src/librustc/ich/hcx.rs

   1 use crate::hir::map::definitions::{DefPathHash, Definitions};
   2 use crate::ich::{self, CachingSourceMapView};
   3 use crate::middle::cstore::CrateStore;
   4 use crate::ty::{fast_reject, TyCtxt};
   5
   6 use rustc_ast::ast;
   7 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
   8 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
   9 use rustc_data_structures::sync::Lrc;
  10 use rustc_hir as hir;
  11 use rustc_hir::def_id::{DefId, LocalDefId};
  12 use rustc_session::Session;
  13 use rustc_span::source_map::SourceMap;
  14 use rustc_span::symbol::Symbol;
  15 use rustc_span::{BytePos, SourceFile};
  16
  17 use smallvec::SmallVec;
  18 use std::cmp::Ord;
  19
  20 fn compute_ignored_attr_names() -> FxHashSet<Symbol> {
  21     debug_assert!(!ich::IGNORED_ATTRIBUTES.is_empty());
  22     ich::IGNORED_ATTRIBUTES.iter().copied().collect()
  23 }
  24
  25 /// This is the context state available during incr. comp. hashing. It contains
  26 /// enough information to transform `DefId`s and `HirId`s into stable `DefPath`s (i.e.,
  27 /// a reference to the `TyCtxt`) and it holds a few caches for speeding up various
  28 /// things (e.g., each `DefId`/`DefPath` is only hashed once).
  29 #[derive(Clone)]
  30 pub struct StableHashingContext<'a> {
  31     sess: &'a Session,
  32     definitions: &'a Definitions,
  33     cstore: &'a dyn CrateStore,
  34     pub(super) body_resolver: BodyResolver<'a>,
  35     hash_spans: bool,
  36     hash_bodies: bool,
  37     pub(super) node_id_hashing_mode: NodeIdHashingMode,
  38
  39     // Very often, we are hashing something that does not need the
  40     // `CachingSourceMapView`, so we initialize it lazily.
  41     raw_source_map: &'a SourceMap,
  42     caching_source_map: Option<CachingSourceMapView<'a>>,
  43 }
  44
  45 #[derive(PartialEq, Eq, Clone, Copy)]
  46 pub enum NodeIdHashingMode {
  47     Ignore,
  48     HashDefPath,
  49 }
  50
  51 /// The `BodyResolver` allows mapping a `BodyId` to the corresponding `hir::Body`.
  52 /// We could also just store a plain reference to the `hir::Crate` but we want
  53 /// to avoid that the crate is used to get untracked access to all of the HIR.
  54 #[derive(Clone, Copy)]
  55 pub(super) struct BodyResolver<'tcx>(&'tcx hir::Crate<'tcx>);
  56
  57 impl<'tcx> BodyResolver<'tcx> {
  58     /// Returns a reference to the `hir::Body` with the given `BodyId`.
  59     /// **Does not do any tracking**; use carefully.
  60     pub(super) fn body(self, id: hir::BodyId) -> &'tcx hir::Body<'tcx> {
  61         self.0.body(id)
  62     }
  63 }
  64
  65 impl<'a> StableHashingContext<'a> {
  66     /// The `krate` here is only used for mapping `BodyId`s to `Body`s.
  67     /// Don't use it for anything else or you'll run the risk of
  68     /// leaking data out of the tracking system.
  69     #[inline]
  70     pub fn new(
  71         sess: &'a Session,
  72         krate: &'a hir::Crate<'a>,
  73         definitions: &'a Definitions,
  74         cstore: &'a dyn CrateStore,
  75     ) -> Self {
  76         let hash_spans_initial = !sess.opts.debugging_opts.incremental_ignore_spans;
  77
  78         StableHashingContext {
  79             sess,
  80             body_resolver: BodyResolver(krate),
  81             definitions,
  82             cstore,
  83             caching_source_map: None,
  84             raw_source_map: sess.source_map(),
  85             hash_spans: hash_spans_initial,
  86             hash_bodies: true,
  87             node_id_hashing_mode: NodeIdHashingMode::HashDefPath,
  88         }
  89     }
  90
  91     #[inline]
  92     pub fn sess(&self) -> &'a Session {
  93         self.sess
  94     }
  95
  96     #[inline]
  97     pub fn while_hashing_hir_bodies<F: FnOnce(&mut Self)>(&mut self, hash_bodies: bool, f: F) {
  98         let prev_hash_bodies = self.hash_bodies;
  99         self.hash_bodies = hash_bodies;
 100         f(self);
 101         self.hash_bodies = prev_hash_bodies;
 102     }
 103
 104     #[inline]
 105     pub fn while_hashing_spans<F: FnOnce(&mut Self)>(&mut self, hash_spans: bool, f: F) {
 106         let prev_hash_spans = self.hash_spans;
 107         self.hash_spans = hash_spans;
 108         f(self);
 109         self.hash_spans = prev_hash_spans;
 110     }
 111
 112     #[inline]
 113     pub fn with_node_id_hashing_mode<F: FnOnce(&mut Self)>(
 114         &mut self,
 115         mode: NodeIdHashingMode,
 116         f: F,
 117     ) {
 118         let prev = self.node_id_hashing_mode;
 119         self.node_id_hashing_mode = mode;
 120         f(self);
 121         self.node_id_hashing_mode = prev;
 122     }
 123
 124     #[inline]
 125     pub fn def_path_hash(&self, def_id: DefId) -> DefPathHash {
 126         if let Some(def_id) = def_id.as_local() {
 127             self.local_def_path_hash(def_id)
 128         } else {
 129             self.cstore.def_path_hash(def_id)
 130         }
 131     }
 132
 133     #[inline]
 134     pub fn local_def_path_hash(&self, def_id: LocalDefId) -> DefPathHash {
 135         self.definitions.def_path_hash(def_id)
 136     }
 137
 138     #[inline]
 139     pub fn node_to_hir_id(&self, node_id: ast::NodeId) -> hir::HirId {
 140         self.definitions.node_to_hir_id(node_id)
 141     }
 142
 143     #[inline]
 144     pub fn hash_bodies(&self) -> bool {
 145         self.hash_bodies
 146     }
 147
 148     #[inline]
 149     pub fn source_map(&mut self) -> &mut CachingSourceMapView<'a> {
 150         match self.caching_source_map {
 151             Some(ref mut sm) => sm,
 152             ref mut none => {
 153                 *none = Some(CachingSourceMapView::new(self.raw_source_map));
 154                 none.as_mut().unwrap()
 155             }
 156         }
 157     }
 158
 159     #[inline]
 160     pub fn is_ignored_attr(&self, name: Symbol) -> bool {
 161         thread_local! {
 162             static IGNORED_ATTRIBUTES: FxHashSet<Symbol> = compute_ignored_attr_names();
 163         }
 164         IGNORED_ATTRIBUTES.with(|attrs| attrs.contains(&name))
 165     }
 166 }
 167
 168 /// Something that can provide a stable hashing context.
 169 pub trait StableHashingContextProvider<'a> {
 170     fn get_stable_hashing_context(&self) -> StableHashingContext<'a>;
 171 }
 172
 173 impl<'a, 'b, T: StableHashingContextProvider<'a>> StableHashingContextProvider<'a> for &'b T {
 174     fn get_stable_hashing_context(&self) -> StableHashingContext<'a> {
 175         (**self).get_stable_hashing_context()
 176     }
 177 }
 178
 179 impl<'a, 'b, T: StableHashingContextProvider<'a>> StableHashingContextProvider<'a> for &'b mut T {
 180     fn get_stable_hashing_context(&self) -> StableHashingContext<'a> {
 181         (**self).get_stable_hashing_context()
 182     }
 183 }
 184
 185 impl StableHashingContextProvider<'tcx> for TyCtxt<'tcx> {
 186     fn get_stable_hashing_context(&self) -> StableHashingContext<'tcx> {
 187         (*self).create_stable_hashing_context()
 188     }
 189 }
 190
 191 impl<'a> StableHashingContextProvider<'a> for StableHashingContext<'a> {
 192     fn get_stable_hashing_context(&self) -> StableHashingContext<'a> {
 193         self.clone()
 194     }
 195 }
 196
 197 impl<'a> crate::dep_graph::DepGraphSafe for StableHashingContext<'a> {}
 198
 199 impl<'a> HashStable<StableHashingContext<'a>> for ast::NodeId {
 200     fn hash_stable(&self, _: &mut StableHashingContext<'a>, _: &mut StableHasher) {
 201         panic!("Node IDs should not appear in incremental state");
 202     }
 203 }
 204
 205 impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> {
 206     fn hash_spans(&self) -> bool {
 207         self.hash_spans
 208     }
 209
 210     #[inline]
 211     fn hash_def_id(&mut self, def_id: DefId, hasher: &mut StableHasher) {
 212         let hcx = self;
 213         hcx.def_path_hash(def_id).hash_stable(hcx, hasher);
 214     }
 215
 216     fn byte_pos_to_line_and_col(
 217         &mut self,
 218         byte: BytePos,
 219     ) -> Option<(Lrc<SourceFile>, usize, BytePos)> {
 220         self.source_map().byte_pos_to_line_and_col(byte)
 221     }
 222 }
 223
 224 pub fn hash_stable_trait_impls<'a>(
 225     hcx: &mut StableHashingContext<'a>,
 226     hasher: &mut StableHasher,
 227     blanket_impls: &[DefId],
 228     non_blanket_impls: &FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>,
 229 ) {
 230     {
 231         let mut blanket_impls: SmallVec<[_; 8]> =
 232             blanket_impls.iter().map(|&def_id| hcx.def_path_hash(def_id)).collect();
 233
 234         if blanket_impls.len() > 1 {
 235             blanket_impls.sort_unstable();
 236         }
 237
 238         blanket_impls.hash_stable(hcx, hasher);
 239     }
 240
 241     {
 242         let mut keys: SmallVec<[_; 8]> =
 243             non_blanket_impls.keys().map(|k| (k, k.map_def(|d| hcx.def_path_hash(d)))).collect();
 244         keys.sort_unstable_by(|&(_, ref k1), &(_, ref k2)| k1.cmp(k2));
 245         keys.len().hash_stable(hcx, hasher);
 246         for (key, ref stable_key) in keys {
 247             stable_key.hash_stable(hcx, hasher);
 248             let mut impls: SmallVec<[_; 8]> =
 249                 non_blanket_impls[key].iter().map(|&impl_id| hcx.def_path_hash(impl_id)).collect();
 250
 251             if impls.len() > 1 {
 252                 impls.sort_unstable();
 253             }
 254
 255             impls.hash_stable(hcx, hasher);
 256         }
 257     }
 258 }