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, one needs to copy the implementation |
12 | //! from <https://github.com/rust-lang/miri/blob/master/src/shims/intrinsics> to |
13 | //! <https://github.com/rust-lang/rust/blob/master/compiler/rustc_const_eval/src/interpret/intrinsics.rs> and add a |
14 | //! `#[rustc_const_unstable(feature = "const_such_and_such", issue = "01234")]` to the intrinsic declaration. |
15 | //! |
16 | //! If an intrinsic is supposed to be used from a `const fn` with a `rustc_const_stable` attribute, |
17 | //! the intrinsic's attribute must be `rustc_const_stable`, too. Such a change should not be done |
18 | //! without T-lang consultation, because it bakes a feature into the language that cannot be |
19 | //! replicated in user code without compiler support. |
20 | //! |
21 | //! # Volatiles |
22 | //! |
23 | //! The volatile intrinsics provide operations intended to act on I/O |
24 | //! memory, which are guaranteed to not be reordered by the compiler |
25 | //! across other volatile intrinsics. See the LLVM documentation on |
26 | //! [[volatile]]. |
27 | //! |
28 | //! [volatile]: https://llvm.org/docs/LangRef.html#volatile-memory-accesses |
29 | //! |
30 | //! # Atomics |
31 | //! |
32 | //! The atomic intrinsics provide common atomic operations on machine |
33 | //! words, with multiple possible memory orderings. They obey the same |
34 | //! semantics as C++11. See the LLVM documentation on [[atomics]]. |
35 | //! |
36 | //! [atomics]: https://llvm.org/docs/Atomics.html |
37 | //! |
38 | //! A quick refresher on memory ordering: |
39 | //! |
40 | //! * Acquire - a barrier for acquiring a lock. Subsequent reads and writes |
41 | //! take place after the barrier. |
42 | //! * Release - a barrier for releasing a lock. Preceding reads and writes |
43 | //! take place before the barrier. |
44 | //! * Sequentially consistent - sequentially consistent operations are |
45 | //! guaranteed to happen in order. This is the standard mode for working |
46 | //! with atomic types and is equivalent to Java's `volatile`. |
47 | //! |
48 | //! # Unwinding |
49 | //! |
50 | //! Rust intrinsics may, in general, unwind. If an intrinsic can never unwind, add the |
51 | //! `#[rustc_nounwind]` attribute so that the compiler can make use of this fact. |
52 | //! |
53 | //! However, even for intrinsics that may unwind, rustc assumes that a Rust intrinsics will never |
54 | //! initiate a foreign (non-Rust) unwind, and thus for panic=abort we can always assume that these |
55 | //! intrinsics cannot unwind. |
56 | |
57 | #![unstable ( |
58 | feature = "core_intrinsics" , |
59 | reason = "intrinsics are unlikely to ever be stabilized, instead \ |
60 | they should be used through stabilized interfaces \ |
61 | in the rest of the standard library" , |
62 | issue = "none" |
63 | )] |
64 | #![allow (missing_docs)] |
65 | |
66 | use crate::marker::DiscriminantKind; |
67 | use crate::marker::Tuple; |
68 | use crate::mem::align_of; |
69 | use crate::ptr; |
70 | use crate::ub_checks; |
71 | |
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 ] |
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 | extern "rust-intrinsic" { |
90 | // N.B., these intrinsics take raw pointers because they mutate aliased |
91 | // memory, which is not valid for either `&` or `&mut`. |
92 | |
93 | /// Stores a value if the current value is the same as the `old` value. |
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_nounwind ] |
100 | pub fn atomic_cxchg_relaxed_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
101 | /// Stores a value if the current value is the same as the `old` value. |
102 | /// |
103 | /// The stabilized version of this intrinsic is available on the |
104 | /// [`atomic`] types via the `compare_exchange` method by passing |
105 | /// [`Ordering::Relaxed`] and [`Ordering::Acquire`] as the success and failure parameters. |
106 | /// For example, [`AtomicBool::compare_exchange`]. |
107 | #[rustc_nounwind ] |
108 | pub fn atomic_cxchg_relaxed_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
109 | /// Stores a value if the current value is the same as the `old` value. |
110 | /// |
111 | /// The stabilized version of this intrinsic is available on the |
112 | /// [`atomic`] types via the `compare_exchange` method by passing |
113 | /// [`Ordering::Relaxed`] and [`Ordering::SeqCst`] as the success and failure parameters. |
114 | /// For example, [`AtomicBool::compare_exchange`]. |
115 | #[rustc_nounwind ] |
116 | pub fn atomic_cxchg_relaxed_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
117 | /// Stores a value if the current value is the same as the `old` value. |
118 | /// |
119 | /// The stabilized version of this intrinsic is available on the |
120 | /// [`atomic`] types via the `compare_exchange` method by passing |
121 | /// [`Ordering::Acquire`] and [`Ordering::Relaxed`] as the success and failure parameters. |
122 | /// For example, [`AtomicBool::compare_exchange`]. |
123 | #[rustc_nounwind ] |
124 | pub fn atomic_cxchg_acquire_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
125 | /// Stores a value if the current value is the same as the `old` value. |
126 | /// |
127 | /// The stabilized version of this intrinsic is available on the |
128 | /// [`atomic`] types via the `compare_exchange` method by passing |
129 | /// [`Ordering::Acquire`] as both the success and failure parameters. |
130 | /// For example, [`AtomicBool::compare_exchange`]. |
131 | #[rustc_nounwind ] |
132 | pub fn atomic_cxchg_acquire_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
133 | /// Stores a value if the current value is the same as the `old` value. |
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`] and [`Ordering::SeqCst`] as the success and failure parameters. |
138 | /// For example, [`AtomicBool::compare_exchange`]. |
139 | #[rustc_nounwind ] |
140 | pub fn atomic_cxchg_acquire_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
141 | /// Stores a value if the current value is the same as the `old` value. |
142 | /// |
143 | /// The stabilized version of this intrinsic is available on the |
144 | /// [`atomic`] types via the `compare_exchange` method by passing |
145 | /// [`Ordering::Release`] and [`Ordering::Relaxed`] as the success and failure parameters. |
146 | /// For example, [`AtomicBool::compare_exchange`]. |
147 | #[rustc_nounwind ] |
148 | pub fn atomic_cxchg_release_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
149 | /// Stores a value if the current value is the same as the `old` value. |
150 | /// |
151 | /// The stabilized version of this intrinsic is available on the |
152 | /// [`atomic`] types via the `compare_exchange` method by passing |
153 | /// [`Ordering::Release`] and [`Ordering::Acquire`] as the success and failure parameters. |
154 | /// For example, [`AtomicBool::compare_exchange`]. |
155 | #[rustc_nounwind ] |
156 | pub fn atomic_cxchg_release_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
157 | /// Stores a value if the current value is the same as the `old` value. |
158 | /// |
159 | /// The stabilized version of this intrinsic is available on the |
160 | /// [`atomic`] types via the `compare_exchange` method by passing |
161 | /// [`Ordering::Release`] and [`Ordering::SeqCst`] as the success and failure parameters. |
162 | /// For example, [`AtomicBool::compare_exchange`]. |
163 | #[rustc_nounwind ] |
164 | pub fn atomic_cxchg_release_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
165 | /// Stores a value if the current value is the same as the `old` value. |
166 | /// |
167 | /// The stabilized version of this intrinsic is available on the |
168 | /// [`atomic`] types via the `compare_exchange` method by passing |
169 | /// [`Ordering::AcqRel`] and [`Ordering::Relaxed`] as the success and failure parameters. |
170 | /// For example, [`AtomicBool::compare_exchange`]. |
171 | #[rustc_nounwind ] |
172 | pub fn atomic_cxchg_acqrel_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
173 | /// Stores a value if the current value is the same as the `old` value. |
174 | /// |
175 | /// The stabilized version of this intrinsic is available on the |
176 | /// [`atomic`] types via the `compare_exchange` method by passing |
177 | /// [`Ordering::AcqRel`] and [`Ordering::Acquire`] as the success and failure parameters. |
178 | /// For example, [`AtomicBool::compare_exchange`]. |
179 | #[rustc_nounwind ] |
180 | pub fn atomic_cxchg_acqrel_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
181 | /// Stores a value if the current value is the same as the `old` value. |
182 | /// |
183 | /// The stabilized version of this intrinsic is available on the |
184 | /// [`atomic`] types via the `compare_exchange` method by passing |
185 | /// [`Ordering::AcqRel`] and [`Ordering::SeqCst`] as the success and failure parameters. |
186 | /// For example, [`AtomicBool::compare_exchange`]. |
187 | #[rustc_nounwind ] |
188 | pub fn atomic_cxchg_acqrel_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
189 | /// Stores a value if the current value is the same as the `old` value. |
190 | /// |
191 | /// The stabilized version of this intrinsic is available on the |
192 | /// [`atomic`] types via the `compare_exchange` method by passing |
193 | /// [`Ordering::SeqCst`] and [`Ordering::Relaxed`] as the success and failure parameters. |
194 | /// For example, [`AtomicBool::compare_exchange`]. |
195 | #[rustc_nounwind ] |
196 | pub fn atomic_cxchg_seqcst_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
197 | /// Stores a value if the current value is the same as the `old` value. |
198 | /// |
199 | /// The stabilized version of this intrinsic is available on the |
200 | /// [`atomic`] types via the `compare_exchange` method by passing |
201 | /// [`Ordering::SeqCst`] and [`Ordering::Acquire`] as the success and failure parameters. |
202 | /// For example, [`AtomicBool::compare_exchange`]. |
203 | #[rustc_nounwind ] |
204 | pub fn atomic_cxchg_seqcst_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
205 | /// Stores a value if the current value is the same as the `old` value. |
206 | /// |
207 | /// The stabilized version of this intrinsic is available on the |
208 | /// [`atomic`] types via the `compare_exchange` method by passing |
209 | /// [`Ordering::SeqCst`] as both the success and failure parameters. |
210 | /// For example, [`AtomicBool::compare_exchange`]. |
211 | #[rustc_nounwind ] |
212 | pub fn atomic_cxchg_seqcst_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
213 | |
214 | /// Stores a value if the current value is the same as the `old` value. |
215 | /// |
216 | /// The stabilized version of this intrinsic is available on the |
217 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
218 | /// [`Ordering::Relaxed`] as both the success and failure parameters. |
219 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
220 | #[rustc_nounwind ] |
221 | pub fn atomic_cxchgweak_relaxed_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 | /// |
224 | /// The stabilized version of this intrinsic is available on the |
225 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
226 | /// [`Ordering::Relaxed`] and [`Ordering::Acquire`] as the success and failure parameters. |
227 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
228 | #[rustc_nounwind ] |
229 | pub fn atomic_cxchgweak_relaxed_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
230 | /// Stores a value if the current value is the same as the `old` value. |
231 | /// |
232 | /// The stabilized version of this intrinsic is available on the |
233 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
234 | /// [`Ordering::Relaxed`] and [`Ordering::SeqCst`] as the success and failure parameters. |
235 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
236 | #[rustc_nounwind ] |
237 | pub fn atomic_cxchgweak_relaxed_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
238 | /// Stores a value if the current value is the same as the `old` value. |
239 | /// |
240 | /// The stabilized version of this intrinsic is available on the |
241 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
242 | /// [`Ordering::Acquire`] and [`Ordering::Relaxed`] as the success and failure parameters. |
243 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
244 | #[rustc_nounwind ] |
245 | pub fn atomic_cxchgweak_acquire_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
246 | /// Stores a value if the current value is the same as the `old` value. |
247 | /// |
248 | /// The stabilized version of this intrinsic is available on the |
249 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
250 | /// [`Ordering::Acquire`] as both the success and failure parameters. |
251 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
252 | #[rustc_nounwind ] |
253 | pub fn atomic_cxchgweak_acquire_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
254 | /// Stores a value if the current value is the same as the `old` value. |
255 | /// |
256 | /// The stabilized version of this intrinsic is available on the |
257 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
258 | /// [`Ordering::Acquire`] and [`Ordering::SeqCst`] as the success and failure parameters. |
259 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
260 | #[rustc_nounwind ] |
261 | pub fn atomic_cxchgweak_acquire_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
262 | /// Stores a value if the current value is the same as the `old` value. |
263 | /// |
264 | /// The stabilized version of this intrinsic is available on the |
265 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
266 | /// [`Ordering::Release`] and [`Ordering::Relaxed`] as the success and failure parameters. |
267 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
268 | #[rustc_nounwind ] |
269 | pub fn atomic_cxchgweak_release_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
270 | /// Stores a value if the current value is the same as the `old` value. |
271 | /// |
272 | /// The stabilized version of this intrinsic is available on the |
273 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
274 | /// [`Ordering::Release`] and [`Ordering::Acquire`] as the success and failure parameters. |
275 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
276 | #[rustc_nounwind ] |
277 | pub fn atomic_cxchgweak_release_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
278 | /// Stores a value if the current value is the same as the `old` value. |
279 | /// |
280 | /// The stabilized version of this intrinsic is available on the |
281 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
282 | /// [`Ordering::Release`] and [`Ordering::SeqCst`] as the success and failure parameters. |
283 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
284 | #[rustc_nounwind ] |
285 | pub fn atomic_cxchgweak_release_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
286 | /// Stores a value if the current value is the same as the `old` value. |
287 | /// |
288 | /// The stabilized version of this intrinsic is available on the |
289 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
290 | /// [`Ordering::AcqRel`] and [`Ordering::Relaxed`] as the success and failure parameters. |
291 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
292 | #[rustc_nounwind ] |
293 | pub fn atomic_cxchgweak_acqrel_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
294 | /// Stores a value if the current value is the same as the `old` value. |
295 | /// |
296 | /// The stabilized version of this intrinsic is available on the |
297 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
298 | /// [`Ordering::AcqRel`] and [`Ordering::Acquire`] as the success and failure parameters. |
299 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
300 | #[rustc_nounwind ] |
301 | pub fn atomic_cxchgweak_acqrel_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
302 | /// Stores a value if the current value is the same as the `old` value. |
303 | /// |
304 | /// The stabilized version of this intrinsic is available on the |
305 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
306 | /// [`Ordering::AcqRel`] and [`Ordering::SeqCst`] as the success and failure parameters. |
307 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
308 | #[rustc_nounwind ] |
309 | pub fn atomic_cxchgweak_acqrel_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
310 | /// Stores a value if the current value is the same as the `old` value. |
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::SeqCst`] and [`Ordering::Relaxed`] as the success and failure parameters. |
315 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
316 | #[rustc_nounwind ] |
317 | pub fn atomic_cxchgweak_seqcst_relaxed<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
318 | /// Stores a value if the current value is the same as the `old` value. |
319 | /// |
320 | /// The stabilized version of this intrinsic is available on the |
321 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
322 | /// [`Ordering::SeqCst`] and [`Ordering::Acquire`] as the success and failure parameters. |
323 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
324 | #[rustc_nounwind ] |
325 | pub fn atomic_cxchgweak_seqcst_acquire<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
326 | /// Stores a value if the current value is the same as the `old` value. |
327 | /// |
328 | /// The stabilized version of this intrinsic is available on the |
329 | /// [`atomic`] types via the `compare_exchange_weak` method by passing |
330 | /// [`Ordering::SeqCst`] as both the success and failure parameters. |
331 | /// For example, [`AtomicBool::compare_exchange_weak`]. |
332 | #[rustc_nounwind ] |
333 | pub fn atomic_cxchgweak_seqcst_seqcst<T: Copy>(dst: *mut T, old: T, src: T) -> (T, bool); |
334 | |
335 | /// Loads the current value of the pointer. |
336 | /// |
337 | /// The stabilized version of this intrinsic is available on the |
338 | /// [`atomic`] types via the `load` method by passing |
339 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::load`]. |
340 | #[rustc_nounwind ] |
341 | pub fn atomic_load_seqcst<T: Copy>(src: *const T) -> T; |
342 | /// Loads the current value of the pointer. |
343 | /// |
344 | /// The stabilized version of this intrinsic is available on the |
345 | /// [`atomic`] types via the `load` method by passing |
346 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::load`]. |
347 | #[rustc_nounwind ] |
348 | pub fn atomic_load_acquire<T: Copy>(src: *const T) -> T; |
349 | /// Loads the current value of the pointer. |
350 | /// |
351 | /// The stabilized version of this intrinsic is available on the |
352 | /// [`atomic`] types via the `load` method by passing |
353 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::load`]. |
354 | #[rustc_nounwind ] |
355 | pub fn atomic_load_relaxed<T: Copy>(src: *const T) -> T; |
356 | /// Do NOT use this intrinsic; "unordered" operations do not exist in our memory model! |
357 | /// In terms of the Rust Abstract Machine, this operation is equivalent to `src.read()`, |
358 | /// i.e., it performs a non-atomic read. |
359 | #[rustc_nounwind ] |
360 | pub fn atomic_load_unordered<T: Copy>(src: *const T) -> T; |
361 | |
362 | /// Stores the value at the specified memory location. |
363 | /// |
364 | /// The stabilized version of this intrinsic is available on the |
365 | /// [`atomic`] types via the `store` method by passing |
366 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::store`]. |
367 | #[rustc_nounwind ] |
368 | pub fn atomic_store_seqcst<T: Copy>(dst: *mut T, val: T); |
369 | /// Stores the value at the specified memory location. |
370 | /// |
371 | /// The stabilized version of this intrinsic is available on the |
372 | /// [`atomic`] types via the `store` method by passing |
373 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::store`]. |
374 | #[rustc_nounwind ] |
375 | pub fn atomic_store_release<T: Copy>(dst: *mut T, val: T); |
376 | /// Stores the value at the specified memory location. |
377 | /// |
378 | /// The stabilized version of this intrinsic is available on the |
379 | /// [`atomic`] types via the `store` method by passing |
380 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::store`]. |
381 | #[rustc_nounwind ] |
382 | pub fn atomic_store_relaxed<T: Copy>(dst: *mut T, val: T); |
383 | /// Do NOT use this intrinsic; "unordered" operations do not exist in our memory model! |
384 | /// In terms of the Rust Abstract Machine, this operation is equivalent to `dst.write(val)`, |
385 | /// i.e., it performs a non-atomic write. |
386 | #[rustc_nounwind ] |
387 | pub fn atomic_store_unordered<T: Copy>(dst: *mut T, val: T); |
388 | |
389 | /// Stores the value at the specified memory location, returning the old value. |
390 | /// |
391 | /// The stabilized version of this intrinsic is available on the |
392 | /// [`atomic`] types via the `swap` method by passing |
393 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::swap`]. |
394 | #[rustc_nounwind ] |
395 | pub fn atomic_xchg_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
396 | /// Stores the value at the specified memory location, returning the old value. |
397 | /// |
398 | /// The stabilized version of this intrinsic is available on the |
399 | /// [`atomic`] types via the `swap` method by passing |
400 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::swap`]. |
401 | #[rustc_nounwind ] |
402 | pub fn atomic_xchg_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
403 | /// Stores the value at the specified memory location, returning the old value. |
404 | /// |
405 | /// The stabilized version of this intrinsic is available on the |
406 | /// [`atomic`] types via the `swap` method by passing |
407 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::swap`]. |
408 | #[rustc_nounwind ] |
409 | pub fn atomic_xchg_release<T: Copy>(dst: *mut T, src: T) -> T; |
410 | /// Stores the value at the specified memory location, returning the old value. |
411 | /// |
412 | /// The stabilized version of this intrinsic is available on the |
413 | /// [`atomic`] types via the `swap` method by passing |
414 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::swap`]. |
415 | #[rustc_nounwind ] |
416 | pub fn atomic_xchg_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
417 | /// Stores the value at the specified memory location, returning the old value. |
418 | /// |
419 | /// The stabilized version of this intrinsic is available on the |
420 | /// [`atomic`] types via the `swap` method by passing |
421 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::swap`]. |
422 | #[rustc_nounwind ] |
423 | pub fn atomic_xchg_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
424 | |
425 | /// Adds to the current value, returning the previous value. |
426 | /// |
427 | /// The stabilized version of this intrinsic is available on the |
428 | /// [`atomic`] types via the `fetch_add` method by passing |
429 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicIsize::fetch_add`]. |
430 | #[rustc_nounwind ] |
431 | pub fn atomic_xadd_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
432 | /// Adds to the current value, returning the previous value. |
433 | /// |
434 | /// The stabilized version of this intrinsic is available on the |
435 | /// [`atomic`] types via the `fetch_add` method by passing |
436 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicIsize::fetch_add`]. |
437 | #[rustc_nounwind ] |
438 | pub fn atomic_xadd_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
439 | /// Adds to the current value, returning the previous value. |
440 | /// |
441 | /// The stabilized version of this intrinsic is available on the |
442 | /// [`atomic`] types via the `fetch_add` method by passing |
443 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicIsize::fetch_add`]. |
444 | #[rustc_nounwind ] |
445 | pub fn atomic_xadd_release<T: Copy>(dst: *mut T, src: T) -> T; |
446 | /// Adds to the current value, returning the previous value. |
447 | /// |
448 | /// The stabilized version of this intrinsic is available on the |
449 | /// [`atomic`] types via the `fetch_add` method by passing |
450 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicIsize::fetch_add`]. |
451 | #[rustc_nounwind ] |
452 | pub fn atomic_xadd_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
453 | /// Adds to the current value, returning the previous value. |
454 | /// |
455 | /// The stabilized version of this intrinsic is available on the |
456 | /// [`atomic`] types via the `fetch_add` method by passing |
457 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicIsize::fetch_add`]. |
458 | #[rustc_nounwind ] |
459 | pub fn atomic_xadd_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
460 | |
461 | /// Subtract from the current value, returning the previous value. |
462 | /// |
463 | /// The stabilized version of this intrinsic is available on the |
464 | /// [`atomic`] types via the `fetch_sub` method by passing |
465 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. |
466 | #[rustc_nounwind ] |
467 | pub fn atomic_xsub_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
468 | /// Subtract from the current value, returning the previous value. |
469 | /// |
470 | /// The stabilized version of this intrinsic is available on the |
471 | /// [`atomic`] types via the `fetch_sub` method by passing |
472 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. |
473 | #[rustc_nounwind ] |
474 | pub fn atomic_xsub_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
475 | /// Subtract from the current value, returning the previous value. |
476 | /// |
477 | /// The stabilized version of this intrinsic is available on the |
478 | /// [`atomic`] types via the `fetch_sub` method by passing |
479 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. |
480 | #[rustc_nounwind ] |
481 | pub fn atomic_xsub_release<T: Copy>(dst: *mut T, src: T) -> T; |
482 | /// Subtract from the current value, returning the previous value. |
483 | /// |
484 | /// The stabilized version of this intrinsic is available on the |
485 | /// [`atomic`] types via the `fetch_sub` method by passing |
486 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. |
487 | #[rustc_nounwind ] |
488 | pub fn atomic_xsub_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
489 | /// Subtract from the current value, returning the previous value. |
490 | /// |
491 | /// The stabilized version of this intrinsic is available on the |
492 | /// [`atomic`] types via the `fetch_sub` method by passing |
493 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicIsize::fetch_sub`]. |
494 | #[rustc_nounwind ] |
495 | pub fn atomic_xsub_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
496 | |
497 | /// Bitwise and with the current value, returning the previous value. |
498 | /// |
499 | /// The stabilized version of this intrinsic is available on the |
500 | /// [`atomic`] types via the `fetch_and` method by passing |
501 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_and`]. |
502 | #[rustc_nounwind ] |
503 | pub fn atomic_and_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
504 | /// Bitwise and with the current value, returning the previous value. |
505 | /// |
506 | /// The stabilized version of this intrinsic is available on the |
507 | /// [`atomic`] types via the `fetch_and` method by passing |
508 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_and`]. |
509 | #[rustc_nounwind ] |
510 | pub fn atomic_and_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
511 | /// Bitwise and with the current value, returning the previous value. |
512 | /// |
513 | /// The stabilized version of this intrinsic is available on the |
514 | /// [`atomic`] types via the `fetch_and` method by passing |
515 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_and`]. |
516 | #[rustc_nounwind ] |
517 | pub fn atomic_and_release<T: Copy>(dst: *mut T, src: T) -> T; |
518 | /// Bitwise and with the current value, returning the previous value. |
519 | /// |
520 | /// The stabilized version of this intrinsic is available on the |
521 | /// [`atomic`] types via the `fetch_and` method by passing |
522 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_and`]. |
523 | #[rustc_nounwind ] |
524 | pub fn atomic_and_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
525 | /// Bitwise and with the current value, returning the previous value. |
526 | /// |
527 | /// The stabilized version of this intrinsic is available on the |
528 | /// [`atomic`] types via the `fetch_and` method by passing |
529 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_and`]. |
530 | #[rustc_nounwind ] |
531 | pub fn atomic_and_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
532 | |
533 | /// Bitwise nand with the current value, returning the previous value. |
534 | /// |
535 | /// The stabilized version of this intrinsic is available on the |
536 | /// [`AtomicBool`] type via the `fetch_nand` method by passing |
537 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_nand`]. |
538 | #[rustc_nounwind ] |
539 | pub fn atomic_nand_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
540 | /// Bitwise nand with the current value, returning the previous value. |
541 | /// |
542 | /// The stabilized version of this intrinsic is available on the |
543 | /// [`AtomicBool`] type via the `fetch_nand` method by passing |
544 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_nand`]. |
545 | #[rustc_nounwind ] |
546 | pub fn atomic_nand_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
547 | /// Bitwise nand with the current value, returning the previous value. |
548 | /// |
549 | /// The stabilized version of this intrinsic is available on the |
550 | /// [`AtomicBool`] type via the `fetch_nand` method by passing |
551 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_nand`]. |
552 | #[rustc_nounwind ] |
553 | pub fn atomic_nand_release<T: Copy>(dst: *mut T, src: T) -> T; |
554 | /// Bitwise nand with the current value, returning the previous value. |
555 | /// |
556 | /// The stabilized version of this intrinsic is available on the |
557 | /// [`AtomicBool`] type via the `fetch_nand` method by passing |
558 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_nand`]. |
559 | #[rustc_nounwind ] |
560 | pub fn atomic_nand_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
561 | /// Bitwise nand with the current value, returning the previous value. |
562 | /// |
563 | /// The stabilized version of this intrinsic is available on the |
564 | /// [`AtomicBool`] type via the `fetch_nand` method by passing |
565 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_nand`]. |
566 | #[rustc_nounwind ] |
567 | pub fn atomic_nand_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
568 | |
569 | /// Bitwise or with the current value, returning the previous value. |
570 | /// |
571 | /// The stabilized version of this intrinsic is available on the |
572 | /// [`atomic`] types via the `fetch_or` method by passing |
573 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_or`]. |
574 | #[rustc_nounwind ] |
575 | pub fn atomic_or_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
576 | /// Bitwise or with the current value, returning the previous value. |
577 | /// |
578 | /// The stabilized version of this intrinsic is available on the |
579 | /// [`atomic`] types via the `fetch_or` method by passing |
580 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_or`]. |
581 | #[rustc_nounwind ] |
582 | pub fn atomic_or_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
583 | /// Bitwise or with the current value, returning the previous value. |
584 | /// |
585 | /// The stabilized version of this intrinsic is available on the |
586 | /// [`atomic`] types via the `fetch_or` method by passing |
587 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_or`]. |
588 | #[rustc_nounwind ] |
589 | pub fn atomic_or_release<T: Copy>(dst: *mut T, src: T) -> T; |
590 | /// Bitwise or with the current value, returning the previous value. |
591 | /// |
592 | /// The stabilized version of this intrinsic is available on the |
593 | /// [`atomic`] types via the `fetch_or` method by passing |
594 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_or`]. |
595 | #[rustc_nounwind ] |
596 | pub fn atomic_or_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
597 | /// Bitwise or with the current value, returning the previous value. |
598 | /// |
599 | /// The stabilized version of this intrinsic is available on the |
600 | /// [`atomic`] types via the `fetch_or` method by passing |
601 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_or`]. |
602 | #[rustc_nounwind ] |
603 | pub fn atomic_or_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
604 | |
605 | /// Bitwise xor with the current value, returning the previous value. |
606 | /// |
607 | /// The stabilized version of this intrinsic is available on the |
608 | /// [`atomic`] types via the `fetch_xor` method by passing |
609 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicBool::fetch_xor`]. |
610 | #[rustc_nounwind ] |
611 | pub fn atomic_xor_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
612 | /// Bitwise xor with the current value, returning the previous value. |
613 | /// |
614 | /// The stabilized version of this intrinsic is available on the |
615 | /// [`atomic`] types via the `fetch_xor` method by passing |
616 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicBool::fetch_xor`]. |
617 | #[rustc_nounwind ] |
618 | pub fn atomic_xor_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
619 | /// Bitwise xor with the current value, returning the previous value. |
620 | /// |
621 | /// The stabilized version of this intrinsic is available on the |
622 | /// [`atomic`] types via the `fetch_xor` method by passing |
623 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicBool::fetch_xor`]. |
624 | #[rustc_nounwind ] |
625 | pub fn atomic_xor_release<T: Copy>(dst: *mut T, src: T) -> T; |
626 | /// Bitwise xor with the current value, returning the previous value. |
627 | /// |
628 | /// The stabilized version of this intrinsic is available on the |
629 | /// [`atomic`] types via the `fetch_xor` method by passing |
630 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicBool::fetch_xor`]. |
631 | #[rustc_nounwind ] |
632 | pub fn atomic_xor_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
633 | /// Bitwise xor with the current value, returning the previous value. |
634 | /// |
635 | /// The stabilized version of this intrinsic is available on the |
636 | /// [`atomic`] types via the `fetch_xor` method by passing |
637 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicBool::fetch_xor`]. |
638 | #[rustc_nounwind ] |
639 | pub fn atomic_xor_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
640 | |
641 | /// Maximum with the current value using a signed comparison. |
642 | /// |
643 | /// The stabilized version of this intrinsic is available on the |
644 | /// [`atomic`] signed integer types via the `fetch_max` method by passing |
645 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicI32::fetch_max`]. |
646 | #[rustc_nounwind ] |
647 | pub fn atomic_max_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
648 | /// Maximum with the current value using a signed comparison. |
649 | /// |
650 | /// The stabilized version of this intrinsic is available on the |
651 | /// [`atomic`] signed integer types via the `fetch_max` method by passing |
652 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicI32::fetch_max`]. |
653 | #[rustc_nounwind ] |
654 | pub fn atomic_max_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
655 | /// Maximum with the current value using a signed comparison. |
656 | /// |
657 | /// The stabilized version of this intrinsic is available on the |
658 | /// [`atomic`] signed integer types via the `fetch_max` method by passing |
659 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicI32::fetch_max`]. |
660 | #[rustc_nounwind ] |
661 | pub fn atomic_max_release<T: Copy>(dst: *mut T, src: T) -> T; |
662 | /// Maximum with the current value using a signed comparison. |
663 | /// |
664 | /// The stabilized version of this intrinsic is available on the |
665 | /// [`atomic`] signed integer types via the `fetch_max` method by passing |
666 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicI32::fetch_max`]. |
667 | #[rustc_nounwind ] |
668 | pub fn atomic_max_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
669 | /// Maximum with the current value. |
670 | /// |
671 | /// The stabilized version of this intrinsic is available on the |
672 | /// [`atomic`] signed integer types via the `fetch_max` method by passing |
673 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicI32::fetch_max`]. |
674 | #[rustc_nounwind ] |
675 | pub fn atomic_max_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
676 | |
677 | /// Minimum with the current value using a signed comparison. |
678 | /// |
679 | /// The stabilized version of this intrinsic is available on the |
680 | /// [`atomic`] signed integer types via the `fetch_min` method by passing |
681 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicI32::fetch_min`]. |
682 | #[rustc_nounwind ] |
683 | pub fn atomic_min_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
684 | /// Minimum with the current value using a signed comparison. |
685 | /// |
686 | /// The stabilized version of this intrinsic is available on the |
687 | /// [`atomic`] signed integer types via the `fetch_min` method by passing |
688 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicI32::fetch_min`]. |
689 | #[rustc_nounwind ] |
690 | pub fn atomic_min_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
691 | /// Minimum with the current value using a signed comparison. |
692 | /// |
693 | /// The stabilized version of this intrinsic is available on the |
694 | /// [`atomic`] signed integer types via the `fetch_min` method by passing |
695 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicI32::fetch_min`]. |
696 | #[rustc_nounwind ] |
697 | pub fn atomic_min_release<T: Copy>(dst: *mut T, src: T) -> T; |
698 | /// Minimum with the current value using a signed comparison. |
699 | /// |
700 | /// The stabilized version of this intrinsic is available on the |
701 | /// [`atomic`] signed integer types via the `fetch_min` method by passing |
702 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicI32::fetch_min`]. |
703 | #[rustc_nounwind ] |
704 | pub fn atomic_min_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
705 | /// Minimum with the current value using a signed comparison. |
706 | /// |
707 | /// The stabilized version of this intrinsic is available on the |
708 | /// [`atomic`] signed integer types via the `fetch_min` method by passing |
709 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicI32::fetch_min`]. |
710 | #[rustc_nounwind ] |
711 | pub fn atomic_min_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
712 | |
713 | /// Minimum with the current value using an unsigned comparison. |
714 | /// |
715 | /// The stabilized version of this intrinsic is available on the |
716 | /// [`atomic`] unsigned integer types via the `fetch_min` method by passing |
717 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicU32::fetch_min`]. |
718 | #[rustc_nounwind ] |
719 | pub fn atomic_umin_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
720 | /// Minimum with the current value using an unsigned comparison. |
721 | /// |
722 | /// The stabilized version of this intrinsic is available on the |
723 | /// [`atomic`] unsigned integer types via the `fetch_min` method by passing |
724 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicU32::fetch_min`]. |
725 | #[rustc_nounwind ] |
726 | pub fn atomic_umin_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
727 | /// Minimum with the current value using an unsigned comparison. |
728 | /// |
729 | /// The stabilized version of this intrinsic is available on the |
730 | /// [`atomic`] unsigned integer types via the `fetch_min` method by passing |
731 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicU32::fetch_min`]. |
732 | #[rustc_nounwind ] |
733 | pub fn atomic_umin_release<T: Copy>(dst: *mut T, src: T) -> T; |
734 | /// Minimum with the current value using an unsigned comparison. |
735 | /// |
736 | /// The stabilized version of this intrinsic is available on the |
737 | /// [`atomic`] unsigned integer types via the `fetch_min` method by passing |
738 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicU32::fetch_min`]. |
739 | #[rustc_nounwind ] |
740 | pub fn atomic_umin_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
741 | /// Minimum with the current value using an unsigned comparison. |
742 | /// |
743 | /// The stabilized version of this intrinsic is available on the |
744 | /// [`atomic`] unsigned integer types via the `fetch_min` method by passing |
745 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicU32::fetch_min`]. |
746 | #[rustc_nounwind ] |
747 | pub fn atomic_umin_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
748 | |
749 | /// Maximum with the current value using an unsigned comparison. |
750 | /// |
751 | /// The stabilized version of this intrinsic is available on the |
752 | /// [`atomic`] unsigned integer types via the `fetch_max` method by passing |
753 | /// [`Ordering::SeqCst`] as the `order`. For example, [`AtomicU32::fetch_max`]. |
754 | #[rustc_nounwind ] |
755 | pub fn atomic_umax_seqcst<T: Copy>(dst: *mut T, src: T) -> T; |
756 | /// Maximum with the current value using an unsigned comparison. |
757 | /// |
758 | /// The stabilized version of this intrinsic is available on the |
759 | /// [`atomic`] unsigned integer types via the `fetch_max` method by passing |
760 | /// [`Ordering::Acquire`] as the `order`. For example, [`AtomicU32::fetch_max`]. |
761 | #[rustc_nounwind ] |
762 | pub fn atomic_umax_acquire<T: Copy>(dst: *mut T, src: T) -> T; |
763 | /// Maximum with the current value using an unsigned comparison. |
764 | /// |
765 | /// The stabilized version of this intrinsic is available on the |
766 | /// [`atomic`] unsigned integer types via the `fetch_max` method by passing |
767 | /// [`Ordering::Release`] as the `order`. For example, [`AtomicU32::fetch_max`]. |
768 | #[rustc_nounwind ] |
769 | pub fn atomic_umax_release<T: Copy>(dst: *mut T, src: T) -> T; |
770 | /// Maximum with the current value using an unsigned comparison. |
771 | /// |
772 | /// The stabilized version of this intrinsic is available on the |
773 | /// [`atomic`] unsigned integer types via the `fetch_max` method by passing |
774 | /// [`Ordering::AcqRel`] as the `order`. For example, [`AtomicU32::fetch_max`]. |
775 | #[rustc_nounwind ] |
776 | pub fn atomic_umax_acqrel<T: Copy>(dst: *mut T, src: T) -> T; |
777 | /// Maximum with the current value using an unsigned comparison. |
778 | /// |
779 | /// The stabilized version of this intrinsic is available on the |
780 | /// [`atomic`] unsigned integer types via the `fetch_max` method by passing |
781 | /// [`Ordering::Relaxed`] as the `order`. For example, [`AtomicU32::fetch_max`]. |
782 | #[rustc_nounwind ] |
783 | pub fn atomic_umax_relaxed<T: Copy>(dst: *mut T, src: T) -> T; |
784 | |
785 | /// An atomic fence. |
786 | /// |
787 | /// The stabilized version of this intrinsic is available in |
788 | /// [`atomic::fence`] by passing [`Ordering::SeqCst`] |
789 | /// as the `order`. |
790 | #[rustc_nounwind ] |
791 | pub fn atomic_fence_seqcst(); |
792 | /// An atomic fence. |
793 | /// |
794 | /// The stabilized version of this intrinsic is available in |
795 | /// [`atomic::fence`] by passing [`Ordering::Acquire`] |
796 | /// as the `order`. |
797 | #[rustc_nounwind ] |
798 | pub fn atomic_fence_acquire(); |
799 | /// An atomic fence. |
800 | /// |
801 | /// The stabilized version of this intrinsic is available in |
802 | /// [`atomic::fence`] by passing [`Ordering::Release`] |
803 | /// as the `order`. |
804 | #[rustc_nounwind ] |
805 | pub fn atomic_fence_release(); |
806 | /// An atomic fence. |
807 | /// |
808 | /// The stabilized version of this intrinsic is available in |
809 | /// [`atomic::fence`] by passing [`Ordering::AcqRel`] |
810 | /// as the `order`. |
811 | #[rustc_nounwind ] |
812 | pub fn atomic_fence_acqrel(); |
813 | |
814 | /// A compiler-only memory barrier. |
815 | /// |
816 | /// Memory accesses will never be reordered across this barrier by the |
817 | /// compiler, but no instructions will be emitted for it. This is |
818 | /// appropriate for operations on the same thread that may be preempted, |
819 | /// such as when interacting with signal handlers. |
820 | /// |
821 | /// The stabilized version of this intrinsic is available in |
822 | /// [`atomic::compiler_fence`] by passing [`Ordering::SeqCst`] |
823 | /// as the `order`. |
824 | #[rustc_nounwind ] |
825 | pub fn atomic_singlethreadfence_seqcst(); |
826 | /// A compiler-only memory barrier. |
827 | /// |
828 | /// Memory accesses will never be reordered across this barrier by the |
829 | /// compiler, but no instructions will be emitted for it. This is |
830 | /// appropriate for operations on the same thread that may be preempted, |
831 | /// such as when interacting with signal handlers. |
832 | /// |
833 | /// The stabilized version of this intrinsic is available in |
834 | /// [`atomic::compiler_fence`] by passing [`Ordering::Acquire`] |
835 | /// as the `order`. |
836 | #[rustc_nounwind ] |
837 | pub fn atomic_singlethreadfence_acquire(); |
838 | /// A compiler-only memory barrier. |
839 | /// |
840 | /// Memory accesses will never be reordered across this barrier by the |
841 | /// compiler, but no instructions will be emitted for it. This is |
842 | /// appropriate for operations on the same thread that may be preempted, |
843 | /// such as when interacting with signal handlers. |
844 | /// |
845 | /// The stabilized version of this intrinsic is available in |
846 | /// [`atomic::compiler_fence`] by passing [`Ordering::Release`] |
847 | /// as the `order`. |
848 | #[rustc_nounwind ] |
849 | pub fn atomic_singlethreadfence_release(); |
850 | /// A compiler-only memory barrier. |
851 | /// |
852 | /// Memory accesses will never be reordered across this barrier by the |
853 | /// compiler, but no instructions will be emitted for it. This is |
854 | /// appropriate for operations on the same thread that may be preempted, |
855 | /// such as when interacting with signal handlers. |
856 | /// |
857 | /// The stabilized version of this intrinsic is available in |
858 | /// [`atomic::compiler_fence`] by passing [`Ordering::AcqRel`] |
859 | /// as the `order`. |
860 | #[rustc_nounwind ] |
861 | pub fn atomic_singlethreadfence_acqrel(); |
862 | |
863 | /// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction |
864 | /// if supported; otherwise, it is a no-op. |
865 | /// Prefetches have no effect on the behavior of the program but can change its performance |
866 | /// characteristics. |
867 | /// |
868 | /// The `locality` argument must be a constant integer and is a temporal locality specifier |
869 | /// ranging from (0) - no locality, to (3) - extremely local keep in cache. |
870 | /// |
871 | /// This intrinsic does not have a stable counterpart. |
872 | #[rustc_nounwind ] |
873 | pub fn prefetch_read_data<T>(data: *const T, locality: i32); |
874 | /// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction |
875 | /// if supported; otherwise, it is a no-op. |
876 | /// Prefetches have no effect on the behavior of the program but can change its performance |
877 | /// characteristics. |
878 | /// |
879 | /// The `locality` argument must be a constant integer and is a temporal locality specifier |
880 | /// ranging from (0) - no locality, to (3) - extremely local keep in cache. |
881 | /// |
882 | /// This intrinsic does not have a stable counterpart. |
883 | #[rustc_nounwind ] |
884 | pub fn prefetch_write_data<T>(data: *const T, locality: i32); |
885 | /// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction |
886 | /// if supported; otherwise, it is a no-op. |
887 | /// Prefetches have no effect on the behavior of the program but can change its performance |
888 | /// characteristics. |
889 | /// |
890 | /// The `locality` argument must be a constant integer and is a temporal locality specifier |
891 | /// ranging from (0) - no locality, to (3) - extremely local keep in cache. |
892 | /// |
893 | /// This intrinsic does not have a stable counterpart. |
894 | #[rustc_nounwind ] |
895 | pub fn prefetch_read_instruction<T>(data: *const T, locality: i32); |
896 | /// The `prefetch` intrinsic is a hint to the code generator to insert a prefetch instruction |
897 | /// if supported; otherwise, it is a no-op. |
898 | /// Prefetches have no effect on the behavior of the program but can change its performance |
899 | /// characteristics. |
900 | /// |
901 | /// The `locality` argument must be a constant integer and is a temporal locality specifier |
902 | /// ranging from (0) - no locality, to (3) - extremely local keep in cache. |
903 | /// |
904 | /// This intrinsic does not have a stable counterpart. |
905 | #[rustc_nounwind ] |
906 | pub fn prefetch_write_instruction<T>(data: *const T, locality: i32); |
907 | |
908 | /// Magic intrinsic that derives its meaning from attributes |
909 | /// attached to the function. |
910 | /// |
911 | /// For example, dataflow uses this to inject static assertions so |
912 | /// that `rustc_peek(potentially_uninitialized)` would actually |
913 | /// double-check that dataflow did indeed compute that it is |
914 | /// uninitialized at that point in the control flow. |
915 | /// |
916 | /// This intrinsic should not be used outside of the compiler. |
917 | #[rustc_safe_intrinsic ] |
918 | #[rustc_nounwind ] |
919 | pub fn rustc_peek<T>(_: T) -> T; |
920 | |
921 | /// Aborts the execution of the process. |
922 | /// |
923 | /// Note that, unlike most intrinsics, this is safe to call; |
924 | /// it does not require an `unsafe` block. |
925 | /// Therefore, implementations must not require the user to uphold |
926 | /// any safety invariants. |
927 | /// |
928 | /// [`std::process::abort`](../../std/process/fn.abort.html) is to be preferred if possible, |
929 | /// as its behavior is more user-friendly and more stable. |
930 | /// |
931 | /// The current implementation of `intrinsics::abort` is to invoke an invalid instruction, |
932 | /// on most platforms. |
933 | /// On Unix, the |
934 | /// process will probably terminate with a signal like `SIGABRT`, `SIGILL`, `SIGTRAP`, `SIGSEGV` or |
935 | /// `SIGBUS`. The precise behaviour is not guaranteed and not stable. |
936 | #[rustc_safe_intrinsic ] |
937 | #[rustc_nounwind ] |
938 | pub fn abort() -> !; |
939 | |
940 | /// Informs the optimizer that this point in the code is not reachable, |
941 | /// enabling further optimizations. |
942 | /// |
943 | /// N.B., this is very different from the `unreachable!()` macro: Unlike the |
944 | /// macro, which panics when it is executed, it is *undefined behavior* to |
945 | /// reach code marked with this function. |
946 | /// |
947 | /// The stabilized version of this intrinsic is [`core::hint::unreachable_unchecked`]. |
948 | #[rustc_const_stable (feature = "const_unreachable_unchecked" , since = "1.57.0" )] |
949 | #[rustc_nounwind ] |
950 | pub fn unreachable() -> !; |
951 | |
952 | } |
953 | |
954 | /// Informs the optimizer that a condition is always true. |
955 | /// If the condition is false, the behavior is undefined. |
956 | /// |
957 | /// No code is generated for this intrinsic, but the optimizer will try |
958 | /// to preserve it (and its condition) between passes, which may interfere |
959 | /// with optimization of surrounding code and reduce performance. It should |
960 | /// not be used if the invariant can be discovered by the optimizer on its |
961 | /// own, or if it does not enable any significant optimizations. |
962 | /// |
963 | /// This intrinsic does not have a stable counterpart. |
964 | #[rustc_const_stable (feature = "const_assume" , since = "1.77.0" )] |
965 | #[rustc_nounwind ] |
966 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
967 | #[rustc_intrinsic] |
968 | pub const unsafe fn assume(b: bool) { |
969 | if !b { |
970 | // SAFETY: the caller must guarantee the argument is never `false` |
971 | unsafe { unreachable() } |
972 | } |
973 | } |
974 | |
975 | /// Hints to the compiler that branch condition is likely to be true. |
976 | /// Returns the value passed to it. |
977 | /// |
978 | /// Any use other than with `if` statements will probably not have an effect. |
979 | /// |
980 | /// Note that, unlike most intrinsics, this is safe to call; |
981 | /// it does not require an `unsafe` block. |
982 | /// Therefore, implementations must not require the user to uphold |
983 | /// any safety invariants. |
984 | /// |
985 | /// This intrinsic does not have a stable counterpart. |
986 | #[rustc_const_unstable (feature = "const_likely" , issue = "none" )] |
987 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
988 | #[rustc_intrinsic] |
989 | #[rustc_nounwind ] |
990 | pub const fn likely(b: bool) -> bool { |
991 | b |
992 | } |
993 | |
994 | /// Hints to the compiler that branch condition is likely to be false. |
995 | /// Returns the value passed to it. |
996 | /// |
997 | /// Any use other than with `if` statements will probably not have an effect. |
998 | /// |
999 | /// Note that, unlike most intrinsics, this is safe to call; |
1000 | /// it does not require an `unsafe` block. |
1001 | /// Therefore, implementations must not require the user to uphold |
1002 | /// any safety invariants. |
1003 | /// |
1004 | /// This intrinsic does not have a stable counterpart. |
1005 | #[rustc_const_unstable (feature = "const_likely" , issue = "none" )] |
1006 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
1007 | #[rustc_intrinsic] |
1008 | #[rustc_nounwind ] |
1009 | pub const fn unlikely(b: bool) -> bool { |
1010 | b |
1011 | } |
1012 | |
1013 | extern "rust-intrinsic" { |
1014 | /// Executes a breakpoint trap, for inspection by a debugger. |
1015 | /// |
1016 | /// This intrinsic does not have a stable counterpart. |
1017 | #[rustc_nounwind ] |
1018 | pub fn breakpoint(); |
1019 | |
1020 | /// The size of a type in bytes. |
1021 | /// |
1022 | /// Note that, unlike most intrinsics, this is safe to call; |
1023 | /// it does not require an `unsafe` block. |
1024 | /// Therefore, implementations must not require the user to uphold |
1025 | /// any safety invariants. |
1026 | /// |
1027 | /// More specifically, this is the offset in bytes between successive |
1028 | /// items of the same type, including alignment padding. |
1029 | /// |
1030 | /// The stabilized version of this intrinsic is [`core::mem::size_of`]. |
1031 | #[rustc_const_stable (feature = "const_size_of" , since = "1.40.0" )] |
1032 | #[rustc_safe_intrinsic ] |
1033 | #[rustc_nounwind ] |
1034 | pub fn size_of<T>() -> usize; |
1035 | |
1036 | /// The minimum alignment of a type. |
1037 | /// |
1038 | /// Note that, unlike most intrinsics, this is safe to call; |
1039 | /// it does not require an `unsafe` block. |
1040 | /// Therefore, implementations must not require the user to uphold |
1041 | /// any safety invariants. |
1042 | /// |
1043 | /// The stabilized version of this intrinsic is [`core::mem::align_of`]. |
1044 | #[rustc_const_stable (feature = "const_min_align_of" , since = "1.40.0" )] |
1045 | #[rustc_safe_intrinsic ] |
1046 | #[rustc_nounwind ] |
1047 | pub fn min_align_of<T>() -> usize; |
1048 | /// The preferred alignment of a type. |
1049 | /// |
1050 | /// This intrinsic does not have a stable counterpart. |
1051 | /// It's "tracking issue" is [#91971](https://github.com/rust-lang/rust/issues/91971). |
1052 | #[rustc_const_unstable (feature = "const_pref_align_of" , issue = "91971" )] |
1053 | #[rustc_nounwind ] |
1054 | pub fn pref_align_of<T>() -> usize; |
1055 | |
1056 | /// The size of the referenced value in bytes. |
1057 | /// |
1058 | /// The stabilized version of this intrinsic is [`crate::mem::size_of_val`]. |
1059 | #[rustc_const_unstable (feature = "const_size_of_val" , issue = "46571" )] |
1060 | #[rustc_nounwind ] |
1061 | pub fn size_of_val<T: ?Sized>(_: *const T) -> usize; |
1062 | /// The required alignment of the referenced value. |
1063 | /// |
1064 | /// The stabilized version of this intrinsic is [`core::mem::align_of_val`]. |
1065 | #[rustc_const_unstable (feature = "const_align_of_val" , issue = "46571" )] |
1066 | #[rustc_nounwind ] |
1067 | pub fn min_align_of_val<T: ?Sized>(_: *const T) -> usize; |
1068 | |
1069 | /// Gets a static string slice containing the name of a type. |
1070 | /// |
1071 | /// Note that, unlike most intrinsics, this is safe to call; |
1072 | /// it does not require an `unsafe` block. |
1073 | /// Therefore, implementations must not require the user to uphold |
1074 | /// any safety invariants. |
1075 | /// |
1076 | /// The stabilized version of this intrinsic is [`core::any::type_name`]. |
1077 | #[rustc_const_unstable (feature = "const_type_name" , issue = "63084" )] |
1078 | #[rustc_safe_intrinsic ] |
1079 | #[rustc_nounwind ] |
1080 | pub fn type_name<T: ?Sized>() -> &'static str; |
1081 | |
1082 | /// Gets an identifier which is globally unique to the specified type. This |
1083 | /// function will return the same value for a type regardless of whichever |
1084 | /// crate it is invoked in. |
1085 | /// |
1086 | /// Note that, unlike most intrinsics, this is safe to call; |
1087 | /// it does not require an `unsafe` block. |
1088 | /// Therefore, implementations must not require the user to uphold |
1089 | /// any safety invariants. |
1090 | /// |
1091 | /// The stabilized version of this intrinsic is [`core::any::TypeId::of`]. |
1092 | #[rustc_const_unstable (feature = "const_type_id" , issue = "77125" )] |
1093 | #[rustc_safe_intrinsic ] |
1094 | #[rustc_nounwind ] |
1095 | pub fn type_id<T: ?Sized + 'static>() -> u128; |
1096 | |
1097 | /// A guard for unsafe functions that cannot ever be executed if `T` is uninhabited: |
1098 | /// This will statically either panic, or do nothing. |
1099 | /// |
1100 | /// This intrinsic does not have a stable counterpart. |
1101 | #[rustc_const_stable (feature = "const_assert_type" , since = "1.59.0" )] |
1102 | #[rustc_safe_intrinsic ] |
1103 | #[rustc_nounwind ] |
1104 | pub fn assert_inhabited<T>(); |
1105 | |
1106 | /// A guard for unsafe functions that cannot ever be executed if `T` does not permit |
1107 | /// zero-initialization: This will statically either panic, or do nothing. |
1108 | /// |
1109 | /// This intrinsic does not have a stable counterpart. |
1110 | #[rustc_const_stable (feature = "const_assert_type2" , since = "1.75.0" )] |
1111 | #[rustc_safe_intrinsic ] |
1112 | #[rustc_nounwind ] |
1113 | pub fn assert_zero_valid<T>(); |
1114 | |
1115 | /// A guard for `std::mem::uninitialized`. This will statically either panic, or do nothing. |
1116 | /// |
1117 | /// This intrinsic does not have a stable counterpart. |
1118 | #[rustc_const_stable (feature = "const_assert_type2" , since = "1.75.0" )] |
1119 | #[rustc_safe_intrinsic ] |
1120 | #[rustc_nounwind ] |
1121 | pub fn assert_mem_uninitialized_valid<T>(); |
1122 | |
1123 | /// Gets a reference to a static `Location` indicating where it was called. |
1124 | /// |
1125 | /// Note that, unlike most intrinsics, this is safe to call; |
1126 | /// it does not require an `unsafe` block. |
1127 | /// Therefore, implementations must not require the user to uphold |
1128 | /// any safety invariants. |
1129 | /// |
1130 | /// Consider using [`core::panic::Location::caller`] instead. |
1131 | #[rustc_const_stable (feature = "const_caller_location" , since = "CURRENT_RUSTC_VERSION" )] |
1132 | #[rustc_safe_intrinsic ] |
1133 | #[rustc_nounwind ] |
1134 | pub fn caller_location() -> &'static crate::panic::Location<'static>; |
1135 | |
1136 | /// Moves a value out of scope without running drop glue. |
1137 | /// |
1138 | /// This exists solely for [`crate::mem::forget_unsized`]; normal `forget` uses |
1139 | /// `ManuallyDrop` instead. |
1140 | /// |
1141 | /// Note that, unlike most intrinsics, this is safe to call; |
1142 | /// it does not require an `unsafe` block. |
1143 | /// Therefore, implementations must not require the user to uphold |
1144 | /// any safety invariants. |
1145 | #[rustc_const_unstable (feature = "const_intrinsic_forget" , issue = "none" )] |
1146 | #[rustc_safe_intrinsic ] |
1147 | #[rustc_nounwind ] |
1148 | pub fn forget<T: ?Sized>(_: T); |
1149 | |
1150 | /// Reinterprets the bits of a value of one type as another type. |
1151 | /// |
1152 | /// Both types must have the same size. Compilation will fail if this is not guaranteed. |
1153 | /// |
1154 | /// `transmute` is semantically equivalent to a bitwise move of one type |
1155 | /// into another. It copies the bits from the source value into the |
1156 | /// destination value, then forgets the original. Note that source and destination |
1157 | /// are passed by-value, which means if `Src` or `Dst` contain padding, that padding |
1158 | /// is *not* guaranteed to be preserved by `transmute`. |
1159 | /// |
1160 | /// Both the argument and the result must be [valid](../../nomicon/what-unsafe-does.html) at |
1161 | /// their given type. Violating this condition leads to [undefined behavior][ub]. The compiler |
1162 | /// will generate code *assuming that you, the programmer, ensure that there will never be |
1163 | /// undefined behavior*. It is therefore your responsibility to guarantee that every value |
1164 | /// passed to `transmute` is valid at both types `Src` and `Dst`. Failing to uphold this condition |
1165 | /// may lead to unexpected and unstable compilation results. This makes `transmute` **incredibly |
1166 | /// unsafe**. `transmute` should be the absolute last resort. |
1167 | /// |
1168 | /// Because `transmute` is a by-value operation, alignment of the *transmuted values |
1169 | /// themselves* is not a concern. As with any other function, the compiler already ensures |
1170 | /// both `Src` and `Dst` are properly aligned. However, when transmuting values that *point |
1171 | /// elsewhere* (such as pointers, references, boxes…), the caller has to ensure proper |
1172 | /// alignment of the pointed-to values. |
1173 | /// |
1174 | /// The [nomicon](../../nomicon/transmutes.html) has additional documentation. |
1175 | /// |
1176 | /// [ub]: ../../reference/behavior-considered-undefined.html |
1177 | /// |
1178 | /// # Transmutation between pointers and integers |
1179 | /// |
1180 | /// Special care has to be taken when transmuting between pointers and integers, e.g. |
1181 | /// transmuting between `*const ()` and `usize`. |
1182 | /// |
1183 | /// Transmuting *pointers to integers* in a `const` context is [undefined behavior][ub], unless |
1184 | /// the pointer was originally created *from* an integer. (That includes this function |
1185 | /// specifically, integer-to-pointer casts, and helpers like [`dangling`][crate::ptr::dangling], |
1186 | /// but also semantically-equivalent conversions such as punning through `repr(C)` union |
1187 | /// fields.) Any attempt to use the resulting value for integer operations will abort |
1188 | /// const-evaluation. (And even outside `const`, such transmutation is touching on many |
1189 | /// unspecified aspects of the Rust memory model and should be avoided. See below for |
1190 | /// alternatives.) |
1191 | /// |
1192 | /// Transmuting *integers to pointers* is a largely unspecified operation. It is likely *not* |
1193 | /// equivalent to an `as` cast. Doing non-zero-sized memory accesses with a pointer constructed |
1194 | /// this way is currently considered undefined behavior. |
1195 | /// |
1196 | /// All this also applies when the integer is nested inside an array, tuple, struct, or enum. |
1197 | /// However, `MaybeUninit<usize>` is not considered an integer type for the purpose of this |
1198 | /// section. Transmuting `*const ()` to `MaybeUninit<usize>` is fine---but then calling |
1199 | /// `assume_init()` on that result is considered as completing the pointer-to-integer transmute |
1200 | /// and thus runs into the issues discussed above. |
1201 | /// |
1202 | /// In particular, doing a pointer-to-integer-to-pointer roundtrip via `transmute` is *not* a |
1203 | /// lossless process. If you want to round-trip a pointer through an integer in a way that you |
1204 | /// can get back the original pointer, you need to use `as` casts, or replace the integer type |
1205 | /// by `MaybeUninit<$int>` (and never call `assume_init()`). If you are looking for a way to |
1206 | /// store data of arbitrary type, also use `MaybeUninit<T>` (that will also handle uninitialized |
1207 | /// memory due to padding). If you specifically need to store something that is "either an |
1208 | /// integer or a pointer", use `*mut ()`: integers can be converted to pointers and back without |
1209 | /// any loss (via `as` casts or via `transmute`). |
1210 | /// |
1211 | /// # Examples |
1212 | /// |
1213 | /// There are a few things that `transmute` is really useful for. |
1214 | /// |
1215 | /// Turning a pointer into a function pointer. This is *not* portable to |
1216 | /// machines where function pointers and data pointers have different sizes. |
1217 | /// |
1218 | /// ``` |
1219 | /// fn foo() -> i32 { |
1220 | /// 0 |
1221 | /// } |
1222 | /// // Crucially, we `as`-cast to a raw pointer before `transmute`ing to a function pointer. |
1223 | /// // This avoids an integer-to-pointer `transmute`, which can be problematic. |
1224 | /// // Transmuting between raw pointers and function pointers (i.e., two pointer types) is fine. |
1225 | /// let pointer = foo as *const (); |
1226 | /// let function = unsafe { |
1227 | /// std::mem::transmute::<*const (), fn() -> i32>(pointer) |
1228 | /// }; |
1229 | /// assert_eq!(function(), 0); |
1230 | /// ``` |
1231 | /// |
1232 | /// Extending a lifetime, or shortening an invariant lifetime. This is |
1233 | /// advanced, very unsafe Rust! |
1234 | /// |
1235 | /// ``` |
1236 | /// struct R<'a>(&'a i32); |
1237 | /// unsafe fn extend_lifetime<'b>(r: R<'b>) -> R<'static> { |
1238 | /// std::mem::transmute::<R<'b>, R<'static>>(r) |
1239 | /// } |
1240 | /// |
1241 | /// unsafe fn shorten_invariant_lifetime<'b, 'c>(r: &'b mut R<'static>) |
1242 | /// -> &'b mut R<'c> { |
1243 | /// std::mem::transmute::<&'b mut R<'static>, &'b mut R<'c>>(r) |
1244 | /// } |
1245 | /// ``` |
1246 | /// |
1247 | /// # Alternatives |
1248 | /// |
1249 | /// Don't despair: many uses of `transmute` can be achieved through other means. |
1250 | /// Below are common applications of `transmute` which can be replaced with safer |
1251 | /// constructs. |
1252 | /// |
1253 | /// Turning raw bytes (`[u8; SZ]`) into `u32`, `f64`, etc.: |
1254 | /// |
1255 | /// ``` |
1256 | /// let raw_bytes = [0x78, 0x56, 0x34, 0x12]; |
1257 | /// |
1258 | /// let num = unsafe { |
1259 | /// std::mem::transmute::<[u8; 4], u32>(raw_bytes) |
1260 | /// }; |
1261 | /// |
1262 | /// // use `u32::from_ne_bytes` instead |
1263 | /// let num = u32::from_ne_bytes(raw_bytes); |
1264 | /// // or use `u32::from_le_bytes` or `u32::from_be_bytes` to specify the endianness |
1265 | /// let num = u32::from_le_bytes(raw_bytes); |
1266 | /// assert_eq!(num, 0x12345678); |
1267 | /// let num = u32::from_be_bytes(raw_bytes); |
1268 | /// assert_eq!(num, 0x78563412); |
1269 | /// ``` |
1270 | /// |
1271 | /// Turning a pointer into a `usize`: |
1272 | /// |
1273 | /// ```no_run |
1274 | /// let ptr = &0; |
1275 | /// let ptr_num_transmute = unsafe { |
1276 | /// std::mem::transmute::<&i32, usize>(ptr) |
1277 | /// }; |
1278 | /// |
1279 | /// // Use an `as` cast instead |
1280 | /// let ptr_num_cast = ptr as *const i32 as usize; |
1281 | /// ``` |
1282 | /// |
1283 | /// Note that using `transmute` to turn a pointer to a `usize` is (as noted above) [undefined |
1284 | /// behavior][ub] in `const` contexts. Also outside of consts, this operation might not behave |
1285 | /// as expected -- this is touching on many unspecified aspects of the Rust memory model. |
1286 | /// Depending on what the code is doing, the following alternatives are preferable to |
1287 | /// pointer-to-integer transmutation: |
1288 | /// - If the code just wants to store data of arbitrary type in some buffer and needs to pick a |
1289 | /// type for that buffer, it can use [`MaybeUninit`][crate::mem::MaybeUninit]. |
1290 | /// - If the code actually wants to work on the address the pointer points to, it can use `as` |
1291 | /// casts or [`ptr.addr()`][pointer::addr]. |
1292 | /// |
1293 | /// Turning a `*mut T` into an `&mut T`: |
1294 | /// |
1295 | /// ``` |
1296 | /// let ptr: *mut i32 = &mut 0; |
1297 | /// let ref_transmuted = unsafe { |
1298 | /// std::mem::transmute::<*mut i32, &mut i32>(ptr) |
1299 | /// }; |
1300 | /// |
1301 | /// // Use a reborrow instead |
1302 | /// let ref_casted = unsafe { &mut *ptr }; |
1303 | /// ``` |
1304 | /// |
1305 | /// Turning an `&mut T` into an `&mut U`: |
1306 | /// |
1307 | /// ``` |
1308 | /// let ptr = &mut 0; |
1309 | /// let val_transmuted = unsafe { |
1310 | /// std::mem::transmute::<&mut i32, &mut u32>(ptr) |
1311 | /// }; |
1312 | /// |
1313 | /// // Now, put together `as` and reborrowing - note the chaining of `as` |
1314 | /// // `as` is not transitive |
1315 | /// let val_casts = unsafe { &mut *(ptr as *mut i32 as *mut u32) }; |
1316 | /// ``` |
1317 | /// |
1318 | /// Turning an `&str` into a `&[u8]`: |
1319 | /// |
1320 | /// ``` |
1321 | /// // this is not a good way to do this. |
1322 | /// let slice = unsafe { std::mem::transmute::<&str, &[u8]>("Rust" ) }; |
1323 | /// assert_eq!(slice, &[82, 117, 115, 116]); |
1324 | /// |
1325 | /// // You could use `str::as_bytes` |
1326 | /// let slice = "Rust" .as_bytes(); |
1327 | /// assert_eq!(slice, &[82, 117, 115, 116]); |
1328 | /// |
1329 | /// // Or, just use a byte string, if you have control over the string |
1330 | /// // literal |
1331 | /// assert_eq!(b"Rust" , &[82, 117, 115, 116]); |
1332 | /// ``` |
1333 | /// |
1334 | /// Turning a `Vec<&T>` into a `Vec<Option<&T>>`. |
1335 | /// |
1336 | /// To transmute the inner type of the contents of a container, you must make sure to not |
1337 | /// violate any of the container's invariants. For `Vec`, this means that both the size |
1338 | /// *and alignment* of the inner types have to match. Other containers might rely on the |
1339 | /// size of the type, alignment, or even the `TypeId`, in which case transmuting wouldn't |
1340 | /// be possible at all without violating the container invariants. |
1341 | /// |
1342 | /// ``` |
1343 | /// let store = [0, 1, 2, 3]; |
1344 | /// let v_orig = store.iter().collect::<Vec<&i32>>(); |
1345 | /// |
1346 | /// // clone the vector as we will reuse them later |
1347 | /// let v_clone = v_orig.clone(); |
1348 | /// |
1349 | /// // Using transmute: this relies on the unspecified data layout of `Vec`, which is a |
1350 | /// // bad idea and could cause Undefined Behavior. |
1351 | /// // However, it is no-copy. |
1352 | /// let v_transmuted = unsafe { |
1353 | /// std::mem::transmute::<Vec<&i32>, Vec<Option<&i32>>>(v_clone) |
1354 | /// }; |
1355 | /// |
1356 | /// let v_clone = v_orig.clone(); |
1357 | /// |
1358 | /// // This is the suggested, safe way. |
1359 | /// // It may copy the entire vector into a new one though, but also may not. |
1360 | /// let v_collected = v_clone.into_iter() |
1361 | /// .map(Some) |
1362 | /// .collect::<Vec<Option<&i32>>>(); |
1363 | /// |
1364 | /// let v_clone = v_orig.clone(); |
1365 | /// |
1366 | /// // This is the proper no-copy, unsafe way of "transmuting" a `Vec`, without relying on the |
1367 | /// // data layout. Instead of literally calling `transmute`, we perform a pointer cast, but |
1368 | /// // in terms of converting the original inner type (`&i32`) to the new one (`Option<&i32>`), |
1369 | /// // this has all the same caveats. Besides the information provided above, also consult the |
1370 | /// // [`from_raw_parts`] documentation. |
1371 | /// let v_from_raw = unsafe { |
1372 | // FIXME Update this when vec_into_raw_parts is stabilized |
1373 | /// // Ensure the original vector is not dropped. |
1374 | /// let mut v_clone = std::mem::ManuallyDrop::new(v_clone); |
1375 | /// Vec::from_raw_parts(v_clone.as_mut_ptr() as *mut Option<&i32>, |
1376 | /// v_clone.len(), |
1377 | /// v_clone.capacity()) |
1378 | /// }; |
1379 | /// ``` |
1380 | /// |
1381 | /// [`from_raw_parts`]: ../../std/vec/struct.Vec.html#method.from_raw_parts |
1382 | /// |
1383 | /// Implementing `split_at_mut`: |
1384 | /// |
1385 | /// ``` |
1386 | /// use std::{slice, mem}; |
1387 | /// |
1388 | /// // There are multiple ways to do this, and there are multiple problems |
1389 | /// // with the following (transmute) way. |
1390 | /// fn split_at_mut_transmute<T>(slice: &mut [T], mid: usize) |
1391 | /// -> (&mut [T], &mut [T]) { |
1392 | /// let len = slice.len(); |
1393 | /// assert!(mid <= len); |
1394 | /// unsafe { |
1395 | /// let slice2 = mem::transmute::<&mut [T], &mut [T]>(slice); |
1396 | /// // first: transmute is not type safe; all it checks is that T and |
1397 | /// // U are of the same size. Second, right here, you have two |
1398 | /// // mutable references pointing to the same memory. |
1399 | /// (&mut slice[0..mid], &mut slice2[mid..len]) |
1400 | /// } |
1401 | /// } |
1402 | /// |
1403 | /// // This gets rid of the type safety problems; `&mut *` will *only* give |
1404 | /// // you an `&mut T` from an `&mut T` or `*mut T`. |
1405 | /// fn split_at_mut_casts<T>(slice: &mut [T], mid: usize) |
1406 | /// -> (&mut [T], &mut [T]) { |
1407 | /// let len = slice.len(); |
1408 | /// assert!(mid <= len); |
1409 | /// unsafe { |
1410 | /// let slice2 = &mut *(slice as *mut [T]); |
1411 | /// // however, you still have two mutable references pointing to |
1412 | /// // the same memory. |
1413 | /// (&mut slice[0..mid], &mut slice2[mid..len]) |
1414 | /// } |
1415 | /// } |
1416 | /// |
1417 | /// // This is how the standard library does it. This is the best method, if |
1418 | /// // you need to do something like this |
1419 | /// fn split_at_stdlib<T>(slice: &mut [T], mid: usize) |
1420 | /// -> (&mut [T], &mut [T]) { |
1421 | /// let len = slice.len(); |
1422 | /// assert!(mid <= len); |
1423 | /// unsafe { |
1424 | /// let ptr = slice.as_mut_ptr(); |
1425 | /// // This now has three mutable references pointing at the same |
1426 | /// // memory. `slice`, the rvalue ret.0, and the rvalue ret.1. |
1427 | /// // `slice` is never used after `let ptr = ...`, and so one can |
1428 | /// // treat it as "dead", and therefore, you only have two real |
1429 | /// // mutable slices. |
1430 | /// (slice::from_raw_parts_mut(ptr, mid), |
1431 | /// slice::from_raw_parts_mut(ptr.add(mid), len - mid)) |
1432 | /// } |
1433 | /// } |
1434 | /// ``` |
1435 | #[stable (feature = "rust1" , since = "1.0.0" )] |
1436 | #[rustc_allowed_through_unstable_modules ] |
1437 | #[rustc_const_stable (feature = "const_transmute" , since = "1.56.0" )] |
1438 | #[rustc_diagnostic_item = "transmute" ] |
1439 | #[rustc_nounwind ] |
1440 | pub fn transmute<Src, Dst>(src: Src) -> Dst; |
1441 | |
1442 | /// Like [`transmute`], but even less checked at compile-time: rather than |
1443 | /// giving an error for `size_of::<Src>() != size_of::<Dst>()`, it's |
1444 | /// **Undefined Behaviour** at runtime. |
1445 | /// |
1446 | /// Prefer normal `transmute` where possible, for the extra checking, since |
1447 | /// both do exactly the same thing at runtime, if they both compile. |
1448 | /// |
1449 | /// This is not expected to ever be exposed directly to users, rather it |
1450 | /// may eventually be exposed through some more-constrained API. |
1451 | #[rustc_const_stable (feature = "const_transmute" , since = "1.56.0" )] |
1452 | #[rustc_nounwind ] |
1453 | pub fn transmute_unchecked<Src, Dst>(src: Src) -> Dst; |
1454 | |
1455 | /// Returns `true` if the actual type given as `T` requires drop |
1456 | /// glue; returns `false` if the actual type provided for `T` |
1457 | /// implements `Copy`. |
1458 | /// |
1459 | /// If the actual type neither requires drop glue nor implements |
1460 | /// `Copy`, then the return value of this function is unspecified. |
1461 | /// |
1462 | /// Note that, unlike most intrinsics, this is safe to call; |
1463 | /// it does not require an `unsafe` block. |
1464 | /// Therefore, implementations must not require the user to uphold |
1465 | /// any safety invariants. |
1466 | /// |
1467 | /// The stabilized version of this intrinsic is [`mem::needs_drop`](crate::mem::needs_drop). |
1468 | #[rustc_const_stable (feature = "const_needs_drop" , since = "1.40.0" )] |
1469 | #[rustc_safe_intrinsic ] |
1470 | #[rustc_nounwind ] |
1471 | pub fn needs_drop<T: ?Sized>() -> bool; |
1472 | |
1473 | /// Calculates the offset from a pointer. |
1474 | /// |
1475 | /// This is implemented as an intrinsic to avoid converting to and from an |
1476 | /// integer, since the conversion would throw away aliasing information. |
1477 | /// |
1478 | /// This can only be used with `Ptr` as a raw pointer type (`*mut` or `*const`) |
1479 | /// to a `Sized` pointee and with `Delta` as `usize` or `isize`. Any other |
1480 | /// instantiations may arbitrarily misbehave, and that's *not* a compiler bug. |
1481 | /// |
1482 | /// # Safety |
1483 | /// |
1484 | /// Both the starting and resulting pointer must be either in bounds or one |
1485 | /// byte past the end of an allocated object. If either pointer is out of |
1486 | /// bounds or arithmetic overflow occurs then any further use of the |
1487 | /// returned value will result in undefined behavior. |
1488 | /// |
1489 | /// The stabilized version of this intrinsic is [`pointer::offset`]. |
1490 | #[must_use = "returns a new pointer rather than modifying its argument" ] |
1491 | #[rustc_const_stable (feature = "const_ptr_offset" , since = "1.61.0" )] |
1492 | #[rustc_nounwind ] |
1493 | pub fn offset<Ptr, Delta>(dst: Ptr, offset: Delta) -> Ptr; |
1494 | |
1495 | /// Calculates the offset from a pointer, potentially wrapping. |
1496 | /// |
1497 | /// This is implemented as an intrinsic to avoid converting to and from an |
1498 | /// integer, since the conversion inhibits certain optimizations. |
1499 | /// |
1500 | /// # Safety |
1501 | /// |
1502 | /// Unlike the `offset` intrinsic, this intrinsic does not restrict the |
1503 | /// resulting pointer to point into or one byte past the end of an allocated |
1504 | /// object, and it wraps with two's complement arithmetic. The resulting |
1505 | /// value is not necessarily valid to be used to actually access memory. |
1506 | /// |
1507 | /// The stabilized version of this intrinsic is [`pointer::wrapping_offset`]. |
1508 | #[must_use = "returns a new pointer rather than modifying its argument" ] |
1509 | #[rustc_const_stable (feature = "const_ptr_offset" , since = "1.61.0" )] |
1510 | #[rustc_nounwind ] |
1511 | pub fn arith_offset<T>(dst: *const T, offset: isize) -> *const T; |
1512 | |
1513 | /// Masks out bits of the pointer according to a mask. |
1514 | /// |
1515 | /// Note that, unlike most intrinsics, this is safe to call; |
1516 | /// it does not require an `unsafe` block. |
1517 | /// Therefore, implementations must not require the user to uphold |
1518 | /// any safety invariants. |
1519 | /// |
1520 | /// Consider using [`pointer::mask`] instead. |
1521 | #[rustc_safe_intrinsic ] |
1522 | #[rustc_nounwind ] |
1523 | pub fn ptr_mask<T>(ptr: *const T, mask: usize) -> *const T; |
1524 | |
1525 | /// Equivalent to the appropriate `llvm.memcpy.p0i8.0i8.*` intrinsic, with |
1526 | /// a size of `count` * `size_of::<T>()` and an alignment of |
1527 | /// `min_align_of::<T>()` |
1528 | /// |
1529 | /// The volatile parameter is set to `true`, so it will not be optimized out |
1530 | /// unless size is equal to zero. |
1531 | /// |
1532 | /// This intrinsic does not have a stable counterpart. |
1533 | #[rustc_nounwind ] |
1534 | pub fn volatile_copy_nonoverlapping_memory<T>(dst: *mut T, src: *const T, count: usize); |
1535 | /// Equivalent to the appropriate `llvm.memmove.p0i8.0i8.*` intrinsic, with |
1536 | /// a size of `count * size_of::<T>()` and an alignment of |
1537 | /// `min_align_of::<T>()` |
1538 | /// |
1539 | /// The volatile parameter is set to `true`, so it will not be optimized out |
1540 | /// unless size is equal to zero. |
1541 | /// |
1542 | /// This intrinsic does not have a stable counterpart. |
1543 | #[rustc_nounwind ] |
1544 | pub fn volatile_copy_memory<T>(dst: *mut T, src: *const T, count: usize); |
1545 | /// Equivalent to the appropriate `llvm.memset.p0i8.*` intrinsic, with a |
1546 | /// size of `count * size_of::<T>()` and an alignment of |
1547 | /// `min_align_of::<T>()`. |
1548 | /// |
1549 | /// The volatile parameter is set to `true`, so it will not be optimized out |
1550 | /// unless size is equal to zero. |
1551 | /// |
1552 | /// This intrinsic does not have a stable counterpart. |
1553 | #[rustc_nounwind ] |
1554 | pub fn volatile_set_memory<T>(dst: *mut T, val: u8, count: usize); |
1555 | |
1556 | /// Performs a volatile load from the `src` pointer. |
1557 | /// |
1558 | /// The stabilized version of this intrinsic is [`core::ptr::read_volatile`]. |
1559 | #[rustc_nounwind ] |
1560 | pub fn volatile_load<T>(src: *const T) -> T; |
1561 | /// Performs a volatile store to the `dst` pointer. |
1562 | /// |
1563 | /// The stabilized version of this intrinsic is [`core::ptr::write_volatile`]. |
1564 | #[rustc_nounwind ] |
1565 | pub fn volatile_store<T>(dst: *mut T, val: T); |
1566 | |
1567 | /// Performs a volatile load from the `src` pointer |
1568 | /// The pointer is not required to be aligned. |
1569 | /// |
1570 | /// This intrinsic does not have a stable counterpart. |
1571 | #[rustc_nounwind ] |
1572 | #[rustc_diagnostic_item = "intrinsics_unaligned_volatile_load" ] |
1573 | pub fn unaligned_volatile_load<T>(src: *const T) -> T; |
1574 | /// Performs a volatile store to the `dst` pointer. |
1575 | /// The pointer is not required to be aligned. |
1576 | /// |
1577 | /// This intrinsic does not have a stable counterpart. |
1578 | #[rustc_nounwind ] |
1579 | #[rustc_diagnostic_item = "intrinsics_unaligned_volatile_store" ] |
1580 | pub fn unaligned_volatile_store<T>(dst: *mut T, val: T); |
1581 | |
1582 | /// Returns the square root of an `f32` |
1583 | /// |
1584 | /// The stabilized version of this intrinsic is |
1585 | /// [`f32::sqrt`](../../std/primitive.f32.html#method.sqrt) |
1586 | #[rustc_nounwind ] |
1587 | pub fn sqrtf32(x: f32) -> f32; |
1588 | /// Returns the square root of an `f64` |
1589 | /// |
1590 | /// The stabilized version of this intrinsic is |
1591 | /// [`f64::sqrt`](../../std/primitive.f64.html#method.sqrt) |
1592 | #[rustc_nounwind ] |
1593 | pub fn sqrtf64(x: f64) -> f64; |
1594 | |
1595 | /// Raises an `f32` to an integer power. |
1596 | /// |
1597 | /// The stabilized version of this intrinsic is |
1598 | /// [`f32::powi`](../../std/primitive.f32.html#method.powi) |
1599 | #[rustc_nounwind ] |
1600 | pub fn powif32(a: f32, x: i32) -> f32; |
1601 | /// Raises an `f64` to an integer power. |
1602 | /// |
1603 | /// The stabilized version of this intrinsic is |
1604 | /// [`f64::powi`](../../std/primitive.f64.html#method.powi) |
1605 | #[rustc_nounwind ] |
1606 | pub fn powif64(a: f64, x: i32) -> f64; |
1607 | |
1608 | /// Returns the sine of an `f32`. |
1609 | /// |
1610 | /// The stabilized version of this intrinsic is |
1611 | /// [`f32::sin`](../../std/primitive.f32.html#method.sin) |
1612 | #[rustc_nounwind ] |
1613 | pub fn sinf32(x: f32) -> f32; |
1614 | /// Returns the sine of an `f64`. |
1615 | /// |
1616 | /// The stabilized version of this intrinsic is |
1617 | /// [`f64::sin`](../../std/primitive.f64.html#method.sin) |
1618 | #[rustc_nounwind ] |
1619 | pub fn sinf64(x: f64) -> f64; |
1620 | |
1621 | /// Returns the cosine of an `f32`. |
1622 | /// |
1623 | /// The stabilized version of this intrinsic is |
1624 | /// [`f32::cos`](../../std/primitive.f32.html#method.cos) |
1625 | #[rustc_nounwind ] |
1626 | pub fn cosf32(x: f32) -> f32; |
1627 | /// Returns the cosine of an `f64`. |
1628 | /// |
1629 | /// The stabilized version of this intrinsic is |
1630 | /// [`f64::cos`](../../std/primitive.f64.html#method.cos) |
1631 | #[rustc_nounwind ] |
1632 | pub fn cosf64(x: f64) -> f64; |
1633 | |
1634 | /// Raises an `f32` to an `f32` power. |
1635 | /// |
1636 | /// The stabilized version of this intrinsic is |
1637 | /// [`f32::powf`](../../std/primitive.f32.html#method.powf) |
1638 | #[rustc_nounwind ] |
1639 | pub fn powf32(a: f32, x: f32) -> f32; |
1640 | /// Raises an `f64` to an `f64` power. |
1641 | /// |
1642 | /// The stabilized version of this intrinsic is |
1643 | /// [`f64::powf`](../../std/primitive.f64.html#method.powf) |
1644 | #[rustc_nounwind ] |
1645 | pub fn powf64(a: f64, x: f64) -> f64; |
1646 | |
1647 | /// Returns the exponential of an `f32`. |
1648 | /// |
1649 | /// The stabilized version of this intrinsic is |
1650 | /// [`f32::exp`](../../std/primitive.f32.html#method.exp) |
1651 | #[rustc_nounwind ] |
1652 | pub fn expf32(x: f32) -> f32; |
1653 | /// Returns the exponential of an `f64`. |
1654 | /// |
1655 | /// The stabilized version of this intrinsic is |
1656 | /// [`f64::exp`](../../std/primitive.f64.html#method.exp) |
1657 | #[rustc_nounwind ] |
1658 | pub fn expf64(x: f64) -> f64; |
1659 | |
1660 | /// Returns 2 raised to the power of an `f32`. |
1661 | /// |
1662 | /// The stabilized version of this intrinsic is |
1663 | /// [`f32::exp2`](../../std/primitive.f32.html#method.exp2) |
1664 | #[rustc_nounwind ] |
1665 | pub fn exp2f32(x: f32) -> f32; |
1666 | /// Returns 2 raised to the power of an `f64`. |
1667 | /// |
1668 | /// The stabilized version of this intrinsic is |
1669 | /// [`f64::exp2`](../../std/primitive.f64.html#method.exp2) |
1670 | #[rustc_nounwind ] |
1671 | pub fn exp2f64(x: f64) -> f64; |
1672 | |
1673 | /// Returns the natural logarithm of an `f32`. |
1674 | /// |
1675 | /// The stabilized version of this intrinsic is |
1676 | /// [`f32::ln`](../../std/primitive.f32.html#method.ln) |
1677 | #[rustc_nounwind ] |
1678 | pub fn logf32(x: f32) -> f32; |
1679 | /// Returns the natural logarithm of an `f64`. |
1680 | /// |
1681 | /// The stabilized version of this intrinsic is |
1682 | /// [`f64::ln`](../../std/primitive.f64.html#method.ln) |
1683 | #[rustc_nounwind ] |
1684 | pub fn logf64(x: f64) -> f64; |
1685 | |
1686 | /// Returns the base 10 logarithm of an `f32`. |
1687 | /// |
1688 | /// The stabilized version of this intrinsic is |
1689 | /// [`f32::log10`](../../std/primitive.f32.html#method.log10) |
1690 | #[rustc_nounwind ] |
1691 | pub fn log10f32(x: f32) -> f32; |
1692 | /// Returns the base 10 logarithm of an `f64`. |
1693 | /// |
1694 | /// The stabilized version of this intrinsic is |
1695 | /// [`f64::log10`](../../std/primitive.f64.html#method.log10) |
1696 | #[rustc_nounwind ] |
1697 | pub fn log10f64(x: f64) -> f64; |
1698 | |
1699 | /// Returns the base 2 logarithm of an `f32`. |
1700 | /// |
1701 | /// The stabilized version of this intrinsic is |
1702 | /// [`f32::log2`](../../std/primitive.f32.html#method.log2) |
1703 | #[rustc_nounwind ] |
1704 | pub fn log2f32(x: f32) -> f32; |
1705 | /// Returns the base 2 logarithm of an `f64`. |
1706 | /// |
1707 | /// The stabilized version of this intrinsic is |
1708 | /// [`f64::log2`](../../std/primitive.f64.html#method.log2) |
1709 | #[rustc_nounwind ] |
1710 | pub fn log2f64(x: f64) -> f64; |
1711 | |
1712 | /// Returns `a * b + c` for `f32` values. |
1713 | /// |
1714 | /// The stabilized version of this intrinsic is |
1715 | /// [`f32::mul_add`](../../std/primitive.f32.html#method.mul_add) |
1716 | #[rustc_nounwind ] |
1717 | pub fn fmaf32(a: f32, b: f32, c: f32) -> f32; |
1718 | /// Returns `a * b + c` for `f64` values. |
1719 | /// |
1720 | /// The stabilized version of this intrinsic is |
1721 | /// [`f64::mul_add`](../../std/primitive.f64.html#method.mul_add) |
1722 | #[rustc_nounwind ] |
1723 | pub fn fmaf64(a: f64, b: f64, c: f64) -> f64; |
1724 | |
1725 | /// Returns the absolute value of an `f32`. |
1726 | /// |
1727 | /// The stabilized version of this intrinsic is |
1728 | /// [`f32::abs`](../../std/primitive.f32.html#method.abs) |
1729 | #[rustc_nounwind ] |
1730 | pub fn fabsf32(x: f32) -> f32; |
1731 | /// Returns the absolute value of an `f64`. |
1732 | /// |
1733 | /// The stabilized version of this intrinsic is |
1734 | /// [`f64::abs`](../../std/primitive.f64.html#method.abs) |
1735 | #[rustc_nounwind ] |
1736 | pub fn fabsf64(x: f64) -> f64; |
1737 | |
1738 | /// Returns the minimum of two `f32` values. |
1739 | /// |
1740 | /// Note that, unlike most intrinsics, this is safe to call; |
1741 | /// it does not require an `unsafe` block. |
1742 | /// Therefore, implementations must not require the user to uphold |
1743 | /// any safety invariants. |
1744 | /// |
1745 | /// The stabilized version of this intrinsic is |
1746 | /// [`f32::min`] |
1747 | #[rustc_safe_intrinsic ] |
1748 | #[rustc_nounwind ] |
1749 | pub fn minnumf32(x: f32, y: f32) -> f32; |
1750 | /// Returns the minimum of two `f64` values. |
1751 | /// |
1752 | /// Note that, unlike most intrinsics, this is safe to call; |
1753 | /// it does not require an `unsafe` block. |
1754 | /// Therefore, implementations must not require the user to uphold |
1755 | /// any safety invariants. |
1756 | /// |
1757 | /// The stabilized version of this intrinsic is |
1758 | /// [`f64::min`] |
1759 | #[rustc_safe_intrinsic ] |
1760 | #[rustc_nounwind ] |
1761 | pub fn minnumf64(x: f64, y: f64) -> f64; |
1762 | /// Returns the maximum of two `f32` values. |
1763 | /// |
1764 | /// Note that, unlike most intrinsics, this is safe to call; |
1765 | /// it does not require an `unsafe` block. |
1766 | /// Therefore, implementations must not require the user to uphold |
1767 | /// any safety invariants. |
1768 | /// |
1769 | /// The stabilized version of this intrinsic is |
1770 | /// [`f32::max`] |
1771 | #[rustc_safe_intrinsic ] |
1772 | #[rustc_nounwind ] |
1773 | pub fn maxnumf32(x: f32, y: f32) -> f32; |
1774 | /// Returns the maximum of two `f64` values. |
1775 | /// |
1776 | /// Note that, unlike most intrinsics, this is safe to call; |
1777 | /// it does not require an `unsafe` block. |
1778 | /// Therefore, implementations must not require the user to uphold |
1779 | /// any safety invariants. |
1780 | /// |
1781 | /// The stabilized version of this intrinsic is |
1782 | /// [`f64::max`] |
1783 | #[rustc_safe_intrinsic ] |
1784 | #[rustc_nounwind ] |
1785 | pub fn maxnumf64(x: f64, y: f64) -> f64; |
1786 | |
1787 | /// Copies the sign from `y` to `x` for `f32` values. |
1788 | /// |
1789 | /// The stabilized version of this intrinsic is |
1790 | /// [`f32::copysign`](../../std/primitive.f32.html#method.copysign) |
1791 | #[rustc_nounwind ] |
1792 | pub fn copysignf32(x: f32, y: f32) -> f32; |
1793 | /// Copies the sign from `y` to `x` for `f64` values. |
1794 | /// |
1795 | /// The stabilized version of this intrinsic is |
1796 | /// [`f64::copysign`](../../std/primitive.f64.html#method.copysign) |
1797 | #[rustc_nounwind ] |
1798 | pub fn copysignf64(x: f64, y: f64) -> f64; |
1799 | |
1800 | /// Returns the largest integer less than or equal to an `f32`. |
1801 | /// |
1802 | /// The stabilized version of this intrinsic is |
1803 | /// [`f32::floor`](../../std/primitive.f32.html#method.floor) |
1804 | #[rustc_nounwind ] |
1805 | pub fn floorf32(x: f32) -> f32; |
1806 | /// Returns the largest integer less than or equal to an `f64`. |
1807 | /// |
1808 | /// The stabilized version of this intrinsic is |
1809 | /// [`f64::floor`](../../std/primitive.f64.html#method.floor) |
1810 | #[rustc_nounwind ] |
1811 | pub fn floorf64(x: f64) -> f64; |
1812 | |
1813 | /// Returns the smallest integer greater than or equal to an `f32`. |
1814 | /// |
1815 | /// The stabilized version of this intrinsic is |
1816 | /// [`f32::ceil`](../../std/primitive.f32.html#method.ceil) |
1817 | #[rustc_nounwind ] |
1818 | pub fn ceilf32(x: f32) -> f32; |
1819 | /// Returns the smallest integer greater than or equal to an `f64`. |
1820 | /// |
1821 | /// The stabilized version of this intrinsic is |
1822 | /// [`f64::ceil`](../../std/primitive.f64.html#method.ceil) |
1823 | #[rustc_nounwind ] |
1824 | pub fn ceilf64(x: f64) -> f64; |
1825 | |
1826 | /// Returns the integer part of an `f32`. |
1827 | /// |
1828 | /// The stabilized version of this intrinsic is |
1829 | /// [`f32::trunc`](../../std/primitive.f32.html#method.trunc) |
1830 | #[rustc_nounwind ] |
1831 | pub fn truncf32(x: f32) -> f32; |
1832 | /// Returns the integer part of an `f64`. |
1833 | /// |
1834 | /// The stabilized version of this intrinsic is |
1835 | /// [`f64::trunc`](../../std/primitive.f64.html#method.trunc) |
1836 | #[rustc_nounwind ] |
1837 | pub fn truncf64(x: f64) -> f64; |
1838 | |
1839 | /// Returns the nearest integer to an `f32`. Changing the rounding mode is not possible in Rust, |
1840 | /// so this rounds half-way cases to the number with an even least significant digit. |
1841 | /// |
1842 | /// May raise an inexact floating-point exception if the argument is not an integer. |
1843 | /// However, Rust assumes floating-point exceptions cannot be observed, so these exceptions |
1844 | /// cannot actually be utilized from Rust code. |
1845 | /// In other words, this intrinsic is equivalent in behavior to `nearbyintf32` and `roundevenf32`. |
1846 | /// |
1847 | /// The stabilized version of this intrinsic is |
1848 | /// [`f32::round_ties_even`](../../std/primitive.f32.html#method.round_ties_even) |
1849 | #[rustc_nounwind ] |
1850 | pub fn rintf32(x: f32) -> f32; |
1851 | /// Returns the nearest integer to an `f64`. Changing the rounding mode is not possible in Rust, |
1852 | /// so this rounds half-way cases to the number with an even least significant digit. |
1853 | /// |
1854 | /// May raise an inexact floating-point exception if the argument is not an integer. |
1855 | /// However, Rust assumes floating-point exceptions cannot be observed, so these exceptions |
1856 | /// cannot actually be utilized from Rust code. |
1857 | /// In other words, this intrinsic is equivalent in behavior to `nearbyintf64` and `roundevenf64`. |
1858 | /// |
1859 | /// The stabilized version of this intrinsic is |
1860 | /// [`f64::round_ties_even`](../../std/primitive.f64.html#method.round_ties_even) |
1861 | #[rustc_nounwind ] |
1862 | pub fn rintf64(x: f64) -> f64; |
1863 | |
1864 | /// Returns the nearest integer to an `f32`. Changing the rounding mode is not possible in Rust, |
1865 | /// so this rounds half-way cases to the number with an even least significant digit. |
1866 | /// |
1867 | /// This intrinsic does not have a stable counterpart. |
1868 | #[rustc_nounwind ] |
1869 | pub fn nearbyintf32(x: f32) -> f32; |
1870 | /// Returns the nearest integer to an `f64`. Changing the rounding mode is not possible in Rust, |
1871 | /// so this rounds half-way cases to the number with an even least significant digit. |
1872 | /// |
1873 | /// This intrinsic does not have a stable counterpart. |
1874 | #[rustc_nounwind ] |
1875 | pub fn nearbyintf64(x: f64) -> f64; |
1876 | |
1877 | /// Returns the nearest integer to an `f32`. Rounds half-way cases away from zero. |
1878 | /// |
1879 | /// The stabilized version of this intrinsic is |
1880 | /// [`f32::round`](../../std/primitive.f32.html#method.round) |
1881 | #[rustc_nounwind ] |
1882 | pub fn roundf32(x: f32) -> f32; |
1883 | /// Returns the nearest integer to an `f64`. Rounds half-way cases away from zero. |
1884 | /// |
1885 | /// The stabilized version of this intrinsic is |
1886 | /// [`f64::round`](../../std/primitive.f64.html#method.round) |
1887 | #[rustc_nounwind ] |
1888 | pub fn roundf64(x: f64) -> f64; |
1889 | |
1890 | /// Returns the nearest integer to an `f32`. Rounds half-way cases to the number |
1891 | /// with an even least significant digit. |
1892 | /// |
1893 | /// This intrinsic does not have a stable counterpart. |
1894 | #[rustc_nounwind ] |
1895 | pub fn roundevenf32(x: f32) -> f32; |
1896 | /// Returns the nearest integer to an `f64`. Rounds half-way cases to the number |
1897 | /// with an even least significant digit. |
1898 | /// |
1899 | /// This intrinsic does not have a stable counterpart. |
1900 | #[rustc_nounwind ] |
1901 | pub fn roundevenf64(x: f64) -> f64; |
1902 | |
1903 | /// Float addition that allows optimizations based on algebraic rules. |
1904 | /// May assume inputs are finite. |
1905 | /// |
1906 | /// This intrinsic does not have a stable counterpart. |
1907 | #[rustc_nounwind ] |
1908 | pub fn fadd_fast<T: Copy>(a: T, b: T) -> T; |
1909 | |
1910 | /// Float subtraction that allows optimizations based on algebraic rules. |
1911 | /// May assume inputs are finite. |
1912 | /// |
1913 | /// This intrinsic does not have a stable counterpart. |
1914 | #[rustc_nounwind ] |
1915 | pub fn fsub_fast<T: Copy>(a: T, b: T) -> T; |
1916 | |
1917 | /// Float multiplication that allows optimizations based on algebraic rules. |
1918 | /// May assume inputs are finite. |
1919 | /// |
1920 | /// This intrinsic does not have a stable counterpart. |
1921 | #[rustc_nounwind ] |
1922 | pub fn fmul_fast<T: Copy>(a: T, b: T) -> T; |
1923 | |
1924 | /// Float division that allows optimizations based on algebraic rules. |
1925 | /// May assume inputs are finite. |
1926 | /// |
1927 | /// This intrinsic does not have a stable counterpart. |
1928 | #[rustc_nounwind ] |
1929 | pub fn fdiv_fast<T: Copy>(a: T, b: T) -> T; |
1930 | |
1931 | /// Float remainder that allows optimizations based on algebraic rules. |
1932 | /// May assume inputs are finite. |
1933 | /// |
1934 | /// This intrinsic does not have a stable counterpart. |
1935 | #[rustc_nounwind ] |
1936 | pub fn frem_fast<T: Copy>(a: T, b: T) -> T; |
1937 | |
1938 | /// Float addition that allows optimizations based on algebraic rules. |
1939 | /// |
1940 | /// This intrinsic does not have a stable counterpart. |
1941 | #[rustc_nounwind ] |
1942 | #[rustc_safe_intrinsic ] |
1943 | pub fn fadd_algebraic<T: Copy>(a: T, b: T) -> T; |
1944 | |
1945 | /// Float subtraction that allows optimizations based on algebraic rules. |
1946 | /// |
1947 | /// This intrinsic does not have a stable counterpart. |
1948 | #[rustc_nounwind ] |
1949 | #[rustc_safe_intrinsic ] |
1950 | pub fn fsub_algebraic<T: Copy>(a: T, b: T) -> T; |
1951 | |
1952 | /// Float multiplication that allows optimizations based on algebraic rules. |
1953 | /// |
1954 | /// This intrinsic does not have a stable counterpart. |
1955 | #[rustc_nounwind ] |
1956 | #[rustc_safe_intrinsic ] |
1957 | pub fn fmul_algebraic<T: Copy>(a: T, b: T) -> T; |
1958 | |
1959 | /// Float division that allows optimizations based on algebraic rules. |
1960 | /// |
1961 | /// This intrinsic does not have a stable counterpart. |
1962 | #[rustc_nounwind ] |
1963 | #[rustc_safe_intrinsic ] |
1964 | pub fn fdiv_algebraic<T: Copy>(a: T, b: T) -> T; |
1965 | |
1966 | /// Float remainder that allows optimizations based on algebraic rules. |
1967 | /// |
1968 | /// This intrinsic does not have a stable counterpart. |
1969 | #[rustc_nounwind ] |
1970 | #[rustc_safe_intrinsic ] |
1971 | pub fn frem_algebraic<T: Copy>(a: T, b: T) -> T; |
1972 | |
1973 | /// Convert with LLVM’s fptoui/fptosi, which may return undef for values out of range |
1974 | /// (<https://github.com/rust-lang/rust/issues/10184>) |
1975 | /// |
1976 | /// Stabilized as [`f32::to_int_unchecked`] and [`f64::to_int_unchecked`]. |
1977 | #[rustc_nounwind ] |
1978 | pub fn float_to_int_unchecked<Float: Copy, Int: Copy>(value: Float) -> Int; |
1979 | |
1980 | /// Returns the number of bits set in an integer type `T` |
1981 | /// |
1982 | /// Note that, unlike most intrinsics, this is safe to call; |
1983 | /// it does not require an `unsafe` block. |
1984 | /// Therefore, implementations must not require the user to uphold |
1985 | /// any safety invariants. |
1986 | /// |
1987 | /// The stabilized versions of this intrinsic are available on the integer |
1988 | /// primitives via the `count_ones` method. For example, |
1989 | /// [`u32::count_ones`] |
1990 | #[cfg (not(bootstrap))] |
1991 | #[rustc_const_stable (feature = "const_ctpop" , since = "1.40.0" )] |
1992 | #[rustc_safe_intrinsic ] |
1993 | #[rustc_nounwind ] |
1994 | pub fn ctpop<T: Copy>(x: T) -> u32; |
1995 | |
1996 | #[cfg (bootstrap)] |
1997 | #[rustc_const_stable (feature = "const_ctpop" , since = "1.40.0" )] |
1998 | #[rustc_safe_intrinsic ] |
1999 | #[rustc_nounwind ] |
2000 | pub fn ctpop<T: Copy>(x: T) -> T; |
2001 | |
2002 | /// Returns the number of leading unset bits (zeroes) in an integer type `T`. |
2003 | /// |
2004 | /// Note that, unlike most intrinsics, this is safe to call; |
2005 | /// it does not require an `unsafe` block. |
2006 | /// Therefore, implementations must not require the user to uphold |
2007 | /// any safety invariants. |
2008 | /// |
2009 | /// The stabilized versions of this intrinsic are available on the integer |
2010 | /// primitives via the `leading_zeros` method. For example, |
2011 | /// [`u32::leading_zeros`] |
2012 | /// |
2013 | /// # Examples |
2014 | /// |
2015 | /// ``` |
2016 | /// #![feature(core_intrinsics)] |
2017 | /// # #![allow(internal_features)] |
2018 | /// |
2019 | /// use std::intrinsics::ctlz; |
2020 | /// |
2021 | /// let x = 0b0001_1100_u8; |
2022 | /// let num_leading = ctlz(x); |
2023 | /// assert_eq!(num_leading, 3); |
2024 | /// ``` |
2025 | /// |
2026 | /// An `x` with value `0` will return the bit width of `T`. |
2027 | /// |
2028 | /// ``` |
2029 | /// #![feature(core_intrinsics)] |
2030 | /// # #![allow(internal_features)] |
2031 | /// |
2032 | /// use std::intrinsics::ctlz; |
2033 | /// |
2034 | /// let x = 0u16; |
2035 | /// let num_leading = ctlz(x); |
2036 | /// assert_eq!(num_leading, 16); |
2037 | /// ``` |
2038 | #[cfg (not(bootstrap))] |
2039 | #[rustc_const_stable (feature = "const_ctlz" , since = "1.40.0" )] |
2040 | #[rustc_safe_intrinsic ] |
2041 | #[rustc_nounwind ] |
2042 | pub fn ctlz<T: Copy>(x: T) -> u32; |
2043 | |
2044 | #[cfg (bootstrap)] |
2045 | #[rustc_const_stable (feature = "const_ctlz" , since = "1.40.0" )] |
2046 | #[rustc_safe_intrinsic ] |
2047 | #[rustc_nounwind ] |
2048 | pub fn ctlz<T: Copy>(x: T) -> T; |
2049 | |
2050 | /// Like `ctlz`, but extra-unsafe as it returns `undef` when |
2051 | /// given an `x` with value `0`. |
2052 | /// |
2053 | /// This intrinsic does not have a stable counterpart. |
2054 | /// |
2055 | /// # Examples |
2056 | /// |
2057 | /// ``` |
2058 | /// #![feature(core_intrinsics)] |
2059 | /// # #![allow(internal_features)] |
2060 | /// |
2061 | /// use std::intrinsics::ctlz_nonzero; |
2062 | /// |
2063 | /// let x = 0b0001_1100_u8; |
2064 | /// let num_leading = unsafe { ctlz_nonzero(x) }; |
2065 | /// assert_eq!(num_leading, 3); |
2066 | /// ``` |
2067 | #[cfg (not(bootstrap))] |
2068 | #[rustc_const_stable (feature = "constctlz" , since = "1.50.0" )] |
2069 | #[rustc_nounwind ] |
2070 | pub fn ctlz_nonzero<T: Copy>(x: T) -> u32; |
2071 | |
2072 | #[cfg (bootstrap)] |
2073 | #[rustc_const_stable (feature = "constctlz" , since = "1.50.0" )] |
2074 | #[rustc_nounwind ] |
2075 | pub fn ctlz_nonzero<T: Copy>(x: T) -> T; |
2076 | |
2077 | /// Returns the number of trailing unset bits (zeroes) in an integer type `T`. |
2078 | /// |
2079 | /// Note that, unlike most intrinsics, this is safe to call; |
2080 | /// it does not require an `unsafe` block. |
2081 | /// Therefore, implementations must not require the user to uphold |
2082 | /// any safety invariants. |
2083 | /// |
2084 | /// The stabilized versions of this intrinsic are available on the integer |
2085 | /// primitives via the `trailing_zeros` method. For example, |
2086 | /// [`u32::trailing_zeros`] |
2087 | /// |
2088 | /// # Examples |
2089 | /// |
2090 | /// ``` |
2091 | /// #![feature(core_intrinsics)] |
2092 | /// # #![allow(internal_features)] |
2093 | /// |
2094 | /// use std::intrinsics::cttz; |
2095 | /// |
2096 | /// let x = 0b0011_1000_u8; |
2097 | /// let num_trailing = cttz(x); |
2098 | /// assert_eq!(num_trailing, 3); |
2099 | /// ``` |
2100 | /// |
2101 | /// An `x` with value `0` will return the bit width of `T`: |
2102 | /// |
2103 | /// ``` |
2104 | /// #![feature(core_intrinsics)] |
2105 | /// # #![allow(internal_features)] |
2106 | /// |
2107 | /// use std::intrinsics::cttz; |
2108 | /// |
2109 | /// let x = 0u16; |
2110 | /// let num_trailing = cttz(x); |
2111 | /// assert_eq!(num_trailing, 16); |
2112 | /// ``` |
2113 | #[cfg (not(bootstrap))] |
2114 | #[rustc_const_stable (feature = "const_cttz" , since = "1.40.0" )] |
2115 | #[rustc_safe_intrinsic ] |
2116 | #[rustc_nounwind ] |
2117 | pub fn cttz<T: Copy>(x: T) -> u32; |
2118 | |
2119 | #[cfg (bootstrap)] |
2120 | #[rustc_const_stable (feature = "const_cttz" , since = "1.40.0" )] |
2121 | #[rustc_safe_intrinsic ] |
2122 | #[rustc_nounwind ] |
2123 | pub fn cttz<T: Copy>(x: T) -> T; |
2124 | |
2125 | /// Like `cttz`, but extra-unsafe as it returns `undef` when |
2126 | /// given an `x` with value `0`. |
2127 | /// |
2128 | /// This intrinsic does not have a stable counterpart. |
2129 | /// |
2130 | /// # Examples |
2131 | /// |
2132 | /// ``` |
2133 | /// #![feature(core_intrinsics)] |
2134 | /// # #![allow(internal_features)] |
2135 | /// |
2136 | /// use std::intrinsics::cttz_nonzero; |
2137 | /// |
2138 | /// let x = 0b0011_1000_u8; |
2139 | /// let num_trailing = unsafe { cttz_nonzero(x) }; |
2140 | /// assert_eq!(num_trailing, 3); |
2141 | /// ``` |
2142 | #[cfg (not(bootstrap))] |
2143 | #[rustc_const_stable (feature = "const_cttz_nonzero" , since = "1.53.0" )] |
2144 | #[rustc_nounwind ] |
2145 | pub fn cttz_nonzero<T: Copy>(x: T) -> u32; |
2146 | |
2147 | #[cfg (bootstrap)] |
2148 | #[rustc_const_stable (feature = "const_cttz_nonzero" , since = "1.53.0" )] |
2149 | #[rustc_nounwind ] |
2150 | pub fn cttz_nonzero<T: Copy>(x: T) -> T; |
2151 | |
2152 | /// Reverses the bytes in an integer type `T`. |
2153 | /// |
2154 | /// Note that, unlike most intrinsics, this is safe to call; |
2155 | /// it does not require an `unsafe` block. |
2156 | /// Therefore, implementations must not require the user to uphold |
2157 | /// any safety invariants. |
2158 | /// |
2159 | /// The stabilized versions of this intrinsic are available on the integer |
2160 | /// primitives via the `swap_bytes` method. For example, |
2161 | /// [`u32::swap_bytes`] |
2162 | #[rustc_const_stable (feature = "const_bswap" , since = "1.40.0" )] |
2163 | #[rustc_safe_intrinsic ] |
2164 | #[rustc_nounwind ] |
2165 | pub fn bswap<T: Copy>(x: T) -> T; |
2166 | |
2167 | /// Reverses the bits in an integer type `T`. |
2168 | /// |
2169 | /// Note that, unlike most intrinsics, this is safe to call; |
2170 | /// it does not require an `unsafe` block. |
2171 | /// Therefore, implementations must not require the user to uphold |
2172 | /// any safety invariants. |
2173 | /// |
2174 | /// The stabilized versions of this intrinsic are available on the integer |
2175 | /// primitives via the `reverse_bits` method. For example, |
2176 | /// [`u32::reverse_bits`] |
2177 | #[rustc_const_stable (feature = "const_bitreverse" , since = "1.40.0" )] |
2178 | #[rustc_safe_intrinsic ] |
2179 | #[rustc_nounwind ] |
2180 | pub fn bitreverse<T: Copy>(x: T) -> T; |
2181 | |
2182 | /// Does a three-way comparison between the two integer arguments. |
2183 | /// |
2184 | /// This is included as an intrinsic as it's useful to let it be one thing |
2185 | /// in MIR, rather than the multiple checks and switches that make its IR |
2186 | /// large and difficult to optimize. |
2187 | /// |
2188 | /// The stabilized version of this intrinsic is [`Ord::cmp`]. |
2189 | #[cfg (not(bootstrap))] |
2190 | #[rustc_const_unstable (feature = "const_three_way_compare" , issue = "none" )] |
2191 | #[rustc_safe_intrinsic ] |
2192 | pub fn three_way_compare<T: Copy>(lhs: T, rhs: T) -> crate::cmp::Ordering; |
2193 | |
2194 | /// Performs checked integer addition. |
2195 | /// |
2196 | /// Note that, unlike most intrinsics, this is safe to call; |
2197 | /// it does not require an `unsafe` block. |
2198 | /// Therefore, implementations must not require the user to uphold |
2199 | /// any safety invariants. |
2200 | /// |
2201 | /// The stabilized versions of this intrinsic are available on the integer |
2202 | /// primitives via the `overflowing_add` method. For example, |
2203 | /// [`u32::overflowing_add`] |
2204 | #[rustc_const_stable (feature = "const_int_overflow" , since = "1.40.0" )] |
2205 | #[rustc_safe_intrinsic ] |
2206 | #[rustc_nounwind ] |
2207 | pub fn add_with_overflow<T: Copy>(x: T, y: T) -> (T, bool); |
2208 | |
2209 | /// Performs checked integer subtraction |
2210 | /// |
2211 | /// Note that, unlike most intrinsics, this is safe to call; |
2212 | /// it does not require an `unsafe` block. |
2213 | /// Therefore, implementations must not require the user to uphold |
2214 | /// any safety invariants. |
2215 | /// |
2216 | /// The stabilized versions of this intrinsic are available on the integer |
2217 | /// primitives via the `overflowing_sub` method. For example, |
2218 | /// [`u32::overflowing_sub`] |
2219 | #[rustc_const_stable (feature = "const_int_overflow" , since = "1.40.0" )] |
2220 | #[rustc_safe_intrinsic ] |
2221 | #[rustc_nounwind ] |
2222 | pub fn sub_with_overflow<T: Copy>(x: T, y: T) -> (T, bool); |
2223 | |
2224 | /// Performs checked integer multiplication |
2225 | /// |
2226 | /// Note that, unlike most intrinsics, this is safe to call; |
2227 | /// it does not require an `unsafe` block. |
2228 | /// Therefore, implementations must not require the user to uphold |
2229 | /// any safety invariants. |
2230 | /// |
2231 | /// The stabilized versions of this intrinsic are available on the integer |
2232 | /// primitives via the `overflowing_mul` method. For example, |
2233 | /// [`u32::overflowing_mul`] |
2234 | #[rustc_const_stable (feature = "const_int_overflow" , since = "1.40.0" )] |
2235 | #[rustc_safe_intrinsic ] |
2236 | #[rustc_nounwind ] |
2237 | pub fn mul_with_overflow<T: Copy>(x: T, y: T) -> (T, bool); |
2238 | |
2239 | /// Performs an exact division, resulting in undefined behavior where |
2240 | /// `x % y != 0` or `y == 0` or `x == T::MIN && y == -1` |
2241 | /// |
2242 | /// This intrinsic does not have a stable counterpart. |
2243 | #[rustc_const_unstable (feature = "const_exact_div" , issue = "none" )] |
2244 | #[rustc_nounwind ] |
2245 | pub fn exact_div<T: Copy>(x: T, y: T) -> T; |
2246 | |
2247 | /// Performs an unchecked division, resulting in undefined behavior |
2248 | /// where `y == 0` or `x == T::MIN && y == -1` |
2249 | /// |
2250 | /// Safe wrappers for this intrinsic are available on the integer |
2251 | /// primitives via the `checked_div` method. For example, |
2252 | /// [`u32::checked_div`] |
2253 | #[rustc_const_stable (feature = "const_int_unchecked_div" , since = "1.52.0" )] |
2254 | #[rustc_nounwind ] |
2255 | pub fn unchecked_div<T: Copy>(x: T, y: T) -> T; |
2256 | /// Returns the remainder of an unchecked division, resulting in |
2257 | /// undefined behavior when `y == 0` or `x == T::MIN && y == -1` |
2258 | /// |
2259 | /// Safe wrappers for this intrinsic are available on the integer |
2260 | /// primitives via the `checked_rem` method. For example, |
2261 | /// [`u32::checked_rem`] |
2262 | #[rustc_const_stable (feature = "const_int_unchecked_rem" , since = "1.52.0" )] |
2263 | #[rustc_nounwind ] |
2264 | pub fn unchecked_rem<T: Copy>(x: T, y: T) -> T; |
2265 | |
2266 | /// Performs an unchecked left shift, resulting in undefined behavior when |
2267 | /// `y < 0` or `y >= N`, where N is the width of T in bits. |
2268 | /// |
2269 | /// Safe wrappers for this intrinsic are available on the integer |
2270 | /// primitives via the `checked_shl` method. For example, |
2271 | /// [`u32::checked_shl`] |
2272 | #[cfg (not(bootstrap))] |
2273 | #[rustc_const_stable (feature = "const_int_unchecked" , since = "1.40.0" )] |
2274 | #[rustc_nounwind ] |
2275 | pub fn unchecked_shl<T: Copy, U: Copy>(x: T, y: U) -> T; |
2276 | /// Performs an unchecked right shift, resulting in undefined behavior when |
2277 | /// `y < 0` or `y >= N`, where N is the width of T in bits. |
2278 | /// |
2279 | /// Safe wrappers for this intrinsic are available on the integer |
2280 | /// primitives via the `checked_shr` method. For example, |
2281 | /// [`u32::checked_shr`] |
2282 | #[cfg (not(bootstrap))] |
2283 | #[rustc_const_stable (feature = "const_int_unchecked" , since = "1.40.0" )] |
2284 | #[rustc_nounwind ] |
2285 | pub fn unchecked_shr<T: Copy, U: Copy>(x: T, y: U) -> T; |
2286 | |
2287 | /// Returns the result of an unchecked addition, resulting in |
2288 | /// undefined behavior when `x + y > T::MAX` or `x + y < T::MIN`. |
2289 | /// |
2290 | /// The stable counterpart of this intrinsic is `unchecked_add` on the various |
2291 | /// integer types, such as [`u16::unchecked_add`] and [`i64::unchecked_add`]. |
2292 | #[rustc_const_stable (feature = "unchecked_math" , since = "CURRENT_RUSTC_VERSION" )] |
2293 | #[rustc_nounwind ] |
2294 | pub fn unchecked_add<T: Copy>(x: T, y: T) -> T; |
2295 | |
2296 | /// Returns the result of an unchecked subtraction, resulting in |
2297 | /// undefined behavior when `x - y > T::MAX` or `x - y < T::MIN`. |
2298 | /// |
2299 | /// The stable counterpart of this intrinsic is `unchecked_sub` on the various |
2300 | /// integer types, such as [`u16::unchecked_sub`] and [`i64::unchecked_sub`]. |
2301 | #[rustc_const_stable (feature = "unchecked_math" , since = "CURRENT_RUSTC_VERSION" )] |
2302 | #[rustc_nounwind ] |
2303 | pub fn unchecked_sub<T: Copy>(x: T, y: T) -> T; |
2304 | |
2305 | /// Returns the result of an unchecked multiplication, resulting in |
2306 | /// undefined behavior when `x * y > T::MAX` or `x * y < T::MIN`. |
2307 | /// |
2308 | /// The stable counterpart of this intrinsic is `unchecked_mul` on the various |
2309 | /// integer types, such as [`u16::unchecked_mul`] and [`i64::unchecked_mul`]. |
2310 | #[rustc_const_stable (feature = "unchecked_math" , since = "CURRENT_RUSTC_VERSION" )] |
2311 | #[rustc_nounwind ] |
2312 | pub fn unchecked_mul<T: Copy>(x: T, y: T) -> T; |
2313 | |
2314 | /// Performs rotate left. |
2315 | /// |
2316 | /// Note that, unlike most intrinsics, this is safe to call; |
2317 | /// it does not require an `unsafe` block. |
2318 | /// Therefore, implementations must not require the user to uphold |
2319 | /// any safety invariants. |
2320 | /// |
2321 | /// The stabilized versions of this intrinsic are available on the integer |
2322 | /// primitives via the `rotate_left` method. For example, |
2323 | /// [`u32::rotate_left`] |
2324 | #[cfg (not(bootstrap))] |
2325 | #[rustc_const_stable (feature = "const_int_rotate" , since = "1.40.0" )] |
2326 | #[rustc_safe_intrinsic ] |
2327 | #[rustc_nounwind ] |
2328 | pub fn rotate_left<T: Copy>(x: T, shift: u32) -> T; |
2329 | |
2330 | #[cfg (bootstrap)] |
2331 | #[rustc_const_stable (feature = "const_int_rotate" , since = "1.40.0" )] |
2332 | #[rustc_safe_intrinsic ] |
2333 | #[rustc_nounwind ] |
2334 | pub fn rotate_left<T: Copy>(x: T, y: T) -> T; |
2335 | |
2336 | /// Performs rotate right. |
2337 | /// |
2338 | /// Note that, unlike most intrinsics, this is safe to call; |
2339 | /// it does not require an `unsafe` block. |
2340 | /// Therefore, implementations must not require the user to uphold |
2341 | /// any safety invariants. |
2342 | /// |
2343 | /// The stabilized versions of this intrinsic are available on the integer |
2344 | /// primitives via the `rotate_right` method. For example, |
2345 | /// [`u32::rotate_right`] |
2346 | #[cfg (not(bootstrap))] |
2347 | #[rustc_const_stable (feature = "const_int_rotate" , since = "1.40.0" )] |
2348 | #[rustc_safe_intrinsic ] |
2349 | #[rustc_nounwind ] |
2350 | pub fn rotate_right<T: Copy>(x: T, shift: u32) -> T; |
2351 | |
2352 | #[cfg (bootstrap)] |
2353 | #[rustc_const_stable (feature = "const_int_rotate" , since = "1.40.0" )] |
2354 | #[rustc_safe_intrinsic ] |
2355 | #[rustc_nounwind ] |
2356 | pub fn rotate_right<T: Copy>(x: T, y: T) -> T; |
2357 | |
2358 | /// Returns (a + b) mod 2<sup>N</sup>, where N is the width of T in bits. |
2359 | /// |
2360 | /// Note that, unlike most intrinsics, this is safe to call; |
2361 | /// it does not require an `unsafe` block. |
2362 | /// Therefore, implementations must not require the user to uphold |
2363 | /// any safety invariants. |
2364 | /// |
2365 | /// The stabilized versions of this intrinsic are available on the integer |
2366 | /// primitives via the `wrapping_add` method. For example, |
2367 | /// [`u32::wrapping_add`] |
2368 | #[rustc_const_stable (feature = "const_int_wrapping" , since = "1.40.0" )] |
2369 | #[rustc_safe_intrinsic ] |
2370 | #[rustc_nounwind ] |
2371 | pub fn wrapping_add<T: Copy>(a: T, b: T) -> T; |
2372 | /// Returns (a - b) mod 2<sup>N</sup>, where N is the width of T in bits. |
2373 | /// |
2374 | /// Note that, unlike most intrinsics, this is safe to call; |
2375 | /// it does not require an `unsafe` block. |
2376 | /// Therefore, implementations must not require the user to uphold |
2377 | /// any safety invariants. |
2378 | /// |
2379 | /// The stabilized versions of this intrinsic are available on the integer |
2380 | /// primitives via the `wrapping_sub` method. For example, |
2381 | /// [`u32::wrapping_sub`] |
2382 | #[rustc_const_stable (feature = "const_int_wrapping" , since = "1.40.0" )] |
2383 | #[rustc_safe_intrinsic ] |
2384 | #[rustc_nounwind ] |
2385 | pub fn wrapping_sub<T: Copy>(a: T, b: T) -> T; |
2386 | /// Returns (a * b) mod 2<sup>N</sup>, where N is the width of T in bits. |
2387 | /// |
2388 | /// Note that, unlike most intrinsics, this is safe to call; |
2389 | /// it does not require an `unsafe` block. |
2390 | /// Therefore, implementations must not require the user to uphold |
2391 | /// any safety invariants. |
2392 | /// |
2393 | /// The stabilized versions of this intrinsic are available on the integer |
2394 | /// primitives via the `wrapping_mul` method. For example, |
2395 | /// [`u32::wrapping_mul`] |
2396 | #[rustc_const_stable (feature = "const_int_wrapping" , since = "1.40.0" )] |
2397 | #[rustc_safe_intrinsic ] |
2398 | #[rustc_nounwind ] |
2399 | pub fn wrapping_mul<T: Copy>(a: T, b: T) -> T; |
2400 | |
2401 | /// Computes `a + b`, saturating at numeric bounds. |
2402 | /// |
2403 | /// Note that, unlike most intrinsics, this is safe to call; |
2404 | /// it does not require an `unsafe` block. |
2405 | /// Therefore, implementations must not require the user to uphold |
2406 | /// any safety invariants. |
2407 | /// |
2408 | /// The stabilized versions of this intrinsic are available on the integer |
2409 | /// primitives via the `saturating_add` method. For example, |
2410 | /// [`u32::saturating_add`] |
2411 | #[rustc_const_stable (feature = "const_int_saturating" , since = "1.40.0" )] |
2412 | #[rustc_safe_intrinsic ] |
2413 | #[rustc_nounwind ] |
2414 | pub fn saturating_add<T: Copy>(a: T, b: T) -> T; |
2415 | /// Computes `a - b`, saturating at numeric bounds. |
2416 | /// |
2417 | /// Note that, unlike most intrinsics, this is safe to call; |
2418 | /// it does not require an `unsafe` block. |
2419 | /// Therefore, implementations must not require the user to uphold |
2420 | /// any safety invariants. |
2421 | /// |
2422 | /// The stabilized versions of this intrinsic are available on the integer |
2423 | /// primitives via the `saturating_sub` method. For example, |
2424 | /// [`u32::saturating_sub`] |
2425 | #[rustc_const_stable (feature = "const_int_saturating" , since = "1.40.0" )] |
2426 | #[rustc_safe_intrinsic ] |
2427 | #[rustc_nounwind ] |
2428 | pub fn saturating_sub<T: Copy>(a: T, b: T) -> T; |
2429 | |
2430 | /// This is an implementation detail of [`crate::ptr::read`] and should |
2431 | /// not be used anywhere else. See its comments for why this exists. |
2432 | /// |
2433 | /// This intrinsic can *only* be called where the pointer is a local without |
2434 | /// projections (`read_via_copy(ptr)`, not `read_via_copy(*ptr)`) so that it |
2435 | /// trivially obeys runtime-MIR rules about derefs in operands. |
2436 | #[rustc_const_stable (feature = "const_ptr_read" , since = "1.71.0" )] |
2437 | #[rustc_nounwind ] |
2438 | pub fn read_via_copy<T>(ptr: *const T) -> T; |
2439 | |
2440 | /// This is an implementation detail of [`crate::ptr::write`] and should |
2441 | /// not be used anywhere else. See its comments for why this exists. |
2442 | /// |
2443 | /// This intrinsic can *only* be called where the pointer is a local without |
2444 | /// projections (`write_via_move(ptr, x)`, not `write_via_move(*ptr, x)`) so |
2445 | /// that it trivially obeys runtime-MIR rules about derefs in operands. |
2446 | #[rustc_const_unstable (feature = "const_ptr_write" , issue = "86302" )] |
2447 | #[rustc_nounwind ] |
2448 | pub fn write_via_move<T>(ptr: *mut T, value: T); |
2449 | |
2450 | /// Returns the value of the discriminant for the variant in 'v'; |
2451 | /// if `T` has no discriminant, returns `0`. |
2452 | /// |
2453 | /// Note that, unlike most intrinsics, this is safe to call; |
2454 | /// it does not require an `unsafe` block. |
2455 | /// Therefore, implementations must not require the user to uphold |
2456 | /// any safety invariants. |
2457 | /// |
2458 | /// The stabilized version of this intrinsic is [`core::mem::discriminant`]. |
2459 | #[rustc_const_stable (feature = "const_discriminant" , since = "1.75.0" )] |
2460 | #[rustc_safe_intrinsic ] |
2461 | #[rustc_nounwind ] |
2462 | pub fn discriminant_value<T>(v: &T) -> <T as DiscriminantKind>::Discriminant; |
2463 | |
2464 | /// Returns the number of variants of the type `T` cast to a `usize`; |
2465 | /// if `T` has no variants, returns `0`. Uninhabited variants will be counted. |
2466 | /// |
2467 | /// Note that, unlike most intrinsics, this is safe to call; |
2468 | /// it does not require an `unsafe` block. |
2469 | /// Therefore, implementations must not require the user to uphold |
2470 | /// any safety invariants. |
2471 | /// |
2472 | /// The to-be-stabilized version of this intrinsic is [`crate::mem::variant_count`]. |
2473 | #[rustc_const_unstable (feature = "variant_count" , issue = "73662" )] |
2474 | #[rustc_safe_intrinsic ] |
2475 | #[rustc_nounwind ] |
2476 | pub fn variant_count<T>() -> usize; |
2477 | |
2478 | /// Rust's "try catch" construct for unwinding. Invokes the function pointer `try_fn` with the |
2479 | /// data pointer `data`, and calls `catch_fn` if unwinding occurs while `try_fn` runs. |
2480 | /// |
2481 | /// `catch_fn` must not unwind. |
2482 | /// |
2483 | /// The third argument is a function called if an unwind occurs (both Rust unwinds and foreign |
2484 | /// unwinds). This function takes the data pointer and a pointer to the target-specific |
2485 | /// exception object that was caught. For more information, see the compiler's source as well as |
2486 | /// std's `catch_unwind` implementation. |
2487 | /// |
2488 | /// The stable version of this intrinsic is `std::panic::catch_unwind`. |
2489 | #[rustc_nounwind ] |
2490 | pub fn catch_unwind(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32; |
2491 | |
2492 | /// Emits a `!nontemporal` store according to LLVM (see their docs). |
2493 | /// Probably will never become stable. |
2494 | /// |
2495 | /// Do NOT use this intrinsic; "nontemporal" operations do not exist in our memory model! |
2496 | /// It exists to support current stdarch, but the plan is to change stdarch and remove this intrinsic. |
2497 | /// See <https://github.com/rust-lang/rust/issues/114582> for some more discussion. |
2498 | #[rustc_nounwind ] |
2499 | pub fn nontemporal_store<T>(ptr: *mut T, val: T); |
2500 | |
2501 | /// See documentation of `<*const T>::offset_from` for details. |
2502 | #[rustc_const_stable (feature = "const_ptr_offset_from" , since = "1.65.0" )] |
2503 | #[rustc_nounwind ] |
2504 | pub fn ptr_offset_from<T>(ptr: *const T, base: *const T) -> isize; |
2505 | |
2506 | /// See documentation of `<*const T>::sub_ptr` for details. |
2507 | #[rustc_const_unstable (feature = "const_ptr_sub_ptr" , issue = "95892" )] |
2508 | #[rustc_nounwind ] |
2509 | pub fn ptr_offset_from_unsigned<T>(ptr: *const T, base: *const T) -> usize; |
2510 | |
2511 | #[rustc_const_unstable (feature = "const_raw_ptr_comparison" , issue = "53020" )] |
2512 | #[rustc_safe_intrinsic ] |
2513 | #[rustc_nounwind ] |
2514 | #[cfg (bootstrap)] |
2515 | pub fn ptr_guaranteed_cmp<T>(ptr: *const T, other: *const T) -> u8; |
2516 | } |
2517 | |
2518 | /// See documentation of `<*const T>::guaranteed_eq` for details. |
2519 | /// Returns `2` if the result is unknown. |
2520 | /// Returns `1` if the pointers are guaranteed equal |
2521 | /// Returns `0` if the pointers are guaranteed inequal |
2522 | #[rustc_const_unstable (feature = "const_raw_ptr_comparison" , issue = "53020" )] |
2523 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2524 | #[rustc_intrinsic] |
2525 | #[cfg (not(bootstrap))] |
2526 | #[rustc_nounwind ] |
2527 | #[rustc_do_not_const_check ] |
2528 | #[inline ] |
2529 | pub const fn ptr_guaranteed_cmp<T>(ptr: *const T, other: *const T) -> u8 { |
2530 | (ptr == other) as u8 |
2531 | } |
2532 | |
2533 | extern "rust-intrinsic" { |
2534 | /// Determines whether the raw bytes of the two values are equal. |
2535 | /// |
2536 | /// This is particularly handy for arrays, since it allows things like just |
2537 | /// comparing `i96`s instead of forcing `alloca`s for `[6 x i16]`. |
2538 | /// |
2539 | /// Above some backend-decided threshold this will emit calls to `memcmp`, |
2540 | /// like slice equality does, instead of causing massive code size. |
2541 | /// |
2542 | /// Since this works by comparing the underlying bytes, the actual `T` is |
2543 | /// not particularly important. It will be used for its size and alignment, |
2544 | /// but any validity restrictions will be ignored, not enforced. |
2545 | /// |
2546 | /// # Safety |
2547 | /// |
2548 | /// It's UB to call this if any of the *bytes* in `*a` or `*b` are uninitialized or carry a |
2549 | /// pointer value. |
2550 | /// Note that this is a stricter criterion than just the *values* being |
2551 | /// fully-initialized: if `T` has padding, it's UB to call this intrinsic. |
2552 | /// |
2553 | /// (The implementation is allowed to branch on the results of comparisons, |
2554 | /// which is UB if any of their inputs are `undef`.) |
2555 | #[rustc_const_unstable (feature = "const_intrinsic_raw_eq" , issue = "none" )] |
2556 | #[rustc_nounwind ] |
2557 | pub fn raw_eq<T>(a: &T, b: &T) -> bool; |
2558 | |
2559 | /// Lexicographically compare `[left, left + bytes)` and `[right, right + bytes)` |
2560 | /// as unsigned bytes, returning negative if `left` is less, zero if all the |
2561 | /// bytes match, or positive if `right` is greater. |
2562 | /// |
2563 | /// This underlies things like `<[u8]>::cmp`, and will usually lower to `memcmp`. |
2564 | /// |
2565 | /// # Safety |
2566 | /// |
2567 | /// `left` and `right` must each be [valid] for reads of `bytes` bytes. |
2568 | /// |
2569 | /// Note that this applies to the whole range, not just until the first byte |
2570 | /// that differs. That allows optimizations that can read in large chunks. |
2571 | /// |
2572 | /// [valid]: crate::ptr#safety |
2573 | #[rustc_const_unstable (feature = "const_intrinsic_compare_bytes" , issue = "none" )] |
2574 | #[rustc_nounwind ] |
2575 | pub fn compare_bytes(left: *const u8, right: *const u8, bytes: usize) -> i32; |
2576 | |
2577 | /// See documentation of [`std::hint::black_box`] for details. |
2578 | /// |
2579 | /// [`std::hint::black_box`]: crate::hint::black_box |
2580 | #[rustc_const_unstable (feature = "const_black_box" , issue = "none" )] |
2581 | #[rustc_safe_intrinsic ] |
2582 | #[rustc_nounwind ] |
2583 | pub fn black_box<T>(dummy: T) -> T; |
2584 | |
2585 | #[rustc_nounwind ] |
2586 | #[cfg (bootstrap)] |
2587 | pub fn vtable_size(ptr: *const ()) -> usize; |
2588 | |
2589 | /// `ptr` must point to a vtable. |
2590 | /// The intrinsic will return the alignment stored in that vtable. |
2591 | #[rustc_nounwind ] |
2592 | #[cfg (bootstrap)] |
2593 | pub fn vtable_align(ptr: *const ()) -> usize; |
2594 | |
2595 | #[rustc_const_unstable (feature = "const_eval_select" , issue = "none" )] |
2596 | #[rustc_safe_intrinsic ] |
2597 | #[cfg (bootstrap)] |
2598 | pub fn const_eval_select<ARG: Tuple, F, G, RET>( |
2599 | arg: ARG, |
2600 | called_in_const: F, |
2601 | called_at_rt: G, |
2602 | ) -> RET |
2603 | where |
2604 | G: FnOnce<ARG, Output = RET>, |
2605 | F: FnOnce<ARG, Output = RET>; |
2606 | } |
2607 | |
2608 | /// Selects which function to call depending on the context. |
2609 | /// |
2610 | /// If this function is evaluated at compile-time, then a call to this |
2611 | /// intrinsic will be replaced with a call to `called_in_const`. It gets |
2612 | /// replaced with a call to `called_at_rt` otherwise. |
2613 | /// |
2614 | /// This function is safe to call, but note the stability concerns below. |
2615 | /// |
2616 | /// # Type Requirements |
2617 | /// |
2618 | /// The two functions must be both function items. They cannot be function |
2619 | /// pointers or closures. The first function must be a `const fn`. |
2620 | /// |
2621 | /// `arg` will be the tupled arguments that will be passed to either one of |
2622 | /// the two functions, therefore, both functions must accept the same type of |
2623 | /// arguments. Both functions must return RET. |
2624 | /// |
2625 | /// # Stability concerns |
2626 | /// |
2627 | /// Rust has not yet decided that `const fn` are allowed to tell whether |
2628 | /// they run at compile-time or at runtime. Therefore, when using this |
2629 | /// intrinsic anywhere that can be reached from stable, it is crucial that |
2630 | /// the end-to-end behavior of the stable `const fn` is the same for both |
2631 | /// modes of execution. (Here, Undefined Behavior is considered "the same" |
2632 | /// as any other behavior, so if the function exhibits UB at runtime then |
2633 | /// it may do whatever it wants at compile-time.) |
2634 | /// |
2635 | /// Here is an example of how this could cause a problem: |
2636 | /// ```no_run |
2637 | /// #![feature(const_eval_select)] |
2638 | /// #![feature(core_intrinsics)] |
2639 | /// # #![allow(internal_features)] |
2640 | /// # #![cfg_attr(bootstrap, allow(unused))] |
2641 | /// use std::intrinsics::const_eval_select; |
2642 | /// |
2643 | /// // Standard library |
2644 | /// # #[cfg (not(bootstrap))] |
2645 | /// pub const fn inconsistent() -> i32 { |
2646 | /// fn runtime() -> i32 { 1 } |
2647 | /// const fn compiletime() -> i32 { 2 } |
2648 | /// |
2649 | // // ⚠ This code violates the required equivalence of `compiletime` |
2650 | /// // and `runtime`. |
2651 | /// const_eval_select((), compiletime, runtime) |
2652 | /// } |
2653 | /// # #[cfg (bootstrap)] |
2654 | /// # pub const fn inconsistent() -> i32 { 0 } |
2655 | /// |
2656 | /// // User Crate |
2657 | /// const X: i32 = inconsistent(); |
2658 | /// let x = inconsistent(); |
2659 | /// assert_eq!(x, X); |
2660 | /// ``` |
2661 | /// |
2662 | /// Currently such an assertion would always succeed; until Rust decides |
2663 | /// otherwise, that principle should not be violated. |
2664 | #[rustc_const_unstable (feature = "const_eval_select" , issue = "none" )] |
2665 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2666 | #[cfg (not(bootstrap))] |
2667 | #[rustc_intrinsic] |
2668 | #[rustc_intrinsic_must_be_overridden] |
2669 | pub const fn const_eval_select<ARG: Tuple, F, G, RET>( |
2670 | _arg: ARG, |
2671 | _called_in_const: F, |
2672 | _called_at_rt: G, |
2673 | ) -> RET |
2674 | where |
2675 | G: FnOnce<ARG, Output = RET>, |
2676 | F: FnOnce<ARG, Output = RET>, |
2677 | { |
2678 | unreachable!() |
2679 | } |
2680 | |
2681 | /// Returns whether the argument's value is statically known at |
2682 | /// compile-time. |
2683 | /// |
2684 | /// This is useful when there is a way of writing the code that will |
2685 | /// be *faster* when some variables have known values, but *slower* |
2686 | /// in the general case: an `if is_val_statically_known(var)` can be used |
2687 | /// to select between these two variants. The `if` will be optimized away |
2688 | /// and only the desired branch remains. |
2689 | /// |
2690 | /// Formally speaking, this function non-deterministically returns `true` |
2691 | /// or `false`, and the caller has to ensure sound behavior for both cases. |
2692 | /// In other words, the following code has *Undefined Behavior*: |
2693 | /// |
2694 | /// ```no_run |
2695 | /// #![feature(is_val_statically_known)] |
2696 | /// #![feature(core_intrinsics)] |
2697 | /// # #![allow(internal_features)] |
2698 | /// use std::hint::unreachable_unchecked; |
2699 | /// use std::intrinsics::is_val_statically_known; |
2700 | /// |
2701 | /// if !is_val_statically_known(0) { unsafe { unreachable_unchecked(); } } |
2702 | /// ``` |
2703 | /// |
2704 | /// This also means that the following code's behavior is unspecified; it |
2705 | /// may panic, or it may not: |
2706 | /// |
2707 | /// ```no_run |
2708 | /// #![feature(is_val_statically_known)] |
2709 | /// #![feature(core_intrinsics)] |
2710 | /// # #![allow(internal_features)] |
2711 | /// use std::intrinsics::is_val_statically_known; |
2712 | /// |
2713 | /// assert_eq!(is_val_statically_known(0), is_val_statically_known(0)); |
2714 | /// ``` |
2715 | /// |
2716 | /// Unsafe code may not rely on `is_val_statically_known` returning any |
2717 | /// particular value, ever. However, the compiler will generally make it |
2718 | /// return `true` only if the value of the argument is actually known. |
2719 | /// |
2720 | /// When calling this in a `const fn`, both paths must be semantically |
2721 | /// equivalent, that is, the result of the `true` branch and the `false` |
2722 | /// branch must return the same value and have the same side-effects *no |
2723 | /// matter what*. |
2724 | #[rustc_const_unstable (feature = "is_val_statically_known" , issue = "none" )] |
2725 | #[rustc_nounwind ] |
2726 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2727 | #[rustc_intrinsic] |
2728 | pub const fn is_val_statically_known<T: Copy>(_arg: T) -> bool { |
2729 | false |
2730 | } |
2731 | |
2732 | /// Non-overlapping *typed* swap of a single value. |
2733 | /// |
2734 | /// The codegen backends will replace this with a better implementation when |
2735 | /// `T` is a simple type that can be loaded and stored as an immediate. |
2736 | /// |
2737 | /// The stabilized form of this intrinsic is [`crate::mem::swap`]. |
2738 | /// |
2739 | /// # Safety |
2740 | /// |
2741 | /// `x` and `y` are readable and writable as `T`, and non-overlapping. |
2742 | #[rustc_nounwind ] |
2743 | #[inline ] |
2744 | #[cfg_attr (not(bootstrap), rustc_intrinsic)] |
2745 | // This has fallback `const fn` MIR, so shouldn't need stability, see #122652 |
2746 | #[rustc_const_unstable (feature = "const_typed_swap" , issue = "none" )] |
2747 | pub const unsafe fn typed_swap<T>(x: *mut T, y: *mut T) { |
2748 | // SAFETY: The caller provided single non-overlapping items behind |
2749 | // pointers, so swapping them with `count: 1` is fine. |
2750 | unsafe { ptr::swap_nonoverlapping(x, y, count:1) }; |
2751 | } |
2752 | |
2753 | /// Returns whether we should perform some UB-checking at runtime. This eventually evaluates to |
2754 | /// `cfg!(ub_checks)`, but behaves different from `cfg!` when mixing crates built with different |
2755 | /// flags: if the crate has UB checks enabled or carries the `#[rustc_preserve_ub_checks]` |
2756 | /// attribute, evaluation is delayed until monomorphization (or until the call gets inlined into |
2757 | /// a crate that does not delay evaluation further); otherwise it can happen any time. |
2758 | /// |
2759 | /// The common case here is a user program built with ub_checks linked against the distributed |
2760 | /// sysroot which is built without ub_checks but with `#[rustc_preserve_ub_checks]`. |
2761 | /// For code that gets monomorphized in the user crate (i.e., generic functions and functions with |
2762 | /// `#[inline]`), gating assertions on `ub_checks()` rather than `cfg!(ub_checks)` means that |
2763 | /// assertions are enabled whenever the *user crate* has UB checks enabled. However if the |
2764 | /// user has UB checks disabled, the checks will still get optimized out. This intrinsic is |
2765 | /// primarily used by [`ub_checks::assert_unsafe_precondition`]. |
2766 | #[rustc_const_unstable (feature = "const_ub_checks" , issue = "none" )] |
2767 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2768 | #[inline (always)] |
2769 | #[cfg_attr (not(bootstrap), rustc_intrinsic)] // just make it a regular fn in bootstrap |
2770 | pub(crate) const fn ub_checks() -> bool { |
2771 | cfg!(debug_assertions) |
2772 | } |
2773 | |
2774 | /// Allocates a block of memory at compile time. |
2775 | /// At runtime, just returns a null pointer. |
2776 | /// |
2777 | /// # Safety |
2778 | /// |
2779 | /// - The `align` argument must be a power of two. |
2780 | /// - At compile time, a compile error occurs if this constraint is violated. |
2781 | /// - At runtime, it is not checked. |
2782 | #[rustc_const_unstable (feature = "const_heap" , issue = "79597" )] |
2783 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2784 | #[rustc_nounwind ] |
2785 | #[rustc_intrinsic] |
2786 | pub const unsafe fn const_allocate(_size: usize, _align: usize) -> *mut u8 { |
2787 | // const eval overrides this function, but runtime code should always just return null pointers. |
2788 | crate::ptr::null_mut() |
2789 | } |
2790 | |
2791 | /// Deallocates a memory which allocated by `intrinsics::const_allocate` at compile time. |
2792 | /// At runtime, does nothing. |
2793 | /// |
2794 | /// # Safety |
2795 | /// |
2796 | /// - The `align` argument must be a power of two. |
2797 | /// - At compile time, a compile error occurs if this constraint is violated. |
2798 | /// - At runtime, it is not checked. |
2799 | /// - If the `ptr` is created in an another const, this intrinsic doesn't deallocate it. |
2800 | /// - If the `ptr` is pointing to a local variable, this intrinsic doesn't deallocate it. |
2801 | #[rustc_const_unstable (feature = "const_heap" , issue = "79597" )] |
2802 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2803 | #[rustc_nounwind ] |
2804 | #[rustc_intrinsic] |
2805 | pub const unsafe fn const_deallocate(_ptr: *mut u8, _size: usize, _align: usize) {} |
2806 | |
2807 | /// `ptr` must point to a vtable. |
2808 | /// The intrinsic will return the size stored in that vtable. |
2809 | #[rustc_nounwind ] |
2810 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2811 | #[rustc_intrinsic] |
2812 | #[rustc_intrinsic_must_be_overridden] |
2813 | #[cfg (not(bootstrap))] |
2814 | pub unsafe fn vtable_size(_ptr: *const ()) -> usize { |
2815 | unreachable!() |
2816 | } |
2817 | |
2818 | /// `ptr` must point to a vtable. |
2819 | /// The intrinsic will return the alignment stored in that vtable. |
2820 | #[rustc_nounwind ] |
2821 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2822 | #[rustc_intrinsic] |
2823 | #[rustc_intrinsic_must_be_overridden] |
2824 | #[cfg (not(bootstrap))] |
2825 | pub unsafe fn vtable_align(_ptr: *const ()) -> usize { |
2826 | unreachable!() |
2827 | } |
2828 | |
2829 | /// Lowers in MIR to `Rvalue::Aggregate` with `AggregateKind::RawPtr`. |
2830 | /// |
2831 | /// This is used to implement functions like `slice::from_raw_parts_mut` and |
2832 | /// `ptr::from_raw_parts` in a way compatible with the compiler being able to |
2833 | /// change the possible layouts of pointers. |
2834 | #[rustc_nounwind ] |
2835 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2836 | #[rustc_const_unstable (feature = "ptr_metadata" , issue = "81513" )] |
2837 | #[rustc_intrinsic] |
2838 | #[rustc_intrinsic_must_be_overridden] |
2839 | #[cfg (not(bootstrap))] |
2840 | pub const fn aggregate_raw_ptr<P: AggregateRawPtr<D, Metadata = M>, D, M>(_data: D, _meta: M) -> P { |
2841 | // To implement a fallback we'd have to assume the layout of the pointer, |
2842 | // but the whole point of this intrinsic is that we shouldn't do that. |
2843 | unreachable!() |
2844 | } |
2845 | |
2846 | #[unstable (feature = "core_intrinsics" , issue = "none" )] |
2847 | pub trait AggregateRawPtr<D> { |
2848 | type Metadata: Copy; |
2849 | } |
2850 | impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*const T> for *const P { |
2851 | type Metadata = <P as ptr::Pointee>::Metadata; |
2852 | } |
2853 | impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*mut T> for *mut P { |
2854 | type Metadata = <P as ptr::Pointee>::Metadata; |
2855 | } |
2856 | |
2857 | // Some functions are defined here because they accidentally got made |
2858 | // available in this module on stable. See <https://github.com/rust-lang/rust/issues/15702>. |
2859 | // (`transmute` also falls into this category, but it cannot be wrapped due to the |
2860 | // check that `T` and `U` have the same size.) |
2861 | |
2862 | /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source |
2863 | /// and destination must *not* overlap. |
2864 | /// |
2865 | /// For regions of memory which might overlap, use [`copy`] instead. |
2866 | /// |
2867 | /// `copy_nonoverlapping` is semantically equivalent to C's [`memcpy`], but |
2868 | /// with the argument order swapped. |
2869 | /// |
2870 | /// The copy is "untyped" in the sense that data may be uninitialized or otherwise violate the |
2871 | /// requirements of `T`. The initialization state is preserved exactly. |
2872 | /// |
2873 | /// [`memcpy`]: https://en.cppreference.com/w/c/string/byte/memcpy |
2874 | /// |
2875 | /// # Safety |
2876 | /// |
2877 | /// Behavior is undefined if any of the following conditions are violated: |
2878 | /// |
2879 | /// * `src` must be [valid] for reads of `count * size_of::<T>()` bytes. |
2880 | /// |
2881 | /// * `dst` must be [valid] for writes of `count * size_of::<T>()` bytes. |
2882 | /// |
2883 | /// * Both `src` and `dst` must be properly aligned. |
2884 | /// |
2885 | /// * The region of memory beginning at `src` with a size of `count * |
2886 | /// size_of::<T>()` bytes must *not* overlap with the region of memory |
2887 | /// beginning at `dst` with the same size. |
2888 | /// |
2889 | /// Like [`read`], `copy_nonoverlapping` creates a bitwise copy of `T`, regardless of |
2890 | /// whether `T` is [`Copy`]. If `T` is not [`Copy`], using *both* the values |
2891 | /// in the region beginning at `*src` and the region beginning at `*dst` can |
2892 | /// [violate memory safety][read-ownership]. |
2893 | /// |
2894 | /// Note that even if the effectively copied size (`count * size_of::<T>()`) is |
2895 | /// `0`, the pointers must be non-null and properly aligned. |
2896 | /// |
2897 | /// [`read`]: crate::ptr::read |
2898 | /// [read-ownership]: crate::ptr::read#ownership-of-the-returned-value |
2899 | /// [valid]: crate::ptr#safety |
2900 | /// |
2901 | /// # Examples |
2902 | /// |
2903 | /// Manually implement [`Vec::append`]: |
2904 | /// |
2905 | /// ``` |
2906 | /// use std::ptr; |
2907 | /// |
2908 | /// /// Moves all the elements of `src` into `dst`, leaving `src` empty. |
2909 | /// fn append<T>(dst: &mut Vec<T>, src: &mut Vec<T>) { |
2910 | /// let src_len = src.len(); |
2911 | /// let dst_len = dst.len(); |
2912 | /// |
2913 | /// // Ensure that `dst` has enough capacity to hold all of `src`. |
2914 | /// dst.reserve(src_len); |
2915 | /// |
2916 | /// unsafe { |
2917 | /// // The call to add is always safe because `Vec` will never |
2918 | /// // allocate more than `isize::MAX` bytes. |
2919 | /// let dst_ptr = dst.as_mut_ptr().add(dst_len); |
2920 | /// let src_ptr = src.as_ptr(); |
2921 | /// |
2922 | /// // Truncate `src` without dropping its contents. We do this first, |
2923 | /// // to avoid problems in case something further down panics. |
2924 | /// src.set_len(0); |
2925 | /// |
2926 | /// // The two regions cannot overlap because mutable references do |
2927 | /// // not alias, and two different vectors cannot own the same |
2928 | /// // memory. |
2929 | /// ptr::copy_nonoverlapping(src_ptr, dst_ptr, src_len); |
2930 | /// |
2931 | /// // Notify `dst` that it now holds the contents of `src`. |
2932 | /// dst.set_len(dst_len + src_len); |
2933 | /// } |
2934 | /// } |
2935 | /// |
2936 | /// let mut a = vec!['r' ]; |
2937 | /// let mut b = vec!['u' , 's' , 't' ]; |
2938 | /// |
2939 | /// append(&mut a, &mut b); |
2940 | /// |
2941 | /// assert_eq!(a, &['r' , 'u' , 's' , 't' ]); |
2942 | /// assert!(b.is_empty()); |
2943 | /// ``` |
2944 | /// |
2945 | /// [`Vec::append`]: ../../std/vec/struct.Vec.html#method.append |
2946 | #[doc (alias = "memcpy" )] |
2947 | #[stable (feature = "rust1" , since = "1.0.0" )] |
2948 | #[rustc_allowed_through_unstable_modules ] |
2949 | #[rustc_const_unstable (feature = "const_intrinsic_copy" , issue = "80697" )] |
2950 | #[inline (always)] |
2951 | #[cfg_attr (miri, track_caller)] // even without panics, this helps for Miri backtraces |
2952 | #[rustc_diagnostic_item = "ptr_copy_nonoverlapping" ] |
2953 | pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) { |
2954 | extern "rust-intrinsic" { |
2955 | #[rustc_const_unstable (feature = "const_intrinsic_copy" , issue = "80697" )] |
2956 | #[rustc_nounwind ] |
2957 | pub fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize); |
2958 | } |
2959 | |
2960 | ub_checks::assert_unsafe_precondition!( |
2961 | check_language_ub, |
2962 | "ptr::copy_nonoverlapping requires that both pointer arguments are aligned and non-null \ |
2963 | and the specified memory ranges do not overlap" , |
2964 | ( |
2965 | src: *const () = src as *const (), |
2966 | dst: *mut () = dst as *mut (), |
2967 | size: usize = size_of::<T>(), |
2968 | align: usize = align_of::<T>(), |
2969 | count: usize = count, |
2970 | ) => |
2971 | ub_checks::is_aligned_and_not_null(src, align) |
2972 | && ub_checks::is_aligned_and_not_null(dst, align) |
2973 | && ub_checks::is_nonoverlapping(src, dst, size, count) |
2974 | ); |
2975 | |
2976 | // SAFETY: the safety contract for `copy_nonoverlapping` must be |
2977 | // upheld by the caller. |
2978 | unsafe { copy_nonoverlapping(src, dst, count) } |
2979 | } |
2980 | |
2981 | /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source |
2982 | /// and destination may overlap. |
2983 | /// |
2984 | /// If the source and destination will *never* overlap, |
2985 | /// [`copy_nonoverlapping`] can be used instead. |
2986 | /// |
2987 | /// `copy` is semantically equivalent to C's [`memmove`], but with the argument |
2988 | /// order swapped. Copying takes place as if the bytes were copied from `src` |
2989 | /// to a temporary array and then copied from the array to `dst`. |
2990 | /// |
2991 | /// The copy is "untyped" in the sense that data may be uninitialized or otherwise violate the |
2992 | /// requirements of `T`. The initialization state is preserved exactly. |
2993 | /// |
2994 | /// [`memmove`]: https://en.cppreference.com/w/c/string/byte/memmove |
2995 | /// |
2996 | /// # Safety |
2997 | /// |
2998 | /// Behavior is undefined if any of the following conditions are violated: |
2999 | /// |
3000 | /// * `src` must be [valid] for reads of `count * size_of::<T>()` bytes, and must remain valid even |
3001 | /// when `dst` is written for `count * size_of::<T>()` bytes. (This means if the memory ranges |
3002 | /// overlap, the two pointers must not be subject to aliasing restrictions relative to each |
3003 | /// other.) |
3004 | /// |
3005 | /// * `dst` must be [valid] for writes of `count * size_of::<T>()` bytes, and must remain valid even |
3006 | /// when `src` is read for `count * size_of::<T>()` bytes. |
3007 | /// |
3008 | /// * Both `src` and `dst` must be properly aligned. |
3009 | /// |
3010 | /// Like [`read`], `copy` creates a bitwise copy of `T`, regardless of |
3011 | /// whether `T` is [`Copy`]. If `T` is not [`Copy`], using both the values |
3012 | /// in the region beginning at `*src` and the region beginning at `*dst` can |
3013 | /// [violate memory safety][read-ownership]. |
3014 | /// |
3015 | /// Note that even if the effectively copied size (`count * size_of::<T>()`) is |
3016 | /// `0`, the pointers must be non-null and properly aligned. |
3017 | /// |
3018 | /// [`read`]: crate::ptr::read |
3019 | /// [read-ownership]: crate::ptr::read#ownership-of-the-returned-value |
3020 | /// [valid]: crate::ptr#safety |
3021 | /// |
3022 | /// # Examples |
3023 | /// |
3024 | /// Efficiently create a Rust vector from an unsafe buffer: |
3025 | /// |
3026 | /// ``` |
3027 | /// use std::ptr; |
3028 | /// |
3029 | /// /// # Safety |
3030 | /// /// |
3031 | /// /// * `ptr` must be correctly aligned for its type and non-zero. |
3032 | /// /// * `ptr` must be valid for reads of `elts` contiguous elements of type `T`. |
3033 | /// /// * Those elements must not be used after calling this function unless `T: Copy`. |
3034 | /// # #[allow (dead_code)] |
3035 | /// unsafe fn from_buf_raw<T>(ptr: *const T, elts: usize) -> Vec<T> { |
3036 | /// let mut dst = Vec::with_capacity(elts); |
3037 | /// |
3038 | /// // SAFETY: Our precondition ensures the source is aligned and valid, |
3039 | /// // and `Vec::with_capacity` ensures that we have usable space to write them. |
3040 | /// ptr::copy(ptr, dst.as_mut_ptr(), elts); |
3041 | /// |
3042 | /// // SAFETY: We created it with this much capacity earlier, |
3043 | /// // and the previous `copy` has initialized these elements. |
3044 | /// dst.set_len(elts); |
3045 | /// dst |
3046 | /// } |
3047 | /// ``` |
3048 | #[doc (alias = "memmove" )] |
3049 | #[stable (feature = "rust1" , since = "1.0.0" )] |
3050 | #[rustc_allowed_through_unstable_modules ] |
3051 | #[rustc_const_unstable (feature = "const_intrinsic_copy" , issue = "80697" )] |
3052 | #[inline (always)] |
3053 | #[cfg_attr (miri, track_caller)] // even without panics, this helps for Miri backtraces |
3054 | #[rustc_diagnostic_item = "ptr_copy" ] |
3055 | pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) { |
3056 | extern "rust-intrinsic" { |
3057 | #[rustc_const_unstable (feature = "const_intrinsic_copy" , issue = "80697" )] |
3058 | #[rustc_nounwind ] |
3059 | fn copy<T>(src: *const T, dst: *mut T, count: usize); |
3060 | } |
3061 | |
3062 | // SAFETY: the safety contract for `copy` must be upheld by the caller. |
3063 | unsafe { |
3064 | ub_checks::assert_unsafe_precondition!( |
3065 | check_language_ub, |
3066 | "ptr::copy_nonoverlapping requires that both pointer arguments are aligned and non-null \ |
3067 | and the specified memory ranges do not overlap" , |
3068 | ( |
3069 | src: *const () = src as *const (), |
3070 | dst: *mut () = dst as *mut (), |
3071 | align: usize = align_of::<T>(), |
3072 | ) => |
3073 | ub_checks::is_aligned_and_not_null(src, align) |
3074 | && ub_checks::is_aligned_and_not_null(dst, align) |
3075 | ); |
3076 | copy(src, dst, count) |
3077 | } |
3078 | } |
3079 | |
3080 | /// Sets `count * size_of::<T>()` bytes of memory starting at `dst` to |
3081 | /// `val`. |
3082 | /// |
3083 | /// `write_bytes` is similar to C's [`memset`], but sets `count * |
3084 | /// size_of::<T>()` bytes to `val`. |
3085 | /// |
3086 | /// [`memset`]: https://en.cppreference.com/w/c/string/byte/memset |
3087 | /// |
3088 | /// # Safety |
3089 | /// |
3090 | /// Behavior is undefined if any of the following conditions are violated: |
3091 | /// |
3092 | /// * `dst` must be [valid] for writes of `count * size_of::<T>()` bytes. |
3093 | /// |
3094 | /// * `dst` must be properly aligned. |
3095 | /// |
3096 | /// Note that even if the effectively copied size (`count * size_of::<T>()`) is |
3097 | /// `0`, the pointer must be non-null and properly aligned. |
3098 | /// |
3099 | /// Additionally, note that changing `*dst` in this way can easily lead to undefined behavior (UB) |
3100 | /// later if the written bytes are not a valid representation of some `T`. For instance, the |
3101 | /// following is an **incorrect** use of this function: |
3102 | /// |
3103 | /// ```rust,no_run |
3104 | /// unsafe { |
3105 | /// let mut value: u8 = 0; |
3106 | /// let ptr: *mut bool = &mut value as *mut u8 as *mut bool; |
3107 | /// let _bool = ptr.read(); // This is fine, `ptr` points to a valid `bool`. |
3108 | /// ptr.write_bytes(42u8, 1); // This function itself does not cause UB... |
3109 | /// let _bool = ptr.read(); // ...but it makes this operation UB! ⚠️ |
3110 | /// } |
3111 | /// ``` |
3112 | /// |
3113 | /// [valid]: crate::ptr#safety |
3114 | /// |
3115 | /// # Examples |
3116 | /// |
3117 | /// Basic usage: |
3118 | /// |
3119 | /// ``` |
3120 | /// use std::ptr; |
3121 | /// |
3122 | /// let mut vec = vec![0u32; 4]; |
3123 | /// unsafe { |
3124 | /// let vec_ptr = vec.as_mut_ptr(); |
3125 | /// ptr::write_bytes(vec_ptr, 0xfe, 2); |
3126 | /// } |
3127 | /// assert_eq!(vec, [0xfefefefe, 0xfefefefe, 0, 0]); |
3128 | /// ``` |
3129 | #[doc (alias = "memset" )] |
3130 | #[stable (feature = "rust1" , since = "1.0.0" )] |
3131 | #[rustc_allowed_through_unstable_modules ] |
3132 | #[rustc_const_unstable (feature = "const_ptr_write" , issue = "86302" )] |
3133 | #[inline (always)] |
3134 | #[cfg_attr (miri, track_caller)] // even without panics, this helps for Miri backtraces |
3135 | #[rustc_diagnostic_item = "ptr_write_bytes" ] |
3136 | pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) { |
3137 | extern "rust-intrinsic" { |
3138 | #[rustc_const_unstable (feature = "const_ptr_write" , issue = "86302" )] |
3139 | #[rustc_nounwind ] |
3140 | fn write_bytes<T>(dst: *mut T, val: u8, count: usize); |
3141 | } |
3142 | |
3143 | // SAFETY: the safety contract for `write_bytes` must be upheld by the caller. |
3144 | unsafe { |
3145 | ub_checks::assert_unsafe_precondition!( |
3146 | check_language_ub, |
3147 | "ptr::write_bytes requires that the destination pointer is aligned and non-null" , |
3148 | ( |
3149 | addr: *const () = dst as *const (), |
3150 | align: usize = align_of::<T>(), |
3151 | ) => ub_checks::is_aligned_and_not_null(addr, align) |
3152 | ); |
3153 | write_bytes(dst, val, count) |
3154 | } |
3155 | } |
3156 | |
3157 | /// Inform Miri that a given pointer definitely has a certain alignment. |
3158 | #[cfg (miri)] |
3159 | pub(crate) const fn miri_promise_symbolic_alignment(ptr: *const (), align: usize) { |
3160 | extern "Rust" { |
3161 | /// Miri-provided extern function to promise that a given pointer is properly aligned for |
3162 | /// "symbolic" alignment checks. Will fail if the pointer is not actually aligned or `align` is |
3163 | /// not a power of two. Has no effect when alignment checks are concrete (which is the default). |
3164 | fn miri_promise_symbolic_alignment(ptr: *const (), align: usize); |
3165 | } |
3166 | |
3167 | fn runtime(ptr: *const (), align: usize) { |
3168 | // SAFETY: this call is always safe. |
3169 | unsafe { |
3170 | miri_promise_symbolic_alignment(ptr, align); |
3171 | } |
3172 | } |
3173 | |
3174 | const fn compiletime(_ptr: *const (), _align: usize) {} |
3175 | |
3176 | const_eval_select((ptr, align), _called_in_const:compiletime, _called_at_rt:runtime); |
3177 | } |
3178 | |