Rollup merge of #108169 - Zoxc:query-key-copy, r=cjgillot

Make query keys `Copy`

This regressed compiler performance locally, so I'm curious what perf will say about it.

<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check</td><td align="right">1.7566s</td><td align="right">1.7657s</td><td align="right"> 0.52%</td></tr><tr><td>🟣 <b>hyper</b>:check</td><td align="right">0.2572s</td><td align="right">0.2578s</td><td align="right"> 0.20%</td></tr><tr><td>🟣 <b>regex</b>:check</td><td align="right">0.9863s</td><td align="right">0.9900s</td><td align="right"> 0.37%</td></tr><tr><td>🟣 <b>syn</b>:check</td><td align="right">1.6018s</td><td align="right">1.6073s</td><td align="right"> 0.34%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check</td><td align="right">6.2493s</td><td align="right">6.2920s</td><td align="right"> 0.68%</td></tr><tr><td>Total</td><td align="right">10.8512s</td><td align="right">10.9127s</td><td align="right"> 0.57%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">1.0042s</td><td align="right"> 0.42%</td></tr></table>

3 files changed, 18 insertions, 17 deletions

diff --git a/compiler/rustc_query_system/src/query/caches.rs b/compiler/rustc_query_system/src/query/caches.rs
index e840108bdd8..4b3cd16c29f 100644
--- a/compiler/rustc_query_system/src/query/caches.rs
+++ b/compiler/rustc_query_system/src/query/caches.rs
@@ -21,7 +21,7 @@ pub trait QueryStorage {
 }
 
 pub trait QueryCache: QueryStorage + Sized {
-    type Key: Hash + Eq + Clone + Debug;
+    type Key: Hash + Eq + Copy + Debug;
 
     /// Checks if the query is already computed and in the cache.
     /// It returns the shard index and a lock guard to the shard,
@@ -61,7 +61,7 @@ impl<K: Eq + Hash, V: Copy + Debug> QueryStorage for DefaultCache<K, V> {
 
 impl<K, V> QueryCache for DefaultCache<K, V>
 where
-    K: Eq + Hash + Clone + Debug,
+    K: Eq + Hash + Copy + Debug,
     V: Copy + Debug,
 {
     type Key = K;
@@ -179,7 +179,7 @@ impl<K: Eq + Idx, V: Copy + Debug> QueryStorage for VecCache<K, V> {
 
 impl<K, V> QueryCache for VecCache<K, V>
 where
-    K: Eq + Idx + Clone + Debug,
+    K: Eq + Idx + Copy + Debug,
     V: Copy + Debug,
 {
     type Key = K;
diff --git a/compiler/rustc_query_system/src/query/config.rs b/compiler/rustc_query_system/src/query/config.rs
index 56247e827a2..d5637387346 100644
--- a/compiler/rustc_query_system/src/query/config.rs
+++ b/compiler/rustc_query_system/src/query/config.rs
@@ -19,7 +19,9 @@ pub type TryLoadFromDisk<Qcx, Q> =
 pub trait QueryConfig<Qcx: QueryContext> {
     const NAME: &'static str;
 
-    type Key: DepNodeParams<Qcx::DepContext> + Eq + Hash + Clone + Debug;
+    // `Key` and `Value` are `Copy` instead of `Clone` to ensure copying them stays cheap,
+    // but it isn't necessary.
+    type Key: DepNodeParams<Qcx::DepContext> + Eq + Hash + Copy + Debug;
     type Value: Debug + Copy;
 
     type Cache: QueryCache<Key = Self::Key, Value = Self::Value>;
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index 21a0c73d720..5499165930d 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -48,7 +48,7 @@ enum QueryResult<D: DepKind> {
 
 impl<K, D> QueryState<K, D>
 where
-    K: Eq + Hash + Clone + Debug,
+    K: Eq + Hash + Copy + Debug,
     D: DepKind,
 {
     pub fn all_inactive(&self) -> bool {
@@ -77,7 +77,7 @@ where
             for shard in shards.iter() {
                 for (k, v) in shard.iter() {
                     if let QueryResult::Started(ref job) = *v {
-                        let query = make_query(qcx, k.clone());
+                        let query = make_query(qcx, *k);
                         jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
                     }
                 }
@@ -91,7 +91,7 @@ where
             // really hurt much.)
             for (k, v) in self.active.try_lock()?.iter() {
                 if let QueryResult::Started(ref job) = *v {
-                    let query = make_query(qcx, k.clone());
+                    let query = make_query(qcx, *k);
                     jobs.insert(job.id, QueryJobInfo { query, job: job.clone() });
                 }
             }
@@ -111,7 +111,7 @@ impl<K, D: DepKind> Default for QueryState<K, D> {
 /// This will poison the relevant query if dropped.
 struct JobOwner<'tcx, K, D: DepKind>
 where
-    K: Eq + Hash + Clone,
+    K: Eq + Hash + Copy,
 {
     state: &'tcx QueryState<K, D>,
     key: K,
@@ -163,7 +163,7 @@ where
 
 impl<'tcx, K, D: DepKind> JobOwner<'tcx, K, D>
 where
-    K: Eq + Hash + Clone,
+    K: Eq + Hash + Copy,
 {
     /// Either gets a `JobOwner` corresponding the query, allowing us to
     /// start executing the query, or returns with the result of the query.
@@ -195,7 +195,7 @@ where
                 let job = qcx.current_query_job();
                 let job = QueryJob::new(id, span, job);
 
-                let key = entry.key().clone();
+                let key = *entry.key();
                 entry.insert(QueryResult::Started(job));
 
                 let owner = JobOwner { state, id, key };
@@ -274,7 +274,7 @@ where
 
 impl<'tcx, K, D> Drop for JobOwner<'tcx, K, D>
 where
-    K: Eq + Hash + Clone,
+    K: Eq + Hash + Copy,
     D: DepKind,
 {
     #[inline(never)]
@@ -291,7 +291,7 @@ where
                 QueryResult::Started(job) => job,
                 QueryResult::Poisoned => panic!(),
             };
-            shard.insert(self.key.clone(), QueryResult::Poisoned);
+            shard.insert(self.key, QueryResult::Poisoned);
             job
         };
         // Also signal the completion of the job, so waiters
@@ -310,7 +310,7 @@ pub(crate) struct CycleError<D: DepKind> {
 /// The result of `try_start`.
 enum TryGetJob<'tcx, K, D>
 where
-    K: Eq + Hash + Clone,
+    K: Eq + Hash + Copy,
     D: DepKind,
 {
     /// The query is not yet started. Contains a guard to the cache eventually used to start it.
@@ -358,10 +358,9 @@ where
     Q: QueryConfig<Qcx>,
     Qcx: QueryContext,
 {
-    match JobOwner::<'_, Q::Key, Qcx::DepKind>::try_start(&qcx, state, span, key.clone()) {
+    match JobOwner::<'_, Q::Key, Qcx::DepKind>::try_start(&qcx, state, span, key) {
         TryGetJob::NotYetStarted(job) => {
-            let (result, dep_node_index) =
-                execute_job::<Q, Qcx>(qcx, key.clone(), dep_node, job.id);
+            let (result, dep_node_index) = execute_job::<Q, Qcx>(qcx, key, dep_node, job.id);
             if Q::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
@@ -551,7 +550,7 @@ where
     let prof_timer = qcx.dep_context().profiler().query_provider();
 
     // The dep-graph for this computation is already in-place.
-    let result = dep_graph.with_ignore(|| Q::compute(qcx, key.clone()));
+    let result = dep_graph.with_ignore(|| Q::compute(qcx, *key));
 
     prof_timer.finish_with_query_invocation_id(dep_node_index.into());