Move inner items outside
This commit is contained in:
Jonas Schievink
parent
cd5d7201ad
commit
682de94e31
@ -858,89 +858,6 @@ fn find_candidates<'a, 'tcx>(
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tcx: TyCtxt<'tcx>,
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body: &'a Body<'tcx>,
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) -> Vec<CandidateAssignment<'tcx>> {
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struct FindAssignments<'a, 'tcx> {
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tcx: TyCtxt<'tcx>,
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body: &'a Body<'tcx>,
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candidates: Vec<CandidateAssignment<'tcx>>,
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ever_borrowed_locals: BitSet<Local>,
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locals_used_as_array_index: BitSet<Local>,
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}
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impl<'a, 'tcx> Visitor<'tcx> for FindAssignments<'a, 'tcx> {
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fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
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if let StatementKind::Assign(box (
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dest,
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Rvalue::Use(Operand::Copy(src) | Operand::Move(src)),
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)) = &statement.kind
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{
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// `dest` must not have pointer indirection.
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if dest.is_indirect() {
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return;
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}
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// `src` must be a plain local.
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if !src.projection.is_empty() {
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return;
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}
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// Since we want to replace `src` with `dest`, `src` must not be required.
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if is_local_required(src.local, self.body) {
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return;
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}
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// Can't optimize if both locals ever have their address taken (can introduce
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// aliasing).
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// FIXME: This can be smarter and take `StorageDead` into account (which
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// invalidates borrows).
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if self.ever_borrowed_locals.contains(dest.local)
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&& self.ever_borrowed_locals.contains(src.local)
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{
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return;
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}
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assert_ne!(dest.local, src.local, "self-assignments are UB");
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// We can't replace locals occurring in `PlaceElem::Index` for now.
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if self.locals_used_as_array_index.contains(src.local) {
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return;
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}
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// Handle the "subtle case" described above by rejecting any `dest` that is or
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// projects through a union.
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let is_union = |ty: Ty<'_>| {
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if let ty::Adt(def, _) = ty.kind() {
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if def.is_union() {
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return true;
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}
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}
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false
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};
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let mut place_ty = PlaceTy::from_ty(self.body.local_decls[dest.local].ty);
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if is_union(place_ty.ty) {
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return;
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}
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for elem in dest.projection {
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if let PlaceElem::Index(_) = elem {
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// `dest` contains an indexing projection.
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return;
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}
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place_ty = place_ty.projection_ty(self.tcx, elem);
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if is_union(place_ty.ty) {
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return;
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}
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}
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self.candidates.push(CandidateAssignment {
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dest: *dest,
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src: src.local,
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loc: location,
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});
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}
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}
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}
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let mut visitor = FindAssignments {
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tcx,
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body,
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@ -952,6 +869,89 @@ fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
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visitor.candidates
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}
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struct FindAssignments<'a, 'tcx> {
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tcx: TyCtxt<'tcx>,
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body: &'a Body<'tcx>,
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candidates: Vec<CandidateAssignment<'tcx>>,
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ever_borrowed_locals: BitSet<Local>,
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locals_used_as_array_index: BitSet<Local>,
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}
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impl<'a, 'tcx> Visitor<'tcx> for FindAssignments<'a, 'tcx> {
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fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
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if let StatementKind::Assign(box (
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dest,
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Rvalue::Use(Operand::Copy(src) | Operand::Move(src)),
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)) = &statement.kind
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{
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// `dest` must not have pointer indirection.
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if dest.is_indirect() {
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return;
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}
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// `src` must be a plain local.
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if !src.projection.is_empty() {
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return;
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}
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// Since we want to replace `src` with `dest`, `src` must not be required.
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if is_local_required(src.local, self.body) {
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return;
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}
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// Can't optimize if both locals ever have their address taken (can introduce
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// aliasing).
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// FIXME: This can be smarter and take `StorageDead` into account (which
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// invalidates borrows).
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if self.ever_borrowed_locals.contains(dest.local)
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&& self.ever_borrowed_locals.contains(src.local)
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{
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return;
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}
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assert_ne!(dest.local, src.local, "self-assignments are UB");
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// We can't replace locals occurring in `PlaceElem::Index` for now.
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if self.locals_used_as_array_index.contains(src.local) {
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return;
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}
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// Handle the "subtle case" described above by rejecting any `dest` that is or
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// projects through a union.
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let is_union = |ty: Ty<'_>| {
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if let ty::Adt(def, _) = ty.kind() {
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if def.is_union() {
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return true;
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}
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}
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false
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};
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let mut place_ty = PlaceTy::from_ty(self.body.local_decls[dest.local].ty);
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if is_union(place_ty.ty) {
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return;
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}
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for elem in dest.projection {
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if let PlaceElem::Index(_) = elem {
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// `dest` contains an indexing projection.
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return;
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}
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place_ty = place_ty.projection_ty(self.tcx, elem);
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if is_union(place_ty.ty) {
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return;
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}
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}
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self.candidates.push(CandidateAssignment {
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dest: *dest,
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src: src.local,
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loc: location,
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});
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}
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}
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}
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/// Some locals are part of the function's interface and can not be removed.
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///
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/// Note that these locals *can* still be merged with non-required locals by removing that other
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@ -965,92 +965,92 @@ fn is_local_required(local: Local, body: &Body<'_>) -> bool {
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/// Walks MIR to find all locals that have their address taken anywhere.
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fn ever_borrowed_locals(body: &Body<'_>) -> BitSet<Local> {
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struct BorrowCollector {
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locals: BitSet<Local>,
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}
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impl<'tcx> Visitor<'tcx> for BorrowCollector {
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fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
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self.super_rvalue(rvalue, location);
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match rvalue {
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Rvalue::AddressOf(_, borrowed_place) | Rvalue::Ref(_, _, borrowed_place) => {
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if !borrowed_place.is_indirect() {
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self.locals.insert(borrowed_place.local);
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}
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}
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Rvalue::Cast(..)
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| Rvalue::Use(..)
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| Rvalue::Repeat(..)
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| Rvalue::Len(..)
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| Rvalue::BinaryOp(..)
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| Rvalue::CheckedBinaryOp(..)
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| Rvalue::NullaryOp(..)
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| Rvalue::UnaryOp(..)
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| Rvalue::Discriminant(..)
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| Rvalue::Aggregate(..)
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| Rvalue::ThreadLocalRef(..) => {}
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}
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}
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fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
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self.super_terminator(terminator, location);
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match terminator.kind {
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TerminatorKind::Drop { place: dropped_place, .. }
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| TerminatorKind::DropAndReplace { place: dropped_place, .. } => {
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self.locals.insert(dropped_place.local);
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}
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TerminatorKind::Abort
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| TerminatorKind::Assert { .. }
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| TerminatorKind::Call { .. }
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| TerminatorKind::FalseEdge { .. }
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| TerminatorKind::FalseUnwind { .. }
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| TerminatorKind::GeneratorDrop
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| TerminatorKind::Goto { .. }
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| TerminatorKind::Resume
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| TerminatorKind::Return
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| TerminatorKind::SwitchInt { .. }
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| TerminatorKind::Unreachable
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| TerminatorKind::Yield { .. }
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| TerminatorKind::InlineAsm { .. } => {}
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}
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}
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}
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let mut visitor = BorrowCollector { locals: BitSet::new_empty(body.local_decls.len()) };
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visitor.visit_body(body);
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visitor.locals
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}
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struct BorrowCollector {
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locals: BitSet<Local>,
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}
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impl<'tcx> Visitor<'tcx> for BorrowCollector {
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fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
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self.super_rvalue(rvalue, location);
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match rvalue {
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Rvalue::AddressOf(_, borrowed_place) | Rvalue::Ref(_, _, borrowed_place) => {
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if !borrowed_place.is_indirect() {
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self.locals.insert(borrowed_place.local);
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}
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}
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Rvalue::Cast(..)
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| Rvalue::Use(..)
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| Rvalue::Repeat(..)
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| Rvalue::Len(..)
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| Rvalue::BinaryOp(..)
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| Rvalue::CheckedBinaryOp(..)
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| Rvalue::NullaryOp(..)
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| Rvalue::UnaryOp(..)
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| Rvalue::Discriminant(..)
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| Rvalue::Aggregate(..)
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| Rvalue::ThreadLocalRef(..) => {}
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}
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}
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fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
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self.super_terminator(terminator, location);
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match terminator.kind {
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TerminatorKind::Drop { place: dropped_place, .. }
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| TerminatorKind::DropAndReplace { place: dropped_place, .. } => {
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self.locals.insert(dropped_place.local);
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}
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TerminatorKind::Abort
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| TerminatorKind::Assert { .. }
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| TerminatorKind::Call { .. }
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| TerminatorKind::FalseEdge { .. }
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| TerminatorKind::FalseUnwind { .. }
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| TerminatorKind::GeneratorDrop
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| TerminatorKind::Goto { .. }
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| TerminatorKind::Resume
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| TerminatorKind::Return
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| TerminatorKind::SwitchInt { .. }
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| TerminatorKind::Unreachable
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| TerminatorKind::Yield { .. }
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| TerminatorKind::InlineAsm { .. } => {}
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}
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}
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}
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/// `PlaceElem::Index` only stores a `Local`, so we can't replace that with a full `Place`.
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///
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/// Collect locals used as indices so we don't generate candidates that are impossible to apply
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/// later.
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fn locals_used_as_array_index(body: &Body<'_>) -> BitSet<Local> {
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struct IndexCollector {
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locals: BitSet<Local>,
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}
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impl<'tcx> Visitor<'tcx> for IndexCollector {
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fn visit_projection_elem(
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&mut self,
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local: Local,
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proj_base: &[PlaceElem<'tcx>],
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elem: PlaceElem<'tcx>,
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context: PlaceContext,
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location: Location,
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) {
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if let PlaceElem::Index(i) = elem {
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self.locals.insert(i);
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}
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self.super_projection_elem(local, proj_base, elem, context, location);
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}
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}
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let mut visitor = IndexCollector { locals: BitSet::new_empty(body.local_decls.len()) };
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visitor.visit_body(body);
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visitor.locals
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}
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struct IndexCollector {
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locals: BitSet<Local>,
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}
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impl<'tcx> Visitor<'tcx> for IndexCollector {
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fn visit_projection_elem(
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&mut self,
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local: Local,
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proj_base: &[PlaceElem<'tcx>],
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elem: PlaceElem<'tcx>,
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context: PlaceContext,
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location: Location,
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) {
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if let PlaceElem::Index(i) = elem {
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self.locals.insert(i);
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}
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self.super_projection_elem(local, proj_base, elem, context, location);
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}
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}
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