Merge #8284

8284: Reduce memory usage by using global `Arc`-based interning r=jonas-schievink a=jonas-schievink

This saves around 50 mb when running `analysis-stats` on r-a itself. Not a lot, but this infra can be easily reused to intern more stuff.

Co-authored-by: Jonas Schievink <[email protected]>

1 files changed, 10 insertions, 84 deletions

diff --git a/crates/hir_def/src/item_tree.rs b/crates/hir_def/src/item_tree.rs
index 5449bbf5d..69a313c7e 100644
--- a/crates/hir_def/src/item_tree.rs
+++ b/crates/hir_def/src/item_tree.rs
@@ -30,6 +30,7 @@ use crate::{
     attr::{Attrs, RawAttrs},
     db::DefDatabase,
     generics::GenericParams,
+    intern::Interned,
     path::{path, AssociatedTypeBinding, GenericArgs, ImportAlias, ModPath, Path, PathKind},
     type_ref::{Mutability, TraitRef, TypeBound, TypeRef},
     visibility::RawVisibility,
@@ -146,8 +147,6 @@ impl ItemTree {
                 macro_defs,
                 vis,
                 generics,
-                type_refs,
-                trait_refs,
                 inner_items,
             } = &mut **data;
 
@@ -172,9 +171,6 @@ impl ItemTree {
 
             vis.arena.shrink_to_fit();
             generics.arena.shrink_to_fit();
-            type_refs.arena.shrink_to_fit();
-            type_refs.map.shrink_to_fit();
-            trait_refs.map.shrink_to_fit();
 
             inner_items.shrink_to_fit();
         }
@@ -271,58 +267,6 @@ static EMPTY_GENERICS: GenericParams = GenericParams {
     where_predicates: Vec::new(),
 };
 
-/// `TypeRef` interner.
-#[derive(Default, Debug, Eq, PartialEq)]
-struct TypeRefStorage {
-    arena: Arena<Arc<TypeRef>>,
-    map: FxHashMap<Arc<TypeRef>, Idx<Arc<TypeRef>>>,
-}
-
-impl TypeRefStorage {
-    // Note: We lie about the `Idx<TypeRef>` to hide the interner details.
-
-    fn intern(&mut self, ty: TypeRef) -> Idx<TypeRef> {
-        if let Some(id) = self.map.get(&ty) {
-            return Idx::from_raw(id.into_raw());
-        }
-
-        let ty = Arc::new(ty);
-        let idx = self.arena.alloc(ty.clone());
-        self.map.insert(ty, idx);
-        Idx::from_raw(idx.into_raw())
-    }
-
-    fn lookup(&self, id: Idx<TypeRef>) -> &TypeRef {
-        &self.arena[Idx::from_raw(id.into_raw())]
-    }
-}
-
-/// `TraitRef` interner.
-#[derive(Default, Debug, Eq, PartialEq)]
-struct TraitRefStorage {
-    arena: Arena<Arc<TraitRef>>,
-    map: FxHashMap<Arc<TraitRef>, Idx<Arc<TraitRef>>>,
-}
-
-impl TraitRefStorage {
-    // Note: We lie about the `Idx<TraitRef>` to hide the interner details.
-
-    fn intern(&mut self, ty: TraitRef) -> Idx<TraitRef> {
-        if let Some(id) = self.map.get(&ty) {
-            return Idx::from_raw(id.into_raw());
-        }
-
-        let ty = Arc::new(ty);
-        let idx = self.arena.alloc(ty.clone());
-        self.map.insert(ty, idx);
-        Idx::from_raw(idx.into_raw())
-    }
-
-    fn lookup(&self, id: Idx<TraitRef>) -> &TraitRef {
-        &self.arena[Idx::from_raw(id.into_raw())]
-    }
-}
-
 #[derive(Default, Debug, Eq, PartialEq)]
 struct ItemTreeData {
     imports: Arena<Import>,
@@ -346,8 +290,6 @@ struct ItemTreeData {
 
     vis: ItemVisibilities,
     generics: GenericParamsStorage,
-    type_refs: TypeRefStorage,
-    trait_refs: TraitRefStorage,
 
     inner_items: FxHashMap<FileAstId<ast::BlockExpr>, SmallVec<[ModItem; 1]>>,
 }
@@ -577,22 +519,6 @@ impl Index<GenericParamsId> for ItemTree {
     }
 }
 
-impl Index<Idx<TypeRef>> for ItemTree {
-    type Output = TypeRef;
-
-    fn index(&self, id: Idx<TypeRef>) -> &Self::Output {
-        self.data().type_refs.lookup(id)
-    }
-}
-
-impl Index<Idx<TraitRef>> for ItemTree {
-    type Output = TraitRef;
-
-    fn index(&self, id: Idx<TraitRef>) -> &Self::Output {
-        self.data().trait_refs.lookup(id)
-    }
-}
-
 impl<N: ItemTreeNode> Index<FileItemTreeId<N>> for ItemTree {
     type Output = N;
     fn index(&self, id: FileItemTreeId<N>) -> &N {
@@ -637,13 +563,13 @@ pub struct Function {
     /// `extern "abi" fn`).
     pub is_in_extern_block: bool,
     pub params: IdRange<Param>,
-    pub ret_type: Idx<TypeRef>,
+    pub ret_type: Interned<TypeRef>,
     pub ast_id: FileAstId<ast::Fn>,
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum Param {
-    Normal(Idx<TypeRef>),
+    Normal(Interned<TypeRef>),
     Varargs,
 }
 
@@ -699,7 +625,7 @@ pub struct Const {
     /// const _: () = ();
     pub name: Option<Name>,
     pub visibility: RawVisibilityId,
-    pub type_ref: Idx<TypeRef>,
+    pub type_ref: Interned<TypeRef>,
     pub ast_id: FileAstId<ast::Const>,
 }
 
@@ -710,7 +636,7 @@ pub struct Static {
     pub mutable: bool,
     /// Whether the static is in an `extern` block.
     pub is_extern: bool,
-    pub type_ref: Idx<TypeRef>,
+    pub type_ref: Interned<TypeRef>,
     pub ast_id: FileAstId<ast::Static>,
 }
 
@@ -729,8 +655,8 @@ pub struct Trait {
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct Impl {
     pub generic_params: GenericParamsId,
-    pub target_trait: Option<Idx<TraitRef>>,
-    pub self_ty: Idx<TypeRef>,
+    pub target_trait: Option<Interned<TraitRef>>,
+    pub self_ty: Interned<TypeRef>,
     pub is_negative: bool,
     pub items: Box<[AssocItem]>,
     pub ast_id: FileAstId<ast::Impl>,
@@ -743,7 +669,7 @@ pub struct TypeAlias {
     /// Bounds on the type alias itself. Only valid in trait declarations, eg. `type Assoc: Copy;`.
     pub bounds: Box<[TypeBound]>,
     pub generic_params: GenericParamsId,
-    pub type_ref: Option<Idx<TypeRef>>,
+    pub type_ref: Option<Interned<TypeRef>>,
     pub is_extern: bool,
     pub ast_id: FileAstId<ast::TypeAlias>,
 }
@@ -768,7 +694,7 @@ pub enum ModKind {
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct MacroCall {
     /// Path to the called macro.
-    pub path: ModPath,
+    pub path: Interned<ModPath>,
     pub ast_id: FileAstId<ast::MacroCall>,
 }
 
@@ -933,6 +859,6 @@ pub enum Fields {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Field {
     pub name: Name,
-    pub type_ref: Idx<TypeRef>,
+    pub type_ref: Interned<TypeRef>,
     pub visibility: RawVisibilityId,
 }