diff --git a/compiler/rustc_ast_lowering/src/index.rs b/compiler/rustc_ast_lowering/src/index.rs index ce847906fb9..eff362f3ff0 100644 --- a/compiler/rustc_ast_lowering/src/index.rs +++ b/compiler/rustc_ast_lowering/src/index.rs @@ -2,19 +2,17 @@ use rustc_data_structures::sorted_map::SortedMap; use rustc_hir as hir; use rustc_hir::def_id::LocalDefId; -use rustc_hir::definitions; use rustc_hir::intravisit::{self, Visitor}; use rustc_hir::*; use rustc_index::{Idx, IndexVec}; use rustc_middle::span_bug; -use rustc_session::Session; -use rustc_span::source_map::SourceMap; +use rustc_middle::ty::TyCtxt; use rustc_span::{Span, DUMMY_SP}; /// A visitor that walks over the HIR and collects `Node`s into a HIR map. pub(super) struct NodeCollector<'a, 'hir> { - /// Source map - source_map: &'a SourceMap, + tcx: TyCtxt<'hir>, + bodies: &'a SortedMap>, /// Outputs @@ -25,14 +23,11 @@ pub(super) struct NodeCollector<'a, 'hir> { parent_node: hir::ItemLocalId, owner: OwnerId, - - definitions: &'a definitions::Definitions, } -#[instrument(level = "debug", skip(sess, definitions, bodies))] +#[instrument(level = "debug", skip(tcx, bodies))] pub(super) fn index_hir<'hir>( - sess: &Session, - definitions: &definitions::Definitions, + tcx: TyCtxt<'hir>, item: hir::OwnerNode<'hir>, bodies: &SortedMap>, ) -> (IndexVec>>, FxHashMap) { @@ -42,8 +37,7 @@ pub(super) fn index_hir<'hir>( // used. nodes.push(Some(ParentedNode { parent: ItemLocalId::INVALID, node: item.into() })); let mut collector = NodeCollector { - source_map: sess.source_map(), - definitions, + tcx, owner: item.def_id(), parent_node: ItemLocalId::new(0), nodes, @@ -79,11 +73,17 @@ fn insert(&mut self, span: Span, hir_id: HirId, node: Node<'hir>) { span, "inconsistent HirId at `{:?}` for `{:?}`: \ current_dep_node_owner={} ({:?}), hir_id.owner={} ({:?})", - self.source_map.span_to_diagnostic_string(span), + self.tcx.sess.source_map().span_to_diagnostic_string(span), node, - self.definitions.def_path(self.owner.def_id).to_string_no_crate_verbose(), + self.tcx + .definitions_untracked() + .def_path(self.owner.def_id) + .to_string_no_crate_verbose(), self.owner, - self.definitions.def_path(hir_id.owner.def_id).to_string_no_crate_verbose(), + self.tcx + .definitions_untracked() + .def_path(hir_id.owner.def_id) + .to_string_no_crate_verbose(), hir_id.owner, ) } diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs index a6d1ef33f40..41db61d391a 100644 --- a/compiler/rustc_ast_lowering/src/lib.rs +++ b/compiler/rustc_ast_lowering/src/lib.rs @@ -671,8 +671,7 @@ fn make_owner_info(&mut self, node: hir::OwnerNode<'hir>) -> &'hir hir::OwnerInf } else { (None, None) }; - let (nodes, parenting) = - index::index_hir(self.tcx.sess, &*self.tcx.definitions_untracked(), node, &bodies); + let (nodes, parenting) = index::index_hir(self.tcx, node, &bodies); let nodes = hir::OwnerNodes { opt_hash_including_bodies, nodes, bodies }; let attrs = hir::AttributeMap { map: attrs, opt_hash: attrs_hash }; diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs index e82b0f6d496..8eda9043e35 100644 --- a/compiler/rustc_data_structures/src/sync.rs +++ b/compiler/rustc_data_structures/src/sync.rs @@ -61,6 +61,9 @@ mod vec; +mod freeze; +pub use freeze::{FreezeLock, FreezeReadGuard, FreezeWriteGuard}; + mod mode { use super::Ordering; use std::sync::atomic::AtomicU8; diff --git a/compiler/rustc_data_structures/src/sync/freeze.rs b/compiler/rustc_data_structures/src/sync/freeze.rs new file mode 100644 index 00000000000..d9f1d72d851 --- /dev/null +++ b/compiler/rustc_data_structures/src/sync/freeze.rs @@ -0,0 +1,108 @@ +use crate::sync::{AtomicBool, ReadGuard, RwLock, WriteGuard}; +#[cfg(parallel_compiler)] +use crate::sync::{DynSend, DynSync}; +use std::{ + cell::UnsafeCell, + marker::PhantomData, + ops::{Deref, DerefMut}, + sync::atomic::Ordering, +}; + +/// A type which allows mutation using a lock until +/// the value is frozen and can be accessed lock-free. +/// +/// Unlike `RwLock`, it can be used to prevent mutation past a point. +#[derive(Default)] +pub struct FreezeLock { + data: UnsafeCell, + frozen: AtomicBool, + + /// This lock protects writes to the `data` and `frozen` fields. + lock: RwLock<()>, +} + +#[cfg(parallel_compiler)] +unsafe impl DynSync for FreezeLock {} + +impl FreezeLock { + #[inline] + pub fn new(value: T) -> Self { + Self { data: UnsafeCell::new(value), frozen: AtomicBool::new(false), lock: RwLock::new(()) } + } + + #[inline] + pub fn read(&self) -> FreezeReadGuard<'_, T> { + FreezeReadGuard { + _lock_guard: if self.frozen.load(Ordering::Acquire) { + None + } else { + Some(self.lock.read()) + }, + lock: self, + } + } + + #[inline] + #[track_caller] + pub fn write(&self) -> FreezeWriteGuard<'_, T> { + let _lock_guard = self.lock.write(); + // Use relaxed ordering since we're in the write lock. + assert!(!self.frozen.load(Ordering::Relaxed), "still mutable"); + FreezeWriteGuard { _lock_guard, lock: self, marker: PhantomData } + } + + #[inline] + pub fn freeze(&self) -> &T { + if !self.frozen.load(Ordering::Acquire) { + // Get the lock to ensure no concurrent writes and that we release the latest write. + let _lock = self.lock.write(); + self.frozen.store(true, Ordering::Release); + } + + // SAFETY: This is frozen so the data cannot be modified and shared access is sound. + unsafe { &*self.data.get() } + } +} + +/// A guard holding shared access to a `FreezeLock` which is in a locked state or frozen. +#[must_use = "if unused the FreezeLock may immediately unlock"] +pub struct FreezeReadGuard<'a, T> { + _lock_guard: Option>, + lock: &'a FreezeLock, +} + +impl<'a, T: 'a> Deref for FreezeReadGuard<'a, T> { + type Target = T; + #[inline] + fn deref(&self) -> &T { + // SAFETY: If `lock` is not frozen, `_lock_guard` holds the lock to the `UnsafeCell` so + // this has shared access until the `FreezeReadGuard` is dropped. If `lock` is frozen, + // the data cannot be modified and shared access is sound. + unsafe { &*self.lock.data.get() } + } +} + +/// A guard holding mutable access to a `FreezeLock` which is in a locked state or frozen. +#[must_use = "if unused the FreezeLock may immediately unlock"] +pub struct FreezeWriteGuard<'a, T> { + _lock_guard: WriteGuard<'a, ()>, + lock: &'a FreezeLock, + marker: PhantomData<&'a mut T>, +} + +impl<'a, T: 'a> Deref for FreezeWriteGuard<'a, T> { + type Target = T; + #[inline] + fn deref(&self) -> &T { + // SAFETY: `self._lock_guard` holds the lock to the `UnsafeCell` so this has shared access. + unsafe { &*self.lock.data.get() } + } +} + +impl<'a, T: 'a> DerefMut for FreezeWriteGuard<'a, T> { + #[inline] + fn deref_mut(&mut self) -> &mut T { + // SAFETY: `self._lock_guard` holds the lock to the `UnsafeCell` so this has mutable access. + unsafe { &mut *self.lock.data.get() } + } +} diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs index 4f95174f869..b0f333b79ca 100644 --- a/compiler/rustc_hir_analysis/src/lib.rs +++ b/compiler/rustc_hir_analysis/src/lib.rs @@ -237,6 +237,10 @@ pub fn check_crate(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> { tcx.hir().for_each_module(|module| tcx.ensure().check_mod_item_types(module)) }); + // Freeze definitions as we don't add new ones at this point. This improves performance by + // allowing lock-free access to them. + tcx.untracked().definitions.freeze(); + // FIXME: Remove this when we implement creating `DefId`s // for anon constants during their parents' typeck. // Typeck all body owners in parallel will produce queries diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs index 2db7aa0e367..e0d9998d919 100644 --- a/compiler/rustc_interface/src/queries.rs +++ b/compiler/rustc_interface/src/queries.rs @@ -7,7 +7,9 @@ use rustc_codegen_ssa::CodegenResults; use rustc_data_structures::steal::Steal; use rustc_data_structures::svh::Svh; -use rustc_data_structures::sync::{AppendOnlyIndexVec, Lrc, OnceLock, RwLock, WorkerLocal}; +use rustc_data_structures::sync::{ + AppendOnlyIndexVec, FreezeLock, Lrc, OnceLock, RwLock, WorkerLocal, +}; use rustc_hir::def_id::{StableCrateId, CRATE_DEF_ID, LOCAL_CRATE}; use rustc_hir::definitions::Definitions; use rustc_incremental::DepGraphFuture; @@ -197,7 +199,7 @@ pub fn global_ctxt(&'tcx self) -> Result> self.codegen_backend().metadata_loader(), stable_crate_id, )) as _); - let definitions = RwLock::new(Definitions::new(stable_crate_id)); + let definitions = FreezeLock::new(Definitions::new(stable_crate_id)); let source_span = AppendOnlyIndexVec::new(); let _id = source_span.push(krate.spans.inner_span); debug_assert_eq!(_id, CRATE_DEF_ID); diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs index 3e8f07ed233..e20a202561f 100644 --- a/compiler/rustc_middle/src/hir/map/mod.rs +++ b/compiler/rustc_middle/src/hir/map/mod.rs @@ -1207,7 +1207,7 @@ pub(super) fn crate_hash(tcx: TyCtxt<'_>, _: LocalCrate) -> Svh { source_file_names.hash_stable(&mut hcx, &mut stable_hasher); debugger_visualizers.hash_stable(&mut hcx, &mut stable_hasher); if tcx.sess.opts.incremental_relative_spans() { - let definitions = tcx.definitions_untracked(); + let definitions = tcx.untracked().definitions.freeze(); let mut owner_spans: Vec<_> = krate .owners .iter_enumerated() diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs index e2f9e299566..90d847804f0 100644 --- a/compiler/rustc_middle/src/ty/context.rs +++ b/compiler/rustc_middle/src/ty/context.rs @@ -39,7 +39,9 @@ use rustc_data_structures::sharded::{IntoPointer, ShardedHashMap}; use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; use rustc_data_structures::steal::Steal; -use rustc_data_structures::sync::{self, Lock, Lrc, MappedReadGuard, ReadGuard, WorkerLocal}; +use rustc_data_structures::sync::{ + self, FreezeReadGuard, Lock, Lrc, MappedReadGuard, ReadGuard, WorkerLocal, +}; use rustc_data_structures::unord::UnordSet; use rustc_errors::{ DecorateLint, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed, MultiSpan, @@ -964,8 +966,8 @@ pub fn iter_local_def_id(self) -> impl Iterator + 'tcx { i += 1; } - // Leak a read lock once we finish iterating on definitions, to prevent adding new ones. - definitions.leak(); + // Freeze definitions once we finish iterating on them, to prevent adding new ones. + definitions.freeze(); }) } @@ -974,10 +976,9 @@ pub fn def_path_table(self) -> &'tcx rustc_hir::definitions::DefPathTable { // definitions change. self.dep_graph.read_index(DepNodeIndex::FOREVER_RED_NODE); - // Leak a read lock once we start iterating on definitions, to prevent adding new ones + // Freeze definitions once we start iterating on them, to prevent adding new ones // while iterating. If some query needs to add definitions, it should be `ensure`d above. - let definitions = self.untracked.definitions.leak(); - definitions.def_path_table() + self.untracked.definitions.freeze().def_path_table() } pub fn def_path_hash_to_def_index_map( @@ -986,10 +987,9 @@ pub fn def_path_hash_to_def_index_map( // Create a dependency to the crate to be sure we re-execute this when the amount of // definitions change. self.ensure().hir_crate(()); - // Leak a read lock once we start iterating on definitions, to prevent adding new ones + // Freeze definitions once we start iterating on them, to prevent adding new ones // while iterating. If some query needs to add definitions, it should be `ensure`d above. - let definitions = self.untracked.definitions.leak(); - definitions.def_path_hash_to_def_index_map() + self.untracked.definitions.freeze().def_path_hash_to_def_index_map() } /// Note that this is *untracked* and should only be used within the query @@ -1006,7 +1006,7 @@ pub fn untracked(self) -> &'tcx Untracked { /// Note that this is *untracked* and should only be used within the query /// system if the result is otherwise tracked through queries #[inline] - pub fn definitions_untracked(self) -> ReadGuard<'tcx, Definitions> { + pub fn definitions_untracked(self) -> FreezeReadGuard<'tcx, Definitions> { self.untracked.definitions.read() } diff --git a/compiler/rustc_session/src/cstore.rs b/compiler/rustc_session/src/cstore.rs index c53a355b533..90f57be9324 100644 --- a/compiler/rustc_session/src/cstore.rs +++ b/compiler/rustc_session/src/cstore.rs @@ -7,7 +7,7 @@ use crate::Session; use rustc_ast as ast; use rustc_data_structures::owned_slice::OwnedSlice; -use rustc_data_structures::sync::{self, AppendOnlyIndexVec, RwLock}; +use rustc_data_structures::sync::{self, AppendOnlyIndexVec, FreezeLock, RwLock}; use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, StableCrateId, LOCAL_CRATE}; use rustc_hir::definitions::{DefKey, DefPath, DefPathHash, Definitions}; use rustc_span::hygiene::{ExpnHash, ExpnId}; @@ -261,5 +261,5 @@ pub struct Untracked { pub cstore: RwLock>, /// Reference span for definitions. pub source_span: AppendOnlyIndexVec, - pub definitions: RwLock, + pub definitions: FreezeLock, }