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InferBorrowKind cleanup
`adjust_upvar_deref` and friends are implemented so that they reuse existing region so new region vars don't have to be generated. Since now we don't have to generate region vars in `InferBorrowKind`, creating a new capture info would be cheap and we can just use `determine_capture_info`. syn is updated so that let_else syntax can be used in fn with `#[instrument]` attribute. `restrict_repr_packed_field_ref_capture` is changed to take place by value since cloning is needed anyway.
This commit is contained in:
Gary Guo
parent
48258ffe5a
commit
52db6b9d02
@ -207,7 +207,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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assert_eq!(body_owner_def_id.to_def_id(), closure_def_id);
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let mut delegate = InferBorrowKind {
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fcx: self,
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closure_def_id,
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closure_def_id: local_def_id,
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capture_information: Default::default(),
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fake_reads: Default::default(),
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};
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@ -1648,7 +1648,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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fn restrict_repr_packed_field_ref_capture<'tcx>(
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tcx: TyCtxt<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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place: &Place<'tcx>,
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mut place: Place<'tcx>,
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mut curr_borrow_kind: ty::UpvarCapture,
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) -> (Place<'tcx>, ty::UpvarCapture) {
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let pos = place.projections.iter().enumerate().position(|(i, p)| {
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@ -1681,8 +1681,6 @@ fn restrict_repr_packed_field_ref_capture<'tcx>(
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}
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});
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let mut place = place.clone();
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if let Some(pos) = pos {
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truncate_place_to_len_and_update_capture_kind(&mut place, &mut curr_borrow_kind, pos);
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}
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@ -1729,7 +1727,7 @@ struct InferBorrowKind<'a, 'tcx> {
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fcx: &'a FnCtxt<'a, 'tcx>,
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// The def-id of the closure whose kind and upvar accesses are being inferred.
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closure_def_id: DefId,
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closure_def_id: LocalDefId,
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/// For each Place that is captured by the closure, we track the minimal kind of
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/// access we need (ref, ref mut, move, etc) and the expression that resulted in such access.
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@ -1762,170 +1760,51 @@ struct InferBorrowKind<'a, 'tcx> {
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}
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impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
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#[instrument(skip(self), level = "debug")]
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fn adjust_upvar_borrow_kind_for_consume(
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&mut self,
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place_with_id: &PlaceWithHirId<'tcx>,
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diag_expr_id: hir::HirId,
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) {
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let PlaceBase::Upvar(upvar_id) = place_with_id.place.base else {
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return;
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};
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debug!(?upvar_id);
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let capture_info = ty::CaptureInfo {
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capture_kind_expr_id: Some(diag_expr_id),
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path_expr_id: Some(diag_expr_id),
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capture_kind: ty::UpvarCapture::ByValue,
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};
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let curr_info = self.capture_information[&place_with_id.place];
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let updated_info = determine_capture_info(curr_info, capture_info);
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self.capture_information[&place_with_id.place] = updated_info;
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}
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/// Indicates that `place_with_id` is being directly mutated (e.g., assigned
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/// to). If the place is based on a by-ref upvar, this implies that
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/// the upvar must be borrowed using an `&mut` borrow.
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#[instrument(skip(self), level = "debug")]
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fn adjust_upvar_borrow_kind_for_mut(
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&mut self,
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place_with_id: &PlaceWithHirId<'tcx>,
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diag_expr_id: hir::HirId,
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) {
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if let PlaceBase::Upvar(_) = place_with_id.place.base {
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// Raw pointers don't inherit mutability
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if place_with_id.place.deref_tys().any(ty::TyS::is_unsafe_ptr) {
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return;
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fn adjust_capture_info(&mut self, place: Place<'tcx>, capture_info: ty::CaptureInfo) {
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match self.capture_information.get_mut(&place) {
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Some(curr_info) => {
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*curr_info = determine_capture_info(*curr_info, capture_info);
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}
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self.adjust_upvar_deref(place_with_id, diag_expr_id, ty::MutBorrow);
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}
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}
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#[instrument(skip(self), level = "debug")]
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fn adjust_upvar_borrow_kind_for_unique(
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&mut self,
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place_with_id: &PlaceWithHirId<'tcx>,
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diag_expr_id: hir::HirId,
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) {
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if let PlaceBase::Upvar(_) = place_with_id.place.base {
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if place_with_id.place.deref_tys().any(ty::TyS::is_unsafe_ptr) {
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// Raw pointers don't inherit mutability.
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return;
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None => {
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debug!("Capturing new place {:?}, capture_info={:?}", place, capture_info);
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self.capture_information.insert(place, capture_info);
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}
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// for a borrowed pointer to be unique, its base must be unique
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self.adjust_upvar_deref(place_with_id, diag_expr_id, ty::UniqueImmBorrow);
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}
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}
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fn adjust_upvar_deref(
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&mut self,
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place_with_id: &PlaceWithHirId<'tcx>,
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diag_expr_id: hir::HirId,
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borrow_kind: ty::BorrowKind,
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) {
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assert!(match borrow_kind {
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ty::MutBorrow => true,
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ty::UniqueImmBorrow => true,
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// imm borrows never require adjusting any kinds, so we don't wind up here
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ty::ImmBorrow => false,
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});
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// if this is an implicit deref of an
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// upvar, then we need to modify the
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// borrow_kind of the upvar to make sure it
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// is inferred to mutable if necessary
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self.adjust_upvar_borrow_kind(place_with_id, diag_expr_id, borrow_kind);
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}
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/// We infer the borrow_kind with which to borrow upvars in a stack closure.
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/// The borrow_kind basically follows a lattice of `imm < unique-imm < mut`,
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/// moving from left to right as needed (but never right to left).
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/// Here the argument `mutbl` is the borrow_kind that is required by
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/// some particular use.
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#[instrument(skip(self), level = "debug")]
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fn adjust_upvar_borrow_kind(
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&mut self,
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place_with_id: &PlaceWithHirId<'tcx>,
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diag_expr_id: hir::HirId,
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kind: ty::BorrowKind,
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) {
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let curr_capture_info = self.capture_information[&place_with_id.place];
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debug!(?curr_capture_info);
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if let ty::UpvarCapture::ByValue = curr_capture_info.capture_kind {
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// It's already captured by value, we don't need to do anything here
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return;
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} else if let ty::UpvarCapture::ByRef(_) = curr_capture_info.capture_kind {
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let capture_info = ty::CaptureInfo {
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capture_kind_expr_id: Some(diag_expr_id),
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path_expr_id: Some(diag_expr_id),
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capture_kind: ty::UpvarCapture::ByRef(kind),
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};
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let updated_info = determine_capture_info(curr_capture_info, capture_info);
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self.capture_information[&place_with_id.place] = updated_info;
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};
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}
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#[instrument(skip(self, diag_expr_id), level = "debug")]
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fn init_capture_info_for_place(
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&mut self,
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place_with_id: &PlaceWithHirId<'tcx>,
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diag_expr_id: hir::HirId,
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) {
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if let PlaceBase::Upvar(upvar_id) = place_with_id.place.base {
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assert_eq!(self.closure_def_id.expect_local(), upvar_id.closure_expr_id);
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// Initialize to ImmBorrow
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// We will escalate the CaptureKind based on any uses we see or in `process_collected_capture_information`.
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let capture_kind = ty::UpvarCapture::ByRef(ty::ImmBorrow);
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let expr_id = Some(diag_expr_id);
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let capture_info = ty::CaptureInfo {
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capture_kind_expr_id: expr_id,
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path_expr_id: expr_id,
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capture_kind,
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};
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debug!("Capturing new place {:?}, capture_info={:?}", place_with_id, capture_info);
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self.capture_information.insert(place_with_id.place.clone(), capture_info);
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} else {
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debug!("Not upvar");
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}
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}
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}
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impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
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fn fake_read(&mut self, place: Place<'tcx>, cause: FakeReadCause, diag_expr_id: hir::HirId) {
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if let PlaceBase::Upvar(_) = place.base {
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// We need to restrict Fake Read precision to avoid fake reading unsafe code,
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// such as deref of a raw pointer.
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let dummy_capture_kind = ty::UpvarCapture::ByRef(ty::BorrowKind::ImmBorrow);
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let PlaceBase::Upvar(_) = place.base else { return };
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let (place, _) = restrict_capture_precision(place, dummy_capture_kind);
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// We need to restrict Fake Read precision to avoid fake reading unsafe code,
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// such as deref of a raw pointer.
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let dummy_capture_kind = ty::UpvarCapture::ByRef(ty::BorrowKind::ImmBorrow);
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let (place, _) = restrict_repr_packed_field_ref_capture(
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self.fcx.tcx,
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self.fcx.param_env,
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&place,
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dummy_capture_kind,
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);
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self.fake_reads.push((place, cause, diag_expr_id));
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}
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let (place, _) = restrict_capture_precision(place, dummy_capture_kind);
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let (place, _) = restrict_repr_packed_field_ref_capture(
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self.fcx.tcx,
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self.fcx.param_env,
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place,
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dummy_capture_kind,
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);
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self.fake_reads.push((place, cause, diag_expr_id));
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}
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#[instrument(skip(self), level = "debug")]
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fn consume(&mut self, place_with_id: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId) {
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if !self.capture_information.contains_key(&place_with_id.place) {
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self.init_capture_info_for_place(place_with_id, diag_expr_id);
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}
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let PlaceBase::Upvar(upvar_id) = place_with_id.place.base else { return };
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assert_eq!(self.closure_def_id, upvar_id.closure_expr_id);
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self.adjust_upvar_borrow_kind_for_consume(place_with_id, diag_expr_id);
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self.adjust_capture_info(
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place_with_id.place.clone(),
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ty::CaptureInfo {
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capture_kind_expr_id: Some(diag_expr_id),
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path_expr_id: Some(diag_expr_id),
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capture_kind: ty::UpvarCapture::ByValue,
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},
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);
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}
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#[instrument(skip(self), level = "debug")]
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@ -1935,39 +1814,35 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
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diag_expr_id: hir::HirId,
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bk: ty::BorrowKind,
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) {
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let PlaceBase::Upvar(upvar_id) = place_with_id.place.base else { return };
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assert_eq!(self.closure_def_id, upvar_id.closure_expr_id);
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// The region here will get discarded/ignored
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let dummy_capture_kind = ty::UpvarCapture::ByRef(bk);
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let capture_kind = ty::UpvarCapture::ByRef(bk);
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// We only want repr packed restriction to be applied to reading references into a packed
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// struct, and not when the data is being moved. Therefore we call this method here instead
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// of in `restrict_capture_precision`.
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let (place, updated_kind) = restrict_repr_packed_field_ref_capture(
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let (place, mut capture_kind) = restrict_repr_packed_field_ref_capture(
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self.fcx.tcx,
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self.fcx.param_env,
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&place_with_id.place,
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dummy_capture_kind,
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place_with_id.place.clone(),
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capture_kind,
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);
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let place_with_id = PlaceWithHirId { place, ..*place_with_id };
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if !self.capture_information.contains_key(&place_with_id.place) {
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self.init_capture_info_for_place(&place_with_id, diag_expr_id);
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// Raw pointers don't inherit mutability
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if place_with_id.place.deref_tys().any(ty::TyS::is_unsafe_ptr) {
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capture_kind = ty::UpvarCapture::ByRef(ty::BorrowKind::ImmBorrow);
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}
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match updated_kind {
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ty::UpvarCapture::ByRef(kind) => match kind {
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ty::ImmBorrow => {}
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ty::UniqueImmBorrow => {
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self.adjust_upvar_borrow_kind_for_unique(&place_with_id, diag_expr_id);
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}
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ty::MutBorrow => {
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self.adjust_upvar_borrow_kind_for_mut(&place_with_id, diag_expr_id);
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}
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self.adjust_capture_info(
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place,
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ty::CaptureInfo {
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capture_kind_expr_id: Some(diag_expr_id),
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path_expr_id: Some(diag_expr_id),
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capture_kind,
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},
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// Just truncating the place will never cause capture kind to be updated to ByValue
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ty::UpvarCapture::ByValue => unreachable!(),
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}
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);
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}
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#[instrument(skip(self), level = "debug")]
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