-use super::{possible_origin::PossibleOriginVisitor, transitive_relation::TransitiveRelation};
+use super::possible_origin::PossibleOriginVisitor;
use crate::ty::is_copy;
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
use rustc_index::bit_set::{BitSet, HybridBitSet};
use rustc_lint::LateContext;
-use rustc_middle::mir::{self, visit::Visitor as _, Mutability};
-use rustc_middle::ty::{self, visit::TypeVisitor};
-use rustc_mir_dataflow::{impls::MaybeStorageLive, Analysis, ResultsCursor};
+use rustc_middle::mir::{
+ self, visit::Visitor as _, BasicBlock, Local, Location, Mutability, Statement, StatementKind, Terminator,
+};
+use rustc_middle::ty::{self, visit::TypeVisitor, TyCtxt};
+use rustc_mir_dataflow::{
+ fmt::DebugWithContext, impls::MaybeStorageLive, lattice::JoinSemiLattice, Analysis, AnalysisDomain,
+ CallReturnPlaces, ResultsCursor,
+};
+use std::collections::VecDeque;
use std::ops::ControlFlow;
/// Collects the possible borrowers of each local.
/// For example, `b = &a; c = &a;` will make `b` and (transitively) `c`
/// possible borrowers of `a`.
#[allow(clippy::module_name_repetitions)]
-struct PossibleBorrowerVisitor<'a, 'b, 'tcx> {
- possible_borrower: TransitiveRelation,
+struct PossibleBorrowerAnalysis<'b, 'tcx> {
+ tcx: TyCtxt<'tcx>,
body: &'b mir::Body<'tcx>,
- cx: &'a LateContext<'tcx>,
possible_origin: FxHashMap<mir::Local, HybridBitSet<mir::Local>>,
}
-impl<'a, 'b, 'tcx> PossibleBorrowerVisitor<'a, 'b, 'tcx> {
- fn new(
- cx: &'a LateContext<'tcx>,
- body: &'b mir::Body<'tcx>,
- possible_origin: FxHashMap<mir::Local, HybridBitSet<mir::Local>>,
- ) -> Self {
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct PossibleBorrowerState {
+ map: FxIndexMap<Local, BitSet<Local>>,
+ domain_size: usize,
+}
+
+impl PossibleBorrowerState {
+ fn new(domain_size: usize) -> Self {
Self {
- possible_borrower: TransitiveRelation::default(),
- cx,
- body,
- possible_origin,
+ map: FxIndexMap::default(),
+ domain_size,
}
}
- fn into_map(
- self,
- cx: &'a LateContext<'tcx>,
- maybe_live: ResultsCursor<'b, 'tcx, MaybeStorageLive>,
- ) -> PossibleBorrowerMap<'b, 'tcx> {
- 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;
- }
+ #[allow(clippy::similar_names)]
+ fn add(&mut self, borrowed: Local, borrower: Local) {
+ self.map
+ .entry(borrowed)
+ .or_insert(BitSet::new_empty(self.domain_size))
+ .insert(borrower);
+ }
+}
+
+impl<C> DebugWithContext<C> for PossibleBorrowerState {
+ fn fmt_with(&self, _ctxt: &C, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ <_ as std::fmt::Debug>::fmt(self, f)
+ }
+ fn fmt_diff_with(&self, _old: &Self, _ctxt: &C, _f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ unimplemented!()
+ }
+}
- let mut borrowers = self.possible_borrower.reachable_from(row, self.body.local_decls.len());
- borrowers.remove(mir::Local::from_usize(0));
+impl JoinSemiLattice for PossibleBorrowerState {
+ fn join(&mut self, other: &Self) -> bool {
+ let mut changed = false;
+ for (&borrowed, borrowers) in other.map.iter() {
if !borrowers.is_empty() {
- map.insert(row, borrowers);
+ changed |= self
+ .map
+ .entry(borrowed)
+ .or_insert(BitSet::new_empty(self.domain_size))
+ .union(borrowers);
}
}
+ changed
+ }
+}
- let bs = BitSet::new_empty(self.body.local_decls.len());
- PossibleBorrowerMap {
- map,
- maybe_live,
- bitset: (bs.clone(), bs),
+impl<'b, 'tcx> AnalysisDomain<'tcx> for PossibleBorrowerAnalysis<'b, 'tcx> {
+ type Domain = PossibleBorrowerState;
+
+ const NAME: &'static str = "possible_borrower";
+
+ fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
+ PossibleBorrowerState::new(body.local_decls.len())
+ }
+
+ fn initialize_start_block(&self, _body: &mir::Body<'tcx>, _entry_set: &mut Self::Domain) {}
+}
+
+impl<'b, 'tcx> PossibleBorrowerAnalysis<'b, 'tcx> {
+ fn new(
+ tcx: TyCtxt<'tcx>,
+ body: &'b mir::Body<'tcx>,
+ possible_origin: FxHashMap<mir::Local, HybridBitSet<mir::Local>>,
+ ) -> Self {
+ Self {
+ tcx,
+ body,
+ possible_origin,
}
}
}
-impl<'a, 'b, 'tcx> mir::visit::Visitor<'tcx> for PossibleBorrowerVisitor<'a, 'b, '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(_, _, borrowed) => {
- self.possible_borrower.add(borrowed.local, lhs);
- },
- other => {
- if ContainsRegion
- .visit_ty(place.ty(&self.body.local_decls, self.cx.tcx).ty)
- .is_continue()
- {
- return;
- }
- rvalue_locals(other, |rhs| {
- if lhs != rhs {
- self.possible_borrower.add(rhs, lhs);
+impl<'b, 'tcx> Analysis<'tcx> for PossibleBorrowerAnalysis<'b, 'tcx> {
+ fn apply_call_return_effect(
+ &self,
+ _state: &mut Self::Domain,
+ _block: BasicBlock,
+ _return_places: CallReturnPlaces<'_, 'tcx>,
+ ) {
+ }
+
+ fn apply_statement_effect(&self, state: &mut Self::Domain, statement: &Statement<'tcx>, _location: Location) {
+ if let StatementKind::Assign(box (place, rvalue)) = &statement.kind {
+ let lhs = place.local;
+ match rvalue {
+ mir::Rvalue::Ref(_, _, borrowed) => {
+ state.add(borrowed.local, lhs);
+ },
+ other => {
+ if ContainsRegion
+ .visit_ty(place.ty(&self.body.local_decls, self.tcx).ty)
+ .is_continue()
+ {
+ return;
}
- });
- },
+ rvalue_locals(other, |rhs| {
+ if lhs != rhs {
+ state.add(rhs, lhs);
+ }
+ });
+ },
+ }
}
}
- fn visit_terminator(&mut self, terminator: &mir::Terminator<'_>, _loc: mir::Location) {
+ fn apply_terminator_effect(&self, state: &mut Self::Domain, terminator: &Terminator<'tcx>, _location: Location) {
if let mir::TerminatorKind::Call {
args,
destination: mir::Place { local: dest, .. },
for y in mutable_variables {
for x in &immutable_borrowers {
- self.possible_borrower.add(*x, y);
+ state.add(*x, y);
}
for x in &mutable_borrowers {
- self.possible_borrower.add(*x, y);
+ state.add(*x, y);
}
}
}
}
}
-/// Result of `PossibleBorrowerVisitor`.
+/// Result of `PossibleBorrowerAnalysis`.
#[allow(clippy::module_name_repetitions)]
pub struct PossibleBorrowerMap<'b, 'tcx> {
- /// Mapping `Local -> its possible borrowers`
- pub map: FxHashMap<mir::Local, HybridBitSet<mir::Local>>,
+ body: &'b mir::Body<'tcx>,
+ possible_borrower: ResultsCursor<'b, 'tcx, PossibleBorrowerAnalysis<'b, 'tcx>>,
maybe_live: ResultsCursor<'b, 'tcx, MaybeStorageLive>,
- // Caches to avoid allocation of `BitSet` on every query
- pub bitset: (BitSet<mir::Local>, BitSet<mir::Local>),
}
-impl<'a, 'b, 'tcx> PossibleBorrowerMap<'b, 'tcx> {
- pub fn new(cx: &'a LateContext<'tcx>, mir: &'b mir::Body<'tcx>) -> Self {
+impl<'b, 'tcx> PossibleBorrowerMap<'b, 'tcx> {
+ pub fn new(cx: &LateContext<'tcx>, mir: &'b mir::Body<'tcx>) -> Self {
let possible_origin = {
let mut vis = PossibleOriginVisitor::new(mir);
vis.visit_body(mir);
vis.into_map(cx)
};
- let maybe_storage_live_result = MaybeStorageLive::new(BitSet::new_empty(mir.local_decls.len()))
+ let possible_borrower = PossibleBorrowerAnalysis::new(cx.tcx, mir, possible_origin)
.into_engine(cx.tcx, mir)
- .pass_name("redundant_clone")
+ .pass_name("possible_borrower")
.iterate_to_fixpoint()
.into_results_cursor(mir);
- let mut vis = PossibleBorrowerVisitor::new(cx, mir, possible_origin);
- vis.visit_body(mir);
- vis.into_map(cx, maybe_storage_live_result)
- }
-
- /// Returns true if the set of borrowers of `borrowed` living at `at` matches with `borrowers`.
- pub fn only_borrowers(&mut self, borrowers: &[mir::Local], borrowed: mir::Local, at: mir::Location) -> bool {
- self.bounded_borrowers(borrowers, borrowers, borrowed, at)
+ let maybe_live = MaybeStorageLive::new(BitSet::new_empty(mir.local_decls.len()))
+ .into_engine(cx.tcx, mir)
+ .pass_name("possible_borrower")
+ .iterate_to_fixpoint()
+ .into_results_cursor(mir);
+ PossibleBorrowerMap {
+ body: mir,
+ possible_borrower,
+ maybe_live,
+ }
}
- /// Returns true if the set of borrowers of `borrowed` living at `at` includes at least `below`
- /// but no more than `above`.
- pub fn bounded_borrowers(
+ /// Returns true if the set of borrowers of `borrowed` living at `at` includes no more than
+ /// `borrowers`.
+ /// Notes:
+ /// 1. It would be nice if `PossibleBorrowerMap` could store `cx` so that `at_most_borrowers`
+ /// would not require it to be passed in. But a `PossibleBorrowerMap` is stored in `LintPass`
+ /// `Dereferencing`, which outlives any `LateContext`.
+ /// 2. In all current uses of `at_most_borrowers`, `borrowers` is a slice of at most two
+ /// elements. Thus, `borrowers.contains(...)` is effectively a constant-time operation. If
+ /// `at_most_borrowers`'s uses were to expand beyond this, its implementation might have to be
+ /// adjusted.
+ pub fn at_most_borrowers(
&mut self,
- below: &[mir::Local],
- above: &[mir::Local],
+ cx: &LateContext<'tcx>,
+ borrowers: &[mir::Local],
borrowed: mir::Local,
at: mir::Location,
) -> bool {
- self.maybe_live.seek_after_primary_effect(at);
+ if is_copy(cx, self.body.local_decls[borrowed].ty) {
+ return true;
+ }
+
+ self.possible_borrower.seek_before_primary_effect(at);
+ self.maybe_live.seek_before_primary_effect(at);
- self.bitset.0.clear();
- let maybe_live = &mut self.maybe_live;
- if let Some(bitset) = self.map.get(&borrowed) {
- for b in bitset.iter().filter(move |b| maybe_live.contains(*b)) {
- self.bitset.0.insert(b);
+ let possible_borrower = &self.possible_borrower.get().map;
+ let maybe_live = &self.maybe_live;
+
+ let mut queued = BitSet::new_empty(self.body.local_decls.len());
+ let mut deque = VecDeque::with_capacity(self.body.local_decls.len());
+
+ if let Some(borrowers) = possible_borrower.get(&borrowed) {
+ for b in borrowers.iter() {
+ if queued.insert(b) {
+ deque.push_back(b);
+ }
}
} else {
- return false;
+ // Nothing borrows `borrowed` at `at`.
+ return true;
}
- self.bitset.1.clear();
- for b in below {
- self.bitset.1.insert(*b);
- }
-
- if !self.bitset.0.superset(&self.bitset.1) {
- return false;
- }
+ while let Some(borrower) = deque.pop_front() {
+ if maybe_live.contains(borrower) && !borrowers.contains(&borrower) {
+ return false;
+ }
- for b in above {
- self.bitset.0.remove(*b);
+ if let Some(borrowers) = possible_borrower.get(&borrower) {
+ for b in borrowers.iter() {
+ if queued.insert(b) {
+ deque.push_back(b);
+ }
+ }
+ }
}
- self.bitset.0.is_empty()
+ true
}
pub fn local_is_alive_at(&mut self, local: mir::Local, at: mir::Location) -> bool {
projects / rust.git / blobdiff