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use rustc_infer::infer::InferCtxt;
use rustc_middle::mir::visit::TyContext;
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::{
BasicBlock, BasicBlockData, Body, Local, Location, Place, PlaceRef, ProjectionElem, Rvalue,
SourceInfo, Statement, StatementKind, Terminator, TerminatorKind, UserTypeProjection,
};
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::visit::TypeVisitable;
use rustc_middle::ty::{self, RegionVid, Ty};
use crate::{
borrow_set::BorrowSet, facts::AllFacts, location::LocationTable, nll::ToRegionVid,
places_conflict, region_infer::values::LivenessValues,
};
pub(super) fn generate_constraints<'cx, 'tcx>(
infcx: &InferCtxt<'cx, 'tcx>,
liveness_constraints: &mut LivenessValues<RegionVid>,
all_facts: &mut Option<AllFacts>,
location_table: &LocationTable,
body: &Body<'tcx>,
borrow_set: &BorrowSet<'tcx>,
) {
let mut cg = ConstraintGeneration {
borrow_set,
infcx,
liveness_constraints,
location_table,
all_facts,
body,
};
for (bb, data) in body.basic_blocks.iter_enumerated() {
cg.visit_basic_block_data(bb, data);
}
}
struct ConstraintGeneration<'cg, 'cx, 'tcx> {
infcx: &'cg InferCtxt<'cx, 'tcx>,
all_facts: &'cg mut Option<AllFacts>,
location_table: &'cg LocationTable,
liveness_constraints: &'cg mut LivenessValues<RegionVid>,
borrow_set: &'cg BorrowSet<'tcx>,
body: &'cg Body<'tcx>,
}
impl<'cg, 'cx, 'tcx> Visitor<'tcx> for ConstraintGeneration<'cg, 'cx, 'tcx> {
fn visit_basic_block_data(&mut self, bb: BasicBlock, data: &BasicBlockData<'tcx>) {
self.super_basic_block_data(bb, data);
}
fn visit_substs(&mut self, substs: &SubstsRef<'tcx>, location: Location) {
self.add_regular_live_constraint(*substs, location);
self.super_substs(substs);
}
fn visit_region(&mut self, region: ty::Region<'tcx>, location: Location) {
self.add_regular_live_constraint(region, location);
self.super_region(region);
}
fn visit_ty(&mut self, ty: Ty<'tcx>, ty_context: TyContext) {
match ty_context {
TyContext::ReturnTy(SourceInfo { span, .. })
| TyContext::YieldTy(SourceInfo { span, .. })
| TyContext::UserTy(span)
| TyContext::LocalDecl { source_info: SourceInfo { span, .. }, .. } => {
span_bug!(span, "should not be visiting outside of the CFG: {:?}", ty_context);
}
TyContext::Location(location) => {
self.add_regular_live_constraint(ty, location);
}
}
self.super_ty(ty);
}
fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
if let Some(all_facts) = self.all_facts {
let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation");
all_facts.cfg_edge.push((
self.location_table.start_index(location),
self.location_table.mid_index(location),
));
all_facts.cfg_edge.push((
self.location_table.mid_index(location),
self.location_table.start_index(location.successor_within_block()),
));
if let StatementKind::StorageDead(local) = statement.kind {
record_killed_borrows_for_local(
all_facts,
self.borrow_set,
self.location_table,
local,
location,
);
}
}
self.super_statement(statement, location);
}
fn visit_assign(&mut self, place: &Place<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) {
self.record_killed_borrows_for_place(*place, location);
self.super_assign(place, rvalue, location);
}
fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
if let Some(all_facts) = self.all_facts {
let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation");
all_facts.cfg_edge.push((
self.location_table.start_index(location),
self.location_table.mid_index(location),
));
let successor_blocks = terminator.successors();
all_facts.cfg_edge.reserve(successor_blocks.size_hint().0);
for successor_block in successor_blocks {
all_facts.cfg_edge.push((
self.location_table.mid_index(location),
self.location_table.start_index(successor_block.start_location()),
));
}
}
if let TerminatorKind::Call { destination, .. } = terminator.kind {
self.record_killed_borrows_for_place(destination, location);
}
self.super_terminator(terminator, location);
}
fn visit_ascribe_user_ty(
&mut self,
_place: &Place<'tcx>,
_variance: ty::Variance,
_user_ty: &UserTypeProjection,
_location: Location,
) {
}
}
impl<'cx, 'cg, 'tcx> ConstraintGeneration<'cx, 'cg, 'tcx> {
fn add_regular_live_constraint<T>(&mut self, live_ty: T, location: Location)
where
T: TypeVisitable<'tcx>,
{
debug!("add_regular_live_constraint(live_ty={:?}, location={:?})", live_ty, location);
self.infcx.tcx.for_each_free_region(&live_ty, |live_region| {
let vid = live_region.to_region_vid();
self.liveness_constraints.add_element(vid, location);
});
}
fn record_killed_borrows_for_place(&mut self, place: Place<'tcx>, location: Location) {
if let Some(all_facts) = self.all_facts {
let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation");
match place.as_ref() {
PlaceRef { local, projection: &[] }
| PlaceRef { local, projection: &[ProjectionElem::Deref] } => {
debug!(
"Recording `killed` facts for borrows of local={:?} at location={:?}",
local, location
);
record_killed_borrows_for_local(
all_facts,
self.borrow_set,
self.location_table,
local,
location,
);
}
PlaceRef { local, projection: &[.., _] } => {
debug!(
"Recording `killed` facts for borrows of \
innermost projected local={:?} at location={:?}",
local, location
);
if let Some(borrow_indices) = self.borrow_set.local_map.get(&local) {
for &borrow_index in borrow_indices {
let places_conflict = places_conflict::places_conflict(
self.infcx.tcx,
self.body,
self.borrow_set[borrow_index].borrowed_place,
place,
places_conflict::PlaceConflictBias::NoOverlap,
);
if places_conflict {
let location_index = self.location_table.mid_index(location);
all_facts.loan_killed_at.push((borrow_index, location_index));
}
}
}
}
}
}
}
}
fn record_killed_borrows_for_local(
all_facts: &mut AllFacts,
borrow_set: &BorrowSet<'_>,
location_table: &LocationTable,
local: Local,
location: Location,
) {
if let Some(borrow_indices) = borrow_set.local_map.get(&local) {
all_facts.loan_killed_at.reserve(borrow_indices.len());
for &borrow_index in borrow_indices {
let location_index = location_table.mid_index(location);
all_facts.loan_killed_at.push((borrow_index, location_index));
}
}
}