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::{report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo};
9 use crate::query::{QueryContext, QueryMap, QuerySideEffects, QueryStackFrame};
10 use rustc_data_structures::fingerprint::Fingerprint;
11 use rustc_data_structures::fx::{FxHashMap, FxHasher};
12 #[cfg(parallel_compiler)]
13 use rustc_data_structures::profiling::TimingGuard;
14 use rustc_data_structures::sharded::{get_shard_index_by_hash, Sharded};
15 use rustc_data_structures::sync::{Lock, LockGuard};
16 use rustc_data_structures::thin_vec::ThinVec;
17 use rustc_errors::{DiagnosticBuilder, FatalError};
18 use rustc_session::Session;
19 use rustc_span::{Span, DUMMY_SP};
21 use std::collections::hash_map::Entry;
23 use std::hash::{Hash, Hasher};
27 pub struct QueryCacheStore<C: QueryCache> {
29 shards: Sharded<C::Sharded>,
32 impl<C: QueryCache + Default> Default for QueryCacheStore<C> {
33 fn default() -> Self {
34 Self { cache: C::default(), shards: Default::default() }
38 /// Values used when checking a query cache which can be reused on a cache-miss to execute the query.
39 pub struct QueryLookup {
40 pub(super) key_hash: u64,
44 // We compute the key's hash once and then use it for both the
45 // shard lookup and the hashmap lookup. This relies on the fact
46 // that both of them use `FxHasher`.
47 fn hash_for_shard<K: Hash>(key: &K) -> u64 {
48 let mut hasher = FxHasher::default();
49 key.hash(&mut hasher);
53 impl<C: QueryCache> QueryCacheStore<C> {
54 pub(super) fn get_lookup<'tcx>(
57 ) -> (QueryLookup, LockGuard<'tcx, C::Sharded>) {
58 let key_hash = hash_for_shard(key);
59 let shard = get_shard_index_by_hash(key_hash);
60 let lock = self.shards.get_shard_by_index(shard).lock();
61 (QueryLookup { key_hash, shard }, lock)
64 pub fn iter_results(&self, f: &mut dyn FnMut(&C::Key, &C::Value, DepNodeIndex)) {
65 self.cache.iter(&self.shards, f)
69 struct QueryStateShard<K> {
70 active: FxHashMap<K, QueryResult>,
73 impl<K> Default for QueryStateShard<K> {
74 fn default() -> QueryStateShard<K> {
75 QueryStateShard { active: Default::default() }
79 pub struct QueryState<K> {
80 shards: Sharded<QueryStateShard<K>>,
83 /// Indicates the state of a query for a given key in a query map.
85 /// An already executing query. The query job can be used to await for its completion.
88 /// The query panicked. Queries trying to wait on this will raise a fatal error which will
95 K: Eq + Hash + Clone + Debug,
97 pub fn all_inactive(&self) -> bool {
98 let shards = self.shards.lock_shards();
99 shards.iter().all(|shard| shard.active.is_empty())
102 pub fn try_collect_active_jobs<CTX: Copy>(
105 make_query: fn(CTX, K) -> QueryStackFrame,
108 // We use try_lock_shards here since we are called from the
109 // deadlock handler, and this shouldn't be locked.
110 let shards = self.shards.try_lock_shards()?;
111 for shard in shards.iter() {
112 for (k, v) in shard.active.iter() {
113 if let QueryResult::Started(ref job) = *v {
114 let query = make_query(tcx, k.clone());
115 jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
124 impl<K> Default for QueryState<K> {
125 fn default() -> QueryState<K> {
126 QueryState { shards: Default::default() }
130 /// A type representing the responsibility to execute the job in the `job` field.
131 /// This will poison the relevant query if dropped.
132 struct JobOwner<'tcx, K>
134 K: Eq + Hash + Clone,
136 state: &'tcx QueryState<K>,
143 fn mk_cycle<CTX, V, R>(
146 handle_cycle_error: fn(CTX, DiagnosticBuilder<'_>) -> V,
147 cache: &dyn crate::query::QueryStorage<Value = V, Stored = R>,
154 let error = report_cycle(tcx.dep_context().sess(), error);
155 let value = handle_cycle_error(tcx, error);
156 cache.store_nocache(value)
159 impl<'tcx, K> JobOwner<'tcx, K>
161 K: Eq + Hash + Clone,
163 /// Either gets a `JobOwner` corresponding the query, allowing us to
164 /// start executing the query, or returns with the result of the query.
165 /// This function assumes that `try_get_cached` is already called and returned `lookup`.
166 /// If the query is executing elsewhere, this will wait for it and return the result.
167 /// If the query panicked, this will silently panic.
169 /// This function is inlined because that results in a noticeable speed-up
170 /// for some compile-time benchmarks.
172 fn try_start<'b, CTX>(
174 state: &'b QueryState<K>,
178 ) -> TryGetJob<'b, K>
182 let shard = lookup.shard;
183 let mut state_lock = state.shards.get_shard_by_index(shard).lock();
184 let lock = &mut *state_lock;
186 match lock.active.entry(key) {
187 Entry::Vacant(entry) => {
188 let id = tcx.next_job_id();
189 let job = tcx.current_query_job();
190 let job = QueryJob::new(id, span, job);
192 let key = entry.key().clone();
193 entry.insert(QueryResult::Started(job));
195 let owner = JobOwner { state, id, key };
196 return TryGetJob::NotYetStarted(owner);
198 Entry::Occupied(mut entry) => {
199 match entry.get_mut() {
200 #[cfg(not(parallel_compiler))]
201 QueryResult::Started(job) => {
205 // If we are single-threaded we know that we have cycle error,
206 // so we just return the error.
207 return TryGetJob::Cycle(id.find_cycle_in_stack(
208 tcx.try_collect_active_jobs().unwrap(),
209 &tcx.current_query_job(),
213 #[cfg(parallel_compiler)]
214 QueryResult::Started(job) => {
215 // For parallel queries, we'll block and wait until the query running
216 // in another thread has completed. Record how long we wait in the
218 let query_blocked_prof_timer = tcx.dep_context().profiler().query_blocked();
221 let latch = job.latch();
225 // With parallel queries we might just have to wait on some other
227 let result = latch.wait_on(tcx.current_query_job(), span);
230 Ok(()) => TryGetJob::JobCompleted(query_blocked_prof_timer),
231 Err(cycle) => TryGetJob::Cycle(cycle),
234 QueryResult::Poisoned => FatalError.raise(),
240 /// Completes the query by updating the query cache with the `result`,
241 /// signals the waiter and forgets the JobOwner, so it won't poison the query
244 cache: &QueryCacheStore<C>,
246 dep_node_index: DepNodeIndex,
249 C: QueryCache<Key = K>,
251 // We can move out of `self` here because we `mem::forget` it below
252 let key = unsafe { ptr::read(&self.key) };
253 let state = self.state;
255 // Forget ourself so our destructor won't poison the query
258 let (job, result) = {
259 let key_hash = hash_for_shard(&key);
260 let shard = get_shard_index_by_hash(key_hash);
262 let mut lock = state.shards.get_shard_by_index(shard).lock();
263 match lock.active.remove(&key).unwrap() {
264 QueryResult::Started(job) => job,
265 QueryResult::Poisoned => panic!(),
269 let mut lock = cache.shards.get_shard_by_index(shard).lock();
270 cache.cache.complete(&mut lock, key, result, dep_node_index)
275 job.signal_complete();
280 impl<'tcx, K> Drop for JobOwner<'tcx, K>
282 K: Eq + Hash + Clone,
287 // Poison the query so jobs waiting on it panic.
288 let state = self.state;
289 let shard = state.shards.get_shard_by_value(&self.key);
291 let mut shard = shard.lock();
292 let job = match shard.active.remove(&self.key).unwrap() {
293 QueryResult::Started(job) => job,
294 QueryResult::Poisoned => panic!(),
296 shard.active.insert(self.key.clone(), QueryResult::Poisoned);
299 // Also signal the completion of the job, so waiters
300 // will continue execution.
301 job.signal_complete();
306 pub(crate) struct CycleError {
307 /// The query and related span that uses the cycle.
308 pub usage: Option<(Span, QueryStackFrame)>,
309 pub cycle: Vec<QueryInfo>,
312 /// The result of `try_start`.
313 enum TryGetJob<'tcx, K>
315 K: Eq + Hash + Clone,
317 /// The query is not yet started. Contains a guard to the cache eventually used to start it.
318 NotYetStarted(JobOwner<'tcx, K>),
320 /// The query was already completed.
321 /// Returns the result of the query and its dep-node index
322 /// if it succeeded or a cycle error if it failed.
323 #[cfg(parallel_compiler)]
324 JobCompleted(TimingGuard<'tcx>),
326 /// Trying to execute the query resulted in a cycle.
330 /// Checks if the query is already computed and in the cache.
331 /// It returns the shard index and a lock guard to the shard,
332 /// which will be used if the query is not in the cache and we need
335 pub fn try_get_cached<'a, CTX, C, R, OnHit>(
337 cache: &'a QueryCacheStore<C>,
339 // `on_hit` can be called while holding a lock to the query cache
341 ) -> Result<R, QueryLookup>
345 OnHit: FnOnce(&C::Stored) -> R,
347 cache.cache.lookup(cache, &key, |value, index| {
348 if unlikely!(tcx.profiler().enabled()) {
349 tcx.profiler().query_cache_hit(index.into());
351 tcx.dep_graph().read_index(index);
356 fn try_execute_query<CTX, C>(
358 state: &QueryState<C::Key>,
359 cache: &QueryCacheStore<C>,
363 dep_node: Option<DepNode<CTX::DepKind>>,
364 query: &QueryVtable<CTX, C::Key, C::Value>,
365 ) -> (C::Stored, Option<DepNodeIndex>)
368 C::Key: Clone + DepNodeParams<CTX::DepContext>,
371 match JobOwner::<'_, C::Key>::try_start(&tcx, state, span, key.clone(), lookup) {
372 TryGetJob::NotYetStarted(job) => {
373 let (result, dep_node_index) = execute_job(tcx, key, dep_node, query, job.id);
374 let result = job.complete(cache, result, dep_node_index);
375 (result, Some(dep_node_index))
377 TryGetJob::Cycle(error) => {
378 let result = mk_cycle(tcx, error, query.handle_cycle_error, &cache.cache);
381 #[cfg(parallel_compiler)]
382 TryGetJob::JobCompleted(query_blocked_prof_timer) => {
383 let (v, index) = cache
385 .lookup(cache, &key, |value, index| (value.clone(), index))
386 .unwrap_or_else(|_| panic!("value must be in cache after waiting"));
388 if unlikely!(tcx.dep_context().profiler().enabled()) {
389 tcx.dep_context().profiler().query_cache_hit(index.into());
391 query_blocked_prof_timer.finish_with_query_invocation_id(index.into());
398 fn execute_job<CTX, K, V>(
401 mut dep_node_opt: Option<DepNode<CTX::DepKind>>,
402 query: &QueryVtable<CTX, K, V>,
404 ) -> (V, DepNodeIndex)
406 K: Clone + DepNodeParams<CTX::DepContext>,
410 let dep_graph = tcx.dep_context().dep_graph();
412 // Fast path for when incr. comp. is off.
413 if !dep_graph.is_fully_enabled() {
414 let prof_timer = tcx.dep_context().profiler().query_provider();
415 let result = tcx.start_query(job_id, None, || query.compute(*tcx.dep_context(), key));
416 let dep_node_index = dep_graph.next_virtual_depnode_index();
417 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
418 return (result, dep_node_index);
421 if !query.anon && !query.eval_always {
422 // `to_dep_node` is expensive for some `DepKind`s.
424 dep_node_opt.get_or_insert_with(|| query.to_dep_node(*tcx.dep_context(), &key));
426 // The diagnostics for this query will be promoted to the current session during
427 // `try_mark_green()`, so we can ignore them here.
428 if let Some(ret) = tcx.start_query(job_id, None, || {
429 try_load_from_disk_and_cache_in_memory(tcx, &key, &dep_node, query)
435 let prof_timer = tcx.dep_context().profiler().query_provider();
436 let diagnostics = Lock::new(ThinVec::new());
438 let (result, dep_node_index) = tcx.start_query(job_id, Some(&diagnostics), || {
440 return dep_graph.with_anon_task(*tcx.dep_context(), query.dep_kind, || {
441 query.compute(*tcx.dep_context(), key)
445 // `to_dep_node` is expensive for some `DepKind`s.
446 let dep_node = dep_node_opt.unwrap_or_else(|| query.to_dep_node(*tcx.dep_context(), &key));
448 dep_graph.with_task(dep_node, *tcx.dep_context(), key, query.compute, query.hash_result)
451 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
453 let diagnostics = diagnostics.into_inner();
454 let side_effects = QuerySideEffects { diagnostics };
456 if unlikely!(!side_effects.is_empty()) {
458 tcx.store_side_effects_for_anon_node(dep_node_index, side_effects);
460 tcx.store_side_effects(dep_node_index, side_effects);
464 (result, dep_node_index)
467 fn try_load_from_disk_and_cache_in_memory<CTX, K, V>(
470 dep_node: &DepNode<CTX::DepKind>,
471 query: &QueryVtable<CTX, K, V>,
472 ) -> Option<(V, DepNodeIndex)>
478 // Note this function can be called concurrently from the same query
479 // We must ensure that this is handled correctly.
481 let dep_graph = tcx.dep_context().dep_graph();
482 let (prev_dep_node_index, dep_node_index) = dep_graph.try_mark_green(tcx, &dep_node)?;
484 debug_assert!(dep_graph.is_green(dep_node));
486 // First we try to load the result from the on-disk cache.
487 // Some things are never cached on disk.
488 if query.cache_on_disk {
489 let prof_timer = tcx.dep_context().profiler().incr_cache_loading();
491 // The call to `with_query_deserialization` enforces that no new `DepNodes`
492 // are created during deserialization. See the docs of that method for more
494 let result = dep_graph
495 .with_query_deserialization(|| query.try_load_from_disk(tcx, prev_dep_node_index));
497 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
499 if let Some(result) = result {
500 if unlikely!(tcx.dep_context().sess().opts.debugging_opts.query_dep_graph) {
501 dep_graph.mark_debug_loaded_from_disk(*dep_node)
504 let prev_fingerprint = tcx
507 .prev_fingerprint_of(dep_node)
508 .unwrap_or(Fingerprint::ZERO);
509 // If `-Zincremental-verify-ich` is specified, re-hash results from
510 // the cache and make sure that they have the expected fingerprint.
512 // If not, we still seek to verify a subset of fingerprints loaded
513 // from disk. Re-hashing results is fairly expensive, so we can't
514 // currently afford to verify every hash. This subset should still
515 // give us some coverage of potential bugs though.
516 let try_verify = prev_fingerprint.as_value().1 % 32 == 0;
518 try_verify || tcx.dep_context().sess().opts.debugging_opts.incremental_verify_ich
520 incremental_verify_ich(*tcx.dep_context(), &result, dep_node, query);
523 return Some((result, dep_node_index));
526 // We always expect to find a cached result for things that
527 // can be forced from `DepNode`.
529 !tcx.dep_context().fingerprint_style(dep_node.kind).reconstructible(),
530 "missing on-disk cache entry for {:?}",
535 // We could not load a result from the on-disk cache, so
537 let prof_timer = tcx.dep_context().profiler().query_provider();
539 // The dep-graph for this computation is already in-place.
540 let result = dep_graph.with_ignore(|| query.compute(*tcx.dep_context(), key.clone()));
542 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
544 // Verify that re-running the query produced a result with the expected hash
545 // This catches bugs in query implementations, turning them into ICEs.
546 // For example, a query might sort its result by `DefId` - since `DefId`s are
547 // not stable across compilation sessions, the result could get up getting sorted
548 // in a different order when the query is re-run, even though all of the inputs
549 // (e.g. `DefPathHash` values) were green.
551 // See issue #82920 for an example of a miscompilation that would get turned into
552 // an ICE by this check
553 incremental_verify_ich(*tcx.dep_context(), &result, dep_node, query);
555 Some((result, dep_node_index))
558 fn incremental_verify_ich<CTX, K, V: Debug>(
559 tcx: CTX::DepContext,
561 dep_node: &DepNode<CTX::DepKind>,
562 query: &QueryVtable<CTX, K, V>,
567 tcx.dep_graph().is_green(dep_node),
568 "fingerprint for green query instance not loaded from cache: {:?}",
572 debug!("BEGIN verify_ich({:?})", dep_node);
573 let new_hash = query.hash_result.map_or(Fingerprint::ZERO, |f| {
574 let mut hcx = tcx.create_stable_hashing_context();
577 let old_hash = tcx.dep_graph().prev_fingerprint_of(dep_node);
578 debug!("END verify_ich({:?})", dep_node);
580 if Some(new_hash) != old_hash {
581 incremental_verify_ich_cold(tcx.sess(), DebugArg::from(&dep_node), DebugArg::from(&result));
585 // This DebugArg business is largely a mirror of std::fmt::ArgumentV1, which is
586 // currently not exposed publicly.
588 // The PR which added this attempted to use `&dyn Debug` instead, but that
589 // showed statistically significant worse compiler performance. It's not
590 // actually clear what the cause there was -- the code should be cold. If this
591 // can be replaced with `&dyn Debug` with on perf impact, then it probably
597 struct DebugArg<'a> {
599 fmt: fn(&Opaque, &mut std::fmt::Formatter<'_>) -> std::fmt::Result,
602 impl<'a, T> From<&'a T> for DebugArg<'a>
606 fn from(value: &'a T) -> DebugArg<'a> {
608 value: unsafe { std::mem::transmute(value) },
610 std::mem::transmute(<T as std::fmt::Debug>::fmt as fn(_, _) -> std::fmt::Result)
616 impl std::fmt::Debug for DebugArg<'_> {
617 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
618 (self.fmt)(self.value, f)
622 // Note that this is marked #[cold] and intentionally takes the equivalent of
623 // `dyn Debug` for its arguments, as we want to avoid generating a bunch of
624 // different implementations for LLVM to chew on (and filling up the final
627 fn incremental_verify_ich_cold(sess: &Session, dep_node: DebugArg<'_>, result: DebugArg<'_>) {
628 let run_cmd = if let Some(crate_name) = &sess.opts.crate_name {
629 format!("`cargo clean -p {}` or `cargo clean`", crate_name)
631 "`cargo clean`".to_string()
634 // When we emit an error message and panic, we try to debug-print the `DepNode`
635 // and query result. Unfortunately, this can cause us to run additional queries,
636 // which may result in another fingerprint mismatch while we're in the middle
637 // of processing this one. To avoid a double-panic (which kills the process
638 // before we can print out the query static), we print out a terse
639 // but 'safe' message if we detect a re-entrant call to this method.
641 static INSIDE_VERIFY_PANIC: Cell<bool> = const { Cell::new(false) };
644 let old_in_panic = INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.replace(true));
648 "internal compiler error: re-entrant incremental verify failure, suppressing message",
652 sess.struct_err(&format!("internal compiler error: encountered incremental compilation error with {:?}", dep_node))
653 .help(&format!("This is a known issue with the compiler. Run {} to allow your project to compile", run_cmd))
654 .note(&"Please follow the instructions below to create a bug report with the provided information")
655 .note(&"See <https://github.com/rust-lang/rust/issues/84970> for more information")
657 panic!("Found unstable fingerprints for {:?}: {:?}", dep_node, result);
660 INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.set(old_in_panic));
663 /// Ensure that either this query has all green inputs or been executed.
664 /// Executing `query::ensure(D)` is considered a read of the dep-node `D`.
665 /// Returns true if the query should still run.
667 /// This function is particularly useful when executing passes for their
668 /// side-effects -- e.g., in order to report errors for erroneous programs.
670 /// Note: The optimization is only available during incr. comp.
672 fn ensure_must_run<CTX, K, V>(
675 query: &QueryVtable<CTX, K, V>,
676 ) -> (bool, Option<DepNode<CTX::DepKind>>)
678 K: crate::dep_graph::DepNodeParams<CTX::DepContext>,
681 if query.eval_always {
685 // Ensuring an anonymous query makes no sense
686 assert!(!query.anon);
688 let dep_node = query.to_dep_node(*tcx.dep_context(), key);
690 let dep_graph = tcx.dep_context().dep_graph();
691 match dep_graph.try_mark_green(tcx, &dep_node) {
693 // A None return from `try_mark_green` means that this is either
694 // a new dep node or that the dep node has already been marked red.
695 // Either way, we can't call `dep_graph.read()` as we don't have the
696 // DepNodeIndex. We must invoke the query itself. The performance cost
697 // this introduces should be negligible as we'll immediately hit the
698 // in-memory cache, or another query down the line will.
699 (true, Some(dep_node))
701 Some((_, dep_node_index)) => {
702 dep_graph.read_index(dep_node_index);
703 tcx.dep_context().profiler().query_cache_hit(dep_node_index.into());
714 pub fn get_query<Q, CTX>(
720 ) -> Option<Q::Stored>
722 Q: QueryDescription<CTX>,
723 Q::Key: DepNodeParams<CTX::DepContext>,
726 let query = Q::make_vtable(tcx, &key);
727 let dep_node = if let QueryMode::Ensure = mode {
728 let (must_run, dep_node) = ensure_must_run(tcx, &key, &query);
737 debug!("ty::query::get_query<{}>(key={:?}, span={:?})", Q::NAME, key, span);
738 let (result, dep_node_index) = try_execute_query(
748 if let Some(dep_node_index) = dep_node_index {
749 tcx.dep_context().dep_graph().read_index(dep_node_index)
754 pub fn force_query<Q, CTX>(tcx: CTX, key: Q::Key, dep_node: DepNode<CTX::DepKind>)
756 Q: QueryDescription<CTX>,
757 Q::Key: DepNodeParams<CTX::DepContext>,
760 // We may be concurrently trying both execute and force a query.
761 // Ensure that only one of them runs the query.
762 let cache = Q::query_cache(tcx);
763 let cached = cache.cache.lookup(cache, &key, |_, index| {
764 if unlikely!(tcx.dep_context().profiler().enabled()) {
765 tcx.dep_context().profiler().query_cache_hit(index.into());
769 let lookup = match cached {
771 Err(lookup) => lookup,
774 let query = Q::make_vtable(tcx, &key);
775 let state = Q::query_state(tcx);
776 debug_assert!(!query.anon);
778 try_execute_query(tcx, state, cache, DUMMY_SP, key, lookup, Some(dep_node), &query);