Update inherent_impls

Author: Zoxc

src/librustc/arena.rs

@@ -9,6 +9,8 @@ macro_rules! arena_types {
                 rustc::ty::subst::SubstsRef<$tcx>
             )>,
             [decode] specialization_graph: rustc::traits::specialization_graph::Graph,
+            // FIXME: We only allocate one of these. Optimize for that case?
+            [] crate_inherent_impls: rustc::ty::CrateInherentImpls,
         ], $tcx);
     )
 }

src/librustc/query/mod.rs

@@ -300,7 +300,7 @@ rustc_queries! {
         /// Maps a DefId of a type to a list of its inherent impls.
         /// Contains implementations of methods that are inherent to a type.
         /// Methods in these implementations don't need to be exported.
-        query inherent_impls(_: DefId) -> Lrc<Vec<DefId>> {
+        query inherent_impls(_: DefId) -> &'tcx [DefId] {
             eval_always
         }
     }
@@ -423,7 +423,7 @@ rustc_queries! {
         /// Not meant to be used directly outside of coherence.
         /// (Defined only for `LOCAL_CRATE`.)
         query crate_inherent_impls(k: CrateNum)
-            -> Lrc<CrateInherentImpls> {
+            -> &'tcx CrateInherentImpls {
             eval_always
             desc { "all inherent impls defined in crate `{:?}`", k }
         }

src/librustc/ty/mod.rs

@@ -3366,7 +3366,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
 /// (constructing this map requires touching the entire crate).
 #[derive(Clone, Debug, Default, HashStable)]
 pub struct CrateInherentImpls {
-    pub inherent_impls: DefIdMap<Lrc<Vec<DefId>>>,
+    pub inherent_impls: DefIdMap<Vec<DefId>>,
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)]

src/librustc_metadata/cstore_impl.rs

@@ -134,7 +134,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
         (cdata.mir_const_qualif(def_id.index), Lrc::new(BitSet::new_empty(0)))
     }
     fn_sig => { cdata.fn_sig(def_id.index, tcx) }
-    inherent_impls => { Lrc::new(cdata.get_inherent_implementations_for_type(def_id.index)) }
+    inherent_impls => { cdata.get_inherent_implementations_for_type(tcx, def_id.index) }
     is_const_fn_raw => { cdata.is_const_fn_raw(def_id.index) }
     is_foreign_item => { cdata.is_foreign_item(def_id.index) }
     describe_def => { cdata.get_def(def_id.index) }

src/librustc_metadata/decoder.rs

@@ -998,12 +998,15 @@ impl<'a, 'tcx> CrateMetadata {
         None
     }
 
-    pub fn get_inherent_implementations_for_type(&self, id: DefIndex) -> Vec<DefId> {
-        self.entry(id)
-            .inherent_impls
-            .decode(self)
-            .map(|index| self.local_def_id(index))
-            .collect()
+    pub fn get_inherent_implementations_for_type(
+        &self,
+        tcx: TyCtxt<'_, 'tcx, '_>,
+        id: DefIndex
+    ) -> &'tcx [DefId] {
+        tcx.arena.alloc_from_iter(self.entry(id)
+                                      .inherent_impls
+                                      .decode(self)
+                                      .map(|index| self.local_def_id(index)))
     }
 
     pub fn get_implementations_for_trait(&self,

src/librustc_typeck/coherence/inherent_impls.rs

@@ -13,14 +13,13 @@ use rustc::hir;
 use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::ty::{self, CrateInherentImpls, TyCtxt};
 
-use rustc_data_structures::sync::Lrc;
 use syntax::ast;
 use syntax_pos::Span;
 
 /// On-demand query: yields a map containing all types mapped to their inherent impls.
 pub fn crate_inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                       crate_num: CrateNum)
-                                      -> Lrc<CrateInherentImpls> {
+                                      -> &'tcx CrateInherentImpls {
     assert_eq!(crate_num, LOCAL_CRATE);
 
     let krate = tcx.hir().krate();
@@ -29,13 +28,13 @@ pub fn crate_inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
         impls_map: Default::default(),
     };
     krate.visit_all_item_likes(&mut collect);
-    Lrc::new(collect.impls_map)
+    tcx.arena.alloc(collect.impls_map)
 }
 
 /// On-demand query: yields a vector of the inherent impls for a specific type.
 pub fn inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                 ty_def_id: DefId)
-                                -> Lrc<Vec<DefId>> {
+                                -> &'tcx [DefId] {
     assert!(ty_def_id.is_local());
 
     // NB. Until we adopt the red-green dep-tracking algorithm (see
@@ -53,15 +52,11 @@ pub fn inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     //
     // [the plan]: https://github.com/rust-lang/rust-roadmap/issues/4
 
-    thread_local! {
-        static EMPTY_DEF_ID_VEC: Lrc<Vec<DefId>> = Lrc::new(vec![])
-    }
-
     let result = tcx.dep_graph.with_ignore(|| {
         let crate_map = tcx.crate_inherent_impls(ty_def_id.krate);
         match crate_map.inherent_impls.get(&ty_def_id) {
-            Some(v) => v.clone(),
-            None => EMPTY_DEF_ID_VEC.with(|v| v.clone())
+            Some(v) => &v[..],
+            None => &[],
         }
     });
 
@@ -289,13 +284,8 @@ impl<'a, 'tcx> InherentCollect<'a, 'tcx> {
             // type def ID, if there is a base type for this implementation and
             // the implementation does not have any associated traits.
             let impl_def_id = self.tcx.hir().local_def_id_from_hir_id(item.hir_id);
-            let mut rc_vec = self.impls_map.inherent_impls
-                                           .entry(def_id)
-                                           .or_default();
-
-            // At this point, there should not be any clones of the
-            // `Lrc`, so we can still safely push into it in place:
-            Lrc::get_mut(&mut rc_vec).unwrap().push(impl_def_id);
+            let vec = self.impls_map.inherent_impls.entry(def_id).or_default();
+            vec.push(impl_def_id);
         } else {
             struct_span_err!(self.tcx.sess,
                              item.span,