1 use parking_lot::Mutex;
2 use rustc_data_structures::fingerprint::Fingerprint;
3 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
4 use rustc_data_structures::profiling::{EventId, QueryInvocationId, SelfProfilerRef};
5 use rustc_data_structures::sharded::{self, Sharded};
6 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
7 use rustc_data_structures::steal::Steal;
8 use rustc_data_structures::sync::{AtomicU32, AtomicU64, Lock, Lrc, Ordering};
9 use rustc_index::vec::IndexVec;
10 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
11 use smallvec::{smallvec, SmallVec};
12 use std::assert_matches::assert_matches;
13 use std::collections::hash_map::Entry;
16 use std::marker::PhantomData;
17 use std::sync::atomic::Ordering::Relaxed;
19 use super::query::DepGraphQuery;
20 use super::serialized::{GraphEncoder, SerializedDepGraph, SerializedDepNodeIndex};
21 use super::{DepContext, DepKind, DepNode, HasDepContext, WorkProductId};
22 use crate::ich::StableHashingContext;
23 use crate::query::{QueryContext, QuerySideEffects};
25 #[cfg(debug_assertions)]
26 use {super::debug::EdgeFilter, std::env};
29 pub struct DepGraph<K: DepKind> {
30 data: Option<Lrc<DepGraphData<K>>>,
32 /// This field is used for assigning DepNodeIndices when running in
33 /// non-incremental mode. Even in non-incremental mode we make sure that
34 /// each task has a `DepNodeIndex` that uniquely identifies it. This unique
35 /// ID is used for self-profiling.
36 virtual_dep_node_index: Lrc<AtomicU32>,
39 rustc_index::newtype_index! {
40 pub struct DepNodeIndex { .. }
44 pub const INVALID: DepNodeIndex = DepNodeIndex::MAX;
45 pub const SINGLETON_DEPENDENCYLESS_ANON_NODE: DepNodeIndex = DepNodeIndex::from_u32(0);
46 pub const FOREVER_RED_NODE: DepNodeIndex = DepNodeIndex::from_u32(1);
49 impl std::convert::From<DepNodeIndex> for QueryInvocationId {
51 fn from(dep_node_index: DepNodeIndex) -> Self {
52 QueryInvocationId(dep_node_index.as_u32())
57 pub enum DepNodeColor {
64 pub fn is_green(self) -> bool {
66 DepNodeColor::Red => false,
67 DepNodeColor::Green(_) => true,
72 struct DepGraphData<K: DepKind> {
73 /// The new encoding of the dependency graph, optimized for red/green
74 /// tracking. The `current` field is the dependency graph of only the
75 /// current compilation session: We don't merge the previous dep-graph into
76 /// current one anymore, but we do reference shared data to save space.
77 current: CurrentDepGraph<K>,
79 /// The dep-graph from the previous compilation session. It contains all
80 /// nodes and edges as well as all fingerprints of nodes that have them.
81 previous: SerializedDepGraph<K>,
83 colors: DepNodeColorMap,
85 processed_side_effects: Mutex<FxHashSet<DepNodeIndex>>,
87 /// When we load, there may be `.o` files, cached MIR, or other such
88 /// things available to us. If we find that they are not dirty, we
89 /// load the path to the file storing those work-products here into
90 /// this map. We can later look for and extract that data.
91 previous_work_products: FxHashMap<WorkProductId, WorkProduct>,
93 dep_node_debug: Lock<FxHashMap<DepNode<K>, String>>,
95 /// Used by incremental compilation tests to assert that
96 /// a particular query result was decoded from disk
97 /// (not just marked green)
98 debug_loaded_from_disk: Lock<FxHashSet<DepNode<K>>>,
101 pub fn hash_result<R>(hcx: &mut StableHashingContext<'_>, result: &R) -> Fingerprint
103 R: for<'a> HashStable<StableHashingContext<'a>>,
105 let mut stable_hasher = StableHasher::new();
106 result.hash_stable(hcx, &mut stable_hasher);
107 stable_hasher.finish()
110 impl<K: DepKind> DepGraph<K> {
112 profiler: &SelfProfilerRef,
113 prev_graph: SerializedDepGraph<K>,
114 prev_work_products: FxHashMap<WorkProductId, WorkProduct>,
115 encoder: FileEncoder,
119 let prev_graph_node_count = prev_graph.node_count();
121 let current = CurrentDepGraph::new(
123 prev_graph_node_count,
129 let colors = DepNodeColorMap::new(prev_graph_node_count);
131 // Instantiate a dependy-less node only once for anonymous queries.
132 let _green_node_index = current.intern_new_node(
134 DepNode { kind: DepKind::NULL, hash: current.anon_id_seed.into() },
138 assert_eq!(_green_node_index, DepNodeIndex::SINGLETON_DEPENDENCYLESS_ANON_NODE);
140 // Instantiate a dependy-less red node only once for anonymous queries.
141 let (_red_node_index, _prev_and_index) = current.intern_node(
144 DepNode { kind: DepKind::RED, hash: Fingerprint::ZERO.into() },
149 assert_eq!(_red_node_index, DepNodeIndex::FOREVER_RED_NODE);
150 assert!(matches!(_prev_and_index, None | Some((_, DepNodeColor::Red))));
153 data: Some(Lrc::new(DepGraphData {
154 previous_work_products: prev_work_products,
155 dep_node_debug: Default::default(),
157 processed_side_effects: Default::default(),
158 previous: prev_graph,
160 debug_loaded_from_disk: Default::default(),
162 virtual_dep_node_index: Lrc::new(AtomicU32::new(0)),
166 pub fn new_disabled() -> DepGraph<K> {
167 DepGraph { data: None, virtual_dep_node_index: Lrc::new(AtomicU32::new(0)) }
170 /// Returns `true` if we are actually building the full dep-graph, and `false` otherwise.
172 pub fn is_fully_enabled(&self) -> bool {
176 pub fn with_query(&self, f: impl Fn(&DepGraphQuery<K>)) {
177 if let Some(data) = &self.data {
178 data.current.encoder.borrow().with_query(f)
182 pub fn assert_ignored(&self) {
183 if let Some(..) = self.data {
184 K::read_deps(|task_deps| {
188 "expected no task dependency tracking"
194 pub fn with_ignore<OP, R>(&self, op: OP) -> R
198 K::with_deps(TaskDepsRef::Ignore, op)
201 /// Used to wrap the deserialization of a query result from disk,
202 /// This method enforces that no new `DepNodes` are created during
203 /// query result deserialization.
205 /// Enforcing this makes the query dep graph simpler - all nodes
206 /// must be created during the query execution, and should be
207 /// created from inside the 'body' of a query (the implementation
208 /// provided by a particular compiler crate).
210 /// Consider the case of three queries `A`, `B`, and `C`, where
211 /// `A` invokes `B` and `B` invokes `C`:
215 /// Suppose that decoding the result of query `B` required re-computing
216 /// the query `C`. If we did not create a fresh `TaskDeps` when
217 /// decoding `B`, we would still be using the `TaskDeps` for query `A`
218 /// (if we needed to re-execute `A`). This would cause us to create
219 /// a new edge `A -> C`. If this edge did not previously
220 /// exist in the `DepGraph`, then we could end up with a different
221 /// `DepGraph` at the end of compilation, even if there were no
222 /// meaningful changes to the overall program (e.g. a newline was added).
223 /// In addition, this edge might cause a subsequent compilation run
224 /// to try to force `C` before marking other necessary nodes green. If
225 /// `C` did not exist in the new compilation session, then we could
226 /// get an ICE. Normally, we would have tried (and failed) to mark
227 /// some other query green (e.g. `item_children`) which was used
228 /// to obtain `C`, which would prevent us from ever trying to force
229 /// a non-existent `D`.
231 /// It might be possible to enforce that all `DepNode`s read during
232 /// deserialization already exist in the previous `DepGraph`. In
233 /// the above example, we would invoke `D` during the deserialization
234 /// of `B`. Since we correctly create a new `TaskDeps` from the decoding
235 /// of `B`, this would result in an edge `B -> D`. If that edge already
236 /// existed (with the same `DepPathHash`es), then it should be correct
237 /// to allow the invocation of the query to proceed during deserialization
238 /// of a query result. We would merely assert that the dep-graph fragment
239 /// that would have been added by invoking `C` while decoding `B`
240 /// is equivalent to the dep-graph fragment that we already instantiated for B
241 /// (at the point where we successfully marked B as green).
243 /// However, this would require additional complexity
244 /// in the query infrastructure, and is not currently needed by the
245 /// decoding of any query results. Should the need arise in the future,
246 /// we should consider extending the query system with this functionality.
247 pub fn with_query_deserialization<OP, R>(&self, op: OP) -> R
251 K::with_deps(TaskDepsRef::Forbid, op)
254 /// Starts a new dep-graph task. Dep-graph tasks are specified
255 /// using a free function (`task`) and **not** a closure -- this
256 /// is intentional because we want to exercise tight control over
257 /// what state they have access to. In particular, we want to
258 /// prevent implicit 'leaks' of tracked state into the task (which
259 /// could then be read without generating correct edges in the
260 /// dep-graph -- see the [rustc dev guide] for more details on
261 /// the dep-graph). To this end, the task function gets exactly two
262 /// pieces of state: the context `cx` and an argument `arg`. Both
263 /// of these bits of state must be of some type that implements
264 /// `DepGraphSafe` and hence does not leak.
266 /// The choice of two arguments is not fundamental. One argument
267 /// would work just as well, since multiple values can be
268 /// collected using tuples. However, using two arguments works out
269 /// to be quite convenient, since it is common to need a context
270 /// (`cx`) and some argument (e.g., a `DefId` identifying what
271 /// item to process).
273 /// For cases where you need some other number of arguments:
275 /// - If you only need one argument, just use `()` for the `arg`
277 /// - If you need 3+ arguments, use a tuple for the
280 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/incremental-compilation.html
281 pub fn with_task<Ctxt: HasDepContext<DepKind = K>, A: Debug, R>(
286 task: fn(Ctxt, A) -> R,
287 hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
288 ) -> (R, DepNodeIndex) {
289 if self.is_fully_enabled() {
290 self.with_task_impl(key, cx, arg, task, hash_result)
292 // Incremental compilation is turned off. We just execute the task
293 // without tracking. We still provide a dep-node index that uniquely
294 // identifies the task so that we have a cheap way of referring to
295 // the query for self-profiling.
296 (task(cx, arg), self.next_virtual_depnode_index())
300 fn with_task_impl<Ctxt: HasDepContext<DepKind = K>, A: Debug, R>(
305 task: fn(Ctxt, A) -> R,
306 hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
307 ) -> (R, DepNodeIndex) {
308 // This function is only called when the graph is enabled.
309 let data = self.data.as_ref().unwrap();
311 // If the following assertion triggers, it can have two reasons:
312 // 1. Something is wrong with DepNode creation, either here or
313 // in `DepGraph::try_mark_green()`.
314 // 2. Two distinct query keys get mapped to the same `DepNode`
315 // (see for example #48923).
317 !self.dep_node_exists(&key),
318 "forcing query with already existing `DepNode`\n\
325 let task_deps = if cx.dep_context().is_eval_always(key.kind) {
328 Some(Lock::new(TaskDeps {
329 #[cfg(debug_assertions)]
331 reads: SmallVec::new(),
332 read_set: Default::default(),
333 phantom_data: PhantomData,
337 let task_deps_ref = match &task_deps {
338 Some(deps) => TaskDepsRef::Allow(deps),
339 None => TaskDepsRef::Ignore,
342 let result = K::with_deps(task_deps_ref, || task(cx, arg));
343 let edges = task_deps.map_or_else(|| smallvec![], |lock| lock.into_inner().reads);
345 let dcx = cx.dep_context();
346 let hashing_timer = dcx.profiler().incr_result_hashing();
347 let current_fingerprint =
348 hash_result.map(|f| dcx.with_stable_hashing_context(|mut hcx| f(&mut hcx, &result)));
350 let print_status = cfg!(debug_assertions) && dcx.sess().opts.unstable_opts.dep_tasks;
352 // Intern the new `DepNode`.
353 let (dep_node_index, prev_and_color) = data.current.intern_node(
362 hashing_timer.finish_with_query_invocation_id(dep_node_index.into());
364 if let Some((prev_index, color)) = prev_and_color {
366 data.colors.get(prev_index).is_none(),
367 "DepGraph::with_task() - Duplicate DepNodeColor \
372 data.colors.insert(prev_index, color);
375 (result, dep_node_index)
378 /// Executes something within an "anonymous" task, that is, a task the
379 /// `DepNode` of which is determined by the list of inputs it read from.
380 pub fn with_anon_task<Ctxt: DepContext<DepKind = K>, OP, R>(
385 ) -> (R, DepNodeIndex)
389 debug_assert!(!cx.is_eval_always(dep_kind));
391 if let Some(ref data) = self.data {
392 let task_deps = Lock::new(TaskDeps::default());
393 let result = K::with_deps(TaskDepsRef::Allow(&task_deps), op);
394 let task_deps = task_deps.into_inner();
395 let task_deps = task_deps.reads;
397 let dep_node_index = match task_deps.len() {
399 // Because the dep-node id of anon nodes is computed from the sets of its
400 // dependencies we already know what the ID of this dependency-less node is
401 // going to be (i.e. equal to the precomputed
402 // `SINGLETON_DEPENDENCYLESS_ANON_NODE`). As a consequence we can skip creating
403 // a `StableHasher` and sending the node through interning.
404 DepNodeIndex::SINGLETON_DEPENDENCYLESS_ANON_NODE
407 // When there is only one dependency, don't bother creating a node.
411 // The dep node indices are hashed here instead of hashing the dep nodes of the
412 // dependencies. These indices may refer to different nodes per session, but this isn't
413 // a problem here because we that ensure the final dep node hash is per session only by
414 // combining it with the per session random number `anon_id_seed`. This hash only need
415 // to map the dependencies to a single value on a per session basis.
416 let mut hasher = StableHasher::new();
417 task_deps.hash(&mut hasher);
419 let target_dep_node = DepNode {
421 // Fingerprint::combine() is faster than sending Fingerprint
422 // through the StableHasher (at least as long as StableHasher
424 hash: data.current.anon_id_seed.combine(hasher.finish()).into(),
427 data.current.intern_new_node(
436 (result, dep_node_index)
438 (op(), self.next_virtual_depnode_index())
443 pub fn read_index(&self, dep_node_index: DepNodeIndex) {
444 if let Some(ref data) = self.data {
445 K::read_deps(|task_deps| {
446 let mut task_deps = match task_deps {
447 TaskDepsRef::Allow(deps) => deps.lock(),
448 TaskDepsRef::Ignore => return,
449 TaskDepsRef::Forbid => {
450 panic!("Illegal read of: {:?}", dep_node_index)
453 let task_deps = &mut *task_deps;
455 if cfg!(debug_assertions) {
456 data.current.total_read_count.fetch_add(1, Relaxed);
459 // As long as we only have a low number of reads we can avoid doing a hash
460 // insert and potentially allocating/reallocating the hashmap
461 let new_read = if task_deps.reads.len() < TASK_DEPS_READS_CAP {
462 task_deps.reads.iter().all(|other| *other != dep_node_index)
464 task_deps.read_set.insert(dep_node_index)
467 task_deps.reads.push(dep_node_index);
468 if task_deps.reads.len() == TASK_DEPS_READS_CAP {
469 // Fill `read_set` with what we have so far so we can use the hashset
471 task_deps.read_set.extend(task_deps.reads.iter().copied());
474 #[cfg(debug_assertions)]
476 if let Some(target) = task_deps.node {
477 if let Some(ref forbidden_edge) = data.current.forbidden_edge {
478 let src = forbidden_edge.index_to_node.lock()[&dep_node_index];
479 if forbidden_edge.test(&src, &target) {
480 panic!("forbidden edge {:?} -> {:?} created", src, target)
485 } else if cfg!(debug_assertions) {
486 data.current.total_duplicate_read_count.fetch_add(1, Relaxed);
493 pub fn dep_node_index_of(&self, dep_node: &DepNode<K>) -> DepNodeIndex {
494 self.dep_node_index_of_opt(dep_node).unwrap()
498 pub fn dep_node_index_of_opt(&self, dep_node: &DepNode<K>) -> Option<DepNodeIndex> {
499 let data = self.data.as_ref().unwrap();
500 let current = &data.current;
502 if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
503 current.prev_index_to_index.lock()[prev_index]
505 current.new_node_to_index.get_shard_by_value(dep_node).lock().get(dep_node).copied()
510 pub fn dep_node_exists(&self, dep_node: &DepNode<K>) -> bool {
511 self.data.is_some() && self.dep_node_index_of_opt(dep_node).is_some()
514 pub fn prev_fingerprint_of(&self, dep_node: &DepNode<K>) -> Option<Fingerprint> {
515 self.data.as_ref().unwrap().previous.fingerprint_of(dep_node)
518 /// Checks whether a previous work product exists for `v` and, if
519 /// so, return the path that leads to it. Used to skip doing work.
520 pub fn previous_work_product(&self, v: &WorkProductId) -> Option<WorkProduct> {
521 self.data.as_ref().and_then(|data| data.previous_work_products.get(v).cloned())
524 /// Access the map of work-products created during the cached run. Only
525 /// used during saving of the dep-graph.
526 pub fn previous_work_products(&self) -> &FxHashMap<WorkProductId, WorkProduct> {
527 &self.data.as_ref().unwrap().previous_work_products
530 pub fn mark_debug_loaded_from_disk(&self, dep_node: DepNode<K>) {
531 self.data.as_ref().unwrap().debug_loaded_from_disk.lock().insert(dep_node);
534 pub fn debug_was_loaded_from_disk(&self, dep_node: DepNode<K>) -> bool {
535 self.data.as_ref().unwrap().debug_loaded_from_disk.lock().contains(&dep_node)
539 pub fn register_dep_node_debug_str<F>(&self, dep_node: DepNode<K>, debug_str_gen: F)
541 F: FnOnce() -> String,
543 let dep_node_debug = &self.data.as_ref().unwrap().dep_node_debug;
545 if dep_node_debug.borrow().contains_key(&dep_node) {
548 let debug_str = debug_str_gen();
549 dep_node_debug.borrow_mut().insert(dep_node, debug_str);
552 pub fn dep_node_debug_str(&self, dep_node: DepNode<K>) -> Option<String> {
553 self.data.as_ref()?.dep_node_debug.borrow().get(&dep_node).cloned()
556 fn node_color(&self, dep_node: &DepNode<K>) -> Option<DepNodeColor> {
557 if let Some(ref data) = self.data {
558 if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
559 return data.colors.get(prev_index);
561 // This is a node that did not exist in the previous compilation session.
569 /// Try to mark a node index for the node dep_node.
571 /// A node will have an index, when it's already been marked green, or when we can mark it
572 /// green. This function will mark the current task as a reader of the specified node, when
573 /// a node index can be found for that node.
574 pub fn try_mark_green<Ctxt: QueryContext<DepKind = K>>(
577 dep_node: &DepNode<K>,
578 ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
579 debug_assert!(!tcx.dep_context().is_eval_always(dep_node.kind));
581 // Return None if the dep graph is disabled
582 let data = self.data.as_ref()?;
584 // Return None if the dep node didn't exist in the previous session
585 let prev_index = data.previous.node_to_index_opt(dep_node)?;
587 match data.colors.get(prev_index) {
588 Some(DepNodeColor::Green(dep_node_index)) => Some((prev_index, dep_node_index)),
589 Some(DepNodeColor::Red) => None,
591 // This DepNode and the corresponding query invocation existed
592 // in the previous compilation session too, so we can try to
593 // mark it as green by recursively marking all of its
594 // dependencies green.
595 self.try_mark_previous_green(tcx, data, prev_index, &dep_node)
596 .map(|dep_node_index| (prev_index, dep_node_index))
601 fn try_mark_parent_green<Ctxt: QueryContext<DepKind = K>>(
604 data: &DepGraphData<K>,
605 parent_dep_node_index: SerializedDepNodeIndex,
606 dep_node: &DepNode<K>,
608 let dep_dep_node_color = data.colors.get(parent_dep_node_index);
609 let dep_dep_node = &data.previous.index_to_node(parent_dep_node_index);
611 match dep_dep_node_color {
612 Some(DepNodeColor::Green(_)) => {
613 // This dependency has been marked as green before, we are
614 // still fine and can continue with checking the other
617 "try_mark_previous_green({:?}) --- found dependency {:?} to \
618 be immediately green",
619 dep_node, dep_dep_node,
623 Some(DepNodeColor::Red) => {
624 // We found a dependency the value of which has changed
625 // compared to the previous compilation session. We cannot
626 // mark the DepNode as green and also don't need to bother
627 // with checking any of the other dependencies.
629 "try_mark_previous_green({:?}) - END - dependency {:?} was immediately red",
630 dep_node, dep_dep_node,
637 // We don't know the state of this dependency. If it isn't
638 // an eval_always node, let's try to mark it green recursively.
639 if !tcx.dep_context().is_eval_always(dep_dep_node.kind) {
641 "try_mark_previous_green({:?}) --- state of dependency {:?} ({}) \
642 is unknown, trying to mark it green",
643 dep_node, dep_dep_node, dep_dep_node.hash,
647 self.try_mark_previous_green(tcx, data, parent_dep_node_index, dep_dep_node);
648 if node_index.is_some() {
650 "try_mark_previous_green({:?}) --- managed to MARK dependency {:?} as green",
651 dep_node, dep_dep_node
657 // We failed to mark it green, so we try to force the query.
659 "try_mark_previous_green({:?}) --- trying to force dependency {:?}",
660 dep_node, dep_dep_node
662 if !tcx.dep_context().try_force_from_dep_node(*dep_dep_node) {
663 // The DepNode could not be forced.
665 "try_mark_previous_green({:?}) - END - dependency {:?} could not be forced",
666 dep_node, dep_dep_node
671 let dep_dep_node_color = data.colors.get(parent_dep_node_index);
673 match dep_dep_node_color {
674 Some(DepNodeColor::Green(_)) => {
676 "try_mark_previous_green({:?}) --- managed to FORCE dependency {:?} to green",
677 dep_node, dep_dep_node
681 Some(DepNodeColor::Red) => {
683 "try_mark_previous_green({:?}) - END - dependency {:?} was red after forcing",
684 dep_node, dep_dep_node
691 if !tcx.dep_context().sess().has_errors_or_delayed_span_bugs() {
692 panic!("try_mark_previous_green() - Forcing the DepNode should have set its color")
695 // If the query we just forced has resulted in
696 // some kind of compilation error, we cannot rely on
697 // the dep-node color having been properly updated.
698 // This means that the query system has reached an
699 // invalid state. We let the compiler continue (by
700 // returning `None`) so it can emit error messages
701 // and wind down, but rely on the fact that this
702 // invalid state will not be persisted to the
703 // incremental compilation cache because of
704 // compilation errors being present.
706 "try_mark_previous_green({:?}) - END - dependency {:?} resulted in compilation error",
707 dep_node, dep_dep_node
712 /// Try to mark a dep-node which existed in the previous compilation session as green.
713 fn try_mark_previous_green<Ctxt: QueryContext<DepKind = K>>(
716 data: &DepGraphData<K>,
717 prev_dep_node_index: SerializedDepNodeIndex,
718 dep_node: &DepNode<K>,
719 ) -> Option<DepNodeIndex> {
720 debug!("try_mark_previous_green({:?}) - BEGIN", dep_node);
722 #[cfg(not(parallel_compiler))]
724 debug_assert!(!self.dep_node_exists(dep_node));
725 debug_assert!(data.colors.get(prev_dep_node_index).is_none());
728 // We never try to mark eval_always nodes as green
729 debug_assert!(!tcx.dep_context().is_eval_always(dep_node.kind));
731 debug_assert_eq!(data.previous.index_to_node(prev_dep_node_index), *dep_node);
733 let prev_deps = data.previous.edge_targets_from(prev_dep_node_index);
735 for &dep_dep_node_index in prev_deps {
736 self.try_mark_parent_green(tcx, data, dep_dep_node_index, dep_node)?
739 // If we got here without hitting a `return` that means that all
740 // dependencies of this DepNode could be marked as green. Therefore we
741 // can also mark this DepNode as green.
743 // There may be multiple threads trying to mark the same dep node green concurrently
745 // We allocating an entry for the node in the current dependency graph and
746 // adding all the appropriate edges imported from the previous graph
747 let dep_node_index = data.current.promote_node_and_deps_to_current(
748 tcx.dep_context().profiler(),
753 // ... emitting any stored diagnostic ...
755 // FIXME: Store the fact that a node has diagnostics in a bit in the dep graph somewhere
756 // Maybe store a list on disk and encode this fact in the DepNodeState
757 let side_effects = tcx.load_side_effects(prev_dep_node_index);
759 #[cfg(not(parallel_compiler))]
761 data.colors.get(prev_dep_node_index).is_none(),
762 "DepGraph::try_mark_previous_green() - Duplicate DepNodeColor \
767 if !side_effects.is_empty() {
768 self.emit_side_effects(tcx, data, dep_node_index, side_effects);
771 // ... and finally storing a "Green" entry in the color map.
772 // Multiple threads can all write the same color here
773 data.colors.insert(prev_dep_node_index, DepNodeColor::Green(dep_node_index));
775 debug!("try_mark_previous_green({:?}) - END - successfully marked as green", dep_node);
779 /// Atomically emits some loaded diagnostics.
780 /// This may be called concurrently on multiple threads for the same dep node.
783 fn emit_side_effects<Ctxt: QueryContext<DepKind = K>>(
786 data: &DepGraphData<K>,
787 dep_node_index: DepNodeIndex,
788 side_effects: QuerySideEffects,
790 let mut processed = data.processed_side_effects.lock();
792 if processed.insert(dep_node_index) {
793 // We were the first to insert the node in the set so this thread
794 // must process side effects
796 // Promote the previous diagnostics to the current session.
797 tcx.store_side_effects(dep_node_index, side_effects.clone());
799 let handle = tcx.dep_context().sess().diagnostic();
801 for mut diagnostic in side_effects.diagnostics {
802 handle.emit_diagnostic(&mut diagnostic);
807 // Returns true if the given node has been marked as red during the
808 // current compilation session. Used in various assertions
809 pub fn is_red(&self, dep_node: &DepNode<K>) -> bool {
810 self.node_color(dep_node) == Some(DepNodeColor::Red)
813 // Returns true if the given node has been marked as green during the
814 // current compilation session. Used in various assertions
815 pub fn is_green(&self, dep_node: &DepNode<K>) -> bool {
816 self.node_color(dep_node).map_or(false, |c| c.is_green())
819 // This method loads all on-disk cacheable query results into memory, so
820 // they can be written out to the new cache file again. Most query results
821 // will already be in memory but in the case where we marked something as
822 // green but then did not need the value, that value will never have been
825 // This method will only load queries that will end up in the disk cache.
826 // Other queries will not be executed.
827 pub fn exec_cache_promotions<Ctxt: DepContext<DepKind = K>>(&self, tcx: Ctxt) {
828 let _prof_timer = tcx.profiler().generic_activity("incr_comp_query_cache_promotion");
830 let data = self.data.as_ref().unwrap();
831 for prev_index in data.colors.values.indices() {
832 match data.colors.get(prev_index) {
833 Some(DepNodeColor::Green(_)) => {
834 let dep_node = data.previous.index_to_node(prev_index);
835 tcx.try_load_from_on_disk_cache(dep_node);
837 None | Some(DepNodeColor::Red) => {
838 // We can skip red nodes because a node can only be marked
839 // as red if the query result was recomputed and thus is
840 // already in memory.
846 pub fn print_incremental_info(&self) {
847 if let Some(data) = &self.data {
848 data.current.encoder.borrow().print_incremental_info(
849 data.current.total_read_count.load(Relaxed),
850 data.current.total_duplicate_read_count.load(Relaxed),
855 pub fn encode(&self, profiler: &SelfProfilerRef) -> FileEncodeResult {
856 if let Some(data) = &self.data {
857 data.current.encoder.steal().finish(profiler)
863 pub(crate) fn next_virtual_depnode_index(&self) -> DepNodeIndex {
864 let index = self.virtual_dep_node_index.fetch_add(1, Relaxed);
865 DepNodeIndex::from_u32(index)
869 /// A "work product" is an intermediate result that we save into the
870 /// incremental directory for later re-use. The primary example are
871 /// the object files that we save for each partition at code
874 /// Each work product is associated with a dep-node, representing the
875 /// process that produced the work-product. If that dep-node is found
876 /// to be dirty when we load up, then we will delete the work-product
877 /// at load time. If the work-product is found to be clean, then we
878 /// will keep a record in the `previous_work_products` list.
880 /// In addition, work products have an associated hash. This hash is
881 /// an extra hash that can be used to decide if the work-product from
882 /// a previous compilation can be re-used (in addition to the dirty
885 /// As the primary example, consider the object files we generate for
886 /// each partition. In the first run, we create partitions based on
887 /// the symbols that need to be compiled. For each partition P, we
888 /// hash the symbols in P and create a `WorkProduct` record associated
889 /// with `DepNode::CodegenUnit(P)`; the hash is the set of symbols
892 /// The next time we compile, if the `DepNode::CodegenUnit(P)` is
893 /// judged to be clean (which means none of the things we read to
894 /// generate the partition were found to be dirty), it will be loaded
895 /// into previous work products. We will then regenerate the set of
896 /// symbols in the partition P and hash them (note that new symbols
897 /// may be added -- for example, new monomorphizations -- even if
898 /// nothing in P changed!). We will compare that hash against the
899 /// previous hash. If it matches up, we can reuse the object file.
900 #[derive(Clone, Debug, Encodable, Decodable)]
901 pub struct WorkProduct {
902 pub cgu_name: String,
903 /// Saved files associated with this CGU. In each key/value pair, the value is the path to the
904 /// saved file and the key is some identifier for the type of file being saved.
906 /// By convention, file extensions are currently used as identifiers, i.e. the key "o" maps to
907 /// the object file's path, and "dwo" to the dwarf object file's path.
908 pub saved_files: FxHashMap<String, String>,
911 // Index type for `DepNodeData`'s edges.
912 rustc_index::newtype_index! {
913 struct EdgeIndex { .. }
916 /// `CurrentDepGraph` stores the dependency graph for the current session. It
917 /// will be populated as we run queries or tasks. We never remove nodes from the
918 /// graph: they are only added.
920 /// The nodes in it are identified by a `DepNodeIndex`. We avoid keeping the nodes
921 /// in memory. This is important, because these graph structures are some of the
922 /// largest in the compiler.
924 /// For this reason, we avoid storing `DepNode`s more than once as map
925 /// keys. The `new_node_to_index` map only contains nodes not in the previous
926 /// graph, and we map nodes in the previous graph to indices via a two-step
927 /// mapping. `SerializedDepGraph` maps from `DepNode` to `SerializedDepNodeIndex`,
928 /// and the `prev_index_to_index` vector (which is more compact and faster than
929 /// using a map) maps from `SerializedDepNodeIndex` to `DepNodeIndex`.
931 /// This struct uses three locks internally. The `data`, `new_node_to_index`,
932 /// and `prev_index_to_index` fields are locked separately. Operations that take
933 /// a `DepNodeIndex` typically just access the `data` field.
935 /// We only need to manipulate at most two locks simultaneously:
936 /// `new_node_to_index` and `data`, or `prev_index_to_index` and `data`. When
937 /// manipulating both, we acquire `new_node_to_index` or `prev_index_to_index`
938 /// first, and `data` second.
939 pub(super) struct CurrentDepGraph<K: DepKind> {
940 encoder: Steal<GraphEncoder<K>>,
941 new_node_to_index: Sharded<FxHashMap<DepNode<K>, DepNodeIndex>>,
942 prev_index_to_index: Lock<IndexVec<SerializedDepNodeIndex, Option<DepNodeIndex>>>,
944 /// Used to trap when a specific edge is added to the graph.
945 /// This is used for debug purposes and is only active with `debug_assertions`.
946 #[cfg(debug_assertions)]
947 forbidden_edge: Option<EdgeFilter<K>>,
949 /// Anonymous `DepNode`s are nodes whose IDs we compute from the list of
950 /// their edges. This has the beneficial side-effect that multiple anonymous
951 /// nodes can be coalesced into one without changing the semantics of the
952 /// dependency graph. However, the merging of nodes can lead to a subtle
953 /// problem during red-green marking: The color of an anonymous node from
954 /// the current session might "shadow" the color of the node with the same
955 /// ID from the previous session. In order to side-step this problem, we make
956 /// sure that anonymous `NodeId`s allocated in different sessions don't overlap.
957 /// This is implemented by mixing a session-key into the ID fingerprint of
958 /// each anon node. The session-key is just a random number generated when
959 /// the `DepGraph` is created.
960 anon_id_seed: Fingerprint,
962 /// These are simple counters that are for profiling and
963 /// debugging and only active with `debug_assertions`.
964 total_read_count: AtomicU64,
965 total_duplicate_read_count: AtomicU64,
967 /// The cached event id for profiling node interning. This saves us
968 /// from having to look up the event id every time we intern a node
969 /// which may incur too much overhead.
970 /// This will be None if self-profiling is disabled.
971 node_intern_event_id: Option<EventId>,
974 impl<K: DepKind> CurrentDepGraph<K> {
976 profiler: &SelfProfilerRef,
977 prev_graph_node_count: usize,
978 encoder: FileEncoder,
981 ) -> CurrentDepGraph<K> {
982 use std::time::{SystemTime, UNIX_EPOCH};
984 let duration = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
985 let nanos = duration.as_secs() * 1_000_000_000 + duration.subsec_nanos() as u64;
986 let mut stable_hasher = StableHasher::new();
987 nanos.hash(&mut stable_hasher);
988 let anon_id_seed = stable_hasher.finish();
990 #[cfg(debug_assertions)]
991 let forbidden_edge = match env::var("RUST_FORBID_DEP_GRAPH_EDGE") {
992 Ok(s) => match EdgeFilter::new(&s) {
994 Err(err) => panic!("RUST_FORBID_DEP_GRAPH_EDGE invalid: {}", err),
999 // We store a large collection of these in `prev_index_to_index` during
1000 // non-full incremental builds, and want to ensure that the element size
1001 // doesn't inadvertently increase.
1002 static_assert_size!(Option<DepNodeIndex>, 4);
1004 let new_node_count_estimate = 102 * prev_graph_node_count / 100 + 200;
1006 let node_intern_event_id = profiler
1007 .get_or_alloc_cached_string("incr_comp_intern_dep_graph_node")
1008 .map(EventId::from_label);
1011 encoder: Steal::new(GraphEncoder::new(
1013 prev_graph_node_count,
1017 new_node_to_index: Sharded::new(|| {
1018 FxHashMap::with_capacity_and_hasher(
1019 new_node_count_estimate / sharded::SHARDS,
1023 prev_index_to_index: Lock::new(IndexVec::from_elem_n(None, prev_graph_node_count)),
1025 #[cfg(debug_assertions)]
1027 total_read_count: AtomicU64::new(0),
1028 total_duplicate_read_count: AtomicU64::new(0),
1029 node_intern_event_id,
1033 #[cfg(debug_assertions)]
1034 fn record_edge(&self, dep_node_index: DepNodeIndex, key: DepNode<K>) {
1035 if let Some(forbidden_edge) = &self.forbidden_edge {
1036 forbidden_edge.index_to_node.lock().insert(dep_node_index, key);
1040 /// Writes the node to the current dep-graph and allocates a `DepNodeIndex` for it.
1041 /// Assumes that this is a node that has no equivalent in the previous dep-graph.
1044 profiler: &SelfProfilerRef,
1047 current_fingerprint: Fingerprint,
1049 match self.new_node_to_index.get_shard_by_value(&key).lock().entry(key) {
1050 Entry::Occupied(entry) => *entry.get(),
1051 Entry::Vacant(entry) => {
1052 let dep_node_index =
1053 self.encoder.borrow().send(profiler, key, current_fingerprint, edges);
1054 entry.insert(dep_node_index);
1055 #[cfg(debug_assertions)]
1056 self.record_edge(dep_node_index, key);
1064 profiler: &SelfProfilerRef,
1065 prev_graph: &SerializedDepGraph<K>,
1068 fingerprint: Option<Fingerprint>,
1070 ) -> (DepNodeIndex, Option<(SerializedDepNodeIndex, DepNodeColor)>) {
1071 let print_status = cfg!(debug_assertions) && print_status;
1073 // Get timer for profiling `DepNode` interning
1074 let _node_intern_timer =
1075 self.node_intern_event_id.map(|eid| profiler.generic_activity_with_event_id(eid));
1077 if let Some(prev_index) = prev_graph.node_to_index_opt(&key) {
1078 // Determine the color and index of the new `DepNode`.
1079 if let Some(fingerprint) = fingerprint {
1080 if fingerprint == prev_graph.fingerprint_by_index(prev_index) {
1082 eprintln!("[task::green] {:?}", key);
1085 // This is a green node: it existed in the previous compilation,
1086 // its query was re-executed, and it has the same result as before.
1087 let mut prev_index_to_index = self.prev_index_to_index.lock();
1089 let dep_node_index = match prev_index_to_index[prev_index] {
1090 Some(dep_node_index) => dep_node_index,
1092 let dep_node_index =
1093 self.encoder.borrow().send(profiler, key, fingerprint, edges);
1094 prev_index_to_index[prev_index] = Some(dep_node_index);
1099 #[cfg(debug_assertions)]
1100 self.record_edge(dep_node_index, key);
1101 (dep_node_index, Some((prev_index, DepNodeColor::Green(dep_node_index))))
1104 eprintln!("[task::red] {:?}", key);
1107 // This is a red node: it existed in the previous compilation, its query
1108 // was re-executed, but it has a different result from before.
1109 let mut prev_index_to_index = self.prev_index_to_index.lock();
1111 let dep_node_index = match prev_index_to_index[prev_index] {
1112 Some(dep_node_index) => dep_node_index,
1114 let dep_node_index =
1115 self.encoder.borrow().send(profiler, key, fingerprint, edges);
1116 prev_index_to_index[prev_index] = Some(dep_node_index);
1121 #[cfg(debug_assertions)]
1122 self.record_edge(dep_node_index, key);
1123 (dep_node_index, Some((prev_index, DepNodeColor::Red)))
1127 eprintln!("[task::unknown] {:?}", key);
1130 // This is a red node, effectively: it existed in the previous compilation
1131 // session, its query was re-executed, but it doesn't compute a result hash
1132 // (i.e. it represents a `no_hash` query), so we have no way of determining
1133 // whether or not the result was the same as before.
1134 let mut prev_index_to_index = self.prev_index_to_index.lock();
1136 let dep_node_index = match prev_index_to_index[prev_index] {
1137 Some(dep_node_index) => dep_node_index,
1139 let dep_node_index =
1140 self.encoder.borrow().send(profiler, key, Fingerprint::ZERO, edges);
1141 prev_index_to_index[prev_index] = Some(dep_node_index);
1146 #[cfg(debug_assertions)]
1147 self.record_edge(dep_node_index, key);
1148 (dep_node_index, Some((prev_index, DepNodeColor::Red)))
1152 eprintln!("[task::new] {:?}", key);
1155 let fingerprint = fingerprint.unwrap_or(Fingerprint::ZERO);
1157 // This is a new node: it didn't exist in the previous compilation session.
1158 let dep_node_index = self.intern_new_node(profiler, key, edges, fingerprint);
1160 (dep_node_index, None)
1164 fn promote_node_and_deps_to_current(
1166 profiler: &SelfProfilerRef,
1167 prev_graph: &SerializedDepGraph<K>,
1168 prev_index: SerializedDepNodeIndex,
1170 self.debug_assert_not_in_new_nodes(prev_graph, prev_index);
1172 let mut prev_index_to_index = self.prev_index_to_index.lock();
1174 match prev_index_to_index[prev_index] {
1175 Some(dep_node_index) => dep_node_index,
1177 let key = prev_graph.index_to_node(prev_index);
1178 let dep_node_index = self.encoder.borrow().send(
1181 prev_graph.fingerprint_by_index(prev_index),
1183 .edge_targets_from(prev_index)
1185 .map(|i| prev_index_to_index[*i].unwrap())
1188 prev_index_to_index[prev_index] = Some(dep_node_index);
1189 #[cfg(debug_assertions)]
1190 self.record_edge(dep_node_index, key);
1197 fn debug_assert_not_in_new_nodes(
1199 prev_graph: &SerializedDepGraph<K>,
1200 prev_index: SerializedDepNodeIndex,
1202 let node = &prev_graph.index_to_node(prev_index);
1204 !self.new_node_to_index.get_shard_by_value(node).lock().contains_key(node),
1205 "node from previous graph present in new node collection"
1210 /// The capacity of the `reads` field `SmallVec`
1211 const TASK_DEPS_READS_CAP: usize = 8;
1212 type EdgesVec = SmallVec<[DepNodeIndex; TASK_DEPS_READS_CAP]>;
1214 #[derive(Debug, Clone, Copy)]
1215 pub enum TaskDepsRef<'a, K: DepKind> {
1216 /// New dependencies can be added to the
1217 /// `TaskDeps`. This is used when executing a 'normal' query
1218 /// (no `eval_always` modifier)
1219 Allow(&'a Lock<TaskDeps<K>>),
1220 /// New dependencies are ignored. This is used when
1221 /// executing an `eval_always` query, since there's no
1222 /// need to track dependencies for a query that's always
1223 /// re-executed. This is also used for `dep_graph.with_ignore`
1225 /// Any attempt to add new dependencies will cause a panic.
1226 /// This is used when decoding a query result from disk,
1227 /// to ensure that the decoding process doesn't itself
1228 /// require the execution of any queries.
1233 pub struct TaskDeps<K: DepKind> {
1234 #[cfg(debug_assertions)]
1235 node: Option<DepNode<K>>,
1237 read_set: FxHashSet<DepNodeIndex>,
1238 phantom_data: PhantomData<DepNode<K>>,
1241 impl<K: DepKind> Default for TaskDeps<K> {
1242 fn default() -> Self {
1244 #[cfg(debug_assertions)]
1246 reads: EdgesVec::new(),
1247 read_set: FxHashSet::default(),
1248 phantom_data: PhantomData,
1253 // A data structure that stores Option<DepNodeColor> values as a contiguous
1254 // array, using one u32 per entry.
1255 struct DepNodeColorMap {
1256 values: IndexVec<SerializedDepNodeIndex, AtomicU32>,
1259 const COMPRESSED_NONE: u32 = 0;
1260 const COMPRESSED_RED: u32 = 1;
1261 const COMPRESSED_FIRST_GREEN: u32 = 2;
1263 impl DepNodeColorMap {
1264 fn new(size: usize) -> DepNodeColorMap {
1265 DepNodeColorMap { values: (0..size).map(|_| AtomicU32::new(COMPRESSED_NONE)).collect() }
1269 fn get(&self, index: SerializedDepNodeIndex) -> Option<DepNodeColor> {
1270 match self.values[index].load(Ordering::Acquire) {
1271 COMPRESSED_NONE => None,
1272 COMPRESSED_RED => Some(DepNodeColor::Red),
1274 Some(DepNodeColor::Green(DepNodeIndex::from_u32(value - COMPRESSED_FIRST_GREEN)))
1279 fn insert(&self, index: SerializedDepNodeIndex, color: DepNodeColor) {
1280 self.values[index].store(
1282 DepNodeColor::Red => COMPRESSED_RED,
1283 DepNodeColor::Green(index) => index.as_u32() + COMPRESSED_FIRST_GREEN,