Remove QueryDispatcher

compiler/rustc_middle/src/query/inner.rs

@@ -2,14 +2,33 @@
 //! `tcx.$query(..)` and its variations.
 
 use rustc_query_system::dep_graph::{DepKind, DepNodeKey};
-use rustc_query_system::query::{QueryCache, QueryMode, try_get_cached};
+use rustc_query_system::query::{QueryCache, QueryMode};
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span};
 
 use crate::dep_graph;
 use crate::query::erase::{self, Erasable, Erased};
 use crate::query::plumbing::QueryVTable;
 use crate::ty::TyCtxt;
 
+/// Checks whether there is already a value for this key in the in-memory
+/// query cache, returning that value if present.
+///
+/// (Also performs some associated bookkeeping, if a value was found.)
+#[inline(always)]
+fn try_get_cached<'tcx, C>(tcx: TyCtxt<'tcx>, cache: &C, key: &C::Key) -> Option<C::Value>
+where
+    C: QueryCache,
+{
+    match cache.lookup(key) {
+        Some((value, index)) => {
+            tcx.prof.query_cache_hit(index.into());
+            tcx.dep_graph.read_index(index);
+            Some(value)
+        }
+        None => None,
+    }
+}
+
 /// Shared implementation of `tcx.$query(..)` and `tcx.at(span).$query(..)`
 /// for all queries.
 #[inline(always)]

compiler/rustc_query_impl/src/lib.rs

@@ -3,16 +3,16 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
 #![feature(adt_const_params)]
+#![feature(core_intrinsics)]
 #![feature(min_specialization)]
 #![feature(rustc_attrs)]
 // tidy-alphabetical-end
 
 use std::marker::ConstParamTy;
 
-use rustc_data_structures::stable_hasher::HashStable;
 use rustc_data_structures::sync::AtomicU64;
 use rustc_middle::arena::Arena;
-use rustc_middle::dep_graph::{self, DepKind, DepKindVTable, DepNodeIndex};
+use rustc_middle::dep_graph::{self, DepKind, DepKindVTable, DepNode, DepNodeIndex};
 use rustc_middle::queries::{
     self, ExternProviders, Providers, QueryCaches, QueryEngine, QueryStates,
 };
@@ -22,10 +22,8 @@ use rustc_middle::query::plumbing::{QuerySystem, QuerySystemFns, QueryVTable};
 use rustc_middle::query::values::Value;
 use rustc_middle::ty::TyCtxt;
 use rustc_query_system::dep_graph::SerializedDepNodeIndex;
-use rustc_query_system::ich::StableHashingContext;
 use rustc_query_system::query::{
-    CycleError, CycleErrorHandling, HashResult, QueryCache, QueryDispatcher, QueryMap, QueryMode,
-    QueryState, get_query_incr, get_query_non_incr,
+    CycleError, CycleErrorHandling, HashResult, QueryCache, QueryMap, QueryMode, QueryState,
 };
 use rustc_span::{ErrorGuaranteed, Span};
 
@@ -52,8 +50,8 @@ struct QueryFlags {
     is_feedable: bool,
 }
 
-/// Combines a [`QueryVTable`] with some additional compile-time booleans
-/// to implement [`QueryDispatcher`], for use by code in [`rustc_query_system`].
+/// Combines a [`QueryVTable`] with some additional compile-time booleans.
+/// "Dispatcher" should be understood as a near-synonym of "vtable".
 ///
 /// Baking these boolean flags into the type gives a modest but measurable
 /// improvement to compiler perf and compiler code size; see
@@ -75,67 +73,60 @@ impl<'tcx, C: QueryCache, const FLAGS: QueryFlags> Clone
     }
 }
 
-// This is `impl QueryDispatcher for SemiDynamicQueryDispatcher`.
-impl<'tcx, C: QueryCache, const FLAGS: QueryFlags> QueryDispatcher<'tcx>
-    for SemiDynamicQueryDispatcher<'tcx, C, FLAGS>
-where
-    for<'a> C::Key: HashStable<StableHashingContext<'a>>,
-{
-    type Qcx = QueryCtxt<'tcx>;
-    type Key = C::Key;
-    type Value = C::Value;
-    type Cache = C;
-
+impl<'tcx, C: QueryCache, const FLAGS: QueryFlags> SemiDynamicQueryDispatcher<'tcx, C, FLAGS> {
     #[inline(always)]
     fn name(self) -> &'static str {
         self.vtable.name
     }
 
     #[inline(always)]
-    fn will_cache_on_disk_for_key(self, tcx: TyCtxt<'tcx>, key: &Self::Key) -> bool {
+    fn will_cache_on_disk_for_key(self, tcx: TyCtxt<'tcx>, key: &C::Key) -> bool {
         self.vtable.will_cache_on_disk_for_key_fn.map_or(false, |f| f(tcx, key))
     }
 
+    // Don't use this method to access query results, instead use the methods on TyCtxt.
     #[inline(always)]
-    fn query_state(self, qcx: QueryCtxt<'tcx>) -> &'tcx QueryState<'tcx, Self::Key> {
+    fn query_state(self, qcx: QueryCtxt<'tcx>) -> &'tcx QueryState<'tcx, C::Key> {
         // Safety:
         // This is just manually doing the subfield referencing through pointer math.
         unsafe {
             &*(&qcx.tcx.query_system.states as *const QueryStates<'tcx>)
                 .byte_add(self.vtable.query_state)
-                .cast::<QueryState<'tcx, Self::Key>>()
+                .cast::<QueryState<'tcx, C::Key>>()
         }
     }
 
+    // Don't use this method to access query results, instead use the methods on TyCtxt.
     #[inline(always)]
-    fn query_cache(self, qcx: QueryCtxt<'tcx>) -> &'tcx Self::Cache {
+    fn query_cache(self, qcx: QueryCtxt<'tcx>) -> &'tcx C {
         // Safety:
         // This is just manually doing the subfield referencing through pointer math.
         unsafe {
             &*(&qcx.tcx.query_system.caches as *const QueryCaches<'tcx>)
                 .byte_add(self.vtable.query_cache)
-                .cast::<Self::Cache>()
+                .cast::<C>()
         }
     }
 
+    // Don't use this method to compute query results, instead use the methods on TyCtxt.
     #[inline(always)]
-    fn execute_query(self, tcx: TyCtxt<'tcx>, key: Self::Key) -> Self::Value {
+    fn execute_query(self, tcx: TyCtxt<'tcx>, key: C::Key) -> C::Value {
         (self.vtable.execute_query)(tcx, key)
     }
 
     #[inline(always)]
-    fn compute(self, qcx: QueryCtxt<'tcx>, key: Self::Key) -> Self::Value {
+    fn compute(self, qcx: QueryCtxt<'tcx>, key: C::Key) -> C::Value {
         (self.vtable.compute_fn)(qcx.tcx, key)
     }
 
     #[inline(always)]
     fn try_load_from_disk(
         self,
         qcx: QueryCtxt<'tcx>,
-        key: &Self::Key,
+        key: &C::Key,
         prev_index: SerializedDepNodeIndex,
         index: DepNodeIndex,
-    ) -> Option<Self::Value> {
+    ) -> Option<C::Value> {
         // `?` will return None immediately for queries that never cache to disk.
         self.vtable.try_load_from_disk_fn?(qcx.tcx, key, prev_index, index)
     }
@@ -144,23 +135,24 @@ where
     fn is_loadable_from_disk(
         self,
         qcx: QueryCtxt<'tcx>,
-        key: &Self::Key,
+        key: &C::Key,
         index: SerializedDepNodeIndex,
     ) -> bool {
         self.vtable.is_loadable_from_disk_fn.map_or(false, |f| f(qcx.tcx, key, index))
     }
 
+    /// Synthesize an error value to let compilation continue after a cycle.
     fn value_from_cycle_error(
         self,
         tcx: TyCtxt<'tcx>,
         cycle_error: &CycleError,
         guar: ErrorGuaranteed,
-    ) -> Self::Value {
+    ) -> C::Value {
         (self.vtable.value_from_cycle_error)(tcx, cycle_error, guar)
     }
 
     #[inline(always)]
-    fn format_value(self) -> fn(&Self::Value) -> String {
+    fn format_value(self) -> fn(&C::Value) -> String {
         self.vtable.format_value
     }
 
@@ -195,13 +187,17 @@ where
     }
 
     #[inline(always)]
-    fn hash_result(self) -> HashResult<Self::Value> {
+    fn hash_result(self) -> HashResult<C::Value> {
         self.vtable.hash_result
     }
+
+    fn construct_dep_node(self, tcx: TyCtxt<'tcx>, key: &C::Key) -> DepNode {
+        DepNode::construct(tcx, self.dep_kind(), key)
+    }
 }
 
 /// Provides access to vtable-like operations for a query
-/// (by creating a [`QueryDispatcher`]),
+/// (by creating a [`SemiDynamicQueryDispatcher`]),
 /// but also keeps track of the "unerased" value type of the query
 /// (i.e. the actual result type in the query declaration).
 ///
@@ -211,17 +207,15 @@ where
 ///
 /// There is one macro-generated implementation of this trait for each query,
 /// on the type `rustc_query_impl::query_impl::$name::QueryType`.
-trait QueryDispatcherUnerased<'tcx> {
+trait QueryDispatcherUnerased<'tcx, C: QueryCache, const FLAGS: QueryFlags> {
     type UnerasedValue;
-    type Dispatcher: QueryDispatcher<'tcx, Qcx = QueryCtxt<'tcx>>;
+    //type Dispatcher: QueryDispatcher<'tcx, Qcx = QueryCtxt<'tcx>>; // njn: remove
 
     const NAME: &'static &'static str;
 
-    fn query_dispatcher(tcx: TyCtxt<'tcx>) -> Self::Dispatcher;
+    fn query_dispatcher(tcx: TyCtxt<'tcx>) -> SemiDynamicQueryDispatcher<'tcx, C, FLAGS>;
 
-    fn restore_val(
-        value: <Self::Dispatcher as QueryDispatcher<'tcx>>::Value,
-    ) -> Self::UnerasedValue;
+    fn restore_val(value: C::Value) -> Self::UnerasedValue;
 }
 
 pub fn query_system<'tcx>(