1 files changed, 140 insertions, 0 deletions
diff --git a/compiler/rustc_borrowck/src/type_check/liveness/polonius.rs b/compiler/rustc_borrowck/src/type_check/liveness/polonius.rs
new file mode 100644
index 000000000..bc76a465e
--- /dev/null
+++ b/compiler/rustc_borrowck/src/type_check/liveness/polonius.rs
@@ -0,0 +1,140 @@
+use crate::def_use::{self, DefUse};
+use crate::location::{LocationIndex, LocationTable};
+use rustc_middle::mir::visit::{MutatingUseContext, PlaceContext, Visitor};
+use rustc_middle::mir::{Body, Local, Location, Place};
+use rustc_middle::ty::subst::GenericArg;
+use rustc_mir_dataflow::move_paths::{LookupResult, MoveData, MovePathIndex};
+
+use super::TypeChecker;
+
+type VarPointRelation = Vec<(Local, LocationIndex)>;
+type PathPointRelation = Vec<(MovePathIndex, LocationIndex)>;
+
+struct UseFactsExtractor<'me, 'tcx> {
+    var_defined_at: &'me mut VarPointRelation,
+    var_used_at: &'me mut VarPointRelation,
+    location_table: &'me LocationTable,
+    var_dropped_at: &'me mut VarPointRelation,
+    move_data: &'me MoveData<'tcx>,
+    path_accessed_at_base: &'me mut PathPointRelation,
+}
+
+// A Visitor to walk through the MIR and extract point-wise facts
+impl UseFactsExtractor<'_, '_> {
+    fn location_to_index(&self, location: Location) -> LocationIndex {
+        self.location_table.mid_index(location)
+    }
+
+    fn insert_def(&mut self, local: Local, location: Location) {
+        debug!("UseFactsExtractor::insert_def()");
+        self.var_defined_at.push((local, self.location_to_index(location)));
+    }
+
+    fn insert_use(&mut self, local: Local, location: Location) {
+        debug!("UseFactsExtractor::insert_use()");
+        self.var_used_at.push((local, self.location_to_index(location)));
+    }
+
+    fn insert_drop_use(&mut self, local: Local, location: Location) {
+        debug!("UseFactsExtractor::insert_drop_use()");
+        self.var_dropped_at.push((local, self.location_to_index(location)));
+    }
+
+    fn insert_path_access(&mut self, path: MovePathIndex, location: Location) {
+        debug!("UseFactsExtractor::insert_path_access({:?}, {:?})", path, location);
+        self.path_accessed_at_base.push((path, self.location_to_index(location)));
+    }
+
+    fn place_to_mpi(&self, place: &Place<'_>) -> Option<MovePathIndex> {
+        match self.move_data.rev_lookup.find(place.as_ref()) {
+            LookupResult::Exact(mpi) => Some(mpi),
+            LookupResult::Parent(mmpi) => mmpi,
+        }
+    }
+}
+
+impl<'a, 'tcx> Visitor<'tcx> for UseFactsExtractor<'a, 'tcx> {
+    fn visit_local(&mut self, local: Local, context: PlaceContext, location: Location) {
+        match def_use::categorize(context) {
+            Some(DefUse::Def) => self.insert_def(local, location),
+            Some(DefUse::Use) => self.insert_use(local, location),
+            Some(DefUse::Drop) => self.insert_drop_use(local, location),
+            _ => (),
+        }
+    }
+
+    fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
+        self.super_place(place, context, location);
+        match context {
+            PlaceContext::NonMutatingUse(_) => {
+                if let Some(mpi) = self.place_to_mpi(place) {
+                    self.insert_path_access(mpi, location);
+                }
+            }
+
+            PlaceContext::MutatingUse(MutatingUseContext::Borrow) => {
+                if let Some(mpi) = self.place_to_mpi(place) {
+                    self.insert_path_access(mpi, location);
+                }
+            }
+            _ => (),
+        }
+    }
+}
+
+pub(super) fn populate_access_facts<'a, 'tcx>(
+    typeck: &mut TypeChecker<'a, 'tcx>,
+    body: &Body<'tcx>,
+    location_table: &LocationTable,
+    move_data: &MoveData<'tcx>,
+    dropped_at: &mut Vec<(Local, Location)>,
+) {
+    debug!("populate_access_facts()");
+
+    if let Some(facts) = typeck.borrowck_context.all_facts.as_mut() {
+        let mut extractor = UseFactsExtractor {
+            var_defined_at: &mut facts.var_defined_at,
+            var_used_at: &mut facts.var_used_at,
+            var_dropped_at: &mut facts.var_dropped_at,
+            path_accessed_at_base: &mut facts.path_accessed_at_base,
+            location_table,
+            move_data,
+        };
+        extractor.visit_body(&body);
+
+        facts.var_dropped_at.extend(
+            dropped_at.iter().map(|&(local, location)| (local, location_table.mid_index(location))),
+        );
+
+        for (local, local_decl) in body.local_decls.iter_enumerated() {
+            debug!(
+                "add use_of_var_derefs_origin facts - local={:?}, type={:?}",
+                local, local_decl.ty
+            );
+            let _prof_timer = typeck.infcx.tcx.prof.generic_activity("polonius_fact_generation");
+            let universal_regions = &typeck.borrowck_context.universal_regions;
+            typeck.infcx.tcx.for_each_free_region(&local_decl.ty, |region| {
+                let region_vid = universal_regions.to_region_vid(region);
+                facts.use_of_var_derefs_origin.push((local, region_vid));
+            });
+        }
+    }
+}
+
+// For every potentially drop()-touched region `region` in `local`'s type
+// (`kind`), emit a Polonius `use_of_var_derefs_origin(local, origin)` fact.
+pub(super) fn add_drop_of_var_derefs_origin<'tcx>(
+    typeck: &mut TypeChecker<'_, 'tcx>,
+    local: Local,
+    kind: &GenericArg<'tcx>,
+) {
+    debug!("add_drop_of_var_derefs_origin(local={:?}, kind={:?}", local, kind);
+    if let Some(facts) = typeck.borrowck_context.all_facts.as_mut() {
+        let _prof_timer = typeck.infcx.tcx.prof.generic_activity("polonius_fact_generation");
+        let universal_regions = &typeck.borrowck_context.universal_regions;
+        typeck.infcx.tcx.for_each_free_region(kind, |drop_live_region| {
+            let region_vid = universal_regions.to_region_vid(drop_live_region);
+            facts.drop_of_var_derefs_origin.push((local, region_vid));
+        });
+    }
+}