Convert typeck constraints in location-sensitive polonius

compiler/rustc_borrowck/src/borrow_set.rs

@@ -11,7 +11,6 @@ use rustc_mir_dataflow::move_paths::MoveData;
 use tracing::debug;
 
 use crate::BorrowIndex;
-use crate::path_utils::allow_two_phase_borrow;
 use crate::place_ext::PlaceExt;
 
 pub struct BorrowSet<'tcx> {
@@ -350,7 +349,7 @@ impl<'a, 'tcx> GatherBorrows<'a, 'tcx> {
             start_location, assigned_place, borrow_index,
         );
 
-        if !allow_two_phase_borrow(kind) {
+        if !kind.allows_two_phase_borrow() {
             debug!("  -> {:?}", start_location);
             return;
         }

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -10,6 +10,7 @@ use rustc_hir::intravisit::Visitor;
 use rustc_hir::{self as hir, BindingMode, ByRef, Node};
 use rustc_middle::bug;
 use rustc_middle::hir::place::PlaceBase;
+use rustc_middle::mir::visit::PlaceContext;
 use rustc_middle::mir::{
     self, BindingForm, Local, LocalDecl, LocalInfo, LocalKind, Location, Mutability, Place,
     PlaceRef, ProjectionElem,
@@ -22,7 +23,6 @@ use rustc_trait_selection::traits;
 use tracing::debug;
 
 use crate::diagnostics::BorrowedContentSource;
-use crate::util::FindAssignments;
 use crate::{MirBorrowckCtxt, session_diagnostics};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
@@ -1084,6 +1084,38 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         }
     }
 
+    /// Finds all statements that assign directly to local (i.e., X = ...) and returns their
+    /// locations.
+    fn find_assignments(&self, local: Local) -> Vec<Location> {
+        use rustc_middle::mir::visit::Visitor;
+
+        struct FindLocalAssignmentVisitor {
+            needle: Local,
+            locations: Vec<Location>,
+        }
+
+        impl<'tcx> Visitor<'tcx> for FindLocalAssignmentVisitor {
+            fn visit_local(
+                &mut self,
+                local: Local,
+                place_context: PlaceContext,
+                location: Location,
+            ) {
+                if self.needle != local {
+                    return;
+                }
+
+                if place_context.is_place_assignment() {
+                    self.locations.push(location);
+                }
+            }
+        }
+
+        let mut visitor = FindLocalAssignmentVisitor { needle: local, locations: vec![] };
+        visitor.visit_body(self.body);
+        visitor.locations
+    }
+
     fn suggest_make_local_mut(&self, err: &mut Diag<'_>, local: Local, name: Symbol) {
         let local_decl = &self.body.local_decls[local];
 
@@ -1117,7 +1149,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             })) => {
                 // check if the RHS is from desugaring
                 let opt_assignment_rhs_span =
-                    self.body.find_assignments(local).first().map(|&location| {
+                    self.find_assignments(local).first().map(|&location| {
                         if let Some(mir::Statement {
                             source_info: _,
                             kind:

compiler/rustc_borrowck/src/lib.rs

@@ -17,7 +17,7 @@
 
 use std::cell::RefCell;
 use std::marker::PhantomData;
-use std::ops::Deref;
+use std::ops::{ControlFlow, Deref};
 
 use rustc_abi::FieldIdx;
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
@@ -81,7 +81,6 @@ mod session_diagnostics;
 mod type_check;
 mod universal_regions;
 mod used_muts;
-mod util;
 
 /// A public API provided for the Rust compiler consumers.
 pub mod consumers;
@@ -1054,31 +1053,31 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                         rw,
                         (borrow_index, borrow),
                     );
-                    Control::Continue
+                    ControlFlow::Continue(())
                 }
 
                 (Read(_), BorrowKind::Shared | BorrowKind::Fake(_))
                 | (
                     Read(ReadKind::Borrow(BorrowKind::Fake(FakeBorrowKind::Shallow))),
                     BorrowKind::Mut { .. },
-                ) => Control::Continue,
+                ) => ControlFlow::Continue(()),
 
                 (Reservation(_), BorrowKind::Fake(_) | BorrowKind::Shared) => {
                     // This used to be a future compatibility warning (to be
                     // disallowed on NLL). See rust-lang/rust#56254
-                    Control::Continue
+                    ControlFlow::Continue(())
                 }
 
                 (Write(WriteKind::Move), BorrowKind::Fake(FakeBorrowKind::Shallow)) => {
                     // Handled by initialization checks.
-                    Control::Continue
+                    ControlFlow::Continue(())
                 }
 
                 (Read(kind), BorrowKind::Mut { .. }) => {
                     // Reading from mere reservations of mutable-borrows is OK.
                     if !is_active(this.dominators(), borrow, location) {
-                        assert!(allow_two_phase_borrow(borrow.kind));
-                        return Control::Continue;
+                        assert!(borrow.kind.allows_two_phase_borrow());
+                        return ControlFlow::Continue(());
                     }
 
                     error_reported = true;
@@ -1094,7 +1093,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                             this.buffer_error(err);
                         }
                     }
-                    Control::Break
+                    ControlFlow::Break(())
                 }
 
                 (Reservation(kind) | Activation(kind, _) | Write(kind), _) => {
@@ -1141,7 +1140,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                             this.report_illegal_mutation_of_borrowed(location, place_span, borrow)
                         }
                     }
-                    Control::Break
+                    ControlFlow::Break(())
                 }
             },
         );
@@ -1185,7 +1184,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                     }
                     BorrowKind::Mut { .. } => {
                         let wk = WriteKind::MutableBorrow(bk);
-                        if allow_two_phase_borrow(bk) {
+                        if bk.allows_two_phase_borrow() {
                             (Deep, Reservation(wk))
                         } else {
                             (Deep, Write(wk))

compiler/rustc_borrowck/src/nll.rs

@@ -142,9 +142,9 @@ pub(crate) fn compute_regions<'a, 'tcx>(
 
     // If requested for `-Zpolonius=next`, convert NLL constraints to localized outlives
     // constraints.
-    let localized_outlives_constraints = polonius_context
-        .as_mut()
-        .map(|polonius_context| polonius_context.create_localized_constraints(&mut regioncx, body));
+    let localized_outlives_constraints = polonius_context.as_mut().map(|polonius_context| {
+        polonius_context.create_localized_constraints(infcx.tcx, &regioncx, body)
+    });
 
     // If requested: dump NLL facts, and run legacy polonius analysis.
     let polonius_output = all_facts.as_ref().and_then(|all_facts| {

compiler/rustc_borrowck/src/path_utils.rs

@@ -1,26 +1,14 @@
+use std::ops::ControlFlow;
+
 use rustc_abi::FieldIdx;
 use rustc_data_structures::graph::dominators::Dominators;
-use rustc_middle::mir::{BasicBlock, Body, BorrowKind, Location, Place, PlaceRef, ProjectionElem};
+use rustc_middle::mir::{BasicBlock, Body, Location, Place, PlaceRef, ProjectionElem};
 use rustc_middle::ty::TyCtxt;
 use tracing::debug;
 
 use crate::borrow_set::{BorrowData, BorrowSet, TwoPhaseActivation};
 use crate::{AccessDepth, BorrowIndex, places_conflict};
 
-/// Returns `true` if the borrow represented by `kind` is
-/// allowed to be split into separate Reservation and
-/// Activation phases.
-pub(super) fn allow_two_phase_borrow(kind: BorrowKind) -> bool {
-    kind.allows_two_phase_borrow()
-}
-
-/// Control for the path borrow checking code
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
-pub(super) enum Control {
-    Continue,
-    Break,
-}
-
 /// Encapsulates the idea of iterating over every borrow that involves a particular path
 pub(super) fn each_borrow_involving_path<'tcx, F, I, S>(
     s: &mut S,
@@ -31,7 +19,7 @@ pub(super) fn each_borrow_involving_path<'tcx, F, I, S>(
     is_candidate: I,
     mut op: F,
 ) where
-    F: FnMut(&mut S, BorrowIndex, &BorrowData<'tcx>) -> Control,
+    F: FnMut(&mut S, BorrowIndex, &BorrowData<'tcx>) -> ControlFlow<()>,
     I: Fn(BorrowIndex) -> bool,
 {
     let (access, place) = access_place;
@@ -62,7 +50,7 @@ pub(super) fn each_borrow_involving_path<'tcx, F, I, S>(
                 i, borrowed, place, access
             );
             let ctrl = op(s, i, borrowed);
-            if ctrl == Control::Break {
+            if matches!(ctrl, ControlFlow::Break(_)) {
                 return;
             }
         }

compiler/rustc_borrowck/src/polonius/legacy/loan_invalidations.rs

@@ -1,3 +1,5 @@
+use std::ops::ControlFlow;
+
 use rustc_data_structures::graph::dominators::Dominators;
 use rustc_middle::bug;
 use rustc_middle::mir::visit::Visitor;
@@ -260,7 +262,7 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {
                     }
                     BorrowKind::Mut { .. } => {
                         let wk = WriteKind::MutableBorrow(bk);
-                        if allow_two_phase_borrow(bk) {
+                        if bk.allows_two_phase_borrow() {
                             (Deep, Reservation(wk))
                         } else {
                             (Deep, Write(wk))
@@ -378,8 +380,8 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {
                         // Reading from mere reservations of mutable-borrows is OK.
                         if !is_active(this.dominators, borrow, location) {
                             // If the borrow isn't active yet, reads don't invalidate it
-                            assert!(allow_two_phase_borrow(borrow.kind));
-                            return Control::Continue;
+                            assert!(borrow.kind.allows_two_phase_borrow());
+                            return ControlFlow::Continue(());
                         }
 
                         // Unique and mutable borrows are invalidated by reads from any
@@ -395,7 +397,7 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {
                         this.emit_loan_invalidated_at(borrow_index, location);
                     }
                 }
-                Control::Continue
+                ControlFlow::Continue(())
             },
         );
     }

compiler/rustc_borrowck/src/polonius/mod.rs

@@ -37,21 +37,20 @@ mod constraints;
 mod dump;
 pub(crate) mod legacy;
 mod liveness_constraints;
+mod typeck_constraints;
 
 use std::collections::BTreeMap;
 
 use rustc_index::bit_set::SparseBitMatrix;
-use rustc_middle::mir::{Body, Location};
-use rustc_middle::ty::RegionVid;
+use rustc_middle::mir::Body;
+use rustc_middle::ty::{RegionVid, TyCtxt};
 use rustc_mir_dataflow::points::PointIndex;
 
 pub(crate) use self::constraints::*;
 pub(crate) use self::dump::dump_polonius_mir;
 use self::liveness_constraints::create_liveness_constraints;
+use self::typeck_constraints::convert_typeck_constraints;
 use crate::RegionInferenceContext;
-use crate::constraints::OutlivesConstraint;
-use crate::region_infer::values::LivenessValues;
-use crate::type_check::Locations;
 
 /// This struct holds the data needed to create the Polonius localized constraints.
 pub(crate) struct PoloniusContext {
@@ -88,14 +87,17 @@ impl PoloniusContext {
     /// - encoding liveness constraints
     pub(crate) fn create_localized_constraints<'tcx>(
         &self,
+        tcx: TyCtxt<'tcx>,
         regioncx: &RegionInferenceContext<'tcx>,
         body: &Body<'tcx>,
     ) -> LocalizedOutlivesConstraintSet {
         let mut localized_outlives_constraints = LocalizedOutlivesConstraintSet::default();
         convert_typeck_constraints(
+            tcx,
             body,
             regioncx.liveness_constraints(),
             regioncx.outlives_constraints(),
+            regioncx.universal_regions(),
             &mut localized_outlives_constraints,
         );
 
@@ -117,38 +119,3 @@ impl PoloniusContext {
         localized_outlives_constraints
     }
 }
-
-/// Propagate loans throughout the subset graph at a given point (with some subtleties around the
-/// location where effects start to be visible).
-fn convert_typeck_constraints<'tcx>(
-    body: &Body<'tcx>,
-    liveness: &LivenessValues,
-    outlives_constraints: impl Iterator<Item = OutlivesConstraint<'tcx>>,
-    localized_outlives_constraints: &mut LocalizedOutlivesConstraintSet,
-) {
-    for outlives_constraint in outlives_constraints {
-        match outlives_constraint.locations {
-            Locations::All(_) => {
-                // For now, turn logical constraints holding at all points into physical edges at
-                // every point in the graph.
-                // FIXME: encode this into *traversal* instead.
-                for (block, bb) in body.basic_blocks.iter_enumerated() {
-                    let statement_count = bb.statements.len();
-                    for statement_index in 0..=statement_count {
-                        let current_location = Location { block, statement_index };
-                        let current_point = liveness.point_from_location(current_location);
-
-                        localized_outlives_constraints.push(LocalizedOutlivesConstraint {
-                            source: outlives_constraint.sup,
-                            from: current_point,
-                            target: outlives_constraint.sub,
-                            to: current_point,
-                        });
-                    }
-                }
-            }
-
-            _ => {}
-        }
-    }
-}