extract polonius "constraint generation"
to help review, this duplicates the existing NLL + polonius constraint generation component, before splitting them up to only do what they individually need.
This commit is contained in:
Rémy Rakic
parent
49010833e9
commit
9f14698680
@ -157,6 +157,14 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
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body,
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borrow_set,
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);
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polonius::emit_cfg_and_loan_kills_facts(
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infcx,
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&mut liveness_constraints,
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&mut all_facts,
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location_table,
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body,
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borrow_set,
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);
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let mut regioncx = RegionInferenceContext::new(
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infcx,
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248
compiler/rustc_borrowck/src/polonius/constraint_generation.rs
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248
compiler/rustc_borrowck/src/polonius/constraint_generation.rs
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@ -0,0 +1,248 @@
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#![deny(rustc::untranslatable_diagnostic)]
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#![deny(rustc::diagnostic_outside_of_impl)]
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use rustc_infer::infer::InferCtxt;
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use rustc_middle::mir::visit::TyContext;
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use rustc_middle::mir::visit::Visitor;
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use rustc_middle::mir::{
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Body, Local, Location, Place, PlaceRef, ProjectionElem, Rvalue, SourceInfo, Statement,
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StatementKind, Terminator, TerminatorKind, UserTypeProjection,
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};
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use rustc_middle::ty::visit::TypeVisitable;
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use rustc_middle::ty::GenericArgsRef;
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use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt};
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use crate::{
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borrow_set::BorrowSet, facts::AllFacts, location::LocationTable, places_conflict,
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region_infer::values::LivenessValues,
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};
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pub(super) fn generate_constraints<'tcx>(
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infcx: &InferCtxt<'tcx>,
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liveness_constraints: &mut LivenessValues<RegionVid>,
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all_facts: &mut Option<AllFacts>,
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location_table: &LocationTable,
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body: &Body<'tcx>,
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borrow_set: &BorrowSet<'tcx>,
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) {
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let mut cg = ConstraintGeneration {
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borrow_set,
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infcx,
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liveness_constraints,
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location_table,
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all_facts,
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body,
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};
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for (bb, data) in body.basic_blocks.iter_enumerated() {
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cg.visit_basic_block_data(bb, data);
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}
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}
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/// 'cg = the duration of the constraint generation process itself.
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struct ConstraintGeneration<'cg, 'tcx> {
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infcx: &'cg InferCtxt<'tcx>,
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all_facts: &'cg mut Option<AllFacts>,
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location_table: &'cg LocationTable,
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liveness_constraints: &'cg mut LivenessValues<RegionVid>,
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borrow_set: &'cg BorrowSet<'tcx>,
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body: &'cg Body<'tcx>,
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}
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impl<'cg, 'tcx> Visitor<'tcx> for ConstraintGeneration<'cg, 'tcx> {
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/// We sometimes have `args` within an rvalue, or within a
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/// call. Make them live at the location where they appear.
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fn visit_args(&mut self, args: &GenericArgsRef<'tcx>, location: Location) {
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self.add_regular_live_constraint(*args, location);
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self.super_args(args);
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}
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/// We sometimes have `region` within an rvalue, or within a
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/// call. Make them live at the location where they appear.
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fn visit_region(&mut self, region: ty::Region<'tcx>, location: Location) {
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self.add_regular_live_constraint(region, location);
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self.super_region(region);
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}
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/// We sometimes have `ty` within an rvalue, or within a
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/// call. Make them live at the location where they appear.
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fn visit_ty(&mut self, ty: Ty<'tcx>, ty_context: TyContext) {
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match ty_context {
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TyContext::ReturnTy(SourceInfo { span, .. })
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| TyContext::YieldTy(SourceInfo { span, .. })
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| TyContext::UserTy(span)
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| TyContext::LocalDecl { source_info: SourceInfo { span, .. }, .. } => {
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span_bug!(span, "should not be visiting outside of the CFG: {:?}", ty_context);
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}
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TyContext::Location(location) => {
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self.add_regular_live_constraint(ty, location);
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}
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}
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self.super_ty(ty);
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}
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fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
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if let Some(all_facts) = self.all_facts {
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let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation");
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all_facts.cfg_edge.push((
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self.location_table.start_index(location),
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self.location_table.mid_index(location),
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));
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all_facts.cfg_edge.push((
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self.location_table.mid_index(location),
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self.location_table.start_index(location.successor_within_block()),
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));
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// If there are borrows on this now dead local, we need to record them as `killed`.
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if let StatementKind::StorageDead(local) = statement.kind {
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record_killed_borrows_for_local(
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all_facts,
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self.borrow_set,
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self.location_table,
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local,
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location,
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);
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}
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}
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self.super_statement(statement, location);
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}
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fn visit_assign(&mut self, place: &Place<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) {
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// When we see `X = ...`, then kill borrows of
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// `(*X).foo` and so forth.
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self.record_killed_borrows_for_place(*place, location);
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self.super_assign(place, rvalue, location);
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}
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fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
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if let Some(all_facts) = self.all_facts {
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let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation");
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all_facts.cfg_edge.push((
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self.location_table.start_index(location),
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self.location_table.mid_index(location),
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));
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let successor_blocks = terminator.successors();
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all_facts.cfg_edge.reserve(successor_blocks.size_hint().0);
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for successor_block in successor_blocks {
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all_facts.cfg_edge.push((
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self.location_table.mid_index(location),
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self.location_table.start_index(successor_block.start_location()),
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));
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}
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}
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// A `Call` terminator's return value can be a local which has borrows,
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// so we need to record those as `killed` as well.
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if let TerminatorKind::Call { destination, .. } = terminator.kind {
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self.record_killed_borrows_for_place(destination, location);
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}
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self.super_terminator(terminator, location);
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}
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fn visit_ascribe_user_ty(
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&mut self,
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_place: &Place<'tcx>,
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_variance: ty::Variance,
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_user_ty: &UserTypeProjection,
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_location: Location,
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) {
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}
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}
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impl<'cx, 'tcx> ConstraintGeneration<'cx, 'tcx> {
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/// Some variable with type `live_ty` is "regular live" at
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/// `location` -- i.e., it may be used later. This means that all
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/// regions appearing in the type `live_ty` must be live at
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/// `location`.
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fn add_regular_live_constraint<T>(&mut self, live_ty: T, location: Location)
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where
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T: TypeVisitable<TyCtxt<'tcx>>,
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{
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debug!("add_regular_live_constraint(live_ty={:?}, location={:?})", live_ty, location);
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self.infcx.tcx.for_each_free_region(&live_ty, |live_region| {
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let vid = live_region.as_var();
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self.liveness_constraints.add_element(vid, location);
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});
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}
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/// When recording facts for Polonius, records the borrows on the specified place
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/// as `killed`. For example, when assigning to a local, or on a call's return destination.
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fn record_killed_borrows_for_place(&mut self, place: Place<'tcx>, location: Location) {
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if let Some(all_facts) = self.all_facts {
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let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation");
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// Depending on the `Place` we're killing:
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// - if it's a local, or a single deref of a local,
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// we kill all the borrows on the local.
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// - if it's a deeper projection, we have to filter which
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// of the borrows are killed: the ones whose `borrowed_place`
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// conflicts with the `place`.
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match place.as_ref() {
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PlaceRef { local, projection: &[] }
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| PlaceRef { local, projection: &[ProjectionElem::Deref] } => {
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debug!(
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"Recording `killed` facts for borrows of local={:?} at location={:?}",
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local, location
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);
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record_killed_borrows_for_local(
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all_facts,
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self.borrow_set,
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self.location_table,
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local,
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location,
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);
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}
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PlaceRef { local, projection: &[.., _] } => {
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// Kill conflicting borrows of the innermost local.
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debug!(
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"Recording `killed` facts for borrows of \
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innermost projected local={:?} at location={:?}",
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local, location
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);
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if let Some(borrow_indices) = self.borrow_set.local_map.get(&local) {
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for &borrow_index in borrow_indices {
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let places_conflict = places_conflict::places_conflict(
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self.infcx.tcx,
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self.body,
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self.borrow_set[borrow_index].borrowed_place,
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place,
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places_conflict::PlaceConflictBias::NoOverlap,
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);
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if places_conflict {
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let location_index = self.location_table.mid_index(location);
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all_facts.loan_killed_at.push((borrow_index, location_index));
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}
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}
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}
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}
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}
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}
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}
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}
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/// When recording facts for Polonius, records the borrows on the specified local as `killed`.
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fn record_killed_borrows_for_local(
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all_facts: &mut AllFacts,
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borrow_set: &BorrowSet<'_>,
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location_table: &LocationTable,
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local: Local,
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location: Location,
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) {
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if let Some(borrow_indices) = borrow_set.local_map.get(&local) {
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all_facts.loan_killed_at.reserve(borrow_indices.len());
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for &borrow_index in borrow_indices {
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let location_index = location_table.mid_index(location);
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all_facts.loan_killed_at.push((borrow_index, location_index));
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}
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}
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}
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@ -3,16 +3,19 @@
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//! Will be removed in the future, once the in-tree `-Zpolonius=next` implementation reaches feature
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//! parity.
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use rustc_infer::infer::InferCtxt;
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use rustc_middle::mir::{Body, LocalKind, Location, START_BLOCK};
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use rustc_middle::ty::TyCtxt;
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use rustc_middle::ty::{RegionVid, TyCtxt};
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use rustc_mir_dataflow::move_paths::{InitKind, InitLocation, MoveData};
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use crate::borrow_set::BorrowSet;
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use crate::facts::AllFacts;
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use crate::location::LocationTable;
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use crate::region_infer::values::LivenessValues;
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use crate::type_check::free_region_relations::UniversalRegionRelations;
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use crate::universal_regions::UniversalRegions;
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mod constraint_generation;
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mod invalidation;
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/// Emit facts needed for move/init analysis: moves and assignments.
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@ -130,7 +133,7 @@ pub(crate) fn emit_universal_region_facts(
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}
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}
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/// Emit facts about loan invalidations
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/// Emit facts about loan invalidations.
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pub(crate) fn emit_loan_invalidations_facts<'tcx>(
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tcx: TyCtxt<'tcx>,
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all_facts: &mut Option<AllFacts>,
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@ -145,3 +148,22 @@ pub(crate) fn emit_loan_invalidations_facts<'tcx>(
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invalidation::emit_loan_invalidations(tcx, all_facts, location_table, body, borrow_set);
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}
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/// Emit facts about CFG points and edges, as well as locations where loans are killed.
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pub(crate) fn emit_cfg_and_loan_kills_facts<'tcx>(
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infcx: &InferCtxt<'tcx>,
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liveness_constraints: &mut LivenessValues<RegionVid>,
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all_facts: &mut Option<AllFacts>,
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location_table: &LocationTable,
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body: &Body<'tcx>,
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borrow_set: &BorrowSet<'tcx>,
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) {
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constraint_generation::generate_constraints(
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infcx,
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liveness_constraints,
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all_facts,
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location_table,
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body,
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borrow_set,
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);
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}
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