Rollup merge of rust-lang#69910 - cjgillot:polym, r=Zoxc

Avoid query type in generics

There are at the moment roughly 170 queries in librustc.
The way ty::query is structured, a lot of code is duplicated for each query.
I suspect this to be responsible for a part of librustc'c compile time.

This PR reduces the amount of code generic on the query,
replacing it by code generic on the key-value types.

This is split out of rust-lang#69808,
and should not contain the perf regression.

cc rust-lang#65031

src/librustc/ty/query/caches.rs

@@ -1,82 +1,94 @@
 use crate::dep_graph::DepNodeIndex;
-use crate::ty::query::config::QueryAccessors;
 use crate::ty::query::plumbing::{QueryLookup, QueryState, QueryStateShard};
 use crate::ty::TyCtxt;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sharded::Sharded;
 use std::default::Default;
 use std::hash::Hash;
+use std::marker::PhantomData;
 
 pub(crate) trait CacheSelector<K, V> {
-    type Cache: QueryCache<K, V>;
+    type Cache: QueryCache<Key = K, Value = V>;
 }
 
-pub(crate) trait QueryCache<K, V>: Default {
+pub(crate) trait QueryCache: Default {
+    type Key;
+    type Value;
     type Sharded: Default;
 
     /// Checks if the query is already computed and in the cache.
     /// It returns the shard index and a lock guard to the shard,
     /// which will be used if the query is not in the cache and we need
     /// to compute it.
-    fn lookup<'tcx, R, GetCache, OnHit, OnMiss, Q>(
+    fn lookup<'tcx, R, GetCache, OnHit, OnMiss>(
         &self,
-        state: &'tcx QueryState<'tcx, Q>,
+        state: &'tcx QueryState<'tcx, Self>,
         get_cache: GetCache,
-        key: K,
+        key: Self::Key,
         // `on_hit` can be called while holding a lock to the query state shard.
         on_hit: OnHit,
         on_miss: OnMiss,
     ) -> R
     where
-        Q: QueryAccessors<'tcx>,
-        GetCache: for<'a> Fn(&'a mut QueryStateShard<'tcx, Q>) -> &'a mut Self::Sharded,
-        OnHit: FnOnce(&V, DepNodeIndex) -> R,
-        OnMiss: FnOnce(K, QueryLookup<'tcx, Q>) -> R;
+        GetCache: for<'a> Fn(
+            &'a mut QueryStateShard<'tcx, Self::Key, Self::Sharded>,
+        ) -> &'a mut Self::Sharded,
+        OnHit: FnOnce(&Self::Value, DepNodeIndex) -> R,
+        OnMiss: FnOnce(Self::Key, QueryLookup<'tcx, Self::Key, Self::Sharded>) -> R;
 
     fn complete(
         &self,
         tcx: TyCtxt<'tcx>,
         lock_sharded_storage: &mut Self::Sharded,
-        key: K,
-        value: V,
+        key: Self::Key,
+        value: Self::Value,
         index: DepNodeIndex,
     );
 
     fn iter<R, L>(
         &self,
         shards: &Sharded<L>,
         get_shard: impl Fn(&mut L) -> &mut Self::Sharded,
-        f: impl for<'a> FnOnce(Box<dyn Iterator<Item = (&'a K, &'a V, DepNodeIndex)> + 'a>) -> R,
+        f: impl for<'a> FnOnce(
+            Box<dyn Iterator<Item = (&'a Self::Key, &'a Self::Value, DepNodeIndex)> + 'a>,
+        ) -> R,
     ) -> R;
 }
 
 pub struct DefaultCacheSelector;
 
 impl<K: Eq + Hash, V: Clone> CacheSelector<K, V> for DefaultCacheSelector {
-    type Cache = DefaultCache;
+    type Cache = DefaultCache<K, V>;
 }
 
-#[derive(Default)]
-pub struct DefaultCache;
+pub struct DefaultCache<K, V>(PhantomData<(K, V)>);
+
+impl<K, V> Default for DefaultCache<K, V> {
+    fn default() -> Self {
+        DefaultCache(PhantomData)
+    }
+}
 
-impl<K: Eq + Hash, V: Clone> QueryCache<K, V> for DefaultCache {
+impl<K: Eq + Hash, V: Clone> QueryCache for DefaultCache<K, V> {
+    type Key = K;
+    type Value = V;
     type Sharded = FxHashMap<K, (V, DepNodeIndex)>;
 
     #[inline(always)]
-    fn lookup<'tcx, R, GetCache, OnHit, OnMiss, Q>(
+    fn lookup<'tcx, R, GetCache, OnHit, OnMiss>(
         &self,
-        state: &'tcx QueryState<'tcx, Q>,
+        state: &'tcx QueryState<'tcx, Self>,
         get_cache: GetCache,
         key: K,
         on_hit: OnHit,
         on_miss: OnMiss,
     ) -> R
     where
-        Q: QueryAccessors<'tcx>,
-        GetCache: for<'a> Fn(&'a mut QueryStateShard<'tcx, Q>) -> &'a mut Self::Sharded,
+        GetCache:
+            for<'a> Fn(&'a mut QueryStateShard<'tcx, K, Self::Sharded>) -> &'a mut Self::Sharded,
         OnHit: FnOnce(&V, DepNodeIndex) -> R,
-        OnMiss: FnOnce(K, QueryLookup<'tcx, Q>) -> R,
+        OnMiss: FnOnce(K, QueryLookup<'tcx, K, Self::Sharded>) -> R,
     {
         let mut lookup = state.get_lookup(&key);
         let lock = &mut *lookup.lock;

src/librustc/ty/query/config.rs

@@ -2,7 +2,7 @@ use crate::dep_graph::SerializedDepNodeIndex;
 use crate::dep_graph::{DepKind, DepNode};
 use crate::ty::query::caches::QueryCache;
 use crate::ty::query::plumbing::CycleError;
-use crate::ty::query::{Query, QueryState};
+use crate::ty::query::QueryState;
 use crate::ty::TyCtxt;
 use rustc_data_structures::profiling::ProfileCategory;
 use rustc_hir::def_id::DefId;
@@ -28,18 +28,15 @@ pub trait QueryConfig<'tcx> {
 pub(crate) trait QueryAccessors<'tcx>: QueryConfig<'tcx> {
     const ANON: bool;
     const EVAL_ALWAYS: bool;
+    const DEP_KIND: DepKind;
 
-    type Cache: QueryCache<Self::Key, Self::Value>;
-
-    fn query(key: Self::Key) -> Query<'tcx>;
+    type Cache: QueryCache<Key = Self::Key, Value = Self::Value>;
 
     // Don't use this method to access query results, instead use the methods on TyCtxt
-    fn query_state<'a>(tcx: TyCtxt<'tcx>) -> &'a QueryState<'tcx, Self>;
+    fn query_state<'a>(tcx: TyCtxt<'tcx>) -> &'a QueryState<'tcx, Self::Cache>;
 
     fn to_dep_node(tcx: TyCtxt<'tcx>, key: &Self::Key) -> DepNode;
 
-    fn dep_kind() -> DepKind;
-
     // Don't use this method to compute query results, instead use the methods on TyCtxt
     fn compute(tcx: TyCtxt<'tcx>, key: Self::Key) -> Self::Value;
 
@@ -62,10 +59,7 @@ pub(crate) trait QueryDescription<'tcx>: QueryAccessors<'tcx> {
     }
 }
 
-impl<'tcx, M: QueryAccessors<'tcx, Key = DefId>> QueryDescription<'tcx> for M
-where
-    <M as QueryAccessors<'tcx>>::Cache: QueryCache<DefId, <M as QueryConfig<'tcx>>::Value>,
-{
+impl<'tcx, M: QueryAccessors<'tcx, Key = DefId>> QueryDescription<'tcx> for M {
     default fn describe(tcx: TyCtxt<'_>, def_id: DefId) -> Cow<'static, str> {
         if !tcx.sess.verbose() {
             format!("processing `{}`", tcx.def_path_str(def_id)).into()

src/librustc/ty/query/mod.rs

@@ -56,13 +56,12 @@ use rustc_span::symbol::Symbol;
 use rustc_span::{Span, DUMMY_SP};
 use std::borrow::Cow;
 use std::collections::BTreeMap;
-use std::convert::TryFrom;
 use std::ops::Deref;
 use std::sync::Arc;
 
 #[macro_use]
 mod plumbing;
-pub use self::plumbing::CycleError;
+pub(crate) use self::plumbing::CycleError;
 use self::plumbing::*;
 
 mod stats;