Switch QueryJobId to a single global counter

This replaces the per-shard counters with a single global counter, simplifying
the JobId struct down to just a u64 and removing the need to pipe a DepKind
generic through a bunch of code. The performance implications on non-parallel
compilers are likely minimal (this switches to `Cell<u64>` as the backing
storage over a `u64`, but the latter was already inside a `RefCell` so it's not
really a significance divergence). On parallel compilers, the cost of a single
global u64 counter may be more significant: it adds a serialization point in
theory. On the other hand, we can imagine changing the counter to have a
thread-local component if it becomes worrisome or some similar structure.

The new design is sufficiently simpler that it warrants the potential for slight
changes down the line if/when we get parallel compilation to be more of a
default.

A u64 counter, instead of u32 (the old per-shard width), is chosen to avoid
possibly overflowing it and causing problems; it is effectively impossible that
we would overflow a u64 counter in this context.

Author: Mark-Simulacrum

compiler/rustc_middle/src/ty/context.rs

@@ -1668,7 +1668,7 @@ CloneLiftImpls! { for<'tcx> { Constness, traits::WellFormedLoc, } }
 pub mod tls {
     use super::{ptr_eq, GlobalCtxt, TyCtxt};
 
-    use crate::dep_graph::{DepKind, TaskDepsRef};
+    use crate::dep_graph::TaskDepsRef;
     use crate::ty::query;
     use rustc_data_structures::sync::{self, Lock};
     use rustc_data_structures::thin_vec::ThinVec;
@@ -1693,7 +1693,7 @@ pub mod tls {
 
         /// The current query job, if any. This is updated by `JobOwner::start` in
         /// `ty::query::plumbing` when executing a query.
-        pub query: Option<query::QueryJobId<DepKind>>,
+        pub query: Option<query::QueryJobId>,
 
         /// Where to store diagnostics for the current query job, if any.
         /// This is updated by `JobOwner::start` in `ty::query::plumbing` when executing a query.

compiler/rustc_query_impl/src/lib.rs

@@ -15,6 +15,7 @@ extern crate rustc_macros;
 extern crate rustc_middle;
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_data_structures::sync::AtomicU64;
 use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::{self, DepKindStruct, SerializedDepNodeIndex};
 use rustc_middle::ty::query::{query_keys, query_storage, query_stored, query_values};

compiler/rustc_query_impl/src/plumbing.rs

@@ -3,7 +3,7 @@
 //! manage the caches, and so forth.
 
 use crate::{on_disk_cache, Queries};
-use rustc_middle::dep_graph::{DepKind, DepNodeIndex, SerializedDepNodeIndex};
+use rustc_middle::dep_graph::{DepNodeIndex, SerializedDepNodeIndex};
 use rustc_middle::ty::tls::{self, ImplicitCtxt};
 use rustc_middle::ty::TyCtxt;
 use rustc_query_system::dep_graph::HasDepContext;
@@ -15,6 +15,7 @@ use rustc_errors::{Diagnostic, Handler};
 use rustc_serialize::opaque;
 
 use std::any::Any;
+use std::num::NonZeroU64;
 
 #[derive(Copy, Clone)]
 pub struct QueryCtxt<'tcx> {
@@ -42,11 +43,20 @@ impl<'tcx> HasDepContext for QueryCtxt<'tcx> {
 }
 
 impl QueryContext for QueryCtxt<'_> {
-    fn current_query_job(&self) -> Option<QueryJobId<Self::DepKind>> {
+    fn next_job_id(&self) -> QueryJobId {
+        QueryJobId(
+            NonZeroU64::new(
+                self.queries.jobs.fetch_add(1, rustc_data_structures::sync::Ordering::Relaxed),
+            )
+            .unwrap(),
+        )
+    }
+
+    fn current_query_job(&self) -> Option<QueryJobId> {
         tls::with_related_context(**self, |icx| icx.query)
     }
 
-    fn try_collect_active_jobs(&self) -> Option<QueryMap<Self::DepKind>> {
+    fn try_collect_active_jobs(&self) -> Option<QueryMap> {
         self.queries.try_collect_active_jobs(**self)
     }
 
@@ -81,7 +91,7 @@ impl QueryContext for QueryCtxt<'_> {
     #[inline(always)]
     fn start_query<R>(
         &self,
-        token: QueryJobId<Self::DepKind>,
+        token: QueryJobId,
         diagnostics: Option<&Lock<ThinVec<Diagnostic>>>,
         compute: impl FnOnce() -> R,
     ) -> R {
@@ -152,7 +162,7 @@ impl<'tcx> QueryCtxt<'tcx> {
 
     pub fn try_print_query_stack(
         self,
-        query: Option<QueryJobId<DepKind>>,
+        query: Option<QueryJobId>,
         handler: &Handler,
         num_frames: Option<usize>,
     ) -> usize {
@@ -320,7 +330,7 @@ macro_rules! define_queries {
             type Cache = query_storage::$name<$tcx>;
 
             #[inline(always)]
-            fn query_state<'a>(tcx: QueryCtxt<$tcx>) -> &'a QueryState<crate::dep_graph::DepKind, Self::Key>
+            fn query_state<'a>(tcx: QueryCtxt<$tcx>) -> &'a QueryState<Self::Key>
                 where QueryCtxt<$tcx>: 'a
             {
                 &tcx.queries.$name
@@ -471,10 +481,9 @@ macro_rules! define_queries_struct {
 
             pub on_disk_cache: Option<OnDiskCache<$tcx>>,
 
-            $($(#[$attr])*  $name: QueryState<
-                crate::dep_graph::DepKind,
-                query_keys::$name<$tcx>,
-            >,)*
+            jobs: AtomicU64,
+
+            $($(#[$attr])*  $name: QueryState<query_keys::$name<$tcx>>,)*
         }
 
         impl<$tcx> Queries<$tcx> {
@@ -487,21 +496,21 @@ macro_rules! define_queries_struct {
                     local_providers: Box::new(local_providers),
                     extern_providers: Box::new(extern_providers),
                     on_disk_cache,
+                    jobs: AtomicU64::new(1),
                     $($name: Default::default()),*
                 }
             }
 
             pub(crate) fn try_collect_active_jobs(
                 &$tcx self,
                 tcx: TyCtxt<$tcx>,
-            ) -> Option<QueryMap<crate::dep_graph::DepKind>> {
+            ) -> Option<QueryMap> {
                 let tcx = QueryCtxt { tcx, queries: self };
                 let mut jobs = QueryMap::default();
 
                 $(
                     self.$name.try_collect_active_jobs(
                         tcx,
-                        dep_graph::DepKind::$name,
                         make_query::$name,
                         &mut jobs,
                     )?;

compiler/rustc_query_system/src/query/config.rs

@@ -59,7 +59,7 @@ pub trait QueryDescription<CTX: QueryContext>: QueryConfig {
     fn describe(tcx: CTX, key: Self::Key) -> String;
 
     // Don't use this method to access query results, instead use the methods on TyCtxt
-    fn query_state<'a>(tcx: CTX) -> &'a QueryState<CTX::DepKind, Self::Key>
+    fn query_state<'a>(tcx: CTX) -> &'a QueryState<Self::Key>
     where
         CTX: 'a;
 

compiler/rustc_query_system/src/query/job.rs

@@ -7,13 +7,11 @@ use rustc_errors::{struct_span_err, Diagnostic, DiagnosticBuilder, Handler, Leve
 use rustc_session::Session;
 use rustc_span::Span;
 
-use std::convert::TryFrom;
 use std::hash::Hash;
-use std::num::NonZeroU32;
+use std::num::NonZeroU64;
 
 #[cfg(parallel_compiler)]
 use {
-    crate::dep_graph::DepKind,
     parking_lot::{Condvar, Mutex},
     rustc_data_structures::fx::FxHashSet,
     rustc_data_structures::sync::Lock,
@@ -33,80 +31,57 @@ pub struct QueryInfo {
     pub query: QueryStackFrame,
 }
 
-pub type QueryMap<D> = FxHashMap<QueryJobId<D>, QueryJobInfo<D>>;
-
-/// A value uniquely identifying an active query job within a shard in the query cache.
-#[derive(Copy, Clone, Eq, PartialEq, Hash)]
-pub struct QueryShardJobId(pub NonZeroU32);
+pub type QueryMap = FxHashMap<QueryJobId, QueryJobInfo>;
 
 /// A value uniquely identifying an active query job.
 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
-pub struct QueryJobId<D> {
-    /// Which job within a shard is this
-    pub job: QueryShardJobId,
-
-    /// In which shard is this job
-    pub shard: u16,
+pub struct QueryJobId(pub NonZeroU64);
 
-    /// What kind of query this job is.
-    pub kind: D,
-}
-
-impl<D> QueryJobId<D>
-where
-    D: Copy + Clone + Eq + Hash,
-{
-    pub fn new(job: QueryShardJobId, shard: usize, kind: D) -> Self {
-        QueryJobId { job, shard: u16::try_from(shard).unwrap(), kind }
-    }
-
-    fn query(self, map: &QueryMap<D>) -> QueryStackFrame {
+impl QueryJobId {
+    fn query(self, map: &QueryMap) -> QueryStackFrame {
         map.get(&self).unwrap().query.clone()
     }
 
     #[cfg(parallel_compiler)]
-    fn span(self, map: &QueryMap<D>) -> Span {
+    fn span(self, map: &QueryMap) -> Span {
         map.get(&self).unwrap().job.span
     }
 
     #[cfg(parallel_compiler)]
-    fn parent(self, map: &QueryMap<D>) -> Option<QueryJobId<D>> {
+    fn parent(self, map: &QueryMap) -> Option<QueryJobId> {
         map.get(&self).unwrap().job.parent
     }
 
     #[cfg(parallel_compiler)]
-    fn latch<'a>(self, map: &'a QueryMap<D>) -> Option<&'a QueryLatch<D>> {
+    fn latch<'a>(self, map: &'a QueryMap) -> Option<&'a QueryLatch> {
         map.get(&self).unwrap().job.latch.as_ref()
     }
 }
 
-pub struct QueryJobInfo<D> {
+pub struct QueryJobInfo {
     pub query: QueryStackFrame,
-    pub job: QueryJob<D>,
+    pub job: QueryJob,
 }
 
 /// Represents an active query job.
 #[derive(Clone)]
-pub struct QueryJob<D> {
-    pub id: QueryShardJobId,
+pub struct QueryJob {
+    pub id: QueryJobId,
 
     /// The span corresponding to the reason for which this query was required.
     pub span: Span,
 
     /// The parent query job which created this job and is implicitly waiting on it.
-    pub parent: Option<QueryJobId<D>>,
+    pub parent: Option<QueryJobId>,
 
     /// The latch that is used to wait on this job.
     #[cfg(parallel_compiler)]
-    latch: Option<QueryLatch<D>>,
+    latch: Option<QueryLatch>,
 }
 
-impl<D> QueryJob<D>
-where
-    D: Copy + Clone + Eq + Hash,
-{
+impl QueryJob {
     /// Creates a new query job.
-    pub fn new(id: QueryShardJobId, span: Span, parent: Option<QueryJobId<D>>) -> Self {
+    pub fn new(id: QueryJobId, span: Span, parent: Option<QueryJobId>) -> Self {
         QueryJob {
             id,
             span,
@@ -117,7 +92,7 @@ where
     }
 
     #[cfg(parallel_compiler)]
-    pub(super) fn latch(&mut self) -> QueryLatch<D> {
+    pub(super) fn latch(&mut self) -> QueryLatch {
         if self.latch.is_none() {
             self.latch = Some(QueryLatch::new());
         }
@@ -139,16 +114,13 @@ where
 }
 
 #[cfg(not(parallel_compiler))]
-impl<D> QueryJobId<D>
-where
-    D: Copy + Clone + Eq + Hash,
-{
+impl QueryJobId {
     #[cold]
     #[inline(never)]
     pub(super) fn find_cycle_in_stack(
         &self,
-        query_map: QueryMap<D>,
-        current_job: &Option<QueryJobId<D>>,
+        query_map: QueryMap,
+        current_job: &Option<QueryJobId>,
         span: Span,
     ) -> CycleError {
         // Find the waitee amongst `current_job` parents
@@ -184,50 +156,43 @@ where
 }
 
 #[cfg(parallel_compiler)]
-struct QueryWaiter<D> {
-    query: Option<QueryJobId<D>>,
+struct QueryWaiter {
+    query: Option<QueryJobId>,
     condvar: Condvar,
     span: Span,
     cycle: Lock<Option<CycleError>>,
 }
 
 #[cfg(parallel_compiler)]
-impl<D> QueryWaiter<D> {
+impl QueryWaiter {
     fn notify(&self, registry: &rayon_core::Registry) {
         rayon_core::mark_unblocked(registry);
         self.condvar.notify_one();
     }
 }
 
 #[cfg(parallel_compiler)]
-struct QueryLatchInfo<D> {
+struct QueryLatchInfo {
     complete: bool,
-    waiters: Vec<Lrc<QueryWaiter<D>>>,
+    waiters: Vec<Lrc<QueryWaiter>>,
 }
 
 #[cfg(parallel_compiler)]
 #[derive(Clone)]
-pub(super) struct QueryLatch<D> {
-    info: Lrc<Mutex<QueryLatchInfo<D>>>,
+pub(super) struct QueryLatch {
+    info: Lrc<Mutex<QueryLatchInfo>>,
 }
 
 #[cfg(parallel_compiler)]
-impl<D: Eq + Hash> QueryLatch<D> {
+impl QueryLatch {
     fn new() -> Self {
         QueryLatch {
             info: Lrc::new(Mutex::new(QueryLatchInfo { complete: false, waiters: Vec::new() })),
         }
     }
-}
 
-#[cfg(parallel_compiler)]
-impl<D> QueryLatch<D> {
     /// Awaits for the query job to complete.
-    pub(super) fn wait_on(
-        &self,
-        query: Option<QueryJobId<D>>,
-        span: Span,
-    ) -> Result<(), CycleError> {
+    pub(super) fn wait_on(&self, query: Option<QueryJobId>, span: Span) -> Result<(), CycleError> {
         let waiter =
             Lrc::new(QueryWaiter { query, span, cycle: Lock::new(None), condvar: Condvar::new() });
         self.wait_on_inner(&waiter);
@@ -242,7 +207,7 @@ impl<D> QueryLatch<D> {
     }
 
     /// Awaits the caller on this latch by blocking the current thread.
-    fn wait_on_inner(&self, waiter: &Lrc<QueryWaiter<D>>) {
+    fn wait_on_inner(&self, waiter: &Lrc<QueryWaiter>) {
         let mut info = self.info.lock();
         if !info.complete {
             // We push the waiter on to the `waiters` list. It can be accessed inside
@@ -276,7 +241,7 @@ impl<D> QueryLatch<D> {
 
     /// Removes a single waiter from the list of waiters.
     /// This is used to break query cycles.
-    fn extract_waiter(&self, waiter: usize) -> Lrc<QueryWaiter<D>> {
+    fn extract_waiter(&self, waiter: usize) -> Lrc<QueryWaiter> {
         let mut info = self.info.lock();
         debug_assert!(!info.complete);
         // Remove the waiter from the list of waiters
@@ -286,7 +251,7 @@ impl<D> QueryLatch<D> {
 
 /// A resumable waiter of a query. The usize is the index into waiters in the query's latch
 #[cfg(parallel_compiler)]
-type Waiter<D> = (QueryJobId<D>, usize);
+type Waiter = (QueryJobId, usize);
 
 /// Visits all the non-resumable and resumable waiters of a query.
 /// Only waiters in a query are visited.
@@ -298,14 +263,9 @@ type Waiter<D> = (QueryJobId<D>, usize);
 /// required information to resume the waiter.
 /// If all `visit` calls returns None, this function also returns None.
 #[cfg(parallel_compiler)]
-fn visit_waiters<D, F>(
-    query_map: &QueryMap<D>,
-    query: QueryJobId<D>,
-    mut visit: F,
-) -> Option<Option<Waiter<D>>>
+fn visit_waiters<F>(query_map: &QueryMap, query: QueryJobId, mut visit: F) -> Option<Option<Waiter>>
 where
-    D: Copy + Clone + Eq + Hash,
-    F: FnMut(Span, QueryJobId<D>) -> Option<Option<Waiter<D>>>,
+    F: FnMut(Span, QueryJobId) -> Option<Option<Waiter>>,
 {
     // Visit the parent query which is a non-resumable waiter since it's on the same stack
     if let Some(parent) = query.parent(query_map) {
@@ -334,16 +294,13 @@ where
 /// If a cycle is detected, this initial value is replaced with the span causing
 /// the cycle.
 #[cfg(parallel_compiler)]
-fn cycle_check<D>(
-    query_map: &QueryMap<D>,
-    query: QueryJobId<D>,
+fn cycle_check(
+    query_map: &QueryMap,
+    query: QueryJobId,
     span: Span,
-    stack: &mut Vec<(Span, QueryJobId<D>)>,
-    visited: &mut FxHashSet<QueryJobId<D>>,
-) -> Option<Option<Waiter<D>>>
-where
-    D: Copy + Clone + Eq + Hash,
-{
+    stack: &mut Vec<(Span, QueryJobId)>,
+    visited: &mut FxHashSet<QueryJobId>,
+) -> Option<Option<Waiter>> {
     if !visited.insert(query) {
         return if let Some(p) = stack.iter().position(|q| q.1 == query) {
             // We detected a query cycle, fix up the initial span and return Some
@@ -378,14 +335,11 @@ where
 /// from `query` without going through any of the queries in `visited`.
 /// This is achieved with a depth first search.
 #[cfg(parallel_compiler)]
-fn connected_to_root<D>(
-    query_map: &QueryMap<D>,
-    query: QueryJobId<D>,
-    visited: &mut FxHashSet<QueryJobId<D>>,
-) -> bool
-where
-    D: Copy + Clone + Eq + Hash,
-{
+fn connected_to_root(
+    query_map: &QueryMap,
+    query: QueryJobId,
+    visited: &mut FxHashSet<QueryJobId>,
+) -> bool {
     // We already visited this or we're deliberately ignoring it
     if !visited.insert(query) {
         return false;
@@ -404,10 +358,9 @@ where
 
 // Deterministically pick an query from a list
 #[cfg(parallel_compiler)]
-fn pick_query<'a, D, T, F>(query_map: &QueryMap<D>, queries: &'a [T], f: F) -> &'a T
+fn pick_query<'a, T, F>(query_map: &QueryMap, queries: &'a [T], f: F) -> &'a T
 where
-    D: Copy + Clone + Eq + Hash,
-    F: Fn(&T) -> (Span, QueryJobId<D>),
+    F: Fn(&T) -> (Span, QueryJobId),
 {
     // Deterministically pick an entry point
     // FIXME: Sort this instead
@@ -431,10 +384,10 @@ where
 /// If a cycle was not found, the starting query is removed from `jobs` and
 /// the function returns false.
 #[cfg(parallel_compiler)]
-fn remove_cycle<D: DepKind>(
-    query_map: &QueryMap<D>,
-    jobs: &mut Vec<QueryJobId<D>>,
-    wakelist: &mut Vec<Lrc<QueryWaiter<D>>>,
+fn remove_cycle(
+    query_map: &QueryMap,
+    jobs: &mut Vec<QueryJobId>,
+    wakelist: &mut Vec<Lrc<QueryWaiter>>,
 ) -> bool {
     let mut visited = FxHashSet::default();
     let mut stack = Vec::new();
@@ -489,7 +442,7 @@ fn remove_cycle<D: DepKind>(
                     }
                 }
             })
-            .collect::<Vec<(Span, QueryJobId<D>, Option<(Span, QueryJobId<D>)>)>>();
+            .collect::<Vec<(Span, QueryJobId, Option<(Span, QueryJobId)>)>>();
 
         // Deterministically pick an entry point
         let (_, entry_point, usage) = pick_query(query_map, &entry_points, |e| (e.0, e.1));
@@ -544,7 +497,7 @@ pub fn deadlock<CTX: QueryContext>(tcx: CTX, registry: &rayon_core::Registry) {
 
     let mut wakelist = Vec::new();
     let query_map = tcx.try_collect_active_jobs().unwrap();
-    let mut jobs: Vec<QueryJobId<CTX::DepKind>> = query_map.keys().cloned().collect();
+    let mut jobs: Vec<QueryJobId> = query_map.keys().cloned().collect();
 
     let mut found_cycle = false;
 
@@ -630,7 +583,7 @@ pub(crate) fn report_cycle<'a>(
 
 pub fn print_query_stack<CTX: QueryContext>(
     tcx: CTX,
-    mut current_query: Option<QueryJobId<CTX::DepKind>>,
+    mut current_query: Option<QueryJobId>,
     handler: &Handler,
     num_frames: Option<usize>,
 ) -> usize {

compiler/rustc_query_system/src/query/mod.rs

@@ -117,10 +117,12 @@ impl QuerySideEffects {
 }
 
 pub trait QueryContext: HasDepContext {
+    fn next_job_id(&self) -> QueryJobId;
+
     /// Get the query information from the TLS context.
-    fn current_query_job(&self) -> Option<QueryJobId<Self::DepKind>>;
+    fn current_query_job(&self) -> Option<QueryJobId>;
 
-    fn try_collect_active_jobs(&self) -> Option<QueryMap<Self::DepKind>>;
+    fn try_collect_active_jobs(&self) -> Option<QueryMap>;
 
     /// Load side effects associated to the node in the previous session.
     fn load_side_effects(&self, prev_dep_node_index: SerializedDepNodeIndex) -> QuerySideEffects;
@@ -140,7 +142,7 @@ pub trait QueryContext: HasDepContext {
     /// captured during execution and the actual result.
     fn start_query<R>(
         &self,
-        token: QueryJobId<Self::DepKind>,
+        token: QueryJobId,
         diagnostics: Option<&Lock<ThinVec<Diagnostic>>>,
         compute: impl FnOnce() -> R,
     ) -> R;

compiler/rustc_query_system/src/query/plumbing.rs

@@ -5,9 +5,7 @@
 use crate::dep_graph::{DepContext, DepNode, DepNodeIndex, DepNodeParams};
 use crate::query::caches::QueryCache;
 use crate::query::config::{QueryDescription, QueryVtable};
-use crate::query::job::{
-    report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo, QueryShardJobId,
-};
+use crate::query::job::{report_cycle, QueryInfo, QueryJob, QueryJobId, QueryJobInfo};
 use crate::query::{QueryContext, QueryMap, QuerySideEffects, QueryStackFrame};
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::{FxHashMap, FxHasher};
@@ -24,7 +22,6 @@ use std::collections::hash_map::Entry;
 use std::fmt::Debug;
 use std::hash::{Hash, Hasher};
 use std::mem;
-use std::num::NonZeroU32;
 use std::ptr;
 
 pub struct QueryCacheStore<C: QueryCache> {
@@ -69,36 +66,32 @@ impl<C: QueryCache> QueryCacheStore<C> {
     }
 }
 
-struct QueryStateShard<D, K> {
-    active: FxHashMap<K, QueryResult<D>>,
-
-    /// Used to generate unique ids for active jobs.
-    jobs: u32,
+struct QueryStateShard<K> {
+    active: FxHashMap<K, QueryResult>,
 }
 
-impl<D, K> Default for QueryStateShard<D, K> {
-    fn default() -> QueryStateShard<D, K> {
-        QueryStateShard { active: Default::default(), jobs: 0 }
+impl<K> Default for QueryStateShard<K> {
+    fn default() -> QueryStateShard<K> {
+        QueryStateShard { active: Default::default() }
     }
 }
 
-pub struct QueryState<D, K> {
-    shards: Sharded<QueryStateShard<D, K>>,
+pub struct QueryState<K> {
+    shards: Sharded<QueryStateShard<K>>,
 }
 
 /// Indicates the state of a query for a given key in a query map.
-enum QueryResult<D> {
+enum QueryResult {
     /// An already executing query. The query job can be used to await for its completion.
-    Started(QueryJob<D>),
+    Started(QueryJob),
 
     /// The query panicked. Queries trying to wait on this will raise a fatal error which will
     /// silently panic.
     Poisoned,
 }
 
-impl<D, K> QueryState<D, K>
+impl<K> QueryState<K>
 where
-    D: Copy + Clone + Eq + Hash,
     K: Eq + Hash + Clone + Debug,
 {
     pub fn all_inactive(&self) -> bool {
@@ -109,19 +102,17 @@ where
     pub fn try_collect_active_jobs<CTX: Copy>(
         &self,
         tcx: CTX,
-        kind: D,
         make_query: fn(CTX, K) -> QueryStackFrame,
-        jobs: &mut QueryMap<D>,
+        jobs: &mut QueryMap,
     ) -> Option<()> {
         // We use try_lock_shards here since we are called from the
         // deadlock handler, and this shouldn't be locked.
         let shards = self.shards.try_lock_shards()?;
-        for (shard_id, shard) in shards.iter().enumerate() {
+        for shard in shards.iter() {
             for (k, v) in shard.active.iter() {
                 if let QueryResult::Started(ref job) = *v {
-                    let id = QueryJobId::new(job.id, shard_id, kind);
                     let query = make_query(tcx, k.clone());
-                    jobs.insert(id, QueryJobInfo { query, job: job.clone() });
+                    jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
                 }
             }
         }
@@ -130,22 +121,21 @@ where
     }
 }
 
-impl<D, K> Default for QueryState<D, K> {
-    fn default() -> QueryState<D, K> {
+impl<K> Default for QueryState<K> {
+    fn default() -> QueryState<K> {
         QueryState { shards: Default::default() }
     }
 }
 
 /// A type representing the responsibility to execute the job in the `job` field.
 /// This will poison the relevant query if dropped.
-struct JobOwner<'tcx, D, K>
+struct JobOwner<'tcx, K>
 where
-    D: Copy + Clone + Eq + Hash,
     K: Eq + Hash + Clone,
 {
-    state: &'tcx QueryState<D, K>,
+    state: &'tcx QueryState<K>,
     key: K,
-    id: QueryJobId<D>,
+    id: QueryJobId,
 }
 
 #[cold]
@@ -166,9 +156,8 @@ where
     cache.store_nocache(value)
 }
 
-impl<'tcx, D, K> JobOwner<'tcx, D, K>
+impl<'tcx, K> JobOwner<'tcx, K>
 where
-    D: Copy + Clone + Eq + Hash,
     K: Eq + Hash + Clone,
 {
     /// Either gets a `JobOwner` corresponding the query, allowing us to
@@ -182,12 +171,11 @@ where
     #[inline(always)]
     fn try_start<'b, CTX>(
         tcx: &'b CTX,
-        state: &'b QueryState<CTX::DepKind, K>,
+        state: &'b QueryState<K>,
         span: Span,
         key: K,
         lookup: QueryLookup,
-        dep_kind: CTX::DepKind,
-    ) -> TryGetJob<'b, CTX::DepKind, K>
+    ) -> TryGetJob<'b, K>
     where
         CTX: QueryContext,
     {
@@ -197,27 +185,21 @@ where
 
         match lock.active.entry(key) {
             Entry::Vacant(entry) => {
-                // Generate an id unique within this shard.
-                let id = lock.jobs.checked_add(1).unwrap();
-                lock.jobs = id;
-                let id = QueryShardJobId(NonZeroU32::new(id).unwrap());
-
+                let id = tcx.next_job_id();
                 let job = tcx.current_query_job();
                 let job = QueryJob::new(id, span, job);
 
                 let key = entry.key().clone();
                 entry.insert(QueryResult::Started(job));
 
-                let global_id = QueryJobId::new(id, shard, dep_kind);
-                let owner = JobOwner { state, id: global_id, key };
+                let owner = JobOwner { state, id, key };
                 return TryGetJob::NotYetStarted(owner);
             }
             Entry::Occupied(mut entry) => {
                 match entry.get_mut() {
                     #[cfg(not(parallel_compiler))]
                     QueryResult::Started(job) => {
-                        let id = QueryJobId::new(job.id, shard, dep_kind);
-
+                        let id = job.id;
                         drop(state_lock);
 
                         // If we are single-threaded we know that we have cycle error,
@@ -295,9 +277,8 @@ where
     }
 }
 
-impl<'tcx, D, K> Drop for JobOwner<'tcx, D, K>
+impl<'tcx, K> Drop for JobOwner<'tcx, K>
 where
-    D: Copy + Clone + Eq + Hash,
     K: Eq + Hash + Clone,
 {
     #[inline(never)]
@@ -329,13 +310,12 @@ pub(crate) struct CycleError {
 }
 
 /// The result of `try_start`.
-enum TryGetJob<'tcx, D, K>
+enum TryGetJob<'tcx, K>
 where
-    D: Copy + Clone + Eq + Hash,
     K: Eq + Hash + Clone,
 {
     /// The query is not yet started. Contains a guard to the cache eventually used to start it.
-    NotYetStarted(JobOwner<'tcx, D, K>),
+    NotYetStarted(JobOwner<'tcx, K>),
 
     /// The query was already completed.
     /// Returns the result of the query and its dep-node index
@@ -375,7 +355,7 @@ where
 
 fn try_execute_query<CTX, C>(
     tcx: CTX,
-    state: &QueryState<CTX::DepKind, C::Key>,
+    state: &QueryState<C::Key>,
     cache: &QueryCacheStore<C>,
     span: Span,
     key: C::Key,
@@ -388,14 +368,7 @@ where
     C::Key: Clone + DepNodeParams<CTX::DepContext>,
     CTX: QueryContext,
 {
-    match JobOwner::<'_, CTX::DepKind, C::Key>::try_start(
-        &tcx,
-        state,
-        span,
-        key.clone(),
-        lookup,
-        query.dep_kind,
-    ) {
+    match JobOwner::<'_, C::Key>::try_start(&tcx, state, span, key.clone(), lookup) {
         TryGetJob::NotYetStarted(job) => {
             let (result, dep_node_index) = execute_job(tcx, key, dep_node, query, job.id);
             let result = job.complete(cache, result, dep_node_index);
@@ -427,7 +400,7 @@ fn execute_job<CTX, K, V>(
     key: K,
     mut dep_node_opt: Option<DepNode<CTX::DepKind>>,
     query: &QueryVtable<CTX, K, V>,
-    job_id: QueryJobId<CTX::DepKind>,
+    job_id: QueryJobId,
 ) -> (V, DepNodeIndex)
 where
     K: Clone + DepNodeParams<CTX::DepContext>,