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, DepKind, DepNode, DepNodeIndex, DepNodeParams};
6 use crate::ich::StableHashingContext;
7 use crate::query::caches::QueryCache;
8 use crate::query::config::QueryVTable;
9 use crate::query::job::{report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo};
10 use crate::query::{QueryContext, QueryMap, QuerySideEffects, QueryStackFrame};
11 use crate::values::Value;
12 use crate::HandleCycleError;
13 use rustc_data_structures::fingerprint::Fingerprint;
14 use rustc_data_structures::fx::FxHashMap;
15 #[cfg(parallel_compiler)]
16 use rustc_data_structures::profiling::TimingGuard;
17 #[cfg(parallel_compiler)]
18 use rustc_data_structures::sharded::Sharded;
19 use rustc_data_structures::sync::Lock;
20 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed, FatalError};
21 use rustc_session::Session;
22 use rustc_span::{Span, DUMMY_SP};
23 use std::borrow::Borrow;
25 use std::collections::hash_map::Entry;
30 use thin_vec::ThinVec;
32 use super::QueryConfig;
34 pub struct QueryState<K, D: DepKind> {
35 #[cfg(parallel_compiler)]
36 active: Sharded<FxHashMap<K, QueryResult<D>>>,
37 #[cfg(not(parallel_compiler))]
38 active: Lock<FxHashMap<K, QueryResult<D>>>,
41 /// Indicates the state of a query for a given key in a query map.
42 enum QueryResult<D: DepKind> {
43 /// An already executing query. The query job can be used to await for its completion.
46 /// The query panicked. Queries trying to wait on this will raise a fatal error which will
51 impl<K, D> QueryState<K, D>
53 K: Eq + Hash + Clone + Debug,
56 pub fn all_inactive(&self) -> bool {
57 #[cfg(parallel_compiler)]
59 let shards = self.active.lock_shards();
60 shards.iter().all(|shard| shard.is_empty())
62 #[cfg(not(parallel_compiler))]
64 self.active.lock().is_empty()
68 pub fn try_collect_active_jobs<Qcx: Copy>(
71 make_query: fn(Qcx, K) -> QueryStackFrame<D>,
72 jobs: &mut QueryMap<D>,
74 #[cfg(parallel_compiler)]
76 // We use try_lock_shards here since we are called from the
77 // deadlock handler, and this shouldn't be locked.
78 let shards = self.active.try_lock_shards()?;
79 for shard in shards.iter() {
80 for (k, v) in shard.iter() {
81 if let QueryResult::Started(ref job) = *v {
82 let query = make_query(qcx, k.clone());
83 jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
88 #[cfg(not(parallel_compiler))]
90 // We use try_lock here since we are called from the
91 // deadlock handler, and this shouldn't be locked.
92 // (FIXME: Is this relevant for non-parallel compilers? It doesn't
94 for (k, v) in self.active.try_lock()?.iter() {
95 if let QueryResult::Started(ref job) = *v {
96 let query = make_query(qcx, k.clone());
97 jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
106 impl<K, D: DepKind> Default for QueryState<K, D> {
107 fn default() -> QueryState<K, D> {
108 QueryState { active: Default::default() }
112 /// A type representing the responsibility to execute the job in the `job` field.
113 /// This will poison the relevant query if dropped.
114 struct JobOwner<'tcx, K, D: DepKind>
116 K: Eq + Hash + Clone,
118 state: &'tcx QueryState<K, D>,
125 fn mk_cycle<Qcx, V, R, D: DepKind>(
127 cycle_error: CycleError<D>,
128 handler: HandleCycleError,
129 cache: &dyn crate::query::QueryStorage<Value = V, Stored = R>,
132 Qcx: QueryContext + crate::query::HasDepContext<DepKind = D>,
133 V: std::fmt::Debug + Value<Qcx::DepContext, Qcx::DepKind>,
136 let error = report_cycle(qcx.dep_context().sess(), &cycle_error);
137 let value = handle_cycle_error(*qcx.dep_context(), &cycle_error, error, handler);
138 cache.store_nocache(value)
141 fn handle_cycle_error<Tcx, V>(
143 cycle_error: &CycleError<Tcx::DepKind>,
144 mut error: DiagnosticBuilder<'_, ErrorGuaranteed>,
145 handler: HandleCycleError,
149 V: Value<Tcx, Tcx::DepKind>,
151 use HandleCycleError::*;
155 Value::from_cycle_error(tcx, &cycle_error.cycle)
159 tcx.sess().abort_if_errors();
163 error.delay_as_bug();
164 Value::from_cycle_error(tcx, &cycle_error.cycle)
169 impl<'tcx, K, D: DepKind> JobOwner<'tcx, K, D>
171 K: Eq + Hash + Clone,
173 /// Either gets a `JobOwner` corresponding the query, allowing us to
174 /// start executing the query, or returns with the result of the query.
175 /// This function assumes that `try_get_cached` is already called and returned `lookup`.
176 /// If the query is executing elsewhere, this will wait for it and return the result.
177 /// If the query panicked, this will silently panic.
179 /// This function is inlined because that results in a noticeable speed-up
180 /// for some compile-time benchmarks.
182 fn try_start<'b, Qcx>(
184 state: &'b QueryState<K, Qcx::DepKind>,
187 ) -> TryGetJob<'b, K, D>
189 Qcx: QueryContext + crate::query::HasDepContext<DepKind = D>,
191 #[cfg(parallel_compiler)]
192 let mut state_lock = state.active.get_shard_by_value(&key).lock();
193 #[cfg(not(parallel_compiler))]
194 let mut state_lock = state.active.lock();
195 let lock = &mut *state_lock;
197 match lock.entry(key) {
198 Entry::Vacant(entry) => {
199 let id = qcx.next_job_id();
200 let job = qcx.current_query_job();
201 let job = QueryJob::new(id, span, job);
203 let key = entry.key().clone();
204 entry.insert(QueryResult::Started(job));
206 let owner = JobOwner { state, id, key };
207 return TryGetJob::NotYetStarted(owner);
209 Entry::Occupied(mut entry) => {
210 match entry.get_mut() {
211 #[cfg(not(parallel_compiler))]
212 QueryResult::Started(job) => {
216 // If we are single-threaded we know that we have cycle error,
217 // so we just return the error.
218 return TryGetJob::Cycle(id.find_cycle_in_stack(
219 qcx.try_collect_active_jobs().unwrap(),
220 &qcx.current_query_job(),
224 #[cfg(parallel_compiler)]
225 QueryResult::Started(job) => {
226 // For parallel queries, we'll block and wait until the query running
227 // in another thread has completed. Record how long we wait in the
229 let query_blocked_prof_timer = qcx.dep_context().profiler().query_blocked();
232 let latch = job.latch();
236 // With parallel queries we might just have to wait on some other
238 let result = latch.wait_on(qcx.current_query_job(), span);
241 Ok(()) => TryGetJob::JobCompleted(query_blocked_prof_timer),
242 Err(cycle) => TryGetJob::Cycle(cycle),
245 QueryResult::Poisoned => FatalError.raise(),
251 /// Completes the query by updating the query cache with the `result`,
252 /// signals the waiter and forgets the JobOwner, so it won't poison the query
253 fn complete<C>(self, cache: &C, result: C::Value, dep_node_index: DepNodeIndex) -> C::Stored
255 C: QueryCache<Key = K>,
257 // We can move out of `self` here because we `mem::forget` it below
258 let key = unsafe { ptr::read(&self.key) };
259 let state = self.state;
261 // Forget ourself so our destructor won't poison the query
264 let (job, result) = {
266 #[cfg(parallel_compiler)]
267 let mut lock = state.active.get_shard_by_value(&key).lock();
268 #[cfg(not(parallel_compiler))]
269 let mut lock = state.active.lock();
270 match lock.remove(&key).unwrap() {
271 QueryResult::Started(job) => job,
272 QueryResult::Poisoned => panic!(),
275 let result = cache.complete(key, result, dep_node_index);
279 job.signal_complete();
284 impl<'tcx, K, D> Drop for JobOwner<'tcx, K, D>
286 K: Eq + Hash + Clone,
292 // Poison the query so jobs waiting on it panic.
293 let state = self.state;
295 #[cfg(parallel_compiler)]
296 let mut shard = state.active.get_shard_by_value(&self.key).lock();
297 #[cfg(not(parallel_compiler))]
298 let mut shard = state.active.lock();
299 let job = match shard.remove(&self.key).unwrap() {
300 QueryResult::Started(job) => job,
301 QueryResult::Poisoned => panic!(),
303 shard.insert(self.key.clone(), QueryResult::Poisoned);
306 // Also signal the completion of the job, so waiters
307 // will continue execution.
308 job.signal_complete();
313 pub(crate) struct CycleError<D: DepKind> {
314 /// The query and related span that uses the cycle.
315 pub usage: Option<(Span, QueryStackFrame<D>)>,
316 pub cycle: Vec<QueryInfo<D>>,
319 /// The result of `try_start`.
320 enum TryGetJob<'tcx, K, D>
322 K: Eq + Hash + Clone,
325 /// The query is not yet started. Contains a guard to the cache eventually used to start it.
326 NotYetStarted(JobOwner<'tcx, K, D>),
328 /// The query was already completed.
329 /// Returns the result of the query and its dep-node index
330 /// if it succeeded or a cycle error if it failed.
331 #[cfg(parallel_compiler)]
332 JobCompleted(TimingGuard<'tcx>),
334 /// Trying to execute the query resulted in a cycle.
335 Cycle(CycleError<D>),
338 /// Checks if the query is already computed and in the cache.
339 /// It returns the shard index and a lock guard to the shard,
340 /// which will be used if the query is not in the cache and we need
343 pub fn try_get_cached<Tcx, C, R, OnHit>(
347 // `on_hit` can be called while holding a lock to the query cache
353 OnHit: FnOnce(&C::Stored) -> R,
355 cache.lookup(&key, |value, index| {
356 if std::intrinsics::unlikely(tcx.profiler().enabled()) {
357 tcx.profiler().query_cache_hit(index.into());
359 tcx.dep_graph().read_index(index);
364 fn try_execute_query<Qcx, C>(
366 state: &QueryState<C::Key, Qcx::DepKind>,
370 dep_node: Option<DepNode<Qcx::DepKind>>,
371 query: &QueryVTable<Qcx, C::Key, C::Value>,
372 ) -> (C::Stored, Option<DepNodeIndex>)
375 C::Key: Clone + DepNodeParams<Qcx::DepContext>,
376 C::Value: Value<Qcx::DepContext, Qcx::DepKind>,
377 C::Stored: Debug + std::borrow::Borrow<C::Value>,
380 match JobOwner::<'_, C::Key, Qcx::DepKind>::try_start(&qcx, state, span, key.clone()) {
381 TryGetJob::NotYetStarted(job) => {
382 let (result, dep_node_index) = execute_job(qcx, key.clone(), dep_node, query, job.id);
384 // We may have put a value inside the cache from inside the execution.
385 // Verify that it has the same hash as what we have now, to ensure consistency.
386 let _ = cache.lookup(&key, |cached_result, _| {
387 let hasher = query.hash_result.expect("feedable forbids no_hash");
388 let old_hash = qcx.dep_context().with_stable_hashing_context(|mut hcx| hasher(&mut hcx, cached_result.borrow()));
389 let new_hash = qcx.dep_context().with_stable_hashing_context(|mut hcx| hasher(&mut hcx, &result));
392 "Computed query value for {:?}({:?}) is inconsistent with fed value,\ncomputed={:#?}\nfed={:#?}",
393 query.dep_kind, key, result, cached_result,
397 let result = job.complete(cache, result, dep_node_index);
398 (result, Some(dep_node_index))
400 TryGetJob::Cycle(error) => {
401 let result = mk_cycle(qcx, error, query.handle_cycle_error, cache);
404 #[cfg(parallel_compiler)]
405 TryGetJob::JobCompleted(query_blocked_prof_timer) => {
406 let (v, index) = cache
407 .lookup(&key, |value, index| (value.clone(), index))
408 .unwrap_or_else(|_| panic!("value must be in cache after waiting"));
410 if std::intrinsics::unlikely(qcx.dep_context().profiler().enabled()) {
411 qcx.dep_context().profiler().query_cache_hit(index.into());
413 query_blocked_prof_timer.finish_with_query_invocation_id(index.into());
420 fn execute_job<Qcx, K, V>(
423 mut dep_node_opt: Option<DepNode<Qcx::DepKind>>,
424 query: &QueryVTable<Qcx, K, V>,
426 ) -> (V, DepNodeIndex)
428 K: Clone + DepNodeParams<Qcx::DepContext>,
432 let dep_graph = qcx.dep_context().dep_graph();
434 // Fast path for when incr. comp. is off.
435 if !dep_graph.is_fully_enabled() {
436 let prof_timer = qcx.dep_context().profiler().query_provider();
437 let result = qcx.start_query(job_id, query.depth_limit, None, || {
438 query.compute(*qcx.dep_context(), key)
440 let dep_node_index = dep_graph.next_virtual_depnode_index();
441 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
442 return (result, dep_node_index);
445 if !query.anon && !query.eval_always {
446 // `to_dep_node` is expensive for some `DepKind`s.
448 dep_node_opt.get_or_insert_with(|| query.to_dep_node(*qcx.dep_context(), &key));
450 // The diagnostics for this query will be promoted to the current session during
451 // `try_mark_green()`, so we can ignore them here.
452 if let Some(ret) = qcx.start_query(job_id, false, None, || {
453 try_load_from_disk_and_cache_in_memory(qcx, &key, &dep_node, query)
459 let prof_timer = qcx.dep_context().profiler().query_provider();
460 let diagnostics = Lock::new(ThinVec::new());
462 let (result, dep_node_index) =
463 qcx.start_query(job_id, query.depth_limit, Some(&diagnostics), || {
465 return dep_graph.with_anon_task(*qcx.dep_context(), query.dep_kind, || {
466 query.compute(*qcx.dep_context(), key)
470 // `to_dep_node` is expensive for some `DepKind`s.
472 dep_node_opt.unwrap_or_else(|| query.to_dep_node(*qcx.dep_context(), &key));
474 dep_graph.with_task(dep_node, *qcx.dep_context(), key, query.compute, query.hash_result)
477 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
479 let diagnostics = diagnostics.into_inner();
480 let side_effects = QuerySideEffects { diagnostics };
482 if std::intrinsics::unlikely(!side_effects.is_empty()) {
484 qcx.store_side_effects_for_anon_node(dep_node_index, side_effects);
486 qcx.store_side_effects(dep_node_index, side_effects);
490 (result, dep_node_index)
493 fn try_load_from_disk_and_cache_in_memory<Qcx, K, V>(
496 dep_node: &DepNode<Qcx::DepKind>,
497 query: &QueryVTable<Qcx, K, V>,
498 ) -> Option<(V, DepNodeIndex)>
504 // Note this function can be called concurrently from the same query
505 // We must ensure that this is handled correctly.
507 let dep_graph = qcx.dep_context().dep_graph();
508 let (prev_dep_node_index, dep_node_index) = dep_graph.try_mark_green(qcx, &dep_node)?;
510 debug_assert!(dep_graph.is_green(dep_node));
512 // First we try to load the result from the on-disk cache.
513 // Some things are never cached on disk.
514 if let Some(try_load_from_disk) = query.try_load_from_disk {
515 let prof_timer = qcx.dep_context().profiler().incr_cache_loading();
517 // The call to `with_query_deserialization` enforces that no new `DepNodes`
518 // are created during deserialization. See the docs of that method for more
521 dep_graph.with_query_deserialization(|| try_load_from_disk(qcx, prev_dep_node_index));
523 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
525 if let Some(result) = result {
526 if std::intrinsics::unlikely(
527 qcx.dep_context().sess().opts.unstable_opts.query_dep_graph,
529 dep_graph.mark_debug_loaded_from_disk(*dep_node)
532 let prev_fingerprint = qcx
535 .prev_fingerprint_of(dep_node)
536 .unwrap_or(Fingerprint::ZERO);
537 // If `-Zincremental-verify-ich` is specified, re-hash results from
538 // the cache and make sure that they have the expected fingerprint.
540 // If not, we still seek to verify a subset of fingerprints loaded
541 // from disk. Re-hashing results is fairly expensive, so we can't
542 // currently afford to verify every hash. This subset should still
543 // give us some coverage of potential bugs though.
544 let try_verify = prev_fingerprint.as_value().1 % 32 == 0;
545 if std::intrinsics::unlikely(
546 try_verify || qcx.dep_context().sess().opts.unstable_opts.incremental_verify_ich,
548 incremental_verify_ich(*qcx.dep_context(), &result, dep_node, query.hash_result);
551 return Some((result, dep_node_index));
554 // We always expect to find a cached result for things that
555 // can be forced from `DepNode`.
557 !qcx.dep_context().fingerprint_style(dep_node.kind).reconstructible(),
558 "missing on-disk cache entry for {:?}",
563 // We could not load a result from the on-disk cache, so
565 let prof_timer = qcx.dep_context().profiler().query_provider();
567 // The dep-graph for this computation is already in-place.
568 let result = dep_graph.with_ignore(|| query.compute(*qcx.dep_context(), key.clone()));
570 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
572 // Verify that re-running the query produced a result with the expected hash
573 // This catches bugs in query implementations, turning them into ICEs.
574 // For example, a query might sort its result by `DefId` - since `DefId`s are
575 // not stable across compilation sessions, the result could get up getting sorted
576 // in a different order when the query is re-run, even though all of the inputs
577 // (e.g. `DefPathHash` values) were green.
579 // See issue #82920 for an example of a miscompilation that would get turned into
580 // an ICE by this check
581 incremental_verify_ich(*qcx.dep_context(), &result, dep_node, query.hash_result);
583 Some((result, dep_node_index))
586 #[instrument(skip(tcx, result, hash_result), level = "debug")]
587 pub(crate) fn incremental_verify_ich<Tcx, V: Debug>(
590 dep_node: &DepNode<Tcx::DepKind>,
591 hash_result: Option<fn(&mut StableHashingContext<'_>, &V) -> Fingerprint>,
597 tcx.dep_graph().is_green(dep_node),
598 "fingerprint for green query instance not loaded from cache: {:?}",
602 let new_hash = hash_result.map_or(Fingerprint::ZERO, |f| {
603 tcx.with_stable_hashing_context(|mut hcx| f(&mut hcx, result))
606 let old_hash = tcx.dep_graph().prev_fingerprint_of(dep_node);
608 if Some(new_hash) != old_hash {
609 incremental_verify_ich_failed(
611 DebugArg::from(&dep_node),
612 DebugArg::from(&result),
619 // This DebugArg business is largely a mirror of std::fmt::ArgumentV1, which is
620 // currently not exposed publicly.
622 // The PR which added this attempted to use `&dyn Debug` instead, but that
623 // showed statistically significant worse compiler performance. It's not
624 // actually clear what the cause there was -- the code should be cold. If this
625 // can be replaced with `&dyn Debug` with on perf impact, then it probably
631 struct DebugArg<'a> {
633 fmt: fn(&Opaque, &mut std::fmt::Formatter<'_>) -> std::fmt::Result,
636 impl<'a, T> From<&'a T> for DebugArg<'a>
640 fn from(value: &'a T) -> DebugArg<'a> {
642 value: unsafe { std::mem::transmute(value) },
644 std::mem::transmute(<T as std::fmt::Debug>::fmt as fn(_, _) -> std::fmt::Result)
650 impl std::fmt::Debug for DebugArg<'_> {
651 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
652 (self.fmt)(self.value, f)
656 // Note that this is marked #[cold] and intentionally takes the equivalent of
657 // `dyn Debug` for its arguments, as we want to avoid generating a bunch of
658 // different implementations for LLVM to chew on (and filling up the final
661 fn incremental_verify_ich_failed(sess: &Session, dep_node: DebugArg<'_>, result: DebugArg<'_>) {
662 // When we emit an error message and panic, we try to debug-print the `DepNode`
663 // and query result. Unfortunately, this can cause us to run additional queries,
664 // which may result in another fingerprint mismatch while we're in the middle
665 // of processing this one. To avoid a double-panic (which kills the process
666 // before we can print out the query static), we print out a terse
667 // but 'safe' message if we detect a re-entrant call to this method.
669 static INSIDE_VERIFY_PANIC: Cell<bool> = const { Cell::new(false) };
672 let old_in_panic = INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.replace(true));
675 sess.emit_err(crate::error::Reentrant);
677 let run_cmd = if let Some(crate_name) = &sess.opts.crate_name {
678 format!("`cargo clean -p {}` or `cargo clean`", crate_name)
680 "`cargo clean`".to_string()
683 sess.emit_err(crate::error::IncrementCompilation {
685 dep_node: format!("{:?}", dep_node),
687 panic!("Found unstable fingerprints for {:?}: {:?}", dep_node, result);
690 INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.set(old_in_panic));
693 /// Ensure that either this query has all green inputs or been executed.
694 /// Executing `query::ensure(D)` is considered a read of the dep-node `D`.
695 /// Returns true if the query should still run.
697 /// This function is particularly useful when executing passes for their
698 /// side-effects -- e.g., in order to report errors for erroneous programs.
700 /// Note: The optimization is only available during incr. comp.
702 fn ensure_must_run<Qcx, K, V>(
705 query: &QueryVTable<Qcx, K, V>,
706 ) -> (bool, Option<DepNode<Qcx::DepKind>>)
708 K: crate::dep_graph::DepNodeParams<Qcx::DepContext>,
711 if query.eval_always {
715 // Ensuring an anonymous query makes no sense
716 assert!(!query.anon);
718 let dep_node = query.to_dep_node(*qcx.dep_context(), key);
720 let dep_graph = qcx.dep_context().dep_graph();
721 match dep_graph.try_mark_green(qcx, &dep_node) {
723 // A None return from `try_mark_green` means that this is either
724 // a new dep node or that the dep node has already been marked red.
725 // Either way, we can't call `dep_graph.read()` as we don't have the
726 // DepNodeIndex. We must invoke the query itself. The performance cost
727 // this introduces should be negligible as we'll immediately hit the
728 // in-memory cache, or another query down the line will.
729 (true, Some(dep_node))
731 Some((_, dep_node_index)) => {
732 dep_graph.read_index(dep_node_index);
733 qcx.dep_context().profiler().query_cache_hit(dep_node_index.into());
745 pub fn get_query<Q, Qcx, D>(qcx: Qcx, span: Span, key: Q::Key, mode: QueryMode) -> Option<Q::Stored>
749 Q::Key: DepNodeParams<Qcx::DepContext>,
750 Q::Value: Value<Qcx::DepContext, D>,
753 let query = Q::make_vtable(qcx, &key);
754 let dep_node = if let QueryMode::Ensure = mode {
755 let (must_run, dep_node) = ensure_must_run(qcx, &key, &query);
764 let (result, dep_node_index) = try_execute_query(
773 if let Some(dep_node_index) = dep_node_index {
774 qcx.dep_context().dep_graph().read_index(dep_node_index)
779 pub fn force_query<Q, Qcx, D>(qcx: Qcx, key: Q::Key, dep_node: DepNode<Qcx::DepKind>)
783 Q::Key: DepNodeParams<Qcx::DepContext>,
784 Q::Value: Value<Qcx::DepContext, D>,
787 // We may be concurrently trying both execute and force a query.
788 // Ensure that only one of them runs the query.
789 let cache = Q::query_cache(qcx);
790 let cached = cache.lookup(&key, |_, index| {
791 if std::intrinsics::unlikely(qcx.dep_context().profiler().enabled()) {
792 qcx.dep_context().profiler().query_cache_hit(index.into());
801 let query = Q::make_vtable(qcx, &key);
802 let state = Q::query_state(qcx);
803 debug_assert!(!query.anon);
805 try_execute_query(qcx, state, cache, DUMMY_SP, key, Some(dep_node), &query);