Auto merge of #62800 - albins:polonius-initialization-1, r=nikomatsakis

Extend Polonius fact generation for (some) move tracking

This PR will extend rustc to emit facts used for tracking moves and initialization in Polonius. It is most likely the final part of my master's thesis work.

Author: bors

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
@@ -58,14 +58,17 @@ impl AllFactsExt for AllFacts {
                 cfg_edge,
                 killed,
                 outlives,
-                region_live_at,
                 invalidates,
                 var_used,
                 var_defined,
                 var_drop_used,
                 var_uses_region,
                 var_drops_region,
-                var_initialized_on_exit,
+                child,
+                path_belongs_to_var,
+                initialized_at,
+                moved_out_at,
+                path_accessed_at,
             ])
         }
         Ok(())
@@ -84,6 +87,12 @@ 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 +4,15 @@ 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 +70,85 @@ 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
+        .path_belongs_to_var
+        .extend(
+            move_data
+                .rev_lookup
+                .iter_locals_enumerated()
+                .map(|(v, &m)| (m, v)));
+
+    for (child, move_path) in move_data.move_paths.iter_enumerated() {
+        all_facts
+            .child
+            .extend(
+                move_path
+                    .parents(&move_data.move_paths)
+                    .iter()
+                    .map(|&parent| (child, parent)));
+    }
+
+    // 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 +167,7 @@ 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 +203,7 @@ 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/local_use_map.rs

@@ -1,7 +1,7 @@
 use crate::borrow_check::nll::region_infer::values::{PointIndex, RegionValueElements};
 use crate::util::liveness::{categorize, DefUse};
 use rustc::mir::visit::{PlaceContext, Visitor};
-use rustc::mir::{Local, Location, Body};
+use rustc::mir::{Body, Local, Location};
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 use rustc_data_structures::vec_linked_list as vll;
 
@@ -72,16 +72,10 @@ impl LocalUseMap {
 
         let mut locals_with_use_data: IndexVec<Local, bool> =
             IndexVec::from_elem_n(false, body.local_decls.len());
-        live_locals
-            .iter()
-            .for_each(|&local| locals_with_use_data[local] = true);
-
-        LocalUseMapBuild {
-            local_use_map: &mut local_use_map,
-            elements,
-            locals_with_use_data,
-        }
-        .visit_body(body);
+        live_locals.iter().for_each(|&local| locals_with_use_data[local] = true);
+
+        LocalUseMapBuild { local_use_map: &mut local_use_map, elements, locals_with_use_data }
+            .visit_body(body);
 
         local_use_map
     }
@@ -151,10 +145,8 @@ impl LocalUseMapBuild<'_> {
         location: Location,
     ) {
         let point_index = elements.point_from_location(location);
-        let appearance_index = appearances.push(Appearance {
-            point_index,
-            next: *first_appearance,
-        });
+        let appearance_index =
+            appearances.push(Appearance { point_index, next: *first_appearance });
         *first_appearance = Some(appearance_index);
     }
 }

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

@@ -58,9 +58,9 @@ pub(super) fn generate<'tcx>(
     };
 
     if !live_locals.is_empty() {
-        trace::trace(typeck, body, elements, flow_inits, move_data, live_locals, location_table);
+        trace::trace(typeck, body, elements, flow_inits, move_data, live_locals);
 
-        polonius::populate_var_liveness_facts(typeck, body, location_table);
+        polonius::populate_access_facts(typeck, body, location_table, move_data);
     }
 }
 

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

@@ -1,22 +1,28 @@
 use crate::borrow_check::location::{LocationIndex, LocationTable};
+use crate::dataflow::indexes::MovePathIndex;
+use crate::dataflow::move_paths::{LookupResult, MoveData};
 use crate::util::liveness::{categorize, DefUse};
-use rustc::mir::visit::{PlaceContext, Visitor};
-use rustc::mir::{Body, Local, Location};
+use rustc::mir::visit::{MutatingUseContext, PlaceContext, Visitor};
+use rustc::mir::{Body, Local, Location, Place};
 use rustc::ty::subst::Kind;
 use rustc::ty::Ty;
 
 use super::TypeChecker;
 
 type VarPointRelations = Vec<(Local, LocationIndex)>;
+type MovePathPointRelations = Vec<(MovePathIndex, LocationIndex)>;
 
-struct LivenessPointFactsExtractor<'me> {
+struct UseFactsExtractor<'me> {
     var_defined: &'me mut VarPointRelations,
     var_used: &'me mut VarPointRelations,
     location_table: &'me LocationTable,
+    var_drop_used: &'me mut VarPointRelations,
+    move_data: &'me MoveData<'me>,
+    path_accessed_at: &'me mut MovePathPointRelations,
 }
 
 // A Visitor to walk through the MIR and extract point-wise facts
-impl LivenessPointFactsExtractor<'_> {
+impl UseFactsExtractor<'_> {
     fn location_to_index(&self, location: Location) -> LocationIndex {
         self.location_table.mid_index(location)
     }
@@ -30,15 +36,50 @@ 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)));
+    }
+
+    fn insert_path_access(&mut self, path: MovePathIndex, location: Location) {
+        debug!("LivenessFactsExtractor::insert_path_access({:?}, {:?})", path, location);
+        self.path_accessed_at.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 Visitor<'tcx> for LivenessPointFactsExtractor<'_> {
+impl Visitor<'tcx> for UseFactsExtractor<'_> {
     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),
+            _ => (),
+        }
+    }
+
+    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);
+                }
+            }
             _ => (),
-            // NOTE: Drop handling is now done in trace()
         }
     }
 }
@@ -54,23 +95,27 @@ fn add_var_uses_regions(typeck: &mut TypeChecker<'_, 'tcx>, local: Local, ty: Ty
     });
 }
 
-pub(super) fn populate_var_liveness_facts(
+pub(super) fn populate_access_facts(
     typeck: &mut TypeChecker<'_, 'tcx>,
-    mir: &Body<'tcx>,
+    body: &Body<'tcx>,
     location_table: &LocationTable,
+    move_data: &MoveData<'_>,
 ) {
     debug!("populate_var_liveness_facts()");
 
     if let Some(facts) = typeck.borrowck_context.all_facts.as_mut() {
-        LivenessPointFactsExtractor {
+        UseFactsExtractor {
             var_defined: &mut facts.var_defined,
             var_used: &mut facts.var_used,
+            var_drop_used: &mut facts.var_drop_used,
+            path_accessed_at: &mut facts.path_accessed_at,
             location_table,
+            move_data,
         }
-        .visit_body(mir);
+        .visit_body(body);
     }
 
-    for (local, local_decl) in mir.local_decls.iter_enumerated() {
+    for (local, local_decl) in body.local_decls.iter_enumerated() {
         add_var_uses_regions(typeck, local, local_decl.ty);
     }
 }