1 use rustc_data_structures::graph::dominators::Dominators;
2 use rustc_middle::mir::visit::Visitor;
3 use rustc_middle::mir::{BasicBlock, Body, Location, Place, Rvalue};
4 use rustc_middle::mir::{BorrowKind, Mutability, Operand};
5 use rustc_middle::mir::{InlineAsmOperand, Terminator, TerminatorKind};
6 use rustc_middle::mir::{Statement, StatementKind};
7 use rustc_middle::ty::TyCtxt;
9 use crate::dataflow::indexes::BorrowIndex;
11 use crate::borrow_check::{
12 borrow_set::BorrowSet, facts::AllFacts, location::LocationTable, path_utils::*, AccessDepth,
13 Activation, ArtificialField, Deep, JustWrite, LocalMutationIsAllowed, MutateMode, Read,
14 ReadKind, ReadOrWrite, Reservation, Shallow, Write, WriteAndRead, WriteKind,
17 pub(super) fn generate_invalidates<'tcx>(
19 all_facts: &mut Option<AllFacts>,
20 location_table: &LocationTable,
22 borrow_set: &BorrowSet<'tcx>,
24 if all_facts.is_none() {
25 // Nothing to do if we don't have any facts
29 if let Some(all_facts) = all_facts {
30 let _prof_timer = tcx.prof.generic_activity("polonius_fact_generation");
31 let dominators = body.dominators();
32 let mut ig = InvalidationGenerator {
44 struct InvalidationGenerator<'cx, 'tcx> {
46 all_facts: &'cx mut AllFacts,
47 location_table: &'cx LocationTable,
48 body: &'cx Body<'tcx>,
49 dominators: Dominators<BasicBlock>,
50 borrow_set: &'cx BorrowSet<'tcx>,
53 /// Visits the whole MIR and generates `invalidates()` facts.
54 /// Most of the code implementing this was stolen from `borrow_check/mod.rs`.
55 impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
56 fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
57 self.check_activations(location);
59 match &statement.kind {
60 StatementKind::Assign(box (lhs, rhs)) => {
61 self.consume_rvalue(location, rhs);
63 self.mutate_place(location, *lhs, Shallow(None), JustWrite);
65 StatementKind::FakeRead(_, _) => {
66 // Only relevant for initialized/liveness/safety checks.
68 StatementKind::SetDiscriminant { place, variant_index: _ } => {
69 self.mutate_place(location, **place, Shallow(None), JustWrite);
71 StatementKind::LlvmInlineAsm(asm) => {
72 for (o, output) in asm.asm.outputs.iter().zip(asm.outputs.iter()) {
74 // FIXME(eddyb) indirect inline asm outputs should
75 // be encoded through MIR place derefs instead.
79 (Deep, Read(ReadKind::Copy)),
80 LocalMutationIsAllowed::No,
86 if o.is_rw { Deep } else { Shallow(None) },
87 if o.is_rw { WriteAndRead } else { JustWrite },
91 for (_, input) in asm.inputs.iter() {
92 self.consume_operand(location, input);
96 | StatementKind::Coverage(..)
97 | StatementKind::AscribeUserType(..)
98 | StatementKind::Retag { .. }
99 | StatementKind::StorageLive(..) => {
100 // `Nop`, `AscribeUserType`, `Retag`, and `StorageLive` are irrelevant
103 StatementKind::StorageDead(local) => {
107 (Shallow(None), Write(WriteKind::StorageDeadOrDrop)),
108 LocalMutationIsAllowed::Yes,
113 self.super_statement(statement, location);
116 fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
117 self.check_activations(location);
119 match &terminator.kind {
120 TerminatorKind::SwitchInt { ref discr, switch_ty: _, targets: _ } => {
121 self.consume_operand(location, discr);
123 TerminatorKind::Drop { place: drop_place, target: _, unwind: _ } => {
127 (AccessDepth::Drop, Write(WriteKind::StorageDeadOrDrop)),
128 LocalMutationIsAllowed::Yes,
131 TerminatorKind::DropAndReplace {
133 value: ref new_value,
137 self.mutate_place(location, *drop_place, Deep, JustWrite);
138 self.consume_operand(location, new_value);
140 TerminatorKind::Call {
148 self.consume_operand(location, func);
150 self.consume_operand(location, arg);
152 if let Some((dest, _ /*bb*/)) = destination {
153 self.mutate_place(location, *dest, Deep, JustWrite);
156 TerminatorKind::Assert { ref cond, expected: _, ref msg, target: _, cleanup: _ } => {
157 self.consume_operand(location, cond);
158 use rustc_middle::mir::AssertKind;
159 if let AssertKind::BoundsCheck { ref len, ref index } = *msg {
160 self.consume_operand(location, len);
161 self.consume_operand(location, index);
164 TerminatorKind::Yield { ref value, resume, resume_arg, drop: _ } => {
165 self.consume_operand(location, value);
167 // Invalidate all borrows of local places
168 let borrow_set = self.borrow_set.clone();
169 let resume = self.location_table.start_index(resume.start_location());
170 for (i, data) in borrow_set.iter_enumerated() {
171 if borrow_of_local_data(data.borrowed_place) {
172 self.all_facts.invalidates.push((resume, i));
176 self.mutate_place(location, *resume_arg, Deep, JustWrite);
178 TerminatorKind::Resume | TerminatorKind::Return | TerminatorKind::GeneratorDrop => {
179 // Invalidate all borrows of local places
180 let borrow_set = self.borrow_set.clone();
181 let start = self.location_table.start_index(location);
182 for (i, data) in borrow_set.iter_enumerated() {
183 if borrow_of_local_data(data.borrowed_place) {
184 self.all_facts.invalidates.push((start, i));
188 TerminatorKind::InlineAsm {
197 InlineAsmOperand::In { reg: _, ref value }
198 | InlineAsmOperand::Const { ref value } => {
199 self.consume_operand(location, value);
201 InlineAsmOperand::Out { reg: _, late: _, place, .. } => {
202 if let Some(place) = place {
203 self.mutate_place(location, place, Shallow(None), JustWrite);
206 InlineAsmOperand::InOut { reg: _, late: _, ref in_value, out_place } => {
207 self.consume_operand(location, in_value);
208 if let Some(out_place) = out_place {
209 self.mutate_place(location, out_place, Shallow(None), JustWrite);
212 InlineAsmOperand::SymFn { value: _ }
213 | InlineAsmOperand::SymStatic { def_id: _ } => {}
217 TerminatorKind::Goto { target: _ }
218 | TerminatorKind::Abort
219 | TerminatorKind::Unreachable
220 | TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ }
221 | TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => {
222 // no data used, thus irrelevant to borrowck
226 self.super_terminator(terminator, location);
230 impl<'cx, 'tcx> InvalidationGenerator<'cx, 'tcx> {
231 /// Simulates mutation of a place.
242 (kind, Write(WriteKind::Mutate)),
243 LocalMutationIsAllowed::ExceptUpvars,
247 /// Simulates consumption of an operand.
248 fn consume_operand(&mut self, location: Location, operand: &Operand<'tcx>) {
250 Operand::Copy(place) => {
254 (Deep, Read(ReadKind::Copy)),
255 LocalMutationIsAllowed::No,
258 Operand::Move(place) => {
262 (Deep, Write(WriteKind::Move)),
263 LocalMutationIsAllowed::Yes,
266 Operand::Constant(_) => {}
270 // Simulates consumption of an rvalue
271 fn consume_rvalue(&mut self, location: Location, rvalue: &Rvalue<'tcx>) {
273 Rvalue::Ref(_ /*rgn*/, bk, place) => {
274 let access_kind = match bk {
275 BorrowKind::Shallow => {
276 (Shallow(Some(ArtificialField::ShallowBorrow)), Read(ReadKind::Borrow(bk)))
278 BorrowKind::Shared => (Deep, Read(ReadKind::Borrow(bk))),
279 BorrowKind::Unique | BorrowKind::Mut { .. } => {
280 let wk = WriteKind::MutableBorrow(bk);
281 if allow_two_phase_borrow(bk) {
282 (Deep, Reservation(wk))
289 self.access_place(location, place, access_kind, LocalMutationIsAllowed::No);
292 Rvalue::AddressOf(mutability, place) => {
293 let access_kind = match mutability {
296 Write(WriteKind::MutableBorrow(BorrowKind::Mut {
297 allow_two_phase_borrow: false,
300 Mutability::Not => (Deep, Read(ReadKind::Borrow(BorrowKind::Shared))),
303 self.access_place(location, place, access_kind, LocalMutationIsAllowed::No);
306 Rvalue::ThreadLocalRef(_) => {}
308 Rvalue::Use(ref operand)
309 | Rvalue::Repeat(ref operand, _)
310 | Rvalue::UnaryOp(_ /*un_op*/, ref operand)
311 | Rvalue::Cast(_ /*cast_kind*/, ref operand, _ /*ty*/) => {
312 self.consume_operand(location, operand)
315 Rvalue::Len(place) | Rvalue::Discriminant(place) => {
316 let af = match *rvalue {
317 Rvalue::Len(..) => Some(ArtificialField::ArrayLength),
318 Rvalue::Discriminant(..) => None,
324 (Shallow(af), Read(ReadKind::Copy)),
325 LocalMutationIsAllowed::No,
329 Rvalue::BinaryOp(_bin_op, box (ref operand1, ref operand2))
330 | Rvalue::CheckedBinaryOp(_bin_op, box (ref operand1, ref operand2)) => {
331 self.consume_operand(location, operand1);
332 self.consume_operand(location, operand2);
335 Rvalue::NullaryOp(_op, _ty) => {}
337 Rvalue::Aggregate(_, ref operands) => {
338 for operand in operands {
339 self.consume_operand(location, operand);
345 /// Simulates an access to a place.
350 kind: (AccessDepth, ReadOrWrite),
351 _is_local_mutation_allowed: LocalMutationIsAllowed,
354 // note: not doing check_access_permissions checks because they don't generate invalidates
355 self.check_access_for_conflict(location, place, sd, rw);
358 fn check_access_for_conflict(
366 "invalidation::check_access_for_conflict(location={:?}, place={:?}, sd={:?}, \
368 location, place, sd, rw,
371 let body = self.body;
372 let borrow_set = self.borrow_set.clone();
373 let indices = self.borrow_set.indices();
374 each_borrow_involving_path(
382 |this, borrow_index, borrow| {
383 match (rw, borrow.kind) {
384 // Obviously an activation is compatible with its own
385 // reservation (or even prior activating uses of same
386 // borrow); so don't check if they interfere.
388 // NOTE: *reservations* do conflict with themselves;
389 // thus aren't injecting unsoundenss w/ this check.)
390 (Activation(_, activating), _) if activating == borrow_index => {
391 // Activating a borrow doesn't generate any invalidations, since we
392 // have already taken the reservation
395 (Read(_), BorrowKind::Shallow | BorrowKind::Shared)
397 Read(ReadKind::Borrow(BorrowKind::Shallow)),
398 BorrowKind::Unique | BorrowKind::Mut { .. },
400 // Reads don't invalidate shared or shallow borrows
403 (Read(_), BorrowKind::Unique | BorrowKind::Mut { .. }) => {
404 // Reading from mere reservations of mutable-borrows is OK.
405 if !is_active(&this.dominators, borrow, location) {
406 // If the borrow isn't active yet, reads don't invalidate it
407 assert!(allow_two_phase_borrow(borrow.kind));
408 return Control::Continue;
411 // Unique and mutable borrows are invalidated by reads from any
413 this.generate_invalidates(borrow_index, location);
416 (Reservation(_) | Activation(_, _) | Write(_), _) => {
417 // unique or mutable borrows are invalidated by writes.
418 // Reservations count as writes since we need to check
419 // that activating the borrow will be OK
420 // FIXME(bob_twinkles) is this actually the right thing to do?
421 this.generate_invalidates(borrow_index, location);
429 /// Generates a new `invalidates(L, B)` fact.
430 fn generate_invalidates(&mut self, b: BorrowIndex, l: Location) {
431 let lidx = self.location_table.start_index(l);
432 self.all_facts.invalidates.push((lidx, b));
435 fn check_activations(&mut self, location: Location) {
436 // Two-phase borrow support: For each activation that is newly
437 // generated at this statement, check if it interferes with
439 for &borrow_index in self.borrow_set.activations_at_location(location) {
440 let borrow = &self.borrow_set[borrow_index];
442 // only mutable borrows should be 2-phase
443 assert!(match borrow.kind {
444 BorrowKind::Shared | BorrowKind::Shallow => false,
445 BorrowKind::Unique | BorrowKind::Mut { .. } => true,
450 borrow.borrowed_place,
451 (Deep, Activation(WriteKind::MutableBorrow(borrow.kind), borrow_index)),
452 LocalMutationIsAllowed::No,
455 // We do not need to call `check_if_path_or_subpath_is_moved`
456 // again, as we already called it when we made the
457 // initial reservation.