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::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> {
35 #[cfg(parallel_compiler)]
36 active: Sharded<FxHashMap<K, QueryResult>>,
37 #[cfg(not(parallel_compiler))]
38 active: Lock<FxHashMap<K, QueryResult>>,
41 /// Indicates the state of a query for a given key in a query map.
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
53 K: Eq + Hash + Clone + Debug,
55 pub fn all_inactive(&self) -> bool {
56 #[cfg(parallel_compiler)]
58 let shards = self.active.lock_shards();
59 shards.iter().all(|shard| shard.is_empty())
61 #[cfg(not(parallel_compiler))]
63 self.active.lock().is_empty()
67 pub fn try_collect_active_jobs<Qcx: Copy>(
70 make_query: fn(Qcx, K) -> QueryStackFrame,
73 #[cfg(parallel_compiler)]
75 // We use try_lock_shards here since we are called from the
76 // deadlock handler, and this shouldn't be locked.
77 let shards = self.active.try_lock_shards()?;
78 for shard in shards.iter() {
79 for (k, v) in shard.iter() {
80 if let QueryResult::Started(ref job) = *v {
81 let query = make_query(qcx, k.clone());
82 jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
87 #[cfg(not(parallel_compiler))]
89 // We use try_lock here since we are called from the
90 // deadlock handler, and this shouldn't be locked.
91 // (FIXME: Is this relevant for non-parallel compilers? It doesn't
93 for (k, v) in self.active.try_lock()?.iter() {
94 if let QueryResult::Started(ref job) = *v {
95 let query = make_query(qcx, k.clone());
96 jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
105 impl<K> Default for QueryState<K> {
106 fn default() -> QueryState<K> {
107 QueryState { active: Default::default() }
111 /// A type representing the responsibility to execute the job in the `job` field.
112 /// This will poison the relevant query if dropped.
113 struct JobOwner<'tcx, K>
115 K: Eq + Hash + Clone,
117 state: &'tcx QueryState<K>,
124 fn mk_cycle<Qcx, V, R>(
126 cycle_error: CycleError,
127 handler: HandleCycleError,
128 cache: &dyn crate::query::QueryStorage<Value = V, Stored = R>,
132 V: std::fmt::Debug + Value<Qcx::DepContext>,
135 let error = report_cycle(qcx.dep_context().sess(), &cycle_error);
136 let value = handle_cycle_error(*qcx.dep_context(), &cycle_error, error, handler);
137 cache.store_nocache(value)
140 fn handle_cycle_error<Tcx, V>(
142 cycle_error: &CycleError,
143 mut error: DiagnosticBuilder<'_, ErrorGuaranteed>,
144 handler: HandleCycleError,
150 use HandleCycleError::*;
154 Value::from_cycle_error(tcx, &cycle_error.cycle)
158 tcx.sess().abort_if_errors();
162 error.delay_as_bug();
163 Value::from_cycle_error(tcx, &cycle_error.cycle)
168 impl<'tcx, K> JobOwner<'tcx, K>
170 K: Eq + Hash + Clone,
172 /// Either gets a `JobOwner` corresponding the query, allowing us to
173 /// start executing the query, or returns with the result of the query.
174 /// This function assumes that `try_get_cached` is already called and returned `lookup`.
175 /// If the query is executing elsewhere, this will wait for it and return the result.
176 /// If the query panicked, this will silently panic.
178 /// This function is inlined because that results in a noticeable speed-up
179 /// for some compile-time benchmarks.
181 fn try_start<'b, Qcx>(
183 state: &'b QueryState<K>,
186 ) -> TryGetJob<'b, K>
190 #[cfg(parallel_compiler)]
191 let mut state_lock = state.active.get_shard_by_value(&key).lock();
192 #[cfg(not(parallel_compiler))]
193 let mut state_lock = state.active.lock();
194 let lock = &mut *state_lock;
196 match lock.entry(key) {
197 Entry::Vacant(entry) => {
198 let id = qcx.next_job_id();
199 let job = qcx.current_query_job();
200 let job = QueryJob::new(id, span, job);
202 let key = entry.key().clone();
203 entry.insert(QueryResult::Started(job));
205 let owner = JobOwner { state, id, key };
206 return TryGetJob::NotYetStarted(owner);
208 Entry::Occupied(mut entry) => {
209 match entry.get_mut() {
210 #[cfg(not(parallel_compiler))]
211 QueryResult::Started(job) => {
215 // If we are single-threaded we know that we have cycle error,
216 // so we just return the error.
217 return TryGetJob::Cycle(id.find_cycle_in_stack(
218 qcx.try_collect_active_jobs().unwrap(),
219 &qcx.current_query_job(),
223 #[cfg(parallel_compiler)]
224 QueryResult::Started(job) => {
225 // For parallel queries, we'll block and wait until the query running
226 // in another thread has completed. Record how long we wait in the
228 let query_blocked_prof_timer = qcx.dep_context().profiler().query_blocked();
231 let latch = job.latch();
235 // With parallel queries we might just have to wait on some other
237 let result = latch.wait_on(qcx.current_query_job(), span);
240 Ok(()) => TryGetJob::JobCompleted(query_blocked_prof_timer),
241 Err(cycle) => TryGetJob::Cycle(cycle),
244 QueryResult::Poisoned => FatalError.raise(),
250 /// Completes the query by updating the query cache with the `result`,
251 /// signals the waiter and forgets the JobOwner, so it won't poison the query
252 fn complete<C>(self, cache: &C, result: C::Value, dep_node_index: DepNodeIndex) -> C::Stored
254 C: QueryCache<Key = K>,
256 // We can move out of `self` here because we `mem::forget` it below
257 let key = unsafe { ptr::read(&self.key) };
258 let state = self.state;
260 // Forget ourself so our destructor won't poison the query
263 let (job, result) = {
265 #[cfg(parallel_compiler)]
266 let mut lock = state.active.get_shard_by_value(&key).lock();
267 #[cfg(not(parallel_compiler))]
268 let mut lock = state.active.lock();
269 match lock.remove(&key).unwrap() {
270 QueryResult::Started(job) => job,
271 QueryResult::Poisoned => panic!(),
274 let result = cache.complete(key, result, dep_node_index);
278 job.signal_complete();
283 impl<'tcx, K> Drop for JobOwner<'tcx, K>
285 K: Eq + Hash + Clone,
290 // Poison the query so jobs waiting on it panic.
291 let state = self.state;
293 #[cfg(parallel_compiler)]
294 let mut shard = state.active.get_shard_by_value(&self.key).lock();
295 #[cfg(not(parallel_compiler))]
296 let mut shard = state.active.lock();
297 let job = match shard.remove(&self.key).unwrap() {
298 QueryResult::Started(job) => job,
299 QueryResult::Poisoned => panic!(),
301 shard.insert(self.key.clone(), QueryResult::Poisoned);
304 // Also signal the completion of the job, so waiters
305 // will continue execution.
306 job.signal_complete();
311 pub(crate) struct CycleError {
312 /// The query and related span that uses the cycle.
313 pub usage: Option<(Span, QueryStackFrame)>,
314 pub cycle: Vec<QueryInfo>,
317 /// The result of `try_start`.
318 enum TryGetJob<'tcx, K>
320 K: Eq + Hash + Clone,
322 /// The query is not yet started. Contains a guard to the cache eventually used to start it.
323 NotYetStarted(JobOwner<'tcx, K>),
325 /// The query was already completed.
326 /// Returns the result of the query and its dep-node index
327 /// if it succeeded or a cycle error if it failed.
328 #[cfg(parallel_compiler)]
329 JobCompleted(TimingGuard<'tcx>),
331 /// Trying to execute the query resulted in a cycle.
335 /// Checks if the query is already computed and in the cache.
336 /// It returns the shard index and a lock guard to the shard,
337 /// which will be used if the query is not in the cache and we need
340 pub fn try_get_cached<'a, Tcx, C, R, OnHit>(
344 // `on_hit` can be called while holding a lock to the query cache
350 OnHit: FnOnce(&C::Stored) -> R,
352 cache.lookup(&key, |value, index| {
353 if std::intrinsics::unlikely(tcx.profiler().enabled()) {
354 tcx.profiler().query_cache_hit(index.into());
356 tcx.dep_graph().read_index(index);
361 fn try_execute_query<Qcx, C>(
363 state: &QueryState<C::Key>,
367 dep_node: Option<DepNode<Qcx::DepKind>>,
368 query: &QueryVTable<Qcx, C::Key, C::Value>,
369 ) -> (C::Stored, Option<DepNodeIndex>)
372 C::Key: Clone + DepNodeParams<Qcx::DepContext>,
373 C::Value: Value<Qcx::DepContext>,
374 C::Stored: Debug + std::borrow::Borrow<C::Value>,
377 match JobOwner::<'_, C::Key>::try_start(&qcx, state, span, key.clone()) {
378 TryGetJob::NotYetStarted(job) => {
379 let (result, dep_node_index) = execute_job(qcx, key.clone(), dep_node, query, job.id);
381 // We may have put a value inside the cache from inside the execution.
382 // Verify that it has the same hash as what we have now, to ensure consistency.
383 let _ = cache.lookup(&key, |cached_result, _| {
384 let hasher = query.hash_result.expect("feedable forbids no_hash");
385 let old_hash = qcx.dep_context().with_stable_hashing_context(|mut hcx| hasher(&mut hcx, cached_result.borrow()));
386 let new_hash = qcx.dep_context().with_stable_hashing_context(|mut hcx| hasher(&mut hcx, &result));
389 "Computed query value for {:?}({:?}) is inconsistent with fed value,\ncomputed={:#?}\nfed={:#?}",
390 query.dep_kind, key, result, cached_result,
394 let result = job.complete(cache, result, dep_node_index);
395 (result, Some(dep_node_index))
397 TryGetJob::Cycle(error) => {
398 let result = mk_cycle(qcx, error, query.handle_cycle_error, cache);
401 #[cfg(parallel_compiler)]
402 TryGetJob::JobCompleted(query_blocked_prof_timer) => {
403 let (v, index) = cache
404 .lookup(&key, |value, index| (value.clone(), index))
405 .unwrap_or_else(|_| panic!("value must be in cache after waiting"));
407 if std::intrinsics::unlikely(qcx.dep_context().profiler().enabled()) {
408 qcx.dep_context().profiler().query_cache_hit(index.into());
410 query_blocked_prof_timer.finish_with_query_invocation_id(index.into());
417 fn execute_job<Qcx, K, V>(
420 mut dep_node_opt: Option<DepNode<Qcx::DepKind>>,
421 query: &QueryVTable<Qcx, K, V>,
423 ) -> (V, DepNodeIndex)
425 K: Clone + DepNodeParams<Qcx::DepContext>,
429 let dep_graph = qcx.dep_context().dep_graph();
431 // Fast path for when incr. comp. is off.
432 if !dep_graph.is_fully_enabled() {
433 let prof_timer = qcx.dep_context().profiler().query_provider();
434 let result = qcx.start_query(job_id, query.depth_limit, None, || {
435 query.compute(*qcx.dep_context(), key)
437 let dep_node_index = dep_graph.next_virtual_depnode_index();
438 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
439 return (result, dep_node_index);
442 if !query.anon && !query.eval_always {
443 // `to_dep_node` is expensive for some `DepKind`s.
445 dep_node_opt.get_or_insert_with(|| query.to_dep_node(*qcx.dep_context(), &key));
447 // The diagnostics for this query will be promoted to the current session during
448 // `try_mark_green()`, so we can ignore them here.
449 if let Some(ret) = qcx.start_query(job_id, false, None, || {
450 try_load_from_disk_and_cache_in_memory(qcx, &key, &dep_node, query)
456 let prof_timer = qcx.dep_context().profiler().query_provider();
457 let diagnostics = Lock::new(ThinVec::new());
459 let (result, dep_node_index) =
460 qcx.start_query(job_id, query.depth_limit, Some(&diagnostics), || {
462 return dep_graph.with_anon_task(*qcx.dep_context(), query.dep_kind, || {
463 query.compute(*qcx.dep_context(), key)
467 // `to_dep_node` is expensive for some `DepKind`s.
469 dep_node_opt.unwrap_or_else(|| query.to_dep_node(*qcx.dep_context(), &key));
471 dep_graph.with_task(dep_node, *qcx.dep_context(), key, query.compute, query.hash_result)
474 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
476 let diagnostics = diagnostics.into_inner();
477 let side_effects = QuerySideEffects { diagnostics };
479 if std::intrinsics::unlikely(!side_effects.is_empty()) {
481 qcx.store_side_effects_for_anon_node(dep_node_index, side_effects);
483 qcx.store_side_effects(dep_node_index, side_effects);
487 (result, dep_node_index)
490 fn try_load_from_disk_and_cache_in_memory<Qcx, K, V>(
493 dep_node: &DepNode<Qcx::DepKind>,
494 query: &QueryVTable<Qcx, K, V>,
495 ) -> Option<(V, DepNodeIndex)>
501 // Note this function can be called concurrently from the same query
502 // We must ensure that this is handled correctly.
504 let dep_graph = qcx.dep_context().dep_graph();
505 let (prev_dep_node_index, dep_node_index) = dep_graph.try_mark_green(qcx, &dep_node)?;
507 debug_assert!(dep_graph.is_green(dep_node));
509 // First we try to load the result from the on-disk cache.
510 // Some things are never cached on disk.
511 if let Some(try_load_from_disk) = query.try_load_from_disk {
512 let prof_timer = qcx.dep_context().profiler().incr_cache_loading();
514 // The call to `with_query_deserialization` enforces that no new `DepNodes`
515 // are created during deserialization. See the docs of that method for more
518 dep_graph.with_query_deserialization(|| try_load_from_disk(qcx, prev_dep_node_index));
520 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
522 if let Some(result) = result {
523 if std::intrinsics::unlikely(
524 qcx.dep_context().sess().opts.unstable_opts.query_dep_graph,
526 dep_graph.mark_debug_loaded_from_disk(*dep_node)
529 let prev_fingerprint = qcx
532 .prev_fingerprint_of(dep_node)
533 .unwrap_or(Fingerprint::ZERO);
534 // If `-Zincremental-verify-ich` is specified, re-hash results from
535 // the cache and make sure that they have the expected fingerprint.
537 // If not, we still seek to verify a subset of fingerprints loaded
538 // from disk. Re-hashing results is fairly expensive, so we can't
539 // currently afford to verify every hash. This subset should still
540 // give us some coverage of potential bugs though.
541 let try_verify = prev_fingerprint.as_value().1 % 32 == 0;
542 if std::intrinsics::unlikely(
543 try_verify || qcx.dep_context().sess().opts.unstable_opts.incremental_verify_ich,
545 incremental_verify_ich(*qcx.dep_context(), &result, dep_node, query.hash_result);
548 return Some((result, dep_node_index));
551 // We always expect to find a cached result for things that
552 // can be forced from `DepNode`.
554 !qcx.dep_context().fingerprint_style(dep_node.kind).reconstructible(),
555 "missing on-disk cache entry for {:?}",
560 // We could not load a result from the on-disk cache, so
562 let prof_timer = qcx.dep_context().profiler().query_provider();
564 // The dep-graph for this computation is already in-place.
565 let result = dep_graph.with_ignore(|| query.compute(*qcx.dep_context(), key.clone()));
567 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
569 // Verify that re-running the query produced a result with the expected hash
570 // This catches bugs in query implementations, turning them into ICEs.
571 // For example, a query might sort its result by `DefId` - since `DefId`s are
572 // not stable across compilation sessions, the result could get up getting sorted
573 // in a different order when the query is re-run, even though all of the inputs
574 // (e.g. `DefPathHash` values) were green.
576 // See issue #82920 for an example of a miscompilation that would get turned into
577 // an ICE by this check
578 incremental_verify_ich(*qcx.dep_context(), &result, dep_node, query.hash_result);
580 Some((result, dep_node_index))
583 #[instrument(skip(tcx, result, hash_result), level = "debug")]
584 pub(crate) fn incremental_verify_ich<Tcx, V: Debug>(
587 dep_node: &DepNode<Tcx::DepKind>,
588 hash_result: Option<fn(&mut StableHashingContext<'_>, &V) -> Fingerprint>,
594 tcx.dep_graph().is_green(dep_node),
595 "fingerprint for green query instance not loaded from cache: {:?}",
599 let new_hash = hash_result.map_or(Fingerprint::ZERO, |f| {
600 tcx.with_stable_hashing_context(|mut hcx| f(&mut hcx, result))
603 let old_hash = tcx.dep_graph().prev_fingerprint_of(dep_node);
605 if Some(new_hash) != old_hash {
606 incremental_verify_ich_failed(
608 DebugArg::from(&dep_node),
609 DebugArg::from(&result),
616 // This DebugArg business is largely a mirror of std::fmt::ArgumentV1, which is
617 // currently not exposed publicly.
619 // The PR which added this attempted to use `&dyn Debug` instead, but that
620 // showed statistically significant worse compiler performance. It's not
621 // actually clear what the cause there was -- the code should be cold. If this
622 // can be replaced with `&dyn Debug` with on perf impact, then it probably
628 struct DebugArg<'a> {
630 fmt: fn(&Opaque, &mut std::fmt::Formatter<'_>) -> std::fmt::Result,
633 impl<'a, T> From<&'a T> for DebugArg<'a>
637 fn from(value: &'a T) -> DebugArg<'a> {
639 value: unsafe { std::mem::transmute(value) },
641 std::mem::transmute(<T as std::fmt::Debug>::fmt as fn(_, _) -> std::fmt::Result)
647 impl std::fmt::Debug for DebugArg<'_> {
648 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
649 (self.fmt)(self.value, f)
653 // Note that this is marked #[cold] and intentionally takes the equivalent of
654 // `dyn Debug` for its arguments, as we want to avoid generating a bunch of
655 // different implementations for LLVM to chew on (and filling up the final
658 fn incremental_verify_ich_failed(sess: &Session, dep_node: DebugArg<'_>, result: DebugArg<'_>) {
659 // When we emit an error message and panic, we try to debug-print the `DepNode`
660 // and query result. Unfortunately, this can cause us to run additional queries,
661 // which may result in another fingerprint mismatch while we're in the middle
662 // of processing this one. To avoid a double-panic (which kills the process
663 // before we can print out the query static), we print out a terse
664 // but 'safe' message if we detect a re-entrant call to this method.
666 static INSIDE_VERIFY_PANIC: Cell<bool> = const { Cell::new(false) };
669 let old_in_panic = INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.replace(true));
672 sess.emit_err(crate::error::Reentrant);
674 let run_cmd = if let Some(crate_name) = &sess.opts.crate_name {
675 format!("`cargo clean -p {}` or `cargo clean`", crate_name)
677 "`cargo clean`".to_string()
680 sess.emit_err(crate::error::IncrementCompilation {
682 dep_node: format!("{:?}", dep_node),
684 panic!("Found unstable fingerprints for {:?}: {:?}", dep_node, result);
687 INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.set(old_in_panic));
690 /// Ensure that either this query has all green inputs or been executed.
691 /// Executing `query::ensure(D)` is considered a read of the dep-node `D`.
692 /// Returns true if the query should still run.
694 /// This function is particularly useful when executing passes for their
695 /// side-effects -- e.g., in order to report errors for erroneous programs.
697 /// Note: The optimization is only available during incr. comp.
699 fn ensure_must_run<Qcx, K, V>(
702 query: &QueryVTable<Qcx, K, V>,
703 ) -> (bool, Option<DepNode<Qcx::DepKind>>)
705 K: crate::dep_graph::DepNodeParams<Qcx::DepContext>,
708 if query.eval_always {
712 // Ensuring an anonymous query makes no sense
713 assert!(!query.anon);
715 let dep_node = query.to_dep_node(*qcx.dep_context(), key);
717 let dep_graph = qcx.dep_context().dep_graph();
718 match dep_graph.try_mark_green(qcx, &dep_node) {
720 // A None return from `try_mark_green` means that this is either
721 // a new dep node or that the dep node has already been marked red.
722 // Either way, we can't call `dep_graph.read()` as we don't have the
723 // DepNodeIndex. We must invoke the query itself. The performance cost
724 // this introduces should be negligible as we'll immediately hit the
725 // in-memory cache, or another query down the line will.
726 (true, Some(dep_node))
728 Some((_, dep_node_index)) => {
729 dep_graph.read_index(dep_node_index);
730 qcx.dep_context().profiler().query_cache_hit(dep_node_index.into());
742 pub fn get_query<Q, Qcx>(qcx: Qcx, span: Span, key: Q::Key, mode: QueryMode) -> Option<Q::Stored>
745 Q::Key: DepNodeParams<Qcx::DepContext>,
746 Q::Value: Value<Qcx::DepContext>,
749 let query = Q::make_vtable(qcx, &key);
750 let dep_node = if let QueryMode::Ensure = mode {
751 let (must_run, dep_node) = ensure_must_run(qcx, &key, &query);
760 let (result, dep_node_index) = try_execute_query(
769 if let Some(dep_node_index) = dep_node_index {
770 qcx.dep_context().dep_graph().read_index(dep_node_index)
775 pub fn force_query<Q, Qcx>(qcx: Qcx, key: Q::Key, dep_node: DepNode<Qcx::DepKind>)
778 Q::Key: DepNodeParams<Qcx::DepContext>,
779 Q::Value: Value<Qcx::DepContext>,
782 // We may be concurrently trying both execute and force a query.
783 // Ensure that only one of them runs the query.
784 let cache = Q::query_cache(qcx);
785 let cached = cache.lookup(&key, |_, index| {
786 if std::intrinsics::unlikely(qcx.dep_context().profiler().enabled()) {
787 qcx.dep_context().profiler().query_cache_hit(index.into());
796 let query = Q::make_vtable(qcx, &key);
797 let state = Q::query_state(qcx);
798 debug_assert!(!query.anon);
800 try_execute_query(qcx, state, cache, DUMMY_SP, key, Some(dep_node), &query);