Auto merge of #59540 - Zoxc:the-arena-2, r=<try>

[WIP] Use arenas to avoid Lrc in queries #1

Based on #59536.

Author: bors

src/librustc/arena.rs

@@ -16,6 +16,7 @@ macro_rules! arena_types {
             )>,
             [few] mir_keys: rustc::util::nodemap::DefIdSet,
             [decode] specialization_graph: rustc::traits::specialization_graph::Graph,
+            [few] resolve_lifetimes: rustc::middle::resolve_lifetime::ResolveLifetimes,
         ], $tcx);
     )
 }

src/librustc/middle/resolve_lifetime.rs

@@ -15,7 +15,6 @@ use crate::rustc::lint;
 use crate::session::Session;
 use crate::util::nodemap::{DefIdMap, FxHashMap, FxHashSet, HirIdMap, HirIdSet};
 use errors::{Applicability, DiagnosticBuilder};
-use rustc_data_structures::sync::Lrc;
 use rustc_macros::HashStable;
 use std::borrow::Cow;
 use std::cell::Cell;
@@ -211,10 +210,10 @@ struct NamedRegionMap {
 /// See [`NamedRegionMap`].
 #[derive(Default)]
 pub struct ResolveLifetimes {
-    defs: FxHashMap<LocalDefId, Lrc<FxHashMap<ItemLocalId, Region>>>,
-    late_bound: FxHashMap<LocalDefId, Lrc<FxHashSet<ItemLocalId>>>,
+    defs: FxHashMap<LocalDefId, FxHashMap<ItemLocalId, Region>>,
+    late_bound: FxHashMap<LocalDefId, FxHashSet<ItemLocalId>>,
     object_lifetime_defaults:
-        FxHashMap<LocalDefId, Lrc<FxHashMap<ItemLocalId, Lrc<Vec<ObjectLifetimeDefault>>>>>,
+        FxHashMap<LocalDefId, FxHashMap<ItemLocalId, Vec<ObjectLifetimeDefault>>>,
 }
 
 impl_stable_hash_for!(struct crate::middle::resolve_lifetime::ResolveLifetimes {
@@ -347,23 +346,21 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
 
         named_region_map: |tcx, id| {
             let id = LocalDefId::from_def_id(DefId::local(id)); // (*)
-            tcx.resolve_lifetimes(LOCAL_CRATE).defs.get(&id).cloned()
+            tcx.resolve_lifetimes(LOCAL_CRATE).defs.get(&id)
         },
 
         is_late_bound_map: |tcx, id| {
             let id = LocalDefId::from_def_id(DefId::local(id)); // (*)
             tcx.resolve_lifetimes(LOCAL_CRATE)
                 .late_bound
                 .get(&id)
-                .cloned()
         },
 
         object_lifetime_defaults_map: |tcx, id| {
             let id = LocalDefId::from_def_id(DefId::local(id)); // (*)
             tcx.resolve_lifetimes(LOCAL_CRATE)
                 .object_lifetime_defaults
                 .get(&id)
-                .cloned()
         },
 
         ..*providers
@@ -379,7 +376,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
 fn resolve_lifetimes<'tcx>(
     tcx: TyCtxt<'_, 'tcx, 'tcx>,
     for_krate: CrateNum,
-) -> Lrc<ResolveLifetimes> {
+) -> &'tcx ResolveLifetimes {
     assert_eq!(for_krate, LOCAL_CRATE);
 
     let named_region_map = krate(tcx);
@@ -388,24 +385,22 @@ fn resolve_lifetimes<'tcx>(
 
     for (hir_id, v) in named_region_map.defs {
         let map = rl.defs.entry(hir_id.owner_local_def_id()).or_default();
-        Lrc::get_mut(map).unwrap().insert(hir_id.local_id, v);
+        map.insert(hir_id.local_id, v);
     }
     for hir_id in named_region_map.late_bound {
         let map = rl.late_bound
             .entry(hir_id.owner_local_def_id())
             .or_default();
-        Lrc::get_mut(map).unwrap().insert(hir_id.local_id);
+        map.insert(hir_id.local_id);
     }
     for (hir_id, v) in named_region_map.object_lifetime_defaults {
         let map = rl.object_lifetime_defaults
             .entry(hir_id.owner_local_def_id())
             .or_default();
-        Lrc::get_mut(map)
-            .unwrap()
-            .insert(hir_id.local_id, Lrc::new(v));
+        map.insert(hir_id.local_id, v);
     }
 
-    Lrc::new(rl)
+    tcx.arena.alloc(rl)
 }
 
 fn krate<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>) -> NamedRegionMap {

src/librustc/query/mod.rs

@@ -754,19 +754,19 @@ rustc_queries! {
 
     BorrowChecking {
         // Lifetime resolution. See `middle::resolve_lifetimes`.
-        query resolve_lifetimes(_: CrateNum) -> Lrc<ResolveLifetimes> {
+        query resolve_lifetimes(_: CrateNum) -> &'tcx ResolveLifetimes {
             desc { "resolving lifetimes" }
         }
         query named_region_map(_: DefIndex) ->
-            Option<Lrc<FxHashMap<ItemLocalId, Region>>> {
+            Option<&'tcx FxHashMap<ItemLocalId, Region>> {
             desc { "looking up a named region" }
         }
         query is_late_bound_map(_: DefIndex) ->
-            Option<Lrc<FxHashSet<ItemLocalId>>> {
+            Option<&'tcx FxHashSet<ItemLocalId>> {
             desc { "testing if a region is late bound" }
         }
         query object_lifetime_defaults_map(_: DefIndex)
-            -> Option<Lrc<FxHashMap<ItemLocalId, Lrc<Vec<ObjectLifetimeDefault>>>>> {
+            -> Option<&'tcx FxHashMap<ItemLocalId, Vec<ObjectLifetimeDefault>>> {
             desc { "looking up lifetime defaults for a region" }
         }
     }

src/librustc/ty/context.rs

@@ -2991,10 +2991,10 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 
     pub fn object_lifetime_defaults(self, id: HirId)
-        -> Option<Lrc<Vec<ObjectLifetimeDefault>>>
+        -> Option<&'gcx [ObjectLifetimeDefault]>
     {
         self.object_lifetime_defaults_map(id.owner)
-            .and_then(|map| map.get(&id.local_id).cloned())
+            .and_then(|map| map.get(&id.local_id).map(|v| &**v))
     }
 }