[WIP] One more attempt to optimize module_children

Author: petrochenkov

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -2266,13 +2266,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let (candidates, globs): (Vec<_>, Vec<_>) = candidates.into_iter().partition(|trait_did| {
             if let Some(parent_did) = parent_map.get(trait_did) {
                 // If the item is re-exported as `_`, we should suggest a glob-import instead.
-                if *parent_did != self.tcx.parent(*trait_did)
-                    && self
-                        .tcx
+                let tcx = self.tcx;
+                if *parent_did != tcx.parent(*trait_did)
+                    && tcx
                         .module_children(*parent_did)
                         .iter()
-                        .filter(|child| child.res.opt_def_id() == Some(*trait_did))
-                        .all(|child| child.ident.name == kw::Underscore)
+                        .filter(|child| child.opt_def_id() == Some(*trait_did))
+                        .all(|child| child.name(tcx) == kw::Underscore)
                 {
                     return false;
                 }

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -17,7 +17,7 @@ use rustc_hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE}
 use rustc_hir::definitions::{DefKey, DefPath, DefPathData, DefPathHash};
 use rustc_hir::diagnostic_items::DiagnosticItems;
 use rustc_index::{Idx, IndexVec};
-use rustc_middle::metadata::ModChild;
+use rustc_middle::metadata::{ModChild, ModChildData};
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use rustc_middle::mir::interpret::{AllocDecodingSession, AllocDecodingState};
 use rustc_middle::ty::codec::TyDecoder;
@@ -904,15 +904,17 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         let variants = if let ty::AdtKind::Enum = adt_kind {
             self.root
                 .tables
-                .module_children_non_reexports
+                .module_children
                 .get(self, item_id)
                 .expect("variants are not encoded for an enum")
                 .decode(self)
-                .filter_map(|index| {
-                    let kind = self.def_kind(index);
+                .filter_map(|child| {
+                    let ModChild::Def(def_id) = child else { bug!() };
+                    assert_eq!(def_id.krate, self.cnum);
+                    let kind = self.def_kind(def_id.index);
                     match kind {
                         DefKind::Ctor(..) => None,
-                        _ => Some(self.get_variant(&kind, index, did)),
+                        _ => Some(self.get_variant(&kind, def_id.index, did)),
                     }
                 })
                 .collect()
@@ -988,12 +990,12 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         DiagnosticItems { id_to_name, name_to_id }
     }
 
-    fn get_mod_child(self, id: DefIndex, sess: &Session) -> ModChild {
+    fn get_mod_child_data(self, id: DefIndex, sess: &Session) -> ModChildData {
         let ident = self.item_ident(id, sess);
         let res = Res::Def(self.def_kind(id), self.local_def_id(id));
         let vis = self.get_visibility(id);
 
-        ModChild { ident, res, vis, reexport_chain: Default::default() }
+        ModChildData { ident, res, vis, reexport_chain: Default::default() }
     }
 
     /// Iterates over all named children of the given module,
@@ -1011,21 +1013,15 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                 // the view of this crate as a proc macro crate.
                 if id == CRATE_DEF_INDEX {
                     for child_index in data.macros.decode(self) {
-                        yield self.get_mod_child(child_index, sess);
+                        yield ModChild::Def(self.local_def_id(child_index));
                     }
                 }
             } else {
                 // Iterate over all children.
-                let non_reexports = self.root.tables.module_children_non_reexports.get(self, id);
-                for child_index in non_reexports.unwrap().decode(self) {
-                    yield self.get_mod_child(child_index, sess);
-                }
-
-                let reexports = self.root.tables.module_children_reexports.get(self, id);
-                if !reexports.is_default() {
-                    for reexport in reexports.decode((self, sess)) {
-                        yield reexport;
-                    }
+                for child in
+                    self.root.tables.module_children.get(self, id).unwrap().decode((self, sess))
+                {
+                    yield child;
                 }
             }
         })

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -10,7 +10,7 @@ use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
 use rustc_middle::arena::ArenaAllocatable;
-use rustc_middle::metadata::ModChild;
+use rustc_middle::metadata::{ModChild, ModChildData};
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
 use rustc_middle::middle::stability::DeprecationEntry;
 use rustc_middle::query::LocalCrate;
@@ -441,12 +441,12 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
             }
 
             let mut add_child = |bfs_queue: &mut VecDeque<_>, child: &ModChild, parent: DefId| {
-                if !child.vis.is_public() {
+                if !child.vis(tcx).is_public() {
                     return;
                 }
 
-                if let Some(def_id) = child.res.opt_def_id() {
-                    if child.ident.name == kw::Underscore {
+                if let Some(def_id) = child.opt_def_id() {
+                    if child.name(tcx) == kw::Underscore {
                         fallback_map.push((def_id, parent));
                         return;
                     }
@@ -467,7 +467,7 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
                         Entry::Vacant(entry) => {
                             entry.insert(parent);
                             if matches!(
-                                child.res,
+                                child.res(tcx),
                                 Res::Def(DefKind::Mod | DefKind::Enum | DefKind::Trait, _)
                             ) {
                                 bfs_queue.push_back(def_id);
@@ -478,7 +478,7 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
             };
 
             while let Some(def) = bfs_queue.pop_front() {
-                for child in tcx.module_children(def).iter() {
+                for child in tcx.module_children(def) {
                     add_child(bfs_queue, child, def);
                 }
             }
@@ -512,6 +512,10 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
 }
 
 impl CStore {
+    pub fn mod_child_data_untracked(&self, def_id: DefId, sess: &Session) -> ModChildData {
+        self.get_crate_data(def_id.krate).get_mod_child_data(def_id.index, sess)
+    }
+
     pub fn ctor_untracked(&self, def: DefId) -> Option<(CtorKind, DefId)> {
         self.get_crate_data(def.krate).get_ctor(def.index)
     }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1364,9 +1364,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         record!(self.tables.params_in_repr[def_id] <- params_in_repr);
 
         if adt_def.is_enum() {
-            let module_children = tcx.module_children_non_reexports(local_def_id);
-            record_array!(self.tables.module_children_non_reexports[def_id] <-
-                module_children.iter().map(|def_id| def_id.local_def_index));
+            record_array!(self.tables.module_children[def_id] <-
+                tcx.module_children_local(local_def_id));
         } else {
             // For non-enum, there is only one variant, and its def_id is the adt's.
             debug_assert_eq!(adt_def.variants().len(), 1);
@@ -1412,12 +1411,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             // Encode this here because we don't do it in encode_def_ids.
             record!(self.tables.expn_that_defined[def_id] <- tcx.expn_that_defined(local_def_id));
         } else {
-            let non_reexports = tcx.module_children_non_reexports(local_def_id);
-            record_array!(self.tables.module_children_non_reexports[def_id] <-
-                non_reexports.iter().map(|def_id| def_id.local_def_index));
-
-            record_defaulted_array!(self.tables.module_children_reexports[def_id] <-
-                tcx.module_children_reexports(local_def_id));
+            record_array!(self.tables.module_children[def_id] <-
+                tcx.module_children_local(local_def_id));
         }
     }
 
@@ -1676,9 +1671,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             hir::ItemKind::Trait(..) => {
                 record!(self.tables.trait_def[def_id] <- self.tcx.trait_def(def_id));
 
-                let module_children = tcx.module_children_non_reexports(item.owner_id.def_id);
-                record_array!(self.tables.module_children_non_reexports[def_id] <-
-                    module_children.iter().map(|def_id| def_id.local_def_index));
+                record_array!(self.tables.module_children[def_id] <-
+                    tcx.module_children_local(item.owner_id.def_id));
 
                 let associated_item_def_ids = self.tcx.associated_item_def_ids(def_id);
                 record_associated_item_def_ids(self, associated_item_def_ids);

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -357,11 +357,10 @@ define_tables! {
     associated_types_for_impl_traits_in_associated_fn: Table<DefIndex, LazyArray<DefId>>,
     opt_rpitit_info: Table<DefIndex, Option<LazyValue<ty::ImplTraitInTraitData>>>,
     unused_generic_params: Table<DefIndex, UnusedGenericParams>,
-    module_children_reexports: Table<DefIndex, LazyArray<ModChild>>,
 
 - optional:
     attributes: Table<DefIndex, LazyArray<ast::Attribute>>,
-    module_children_non_reexports: Table<DefIndex, LazyArray<DefIndex>>,
+    module_children: Table<DefIndex, LazyArray<ModChild>>,
     associated_item_or_field_def_ids: Table<DefIndex, LazyArray<DefIndex>>,
     opt_def_kind: Table<DefIndex, DefKind>,
     visibility: Table<DefIndex, LazyValue<ty::Visibility<DefIndex>>>,

compiler/rustc_middle/src/metadata.rs

@@ -1,9 +1,10 @@
 use crate::ty;
 
+use crate::ty::TyCtxt;
 use rustc_hir::def::Res;
 use rustc_macros::HashStable;
 use rustc_span::def_id::DefId;
-use rustc_span::symbol::Ident;
+use rustc_span::symbol::{Ident, Symbol};
 use smallvec::SmallVec;
 
 /// A simplified version of `ImportKind` from resolve.
@@ -32,7 +33,7 @@ impl Reexport {
 /// Module child can be either a proper item or a reexport (including private imports).
 /// In case of reexport all the fields describe the reexport item itself, not what it refers to.
 #[derive(Debug, TyEncodable, TyDecodable, HashStable)]
-pub struct ModChild {
+pub struct ModChildData {
     /// Name of the item.
     pub ident: Ident,
     /// Resolution result corresponding to the item.
@@ -44,3 +45,55 @@ pub struct ModChild {
     /// Empty if the module child is a proper item.
     pub reexport_chain: SmallVec<[Reexport; 2]>,
 }
+
+#[derive(Debug, TyEncodable, TyDecodable, HashStable)]
+pub enum ModChild {
+    Def(DefId),
+    Reexport(ModChildData),
+}
+
+impl ModChild {
+    pub fn res(&self, tcx: TyCtxt<'_>) -> Res<!> {
+        match self {
+            ModChild::Def(def_id) => Res::Def(tcx.def_kind(*def_id), *def_id),
+            ModChild::Reexport(child) => child.res,
+        }
+    }
+
+    pub fn opt_def_id(&self) -> Option<DefId> {
+        match self {
+            ModChild::Def(def_id) => Some(*def_id),
+            ModChild::Reexport(child) => child.res.opt_def_id(),
+        }
+    }
+
+    pub fn vis(&self, tcx: TyCtxt<'_>) -> ty::Visibility<DefId> {
+        match self {
+            ModChild::Def(def_id) => tcx.visibility(*def_id),
+            ModChild::Reexport(child) => child.vis,
+        }
+    }
+
+    pub fn name(&self, tcx: TyCtxt<'_>) -> Symbol {
+        match self {
+            ModChild::Def(def_id) => tcx.item_name(*def_id),
+            ModChild::Reexport(child) => child.ident.name,
+        }
+    }
+
+    // FIXME: `opt_item_ident` is buggy and doesn't decode hygiene correctly,
+    // figure out what happens.
+    pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
+        match self {
+            ModChild::Def(def_id) => tcx.opt_item_ident(*def_id).unwrap(),
+            ModChild::Reexport(child) => child.ident,
+        }
+    }
+
+    pub fn reexport_chain(&self) -> &[Reexport] {
+        match self {
+            ModChild::Def(_) => &[],
+            ModChild::Reexport(child) => &child.reexport_chain,
+        }
+    }
+}

compiler/rustc_middle/src/ty/context.rs

@@ -2437,26 +2437,8 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
-    /// Named module children from all items except `use` and `extern crate` imports.
-    ///
-    /// In addition to regular items this list also includes struct or variant constructors, and
-    /// items inside `extern {}` blocks because all of them introduce names into parent module.
-    /// For non-reexported children every such name is associated with a separate `DefId`.
-    ///
-    /// Module here is understood in name resolution sense - it can be a `mod` item,
-    /// or a crate root, or an enum, or a trait.
-    pub fn module_children_non_reexports(self, def_id: LocalDefId) -> &'tcx [LocalDefId] {
-        self.resolutions(()).module_children_non_reexports.get(&def_id).map_or(&[], |v| &v[..])
-    }
-
-    /// Named module children from `use` and `extern crate` imports.
-    ///
-    /// Reexported names are not associated with individual `DefId`s,
-    /// e.g. a glob import can introduce a lot of names, all with the same `DefId`.
-    /// That's why the list needs to contain `ModChild` structures describing all the names
-    /// individually instead of `DefId`s.
-    pub fn module_children_reexports(self, def_id: LocalDefId) -> &'tcx [ModChild] {
-        self.resolutions(()).module_children_reexports.get(&def_id).map_or(&[], |v| &v[..])
+    pub fn module_children_local(self, def_id: LocalDefId) -> &'tcx [ModChild] {
+        self.resolutions(()).module_children.get(&def_id).map_or(&[], |v| &v[..])
     }
 }
 

compiler/rustc_middle/src/ty/mod.rs

@@ -166,8 +166,7 @@ pub struct ResolverGlobalCtxt {
     pub effective_visibilities: EffectiveVisibilities,
     pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
     pub maybe_unused_trait_imports: FxIndexSet<LocalDefId>,
-    pub module_children_non_reexports: LocalDefIdMap<Vec<LocalDefId>>,
-    pub module_children_reexports: LocalDefIdMap<Vec<ModChild>>,
+    pub module_children: LocalDefIdMap<Vec<ModChild>>,
     pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
     pub main_def: Option<MainDefinition>,
     pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,