rustc_borrowck/polonius/legacy/
accesses.rs

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1use rustc_middle::mir::visit::{MutatingUseContext, PlaceContext, Visitor};
2use rustc_middle::mir::{Body, Local, Location, Place};
3use rustc_middle::ty::TyCtxt;
4use rustc_mir_dataflow::move_paths::{LookupResult, MoveData};
5use tracing::debug;
6
7use super::{LocationIndex, PoloniusFacts, PoloniusLocationTable};
8use crate::def_use::{self, DefUse};
9use crate::universal_regions::UniversalRegions;
10
11/// Emit polonius facts for variable defs, uses, drops, and path accesses.
12pub(crate) fn emit_access_facts<'tcx>(
13    tcx: TyCtxt<'tcx>,
14    facts: &mut PoloniusFacts,
15    body: &Body<'tcx>,
16    location_table: &PoloniusLocationTable,
17    move_data: &MoveData<'tcx>,
18    universal_regions: &UniversalRegions<'tcx>,
19) {
20    let mut extractor = AccessFactsExtractor { facts, move_data, location_table };
21    extractor.visit_body(body);
22
23    for (local, local_decl) in body.local_decls.iter_enumerated() {
24        debug!("add use_of_var_derefs_origin facts - local={:?}, type={:?}", local, local_decl.ty);
25        tcx.for_each_free_region(&local_decl.ty, |region| {
26            let region_vid = universal_regions.to_region_vid(region);
27            facts.use_of_var_derefs_origin.push((local, region_vid.into()));
28        });
29    }
30}
31
32/// MIR visitor extracting point-wise facts about accesses.
33struct AccessFactsExtractor<'a, 'tcx> {
34    facts: &'a mut PoloniusFacts,
35    move_data: &'a MoveData<'tcx>,
36    location_table: &'a PoloniusLocationTable,
37}
38
39impl<'tcx> AccessFactsExtractor<'_, 'tcx> {
40    fn location_to_index(&self, location: Location) -> LocationIndex {
41        self.location_table.mid_index(location)
42    }
43}
44
45impl<'a, 'tcx> Visitor<'tcx> for AccessFactsExtractor<'a, 'tcx> {
46    fn visit_local(&mut self, local: Local, context: PlaceContext, location: Location) {
47        match def_use::categorize(context) {
48            Some(DefUse::Def) => {
49                debug!("AccessFactsExtractor - emit def");
50                self.facts.var_defined_at.push((local, self.location_to_index(location)));
51            }
52            Some(DefUse::Use) => {
53                debug!("AccessFactsExtractor - emit use");
54                self.facts.var_used_at.push((local, self.location_to_index(location)));
55            }
56            Some(DefUse::Drop) => {
57                debug!("AccessFactsExtractor - emit drop");
58                self.facts.var_dropped_at.push((local, self.location_to_index(location)));
59            }
60            _ => (),
61        }
62    }
63
64    fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
65        self.super_place(place, context, location);
66
67        match context {
68            PlaceContext::NonMutatingUse(_)
69            | PlaceContext::MutatingUse(MutatingUseContext::Borrow) => {
70                let path = match self.move_data.rev_lookup.find(place.as_ref()) {
71                    LookupResult::Exact(path) | LookupResult::Parent(Some(path)) => path,
72                    _ => {
73                        // There's no path access to emit.
74                        return;
75                    }
76                };
77                debug!("AccessFactsExtractor - emit path access ({path:?}, {location:?})");
78                self.facts.path_accessed_at_base.push((path, self.location_to_index(location)));
79            }
80
81            _ => {}
82        }
83    }
84}
rustc_borrowck/polonius/legacy/accesses.rs

rustc_borrowck/polonius/legacy/
accesses.rs
