1 use rustc_data_structures::fingerprint::Fingerprint;
2 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
3 use rustc_data_structures::profiling::QueryInvocationId;
4 use rustc_data_structures::sharded::{self, Sharded};
5 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
6 use rustc_data_structures::sync::{AtomicU32, AtomicU64, Lock, Lrc, Ordering};
7 use rustc_data_structures::unlikely;
8 use rustc_errors::Diagnostic;
9 use rustc_index::vec::{Idx, IndexVec};
11 use parking_lot::{Condvar, Mutex};
12 use smallvec::{smallvec, SmallVec};
13 use std::collections::hash_map::Entry;
16 use std::marker::PhantomData;
18 use std::sync::atomic::Ordering::Relaxed;
20 use super::debug::EdgeFilter;
21 use super::prev::PreviousDepGraph;
22 use super::query::DepGraphQuery;
23 use super::safe::DepGraphSafe;
24 use super::serialized::{SerializedDepGraph, SerializedDepNodeIndex};
25 use super::{DepContext, DepKind, DepNode, WorkProductId};
26 use crate::{HashStableContext, HashStableContextProvider};
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;
47 impl std::convert::From<DepNodeIndex> for QueryInvocationId {
49 fn from(dep_node_index: DepNodeIndex) -> Self {
50 QueryInvocationId(dep_node_index.as_u32())
55 pub enum DepNodeColor {
61 pub fn is_green(self) -> bool {
63 DepNodeColor::Red => false,
64 DepNodeColor::Green(_) => true,
69 struct DepGraphData<K: DepKind> {
70 /// The new encoding of the dependency graph, optimized for red/green
71 /// tracking. The `current` field is the dependency graph of only the
72 /// current compilation session: We don't merge the previous dep-graph into
73 /// current one anymore.
74 current: CurrentDepGraph<K>,
76 /// The dep-graph from the previous compilation session. It contains all
77 /// nodes and edges as well as all fingerprints of nodes that have them.
78 previous: PreviousDepGraph<K>,
80 colors: DepNodeColorMap,
82 /// A set of loaded diagnostics that is in the progress of being emitted.
83 emitting_diagnostics: Mutex<FxHashSet<DepNodeIndex>>,
85 /// Used to wait for diagnostics to be emitted.
86 emitting_diagnostics_cond_var: Condvar,
88 /// When we load, there may be `.o` files, cached MIR, or other such
89 /// things available to us. If we find that they are not dirty, we
90 /// load the path to the file storing those work-products here into
91 /// this map. We can later look for and extract that data.
92 previous_work_products: FxHashMap<WorkProductId, WorkProduct>,
94 dep_node_debug: Lock<FxHashMap<DepNode<K>, String>>,
97 pub fn hash_result<HashCtxt, R>(hcx: &mut HashCtxt, result: &R) -> Option<Fingerprint>
99 R: HashStable<HashCtxt>,
101 let mut stable_hasher = StableHasher::new();
102 result.hash_stable(hcx, &mut stable_hasher);
104 Some(stable_hasher.finish())
107 impl<K: DepKind> DepGraph<K> {
109 prev_graph: PreviousDepGraph<K>,
110 prev_work_products: FxHashMap<WorkProductId, WorkProduct>,
112 let prev_graph_node_count = prev_graph.node_count();
115 data: Some(Lrc::new(DepGraphData {
116 previous_work_products: prev_work_products,
117 dep_node_debug: Default::default(),
118 current: CurrentDepGraph::new(prev_graph_node_count),
119 emitting_diagnostics: Default::default(),
120 emitting_diagnostics_cond_var: Condvar::new(),
121 previous: prev_graph,
122 colors: DepNodeColorMap::new(prev_graph_node_count),
124 virtual_dep_node_index: Lrc::new(AtomicU32::new(0)),
128 pub fn new_disabled() -> DepGraph<K> {
129 DepGraph { data: None, virtual_dep_node_index: Lrc::new(AtomicU32::new(0)) }
132 /// Returns `true` if we are actually building the full dep-graph, and `false` otherwise.
134 pub fn is_fully_enabled(&self) -> bool {
138 pub fn query(&self) -> DepGraphQuery<K> {
139 let data = self.data.as_ref().unwrap().current.data.lock();
140 let nodes: Vec<_> = data.iter().map(|n| n.node).collect();
141 let mut edges = Vec::new();
142 for (from, edge_targets) in data.iter().map(|d| (d.node, &d.edges)) {
143 for &edge_target in edge_targets.iter() {
144 let to = data[edge_target].node;
145 edges.push((from, to));
149 DepGraphQuery::new(&nodes[..], &edges[..])
152 pub fn assert_ignored(&self) {
153 if let Some(..) = self.data {
154 K::read_deps(|task_deps| {
155 assert!(task_deps.is_none(), "expected no task dependency tracking");
160 pub fn with_ignore<OP, R>(&self, op: OP) -> R
164 K::with_deps(None, op)
167 /// Starts a new dep-graph task. Dep-graph tasks are specified
168 /// using a free function (`task`) and **not** a closure -- this
169 /// is intentional because we want to exercise tight control over
170 /// what state they have access to. In particular, we want to
171 /// prevent implicit 'leaks' of tracked state into the task (which
172 /// could then be read without generating correct edges in the
173 /// dep-graph -- see the [rustc dev guide] for more details on
174 /// the dep-graph). To this end, the task function gets exactly two
175 /// pieces of state: the context `cx` and an argument `arg`. Both
176 /// of these bits of state must be of some type that implements
177 /// `DepGraphSafe` and hence does not leak.
179 /// The choice of two arguments is not fundamental. One argument
180 /// would work just as well, since multiple values can be
181 /// collected using tuples. However, using two arguments works out
182 /// to be quite convenient, since it is common to need a context
183 /// (`cx`) and some argument (e.g., a `DefId` identifying what
184 /// item to process).
186 /// For cases where you need some other number of arguments:
188 /// - If you only need one argument, just use `()` for the `arg`
190 /// - If you need 3+ arguments, use a tuple for the
193 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/incremental-compilation.html
194 pub fn with_task<H, C, A, R>(
200 hash_result: impl FnOnce(&mut H, &R) -> Option<Fingerprint>,
201 ) -> (R, DepNodeIndex)
203 C: DepGraphSafe + HashStableContextProvider<H>,
204 H: HashStableContext,
214 #[cfg(debug_assertions)]
216 reads: SmallVec::new(),
217 read_set: Default::default(),
218 phantom_data: PhantomData,
221 |data, key, fingerprint, task| data.complete_task(key, task.unwrap(), fingerprint),
226 fn with_task_impl<H, C, A, R>(
233 create_task: fn(DepNode<K>) -> Option<TaskDeps<K>>,
234 finish_task_and_alloc_depnode: fn(
240 hash_result: impl FnOnce(&mut H, &R) -> Option<Fingerprint>,
241 ) -> (R, DepNodeIndex)
243 C: DepGraphSafe + HashStableContextProvider<H>,
244 H: HashStableContext,
246 if let Some(ref data) = self.data {
247 let task_deps = create_task(key).map(Lock::new);
249 // In incremental mode, hash the result of the task. We don't
250 // do anything with the hash yet, but we are computing it
252 // - we make sure that the infrastructure works and
253 // - we can get an idea of the runtime cost.
254 let mut hcx = cx.get_stable_hashing_context();
256 let result = if no_tcx {
259 K::with_deps(task_deps.as_ref(), || task(cx, arg))
262 let current_fingerprint = hash_result(&mut hcx, &result);
264 let dep_node_index = finish_task_and_alloc_depnode(
267 current_fingerprint.unwrap_or(Fingerprint::ZERO),
268 task_deps.map(|lock| lock.into_inner()),
271 let print_status = cfg!(debug_assertions) && hcx.debug_dep_tasks();
273 // Determine the color of the new DepNode.
274 if let Some(prev_index) = data.previous.node_to_index_opt(&key) {
275 let prev_fingerprint = data.previous.fingerprint_by_index(prev_index);
277 let color = if let Some(current_fingerprint) = current_fingerprint {
278 if current_fingerprint == prev_fingerprint {
280 eprintln!("[task::green] {:?}", key);
282 DepNodeColor::Green(dep_node_index)
285 eprintln!("[task::red] {:?}", key);
291 eprintln!("[task::unknown] {:?}", key);
293 // Mark the node as Red if we can't hash the result
298 data.colors.get(prev_index).is_none(),
299 "DepGraph::with_task() - Duplicate DepNodeColor \
304 data.colors.insert(prev_index, color);
307 eprintln!("[task::new] {:?}", key);
311 (result, dep_node_index)
313 (task(cx, arg), self.next_virtual_depnode_index())
317 /// Executes something within an "anonymous" task, that is, a task the
318 /// `DepNode` of which is determined by the list of inputs it read from.
319 pub fn with_anon_task<OP, R>(&self, dep_kind: K, op: OP) -> (R, DepNodeIndex)
323 if let Some(ref data) = self.data {
324 let task_deps = Lock::new(TaskDeps::default());
326 let result = K::with_deps(Some(&task_deps), op);
327 let task_deps = task_deps.into_inner();
329 let dep_node_index = data.current.complete_anon_task(dep_kind, task_deps);
330 (result, dep_node_index)
332 (op(), self.next_virtual_depnode_index())
336 /// Executes something within an "eval-always" task which is a task
337 /// that runs whenever anything changes.
338 pub fn with_eval_always_task<H, C, A, R>(
344 hash_result: impl FnOnce(&mut H, &R) -> Option<Fingerprint>,
345 ) -> (R, DepNodeIndex)
347 C: DepGraphSafe + HashStableContextProvider<H>,
348 H: HashStableContext,
357 |data, key, fingerprint, _| data.alloc_node(key, smallvec![], fingerprint),
363 pub fn read(&self, v: DepNode<K>) {
364 if let Some(ref data) = self.data {
365 let map = data.current.node_to_node_index.get_shard_by_value(&v).lock();
366 if let Some(dep_node_index) = map.get(&v).copied() {
368 data.read_index(dep_node_index);
370 panic!("DepKind {:?} should be pre-allocated but isn't.", v.kind)
376 pub fn read_index(&self, dep_node_index: DepNodeIndex) {
377 if let Some(ref data) = self.data {
378 data.read_index(dep_node_index);
383 pub fn dep_node_index_of(&self, dep_node: &DepNode<K>) -> DepNodeIndex {
389 .get_shard_by_value(dep_node)
397 pub fn dep_node_exists(&self, dep_node: &DepNode<K>) -> bool {
398 if let Some(ref data) = self.data {
401 .get_shard_by_value(&dep_node)
403 .contains_key(dep_node)
410 pub fn fingerprint_of(&self, dep_node_index: DepNodeIndex) -> Fingerprint {
411 let data = self.data.as_ref().expect("dep graph enabled").current.data.lock();
412 data[dep_node_index].fingerprint
415 pub fn prev_fingerprint_of(&self, dep_node: &DepNode<K>) -> Option<Fingerprint> {
416 self.data.as_ref().unwrap().previous.fingerprint_of(dep_node)
420 pub fn prev_dep_node_index_of(&self, dep_node: &DepNode<K>) -> SerializedDepNodeIndex {
421 self.data.as_ref().unwrap().previous.node_to_index(dep_node)
424 /// Checks whether a previous work product exists for `v` and, if
425 /// so, return the path that leads to it. Used to skip doing work.
426 pub fn previous_work_product(&self, v: &WorkProductId) -> Option<WorkProduct> {
427 self.data.as_ref().and_then(|data| data.previous_work_products.get(v).cloned())
430 /// Access the map of work-products created during the cached run. Only
431 /// used during saving of the dep-graph.
432 pub fn previous_work_products(&self) -> &FxHashMap<WorkProductId, WorkProduct> {
433 &self.data.as_ref().unwrap().previous_work_products
437 pub fn register_dep_node_debug_str<F>(&self, dep_node: DepNode<K>, debug_str_gen: F)
439 F: FnOnce() -> String,
441 let dep_node_debug = &self.data.as_ref().unwrap().dep_node_debug;
443 if dep_node_debug.borrow().contains_key(&dep_node) {
446 let debug_str = debug_str_gen();
447 dep_node_debug.borrow_mut().insert(dep_node, debug_str);
450 pub fn dep_node_debug_str(&self, dep_node: DepNode<K>) -> Option<String> {
451 self.data.as_ref()?.dep_node_debug.borrow().get(&dep_node).cloned()
454 pub fn edge_deduplication_data(&self) -> Option<(u64, u64)> {
455 if cfg!(debug_assertions) {
456 let current_dep_graph = &self.data.as_ref().unwrap().current;
459 current_dep_graph.total_read_count.load(Relaxed),
460 current_dep_graph.total_duplicate_read_count.load(Relaxed),
467 pub fn serialize(&self) -> SerializedDepGraph<K> {
468 let data = self.data.as_ref().unwrap().current.data.lock();
470 let fingerprints: IndexVec<SerializedDepNodeIndex, _> =
471 data.iter().map(|d| d.fingerprint).collect();
472 let nodes: IndexVec<SerializedDepNodeIndex, _> = data.iter().map(|d| d.node).collect();
474 let total_edge_count: usize = data.iter().map(|d| d.edges.len()).sum();
476 let mut edge_list_indices = IndexVec::with_capacity(nodes.len());
477 let mut edge_list_data = Vec::with_capacity(total_edge_count);
479 for (current_dep_node_index, edges) in data.iter_enumerated().map(|(i, d)| (i, &d.edges)) {
480 let start = edge_list_data.len() as u32;
481 // This should really just be a memcpy :/
482 edge_list_data.extend(edges.iter().map(|i| SerializedDepNodeIndex::new(i.index())));
483 let end = edge_list_data.len() as u32;
485 debug_assert_eq!(current_dep_node_index.index(), edge_list_indices.len());
486 edge_list_indices.push((start, end));
489 debug_assert!(edge_list_data.len() <= u32::MAX as usize);
490 debug_assert_eq!(edge_list_data.len(), total_edge_count);
492 SerializedDepGraph { nodes, fingerprints, edge_list_indices, edge_list_data }
495 pub fn node_color(&self, dep_node: &DepNode<K>) -> Option<DepNodeColor> {
496 if let Some(ref data) = self.data {
497 if let Some(prev_index) = data.previous.node_to_index_opt(dep_node) {
498 return data.colors.get(prev_index);
500 // This is a node that did not exist in the previous compilation
501 // session, so we consider it to be red.
502 return Some(DepNodeColor::Red);
509 /// Try to read a node index for the node dep_node.
510 /// A node will have an index, when it's already been marked green, or when we can mark it
511 /// green. This function will mark the current task as a reader of the specified node, when
512 /// a node index can be found for that node.
513 pub fn try_mark_green_and_read<Ctxt: DepContext<DepKind = K>>(
516 dep_node: &DepNode<K>,
517 ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
518 self.try_mark_green(tcx, dep_node).map(|(prev_index, dep_node_index)| {
519 debug_assert!(self.is_green(&dep_node));
520 self.read_index(dep_node_index);
521 (prev_index, dep_node_index)
525 pub fn try_mark_green<Ctxt: DepContext<DepKind = K>>(
528 dep_node: &DepNode<K>,
529 ) -> Option<(SerializedDepNodeIndex, DepNodeIndex)> {
530 debug_assert!(!dep_node.kind.is_eval_always());
532 // Return None if the dep graph is disabled
533 let data = self.data.as_ref()?;
535 // Return None if the dep node didn't exist in the previous session
536 let prev_index = data.previous.node_to_index_opt(dep_node)?;
538 match data.colors.get(prev_index) {
539 Some(DepNodeColor::Green(dep_node_index)) => Some((prev_index, dep_node_index)),
540 Some(DepNodeColor::Red) => None,
542 // This DepNode and the corresponding query invocation existed
543 // in the previous compilation session too, so we can try to
544 // mark it as green by recursively marking all of its
545 // dependencies green.
546 self.try_mark_previous_green(tcx, data, prev_index, &dep_node)
547 .map(|dep_node_index| (prev_index, dep_node_index))
552 /// Try to mark a dep-node which existed in the previous compilation session as green.
553 fn try_mark_previous_green<Ctxt: DepContext<DepKind = K>>(
556 data: &DepGraphData<K>,
557 prev_dep_node_index: SerializedDepNodeIndex,
558 dep_node: &DepNode<K>,
559 ) -> Option<DepNodeIndex> {
560 debug!("try_mark_previous_green({:?}) - BEGIN", dep_node);
562 #[cfg(not(parallel_compiler))]
568 .get_shard_by_value(dep_node)
570 .contains_key(dep_node)
572 debug_assert!(data.colors.get(prev_dep_node_index).is_none());
575 // We never try to mark eval_always nodes as green
576 debug_assert!(!dep_node.kind.is_eval_always());
578 debug_assert_eq!(data.previous.index_to_node(prev_dep_node_index), *dep_node);
580 let prev_deps = data.previous.edge_targets_from(prev_dep_node_index);
582 let mut current_deps = SmallVec::new();
584 for &dep_dep_node_index in prev_deps {
585 let dep_dep_node_color = data.colors.get(dep_dep_node_index);
587 match dep_dep_node_color {
588 Some(DepNodeColor::Green(node_index)) => {
589 // This dependency has been marked as green before, we are
590 // still fine and can continue with checking the other
593 "try_mark_previous_green({:?}) --- found dependency {:?} to \
594 be immediately green",
596 data.previous.index_to_node(dep_dep_node_index)
598 current_deps.push(node_index);
600 Some(DepNodeColor::Red) => {
601 // We found a dependency the value of which has changed
602 // compared to the previous compilation session. We cannot
603 // mark the DepNode as green and also don't need to bother
604 // with checking any of the other dependencies.
606 "try_mark_previous_green({:?}) - END - dependency {:?} was \
609 data.previous.index_to_node(dep_dep_node_index)
614 let dep_dep_node = &data.previous.index_to_node(dep_dep_node_index);
616 // We don't know the state of this dependency. If it isn't
617 // an eval_always node, let's try to mark it green recursively.
618 if !dep_dep_node.kind.is_eval_always() {
620 "try_mark_previous_green({:?}) --- state of dependency {:?} \
621 is unknown, trying to mark it green",
622 dep_node, dep_dep_node
625 let node_index = self.try_mark_previous_green(
631 if let Some(node_index) = node_index {
633 "try_mark_previous_green({:?}) --- managed to MARK \
634 dependency {:?} as green",
635 dep_node, dep_dep_node
637 current_deps.push(node_index);
642 // We failed to mark it green, so we try to force the query.
644 "try_mark_previous_green({:?}) --- trying to force \
646 dep_node, dep_dep_node
648 if tcx.try_force_from_dep_node(dep_dep_node) {
649 let dep_dep_node_color = data.colors.get(dep_dep_node_index);
651 match dep_dep_node_color {
652 Some(DepNodeColor::Green(node_index)) => {
654 "try_mark_previous_green({:?}) --- managed to \
655 FORCE dependency {:?} to green",
656 dep_node, dep_dep_node
658 current_deps.push(node_index);
660 Some(DepNodeColor::Red) => {
662 "try_mark_previous_green({:?}) - END - \
663 dependency {:?} was red after forcing",
664 dep_node, dep_dep_node
669 if !tcx.has_errors_or_delayed_span_bugs() {
671 "try_mark_previous_green() - Forcing the DepNode \
672 should have set its color"
675 // If the query we just forced has resulted in
676 // some kind of compilation error, we cannot rely on
677 // the dep-node color having been properly updated.
678 // This means that the query system has reached an
679 // invalid state. We let the compiler continue (by
680 // returning `None`) so it can emit error messages
681 // and wind down, but rely on the fact that this
682 // invalid state will not be persisted to the
683 // incremental compilation cache because of
684 // compilation errors being present.
686 "try_mark_previous_green({:?}) - END - \
687 dependency {:?} resulted in compilation error",
688 dep_node, dep_dep_node
695 // The DepNode could not be forced.
697 "try_mark_previous_green({:?}) - END - dependency {:?} \
698 could not be forced",
699 dep_node, dep_dep_node
707 // If we got here without hitting a `return` that means that all
708 // dependencies of this DepNode could be marked as green. Therefore we
709 // can also mark this DepNode as green.
711 // There may be multiple threads trying to mark the same dep node green concurrently
713 let dep_node_index = {
714 // Copy the fingerprint from the previous graph,
715 // so we don't have to recompute it
716 let fingerprint = data.previous.fingerprint_by_index(prev_dep_node_index);
718 // We allocating an entry for the node in the current dependency graph and
719 // adding all the appropriate edges imported from the previous graph
720 data.current.intern_node(*dep_node, current_deps, fingerprint)
723 // ... emitting any stored diagnostic ...
725 // FIXME: Store the fact that a node has diagnostics in a bit in the dep graph somewhere
726 // Maybe store a list on disk and encode this fact in the DepNodeState
727 let diagnostics = tcx.load_diagnostics(prev_dep_node_index);
729 #[cfg(not(parallel_compiler))]
731 data.colors.get(prev_dep_node_index).is_none(),
732 "DepGraph::try_mark_previous_green() - Duplicate DepNodeColor \
737 if unlikely!(!diagnostics.is_empty()) {
738 self.emit_diagnostics(tcx, data, dep_node_index, prev_dep_node_index, diagnostics);
741 // ... and finally storing a "Green" entry in the color map.
742 // Multiple threads can all write the same color here
743 data.colors.insert(prev_dep_node_index, DepNodeColor::Green(dep_node_index));
745 debug!("try_mark_previous_green({:?}) - END - successfully marked as green", dep_node);
749 /// Atomically emits some loaded diagnostics.
750 /// This may be called concurrently on multiple threads for the same dep node.
753 fn emit_diagnostics<Ctxt: DepContext<DepKind = K>>(
756 data: &DepGraphData<K>,
757 dep_node_index: DepNodeIndex,
758 prev_dep_node_index: SerializedDepNodeIndex,
759 diagnostics: Vec<Diagnostic>,
761 let mut emitting = data.emitting_diagnostics.lock();
763 if data.colors.get(prev_dep_node_index) == Some(DepNodeColor::Green(dep_node_index)) {
764 // The node is already green so diagnostics must have been emitted already
768 if emitting.insert(dep_node_index) {
769 // We were the first to insert the node in the set so this thread
770 // must emit the diagnostics and signal other potentially waiting
774 // Promote the previous diagnostics to the current session.
775 tcx.store_diagnostics(dep_node_index, diagnostics.clone().into());
777 let handle = tcx.diagnostic();
779 for diagnostic in diagnostics {
780 handle.emit_diagnostic(&diagnostic);
783 // Mark the node as green now that diagnostics are emitted
784 data.colors.insert(prev_dep_node_index, DepNodeColor::Green(dep_node_index));
786 // Remove the node from the set
787 data.emitting_diagnostics.lock().remove(&dep_node_index);
790 data.emitting_diagnostics_cond_var.notify_all();
792 // We must wait for the other thread to finish emitting the diagnostic
795 data.emitting_diagnostics_cond_var.wait(&mut emitting);
796 if data.colors.get(prev_dep_node_index) == Some(DepNodeColor::Green(dep_node_index))
804 // Returns true if the given node has been marked as green during the
805 // current compilation session. Used in various assertions
806 pub fn is_green(&self, dep_node: &DepNode<K>) -> bool {
807 self.node_color(dep_node).map(|c| c.is_green()).unwrap_or(false)
810 // This method loads all on-disk cacheable query results into memory, so
811 // they can be written out to the new cache file again. Most query results
812 // will already be in memory but in the case where we marked something as
813 // green but then did not need the value, that value will never have been
816 // This method will only load queries that will end up in the disk cache.
817 // Other queries will not be executed.
818 pub fn exec_cache_promotions<Ctxt: DepContext<DepKind = K>>(&self, tcx: Ctxt) {
819 let _prof_timer = tcx.profiler().generic_activity("incr_comp_query_cache_promotion");
821 let data = self.data.as_ref().unwrap();
822 for prev_index in data.colors.values.indices() {
823 match data.colors.get(prev_index) {
824 Some(DepNodeColor::Green(_)) => {
825 let dep_node = data.previous.index_to_node(prev_index);
826 tcx.try_load_from_on_disk_cache(&dep_node);
828 None | Some(DepNodeColor::Red) => {
829 // We can skip red nodes because a node can only be marked
830 // as red if the query result was recomputed and thus is
831 // already in memory.
837 fn next_virtual_depnode_index(&self) -> DepNodeIndex {
838 let index = self.virtual_dep_node_index.fetch_add(1, Relaxed);
839 DepNodeIndex::from_u32(index)
843 /// A "work product" is an intermediate result that we save into the
844 /// incremental directory for later re-use. The primary example are
845 /// the object files that we save for each partition at code
848 /// Each work product is associated with a dep-node, representing the
849 /// process that produced the work-product. If that dep-node is found
850 /// to be dirty when we load up, then we will delete the work-product
851 /// at load time. If the work-product is found to be clean, then we
852 /// will keep a record in the `previous_work_products` list.
854 /// In addition, work products have an associated hash. This hash is
855 /// an extra hash that can be used to decide if the work-product from
856 /// a previous compilation can be re-used (in addition to the dirty
859 /// As the primary example, consider the object files we generate for
860 /// each partition. In the first run, we create partitions based on
861 /// the symbols that need to be compiled. For each partition P, we
862 /// hash the symbols in P and create a `WorkProduct` record associated
863 /// with `DepNode::CodegenUnit(P)`; the hash is the set of symbols
866 /// The next time we compile, if the `DepNode::CodegenUnit(P)` is
867 /// judged to be clean (which means none of the things we read to
868 /// generate the partition were found to be dirty), it will be loaded
869 /// into previous work products. We will then regenerate the set of
870 /// symbols in the partition P and hash them (note that new symbols
871 /// may be added -- for example, new monomorphizations -- even if
872 /// nothing in P changed!). We will compare that hash against the
873 /// previous hash. If it matches up, we can reuse the object file.
874 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
875 pub struct WorkProduct {
876 pub cgu_name: String,
877 /// Saved files associated with this CGU.
878 pub saved_files: Vec<(WorkProductFileKind, String)>,
881 #[derive(Clone, Copy, Debug, RustcEncodable, RustcDecodable, PartialEq)]
882 pub enum WorkProductFileKind {
889 struct DepNodeData<K> {
892 fingerprint: Fingerprint,
895 /// `CurrentDepGraph` stores the dependency graph for the current session.
896 /// It will be populated as we run queries or tasks.
898 /// The nodes in it are identified by an index (`DepNodeIndex`).
899 /// The data for each node is stored in its `DepNodeData`, found in the `data` field.
901 /// We never remove nodes from the graph: they are only added.
903 /// This struct uses two locks internally. The `data` and `node_to_node_index` fields are
904 /// locked separately. Operations that take a `DepNodeIndex` typically just access
907 /// The only operation that must manipulate both locks is adding new nodes, in which case
908 /// we first acquire the `node_to_node_index` lock and then, once a new node is to be inserted,
909 /// acquire the lock on `data.`
910 pub(super) struct CurrentDepGraph<K> {
911 data: Lock<IndexVec<DepNodeIndex, DepNodeData<K>>>,
912 node_to_node_index: Sharded<FxHashMap<DepNode<K>, DepNodeIndex>>,
914 /// Used to trap when a specific edge is added to the graph.
915 /// This is used for debug purposes and is only active with `debug_assertions`.
917 forbidden_edge: Option<EdgeFilter>,
919 /// Anonymous `DepNode`s are nodes whose IDs we compute from the list of
920 /// their edges. This has the beneficial side-effect that multiple anonymous
921 /// nodes can be coalesced into one without changing the semantics of the
922 /// dependency graph. However, the merging of nodes can lead to a subtle
923 /// problem during red-green marking: The color of an anonymous node from
924 /// the current session might "shadow" the color of the node with the same
925 /// ID from the previous session. In order to side-step this problem, we make
926 /// sure that anonymous `NodeId`s allocated in different sessions don't overlap.
927 /// This is implemented by mixing a session-key into the ID fingerprint of
928 /// each anon node. The session-key is just a random number generated when
929 /// the `DepGraph` is created.
930 anon_id_seed: Fingerprint,
932 /// These are simple counters that are for profiling and
933 /// debugging and only active with `debug_assertions`.
934 total_read_count: AtomicU64,
935 total_duplicate_read_count: AtomicU64,
938 impl<K: DepKind> CurrentDepGraph<K> {
939 fn new(prev_graph_node_count: usize) -> CurrentDepGraph<K> {
940 use std::time::{SystemTime, UNIX_EPOCH};
942 let duration = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
943 let nanos = duration.as_secs() * 1_000_000_000 + duration.subsec_nanos() as u64;
944 let mut stable_hasher = StableHasher::new();
945 nanos.hash(&mut stable_hasher);
947 let forbidden_edge = if cfg!(debug_assertions) {
948 match env::var("RUST_FORBID_DEP_GRAPH_EDGE") {
949 Ok(s) => match EdgeFilter::new(&s) {
951 Err(err) => panic!("RUST_FORBID_DEP_GRAPH_EDGE invalid: {}", err),
959 // Pre-allocate the dep node structures. We over-allocate a little so
960 // that we hopefully don't have to re-allocate during this compilation
961 // session. The over-allocation is 2% plus a small constant to account
962 // for the fact that in very small crates 2% might not be enough.
963 let new_node_count_estimate = (prev_graph_node_count * 102) / 100 + 200;
966 data: Lock::new(IndexVec::with_capacity(new_node_count_estimate)),
967 node_to_node_index: Sharded::new(|| {
968 FxHashMap::with_capacity_and_hasher(
969 new_node_count_estimate / sharded::SHARDS,
973 anon_id_seed: stable_hasher.finish(),
975 total_read_count: AtomicU64::new(0),
976 total_duplicate_read_count: AtomicU64::new(0),
983 task_deps: TaskDeps<K>,
984 fingerprint: Fingerprint,
986 self.alloc_node(node, task_deps.reads, fingerprint)
989 fn complete_anon_task(&self, kind: K, task_deps: TaskDeps<K>) -> DepNodeIndex {
990 debug_assert!(!kind.is_eval_always());
992 let mut hasher = StableHasher::new();
994 // The dep node indices are hashed here instead of hashing the dep nodes of the
995 // dependencies. These indices may refer to different nodes per session, but this isn't
996 // a problem here because we that ensure the final dep node hash is per session only by
997 // combining it with the per session random number `anon_id_seed`. This hash only need
998 // to map the dependencies to a single value on a per session basis.
999 task_deps.reads.hash(&mut hasher);
1001 let target_dep_node = DepNode {
1004 // Fingerprint::combine() is faster than sending Fingerprint
1005 // through the StableHasher (at least as long as StableHasher
1007 hash: self.anon_id_seed.combine(hasher.finish()),
1010 self.intern_node(target_dep_node, task_deps.reads, Fingerprint::ZERO)
1015 dep_node: DepNode<K>,
1017 fingerprint: Fingerprint,
1020 !self.node_to_node_index.get_shard_by_value(&dep_node).lock().contains_key(&dep_node)
1022 self.intern_node(dep_node, edges, fingerprint)
1027 dep_node: DepNode<K>,
1029 fingerprint: Fingerprint,
1031 match self.node_to_node_index.get_shard_by_value(&dep_node).lock().entry(dep_node) {
1032 Entry::Occupied(entry) => *entry.get(),
1033 Entry::Vacant(entry) => {
1034 let mut data = self.data.lock();
1035 let dep_node_index = DepNodeIndex::new(data.len());
1036 data.push(DepNodeData { node: dep_node, edges, fingerprint });
1037 entry.insert(dep_node_index);
1044 impl<K: DepKind> DepGraphData<K> {
1046 fn read_index(&self, source: DepNodeIndex) {
1047 K::read_deps(|task_deps| {
1048 if let Some(task_deps) = task_deps {
1049 let mut task_deps = task_deps.lock();
1050 let task_deps = &mut *task_deps;
1051 if cfg!(debug_assertions) {
1052 self.current.total_read_count.fetch_add(1, Relaxed);
1055 // As long as we only have a low number of reads we can avoid doing a hash
1056 // insert and potentially allocating/reallocating the hashmap
1057 let new_read = if task_deps.reads.len() < TASK_DEPS_READS_CAP {
1058 task_deps.reads.iter().all(|other| *other != source)
1060 task_deps.read_set.insert(source)
1063 task_deps.reads.push(source);
1064 if task_deps.reads.len() == TASK_DEPS_READS_CAP {
1065 // Fill `read_set` with what we have so far so we can use the hashset next
1067 task_deps.read_set.extend(task_deps.reads.iter().copied());
1070 #[cfg(debug_assertions)]
1072 if let Some(target) = task_deps.node {
1073 let data = self.current.data.lock();
1074 if let Some(ref forbidden_edge) = self.current.forbidden_edge {
1075 let source = data[source].node;
1076 if forbidden_edge.test(&source, &target) {
1077 panic!("forbidden edge {:?} -> {:?} created", source, target)
1082 } else if cfg!(debug_assertions) {
1083 self.current.total_duplicate_read_count.fetch_add(1, Relaxed);
1090 /// The capacity of the `reads` field `SmallVec`
1091 const TASK_DEPS_READS_CAP: usize = 8;
1092 type EdgesVec = SmallVec<[DepNodeIndex; TASK_DEPS_READS_CAP]>;
1094 pub struct TaskDeps<K> {
1095 #[cfg(debug_assertions)]
1096 node: Option<DepNode<K>>,
1098 read_set: FxHashSet<DepNodeIndex>,
1099 phantom_data: PhantomData<DepNode<K>>,
1102 impl<K> Default for TaskDeps<K> {
1103 fn default() -> Self {
1105 #[cfg(debug_assertions)]
1107 reads: EdgesVec::new(),
1108 read_set: FxHashSet::default(),
1109 phantom_data: PhantomData,
1114 // A data structure that stores Option<DepNodeColor> values as a contiguous
1115 // array, using one u32 per entry.
1116 struct DepNodeColorMap {
1117 values: IndexVec<SerializedDepNodeIndex, AtomicU32>,
1120 const COMPRESSED_NONE: u32 = 0;
1121 const COMPRESSED_RED: u32 = 1;
1122 const COMPRESSED_FIRST_GREEN: u32 = 2;
1124 impl DepNodeColorMap {
1125 fn new(size: usize) -> DepNodeColorMap {
1126 DepNodeColorMap { values: (0..size).map(|_| AtomicU32::new(COMPRESSED_NONE)).collect() }
1129 fn get(&self, index: SerializedDepNodeIndex) -> Option<DepNodeColor> {
1130 match self.values[index].load(Ordering::Acquire) {
1131 COMPRESSED_NONE => None,
1132 COMPRESSED_RED => Some(DepNodeColor::Red),
1134 Some(DepNodeColor::Green(DepNodeIndex::from_u32(value - COMPRESSED_FIRST_GREEN)))
1139 fn insert(&self, index: SerializedDepNodeIndex, color: DepNodeColor) {
1140 self.values[index].store(
1142 DepNodeColor::Red => COMPRESSED_RED,
1143 DepNodeColor::Green(index) => index.as_u32() + COMPRESSED_FIRST_GREEN,