Cache whether a body has inline consts

Author: oli-obk

compiler/rustc_ast_lowering/src/expr.rs

@@ -74,7 +74,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
             let kind = match &e.kind {
                 ExprKind::Array(exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)),
-                ExprKind::ConstBlock(c) => hir::ExprKind::ConstBlock(self.lower_expr(c)),
+                ExprKind::ConstBlock(c) => {
+                    self.has_inline_consts = true;
+                    hir::ExprKind::ConstBlock(self.lower_expr(c))
+                }
                 ExprKind::Repeat(expr, count) => {
                     let expr = self.lower_expr(expr);
                     let count = self.lower_array_length(count);

compiler/rustc_ast_lowering/src/lib.rs

@@ -96,6 +96,8 @@ struct LoweringContext<'a, 'hir> {
 
     /// Bodies inside the owner being lowered.
     bodies: Vec<(hir::ItemLocalId, &'hir hir::Body<'hir>)>,
+    /// Whether there were inline consts that typeck will split out into bodies
+    has_inline_consts: bool,
     /// Attributes inside the owner being lowered.
     attrs: SortedMap<hir::ItemLocalId, &'hir [Attribute]>,
     /// Collect items that were created by lowering the current owner.
@@ -158,6 +160,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             item_local_id_counter: hir::ItemLocalId::ZERO,
             node_id_to_local_id: Default::default(),
             trait_map: Default::default(),
+            has_inline_consts: false,
 
             // Lowering state.
             catch_scope: None,
@@ -567,6 +570,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
         let current_attrs = std::mem::take(&mut self.attrs);
         let current_bodies = std::mem::take(&mut self.bodies);
+        let current_has_inline_consts = std::mem::take(&mut self.has_inline_consts);
         let current_node_ids = std::mem::take(&mut self.node_id_to_local_id);
         let current_trait_map = std::mem::take(&mut self.trait_map);
         let current_owner =
@@ -593,6 +597,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
         self.attrs = current_attrs;
         self.bodies = current_bodies;
+        self.has_inline_consts = current_has_inline_consts;
         self.node_id_to_local_id = current_node_ids;
         self.trait_map = current_trait_map;
         self.current_hir_id_owner = current_owner;
@@ -629,6 +634,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let attrs = std::mem::take(&mut self.attrs);
         let mut bodies = std::mem::take(&mut self.bodies);
         let trait_map = std::mem::take(&mut self.trait_map);
+        let has_inline_consts = std::mem::take(&mut self.has_inline_consts);
 
         #[cfg(debug_assertions)]
         for (id, attrs) in attrs.iter() {
@@ -646,7 +652,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             self.tcx.hash_owner_nodes(node, &bodies, &attrs);
         let num_nodes = self.item_local_id_counter.as_usize();
         let (nodes, parenting) = index::index_hir(self.tcx, node, &bodies, num_nodes);
-        let nodes = hir::OwnerNodes { opt_hash_including_bodies, nodes, bodies };
+        let nodes = hir::OwnerNodes { opt_hash_including_bodies, nodes, bodies, has_inline_consts };
         let attrs = hir::AttributeMap { map: attrs, opt_hash: attrs_hash };
 
         self.arena.alloc(hir::OwnerInfo { nodes, parenting, attrs, trait_map })

compiler/rustc_hir/src/hir.rs

@@ -876,6 +876,9 @@ pub struct OwnerNodes<'tcx> {
     pub nodes: IndexVec<ItemLocalId, ParentedNode<'tcx>>,
     /// Content of local bodies.
     pub bodies: SortedMap<ItemLocalId, &'tcx Body<'tcx>>,
+    /// Whether the body contains inline constants that are created for the query system during typeck
+    /// of the body.
+    pub has_inline_consts: bool,
 }
 
 impl<'tcx> OwnerNodes<'tcx> {

compiler/rustc_hir/src/stable_hash_impls.rs

@@ -93,7 +93,8 @@ impl<'tcx, HirCtx: crate::HashStableContext> HashStable<HirCtx> for OwnerNodes<'
         // `local_id_to_def_id` is also ignored because is dependent on the body, then just hashing
         // the body satisfies the condition of two nodes being different have different
         // `hash_stable` results.
-        let OwnerNodes { opt_hash_including_bodies, nodes: _, bodies: _ } = *self;
+        let OwnerNodes { opt_hash_including_bodies, nodes: _, bodies: _, has_inline_consts: _ } =
+            *self;
         opt_hash_including_bodies.unwrap().hash_stable(hcx, hasher);
     }
 }

compiler/rustc_middle/src/ty/context.rs

@@ -737,6 +737,7 @@ impl<'tcx> TyCtxtFeed<'tcx, LocalDefId> {
                 1,
             ),
             bodies,
+            has_inline_consts: false,
         })));
         self.feed_owner_id().hir_attrs(attrs);
     }

compiler/rustc_mir_transform/src/lib.rs

@@ -225,7 +225,10 @@ fn mir_keys(tcx: TyCtxt<'_>, (): ()) -> FxIndexSet<LocalDefId> {
     // Inline consts' bodies are created in
     // typeck instead of during ast lowering, like all other bodies so far.
     for def_id in tcx.hir().body_owners() {
-        set.extend(tcx.typeck(def_id).inline_consts.values())
+        // Incremental performance optimization: only load typeck results for things that actually have inline consts
+        if tcx.hir_owner_nodes(tcx.hir().body_owned_by(def_id).hir_id.owner).has_inline_consts {
+            set.extend(tcx.typeck(def_id).inline_consts.values())
+        }
     }
 
     // Additionally, tuple struct/variant constructors have MIR, but