1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
//! The implementation of the query system itself. This defines the macros that
//! generate the actual methods on tcx which find and execute the provider,
//! manage the caches, and so forth.

use crate::dep_graph::{DepContext, DepNode, DepNodeIndex, DepNodeParams};
use crate::query::caches::QueryCache;
use crate::query::config::{QueryDescription, QueryVTable};
use crate::query::job::{report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo};
use crate::query::{QueryContext, QueryMap, QuerySideEffects, QueryStackFrame};
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::FxHashMap;
#[cfg(parallel_compiler)]
use rustc_data_structures::profiling::TimingGuard;
#[cfg(parallel_compiler)]
use rustc_data_structures::sharded::Sharded;
use rustc_data_structures::sync::Lock;
use rustc_data_structures::thin_vec::ThinVec;
use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed, FatalError};
use rustc_session::Session;
use rustc_span::{Span, DUMMY_SP};
use std::cell::Cell;
use std::collections::hash_map::Entry;
use std::fmt::Debug;
use std::hash::Hash;
use std::mem;
use std::ptr;

pub struct QueryState<K> {
    #[cfg(parallel_compiler)]
    active: Sharded<FxHashMap<K, QueryResult>>,
    #[cfg(not(parallel_compiler))]
    active: Lock<FxHashMap<K, QueryResult>>,
}

/// Indicates the state of a query for a given key in a query map.
enum QueryResult {
    /// An already executing query. The query job can be used to await for its completion.
    Started(QueryJob),

    /// The query panicked. Queries trying to wait on this will raise a fatal error which will
    /// silently panic.
    Poisoned,
}

impl<K> QueryState<K>
where
    K: Eq + Hash + Clone + Debug,
{
    pub fn all_inactive(&self) -> bool {
        #[cfg(parallel_compiler)]
        {
            let shards = self.active.lock_shards();
            shards.iter().all(|shard| shard.is_empty())
        }
        #[cfg(not(parallel_compiler))]
        {
            self.active.lock().is_empty()
        }
    }

    pub fn try_collect_active_jobs<CTX: Copy>(
        &self,
        tcx: CTX,
        make_query: fn(CTX, K) -> QueryStackFrame,
        jobs: &mut QueryMap,
    ) -> Option<()> {
        #[cfg(parallel_compiler)]
        {
            // We use try_lock_shards here since we are called from the
            // deadlock handler, and this shouldn't be locked.
            let shards = self.active.try_lock_shards()?;
            for shard in shards.iter() {
                for (k, v) in shard.iter() {
                    if let QueryResult::Started(ref job) = *v {
                        let query = make_query(tcx, k.clone());
                        jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
                    }
                }
            }
        }
        #[cfg(not(parallel_compiler))]
        {
            // We use try_lock here since we are called from the
            // deadlock handler, and this shouldn't be locked.
            // (FIXME: Is this relevant for non-parallel compilers? It doesn't
            // really hurt much.)
            for (k, v) in self.active.try_lock()?.iter() {
                if let QueryResult::Started(ref job) = *v {
                    let query = make_query(tcx, k.clone());
                    jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
                }
            }
        }

        Some(())
    }
}

impl<K> Default for QueryState<K> {
    fn default() -> QueryState<K> {
        QueryState { active: Default::default() }
    }
}

/// A type representing the responsibility to execute the job in the `job` field.
/// This will poison the relevant query if dropped.
struct JobOwner<'tcx, K>
where
    K: Eq + Hash + Clone,
{
    state: &'tcx QueryState<K>,
    key: K,
    id: QueryJobId,
}

#[cold]
#[inline(never)]
fn mk_cycle<CTX, V, R>(
    tcx: CTX,
    error: CycleError,
    handle_cycle_error: fn(CTX, DiagnosticBuilder<'_, ErrorGuaranteed>) -> V,
    cache: &dyn crate::query::QueryStorage<Value = V, Stored = R>,
) -> R
where
    CTX: QueryContext,
    V: std::fmt::Debug,
    R: Clone,
{
    let error = report_cycle(tcx.dep_context().sess(), error);
    let value = handle_cycle_error(tcx, error);
    cache.store_nocache(value)
}

impl<'tcx, K> JobOwner<'tcx, K>
where
    K: Eq + Hash + Clone,
{
    /// Either gets a `JobOwner` corresponding the query, allowing us to
    /// start executing the query, or returns with the result of the query.
    /// This function assumes that `try_get_cached` is already called and returned `lookup`.
    /// If the query is executing elsewhere, this will wait for it and return the result.
    /// If the query panicked, this will silently panic.
    ///
    /// This function is inlined because that results in a noticeable speed-up
    /// for some compile-time benchmarks.
    #[inline(always)]
    fn try_start<'b, CTX>(
        tcx: &'b CTX,
        state: &'b QueryState<K>,
        span: Span,
        key: K,
    ) -> TryGetJob<'b, K>
    where
        CTX: QueryContext,
    {
        #[cfg(parallel_compiler)]
        let mut state_lock = state.active.get_shard_by_value(&key).lock();
        #[cfg(not(parallel_compiler))]
        let mut state_lock = state.active.lock();
        let lock = &mut *state_lock;

        match lock.entry(key) {
            Entry::Vacant(entry) => {
                let id = tcx.next_job_id();
                let job = tcx.current_query_job();
                let job = QueryJob::new(id, span, job);

                let key = entry.key().clone();
                entry.insert(QueryResult::Started(job));

                let owner = JobOwner { state, id, key };
                return TryGetJob::NotYetStarted(owner);
            }
            Entry::Occupied(mut entry) => {
                match entry.get_mut() {
                    #[cfg(not(parallel_compiler))]
                    QueryResult::Started(job) => {
                        let id = job.id;
                        drop(state_lock);

                        // If we are single-threaded we know that we have cycle error,
                        // so we just return the error.
                        return TryGetJob::Cycle(id.find_cycle_in_stack(
                            tcx.try_collect_active_jobs().unwrap(),
                            &tcx.current_query_job(),
                            span,
                        ));
                    }
                    #[cfg(parallel_compiler)]
                    QueryResult::Started(job) => {
                        // For parallel queries, we'll block and wait until the query running
                        // in another thread has completed. Record how long we wait in the
                        // self-profiler.
                        let query_blocked_prof_timer = tcx.dep_context().profiler().query_blocked();

                        // Get the latch out
                        let latch = job.latch();

                        drop(state_lock);

                        // With parallel queries we might just have to wait on some other
                        // thread.
                        let result = latch.wait_on(tcx.current_query_job(), span);

                        match result {
                            Ok(()) => TryGetJob::JobCompleted(query_blocked_prof_timer),
                            Err(cycle) => TryGetJob::Cycle(cycle),
                        }
                    }
                    QueryResult::Poisoned => FatalError.raise(),
                }
            }
        }
    }

    /// Completes the query by updating the query cache with the `result`,
    /// signals the waiter and forgets the JobOwner, so it won't poison the query
    fn complete<C>(self, cache: &C, result: C::Value, dep_node_index: DepNodeIndex) -> C::Stored
    where
        C: QueryCache<Key = K>,
    {
        // We can move out of `self` here because we `mem::forget` it below
        let key = unsafe { ptr::read(&self.key) };
        let state = self.state;

        // Forget ourself so our destructor won't poison the query
        mem::forget(self);

        let (job, result) = {
            let job = {
                #[cfg(parallel_compiler)]
                let mut lock = state.active.get_shard_by_value(&key).lock();
                #[cfg(not(parallel_compiler))]
                let mut lock = state.active.lock();
                match lock.remove(&key).unwrap() {
                    QueryResult::Started(job) => job,
                    QueryResult::Poisoned => panic!(),
                }
            };
            let result = cache.complete(key, result, dep_node_index);
            (job, result)
        };

        job.signal_complete();
        result
    }
}

impl<'tcx, K> Drop for JobOwner<'tcx, K>
where
    K: Eq + Hash + Clone,
{
    #[inline(never)]
    #[cold]
    fn drop(&mut self) {
        // Poison the query so jobs waiting on it panic.
        let state = self.state;
        let job = {
            #[cfg(parallel_compiler)]
            let mut shard = state.active.get_shard_by_value(&self.key).lock();
            #[cfg(not(parallel_compiler))]
            let mut shard = state.active.lock();
            let job = match shard.remove(&self.key).unwrap() {
                QueryResult::Started(job) => job,
                QueryResult::Poisoned => panic!(),
            };
            shard.insert(self.key.clone(), QueryResult::Poisoned);
            job
        };
        // Also signal the completion of the job, so waiters
        // will continue execution.
        job.signal_complete();
    }
}

#[derive(Clone)]
pub(crate) struct CycleError {
    /// The query and related span that uses the cycle.
    pub usage: Option<(Span, QueryStackFrame)>,
    pub cycle: Vec<QueryInfo>,
}

/// The result of `try_start`.
enum TryGetJob<'tcx, K>
where
    K: Eq + Hash + Clone,
{
    /// The query is not yet started. Contains a guard to the cache eventually used to start it.
    NotYetStarted(JobOwner<'tcx, K>),

    /// The query was already completed.
    /// Returns the result of the query and its dep-node index
    /// if it succeeded or a cycle error if it failed.
    #[cfg(parallel_compiler)]
    JobCompleted(TimingGuard<'tcx>),

    /// Trying to execute the query resulted in a cycle.
    Cycle(CycleError),
}

/// Checks if the query is already computed and in the cache.
/// It returns the shard index and a lock guard to the shard,
/// which will be used if the query is not in the cache and we need
/// to compute it.
#[inline]
pub fn try_get_cached<'a, CTX, C, R, OnHit>(
    tcx: CTX,
    cache: &'a C,
    key: &C::Key,
    // `on_hit` can be called while holding a lock to the query cache
    on_hit: OnHit,
) -> Result<R, ()>
where
    C: QueryCache,
    CTX: DepContext,
    OnHit: FnOnce(&C::Stored) -> R,
{
    cache.lookup(&key, |value, index| {
        if std::intrinsics::unlikely(tcx.profiler().enabled()) {
            tcx.profiler().query_cache_hit(index.into());
        }
        tcx.dep_graph().read_index(index);
        on_hit(value)
    })
}

fn try_execute_query<CTX, C>(
    tcx: CTX,
    state: &QueryState<C::Key>,
    cache: &C,
    span: Span,
    key: C::Key,
    dep_node: Option<DepNode<CTX::DepKind>>,
    query: &QueryVTable<CTX, C::Key, C::Value>,
) -> (C::Stored, Option<DepNodeIndex>)
where
    C: QueryCache,
    C::Key: Clone + DepNodeParams<CTX::DepContext>,
    CTX: QueryContext,
{
    match JobOwner::<'_, C::Key>::try_start(&tcx, state, span, key.clone()) {
        TryGetJob::NotYetStarted(job) => {
            let (result, dep_node_index) = execute_job(tcx, key, dep_node, query, job.id);
            let result = job.complete(cache, result, dep_node_index);
            (result, Some(dep_node_index))
        }
        TryGetJob::Cycle(error) => {
            let result = mk_cycle(tcx, error, query.handle_cycle_error, cache);
            (result, None)
        }
        #[cfg(parallel_compiler)]
        TryGetJob::JobCompleted(query_blocked_prof_timer) => {
            let (v, index) = cache
                .lookup(&key, |value, index| (value.clone(), index))
                .unwrap_or_else(|_| panic!("value must be in cache after waiting"));

            if std::intrinsics::unlikely(tcx.dep_context().profiler().enabled()) {
                tcx.dep_context().profiler().query_cache_hit(index.into());
            }
            query_blocked_prof_timer.finish_with_query_invocation_id(index.into());

            (v, Some(index))
        }
    }
}

fn execute_job<CTX, K, V>(
    tcx: CTX,
    key: K,
    mut dep_node_opt: Option<DepNode<CTX::DepKind>>,
    query: &QueryVTable<CTX, K, V>,
    job_id: QueryJobId,
) -> (V, DepNodeIndex)
where
    K: Clone + DepNodeParams<CTX::DepContext>,
    V: Debug,
    CTX: QueryContext,
{
    let dep_graph = tcx.dep_context().dep_graph();

    // Fast path for when incr. comp. is off.
    if !dep_graph.is_fully_enabled() {
        let prof_timer = tcx.dep_context().profiler().query_provider();
        let result = tcx.start_query(job_id, None, || query.compute(*tcx.dep_context(), key));
        let dep_node_index = dep_graph.next_virtual_depnode_index();
        prof_timer.finish_with_query_invocation_id(dep_node_index.into());
        return (result, dep_node_index);
    }

    if !query.anon && !query.eval_always {
        // `to_dep_node` is expensive for some `DepKind`s.
        let dep_node =
            dep_node_opt.get_or_insert_with(|| query.to_dep_node(*tcx.dep_context(), &key));

        // The diagnostics for this query will be promoted to the current session during
        // `try_mark_green()`, so we can ignore them here.
        if let Some(ret) = tcx.start_query(job_id, None, || {
            try_load_from_disk_and_cache_in_memory(tcx, &key, &dep_node, query)
        }) {
            return ret;
        }
    }

    let prof_timer = tcx.dep_context().profiler().query_provider();
    let diagnostics = Lock::new(ThinVec::new());

    let (result, dep_node_index) = tcx.start_query(job_id, Some(&diagnostics), || {
        if query.anon {
            return dep_graph.with_anon_task(*tcx.dep_context(), query.dep_kind, || {
                query.compute(*tcx.dep_context(), key)
            });
        }

        // `to_dep_node` is expensive for some `DepKind`s.
        let dep_node = dep_node_opt.unwrap_or_else(|| query.to_dep_node(*tcx.dep_context(), &key));

        dep_graph.with_task(dep_node, *tcx.dep_context(), key, query.compute, query.hash_result)
    });

    prof_timer.finish_with_query_invocation_id(dep_node_index.into());

    let diagnostics = diagnostics.into_inner();
    let side_effects = QuerySideEffects { diagnostics };

    if std::intrinsics::unlikely(!side_effects.is_empty()) {
        if query.anon {
            tcx.store_side_effects_for_anon_node(dep_node_index, side_effects);
        } else {
            tcx.store_side_effects(dep_node_index, side_effects);
        }
    }

    (result, dep_node_index)
}

fn try_load_from_disk_and_cache_in_memory<CTX, K, V>(
    tcx: CTX,
    key: &K,
    dep_node: &DepNode<CTX::DepKind>,
    query: &QueryVTable<CTX, K, V>,
) -> Option<(V, DepNodeIndex)>
where
    K: Clone,
    CTX: QueryContext,
    V: Debug,
{
    // Note this function can be called concurrently from the same query
    // We must ensure that this is handled correctly.

    let dep_graph = tcx.dep_context().dep_graph();
    let (prev_dep_node_index, dep_node_index) = dep_graph.try_mark_green(tcx, &dep_node)?;

    debug_assert!(dep_graph.is_green(dep_node));

    // First we try to load the result from the on-disk cache.
    // Some things are never cached on disk.
    if query.cache_on_disk {
        let prof_timer = tcx.dep_context().profiler().incr_cache_loading();

        // The call to `with_query_deserialization` enforces that no new `DepNodes`
        // are created during deserialization. See the docs of that method for more
        // details.
        let result = dep_graph
            .with_query_deserialization(|| query.try_load_from_disk(tcx, prev_dep_node_index));

        prof_timer.finish_with_query_invocation_id(dep_node_index.into());

        if let Some(result) = result {
            if std::intrinsics::unlikely(
                tcx.dep_context().sess().opts.unstable_opts.query_dep_graph,
            ) {
                dep_graph.mark_debug_loaded_from_disk(*dep_node)
            }

            let prev_fingerprint = tcx
                .dep_context()
                .dep_graph()
                .prev_fingerprint_of(dep_node)
                .unwrap_or(Fingerprint::ZERO);
            // If `-Zincremental-verify-ich` is specified, re-hash results from
            // the cache and make sure that they have the expected fingerprint.
            //
            // If not, we still seek to verify a subset of fingerprints loaded
            // from disk. Re-hashing results is fairly expensive, so we can't
            // currently afford to verify every hash. This subset should still
            // give us some coverage of potential bugs though.
            let try_verify = prev_fingerprint.as_value().1 % 32 == 0;
            if std::intrinsics::unlikely(
                try_verify || tcx.dep_context().sess().opts.unstable_opts.incremental_verify_ich,
            ) {
                incremental_verify_ich(*tcx.dep_context(), &result, dep_node, query);
            }

            return Some((result, dep_node_index));
        }

        // We always expect to find a cached result for things that
        // can be forced from `DepNode`.
        debug_assert!(
            !tcx.dep_context().fingerprint_style(dep_node.kind).reconstructible(),
            "missing on-disk cache entry for {:?}",
            dep_node
        );
    }

    // We could not load a result from the on-disk cache, so
    // recompute.
    let prof_timer = tcx.dep_context().profiler().query_provider();

    // The dep-graph for this computation is already in-place.
    let result = dep_graph.with_ignore(|| query.compute(*tcx.dep_context(), key.clone()));

    prof_timer.finish_with_query_invocation_id(dep_node_index.into());

    // Verify that re-running the query produced a result with the expected hash
    // This catches bugs in query implementations, turning them into ICEs.
    // For example, a query might sort its result by `DefId` - since `DefId`s are
    // not stable across compilation sessions, the result could get up getting sorted
    // in a different order when the query is re-run, even though all of the inputs
    // (e.g. `DefPathHash` values) were green.
    //
    // See issue #82920 for an example of a miscompilation that would get turned into
    // an ICE by this check
    incremental_verify_ich(*tcx.dep_context(), &result, dep_node, query);

    Some((result, dep_node_index))
}

fn incremental_verify_ich<CTX, K, V: Debug>(
    tcx: CTX::DepContext,
    result: &V,
    dep_node: &DepNode<CTX::DepKind>,
    query: &QueryVTable<CTX, K, V>,
) where
    CTX: QueryContext,
{
    assert!(
        tcx.dep_graph().is_green(dep_node),
        "fingerprint for green query instance not loaded from cache: {:?}",
        dep_node,
    );

    debug!("BEGIN verify_ich({:?})", dep_node);
    let new_hash = query.hash_result.map_or(Fingerprint::ZERO, |f| {
        tcx.with_stable_hashing_context(|mut hcx| f(&mut hcx, result))
    });
    let old_hash = tcx.dep_graph().prev_fingerprint_of(dep_node);
    debug!("END verify_ich({:?})", dep_node);

    if Some(new_hash) != old_hash {
        incremental_verify_ich_cold(tcx.sess(), DebugArg::from(&dep_node), DebugArg::from(&result));
    }
}

// This DebugArg business is largely a mirror of std::fmt::ArgumentV1, which is
// currently not exposed publicly.
//
// The PR which added this attempted to use `&dyn Debug` instead, but that
// showed statistically significant worse compiler performance. It's not
// actually clear what the cause there was -- the code should be cold. If this
// can be replaced with `&dyn Debug` with on perf impact, then it probably
// should be.
extern "C" {
    type Opaque;
}

struct DebugArg<'a> {
    value: &'a Opaque,
    fmt: fn(&Opaque, &mut std::fmt::Formatter<'_>) -> std::fmt::Result,
}

impl<'a, T> From<&'a T> for DebugArg<'a>
where
    T: std::fmt::Debug,
{
    fn from(value: &'a T) -> DebugArg<'a> {
        DebugArg {
            value: unsafe { std::mem::transmute(value) },
            fmt: unsafe {
                std::mem::transmute(<T as std::fmt::Debug>::fmt as fn(_, _) -> std::fmt::Result)
            },
        }
    }
}

impl std::fmt::Debug for DebugArg<'_> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        (self.fmt)(self.value, f)
    }
}

// Note that this is marked #[cold] and intentionally takes the equivalent of
// `dyn Debug` for its arguments, as we want to avoid generating a bunch of
// different implementations for LLVM to chew on (and filling up the final
// binary, too).
#[cold]
fn incremental_verify_ich_cold(sess: &Session, dep_node: DebugArg<'_>, result: DebugArg<'_>) {
    let run_cmd = if let Some(crate_name) = &sess.opts.crate_name {
        format!("`cargo clean -p {}` or `cargo clean`", crate_name)
    } else {
        "`cargo clean`".to_string()
    };

    // When we emit an error message and panic, we try to debug-print the `DepNode`
    // and query result. Unfortunately, this can cause us to run additional queries,
    // which may result in another fingerprint mismatch while we're in the middle
    // of processing this one. To avoid a double-panic (which kills the process
    // before we can print out the query static), we print out a terse
    // but 'safe' message if we detect a re-entrant call to this method.
    thread_local! {
        static INSIDE_VERIFY_PANIC: Cell<bool> = const { Cell::new(false) };
    };

    let old_in_panic = INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.replace(true));

    if old_in_panic {
        sess.struct_err(
            "internal compiler error: re-entrant incremental verify failure, suppressing message",
        )
        .emit();
    } else {
        sess.struct_err(&format!("internal compiler error: encountered incremental compilation error with {:?}", dep_node))
                .help(&format!("This is a known issue with the compiler. Run {} to allow your project to compile", run_cmd))
                .note("Please follow the instructions below to create a bug report with the provided information")
                .note("See <https://github.com/rust-lang/rust/issues/84970> for more information")
                .emit();
        panic!("Found unstable fingerprints for {:?}: {:?}", dep_node, result);
    }

    INSIDE_VERIFY_PANIC.with(|in_panic| in_panic.set(old_in_panic));
}

/// Ensure that either this query has all green inputs or been executed.
/// Executing `query::ensure(D)` is considered a read of the dep-node `D`.
/// Returns true if the query should still run.
///
/// This function is particularly useful when executing passes for their
/// side-effects -- e.g., in order to report errors for erroneous programs.
///
/// Note: The optimization is only available during incr. comp.
#[inline(never)]
fn ensure_must_run<CTX, K, V>(
    tcx: CTX,
    key: &K,
    query: &QueryVTable<CTX, K, V>,
) -> (bool, Option<DepNode<CTX::DepKind>>)
where
    K: crate::dep_graph::DepNodeParams<CTX::DepContext>,
    CTX: QueryContext,
{
    if query.eval_always {
        return (true, None);
    }

    // Ensuring an anonymous query makes no sense
    assert!(!query.anon);

    let dep_node = query.to_dep_node(*tcx.dep_context(), key);

    let dep_graph = tcx.dep_context().dep_graph();
    match dep_graph.try_mark_green(tcx, &dep_node) {
        None => {
            // A None return from `try_mark_green` means that this is either
            // a new dep node or that the dep node has already been marked red.
            // Either way, we can't call `dep_graph.read()` as we don't have the
            // DepNodeIndex. We must invoke the query itself. The performance cost
            // this introduces should be negligible as we'll immediately hit the
            // in-memory cache, or another query down the line will.
            (true, Some(dep_node))
        }
        Some((_, dep_node_index)) => {
            dep_graph.read_index(dep_node_index);
            tcx.dep_context().profiler().query_cache_hit(dep_node_index.into());
            (false, None)
        }
    }
}

#[derive(Debug)]
pub enum QueryMode {
    Get,
    Ensure,
}

pub fn get_query<Q, CTX>(tcx: CTX, span: Span, key: Q::Key, mode: QueryMode) -> Option<Q::Stored>
where
    Q: QueryDescription<CTX>,
    Q::Key: DepNodeParams<CTX::DepContext>,
    CTX: QueryContext,
{
    let query = Q::make_vtable(tcx, &key);
    let dep_node = if let QueryMode::Ensure = mode {
        let (must_run, dep_node) = ensure_must_run(tcx, &key, &query);
        if !must_run {
            return None;
        }
        dep_node
    } else {
        None
    };

    let (result, dep_node_index) = try_execute_query(
        tcx,
        Q::query_state(tcx),
        Q::query_cache(tcx),
        span,
        key,
        dep_node,
        &query,
    );
    if let Some(dep_node_index) = dep_node_index {
        tcx.dep_context().dep_graph().read_index(dep_node_index)
    }
    Some(result)
}

pub fn force_query<Q, CTX>(tcx: CTX, key: Q::Key, dep_node: DepNode<CTX::DepKind>)
where
    Q: QueryDescription<CTX>,
    Q::Key: DepNodeParams<CTX::DepContext>,
    CTX: QueryContext,
{
    // We may be concurrently trying both execute and force a query.
    // Ensure that only one of them runs the query.
    let cache = Q::query_cache(tcx);
    let cached = cache.lookup(&key, |_, index| {
        if std::intrinsics::unlikely(tcx.dep_context().profiler().enabled()) {
            tcx.dep_context().profiler().query_cache_hit(index.into());
        }
    });

    match cached {
        Ok(()) => return,
        Err(()) => {}
    }

    let query = Q::make_vtable(tcx, &key);
    let state = Q::query_state(tcx);
    debug_assert!(!query.anon);

    try_execute_query(tcx, state, cache, DUMMY_SP, key, Some(dep_node), &query);
}