1 // Copyright 2012-2016 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
12 use rustc::ty::{self, TyCtxt};
14 use rustc::util::nodemap::FxHashMap;
15 use rustc_data_structures::indexed_vec::{IndexVec};
16 use syntax_pos::{Span};
19 use std::ops::{Index, IndexMut};
21 use self::abs_domain::{AbstractElem, Lift};
25 // This submodule holds some newtype'd Index wrappers that are using
26 // NonZero to ensure that Option<Index> occupies only a single word.
27 // They are in a submodule to impose privacy restrictions; namely, to
28 // ensure that other code does not accidentally access `index.0`
29 // (which is likely to yield a subtle off-by-one error).
30 pub(crate) mod indexes {
32 use core::nonzero::NonZero;
33 use rustc_data_structures::indexed_vec::Idx;
35 macro_rules! new_index {
36 ($Index:ident, $debug_name:expr) => {
37 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
38 pub struct $Index(NonZero<usize>);
41 fn new(idx: usize) -> Self {
42 $Index(NonZero::new(idx + 1).unwrap())
44 fn index(self) -> usize {
49 impl fmt::Debug for $Index {
50 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
51 write!(fmt, "{}{}", $debug_name, self.index())
57 /// Index into MovePathData.move_paths
58 new_index!(MovePathIndex, "mp");
60 /// Index into MoveData.moves.
61 new_index!(MoveOutIndex, "mo");
63 /// Index into MoveData.inits.
64 new_index!(InitIndex, "in");
66 /// Index into Borrows.locations
67 new_index!(BorrowIndex, "bw");
69 /// Index into Reservations/Activations bitvector
70 new_index!(ReserveOrActivateIndex, "ra");
73 pub use self::indexes::MovePathIndex;
74 pub use self::indexes::MoveOutIndex;
75 pub use self::indexes::InitIndex;
78 pub fn move_path_index(&self, move_data: &MoveData) -> MovePathIndex {
79 move_data.moves[*self].path
83 /// `MovePath` is a canonicalized representation of a path that is
84 /// moved or assigned to.
86 /// It follows a tree structure.
88 /// Given `struct X { m: M, n: N }` and `x: X`, moves like `drop x.m;`
89 /// move *out* of the l-value `x.m`.
91 /// The MovePaths representing `x.m` and `x.n` are siblings (that is,
92 /// one of them will link to the other via the `next_sibling` field,
93 /// and the other will have no entry in its `next_sibling` field), and
94 /// they both have the MovePath representing `x` as their parent.
96 pub struct MovePath<'tcx> {
97 pub next_sibling: Option<MovePathIndex>,
98 pub first_child: Option<MovePathIndex>,
99 pub parent: Option<MovePathIndex>,
100 pub place: Place<'tcx>,
103 impl<'tcx> fmt::Debug for MovePath<'tcx> {
104 fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
105 write!(w, "MovePath {{")?;
106 if let Some(parent) = self.parent {
107 write!(w, " parent: {:?},", parent)?;
109 if let Some(first_child) = self.first_child {
110 write!(w, " first_child: {:?},", first_child)?;
112 if let Some(next_sibling) = self.next_sibling {
113 write!(w, " next_sibling: {:?}", next_sibling)?;
115 write!(w, " place: {:?} }}", self.place)
119 impl<'tcx> fmt::Display for MovePath<'tcx> {
120 fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
121 write!(w, "{:?}", self.place)
126 pub struct MoveData<'tcx> {
127 pub move_paths: IndexVec<MovePathIndex, MovePath<'tcx>>,
128 pub moves: IndexVec<MoveOutIndex, MoveOut>,
129 /// Each Location `l` is mapped to the MoveOut's that are effects
130 /// of executing the code at `l`. (There can be multiple MoveOut's
131 /// for a given `l` because each MoveOut is associated with one
132 /// particular path being moved.)
133 pub loc_map: LocationMap<Vec<MoveOutIndex>>,
134 pub path_map: IndexVec<MovePathIndex, Vec<MoveOutIndex>>,
135 pub rev_lookup: MovePathLookup<'tcx>,
136 pub inits: IndexVec<InitIndex, Init>,
137 /// Each Location `l` is mapped to the Inits that are effects
138 /// of executing the code at `l`.
139 pub init_loc_map: LocationMap<Vec<InitIndex>>,
140 pub init_path_map: IndexVec<MovePathIndex, Vec<InitIndex>>,
143 pub trait HasMoveData<'tcx> {
144 fn move_data(&self) -> &MoveData<'tcx>;
148 pub struct LocationMap<T> {
149 /// Location-indexed (BasicBlock for outer index, index within BB
150 /// for inner index) map.
151 pub(crate) map: IndexVec<BasicBlock, Vec<T>>,
154 impl<T> Index<Location> for LocationMap<T> {
156 fn index(&self, index: Location) -> &Self::Output {
157 &self.map[index.block][index.statement_index]
161 impl<T> IndexMut<Location> for LocationMap<T> {
162 fn index_mut(&mut self, index: Location) -> &mut Self::Output {
163 &mut self.map[index.block][index.statement_index]
167 impl<T> LocationMap<T> where T: Default + Clone {
168 fn new(mir: &Mir) -> Self {
170 map: mir.basic_blocks().iter().map(|block| {
171 vec![T::default(); block.statements.len()+1]
177 /// `MoveOut` represents a point in a program that moves out of some
178 /// L-value; i.e., "creates" uninitialized memory.
180 /// With respect to dataflow analysis:
181 /// - Generated by moves and declaration of uninitialized variables.
182 /// - Killed by assignments to the memory.
183 #[derive(Copy, Clone)]
186 pub path: MovePathIndex,
188 pub source: Location,
191 impl fmt::Debug for MoveOut {
192 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
193 write!(fmt, "{:?}@{:?}", self.path, self.source)
197 /// `Init` represents a point in a program that initializes some L-value;
198 #[derive(Copy, Clone)]
200 /// path being initialized
201 pub path: MovePathIndex,
202 /// span of initialization
204 /// Extra information about this initialization
208 /// Additional information about the initialization.
209 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
211 /// Deep init, even on panic
213 /// Only does a shallow init
215 /// This doesn't initialize the variabe on panic (and a panic is possible).
219 impl fmt::Debug for Init {
220 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
221 write!(fmt, "{:?}@{:?} ({:?})", self.path, self.span, self.kind)
225 /// Tables mapping from an l-value to its MovePathIndex.
227 pub struct MovePathLookup<'tcx> {
228 locals: IndexVec<Local, MovePathIndex>,
230 /// projections are made from a base-place and a projection
231 /// elem. The base-place will have a unique MovePathIndex; we use
232 /// the latter as the index into the outer vector (narrowing
233 /// subsequent search so that it is solely relative to that
234 /// base-place). For the remaining lookup, we map the projection
235 /// elem to the associated MovePathIndex.
236 projections: FxHashMap<(MovePathIndex, AbstractElem<'tcx>), MovePathIndex>
241 #[derive(Copy, Clone, Debug)]
242 pub enum LookupResult {
243 Exact(MovePathIndex),
244 Parent(Option<MovePathIndex>)
247 impl<'tcx> MovePathLookup<'tcx> {
248 // Unlike the builder `fn move_path_for` below, this lookup
249 // alternative will *not* create a MovePath on the fly for an
250 // unknown l-value, but will rather return the nearest available
252 pub fn find(&self, place: &Place<'tcx>) -> LookupResult {
254 Place::Local(local) => LookupResult::Exact(self.locals[local]),
255 Place::Static(..) => LookupResult::Parent(None),
256 Place::Projection(ref proj) => {
257 match self.find(&proj.base) {
258 LookupResult::Exact(base_path) => {
259 match self.projections.get(&(base_path, proj.elem.lift())) {
260 Some(&subpath) => LookupResult::Exact(subpath),
261 None => LookupResult::Parent(Some(base_path))
270 pub fn find_local(&self, local: Local) -> MovePathIndex {
276 pub struct IllegalMoveOrigin<'tcx> {
277 pub(crate) span: Span,
278 pub(crate) kind: IllegalMoveOriginKind<'tcx>,
282 pub(crate) enum IllegalMoveOriginKind<'tcx> {
285 InteriorOfTypeWithDestructor { container_ty: ty::Ty<'tcx> },
286 InteriorOfSliceOrArray { ty: ty::Ty<'tcx>, is_index: bool, },
290 pub enum MoveError<'tcx> {
291 IllegalMove { cannot_move_out_of: IllegalMoveOrigin<'tcx> },
292 UnionMove { path: MovePathIndex },
295 impl<'tcx> MoveError<'tcx> {
296 fn cannot_move_out_of(span: Span, kind: IllegalMoveOriginKind<'tcx>) -> Self {
297 let origin = IllegalMoveOrigin { span, kind };
298 MoveError::IllegalMove { cannot_move_out_of: origin }
302 impl<'a, 'gcx, 'tcx> MoveData<'tcx> {
303 pub fn gather_moves(mir: &Mir<'tcx>, tcx: TyCtxt<'a, 'gcx, 'tcx>)
304 -> Result<Self, (Self, Vec<MoveError<'tcx>>)> {
305 builder::gather_moves(mir, tcx)