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};
6 use crate::ich::StableHashingContext;
7 use crate::query::caches::QueryCache;
8 use crate::query::job::{report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo};
9 use crate::query::{QueryContext, QueryMap, QuerySideEffects, QueryStackFrame};
10 use crate::values::Value;
11 use crate::HandleCycleError;
12 use rustc_data_structures::fingerprint::Fingerprint;
13 use rustc_data_structures::fx::FxHashMap;
14 #[cfg(parallel_compiler)]
15 use rustc_data_structures::profiling::TimingGuard;
16 #[cfg(parallel_compiler)]
17 use rustc_data_structures::sharded::Sharded;
18 use rustc_data_structures::sync::Lock;
19 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed, FatalError};
20 use rustc_session::Session;
21 use rustc_span::{Span, DUMMY_SP};
22 use std::borrow::Borrow;
24 use std::collections::hash_map::Entry;
29 use thin_vec::ThinVec;
31 use super::QueryConfig;
33 pub struct QueryState<K, D: DepKind> {
34 #[cfg(parallel_compiler)]
35 active: Sharded<FxHashMap<K, QueryResult<D>>>,
36 #[cfg(not(parallel_compiler))]
37 active: Lock<FxHashMap<K, QueryResult<D>>>,
40 /// Indicates the state of a query for a given key in a query map.
41 enum QueryResult<D: DepKind> {
42 /// An already executing query. The query job can be used to await for its completion.
45 /// The query panicked. Queries trying to wait on this will raise a fatal error which will
50 impl<K, D> QueryState<K, D>
52 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<D>,
71 jobs: &mut QueryMap<D>,
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, D: DepKind> Default for QueryState<K, D> {
106 fn default() -> QueryState<K, D> {
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, D: DepKind>
115 K: Eq + Hash + Clone,
117 state: &'tcx QueryState<K, D>,
124 fn mk_cycle<Qcx, R, D: DepKind>(
126 cycle_error: CycleError<D>,
127 handler: HandleCycleError,
130 Qcx: QueryContext + crate::query::HasDepContext<DepKind = D>,
131 R: std::fmt::Debug + Value<Qcx::DepContext, Qcx::DepKind>,
133 let error = report_cycle(qcx.dep_context().sess(), &cycle_error);
134 handle_cycle_error(*qcx.dep_context(), &cycle_error, error, handler)
137 fn handle_cycle_error<Tcx, V>(
139 cycle_error: &CycleError<Tcx::DepKind>,
140 mut error: DiagnosticBuilder<'_, ErrorGuaranteed>,
141 handler: HandleCycleError,
145 V: Value<Tcx, Tcx::DepKind>,
147 use HandleCycleError::*;
151 Value::from_cycle_error(tcx, &cycle_error.cycle)
155 tcx.sess().abort_if_errors();
159 error.delay_as_bug();
160 Value::from_cycle_error(tcx, &cycle_error.cycle)
165 impl<'tcx, K, D: DepKind> JobOwner<'tcx, K, D>
167 K: Eq + Hash + Clone,
169 /// Either gets a `JobOwner` corresponding the query, allowing us to
170 /// start executing the query, or returns with the result of the query.
171 /// This function assumes that `try_get_cached` is already called and returned `lookup`.
172 /// If the query is executing elsewhere, this will wait for it and return the result.
173 /// If the query panicked, this will silently panic.
175 /// This function is inlined because that results in a noticeable speed-up
176 /// for some compile-time benchmarks.
178 fn try_start<'b, Qcx>(
180 state: &'b QueryState<K, Qcx::DepKind>,
183 ) -> TryGetJob<'b, K, D>
185 Qcx: QueryContext + crate::query::HasDepContext<DepKind = D>,
187 #[cfg(parallel_compiler)]
188 let mut state_lock = state.active.get_shard_by_value(&key).lock();
189 #[cfg(not(parallel_compiler))]
190 let mut state_lock = state.active.lock();
191 let lock = &mut *state_lock;
193 match lock.entry(key) {
194 Entry::Vacant(entry) => {
195 let id = qcx.next_job_id();
196 let job = qcx.current_query_job();
197 let job = QueryJob::new(id, span, job);
199 let key = entry.key().clone();
200 entry.insert(QueryResult::Started(job));
202 let owner = JobOwner { state, id, key };
203 return TryGetJob::NotYetStarted(owner);
205 Entry::Occupied(mut entry) => {
206 match entry.get_mut() {
207 #[cfg(not(parallel_compiler))]
208 QueryResult::Started(job) => {
212 // If we are single-threaded we know that we have cycle error,
213 // so we just return the error.
214 return TryGetJob::Cycle(id.find_cycle_in_stack(
215 qcx.try_collect_active_jobs().unwrap(),
216 &qcx.current_query_job(),
220 #[cfg(parallel_compiler)]
221 QueryResult::Started(job) => {
222 // For parallel queries, we'll block and wait until the query running
223 // in another thread has completed. Record how long we wait in the
225 let query_blocked_prof_timer = qcx.dep_context().profiler().query_blocked();
228 let latch = job.latch();
232 // With parallel queries we might just have to wait on some other
234 let result = latch.wait_on(qcx.current_query_job(), span);
237 Ok(()) => TryGetJob::JobCompleted(query_blocked_prof_timer),
238 Err(cycle) => TryGetJob::Cycle(cycle),
241 QueryResult::Poisoned => FatalError.raise(),
247 /// Completes the query by updating the query cache with the `result`,
248 /// signals the waiter and forgets the JobOwner, so it won't poison the query
249 fn complete<C>(self, cache: &C, result: C::Value, dep_node_index: DepNodeIndex) -> C::Stored
251 C: QueryCache<Key = K>,
253 // We can move out of `self` here because we `mem::forget` it below
254 let key = unsafe { ptr::read(&self.key) };
255 let state = self.state;
257 // Forget ourself so our destructor won't poison the query
260 let (job, result) = {
262 #[cfg(parallel_compiler)]
263 let mut lock = state.active.get_shard_by_value(&key).lock();
264 #[cfg(not(parallel_compiler))]
265 let mut lock = state.active.lock();
266 match lock.remove(&key).unwrap() {
267 QueryResult::Started(job) => job,
268 QueryResult::Poisoned => panic!(),
271 let result = cache.complete(key, result, dep_node_index);
275 job.signal_complete();
280 impl<'tcx, K, D> Drop for JobOwner<'tcx, K, D>
282 K: Eq + Hash + Clone,
288 // Poison the query so jobs waiting on it panic.
289 let state = self.state;
291 #[cfg(parallel_compiler)]
292 let mut shard = state.active.get_shard_by_value(&self.key).lock();
293 #[cfg(not(parallel_compiler))]
294 let mut shard = state.active.lock();
295 let job = match shard.remove(&self.key).unwrap() {
296 QueryResult::Started(job) => job,
297 QueryResult::Poisoned => panic!(),
299 shard.insert(self.key.clone(), QueryResult::Poisoned);
302 // Also signal the completion of the job, so waiters
303 // will continue execution.
304 job.signal_complete();
309 pub(crate) struct CycleError<D: DepKind> {
310 /// The query and related span that uses the cycle.
311 pub usage: Option<(Span, QueryStackFrame<D>)>,
312 pub cycle: Vec<QueryInfo<D>>,
315 /// The result of `try_start`.
316 enum TryGetJob<'tcx, K, D>
318 K: Eq + Hash + Clone,
321 /// The query is not yet started. Contains a guard to the cache eventually used to start it.
322 NotYetStarted(JobOwner<'tcx, K, D>),
324 /// The query was already completed.
325 /// Returns the result of the query and its dep-node index
326 /// if it succeeded or a cycle error if it failed.
327 #[cfg(parallel_compiler)]
328 JobCompleted(TimingGuard<'tcx>),
330 /// Trying to execute the query resulted in a cycle.
331 Cycle(CycleError<D>),
334 /// Checks if the query is already computed and in the cache.
335 /// It returns the shard index and a lock guard to the shard,
336 /// which will be used if the query is not in the cache and we need
339 pub fn try_get_cached<Tcx, C>(tcx: Tcx, cache: &C, key: &C::Key) -> Option<C::Stored>
344 match cache.lookup(&key) {
345 Some((value, index)) => {
346 if std::intrinsics::unlikely(tcx.profiler().enabled()) {
347 tcx.profiler().query_cache_hit(index.into());
349 tcx.dep_graph().read_index(index);
356 fn try_execute_query<Q, Qcx>(
358 state: &QueryState<Q::Key, Qcx::DepKind>,
362 dep_node: Option<DepNode<Qcx::DepKind>>,
363 ) -> (Q::Stored, Option<DepNodeIndex>)
368 match JobOwner::<'_, Q::Key, Qcx::DepKind>::try_start(&qcx, state, span, key.clone()) {
369 TryGetJob::NotYetStarted(job) => {
370 let (result, dep_node_index) =
371 execute_job::<Q, Qcx>(qcx, key.clone(), dep_node, job.id);
373 // We may have put a value inside the cache from inside the execution.
374 // Verify that it has the same hash as what we have now, to ensure consistency.
375 if let Some((cached_result, _)) = cache.lookup(&key) {
376 let hasher = Q::HASH_RESULT.expect("feedable forbids no_hash");
378 let old_hash = qcx.dep_context().with_stable_hashing_context(|mut hcx| {
379 hasher(&mut hcx, cached_result.borrow())
383 .with_stable_hashing_context(|mut hcx| hasher(&mut hcx, &result));
387 "Computed query value for {:?}({:?}) is inconsistent with fed value,\ncomputed={:#?}\nfed={:#?}",
395 let result = job.complete(cache, result, dep_node_index);
396 (result, Some(dep_node_index))
398 TryGetJob::Cycle(error) => {
399 let result = mk_cycle(qcx, error, Q::HANDLE_CYCLE_ERROR);
402 #[cfg(parallel_compiler)]
403 TryGetJob::JobCompleted(query_blocked_prof_timer) => {
404 let Some((v, index)) = cache.lookup(&key) else {
405 panic!("value must be in cache after waiting")
408 if std::intrinsics::unlikely(qcx.dep_context().profiler().enabled()) {
409 qcx.dep_context().profiler().query_cache_hit(index.into());
411 query_blocked_prof_timer.finish_with_query_invocation_id(index.into());
418 fn execute_job<Q, Qcx>(
421 mut dep_node_opt: Option<DepNode<Qcx::DepKind>>,
423 ) -> (Q::Value, DepNodeIndex)
428 let dep_graph = qcx.dep_context().dep_graph();
430 // Fast path for when incr. comp. is off.
431 if !dep_graph.is_fully_enabled() {
432 let prof_timer = qcx.dep_context().profiler().query_provider();
433 let result = qcx.start_query(job_id, Q::DEPTH_LIMIT, None, || {
434 Q::compute(qcx, &key)(*qcx.dep_context(), key)
436 let dep_node_index = dep_graph.next_virtual_depnode_index();
437 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
438 return (result, dep_node_index);
441 if !Q::ANON && !Q::EVAL_ALWAYS {
442 // `to_dep_node` is expensive for some `DepKind`s.
444 dep_node_opt.get_or_insert_with(|| Q::construct_dep_node(*qcx.dep_context(), &key));
446 // The diagnostics for this query will be promoted to the current session during
447 // `try_mark_green()`, so we can ignore them here.
448 if let Some(ret) = qcx.start_query(job_id, false, None, || {
449 try_load_from_disk_and_cache_in_memory::<Q, Qcx>(qcx, &key, &dep_node)
455 let prof_timer = qcx.dep_context().profiler().query_provider();
456 let diagnostics = Lock::new(ThinVec::new());
458 let (result, dep_node_index) =
459 qcx.start_query(job_id, Q::DEPTH_LIMIT, Some(&diagnostics), || {
461 return dep_graph.with_anon_task(*qcx.dep_context(), Q::DEP_KIND, || {
462 Q::compute(qcx, &key)(*qcx.dep_context(), key)
466 // `to_dep_node` is expensive for some `DepKind`s.
468 dep_node_opt.unwrap_or_else(|| Q::construct_dep_node(*qcx.dep_context(), &key));
470 let task = Q::compute(qcx, &key);
471 dep_graph.with_task(dep_node, *qcx.dep_context(), key, task, Q::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<Q, Qcx>(
493 dep_node: &DepNode<Qcx::DepKind>,
494 ) -> Option<(Q::Value, DepNodeIndex)>
499 // Note this function can be called concurrently from the same query
500 // We must ensure that this is handled correctly.
502 let dep_graph = qcx.dep_context().dep_graph();
503 let (prev_dep_node_index, dep_node_index) = dep_graph.try_mark_green(qcx, &dep_node)?;
505 debug_assert!(dep_graph.is_green(dep_node));
507 // First we try to load the result from the on-disk cache.
508 // Some things are never cached on disk.
509 if let Some(try_load_from_disk) = Q::try_load_from_disk(qcx, &key) {
510 let prof_timer = qcx.dep_context().profiler().incr_cache_loading();
512 // The call to `with_query_deserialization` enforces that no new `DepNodes`
513 // are created during deserialization. See the docs of that method for more
516 dep_graph.with_query_deserialization(|| try_load_from_disk(qcx, prev_dep_node_index));
518 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
520 if let Some(result) = result {
521 if std::intrinsics::unlikely(
522 qcx.dep_context().sess().opts.unstable_opts.query_dep_graph,
524 dep_graph.mark_debug_loaded_from_disk(*dep_node)
527 let prev_fingerprint = qcx
530 .prev_fingerprint_of(dep_node)
531 .unwrap_or(Fingerprint::ZERO);
532 // If `-Zincremental-verify-ich` is specified, re-hash results from
533 // the cache and make sure that they have the expected fingerprint.
535 // If not, we still seek to verify a subset of fingerprints loaded
536 // from disk. Re-hashing results is fairly expensive, so we can't
537 // currently afford to verify every hash. This subset should still
538 // give us some coverage of potential bugs though.
539 let try_verify = prev_fingerprint.as_value().1 % 32 == 0;
540 if std::intrinsics::unlikely(
541 try_verify || qcx.dep_context().sess().opts.unstable_opts.incremental_verify_ich,
543 incremental_verify_ich(*qcx.dep_context(), &result, dep_node, Q::HASH_RESULT);
546 return Some((result, dep_node_index));
549 // We always expect to find a cached result for things that
550 // can be forced from `DepNode`.
552 !qcx.dep_context().fingerprint_style(dep_node.kind).reconstructible(),
553 "missing on-disk cache entry for {dep_node:?}"
557 // We could not load a result from the on-disk cache, so
559 let prof_timer = qcx.dep_context().profiler().query_provider();
561 // The dep-graph for this computation is already in-place.
562 let result = dep_graph.with_ignore(|| Q::compute(qcx, key)(*qcx.dep_context(), key.clone()));
564 prof_timer.finish_with_query_invocation_id(dep_node_index.into());
566 // Verify that re-running the query produced a result with the expected hash
567 // This catches bugs in query implementations, turning them into ICEs.
568 // For example, a query might sort its result by `DefId` - since `DefId`s are
569 // not stable across compilation sessions, the result could get up getting sorted
570 // in a different order when the query is re-run, even though all of the inputs
571 // (e.g. `DefPathHash` values) were green.
573 // See issue #82920 for an example of a miscompilation that would get turned into
574 // an ICE by this check
575 incremental_verify_ich(*qcx.dep_context(), &result, dep_node, Q::HASH_RESULT);
577 Some((result, dep_node_index))
580 #[instrument(skip(tcx, result, hash_result), level = "debug")]
581 pub(crate) fn incremental_verify_ich<Tcx, V: Debug>(
584 dep_node: &DepNode<Tcx::DepKind>,
585 hash_result: Option<fn(&mut StableHashingContext<'_>, &V) -> Fingerprint>,
591 tcx.dep_graph().is_green(dep_node),
592 "fingerprint for green query instance not loaded from cache: {dep_node:?}",
595 let new_hash = hash_result.map_or(Fingerprint::ZERO, |f| {
596 tcx.with_stable_hashing_context(|mut hcx| f(&mut hcx, result))
599 let old_hash = tcx.dep_graph().prev_fingerprint_of(dep_node);
601 if Some(new_hash) != old_hash {
602 incremental_verify_ich_failed(
604 DebugArg::from(&dep_node),
605 DebugArg::from(&result),
612 // This DebugArg business is largely a mirror of std::fmt::ArgumentV1, which is
613 // currently not exposed publicly.
615 // The PR which added this attempted to use `&dyn Debug` instead, but that
616 // showed statistically significant worse compiler performance. It's not
617 // actually clear what the cause there was -- the code should be cold. If this
618 // can be replaced with `&dyn Debug` with on perf impact, then it probably
624 struct DebugArg<'a> {
626 fmt: fn(&Opaque, &mut std::fmt::Formatter<'_>) -> std::fmt::Result,
629 impl<'a, T> From<&'a T> for DebugArg<'a>
633 fn from(value: &'a T) -> DebugArg<'a> {
635 value: unsafe { std::mem::transmute(value) },
637 std::mem::transmute(<T as std::fmt::Debug>::fmt as fn(_, _) -> std::fmt::Result)
643 impl std::fmt::Debug for DebugArg<'_> {
644 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
645 (self.fmt)(self.value, f)
649 // Note that this is marked #[cold] and intentionally takes the equivalent of
650 // `dyn Debug` for its arguments, as we want to avoid generating a bunch of
651 // different implementations for LLVM to chew on (and filling up the final
654 fn incremental_verify_ich_failed(sess: &Session, dep_node: DebugArg<'_>, result: DebugArg<'_>) {
655 // When we emit an error message and panic, we try to debug-print the `DepNode`
656 // and query result. Unfortunately, this can cause us to run additional queries,
657 // which may result in another fingerprint mismatch while we're in the middle
658 // of processing this one. To avoid a double-panic (which kills the process
659 // before we can print out the query static), we print out a terse
660 // but 'safe' message if we detect a re-entrant call to this method.
662 static INSIDE_VERIFY_PANIC: Cell<bool> = const { Cell::new(false) };
665 let old_in_panic = INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.replace(true));
668 sess.emit_err(crate::error::Reentrant);
670 let run_cmd = if let Some(crate_name) = &sess.opts.crate_name {
671 format!("`cargo clean -p {crate_name}` or `cargo clean`")
673 "`cargo clean`".to_string()
676 sess.emit_err(crate::error::IncrementCompilation {
678 dep_node: format!("{dep_node:?}"),
680 panic!("Found unstable fingerprints for {dep_node:?}: {result:?}");
683 INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.set(old_in_panic));
686 /// Ensure that either this query has all green inputs or been executed.
687 /// Executing `query::ensure(D)` is considered a read of the dep-node `D`.
688 /// Returns true if the query should still run.
690 /// This function is particularly useful when executing passes for their
691 /// side-effects -- e.g., in order to report errors for erroneous programs.
693 /// Note: The optimization is only available during incr. comp.
695 fn ensure_must_run<Q, Qcx>(qcx: Qcx, key: &Q::Key) -> (bool, Option<DepNode<Qcx::DepKind>>)
704 // Ensuring an anonymous query makes no sense
707 let dep_node = Q::construct_dep_node(*qcx.dep_context(), key);
709 let dep_graph = qcx.dep_context().dep_graph();
710 match dep_graph.try_mark_green(qcx, &dep_node) {
712 // A None return from `try_mark_green` means that this is either
713 // a new dep node or that the dep node has already been marked red.
714 // Either way, we can't call `dep_graph.read()` as we don't have the
715 // DepNodeIndex. We must invoke the query itself. The performance cost
716 // this introduces should be negligible as we'll immediately hit the
717 // in-memory cache, or another query down the line will.
718 (true, Some(dep_node))
720 Some((_, dep_node_index)) => {
721 dep_graph.read_index(dep_node_index);
722 qcx.dep_context().profiler().query_cache_hit(dep_node_index.into());
734 pub fn get_query<Q, Qcx, D>(qcx: Qcx, span: Span, key: Q::Key, mode: QueryMode) -> Option<Q::Stored>
738 Q::Value: Value<Qcx::DepContext, D>,
741 let dep_node = if let QueryMode::Ensure = mode {
742 let (must_run, dep_node) = ensure_must_run::<Q, _>(qcx, &key);
751 let (result, dep_node_index) = try_execute_query::<Q, Qcx>(
759 if let Some(dep_node_index) = dep_node_index {
760 qcx.dep_context().dep_graph().read_index(dep_node_index)
765 pub fn force_query<Q, Qcx, D>(qcx: Qcx, key: Q::Key, dep_node: DepNode<Qcx::DepKind>)
769 Q::Value: Value<Qcx::DepContext, D>,
772 // We may be concurrently trying both execute and force a query.
773 // Ensure that only one of them runs the query.
774 let cache = Q::query_cache(qcx);
775 if let Some((_, index)) = cache.lookup(&key) {
776 if std::intrinsics::unlikely(qcx.dep_context().profiler().enabled()) {
777 qcx.dep_context().profiler().query_cache_hit(index.into());
782 let state = Q::query_state(qcx);
783 debug_assert!(!Q::ANON);
785 try_execute_query::<Q, _>(qcx, state, cache, DUMMY_SP, key, Some(dep_node));