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);
48 impl std::convert::From<DepNodeIndex> for QueryInvocationId {
50 fn from(dep_node_index: DepNodeIndex) -> Self {
51 QueryInvocationId(dep_node_index.as_u32())
56 pub enum DepNodeColor {
62 pub fn is_green(self) -> bool {
64 DepNodeColor::Red => false,
65 DepNodeColor::Green(_) => true,
70 struct DepGraphData<K: DepKind> {
71 /// The new encoding of the dependency graph, optimized for red/green
72 /// tracking. The `current` field is the dependency graph of only the
73 /// current compilation session: We don't merge the previous dep-graph into
74 /// current one anymore, but we do reference shared data to save space.
75 current: CurrentDepGraph<K>,
77 /// The dep-graph from the previous compilation session. It contains all
78 /// nodes and edges as well as all fingerprints of nodes that have them.
79 previous: SerializedDepGraph<K>,
81 colors: DepNodeColorMap,
83 processed_side_effects: Mutex<FxHashSet<DepNodeIndex>>,
85 /// When we load, there may be `.o` files, cached MIR, or other such
86 /// things available to us. If we find that they are not dirty, we
87 /// load the path to the file storing those work-products here into
88 /// this map. We can later look for and extract that data.
89 previous_work_products: FxHashMap<WorkProductId, WorkProduct>,
91 dep_node_debug: Lock<FxHashMap<DepNode<K>, String>>,
93 /// Used by incremental compilation tests to assert that
94 /// a particular query result was decoded from disk
95 /// (not just marked green)
96 debug_loaded_from_disk: Lock<FxHashSet<DepNode<K>>>,
99 pub fn hash_result<R>(hcx: &mut StableHashingContext<'_>, result: &R) -> Fingerprint
101 R: for<'a> HashStable<StableHashingContext<'a>>,
103 let mut stable_hasher = StableHasher::new();
104 result.hash_stable(hcx, &mut stable_hasher);
105 stable_hasher.finish()
108 impl<K: DepKind> DepGraph<K> {
110 profiler: &SelfProfilerRef,
111 prev_graph: SerializedDepGraph<K>,
112 prev_work_products: FxHashMap<WorkProductId, WorkProduct>,
113 encoder: FileEncoder,
117 let prev_graph_node_count = prev_graph.node_count();
119 let current = CurrentDepGraph::new(
121 prev_graph_node_count,
127 // Instantiate a dependy-less node only once for anonymous queries.
128 let _green_node_index = current.intern_new_node(
130 DepNode { kind: DepKind::NULL, hash: current.anon_id_seed.into() },
134 debug_assert_eq!(_green_node_index, DepNodeIndex::SINGLETON_DEPENDENCYLESS_ANON_NODE);
137 data: Some(Lrc::new(DepGraphData {
138 previous_work_products: prev_work_products,
139 dep_node_debug: Default::default(),
141 processed_side_effects: Default::default(),
142 previous: prev_graph,
143 colors: DepNodeColorMap::new(prev_graph_node_count),
144 debug_loaded_from_disk: Default::default(),
146 virtual_dep_node_index: Lrc::new(AtomicU32::new(0)),
150 pub fn new_disabled() -> DepGraph<K> {
151 DepGraph { data: None, virtual_dep_node_index: Lrc::new(AtomicU32::new(0)) }
154 /// Returns `true` if we are actually building the full dep-graph, and `false` otherwise.
156 pub fn is_fully_enabled(&self) -> bool {
160 pub fn with_query(&self, f: impl Fn(&DepGraphQuery<K>)) {
161 if let Some(data) = &self.data {
162 data.current.encoder.borrow().with_query(f)
166 pub fn assert_ignored(&self) {
167 if let Some(..) = self.data {
168 K::read_deps(|task_deps| {
172 "expected no task dependency tracking"
178 pub fn with_ignore<OP, R>(&self, op: OP) -> R
182 K::with_deps(TaskDepsRef::Ignore, op)
185 /// Used to wrap the deserialization of a query result from disk,
186 /// This method enforces that no new `DepNodes` are created during
187 /// query result deserialization.
189 /// Enforcing this makes the query dep graph simpler - all nodes
190 /// must be created during the query execution, and should be
191 /// created from inside the 'body' of a query (the implementation
192 /// provided by a particular compiler crate).
194 /// Consider the case of three queries `A`, `B`, and `C`, where
195 /// `A` invokes `B` and `B` invokes `C`:
199 /// Suppose that decoding the result of query `B` required re-computing
200 /// the query `C`. If we did not create a fresh `TaskDeps` when
201 /// decoding `B`, we would still be using the `TaskDeps` for query `A`
202 /// (if we needed to re-execute `A`). This would cause us to create
203 /// a new edge `A -> C`. If this edge did not previously
204 /// exist in the `DepGraph`, then we could end up with a different
205 /// `DepGraph` at the end of compilation, even if there were no
206 /// meaningful changes to the overall program (e.g. a newline was added).
207 /// In addition, this edge might cause a subsequent compilation run
208 /// to try to force `C` before marking other necessary nodes green. If
209 /// `C` did not exist in the new compilation session, then we could
210 /// get an ICE. Normally, we would have tried (and failed) to mark
211 /// some other query green (e.g. `item_children`) which was used
212 /// to obtain `C`, which would prevent us from ever trying to force
213 /// a non-existent `D`.
215 /// It might be possible to enforce that all `DepNode`s read during
216 /// deserialization already exist in the previous `DepGraph`. In
217 /// the above example, we would invoke `D` during the deserialization
218 /// of `B`. Since we correctly create a new `TaskDeps` from the decoding
219 /// of `B`, this would result in an edge `B -> D`. If that edge already
220 /// existed (with the same `DepPathHash`es), then it should be correct
221 /// to allow the invocation of the query to proceed during deserialization
222 /// of a query result. We would merely assert that the dep-graph fragment
223 /// that would have been added by invoking `C` while decoding `B`
224 /// is equivalent to the dep-graph fragment that we already instantiated for B
225 /// (at the point where we successfully marked B as green).
227 /// However, this would require additional complexity
228 /// in the query infrastructure, and is not currently needed by the
229 /// decoding of any query results. Should the need arise in the future,
230 /// we should consider extending the query system with this functionality.
231 pub fn with_query_deserialization<OP, R>(&self, op: OP) -> R
235 K::with_deps(TaskDepsRef::Forbid, op)
238 /// Starts a new dep-graph task. Dep-graph tasks are specified
239 /// using a free function (`task`) and **not** a closure -- this
240 /// is intentional because we want to exercise tight control over
241 /// what state they have access to. In particular, we want to
242 /// prevent implicit 'leaks' of tracked state into the task (which
243 /// could then be read without generating correct edges in the
244 /// dep-graph -- see the [rustc dev guide] for more details on
245 /// the dep-graph). To this end, the task function gets exactly two
246 /// pieces of state: the context `cx` and an argument `arg`. Both
247 /// of these bits of state must be of some type that implements
248 /// `DepGraphSafe` and hence does not leak.
250 /// The choice of two arguments is not fundamental. One argument
251 /// would work just as well, since multiple values can be
252 /// collected using tuples. However, using two arguments works out
253 /// to be quite convenient, since it is common to need a context
254 /// (`cx`) and some argument (e.g., a `DefId` identifying what
255 /// item to process).
257 /// For cases where you need some other number of arguments:
259 /// - If you only need one argument, just use `()` for the `arg`
261 /// - If you need 3+ arguments, use a tuple for the
264 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/incremental-compilation.html
265 pub fn with_task<Ctxt: HasDepContext<DepKind = K>, A: Debug, R>(
270 task: fn(Ctxt, A) -> R,
271 hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
272 ) -> (R, DepNodeIndex) {
273 if self.is_fully_enabled() {
274 self.with_task_impl(key, cx, arg, task, hash_result)
276 // Incremental compilation is turned off. We just execute the task
277 // without tracking. We still provide a dep-node index that uniquely
278 // identifies the task so that we have a cheap way of referring to
279 // the query for self-profiling.
280 (task(cx, arg), self.next_virtual_depnode_index())
284 fn with_task_impl<Ctxt: HasDepContext<DepKind = K>, A: Debug, R>(
289 task: fn(Ctxt, A) -> R,
290 hash_result: Option<fn(&mut StableHashingContext<'_>, &R) -> Fingerprint>,
291 ) -> (R, DepNodeIndex) {
292 // This function is only called when the graph is enabled.
293 let data = self.data.as_ref().unwrap();
295 // If the following assertion triggers, it can have two reasons:
296 // 1. Something is wrong with DepNode creation, either here or
297 // in `DepGraph::try_mark_green()`.
298 // 2. Two distinct query keys get mapped to the same `DepNode`
299 // (see for example #48923).
301 !self.dep_node_exists(&key),
302 "forcing query with already existing `DepNode`\n\
309 let task_deps = if cx.dep_context().is_eval_always(key.kind) {
312 Some(Lock::new(TaskDeps {
313 #[cfg(debug_assertions)]
315 reads: SmallVec::new(),
316 read_set: Default::default(),
317 phantom_data: PhantomData,
321 let task_deps_ref = match &task_deps {
322 Some(deps) => TaskDepsRef::Allow(deps),
323 None => TaskDepsRef::Ignore,
326 let result = K::with_deps(task_deps_ref, || task(cx, arg));
327 let edges = task_deps.map_or_else(|| smallvec![], |lock| lock.into_inner().reads);
329 let dcx = cx.dep_context();
330 let hashing_timer = dcx.profiler().incr_result_hashing();
331 let current_fingerprint = hash_result.map(|f| {
332 let mut hcx = dcx.create_stable_hashing_context();
336 let print_status = cfg!(debug_assertions) && dcx.sess().opts.debugging_opts.dep_tasks;
338 // Intern the new `DepNode`.
339 let (dep_node_index, prev_and_color) = data.current.intern_node(
348 hashing_timer.finish_with_query_invocation_id(dep_node_index.into());
350 if let Some((prev_index, color)) = prev_and_color {
352 data.colors.get(prev_index).is_none(),
353 "DepGraph::with_task() - Duplicate DepNodeColor \
358 data.colors.insert(prev_index, color);
361 (result, dep_node_index)
364 /// Executes something within an "anonymous" task, that is, a task the
365 /// `DepNode` of which is determined by the list of inputs it read from.
366 pub fn with_anon_task<Ctxt: DepContext<DepKind = K>, OP, R>(
371 ) -> (R, DepNodeIndex)
375 debug_assert!(!cx.is_eval_always(dep_kind));
377 if let Some(ref data) = self.data {
378 let task_deps = Lock::new(TaskDeps::default());
379 let result = K::with_deps(TaskDepsRef::Allow(&task_deps), op);
380 let task_deps = task_deps.into_inner();
381 let task_deps = task_deps.reads;
383 let dep_node_index = match task_deps.len() {
385 // Because the dep-node id of anon nodes is computed from the sets of its
386 // dependencies we already know what the ID of this dependency-less node is
387 // going to be (i.e. equal to the precomputed
388 // `SINGLETON_DEPENDENCYLESS_ANON_NODE`). As a consequence we can skip creating
389 // a `StableHasher` and sending the node through interning.
390 DepNodeIndex::SINGLETON_DEPENDENCYLESS_ANON_NODE
393 // When there is only one dependency, don't bother creating a node.
397 // The dep node indices are hashed here instead of hashing the dep nodes of the
398 // dependencies. These indices may refer to different nodes per session, but this isn't
399 // a problem here because we that ensure the final dep node hash is per session only by
400 // combining it with the per session random number `anon_id_seed`. This hash only need
401 // to map the dependencies to a single value on a per session basis.
402 let mut hasher = StableHasher::new();
403 task_deps.hash(&mut hasher);
405 let target_dep_node = DepNode {
407 // Fingerprint::combine() is faster than sending Fingerprint
408 // through the StableHasher (at least as long as StableHasher
410 hash: data.current.anon_id_seed.combine(hasher.finish()).into(),
413 data.current.intern_new_node(
422 (result, dep_node_index)
424 (op(), self.next_virtual_depnode_index())
429 pub fn read_index(&self, dep_node_index: DepNodeIndex) {
430 if let Some(ref data) = self.data {
431 K::read_deps(|task_deps| {
432 let mut task_deps = match task_deps {
433 TaskDepsRef::Allow(deps) => deps.lock(),
434 TaskDepsRef::Ignore => return,
435 TaskDepsRef::Forbid => {
436 panic!("Illegal read of: {:?}", dep_node_index)
439 let task_deps = &mut *task_deps;
441 if cfg!(debug_assertions) {
442 data.current.total_read_count.fetch_add(1, Relaxed);
445 // As long as we only have a low number of reads we can avoid doing a hash
446 // insert and potentially allocating/reallocating the hashmap
447 let new_read = if task_deps.reads.len() < TASK_DEPS_READS_CAP {
448 task_deps.reads.iter().all(|other| *other != dep_node_index)
450 task_deps.read_set.insert(dep_node_index)
453 task_deps.reads.push(dep_node_index);
454 if task_deps.reads.len() == TASK_DEPS_READS_CAP {
455 // Fill `read_set` with what we have so far so we can use the hashset
457 task_deps.read_set.extend(task_deps.reads.iter().copied());
460 #[cfg(debug_assertions)]
462 if let Some(target) = task_deps.node {
463 if let Some(ref forbidden_edge) = data.current.forbidden_edge {
464 let src = forbidden_edge.index_to_node.lock()[&dep_node_index];
465 if forbidden_edge.test(&src, &target) {
466 panic!("forbidden edge {:?} -> {:?} created", src, target)
471 } else if cfg!(debug_assertions) {
472 data.current.total_duplicate_read_count.fetch_add(1, Relaxed);
479 pub fn dep_node_index_of(&self, dep_node: &DepNode<K>) -> DepNodeIndex {
480 self.dep_node_index_of_opt(dep_node).unwrap()
484 pub fn dep_node_index_of_opt(&self, dep_node: &DepNode<K>) -> Option<DepNodeIndex> {
485 let data = self.data.as_ref().unwrap();
486 let current = &data.current;
488 if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
489 current.prev_index_to_index.lock()[prev_index]
491 current.new_node_to_index.get_shard_by_value(dep_node).lock().get(dep_node).copied()
496 pub fn dep_node_exists(&self, dep_node: &DepNode<K>) -> bool {
497 self.data.is_some() && self.dep_node_index_of_opt(dep_node).is_some()
500 pub fn prev_fingerprint_of(&self, dep_node: &DepNode<K>) -> Option<Fingerprint> {
501 self.data.as_ref().unwrap().previous.fingerprint_of(dep_node)
504 /// Checks whether a previous work product exists for `v` and, if
505 /// so, return the path that leads to it. Used to skip doing work.
506 pub fn previous_work_product(&self, v: &WorkProductId) -> Option<WorkProduct> {
507 self.data.as_ref().and_then(|data| data.previous_work_products.get(v).cloned())
510 /// Access the map of work-products created during the cached run. Only
511 /// used during saving of the dep-graph.
512 pub fn previous_work_products(&self) -> &FxHashMap<WorkProductId, WorkProduct> {
513 &self.data.as_ref().unwrap().previous_work_products
516 pub fn mark_debug_loaded_from_disk(&self, dep_node: DepNode<K>) {
517 self.data.as_ref().unwrap().debug_loaded_from_disk.lock().insert(dep_node);
520 pub fn debug_was_loaded_from_disk(&self, dep_node: DepNode<K>) -> bool {
521 self.data.as_ref().unwrap().debug_loaded_from_disk.lock().contains(&dep_node)
525 pub fn register_dep_node_debug_str<F>(&self, dep_node: DepNode<K>, debug_str_gen: F)
527 F: FnOnce() -> String,
529 let dep_node_debug = &self.data.as_ref().unwrap().dep_node_debug;
531 if dep_node_debug.borrow().contains_key(&dep_node) {
534 let debug_str = debug_str_gen();
535 dep_node_debug.borrow_mut().insert(dep_node, debug_str);
538 pub fn dep_node_debug_str(&self, dep_node: DepNode<K>) -> Option<String> {
539 self.data.as_ref()?.dep_node_debug.borrow().get(&dep_node).cloned()
542 fn node_color(&self, dep_node: &DepNode<K>) -> Option<DepNodeColor> {
543 if let Some(ref data) = self.data {
544 if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
545 return data.colors.get(prev_index);
547 // This is a node that did not exist in the previous compilation session.
555 /// Try to mark a node index for the node dep_node.
557 /// A node will have an index, when it's already been marked green, or when we can mark it
558 /// green. This function will mark the current task as a reader of the specified node, when
559 /// a node index can be found for that node.
560 pub fn try_mark_green<Ctxt: QueryContext<DepKind = K>>(
563 dep_node: &DepNode<K>,
564 ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
565 debug_assert!(!tcx.dep_context().is_eval_always(dep_node.kind));
567 // Return None if the dep graph is disabled
568 let data = self.data.as_ref()?;
570 // Return None if the dep node didn't exist in the previous session
571 let prev_index = data.previous.node_to_index_opt(dep_node)?;
573 match data.colors.get(prev_index) {
574 Some(DepNodeColor::Green(dep_node_index)) => Some((prev_index, dep_node_index)),
575 Some(DepNodeColor::Red) => None,
577 // This DepNode and the corresponding query invocation existed
578 // in the previous compilation session too, so we can try to
579 // mark it as green by recursively marking all of its
580 // dependencies green.
581 self.try_mark_previous_green(tcx, data, prev_index, &dep_node)
582 .map(|dep_node_index| (prev_index, dep_node_index))
587 fn try_mark_parent_green<Ctxt: QueryContext<DepKind = K>>(
590 data: &DepGraphData<K>,
591 parent_dep_node_index: SerializedDepNodeIndex,
592 dep_node: &DepNode<K>,
594 let dep_dep_node_color = data.colors.get(parent_dep_node_index);
595 let dep_dep_node = &data.previous.index_to_node(parent_dep_node_index);
597 match dep_dep_node_color {
598 Some(DepNodeColor::Green(_)) => {
599 // This dependency has been marked as green before, we are
600 // still fine and can continue with checking the other
603 "try_mark_previous_green({:?}) --- found dependency {:?} to \
604 be immediately green",
605 dep_node, dep_dep_node,
609 Some(DepNodeColor::Red) => {
610 // We found a dependency the value of which has changed
611 // compared to the previous compilation session. We cannot
612 // mark the DepNode as green and also don't need to bother
613 // with checking any of the other dependencies.
615 "try_mark_previous_green({:?}) - END - dependency {:?} was immediately red",
616 dep_node, dep_dep_node,
623 // We don't know the state of this dependency. If it isn't
624 // an eval_always node, let's try to mark it green recursively.
625 if !tcx.dep_context().is_eval_always(dep_dep_node.kind) {
627 "try_mark_previous_green({:?}) --- state of dependency {:?} ({}) \
628 is unknown, trying to mark it green",
629 dep_node, dep_dep_node, dep_dep_node.hash,
633 self.try_mark_previous_green(tcx, data, parent_dep_node_index, dep_dep_node);
634 if node_index.is_some() {
636 "try_mark_previous_green({:?}) --- managed to MARK dependency {:?} as green",
637 dep_node, dep_dep_node
643 // We failed to mark it green, so we try to force the query.
645 "try_mark_previous_green({:?}) --- trying to force dependency {:?}",
646 dep_node, dep_dep_node
648 if !tcx.dep_context().try_force_from_dep_node(*dep_dep_node) {
649 // The DepNode could not be forced.
651 "try_mark_previous_green({:?}) - END - dependency {:?} could not be forced",
652 dep_node, dep_dep_node
657 let dep_dep_node_color = data.colors.get(parent_dep_node_index);
659 match dep_dep_node_color {
660 Some(DepNodeColor::Green(_)) => {
662 "try_mark_previous_green({:?}) --- managed to FORCE dependency {:?} to green",
663 dep_node, dep_dep_node
667 Some(DepNodeColor::Red) => {
669 "try_mark_previous_green({:?}) - END - dependency {:?} was red after forcing",
670 dep_node, dep_dep_node
677 if !tcx.dep_context().sess().has_errors_or_delayed_span_bugs() {
678 panic!("try_mark_previous_green() - Forcing the DepNode should have set its color")
681 // If the query we just forced has resulted in
682 // some kind of compilation error, we cannot rely on
683 // the dep-node color having been properly updated.
684 // This means that the query system has reached an
685 // invalid state. We let the compiler continue (by
686 // returning `None`) so it can emit error messages
687 // and wind down, but rely on the fact that this
688 // invalid state will not be persisted to the
689 // incremental compilation cache because of
690 // compilation errors being present.
692 "try_mark_previous_green({:?}) - END - dependency {:?} resulted in compilation error",
693 dep_node, dep_dep_node
698 /// Try to mark a dep-node which existed in the previous compilation session as green.
699 fn try_mark_previous_green<Ctxt: QueryContext<DepKind = K>>(
702 data: &DepGraphData<K>,
703 prev_dep_node_index: SerializedDepNodeIndex,
704 dep_node: &DepNode<K>,
705 ) -> Option<DepNodeIndex> {
706 debug!("try_mark_previous_green({:?}) - BEGIN", dep_node);
708 #[cfg(not(parallel_compiler))]
710 debug_assert!(!self.dep_node_exists(dep_node));
711 debug_assert!(data.colors.get(prev_dep_node_index).is_none());
714 // We never try to mark eval_always nodes as green
715 debug_assert!(!tcx.dep_context().is_eval_always(dep_node.kind));
717 debug_assert_eq!(data.previous.index_to_node(prev_dep_node_index), *dep_node);
719 let prev_deps = data.previous.edge_targets_from(prev_dep_node_index);
721 for &dep_dep_node_index in prev_deps {
722 self.try_mark_parent_green(tcx, data, dep_dep_node_index, dep_node)?
725 // If we got here without hitting a `return` that means that all
726 // dependencies of this DepNode could be marked as green. Therefore we
727 // can also mark this DepNode as green.
729 // There may be multiple threads trying to mark the same dep node green concurrently
731 // We allocating an entry for the node in the current dependency graph and
732 // adding all the appropriate edges imported from the previous graph
733 let dep_node_index = data.current.promote_node_and_deps_to_current(
734 tcx.dep_context().profiler(),
739 // ... emitting any stored diagnostic ...
741 // FIXME: Store the fact that a node has diagnostics in a bit in the dep graph somewhere
742 // Maybe store a list on disk and encode this fact in the DepNodeState
743 let side_effects = tcx.load_side_effects(prev_dep_node_index);
745 #[cfg(not(parallel_compiler))]
747 data.colors.get(prev_dep_node_index).is_none(),
748 "DepGraph::try_mark_previous_green() - Duplicate DepNodeColor \
753 if unlikely!(!side_effects.is_empty()) {
754 self.emit_side_effects(tcx, data, dep_node_index, side_effects);
757 // ... and finally storing a "Green" entry in the color map.
758 // Multiple threads can all write the same color here
759 data.colors.insert(prev_dep_node_index, DepNodeColor::Green(dep_node_index));
761 debug!("try_mark_previous_green({:?}) - END - successfully marked as green", dep_node);
765 /// Atomically emits some loaded diagnostics.
766 /// This may be called concurrently on multiple threads for the same dep node.
769 fn emit_side_effects<Ctxt: QueryContext<DepKind = K>>(
772 data: &DepGraphData<K>,
773 dep_node_index: DepNodeIndex,
774 side_effects: QuerySideEffects,
776 let mut processed = data.processed_side_effects.lock();
778 if processed.insert(dep_node_index) {
779 // We were the first to insert the node in the set so this thread
780 // must process side effects
782 // Promote the previous diagnostics to the current session.
783 tcx.store_side_effects(dep_node_index, side_effects.clone());
785 let handle = tcx.dep_context().sess().diagnostic();
787 for mut diagnostic in side_effects.diagnostics {
788 handle.emit_diagnostic(&mut diagnostic);
793 // Returns true if the given node has been marked as red during the
794 // current compilation session. Used in various assertions
795 pub fn is_red(&self, dep_node: &DepNode<K>) -> bool {
796 self.node_color(dep_node) == Some(DepNodeColor::Red)
799 // Returns true if the given node has been marked as green during the
800 // current compilation session. Used in various assertions
801 pub fn is_green(&self, dep_node: &DepNode<K>) -> bool {
802 self.node_color(dep_node).map_or(false, |c| c.is_green())
805 // This method loads all on-disk cacheable query results into memory, so
806 // they can be written out to the new cache file again. Most query results
807 // will already be in memory but in the case where we marked something as
808 // green but then did not need the value, that value will never have been
811 // This method will only load queries that will end up in the disk cache.
812 // Other queries will not be executed.
813 pub fn exec_cache_promotions<Ctxt: DepContext<DepKind = K>>(&self, tcx: Ctxt) {
814 let _prof_timer = tcx.profiler().generic_activity("incr_comp_query_cache_promotion");
816 let data = self.data.as_ref().unwrap();
817 for prev_index in data.colors.values.indices() {
818 match data.colors.get(prev_index) {
819 Some(DepNodeColor::Green(_)) => {
820 let dep_node = data.previous.index_to_node(prev_index);
821 tcx.try_load_from_on_disk_cache(dep_node);
823 None | Some(DepNodeColor::Red) => {
824 // We can skip red nodes because a node can only be marked
825 // as red if the query result was recomputed and thus is
826 // already in memory.
832 pub fn print_incremental_info(&self) {
833 if let Some(data) = &self.data {
834 data.current.encoder.borrow().print_incremental_info(
835 data.current.total_read_count.load(Relaxed),
836 data.current.total_duplicate_read_count.load(Relaxed),
841 pub fn encode(&self, profiler: &SelfProfilerRef) -> FileEncodeResult {
842 if let Some(data) = &self.data {
843 data.current.encoder.steal().finish(profiler)
849 pub(crate) fn next_virtual_depnode_index(&self) -> DepNodeIndex {
850 let index = self.virtual_dep_node_index.fetch_add(1, Relaxed);
851 DepNodeIndex::from_u32(index)
855 /// A "work product" is an intermediate result that we save into the
856 /// incremental directory for later re-use. The primary example are
857 /// the object files that we save for each partition at code
860 /// Each work product is associated with a dep-node, representing the
861 /// process that produced the work-product. If that dep-node is found
862 /// to be dirty when we load up, then we will delete the work-product
863 /// at load time. If the work-product is found to be clean, then we
864 /// will keep a record in the `previous_work_products` list.
866 /// In addition, work products have an associated hash. This hash is
867 /// an extra hash that can be used to decide if the work-product from
868 /// a previous compilation can be re-used (in addition to the dirty
871 /// As the primary example, consider the object files we generate for
872 /// each partition. In the first run, we create partitions based on
873 /// the symbols that need to be compiled. For each partition P, we
874 /// hash the symbols in P and create a `WorkProduct` record associated
875 /// with `DepNode::CodegenUnit(P)`; the hash is the set of symbols
878 /// The next time we compile, if the `DepNode::CodegenUnit(P)` is
879 /// judged to be clean (which means none of the things we read to
880 /// generate the partition were found to be dirty), it will be loaded
881 /// into previous work products. We will then regenerate the set of
882 /// symbols in the partition P and hash them (note that new symbols
883 /// may be added -- for example, new monomorphizations -- even if
884 /// nothing in P changed!). We will compare that hash against the
885 /// previous hash. If it matches up, we can reuse the object file.
886 #[derive(Clone, Debug, Encodable, Decodable)]
887 pub struct WorkProduct {
888 pub cgu_name: String,
889 /// Saved file associated with this CGU.
890 pub saved_file: Option<String>,
893 // Index type for `DepNodeData`'s edges.
894 rustc_index::newtype_index! {
895 struct EdgeIndex { .. }
898 /// `CurrentDepGraph` stores the dependency graph for the current session. It
899 /// will be populated as we run queries or tasks. We never remove nodes from the
900 /// graph: they are only added.
902 /// The nodes in it are identified by a `DepNodeIndex`. We avoid keeping the nodes
903 /// in memory. This is important, because these graph structures are some of the
904 /// largest in the compiler.
906 /// For this reason, we avoid storing `DepNode`s more than once as map
907 /// keys. The `new_node_to_index` map only contains nodes not in the previous
908 /// graph, and we map nodes in the previous graph to indices via a two-step
909 /// mapping. `SerializedDepGraph` maps from `DepNode` to `SerializedDepNodeIndex`,
910 /// and the `prev_index_to_index` vector (which is more compact and faster than
911 /// using a map) maps from `SerializedDepNodeIndex` to `DepNodeIndex`.
913 /// This struct uses three locks internally. The `data`, `new_node_to_index`,
914 /// and `prev_index_to_index` fields are locked separately. Operations that take
915 /// a `DepNodeIndex` typically just access the `data` field.
917 /// We only need to manipulate at most two locks simultaneously:
918 /// `new_node_to_index` and `data`, or `prev_index_to_index` and `data`. When
919 /// manipulating both, we acquire `new_node_to_index` or `prev_index_to_index`
920 /// first, and `data` second.
921 pub(super) struct CurrentDepGraph<K: DepKind> {
922 encoder: Steal<GraphEncoder<K>>,
923 new_node_to_index: Sharded<FxHashMap<DepNode<K>, DepNodeIndex>>,
924 prev_index_to_index: Lock<IndexVec<SerializedDepNodeIndex, Option<DepNodeIndex>>>,
926 /// Used to trap when a specific edge is added to the graph.
927 /// This is used for debug purposes and is only active with `debug_assertions`.
928 #[cfg(debug_assertions)]
929 forbidden_edge: Option<EdgeFilter<K>>,
931 /// Anonymous `DepNode`s are nodes whose IDs we compute from the list of
932 /// their edges. This has the beneficial side-effect that multiple anonymous
933 /// nodes can be coalesced into one without changing the semantics of the
934 /// dependency graph. However, the merging of nodes can lead to a subtle
935 /// problem during red-green marking: The color of an anonymous node from
936 /// the current session might "shadow" the color of the node with the same
937 /// ID from the previous session. In order to side-step this problem, we make
938 /// sure that anonymous `NodeId`s allocated in different sessions don't overlap.
939 /// This is implemented by mixing a session-key into the ID fingerprint of
940 /// each anon node. The session-key is just a random number generated when
941 /// the `DepGraph` is created.
942 anon_id_seed: Fingerprint,
944 /// These are simple counters that are for profiling and
945 /// debugging and only active with `debug_assertions`.
946 total_read_count: AtomicU64,
947 total_duplicate_read_count: AtomicU64,
949 /// The cached event id for profiling node interning. This saves us
950 /// from having to look up the event id every time we intern a node
951 /// which may incur too much overhead.
952 /// This will be None if self-profiling is disabled.
953 node_intern_event_id: Option<EventId>,
956 impl<K: DepKind> CurrentDepGraph<K> {
958 profiler: &SelfProfilerRef,
959 prev_graph_node_count: usize,
960 encoder: FileEncoder,
963 ) -> CurrentDepGraph<K> {
964 use std::time::{SystemTime, UNIX_EPOCH};
966 let duration = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
967 let nanos = duration.as_secs() * 1_000_000_000 + duration.subsec_nanos() as u64;
968 let mut stable_hasher = StableHasher::new();
969 nanos.hash(&mut stable_hasher);
971 #[cfg(debug_assertions)]
972 let forbidden_edge = match env::var("RUST_FORBID_DEP_GRAPH_EDGE") {
973 Ok(s) => match EdgeFilter::new(&s) {
975 Err(err) => panic!("RUST_FORBID_DEP_GRAPH_EDGE invalid: {}", err),
980 // We store a large collection of these in `prev_index_to_index` during
981 // non-full incremental builds, and want to ensure that the element size
982 // doesn't inadvertently increase.
983 static_assert_size!(Option<DepNodeIndex>, 4);
985 let new_node_count_estimate = 102 * prev_graph_node_count / 100 + 200;
987 let node_intern_event_id = profiler
988 .get_or_alloc_cached_string("incr_comp_intern_dep_graph_node")
989 .map(EventId::from_label);
992 encoder: Steal::new(GraphEncoder::new(
994 prev_graph_node_count,
998 new_node_to_index: Sharded::new(|| {
999 FxHashMap::with_capacity_and_hasher(
1000 new_node_count_estimate / sharded::SHARDS,
1004 prev_index_to_index: Lock::new(IndexVec::from_elem_n(None, prev_graph_node_count)),
1005 anon_id_seed: stable_hasher.finish(),
1006 #[cfg(debug_assertions)]
1008 total_read_count: AtomicU64::new(0),
1009 total_duplicate_read_count: AtomicU64::new(0),
1010 node_intern_event_id,
1014 #[cfg(debug_assertions)]
1015 fn record_edge(&self, dep_node_index: DepNodeIndex, key: DepNode<K>) {
1016 if let Some(forbidden_edge) = &self.forbidden_edge {
1017 forbidden_edge.index_to_node.lock().insert(dep_node_index, key);
1021 /// Writes the node to the current dep-graph and allocates a `DepNodeIndex` for it.
1022 /// Assumes that this is a node that has no equivalent in the previous dep-graph.
1025 profiler: &SelfProfilerRef,
1028 current_fingerprint: Fingerprint,
1030 match self.new_node_to_index.get_shard_by_value(&key).lock().entry(key) {
1031 Entry::Occupied(entry) => *entry.get(),
1032 Entry::Vacant(entry) => {
1033 let dep_node_index =
1034 self.encoder.borrow().send(profiler, key, current_fingerprint, edges);
1035 entry.insert(dep_node_index);
1036 #[cfg(debug_assertions)]
1037 self.record_edge(dep_node_index, key);
1045 profiler: &SelfProfilerRef,
1046 prev_graph: &SerializedDepGraph<K>,
1049 fingerprint: Option<Fingerprint>,
1051 ) -> (DepNodeIndex, Option<(SerializedDepNodeIndex, DepNodeColor)>) {
1052 let print_status = cfg!(debug_assertions) && print_status;
1054 // Get timer for profiling `DepNode` interning
1055 let _node_intern_timer =
1056 self.node_intern_event_id.map(|eid| profiler.generic_activity_with_event_id(eid));
1058 if let Some(prev_index) = prev_graph.node_to_index_opt(&key) {
1059 // Determine the color and index of the new `DepNode`.
1060 if let Some(fingerprint) = fingerprint {
1061 if fingerprint == prev_graph.fingerprint_by_index(prev_index) {
1063 eprintln!("[task::green] {:?}", key);
1066 // This is a green node: it existed in the previous compilation,
1067 // its query was re-executed, and it has the same result as before.
1068 let mut prev_index_to_index = self.prev_index_to_index.lock();
1070 let dep_node_index = match prev_index_to_index[prev_index] {
1071 Some(dep_node_index) => dep_node_index,
1073 let dep_node_index =
1074 self.encoder.borrow().send(profiler, key, fingerprint, edges);
1075 prev_index_to_index[prev_index] = Some(dep_node_index);
1080 #[cfg(debug_assertions)]
1081 self.record_edge(dep_node_index, key);
1082 (dep_node_index, Some((prev_index, DepNodeColor::Green(dep_node_index))))
1085 eprintln!("[task::red] {:?}", key);
1088 // This is a red node: it existed in the previous compilation, its query
1089 // was re-executed, but it has a different result from before.
1090 let mut prev_index_to_index = self.prev_index_to_index.lock();
1092 let dep_node_index = match prev_index_to_index[prev_index] {
1093 Some(dep_node_index) => dep_node_index,
1095 let dep_node_index =
1096 self.encoder.borrow().send(profiler, key, fingerprint, edges);
1097 prev_index_to_index[prev_index] = Some(dep_node_index);
1102 #[cfg(debug_assertions)]
1103 self.record_edge(dep_node_index, key);
1104 (dep_node_index, Some((prev_index, DepNodeColor::Red)))
1108 eprintln!("[task::unknown] {:?}", key);
1111 // This is a red node, effectively: it existed in the previous compilation
1112 // session, its query was re-executed, but it doesn't compute a result hash
1113 // (i.e. it represents a `no_hash` query), so we have no way of determining
1114 // whether or not the result was the same as before.
1115 let mut prev_index_to_index = self.prev_index_to_index.lock();
1117 let dep_node_index = match prev_index_to_index[prev_index] {
1118 Some(dep_node_index) => dep_node_index,
1120 let dep_node_index =
1121 self.encoder.borrow().send(profiler, key, Fingerprint::ZERO, edges);
1122 prev_index_to_index[prev_index] = Some(dep_node_index);
1127 #[cfg(debug_assertions)]
1128 self.record_edge(dep_node_index, key);
1129 (dep_node_index, Some((prev_index, DepNodeColor::Red)))
1133 eprintln!("[task::new] {:?}", key);
1136 let fingerprint = fingerprint.unwrap_or(Fingerprint::ZERO);
1138 // This is a new node: it didn't exist in the previous compilation session.
1139 let dep_node_index = self.intern_new_node(profiler, key, edges, fingerprint);
1141 (dep_node_index, None)
1145 fn promote_node_and_deps_to_current(
1147 profiler: &SelfProfilerRef,
1148 prev_graph: &SerializedDepGraph<K>,
1149 prev_index: SerializedDepNodeIndex,
1151 self.debug_assert_not_in_new_nodes(prev_graph, prev_index);
1153 let mut prev_index_to_index = self.prev_index_to_index.lock();
1155 match prev_index_to_index[prev_index] {
1156 Some(dep_node_index) => dep_node_index,
1158 let key = prev_graph.index_to_node(prev_index);
1159 let dep_node_index = self.encoder.borrow().send(
1162 prev_graph.fingerprint_by_index(prev_index),
1164 .edge_targets_from(prev_index)
1166 .map(|i| prev_index_to_index[*i].unwrap())
1169 prev_index_to_index[prev_index] = Some(dep_node_index);
1170 #[cfg(debug_assertions)]
1171 self.record_edge(dep_node_index, key);
1178 fn debug_assert_not_in_new_nodes(
1180 prev_graph: &SerializedDepGraph<K>,
1181 prev_index: SerializedDepNodeIndex,
1183 let node = &prev_graph.index_to_node(prev_index);
1185 !self.new_node_to_index.get_shard_by_value(node).lock().contains_key(node),
1186 "node from previous graph present in new node collection"
1191 /// The capacity of the `reads` field `SmallVec`
1192 const TASK_DEPS_READS_CAP: usize = 8;
1193 type EdgesVec = SmallVec<[DepNodeIndex; TASK_DEPS_READS_CAP]>;
1195 #[derive(Debug, Clone, Copy)]
1196 pub enum TaskDepsRef<'a, K: DepKind> {
1197 /// New dependencies can be added to the
1198 /// `TaskDeps`. This is used when executing a 'normal' query
1199 /// (no `eval_always` modifier)
1200 Allow(&'a Lock<TaskDeps<K>>),
1201 /// New dependencies are ignored. This is used when
1202 /// executing an `eval_always` query, since there's no
1203 /// need to track dependencies for a query that's always
1204 /// re-executed. This is also used for `dep_graph.with_ignore`
1206 /// Any attempt to add new dependencies will cause a panic.
1207 /// This is used when decoding a query result from disk,
1208 /// to ensure that the decoding process doesn't itself
1209 /// require the execution of any queries.
1214 pub struct TaskDeps<K: DepKind> {
1215 #[cfg(debug_assertions)]
1216 node: Option<DepNode<K>>,
1218 read_set: FxHashSet<DepNodeIndex>,
1219 phantom_data: PhantomData<DepNode<K>>,
1222 impl<K: DepKind> Default for TaskDeps<K> {
1223 fn default() -> Self {
1225 #[cfg(debug_assertions)]
1227 reads: EdgesVec::new(),
1228 read_set: FxHashSet::default(),
1229 phantom_data: PhantomData,
1234 // A data structure that stores Option<DepNodeColor> values as a contiguous
1235 // array, using one u32 per entry.
1236 struct DepNodeColorMap {
1237 values: IndexVec<SerializedDepNodeIndex, AtomicU32>,
1240 const COMPRESSED_NONE: u32 = 0;
1241 const COMPRESSED_RED: u32 = 1;
1242 const COMPRESSED_FIRST_GREEN: u32 = 2;
1244 impl DepNodeColorMap {
1245 fn new(size: usize) -> DepNodeColorMap {
1246 DepNodeColorMap { values: (0..size).map(|_| AtomicU32::new(COMPRESSED_NONE)).collect() }
1250 fn get(&self, index: SerializedDepNodeIndex) -> Option<DepNodeColor> {
1251 match self.values[index].load(Ordering::Acquire) {
1252 COMPRESSED_NONE => None,
1253 COMPRESSED_RED => Some(DepNodeColor::Red),
1255 Some(DepNodeColor::Green(DepNodeIndex::from_u32(value - COMPRESSED_FIRST_GREEN)))
1260 fn insert(&self, index: SerializedDepNodeIndex, color: DepNodeColor) {
1261 self.values[index].store(
1263 DepNodeColor::Red => COMPRESSED_RED,
1264 DepNodeColor::Green(index) => index.as_u32() + COMPRESSED_FIRST_GREEN,