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-rw-r--r--compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs61
-rw-r--r--compiler/rustc_mir_dataflow/src/move_paths/builder.rs559
-rw-r--r--compiler/rustc_mir_dataflow/src/move_paths/mod.rs422
3 files changed, 1042 insertions, 0 deletions
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs b/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs
new file mode 100644
index 000000000..28936274b
--- /dev/null
+++ b/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs
@@ -0,0 +1,61 @@
+//! The move-analysis portion of borrowck needs to work in an abstract
+//! domain of lifted `Place`s. Most of the `Place` variants fall into a
+//! one-to-one mapping between the concrete and abstract (e.g., a
+//! field-deref on a local variable, `x.field`, has the same meaning
+//! in both domains). Indexed projections are the exception: `a[x]`
+//! needs to be treated as mapping to the same move path as `a[y]` as
+//! well as `a[13]`, etc.
+//!
+//! (In theory, the analysis could be extended to work with sets of
+//! paths, so that `a[0]` and `a[13]` could be kept distinct, while
+//! `a[x]` would still overlap them both. But that is not this
+//! representation does today.)
+
+use rustc_middle::mir::{Local, Operand, PlaceElem, ProjectionElem};
+use rustc_middle::ty::Ty;
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct AbstractOperand;
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct AbstractType;
+pub type AbstractElem = ProjectionElem<AbstractOperand, AbstractType>;
+
+pub trait Lift {
+ type Abstract;
+ fn lift(&self) -> Self::Abstract;
+}
+impl<'tcx> Lift for Operand<'tcx> {
+ type Abstract = AbstractOperand;
+ fn lift(&self) -> Self::Abstract {
+ AbstractOperand
+ }
+}
+impl Lift for Local {
+ type Abstract = AbstractOperand;
+ fn lift(&self) -> Self::Abstract {
+ AbstractOperand
+ }
+}
+impl<'tcx> Lift for Ty<'tcx> {
+ type Abstract = AbstractType;
+ fn lift(&self) -> Self::Abstract {
+ AbstractType
+ }
+}
+impl<'tcx> Lift for PlaceElem<'tcx> {
+ type Abstract = AbstractElem;
+ fn lift(&self) -> Self::Abstract {
+ match *self {
+ ProjectionElem::Deref => ProjectionElem::Deref,
+ ProjectionElem::Field(f, ty) => ProjectionElem::Field(f, ty.lift()),
+ ProjectionElem::Index(ref i) => ProjectionElem::Index(i.lift()),
+ ProjectionElem::Subslice { from, to, from_end } => {
+ ProjectionElem::Subslice { from, to, from_end }
+ }
+ ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
+ ProjectionElem::ConstantIndex { offset, min_length, from_end }
+ }
+ ProjectionElem::Downcast(a, u) => ProjectionElem::Downcast(a, u),
+ }
+ }
+}
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);
+ }
+ }
+}
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/mod.rs b/compiler/rustc_mir_dataflow/src/move_paths/mod.rs
new file mode 100644
index 000000000..a951c5b0b
--- /dev/null
+++ b/compiler/rustc_mir_dataflow/src/move_paths/mod.rs
@@ -0,0 +1,422 @@
+use crate::move_paths::builder::MoveDat;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_index::vec::IndexVec;
+use rustc_middle::mir::*;
+use rustc_middle::ty::{ParamEnv, Ty, TyCtxt};
+use rustc_span::Span;
+use smallvec::SmallVec;
+
+use std::fmt;
+use std::ops::{Index, IndexMut};
+
+use self::abs_domain::{AbstractElem, Lift};
+
+mod abs_domain;
+
+rustc_index::newtype_index! {
+ pub struct MovePathIndex {
+ DEBUG_FORMAT = "mp{}"
+ }
+}
+
+impl polonius_engine::Atom for MovePathIndex {
+ fn index(self) -> usize {
+ rustc_index::vec::Idx::index(self)
+ }
+}
+
+rustc_index::newtype_index! {
+ pub struct MoveOutIndex {
+ DEBUG_FORMAT = "mo{}"
+ }
+}
+
+rustc_index::newtype_index! {
+ pub struct InitIndex {
+ DEBUG_FORMAT = "in{}"
+ }
+}
+
+impl MoveOutIndex {
+ pub fn move_path_index(self, move_data: &MoveData<'_>) -> MovePathIndex {
+ move_data.moves[self].path
+ }
+}
+
+/// `MovePath` is a canonicalized representation of a path that is
+/// moved or assigned to.
+///
+/// It follows a tree structure.
+///
+/// Given `struct X { m: M, n: N }` and `x: X`, moves like `drop x.m;`
+/// move *out* of the place `x.m`.
+///
+/// The MovePaths representing `x.m` and `x.n` are siblings (that is,
+/// one of them will link to the other via the `next_sibling` field,
+/// and the other will have no entry in its `next_sibling` field), and
+/// they both have the MovePath representing `x` as their parent.
+#[derive(Clone)]
+pub struct MovePath<'tcx> {
+ pub next_sibling: Option<MovePathIndex>,
+ pub first_child: Option<MovePathIndex>,
+ pub parent: Option<MovePathIndex>,
+ pub place: Place<'tcx>,
+}
+
+impl<'tcx> MovePath<'tcx> {
+ /// Returns an iterator over the parents of `self`.
+ pub fn parents<'a>(
+ &self,
+ move_paths: &'a IndexVec<MovePathIndex, MovePath<'tcx>>,
+ ) -> impl 'a + Iterator<Item = (MovePathIndex, &'a MovePath<'tcx>)> {
+ let first = self.parent.map(|mpi| (mpi, &move_paths[mpi]));
+ MovePathLinearIter {
+ next: first,
+ fetch_next: move |_, parent: &MovePath<'_>| {
+ parent.parent.map(|mpi| (mpi, &move_paths[mpi]))
+ },
+ }
+ }
+
+ /// Returns an iterator over the immediate children of `self`.
+ pub fn children<'a>(
+ &self,
+ move_paths: &'a IndexVec<MovePathIndex, MovePath<'tcx>>,
+ ) -> impl 'a + Iterator<Item = (MovePathIndex, &'a MovePath<'tcx>)> {
+ let first = self.first_child.map(|mpi| (mpi, &move_paths[mpi]));
+ MovePathLinearIter {
+ next: first,
+ fetch_next: move |_, child: &MovePath<'_>| {
+ child.next_sibling.map(|mpi| (mpi, &move_paths[mpi]))
+ },
+ }
+ }
+
+ /// Finds the closest descendant of `self` for which `f` returns `true` using a breadth-first
+ /// search.
+ ///
+ /// `f` will **not** be called on `self`.
+ pub fn find_descendant(
+ &self,
+ move_paths: &IndexVec<MovePathIndex, MovePath<'_>>,
+ f: impl Fn(MovePathIndex) -> bool,
+ ) -> Option<MovePathIndex> {
+ let mut todo = if let Some(child) = self.first_child {
+ vec![child]
+ } else {
+ return None;
+ };
+
+ while let Some(mpi) = todo.pop() {
+ if f(mpi) {
+ return Some(mpi);
+ }
+
+ let move_path = &move_paths[mpi];
+ if let Some(child) = move_path.first_child {
+ todo.push(child);
+ }
+
+ // After we've processed the original `mpi`, we should always
+ // traverse the siblings of any of its children.
+ if let Some(sibling) = move_path.next_sibling {
+ todo.push(sibling);
+ }
+ }
+
+ None
+ }
+}
+
+impl<'tcx> fmt::Debug for MovePath<'tcx> {
+ fn fmt(&self, w: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(w, "MovePath {{")?;
+ if let Some(parent) = self.parent {
+ write!(w, " parent: {:?},", parent)?;
+ }
+ if let Some(first_child) = self.first_child {
+ write!(w, " first_child: {:?},", first_child)?;
+ }
+ if let Some(next_sibling) = self.next_sibling {
+ write!(w, " next_sibling: {:?}", next_sibling)?;
+ }
+ write!(w, " place: {:?} }}", self.place)
+ }
+}
+
+impl<'tcx> fmt::Display for MovePath<'tcx> {
+ fn fmt(&self, w: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(w, "{:?}", self.place)
+ }
+}
+
+struct MovePathLinearIter<'a, 'tcx, F> {
+ next: Option<(MovePathIndex, &'a MovePath<'tcx>)>,
+ fetch_next: F,
+}
+
+impl<'a, 'tcx, F> Iterator for MovePathLinearIter<'a, 'tcx, F>
+where
+ F: FnMut(MovePathIndex, &'a MovePath<'tcx>) -> Option<(MovePathIndex, &'a MovePath<'tcx>)>,
+{
+ type Item = (MovePathIndex, &'a MovePath<'tcx>);
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let ret = self.next.take()?;
+ self.next = (self.fetch_next)(ret.0, ret.1);
+ Some(ret)
+ }
+}
+
+#[derive(Debug)]
+pub struct MoveData<'tcx> {
+ pub move_paths: IndexVec<MovePathIndex, MovePath<'tcx>>,
+ pub moves: IndexVec<MoveOutIndex, MoveOut>,
+ /// Each Location `l` is mapped to the MoveOut's that are effects
+ /// of executing the code at `l`. (There can be multiple MoveOut's
+ /// for a given `l` because each MoveOut is associated with one
+ /// particular path being moved.)
+ pub loc_map: LocationMap<SmallVec<[MoveOutIndex; 4]>>,
+ pub path_map: IndexVec<MovePathIndex, SmallVec<[MoveOutIndex; 4]>>,
+ pub rev_lookup: MovePathLookup,
+ pub inits: IndexVec<InitIndex, Init>,
+ /// Each Location `l` is mapped to the Inits that are effects
+ /// of executing the code at `l`.
+ pub init_loc_map: LocationMap<SmallVec<[InitIndex; 4]>>,
+ pub init_path_map: IndexVec<MovePathIndex, SmallVec<[InitIndex; 4]>>,
+}
+
+pub trait HasMoveData<'tcx> {
+ fn move_data(&self) -> &MoveData<'tcx>;
+}
+
+#[derive(Debug)]
+pub struct LocationMap<T> {
+ /// Location-indexed (BasicBlock for outer index, index within BB
+ /// for inner index) map.
+ pub(crate) map: IndexVec<BasicBlock, Vec<T>>,
+}
+
+impl<T> Index<Location> for LocationMap<T> {
+ type Output = T;
+ fn index(&self, index: Location) -> &Self::Output {
+ &self.map[index.block][index.statement_index]
+ }
+}
+
+impl<T> IndexMut<Location> for LocationMap<T> {
+ fn index_mut(&mut self, index: Location) -> &mut Self::Output {
+ &mut self.map[index.block][index.statement_index]
+ }
+}
+
+impl<T> LocationMap<T>
+where
+ T: Default + Clone,
+{
+ fn new(body: &Body<'_>) -> Self {
+ LocationMap {
+ map: body
+ .basic_blocks()
+ .iter()
+ .map(|block| vec![T::default(); block.statements.len() + 1])
+ .collect(),
+ }
+ }
+}
+
+/// `MoveOut` represents a point in a program that moves out of some
+/// L-value; i.e., "creates" uninitialized memory.
+///
+/// With respect to dataflow analysis:
+/// - Generated by moves and declaration of uninitialized variables.
+/// - Killed by assignments to the memory.
+#[derive(Copy, Clone)]
+pub struct MoveOut {
+ /// path being moved
+ pub path: MovePathIndex,
+ /// location of move
+ pub source: Location,
+}
+
+impl fmt::Debug for MoveOut {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(fmt, "{:?}@{:?}", self.path, self.source)
+ }
+}
+
+/// `Init` represents a point in a program that initializes some L-value;
+#[derive(Copy, Clone)]
+pub struct Init {
+ /// path being initialized
+ pub path: MovePathIndex,
+ /// location of initialization
+ pub location: InitLocation,
+ /// Extra information about this initialization
+ pub kind: InitKind,
+}
+
+/// Initializations can be from an argument or from a statement. Arguments
+/// do not have locations, in those cases the `Local` is kept..
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum InitLocation {
+ Argument(Local),
+ Statement(Location),
+}
+
+/// Additional information about the initialization.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum InitKind {
+ /// Deep init, even on panic
+ Deep,
+ /// Only does a shallow init
+ Shallow,
+ /// This doesn't initialize the variable on panic (and a panic is possible).
+ NonPanicPathOnly,
+}
+
+impl fmt::Debug for Init {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(fmt, "{:?}@{:?} ({:?})", self.path, self.location, self.kind)
+ }
+}
+
+impl Init {
+ pub fn span<'tcx>(&self, body: &Body<'tcx>) -> Span {
+ match self.location {
+ InitLocation::Argument(local) => body.local_decls[local].source_info.span,
+ InitLocation::Statement(location) => body.source_info(location).span,
+ }
+ }
+}
+
+/// Tables mapping from a place to its MovePathIndex.
+#[derive(Debug)]
+pub struct MovePathLookup {
+ locals: IndexVec<Local, MovePathIndex>,
+
+ /// projections are made from a base-place and a projection
+ /// elem. The base-place will have a unique MovePathIndex; we use
+ /// the latter as the index into the outer vector (narrowing
+ /// subsequent search so that it is solely relative to that
+ /// base-place). For the remaining lookup, we map the projection
+ /// elem to the associated MovePathIndex.
+ projections: FxHashMap<(MovePathIndex, AbstractElem), MovePathIndex>,
+}
+
+mod builder;
+
+#[derive(Copy, Clone, Debug)]
+pub enum LookupResult {
+ Exact(MovePathIndex),
+ Parent(Option<MovePathIndex>),
+}
+
+impl MovePathLookup {
+ // Unlike the builder `fn move_path_for` below, this lookup
+ // alternative will *not* create a MovePath on the fly for an
+ // unknown place, but will rather return the nearest available
+ // parent.
+ pub fn find(&self, place: PlaceRef<'_>) -> LookupResult {
+ let mut result = self.locals[place.local];
+
+ for elem in place.projection.iter() {
+ if let Some(&subpath) = self.projections.get(&(result, elem.lift())) {
+ result = subpath;
+ } else {
+ return LookupResult::Parent(Some(result));
+ }
+ }
+
+ LookupResult::Exact(result)
+ }
+
+ pub fn find_local(&self, local: Local) -> MovePathIndex {
+ self.locals[local]
+ }
+
+ /// An enumerated iterator of `local`s and their associated
+ /// `MovePathIndex`es.
+ pub fn iter_locals_enumerated(
+ &self,
+ ) -> impl DoubleEndedIterator<Item = (Local, MovePathIndex)> + ExactSizeIterator + '_ {
+ self.locals.iter_enumerated().map(|(l, &idx)| (l, idx))
+ }
+}
+
+#[derive(Debug)]
+pub struct IllegalMoveOrigin<'tcx> {
+ pub location: Location,
+ pub kind: IllegalMoveOriginKind<'tcx>,
+}
+
+#[derive(Debug)]
+pub enum IllegalMoveOriginKind<'tcx> {
+ /// Illegal move due to attempt to move from behind a reference.
+ BorrowedContent {
+ /// The place the reference refers to: if erroneous code was trying to
+ /// move from `(*x).f` this will be `*x`.
+ target_place: Place<'tcx>,
+ },
+
+ /// Illegal move due to attempt to move from field of an ADT that
+ /// implements `Drop`. Rust maintains invariant that all `Drop`
+ /// ADT's remain fully-initialized so that user-defined destructor
+ /// can safely read from all of the ADT's fields.
+ InteriorOfTypeWithDestructor { container_ty: Ty<'tcx> },
+
+ /// Illegal move due to attempt to move out of a slice or array.
+ InteriorOfSliceOrArray { ty: Ty<'tcx>, is_index: bool },
+}
+
+#[derive(Debug)]
+pub enum MoveError<'tcx> {
+ IllegalMove { cannot_move_out_of: IllegalMoveOrigin<'tcx> },
+ UnionMove { path: MovePathIndex },
+}
+
+impl<'tcx> MoveError<'tcx> {
+ fn cannot_move_out_of(location: Location, kind: IllegalMoveOriginKind<'tcx>) -> Self {
+ let origin = IllegalMoveOrigin { location, kind };
+ MoveError::IllegalMove { cannot_move_out_of: origin }
+ }
+}
+
+impl<'tcx> MoveData<'tcx> {
+ pub fn gather_moves(
+ body: &Body<'tcx>,
+ tcx: TyCtxt<'tcx>,
+ param_env: ParamEnv<'tcx>,
+ ) -> MoveDat<'tcx> {
+ builder::gather_moves(body, tcx, param_env)
+ }
+
+ /// For the move path `mpi`, returns the root local variable (if any) that starts the path.
+ /// (e.g., for a path like `a.b.c` returns `Some(a)`)
+ pub fn base_local(&self, mut mpi: MovePathIndex) -> Option<Local> {
+ loop {
+ let path = &self.move_paths[mpi];
+ if let Some(l) = path.place.as_local() {
+ return Some(l);
+ }
+ if let Some(parent) = path.parent {
+ mpi = parent;
+ continue;
+ } else {
+ return None;
+ }
+ }
+ }
+
+ pub fn find_in_move_path_or_its_descendants(
+ &self,
+ root: MovePathIndex,
+ pred: impl Fn(MovePathIndex) -> bool,
+ ) -> Option<MovePathIndex> {
+ if pred(root) {
+ return Some(root);
+ }
+
+ self.move_paths[root].find_descendant(&self.move_paths, pred)
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-18 22:01:14 +0000