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 {
63 pub fn is_green(self) -> bool {
65 DepNodeColor::Red => false,
66 DepNodeColor::Green(_) => true,
71 struct DepGraphData<K: DepKind> {
72 /// The new encoding of the dependency graph, optimized for red/green
73 /// tracking. The `current` field is the dependency graph of only the
74 /// current compilation session: We don't merge the previous dep-graph into
75 /// current one anymore, but we do reference shared data to save space.
76 current: CurrentDepGraph<K>,
78 /// The dep-graph from the previous compilation session. It contains all
79 /// nodes and edges as well as all fingerprints of nodes that have them.
80 previous: SerializedDepGraph<K>,
82 colors: DepNodeColorMap,
84 processed_side_effects: Mutex<FxHashSet<DepNodeIndex>>,
86 /// When we load, there may be `.o` files, cached MIR, or other such
87 /// things available to us. If we find that they are not dirty, we
88 /// load the path to the file storing those work-products here into
89 /// this map. We can later look for and extract that data.
90 previous_work_products: FxHashMap<WorkProductId, WorkProduct>,
92 dep_node_debug: Lock<FxHashMap<DepNode<K>, String>>,
94 /// Used by incremental compilation tests to assert that
95 /// a particular query result was decoded from disk
96 /// (not just marked green)
97 debug_loaded_from_disk: Lock<FxHashSet<DepNode<K>>>,
100 pub fn hash_result<R>(hcx: &mut StableHashingContext<'_>, result: &R) -> Fingerprint
102 R: for<'a> HashStable<StableHashingContext<'a>>,
104 let mut stable_hasher = StableHasher::new();
105 result.hash_stable(hcx, &mut stable_hasher);
106 stable_hasher.finish()
109 impl<K: DepKind> DepGraph<K> {
111 profiler: &SelfProfilerRef,
112 prev_graph: SerializedDepGraph<K>,
113 prev_work_products: FxHashMap<WorkProductId, WorkProduct>,
114 encoder: FileEncoder,
118 let prev_graph_node_count = prev_graph.node_count();
120 let current = CurrentDepGraph::new(
122 prev_graph_node_count,
128 let colors = DepNodeColorMap::new(prev_graph_node_count);
130 // Instantiate a dependy-less node only once for anonymous queries.
131 let _green_node_index = current.intern_new_node(
133 DepNode { kind: DepKind::NULL, hash: current.anon_id_seed.into() },
137 debug_assert_eq!(_green_node_index, DepNodeIndex::SINGLETON_DEPENDENCYLESS_ANON_NODE);
139 // Instantiate a dependy-less red node only once for anonymous queries.
140 let (_red_node_index, _prev_and_index) = current.intern_node(
143 DepNode { kind: DepKind::NULL, hash: Fingerprint::ZERO.into() },
148 debug_assert_eq!(_red_node_index, DepNodeIndex::FOREVER_RED_NODE);
149 debug_assert!(matches!(_prev_and_index, None | Some((_, DepNodeColor::Red))));
152 data: Some(Lrc::new(DepGraphData {
153 previous_work_products: prev_work_products,
154 dep_node_debug: Default::default(),
156 processed_side_effects: Default::default(),
157 previous: prev_graph,
159 debug_loaded_from_disk: Default::default(),
161 virtual_dep_node_index: Lrc::new(AtomicU32::new(0)),
165 pub fn new_disabled() -> DepGraph<K> {
166 DepGraph { data: None, virtual_dep_node_index: Lrc::new(AtomicU32::new(0)) }
169 /// Returns `true` if we are actually building the full dep-graph, and `false` otherwise.
171 pub fn is_fully_enabled(&self) -> bool {
175 pub fn with_query(&self, f: impl Fn(&DepGraphQuery<K>)) {
176 if let Some(data) = &self.data {
177 data.current.encoder.borrow().with_query(f)
181 pub fn assert_ignored(&self) {
182 if let Some(..) = self.data {
183 K::read_deps(|task_deps| {
187 "expected no task dependency tracking"
193 pub fn with_ignore<OP, R>(&self, op: OP) -> R
197 K::with_deps(TaskDepsRef::Ignore, op)
200 /// Used to wrap the deserialization of a query result from disk,
201 /// This method enforces that no new `DepNodes` are created during
202 /// query result deserialization.
204 /// Enforcing this makes the query dep graph simpler - all nodes
205 /// must be created during the query execution, and should be
206 /// created from inside the 'body' of a query (the implementation
207 /// provided by a particular compiler crate).
209 /// Consider the case of three queries `A`, `B`, and `C`, where
210 /// `A` invokes `B` and `B` invokes `C`:
214 /// Suppose that decoding the result of query `B` required re-computing
215 /// the query `C`. If we did not create a fresh `TaskDeps` when
216 /// decoding `B`, we would still be using the `TaskDeps` for query `A`
217 /// (if we needed to re-execute `A`). This would cause us to create
218 /// a new edge `A -> C`. If this edge did not previously
219 /// exist in the `DepGraph`, then we could end up with a different
220 /// `DepGraph` at the end of compilation, even if there were no
221 /// meaningful changes to the overall program (e.g. a newline was added).
222 /// In addition, this edge might cause a subsequent compilation run
223 /// to try to force `C` before marking other necessary nodes green. If
224 /// `C` did not exist in the new compilation session, then we could
225 /// get an ICE. Normally, we would have tried (and failed) to mark
226 /// some other query green (e.g. `item_children`) which was used
227 /// to obtain `C`, which would prevent us from ever trying to force
228 /// a non-existent `D`.
230 /// It might be possible to enforce that all `DepNode`s read during
231 /// deserialization already exist in the previous `DepGraph`. In
232 /// the above example, we would invoke `D` during the deserialization
233 /// of `B`. Since we correctly create a new `TaskDeps` from the decoding
234 /// of `B`, this would result in an edge `B -> D`. If that edge already
235 /// existed (with the same `DepPathHash`es), then it should be correct
236 /// to allow the invocation of the query to proceed during deserialization
237 /// of a query result. We would merely assert that the dep-graph fragment
238 /// that would have been added by invoking `C` while decoding `B`
239 /// is equivalent to the dep-graph fragment that we already instantiated for B
240 /// (at the point where we successfully marked B as green).
242 /// However, this would require additional complexity
243 /// in the query infrastructure, and is not currently needed by the
244 /// decoding of any query results. Should the need arise in the future,
245 /// we should consider extending the query system with this functionality.
246 pub fn with_query_deserialization<OP, R>(&self, op: OP) -> R
250 K::with_deps(TaskDepsRef::Forbid, op)
253 /// Starts a new dep-graph task. Dep-graph tasks are specified
254 /// using a free function (`task`) and **not** a closure -- this
255 /// is intentional because we want to exercise tight control over
256 /// what state they have access to. In particular, we want to
257 /// prevent implicit 'leaks' of tracked state into the task (which
258 /// could then be read without generating correct edges in the
259 /// dep-graph -- see the [rustc dev guide] for more details on
260 /// the dep-graph). To this end, the task function gets exactly two
261 /// pieces of state: the context `cx` and an argument `arg`. Both
262 /// of these bits of state must be of some type that implements
263 /// `DepGraphSafe` and hence does not leak.
265 /// The choice of two arguments is not fundamental. One argument
266 /// would work just as well, since multiple values can be
267 /// collected using tuples. However, using two arguments works out
268 /// to be quite convenient, since it is common to need a context
269 /// (`cx`) and some argument (e.g., a `DefId` identifying what
270 /// item to process).
272 /// For cases where you need some other number of arguments:
274 /// - If you only need one argument, just use `()` for the `arg`
276 /// - If you need 3+ arguments, use a tuple for the
279 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/incremental-compilation.html
280 pub fn with_task<Ctxt: HasDepContext<DepKind = K>, A: Debug, R>(
285 task: fn(Ctxt, A) -> R,
286 hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
287 ) -> (R, DepNodeIndex) {
288 if self.is_fully_enabled() {
289 self.with_task_impl(key, cx, arg, task, hash_result)
291 // Incremental compilation is turned off. We just execute the task
292 // without tracking. We still provide a dep-node index that uniquely
293 // identifies the task so that we have a cheap way of referring to
294 // the query for self-profiling.
295 (task(cx, arg), self.next_virtual_depnode_index())
299 fn with_task_impl<Ctxt: HasDepContext<DepKind = K>, A: Debug, R>(
304 task: fn(Ctxt, A) -> R,
305 hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
306 ) -> (R, DepNodeIndex) {
307 // This function is only called when the graph is enabled.
308 let data = self.data.as_ref().unwrap();
310 // If the following assertion triggers, it can have two reasons:
311 // 1. Something is wrong with DepNode creation, either here or
312 // in `DepGraph::try_mark_green()`.
313 // 2. Two distinct query keys get mapped to the same `DepNode`
314 // (see for example #48923).
316 !self.dep_node_exists(&key),
317 "forcing query with already existing `DepNode`\n\
324 let task_deps = if cx.dep_context().is_eval_always(key.kind) {
327 Some(Lock::new(TaskDeps {
328 #[cfg(debug_assertions)]
330 reads: SmallVec::new(),
331 read_set: Default::default(),
332 phantom_data: PhantomData,
336 let task_deps_ref = match &task_deps {
337 Some(deps) => TaskDepsRef::Allow(deps),
338 None => TaskDepsRef::Ignore,
341 let result = K::with_deps(task_deps_ref, || task(cx, arg));
342 let edges = task_deps.map_or_else(|| smallvec![], |lock| lock.into_inner().reads);
344 let dcx = cx.dep_context();
345 let hashing_timer = dcx.profiler().incr_result_hashing();
346 let current_fingerprint =
347 hash_result.map(|f| dcx.with_stable_hashing_context(|mut hcx| f(&mut hcx, &result)));
349 let print_status = cfg!(debug_assertions) && dcx.sess().opts.debugging_opts.dep_tasks;
351 // Intern the new `DepNode`.
352 let (dep_node_index, prev_and_color) = data.current.intern_node(
361 hashing_timer.finish_with_query_invocation_id(dep_node_index.into());
363 if let Some((prev_index, color)) = prev_and_color {
365 data.colors.get(prev_index).is_none(),
366 "DepGraph::with_task() - Duplicate DepNodeColor \
371 data.colors.insert(prev_index, color);
374 (result, dep_node_index)
377 /// Executes something within an "anonymous" task, that is, a task the
378 /// `DepNode` of which is determined by the list of inputs it read from.
379 pub fn with_anon_task<Ctxt: DepContext<DepKind = K>, OP, R>(
384 ) -> (R, DepNodeIndex)
388 debug_assert!(!cx.is_eval_always(dep_kind));
390 if let Some(ref data) = self.data {
391 let task_deps = Lock::new(TaskDeps::default());
392 let result = K::with_deps(TaskDepsRef::Allow(&task_deps), op);
393 let task_deps = task_deps.into_inner();
394 let task_deps = task_deps.reads;
396 let dep_node_index = match task_deps.len() {
398 // Because the dep-node id of anon nodes is computed from the sets of its
399 // dependencies we already know what the ID of this dependency-less node is
400 // going to be (i.e. equal to the precomputed
401 // `SINGLETON_DEPENDENCYLESS_ANON_NODE`). As a consequence we can skip creating
402 // a `StableHasher` and sending the node through interning.
403 DepNodeIndex::SINGLETON_DEPENDENCYLESS_ANON_NODE
406 // When there is only one dependency, don't bother creating a node.
410 // The dep node indices are hashed here instead of hashing the dep nodes of the
411 // dependencies. These indices may refer to different nodes per session, but this isn't
412 // a problem here because we that ensure the final dep node hash is per session only by
413 // combining it with the per session random number `anon_id_seed`. This hash only need
414 // to map the dependencies to a single value on a per session basis.
415 let mut hasher = StableHasher::new();
416 task_deps.hash(&mut hasher);
418 let target_dep_node = DepNode {
420 // Fingerprint::combine() is faster than sending Fingerprint
421 // through the StableHasher (at least as long as StableHasher
423 hash: data.current.anon_id_seed.combine(hasher.finish()).into(),
426 data.current.intern_new_node(
435 (result, dep_node_index)
437 (op(), self.next_virtual_depnode_index())
442 pub fn read_index(&self, dep_node_index: DepNodeIndex) {
443 if let Some(ref data) = self.data {
444 K::read_deps(|task_deps| {
445 let mut task_deps = match task_deps {
446 TaskDepsRef::Allow(deps) => deps.lock(),
447 TaskDepsRef::Ignore => return,
448 TaskDepsRef::Forbid => {
449 panic!("Illegal read of: {:?}", dep_node_index)
452 let task_deps = &mut *task_deps;
454 if cfg!(debug_assertions) {
455 data.current.total_read_count.fetch_add(1, Relaxed);
458 // As long as we only have a low number of reads we can avoid doing a hash
459 // insert and potentially allocating/reallocating the hashmap
460 let new_read = if task_deps.reads.len() < TASK_DEPS_READS_CAP {
461 task_deps.reads.iter().all(|other| *other != dep_node_index)
463 task_deps.read_set.insert(dep_node_index)
466 task_deps.reads.push(dep_node_index);
467 if task_deps.reads.len() == TASK_DEPS_READS_CAP {
468 // Fill `read_set` with what we have so far so we can use the hashset
470 task_deps.read_set.extend(task_deps.reads.iter().copied());
473 #[cfg(debug_assertions)]
475 if let Some(target) = task_deps.node {
476 if let Some(ref forbidden_edge) = data.current.forbidden_edge {
477 let src = forbidden_edge.index_to_node.lock()[&dep_node_index];
478 if forbidden_edge.test(&src, &target) {
479 panic!("forbidden edge {:?} -> {:?} created", src, target)
484 } else if cfg!(debug_assertions) {
485 data.current.total_duplicate_read_count.fetch_add(1, Relaxed);
492 pub fn dep_node_index_of(&self, dep_node: &DepNode<K>) -> DepNodeIndex {
493 self.dep_node_index_of_opt(dep_node).unwrap()
497 pub fn dep_node_index_of_opt(&self, dep_node: &DepNode<K>) -> Option<DepNodeIndex> {
498 let data = self.data.as_ref().unwrap();
499 let current = &data.current;
501 if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
502 current.prev_index_to_index.lock()[prev_index]
504 current.new_node_to_index.get_shard_by_value(dep_node).lock().get(dep_node).copied()
509 pub fn dep_node_exists(&self, dep_node: &DepNode<K>) -> bool {
510 self.data.is_some() && self.dep_node_index_of_opt(dep_node).is_some()
513 pub fn prev_fingerprint_of(&self, dep_node: &DepNode<K>) -> Option<Fingerprint> {
514 self.data.as_ref().unwrap().previous.fingerprint_of(dep_node)
517 /// Checks whether a previous work product exists for `v` and, if
518 /// so, return the path that leads to it. Used to skip doing work.
519 pub fn previous_work_product(&self, v: &WorkProductId) -> Option<WorkProduct> {
520 self.data.as_ref().and_then(|data| data.previous_work_products.get(v).cloned())
523 /// Access the map of work-products created during the cached run. Only
524 /// used during saving of the dep-graph.
525 pub fn previous_work_products(&self) -> &FxHashMap<WorkProductId, WorkProduct> {
526 &self.data.as_ref().unwrap().previous_work_products
529 pub fn mark_debug_loaded_from_disk(&self, dep_node: DepNode<K>) {
530 self.data.as_ref().unwrap().debug_loaded_from_disk.lock().insert(dep_node);
533 pub fn debug_was_loaded_from_disk(&self, dep_node: DepNode<K>) -> bool {
534 self.data.as_ref().unwrap().debug_loaded_from_disk.lock().contains(&dep_node)
538 pub fn register_dep_node_debug_str<F>(&self, dep_node: DepNode<K>, debug_str_gen: F)
540 F: FnOnce() -> String,
542 let dep_node_debug = &self.data.as_ref().unwrap().dep_node_debug;
544 if dep_node_debug.borrow().contains_key(&dep_node) {
547 let debug_str = debug_str_gen();
548 dep_node_debug.borrow_mut().insert(dep_node, debug_str);
551 pub fn dep_node_debug_str(&self, dep_node: DepNode<K>) -> Option<String> {
552 self.data.as_ref()?.dep_node_debug.borrow().get(&dep_node).cloned()
555 fn node_color(&self, dep_node: &DepNode<K>) -> Option<DepNodeColor> {
556 if let Some(ref data) = self.data {
557 if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
558 return data.colors.get(prev_index);
560 // This is a node that did not exist in the previous compilation session.
568 /// Try to mark a node index for the node dep_node.
570 /// A node will have an index, when it's already been marked green, or when we can mark it
571 /// green. This function will mark the current task as a reader of the specified node, when
572 /// a node index can be found for that node.
573 pub fn try_mark_green<Ctxt: QueryContext<DepKind = K>>(
576 dep_node: &DepNode<K>,
577 ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
578 debug_assert!(!tcx.dep_context().is_eval_always(dep_node.kind));
580 // Return None if the dep graph is disabled
581 let data = self.data.as_ref()?;
583 // Return None if the dep node didn't exist in the previous session
584 let prev_index = data.previous.node_to_index_opt(dep_node)?;
586 match data.colors.get(prev_index) {
587 Some(DepNodeColor::Green(dep_node_index)) => Some((prev_index, dep_node_index)),
588 Some(DepNodeColor::Red) => None,
590 // This DepNode and the corresponding query invocation existed
591 // in the previous compilation session too, so we can try to
592 // mark it as green by recursively marking all of its
593 // dependencies green.
594 self.try_mark_previous_green(tcx, data, prev_index, &dep_node)
595 .map(|dep_node_index| (prev_index, dep_node_index))
600 fn try_mark_parent_green<Ctxt: QueryContext<DepKind = K>>(
603 data: &DepGraphData<K>,
604 parent_dep_node_index: SerializedDepNodeIndex,
605 dep_node: &DepNode<K>,
607 let dep_dep_node_color = data.colors.get(parent_dep_node_index);
608 let dep_dep_node = &data.previous.index_to_node(parent_dep_node_index);
610 match dep_dep_node_color {
611 Some(DepNodeColor::Green(_)) => {
612 // This dependency has been marked as green before, we are
613 // still fine and can continue with checking the other
616 "try_mark_previous_green({:?}) --- found dependency {:?} to \
617 be immediately green",
618 dep_node, dep_dep_node,
622 Some(DepNodeColor::Red) => {
623 // We found a dependency the value of which has changed
624 // compared to the previous compilation session. We cannot
625 // mark the DepNode as green and also don't need to bother
626 // with checking any of the other dependencies.
628 "try_mark_previous_green({:?}) - END - dependency {:?} was immediately red",
629 dep_node, dep_dep_node,
636 // We don't know the state of this dependency. If it isn't
637 // an eval_always node, let's try to mark it green recursively.
638 if !tcx.dep_context().is_eval_always(dep_dep_node.kind) {
640 "try_mark_previous_green({:?}) --- state of dependency {:?} ({}) \
641 is unknown, trying to mark it green",
642 dep_node, dep_dep_node, dep_dep_node.hash,
646 self.try_mark_previous_green(tcx, data, parent_dep_node_index, dep_dep_node);
647 if node_index.is_some() {
649 "try_mark_previous_green({:?}) --- managed to MARK dependency {:?} as green",
650 dep_node, dep_dep_node
656 // We failed to mark it green, so we try to force the query.
658 "try_mark_previous_green({:?}) --- trying to force dependency {:?}",
659 dep_node, dep_dep_node
661 if !tcx.dep_context().try_force_from_dep_node(*dep_dep_node) {
662 // The DepNode could not be forced.
664 "try_mark_previous_green({:?}) - END - dependency {:?} could not be forced",
665 dep_node, dep_dep_node
670 let dep_dep_node_color = data.colors.get(parent_dep_node_index);
672 match dep_dep_node_color {
673 Some(DepNodeColor::Green(_)) => {
675 "try_mark_previous_green({:?}) --- managed to FORCE dependency {:?} to green",
676 dep_node, dep_dep_node
680 Some(DepNodeColor::Red) => {
682 "try_mark_previous_green({:?}) - END - dependency {:?} was red after forcing",
683 dep_node, dep_dep_node
690 if !tcx.dep_context().sess().has_errors_or_delayed_span_bugs() {
691 panic!("try_mark_previous_green() - Forcing the DepNode should have set its color")
694 // If the query we just forced has resulted in
695 // some kind of compilation error, we cannot rely on
696 // the dep-node color having been properly updated.
697 // This means that the query system has reached an
698 // invalid state. We let the compiler continue (by
699 // returning `None`) so it can emit error messages
700 // and wind down, but rely on the fact that this
701 // invalid state will not be persisted to the
702 // incremental compilation cache because of
703 // compilation errors being present.
705 "try_mark_previous_green({:?}) - END - dependency {:?} resulted in compilation error",
706 dep_node, dep_dep_node
711 /// Try to mark a dep-node which existed in the previous compilation session as green.
712 fn try_mark_previous_green<Ctxt: QueryContext<DepKind = K>>(
715 data: &DepGraphData<K>,
716 prev_dep_node_index: SerializedDepNodeIndex,
717 dep_node: &DepNode<K>,
718 ) -> Option<DepNodeIndex> {
719 debug!("try_mark_previous_green({:?}) - BEGIN", dep_node);
721 #[cfg(not(parallel_compiler))]
723 debug_assert!(!self.dep_node_exists(dep_node));
724 debug_assert!(data.colors.get(prev_dep_node_index).is_none());
727 // We never try to mark eval_always nodes as green
728 debug_assert!(!tcx.dep_context().is_eval_always(dep_node.kind));
730 debug_assert_eq!(data.previous.index_to_node(prev_dep_node_index), *dep_node);
732 let prev_deps = data.previous.edge_targets_from(prev_dep_node_index);
734 for &dep_dep_node_index in prev_deps {
735 self.try_mark_parent_green(tcx, data, dep_dep_node_index, dep_node)?
738 // If we got here without hitting a `return` that means that all
739 // dependencies of this DepNode could be marked as green. Therefore we
740 // can also mark this DepNode as green.
742 // There may be multiple threads trying to mark the same dep node green concurrently
744 // We allocating an entry for the node in the current dependency graph and
745 // adding all the appropriate edges imported from the previous graph
746 let dep_node_index = data.current.promote_node_and_deps_to_current(
747 tcx.dep_context().profiler(),
752 // ... emitting any stored diagnostic ...
754 // FIXME: Store the fact that a node has diagnostics in a bit in the dep graph somewhere
755 // Maybe store a list on disk and encode this fact in the DepNodeState
756 let side_effects = tcx.load_side_effects(prev_dep_node_index);
758 #[cfg(not(parallel_compiler))]
760 data.colors.get(prev_dep_node_index).is_none(),
761 "DepGraph::try_mark_previous_green() - Duplicate DepNodeColor \
766 if !side_effects.is_empty() {
767 self.emit_side_effects(tcx, data, dep_node_index, side_effects);
770 // ... and finally storing a "Green" entry in the color map.
771 // Multiple threads can all write the same color here
772 data.colors.insert(prev_dep_node_index, DepNodeColor::Green(dep_node_index));
774 debug!("try_mark_previous_green({:?}) - END - successfully marked as green", dep_node);
778 /// Atomically emits some loaded diagnostics.
779 /// This may be called concurrently on multiple threads for the same dep node.
782 fn emit_side_effects<Ctxt: QueryContext<DepKind = K>>(
785 data: &DepGraphData<K>,
786 dep_node_index: DepNodeIndex,
787 side_effects: QuerySideEffects,
789 let mut processed = data.processed_side_effects.lock();
791 if processed.insert(dep_node_index) {
792 // We were the first to insert the node in the set so this thread
793 // must process side effects
795 // Promote the previous diagnostics to the current session.
796 tcx.store_side_effects(dep_node_index, side_effects.clone());
798 let handle = tcx.dep_context().sess().diagnostic();
800 for mut diagnostic in side_effects.diagnostics {
801 handle.emit_diagnostic(&mut diagnostic);
806 // Returns true if the given node has been marked as red during the
807 // current compilation session. Used in various assertions
808 pub fn is_red(&self, dep_node: &DepNode<K>) -> bool {
809 self.node_color(dep_node) == Some(DepNodeColor::Red)
812 // Returns true if the given node has been marked as green during the
813 // current compilation session. Used in various assertions
814 pub fn is_green(&self, dep_node: &DepNode<K>) -> bool {
815 self.node_color(dep_node).map_or(false, |c| c.is_green())
818 // This method loads all on-disk cacheable query results into memory, so
819 // they can be written out to the new cache file again. Most query results
820 // will already be in memory but in the case where we marked something as
821 // green but then did not need the value, that value will never have been
824 // This method will only load queries that will end up in the disk cache.
825 // Other queries will not be executed.
826 pub fn exec_cache_promotions<Ctxt: DepContext<DepKind = K>>(&self, tcx: Ctxt) {
827 let _prof_timer = tcx.profiler().generic_activity("incr_comp_query_cache_promotion");
829 let data = self.data.as_ref().unwrap();
830 for prev_index in data.colors.values.indices() {
831 match data.colors.get(prev_index) {
832 Some(DepNodeColor::Green(_)) => {
833 let dep_node = data.previous.index_to_node(prev_index);
834 tcx.try_load_from_on_disk_cache(dep_node);
836 None | Some(DepNodeColor::Red) => {
837 // We can skip red nodes because a node can only be marked
838 // as red if the query result was recomputed and thus is
839 // already in memory.
845 pub fn print_incremental_info(&self) {
846 if let Some(data) = &self.data {
847 data.current.encoder.borrow().print_incremental_info(
848 data.current.total_read_count.load(Relaxed),
849 data.current.total_duplicate_read_count.load(Relaxed),
854 pub fn encode(&self, profiler: &SelfProfilerRef) -> FileEncodeResult {
855 if let Some(data) = &self.data {
856 data.current.encoder.steal().finish(profiler)
862 pub(crate) fn next_virtual_depnode_index(&self) -> DepNodeIndex {
863 let index = self.virtual_dep_node_index.fetch_add(1, Relaxed);
864 DepNodeIndex::from_u32(index)
868 /// A "work product" is an intermediate result that we save into the
869 /// incremental directory for later re-use. The primary example are
870 /// the object files that we save for each partition at code
873 /// Each work product is associated with a dep-node, representing the
874 /// process that produced the work-product. If that dep-node is found
875 /// to be dirty when we load up, then we will delete the work-product
876 /// at load time. If the work-product is found to be clean, then we
877 /// will keep a record in the `previous_work_products` list.
879 /// In addition, work products have an associated hash. This hash is
880 /// an extra hash that can be used to decide if the work-product from
881 /// a previous compilation can be re-used (in addition to the dirty
884 /// As the primary example, consider the object files we generate for
885 /// each partition. In the first run, we create partitions based on
886 /// the symbols that need to be compiled. For each partition P, we
887 /// hash the symbols in P and create a `WorkProduct` record associated
888 /// with `DepNode::CodegenUnit(P)`; the hash is the set of symbols
891 /// The next time we compile, if the `DepNode::CodegenUnit(P)` is
892 /// judged to be clean (which means none of the things we read to
893 /// generate the partition were found to be dirty), it will be loaded
894 /// into previous work products. We will then regenerate the set of
895 /// symbols in the partition P and hash them (note that new symbols
896 /// may be added -- for example, new monomorphizations -- even if
897 /// nothing in P changed!). We will compare that hash against the
898 /// previous hash. If it matches up, we can reuse the object file.
899 #[derive(Clone, Debug, Encodable, Decodable)]
900 pub struct WorkProduct {
901 pub cgu_name: String,
902 /// Saved file associated with this CGU.
903 pub saved_file: String,
906 // Index type for `DepNodeData`'s edges.
907 rustc_index::newtype_index! {
908 struct EdgeIndex { .. }
911 /// `CurrentDepGraph` stores the dependency graph for the current session. It
912 /// will be populated as we run queries or tasks. We never remove nodes from the
913 /// graph: they are only added.
915 /// The nodes in it are identified by a `DepNodeIndex`. We avoid keeping the nodes
916 /// in memory. This is important, because these graph structures are some of the
917 /// largest in the compiler.
919 /// For this reason, we avoid storing `DepNode`s more than once as map
920 /// keys. The `new_node_to_index` map only contains nodes not in the previous
921 /// graph, and we map nodes in the previous graph to indices via a two-step
922 /// mapping. `SerializedDepGraph` maps from `DepNode` to `SerializedDepNodeIndex`,
923 /// and the `prev_index_to_index` vector (which is more compact and faster than
924 /// using a map) maps from `SerializedDepNodeIndex` to `DepNodeIndex`.
926 /// This struct uses three locks internally. The `data`, `new_node_to_index`,
927 /// and `prev_index_to_index` fields are locked separately. Operations that take
928 /// a `DepNodeIndex` typically just access the `data` field.
930 /// We only need to manipulate at most two locks simultaneously:
931 /// `new_node_to_index` and `data`, or `prev_index_to_index` and `data`. When
932 /// manipulating both, we acquire `new_node_to_index` or `prev_index_to_index`
933 /// first, and `data` second.
934 pub(super) struct CurrentDepGraph<K: DepKind> {
935 encoder: Steal<GraphEncoder<K>>,
936 new_node_to_index: Sharded<FxHashMap<DepNode<K>, DepNodeIndex>>,
937 prev_index_to_index: Lock<IndexVec<SerializedDepNodeIndex, Option<DepNodeIndex>>>,
939 /// Used to trap when a specific edge is added to the graph.
940 /// This is used for debug purposes and is only active with `debug_assertions`.
941 #[cfg(debug_assertions)]
942 forbidden_edge: Option<EdgeFilter<K>>,
944 /// Anonymous `DepNode`s are nodes whose IDs we compute from the list of
945 /// their edges. This has the beneficial side-effect that multiple anonymous
946 /// nodes can be coalesced into one without changing the semantics of the
947 /// dependency graph. However, the merging of nodes can lead to a subtle
948 /// problem during red-green marking: The color of an anonymous node from
949 /// the current session might "shadow" the color of the node with the same
950 /// ID from the previous session. In order to side-step this problem, we make
951 /// sure that anonymous `NodeId`s allocated in different sessions don't overlap.
952 /// This is implemented by mixing a session-key into the ID fingerprint of
953 /// each anon node. The session-key is just a random number generated when
954 /// the `DepGraph` is created.
955 anon_id_seed: Fingerprint,
957 /// These are simple counters that are for profiling and
958 /// debugging and only active with `debug_assertions`.
959 total_read_count: AtomicU64,
960 total_duplicate_read_count: AtomicU64,
962 /// The cached event id for profiling node interning. This saves us
963 /// from having to look up the event id every time we intern a node
964 /// which may incur too much overhead.
965 /// This will be None if self-profiling is disabled.
966 node_intern_event_id: Option<EventId>,
969 impl<K: DepKind> CurrentDepGraph<K> {
971 profiler: &SelfProfilerRef,
972 prev_graph_node_count: usize,
973 encoder: FileEncoder,
976 ) -> CurrentDepGraph<K> {
977 use std::time::{SystemTime, UNIX_EPOCH};
979 let duration = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
980 let nanos = duration.as_secs() * 1_000_000_000 + duration.subsec_nanos() as u64;
981 let mut stable_hasher = StableHasher::new();
982 nanos.hash(&mut stable_hasher);
983 let anon_id_seed = stable_hasher.finish();
984 // We rely on the fact that `anon_id_seed` is not zero when creating static nodes.
985 debug_assert_ne!(anon_id_seed, Fingerprint::ZERO);
987 #[cfg(debug_assertions)]
988 let forbidden_edge = match env::var("RUST_FORBID_DEP_GRAPH_EDGE") {
989 Ok(s) => match EdgeFilter::new(&s) {
991 Err(err) => panic!("RUST_FORBID_DEP_GRAPH_EDGE invalid: {}", err),
996 // We store a large collection of these in `prev_index_to_index` during
997 // non-full incremental builds, and want to ensure that the element size
998 // doesn't inadvertently increase.
999 static_assert_size!(Option<DepNodeIndex>, 4);
1001 let new_node_count_estimate = 102 * prev_graph_node_count / 100 + 200;
1003 let node_intern_event_id = profiler
1004 .get_or_alloc_cached_string("incr_comp_intern_dep_graph_node")
1005 .map(EventId::from_label);
1008 encoder: Steal::new(GraphEncoder::new(
1010 prev_graph_node_count,
1014 new_node_to_index: Sharded::new(|| {
1015 FxHashMap::with_capacity_and_hasher(
1016 new_node_count_estimate / sharded::SHARDS,
1020 prev_index_to_index: Lock::new(IndexVec::from_elem_n(None, prev_graph_node_count)),
1022 #[cfg(debug_assertions)]
1024 total_read_count: AtomicU64::new(0),
1025 total_duplicate_read_count: AtomicU64::new(0),
1026 node_intern_event_id,
1030 #[cfg(debug_assertions)]
1031 fn record_edge(&self, dep_node_index: DepNodeIndex, key: DepNode<K>) {
1032 if let Some(forbidden_edge) = &self.forbidden_edge {
1033 forbidden_edge.index_to_node.lock().insert(dep_node_index, key);
1037 /// Writes the node to the current dep-graph and allocates a `DepNodeIndex` for it.
1038 /// Assumes that this is a node that has no equivalent in the previous dep-graph.
1041 profiler: &SelfProfilerRef,
1044 current_fingerprint: Fingerprint,
1046 match self.new_node_to_index.get_shard_by_value(&key).lock().entry(key) {
1047 Entry::Occupied(entry) => *entry.get(),
1048 Entry::Vacant(entry) => {
1049 let dep_node_index =
1050 self.encoder.borrow().send(profiler, key, current_fingerprint, edges);
1051 entry.insert(dep_node_index);
1052 #[cfg(debug_assertions)]
1053 self.record_edge(dep_node_index, key);
1061 profiler: &SelfProfilerRef,
1062 prev_graph: &SerializedDepGraph<K>,
1065 fingerprint: Option<Fingerprint>,
1067 ) -> (DepNodeIndex, Option<(SerializedDepNodeIndex, DepNodeColor)>) {
1068 let print_status = cfg!(debug_assertions) && print_status;
1070 // Get timer for profiling `DepNode` interning
1071 let _node_intern_timer =
1072 self.node_intern_event_id.map(|eid| profiler.generic_activity_with_event_id(eid));
1074 if let Some(prev_index) = prev_graph.node_to_index_opt(&key) {
1075 // Determine the color and index of the new `DepNode`.
1076 if let Some(fingerprint) = fingerprint {
1077 if fingerprint == prev_graph.fingerprint_by_index(prev_index) {
1079 eprintln!("[task::green] {:?}", key);
1082 // This is a green node: it existed in the previous compilation,
1083 // its query was re-executed, and it has the same result as before.
1084 let mut prev_index_to_index = self.prev_index_to_index.lock();
1086 let dep_node_index = match prev_index_to_index[prev_index] {
1087 Some(dep_node_index) => dep_node_index,
1089 let dep_node_index =
1090 self.encoder.borrow().send(profiler, key, fingerprint, edges);
1091 prev_index_to_index[prev_index] = Some(dep_node_index);
1096 #[cfg(debug_assertions)]
1097 self.record_edge(dep_node_index, key);
1098 (dep_node_index, Some((prev_index, DepNodeColor::Green(dep_node_index))))
1101 eprintln!("[task::red] {:?}", key);
1104 // This is a red node: it existed in the previous compilation, its query
1105 // was re-executed, but it has a different result from before.
1106 let mut prev_index_to_index = self.prev_index_to_index.lock();
1108 let dep_node_index = match prev_index_to_index[prev_index] {
1109 Some(dep_node_index) => dep_node_index,
1111 let dep_node_index =
1112 self.encoder.borrow().send(profiler, key, fingerprint, edges);
1113 prev_index_to_index[prev_index] = Some(dep_node_index);
1118 #[cfg(debug_assertions)]
1119 self.record_edge(dep_node_index, key);
1120 (dep_node_index, Some((prev_index, DepNodeColor::Red)))
1124 eprintln!("[task::unknown] {:?}", key);
1127 // This is a red node, effectively: it existed in the previous compilation
1128 // session, its query was re-executed, but it doesn't compute a result hash
1129 // (i.e. it represents a `no_hash` query), so we have no way of determining
1130 // whether or not the result was the same as before.
1131 let mut prev_index_to_index = self.prev_index_to_index.lock();
1133 let dep_node_index = match prev_index_to_index[prev_index] {
1134 Some(dep_node_index) => dep_node_index,
1136 let dep_node_index =
1137 self.encoder.borrow().send(profiler, key, Fingerprint::ZERO, edges);
1138 prev_index_to_index[prev_index] = Some(dep_node_index);
1143 #[cfg(debug_assertions)]
1144 self.record_edge(dep_node_index, key);
1145 (dep_node_index, Some((prev_index, DepNodeColor::Red)))
1149 eprintln!("[task::new] {:?}", key);
1152 let fingerprint = fingerprint.unwrap_or(Fingerprint::ZERO);
1154 // This is a new node: it didn't exist in the previous compilation session.
1155 let dep_node_index = self.intern_new_node(profiler, key, edges, fingerprint);
1157 (dep_node_index, None)
1161 fn promote_node_and_deps_to_current(
1163 profiler: &SelfProfilerRef,
1164 prev_graph: &SerializedDepGraph<K>,
1165 prev_index: SerializedDepNodeIndex,
1167 self.debug_assert_not_in_new_nodes(prev_graph, prev_index);
1169 let mut prev_index_to_index = self.prev_index_to_index.lock();
1171 match prev_index_to_index[prev_index] {
1172 Some(dep_node_index) => dep_node_index,
1174 let key = prev_graph.index_to_node(prev_index);
1175 let dep_node_index = self.encoder.borrow().send(
1178 prev_graph.fingerprint_by_index(prev_index),
1180 .edge_targets_from(prev_index)
1182 .map(|i| prev_index_to_index[*i].unwrap())
1185 prev_index_to_index[prev_index] = Some(dep_node_index);
1186 #[cfg(debug_assertions)]
1187 self.record_edge(dep_node_index, key);
1194 fn debug_assert_not_in_new_nodes(
1196 prev_graph: &SerializedDepGraph<K>,
1197 prev_index: SerializedDepNodeIndex,
1199 let node = &prev_graph.index_to_node(prev_index);
1201 !self.new_node_to_index.get_shard_by_value(node).lock().contains_key(node),
1202 "node from previous graph present in new node collection"
1207 /// The capacity of the `reads` field `SmallVec`
1208 const TASK_DEPS_READS_CAP: usize = 8;
1209 type EdgesVec = SmallVec<[DepNodeIndex; TASK_DEPS_READS_CAP]>;
1211 #[derive(Debug, Clone, Copy)]
1212 pub enum TaskDepsRef<'a, K: DepKind> {
1213 /// New dependencies can be added to the
1214 /// `TaskDeps`. This is used when executing a 'normal' query
1215 /// (no `eval_always` modifier)
1216 Allow(&'a Lock<TaskDeps<K>>),
1217 /// New dependencies are ignored. This is used when
1218 /// executing an `eval_always` query, since there's no
1219 /// need to track dependencies for a query that's always
1220 /// re-executed. This is also used for `dep_graph.with_ignore`
1222 /// Any attempt to add new dependencies will cause a panic.
1223 /// This is used when decoding a query result from disk,
1224 /// to ensure that the decoding process doesn't itself
1225 /// require the execution of any queries.
1230 pub struct TaskDeps<K: DepKind> {
1231 #[cfg(debug_assertions)]
1232 node: Option<DepNode<K>>,
1234 read_set: FxHashSet<DepNodeIndex>,
1235 phantom_data: PhantomData<DepNode<K>>,
1238 impl<K: DepKind> Default for TaskDeps<K> {
1239 fn default() -> Self {
1241 #[cfg(debug_assertions)]
1243 reads: EdgesVec::new(),
1244 read_set: FxHashSet::default(),
1245 phantom_data: PhantomData,
1250 // A data structure that stores Option<DepNodeColor> values as a contiguous
1251 // array, using one u32 per entry.
1252 struct DepNodeColorMap {
1253 values: IndexVec<SerializedDepNodeIndex, AtomicU32>,
1256 const COMPRESSED_NONE: u32 = 0;
1257 const COMPRESSED_RED: u32 = 1;
1258 const COMPRESSED_FIRST_GREEN: u32 = 2;
1260 impl DepNodeColorMap {
1261 fn new(size: usize) -> DepNodeColorMap {
1262 DepNodeColorMap { values: (0..size).map(|_| AtomicU32::new(COMPRESSED_NONE)).collect() }
1266 fn get(&self, index: SerializedDepNodeIndex) -> Option<DepNodeColor> {
1267 match self.values[index].load(Ordering::Acquire) {
1268 COMPRESSED_NONE => None,
1269 COMPRESSED_RED => Some(DepNodeColor::Red),
1271 Some(DepNodeColor::Green(DepNodeIndex::from_u32(value - COMPRESSED_FIRST_GREEN)))
1276 fn insert(&self, index: SerializedDepNodeIndex, color: DepNodeColor) {
1277 self.values[index].store(
1279 DepNodeColor::Red => COMPRESSED_RED,
1280 DepNodeColor::Green(index) => index.as_u32() + COMPRESSED_FIRST_GREEN,