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-rw-r--r--compiler/rustc_mir_dataflow/src/move_paths/builder.rs559
1 files changed, 559 insertions, 0 deletions
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
new file mode 100644
index 000000000..116e5c1f3
--- /dev/null
+++ b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
@@ -0,0 +1,559 @@
+use crate::move_paths::FxHashMap;
+use crate::un_derefer::UnDerefer;
+use rustc_index::vec::IndexVec;
+use rustc_middle::mir::tcx::RvalueInitializationState;
+use rustc_middle::mir::*;
+use rustc_middle::ty::{self, TyCtxt};
+use smallvec::{smallvec, SmallVec};
+
+use std::mem;
+
+use super::abs_domain::Lift;
+use super::IllegalMoveOriginKind::*;
+use super::{Init, InitIndex, InitKind, InitLocation, LookupResult, MoveError};
+use super::{
+ LocationMap, MoveData, MoveOut, MoveOutIndex, MovePath, MovePathIndex, MovePathLookup,
+};
+
+struct MoveDataBuilder<'a, 'tcx> {
+ body: &'a Body<'tcx>,
+ tcx: TyCtxt<'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+ data: MoveData<'tcx>,
+ errors: Vec<(Place<'tcx>, MoveError<'tcx>)>,
+ un_derefer: UnDerefer<'tcx>,
+}
+
+impl<'a, 'tcx> MoveDataBuilder<'a, 'tcx> {
+ fn new(body: &'a Body<'tcx>, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
+ let mut move_paths = IndexVec::new();
+ let mut path_map = IndexVec::new();
+ let mut init_path_map = IndexVec::new();
+
+ MoveDataBuilder {
+ body,
+ tcx,
+ param_env,
+ errors: Vec::new(),
+ un_derefer: UnDerefer { tcx: tcx, derefer_sidetable: Default::default() },
+ data: MoveData {
+ moves: IndexVec::new(),
+ loc_map: LocationMap::new(body),
+ rev_lookup: MovePathLookup {
+ locals: body
+ .local_decls
+ .indices()
+ .map(|i| {
+ Self::new_move_path(
+ &mut move_paths,
+ &mut path_map,
+ &mut init_path_map,
+ None,
+ Place::from(i),
+ )
+ })
+ .collect(),
+ projections: Default::default(),
+ },
+ move_paths,
+ path_map,
+ inits: IndexVec::new(),
+ init_loc_map: LocationMap::new(body),
+ init_path_map,
+ },
+ }
+ }
+
+ fn new_move_path(
+ move_paths: &mut IndexVec<MovePathIndex, MovePath<'tcx>>,
+ path_map: &mut IndexVec<MovePathIndex, SmallVec<[MoveOutIndex; 4]>>,
+ init_path_map: &mut IndexVec<MovePathIndex, SmallVec<[InitIndex; 4]>>,
+ parent: Option<MovePathIndex>,
+ place: Place<'tcx>,
+ ) -> MovePathIndex {
+ let move_path =
+ move_paths.push(MovePath { next_sibling: None, first_child: None, parent, place });
+
+ if let Some(parent) = parent {
+ let next_sibling = mem::replace(&mut move_paths[parent].first_child, Some(move_path));
+ move_paths[move_path].next_sibling = next_sibling;
+ }
+
+ let path_map_ent = path_map.push(smallvec![]);
+ assert_eq!(path_map_ent, move_path);
+
+ let init_path_map_ent = init_path_map.push(smallvec![]);
+ assert_eq!(init_path_map_ent, move_path);
+
+ move_path
+ }
+}
+
+impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
+ /// This creates a MovePath for a given place, returning an `MovePathError`
+ /// if that place can't be moved from.
+ ///
+ /// NOTE: places behind references *do not* get a move path, which is
+ /// problematic for borrowck.
+ ///
+ /// Maybe we should have separate "borrowck" and "moveck" modes.
+ fn move_path_for(&mut self, place: Place<'tcx>) -> Result<MovePathIndex, MoveError<'tcx>> {
+ if let Some(new_place) = self.builder.un_derefer.derefer(place.as_ref(), self.builder.body)
+ {
+ return self.move_path_for(new_place);
+ }
+
+ debug!("lookup({:?})", place);
+ let mut base = self.builder.data.rev_lookup.locals[place.local];
+
+ // The move path index of the first union that we find. Once this is
+ // some we stop creating child move paths, since moves from unions
+ // move the whole thing.
+ // We continue looking for other move errors though so that moving
+ // from `*(u.f: &_)` isn't allowed.
+ let mut union_path = None;
+
+ for (i, elem) in place.projection.iter().enumerate() {
+ let proj_base = &place.projection[..i];
+ let body = self.builder.body;
+ let tcx = self.builder.tcx;
+ let place_ty = Place::ty_from(place.local, proj_base, body, tcx).ty;
+ match place_ty.kind() {
+ ty::Ref(..) | ty::RawPtr(..) => {
+ let proj = &place.projection[..i + 1];
+ return Err(MoveError::cannot_move_out_of(
+ self.loc,
+ BorrowedContent {
+ target_place: Place {
+ local: place.local,
+ projection: tcx.intern_place_elems(proj),
+ },
+ },
+ ));
+ }
+ ty::Adt(adt, _) if adt.has_dtor(tcx) && !adt.is_box() => {
+ return Err(MoveError::cannot_move_out_of(
+ self.loc,
+ InteriorOfTypeWithDestructor { container_ty: place_ty },
+ ));
+ }
+ ty::Adt(adt, _) if adt.is_union() => {
+ union_path.get_or_insert(base);
+ }
+ ty::Slice(_) => {
+ return Err(MoveError::cannot_move_out_of(
+ self.loc,
+ InteriorOfSliceOrArray {
+ ty: place_ty,
+ is_index: matches!(elem, ProjectionElem::Index(..)),
+ },
+ ));
+ }
+
+ ty::Array(..) => {
+ if let ProjectionElem::Index(..) = elem {
+ return Err(MoveError::cannot_move_out_of(
+ self.loc,
+ InteriorOfSliceOrArray { ty: place_ty, is_index: true },
+ ));
+ }
+ }
+
+ _ => {}
+ };
+
+ if union_path.is_none() {
+ base = self.add_move_path(base, elem, |tcx| Place {
+ local: place.local,
+ projection: tcx.intern_place_elems(&place.projection[..i + 1]),
+ });
+ }
+ }
+
+ if let Some(base) = union_path {
+ // Move out of union - always move the entire union.
+ Err(MoveError::UnionMove { path: base })
+ } else {
+ Ok(base)
+ }
+ }
+
+ fn add_move_path(
+ &mut self,
+ base: MovePathIndex,
+ elem: PlaceElem<'tcx>,
+ mk_place: impl FnOnce(TyCtxt<'tcx>) -> Place<'tcx>,
+ ) -> MovePathIndex {
+ let MoveDataBuilder {
+ data: MoveData { rev_lookup, move_paths, path_map, init_path_map, .. },
+ tcx,
+ ..
+ } = self.builder;
+ *rev_lookup.projections.entry((base, elem.lift())).or_insert_with(move || {
+ MoveDataBuilder::new_move_path(
+ move_paths,
+ path_map,
+ init_path_map,
+ Some(base),
+ mk_place(*tcx),
+ )
+ })
+ }
+
+ fn create_move_path(&mut self, place: Place<'tcx>) {
+ // This is an non-moving access (such as an overwrite or
+ // drop), so this not being a valid move path is OK.
+ let _ = self.move_path_for(place);
+ }
+}
+
+pub type MoveDat<'tcx> = Result<
+ (FxHashMap<Local, Place<'tcx>>, MoveData<'tcx>),
+ (MoveData<'tcx>, Vec<(Place<'tcx>, MoveError<'tcx>)>),
+>;
+
+impl<'a, 'tcx> MoveDataBuilder<'a, 'tcx> {
+ fn finalize(self) -> MoveDat<'tcx> {
+ debug!("{}", {
+ debug!("moves for {:?}:", self.body.span);
+ for (j, mo) in self.data.moves.iter_enumerated() {
+ debug!(" {:?} = {:?}", j, mo);
+ }
+ debug!("move paths for {:?}:", self.body.span);
+ for (j, path) in self.data.move_paths.iter_enumerated() {
+ debug!(" {:?} = {:?}", j, path);
+ }
+ "done dumping moves"
+ });
+
+ if self.errors.is_empty() {
+ Ok((self.un_derefer.derefer_sidetable, self.data))
+ } else {
+ Err((self.data, self.errors))
+ }
+ }
+}
+
+pub(super) fn gather_moves<'tcx>(
+ body: &Body<'tcx>,
+ tcx: TyCtxt<'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+) -> MoveDat<'tcx> {
+ let mut builder = MoveDataBuilder::new(body, tcx, param_env);
+
+ builder.gather_args();
+
+ for (bb, block) in body.basic_blocks().iter_enumerated() {
+ for (i, stmt) in block.statements.iter().enumerate() {
+ let source = Location { block: bb, statement_index: i };
+ builder.gather_statement(source, stmt);
+ }
+
+ let terminator_loc = Location { block: bb, statement_index: block.statements.len() };
+ builder.gather_terminator(terminator_loc, block.terminator());
+ }
+
+ builder.finalize()
+}
+
+impl<'a, 'tcx> MoveDataBuilder<'a, 'tcx> {
+ fn gather_args(&mut self) {
+ for arg in self.body.args_iter() {
+ let path = self.data.rev_lookup.locals[arg];
+
+ let init = self.data.inits.push(Init {
+ path,
+ kind: InitKind::Deep,
+ location: InitLocation::Argument(arg),
+ });
+
+ debug!("gather_args: adding init {:?} of {:?} for argument {:?}", init, path, arg);
+
+ self.data.init_path_map[path].push(init);
+ }
+ }
+
+ fn gather_statement(&mut self, loc: Location, stmt: &Statement<'tcx>) {
+ debug!("gather_statement({:?}, {:?})", loc, stmt);
+ (Gatherer { builder: self, loc }).gather_statement(stmt);
+ }
+
+ fn gather_terminator(&mut self, loc: Location, term: &Terminator<'tcx>) {
+ debug!("gather_terminator({:?}, {:?})", loc, term);
+ (Gatherer { builder: self, loc }).gather_terminator(term);
+ }
+}
+
+struct Gatherer<'b, 'a, 'tcx> {
+ builder: &'b mut MoveDataBuilder<'a, 'tcx>,
+ loc: Location,
+}
+
+impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
+ fn gather_statement(&mut self, stmt: &Statement<'tcx>) {
+ match &stmt.kind {
+ StatementKind::Assign(box (place, Rvalue::CopyForDeref(reffed))) => {
+ assert!(place.projection.is_empty());
+ if self.builder.body.local_decls[place.local].is_deref_temp() {
+ self.builder.un_derefer.derefer_sidetable.insert(place.local, *reffed);
+ }
+ }
+ StatementKind::Assign(box (place, rval)) => {
+ self.create_move_path(*place);
+ if let RvalueInitializationState::Shallow = rval.initialization_state() {
+ // Box starts out uninitialized - need to create a separate
+ // move-path for the interior so it will be separate from
+ // the exterior.
+ self.create_move_path(self.builder.tcx.mk_place_deref(*place));
+ self.gather_init(place.as_ref(), InitKind::Shallow);
+ } else {
+ self.gather_init(place.as_ref(), InitKind::Deep);
+ }
+ self.gather_rvalue(rval);
+ }
+ StatementKind::FakeRead(box (_, place)) => {
+ self.create_move_path(*place);
+ }
+ StatementKind::StorageLive(_) => {}
+ StatementKind::StorageDead(local) => {
+ // DerefTemp locals (results of CopyForDeref) don't actually move anything.
+ if !self.builder.un_derefer.derefer_sidetable.contains_key(&local) {
+ self.gather_move(Place::from(*local));
+ }
+ }
+ StatementKind::SetDiscriminant { .. } | StatementKind::Deinit(..) => {
+ span_bug!(
+ stmt.source_info.span,
+ "SetDiscriminant/Deinit should not exist during borrowck"
+ );
+ }
+ StatementKind::Retag { .. }
+ | StatementKind::AscribeUserType(..)
+ | StatementKind::Coverage(..)
+ | StatementKind::CopyNonOverlapping(..)
+ | StatementKind::Nop => {}
+ }
+ }
+
+ fn gather_rvalue(&mut self, rvalue: &Rvalue<'tcx>) {
+ match *rvalue {
+ Rvalue::ThreadLocalRef(_) => {} // not-a-move
+ Rvalue::Use(ref operand)
+ | Rvalue::Repeat(ref operand, _)
+ | Rvalue::Cast(_, ref operand, _)
+ | Rvalue::ShallowInitBox(ref operand, _)
+ | Rvalue::UnaryOp(_, ref operand) => self.gather_operand(operand),
+ Rvalue::BinaryOp(ref _binop, box (ref lhs, ref rhs))
+ | Rvalue::CheckedBinaryOp(ref _binop, box (ref lhs, ref rhs)) => {
+ self.gather_operand(lhs);
+ self.gather_operand(rhs);
+ }
+ Rvalue::Aggregate(ref _kind, ref operands) => {
+ for operand in operands {
+ self.gather_operand(operand);
+ }
+ }
+ Rvalue::CopyForDeref(..) => unreachable!(),
+ Rvalue::Ref(..)
+ | Rvalue::AddressOf(..)
+ | Rvalue::Discriminant(..)
+ | Rvalue::Len(..)
+ | Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) => {}
+ }
+ }
+
+ fn gather_terminator(&mut self, term: &Terminator<'tcx>) {
+ match term.kind {
+ TerminatorKind::Goto { target: _ }
+ | TerminatorKind::FalseEdge { .. }
+ | TerminatorKind::FalseUnwind { .. }
+ // In some sense returning moves the return place into the current
+ // call's destination, however, since there are no statements after
+ // this that could possibly access the return place, this doesn't
+ // need recording.
+ | TerminatorKind::Return
+ | TerminatorKind::Resume
+ | TerminatorKind::Abort
+ | TerminatorKind::GeneratorDrop
+ | TerminatorKind::Unreachable => {}
+
+ TerminatorKind::Assert { ref cond, .. } => {
+ self.gather_operand(cond);
+ }
+
+ TerminatorKind::SwitchInt { ref discr, .. } => {
+ self.gather_operand(discr);
+ }
+
+ TerminatorKind::Yield { ref value, resume_arg: place, .. } => {
+ self.gather_operand(value);
+ self.create_move_path(place);
+ self.gather_init(place.as_ref(), InitKind::Deep);
+ }
+
+ TerminatorKind::Drop { place, target: _, unwind: _ } => {
+ self.gather_move(place);
+ }
+ TerminatorKind::DropAndReplace { place, ref value, .. } => {
+ self.create_move_path(place);
+ self.gather_operand(value);
+ self.gather_init(place.as_ref(), InitKind::Deep);
+ }
+ TerminatorKind::Call {
+ ref func,
+ ref args,
+ destination,
+ target,
+ cleanup: _,
+ from_hir_call: _,
+ fn_span: _,
+ } => {
+ self.gather_operand(func);
+ for arg in args {
+ self.gather_operand(arg);
+ }
+ if let Some(_bb) = target {
+ self.create_move_path(destination);
+ self.gather_init(destination.as_ref(), InitKind::NonPanicPathOnly);
+ }
+ }
+ TerminatorKind::InlineAsm {
+ template: _,
+ ref operands,
+ options: _,
+ line_spans: _,
+ destination: _,
+ cleanup: _,
+ } => {
+ for op in operands {
+ match *op {
+ InlineAsmOperand::In { reg: _, ref value }
+ => {
+ self.gather_operand(value);
+ }
+ InlineAsmOperand::Out { reg: _, late: _, place, .. } => {
+ if let Some(place) = place {
+ self.create_move_path(place);
+ self.gather_init(place.as_ref(), InitKind::Deep);
+ }
+ }
+ InlineAsmOperand::InOut { reg: _, late: _, ref in_value, out_place } => {
+ self.gather_operand(in_value);
+ if let Some(out_place) = out_place {
+ self.create_move_path(out_place);
+ self.gather_init(out_place.as_ref(), InitKind::Deep);
+ }
+ }
+ InlineAsmOperand::Const { value: _ }
+ | InlineAsmOperand::SymFn { value: _ }
+ | InlineAsmOperand::SymStatic { def_id: _ } => {}
+ }
+ }
+ }
+ }
+ }
+
+ fn gather_operand(&mut self, operand: &Operand<'tcx>) {
+ match *operand {
+ Operand::Constant(..) | Operand::Copy(..) => {} // not-a-move
+ Operand::Move(place) => {
+ // a move
+ self.gather_move(place);
+ }
+ }
+ }
+
+ fn gather_move(&mut self, place: Place<'tcx>) {
+ debug!("gather_move({:?}, {:?})", self.loc, place);
+ if let Some(new_place) = self.builder.un_derefer.derefer(place.as_ref(), self.builder.body)
+ {
+ self.gather_move(new_place);
+ return;
+ }
+
+ if let [ref base @ .., ProjectionElem::Subslice { from, to, from_end: false }] =
+ **place.projection
+ {
+ // Split `Subslice` patterns into the corresponding list of
+ // `ConstIndex` patterns. This is done to ensure that all move paths
+ // are disjoint, which is expected by drop elaboration.
+ let base_place =
+ Place { local: place.local, projection: self.builder.tcx.intern_place_elems(base) };
+ let base_path = match self.move_path_for(base_place) {
+ Ok(path) => path,
+ Err(MoveError::UnionMove { path }) => {
+ self.record_move(place, path);
+ return;
+ }
+ Err(error @ MoveError::IllegalMove { .. }) => {
+ self.builder.errors.push((base_place, error));
+ return;
+ }
+ };
+ let base_ty = base_place.ty(self.builder.body, self.builder.tcx).ty;
+ let len: u64 = match base_ty.kind() {
+ ty::Array(_, size) => size.eval_usize(self.builder.tcx, self.builder.param_env),
+ _ => bug!("from_end: false slice pattern of non-array type"),
+ };
+ for offset in from..to {
+ let elem =
+ ProjectionElem::ConstantIndex { offset, min_length: len, from_end: false };
+ let path =
+ self.add_move_path(base_path, elem, |tcx| tcx.mk_place_elem(base_place, elem));
+ self.record_move(place, path);
+ }
+ } else {
+ match self.move_path_for(place) {
+ Ok(path) | Err(MoveError::UnionMove { path }) => self.record_move(place, path),
+ Err(error @ MoveError::IllegalMove { .. }) => {
+ self.builder.errors.push((place, error));
+ }
+ };
+ }
+ }
+
+ fn record_move(&mut self, place: Place<'tcx>, path: MovePathIndex) {
+ let move_out = self.builder.data.moves.push(MoveOut { path, source: self.loc });
+ debug!(
+ "gather_move({:?}, {:?}): adding move {:?} of {:?}",
+ self.loc, place, move_out, path
+ );
+ self.builder.data.path_map[path].push(move_out);
+ self.builder.data.loc_map[self.loc].push(move_out);
+ }
+
+ fn gather_init(&mut self, place: PlaceRef<'tcx>, kind: InitKind) {
+ debug!("gather_init({:?}, {:?})", self.loc, place);
+
+ if let Some(new_place) = self.builder.un_derefer.derefer(place, self.builder.body) {
+ self.gather_init(new_place.as_ref(), kind);
+ return;
+ }
+
+ let mut place = place;
+
+ // Check if we are assigning into a field of a union, if so, lookup the place
+ // of the union so it is marked as initialized again.
+ if let Some((place_base, ProjectionElem::Field(_, _))) = place.last_projection() {
+ if place_base.ty(self.builder.body, self.builder.tcx).ty.is_union() {
+ place = place_base;
+ }
+ }
+
+ if let LookupResult::Exact(path) = self.builder.data.rev_lookup.find(place) {
+ let init = self.builder.data.inits.push(Init {
+ location: InitLocation::Statement(self.loc),
+ path,
+ kind,
+ });
+
+ debug!(
+ "gather_init({:?}, {:?}): adding init {:?} of {:?}",
+ self.loc, place, init, path
+ );
+
+ self.builder.data.init_path_map[path].push(init);
+ self.builder.data.init_loc_map[self.loc].push(init);
+ }
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-02 20:01:56 +0000