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1 | // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
11 | //! Data structures used for tracking moves. Please see the extensive | |
c34b1796 | 12 | //! comments in the section "Moves and initialization" in `README.md`. |
1a4d82fc JJ |
13 | |
14 | pub use self::MoveKind::*; | |
15 | ||
16 | use borrowck::*; | |
54a0048b | 17 | use rustc::cfg; |
1a4d82fc JJ |
18 | use rustc::middle::dataflow::DataFlowContext; |
19 | use rustc::middle::dataflow::BitwiseOperator; | |
20 | use rustc::middle::dataflow::DataFlowOperator; | |
9346a6ac | 21 | use rustc::middle::dataflow::KillFrom; |
1a4d82fc | 22 | use rustc::middle::expr_use_visitor as euv; |
9cc50fc6 | 23 | use rustc::middle::expr_use_visitor::MutateMode; |
9e0c209e SL |
24 | use rustc::middle::mem_categorization as mc; |
25 | use rustc::ty::{self, TyCtxt}; | |
ea8adc8c | 26 | use rustc::util::nodemap::{FxHashMap, FxHashSet}; |
62682a34 | 27 | |
1a4d82fc JJ |
28 | use std::cell::RefCell; |
29 | use std::rc::Rc; | |
85aaf69f | 30 | use std::usize; |
3157f602 | 31 | use syntax_pos::Span; |
54a0048b SL |
32 | use rustc::hir; |
33 | use rustc::hir::intravisit::IdRange; | |
1a4d82fc | 34 | |
ea8adc8c | 35 | #[derive(Default)] |
1a4d82fc | 36 | pub struct MoveData<'tcx> { |
c34b1796 | 37 | /// Move paths. See section "Move paths" in `README.md`. |
1a4d82fc JJ |
38 | pub paths: RefCell<Vec<MovePath<'tcx>>>, |
39 | ||
40 | /// Cache of loan path to move path index, for easy lookup. | |
476ff2be | 41 | pub path_map: RefCell<FxHashMap<Rc<LoanPath<'tcx>>, MovePathIndex>>, |
1a4d82fc JJ |
42 | |
43 | /// Each move or uninitialized variable gets an entry here. | |
44 | pub moves: RefCell<Vec<Move>>, | |
45 | ||
46 | /// Assignments to a variable, like `x = foo`. These are assigned | |
47 | /// bits for dataflow, since we must track them to ensure that | |
48 | /// immutable variables are assigned at most once along each path. | |
49 | pub var_assignments: RefCell<Vec<Assignment>>, | |
50 | ||
51 | /// Assignments to a path, like `x.f = foo`. These are not | |
52 | /// assigned dataflow bits, but we track them because they still | |
53 | /// kill move bits. | |
54 | pub path_assignments: RefCell<Vec<Assignment>>, | |
55 | ||
1a4d82fc | 56 | /// Assignments to a variable or path, like `x = foo`, but not `x += foo`. |
ea8adc8c | 57 | pub assignee_ids: RefCell<FxHashSet<hir::ItemLocalId>>, |
1a4d82fc JJ |
58 | } |
59 | ||
60 | pub struct FlowedMoveData<'a, 'tcx: 'a> { | |
61 | pub move_data: MoveData<'tcx>, | |
62 | ||
63 | pub dfcx_moves: MoveDataFlow<'a, 'tcx>, | |
64 | ||
65 | // We could (and maybe should, for efficiency) combine both move | |
66 | // and assign data flow into one, but this way it's easier to | |
67 | // distinguish the bits that correspond to moves and assignments. | |
68 | pub dfcx_assign: AssignDataFlow<'a, 'tcx> | |
69 | } | |
70 | ||
71 | /// Index into `MoveData.paths`, used like a pointer | |
85aaf69f | 72 | #[derive(Copy, PartialEq, Eq, PartialOrd, Ord, Debug)] |
c34b1796 | 73 | pub struct MovePathIndex(usize); |
1a4d82fc JJ |
74 | |
75 | impl MovePathIndex { | |
c34b1796 | 76 | fn get(&self) -> usize { |
1a4d82fc JJ |
77 | let MovePathIndex(v) = *self; v |
78 | } | |
79 | } | |
80 | ||
81 | impl Clone for MovePathIndex { | |
82 | fn clone(&self) -> MovePathIndex { | |
83 | MovePathIndex(self.get()) | |
84 | } | |
85 | } | |
86 | ||
87 | #[allow(non_upper_case_globals)] | |
c34b1796 | 88 | const InvalidMovePathIndex: MovePathIndex = MovePathIndex(usize::MAX); |
1a4d82fc JJ |
89 | |
90 | /// Index into `MoveData.moves`, used like a pointer | |
c34b1796 AL |
91 | #[derive(Copy, Clone, PartialEq)] |
92 | pub struct MoveIndex(usize); | |
1a4d82fc JJ |
93 | |
94 | impl MoveIndex { | |
c34b1796 | 95 | fn get(&self) -> usize { |
1a4d82fc JJ |
96 | let MoveIndex(v) = *self; v |
97 | } | |
98 | } | |
99 | ||
100 | #[allow(non_upper_case_globals)] | |
c34b1796 | 101 | const InvalidMoveIndex: MoveIndex = MoveIndex(usize::MAX); |
1a4d82fc JJ |
102 | |
103 | pub struct MovePath<'tcx> { | |
104 | /// Loan path corresponding to this move path | |
105 | pub loan_path: Rc<LoanPath<'tcx>>, | |
106 | ||
107 | /// Parent pointer, `InvalidMovePathIndex` if root | |
108 | pub parent: MovePathIndex, | |
109 | ||
110 | /// Head of linked list of moves to this path, | |
111 | /// `InvalidMoveIndex` if not moved | |
112 | pub first_move: MoveIndex, | |
113 | ||
114 | /// First node in linked list of children, `InvalidMovePathIndex` if leaf | |
115 | pub first_child: MovePathIndex, | |
116 | ||
117 | /// Next node in linked list of parent's children (siblings), | |
118 | /// `InvalidMovePathIndex` if none. | |
119 | pub next_sibling: MovePathIndex, | |
120 | } | |
121 | ||
c34b1796 | 122 | #[derive(Copy, Clone, PartialEq, Debug)] |
1a4d82fc JJ |
123 | pub enum MoveKind { |
124 | Declared, // When declared, variables start out "moved". | |
125 | MoveExpr, // Expression or binding that moves a variable | |
126 | MovePat, // By-move binding | |
127 | Captured // Closure creation that moves a value | |
128 | } | |
129 | ||
c34b1796 | 130 | #[derive(Copy, Clone)] |
1a4d82fc JJ |
131 | pub struct Move { |
132 | /// Path being moved. | |
133 | pub path: MovePathIndex, | |
134 | ||
135 | /// id of node that is doing the move. | |
ea8adc8c | 136 | pub id: hir::ItemLocalId, |
1a4d82fc JJ |
137 | |
138 | /// Kind of move, for error messages. | |
139 | pub kind: MoveKind, | |
140 | ||
141 | /// Next node in linked list of moves from `path`, or `InvalidMoveIndex` | |
142 | pub next_move: MoveIndex | |
143 | } | |
144 | ||
c34b1796 | 145 | #[derive(Copy, Clone)] |
1a4d82fc JJ |
146 | pub struct Assignment { |
147 | /// Path being assigned. | |
148 | pub path: MovePathIndex, | |
149 | ||
150 | /// id where assignment occurs | |
ea8adc8c | 151 | pub id: hir::ItemLocalId, |
1a4d82fc JJ |
152 | |
153 | /// span of node where assignment occurs | |
154 | pub span: Span, | |
c1a9b12d SL |
155 | |
156 | /// id for l-value expression on lhs of assignment | |
ea8adc8c | 157 | pub assignee_id: hir::ItemLocalId, |
1a4d82fc JJ |
158 | } |
159 | ||
1a4d82fc JJ |
160 | #[derive(Clone, Copy)] |
161 | pub struct MoveDataFlowOperator; | |
162 | ||
163 | pub type MoveDataFlow<'a, 'tcx> = DataFlowContext<'a, 'tcx, MoveDataFlowOperator>; | |
164 | ||
165 | #[derive(Clone, Copy)] | |
166 | pub struct AssignDataFlowOperator; | |
167 | ||
168 | pub type AssignDataFlow<'a, 'tcx> = DataFlowContext<'a, 'tcx, AssignDataFlowOperator>; | |
169 | ||
170 | fn loan_path_is_precise(loan_path: &LoanPath) -> bool { | |
171 | match loan_path.kind { | |
172 | LpVar(_) | LpUpvar(_) => { | |
173 | true | |
174 | } | |
7cac9316 | 175 | LpExtend(.., LpInterior(_, InteriorKind::InteriorElement)) => { |
85aaf69f | 176 | // Paths involving element accesses a[i] do not refer to a unique |
1a4d82fc | 177 | // location, as there is no accurate tracking of the indices. |
85aaf69f SL |
178 | // |
179 | // (Paths involving element accesses via slice pattern bindings | |
180 | // can in principle be tracked precisely, but that is future | |
181 | // work. For now, continue claiming that they are imprecise.) | |
1a4d82fc JJ |
182 | false |
183 | } | |
184 | LpDowncast(ref lp_base, _) | | |
9e0c209e | 185 | LpExtend(ref lp_base, ..) => { |
7453a54e | 186 | loan_path_is_precise(&lp_base) |
1a4d82fc JJ |
187 | } |
188 | } | |
189 | } | |
190 | ||
a7813a04 | 191 | impl<'a, 'tcx> MoveData<'tcx> { |
3b2f2976 XL |
192 | /// return true if there are no trackable assignments or moves |
193 | /// in this move data - that means that there is nothing that | |
194 | /// could cause a borrow error. | |
195 | pub fn is_empty(&self) -> bool { | |
196 | self.moves.borrow().is_empty() && | |
197 | self.path_assignments.borrow().is_empty() && | |
198 | self.var_assignments.borrow().is_empty() | |
199 | } | |
200 | ||
1a4d82fc JJ |
201 | pub fn path_loan_path(&self, index: MovePathIndex) -> Rc<LoanPath<'tcx>> { |
202 | (*self.paths.borrow())[index.get()].loan_path.clone() | |
203 | } | |
204 | ||
205 | fn path_parent(&self, index: MovePathIndex) -> MovePathIndex { | |
206 | (*self.paths.borrow())[index.get()].parent | |
207 | } | |
208 | ||
209 | fn path_first_move(&self, index: MovePathIndex) -> MoveIndex { | |
210 | (*self.paths.borrow())[index.get()].first_move | |
211 | } | |
212 | ||
213 | /// Returns the index of first child, or `InvalidMovePathIndex` if | |
214 | /// `index` is leaf. | |
215 | fn path_first_child(&self, index: MovePathIndex) -> MovePathIndex { | |
216 | (*self.paths.borrow())[index.get()].first_child | |
217 | } | |
218 | ||
219 | fn path_next_sibling(&self, index: MovePathIndex) -> MovePathIndex { | |
220 | (*self.paths.borrow())[index.get()].next_sibling | |
221 | } | |
222 | ||
223 | fn set_path_first_move(&self, | |
224 | index: MovePathIndex, | |
225 | first_move: MoveIndex) { | |
226 | (*self.paths.borrow_mut())[index.get()].first_move = first_move | |
227 | } | |
228 | ||
229 | fn set_path_first_child(&self, | |
230 | index: MovePathIndex, | |
231 | first_child: MovePathIndex) { | |
232 | (*self.paths.borrow_mut())[index.get()].first_child = first_child | |
233 | } | |
234 | ||
235 | fn move_next_move(&self, index: MoveIndex) -> MoveIndex { | |
236 | //! Type safe indexing operator | |
237 | (*self.moves.borrow())[index.get()].next_move | |
238 | } | |
239 | ||
240 | fn is_var_path(&self, index: MovePathIndex) -> bool { | |
241 | //! True if `index` refers to a variable | |
242 | self.path_parent(index) == InvalidMovePathIndex | |
243 | } | |
244 | ||
245 | /// Returns the existing move path index for `lp`, if any, and otherwise adds a new index for | |
246 | /// `lp` and any of its base paths that do not yet have an index. | |
a7813a04 | 247 | pub fn move_path(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, |
1a4d82fc | 248 | lp: Rc<LoanPath<'tcx>>) -> MovePathIndex { |
3157f602 XL |
249 | if let Some(&index) = self.path_map.borrow().get(&lp) { |
250 | return index; | |
1a4d82fc JJ |
251 | } |
252 | ||
253 | let index = match lp.kind { | |
254 | LpVar(..) | LpUpvar(..) => { | |
255 | let index = MovePathIndex(self.paths.borrow().len()); | |
256 | ||
257 | self.paths.borrow_mut().push(MovePath { | |
258 | loan_path: lp.clone(), | |
259 | parent: InvalidMovePathIndex, | |
260 | first_move: InvalidMoveIndex, | |
261 | first_child: InvalidMovePathIndex, | |
262 | next_sibling: InvalidMovePathIndex, | |
263 | }); | |
264 | ||
265 | index | |
266 | } | |
267 | ||
268 | LpDowncast(ref base, _) | | |
9e0c209e | 269 | LpExtend(ref base, ..) => { |
1a4d82fc JJ |
270 | let parent_index = self.move_path(tcx, base.clone()); |
271 | ||
272 | let index = MovePathIndex(self.paths.borrow().len()); | |
273 | ||
274 | let next_sibling = self.path_first_child(parent_index); | |
275 | self.set_path_first_child(parent_index, index); | |
276 | ||
277 | self.paths.borrow_mut().push(MovePath { | |
278 | loan_path: lp.clone(), | |
279 | parent: parent_index, | |
280 | first_move: InvalidMoveIndex, | |
281 | first_child: InvalidMovePathIndex, | |
3b2f2976 | 282 | next_sibling, |
1a4d82fc JJ |
283 | }); |
284 | ||
285 | index | |
286 | } | |
287 | }; | |
288 | ||
62682a34 SL |
289 | debug!("move_path(lp={:?}, index={:?})", |
290 | lp, | |
1a4d82fc JJ |
291 | index); |
292 | ||
293 | assert_eq!(index.get(), self.paths.borrow().len() - 1); | |
294 | self.path_map.borrow_mut().insert(lp, index); | |
295 | return index; | |
296 | } | |
297 | ||
298 | fn existing_move_path(&self, lp: &Rc<LoanPath<'tcx>>) | |
299 | -> Option<MovePathIndex> { | |
300 | self.path_map.borrow().get(lp).cloned() | |
301 | } | |
302 | ||
303 | fn existing_base_paths(&self, lp: &Rc<LoanPath<'tcx>>) | |
304 | -> Vec<MovePathIndex> { | |
c30ab7b3 | 305 | let mut result = vec![]; |
1a4d82fc JJ |
306 | self.add_existing_base_paths(lp, &mut result); |
307 | result | |
308 | } | |
309 | ||
310 | /// Adds any existing move path indices for `lp` and any base paths of `lp` to `result`, but | |
311 | /// does not add new move paths | |
312 | fn add_existing_base_paths(&self, lp: &Rc<LoanPath<'tcx>>, | |
313 | result: &mut Vec<MovePathIndex>) { | |
314 | match self.path_map.borrow().get(lp).cloned() { | |
315 | Some(index) => { | |
316 | self.each_base_path(index, |p| { | |
317 | result.push(p); | |
318 | true | |
319 | }); | |
320 | } | |
321 | None => { | |
322 | match lp.kind { | |
323 | LpVar(..) | LpUpvar(..) => { } | |
324 | LpDowncast(ref b, _) | | |
9e0c209e | 325 | LpExtend(ref b, ..) => { |
1a4d82fc JJ |
326 | self.add_existing_base_paths(b, result); |
327 | } | |
328 | } | |
329 | } | |
330 | } | |
331 | ||
332 | } | |
333 | ||
334 | /// Adds a new move entry for a move of `lp` that occurs at location `id` with kind `kind`. | |
a7813a04 | 335 | pub fn add_move(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, |
cc61c64b | 336 | orig_lp: Rc<LoanPath<'tcx>>, |
ea8adc8c | 337 | id: hir::ItemLocalId, |
1a4d82fc | 338 | kind: MoveKind) { |
cc61c64b XL |
339 | // Moving one union field automatically moves all its fields. Also move siblings of |
340 | // all parent union fields, moves do not propagate upwards automatically. | |
341 | let mut lp = orig_lp.clone(); | |
342 | while let LpExtend(ref base_lp, mutbl, lp_elem) = lp.clone().kind { | |
343 | if let (&ty::TyAdt(adt_def, _), LpInterior(opt_variant_id, interior)) | |
344 | = (&base_lp.ty.sty, lp_elem) { | |
9e0c209e SL |
345 | if adt_def.is_union() { |
346 | for field in &adt_def.struct_variant().fields { | |
347 | let field = InteriorKind::InteriorField(mc::NamedField(field.name)); | |
cc61c64b XL |
348 | if field != interior { |
349 | let sibling_lp_kind = | |
350 | LpExtend(base_lp.clone(), mutbl, LpInterior(opt_variant_id, field)); | |
351 | let sibling_lp = Rc::new(LoanPath::new(sibling_lp_kind, tcx.types.err)); | |
352 | self.add_move_helper(tcx, sibling_lp, id, kind); | |
353 | } | |
9e0c209e | 354 | } |
9e0c209e SL |
355 | } |
356 | } | |
cc61c64b | 357 | lp = base_lp.clone(); |
9e0c209e SL |
358 | } |
359 | ||
cc61c64b | 360 | self.add_move_helper(tcx, orig_lp.clone(), id, kind); |
9e0c209e SL |
361 | } |
362 | ||
363 | fn add_move_helper(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, | |
364 | lp: Rc<LoanPath<'tcx>>, | |
ea8adc8c | 365 | id: hir::ItemLocalId, |
9e0c209e | 366 | kind: MoveKind) { |
ea8adc8c | 367 | debug!("add_move(lp={:?}, id={:?}, kind={:?})", |
62682a34 | 368 | lp, |
1a4d82fc JJ |
369 | id, |
370 | kind); | |
371 | ||
372 | let path_index = self.move_path(tcx, lp.clone()); | |
373 | let move_index = MoveIndex(self.moves.borrow().len()); | |
374 | ||
1a4d82fc JJ |
375 | let next_move = self.path_first_move(path_index); |
376 | self.set_path_first_move(path_index, move_index); | |
377 | ||
378 | self.moves.borrow_mut().push(Move { | |
379 | path: path_index, | |
3b2f2976 XL |
380 | id, |
381 | kind, | |
382 | next_move, | |
1a4d82fc JJ |
383 | }); |
384 | } | |
385 | ||
386 | /// Adds a new record for an assignment to `lp` that occurs at location `id` with the given | |
387 | /// `span`. | |
a7813a04 | 388 | pub fn add_assignment(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, |
1a4d82fc | 389 | lp: Rc<LoanPath<'tcx>>, |
ea8adc8c | 390 | assign_id: hir::ItemLocalId, |
1a4d82fc | 391 | span: Span, |
ea8adc8c | 392 | assignee_id: hir::ItemLocalId, |
1a4d82fc | 393 | mode: euv::MutateMode) { |
9e0c209e SL |
394 | // Assigning to one union field automatically assigns to all its fields. |
395 | if let LpExtend(ref base_lp, mutbl, LpInterior(opt_variant_id, interior)) = lp.kind { | |
396 | if let ty::TyAdt(adt_def, _) = base_lp.ty.sty { | |
397 | if adt_def.is_union() { | |
398 | for field in &adt_def.struct_variant().fields { | |
399 | let field = InteriorKind::InteriorField(mc::NamedField(field.name)); | |
400 | let field_ty = if field == interior { | |
401 | lp.ty | |
402 | } else { | |
403 | tcx.types.err // Doesn't matter | |
404 | }; | |
405 | let sibling_lp_kind = LpExtend(base_lp.clone(), mutbl, | |
406 | LpInterior(opt_variant_id, field)); | |
407 | let sibling_lp = Rc::new(LoanPath::new(sibling_lp_kind, field_ty)); | |
408 | self.add_assignment_helper(tcx, sibling_lp, assign_id, | |
409 | span, assignee_id, mode); | |
410 | } | |
411 | return; | |
412 | } | |
413 | } | |
414 | } | |
415 | ||
416 | self.add_assignment_helper(tcx, lp.clone(), assign_id, span, assignee_id, mode); | |
417 | } | |
418 | ||
419 | fn add_assignment_helper(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, | |
420 | lp: Rc<LoanPath<'tcx>>, | |
ea8adc8c | 421 | assign_id: hir::ItemLocalId, |
9e0c209e | 422 | span: Span, |
ea8adc8c | 423 | assignee_id: hir::ItemLocalId, |
9e0c209e | 424 | mode: euv::MutateMode) { |
ea8adc8c | 425 | debug!("add_assignment(lp={:?}, assign_id={:?}, assignee_id={:?}", |
62682a34 | 426 | lp, assign_id, assignee_id); |
1a4d82fc JJ |
427 | |
428 | let path_index = self.move_path(tcx, lp.clone()); | |
429 | ||
1a4d82fc | 430 | match mode { |
9cc50fc6 | 431 | MutateMode::Init | MutateMode::JustWrite => { |
1a4d82fc JJ |
432 | self.assignee_ids.borrow_mut().insert(assignee_id); |
433 | } | |
9cc50fc6 | 434 | MutateMode::WriteAndRead => { } |
1a4d82fc JJ |
435 | } |
436 | ||
437 | let assignment = Assignment { | |
438 | path: path_index, | |
439 | id: assign_id, | |
3b2f2976 XL |
440 | span, |
441 | assignee_id, | |
1a4d82fc JJ |
442 | }; |
443 | ||
444 | if self.is_var_path(path_index) { | |
62682a34 SL |
445 | debug!("add_assignment[var](lp={:?}, assignment={}, path_index={:?})", |
446 | lp, self.var_assignments.borrow().len(), path_index); | |
1a4d82fc JJ |
447 | |
448 | self.var_assignments.borrow_mut().push(assignment); | |
449 | } else { | |
62682a34 SL |
450 | debug!("add_assignment[path](lp={:?}, path_index={:?})", |
451 | lp, path_index); | |
1a4d82fc JJ |
452 | |
453 | self.path_assignments.borrow_mut().push(assignment); | |
454 | } | |
455 | } | |
456 | ||
1a4d82fc JJ |
457 | /// Adds the gen/kills for the various moves and |
458 | /// assignments into the provided data flow contexts. | |
459 | /// Moves are generated by moves and killed by assignments and | |
460 | /// scoping. Assignments are generated by assignment to variables and | |
c34b1796 | 461 | /// killed by scoping. See `README.md` for more details. |
7cac9316 XL |
462 | fn add_gen_kills(&self, |
463 | bccx: &BorrowckCtxt<'a, 'tcx>, | |
1a4d82fc JJ |
464 | dfcx_moves: &mut MoveDataFlow, |
465 | dfcx_assign: &mut AssignDataFlow) { | |
466 | for (i, the_move) in self.moves.borrow().iter().enumerate() { | |
467 | dfcx_moves.add_gen(the_move.id, i); | |
468 | } | |
469 | ||
470 | for (i, assignment) in self.var_assignments.borrow().iter().enumerate() { | |
471 | dfcx_assign.add_gen(assignment.id, i); | |
9346a6ac AL |
472 | self.kill_moves(assignment.path, assignment.id, |
473 | KillFrom::Execution, dfcx_moves); | |
1a4d82fc JJ |
474 | } |
475 | ||
62682a34 | 476 | for assignment in self.path_assignments.borrow().iter() { |
9346a6ac AL |
477 | self.kill_moves(assignment.path, assignment.id, |
478 | KillFrom::Execution, dfcx_moves); | |
1a4d82fc JJ |
479 | } |
480 | ||
481 | // Kill all moves related to a variable `x` when | |
482 | // it goes out of scope: | |
62682a34 | 483 | for path in self.paths.borrow().iter() { |
1a4d82fc JJ |
484 | match path.loan_path.kind { |
485 | LpVar(..) | LpUpvar(..) | LpDowncast(..) => { | |
7cac9316 | 486 | let kill_scope = path.loan_path.kill_scope(bccx); |
c34b1796 | 487 | let path = *self.path_map.borrow().get(&path.loan_path).unwrap(); |
ea8adc8c | 488 | self.kill_moves(path, kill_scope.item_local_id(), |
9346a6ac | 489 | KillFrom::ScopeEnd, dfcx_moves); |
1a4d82fc JJ |
490 | } |
491 | LpExtend(..) => {} | |
492 | } | |
493 | } | |
494 | ||
495 | // Kill all assignments when the variable goes out of scope: | |
496 | for (assignment_index, assignment) in | |
497 | self.var_assignments.borrow().iter().enumerate() { | |
498 | let lp = self.path_loan_path(assignment.path); | |
499 | match lp.kind { | |
500 | LpVar(..) | LpUpvar(..) | LpDowncast(..) => { | |
7cac9316 | 501 | let kill_scope = lp.kill_scope(bccx); |
9346a6ac | 502 | dfcx_assign.add_kill(KillFrom::ScopeEnd, |
ea8adc8c | 503 | kill_scope.item_local_id(), |
9346a6ac | 504 | assignment_index); |
1a4d82fc JJ |
505 | } |
506 | LpExtend(..) => { | |
54a0048b | 507 | bug!("var assignment for non var path"); |
1a4d82fc JJ |
508 | } |
509 | } | |
510 | } | |
511 | } | |
512 | ||
513 | fn each_base_path<F>(&self, index: MovePathIndex, mut f: F) -> bool where | |
514 | F: FnMut(MovePathIndex) -> bool, | |
515 | { | |
516 | let mut p = index; | |
517 | while p != InvalidMovePathIndex { | |
518 | if !f(p) { | |
519 | return false; | |
520 | } | |
521 | p = self.path_parent(p); | |
522 | } | |
523 | return true; | |
524 | } | |
525 | ||
526 | // FIXME(#19596) This is a workaround, but there should be better way to do this | |
527 | fn each_extending_path_<F>(&self, index: MovePathIndex, f: &mut F) -> bool where | |
528 | F: FnMut(MovePathIndex) -> bool, | |
529 | { | |
530 | if !(*f)(index) { | |
531 | return false; | |
532 | } | |
533 | ||
534 | let mut p = self.path_first_child(index); | |
535 | while p != InvalidMovePathIndex { | |
536 | if !self.each_extending_path_(p, f) { | |
537 | return false; | |
538 | } | |
539 | p = self.path_next_sibling(p); | |
540 | } | |
541 | ||
542 | return true; | |
543 | } | |
544 | ||
545 | fn each_extending_path<F>(&self, index: MovePathIndex, mut f: F) -> bool where | |
546 | F: FnMut(MovePathIndex) -> bool, | |
547 | { | |
548 | self.each_extending_path_(index, &mut f) | |
549 | } | |
550 | ||
551 | fn each_applicable_move<F>(&self, index0: MovePathIndex, mut f: F) -> bool where | |
552 | F: FnMut(MoveIndex) -> bool, | |
553 | { | |
554 | let mut ret = true; | |
555 | self.each_extending_path(index0, |index| { | |
556 | let mut p = self.path_first_move(index); | |
557 | while p != InvalidMoveIndex { | |
558 | if !f(p) { | |
559 | ret = false; | |
560 | break; | |
561 | } | |
562 | p = self.move_next_move(p); | |
563 | } | |
564 | ret | |
565 | }); | |
566 | ret | |
567 | } | |
568 | ||
569 | fn kill_moves(&self, | |
570 | path: MovePathIndex, | |
ea8adc8c | 571 | kill_id: hir::ItemLocalId, |
9346a6ac | 572 | kill_kind: KillFrom, |
1a4d82fc JJ |
573 | dfcx_moves: &mut MoveDataFlow) { |
574 | // We can only perform kills for paths that refer to a unique location, | |
575 | // since otherwise we may kill a move from one location with an | |
576 | // assignment referring to another location. | |
577 | ||
578 | let loan_path = self.path_loan_path(path); | |
7453a54e | 579 | if loan_path_is_precise(&loan_path) { |
1a4d82fc | 580 | self.each_applicable_move(path, |move_index| { |
ea8adc8c | 581 | debug!("kill_moves add_kill {:?} kill_id={:?} move_index={}", |
9346a6ac AL |
582 | kill_kind, kill_id, move_index.get()); |
583 | dfcx_moves.add_kill(kill_kind, kill_id, move_index.get()); | |
1a4d82fc JJ |
584 | true |
585 | }); | |
586 | } | |
587 | } | |
588 | } | |
589 | ||
590 | impl<'a, 'tcx> FlowedMoveData<'a, 'tcx> { | |
591 | pub fn new(move_data: MoveData<'tcx>, | |
7cac9316 | 592 | bccx: &BorrowckCtxt<'a, 'tcx>, |
1a4d82fc | 593 | cfg: &cfg::CFG, |
54a0048b | 594 | id_range: IdRange, |
32a655c1 | 595 | body: &hir::Body) |
1a4d82fc | 596 | -> FlowedMoveData<'a, 'tcx> { |
7cac9316 XL |
597 | let tcx = bccx.tcx; |
598 | ||
1a4d82fc JJ |
599 | let mut dfcx_moves = |
600 | DataFlowContext::new(tcx, | |
601 | "flowed_move_data_moves", | |
32a655c1 | 602 | Some(body), |
1a4d82fc JJ |
603 | cfg, |
604 | MoveDataFlowOperator, | |
605 | id_range, | |
606 | move_data.moves.borrow().len()); | |
607 | let mut dfcx_assign = | |
608 | DataFlowContext::new(tcx, | |
609 | "flowed_move_data_assigns", | |
32a655c1 | 610 | Some(body), |
1a4d82fc JJ |
611 | cfg, |
612 | AssignDataFlowOperator, | |
613 | id_range, | |
614 | move_data.var_assignments.borrow().len()); | |
615 | ||
7cac9316 | 616 | move_data.add_gen_kills(bccx, |
1a4d82fc JJ |
617 | &mut dfcx_moves, |
618 | &mut dfcx_assign); | |
619 | ||
620 | dfcx_moves.add_kills_from_flow_exits(cfg); | |
621 | dfcx_assign.add_kills_from_flow_exits(cfg); | |
622 | ||
623 | dfcx_moves.propagate(cfg, body); | |
624 | dfcx_assign.propagate(cfg, body); | |
625 | ||
626 | FlowedMoveData { | |
3b2f2976 XL |
627 | move_data, |
628 | dfcx_moves, | |
629 | dfcx_assign, | |
1a4d82fc JJ |
630 | } |
631 | } | |
632 | ||
633 | pub fn kind_of_move_of_path(&self, | |
ea8adc8c | 634 | id: hir::ItemLocalId, |
1a4d82fc JJ |
635 | loan_path: &Rc<LoanPath<'tcx>>) |
636 | -> Option<MoveKind> { | |
637 | //! Returns the kind of a move of `loan_path` by `id`, if one exists. | |
638 | ||
639 | let mut ret = None; | |
85aaf69f | 640 | if let Some(loan_path_index) = self.move_data.path_map.borrow().get(&*loan_path) { |
1a4d82fc JJ |
641 | self.dfcx_moves.each_gen_bit(id, |move_index| { |
642 | let the_move = self.move_data.moves.borrow(); | |
643 | let the_move = (*the_move)[move_index]; | |
85aaf69f | 644 | if the_move.path == *loan_path_index { |
1a4d82fc JJ |
645 | ret = Some(the_move.kind); |
646 | false | |
647 | } else { | |
648 | true | |
649 | } | |
650 | }); | |
651 | } | |
652 | ret | |
653 | } | |
654 | ||
655 | /// Iterates through each move of `loan_path` (or some base path of `loan_path`) that *may* | |
656 | /// have occurred on entry to `id` without an intervening assignment. In other words, any moves | |
657 | /// that would invalidate a reference to `loan_path` at location `id`. | |
658 | pub fn each_move_of<F>(&self, | |
ea8adc8c | 659 | id: hir::ItemLocalId, |
1a4d82fc JJ |
660 | loan_path: &Rc<LoanPath<'tcx>>, |
661 | mut f: F) | |
662 | -> bool where | |
663 | F: FnMut(&Move, &LoanPath<'tcx>) -> bool, | |
664 | { | |
665 | // Bad scenarios: | |
666 | // | |
667 | // 1. Move of `a.b.c`, use of `a.b.c` | |
668 | // 2. Move of `a.b.c`, use of `a.b.c.d` | |
669 | // 3. Move of `a.b.c`, use of `a` or `a.b` | |
670 | // | |
671 | // OK scenario: | |
672 | // | |
673 | // 4. move of `a.b.c`, use of `a.b.d` | |
674 | ||
675 | let base_indices = self.move_data.existing_base_paths(loan_path); | |
676 | if base_indices.is_empty() { | |
677 | return true; | |
678 | } | |
679 | ||
680 | let opt_loan_path_index = self.move_data.existing_move_path(loan_path); | |
681 | ||
682 | let mut ret = true; | |
683 | ||
684 | self.dfcx_moves.each_bit_on_entry(id, |index| { | |
685 | let the_move = self.move_data.moves.borrow(); | |
686 | let the_move = &(*the_move)[index]; | |
687 | let moved_path = the_move.path; | |
688 | if base_indices.iter().any(|x| x == &moved_path) { | |
689 | // Scenario 1 or 2: `loan_path` or some base path of | |
690 | // `loan_path` was moved. | |
7453a54e | 691 | if !f(the_move, &self.move_data.path_loan_path(moved_path)) { |
1a4d82fc JJ |
692 | ret = false; |
693 | } | |
694 | } else { | |
85aaf69f | 695 | if let Some(loan_path_index) = opt_loan_path_index { |
1a4d82fc JJ |
696 | let cont = self.move_data.each_base_path(moved_path, |p| { |
697 | if p == loan_path_index { | |
698 | // Scenario 3: some extension of `loan_path` | |
699 | // was moved | |
700 | f(the_move, | |
7453a54e | 701 | &self.move_data.path_loan_path(moved_path)) |
1a4d82fc JJ |
702 | } else { |
703 | true | |
704 | } | |
705 | }); | |
85aaf69f | 706 | if !cont { ret = false; } |
1a4d82fc JJ |
707 | } |
708 | } | |
709 | ret | |
710 | }) | |
711 | } | |
712 | ||
713 | /// Iterates through every assignment to `loan_path` that may have occurred on entry to `id`. | |
714 | /// `loan_path` must be a single variable. | |
715 | pub fn each_assignment_of<F>(&self, | |
ea8adc8c | 716 | id: hir::ItemLocalId, |
1a4d82fc JJ |
717 | loan_path: &Rc<LoanPath<'tcx>>, |
718 | mut f: F) | |
719 | -> bool where | |
720 | F: FnMut(&Assignment) -> bool, | |
721 | { | |
722 | let loan_path_index = { | |
723 | match self.move_data.existing_move_path(loan_path) { | |
724 | Some(i) => i, | |
725 | None => { | |
726 | // if there were any assignments, it'd have an index | |
727 | return true; | |
728 | } | |
729 | } | |
730 | }; | |
731 | ||
732 | self.dfcx_assign.each_bit_on_entry(id, |index| { | |
733 | let assignment = self.move_data.var_assignments.borrow(); | |
734 | let assignment = &(*assignment)[index]; | |
735 | if assignment.path == loan_path_index && !f(assignment) { | |
736 | false | |
737 | } else { | |
738 | true | |
739 | } | |
740 | }) | |
741 | } | |
742 | } | |
743 | ||
744 | impl BitwiseOperator for MoveDataFlowOperator { | |
745 | #[inline] | |
c34b1796 | 746 | fn join(&self, succ: usize, pred: usize) -> usize { |
1a4d82fc JJ |
747 | succ | pred // moves from both preds are in scope |
748 | } | |
749 | } | |
750 | ||
751 | impl DataFlowOperator for MoveDataFlowOperator { | |
752 | #[inline] | |
753 | fn initial_value(&self) -> bool { | |
754 | false // no loans in scope by default | |
755 | } | |
756 | } | |
757 | ||
758 | impl BitwiseOperator for AssignDataFlowOperator { | |
759 | #[inline] | |
c34b1796 | 760 | fn join(&self, succ: usize, pred: usize) -> usize { |
1a4d82fc JJ |
761 | succ | pred // moves from both preds are in scope |
762 | } | |
763 | } | |
764 | ||
765 | impl DataFlowOperator for AssignDataFlowOperator { | |
766 | #[inline] | |
767 | fn initial_value(&self) -> bool { | |
768 | false // no assignments in scope by default | |
769 | } | |
770 | } |