rustc_query_system/dep_graph/
graph.rs

1use std::assert_matches::assert_matches;
2use std::fmt::Debug;
3use std::hash::Hash;
4use std::marker::PhantomData;
5use std::sync::Arc;
6use std::sync::atomic::{AtomicU32, Ordering};
7
8use rustc_data_structures::fingerprint::{Fingerprint, PackedFingerprint};
9use rustc_data_structures::fx::{FxHashMap, FxHashSet};
10use rustc_data_structures::outline;
11use rustc_data_structures::profiling::QueryInvocationId;
12use rustc_data_structures::sharded::{self, ShardedHashMap};
13use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
14use rustc_data_structures::sync::{AtomicU64, Lock};
15use rustc_data_structures::unord::UnordMap;
16use rustc_errors::DiagInner;
17use rustc_index::IndexVec;
18use rustc_macros::{Decodable, Encodable};
19use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
20use rustc_session::Session;
21use tracing::{debug, instrument};
22#[cfg(debug_assertions)]
23use {super::debug::EdgeFilter, std::env};
24
25use super::query::DepGraphQuery;
26use super::serialized::{GraphEncoder, SerializedDepGraph, SerializedDepNodeIndex};
27use super::{DepContext, DepKind, DepNode, Deps, HasDepContext, WorkProductId};
28use crate::dep_graph::edges::EdgesVec;
29use crate::ich::StableHashingContext;
30use crate::query::{QueryContext, QuerySideEffect};
31
32#[derive(Clone)]
33pub struct DepGraph<D: Deps> {
34    data: Option<Arc<DepGraphData<D>>>,
35
36    /// This field is used for assigning DepNodeIndices when running in
37    /// non-incremental mode. Even in non-incremental mode we make sure that
38    /// each task has a `DepNodeIndex` that uniquely identifies it. This unique
39    /// ID is used for self-profiling.
40    virtual_dep_node_index: Arc<AtomicU32>,
41}
42
43rustc_index::newtype_index! {
44    pub struct DepNodeIndex {}
45}
46
47// We store a large collection of these in `prev_index_to_index` during
48// non-full incremental builds, and want to ensure that the element size
49// doesn't inadvertently increase.
50rustc_data_structures::static_assert_size!(Option<DepNodeIndex>, 4);
51
52impl DepNodeIndex {
53    const SINGLETON_ZERO_DEPS_ANON_NODE: DepNodeIndex = DepNodeIndex::ZERO;
54    pub const FOREVER_RED_NODE: DepNodeIndex = DepNodeIndex::from_u32(1);
55}
56
57impl From<DepNodeIndex> for QueryInvocationId {
58    #[inline(always)]
59    fn from(dep_node_index: DepNodeIndex) -> Self {
60        QueryInvocationId(dep_node_index.as_u32())
61    }
62}
63
64pub struct MarkFrame<'a> {
65    index: SerializedDepNodeIndex,
66    parent: Option<&'a MarkFrame<'a>>,
67}
68
69#[derive(Debug)]
70pub(super) enum DepNodeColor {
71    Red,
72    Green(DepNodeIndex),
73}
74
75impl DepNodeColor {
76    #[inline]
77    fn is_green(self) -> bool {
78        match self {
79            DepNodeColor::Red => false,
80            DepNodeColor::Green(_) => true,
81        }
82    }
83}
84
85pub(crate) struct DepGraphData<D: Deps> {
86    /// The new encoding of the dependency graph, optimized for red/green
87    /// tracking. The `current` field is the dependency graph of only the
88    /// current compilation session: We don't merge the previous dep-graph into
89    /// current one anymore, but we do reference shared data to save space.
90    current: CurrentDepGraph<D>,
91
92    /// The dep-graph from the previous compilation session. It contains all
93    /// nodes and edges as well as all fingerprints of nodes that have them.
94    previous: Arc<SerializedDepGraph>,
95
96    colors: DepNodeColorMap,
97
98    /// When we load, there may be `.o` files, cached MIR, or other such
99    /// things available to us. If we find that they are not dirty, we
100    /// load the path to the file storing those work-products here into
101    /// this map. We can later look for and extract that data.
102    previous_work_products: WorkProductMap,
103
104    dep_node_debug: Lock<FxHashMap<DepNode, String>>,
105
106    /// Used by incremental compilation tests to assert that
107    /// a particular query result was decoded from disk
108    /// (not just marked green)
109    debug_loaded_from_disk: Lock<FxHashSet<DepNode>>,
110}
111
112pub fn hash_result<R>(hcx: &mut StableHashingContext<'_>, result: &R) -> Fingerprint
113where
114    R: for<'a> HashStable<StableHashingContext<'a>>,
115{
116    let mut stable_hasher = StableHasher::new();
117    result.hash_stable(hcx, &mut stable_hasher);
118    stable_hasher.finish()
119}
120
121impl<D: Deps> DepGraph<D> {
122    pub fn new(
123        session: &Session,
124        prev_graph: Arc<SerializedDepGraph>,
125        prev_work_products: WorkProductMap,
126        encoder: FileEncoder,
127        record_graph: bool,
128        record_stats: bool,
129    ) -> DepGraph<D> {
130        let prev_graph_node_count = prev_graph.node_count();
131
132        let current = CurrentDepGraph::new(
133            session,
134            prev_graph_node_count,
135            encoder,
136            record_graph,
137            record_stats,
138            Arc::clone(&prev_graph),
139        );
140
141        let colors = DepNodeColorMap::new(prev_graph_node_count);
142
143        // Instantiate a node with zero dependencies only once for anonymous queries.
144        let _green_node_index = current.alloc_new_node(
145            DepNode { kind: D::DEP_KIND_ANON_ZERO_DEPS, hash: current.anon_id_seed.into() },
146            EdgesVec::new(),
147            Fingerprint::ZERO,
148        );
149        assert_eq!(_green_node_index, DepNodeIndex::SINGLETON_ZERO_DEPS_ANON_NODE);
150
151        // Instantiate a dependy-less red node only once for anonymous queries.
152        let red_node_index = current.alloc_new_node(
153            DepNode { kind: D::DEP_KIND_RED, hash: Fingerprint::ZERO.into() },
154            EdgesVec::new(),
155            Fingerprint::ZERO,
156        );
157        assert_eq!(red_node_index, DepNodeIndex::FOREVER_RED_NODE);
158        if prev_graph_node_count > 0 {
159            colors.insert(
160                SerializedDepNodeIndex::from_u32(DepNodeIndex::FOREVER_RED_NODE.as_u32()),
161                DepNodeColor::Red,
162            );
163        }
164
165        DepGraph {
166            data: Some(Arc::new(DepGraphData {
167                previous_work_products: prev_work_products,
168                dep_node_debug: Default::default(),
169                current,
170                previous: prev_graph,
171                colors,
172                debug_loaded_from_disk: Default::default(),
173            })),
174            virtual_dep_node_index: Arc::new(AtomicU32::new(0)),
175        }
176    }
177
178    pub fn new_disabled() -> DepGraph<D> {
179        DepGraph { data: None, virtual_dep_node_index: Arc::new(AtomicU32::new(0)) }
180    }
181
182    #[inline]
183    pub(crate) fn data(&self) -> Option<&DepGraphData<D>> {
184        self.data.as_deref()
185    }
186
187    /// Returns `true` if we are actually building the full dep-graph, and `false` otherwise.
188    #[inline]
189    pub fn is_fully_enabled(&self) -> bool {
190        self.data.is_some()
191    }
192
193    pub fn with_query(&self, f: impl Fn(&DepGraphQuery)) {
194        if let Some(data) = &self.data {
195            data.current.encoder.with_query(f)
196        }
197    }
198
199    pub fn assert_ignored(&self) {
200        if let Some(..) = self.data {
201            D::read_deps(|task_deps| {
202                assert_matches!(
203                    task_deps,
204                    TaskDepsRef::Ignore,
205                    "expected no task dependency tracking"
206                );
207            })
208        }
209    }
210
211    pub fn with_ignore<OP, R>(&self, op: OP) -> R
212    where
213        OP: FnOnce() -> R,
214    {
215        D::with_deps(TaskDepsRef::Ignore, op)
216    }
217
218    /// Used to wrap the deserialization of a query result from disk,
219    /// This method enforces that no new `DepNodes` are created during
220    /// query result deserialization.
221    ///
222    /// Enforcing this makes the query dep graph simpler - all nodes
223    /// must be created during the query execution, and should be
224    /// created from inside the 'body' of a query (the implementation
225    /// provided by a particular compiler crate).
226    ///
227    /// Consider the case of three queries `A`, `B`, and `C`, where
228    /// `A` invokes `B` and `B` invokes `C`:
229    ///
230    /// `A -> B -> C`
231    ///
232    /// Suppose that decoding the result of query `B` required re-computing
233    /// the query `C`. If we did not create a fresh `TaskDeps` when
234    /// decoding `B`, we would still be using the `TaskDeps` for query `A`
235    /// (if we needed to re-execute `A`). This would cause us to create
236    /// a new edge `A -> C`. If this edge did not previously
237    /// exist in the `DepGraph`, then we could end up with a different
238    /// `DepGraph` at the end of compilation, even if there were no
239    /// meaningful changes to the overall program (e.g. a newline was added).
240    /// In addition, this edge might cause a subsequent compilation run
241    /// to try to force `C` before marking other necessary nodes green. If
242    /// `C` did not exist in the new compilation session, then we could
243    /// get an ICE. Normally, we would have tried (and failed) to mark
244    /// some other query green (e.g. `item_children`) which was used
245    /// to obtain `C`, which would prevent us from ever trying to force
246    /// a nonexistent `D`.
247    ///
248    /// It might be possible to enforce that all `DepNode`s read during
249    /// deserialization already exist in the previous `DepGraph`. In
250    /// the above example, we would invoke `D` during the deserialization
251    /// of `B`. Since we correctly create a new `TaskDeps` from the decoding
252    /// of `B`, this would result in an edge `B -> D`. If that edge already
253    /// existed (with the same `DepPathHash`es), then it should be correct
254    /// to allow the invocation of the query to proceed during deserialization
255    /// of a query result. We would merely assert that the dep-graph fragment
256    /// that would have been added by invoking `C` while decoding `B`
257    /// is equivalent to the dep-graph fragment that we already instantiated for B
258    /// (at the point where we successfully marked B as green).
259    ///
260    /// However, this would require additional complexity
261    /// in the query infrastructure, and is not currently needed by the
262    /// decoding of any query results. Should the need arise in the future,
263    /// we should consider extending the query system with this functionality.
264    pub fn with_query_deserialization<OP, R>(&self, op: OP) -> R
265    where
266        OP: FnOnce() -> R,
267    {
268        D::with_deps(TaskDepsRef::Forbid, op)
269    }
270
271    #[inline(always)]
272    pub fn with_task<Ctxt: HasDepContext<Deps = D>, A: Debug, R>(
273        &self,
274        key: DepNode,
275        cx: Ctxt,
276        arg: A,
277        task: fn(Ctxt, A) -> R,
278        hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
279    ) -> (R, DepNodeIndex) {
280        match self.data() {
281            Some(data) => data.with_task(key, cx, arg, task, hash_result),
282            None => (task(cx, arg), self.next_virtual_depnode_index()),
283        }
284    }
285
286    pub fn with_anon_task<Tcx: DepContext<Deps = D>, OP, R>(
287        &self,
288        cx: Tcx,
289        dep_kind: DepKind,
290        op: OP,
291    ) -> (R, DepNodeIndex)
292    where
293        OP: FnOnce() -> R,
294    {
295        match self.data() {
296            Some(data) => {
297                let (result, index) = data.with_anon_task_inner(cx, dep_kind, op);
298                self.read_index(index);
299                (result, index)
300            }
301            None => (op(), self.next_virtual_depnode_index()),
302        }
303    }
304}
305
306impl<D: Deps> DepGraphData<D> {
307    /// Starts a new dep-graph task. Dep-graph tasks are specified
308    /// using a free function (`task`) and **not** a closure -- this
309    /// is intentional because we want to exercise tight control over
310    /// what state they have access to. In particular, we want to
311    /// prevent implicit 'leaks' of tracked state into the task (which
312    /// could then be read without generating correct edges in the
313    /// dep-graph -- see the [rustc dev guide] for more details on
314    /// the dep-graph). To this end, the task function gets exactly two
315    /// pieces of state: the context `cx` and an argument `arg`. Both
316    /// of these bits of state must be of some type that implements
317    /// `DepGraphSafe` and hence does not leak.
318    ///
319    /// The choice of two arguments is not fundamental. One argument
320    /// would work just as well, since multiple values can be
321    /// collected using tuples. However, using two arguments works out
322    /// to be quite convenient, since it is common to need a context
323    /// (`cx`) and some argument (e.g., a `DefId` identifying what
324    /// item to process).
325    ///
326    /// For cases where you need some other number of arguments:
327    ///
328    /// - If you only need one argument, just use `()` for the `arg`
329    ///   parameter.
330    /// - If you need 3+ arguments, use a tuple for the
331    ///   `arg` parameter.
332    ///
333    /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/queries/incremental-compilation.html
334    #[inline(always)]
335    pub(crate) fn with_task<Ctxt: HasDepContext<Deps = D>, A: Debug, R>(
336        &self,
337        key: DepNode,
338        cx: Ctxt,
339        arg: A,
340        task: fn(Ctxt, A) -> R,
341        hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
342    ) -> (R, DepNodeIndex) {
343        // If the following assertion triggers, it can have two reasons:
344        // 1. Something is wrong with DepNode creation, either here or
345        //    in `DepGraph::try_mark_green()`.
346        // 2. Two distinct query keys get mapped to the same `DepNode`
347        //    (see for example #48923).
348        self.assert_dep_node_not_yet_allocated_in_current_session(&key, || {
349            format!(
350                "forcing query with already existing `DepNode`\n\
351                 - query-key: {arg:?}\n\
352                 - dep-node: {key:?}"
353            )
354        });
355
356        let with_deps = |task_deps| D::with_deps(task_deps, || task(cx, arg));
357        let (result, edges) = if cx.dep_context().is_eval_always(key.kind) {
358            (with_deps(TaskDepsRef::EvalAlways), EdgesVec::new())
359        } else {
360            let task_deps = Lock::new(TaskDeps {
361                #[cfg(debug_assertions)]
362                node: Some(key),
363                reads: EdgesVec::new(),
364                read_set: Default::default(),
365                phantom_data: PhantomData,
366            });
367            (with_deps(TaskDepsRef::Allow(&task_deps)), task_deps.into_inner().reads)
368        };
369
370        let dcx = cx.dep_context();
371        let dep_node_index = self.hash_result_and_alloc_node(dcx, key, edges, &result, hash_result);
372
373        (result, dep_node_index)
374    }
375
376    /// Executes something within an "anonymous" task, that is, a task the
377    /// `DepNode` of which is determined by the list of inputs it read from.
378    ///
379    /// NOTE: this does not actually count as a read of the DepNode here.
380    /// Using the result of this task without reading the DepNode will result
381    /// in untracked dependencies which may lead to ICEs as nodes are
382    /// incorrectly marked green.
383    ///
384    /// FIXME: This could perhaps return a `WithDepNode` to ensure that the
385    /// user of this function actually performs the read; we'll have to see
386    /// how to make that work with `anon` in `execute_job_incr`, though.
387    pub(crate) fn with_anon_task_inner<Tcx: DepContext<Deps = D>, OP, R>(
388        &self,
389        cx: Tcx,
390        dep_kind: DepKind,
391        op: OP,
392    ) -> (R, DepNodeIndex)
393    where
394        OP: FnOnce() -> R,
395    {
396        debug_assert!(!cx.is_eval_always(dep_kind));
397
398        let task_deps = Lock::new(TaskDeps::default());
399        let result = D::with_deps(TaskDepsRef::Allow(&task_deps), op);
400        let task_deps = task_deps.into_inner();
401        let task_deps = task_deps.reads;
402
403        let dep_node_index = match task_deps.len() {
404            0 => {
405                // Because the dep-node id of anon nodes is computed from the sets of its
406                // dependencies we already know what the ID of this dependency-less node is
407                // going to be (i.e. equal to the precomputed
408                // `SINGLETON_DEPENDENCYLESS_ANON_NODE`). As a consequence we can skip creating
409                // a `StableHasher` and sending the node through interning.
410                DepNodeIndex::SINGLETON_ZERO_DEPS_ANON_NODE
411            }
412            1 => {
413                // When there is only one dependency, don't bother creating a node.
414                task_deps[0]
415            }
416            _ => {
417                // The dep node indices are hashed here instead of hashing the dep nodes of the
418                // dependencies. These indices may refer to different nodes per session, but this isn't
419                // a problem here because we that ensure the final dep node hash is per session only by
420                // combining it with the per session random number `anon_id_seed`. This hash only need
421                // to map the dependencies to a single value on a per session basis.
422                let mut hasher = StableHasher::new();
423                task_deps.hash(&mut hasher);
424
425                let target_dep_node = DepNode {
426                    kind: dep_kind,
427                    // Fingerprint::combine() is faster than sending Fingerprint
428                    // through the StableHasher (at least as long as StableHasher
429                    // is so slow).
430                    hash: self.current.anon_id_seed.combine(hasher.finish()).into(),
431                };
432
433                // The DepNodes generated by the process above are not unique. 2 queries could
434                // have exactly the same dependencies. However, deserialization does not handle
435                // duplicated nodes, so we do the deduplication here directly.
436                //
437                // As anonymous nodes are a small quantity compared to the full dep-graph, the
438                // memory impact of this `anon_node_to_index` map remains tolerable, and helps
439                // us avoid useless growth of the graph with almost-equivalent nodes.
440                self.current.anon_node_to_index.get_or_insert_with(target_dep_node, || {
441                    self.current.alloc_new_node(target_dep_node, task_deps, Fingerprint::ZERO)
442                })
443            }
444        };
445
446        (result, dep_node_index)
447    }
448
449    /// Intern the new `DepNode` with the dependencies up-to-now.
450    fn hash_result_and_alloc_node<Ctxt: DepContext<Deps = D>, R>(
451        &self,
452        cx: &Ctxt,
453        node: DepNode,
454        edges: EdgesVec,
455        result: &R,
456        hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
457    ) -> DepNodeIndex {
458        let hashing_timer = cx.profiler().incr_result_hashing();
459        let current_fingerprint = hash_result.map(|hash_result| {
460            cx.with_stable_hashing_context(|mut hcx| hash_result(&mut hcx, result))
461        });
462        let dep_node_index = self.alloc_and_color_node(node, edges, current_fingerprint);
463        hashing_timer.finish_with_query_invocation_id(dep_node_index.into());
464        dep_node_index
465    }
466}
467
468impl<D: Deps> DepGraph<D> {
469    #[inline]
470    pub fn read_index(&self, dep_node_index: DepNodeIndex) {
471        if let Some(ref data) = self.data {
472            D::read_deps(|task_deps| {
473                let mut task_deps = match task_deps {
474                    TaskDepsRef::Allow(deps) => deps.lock(),
475                    TaskDepsRef::EvalAlways => {
476                        // We don't need to record dependencies of eval_always
477                        // queries. They are re-evaluated unconditionally anyway.
478                        return;
479                    }
480                    TaskDepsRef::Ignore => return,
481                    TaskDepsRef::Forbid => {
482                        // Reading is forbidden in this context. ICE with a useful error message.
483                        panic_on_forbidden_read(data, dep_node_index)
484                    }
485                };
486                let task_deps = &mut *task_deps;
487
488                if cfg!(debug_assertions) {
489                    data.current.total_read_count.fetch_add(1, Ordering::Relaxed);
490                }
491
492                // As long as we only have a low number of reads we can avoid doing a hash
493                // insert and potentially allocating/reallocating the hashmap
494                let new_read = if task_deps.reads.len() < EdgesVec::INLINE_CAPACITY {
495                    task_deps.reads.iter().all(|other| *other != dep_node_index)
496                } else {
497                    task_deps.read_set.insert(dep_node_index)
498                };
499                if new_read {
500                    task_deps.reads.push(dep_node_index);
501                    if task_deps.reads.len() == EdgesVec::INLINE_CAPACITY {
502                        // Fill `read_set` with what we have so far so we can use the hashset
503                        // next time
504                        task_deps.read_set.extend(task_deps.reads.iter().copied());
505                    }
506
507                    #[cfg(debug_assertions)]
508                    {
509                        if let Some(target) = task_deps.node {
510                            if let Some(ref forbidden_edge) = data.current.forbidden_edge {
511                                let src = forbidden_edge.index_to_node.lock()[&dep_node_index];
512                                if forbidden_edge.test(&src, &target) {
513                                    panic!("forbidden edge {:?} -> {:?} created", src, target)
514                                }
515                            }
516                        }
517                    }
518                } else if cfg!(debug_assertions) {
519                    data.current.total_duplicate_read_count.fetch_add(1, Ordering::Relaxed);
520                }
521            })
522        }
523    }
524
525    /// This encodes a diagnostic by creating a node with an unique index and assoicating
526    /// `diagnostic` with it, for use in the next session.
527    #[inline]
528    pub fn record_diagnostic<Qcx: QueryContext>(&self, qcx: Qcx, diagnostic: &DiagInner) {
529        if let Some(ref data) = self.data {
530            D::read_deps(|task_deps| match task_deps {
531                TaskDepsRef::EvalAlways | TaskDepsRef::Ignore => return,
532                TaskDepsRef::Forbid | TaskDepsRef::Allow(..) => {
533                    self.read_index(data.encode_diagnostic(qcx, diagnostic));
534                }
535            })
536        }
537    }
538    /// This forces a diagnostic node green by running its side effect. `prev_index` would
539    /// refer to a node created used `encode_diagnostic` in the previous session.
540    #[inline]
541    pub fn force_diagnostic_node<Qcx: QueryContext>(
542        &self,
543        qcx: Qcx,
544        prev_index: SerializedDepNodeIndex,
545    ) {
546        if let Some(ref data) = self.data {
547            data.force_diagnostic_node(qcx, prev_index);
548        }
549    }
550
551    /// Create a node when we force-feed a value into the query cache.
552    /// This is used to remove cycles during type-checking const generic parameters.
553    ///
554    /// As usual in the query system, we consider the current state of the calling query
555    /// only depends on the list of dependencies up to now. As a consequence, the value
556    /// that this query gives us can only depend on those dependencies too. Therefore,
557    /// it is sound to use the current dependency set for the created node.
558    ///
559    /// During replay, the order of the nodes is relevant in the dependency graph.
560    /// So the unchanged replay will mark the caller query before trying to mark this one.
561    /// If there is a change to report, the caller query will be re-executed before this one.
562    ///
563    /// FIXME: If the code is changed enough for this node to be marked before requiring the
564    /// caller's node, we suppose that those changes will be enough to mark this node red and
565    /// force a recomputation using the "normal" way.
566    pub fn with_feed_task<Ctxt: DepContext<Deps = D>, R: Debug>(
567        &self,
568        node: DepNode,
569        cx: Ctxt,
570        result: &R,
571        hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
572    ) -> DepNodeIndex {
573        if let Some(data) = self.data.as_ref() {
574            // The caller query has more dependencies than the node we are creating. We may
575            // encounter a case where this created node is marked as green, but the caller query is
576            // subsequently marked as red or recomputed. In this case, we will end up feeding a
577            // value to an existing node.
578            //
579            // For sanity, we still check that the loaded stable hash and the new one match.
580            if let Some(prev_index) = data.previous.node_to_index_opt(&node) {
581                let dep_node_index = data.colors.current(prev_index);
582                if let Some(dep_node_index) = dep_node_index {
583                    crate::query::incremental_verify_ich(
584                        cx,
585                        data,
586                        result,
587                        prev_index,
588                        hash_result,
589                        |value| format!("{value:?}"),
590                    );
591
592                    #[cfg(debug_assertions)]
593                    if hash_result.is_some() {
594                        data.current.record_edge(
595                            dep_node_index,
596                            node,
597                            data.prev_fingerprint_of(prev_index),
598                        );
599                    }
600
601                    return dep_node_index;
602                }
603            }
604
605            let mut edges = EdgesVec::new();
606            D::read_deps(|task_deps| match task_deps {
607                TaskDepsRef::Allow(deps) => edges.extend(deps.lock().reads.iter().copied()),
608                TaskDepsRef::EvalAlways => {
609                    edges.push(DepNodeIndex::FOREVER_RED_NODE);
610                }
611                TaskDepsRef::Ignore => {}
612                TaskDepsRef::Forbid => {
613                    panic!("Cannot summarize when dependencies are not recorded.")
614                }
615            });
616
617            data.hash_result_and_alloc_node(&cx, node, edges, result, hash_result)
618        } else {
619            // Incremental compilation is turned off. We just execute the task
620            // without tracking. We still provide a dep-node index that uniquely
621            // identifies the task so that we have a cheap way of referring to
622            // the query for self-profiling.
623            self.next_virtual_depnode_index()
624        }
625    }
626}
627
628impl<D: Deps> DepGraphData<D> {
629    fn assert_dep_node_not_yet_allocated_in_current_session<S: std::fmt::Display>(
630        &self,
631        dep_node: &DepNode,
632        msg: impl FnOnce() -> S,
633    ) {
634        if let Some(prev_index) = self.previous.node_to_index_opt(dep_node) {
635            let current = self.colors.get(prev_index);
636            assert!(current.is_none(), "{}", msg())
637        } else if let Some(nodes_in_current_session) = &self.current.nodes_in_current_session {
638            outline(|| {
639                let seen = nodes_in_current_session.lock().contains_key(dep_node);
640                assert!(!seen, "{}", msg());
641            });
642        }
643    }
644
645    fn node_color(&self, dep_node: &DepNode) -> Option<DepNodeColor> {
646        if let Some(prev_index) = self.previous.node_to_index_opt(dep_node) {
647            self.colors.get(prev_index)
648        } else {
649            // This is a node that did not exist in the previous compilation session.
650            None
651        }
652    }
653
654    /// Returns true if the given node has been marked as green during the
655    /// current compilation session. Used in various assertions
656    #[inline]
657    pub(crate) fn is_index_green(&self, prev_index: SerializedDepNodeIndex) -> bool {
658        self.colors.get(prev_index).is_some_and(|c| c.is_green())
659    }
660
661    #[inline]
662    pub(crate) fn prev_fingerprint_of(&self, prev_index: SerializedDepNodeIndex) -> Fingerprint {
663        self.previous.fingerprint_by_index(prev_index)
664    }
665
666    #[inline]
667    pub(crate) fn prev_node_of(&self, prev_index: SerializedDepNodeIndex) -> DepNode {
668        self.previous.index_to_node(prev_index)
669    }
670
671    pub(crate) fn mark_debug_loaded_from_disk(&self, dep_node: DepNode) {
672        self.debug_loaded_from_disk.lock().insert(dep_node);
673    }
674
675    /// This encodes a diagnostic by creating a node with an unique index and assoicating
676    /// `diagnostic` with it, for use in the next session.
677    #[inline]
678    fn encode_diagnostic<Qcx: QueryContext>(
679        &self,
680        qcx: Qcx,
681        diagnostic: &DiagInner,
682    ) -> DepNodeIndex {
683        // Use `send_new` so we get an unique index, even though the dep node is not.
684        let dep_node_index = self.current.encoder.send_new(
685            DepNode {
686                kind: D::DEP_KIND_SIDE_EFFECT,
687                hash: PackedFingerprint::from(Fingerprint::ZERO),
688            },
689            Fingerprint::ZERO,
690            // We want the side effect node to always be red so it will be forced and emit the
691            // diagnostic.
692            std::iter::once(DepNodeIndex::FOREVER_RED_NODE).collect(),
693        );
694        let side_effect = QuerySideEffect::Diagnostic(diagnostic.clone());
695        qcx.store_side_effect(dep_node_index, side_effect);
696        dep_node_index
697    }
698
699    /// This forces a diagnostic node green by running its side effect. `prev_index` would
700    /// refer to a node created used `encode_diagnostic` in the previous session.
701    #[inline]
702    fn force_diagnostic_node<Qcx: QueryContext>(
703        &self,
704        qcx: Qcx,
705        prev_index: SerializedDepNodeIndex,
706    ) {
707        D::with_deps(TaskDepsRef::Ignore, || {
708            let side_effect = qcx.load_side_effect(prev_index).unwrap();
709
710            match &side_effect {
711                QuerySideEffect::Diagnostic(diagnostic) => {
712                    qcx.dep_context().sess().dcx().emit_diagnostic(diagnostic.clone());
713                }
714            }
715
716            // Use `send_and_color` as `promote_node_and_deps_to_current` expects all
717            // green dependencies. `send_and_color` will also prevent multiple nodes
718            // being encoded for concurrent calls.
719            let dep_node_index = self.current.encoder.send_and_color(
720                prev_index,
721                &self.colors,
722                DepNode {
723                    kind: D::DEP_KIND_SIDE_EFFECT,
724                    hash: PackedFingerprint::from(Fingerprint::ZERO),
725                },
726                Fingerprint::ZERO,
727                std::iter::once(DepNodeIndex::FOREVER_RED_NODE).collect(),
728                true,
729            );
730            // This will just overwrite the same value for concurrent calls.
731            qcx.store_side_effect(dep_node_index, side_effect);
732        })
733    }
734
735    fn alloc_and_color_node(
736        &self,
737        key: DepNode,
738        edges: EdgesVec,
739        fingerprint: Option<Fingerprint>,
740    ) -> DepNodeIndex {
741        if let Some(prev_index) = self.previous.node_to_index_opt(&key) {
742            // Determine the color and index of the new `DepNode`.
743            let is_green = if let Some(fingerprint) = fingerprint {
744                if fingerprint == self.previous.fingerprint_by_index(prev_index) {
745                    // This is a green node: it existed in the previous compilation,
746                    // its query was re-executed, and it has the same result as before.
747                    true
748                } else {
749                    // This is a red node: it existed in the previous compilation, its query
750                    // was re-executed, but it has a different result from before.
751                    false
752                }
753            } else {
754                // This is a red node, effectively: it existed in the previous compilation
755                // session, its query was re-executed, but it doesn't compute a result hash
756                // (i.e. it represents a `no_hash` query), so we have no way of determining
757                // whether or not the result was the same as before.
758                false
759            };
760
761            let fingerprint = fingerprint.unwrap_or(Fingerprint::ZERO);
762
763            let dep_node_index = self.current.encoder.send_and_color(
764                prev_index,
765                &self.colors,
766                key,
767                fingerprint,
768                edges,
769                is_green,
770            );
771
772            self.current.record_node(dep_node_index, key, fingerprint);
773
774            dep_node_index
775        } else {
776            self.current.alloc_new_node(key, edges, fingerprint.unwrap_or(Fingerprint::ZERO))
777        }
778    }
779
780    fn promote_node_and_deps_to_current(&self, prev_index: SerializedDepNodeIndex) -> DepNodeIndex {
781        self.current.debug_assert_not_in_new_nodes(&self.previous, prev_index);
782
783        let dep_node_index = self.current.encoder.send_promoted(prev_index, &self.colors);
784
785        #[cfg(debug_assertions)]
786        self.current.record_edge(
787            dep_node_index,
788            self.previous.index_to_node(prev_index),
789            self.previous.fingerprint_by_index(prev_index),
790        );
791
792        dep_node_index
793    }
794}
795
796impl<D: Deps> DepGraph<D> {
797    /// Checks whether a previous work product exists for `v` and, if
798    /// so, return the path that leads to it. Used to skip doing work.
799    pub fn previous_work_product(&self, v: &WorkProductId) -> Option<WorkProduct> {
800        self.data.as_ref().and_then(|data| data.previous_work_products.get(v).cloned())
801    }
802
803    /// Access the map of work-products created during the cached run. Only
804    /// used during saving of the dep-graph.
805    pub fn previous_work_products(&self) -> &WorkProductMap {
806        &self.data.as_ref().unwrap().previous_work_products
807    }
808
809    pub fn debug_was_loaded_from_disk(&self, dep_node: DepNode) -> bool {
810        self.data.as_ref().unwrap().debug_loaded_from_disk.lock().contains(&dep_node)
811    }
812
813    #[cfg(debug_assertions)]
814    #[inline(always)]
815    pub(crate) fn register_dep_node_debug_str<F>(&self, dep_node: DepNode, debug_str_gen: F)
816    where
817        F: FnOnce() -> String,
818    {
819        let dep_node_debug = &self.data.as_ref().unwrap().dep_node_debug;
820
821        if dep_node_debug.borrow().contains_key(&dep_node) {
822            return;
823        }
824        let debug_str = self.with_ignore(debug_str_gen);
825        dep_node_debug.borrow_mut().insert(dep_node, debug_str);
826    }
827
828    pub fn dep_node_debug_str(&self, dep_node: DepNode) -> Option<String> {
829        self.data.as_ref()?.dep_node_debug.borrow().get(&dep_node).cloned()
830    }
831
832    fn node_color(&self, dep_node: &DepNode) -> Option<DepNodeColor> {
833        if let Some(ref data) = self.data {
834            return data.node_color(dep_node);
835        }
836
837        None
838    }
839
840    pub fn try_mark_green<Qcx: QueryContext<Deps = D>>(
841        &self,
842        qcx: Qcx,
843        dep_node: &DepNode,
844    ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
845        self.data().and_then(|data| data.try_mark_green(qcx, dep_node))
846    }
847}
848
849impl<D: Deps> DepGraphData<D> {
850    /// Try to mark a node index for the node dep_node.
851    ///
852    /// A node will have an index, when it's already been marked green, or when we can mark it
853    /// green. This function will mark the current task as a reader of the specified node, when
854    /// a node index can be found for that node.
855    pub(crate) fn try_mark_green<Qcx: QueryContext<Deps = D>>(
856        &self,
857        qcx: Qcx,
858        dep_node: &DepNode,
859    ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
860        debug_assert!(!qcx.dep_context().is_eval_always(dep_node.kind));
861
862        // Return None if the dep node didn't exist in the previous session
863        let prev_index = self.previous.node_to_index_opt(dep_node)?;
864
865        match self.colors.get(prev_index) {
866            Some(DepNodeColor::Green(dep_node_index)) => Some((prev_index, dep_node_index)),
867            Some(DepNodeColor::Red) => None,
868            None => {
869                // This DepNode and the corresponding query invocation existed
870                // in the previous compilation session too, so we can try to
871                // mark it as green by recursively marking all of its
872                // dependencies green.
873                self.try_mark_previous_green(qcx, prev_index, dep_node, None)
874                    .map(|dep_node_index| (prev_index, dep_node_index))
875            }
876        }
877    }
878
879    #[instrument(skip(self, qcx, parent_dep_node_index, frame), level = "debug")]
880    fn try_mark_parent_green<Qcx: QueryContext<Deps = D>>(
881        &self,
882        qcx: Qcx,
883        parent_dep_node_index: SerializedDepNodeIndex,
884        frame: Option<&MarkFrame<'_>>,
885    ) -> Option<()> {
886        let dep_dep_node_color = self.colors.get(parent_dep_node_index);
887        let dep_dep_node = &self.previous.index_to_node(parent_dep_node_index);
888
889        match dep_dep_node_color {
890            Some(DepNodeColor::Green(_)) => {
891                // This dependency has been marked as green before, we are
892                // still fine and can continue with checking the other
893                // dependencies.
894                debug!("dependency {dep_dep_node:?} was immediately green");
895                return Some(());
896            }
897            Some(DepNodeColor::Red) => {
898                // We found a dependency the value of which has changed
899                // compared to the previous compilation session. We cannot
900                // mark the DepNode as green and also don't need to bother
901                // with checking any of the other dependencies.
902                debug!("dependency {dep_dep_node:?} was immediately red");
903                return None;
904            }
905            None => {}
906        }
907
908        // We don't know the state of this dependency. If it isn't
909        // an eval_always node, let's try to mark it green recursively.
910        if !qcx.dep_context().is_eval_always(dep_dep_node.kind) {
911            debug!(
912                "state of dependency {:?} ({}) is unknown, trying to mark it green",
913                dep_dep_node, dep_dep_node.hash,
914            );
915
916            let node_index =
917                self.try_mark_previous_green(qcx, parent_dep_node_index, dep_dep_node, frame);
918
919            if node_index.is_some() {
920                debug!("managed to MARK dependency {dep_dep_node:?} as green");
921                return Some(());
922            }
923        }
924
925        // We failed to mark it green, so we try to force the query.
926        debug!("trying to force dependency {dep_dep_node:?}");
927        if !qcx.dep_context().try_force_from_dep_node(*dep_dep_node, parent_dep_node_index, frame) {
928            // The DepNode could not be forced.
929            debug!("dependency {dep_dep_node:?} could not be forced");
930            return None;
931        }
932
933        let dep_dep_node_color = self.colors.get(parent_dep_node_index);
934
935        match dep_dep_node_color {
936            Some(DepNodeColor::Green(_)) => {
937                debug!("managed to FORCE dependency {dep_dep_node:?} to green");
938                return Some(());
939            }
940            Some(DepNodeColor::Red) => {
941                debug!("dependency {dep_dep_node:?} was red after forcing");
942                return None;
943            }
944            None => {}
945        }
946
947        if let None = qcx.dep_context().sess().dcx().has_errors_or_delayed_bugs() {
948            panic!("try_mark_previous_green() - Forcing the DepNode should have set its color")
949        }
950
951        // If the query we just forced has resulted in
952        // some kind of compilation error, we cannot rely on
953        // the dep-node color having been properly updated.
954        // This means that the query system has reached an
955        // invalid state. We let the compiler continue (by
956        // returning `None`) so it can emit error messages
957        // and wind down, but rely on the fact that this
958        // invalid state will not be persisted to the
959        // incremental compilation cache because of
960        // compilation errors being present.
961        debug!("dependency {dep_dep_node:?} resulted in compilation error");
962        return None;
963    }
964
965    /// Try to mark a dep-node which existed in the previous compilation session as green.
966    #[instrument(skip(self, qcx, prev_dep_node_index, frame), level = "debug")]
967    fn try_mark_previous_green<Qcx: QueryContext<Deps = D>>(
968        &self,
969        qcx: Qcx,
970        prev_dep_node_index: SerializedDepNodeIndex,
971        dep_node: &DepNode,
972        frame: Option<&MarkFrame<'_>>,
973    ) -> Option<DepNodeIndex> {
974        let frame = MarkFrame { index: prev_dep_node_index, parent: frame };
975
976        // We never try to mark eval_always nodes as green
977        debug_assert!(!qcx.dep_context().is_eval_always(dep_node.kind));
978
979        debug_assert_eq!(self.previous.index_to_node(prev_dep_node_index), *dep_node);
980
981        let prev_deps = self.previous.edge_targets_from(prev_dep_node_index);
982
983        for dep_dep_node_index in prev_deps {
984            self.try_mark_parent_green(qcx, dep_dep_node_index, Some(&frame))?;
985        }
986
987        // If we got here without hitting a `return` that means that all
988        // dependencies of this DepNode could be marked as green. Therefore we
989        // can also mark this DepNode as green.
990
991        // There may be multiple threads trying to mark the same dep node green concurrently
992
993        // We allocating an entry for the node in the current dependency graph and
994        // adding all the appropriate edges imported from the previous graph
995        let dep_node_index = self.promote_node_and_deps_to_current(prev_dep_node_index);
996
997        // ... and finally storing a "Green" entry in the color map.
998        // Multiple threads can all write the same color here
999
1000        debug!("successfully marked {dep_node:?} as green");
1001        Some(dep_node_index)
1002    }
1003}
1004
1005impl<D: Deps> DepGraph<D> {
1006    /// Returns true if the given node has been marked as red during the
1007    /// current compilation session. Used in various assertions
1008    pub fn is_red(&self, dep_node: &DepNode) -> bool {
1009        matches!(self.node_color(dep_node), Some(DepNodeColor::Red))
1010    }
1011
1012    /// Returns true if the given node has been marked as green during the
1013    /// current compilation session. Used in various assertions
1014    pub fn is_green(&self, dep_node: &DepNode) -> bool {
1015        self.node_color(dep_node).is_some_and(|c| c.is_green())
1016    }
1017
1018    pub fn assert_dep_node_not_yet_allocated_in_current_session<S: std::fmt::Display>(
1019        &self,
1020        dep_node: &DepNode,
1021        msg: impl FnOnce() -> S,
1022    ) {
1023        if let Some(data) = &self.data {
1024            data.assert_dep_node_not_yet_allocated_in_current_session(dep_node, msg)
1025        }
1026    }
1027
1028    /// This method loads all on-disk cacheable query results into memory, so
1029    /// they can be written out to the new cache file again. Most query results
1030    /// will already be in memory but in the case where we marked something as
1031    /// green but then did not need the value, that value will never have been
1032    /// loaded from disk.
1033    ///
1034    /// This method will only load queries that will end up in the disk cache.
1035    /// Other queries will not be executed.
1036    pub fn exec_cache_promotions<Tcx: DepContext>(&self, tcx: Tcx) {
1037        let _prof_timer = tcx.profiler().generic_activity("incr_comp_query_cache_promotion");
1038
1039        let data = self.data.as_ref().unwrap();
1040        for prev_index in data.colors.values.indices() {
1041            match data.colors.get(prev_index) {
1042                Some(DepNodeColor::Green(_)) => {
1043                    let dep_node = data.previous.index_to_node(prev_index);
1044                    tcx.try_load_from_on_disk_cache(dep_node);
1045                }
1046                None | Some(DepNodeColor::Red) => {
1047                    // We can skip red nodes because a node can only be marked
1048                    // as red if the query result was recomputed and thus is
1049                    // already in memory.
1050                }
1051            }
1052        }
1053    }
1054
1055    pub fn print_incremental_info(&self) {
1056        if let Some(data) = &self.data {
1057            data.current.encoder.print_incremental_info(
1058                data.current.total_read_count.load(Ordering::Relaxed),
1059                data.current.total_duplicate_read_count.load(Ordering::Relaxed),
1060            )
1061        }
1062    }
1063
1064    pub fn finish_encoding(&self) -> FileEncodeResult {
1065        if let Some(data) = &self.data { data.current.encoder.finish() } else { Ok(0) }
1066    }
1067
1068    pub(crate) fn next_virtual_depnode_index(&self) -> DepNodeIndex {
1069        debug_assert!(self.data.is_none());
1070        let index = self.virtual_dep_node_index.fetch_add(1, Ordering::Relaxed);
1071        DepNodeIndex::from_u32(index)
1072    }
1073}
1074
1075/// A "work product" is an intermediate result that we save into the
1076/// incremental directory for later re-use. The primary example are
1077/// the object files that we save for each partition at code
1078/// generation time.
1079///
1080/// Each work product is associated with a dep-node, representing the
1081/// process that produced the work-product. If that dep-node is found
1082/// to be dirty when we load up, then we will delete the work-product
1083/// at load time. If the work-product is found to be clean, then we
1084/// will keep a record in the `previous_work_products` list.
1085///
1086/// In addition, work products have an associated hash. This hash is
1087/// an extra hash that can be used to decide if the work-product from
1088/// a previous compilation can be re-used (in addition to the dirty
1089/// edges check).
1090///
1091/// As the primary example, consider the object files we generate for
1092/// each partition. In the first run, we create partitions based on
1093/// the symbols that need to be compiled. For each partition P, we
1094/// hash the symbols in P and create a `WorkProduct` record associated
1095/// with `DepNode::CodegenUnit(P)`; the hash is the set of symbols
1096/// in P.
1097///
1098/// The next time we compile, if the `DepNode::CodegenUnit(P)` is
1099/// judged to be clean (which means none of the things we read to
1100/// generate the partition were found to be dirty), it will be loaded
1101/// into previous work products. We will then regenerate the set of
1102/// symbols in the partition P and hash them (note that new symbols
1103/// may be added -- for example, new monomorphizations -- even if
1104/// nothing in P changed!). We will compare that hash against the
1105/// previous hash. If it matches up, we can reuse the object file.
1106#[derive(Clone, Debug, Encodable, Decodable)]
1107pub struct WorkProduct {
1108    pub cgu_name: String,
1109    /// Saved files associated with this CGU. In each key/value pair, the value is the path to the
1110    /// saved file and the key is some identifier for the type of file being saved.
1111    ///
1112    /// By convention, file extensions are currently used as identifiers, i.e. the key "o" maps to
1113    /// the object file's path, and "dwo" to the dwarf object file's path.
1114    pub saved_files: UnordMap<String, String>,
1115}
1116
1117pub type WorkProductMap = UnordMap<WorkProductId, WorkProduct>;
1118
1119// Index type for `DepNodeData`'s edges.
1120rustc_index::newtype_index! {
1121    struct EdgeIndex {}
1122}
1123
1124/// `CurrentDepGraph` stores the dependency graph for the current session. It
1125/// will be populated as we run queries or tasks. We never remove nodes from the
1126/// graph: they are only added.
1127///
1128/// The nodes in it are identified by a `DepNodeIndex`. We avoid keeping the nodes
1129/// in memory. This is important, because these graph structures are some of the
1130/// largest in the compiler.
1131///
1132/// For this reason, we avoid storing `DepNode`s more than once as map
1133/// keys. The `anon_node_to_index` map only contains nodes of anonymous queries not in the previous
1134/// graph, and we map nodes in the previous graph to indices via a two-step
1135/// mapping. `SerializedDepGraph` maps from `DepNode` to `SerializedDepNodeIndex`,
1136/// and the `prev_index_to_index` vector (which is more compact and faster than
1137/// using a map) maps from `SerializedDepNodeIndex` to `DepNodeIndex`.
1138///
1139/// This struct uses three locks internally. The `data`, `anon_node_to_index`,
1140/// and `prev_index_to_index` fields are locked separately. Operations that take
1141/// a `DepNodeIndex` typically just access the `data` field.
1142///
1143/// We only need to manipulate at most two locks simultaneously:
1144/// `anon_node_to_index` and `data`, or `prev_index_to_index` and `data`. When
1145/// manipulating both, we acquire `anon_node_to_index` or `prev_index_to_index`
1146/// first, and `data` second.
1147pub(super) struct CurrentDepGraph<D: Deps> {
1148    encoder: GraphEncoder<D>,
1149    anon_node_to_index: ShardedHashMap<DepNode, DepNodeIndex>,
1150
1151    /// This is used to verify that fingerprints do not change between the creation of a node
1152    /// and its recomputation.
1153    #[cfg(debug_assertions)]
1154    fingerprints: Lock<IndexVec<DepNodeIndex, Option<Fingerprint>>>,
1155
1156    /// Used to trap when a specific edge is added to the graph.
1157    /// This is used for debug purposes and is only active with `debug_assertions`.
1158    #[cfg(debug_assertions)]
1159    forbidden_edge: Option<EdgeFilter>,
1160
1161    /// Used to verify the absence of hash collisions among DepNodes.
1162    /// This field is only `Some` if the `-Z incremental_verify_ich` option is present
1163    /// or if `debug_assertions` are enabled.
1164    ///
1165    /// The map contains all DepNodes that have been allocated in the current session so far.
1166    nodes_in_current_session: Option<Lock<FxHashMap<DepNode, DepNodeIndex>>>,
1167
1168    /// Anonymous `DepNode`s are nodes whose IDs we compute from the list of
1169    /// their edges. This has the beneficial side-effect that multiple anonymous
1170    /// nodes can be coalesced into one without changing the semantics of the
1171    /// dependency graph. However, the merging of nodes can lead to a subtle
1172    /// problem during red-green marking: The color of an anonymous node from
1173    /// the current session might "shadow" the color of the node with the same
1174    /// ID from the previous session. In order to side-step this problem, we make
1175    /// sure that anonymous `NodeId`s allocated in different sessions don't overlap.
1176    /// This is implemented by mixing a session-key into the ID fingerprint of
1177    /// each anon node. The session-key is a hash of the number of previous sessions.
1178    anon_id_seed: Fingerprint,
1179
1180    /// These are simple counters that are for profiling and
1181    /// debugging and only active with `debug_assertions`.
1182    total_read_count: AtomicU64,
1183    total_duplicate_read_count: AtomicU64,
1184}
1185
1186impl<D: Deps> CurrentDepGraph<D> {
1187    fn new(
1188        session: &Session,
1189        prev_graph_node_count: usize,
1190        encoder: FileEncoder,
1191        record_graph: bool,
1192        record_stats: bool,
1193        previous: Arc<SerializedDepGraph>,
1194    ) -> Self {
1195        let mut stable_hasher = StableHasher::new();
1196        previous.session_count().hash(&mut stable_hasher);
1197        let anon_id_seed = stable_hasher.finish();
1198
1199        #[cfg(debug_assertions)]
1200        let forbidden_edge = match env::var("RUST_FORBID_DEP_GRAPH_EDGE") {
1201            Ok(s) => match EdgeFilter::new(&s) {
1202                Ok(f) => Some(f),
1203                Err(err) => panic!("RUST_FORBID_DEP_GRAPH_EDGE invalid: {}", err),
1204            },
1205            Err(_) => None,
1206        };
1207
1208        let new_node_count_estimate = 102 * prev_graph_node_count / 100 + 200;
1209
1210        let new_node_dbg =
1211            session.opts.unstable_opts.incremental_verify_ich || cfg!(debug_assertions);
1212
1213        CurrentDepGraph {
1214            encoder: GraphEncoder::new(
1215                encoder,
1216                prev_graph_node_count,
1217                record_graph,
1218                record_stats,
1219                &session.prof,
1220                previous,
1221            ),
1222            anon_node_to_index: ShardedHashMap::with_capacity(
1223                // FIXME: The count estimate is off as anon nodes are only a portion of the nodes.
1224                new_node_count_estimate / sharded::shards(),
1225            ),
1226            anon_id_seed,
1227            #[cfg(debug_assertions)]
1228            forbidden_edge,
1229            #[cfg(debug_assertions)]
1230            fingerprints: Lock::new(IndexVec::from_elem_n(None, new_node_count_estimate)),
1231            nodes_in_current_session: new_node_dbg.then(|| {
1232                Lock::new(FxHashMap::with_capacity_and_hasher(
1233                    new_node_count_estimate,
1234                    Default::default(),
1235                ))
1236            }),
1237            total_read_count: AtomicU64::new(0),
1238            total_duplicate_read_count: AtomicU64::new(0),
1239        }
1240    }
1241
1242    #[cfg(debug_assertions)]
1243    fn record_edge(&self, dep_node_index: DepNodeIndex, key: DepNode, fingerprint: Fingerprint) {
1244        if let Some(forbidden_edge) = &self.forbidden_edge {
1245            forbidden_edge.index_to_node.lock().insert(dep_node_index, key);
1246        }
1247        let previous = *self.fingerprints.lock().get_or_insert_with(dep_node_index, || fingerprint);
1248        assert_eq!(previous, fingerprint, "Unstable fingerprints for {:?}", key);
1249    }
1250
1251    #[inline(always)]
1252    fn record_node(
1253        &self,
1254        dep_node_index: DepNodeIndex,
1255        key: DepNode,
1256        _current_fingerprint: Fingerprint,
1257    ) {
1258        #[cfg(debug_assertions)]
1259        self.record_edge(dep_node_index, key, _current_fingerprint);
1260
1261        if let Some(ref nodes_in_current_session) = self.nodes_in_current_session {
1262            outline(|| {
1263                if nodes_in_current_session.lock().insert(key, dep_node_index).is_some() {
1264                    panic!("Found duplicate dep-node {key:?}");
1265                }
1266            });
1267        }
1268    }
1269
1270    /// Writes the node to the current dep-graph and allocates a `DepNodeIndex` for it.
1271    /// Assumes that this is a node that has no equivalent in the previous dep-graph.
1272    #[inline(always)]
1273    fn alloc_new_node(
1274        &self,
1275        key: DepNode,
1276        edges: EdgesVec,
1277        current_fingerprint: Fingerprint,
1278    ) -> DepNodeIndex {
1279        let dep_node_index = self.encoder.send_new(key, current_fingerprint, edges);
1280
1281        self.record_node(dep_node_index, key, current_fingerprint);
1282
1283        dep_node_index
1284    }
1285
1286    #[inline]
1287    fn debug_assert_not_in_new_nodes(
1288        &self,
1289        prev_graph: &SerializedDepGraph,
1290        prev_index: SerializedDepNodeIndex,
1291    ) {
1292        if let Some(ref nodes_in_current_session) = self.nodes_in_current_session {
1293            debug_assert!(
1294                !nodes_in_current_session
1295                    .lock()
1296                    .contains_key(&prev_graph.index_to_node(prev_index)),
1297                "node from previous graph present in new node collection"
1298            );
1299        }
1300    }
1301}
1302
1303#[derive(Debug, Clone, Copy)]
1304pub enum TaskDepsRef<'a> {
1305    /// New dependencies can be added to the
1306    /// `TaskDeps`. This is used when executing a 'normal' query
1307    /// (no `eval_always` modifier)
1308    Allow(&'a Lock<TaskDeps>),
1309    /// This is used when executing an `eval_always` query. We don't
1310    /// need to track dependencies for a query that's always
1311    /// re-executed -- but we need to know that this is an `eval_always`
1312    /// query in order to emit dependencies to `DepNodeIndex::FOREVER_RED_NODE`
1313    /// when directly feeding other queries.
1314    EvalAlways,
1315    /// New dependencies are ignored. This is also used for `dep_graph.with_ignore`.
1316    Ignore,
1317    /// Any attempt to add new dependencies will cause a panic.
1318    /// This is used when decoding a query result from disk,
1319    /// to ensure that the decoding process doesn't itself
1320    /// require the execution of any queries.
1321    Forbid,
1322}
1323
1324#[derive(Debug)]
1325pub struct TaskDeps {
1326    #[cfg(debug_assertions)]
1327    node: Option<DepNode>,
1328    reads: EdgesVec,
1329    read_set: FxHashSet<DepNodeIndex>,
1330    phantom_data: PhantomData<DepNode>,
1331}
1332
1333impl Default for TaskDeps {
1334    fn default() -> Self {
1335        Self {
1336            #[cfg(debug_assertions)]
1337            node: None,
1338            reads: EdgesVec::new(),
1339            read_set: FxHashSet::with_capacity_and_hasher(128, Default::default()),
1340            phantom_data: PhantomData,
1341        }
1342    }
1343}
1344// A data structure that stores Option<DepNodeColor> values as a contiguous
1345// array, using one u32 per entry.
1346pub(super) struct DepNodeColorMap {
1347    values: IndexVec<SerializedDepNodeIndex, AtomicU32>,
1348}
1349
1350const COMPRESSED_NONE: u32 = u32::MAX;
1351const COMPRESSED_RED: u32 = u32::MAX - 1;
1352
1353impl DepNodeColorMap {
1354    fn new(size: usize) -> DepNodeColorMap {
1355        debug_assert!(COMPRESSED_RED > DepNodeIndex::MAX_AS_U32);
1356        DepNodeColorMap { values: (0..size).map(|_| AtomicU32::new(COMPRESSED_NONE)).collect() }
1357    }
1358
1359    #[inline]
1360    pub(super) fn current(&self, index: SerializedDepNodeIndex) -> Option<DepNodeIndex> {
1361        let value = self.values[index].load(Ordering::Relaxed);
1362        if value <= DepNodeIndex::MAX_AS_U32 { Some(DepNodeIndex::from_u32(value)) } else { None }
1363    }
1364
1365    #[inline]
1366    pub(super) fn get(&self, index: SerializedDepNodeIndex) -> Option<DepNodeColor> {
1367        match self.values[index].load(Ordering::Acquire) {
1368            COMPRESSED_NONE => None,
1369            COMPRESSED_RED => Some(DepNodeColor::Red),
1370            value => Some(DepNodeColor::Green(DepNodeIndex::from_u32(value))),
1371        }
1372    }
1373
1374    #[inline]
1375    pub(super) fn insert(&self, index: SerializedDepNodeIndex, color: DepNodeColor) {
1376        self.values[index].store(
1377            match color {
1378                DepNodeColor::Red => COMPRESSED_RED,
1379                DepNodeColor::Green(index) => index.as_u32(),
1380            },
1381            Ordering::Release,
1382        )
1383    }
1384}
1385
1386#[inline(never)]
1387#[cold]
1388pub(crate) fn print_markframe_trace<D: Deps>(graph: &DepGraph<D>, frame: Option<&MarkFrame<'_>>) {
1389    let data = graph.data.as_ref().unwrap();
1390
1391    eprintln!("there was a panic while trying to force a dep node");
1392    eprintln!("try_mark_green dep node stack:");
1393
1394    let mut i = 0;
1395    let mut current = frame;
1396    while let Some(frame) = current {
1397        let node = data.previous.index_to_node(frame.index);
1398        eprintln!("#{i} {node:?}");
1399        current = frame.parent;
1400        i += 1;
1401    }
1402
1403    eprintln!("end of try_mark_green dep node stack");
1404}
1405
1406#[cold]
1407#[inline(never)]
1408fn panic_on_forbidden_read<D: Deps>(data: &DepGraphData<D>, dep_node_index: DepNodeIndex) -> ! {
1409    // We have to do an expensive reverse-lookup of the DepNode that
1410    // corresponds to `dep_node_index`, but that's OK since we are about
1411    // to ICE anyway.
1412    let mut dep_node = None;
1413
1414    // First try to find the dep node among those that already existed in the
1415    // previous session and has been marked green
1416    for prev_index in data.colors.values.indices() {
1417        if data.colors.current(prev_index) == Some(dep_node_index) {
1418            dep_node = Some(data.previous.index_to_node(prev_index));
1419            break;
1420        }
1421    }
1422
1423    if dep_node.is_none()
1424        && let Some(nodes) = &data.current.nodes_in_current_session
1425    {
1426        // Try to find it among the nodes allocated so far in this session
1427        if let Some((node, _)) = nodes.lock().iter().find(|&(_, index)| *index == dep_node_index) {
1428            dep_node = Some(*node);
1429        }
1430    }
1431
1432    let dep_node = dep_node.map_or_else(
1433        || format!("with index {:?}", dep_node_index),
1434        |dep_node| format!("`{:?}`", dep_node),
1435    );
1436
1437    panic!(
1438        "Error: trying to record dependency on DepNode {dep_node} in a \
1439         context that does not allow it (e.g. during query deserialization). \
1440         The most common case of recording a dependency on a DepNode `foo` is \
1441         when the corresponding query `foo` is invoked. Invoking queries is not \
1442         allowed as part of loading something from the incremental on-disk cache. \
1443         See <https://github.com/rust-lang/rust/pull/91919>."
1444    )
1445}