use super::transitive_relation::TransitiveRelation;
use crate::ty::is_copy;
use rustc_data_structures::fx::FxHashMap;
use rustc_index::bit_set::HybridBitSet;
use rustc_lint::LateContext;
use rustc_middle::mir;
#[allow(clippy::module_name_repetitions)]
pub(super) struct PossibleOriginVisitor<'a, 'tcx> {
possible_origin: TransitiveRelation,
body: &'a mir::Body<'tcx>,
}
impl<'a, 'tcx> PossibleOriginVisitor<'a, 'tcx> {
pub fn new(body: &'a mir::Body<'tcx>) -> Self {
Self {
possible_origin: TransitiveRelation::default(),
body,
}
}
pub fn into_map(self, cx: &LateContext<'tcx>) -> FxHashMap<mir::Local, HybridBitSet<mir::Local>> {
let mut map = FxHashMap::default();
for row in (1..self.body.local_decls.len()).map(mir::Local::from_usize) {
if is_copy(cx, self.body.local_decls[row].ty) {
continue;
}
let mut borrowers = self.possible_origin.reachable_from(row, self.body.local_decls.len());
borrowers.remove(mir::Local::from_usize(0));
if !borrowers.is_empty() {
map.insert(row, borrowers);
}
}
map
}
}
impl<'a, 'tcx> mir::visit::Visitor<'tcx> for PossibleOriginVisitor<'a, 'tcx> {
fn visit_assign(&mut self, place: &mir::Place<'tcx>, rvalue: &mir::Rvalue<'_>, _location: mir::Location) {
let lhs = place.local;
match rvalue {
mir::Rvalue::Ref(_, mir::BorrowKind::Mut { .. }, borrowed) |
mir::Rvalue::Use(mir::Operand::Move(borrowed)) |
mir::Rvalue::Cast(_, mir::Operand::Move(borrowed), _)
=> {
self.possible_origin.add(lhs, borrowed.local);
},
_ => {},
}
}
}