use std::hash::Hash; use std::mem; use rustc_data_structures::hash_table::{Entry, HashTable}; use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_data_structures::{outline, sharded, sync}; use rustc_errors::{Diag, FatalError, StashKey}; use rustc_middle::dep_graph::{DepGraphData, DepNodeKey}; use rustc_middle::query::{ ActiveKeyStatus, CycleError, CycleErrorHandling, QueryCache, QueryJob, QueryJobId, QueryLatch, QueryMode, QueryStackDeferred, QueryStackFrame, QueryState, }; use rustc_middle::ty::TyCtxt; use rustc_middle::verify_ich::incremental_verify_ich; use rustc_span::{DUMMY_SP, Span}; use crate::dep_graph::{DepNode, DepNodeIndex}; use crate::job::{QueryJobInfo, QueryJobMap, find_cycle_in_stack, report_cycle}; use crate::plumbing::{ collect_active_jobs_from_all_queries, current_query_job, next_job_id, start_query, }; use crate::{QueryFlags, SemiDynamicQueryDispatcher}; #[inline] fn equivalent_key(k: &K) -> impl Fn(&(K, V)) -> bool + '_ { move |x| x.0 == *k } /// Obtains the enclosed [`QueryJob`], or panics if this query evaluation /// was poisoned by a panic. fn expect_job<'tcx>(status: ActiveKeyStatus<'tcx>) -> QueryJob<'tcx> { match status { ActiveKeyStatus::Started(job) => job, ActiveKeyStatus::Poisoned => { panic!("job for query failed to start and was poisoned") } } } pub(crate) fn all_inactive<'tcx, K>(state: &QueryState<'tcx, K>) -> bool { state.active.lock_shards().all(|shard| shard.is_empty()) } /// Internal plumbing for collecting the set of active jobs for this query. /// /// Should only be called from `gather_active_jobs`. pub(crate) fn gather_active_jobs_inner<'tcx, K: Copy>( state: &QueryState<'tcx, K>, tcx: TyCtxt<'tcx>, make_frame: fn(TyCtxt<'tcx>, K) -> QueryStackFrame>, require_complete: bool, job_map_out: &mut QueryJobMap<'tcx>, // Out-param; job info is gathered into this map ) -> Option<()> { let mut active = Vec::new(); // Helper to gather active jobs from a single shard. let mut gather_shard_jobs = |shard: &HashTable<(K, ActiveKeyStatus<'tcx>)>| { for (k, v) in shard.iter() { if let ActiveKeyStatus::Started(ref job) = *v { active.push((*k, job.clone())); } } }; // Lock shards and gather jobs from each shard. if require_complete { for shard in state.active.lock_shards() { gather_shard_jobs(&shard); } } else { // We use try_lock_shards here since we are called from the // deadlock handler, and this shouldn't be locked. for shard in state.active.try_lock_shards() { let shard = shard?; gather_shard_jobs(&shard); } } // Call `make_frame` while we're not holding a `state.active` lock as `make_frame` may call // queries leading to a deadlock. for (key, job) in active { let frame = make_frame(tcx, key); job_map_out.insert(job.id, QueryJobInfo { frame, job }); } Some(()) } /// Guard object representing the responsibility to execute a query job and /// mark it as completed. /// /// This will poison the relevant query key if it is dropped without calling /// [`Self::complete`]. struct ActiveJobGuard<'tcx, K> where K: Eq + Hash + Copy, { state: &'tcx QueryState<'tcx, K>, key: K, key_hash: u64, } #[cold] #[inline(never)] fn mk_cycle<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, cycle_error: CycleError, ) -> C::Value { let error = report_cycle(tcx.sess, &cycle_error); handle_cycle_error(query, tcx, &cycle_error, error) } fn handle_cycle_error<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, cycle_error: &CycleError, error: Diag<'_>, ) -> C::Value { match query.cycle_error_handling() { CycleErrorHandling::Error => { let guar = error.emit(); query.value_from_cycle_error(tcx, cycle_error, guar) } CycleErrorHandling::Fatal => { error.emit(); tcx.dcx().abort_if_errors(); unreachable!() } CycleErrorHandling::DelayBug => { let guar = error.delay_as_bug(); query.value_from_cycle_error(tcx, cycle_error, guar) } CycleErrorHandling::Stash => { let guar = if let Some(root) = cycle_error.cycle.first() && let Some(span) = root.frame.info.span { error.stash(span, StashKey::Cycle).unwrap() } else { error.emit() }; query.value_from_cycle_error(tcx, cycle_error, guar) } } } impl<'tcx, K> ActiveJobGuard<'tcx, K> where K: Eq + Hash + Copy, { /// Completes the query by updating the query cache with the `result`, /// signals the waiter, and forgets the guard so it won't poison the query. fn complete(self, cache: &C, result: C::Value, dep_node_index: DepNodeIndex) where C: QueryCache, { // Forget ourself so our destructor won't poison the query. // (Extract fields by value first to make sure we don't leak anything.) let Self { state, key, key_hash }: Self = self; mem::forget(self); // Mark as complete before we remove the job from the active state // so no other thread can re-execute this query. cache.complete(key, result, dep_node_index); let job = { // don't keep the lock during the `unwrap()` of the retrieved value, or we taint the // underlying shard. // since unwinding also wants to look at this map, this can also prevent a double // panic. let mut shard = state.active.lock_shard_by_hash(key_hash); match shard.find_entry(key_hash, equivalent_key(&key)) { Err(_) => None, Ok(occupied) => Some(occupied.remove().0.1), } }; let job = expect_job(job.expect("active query job entry")); job.signal_complete(); } } impl<'tcx, K> Drop for ActiveJobGuard<'tcx, K> where K: Eq + Hash + Copy, { #[inline(never)] #[cold] fn drop(&mut self) { // Poison the query so jobs waiting on it panic. let Self { state, key, key_hash } = *self; let job = { let mut shard = state.active.lock_shard_by_hash(key_hash); match shard.find_entry(key_hash, equivalent_key(&key)) { Err(_) => panic!(), Ok(occupied) => { let ((key, value), vacant) = occupied.remove(); vacant.insert((key, ActiveKeyStatus::Poisoned)); expect_job(value) } } }; // Also signal the completion of the job, so waiters // will continue execution. job.signal_complete(); } } #[cold] #[inline(never)] fn cycle_error<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, try_execute: QueryJobId, span: Span, ) -> (C::Value, Option) { // Ensure there was no errors collecting all active jobs. // We need the complete map to ensure we find a cycle to break. let job_map = collect_active_jobs_from_all_queries(tcx, false) .ok() .expect("failed to collect active queries"); let error = find_cycle_in_stack(try_execute, job_map, ¤t_query_job(tcx), span); (mk_cycle(query, tcx, error.lift()), None) } #[inline(always)] fn wait_for_query<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, span: Span, key: C::Key, latch: QueryLatch<'tcx>, current: Option, ) -> (C::Value, Option) { // For parallel queries, we'll block and wait until the query running // in another thread has completed. Record how long we wait in the // self-profiler. let query_blocked_prof_timer = tcx.prof.query_blocked(); // With parallel queries we might just have to wait on some other // thread. let result = latch.wait_on(tcx, current, span); match result { Ok(()) => { let Some((v, index)) = query.query_cache(tcx).lookup(&key) else { outline(|| { // We didn't find the query result in the query cache. Check if it was // poisoned due to a panic instead. let key_hash = sharded::make_hash(&key); let shard = query.query_state(tcx).active.lock_shard_by_hash(key_hash); match shard.find(key_hash, equivalent_key(&key)) { // The query we waited on panicked. Continue unwinding here. Some((_, ActiveKeyStatus::Poisoned)) => FatalError.raise(), _ => panic!( "query '{}' result must be in the cache or the query must be poisoned after a wait", query.name() ), } }) }; tcx.prof.query_cache_hit(index.into()); query_blocked_prof_timer.finish_with_query_invocation_id(index.into()); (v, Some(index)) } Err(cycle) => (mk_cycle(query, tcx, cycle.lift()), None), } } #[inline(never)] fn try_execute_query<'tcx, C: QueryCache, const FLAGS: QueryFlags, const INCR: bool>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, span: Span, key: C::Key, dep_node: Option, ) -> (C::Value, Option) { let state = query.query_state(tcx); let key_hash = sharded::make_hash(&key); let mut state_lock = state.active.lock_shard_by_hash(key_hash); // For the parallel compiler we need to check both the query cache and query state structures // while holding the state lock to ensure that 1) the query has not yet completed and 2) the // query is not still executing. Without checking the query cache here, we can end up // re-executing the query since `try_start` only checks that the query is not currently // executing, but another thread may have already completed the query and stores it result // in the query cache. if tcx.sess.threads() > 1 { if let Some((value, index)) = query.query_cache(tcx).lookup(&key) { tcx.prof.query_cache_hit(index.into()); return (value, Some(index)); } } let current_job_id = current_query_job(tcx); match state_lock.entry(key_hash, equivalent_key(&key), |(k, _)| sharded::make_hash(k)) { Entry::Vacant(entry) => { // Nothing has computed or is computing the query, so we start a new job and insert it in the // state map. let id = next_job_id(tcx); let job = QueryJob::new(id, span, current_job_id); entry.insert((key, ActiveKeyStatus::Started(job))); // Drop the lock before we start executing the query drop(state_lock); execute_job::(query, tcx, state, key, key_hash, id, dep_node) } Entry::Occupied(mut entry) => { match &mut entry.get_mut().1 { ActiveKeyStatus::Started(job) => { if sync::is_dyn_thread_safe() { // Get the latch out let latch = job.latch(); drop(state_lock); // Only call `wait_for_query` if we're using a Rayon thread pool // as it will attempt to mark the worker thread as blocked. return wait_for_query(query, tcx, span, key, latch, current_job_id); } let id = job.id; drop(state_lock); // If we are single-threaded we know that we have cycle error, // so we just return the error. cycle_error(query, tcx, id, span) } ActiveKeyStatus::Poisoned => FatalError.raise(), } } } } #[inline(always)] fn execute_job<'tcx, C: QueryCache, const FLAGS: QueryFlags, const INCR: bool>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, state: &'tcx QueryState<'tcx, C::Key>, key: C::Key, key_hash: u64, id: QueryJobId, dep_node: Option, ) -> (C::Value, Option) { // Set up a guard object that will automatically poison the query if a // panic occurs while executing the query (or any intermediate plumbing). let job_guard = ActiveJobGuard { state, key, key_hash }; debug_assert_eq!(tcx.dep_graph.is_fully_enabled(), INCR); // Delegate to another function to actually execute the query job. let (result, dep_node_index) = if INCR { execute_job_incr(query, tcx, key, dep_node, id) } else { execute_job_non_incr(query, tcx, key, id) }; let cache = query.query_cache(tcx); if query.feedable() { // We should not compute queries that also got a value via feeding. // This can't happen, as query feeding adds the very dependencies to the fed query // as its feeding query had. So if the fed query is red, so is its feeder, which will // get evaluated first, and re-feed the query. if let Some((cached_result, _)) = cache.lookup(&key) { let Some(hasher) = query.hash_result() else { panic!( "no_hash fed query later has its value computed.\n\ Remove `no_hash` modifier to allow recomputation.\n\ The already cached value: {}", (query.format_value())(&cached_result) ); }; let (old_hash, new_hash) = tcx.with_stable_hashing_context(|mut hcx| { (hasher(&mut hcx, &cached_result), hasher(&mut hcx, &result)) }); let formatter = query.format_value(); if old_hash != new_hash { // We have an inconsistency. This can happen if one of the two // results is tainted by errors. assert!( tcx.dcx().has_errors().is_some(), "Computed query value for {:?}({:?}) is inconsistent with fed value,\n\ computed={:#?}\nfed={:#?}", query.dep_kind(), key, formatter(&result), formatter(&cached_result), ); } } } // Tell the guard to perform completion bookkeeping, and also to not poison the query. job_guard.complete(cache, result, dep_node_index); (result, Some(dep_node_index)) } // Fast path for when incr. comp. is off. #[inline(always)] fn execute_job_non_incr<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, key: C::Key, job_id: QueryJobId, ) -> (C::Value, DepNodeIndex) { debug_assert!(!tcx.dep_graph.is_fully_enabled()); // Fingerprint the key, just to assert that it doesn't // have anything we don't consider hashable if cfg!(debug_assertions) { let _ = key.to_fingerprint(tcx); } let prof_timer = tcx.prof.query_provider(); // Call the query provider. let result = start_query(tcx, job_id, query.depth_limit(), || query.invoke_provider(tcx, key)); let dep_node_index = tcx.dep_graph.next_virtual_depnode_index(); prof_timer.finish_with_query_invocation_id(dep_node_index.into()); // Similarly, fingerprint the result to assert that // it doesn't have anything not considered hashable. if cfg!(debug_assertions) && let Some(hash_result) = query.hash_result() { tcx.with_stable_hashing_context(|mut hcx| { hash_result(&mut hcx, &result); }); } (result, dep_node_index) } #[inline(always)] fn execute_job_incr<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, key: C::Key, mut dep_node_opt: Option, job_id: QueryJobId, ) -> (C::Value, DepNodeIndex) { let dep_graph_data = tcx.dep_graph.data().expect("should always be present in incremental mode"); if !query.anon() && !query.eval_always() { // `to_dep_node` is expensive for some `DepKind`s. let dep_node = dep_node_opt.get_or_insert_with(|| query.construct_dep_node(tcx, &key)); // The diagnostics for this query will be promoted to the current session during // `try_mark_green()`, so we can ignore them here. if let Some(ret) = start_query(tcx, job_id, false, || { try_load_from_disk_and_cache_in_memory(query, dep_graph_data, tcx, &key, dep_node) }) { return ret; } } let prof_timer = tcx.prof.query_provider(); let (result, dep_node_index) = start_query(tcx, job_id, query.depth_limit(), || { if query.anon() { // Call the query provider inside an anon task. return dep_graph_data .with_anon_task_inner(tcx, query.dep_kind(), || query.invoke_provider(tcx, key)); } // `to_dep_node` is expensive for some `DepKind`s. let dep_node = dep_node_opt.unwrap_or_else(|| query.construct_dep_node(tcx, &key)); // Call the query provider. dep_graph_data.with_task( dep_node, tcx, (query, key), |tcx, (query, key)| query.invoke_provider(tcx, key), query.hash_result(), ) }); prof_timer.finish_with_query_invocation_id(dep_node_index.into()); (result, dep_node_index) } #[inline(always)] fn try_load_from_disk_and_cache_in_memory<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, dep_graph_data: &DepGraphData, tcx: TyCtxt<'tcx>, key: &C::Key, dep_node: &DepNode, ) -> Option<(C::Value, DepNodeIndex)> { // Note this function can be called concurrently from the same query // We must ensure that this is handled correctly. let (prev_dep_node_index, dep_node_index) = dep_graph_data.try_mark_green(tcx, dep_node)?; debug_assert!(dep_graph_data.is_index_green(prev_dep_node_index)); // First we try to load the result from the on-disk cache. // Some things are never cached on disk. if let Some(result) = query.try_load_from_disk(tcx, key, prev_dep_node_index, dep_node_index) { if std::intrinsics::unlikely(tcx.sess.opts.unstable_opts.query_dep_graph) { dep_graph_data.mark_debug_loaded_from_disk(*dep_node) } let prev_fingerprint = dep_graph_data.prev_fingerprint_of(prev_dep_node_index); // If `-Zincremental-verify-ich` is specified, re-hash results from // the cache and make sure that they have the expected fingerprint. // // If not, we still seek to verify a subset of fingerprints loaded // from disk. Re-hashing results is fairly expensive, so we can't // currently afford to verify every hash. This subset should still // give us some coverage of potential bugs though. let try_verify = prev_fingerprint.split().1.as_u64().is_multiple_of(32); if std::intrinsics::unlikely( try_verify || tcx.sess.opts.unstable_opts.incremental_verify_ich, ) { incremental_verify_ich( tcx, dep_graph_data, &result, prev_dep_node_index, query.hash_result(), query.format_value(), ); } return Some((result, dep_node_index)); } // We always expect to find a cached result for things that // can be forced from `DepNode`. debug_assert!( !query.will_cache_on_disk_for_key(tcx, key) || !tcx.fingerprint_style(dep_node.kind).reconstructible(), "missing on-disk cache entry for {dep_node:?}" ); // Sanity check for the logic in `ensure`: if the node is green and the result loadable, // we should actually be able to load it. debug_assert!( !query.is_loadable_from_disk(tcx, key, prev_dep_node_index), "missing on-disk cache entry for loadable {dep_node:?}" ); // We could not load a result from the on-disk cache, so // recompute. let prof_timer = tcx.prof.query_provider(); // The dep-graph for this computation is already in-place. // Call the query provider. let result = tcx.dep_graph.with_ignore(|| query.invoke_provider(tcx, *key)); prof_timer.finish_with_query_invocation_id(dep_node_index.into()); // Verify that re-running the query produced a result with the expected hash // This catches bugs in query implementations, turning them into ICEs. // For example, a query might sort its result by `DefId` - since `DefId`s are // not stable across compilation sessions, the result could get up getting sorted // in a different order when the query is re-run, even though all of the inputs // (e.g. `DefPathHash` values) were green. // // See issue #82920 for an example of a miscompilation that would get turned into // an ICE by this check incremental_verify_ich( tcx, dep_graph_data, &result, prev_dep_node_index, query.hash_result(), query.format_value(), ); Some((result, dep_node_index)) } /// Ensure that either this query has all green inputs or been executed. /// Executing `query::ensure(D)` is considered a read of the dep-node `D`. /// Returns true if the query should still run. /// /// This function is particularly useful when executing passes for their /// side-effects -- e.g., in order to report errors for erroneous programs. /// /// Note: The optimization is only available during incr. comp. #[inline(never)] fn ensure_must_run<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, key: &C::Key, check_cache: bool, ) -> (bool, Option) { if query.eval_always() { return (true, None); } // Ensuring an anonymous query makes no sense assert!(!query.anon()); let dep_node = query.construct_dep_node(tcx, key); let dep_graph = &tcx.dep_graph; let serialized_dep_node_index = match dep_graph.try_mark_green(tcx, &dep_node) { None => { // A None return from `try_mark_green` means that this is either // a new dep node or that the dep node has already been marked red. // Either way, we can't call `dep_graph.read()` as we don't have the // DepNodeIndex. We must invoke the query itself. The performance cost // this introduces should be negligible as we'll immediately hit the // in-memory cache, or another query down the line will. return (true, Some(dep_node)); } Some((serialized_dep_node_index, dep_node_index)) => { dep_graph.read_index(dep_node_index); tcx.prof.query_cache_hit(dep_node_index.into()); serialized_dep_node_index } }; // We do not need the value at all, so do not check the cache. if !check_cache { return (false, None); } let loadable = query.is_loadable_from_disk(tcx, key, serialized_dep_node_index); (!loadable, Some(dep_node)) } #[inline(always)] pub(super) fn get_query_non_incr<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, span: Span, key: C::Key, ) -> C::Value { debug_assert!(!tcx.dep_graph.is_fully_enabled()); ensure_sufficient_stack(|| try_execute_query::(query, tcx, span, key, None).0) } #[inline(always)] pub(super) fn get_query_incr<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, span: Span, key: C::Key, mode: QueryMode, ) -> Option { debug_assert!(tcx.dep_graph.is_fully_enabled()); let dep_node = if let QueryMode::Ensure { check_cache } = mode { let (must_run, dep_node) = ensure_must_run(query, tcx, &key, check_cache); if !must_run { return None; } dep_node } else { None }; let (result, dep_node_index) = ensure_sufficient_stack(|| { try_execute_query::(query, tcx, span, key, dep_node) }); if let Some(dep_node_index) = dep_node_index { tcx.dep_graph.read_index(dep_node_index) } Some(result) } pub(crate) fn force_query<'tcx, C: QueryCache, const FLAGS: QueryFlags>( query: SemiDynamicQueryDispatcher<'tcx, C, FLAGS>, tcx: TyCtxt<'tcx>, key: C::Key, dep_node: DepNode, ) { // We may be concurrently trying both execute and force a query. // Ensure that only one of them runs the query. if let Some((_, index)) = query.query_cache(tcx).lookup(&key) { tcx.prof.query_cache_hit(index.into()); return; } debug_assert!(!query.anon()); ensure_sufficient_stack(|| { try_execute_query::(query, tcx, DUMMY_SP, key, Some(dep_node)) }); }