinsics", issue = "none")]
3610	#[rustc_intrinsic_const_stable_indirect]
3611	#[rustc_intrinsic]
3612	pub const fn aggregate_raw_ptr<P: AggregateRawPtr<D, Metadata = M>, D, M>(data: D, meta: M) -> P;
3613
3614	#[unstable(feature = "core_intrinsics", issue = "none")]
3615	pub trait AggregateRawPtr<D> {
3616	type Metadata: Copy;
3617	}
3618	impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*const T> for *const P {
3619	type Metadata = <P as ptr::Pointee>::Metadata;
3620	}
3621	impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*mut T> for *mut P {
3622	type Metadata = <P as ptr::Pointee>::Metadata;
3623	}
3624
3625	/// Lowers in MIR to `Rvalue::UnaryOp` with `UnOp::PtrMetadata`.
3626	///
3627	/// This is used to implement functions like `ptr::metadata`.
3628	#[rustc_nounwind]
3629	#[unstable(feature = "core_intrinsics", issue = "none")]
3630	#[rustc_intrinsic_const_stable_indirect]
3631	#[rustc_intrinsic]
3632	pub const fn ptr_metadata<P: ptr::Pointee<Metadata = M> + ?Sized, M>(ptr: *const P) -> M;
3633
3634	// Some functions are defined here because they accidentally got made
3635	// available in this module on stable. See <https://github.com/rust-lang/rust/issues/15702>.
3636	// (`transmute` also falls into this category, but it cannot be wrapped due to the
3637	// check that `T` and `U` have the same size.)
3638
3639	/// Copies `count size_of::<T>()` bytes from `src` to `dst`. The source*
3640	/// and destination must not* overlap.*
3641	///
3642	/// For regions of memory which might overlap, use [`copy`] instead.
3643	///
3644	/// `copy_nonoverlapping` is semantically equivalent to C's [`memcpy`], but
3645	/// with the source and destination arguments swapped,
3646	/// and `count` counting the number of `T`s instead of bytes.
3647	///
3648	/// The copy is "untyped" in the sense that data may be uninitialized or otherwise violate the
3649	/// requirements of `T`. The initialization state is preserved exactly.
3650	///
3651	/// [`memcpy`]: https://en.cppreference.com/w/c/string/byte/memcpy
3652	///
3653	/// # Safety
3654	///
3655	/// Behavior is undefined if any of the following conditions are violated:
3656	///
3657	/// `src` must be [valid] for reads of `count * size_of::<T>()` bytes.*
3658	///
3659	/// `dst` must be [valid] for writes of `count * size_of::<T>()` bytes.*
3660	///
3661	/// Both `src` and `dst` must be properly aligned.*
3662	///
3663	/// * The region of memory beginning at `src` with a size of `count *
3664	/// size_of::<T>()` bytes must not* overlap with the region of memory*
3665	/// beginning at `dst` with the same size.
3666	///
3667	/// Like [`read`], `copy_nonoverlapping` creates a bitwise copy of `T`, regardless of
3668	/// whether `T` is [`Copy`]. If `T` is not [`Copy`], using both* the values*
3669	/// in the region beginning at `src` and the region beginning at `dst` can
3670	/// [violate memory safety][read-ownership].
3671	///
3672	/// Note that even if the effectively copied size (`count size_of::<T>()`) is*
3673	/// `0`, the pointers must be properly aligned.
3674	///
3675	/// [`read`]: crate::ptr::read
3676	/// [read-ownership]: crate::ptr::read#ownership-of-the-returned-value
3677	/// [valid]: crate::ptr#safety
3678	///
3679	/// # Examples
3680	///
3681	/// Manually implement [`Vec::append`]:
3682	///
3683	/// ```
3684	/// use std::ptr;
3685	///
3686	/// /// Moves all the elements of `src` into `dst`, leaving `src` empty.
3687	/// fn append<T>(dst: &mut Vec<T>, src: &mut Vec<T>) {
3688	/// let src_len = src.len();
3689	/// let dst_len = dst.len();
3690	///
3691	/// // Ensure that `dst` has enough capacity to hold all of `src`.
3692	/// dst.reserve(src_len);
3693	///
3694	/// unsafe {
3695	/// // The call to add is always safe because `Vec` will never
3696	/// // allocate more than `isize::MAX` bytes.
3697	/// let dst_ptr = dst.as_mut_ptr().add(dst_len);
3698	/// let src_ptr = src.as_ptr();
3699	///
3700	/// // Truncate `src` without dropping its contents. We do this first,
3701	/// // to avoid problems in case something further down panics.
3702	/// src.set_len(`0`);
3703	///
3704	/// // The two regions cannot overlap because mutable references do
3705	/// // not alias, and two different vectors cannot own the same
3706	/// // memory.
3707	/// ptr::copy_nonoverlapping(src_ptr, dst_ptr, src_len);
3708	///
3709	/// // Notify `dst` that it now holds the contents of `src`.
3710	/// dst.set_len(dst_len + src_len);
3711	/// }
3712	/// }
3713	///
3714	/// let mut a = vec!['r'];
3715	/// let mut b = vec!['u', 's', 't'];
3716	///
3717	/// append(&mut a, &mut b);
3718	///
3719	/// assert_eq!(a, &['r', 'u', 's', 't']);
3720	/// assert!(b.is_empty());
3721	/// ```
3722	///
3723	/// [`Vec::append`]: ../../std/vec/struct.Vec.html#method.append
3724	#[doc(alias = "memcpy")]
3725	#[stable(feature = "rust1", since = "1.0.0")]
3726	#[rustc_allowed_through_unstable_modules = "import this function via `std::mem` instead"]
3727	#[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
3728	#[inline(always)]
3729	#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
3730	#[rustc_diagnostic_item = "ptr_copy_nonoverlapping"]
3731	pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
3732	#[rustc_intrinsic_const_stable_indirect]
3733	#[rustc_nounwind]
3734	#[rustc_intrinsic]
3735	const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
3736
3737	ub_checks::assert_unsafe_precondition!(
3738	check_language_ub,
3739	"ptr::copy_nonoverlapping requires that both pointer arguments are aligned and non-null \
3740	and the specified memory ranges do not overlap",
3741	(
3742	src: *const () = src as *const (),
3743	dst: *mut () = dst as *mut (),
3744	size: usize = size_of::<T>(),
3745	align: usize = align_of::<T>(),
3746	count: usize = count,
3747	) => {
3748	let zero_size = count == `0` \|\| size == `0`;
3749	ub_checks::maybe_is_aligned_and_not_null(src, align, zero_size)
3750	&& ub_checks::maybe_is_aligned_and_not_null(dst, align, zero_size)
3751	&& ub_checks::maybe_is_nonoverlapping(src, dst, size, count)
3752	}
3753	);
3754
3755	// SAFETY: the safety contract for `copy_nonoverlapping` must be
3756	// upheld by the caller.
3757	unsafe { copy_nonoverlapping(src, dst, count) }
3758	}
3759
3760	/// Copies `count size_of::<T>()` bytes from `src` to `dst`. The source*
3761	/// and destination may overlap.
3762	///
3763	/// If the source and destination will never* overlap,*
3764	/// [`copy_nonoverlapping`] can be used instead.
3765	///
3766	/// `copy` is semantically equivalent to C's [`memmove`], but
3767	/// with the source and destination arguments swapped,
3768	/// and `count` counting the number of `T`s instead of bytes.
3769	/// Copying takes place as if the bytes were copied from `src`
3770	/// to a temporary array and then copied from the array to `dst`.
3771	///
3772	/// The copy is "untyped" in the sense that data may be uninitialized or otherwise violate the
3773	/// requirements of `T`. The initialization state is preserved exactly.
3774	///
3775	/// [`memmove`]: https://en.cppreference.com/w/c/string/byte/memmove
3776	///
3777	/// # Safety
3778	///
3779	/// Behavior is undefined if any of the following conditions are violated:
3780	///
3781	/// `src` must be [valid] for reads of `count * size_of::<T>()` bytes.*
3782	///
3783	/// `dst` must be [valid] for writes of `count * size_of::<T>()` bytes, and must remain valid even*
3784	/// when `src` is read for `count size_of::<T>()` bytes. (This means if the memory ranges*
3785	/// overlap, the `dst` pointer must not be invalidated by `src` reads.)
3786	///
3787	/// Both `src` and `dst` must be properly aligned.*
3788	///
3789	/// Like [`read`], `copy` creates a bitwise copy of `T`, regardless of
3790	/// whether `T` is [`Copy`]. If `T` is not [`Copy`], using both the values
3791	/// in the region beginning at `src` and the region beginning at `dst` can
3792	/// [violate memory safety][read-ownership].
3793	///
3794	/// Note that even if the effectively copied size (`count size_of::<T>()`) is*
3795	/// `0`, the pointers must be properly aligned.
3796	///
3797	/// [`read`]: crate::ptr::read
3798	/// [read-ownership]: crate::ptr::read#ownership-of-the-returned-value
3799	/// [valid]: crate::ptr#safety
3800	///
3801	/// # Examples
3802	///
3803	/// Efficiently create a Rust vector from an unsafe buffer:
3804	///
3805	/// ```
3806	/// use std::ptr;
3807	///
3808	/// /// # Safety
3809	/// ///
3810	/// /// `ptr` must be correctly aligned for its type and non-zero.*
3811	/// /// `ptr` must be valid for reads of `elts` contiguous elements of type `T`.*
3812	/// /// Those elements must not be used after calling this function unless `T: Copy`.*
3813	/// # #[allow(dead_code)]
3814	/// unsafe fn from_buf_raw<T>(ptr: *const T, elts: usize) -> Vec<T> {
3815	/// let mut dst = Vec::with_capacity(elts);
3816	///
3817	/// // SAFETY: Our precondition ensures the source is aligned and valid,
3818	/// // and `Vec::with_capacity` ensures that we have usable space to write them.
3819	/// unsafe { ptr::copy(ptr, dst.as_mut_ptr(), elts); }
3820	///
3821	/// // SAFETY: We created it with this much capacity earlier,
3822	/// // and the previous `copy` has initialized these elements.
3823	/// unsafe { dst.set_len(elts); }
3824	/// dst
3825	/// }
3826	/// ```
3827	#[doc(alias = "memmove")]
3828	#[stable(feature = "rust1", since = "1.0.0")]
3829	#[rustc_allowed_through_unstable_modules = "import this function via `std::mem` instead"]
3830	#[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
3831	#[inline(always)]
3832	#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
3833	#[rustc_diagnostic_item = "ptr_copy"]
3834	pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
3835	#[rustc_intrinsic_const_stable_indirect]
3836	#[rustc_nounwind]
3837	#[rustc_intrinsic]
3838	const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize);
3839
3840	// SAFETY: the safety contract for `copy` must be upheld by the caller.
3841	unsafe {
3842	ub_checks::assert_unsafe_precondition!(
3843	check_language_ub,
3844	"ptr::copy requires that both pointer arguments are aligned and non-null",
3845	(
3846	src: *const () = src as *const (),
3847	dst: *mut () = dst as *mut (),
3848	align: usize = align_of::<T>(),
3849	zero_size: bool = T::IS_ZST \|\| count == `0`,
3850	) =>
3851	ub_checks::maybe_is_aligned_and_not_null(src, align, zero_size)
3852	&& ub_checks::maybe_is_aligned_and_not_null(dst, align, zero_size)
3853	);
3854	copy(src, dst, count)
3855	}
3856	}
3857
3858	/// Sets `count size_of::<T>()` bytes of memory starting at `dst` to*
3859	/// `val`.
3860	///
3861	/// `write_bytes` is similar to C's [`memset`], but sets `count *
3862	/// size_of::<T>()` bytes to `val`.
3863	///
3864	/// [`memset`]: https://en.cppreference.com/w/c/string/byte/memset
3865	///
3866	/// # Safety
3867	///
3868	/// Behavior is undefined if any of the following conditions are violated:
3869	///
3870	/// `dst` must be [valid] for writes of `count * size_of::<T>()` bytes.*
3871	///
3872	/// `dst` must be properly aligned.*
3873	///
3874	/// Note that even if the effectively copied size (`count size_of::<T>()`) is*
3875	/// `0`, the pointer must be properly aligned.
3876	///
3877	/// Additionally, note that changing `dst` in this way can easily lead to undefined behavior (UB)*
3878	/// later if the written bytes are not a valid representation of some `T`. For instance, the
3879	/// following is an incorrect* use of this function:*
3880	///
3881	/// ```rust,no_run
3882	/// unsafe {
3883	/// let mut value: u8 = `0`;
3884	/// let ptr: *mut bool = &mut value as *mut u8 as *mut bool;
3885	/// let _bool = ptr.read(); // This is fine, `ptr` points to a valid `bool`.
3886	/// ptr.write_bytes(`42u8`, `1`); // This function itself does not cause UB...
3887	/// let _bool = ptr.read(); // ...but it makes this operation UB! ⚠️
3888	/// }
3889	/// ```
3890	///
3891	/// [valid]: crate::ptr#safety
3892	///
3893	/// # Examples
3894	///
3895	/// Basic usage:
3896	///
3897	/// ```
3898	/// use std::ptr;
3899	///
3900	/// let mut vec = vec![`0u32`; `4`];
3901	/// unsafe {
3902	/// let vec_ptr = vec.as_mut_ptr();
3903	/// ptr::write_bytes(vec_ptr, `0xfe`, `2`);
3904	/// }
3905	/// assert_eq!(vec, [`0xfefefefe`, `0xfefefefe`, `0`, `0`]);
3906	/// ```
3907	#[doc(alias = "memset")]
3908	#[stable(feature = "rust1", since = "1.0.0")]
3909	#[rustc_allowed_through_unstable_modules = "import this function via `std::mem` instead"]
3910	#[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
3911	#[inline(always)]
3912	#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
3913	#[rustc_diagnostic_item = "ptr_write_bytes"]
3914	pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
3915	#[rustc_intrinsic_const_stable_indirect]
3916	#[rustc_nounwind]
3917	#[rustc_intrinsic]
3918	const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
3919
3920	// SAFETY: the safety contract for `write_bytes` must be upheld by the caller.
3921	unsafe {
3922	ub_checks::assert_unsafe_precondition!(
3923	check_language_ub,
3924	"ptr::write_bytes requires that the destination pointer is aligned and non-null",
3925	(
3926	addr: *const () = dst as *const (),
3927	align: usize = align_of::<T>(),
3928	zero_size: bool = T::IS_ZST \|\| count == `0`,
3929	) => ub_checks::maybe_is_aligned_and_not_null(addr, align, zero_size)
3930	);
3931	write_bytes(dst, val, count)
3932	}
3933	}
3934
3935	/// Returns the minimum of two `f16` values.
3936	///
3937	/// Note that, unlike most intrinsics, this is safe to call;
3938	/// it does not require an `unsafe` block.
3939	/// Therefore, implementations must not require the user to uphold
3940	/// any safety invariants.
3941	///
3942	/// The stabilized version of this intrinsic is
3943	/// [`f16::min`]
3944	#[rustc_nounwind]
3945	#[rustc_intrinsic]
3946	pub const fn minnumf16(x: f16, y: f16) -> f16;
3947
3948	/// Returns the minimum of two `f32` values.
3949	///
3950	/// Note that, unlike most intrinsics, this is safe to call;
3951	/// it does not require an `unsafe` block.
3952	/// Therefore, implementations must not require the user to uphold
3953	/// any safety invariants.
3954	///
3955	/// The stabilized version of this intrinsic is
3956	/// [`f32::min`]
3957	#[rustc_nounwind]
3958	#[rustc_intrinsic_const_stable_indirect]
3959	#[rustc_intrinsic]
3960	pub const fn minnumf32(x: f32, y: f32) -> f32;
3961
3962	/// Returns the minimum of two `f64` values.
3963	///
3964	/// Note that, unlike most intrinsics, this is safe to call;
3965	/// it does not require an `unsafe` block.
3966	/// Therefore, implementations must not require the user to uphold
3967	/// any safety invariants.
3968	///
3969	/// The stabilized version of this intrinsic is
3970	/// [`f64::min`]
3971	#[rustc_nounwind]
3972	#[rustc_intrinsic_const_stable_indirect]
3973	#[rustc_intrinsic]
3974	pub const fn minnumf64(x: f64, y: f64) -> f64;
3975
3976	/// Returns the minimum of two `f128` values.
3977	///
3978	/// Note that, unlike most intrinsics, this is safe to call;
3979	/// it does not require an `unsafe` block.
3980	/// Therefore, implementations must not require the user to uphold
3981	/// any safety invariants.
3982	///
3983	/// The stabilized version of this intrinsic is
3984	/// [`f128::min`]
3985	#[rustc_nounwind]
3986	#[rustc_intrinsic]
3987	pub const fn minnumf128(x: f128, y: f128) -> f128;
3988
3989	/// Returns the maximum of two `f16` values.
3990	///
3991	/// Note that, unlike most intrinsics, this is safe to call;
3992	/// it does not require an `unsafe` block.
3993	/// Therefore, implementations must not require the user to uphold
3994	/// any safety invariants.
3995	///
3996	/// The stabilized version of this intrinsic is
3997	/// [`f16::max`]
3998	#[rustc_nounwind]
3999	#[rustc_intrinsic]
4000	pub const fn maxnumf16(x: f16, y: f16) -> f16;
4001
4002	/// Returns the maximum of two `f32` values.
4003	///
4004	/// Note that, unlike most intrinsics, this is safe to call;
4005	/// it does not require an `unsafe` block.
4006	/// Therefore, implementations must not require the user to uphold
4007	/// any safety invariants.
4008	///
4009	/// The stabilized version of this intrinsic is
4010	/// [`f32::max`]
4011	#[rustc_nounwind]
4012	#[rustc_intrinsic_const_stable_indirect]
4013	#[rustc_intrinsic]
4014	pub const fn maxnumf32(x: f32, y: f32) -> f32;
4015
4016	/// Returns the maximum of two `f64` values.
4017	///
4018	/// Note that, unlike most intrinsics, this is safe to call;
4019	/// it does not require an `unsafe` block.
4020	/// Therefore, implementations must not require the user to uphold
4021	/// any safety invariants.
4022	///
4023	/// The stabilized version of this intrinsic is
4024	/// [`f64::max`]
4025	#[rustc_nounwind]
4026	#[rustc_intrinsic_const_stable_indirect]
4027	#[rustc_intrinsic]
4028	pub const fn maxnumf64(x: f64, y: f64) -> f64;
4029
4030	/// Returns the maximum of two `f128` values.
4031	///
4032	/// Note that, unlike most intrinsics, this is safe to call;
4033	/// it does not require an `unsafe` block.
4034	/// Therefore, implementations must not require the user to uphold
4035	/// any safety invariants.
4036	///
4037	/// The stabilized version of this intrinsic is
4038	/// [`f128::max`]
4039	#[rustc_nounwind]
4040	#[rustc_intrinsic]
4041	pub const fn maxnumf128(x: f128, y: f128) -> f128;
4042
4043	/// Returns the absolute value of an `f16`.
4044	///
4045	/// The stabilized version of this intrinsic is
4046	/// [`f16::abs`](../../std/primitive.f16.html#method.abs)
4047	#[rustc_nounwind]
4048	#[rustc_intrinsic]
4049	pub const unsafe fn fabsf16(x: f16) -> f16;
4050
4051	/// Returns the absolute value of an `f32`.
4052	///
4053	/// The stabilized version of this intrinsic is
4054	/// [`f32::abs`](../../std/primitive.f32.html#method.abs)
4055	#[rustc_nounwind]
4056	#[rustc_intrinsic_const_stable_indirect]
4057	#[rustc_intrinsic]
4058	pub const unsafe fn fabsf32(x: f32) -> f32;
4059
4060	/// Returns the absolute value of an `f64`.
4061	///
4062	/// The stabilized version of this intrinsic is
4063	/// [`f64::abs`](../../std/primitive.f64.html#method.abs)
4064	#[rustc_nounwind]
4065	#[rustc_intrinsic_const_stable_indirect]
4066	#[rustc_intrinsic]
4067	pub const unsafe fn fabsf64(x: f64) -> f64;
4068
4069	/// Returns the absolute value of an `f128`.
4070	///
4071	/// The stabilized version of this intrinsic is
4072	/// [`f128::abs`](../../std/primitive.f128.html#method.abs)
4073	#[rustc_nounwind]
4074	#[rustc_intrinsic]
4075	pub const unsafe fn fabsf128(x: f128) -> f128;
4076
4077	/// Copies the sign from `y` to `x` for `f16` values.
4078	///
4079	/// The stabilized version of this intrinsic is
4080	/// [`f16::copysign`](../../std/primitive.f16.html#method.copysign)
4081	#[rustc_nounwind]
4082	#[rustc_intrinsic]
4083	pub const unsafe fn copysignf16(x: f16, y: f16) -> f16;
4084
4085	/// Copies the sign from `y` to `x` for `f32` values.
4086	///
4087	/// The stabilized version of this intrinsic is
4088	/// [`f32::copysign`](../../std/primitive.f32.html#method.copysign)
4089	#[rustc_nounwind]
4090	#[rustc_intrinsic_const_stable_indirect]
4091	#[rustc_intrinsic]
4092	pub const unsafe fn copysignf32(x: f32, y: f32) -> f32;
4093	/// Copies the sign from `y` to `x` for `f64` values.
4094	///
4095	/// The stabilized version of this intrinsic is
4096	/// [`f64::copysign`](../../std/primitive.f64.html#method.copysign)
4097	#[rustc_nounwind]
4098	#[rustc_intrinsic_const_stable_indirect]
4099	#[rustc_intrinsic]
4100	pub const unsafe fn copysignf64(x: f64, y: f64) -> f64;
4101
4102	/// Copies the sign from `y` to `x` for `f128` values.
4103	///
4104	/// The stabilized version of this intrinsic is
4105	/// [`f128::copysign`](../../std/primitive.f128.html#method.copysign)
4106	#[rustc_nounwind]
4107	#[rustc_intrinsic]
4108	pub const unsafe fn copysignf128(x: f128, y: f128) -> f128;
4109
4110	/// Inform Miri that a given pointer definitely has a certain alignment.
4111	#[cfg(miri)]
4112	#[rustc_allow_const_fn_unstable(const_eval_select)]
4113	pub(crate) const fn miri_promise_symbolic_alignment(ptr: *const (), align: usize) {
4114	unsafe extern "Rust" {
4115	/// Miri-provided extern function to promise that a given pointer is properly aligned for
4116	/// "symbolic" alignment checks. Will fail if the pointer is not actually aligned or `align` is
4117	/// not a power of two. Has no effect when alignment checks are concrete (which is the default).
4118	unsafefn miri_promise_symbolic_alignment(ptr: *const (), align: usize);
4119	}
4120
4121	const_eval_select!(
4122	@capture { ptr: *const (), align: usize}:
4123	if const {
4124	// Do nothing.
4125	} else {
4126	// SAFETY: this call is always safe.
4127	unsafe {
4128	miri_promise_symbolic_alignment(ptr, align);
4129	}
4130	}
4131	)
4132	}
4133