Reduce memory usage by using global Arc-based interning

crates/hir/src/display.rs

@@ -91,7 +91,7 @@ impl HirDisplay for Function {
         let ret_type = if !qual.is_async {
             &data.ret_type
         } else {
-            match &data.ret_type {
+            match &*data.ret_type {
                 TypeRef::ImplTrait(bounds) => match &bounds[0] {
                     TypeBound::Path(path) => {
                         path.segments().iter().last().unwrap().args_and_bindings.unwrap().bindings

crates/hir/src/lib.rs

@@ -957,7 +957,7 @@ impl SelfParam {
         func_data
             .params
             .first()
-            .map(|param| match *param {
+            .map(|param| match &**param {
                 TypeRef::Reference(.., mutability) => match mutability {
                     hir_def::type_ref::Mutability::Shared => Access::Shared,
                     hir_def::type_ref::Mutability::Mut => Access::Exclusive,
@@ -1011,7 +1011,7 @@ impl Const {
     }
 
     pub fn type_ref(self, db: &dyn HirDatabase) -> TypeRef {
-        db.const_data(self.id).type_ref.clone()
+        db.const_data(self.id).type_ref.as_ref().clone()
     }
 }
 
@@ -1101,7 +1101,7 @@ impl TypeAlias {
     }
 
     pub fn type_ref(self, db: &dyn HirDatabase) -> Option<TypeRef> {
-        db.type_alias_data(self.id).type_ref.clone()
+        db.type_alias_data(self.id).type_ref.as_deref().cloned()
     }
 
     pub fn ty(self, db: &dyn HirDatabase) -> Type {
@@ -1615,7 +1615,7 @@ impl Impl {
     // FIXME: the return type is wrong. This should be a hir version of
     // `TraitRef` (ie, resolved `TypeRef`).
     pub fn trait_(self, db: &dyn HirDatabase) -> Option<TraitRef> {
-        db.impl_data(self.id).target_trait.clone()
+        db.impl_data(self.id).target_trait.as_deref().cloned()
     }
 
     pub fn self_ty(self, db: &dyn HirDatabase) -> Type {

crates/hir_def/Cargo.toml

@@ -11,6 +11,7 @@ doctest = false
 
 [dependencies]
 cov-mark = { version = "1.1", features = ["thread-local"] }
+dashmap = { version = "4.0.2", features = ["raw-api"] }
 log = "0.4.8"
 once_cell = "1.3.1"
 rustc-hash = "1.1.0"

crates/hir_def/src/adt.rs

@@ -15,6 +15,7 @@ use tt::{Delimiter, DelimiterKind, Leaf, Subtree, TokenTree};
 use crate::{
     body::{CfgExpander, LowerCtx},
     db::DefDatabase,
+    intern::Interned,
     item_tree::{AttrOwner, Field, Fields, ItemTree, ModItem, RawVisibilityId},
     src::HasChildSource,
     src::HasSource,
@@ -58,7 +59,7 @@ pub enum VariantData {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct FieldData {
     pub name: Name,
-    pub type_ref: TypeRef,
+    pub type_ref: Interned<TypeRef>,
     pub visibility: RawVisibility,
 }
 
@@ -292,7 +293,7 @@ fn lower_struct(
                     || Either::Left(fd.clone()),
                     || FieldData {
                         name: Name::new_tuple_field(i),
-                        type_ref: TypeRef::from_ast_opt(&ctx, fd.ty()),
+                        type_ref: Interned::new(TypeRef::from_ast_opt(&ctx, fd.ty())),
                         visibility: RawVisibility::from_ast(db, ast.with_value(fd.visibility())),
                     },
                 );
@@ -309,7 +310,7 @@ fn lower_struct(
                     || Either::Right(fd.clone()),
                     || FieldData {
                         name: fd.name().map(|n| n.as_name()).unwrap_or_else(Name::missing),
-                        type_ref: TypeRef::from_ast_opt(&ctx, fd.ty()),
+                        type_ref: Interned::new(TypeRef::from_ast_opt(&ctx, fd.ty())),
                         visibility: RawVisibility::from_ast(db, ast.with_value(fd.visibility())),
                     },
                 );
@@ -358,7 +359,7 @@ fn lower_field(
 ) -> FieldData {
     FieldData {
         name: field.name.clone(),
-        type_ref: item_tree[field.type_ref].clone(),
+        type_ref: field.type_ref.clone(),
         visibility: item_tree[override_visibility.unwrap_or(field.visibility)].clone(),
     }
 }

crates/hir_def/src/attr.rs

@@ -18,6 +18,7 @@ use tt::Subtree;
 
 use crate::{
     db::DefDatabase,
+    intern::Interned,
     item_tree::{ItemTreeId, ItemTreeNode},
     nameres::ModuleSource,
     path::{ModPath, PathKind},
@@ -98,7 +99,7 @@ impl RawAttrs {
                 Either::Right(comment) => comment.doc_comment().map(|doc| Attr {
                     index: i as u32,
                     input: Some(AttrInput::Literal(SmolStr::new(doc))),
-                    path: ModPath::from(hir_expand::name!(doc)),
+                    path: Interned::new(ModPath::from(hir_expand::name!(doc))),
                 }),
             })
             .collect::<Arc<_>>();
@@ -510,7 +511,7 @@ impl AttrSourceMap {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Attr {
     index: u32,
-    pub(crate) path: ModPath,
+    pub(crate) path: Interned<ModPath>,
     pub(crate) input: Option<AttrInput>,
 }
 
@@ -524,7 +525,7 @@ pub enum AttrInput {
 
 impl Attr {
     fn from_src(ast: ast::Attr, hygiene: &Hygiene, index: u32) -> Option<Attr> {
-        let path = ModPath::from_src(ast.path()?, hygiene)?;
+        let path = Interned::new(ModPath::from_src(ast.path()?, hygiene)?);
         let input = if let Some(ast::Expr::Literal(lit)) = ast.expr() {
             let value = match lit.kind() {
                 ast::LiteralKind::String(string) => string.value()?.into(),

crates/hir_def/src/data.rs

@@ -9,6 +9,7 @@ use crate::{
     attr::Attrs,
     body::Expander,
     db::DefDatabase,
+    intern::Interned,
     item_tree::{AssocItem, FunctionQualifier, ItemTreeId, ModItem, Param},
     type_ref::{TraitRef, TypeBound, TypeRef},
     visibility::RawVisibility,
@@ -19,8 +20,8 @@ use crate::{
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct FunctionData {
     pub name: Name,
-    pub params: Vec<TypeRef>,
-    pub ret_type: TypeRef,
+    pub params: Vec<Interned<TypeRef>>,
+    pub ret_type: Interned<TypeRef>,
     pub attrs: Attrs,
     /// True if the first param is `self`. This is relevant to decide whether this
     /// can be called as a method.
@@ -57,11 +58,11 @@ impl FunctionData {
             params: enabled_params
                 .clone()
                 .filter_map(|id| match &item_tree[id] {
-                    Param::Normal(ty) => Some(item_tree[*ty].clone()),
+                    Param::Normal(ty) => Some(ty.clone()),
                     Param::Varargs => None,
                 })
                 .collect(),
-            ret_type: item_tree[func.ret_type].clone(),
+            ret_type: func.ret_type.clone(),
             attrs: item_tree.attrs(db, krate, ModItem::from(loc.id.value).into()),
             has_self_param: func.has_self_param,
             has_body: func.has_body,
@@ -76,7 +77,7 @@ impl FunctionData {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct TypeAliasData {
     pub name: Name,
-    pub type_ref: Option<TypeRef>,
+    pub type_ref: Option<Interned<TypeRef>>,
     pub visibility: RawVisibility,
     pub is_extern: bool,
     /// Bounds restricting the type alias itself (eg. `type Ty: Bound;` in a trait or impl).
@@ -94,7 +95,7 @@ impl TypeAliasData {
 
         Arc::new(TypeAliasData {
             name: typ.name.clone(),
-            type_ref: typ.type_ref.map(|id| item_tree[id].clone()),
+            type_ref: typ.type_ref.clone(),
             visibility: item_tree[typ.visibility].clone(),
             is_extern: typ.is_extern,
             bounds: typ.bounds.to_vec(),
@@ -156,8 +157,8 @@ impl TraitData {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ImplData {
-    pub target_trait: Option<TraitRef>,
-    pub self_ty: TypeRef,
+    pub target_trait: Option<Interned<TraitRef>>,
+    pub self_ty: Interned<TypeRef>,
     pub items: Vec<AssocItemId>,
     pub is_negative: bool,
 }
@@ -169,8 +170,8 @@ impl ImplData {
 
         let item_tree = impl_loc.id.item_tree(db);
         let impl_def = &item_tree[impl_loc.id.value];
-        let target_trait = impl_def.target_trait.map(|id| item_tree[id].clone());
-        let self_ty = item_tree[impl_def.self_ty].clone();
+        let target_trait = impl_def.target_trait.clone();
+        let self_ty = impl_def.self_ty.clone();
         let is_negative = impl_def.is_negative;
         let module_id = impl_loc.container;
         let container = AssocContainerId::ImplId(id);
@@ -195,7 +196,7 @@ impl ImplData {
 pub struct ConstData {
     /// const _: () = ();
     pub name: Option<Name>,
-    pub type_ref: TypeRef,
+    pub type_ref: Interned<TypeRef>,
     pub visibility: RawVisibility,
 }
 
@@ -207,7 +208,7 @@ impl ConstData {
 
         Arc::new(ConstData {
             name: konst.name.clone(),
-            type_ref: item_tree[konst.type_ref].clone(),
+            type_ref: konst.type_ref.clone(),
             visibility: item_tree[konst.visibility].clone(),
         })
     }
@@ -216,7 +217,7 @@ impl ConstData {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct StaticData {
     pub name: Option<Name>,
-    pub type_ref: TypeRef,
+    pub type_ref: Interned<TypeRef>,
     pub visibility: RawVisibility,
     pub mutable: bool,
     pub is_extern: bool,
@@ -230,7 +231,7 @@ impl StaticData {
 
         Arc::new(StaticData {
             name: Some(statik.name.clone()),
-            type_ref: item_tree[statik.type_ref].clone(),
+            type_ref: statik.type_ref.clone(),
             visibility: item_tree[statik.visibility].clone(),
             mutable: statik.mutable,
             is_extern: statik.is_extern,