Auto merge of rust-lang#152791 - nnethercote:rm-const-FLAGS, r=Zalathar

Remove `const FLAGS`.

*[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/152791)*

The performance wins provided by these types are meagre, and I don't think they justify the code complexity they introduce.

r? @Zalathar

Author: bors

compiler/rustc_middle/src/query/plumbing.rs

@@ -1,4 +1,4 @@
-use std::fmt::Debug;
+use std::fmt;
 use std::ops::Deref;
 
 use rustc_data_structures::fingerprint::Fingerprint;
@@ -12,7 +12,7 @@ use rustc_span::{ErrorGuaranteed, Span};
 pub use sealed::IntoQueryParam;
 
 use crate::dep_graph;
-use crate::dep_graph::{DepKind, DepNodeIndex, SerializedDepNodeIndex};
+use crate::dep_graph::{DepKind, DepNode, DepNodeIndex, SerializedDepNodeIndex};
 use crate::ich::StableHashingContext;
 use crate::queries::{
     ExternProviders, PerQueryVTables, Providers, QueryArenas, QueryCaches, QueryEngine, QueryStates,
@@ -104,7 +104,16 @@ pub enum QueryMode {
 /// Stores function pointers and other metadata for a particular query.
 pub struct QueryVTable<'tcx, C: QueryCache> {
     pub name: &'static str,
+
+    /// True if this query has the `anon` modifier.
+    pub anon: bool,
+    /// True if this query has the `eval_always` modifier.
     pub eval_always: bool,
+    /// True if this query has the `depth_limit` modifier.
+    pub depth_limit: bool,
+    /// True if this query has the `feedable` modifier.
+    pub feedable: bool,
+
     pub dep_kind: DepKind,
     /// How this query deals with query cycle errors.
     pub cycle_error_handling: CycleErrorHandling,
@@ -142,6 +151,85 @@ pub struct QueryVTable<'tcx, C: QueryCache> {
     pub description_fn: fn(TyCtxt<'tcx>, C::Key) -> String,
 }
 
+impl<'tcx, C: QueryCache> fmt::Debug for QueryVTable<'tcx, C> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // When debug-printing a query vtable (e.g. for ICE or tracing),
+        // just print the query name to know what query we're dealing with.
+        // The other fields and flags are probably just unhelpful noise.
+        //
+        // If there is need for a more detailed dump of all flags and fields,
+        // consider writing a separate dump method and calling it explicitly.
+        f.write_str(self.name)
+    }
+}
+
+impl<'tcx, C: QueryCache> QueryVTable<'tcx, C> {
+    #[inline(always)]
+    pub fn will_cache_on_disk_for_key(&self, tcx: TyCtxt<'tcx>, key: &C::Key) -> bool {
+        self.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)]
+    pub fn query_state(&self, tcx: TyCtxt<'tcx>) -> &'tcx QueryState<'tcx, C::Key> {
+        // Safety:
+        // This is just manually doing the subfield referencing through pointer math.
+        unsafe {
+            &*(&tcx.query_system.states as *const QueryStates<'tcx>)
+                .byte_add(self.query_state)
+                .cast::<QueryState<'tcx, C::Key>>()
+        }
+    }
+
+    // Don't use this method to access query results, instead use the methods on TyCtxt.
+    #[inline(always)]
+    pub fn query_cache(&self, tcx: TyCtxt<'tcx>) -> &'tcx C {
+        // Safety:
+        // This is just manually doing the subfield referencing through pointer math.
+        unsafe {
+            &*(&tcx.query_system.caches as *const QueryCaches<'tcx>)
+                .byte_add(self.query_cache)
+                .cast::<C>()
+        }
+    }
+
+    #[inline(always)]
+    pub fn try_load_from_disk(
+        &self,
+        tcx: TyCtxt<'tcx>,
+        key: &C::Key,
+        prev_index: SerializedDepNodeIndex,
+        index: DepNodeIndex,
+    ) -> Option<C::Value> {
+        // `?` will return None immediately for queries that never cache to disk.
+        self.try_load_from_disk_fn?(tcx, key, prev_index, index)
+    }
+
+    #[inline]
+    pub fn is_loadable_from_disk(
+        &self,
+        tcx: TyCtxt<'tcx>,
+        key: &C::Key,
+        index: SerializedDepNodeIndex,
+    ) -> bool {
+        self.is_loadable_from_disk_fn.map_or(false, |f| f(tcx, key, index))
+    }
+
+    /// Synthesize an error value to let compilation continue after a cycle.
+    pub fn value_from_cycle_error(
+        &self,
+        tcx: TyCtxt<'tcx>,
+        cycle_error: &CycleError,
+        guar: ErrorGuaranteed,
+    ) -> C::Value {
+        (self.value_from_cycle_error)(tcx, cycle_error, guar)
+    }
+
+    pub fn construct_dep_node(&self, tcx: TyCtxt<'tcx>, key: &C::Key) -> DepNode {
+        DepNode::construct(tcx, self.dep_kind, key)
+    }
+}
+
 pub struct QuerySystemFns {
     pub engine: QueryEngine,
     pub local_providers: Providers,

compiler/rustc_query_impl/src/dep_kind_vtables.rs

@@ -2,8 +2,8 @@ use rustc_middle::bug;
 use rustc_middle::dep_graph::{DepKindVTable, DepNodeKey, KeyFingerprintStyle};
 use rustc_middle::query::QueryCache;
 
+use crate::QueryDispatcherUnerased;
 use crate::plumbing::{force_from_dep_node_inner, try_load_from_on_disk_cache_inner};
-use crate::{QueryDispatcherUnerased, QueryFlags};
 
 /// [`DepKindVTable`] constructors for special dep kinds that aren't queries.
 #[expect(non_snake_case, reason = "use non-snake case to avoid collision with query names")]
@@ -102,14 +102,14 @@ mod non_query {
 
 /// Shared implementation of the [`DepKindVTable`] constructor for queries.
 /// Called from macro-generated code for each query.
-pub(crate) fn make_dep_kind_vtable_for_query<'tcx, Q, Cache, const FLAGS: QueryFlags>(
+pub(crate) fn make_dep_kind_vtable_for_query<'tcx, Q, Cache>(
+    is_anon: bool,
     is_eval_always: bool,
 ) -> DepKindVTable<'tcx>
 where
-    Q: QueryDispatcherUnerased<'tcx, Cache, FLAGS>,
+    Q: QueryDispatcherUnerased<'tcx, Cache>,
     Cache: QueryCache + 'tcx,
 {
-    let is_anon = FLAGS.is_anon;
     let key_fingerprint_style = if is_anon {
         KeyFingerprintStyle::Opaque
     } else {
@@ -131,10 +131,10 @@ where
         is_eval_always,
         key_fingerprint_style,
         force_from_dep_node: Some(|tcx, dep_node, _| {
-            force_from_dep_node_inner(Q::query_dispatcher(tcx), tcx, dep_node)
+            force_from_dep_node_inner(Q::query_vtable(tcx), tcx, dep_node)
         }),
         try_load_from_on_disk_cache: Some(|tcx, dep_node| {
-            try_load_from_on_disk_cache_inner(Q::query_dispatcher(tcx), tcx, dep_node)
+            try_load_from_on_disk_cache_inner(Q::query_vtable(tcx), tcx, dep_node)
         }),
     }
 }