perf(semantic): use Atom<'a> for References (#3972)

Relates to [this
issue](oxc-project/backlog#31) on the backlog.

crates/oxc_linter/src/rules/eslint/no_global_assign.rs

@@ -66,7 +66,9 @@ impl Rule for NoGlobalAssign {
                 let reference = symbol_table.get_reference(reference_id);
                 if reference.is_write() {
                     let name = reference.name();
-                    if !self.excludes.contains(name) && ctx.env_contains_var(name) {
+                    // Vec::contains isn't working here, but this has the same
+                    // effect and time complexity.
+                    if !self.excludes.iter().any(|e| e == name) && ctx.env_contains_var(name) {
                         ctx.diagnostic(no_global_assign_diagnostic(name, reference.span()));
                     }
                 }

crates/oxc_minifier/src/mangler/mod.rs

@@ -7,11 +7,11 @@ use oxc_span::CompactStr;
 type Slot = usize;
 
 #[derive(Debug)]
-pub struct Mangler {
-    symbol_table: SymbolTable,
+pub struct Mangler<'a> {
+    symbol_table: SymbolTable<'a>,
 }
 
-impl Mangler {
+impl<'a> Mangler<'a> {
     pub fn get_symbol_name(&self, symbol_id: SymbolId) -> &str {
         self.symbol_table.get_name(symbol_id)
     }

crates/oxc_semantic/src/builder.rs

@@ -9,7 +9,7 @@ use oxc_cfg::{
     IterationInstructionKind, ReturnInstructionKind,
 };
 use oxc_diagnostics::OxcDiagnostic;
-use oxc_span::{CompactStr, SourceType, Span};
+use oxc_span::{Atom, CompactStr, SourceType, Span};
 use oxc_syntax::{module_record::ModuleRecord, operator::AssignmentOperator};
 
 use crate::{
@@ -63,8 +63,8 @@ pub struct SemanticBuilder<'a> {
 
     // builders
     pub nodes: AstNodes<'a>,
-    pub scope: ScopeTree,
-    pub symbols: SymbolTable,
+    pub scope: ScopeTree<'a>,
+    pub symbols: SymbolTable<'a>,
 
     pub(crate) module_record: Arc<ModuleRecord>,
 
@@ -315,7 +315,7 @@ impl<'a> SemanticBuilder<'a> {
 
     pub fn declare_reference(
         &mut self,
-        reference: Reference,
+        reference: Reference<'a>,
         add_unresolved_reference: bool,
     ) -> ReferenceId {
         let reference_name = reference.name().clone();
@@ -327,7 +327,7 @@ impl<'a> SemanticBuilder<'a> {
                 reference_id,
             );
         } else {
-            self.resolve_reference_ids(reference_name.clone(), vec![reference_id]);
+            self.resolve_reference_ids(reference_name, vec![reference_id]);
         }
         reference_id
     }
@@ -361,7 +361,7 @@ impl<'a> SemanticBuilder<'a> {
         }
     }
 
-    fn resolve_reference_ids(&mut self, name: CompactStr, reference_ids: Vec<ReferenceId>) {
+    fn resolve_reference_ids(&mut self, name: Atom<'a>, reference_ids: Vec<ReferenceId>) {
         let parent_scope_id =
             self.scope.get_parent_id(self.current_scope_id).unwrap_or(self.current_scope_id);
 
@@ -1884,9 +1884,9 @@ impl<'a> SemanticBuilder<'a> {
         }
     }
 
-    fn reference_identifier(&mut self, ident: &IdentifierReference) {
+    fn reference_identifier(&mut self, ident: &IdentifierReference<'a>) {
         let flag = self.resolve_reference_usages();
-        let name = ident.name.to_compact_str();
+        let name = ident.name.clone();
         let reference = Reference::new(ident.span, name, self.current_node_id, flag);
         // `function foo({bar: identifier_reference}) {}`
         //                     ^^^^^^^^^^^^^^^^^^^^ Parameter initializer must be resolved immediately
@@ -1905,7 +1905,7 @@ impl<'a> SemanticBuilder<'a> {
         }
     }
 
-    fn reference_jsx_identifier(&mut self, ident: &JSXIdentifier) {
+    fn reference_jsx_identifier(&mut self, ident: &JSXIdentifier<'a>) {
         match self.nodes.parent_kind(self.current_node_id) {
             Some(AstKind::JSXElementName(_)) => {
                 if !ident.name.chars().next().is_some_and(char::is_uppercase) {
@@ -1917,7 +1917,7 @@ impl<'a> SemanticBuilder<'a> {
         }
         let reference = Reference::new(
             ident.span,
-            ident.name.to_compact_str(),
+            ident.name.clone(),
             self.current_node_id,
             ReferenceFlag::read(),
         );

crates/oxc_semantic/src/lib.rs

@@ -42,9 +42,9 @@ pub struct Semantic<'a> {
 
     nodes: AstNodes<'a>,
 
-    scopes: ScopeTree,
+    scopes: ScopeTree<'a>,
 
-    symbols: SymbolTable,
+    symbols: SymbolTable<'a>,
 
     classes: ClassTable,
 
@@ -60,7 +60,7 @@ pub struct Semantic<'a> {
 }
 
 impl<'a> Semantic<'a> {
-    pub fn into_symbol_table_and_scope_tree(self) -> (SymbolTable, ScopeTree) {
+    pub fn into_symbol_table_and_scope_tree(self) -> (SymbolTable<'a>, ScopeTree<'a>) {
         (self.symbols, self.scopes)
     }
 
@@ -84,7 +84,7 @@ impl<'a> Semantic<'a> {
         &self.classes
     }
 
-    pub fn scopes_mut(&mut self) -> &mut ScopeTree {
+    pub fn scopes_mut(&mut self) -> &mut ScopeTree<'a> {
         &mut self.scopes
     }
 

crates/oxc_semantic/src/reference.rs

@@ -1,7 +1,7 @@
 // Silence erroneous warnings from Rust Analyser for `#[derive(Tsify)]`
 #![allow(non_snake_case)]
 
-use oxc_span::{CompactStr, Span};
+use oxc_span::{Atom, Span};
 pub use oxc_syntax::reference::{ReferenceFlag, ReferenceId};
 #[cfg(feature = "serialize")]
 use serde::Serialize;
@@ -13,25 +13,25 @@ use crate::{symbol::SymbolId, AstNodeId};
 #[derive(Debug, Clone)]
 #[cfg_attr(feature = "serialize", derive(Serialize, Tsify))]
 #[cfg_attr(feature = "serialize", serde(rename_all = "camelCase"))]
-pub struct Reference {
+pub struct Reference<'a> {
     span: Span,
     /// The name of the identifier that was referred to
-    name: CompactStr,
+    name: Atom<'a>,
     node_id: AstNodeId,
     symbol_id: Option<SymbolId>,
     /// Describes how this referenced is used by other AST nodes. References can
     /// be reads, writes, or both.
     flag: ReferenceFlag,
 }
 
-impl Reference {
-    pub fn new(span: Span, name: CompactStr, node_id: AstNodeId, flag: ReferenceFlag) -> Self {
+impl<'a> Reference<'a> {
+    pub fn new(span: Span, name: Atom<'a>, node_id: AstNodeId, flag: ReferenceFlag) -> Self {
         Self { span, name, node_id, symbol_id: None, flag }
     }
 
     pub fn new_with_symbol_id(
         span: Span,
-        name: CompactStr,
+        name: Atom<'a>,
         node_id: AstNodeId,
         symbol_id: SymbolId,
         flag: ReferenceFlag,
@@ -43,7 +43,7 @@ impl Reference {
         self.span
     }
 
-    pub fn name(&self) -> &CompactStr {
+    pub fn name(&self) -> &Atom<'a> {
         &self.name
     }
 

crates/oxc_semantic/src/scope.rs

@@ -2,7 +2,7 @@ use std::hash::BuildHasherDefault;
 
 use indexmap::IndexMap;
 use oxc_index::IndexVec;
-use oxc_span::CompactStr;
+use oxc_span::{Atom, CompactStr};
 pub use oxc_syntax::scope::{ScopeFlags, ScopeId};
 use rustc_hash::{FxHashMap, FxHasher};
 
@@ -11,13 +11,13 @@ use crate::{reference::ReferenceId, symbol::SymbolId, AstNodeId};
 type FxIndexMap<K, V> = IndexMap<K, V, BuildHasherDefault<FxHasher>>;
 
 type Bindings = FxIndexMap<CompactStr, SymbolId>;
-type UnresolvedReferences = FxHashMap<CompactStr, Vec<ReferenceId>>;
+type UnresolvedReferences<'a> = FxHashMap<Atom<'a>, Vec<ReferenceId>>;
 
 /// Scope Tree
 ///
 /// `SoA` (Struct of Arrays) for memory efficiency.
 #[derive(Debug, Default)]
-pub struct ScopeTree {
+pub struct ScopeTree<'a> {
     /// Maps a scope to the parent scope it belongs in
     parent_ids: IndexVec<ScopeId, Option<ScopeId>>,
 
@@ -27,10 +27,10 @@ pub struct ScopeTree {
     node_ids: FxHashMap<ScopeId, AstNodeId>,
     flags: IndexVec<ScopeId, ScopeFlags>,
     bindings: IndexVec<ScopeId, Bindings>,
-    unresolved_references: IndexVec<ScopeId, UnresolvedReferences>,
+    unresolved_references: IndexVec<ScopeId, UnresolvedReferences<'a>>,
 }
 
-impl ScopeTree {
+impl<'a> ScopeTree<'a> {
     pub fn len(&self) -> usize {
         self.parent_ids.len()
     }
@@ -141,7 +141,7 @@ impl ScopeTree {
         self.get_binding(self.root_scope_id(), name)
     }
 
-    pub fn add_root_unresolved_reference(&mut self, name: CompactStr, reference_id: ReferenceId) {
+    pub fn add_root_unresolved_reference(&mut self, name: Atom<'a>, reference_id: ReferenceId) {
         self.add_unresolved_reference(self.root_scope_id(), name, reference_id);
     }
 
@@ -208,7 +208,7 @@ impl ScopeTree {
     pub(crate) fn add_unresolved_reference(
         &mut self,
         scope_id: ScopeId,
-        name: CompactStr,
+        name: Atom<'a>,
         reference_id: ReferenceId,
     ) {
         self.unresolved_references[scope_id].entry(name).or_default().push(reference_id);
@@ -217,7 +217,7 @@ impl ScopeTree {
     pub(crate) fn extend_unresolved_reference(
         &mut self,
         scope_id: ScopeId,
-        name: CompactStr,
+        name: Atom<'a>,
         reference_ids: Vec<ReferenceId>,
     ) {
         self.unresolved_references[scope_id].entry(name).or_default().extend(reference_ids);
@@ -226,7 +226,7 @@ impl ScopeTree {
     pub(crate) fn unresolved_references_mut(
         &mut self,
         scope_id: ScopeId,
-    ) -> &mut UnresolvedReferences {
+    ) -> &mut UnresolvedReferences<'a> {
         &mut self.unresolved_references[scope_id]
     }
 }

crates/oxc_semantic/src/symbol.rs

@@ -28,19 +28,19 @@ export type IndexVec<I, T> = Array<T>;
 /// `SoA` (Struct of Arrays) for memory efficiency.
 #[derive(Debug, Default)]
 #[cfg_attr(feature = "serialize", derive(Serialize, Tsify), serde(rename_all = "camelCase"))]
-pub struct SymbolTable {
+pub struct SymbolTable<'a> {
     pub spans: IndexVec<SymbolId, Span>,
     pub names: IndexVec<SymbolId, CompactStr>,
     pub flags: IndexVec<SymbolId, SymbolFlags>,
     pub scope_ids: IndexVec<SymbolId, ScopeId>,
     /// Pointer to the AST Node where this symbol is declared
     pub declarations: IndexVec<SymbolId, AstNodeId>,
     pub resolved_references: IndexVec<SymbolId, Vec<ReferenceId>>,
-    pub references: IndexVec<ReferenceId, Reference>,
+    pub references: IndexVec<ReferenceId, Reference<'a>>,
     pub redeclare_variables: IndexVec<SymbolId, Vec<Span>>,
 }
 
-impl SymbolTable {
+impl<'a> SymbolTable<'a> {
     pub fn len(&self) -> usize {
         self.spans.len()
     }
@@ -136,15 +136,15 @@ impl SymbolTable {
         self.redeclare_variables[symbol_id].push(span);
     }
 
-    pub fn create_reference(&mut self, reference: Reference) -> ReferenceId {
+    pub fn create_reference(&mut self, reference: Reference<'a>) -> ReferenceId {
         self.references.push(reference)
     }
 
-    pub fn get_reference(&self, reference_id: ReferenceId) -> &Reference {
+    pub fn get_reference(&self, reference_id: ReferenceId) -> &Reference<'a> {
         &self.references[reference_id]
     }
 
-    pub fn get_reference_mut(&mut self, reference_id: ReferenceId) -> &mut Reference {
+    pub fn get_reference_mut(&mut self, reference_id: ReferenceId) -> &mut Reference<'a> {
         &mut self.references[reference_id]
     }
 

crates/oxc_semantic/tests/integration/util/symbol_tester.rs

@@ -110,18 +110,24 @@ impl<'a> SymbolTester<'a> {
         self
     }
 
+    // Note: can't use `Reference::is_read()` due to error warning about overly
+    // generic FnMut impl.
+
     #[must_use]
     pub fn has_number_of_reads(self, ref_count: usize) -> Self {
-        self.has_number_of_references_where(ref_count, Reference::is_read)
+        #[allow(clippy::redundant_closure_for_method_calls)]
+        self.has_number_of_references_where(ref_count, |r| r.is_read())
     }
 
     #[must_use]
     pub fn has_number_of_writes(self, ref_count: usize) -> Self {
-        self.has_number_of_references_where(ref_count, Reference::is_write)
+        #[allow(clippy::redundant_closure_for_method_calls)]
+        self.has_number_of_references_where(ref_count, |r| r.is_write())
     }
 
     #[must_use]
     pub fn has_number_of_references(self, ref_count: usize) -> Self {
+        #[allow(clippy::redundant_closure_for_method_calls)]
         self.has_number_of_references_where(ref_count, |_| true)
     }
 

crates/oxc_transformer/src/react/jsx.rs

@@ -986,8 +986,7 @@ fn get_read_identifier_reference<'a>(
     name: Atom<'a>,
     ctx: &mut TraverseCtx<'a>,
 ) -> IdentifierReference<'a> {
-    let reference_id =
-        ctx.create_reference_in_current_scope(name.to_compact_str(), ReferenceFlag::Read);
+    let reference_id = ctx.create_reference_in_current_scope(name.clone(), ReferenceFlag::Read);
     IdentifierReference::new_read(span, name, Some(reference_id))
 }
 

crates/oxc_transformer/src/typescript/annotations.rs

@@ -540,11 +540,8 @@ struct Assignment<'a> {
 impl<'a> Assignment<'a> {
     // Creates `this.name = name`
     fn create_this_property_assignment(&self, ctx: &mut TraverseCtx<'a>) -> Statement<'a> {
-        let reference_id = ctx.create_bound_reference(
-            self.name.to_compact_str(),
-            self.symbol_id,
-            ReferenceFlag::Read,
-        );
+        let reference_id =
+            ctx.create_bound_reference(self.name.clone(), self.symbol_id, ReferenceFlag::Read);
         let id = IdentifierReference::new_read(self.span, self.name.clone(), Some(reference_id));
 
         ctx.ast.expression_statement(