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!("{:?}", $key))
 181             } else { None }
 182         } else { None }
 183     }
 184 }
 185
 186 macro_rules! handle_cycle_error {
 187     ([][$this: expr]) => {{
 188         Value::from_cycle_error($this.global_tcx())
 189     }};
 190     ([fatal_cycle$(, $modifiers:ident)*][$this:expr]) => {{
 191         $this.tcx.sess.abort_if_errors();
 192         unreachable!();
 193     }};
 194     ([$other:ident$(, $modifiers:ident)*][$($args:tt)*]) => {
 195         handle_cycle_error!([$($modifiers),*][$($args)*])
 196     };
 197 }
 198
 199 macro_rules! define_maps {
 200     (<$tcx:tt>
 201      $($(#[$attr:meta])*
 202        [$($modifiers:tt)*] fn $name:ident: $node:ident($K:ty) -> $V:ty,)*) => {
 203
 204         use dep_graph::DepNodeIndex;
 205         use std::cell::RefCell;
 206
 207         define_map_struct! {
 208             tcx: $tcx,
 209             input: ($(([$($modifiers)*] [$($attr)*] [$name]))*)
 210         }
 211
 212         impl<$tcx> Maps<$tcx> {
 213             pub fn new(providers: IndexVec<CrateNum, Providers<$tcx>>)
 214                        -> Self {
 215                 Maps {
 216                     providers,
 217                     query_stack: RefCell::new(vec![]),
 218                     $($name: RefCell::new(QueryMap::new())),*
 219                 }
 220             }
 221         }
 222
 223         #[allow(bad_style)]
 224         #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 225         pub enum Query<$tcx> {
 226             $($(#[$attr])* $name($K)),*
 227         }
 228
 229         #[allow(bad_style)]
 230         #[derive(Clone, Debug, PartialEq, Eq)]
 231         pub enum QueryMsg {
 232             $($name(Option<String>)),*
 233         }
 234
 235         impl<$tcx> Query<$tcx> {
 236             pub fn describe(&self, tcx: TyCtxt) -> String {
 237                 let (r, name) = match *self {
 238                     $(Query::$name(key) => {
 239                         (queries::$name::describe(tcx, key), stringify!($name))
 240                     })*
 241                 };
 242                 if tcx.sess.verbose() {
 243                     format!("{} [{}]", r, name)
 244                 } else {
 245                     r
 246                 }
 247             }
 248         }
 249
 250         pub mod queries {
 251             use std::marker::PhantomData;
 252
 253             $(#[allow(bad_style)]
 254             pub struct $name<$tcx> {
 255                 data: PhantomData<&$tcx ()>
 256             })*
 257         }
 258
 259         $(impl<$tcx> QueryConfig for queries::$name<$tcx> {
 260             type Key = $K;
 261             type Value = $V;
 262         }
 263
 264         impl<$tcx> GetCacheInternal<$tcx> for queries::$name<$tcx> {
 265             fn get_cache_internal<'a>(tcx: TyCtxt<'a, $tcx, $tcx>)
 266                                       -> ::std::cell::Ref<'a, QueryMap<$tcx, Self>> {
 267                 tcx.maps.$name.borrow()
 268             }
 269         }
 270
 271         impl<'a, $tcx, 'lcx> queries::$name<$tcx> {
 272
 273             #[allow(unused)]
 274             fn to_dep_node(tcx: TyCtxt<'a, $tcx, 'lcx>, key: &$K) -> DepNode {
 275                 use dep_graph::DepConstructor::*;
 276
 277                 DepNode::new(tcx, $node(*key))
 278             }
 279
 280             fn try_get_with(tcx: TyCtxt<'a, $tcx, 'lcx>,
 281                             mut span: Span,
 282                             key: $K)
 283                             -> Result<$V, CycleError<'a, $tcx>>
 284             {
 285                 debug!("ty::queries::{}::try_get_with(key={:?}, span={:?})",
 286                        stringify!($name),
 287                        key,
 288                        span);
 289
 290                 profq_msg!(tcx,
 291                     ProfileQueriesMsg::QueryBegin(
 292                         span.data(),
 293                         QueryMsg::$name(profq_key!(tcx, key))
 294                     )
 295                 );
 296
 297                 if let Some(value) = tcx.maps.$name.borrow().map.get(&key) {
 298                     profq_msg!(tcx, ProfileQueriesMsg::CacheHit);
 299                     tcx.dep_graph.read_index(value.index);
 300                     return Ok((&value.value).clone());
 301                 }
 302
 303                 // FIXME(eddyb) Get more valid Span's on queries.
 304                 // def_span guard is necessary to prevent a recursive loop,
 305                 // default_span calls def_span query internally.
 306                 if span == DUMMY_SP && stringify!($name) != "def_span" {
 307                     span = key.default_span(tcx)
 308                 }
 309
 310                 // Fast path for when incr. comp. is off. `to_dep_node` is
 311                 // expensive for some DepKinds.
 312                 if !tcx.dep_graph.is_fully_enabled() {
 313                     let null_dep_node = DepNode::new_no_params(::dep_graph::DepKind::Null);
 314                     return Self::force(tcx, key, span, null_dep_node)
 315                                 .map(|(v, _)| v);
 316                 }
 317
 318                 let dep_node = Self::to_dep_node(tcx, &key);
 319
 320                 if dep_node.kind.is_anon() {
 321                     profq_msg!(tcx, ProfileQueriesMsg::ProviderBegin);
 322
 323                     let res = tcx.cycle_check(span, Query::$name(key), || {
 324                         tcx.sess.diagnostic().track_diagnostics(|| {
 325                             tcx.dep_graph.with_anon_task(dep_node.kind, || {
 326                                 Self::compute_result(tcx.global_tcx(), key)
 327                             })
 328                         })
 329                     })?;
 330
 331                     profq_msg!(tcx, ProfileQueriesMsg::ProviderEnd);
 332                     let ((result, dep_node_index), diagnostics) = res;
 333
 334                     tcx.dep_graph.read_index(dep_node_index);
 335
 336                     tcx.on_disk_query_result_cache
 337                        .store_diagnostics_for_anon_node(dep_node_index, diagnostics);
 338
 339                     let value = QueryValue::new(result, dep_node_index);
 340
 341                     return Ok((&tcx.maps
 342                                     .$name
 343                                     .borrow_mut()
 344                                     .map
 345                                     .entry(key)
 346                                     .or_insert(value)
 347                                     .value).clone());
 348                 }
 349
 350                 if !dep_node.kind.is_input() {
 351                     if let Some(dep_node_index) = tcx.try_mark_green_and_read(&dep_node) {
 352                         profq_msg!(tcx, ProfileQueriesMsg::CacheHit);
 353                         return Self::load_from_disk_and_cache_in_memory(tcx,
 354                                                                         key,
 355                                                                         span,
 356                                                                         dep_node_index,
 357                                                                         &dep_node)
 358                     }
 359                 }
 360
 361                 match Self::force(tcx, key, span, dep_node) {
 362                     Ok((result, dep_node_index)) => {
 363                         tcx.dep_graph.read_index(dep_node_index);
 364                         Ok(result)
 365                     }
 366                     Err(e) => Err(e)
 367                 }
 368             }
 369
 370             /// Ensure that either this query has all green inputs or been executed.
 371             /// Executing query::ensure(D) is considered a read of the dep-node D.
 372             ///
 373             /// This function is particularly useful when executing passes for their
 374             /// side-effects -- e.g., in order to report errors for erroneous programs.
 375             ///
 376             /// Note: The optimization is only available during incr. comp.
 377             pub fn ensure(tcx: TyCtxt<'a, $tcx, 'lcx>, key: $K) -> () {
 378                 let dep_node = Self::to_dep_node(tcx, &key);
 379
 380                 // Ensuring an "input" or anonymous query makes no sense
 381                 assert!(!dep_node.kind.is_anon());
 382                 assert!(!dep_node.kind.is_input());
 383                 if tcx.try_mark_green_and_read(&dep_node).is_none() {
 384                     // A None return from `try_mark_green_and_read` means that this is either
 385                     // a new dep node or that the dep node has already been marked red.
 386                     // Either way, we can't call `dep_graph.read()` as we don't have the
 387                     // DepNodeIndex. We must invoke the query itself. The performance cost
 388                     // this introduces should be negligible as we'll immediately hit the
 389                     // in-memory cache, or another query down the line will.
 390                     let _ = tcx.$name(key);
 391                 }
 392             }
 393
 394             fn compute_result(tcx: TyCtxt<'a, $tcx, 'lcx>, key: $K) -> $V {
 395                 let provider = tcx.maps.providers[key.map_crate()].$name;
 396                 provider(tcx.global_tcx(), key)
 397             }
 398
 399             fn load_from_disk_and_cache_in_memory(tcx: TyCtxt<'a, $tcx, 'lcx>,
 400                                                   key: $K,
 401                                                   span: Span,
 402                                                   dep_node_index: DepNodeIndex,
 403                                                   dep_node: &DepNode)
 404                                                   -> Result<$V, CycleError<'a, $tcx>>
 405             {
 406                 debug_assert!(tcx.dep_graph.is_green(dep_node_index));
 407
 408                 // First we try to load the result from the on-disk cache
 409                 let result = if Self::cache_on_disk(key) &&
 410                                 tcx.sess.opts.debugging_opts.incremental_queries {
 411                     let prev_dep_node_index =
 412                         tcx.dep_graph.prev_dep_node_index_of(dep_node);
 413                     let result = Self::try_load_from_disk(tcx.global_tcx(),
 414                                                           prev_dep_node_index);
 415
 416                     // We always expect to find a cached result for things that
 417                     // can be forced from DepNode.
 418                     debug_assert!(!dep_node.kind.can_reconstruct_query_key() ||
 419                                   result.is_some(),
 420                                   "Missing on-disk cache entry for {:?}",
 421                                   dep_node);
 422                     result
 423                 } else {
 424                     // Some things are never cached on disk.
 425                     None
 426                 };
 427
 428                 let result = if let Some(result) = result {
 429                     result
 430                 } else {
 431                     // We could not load a result from the on-disk cache, so
 432                     // recompute.
 433                     let (result, _ ) = tcx.cycle_check(span, Query::$name(key), || {
 434                         // The diagnostics for this query have already been
 435                         // promoted to the current session during
 436                         // try_mark_green(), so we can ignore them here.
 437                         tcx.sess.diagnostic().track_diagnostics(|| {
 438                             // The dep-graph for this computation is already in
 439                             // place
 440                             tcx.dep_graph.with_ignore(|| {
 441                                 Self::compute_result(tcx, key)
 442                             })
 443                         })
 444                     })?;
 445                     result
 446                 };
 447
 448                 // If -Zincremental-verify-ich is specified, re-hash results from
 449                 // the cache and make sure that they have the expected fingerprint.
 450                 if tcx.sess.opts.debugging_opts.incremental_verify_ich {
 451                     use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
 452                     use ich::Fingerprint;
 453
 454                     assert!(Some(tcx.dep_graph.fingerprint_of(dep_node_index)) ==
 455                             tcx.dep_graph.prev_fingerprint_of(dep_node),
 456                             "Fingerprint for green query instance not loaded \
 457                              from cache: {:?}", dep_node);
 458
 459                     debug!("BEGIN verify_ich({:?})", dep_node);
 460                     let mut hcx = tcx.create_stable_hashing_context();
 461                     let mut hasher = StableHasher::new();
 462
 463                     result.hash_stable(&mut hcx, &mut hasher);
 464
 465                     let new_hash: Fingerprint = hasher.finish();
 466                     debug!("END verify_ich({:?})", dep_node);
 467
 468                     let old_hash = tcx.dep_graph.fingerprint_of(dep_node_index);
 469
 470                     assert!(new_hash == old_hash, "Found unstable fingerprints \
 471                         for {:?}", dep_node);
 472                 }
 473
 474                 if tcx.sess.opts.debugging_opts.query_dep_graph {
 475                     tcx.dep_graph.mark_loaded_from_cache(dep_node_index, true);
 476                 }
 477
 478                 let value = QueryValue::new(result, dep_node_index);
 479
 480                 Ok((&tcx.maps
 481                          .$name
 482                          .borrow_mut()
 483                          .map
 484                          .entry(key)
 485                          .or_insert(value)
 486                          .value).clone())
 487             }
 488
 489             fn force(tcx: TyCtxt<'a, $tcx, 'lcx>,
 490                      key: $K,
 491                      span: Span,
 492                      dep_node: DepNode)
 493                      -> Result<($V, DepNodeIndex), CycleError<'a, $tcx>> {
 494                 debug_assert!(tcx.dep_graph.node_color(&dep_node).is_none());
 495
 496                 profq_msg!(tcx, ProfileQueriesMsg::ProviderBegin);
 497                 let res = tcx.cycle_check(span, Query::$name(key), || {
 498                     tcx.sess.diagnostic().track_diagnostics(|| {
 499                         if dep_node.kind.is_eval_always() {
 500                             tcx.dep_graph.with_eval_always_task(dep_node,
 501                                                                 tcx,
 502                                                                 key,
 503                                                                 Self::compute_result)
 504                         } else {
 505                             tcx.dep_graph.with_task(dep_node,
 506                                                     tcx,
 507                                                     key,
 508                                                     Self::compute_result)
 509                         }
 510                     })
 511                 })?;
 512                 profq_msg!(tcx, ProfileQueriesMsg::ProviderEnd);
 513
 514                 let ((result, dep_node_index), diagnostics) = res;
 515
 516                 if tcx.sess.opts.debugging_opts.query_dep_graph {
 517                     tcx.dep_graph.mark_loaded_from_cache(dep_node_index, false);
 518                 }
 519
 520                 if dep_node.kind != ::dep_graph::DepKind::Null {
 521                     tcx.on_disk_query_result_cache
 522                        .store_diagnostics(dep_node_index, diagnostics);
 523                 }
 524
 525                 let value = QueryValue::new(result, dep_node_index);
 526
 527                 Ok(((&tcx.maps
 528                          .$name
 529                          .borrow_mut()
 530                          .map
 531                          .entry(key)
 532                          .or_insert(value)
 533                          .value).clone(),
 534                    dep_node_index))
 535             }
 536
 537             pub fn try_get(tcx: TyCtxt<'a, $tcx, 'lcx>, span: Span, key: $K)
 538                            -> Result<$V, DiagnosticBuilder<'a>> {
 539                 match Self::try_get_with(tcx, span, key) {
 540                     Ok(e) => Ok(e),
 541                     Err(e) => Err(tcx.report_cycle(e)),
 542                 }
 543             }
 544         })*
 545
 546         #[derive(Copy, Clone)]
 547         pub struct TyCtxtAt<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
 548             pub tcx: TyCtxt<'a, 'gcx, 'tcx>,
 549             pub span: Span,
 550         }
 551
 552         impl<'a, 'gcx, 'tcx> Deref for TyCtxtAt<'a, 'gcx, 'tcx> {
 553             type Target = TyCtxt<'a, 'gcx, 'tcx>;
 554             fn deref(&self) -> &Self::Target {
 555                 &self.tcx
 556             }
 557         }
 558
 559         impl<'a, $tcx, 'lcx> TyCtxt<'a, $tcx, 'lcx> {
 560             /// Return a transparent wrapper for `TyCtxt` which uses
 561             /// `span` as the location of queries performed through it.
 562             pub fn at(self, span: Span) -> TyCtxtAt<'a, $tcx, 'lcx> {
 563                 TyCtxtAt {
 564                     tcx: self,
 565                     span
 566                 }
 567             }
 568
 569             $($(#[$attr])*
 570             pub fn $name(self, key: $K) -> $V {
 571                 self.at(DUMMY_SP).$name(key)
 572             })*
 573         }
 574
 575         impl<'a, $tcx, 'lcx> TyCtxtAt<'a, $tcx, 'lcx> {
 576             $($(#[$attr])*
 577             pub fn $name(self, key: $K) -> $V {
 578                 queries::$name::try_get(self.tcx, self.span, key).unwrap_or_else(|mut e| {
 579                     e.emit();
 580                     handle_cycle_error!([$($modifiers)*][self])
 581                 })
 582             })*
 583         }
 584
 585         define_provider_struct! {
 586             tcx: $tcx,
 587             input: ($(([$($modifiers)*] [$name] [$K] [$V]))*)
 588         }
 589
 590         impl<$tcx> Copy for Providers<$tcx> {}
 591         impl<$tcx> Clone for Providers<$tcx> {
 592             fn clone(&self) -> Self { *self }
 593         }
 594     }
 595 }
 596
 597 macro_rules! define_map_struct {
 598     (tcx: $tcx:tt,
 599      input: ($(([$($modifiers:tt)*] [$($attr:tt)*] [$name:ident]))*)) => {
 600         pub struct Maps<$tcx> {
 601             providers: IndexVec<CrateNum, Providers<$tcx>>,
 602             query_stack: RefCell<Vec<(Span, Query<$tcx>)>>,
 603             $($(#[$attr])*  $name: RefCell<QueryMap<$tcx, queries::$name<$tcx>>>,)*
 604         }
 605     };
 606 }
 607
 608 macro_rules! define_provider_struct {
 609     (tcx: $tcx:tt,
 610      input: ($(([$($modifiers:tt)*] [$name:ident] [$K:ty] [$R:ty]))*)) => {
 611         pub struct Providers<$tcx> {
 612             $(pub $name: for<'a> fn(TyCtxt<'a, $tcx, $tcx>, $K) -> $R,)*
 613         }
 614
 615         impl<$tcx> Default for Providers<$tcx> {
 616             fn default() -> Self {
 617                 $(fn $name<'a, $tcx>(_: TyCtxt<'a, $tcx, $tcx>, key: $K) -> $R {
 618                     bug!("tcx.maps.{}({:?}) unsupported by its crate",
 619                          stringify!($name), key);
 620                 })*
 621                 Providers { $($name),* }
 622             }
 623         }
 624     };
 625 }
 626
 627
 628 /// The red/green evaluation system will try to mark a specific DepNode in the
 629 /// dependency graph as green by recursively trying to mark the dependencies of
 630 /// that DepNode as green. While doing so, it will sometimes encounter a DepNode
 631 /// where we don't know if it is red or green and we therefore actually have
 632 /// to recompute its value in order to find out. Since the only piece of
 633 /// information that we have at that point is the DepNode we are trying to
 634 /// re-evaluate, we need some way to re-run a query from just that. This is what
 635 /// `force_from_dep_node()` implements.
 636 ///
 637 /// In the general case, a DepNode consists of a DepKind and an opaque
 638 /// GUID/fingerprint that will uniquely identify the node. This GUID/fingerprint
 639 /// is usually constructed by computing a stable hash of the query-key that the
 640 /// DepNode corresponds to. Consequently, it is not in general possible to go
 641 /// back from hash to query-key (since hash functions are not reversible). For
 642 /// this reason `force_from_dep_node()` is expected to fail from time to time
 643 /// because we just cannot find out, from the DepNode alone, what the
 644 /// corresponding query-key is and therefore cannot re-run the query.
 645 ///
 646 /// The system deals with this case letting `try_mark_green` fail which forces
 647 /// the root query to be re-evaluated.
 648 ///
 649 /// Now, if force_from_dep_node() would always fail, it would be pretty useless.
 650 /// Fortunately, we can use some contextual information that will allow us to
 651 /// reconstruct query-keys for certain kinds of DepNodes. In particular, we
 652 /// enforce by construction that the GUID/fingerprint of certain DepNodes is a
 653 /// valid DefPathHash. Since we also always build a huge table that maps every
 654 /// DefPathHash in the current codebase to the corresponding DefId, we have
 655 /// everything we need to re-run the query.
 656 ///
 657 /// Take the `mir_validated` query as an example. Like many other queries, it
 658 /// just has a single parameter: the DefId of the item it will compute the
 659 /// validated MIR for. Now, when we call `force_from_dep_node()` on a dep-node
 660 /// with kind `MirValidated`, we know that the GUID/fingerprint of the dep-node
 661 /// is actually a DefPathHash, and can therefore just look up the corresponding
 662 /// DefId in `tcx.def_path_hash_to_def_id`.
 663 ///
 664 /// When you implement a new query, it will likely have a corresponding new
 665 /// DepKind, and you'll have to support it here in `force_from_dep_node()`. As
 666 /// a rule of thumb, if your query takes a DefId or DefIndex as sole parameter,
 667 /// then `force_from_dep_node()` should not fail for it. Otherwise, you can just
 668 /// add it to the "We don't have enough information to reconstruct..." group in
 669 /// the match below.
 670 pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>,
 671                                            dep_node: &DepNode)
 672                                            -> bool {
 673     use ty::maps::keys::Key;
 674     use hir::def_id::LOCAL_CRATE;
 675
 676     // We must avoid ever having to call force_from_dep_node() for a
 677     // DepNode::CodegenUnit:
 678     // Since we cannot reconstruct the query key of a DepNode::CodegenUnit, we
 679     // would always end up having to evaluate the first caller of the
 680     // `codegen_unit` query that *is* reconstructible. This might very well be
 681     // the `compile_codegen_unit` query, thus re-translating the whole CGU just
 682     // to re-trigger calling the `codegen_unit` query with the right key. At
 683     // that point we would already have re-done all the work we are trying to
 684     // avoid doing in the first place.
 685     // The solution is simple: Just explicitly call the `codegen_unit` query for
 686     // each CGU, right after partitioning. This way `try_mark_green` will always
 687     // hit the cache instead of having to go through `force_from_dep_node`.
 688     // This assertion makes sure, we actually keep applying the solution above.
 689     debug_assert!(dep_node.kind != DepKind::CodegenUnit,
 690                   "calling force_from_dep_node() on DepKind::CodegenUnit");
 691
 692     if !dep_node.kind.can_reconstruct_query_key() {
 693         return false
 694     }
 695
 696     macro_rules! def_id {
 697         () => {
 698             if let Some(def_id) = dep_node.extract_def_id(tcx) {
 699                 def_id
 700             } else {
 701                 // return from the whole function
 702                 return false
 703             }
 704         }
 705     };
 706
 707     macro_rules! krate {
 708         () => { (def_id!()).krate }
 709     };
 710
 711     macro_rules! force {
 712         ($query:ident, $key:expr) => {
 713             {
 714                 use $crate::util::common::{ProfileQueriesMsg, profq_msg};
 715
 716                 // FIXME(eddyb) Get more valid Span's on queries.
 717                 // def_span guard is necessary to prevent a recursive loop,
 718                 // default_span calls def_span query internally.
 719                 let span = if stringify!($query) != "def_span" {
 720                     $key.default_span(tcx)
 721                 } else {
 722                     ::syntax_pos::DUMMY_SP
 723                 };
 724
 725                 profq_msg!(tcx,
 726                     ProfileQueriesMsg::QueryBegin(
 727                         span.data(),
 728                         ::ty::maps::QueryMsg::$query(profq_key!(tcx, $key))
 729                     )
 730                 );
 731
 732                 match ::ty::maps::queries::$query::force(tcx, $key, span, *dep_node) {
 733                     Ok(_) => {},
 734                     Err(e) => {
 735                         tcx.report_cycle(e).emit();
 736                     }
 737                 }
 738             }
 739         }
 740     };
 741
 742     // FIXME(#45015): We should try move this boilerplate code into a macro
 743     //                somehow.
 744     match dep_node.kind {
 745         // These are inputs that are expected to be pre-allocated and that
 746         // should therefore always be red or green already
 747         DepKind::AllLocalTraitImpls |
 748         DepKind::Krate |
 749         DepKind::CrateMetadata |
 750         DepKind::HirBody |
 751         DepKind::Hir |
 752
 753         // This are anonymous nodes
 754         DepKind::TraitSelect |
 755
 756         // We don't have enough information to reconstruct the query key of
 757         // these
 758         DepKind::IsCopy |
 759         DepKind::IsSized |
 760         DepKind::IsFreeze |
 761         DepKind::NeedsDrop |
 762         DepKind::Layout |
 763         DepKind::ConstEval |
 764         DepKind::InstanceSymbolName |
 765         DepKind::MirShim |
 766         DepKind::BorrowCheckKrate |
 767         DepKind::Specializes |
 768         DepKind::ImplementationsOfTrait |
 769         DepKind::TypeParamPredicates |
 770         DepKind::CodegenUnit |
 771         DepKind::CompileCodegenUnit |
 772         DepKind::FulfillObligation |
 773         DepKind::VtableMethods |
 774         DepKind::EraseRegionsTy |
 775         DepKind::NormalizeTy |
 776         DepKind::SubstituteNormalizeAndTestPredicates |
 777         DepKind::InstanceDefSizeEstimate |
 778
 779         // This one should never occur in this context
 780         DepKind::Null => {
 781             bug!("force_from_dep_node() - Encountered {:?}", dep_node)
 782         }
 783
 784         // These are not queries
 785         DepKind::CoherenceCheckTrait |
 786         DepKind::ItemVarianceConstraints => {
 787             return false
 788         }
 789
 790         DepKind::RegionScopeTree => { force!(region_scope_tree, def_id!()); }
 791
 792         DepKind::Coherence => { force!(crate_inherent_impls, LOCAL_CRATE); }
 793         DepKind::CoherenceInherentImplOverlapCheck => {
 794             force!(crate_inherent_impls_overlap_check, LOCAL_CRATE)
 795         },
 796         DepKind::PrivacyAccessLevels => { force!(privacy_access_levels, LOCAL_CRATE); }
 797         DepKind::MirBuilt => { force!(mir_built, def_id!()); }
 798         DepKind::MirConstQualif => { force!(mir_const_qualif, def_id!()); }
 799         DepKind::MirConst => { force!(mir_const, def_id!()); }
 800         DepKind::MirValidated => { force!(mir_validated, def_id!()); }
 801         DepKind::MirOptimized => { force!(optimized_mir, def_id!()); }
 802
 803         DepKind::BorrowCheck => { force!(borrowck, def_id!()); }
 804         DepKind::MirBorrowCheck => { force!(mir_borrowck, def_id!()); }
 805         DepKind::UnsafetyCheckResult => { force!(unsafety_check_result, def_id!()); }
 806         DepKind::UnsafeDeriveOnReprPacked => { force!(unsafe_derive_on_repr_packed, def_id!()); }
 807         DepKind::Reachability => { force!(reachable_set, LOCAL_CRATE); }
 808         DepKind::MirKeys => { force!(mir_keys, LOCAL_CRATE); }
 809         DepKind::CrateVariances => { force!(crate_variances, LOCAL_CRATE); }
 810         DepKind::AssociatedItems => { force!(associated_item, def_id!()); }
 811         DepKind::TypeOfItem => { force!(type_of, def_id!()); }
 812         DepKind::GenericsOfItem => { force!(generics_of, def_id!()); }
 813         DepKind::PredicatesOfItem => { force!(predicates_of, def_id!()); }
 814         DepKind::InferredOutlivesOf => { force!(inferred_outlives_of, def_id!()); }
 815         DepKind::SuperPredicatesOfItem => { force!(super_predicates_of, def_id!()); }
 816         DepKind::TraitDefOfItem => { force!(trait_def, def_id!()); }
 817         DepKind::AdtDefOfItem => { force!(adt_def, def_id!()); }
 818         DepKind::ImplTraitRef => { force!(impl_trait_ref, def_id!()); }
 819         DepKind::ImplPolarity => { force!(impl_polarity, def_id!()); }
 820         DepKind::FnSignature => { force!(fn_sig, def_id!()); }
 821         DepKind::CoerceUnsizedInfo => { force!(coerce_unsized_info, def_id!()); }
 822         DepKind::ItemVariances => { force!(variances_of, def_id!()); }
 823         DepKind::IsConstFn => { force!(is_const_fn, def_id!()); }
 824         DepKind::IsForeignItem => { force!(is_foreign_item, def_id!()); }
 825         DepKind::SizedConstraint => { force!(adt_sized_constraint, def_id!()); }
 826         DepKind::DtorckConstraint => { force!(adt_dtorck_constraint, def_id!()); }
 827         DepKind::AdtDestructor => { force!(adt_destructor, def_id!()); }
 828         DepKind::AssociatedItemDefIds => { force!(associated_item_def_ids, def_id!()); }
 829         DepKind::InherentImpls => { force!(inherent_impls, def_id!()); }
 830         DepKind::TypeckBodiesKrate => { force!(typeck_item_bodies, LOCAL_CRATE); }
 831         DepKind::TypeckTables => { force!(typeck_tables_of, def_id!()); }
 832         DepKind::UsedTraitImports => { force!(used_trait_imports, def_id!()); }
 833         DepKind::HasTypeckTables => { force!(has_typeck_tables, def_id!()); }
 834         DepKind::SymbolName => { force!(def_symbol_name, def_id!()); }
 835         DepKind::SpecializationGraph => { force!(specialization_graph_of, def_id!()); }
 836         DepKind::ObjectSafety => { force!(is_object_safe, def_id!()); }
 837         DepKind::TraitImpls => { force!(trait_impls_of, def_id!()); }
 838         DepKind::CheckMatch => { force!(check_match, def_id!()); }
 839
 840         DepKind::ParamEnv => { force!(param_env, def_id!()); }
 841         DepKind::DescribeDef => { force!(describe_def, def_id!()); }
 842         DepKind::DefSpan => { force!(def_span, def_id!()); }
 843         DepKind::LookupStability => { force!(lookup_stability, def_id!()); }
 844         DepKind::LookupDeprecationEntry => {
 845             force!(lookup_deprecation_entry, def_id!());
 846         }
 847         DepKind::ItemBodyNestedBodies => { force!(item_body_nested_bodies, def_id!()); }
 848         DepKind::ConstIsRvaluePromotableToStatic => {
 849             force!(const_is_rvalue_promotable_to_static, def_id!());
 850         }
 851         DepKind::RvaluePromotableMap => { force!(rvalue_promotable_map, def_id!()); }
 852         DepKind::ImplParent => { force!(impl_parent, def_id!()); }
 853         DepKind::TraitOfItem => { force!(trait_of_item, def_id!()); }
 854         DepKind::IsExportedSymbol => { force!(is_exported_symbol, def_id!()); }
 855         DepKind::IsMirAvailable => { force!(is_mir_available, def_id!()); }
 856         DepKind::ItemAttrs => { force!(item_attrs, def_id!()); }
 857         DepKind::FnArgNames => { force!(fn_arg_names, def_id!()); }
 858         DepKind::DylibDepFormats => { force!(dylib_dependency_formats, krate!()); }
 859         DepKind::IsPanicRuntime => { force!(is_panic_runtime, krate!()); }
 860         DepKind::IsCompilerBuiltins => { force!(is_compiler_builtins, krate!()); }
 861         DepKind::HasGlobalAllocator => { force!(has_global_allocator, krate!()); }
 862         DepKind::ExternCrate => { force!(extern_crate, def_id!()); }
 863         DepKind::LintLevels => { force!(lint_levels, LOCAL_CRATE); }
 864         DepKind::InScopeTraits => { force!(in_scope_traits_map, def_id!().index); }
 865         DepKind::ModuleExports => { force!(module_exports, def_id!()); }
 866         DepKind::IsSanitizerRuntime => { force!(is_sanitizer_runtime, krate!()); }
 867         DepKind::IsProfilerRuntime => { force!(is_profiler_runtime, krate!()); }
 868         DepKind::GetPanicStrategy => { force!(panic_strategy, krate!()); }
 869         DepKind::IsNoBuiltins => { force!(is_no_builtins, krate!()); }
 870         DepKind::ImplDefaultness => { force!(impl_defaultness, def_id!()); }
 871         DepKind::ExportedSymbolIds => { force!(exported_symbol_ids, krate!()); }
 872         DepKind::NativeLibraries => { force!(native_libraries, krate!()); }
 873         DepKind::PluginRegistrarFn => { force!(plugin_registrar_fn, krate!()); }
 874         DepKind::DeriveRegistrarFn => { force!(derive_registrar_fn, krate!()); }
 875         DepKind::CrateDisambiguator => { force!(crate_disambiguator, krate!()); }
 876         DepKind::CrateHash => { force!(crate_hash, krate!()); }
 877         DepKind::OriginalCrateName => { force!(original_crate_name, krate!()); }
 878
 879         DepKind::AllTraitImplementations => {
 880             force!(all_trait_implementations, krate!());
 881         }
 882
 883         DepKind::IsDllimportForeignItem => {
 884             force!(is_dllimport_foreign_item, def_id!());
 885         }
 886         DepKind::IsStaticallyIncludedForeignItem => {
 887             force!(is_statically_included_foreign_item, def_id!());
 888         }
 889         DepKind::NativeLibraryKind => { force!(native_library_kind, def_id!()); }
 890         DepKind::LinkArgs => { force!(link_args, LOCAL_CRATE); }
 891
 892         DepKind::ResolveLifetimes => { force!(resolve_lifetimes, krate!()); }
 893         DepKind::NamedRegion => { force!(named_region_map, def_id!().index); }
 894         DepKind::IsLateBound => { force!(is_late_bound_map, def_id!().index); }
 895         DepKind::ObjectLifetimeDefaults => {
 896             force!(object_lifetime_defaults_map, def_id!().index);
 897         }
 898
 899         DepKind::Visibility => { force!(visibility, def_id!()); }
 900         DepKind::DepKind => { force!(dep_kind, krate!()); }
 901         DepKind::CrateName => { force!(crate_name, krate!()); }
 902         DepKind::ItemChildren => { force!(item_children, def_id!()); }
 903         DepKind::ExternModStmtCnum => { force!(extern_mod_stmt_cnum, def_id!()); }
 904         DepKind::GetLangItems => { force!(get_lang_items, LOCAL_CRATE); }
 905         DepKind::DefinedLangItems => { force!(defined_lang_items, krate!()); }
 906         DepKind::MissingLangItems => { force!(missing_lang_items, krate!()); }
 907         DepKind::ExternConstBody => { force!(extern_const_body, def_id!()); }
 908         DepKind::VisibleParentMap => { force!(visible_parent_map, LOCAL_CRATE); }
 909         DepKind::MissingExternCrateItem => {
 910             force!(missing_extern_crate_item, krate!());
 911         }
 912         DepKind::UsedCrateSource => { force!(used_crate_source, krate!()); }
 913         DepKind::PostorderCnums => { force!(postorder_cnums, LOCAL_CRATE); }
 914         DepKind::HasCloneClosures => { force!(has_clone_closures, krate!()); }
 915         DepKind::HasCopyClosures => { force!(has_copy_closures, krate!()); }
 916
 917         DepKind::Freevars => { force!(freevars, def_id!()); }
 918         DepKind::MaybeUnusedTraitImport => {
 919             force!(maybe_unused_trait_import, def_id!());
 920         }
 921         DepKind::MaybeUnusedExternCrates => { force!(maybe_unused_extern_crates, LOCAL_CRATE); }
 922         DepKind::StabilityIndex => { force!(stability_index, LOCAL_CRATE); }
 923         DepKind::AllCrateNums => { force!(all_crate_nums, LOCAL_CRATE); }
 924         DepKind::ExportedSymbols => { force!(exported_symbols, krate!()); }
 925         DepKind::CollectAndPartitionTranslationItems => {
 926             force!(collect_and_partition_translation_items, LOCAL_CRATE);
 927         }
 928         DepKind::ExportName => { force!(export_name, def_id!()); }
 929         DepKind::ContainsExternIndicator => {
 930             force!(contains_extern_indicator, def_id!());
 931         }
 932         DepKind::IsTranslatedItem => { force!(is_translated_item, def_id!()); }
 933         DepKind::OutputFilenames => { force!(output_filenames, LOCAL_CRATE); }
 934
 935         DepKind::TargetFeaturesWhitelist => { force!(target_features_whitelist, LOCAL_CRATE); }
 936         DepKind::TargetFeaturesEnabled => { force!(target_features_enabled, def_id!()); }
 937
 938         DepKind::GetSymbolExportLevel => { force!(symbol_export_level, def_id!()); }
 939     }
 940
 941     true
 942 }
 943
 944
 945 // FIXME(#45015): Another piece of boilerplate code that could be generated in
 946 //                a combined define_dep_nodes!()/define_maps!() macro.
 947 macro_rules! impl_load_from_cache {
 948     ($($dep_kind:ident => $query_name:ident,)*) => {
 949         impl DepNode {
 950             // Check whether the query invocation corresponding to the given
 951             // DepNode is eligible for on-disk-caching.
 952             pub fn cache_on_disk(&self, tcx: TyCtxt) -> bool {
 953                 use ty::maps::queries;
 954                 use ty::maps::QueryDescription;
 955
 956                 match self.kind {
 957                     $(DepKind::$dep_kind => {
 958                         let def_id = self.extract_def_id(tcx).unwrap();
 959                         queries::$query_name::cache_on_disk(def_id)
 960                     })*
 961                     _ => false
 962                 }
 963             }
 964
 965             // This is method will execute the query corresponding to the given
 966             // DepNode. It is only expected to work for DepNodes where the
 967             // above `cache_on_disk` methods returns true.
 968             // Also, as a sanity check, it expects that the corresponding query
 969             // invocation has been marked as green already.
 970             pub fn load_from_on_disk_cache(&self, tcx: TyCtxt) {
 971                 match self.kind {
 972                     $(DepKind::$dep_kind => {
 973                         debug_assert!(tcx.dep_graph
 974                                          .node_color(self)
 975                                          .map(|c| c.is_green())
 976                                          .unwrap_or(false));
 977
 978                         let def_id = self.extract_def_id(tcx).unwrap();
 979                         let _ = tcx.$query_name(def_id);
 980                     })*
 981                     _ => {
 982                         bug!()
 983                     }
 984                 }
 985             }
 986         }
 987     }
 988 }
 989
 990 impl_load_from_cache!(
 991     TypeckTables => typeck_tables_of,
 992     MirOptimized => optimized_mir,
 993     UnsafetyCheckResult => unsafety_check_result,
 994     BorrowCheck => borrowck,
 995     MirBorrowCheck => mir_borrowck,
 996     MirConstQualif => mir_const_qualif,
 997     SymbolName => def_symbol_name,
 998     ConstIsRvaluePromotableToStatic => const_is_rvalue_promotable_to_static,
 999     ContainsExternIndicator => contains_extern_indicator,
1000     CheckMatch => check_match,
1001     TypeOfItem => type_of,
1002     GenericsOfItem => generics_of,
1003     PredicatesOfItem => predicates_of,
1004     UsedTraitImports => used_trait_imports,
1005 );