1 //! The implementation of the query system itself. This defines the macros that
2 //! generate the actual methods on tcx which find and execute the provider,
3 //! manage the caches, and so forth.
5 use crate::dep_graph::{DepContext, DepNode, DepNodeIndex, DepNodeParams};
6 use crate::query::caches::QueryCache;
7 use crate::query::config::{QueryDescription, QueryVtable};
8 use crate::query::job::{
9 report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo, QueryShardJobId,
11 use crate::query::{QueryContext, QueryMap, QuerySideEffects, QueryStackFrame};
13 use rustc_data_structures::fingerprint::Fingerprint;
14 use rustc_data_structures::fx::{FxHashMap, FxHasher};
15 #[cfg(parallel_compiler)]
16 use rustc_data_structures::profiling::TimingGuard;
17 use rustc_data_structures::sharded::{get_shard_index_by_hash, Sharded};
18 use rustc_data_structures::sync::{Lock, LockGuard};
19 use rustc_data_structures::thin_vec::ThinVec;
20 use rustc_errors::{DiagnosticBuilder, FatalError};
21 use rustc_session::Session;
22 use rustc_span::{Span, DUMMY_SP};
24 use std::collections::hash_map::Entry;
26 use std::hash::{Hash, Hasher};
28 use std::num::NonZeroU32;
31 pub struct QueryCacheStore<C: QueryCache> {
33 shards: Sharded<C::Sharded>,
36 impl<C: QueryCache + Default> Default for QueryCacheStore<C> {
37 fn default() -> Self {
38 Self { cache: C::default(), shards: Default::default() }
42 /// Values used when checking a query cache which can be reused on a cache-miss to execute the query.
43 pub struct QueryLookup {
44 pub(super) key_hash: u64,
48 // We compute the key's hash once and then use it for both the
49 // shard lookup and the hashmap lookup. This relies on the fact
50 // that both of them use `FxHasher`.
51 fn hash_for_shard<K: Hash>(key: &K) -> u64 {
52 let mut hasher = FxHasher::default();
53 key.hash(&mut hasher);
57 impl<C: QueryCache> QueryCacheStore<C> {
58 pub(super) fn get_lookup<'tcx>(
61 ) -> (QueryLookup, LockGuard<'tcx, C::Sharded>) {
62 let key_hash = hash_for_shard(key);
63 let shard = get_shard_index_by_hash(key_hash);
64 let lock = self.shards.get_shard_by_index(shard).lock();
65 (QueryLookup { key_hash, shard }, lock)
68 pub fn iter_results(&self, f: &mut dyn FnMut(&C::Key, &C::Value, DepNodeIndex)) {
69 self.cache.iter(&self.shards, f)
73 struct QueryStateShard<D, K> {
74 active: FxHashMap<K, QueryResult<D>>,
76 /// Used to generate unique ids for active jobs.
80 impl<D, K> Default for QueryStateShard<D, K> {
81 fn default() -> QueryStateShard<D, K> {
82 QueryStateShard { active: Default::default(), jobs: 0 }
86 pub struct QueryState<D, K> {
87 shards: Sharded<QueryStateShard<D, K>>,
90 /// Indicates the state of a query for a given key in a query map.
92 /// An already executing query. The query job can be used to await for its completion.
95 /// The query panicked. Queries trying to wait on this will raise a fatal error which will
100 impl<D, K> QueryState<D, K>
102 D: Copy + Clone + Eq + Hash,
103 K: Eq + Hash + Clone + Debug,
105 pub fn all_inactive(&self) -> bool {
106 let shards = self.shards.lock_shards();
107 shards.iter().all(|shard| shard.active.is_empty())
110 pub fn try_collect_active_jobs<CTX: Copy>(
114 make_query: fn(CTX, K) -> QueryStackFrame,
115 jobs: &mut QueryMap<D>,
117 // We use try_lock_shards here since we are called from the
118 // deadlock handler, and this shouldn't be locked.
119 let shards = self.shards.try_lock_shards()?;
120 for (shard_id, shard) in shards.iter().enumerate() {
121 for (k, v) in shard.active.iter() {
122 if let QueryResult::Started(ref job) = *v {
123 let id = QueryJobId::new(job.id, shard_id, kind);
124 let query = make_query(tcx, k.clone());
125 jobs.insert(id, QueryJobInfo { query, job: job.clone() });
134 impl<D, K> Default for QueryState<D, K> {
135 fn default() -> QueryState<D, K> {
136 QueryState { shards: Default::default() }
140 /// A type representing the responsibility to execute the job in the `job` field.
141 /// This will poison the relevant query if dropped.
142 struct JobOwner<'tcx, D, K>
144 D: Copy + Clone + Eq + Hash,
145 K: Eq + Hash + Clone,
147 state: &'tcx QueryState<D, K>,
154 fn mk_cycle<CTX, V, R>(
157 handle_cycle_error: fn(CTX, DiagnosticBuilder<'_>) -> V,
158 cache: &dyn crate::query::QueryStorage<Value = V, Stored = R>,
165 let error = report_cycle(tcx.dep_context().sess(), error);
166 let value = handle_cycle_error(tcx, error);
167 cache.store_nocache(value)
170 impl<'tcx, D, K> JobOwner<'tcx, D, K>
172 D: Copy + Clone + Eq + Hash,
173 K: Eq + Hash + Clone,
175 /// Either gets a `JobOwner` corresponding the query, allowing us to
176 /// start executing the query, or returns with the result of the query.
177 /// This function assumes that `try_get_cached` is already called and returned `lookup`.
178 /// If the query is executing elsewhere, this will wait for it and return the result.
179 /// If the query panicked, this will silently panic.
181 /// This function is inlined because that results in a noticeable speed-up
182 /// for some compile-time benchmarks.
184 fn try_start<'b, CTX>(
186 state: &'b QueryState<CTX::DepKind, K>,
190 dep_kind: CTX::DepKind,
191 ) -> TryGetJob<'b, CTX::DepKind, K>
195 let shard = lookup.shard;
196 let mut state_lock = state.shards.get_shard_by_index(shard).lock();
197 let lock = &mut *state_lock;
199 match lock.active.entry(key) {
200 Entry::Vacant(entry) => {
201 // Generate an id unique within this shard.
202 let id = lock.jobs.checked_add(1).unwrap();
204 let id = QueryShardJobId(NonZeroU32::new(id).unwrap());
206 let job = tcx.current_query_job();
207 let job = QueryJob::new(id, span, job);
209 let key = entry.key().clone();
210 entry.insert(QueryResult::Started(job));
212 let global_id = QueryJobId::new(id, shard, dep_kind);
213 let owner = JobOwner { state, id: global_id, key };
214 return TryGetJob::NotYetStarted(owner);
216 Entry::Occupied(mut entry) => {
217 match entry.get_mut() {
218 #[cfg(not(parallel_compiler))]
219 QueryResult::Started(job) => {
220 let id = QueryJobId::new(job.id, shard, dep_kind);
224 // If we are single-threaded we know that we have cycle error,
225 // so we just return the error.
226 return TryGetJob::Cycle(id.find_cycle_in_stack(
227 tcx.try_collect_active_jobs().unwrap(),
228 &tcx.current_query_job(),
232 #[cfg(parallel_compiler)]
233 QueryResult::Started(job) => {
234 // For parallel queries, we'll block and wait until the query running
235 // in another thread has completed. Record how long we wait in the
237 let query_blocked_prof_timer = tcx.dep_context().profiler().query_blocked();
240 let latch = job.latch();
244 // With parallel queries we might just have to wait on some other
246 let result = latch.wait_on(tcx.current_query_job(), span);
249 Ok(()) => TryGetJob::JobCompleted(query_blocked_prof_timer),
250 Err(cycle) => TryGetJob::Cycle(cycle),
253 QueryResult::Poisoned => FatalError.raise(),
259 /// Completes the query by updating the query cache with the `result`,
260 /// signals the waiter and forgets the JobOwner, so it won't poison the query
263 cache: &QueryCacheStore<C>,
265 dep_node_index: DepNodeIndex,
268 C: QueryCache<Key = K>,
270 // We can move out of `self` here because we `mem::forget` it below
271 let key = unsafe { ptr::read(&self.key) };
272 let state = self.state;
274 // Forget ourself so our destructor won't poison the query
277 let (job, result) = {
278 let key_hash = hash_for_shard(&key);
279 let shard = get_shard_index_by_hash(key_hash);
281 let mut lock = state.shards.get_shard_by_index(shard).lock();
282 match lock.active.remove(&key).unwrap() {
283 QueryResult::Started(job) => job,
284 QueryResult::Poisoned => panic!(),
288 let mut lock = cache.shards.get_shard_by_index(shard).lock();
289 cache.cache.complete(&mut lock, key, result, dep_node_index)
294 job.signal_complete();
299 impl<'tcx, D, K> Drop for JobOwner<'tcx, D, K>
301 D: Copy + Clone + Eq + Hash,
302 K: Eq + Hash + Clone,
307 // Poison the query so jobs waiting on it panic.
308 let state = self.state;
309 let shard = state.shards.get_shard_by_value(&self.key);
311 let mut shard = shard.lock();
312 let job = match shard.active.remove(&self.key).unwrap() {
313 QueryResult::Started(job) => job,
314 QueryResult::Poisoned => panic!(),
316 shard.active.insert(self.key.clone(), QueryResult::Poisoned);
319 // Also signal the completion of the job, so waiters
320 // will continue execution.
321 job.signal_complete();
326 pub(crate) struct CycleError {
327 /// The query and related span that uses the cycle.
328 pub usage: Option<(Span, QueryStackFrame)>,
329 pub cycle: Vec<QueryInfo>,
332 /// The result of `try_start`.
333 enum TryGetJob<'tcx, D, K>
335 D: Copy + Clone + Eq + Hash,
336 K: Eq + Hash + Clone,
338 /// The query is not yet started. Contains a guard to the cache eventually used to start it.
339 NotYetStarted(JobOwner<'tcx, D, K>),
341 /// The query was already completed.
342 /// Returns the result of the query and its dep-node index
343 /// if it succeeded or a cycle error if it failed.
344 #[cfg(parallel_compiler)]
345 JobCompleted(TimingGuard<'tcx>),
347 /// Trying to execute the query resulted in a cycle.
351 /// Checks if the query is already computed and in the cache.
352 /// It returns the shard index and a lock guard to the shard,
353 /// which will be used if the query is not in the cache and we need
356 pub fn try_get_cached<'a, CTX, C, R, OnHit>(
358 cache: &'a QueryCacheStore<C>,
360 // `on_hit` can be called while holding a lock to the query cache
362 ) -> Result<R, QueryLookup>
366 OnHit: FnOnce(&C::Stored) -> R,
368 cache.cache.lookup(cache, &key, |value, index| {
369 if unlikely!(tcx.profiler().enabled()) {
370 tcx.profiler().query_cache_hit(index.into());
372 tcx.dep_graph().read_index(index);
377 fn try_execute_query<CTX, C>(
379 state: &QueryState<CTX::DepKind, C::Key>,
380 cache: &QueryCacheStore<C>,
384 dep_node: Option<DepNode<CTX::DepKind>>,
385 query: &QueryVtable<CTX, C::Key, C::Value>,
386 ) -> (C::Stored, Option<DepNodeIndex>)
389 C::Key: Clone + DepNodeParams<CTX::DepContext>,
392 match JobOwner::<'_, CTX::DepKind, C::Key>::try_start(
400 TryGetJob::NotYetStarted(job) => {
401 let (result, dep_node_index) = execute_job(tcx, key, dep_node, query, job.id);
402 let result = job.complete(cache, result, dep_node_index);
403 (result, Some(dep_node_index))
405 TryGetJob::Cycle(error) => {
406 let result = mk_cycle(tcx, error, query.handle_cycle_error, &cache.cache);
409 #[cfg(parallel_compiler)]
410 TryGetJob::JobCompleted(query_blocked_prof_timer) => {
411 let (v, index) = cache
413 .lookup(cache, &key, |value, index| (value.clone(), index))
414 .unwrap_or_else(|_| panic!("value must be in cache after waiting"));
416 if unlikely!(tcx.dep_context().profiler().enabled()) {
417 tcx.dep_context().profiler().query_cache_hit(index.into());
419 query_blocked_prof_timer.finish_with_query_invocation_id(index.into());
426 fn execute_job<CTX, K, V>(
429 mut dep_node_opt: Option<DepNode<CTX::DepKind>>,
430 query: &QueryVtable<CTX, K, V>,
431 job_id: QueryJobId<CTX::DepKind>,
432 ) -> (V, DepNodeIndex)
434 K: Clone + DepNodeParams<CTX::DepContext>,
438 let dep_graph = tcx.dep_context().dep_graph();
440 // Fast path for when incr. comp. is off.
441 if !dep_graph.is_fully_enabled() {
442 let prof_timer = tcx.dep_context().profiler().query_provider();
443 let result = tcx.start_query(job_id, None, true, || query.compute(*tcx.dep_context(), key));
444 let dep_node_index = dep_graph.next_virtual_depnode_index();
445 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
446 return (result, dep_node_index);
449 if !query.anon && !query.eval_always {
450 // `to_dep_node` is expensive for some `DepKind`s.
452 dep_node_opt.get_or_insert_with(|| query.to_dep_node(*tcx.dep_context(), &key));
454 // The diagnostics for this query will be promoted to the current session during
455 // `try_mark_green()`, so we can ignore them here.
456 if let Some(ret) = tcx.start_query(job_id, None, false, || {
457 try_load_from_disk_and_cache_in_memory(tcx, &key, &dep_node, query)
463 let prof_timer = tcx.dep_context().profiler().query_provider();
464 let diagnostics = Lock::new(ThinVec::new());
466 let (result, dep_node_index) = tcx.start_query(job_id, Some(&diagnostics), true, || {
468 return dep_graph.with_anon_task(*tcx.dep_context(), query.dep_kind, || {
469 query.compute(*tcx.dep_context(), key)
473 // `to_dep_node` is expensive for some `DepKind`s.
474 let dep_node = dep_node_opt.unwrap_or_else(|| query.to_dep_node(*tcx.dep_context(), &key));
476 dep_graph.with_task(dep_node, *tcx.dep_context(), key, query.compute, query.hash_result)
479 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
481 let diagnostics = diagnostics.into_inner();
482 let side_effects = QuerySideEffects { diagnostics };
484 if unlikely!(!side_effects.is_empty()) {
486 tcx.store_side_effects_for_anon_node(dep_node_index, side_effects);
488 tcx.store_side_effects(dep_node_index, side_effects);
492 (result, dep_node_index)
495 fn try_load_from_disk_and_cache_in_memory<CTX, K, V>(
498 dep_node: &DepNode<CTX::DepKind>,
499 query: &QueryVtable<CTX, K, V>,
500 ) -> Option<(V, DepNodeIndex)>
506 // Note this function can be called concurrently from the same query
507 // We must ensure that this is handled correctly.
509 let dep_graph = tcx.dep_context().dep_graph();
510 let (prev_dep_node_index, dep_node_index) = dep_graph.try_mark_green(tcx, &dep_node)?;
512 debug_assert!(dep_graph.is_green(dep_node));
514 // First we try to load the result from the on-disk cache.
515 // Some things are never cached on disk.
516 if query.cache_on_disk {
517 let prof_timer = tcx.dep_context().profiler().incr_cache_loading();
518 let result = query.try_load_from_disk(tcx, prev_dep_node_index);
519 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
521 if let Some(result) = result {
522 let prev_fingerprint = tcx
525 .prev_fingerprint_of(dep_node)
526 .unwrap_or(Fingerprint::ZERO);
527 // If `-Zincremental-verify-ich` is specified, re-hash results from
528 // the cache and make sure that they have the expected fingerprint.
530 // If not, we still seek to verify a subset of fingerprints loaded
531 // from disk. Re-hashing results is fairly expensive, so we can't
532 // currently afford to verify every hash. This subset should still
533 // give us some coverage of potential bugs though.
534 let try_verify = prev_fingerprint.as_value().1 % 32 == 0;
536 try_verify || tcx.dep_context().sess().opts.debugging_opts.incremental_verify_ich
538 incremental_verify_ich(*tcx.dep_context(), &result, dep_node, query);
541 return Some((result, dep_node_index));
544 // We always expect to find a cached result for things that
545 // can be forced from `DepNode`.
547 !tcx.dep_context().fingerprint_style(dep_node.kind).reconstructible(),
548 "missing on-disk cache entry for {:?}",
553 // We could not load a result from the on-disk cache, so
555 let prof_timer = tcx.dep_context().profiler().query_provider();
557 // The dep-graph for this computation is already in-place.
558 let result = dep_graph.with_ignore(|| query.compute(*tcx.dep_context(), key.clone()));
560 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
562 // Verify that re-running the query produced a result with the expected hash
563 // This catches bugs in query implementations, turning them into ICEs.
564 // For example, a query might sort its result by `DefId` - since `DefId`s are
565 // not stable across compilation sessions, the result could get up getting sorted
566 // in a different order when the query is re-run, even though all of the inputs
567 // (e.g. `DefPathHash` values) were green.
569 // See issue #82920 for an example of a miscompilation that would get turned into
570 // an ICE by this check
571 incremental_verify_ich(*tcx.dep_context(), &result, dep_node, query);
573 Some((result, dep_node_index))
576 fn incremental_verify_ich<CTX, K, V: Debug>(
577 tcx: CTX::DepContext,
579 dep_node: &DepNode<CTX::DepKind>,
580 query: &QueryVtable<CTX, K, V>,
585 tcx.dep_graph().is_green(dep_node),
586 "fingerprint for green query instance not loaded from cache: {:?}",
590 debug!("BEGIN verify_ich({:?})", dep_node);
591 let new_hash = query.hash_result.map_or(Fingerprint::ZERO, |f| {
592 let mut hcx = tcx.create_stable_hashing_context();
595 let old_hash = tcx.dep_graph().prev_fingerprint_of(dep_node);
596 debug!("END verify_ich({:?})", dep_node);
598 if Some(new_hash) != old_hash {
599 incremental_verify_ich_cold(tcx.sess(), DebugArg::from(&dep_node), DebugArg::from(&result));
603 // This DebugArg business is largely a mirror of std::fmt::ArgumentV1, which is
604 // currently not exposed publicly.
606 // The PR which added this attempted to use `&dyn Debug` instead, but that
607 // showed statistically significant worse compiler performance. It's not
608 // actually clear what the cause there was -- the code should be cold. If this
609 // can be replaced with `&dyn Debug` with on perf impact, then it probably
615 struct DebugArg<'a> {
617 fmt: fn(&Opaque, &mut std::fmt::Formatter<'_>) -> std::fmt::Result,
620 impl<'a, T> From<&'a T> for DebugArg<'a>
624 fn from(value: &'a T) -> DebugArg<'a> {
626 value: unsafe { std::mem::transmute(value) },
628 std::mem::transmute(<T as std::fmt::Debug>::fmt as fn(_, _) -> std::fmt::Result)
634 impl std::fmt::Debug for DebugArg<'_> {
635 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
636 (self.fmt)(self.value, f)
640 // Note that this is marked #[cold] and intentionally takes the equivalent of
641 // `dyn Debug` for its arguments, as we want to avoid generating a bunch of
642 // different implementations for LLVM to chew on (and filling up the final
645 fn incremental_verify_ich_cold(sess: &Session, dep_node: DebugArg<'_>, result: DebugArg<'_>) {
646 let run_cmd = if let Some(crate_name) = &sess.opts.crate_name {
647 format!("`cargo clean -p {}` or `cargo clean`", crate_name)
649 "`cargo clean`".to_string()
652 // When we emit an error message and panic, we try to debug-print the `DepNode`
653 // and query result. Unfortunately, this can cause us to run additional queries,
654 // which may result in another fingerprint mismatch while we're in the middle
655 // of processing this one. To avoid a double-panic (which kills the process
656 // before we can print out the query static), we print out a terse
657 // but 'safe' message if we detect a re-entrant call to this method.
659 static INSIDE_VERIFY_PANIC: Cell<bool> = const { Cell::new(false) };
662 let old_in_panic = INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.replace(true));
666 "internal compiler error: re-entrant incremental verify failure, suppressing message",
670 sess.struct_err(&format!("internal compiler error: encountered incremental compilation error with {:?}", dep_node))
671 .help(&format!("This is a known issue with the compiler. Run {} to allow your project to compile", run_cmd))
672 .note(&"Please follow the instructions below to create a bug report with the provided information")
673 .note(&"See <https://github.com/rust-lang/rust/issues/84970> for more information")
675 panic!("Found unstable fingerprints for {:?}: {:?}", dep_node, result);
678 INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.set(old_in_panic));
681 /// Ensure that either this query has all green inputs or been executed.
682 /// Executing `query::ensure(D)` is considered a read of the dep-node `D`.
683 /// Returns true if the query should still run.
685 /// This function is particularly useful when executing passes for their
686 /// side-effects -- e.g., in order to report errors for erroneous programs.
688 /// Note: The optimization is only available during incr. comp.
690 fn ensure_must_run<CTX, K, V>(
693 query: &QueryVtable<CTX, K, V>,
694 ) -> (bool, Option<DepNode<CTX::DepKind>>)
696 K: crate::dep_graph::DepNodeParams<CTX::DepContext>,
699 if query.eval_always {
703 // Ensuring an anonymous query makes no sense
704 assert!(!query.anon);
706 let dep_node = query.to_dep_node(*tcx.dep_context(), key);
708 let dep_graph = tcx.dep_context().dep_graph();
709 match dep_graph.try_mark_green(tcx, &dep_node) {
711 // A None return from `try_mark_green` means that this is either
712 // a new dep node or that the dep node has already been marked red.
713 // Either way, we can't call `dep_graph.read()` as we don't have the
714 // DepNodeIndex. We must invoke the query itself. The performance cost
715 // this introduces should be negligible as we'll immediately hit the
716 // in-memory cache, or another query down the line will.
717 (true, Some(dep_node))
719 Some((_, dep_node_index)) => {
720 dep_graph.read_index(dep_node_index);
721 tcx.dep_context().profiler().query_cache_hit(dep_node_index.into());
732 pub fn get_query<Q, CTX>(
738 ) -> Option<Q::Stored>
740 Q: QueryDescription<CTX>,
741 Q::Key: DepNodeParams<CTX::DepContext>,
744 let query = Q::make_vtable(tcx, &key);
745 let dep_node = if let QueryMode::Ensure = mode {
746 let (must_run, dep_node) = ensure_must_run(tcx, &key, &query);
755 debug!("ty::query::get_query<{}>(key={:?}, span={:?})", Q::NAME, key, span);
756 let (result, dep_node_index) = try_execute_query(
766 if let Some(dep_node_index) = dep_node_index {
767 tcx.dep_context().dep_graph().read_index(dep_node_index)
772 pub fn force_query<Q, CTX>(tcx: CTX, key: Q::Key, dep_node: DepNode<CTX::DepKind>)
774 Q: QueryDescription<CTX>,
775 Q::Key: DepNodeParams<CTX::DepContext>,
778 // We may be concurrently trying both execute and force a query.
779 // Ensure that only one of them runs the query.
780 let cache = Q::query_cache(tcx);
781 let cached = cache.cache.lookup(cache, &key, |_, index| {
782 if unlikely!(tcx.dep_context().profiler().enabled()) {
783 tcx.dep_context().profiler().query_cache_hit(index.into());
787 let lookup = match cached {
789 Err(lookup) => lookup,
792 let query = Q::make_vtable(tcx, &key);
793 let state = Q::query_state(tcx);
794 debug_assert!(!query.anon);
796 try_execute_query(tcx, state, cache, DUMMY_SP, key, lookup, Some(dep_node), &query);