src/librustc/ty/maps/plumbing.rs

   1 // Copyright 2012-2015 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.
   4 //
   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.
  10
  11 //! The implementation of the query system itself. Defines the macros
  12 //! that generate the actual methods on tcx which find and execute the
  13 //! provider, manage the caches, and so forth.
  14
  15 use dep_graph::{DepNodeIndex, DepNode, DepKind, DepNodeColor};
  16 use errors::DiagnosticBuilder;
  17 use ty::{TyCtxt};
  18 use ty::maps::Query; // NB: actually generated by the macros in this file
  19 use ty::maps::config::QueryDescription;
  20 use ty::item_path;
  21
  22 use rustc_data_structures::fx::{FxHashMap};
  23 use std::cell::{Ref, RefMut};
  24 use std::marker::PhantomData;
  25 use std::mem;
  26 use syntax_pos::Span;
  27
  28 pub(super) struct QueryMap<'tcx, D: QueryDescription<'tcx>> {
  29     phantom: PhantomData<(D, &'tcx ())>,
  30     pub(super) map: FxHashMap<D::Key, QueryValue<D::Value>>,
  31 }
  32
  33 pub(super) struct QueryValue<T> {
  34     pub(super) value: T,
  35     pub(super) index: DepNodeIndex,
  36 }
  37
  38 impl<T> QueryValue<T> {
  39     pub(super) fn new(value: T,
  40                       dep_node_index: DepNodeIndex)
  41                       -> QueryValue<T> {
  42         QueryValue {
  43             value,
  44             index: dep_node_index,
  45         }
  46     }
  47 }
  48
  49 impl<'tcx, M: QueryDescription<'tcx>> QueryMap<'tcx, M> {
  50     pub(super) fn new() -> QueryMap<'tcx, M> {
  51         QueryMap {
  52             phantom: PhantomData,
  53             map: FxHashMap(),
  54         }
  55     }
  56 }
  57
  58 pub(super) trait GetCacheInternal<'tcx>: QueryDescription<'tcx> + Sized {
  59     fn get_cache_internal<'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>)
  60                               -> Ref<'a, QueryMap<'tcx, Self>>;
  61 }
  62
  63 pub(super) struct CycleError<'a, 'tcx: 'a> {
  64     span: Span,
  65     cycle: RefMut<'a, [(Span, Query<'tcx>)]>,
  66 }
  67
  68 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
  69     pub(super) fn report_cycle(self, CycleError { span, cycle }: CycleError)
  70         -> DiagnosticBuilder<'a>
  71     {
  72         // Subtle: release the refcell lock before invoking `describe()`
  73         // below by dropping `cycle`.
  74         let stack = cycle.to_vec();
  75         mem::drop(cycle);
  76
  77         assert!(!stack.is_empty());
  78
  79         // Disable naming impls with types in this path, since that
  80         // sometimes cycles itself, leading to extra cycle errors.
  81         // (And cycle errors around impls tend to occur during the
  82         // collect/coherence phases anyhow.)
  83         item_path::with_forced_impl_filename_line(|| {
  84             let span = self.sess.codemap().def_span(span);
  85             let mut err =
  86                 struct_span_err!(self.sess, span, E0391,
  87                                  "unsupported cyclic reference between types/traits detected");
  88             err.span_label(span, "cyclic reference");
  89
  90             err.span_note(self.sess.codemap().def_span(stack[0].0),
  91                           &format!("the cycle begins when {}...", stack[0].1.describe(self)));
  92
  93             for &(span, ref query) in &stack[1..] {
  94                 err.span_note(self.sess.codemap().def_span(span),
  95                               &format!("...which then requires {}...", query.describe(self)));
  96             }
  97
  98             err.note(&format!("...which then again requires {}, completing the cycle.",
  99                               stack[0].1.describe(self)));
 100
 101             return err
 102         })
 103     }
 104
 105     pub(super) fn cycle_check<F, R>(self, span: Span, query: Query<'gcx>, compute: F)
 106                                     -> Result<R, CycleError<'a, 'gcx>>
 107         where F: FnOnce() -> R
 108     {
 109         {
 110             let mut stack = self.maps.query_stack.borrow_mut();
 111             if let Some((i, _)) = stack.iter().enumerate().rev()
 112                                        .find(|&(_, &(_, ref q))| *q == query) {
 113                 return Err(CycleError {
 114                     span,
 115                     cycle: RefMut::map(stack, |stack| &mut stack[i..])
 116                 });
 117             }
 118             stack.push((span, query));
 119         }
 120
 121         let result = compute();
 122
 123         self.maps.query_stack.borrow_mut().pop();
 124
 125         Ok(result)
 126     }
 127
 128     /// Try to read a node index for the node dep_node.
 129     /// A node will have an index, when it's already been marked green, or when we can mark it
 130     /// green. This function will mark the current task as a reader of the specified node, when
 131     /// the a node index can be found for that node.
 132     pub(super) fn try_mark_green_and_read(self, dep_node: &DepNode) -> Option<DepNodeIndex> {
 133         match self.dep_graph.node_color(dep_node) {
 134             Some(DepNodeColor::Green(dep_node_index)) => {
 135                 self.dep_graph.read_index(dep_node_index);
 136                 Some(dep_node_index)
 137             }
 138             Some(DepNodeColor::Red) => {
 139                 None
 140             }
 141             None => {
 142                 // try_mark_green (called below) will panic when full incremental
 143                 // compilation is disabled. If that's the case, we can't try to mark nodes
 144                 // as green anyway, so we can safely return None here.
 145                 if !self.dep_graph.is_fully_enabled() {
 146                     return None;
 147                 }
 148                 match self.dep_graph.try_mark_green(self.global_tcx(), &dep_node) {
 149                     Some(dep_node_index) => {
 150                         debug_assert!(self.dep_graph.is_green(dep_node_index));
 151                         self.dep_graph.read_index(dep_node_index);
 152                         Some(dep_node_index)
 153                     }
 154                     None => {
 155                         None
 156                     }
 157                 }
 158             }
 159         }
 160     }
 161 }
 162
 163 // If enabled, send a message to the profile-queries thread
 164 macro_rules! profq_msg {
 165     ($tcx:expr, $msg:expr) => {
 166         if cfg!(debug_assertions) {
 167             if  $tcx.sess.profile_queries() {
 168                 profq_msg($msg)
 169             }
 170         }
 171     }
 172 }
 173
 174 // If enabled, format a key using its debug string, which can be
 175 // expensive to compute (in terms of time).
 176 macro_rules! profq_key {
 177     ($tcx:expr, $key:expr) => {
 178         if cfg!(debug_assertions) {
 179             if $tcx.sess.profile_queries_and_keys() {
 180                 Some(format!("{:?}", $key))
 181             } else { None }
 182         } else { None }
 183     }
 184 }
 185
 186 macro_rules! define_maps {
 187     (<$tcx:tt>
 188      $($(#[$attr:meta])*
 189        [$($modifiers:tt)*] fn $name:ident: $node:ident($K:ty) -> $V:ty,)*) => {
 190
 191         use dep_graph::DepNodeIndex;
 192         use std::cell::RefCell;
 193
 194         define_map_struct! {
 195             tcx: $tcx,
 196             input: ($(([$($modifiers)*] [$($attr)*] [$name]))*)
 197         }
 198
 199         impl<$tcx> Maps<$tcx> {
 200             pub fn new(providers: IndexVec<CrateNum, Providers<$tcx>>)
 201                        -> Self {
 202                 Maps {
 203                     providers,
 204                     query_stack: RefCell::new(vec![]),
 205                     $($name: RefCell::new(QueryMap::new())),*
 206                 }
 207             }
 208         }
 209
 210         #[allow(bad_style)]
 211         #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 212         pub enum Query<$tcx> {
 213             $($(#[$attr])* $name($K)),*
 214         }
 215
 216         #[allow(bad_style)]
 217         #[derive(Clone, Debug, PartialEq, Eq)]
 218         pub enum QueryMsg {
 219             $($name(Option<String>)),*
 220         }
 221
 222         impl<$tcx> Query<$tcx> {
 223             pub fn describe(&self, tcx: TyCtxt) -> String {
 224                 let (r, name) = match *self {
 225                     $(Query::$name(key) => {
 226                         (queries::$name::describe(tcx, key), stringify!($name))
 227                     })*
 228                 };
 229                 if tcx.sess.verbose() {
 230                     format!("{} [{}]", r, name)
 231                 } else {
 232                     r
 233                 }
 234             }
 235         }
 236
 237         pub mod queries {
 238             use std::marker::PhantomData;
 239
 240             $(#[allow(bad_style)]
 241             pub struct $name<$tcx> {
 242                 data: PhantomData<&$tcx ()>
 243             })*
 244         }
 245
 246         $(impl<$tcx> QueryConfig for queries::$name<$tcx> {
 247             type Key = $K;
 248             type Value = $V;
 249         }
 250
 251         impl<$tcx> GetCacheInternal<$tcx> for queries::$name<$tcx> {
 252             fn get_cache_internal<'a>(tcx: TyCtxt<'a, $tcx, $tcx>)
 253                                       -> ::std::cell::Ref<'a, QueryMap<$tcx, Self>> {
 254                 tcx.maps.$name.borrow()
 255             }
 256         }
 257
 258         impl<'a, $tcx, 'lcx> queries::$name<$tcx> {
 259
 260             #[allow(unused)]
 261             fn to_dep_node(tcx: TyCtxt<'a, $tcx, 'lcx>, key: &$K) -> DepNode {
 262                 use dep_graph::DepConstructor::*;
 263
 264                 DepNode::new(tcx, $node(*key))
 265             }
 266
 267             fn try_get_with(tcx: TyCtxt<'a, $tcx, 'lcx>,
 268                             mut span: Span,
 269                             key: $K)
 270                             -> Result<$V, CycleError<'a, $tcx>>
 271             {
 272                 debug!("ty::queries::{}::try_get_with(key={:?}, span={:?})",
 273                        stringify!($name),
 274                        key,
 275                        span);
 276
 277                 profq_msg!(tcx,
 278                     ProfileQueriesMsg::QueryBegin(
 279                         span.data(),
 280                         QueryMsg::$name(profq_key!(tcx, key))
 281                     )
 282                 );
 283
 284                 if let Some(value) = tcx.maps.$name.borrow().map.get(&key) {
 285                     profq_msg!(tcx, ProfileQueriesMsg::CacheHit);
 286                     tcx.dep_graph.read_index(value.index);
 287                     return Ok((&value.value).clone());
 288                 }
 289
 290                 // FIXME(eddyb) Get more valid Span's on queries.
 291                 // def_span guard is necessary to prevent a recursive loop,
 292                 // default_span calls def_span query internally.
 293                 if span == DUMMY_SP && stringify!($name) != "def_span" {
 294                     span = key.default_span(tcx)
 295                 }
 296
 297                 // Fast path for when incr. comp. is off. `to_dep_node` is
 298                 // expensive for some DepKinds.
 299                 if !tcx.dep_graph.is_fully_enabled() {
 300                     let null_dep_node = DepNode::new_no_params(::dep_graph::DepKind::Null);
 301                     return Self::force(tcx, key, span, null_dep_node)
 302                                 .map(|(v, _)| v);
 303                 }
 304
 305                 let dep_node = Self::to_dep_node(tcx, &key);
 306
 307                 if dep_node.kind.is_anon() {
 308                     profq_msg!(tcx, ProfileQueriesMsg::ProviderBegin);
 309
 310                     let res = tcx.cycle_check(span, Query::$name(key), || {
 311                         tcx.sess.diagnostic().track_diagnostics(|| {
 312                             tcx.dep_graph.with_anon_task(dep_node.kind, || {
 313                                 Self::compute_result(tcx.global_tcx(), key)
 314                             })
 315                         })
 316                     })?;
 317
 318                     profq_msg!(tcx, ProfileQueriesMsg::ProviderEnd);
 319                     let ((result, dep_node_index), diagnostics) = res;
 320
 321                     tcx.dep_graph.read_index(dep_node_index);
 322
 323                     tcx.on_disk_query_result_cache
 324                        .store_diagnostics_for_anon_node(dep_node_index, diagnostics);
 325
 326                     let value = QueryValue::new(result, dep_node_index);
 327
 328                     return Ok((&tcx.maps
 329                                     .$name
 330                                     .borrow_mut()
 331                                     .map
 332                                     .entry(key)
 333                                     .or_insert(value)
 334                                     .value).clone());
 335                 }
 336
 337                 if !dep_node.kind.is_input() {
 338                     if let Some(dep_node_index) = tcx.try_mark_green_and_read(&dep_node) {
 339                         profq_msg!(tcx, ProfileQueriesMsg::CacheHit);
 340                         return Self::load_from_disk_and_cache_in_memory(tcx,
 341                                                                         key,
 342                                                                         span,
 343                                                                         dep_node_index,
 344                                                                         &dep_node)
 345                     }
 346                 }
 347
 348                 match Self::force(tcx, key, span, dep_node) {
 349                     Ok((result, dep_node_index)) => {
 350                         tcx.dep_graph.read_index(dep_node_index);
 351                         Ok(result)
 352                     }
 353                     Err(e) => Err(e)
 354                 }
 355             }
 356
 357             /// Ensure that either this query has all green inputs or been executed.
 358             /// Executing query::ensure(D) is considered a read of the dep-node D.
 359             ///
 360             /// This function is particularly useful when executing passes for their
 361             /// side-effects -- e.g., in order to report errors for erroneous programs.
 362             ///
 363             /// Note: The optimization is only available during incr. comp.
 364             pub fn ensure(tcx: TyCtxt<'a, $tcx, 'lcx>, key: $K) -> () {
 365                 let dep_node = Self::to_dep_node(tcx, &key);
 366
 367                 // Ensuring an "input" or anonymous query makes no sense
 368                 assert!(!dep_node.kind.is_anon());
 369                 assert!(!dep_node.kind.is_input());
 370                 if tcx.try_mark_green_and_read(&dep_node).is_none() {
 371                     // A None return from `try_mark_green_and_read` means that this is either
 372                     // a new dep node or that the dep node has already been marked red.
 373                     // Either way, we can't call `dep_graph.read()` as we don't have the
 374                     // DepNodeIndex. We must invoke the query itself. The performance cost
 375                     // this introduces should be negligible as we'll immediately hit the
 376                     // in-memory cache, or another query down the line will.
 377                     let _ = tcx.$name(key);
 378                 }
 379             }
 380
 381             fn compute_result(tcx: TyCtxt<'a, $tcx, 'lcx>, key: $K) -> $V {
 382                 let provider = tcx.maps.providers[key.map_crate()].$name;
 383                 provider(tcx.global_tcx(), key)
 384             }
 385
 386             fn load_from_disk_and_cache_in_memory(tcx: TyCtxt<'a, $tcx, 'lcx>,
 387                                                   key: $K,
 388                                                   span: Span,
 389                                                   dep_node_index: DepNodeIndex,
 390                                                   dep_node: &DepNode)
 391                                                   -> Result<$V, CycleError<'a, $tcx>>
 392             {
 393                 debug_assert!(tcx.dep_graph.is_green(dep_node_index));
 394
 395                 // First we try to load the result from the on-disk cache
 396                 let result = if Self::cache_on_disk(key) &&
 397                                 tcx.sess.opts.debugging_opts.incremental_queries {
 398                     let prev_dep_node_index =
 399                         tcx.dep_graph.prev_dep_node_index_of(dep_node);
 400                     let result = Self::try_load_from_disk(tcx.global_tcx(),
 401                                                           prev_dep_node_index);
 402
 403                     // We always expect to find a cached result for things that
 404                     // can be forced from DepNode.
 405                     debug_assert!(!dep_node.kind.can_reconstruct_query_key() ||
 406                                   result.is_some(),
 407                                   "Missing on-disk cache entry for {:?}",
 408                                   dep_node);
 409                     result
 410                 } else {
 411                     // Some things are never cached on disk.
 412                     None
 413                 };
 414
 415                 let result = if let Some(result) = result {
 416                     result
 417                 } else {
 418                     // We could not load a result from the on-disk cache, so
 419                     // recompute.
 420                     let (result, _ ) = tcx.cycle_check(span, Query::$name(key), || {
 421                         // The diagnostics for this query have already been
 422                         // promoted to the current session during
 423                         // try_mark_green(), so we can ignore them here.
 424                         tcx.sess.diagnostic().track_diagnostics(|| {
 425                             // The dep-graph for this computation is already in
 426                             // place
 427                             tcx.dep_graph.with_ignore(|| {
 428                                 Self::compute_result(tcx, key)
 429                             })
 430                         })
 431                     })?;
 432                     result
 433                 };
 434
 435                 // If -Zincremental-verify-ich is specified, re-hash results from
 436                 // the cache and make sure that they have the expected fingerprint.
 437                 if tcx.sess.opts.debugging_opts.incremental_verify_ich {
 438                     use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
 439                     use ich::Fingerprint;
 440
 441                     assert!(Some(tcx.dep_graph.fingerprint_of(dep_node_index)) ==
 442                             tcx.dep_graph.prev_fingerprint_of(dep_node),
 443                             "Fingerprint for green query instance not loaded \
 444                              from cache: {:?}", dep_node);
 445
 446                     debug!("BEGIN verify_ich({:?})", dep_node);
 447                     let mut hcx = tcx.create_stable_hashing_context();
 448                     let mut hasher = StableHasher::new();
 449
 450                     result.hash_stable(&mut hcx, &mut hasher);
 451
 452                     let new_hash: Fingerprint = hasher.finish();
 453                     debug!("END verify_ich({:?})", dep_node);
 454
 455                     let old_hash = tcx.dep_graph.fingerprint_of(dep_node_index);
 456
 457                     assert!(new_hash == old_hash, "Found unstable fingerprints \
 458                         for {:?}", dep_node);
 459                 }
 460
 461                 if tcx.sess.opts.debugging_opts.query_dep_graph {
 462                     tcx.dep_graph.mark_loaded_from_cache(dep_node_index, true);
 463                 }
 464
 465                 let value = QueryValue::new(result, dep_node_index);
 466
 467                 Ok((&tcx.maps
 468                          .$name
 469                          .borrow_mut()
 470                          .map
 471                          .entry(key)
 472                          .or_insert(value)
 473                          .value).clone())
 474             }
 475
 476             fn force(tcx: TyCtxt<'a, $tcx, 'lcx>,
 477                      key: $K,
 478                      span: Span,
 479                      dep_node: DepNode)
 480                      -> Result<($V, DepNodeIndex), CycleError<'a, $tcx>> {
 481                 debug_assert!(tcx.dep_graph.node_color(&dep_node).is_none());
 482
 483                 profq_msg!(tcx, ProfileQueriesMsg::ProviderBegin);
 484                 let res = tcx.cycle_check(span, Query::$name(key), || {
 485                     tcx.sess.diagnostic().track_diagnostics(|| {
 486                         if dep_node.kind.is_eval_always() {
 487                             tcx.dep_graph.with_eval_always_task(dep_node,
 488                                                                 tcx,
 489                                                                 key,
 490                                                                 Self::compute_result)
 491                         } else {
 492                             tcx.dep_graph.with_task(dep_node,
 493                                                     tcx,
 494                                                     key,
 495                                                     Self::compute_result)
 496                         }
 497                     })
 498                 })?;
 499                 profq_msg!(tcx, ProfileQueriesMsg::ProviderEnd);
 500
 501                 let ((result, dep_node_index), diagnostics) = res;
 502
 503                 if tcx.sess.opts.debugging_opts.query_dep_graph {
 504                     tcx.dep_graph.mark_loaded_from_cache(dep_node_index, false);
 505                 }
 506
 507                 if dep_node.kind != ::dep_graph::DepKind::Null {
 508                     tcx.on_disk_query_result_cache
 509                        .store_diagnostics(dep_node_index, diagnostics);
 510                 }
 511
 512                 let value = QueryValue::new(result, dep_node_index);
 513
 514                 Ok(((&tcx.maps
 515                          .$name
 516                          .borrow_mut()
 517                          .map
 518                          .entry(key)
 519                          .or_insert(value)
 520                          .value).clone(),
 521                    dep_node_index))
 522             }
 523
 524             pub fn try_get(tcx: TyCtxt<'a, $tcx, 'lcx>, span: Span, key: $K)
 525                            -> Result<$V, DiagnosticBuilder<'a>> {
 526                 match Self::try_get_with(tcx, span, key) {
 527                     Ok(e) => Ok(e),
 528                     Err(e) => Err(tcx.report_cycle(e)),
 529                 }
 530             }
 531         })*
 532
 533         #[derive(Copy, Clone)]
 534         pub struct TyCtxtAt<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
 535             pub tcx: TyCtxt<'a, 'gcx, 'tcx>,
 536             pub span: Span,
 537         }
 538
 539         impl<'a, 'gcx, 'tcx> Deref for TyCtxtAt<'a, 'gcx, 'tcx> {
 540             type Target = TyCtxt<'a, 'gcx, 'tcx>;
 541             fn deref(&self) -> &Self::Target {
 542                 &self.tcx
 543             }
 544         }
 545
 546         impl<'a, $tcx, 'lcx> TyCtxt<'a, $tcx, 'lcx> {
 547             /// Return a transparent wrapper for `TyCtxt` which uses
 548             /// `span` as the location of queries performed through it.
 549             pub fn at(self, span: Span) -> TyCtxtAt<'a, $tcx, 'lcx> {
 550                 TyCtxtAt {
 551                     tcx: self,
 552                     span
 553                 }
 554             }
 555
 556             $($(#[$attr])*
 557             pub fn $name(self, key: $K) -> $V {
 558                 self.at(DUMMY_SP).$name(key)
 559             })*
 560         }
 561
 562         impl<'a, $tcx, 'lcx> TyCtxtAt<'a, $tcx, 'lcx> {
 563             $($(#[$attr])*
 564             pub fn $name(self, key: $K) -> $V {
 565                 queries::$name::try_get(self.tcx, self.span, key).unwrap_or_else(|mut e| {
 566                     e.emit();
 567                     Value::from_cycle_error(self.global_tcx())
 568                 })
 569             })*
 570         }
 571
 572         define_provider_struct! {
 573             tcx: $tcx,
 574             input: ($(([$($modifiers)*] [$name] [$K] [$V]))*)
 575         }
 576
 577         impl<$tcx> Copy for Providers<$tcx> {}
 578         impl<$tcx> Clone for Providers<$tcx> {
 579             fn clone(&self) -> Self { *self }
 580         }
 581     }
 582 }
 583
 584 macro_rules! define_map_struct {
 585     (tcx: $tcx:tt,
 586      input: ($(([$(modifiers:tt)*] [$($attr:tt)*] [$name:ident]))*)) => {
 587         pub struct Maps<$tcx> {
 588             providers: IndexVec<CrateNum, Providers<$tcx>>,
 589             query_stack: RefCell<Vec<(Span, Query<$tcx>)>>,
 590             $($(#[$attr])*  $name: RefCell<QueryMap<$tcx, queries::$name<$tcx>>>,)*
 591         }
 592     };
 593 }
 594
 595 macro_rules! define_provider_struct {
 596     (tcx: $tcx:tt,
 597      input: ($(([$($modifiers:tt)*] [$name:ident] [$K:ty] [$R:ty]))*)) => {
 598         pub struct Providers<$tcx> {
 599             $(pub $name: for<'a> fn(TyCtxt<'a, $tcx, $tcx>, $K) -> $R,)*
 600         }
 601
 602         impl<$tcx> Default for Providers<$tcx> {
 603             fn default() -> Self {
 604                 $(fn $name<'a, $tcx>(_: TyCtxt<'a, $tcx, $tcx>, key: $K) -> $R {
 605                     bug!("tcx.maps.{}({:?}) unsupported by its crate",
 606                          stringify!($name), key);
 607                 })*
 608                 Providers { $($name),* }
 609             }
 610         }
 611     };
 612 }
 613
 614
 615 /// The red/green evaluation system will try to mark a specific DepNode in the
 616 /// dependency graph as green by recursively trying to mark the dependencies of
 617 /// that DepNode as green. While doing so, it will sometimes encounter a DepNode
 618 /// where we don't know if it is red or green and we therefore actually have
 619 /// to recompute its value in order to find out. Since the only piece of
 620 /// information that we have at that point is the DepNode we are trying to
 621 /// re-evaluate, we need some way to re-run a query from just that. This is what
 622 /// `force_from_dep_node()` implements.
 623 ///
 624 /// In the general case, a DepNode consists of a DepKind and an opaque
 625 /// GUID/fingerprint that will uniquely identify the node. This GUID/fingerprint
 626 /// is usually constructed by computing a stable hash of the query-key that the
 627 /// DepNode corresponds to. Consequently, it is not in general possible to go
 628 /// back from hash to query-key (since hash functions are not reversible). For
 629 /// this reason `force_from_dep_node()` is expected to fail from time to time
 630 /// because we just cannot find out, from the DepNode alone, what the
 631 /// corresponding query-key is and therefore cannot re-run the query.
 632 ///
 633 /// The system deals with this case letting `try_mark_green` fail which forces
 634 /// the root query to be re-evaluated.
 635 ///
 636 /// Now, if force_from_dep_node() would always fail, it would be pretty useless.
 637 /// Fortunately, we can use some contextual information that will allow us to
 638 /// reconstruct query-keys for certain kinds of DepNodes. In particular, we
 639 /// enforce by construction that the GUID/fingerprint of certain DepNodes is a
 640 /// valid DefPathHash. Since we also always build a huge table that maps every
 641 /// DefPathHash in the current codebase to the corresponding DefId, we have
 642 /// everything we need to re-run the query.
 643 ///
 644 /// Take the `mir_validated` query as an example. Like many other queries, it
 645 /// just has a single parameter: the DefId of the item it will compute the
 646 /// validated MIR for. Now, when we call `force_from_dep_node()` on a dep-node
 647 /// with kind `MirValidated`, we know that the GUID/fingerprint of the dep-node
 648 /// is actually a DefPathHash, and can therefore just look up the corresponding
 649 /// DefId in `tcx.def_path_hash_to_def_id`.
 650 ///
 651 /// When you implement a new query, it will likely have a corresponding new
 652 /// DepKind, and you'll have to support it here in `force_from_dep_node()`. As
 653 /// a rule of thumb, if your query takes a DefId or DefIndex as sole parameter,
 654 /// then `force_from_dep_node()` should not fail for it. Otherwise, you can just
 655 /// add it to the "We don't have enough information to reconstruct..." group in
 656 /// the match below.
 657 pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>,
 658                                            dep_node: &DepNode)
 659                                            -> bool {
 660     use ty::maps::keys::Key;
 661     use hir::def_id::LOCAL_CRATE;
 662
 663     // We must avoid ever having to call force_from_dep_node() for a
 664     // DepNode::CodegenUnit:
 665     // Since we cannot reconstruct the query key of a DepNode::CodegenUnit, we
 666     // would always end up having to evaluate the first caller of the
 667     // `codegen_unit` query that *is* reconstructible. This might very well be
 668     // the `compile_codegen_unit` query, thus re-translating the whole CGU just
 669     // to re-trigger calling the `codegen_unit` query with the right key. At
 670     // that point we would already have re-done all the work we are trying to
 671     // avoid doing in the first place.
 672     // The solution is simple: Just explicitly call the `codegen_unit` query for
 673     // each CGU, right after partitioning. This way `try_mark_green` will always
 674     // hit the cache instead of having to go through `force_from_dep_node`.
 675     // This assertion makes sure, we actually keep applying the solution above.
 676     debug_assert!(dep_node.kind != DepKind::CodegenUnit,
 677                   "calling force_from_dep_node() on DepKind::CodegenUnit");
 678
 679     if !dep_node.kind.can_reconstruct_query_key() {
 680         return false
 681     }
 682
 683     macro_rules! def_id {
 684         () => {
 685             if let Some(def_id) = dep_node.extract_def_id(tcx) {
 686                 def_id
 687             } else {
 688                 // return from the whole function
 689                 return false
 690             }
 691         }
 692     };
 693
 694     macro_rules! krate {
 695         () => { (def_id!()).krate }
 696     };
 697
 698     macro_rules! force {
 699         ($query:ident, $key:expr) => {
 700             {
 701                 use $crate::util::common::{ProfileQueriesMsg, profq_msg};
 702
 703                 // FIXME(eddyb) Get more valid Span's on queries.
 704                 // def_span guard is necessary to prevent a recursive loop,
 705                 // default_span calls def_span query internally.
 706                 let span = if stringify!($query) != "def_span" {
 707                     $key.default_span(tcx)
 708                 } else {
 709                     ::syntax_pos::DUMMY_SP
 710                 };
 711
 712                 profq_msg!(tcx,
 713                     ProfileQueriesMsg::QueryBegin(
 714                         span.data(),
 715                         ::ty::maps::QueryMsg::$query(profq_key!(tcx, $key))
 716                     )
 717                 );
 718
 719                 match ::ty::maps::queries::$query::force(tcx, $key, span, *dep_node) {
 720                     Ok(_) => {},
 721                     Err(e) => {
 722                         tcx.report_cycle(e).emit();
 723                     }
 724                 }
 725             }
 726         }
 727     };
 728
 729     // FIXME(#45015): We should try move this boilerplate code into a macro
 730     //                somehow.
 731     match dep_node.kind {
 732         // These are inputs that are expected to be pre-allocated and that
 733         // should therefore always be red or green already
 734         DepKind::AllLocalTraitImpls |
 735         DepKind::Krate |
 736         DepKind::CrateMetadata |
 737         DepKind::HirBody |
 738         DepKind::Hir |
 739
 740         // This are anonymous nodes
 741         DepKind::TraitSelect |
 742
 743         // We don't have enough information to reconstruct the query key of
 744         // these
 745         DepKind::IsCopy |
 746         DepKind::IsSized |
 747         DepKind::IsFreeze |
 748         DepKind::NeedsDrop |
 749         DepKind::Layout |
 750         DepKind::ConstEval |
 751         DepKind::InstanceSymbolName |
 752         DepKind::MirShim |
 753         DepKind::BorrowCheckKrate |
 754         DepKind::Specializes |
 755         DepKind::ImplementationsOfTrait |
 756         DepKind::TypeParamPredicates |
 757         DepKind::CodegenUnit |
 758         DepKind::CompileCodegenUnit |
 759         DepKind::FulfillObligation |
 760         DepKind::VtableMethods |
 761         DepKind::EraseRegionsTy |
 762         DepKind::NormalizeTy |
 763         DepKind::SubstituteNormalizeAndTestPredicates |
 764
 765         // This one should never occur in this context
 766         DepKind::Null => {
 767             bug!("force_from_dep_node() - Encountered {:?}", dep_node)
 768         }
 769
 770         // These are not queries
 771         DepKind::CoherenceCheckTrait |
 772         DepKind::ItemVarianceConstraints => {
 773             return false
 774         }
 775
 776         DepKind::RegionScopeTree => { force!(region_scope_tree, def_id!()); }
 777
 778         DepKind::Coherence => { force!(crate_inherent_impls, LOCAL_CRATE); }
 779         DepKind::CoherenceInherentImplOverlapCheck => {
 780             force!(crate_inherent_impls_overlap_check, LOCAL_CRATE)
 781         },
 782         DepKind::PrivacyAccessLevels => { force!(privacy_access_levels, LOCAL_CRATE); }
 783         DepKind::MirBuilt => { force!(mir_built, def_id!()); }
 784         DepKind::MirConstQualif => { force!(mir_const_qualif, def_id!()); }
 785         DepKind::MirConst => { force!(mir_const, def_id!()); }
 786         DepKind::MirValidated => { force!(mir_validated, def_id!()); }
 787         DepKind::MirOptimized => { force!(optimized_mir, def_id!()); }
 788
 789         DepKind::BorrowCheck => { force!(borrowck, def_id!()); }
 790         DepKind::MirBorrowCheck => { force!(mir_borrowck, def_id!()); }
 791         DepKind::UnsafetyCheckResult => { force!(unsafety_check_result, def_id!()); }
 792         DepKind::UnsafeDeriveOnReprPacked => { force!(unsafe_derive_on_repr_packed, def_id!()); }
 793         DepKind::Reachability => { force!(reachable_set, LOCAL_CRATE); }
 794         DepKind::MirKeys => { force!(mir_keys, LOCAL_CRATE); }
 795         DepKind::CrateVariances => { force!(crate_variances, LOCAL_CRATE); }
 796         DepKind::AssociatedItems => { force!(associated_item, def_id!()); }
 797         DepKind::TypeOfItem => { force!(type_of, def_id!()); }
 798         DepKind::GenericsOfItem => { force!(generics_of, def_id!()); }
 799         DepKind::PredicatesOfItem => { force!(predicates_of, def_id!()); }
 800         DepKind::InferredOutlivesOf => { force!(inferred_outlives_of, def_id!()); }
 801         DepKind::SuperPredicatesOfItem => { force!(super_predicates_of, def_id!()); }
 802         DepKind::TraitDefOfItem => { force!(trait_def, def_id!()); }
 803         DepKind::AdtDefOfItem => { force!(adt_def, def_id!()); }
 804         DepKind::IsAutoImpl => { force!(is_auto_impl, def_id!()); }
 805         DepKind::ImplTraitRef => { force!(impl_trait_ref, def_id!()); }
 806         DepKind::ImplPolarity => { force!(impl_polarity, def_id!()); }
 807         DepKind::FnSignature => { force!(fn_sig, def_id!()); }
 808         DepKind::CoerceUnsizedInfo => { force!(coerce_unsized_info, def_id!()); }
 809         DepKind::ItemVariances => { force!(variances_of, def_id!()); }
 810         DepKind::IsConstFn => { force!(is_const_fn, def_id!()); }
 811         DepKind::IsForeignItem => { force!(is_foreign_item, def_id!()); }
 812         DepKind::SizedConstraint => { force!(adt_sized_constraint, def_id!()); }
 813         DepKind::DtorckConstraint => { force!(adt_dtorck_constraint, def_id!()); }
 814         DepKind::AdtDestructor => { force!(adt_destructor, def_id!()); }
 815         DepKind::AssociatedItemDefIds => { force!(associated_item_def_ids, def_id!()); }
 816         DepKind::InherentImpls => { force!(inherent_impls, def_id!()); }
 817         DepKind::TypeckBodiesKrate => { force!(typeck_item_bodies, LOCAL_CRATE); }
 818         DepKind::TypeckTables => { force!(typeck_tables_of, def_id!()); }
 819         DepKind::UsedTraitImports => { force!(used_trait_imports, def_id!()); }
 820         DepKind::HasTypeckTables => { force!(has_typeck_tables, def_id!()); }
 821         DepKind::SymbolName => { force!(def_symbol_name, def_id!()); }
 822         DepKind::SpecializationGraph => { force!(specialization_graph_of, def_id!()); }
 823         DepKind::ObjectSafety => { force!(is_object_safe, def_id!()); }
 824         DepKind::TraitImpls => { force!(trait_impls_of, def_id!()); }
 825         DepKind::CheckMatch => { force!(check_match, def_id!()); }
 826
 827         DepKind::ParamEnv => { force!(param_env, def_id!()); }
 828         DepKind::DescribeDef => { force!(describe_def, def_id!()); }
 829         DepKind::DefSpan => { force!(def_span, def_id!()); }
 830         DepKind::LookupStability => { force!(lookup_stability, def_id!()); }
 831         DepKind::LookupDeprecationEntry => {
 832             force!(lookup_deprecation_entry, def_id!());
 833         }
 834         DepKind::ItemBodyNestedBodies => { force!(item_body_nested_bodies, def_id!()); }
 835         DepKind::ConstIsRvaluePromotableToStatic => {
 836             force!(const_is_rvalue_promotable_to_static, def_id!());
 837         }
 838         DepKind::RvaluePromotableMap => { force!(rvalue_promotable_map, def_id!()); }
 839         DepKind::ImplParent => { force!(impl_parent, def_id!()); }
 840         DepKind::TraitOfItem => { force!(trait_of_item, def_id!()); }
 841         DepKind::IsExportedSymbol => { force!(is_exported_symbol, def_id!()); }
 842         DepKind::IsMirAvailable => { force!(is_mir_available, def_id!()); }
 843         DepKind::ItemAttrs => { force!(item_attrs, def_id!()); }
 844         DepKind::FnArgNames => { force!(fn_arg_names, def_id!()); }
 845         DepKind::DylibDepFormats => { force!(dylib_dependency_formats, krate!()); }
 846         DepKind::IsPanicRuntime => { force!(is_panic_runtime, krate!()); }
 847         DepKind::IsCompilerBuiltins => { force!(is_compiler_builtins, krate!()); }
 848         DepKind::HasGlobalAllocator => { force!(has_global_allocator, krate!()); }
 849         DepKind::ExternCrate => { force!(extern_crate, def_id!()); }
 850         DepKind::LintLevels => { force!(lint_levels, LOCAL_CRATE); }
 851         DepKind::InScopeTraits => { force!(in_scope_traits_map, def_id!().index); }
 852         DepKind::ModuleExports => { force!(module_exports, def_id!()); }
 853         DepKind::IsSanitizerRuntime => { force!(is_sanitizer_runtime, krate!()); }
 854         DepKind::IsProfilerRuntime => { force!(is_profiler_runtime, krate!()); }
 855         DepKind::GetPanicStrategy => { force!(panic_strategy, krate!()); }
 856         DepKind::IsNoBuiltins => { force!(is_no_builtins, krate!()); }
 857         DepKind::ImplDefaultness => { force!(impl_defaultness, def_id!()); }
 858         DepKind::ExportedSymbolIds => { force!(exported_symbol_ids, krate!()); }
 859         DepKind::NativeLibraries => { force!(native_libraries, krate!()); }
 860         DepKind::PluginRegistrarFn => { force!(plugin_registrar_fn, krate!()); }
 861         DepKind::DeriveRegistrarFn => { force!(derive_registrar_fn, krate!()); }
 862         DepKind::CrateDisambiguator => { force!(crate_disambiguator, krate!()); }
 863         DepKind::CrateHash => { force!(crate_hash, krate!()); }
 864         DepKind::OriginalCrateName => { force!(original_crate_name, krate!()); }
 865
 866         DepKind::AllTraitImplementations => {
 867             force!(all_trait_implementations, krate!());
 868         }
 869
 870         DepKind::IsDllimportForeignItem => {
 871             force!(is_dllimport_foreign_item, def_id!());
 872         }
 873         DepKind::IsStaticallyIncludedForeignItem => {
 874             force!(is_statically_included_foreign_item, def_id!());
 875         }
 876         DepKind::NativeLibraryKind => { force!(native_library_kind, def_id!()); }
 877         DepKind::LinkArgs => { force!(link_args, LOCAL_CRATE); }
 878
 879         DepKind::ResolveLifetimes => { force!(resolve_lifetimes, krate!()); }
 880         DepKind::NamedRegion => { force!(named_region_map, def_id!().index); }
 881         DepKind::IsLateBound => { force!(is_late_bound_map, def_id!().index); }
 882         DepKind::ObjectLifetimeDefaults => {
 883             force!(object_lifetime_defaults_map, def_id!().index);
 884         }
 885
 886         DepKind::Visibility => { force!(visibility, def_id!()); }
 887         DepKind::DepKind => { force!(dep_kind, krate!()); }
 888         DepKind::CrateName => { force!(crate_name, krate!()); }
 889         DepKind::ItemChildren => { force!(item_children, def_id!()); }
 890         DepKind::ExternModStmtCnum => { force!(extern_mod_stmt_cnum, def_id!()); }
 891         DepKind::GetLangItems => { force!(get_lang_items, LOCAL_CRATE); }
 892         DepKind::DefinedLangItems => { force!(defined_lang_items, krate!()); }
 893         DepKind::MissingLangItems => { force!(missing_lang_items, krate!()); }
 894         DepKind::ExternConstBody => { force!(extern_const_body, def_id!()); }
 895         DepKind::VisibleParentMap => { force!(visible_parent_map, LOCAL_CRATE); }
 896         DepKind::MissingExternCrateItem => {
 897             force!(missing_extern_crate_item, krate!());
 898         }
 899         DepKind::UsedCrateSource => { force!(used_crate_source, krate!()); }
 900         DepKind::PostorderCnums => { force!(postorder_cnums, LOCAL_CRATE); }
 901         DepKind::HasCloneClosures => { force!(has_clone_closures, krate!()); }
 902         DepKind::HasCopyClosures => { force!(has_copy_closures, krate!()); }
 903
 904         DepKind::Freevars => { force!(freevars, def_id!()); }
 905         DepKind::MaybeUnusedTraitImport => {
 906             force!(maybe_unused_trait_import, def_id!());
 907         }
 908         DepKind::MaybeUnusedExternCrates => { force!(maybe_unused_extern_crates, LOCAL_CRATE); }
 909         DepKind::StabilityIndex => { force!(stability_index, LOCAL_CRATE); }
 910         DepKind::AllCrateNums => { force!(all_crate_nums, LOCAL_CRATE); }
 911         DepKind::ExportedSymbols => { force!(exported_symbols, krate!()); }
 912         DepKind::CollectAndPartitionTranslationItems => {
 913             force!(collect_and_partition_translation_items, LOCAL_CRATE);
 914         }
 915         DepKind::ExportName => { force!(export_name, def_id!()); }
 916         DepKind::ContainsExternIndicator => {
 917             force!(contains_extern_indicator, def_id!());
 918         }
 919         DepKind::IsTranslatedFunction => { force!(is_translated_function, def_id!()); }
 920         DepKind::OutputFilenames => { force!(output_filenames, LOCAL_CRATE); }
 921     }
 922
 923     true
 924 }
 925
 926
 927 // FIXME(#45015): Another piece of boilerplate code that could be generated in
 928 //                a combined define_dep_nodes!()/define_maps!() macro.
 929 macro_rules! impl_load_from_cache {
 930     ($($dep_kind:ident => $query_name:ident,)*) => {
 931         impl DepNode {
 932             // Check whether the query invocation corresponding to the given
 933             // DepNode is eligible for on-disk-caching.
 934             pub fn cache_on_disk(&self, tcx: TyCtxt) -> bool {
 935                 use ty::maps::queries;
 936                 use ty::maps::QueryDescription;
 937
 938                 match self.kind {
 939                     $(DepKind::$dep_kind => {
 940                         let def_id = self.extract_def_id(tcx).unwrap();
 941                         queries::$query_name::cache_on_disk(def_id)
 942                     })*
 943                     _ => false
 944                 }
 945             }
 946
 947             // This is method will execute the query corresponding to the given
 948             // DepNode. It is only expected to work for DepNodes where the
 949             // above `cache_on_disk` methods returns true.
 950             // Also, as a sanity check, it expects that the corresponding query
 951             // invocation has been marked as green already.
 952             pub fn load_from_on_disk_cache(&self, tcx: TyCtxt) {
 953                 match self.kind {
 954                     $(DepKind::$dep_kind => {
 955                         debug_assert!(tcx.dep_graph
 956                                          .node_color(self)
 957                                          .map(|c| c.is_green())
 958                                          .unwrap_or(false));
 959
 960                         let def_id = self.extract_def_id(tcx).unwrap();
 961                         let _ = tcx.$query_name(def_id);
 962                     })*
 963                     _ => {
 964                         bug!()
 965                     }
 966                 }
 967             }
 968         }
 969     }
 970 }
 971
 972 impl_load_from_cache!(
 973     TypeckTables => typeck_tables_of,
 974     MirOptimized => optimized_mir,
 975     UnsafetyCheckResult => unsafety_check_result,
 976     BorrowCheck => borrowck,
 977     MirBorrowCheck => mir_borrowck,
 978     MirConstQualif => mir_const_qualif,
 979     SymbolName => def_symbol_name,
 980     ConstIsRvaluePromotableToStatic => const_is_rvalue_promotable_to_static,
 981     ContainsExternIndicator => contains_extern_indicator,
 982     CheckMatch => check_match,
 983 );