Extend Polonius fact generation for (some) move tracking

Cargo.lock

@@ -2324,9 +2324,9 @@ checksum = "676e8eb2b1b4c9043511a9b7bea0915320d7e502b0a079fb03f9635a5252b18c"
 
 [[package]]
 name = "polonius-engine"
-version = "0.9.0"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f6b8a5defa2aef9ba4999aaa745fbc01c622ecea35964a306adc3e44be4f3b5b"
+checksum = "50fa9dbfd0d3d60594da338cfe6f94028433eecae4b11b7e83fd99759227bbfe"
 dependencies = [
  "datafrog",
  "log",

src/librustc/Cargo.toml

@@ -21,7 +21,7 @@ scoped-tls = "1.0"
 log = { version = "0.4", features = ["release_max_level_info", "std"] }
 rustc-rayon = "0.2.0"
 rustc-rayon-core = "0.2.0"
-polonius-engine  = "0.9.0"
+polonius-engine  = "0.10.0"
 rustc_apfloat = { path = "../librustc_apfloat" }
 rustc_target = { path = "../librustc_target" }
 rustc_macros = { path = "../librustc_macros" }

src/librustc_mir/Cargo.toml

@@ -15,7 +15,7 @@ either = "1.5.0"
 dot = { path = "../libgraphviz", package = "graphviz" }
 log = "0.4"
 log_settings = "0.1.1"
-polonius-engine  = "0.9.0"
+polonius-engine  = "0.10.0"
 rustc = { path = "../librustc" }
 rustc_target = { path = "../librustc_target" }
 rustc_data_structures = { path = "../librustc_data_structures" }

src/librustc_mir/borrow_check/flows.rs

@@ -12,7 +12,7 @@ use crate::borrow_check::location::LocationIndex;
 use polonius_engine::Output;
 
 use crate::dataflow::indexes::BorrowIndex;
-use crate::dataflow::move_paths::HasMoveData;
+use crate::dataflow::move_paths::{HasMoveData, MovePathIndex};
 use crate::dataflow::Borrows;
 use crate::dataflow::EverInitializedPlaces;
 use crate::dataflow::MaybeUninitializedPlaces;
@@ -21,7 +21,7 @@ use either::Either;
 use std::fmt;
 use std::rc::Rc;
 
-crate type PoloniusOutput = Output<RegionVid, BorrowIndex, LocationIndex, Local>;
+crate type PoloniusOutput = Output<RegionVid, BorrowIndex, LocationIndex, Local, MovePathIndex>;
 
 // (forced to be `pub` due to its use as an associated type below.)
 crate struct Flows<'b, 'tcx> {

src/librustc_mir/borrow_check/nll/facts.rs

@@ -1,5 +1,5 @@
 use crate::borrow_check::location::{LocationIndex, LocationTable};
-use crate::dataflow::indexes::BorrowIndex;
+use crate::dataflow::indexes::{BorrowIndex, MovePathIndex};
 use polonius_engine::AllFacts as PoloniusAllFacts;
 use polonius_engine::Atom;
 use rustc::mir::Local;
@@ -11,7 +11,7 @@ use std::fs::{self, File};
 use std::io::Write;
 use std::path::Path;
 
-crate type AllFacts = PoloniusAllFacts<RegionVid, BorrowIndex, LocationIndex, Local>;
+crate type AllFacts = PoloniusAllFacts<RegionVid, BorrowIndex, LocationIndex, Local, MovePathIndex>;
 
 crate trait AllFactsExt {
     /// Returns `true` if there is a need to gather `AllFacts` given the
@@ -65,7 +65,11 @@ impl AllFactsExt for AllFacts {
                 var_drop_used,
                 var_uses_region,
                 var_drops_region,
-                var_initialized_on_exit,
+                var_maybe_initialized_on_exit,
+                parent,
+                var_starts_path,
+                initialized_at,
+                moved_out_at,
             ])
         }
         Ok(())
@@ -84,6 +88,12 @@ impl Atom for LocationIndex {
     }
 }
 
+impl Atom for MovePathIndex {
+    fn index(self) -> usize {
+        Idx::index(self)
+    }
+}
+
 struct FactWriter<'w> {
     location_table: &'w LocationTable,
     dir: &'w Path,

src/librustc_mir/borrow_check/nll/mod.rs

@@ -4,14 +4,14 @@ use crate::borrow_check::nll::facts::AllFactsExt;
 use crate::borrow_check::nll::type_check::{MirTypeckResults, MirTypeckRegionConstraints};
 use crate::borrow_check::nll::region_infer::values::RegionValueElements;
 use crate::dataflow::indexes::BorrowIndex;
-use crate::dataflow::move_paths::MoveData;
+use crate::dataflow::move_paths::{InitLocation, MoveData, MovePathIndex, InitKind};
 use crate::dataflow::FlowAtLocation;
 use crate::dataflow::MaybeInitializedPlaces;
 use crate::transform::MirSource;
 use crate::borrow_check::Upvar;
 use rustc::hir::def_id::DefId;
 use rustc::infer::InferCtxt;
-use rustc::mir::{ClosureOutlivesSubject, ClosureRegionRequirements, Local, Body, Promoted};
+use rustc::mir::{ClosureOutlivesSubject, ClosureRegionRequirements, Local, Location, Body, LocalKind, BasicBlock, Promoted};
 use rustc::ty::{self, RegionKind, RegionVid};
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc_errors::Diagnostic;
@@ -69,6 +69,61 @@ pub(in crate::borrow_check) fn replace_regions_in_mir<'cx, 'tcx>(
     universal_regions
 }
 
+
+// This function populates an AllFacts instance with base facts related to
+// MovePaths and needed for the move analysis.
+fn populate_polonius_move_facts(all_facts: &mut AllFacts, move_data: &MoveData<'_>, location_table: &LocationTable, body: &Body<'_>) {
+    all_facts.var_starts_path.extend(move_data.rev_lookup.iter_locals_enumerated().map(|(v, &m)| (v, m)));
+
+    for (idx, move_path) in move_data.move_paths.iter_enumerated() {
+        all_facts.parent.extend(move_path.parents(&move_data.move_paths).iter().map(|&parent| (parent, idx)));
+    }
+
+    // initialized_at
+    for init in move_data.inits.iter() {
+
+        match init.location {
+            InitLocation::Statement(location) => {
+                let block_data = &body[location.block];
+                let is_terminator = location.statement_index == block_data.statements.len();
+
+                if is_terminator && init.kind == InitKind::NonPanicPathOnly {
+                    // We are at the terminator of an init that has a panic path,
+                    // and where the init should not happen on panic
+
+                    for &successor in block_data.terminator().successors() {
+                        if body[successor].is_cleanup {
+                            continue;
+                        }
+
+                        // The initialization happened in (or rather, when arriving at)
+                        // the successors, but not in the unwind block.
+                        let first_statement = Location { block: successor, statement_index: 0};
+                        all_facts.initialized_at.push((init.path, location_table.start_index(first_statement)));
+                    }
+
+                } else {
+                    // In all other cases, the initialization just happens at the
+                    // midpoint, like any other effect.
+                    all_facts.initialized_at.push((init.path, location_table.mid_index(location)));
+                }
+            },
+            // Arguments are initialized on function entry
+            InitLocation::Argument(local) => {
+                assert!(body.local_kind(local) == LocalKind::Arg);
+                let fn_entry = Location {block: BasicBlock::from_u32(0u32), statement_index: 0 };
+                all_facts.initialized_at.push((init.path, location_table.start_index(fn_entry)));
+
+            }
+        }
+    }
+
+
+    // moved_out_at
+    // deinitialisation is assumed to always happen!
+    all_facts.moved_out_at.extend(move_data.moves.iter().map(|mo| (mo.path, location_table.mid_index(mo.source))));
+}
+
 /// Computes the (non-lexical) regions from the input MIR.
 ///
 /// This may result in errors being reported.
@@ -87,7 +142,7 @@ pub(in crate::borrow_check) fn compute_regions<'cx, 'tcx>(
     errors_buffer: &mut Vec<Diagnostic>,
 ) -> (
     RegionInferenceContext<'tcx>,
-    Option<Rc<Output<RegionVid, BorrowIndex, LocationIndex, Local>>>,
+    Option<Rc<Output<RegionVid, BorrowIndex, LocationIndex, Local, MovePathIndex>>>,
     Option<ClosureRegionRequirements<'tcx>>,
 ) {
     let mut all_facts = if AllFacts::enabled(infcx.tcx) {
@@ -123,6 +178,7 @@ pub(in crate::borrow_check) fn compute_regions<'cx, 'tcx>(
         all_facts
             .universal_region
             .extend(universal_regions.universal_regions());
+        populate_polonius_move_facts(all_facts, move_data, location_table, body);
     }
 
     // Create the region inference context, taking ownership of the

src/librustc_mir/borrow_check/nll/type_check/liveness/polonius.rs

@@ -13,6 +13,7 @@ struct LivenessPointFactsExtractor<'me> {
     var_defined: &'me mut VarPointRelations,
     var_used: &'me mut VarPointRelations,
     location_table: &'me LocationTable,
+    var_drop_used: &'me mut VarPointRelations,
 }
 
 // A Visitor to walk through the MIR and extract point-wise facts
@@ -30,15 +31,20 @@ impl LivenessPointFactsExtractor<'_> {
         debug!("LivenessFactsExtractor::insert_use()");
         self.var_used.push((local, self.location_to_index(location)));
     }
+
+    fn insert_drop_use(&mut self, local: Local, location: Location) {
+        debug!("LivenessFactsExtractor::insert_drop_use()");
+        self.var_drop_used.push((local, self.location_to_index(location)));
+    }
 }
 
 impl Visitor<'tcx> for LivenessPointFactsExtractor<'_> {
     fn visit_local(&mut self, &local: &Local, context: PlaceContext, location: Location) {
         match 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),
             _ => (),
-            // NOTE: Drop handling is now done in trace()
         }
     }
 }
@@ -65,6 +71,7 @@ pub(super) fn populate_var_liveness_facts(
         LivenessPointFactsExtractor {
             var_defined: &mut facts.var_defined,
             var_used: &mut facts.var_used,
+            var_drop_used: &mut facts.var_drop_used,
             location_table,
         }
         .visit_body(mir);

src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs

@@ -134,7 +134,7 @@ impl LivenessResults<'me, 'typeck, 'flow, 'tcx> {
 
             // FIXME: this is temporary until we can generate our own initialization
             if self.cx.typeck.borrowck_context.all_facts.is_some() {
-                self.add_polonius_var_initialized_on_exit_for(local)
+                self.add_polonius_var_maybe_initialized_on_exit_for(local)
             }
 
             self.compute_use_live_points_for(local);
@@ -161,14 +161,14 @@ impl LivenessResults<'me, 'typeck, 'flow, 'tcx> {
     //
     // FIXME: this analysis (the initialization tracking) should be
     // done in Polonius, but isn't yet.
-    fn add_polonius_var_initialized_on_exit_for(&mut self, local: Local) {
+    fn add_polonius_var_maybe_initialized_on_exit_for(&mut self, local: Local) {
         let move_path = self.cx.move_data.rev_lookup.find_local(local);
         let facts = self.cx.typeck.borrowck_context.all_facts.as_mut().unwrap();
         for block in self.cx.body.basic_blocks().indices() {
             debug!("polonius: generating initialization facts for {:?} in {:?}", local, block);
 
             // iterate through the block, applying the effects of each statement
-            // up to and including location, and populate `var_initialized_on_exit`
+            // up to and including location, and populate `var_maybe_initialized_on_exit`
             self.cx.flow_inits.reset_to_entry_of(block);
             let start_location = Location { block, statement_index: 0 };
             self.cx.flow_inits.apply_local_effect(start_location);
@@ -181,7 +181,7 @@ impl LivenessResults<'me, 'typeck, 'flow, 'tcx> {
                 // statement has not yet taken effect:
                 if self.cx.flow_inits.has_any_child_of(move_path).is_some() {
                     facts
-                        .var_initialized_on_exit
+                        .var_maybe_initialized_on_exit
                         .push((local, self.cx.location_table.start_index(current_location)));
                 }
 
@@ -190,7 +190,7 @@ impl LivenessResults<'me, 'typeck, 'flow, 'tcx> {
 
                 if self.cx.flow_inits.has_any_child_of(move_path).is_some() {
                     facts
-                        .var_initialized_on_exit
+                        .var_maybe_initialized_on_exit
                         .push((local, self.cx.location_table.mid_index(current_location)));
                 }
             }
@@ -199,7 +199,7 @@ impl LivenessResults<'me, 'typeck, 'flow, 'tcx> {
 
             if self.cx.flow_inits.has_any_child_of(move_path).is_some() {
                 facts
-                    .var_initialized_on_exit
+                    .var_maybe_initialized_on_exit
                     .push((local, self.cx.location_table.start_index(terminator_location)));
             }
 
@@ -208,7 +208,7 @@ impl LivenessResults<'me, 'typeck, 'flow, 'tcx> {
 
             if self.cx.flow_inits.has_any_child_of(move_path).is_some() {
                 facts
-                    .var_initialized_on_exit
+                    .var_maybe_initialized_on_exit
                     .push((local, self.cx.location_table.mid_index(terminator_location)));
             }
         }
@@ -273,11 +273,6 @@ impl LivenessResults<'me, 'typeck, 'flow, 'tcx> {
             debug_assert_eq!(self.cx.body.terminator_loc(location.block), location,);
 
             if self.cx.initialized_at_terminator(location.block, mpi) {
-                // FIXME: this analysis (the initialization tracking) should be
-                // done in Polonius, but isn't yet.
-                if let Some(facts) = self.cx.typeck.borrowck_context.all_facts {
-                    facts.var_drop_used.push((local, self.cx.location_table.mid_index(location)));
-                }
                 if self.drop_live_at.insert(drop_point) {
                     self.drop_locations.push(location);
                     self.stack.push(drop_point);

src/librustc_mir/dataflow/move_paths/mod.rs

@@ -1,9 +1,10 @@
 use rustc::ty::{Ty, TyCtxt};
 use rustc::mir::*;
 use rustc::util::nodemap::FxHashMap;
-use rustc_data_structures::indexed_vec::{Idx, IndexVec};
+use rustc_data_structures::indexed_vec::{Idx, IndexVec, Enumerated};
 use smallvec::SmallVec;
 use syntax_pos::{Span};
+use core::slice::Iter;
 
 use std::fmt;
 use std::ops::{Index, IndexMut};
@@ -262,6 +263,12 @@ impl MovePathLookup {
     pub fn find_local(&self, local: Local) -> MovePathIndex {
         self.locals[local]
     }
+
+    /// An enumerated iterator of `local`s and their associated
+    /// `MovePathIndex`es.
+    pub fn iter_locals_enumerated(&self) -> Enumerated<Local, Iter<'_, MovePathIndex>> {
+        self.locals.iter_enumerated()
+    }
 }
 
 #[derive(Debug)]