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9fa01778 XL |
1 | use crate::borrow_check::ArtificialField; |
2 | use crate::borrow_check::Overlap; | |
dfeec247 | 3 | use crate::borrow_check::{AccessDepth, Deep, Shallow}; |
dfeec247 | 4 | use rustc_hir as hir; |
ba9703b0 XL |
5 | use rustc_middle::mir::{Body, BorrowKind, Local, Place, PlaceElem, PlaceRef, ProjectionElem}; |
6 | use rustc_middle::ty::{self, TyCtxt}; | |
8faf50e0 XL |
7 | use std::cmp::max; |
8 | ||
0731742a XL |
9 | /// When checking if a place conflicts with another place, this enum is used to influence decisions |
10 | /// where a place might be equal or disjoint with another place, such as if `a[i] == a[j]`. | |
11 | /// `PlaceConflictBias::Overlap` would bias toward assuming that `i` might equal `j` and that these | |
12 | /// places overlap. `PlaceConflictBias::NoOverlap` assumes that for the purposes of the predicate | |
13 | /// being run in the calling context, the conservative choice is to assume the compared indices | |
14 | /// are disjoint (and therefore, do not overlap). | |
15 | #[derive(Copy, Clone, Debug, Eq, PartialEq)] | |
16 | crate enum PlaceConflictBias { | |
17 | Overlap, | |
18 | NoOverlap, | |
19 | } | |
20 | ||
21 | /// Helper function for checking if places conflict with a mutable borrow and deep access depth. | |
22 | /// This is used to check for places conflicting outside of the borrow checking code (such as in | |
23 | /// dataflow). | |
dc9dc135 XL |
24 | crate fn places_conflict<'tcx>( |
25 | tcx: TyCtxt<'tcx>, | |
26 | body: &Body<'tcx>, | |
ba9703b0 XL |
27 | borrow_place: Place<'tcx>, |
28 | access_place: Place<'tcx>, | |
0731742a XL |
29 | bias: PlaceConflictBias, |
30 | ) -> bool { | |
31 | borrow_conflicts_with_place( | |
32 | tcx, | |
dc9dc135 | 33 | body, |
0731742a XL |
34 | borrow_place, |
35 | BorrowKind::Mut { allow_two_phase_borrow: true }, | |
416331ca | 36 | access_place.as_ref(), |
0731742a XL |
37 | AccessDepth::Deep, |
38 | bias, | |
39 | ) | |
40 | } | |
41 | ||
42 | /// Checks whether the `borrow_place` conflicts with the `access_place` given a borrow kind and | |
43 | /// access depth. The `bias` parameter is used to determine how the unknowable (comparing runtime | |
44 | /// array indices, for example) should be interpreted - this depends on what the caller wants in | |
45 | /// order to make the conservative choice and preserve soundness. | |
dc9dc135 XL |
46 | pub(super) fn borrow_conflicts_with_place<'tcx>( |
47 | tcx: TyCtxt<'tcx>, | |
48 | body: &Body<'tcx>, | |
ba9703b0 | 49 | borrow_place: Place<'tcx>, |
0bf4aa26 | 50 | borrow_kind: BorrowKind, |
74b04a01 | 51 | access_place: PlaceRef<'tcx>, |
0bf4aa26 | 52 | access: AccessDepth, |
0731742a | 53 | bias: PlaceConflictBias, |
8faf50e0 XL |
54 | ) -> bool { |
55 | debug!( | |
0731742a XL |
56 | "borrow_conflicts_with_place({:?}, {:?}, {:?}, {:?})", |
57 | borrow_place, access_place, access, bias, | |
8faf50e0 XL |
58 | ); |
59 | ||
b7449926 XL |
60 | // This Local/Local case is handled by the more general code below, but |
61 | // it's so common that it's a speed win to check for it first. | |
e74abb32 XL |
62 | if let Some(l1) = borrow_place.as_local() { |
63 | if let Some(l2) = access_place.as_local() { | |
b7449926 XL |
64 | return l1 == l2; |
65 | } | |
66 | } | |
67 | ||
dfeec247 | 68 | place_components_conflict(tcx, body, borrow_place, borrow_kind, access_place, access, bias) |
8faf50e0 XL |
69 | } |
70 | ||
dc9dc135 XL |
71 | fn place_components_conflict<'tcx>( |
72 | tcx: TyCtxt<'tcx>, | |
73 | body: &Body<'tcx>, | |
ba9703b0 | 74 | borrow_place: Place<'tcx>, |
0bf4aa26 | 75 | borrow_kind: BorrowKind, |
74b04a01 | 76 | access_place: PlaceRef<'tcx>, |
0bf4aa26 | 77 | access: AccessDepth, |
0731742a | 78 | bias: PlaceConflictBias, |
8faf50e0 XL |
79 | ) -> bool { |
80 | // The borrowck rules for proving disjointness are applied from the "root" of the | |
81 | // borrow forwards, iterating over "similar" projections in lockstep until | |
82 | // we can prove overlap one way or another. Essentially, we treat `Overlap` as | |
83 | // a monoid and report a conflict if the product ends up not being `Disjoint`. | |
84 | // | |
85 | // At each step, if we didn't run out of borrow or place, we know that our elements | |
86 | // have the same type, and that they only overlap if they are the identical. | |
87 | // | |
88 | // For example, if we are comparing these: | |
89 | // BORROW: (*x1[2].y).z.a | |
90 | // ACCESS: (*x1[i].y).w.b | |
91 | // | |
92 | // Then our steps are: | |
93 | // x1 | x1 -- places are the same | |
94 | // x1[2] | x1[i] -- equal or disjoint (disjoint if indexes differ) | |
95 | // x1[2].y | x1[i].y -- equal or disjoint | |
96 | // *x1[2].y | *x1[i].y -- equal or disjoint | |
97 | // (*x1[2].y).z | (*x1[i].y).w -- we are disjoint and don't need to check more! | |
98 | // | |
99 | // Because `zip` does potentially bad things to the iterator inside, this loop | |
100 | // also handles the case where the access might be a *prefix* of the borrow, e.g. | |
101 | // | |
102 | // BORROW: (*x1[2].y).z.a | |
103 | // ACCESS: x1[i].y | |
104 | // | |
105 | // Then our steps are: | |
106 | // x1 | x1 -- places are the same | |
107 | // x1[2] | x1[i] -- equal or disjoint (disjoint if indexes differ) | |
108 | // x1[2].y | x1[i].y -- equal or disjoint | |
109 | // | |
110 | // -- here we run out of access - the borrow can access a part of it. If this | |
111 | // is a full deep access, then we *know* the borrow conflicts with it. However, | |
112 | // if the access is shallow, then we can proceed: | |
113 | // | |
114 | // x1[2].y | (*x1[i].y) -- a deref! the access can't get past this, so we | |
115 | // are disjoint | |
116 | // | |
117 | // Our invariant is, that at each step of the iteration: | |
118 | // - If we didn't run out of access to match, our borrow and access are comparable | |
119 | // and either equal or disjoint. | |
b7449926 | 120 | // - If we did run out of access, the borrow can access a part of it. |
48663c56 | 121 | |
74b04a01 | 122 | let borrow_local = borrow_place.local; |
dfeec247 | 123 | let access_local = access_place.local; |
48663c56 | 124 | |
dfeec247 | 125 | match place_base_conflict(borrow_local, access_local) { |
48663c56 XL |
126 | Overlap::Arbitrary => { |
127 | bug!("Two base can't return Arbitrary"); | |
128 | } | |
129 | Overlap::EqualOrDisjoint => { | |
130 | // This is the recursive case - proceed to the next element. | |
131 | } | |
132 | Overlap::Disjoint => { | |
133 | // We have proven the borrow disjoint - further | |
134 | // projections will remain disjoint. | |
135 | debug!("borrow_conflicts_with_place: disjoint"); | |
136 | return false; | |
137 | } | |
138 | } | |
139 | ||
e1599b0c | 140 | // loop invariant: borrow_c is always either equal to access_c or disjoint from it. |
f9f354fc | 141 | for (i, (borrow_c, &access_c)) in |
e1599b0c XL |
142 | borrow_place.projection.iter().zip(access_place.projection.iter()).enumerate() |
143 | { | |
144 | debug!("borrow_conflicts_with_place: borrow_c = {:?}", borrow_c); | |
145 | let borrow_proj_base = &borrow_place.projection[..i]; | |
8faf50e0 | 146 | |
e1599b0c | 147 | debug!("borrow_conflicts_with_place: access_c = {:?}", access_c); |
8faf50e0 | 148 | |
e1599b0c XL |
149 | // Borrow and access path both have more components. |
150 | // | |
151 | // Examples: | |
152 | // | |
153 | // - borrow of `a.(...)`, access to `a.(...)` | |
154 | // - borrow of `a.(...)`, access to `b.(...)` | |
155 | // | |
156 | // Here we only see the components we have checked so | |
157 | // far (in our examples, just the first component). We | |
158 | // check whether the components being borrowed vs | |
159 | // accessed are disjoint (as in the second example, | |
160 | // but not the first). | |
161 | match place_projection_conflict( | |
162 | tcx, | |
163 | body, | |
dfeec247 | 164 | borrow_local, |
e1599b0c XL |
165 | borrow_proj_base, |
166 | borrow_c, | |
167 | access_c, | |
168 | bias, | |
169 | ) { | |
170 | Overlap::Arbitrary => { | |
171 | // We have encountered different fields of potentially | |
172 | // the same union - the borrow now partially overlaps. | |
8faf50e0 | 173 | // |
e1599b0c XL |
174 | // There is no *easy* way of comparing the fields |
175 | // further on, because they might have different types | |
176 | // (e.g., borrows of `u.a.0` and `u.b.y` where `.0` and | |
177 | // `.y` come from different structs). | |
8faf50e0 | 178 | // |
e1599b0c XL |
179 | // We could try to do some things here - e.g., count |
180 | // dereferences - but that's probably not a good | |
181 | // idea, at least for now, so just give up and | |
182 | // report a conflict. This is unsafe code anyway so | |
183 | // the user could always use raw pointers. | |
184 | debug!("borrow_conflicts_with_place: arbitrary -> conflict"); | |
185 | return true; | |
186 | } | |
187 | Overlap::EqualOrDisjoint => { | |
188 | // This is the recursive case - proceed to the next element. | |
189 | } | |
190 | Overlap::Disjoint => { | |
191 | // We have proven the borrow disjoint - further | |
192 | // projections will remain disjoint. | |
193 | debug!("borrow_conflicts_with_place: disjoint"); | |
194 | return false; | |
195 | } | |
196 | } | |
197 | } | |
198 | ||
199 | if borrow_place.projection.len() > access_place.projection.len() { | |
200 | for (i, elem) in borrow_place.projection[access_place.projection.len()..].iter().enumerate() | |
201 | { | |
202 | // Borrow path is longer than the access path. Examples: | |
203 | // | |
204 | // - borrow of `a.b.c`, access to `a.b` | |
205 | // | |
206 | // Here, we know that the borrow can access a part of | |
207 | // our place. This is a conflict if that is a part our | |
208 | // access cares about. | |
8faf50e0 | 209 | |
e1599b0c | 210 | let proj_base = &borrow_place.projection[..access_place.projection.len() + i]; |
dfeec247 | 211 | let base_ty = Place::ty_from(borrow_local, proj_base, body, tcx).ty; |
8faf50e0 | 212 | |
e74abb32 | 213 | match (elem, &base_ty.kind, access) { |
e1599b0c XL |
214 | (_, _, Shallow(Some(ArtificialField::ArrayLength))) |
215 | | (_, _, Shallow(Some(ArtificialField::ShallowBorrow))) => { | |
216 | // The array length is like additional fields on the | |
217 | // type; it does not overlap any existing data there. | |
218 | // Furthermore, if cannot actually be a prefix of any | |
219 | // borrowed place (at least in MIR as it is currently.) | |
220 | // | |
221 | // e.g., a (mutable) borrow of `a[5]` while we read the | |
222 | // array length of `a`. | |
223 | debug!("borrow_conflicts_with_place: implicit field"); | |
224 | return false; | |
225 | } | |
8faf50e0 | 226 | |
e1599b0c XL |
227 | (ProjectionElem::Deref, _, Shallow(None)) => { |
228 | // e.g., a borrow of `*x.y` while we shallowly access `x.y` or some | |
229 | // prefix thereof - the shallow access can't touch anything behind | |
230 | // the pointer. | |
231 | debug!("borrow_conflicts_with_place: shallow access behind ptr"); | |
232 | return false; | |
233 | } | |
dfeec247 | 234 | (ProjectionElem::Deref, ty::Ref(_, _, hir::Mutability::Not), _) => { |
e1599b0c XL |
235 | // Shouldn't be tracked |
236 | bug!("Tracking borrow behind shared reference."); | |
237 | } | |
dfeec247 | 238 | (ProjectionElem::Deref, ty::Ref(_, _, hir::Mutability::Mut), AccessDepth::Drop) => { |
e1599b0c XL |
239 | // Values behind a mutable reference are not access either by dropping a |
240 | // value, or by StorageDead | |
241 | debug!("borrow_conflicts_with_place: drop access behind ptr"); | |
242 | return false; | |
243 | } | |
8faf50e0 | 244 | |
e1599b0c XL |
245 | (ProjectionElem::Field { .. }, ty::Adt(def, _), AccessDepth::Drop) => { |
246 | // Drop can read/write arbitrary projections, so places | |
247 | // conflict regardless of further projections. | |
248 | if def.has_dtor(tcx) { | |
249 | return true; | |
0bf4aa26 | 250 | } |
e1599b0c | 251 | } |
0bf4aa26 | 252 | |
e1599b0c XL |
253 | (ProjectionElem::Deref, _, Deep) |
254 | | (ProjectionElem::Deref, _, AccessDepth::Drop) | |
255 | | (ProjectionElem::Field { .. }, _, _) | |
256 | | (ProjectionElem::Index { .. }, _, _) | |
257 | | (ProjectionElem::ConstantIndex { .. }, _, _) | |
258 | | (ProjectionElem::Subslice { .. }, _, _) | |
259 | | (ProjectionElem::Downcast { .. }, _, _) => { | |
260 | // Recursive case. This can still be disjoint on a | |
261 | // further iteration if this a shallow access and | |
262 | // there's a deref later on, e.g., a borrow | |
263 | // of `*x.y` while accessing `x`. | |
8faf50e0 XL |
264 | } |
265 | } | |
8faf50e0 XL |
266 | } |
267 | } | |
e1599b0c XL |
268 | |
269 | // Borrow path ran out but access path may not | |
270 | // have. Examples: | |
271 | // | |
272 | // - borrow of `a.b`, access to `a.b.c` | |
273 | // - borrow of `a.b`, access to `a.b` | |
274 | // | |
275 | // In the first example, where we didn't run out of | |
276 | // access, the borrow can access all of our place, so we | |
277 | // have a conflict. | |
278 | // | |
279 | // If the second example, where we did, then we still know | |
280 | // that the borrow can access a *part* of our place that | |
281 | // our access cares about, so we still have a conflict. | |
282 | if borrow_kind == BorrowKind::Shallow | |
283 | && borrow_place.projection.len() < access_place.projection.len() | |
284 | { | |
285 | debug!("borrow_conflicts_with_place: shallow borrow"); | |
286 | false | |
287 | } else { | |
288 | debug!("borrow_conflicts_with_place: full borrow, CONFLICT"); | |
289 | true | |
290 | } | |
8faf50e0 XL |
291 | } |
292 | ||
8faf50e0 XL |
293 | // Given that the bases of `elem1` and `elem2` are always either equal |
294 | // or disjoint (and have the same type!), return the overlap situation | |
295 | // between `elem1` and `elem2`. | |
74b04a01 | 296 | fn place_base_conflict(l1: Local, l2: Local) -> Overlap { |
dfeec247 XL |
297 | if l1 == l2 { |
298 | // the same local - base case, equal | |
299 | debug!("place_element_conflict: DISJOINT-OR-EQ-LOCAL"); | |
300 | Overlap::EqualOrDisjoint | |
301 | } else { | |
302 | // different locals - base case, disjoint | |
303 | debug!("place_element_conflict: DISJOINT-LOCAL"); | |
304 | Overlap::Disjoint | |
48663c56 XL |
305 | } |
306 | } | |
307 | ||
308 | // Given that the bases of `elem1` and `elem2` are always either equal | |
309 | // or disjoint (and have the same type!), return the overlap situation | |
310 | // between `elem1` and `elem2`. | |
dc9dc135 XL |
311 | fn place_projection_conflict<'tcx>( |
312 | tcx: TyCtxt<'tcx>, | |
313 | body: &Body<'tcx>, | |
74b04a01 | 314 | pi1_local: Local, |
e1599b0c | 315 | pi1_proj_base: &[PlaceElem<'tcx>], |
f9f354fc XL |
316 | pi1_elem: PlaceElem<'tcx>, |
317 | pi2_elem: PlaceElem<'tcx>, | |
48663c56 XL |
318 | bias: PlaceConflictBias, |
319 | ) -> Overlap { | |
e1599b0c | 320 | match (pi1_elem, pi2_elem) { |
48663c56 XL |
321 | (ProjectionElem::Deref, ProjectionElem::Deref) => { |
322 | // derefs (e.g., `*x` vs. `*x`) - recur. | |
323 | debug!("place_element_conflict: DISJOINT-OR-EQ-DEREF"); | |
324 | Overlap::EqualOrDisjoint | |
325 | } | |
326 | (ProjectionElem::Field(f1, _), ProjectionElem::Field(f2, _)) => { | |
327 | if f1 == f2 { | |
328 | // same field (e.g., `a.y` vs. `a.y`) - recur. | |
329 | debug!("place_element_conflict: DISJOINT-OR-EQ-FIELD"); | |
330 | Overlap::EqualOrDisjoint | |
331 | } else { | |
dfeec247 | 332 | let ty = Place::ty_from(pi1_local, pi1_proj_base, body, tcx).ty; |
e74abb32 | 333 | match ty.kind { |
48663c56 XL |
334 | ty::Adt(def, _) if def.is_union() => { |
335 | // Different fields of a union, we are basically stuck. | |
336 | debug!("place_element_conflict: STUCK-UNION"); | |
337 | Overlap::Arbitrary | |
8faf50e0 | 338 | } |
48663c56 XL |
339 | _ => { |
340 | // Different fields of a struct (`a.x` vs. `a.y`). Disjoint! | |
8faf50e0 XL |
341 | debug!("place_element_conflict: DISJOINT-FIELD"); |
342 | Overlap::Disjoint | |
343 | } | |
344 | } | |
48663c56 XL |
345 | } |
346 | } | |
347 | (ProjectionElem::Downcast(_, v1), ProjectionElem::Downcast(_, v2)) => { | |
348 | // different variants are treated as having disjoint fields, | |
349 | // even if they occupy the same "space", because it's | |
350 | // impossible for 2 variants of the same enum to exist | |
351 | // (and therefore, to be borrowed) at the same time. | |
352 | // | |
353 | // Note that this is different from unions - we *do* allow | |
354 | // this code to compile: | |
355 | // | |
356 | // ``` | |
357 | // fn foo(x: &mut Result<i32, i32>) { | |
358 | // let mut v = None; | |
359 | // if let Ok(ref mut a) = *x { | |
360 | // v = Some(a); | |
361 | // } | |
362 | // // here, you would *think* that the | |
363 | // // *entirety* of `x` would be borrowed, | |
364 | // // but in fact only the `Ok` variant is, | |
365 | // // so the `Err` variant is *entirely free*: | |
366 | // if let Err(ref mut a) = *x { | |
367 | // v = Some(a); | |
368 | // } | |
369 | // drop(v); | |
370 | // } | |
371 | // ``` | |
372 | if v1 == v2 { | |
373 | debug!("place_element_conflict: DISJOINT-OR-EQ-FIELD"); | |
374 | Overlap::EqualOrDisjoint | |
375 | } else { | |
376 | debug!("place_element_conflict: DISJOINT-FIELD"); | |
377 | Overlap::Disjoint | |
378 | } | |
379 | } | |
ba9703b0 XL |
380 | ( |
381 | ProjectionElem::Index(..), | |
382 | ProjectionElem::Index(..) | |
383 | | ProjectionElem::ConstantIndex { .. } | |
384 | | ProjectionElem::Subslice { .. }, | |
385 | ) | |
386 | | ( | |
387 | ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. }, | |
388 | ProjectionElem::Index(..), | |
389 | ) => { | |
48663c56 XL |
390 | // Array indexes (`a[0]` vs. `a[i]`). These can either be disjoint |
391 | // (if the indexes differ) or equal (if they are the same). | |
392 | match bias { | |
393 | PlaceConflictBias::Overlap => { | |
394 | // If we are biased towards overlapping, then this is the recursive | |
395 | // case that gives "equal *or* disjoint" its meaning. | |
396 | debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-INDEX"); | |
397 | Overlap::EqualOrDisjoint | |
8faf50e0 | 398 | } |
48663c56 XL |
399 | PlaceConflictBias::NoOverlap => { |
400 | // If we are biased towards no overlapping, then this is disjoint. | |
401 | debug!("place_element_conflict: DISJOINT-ARRAY-INDEX"); | |
402 | Overlap::Disjoint | |
8faf50e0 | 403 | } |
8faf50e0 XL |
404 | } |
405 | } | |
dfeec247 XL |
406 | ( |
407 | ProjectionElem::ConstantIndex { offset: o1, min_length: _, from_end: false }, | |
408 | ProjectionElem::ConstantIndex { offset: o2, min_length: _, from_end: false }, | |
409 | ) | |
410 | | ( | |
411 | ProjectionElem::ConstantIndex { offset: o1, min_length: _, from_end: true }, | |
412 | ProjectionElem::ConstantIndex { offset: o2, min_length: _, from_end: true }, | |
413 | ) => { | |
48663c56 XL |
414 | if o1 == o2 { |
415 | debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX"); | |
416 | Overlap::EqualOrDisjoint | |
417 | } else { | |
418 | debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX"); | |
419 | Overlap::Disjoint | |
420 | } | |
421 | } | |
dfeec247 | 422 | ( |
48663c56 | 423 | ProjectionElem::ConstantIndex { |
dfeec247 XL |
424 | offset: offset_from_begin, |
425 | min_length: min_length1, | |
426 | from_end: false, | |
427 | }, | |
428 | ProjectionElem::ConstantIndex { | |
429 | offset: offset_from_end, | |
430 | min_length: min_length2, | |
431 | from_end: true, | |
432 | }, | |
433 | ) | |
434 | | ( | |
435 | ProjectionElem::ConstantIndex { | |
436 | offset: offset_from_end, | |
437 | min_length: min_length1, | |
438 | from_end: true, | |
439 | }, | |
440 | ProjectionElem::ConstantIndex { | |
441 | offset: offset_from_begin, | |
442 | min_length: min_length2, | |
443 | from_end: false, | |
444 | }, | |
445 | ) => { | |
48663c56 XL |
446 | // both patterns matched so it must be at least the greater of the two |
447 | let min_length = max(min_length1, min_length2); | |
448 | // `offset_from_end` can be in range `[1..min_length]`, 1 indicates the last | |
449 | // element (like -1 in Python) and `min_length` the first. | |
450 | // Therefore, `min_length - offset_from_end` gives the minimal possible | |
451 | // offset from the beginning | |
f9f354fc | 452 | if offset_from_begin >= min_length - offset_from_end { |
48663c56 XL |
453 | debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX-FE"); |
454 | Overlap::EqualOrDisjoint | |
455 | } else { | |
456 | debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX-FE"); | |
457 | Overlap::Disjoint | |
458 | } | |
459 | } | |
60c5eb7d XL |
460 | ( |
461 | ProjectionElem::ConstantIndex { offset, min_length: _, from_end: false }, | |
dfeec247 | 462 | ProjectionElem::Subslice { from, to, from_end: false }, |
60c5eb7d XL |
463 | ) |
464 | | ( | |
465 | ProjectionElem::Subslice { from, to, from_end: false }, | |
dfeec247 | 466 | ProjectionElem::ConstantIndex { offset, min_length: _, from_end: false }, |
60c5eb7d XL |
467 | ) => { |
468 | if (from..to).contains(&offset) { | |
469 | debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX-SUBSLICE"); | |
470 | Overlap::EqualOrDisjoint | |
471 | } else { | |
472 | debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX-SUBSLICE"); | |
473 | Overlap::Disjoint | |
474 | } | |
475 | } | |
dfeec247 XL |
476 | ( |
477 | ProjectionElem::ConstantIndex { offset, min_length: _, from_end: false }, | |
478 | ProjectionElem::Subslice { from, .. }, | |
479 | ) | |
480 | | ( | |
481 | ProjectionElem::Subslice { from, .. }, | |
482 | ProjectionElem::ConstantIndex { offset, min_length: _, from_end: false }, | |
483 | ) => { | |
48663c56 | 484 | if offset >= from { |
dfeec247 | 485 | debug!("place_element_conflict: DISJOINT-OR-EQ-SLICE-CONSTANT-INDEX-SUBSLICE"); |
48663c56 XL |
486 | Overlap::EqualOrDisjoint |
487 | } else { | |
60c5eb7d | 488 | debug!("place_element_conflict: DISJOINT-SLICE-CONSTANT-INDEX-SUBSLICE"); |
48663c56 XL |
489 | Overlap::Disjoint |
490 | } | |
491 | } | |
dfeec247 XL |
492 | ( |
493 | ProjectionElem::ConstantIndex { offset, min_length: _, from_end: true }, | |
494 | ProjectionElem::Subslice { to, from_end: true, .. }, | |
495 | ) | |
496 | | ( | |
497 | ProjectionElem::Subslice { to, from_end: true, .. }, | |
498 | ProjectionElem::ConstantIndex { offset, min_length: _, from_end: true }, | |
499 | ) => { | |
48663c56 | 500 | if offset > to { |
dfeec247 XL |
501 | debug!( |
502 | "place_element_conflict: \ | |
503 | DISJOINT-OR-EQ-SLICE-CONSTANT-INDEX-SUBSLICE-FE" | |
504 | ); | |
48663c56 XL |
505 | Overlap::EqualOrDisjoint |
506 | } else { | |
60c5eb7d XL |
507 | debug!("place_element_conflict: DISJOINT-SLICE-CONSTANT-INDEX-SUBSLICE-FE"); |
508 | Overlap::Disjoint | |
509 | } | |
510 | } | |
511 | ( | |
512 | ProjectionElem::Subslice { from: f1, to: t1, from_end: false }, | |
dfeec247 | 513 | ProjectionElem::Subslice { from: f2, to: t2, from_end: false }, |
60c5eb7d XL |
514 | ) => { |
515 | if f2 >= t1 || f1 >= t2 { | |
516 | debug!("place_element_conflict: DISJOINT-ARRAY-SUBSLICES"); | |
48663c56 | 517 | Overlap::Disjoint |
60c5eb7d XL |
518 | } else { |
519 | debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-SUBSLICES"); | |
520 | Overlap::EqualOrDisjoint | |
48663c56 XL |
521 | } |
522 | } | |
523 | (ProjectionElem::Subslice { .. }, ProjectionElem::Subslice { .. }) => { | |
60c5eb7d | 524 | debug!("place_element_conflict: DISJOINT-OR-EQ-SLICE-SUBSLICES"); |
dfeec247 | 525 | Overlap::EqualOrDisjoint |
48663c56 | 526 | } |
ba9703b0 XL |
527 | ( |
528 | ProjectionElem::Deref | |
529 | | ProjectionElem::Field(..) | |
530 | | ProjectionElem::Index(..) | |
531 | | ProjectionElem::ConstantIndex { .. } | |
532 | | ProjectionElem::Subslice { .. } | |
533 | | ProjectionElem::Downcast(..), | |
534 | _, | |
535 | ) => bug!( | |
48663c56 | 536 | "mismatched projections in place_element_conflict: {:?} and {:?}", |
e1599b0c XL |
537 | pi1_elem, |
538 | pi2_elem | |
8faf50e0 XL |
539 | ), |
540 | } | |
541 | } |