rustc_metadata: Split children into multiple tables

instead of merging everything into a single bag.

If it's acceptable from performance point of view, then it's more clear to keep this stuff organized more in accordance with its use.

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -876,16 +876,11 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             variant_did,
             ctor,
             data.discr,
-            self.root
-                .tables
-                .children
-                .get(self, index)
-                .expect("fields are not encoded for a variant")
-                .decode(self)
-                .map(|index| ty::FieldDef {
-                    did: self.local_def_id(index),
-                    name: self.item_name(index),
-                    vis: self.get_visibility(index),
+            self.get_associated_item_or_field_def_ids(index)
+                .map(|did| ty::FieldDef {
+                    did,
+                    name: self.item_name(did.index),
+                    vis: self.get_visibility(did.index),
                 })
                 .collect(),
             adt_kind,
@@ -910,7 +905,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         let variants = if let ty::AdtKind::Enum = adt_kind {
             self.root
                 .tables
-                .children
+                .module_children_non_reexports
                 .get(self, item_id)
                 .expect("variants are not encoded for an enum")
                 .decode(self)
@@ -1022,11 +1017,9 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                 }
             } else {
                 // Iterate over all children.
-                for child_index in self.root.tables.children.get(self, id).unwrap().decode(self) {
-                    // FIXME: Do not encode RPITITs as a part of this list.
-                    if self.root.tables.opt_rpitit_info.get(self, child_index).is_none() {
-                        yield self.get_mod_child(child_index, sess);
-                    }
+                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);
@@ -1058,17 +1051,16 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             .map_or(false, |ident| ident.name == kw::SelfLower)
     }
 
-    fn get_associated_item_def_ids(
+    fn get_associated_item_or_field_def_ids(
         self,
         id: DefIndex,
-        sess: &'a Session,
     ) -> impl Iterator<Item = DefId> + 'a {
         self.root
             .tables
-            .children
+            .associated_item_or_field_def_ids
             .get(self, id)
-            .expect("associated items not encoded for an item")
-            .decode((self, sess))
+            .unwrap_or_else(|| self.missing("associated_item_or_field_def_ids", id))
+            .decode(self)
             .map(move |child_index| self.local_def_id(child_index))
     }
 

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

@@ -276,7 +276,7 @@ provide! { tcx, def_id, other, cdata,
         tcx.calculate_dtor(def_id, |_,_| Ok(()))
     }
     associated_item_def_ids => {
-        tcx.arena.alloc_from_iter(cdata.get_associated_item_def_ids(def_id.index, tcx.sess))
+        tcx.arena.alloc_from_iter(cdata.get_associated_item_or_field_def_ids(def_id.index))
     }
     associated_item => { cdata.get_associated_item(def_id.index, tcx.sess) }
     inherent_impls => { cdata.get_inherent_implementations_for_type(tcx, def_id.index) }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1367,7 +1367,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
 
         if adt_def.is_enum() {
             let module_children = tcx.module_children_non_reexports(local_def_id);
-            record_array!(self.tables.children[def_id] <-
+            record_array!(self.tables.module_children_non_reexports[def_id] <-
                 module_children.iter().map(|def_id| def_id.local_def_index));
         } else {
             // For non-enum, there is only one variant, and its def_id is the adt's.
@@ -1385,7 +1385,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             record!(self.tables.variant_data[variant.def_id] <- data);
 
             self.tables.constness.set_some(variant.def_id.index, hir::Constness::Const);
-            record_array!(self.tables.children[variant.def_id] <- variant.fields.iter().map(|f| {
+            record_array!(self.tables.associated_item_or_field_def_ids[variant.def_id] <- variant.fields.iter().map(|f| {
                 assert!(f.did.is_local());
                 f.did.index
             }));
@@ -1415,7 +1415,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             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.children[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] <-
@@ -1617,7 +1617,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         debug!("EncodeContext::encode_info_for_item({:?})", def_id);
 
         let record_associated_item_def_ids = |this: &mut Self, def_ids: &[DefId]| {
-            record_array!(this.tables.children[def_id] <- def_ids.iter().map(|&def_id| {
+            record_array!(this.tables.associated_item_or_field_def_ids[def_id] <- def_ids.iter().map(|&def_id| {
                 assert!(def_id.is_local());
                 def_id.index
             }))
@@ -1678,6 +1678,10 @@ 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));
+
                 let associated_item_def_ids = self.tcx.associated_item_def_ids(def_id);
                 record_associated_item_def_ids(self, associated_item_def_ids);
                 for &item_def_id in associated_item_def_ids {

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -361,7 +361,8 @@ define_tables! {
 
 - optional:
     attributes: Table<DefIndex, LazyArray<ast::Attribute>>,
-    children: Table<DefIndex, LazyArray<DefIndex>>,
+    module_children_non_reexports: Table<DefIndex, LazyArray<DefIndex>>,
+    associated_item_or_field_def_ids: Table<DefIndex, LazyArray<DefIndex>>,
     opt_def_kind: Table<DefIndex, DefKind>,
     visibility: Table<DefIndex, LazyValue<ty::Visibility<DefIndex>>>,
     def_span: Table<DefIndex, LazyValue<Span>>,

compiler/rustc_middle/src/query/mod.rs

@@ -670,9 +670,10 @@ rustc_queries! {
         desc { "computing the inferred outlives predicates for items in this crate" }
     }
 
-    /// Maps from an impl/trait `DefId` to a list of the `DefId`s of its items.
+    /// Maps from an impl/trait or struct/variant `DefId`
+    /// to a list of the `DefId`s of its associated items or fields.
     query associated_item_def_ids(key: DefId) -> &'tcx [DefId] {
-        desc { |tcx| "collecting associated items of `{}`", tcx.def_path_str(key) }
+        desc { |tcx| "collecting associated items or fields of `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
     }