perf(linter): reduce mallocs (#654)

Reduces mallocs via `clones()` (particularly of `Atom`s), and vec
allocations.

Affects the following rules:
- [x] eslint/no-dupe-keys
- [x] eslint/no-global-assign
- [x] eslint/no-loss-of-precision _(only partially optimized, needs more
work later)_
~- [ ] typescript-eslint/ajacent-overload-signatures~ (_will be
addressed in following pr_)

crates/oxc_ast/src/ast/js.rs

@@ -347,6 +347,7 @@ pub enum PropertyKey<'a> {
 }
 
 impl<'a> PropertyKey<'a> {
+    // FIXME: this would ideally return Option<&'a Atom> or a Cow
     pub fn static_name(&self) -> Option<Atom> {
         match self {
             Self::Identifier(ident) => Some(ident.name.clone()),

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

@@ -1,5 +1,5 @@
 use oxc_ast::{
-    ast::{ObjectPropertyKind, PropertyKind},
+    ast::{ObjectPropertyKind, PropertyKey, PropertyKind, Expression},
     AstKind,
 };
 use oxc_diagnostics::{
@@ -9,6 +9,7 @@ use oxc_diagnostics::{
 use oxc_macros::declare_oxc_lint;
 use oxc_span::{GetSpan, Span};
 use rustc_hash::FxHashMap;
+use lazy_static::lazy_static;
 
 use crate::{ast_util::calculate_hash, context::LintContext, rule::Rule, AstNode};
 
@@ -42,15 +43,12 @@ declare_oxc_lint!(
 
 impl Rule for NoDupeKeys {
     fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
-        if let AstKind::ObjectExpression(obj_expr) = node.kind() {
+        let AstKind::ObjectExpression(obj_expr) = node.kind() else { return };
         let mut map = FxHashMap::default();
         for prop in &obj_expr.properties {
-                if let ObjectPropertyKind::ObjectProperty(prop) = prop {
+            let ObjectPropertyKind::ObjectProperty(prop) = prop else { continue };
-                    if let Some(key_name) = prop.key.static_name().as_ref() {
+            let Some(hash) = calculate_property_kind_hash(&prop.key) else { continue };
-                        let hash = calculate_hash(key_name);
+            if let Some((prev_kind, prev_span)) = map.insert(hash, (prop.kind, prop.key.span())) {
-                        if let Some((prev_kind, prev_span)) =
-                            map.insert(hash, (prop.kind, prop.key.span()))
-                        {
                 if prev_kind == PropertyKind::Init
                     || prop.kind == PropertyKind::Init
                     || prev_kind == prop.kind
@@ -60,8 +58,32 @@ impl Rule for NoDupeKeys {
             }
         }
     }
+}
+
+// todo: should this be located within oxc_ast?
+fn calculate_property_kind_hash(key: &PropertyKey) -> Option<u64> {
+    lazy_static! {
+        static ref NULL_HASH: u64 = calculate_hash(&"null");
     }
+
+    match key {
+        PropertyKey::Identifier(ident) => Some(calculate_hash(&ident)),
+        PropertyKey::PrivateIdentifier(_) => None,
+        PropertyKey::Expression(expr) => match expr {
+            Expression::StringLiteral(lit) => Some(calculate_hash(&lit.value)),
+            // note: hashes won't work as expected if these aren't strings. Save
+            // NumberLiteral I don't think this should be too much of a problem
+            // b/c most people don't use `null`, regexes, etc. as object
+            // property keys when writing real code.
+            Expression::RegExpLiteral(lit) => Some(calculate_hash(&lit.regex.to_string())),
+            Expression::NumberLiteral(lit) => Some(calculate_hash(&lit.value.to_string())),
+            Expression::BigintLiteral(lit) => Some(calculate_hash(&lit.value.to_string())),
+            Expression::NullLiteral(_) => Some(*NULL_HASH),
+            Expression::TemplateLiteral(lit) => {
+                lit.expressions.is_empty().then(|| lit.quasi()).flatten().map(calculate_hash)
             }
+            _ => None,
+        },
     }
 }
 

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

@@ -53,25 +53,15 @@ impl Rule for NoGlobalAssign {
     }
 
     fn run_once(&self, ctx: &LintContext) {
-        let symbol_table = ctx.semantic().symbols();
+        let symbol_table = ctx.symbols();
         for reference_id_list in ctx.scopes().root_unresolved_references().values() {
             for &reference_id in reference_id_list {
                 let reference = symbol_table.get_reference(reference_id);
-                if symbol_table.is_global_reference(reference_id) && reference.is_write() {
+                if reference.is_write() && symbol_table.is_global_reference(reference_id) {
-                    let name = reference.name().clone();
+                    let name = reference.name();
-                    let mut is_global_assign = false;
-                    if let Some(&value) = BUILTINS.get(&name) {
-                        if !value {
-                            is_global_assign = true;
-                        }
-                    }
 
-                    if self.excludes.contains(&name.clone()) {
+                    if !self.excludes.contains(name) && BUILTINS.contains_key(name) {
-                        is_global_assign = false;
+                        ctx.diagnostic(NoGlobalAssignDiagnostic(name.clone(), reference.span()));
-                    }
-
-                    if is_global_assign {
-                        ctx.diagnostic(NoGlobalAssignDiagnostic(name, reference.span()));
                     }
                 }
             }

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

@@ -59,8 +59,7 @@ impl<'a> PartialEq for NormalizedNum<'a> {
         if self.coefficient == "0" {
             true
         } else {
-            self.magnitude == other.magnitude
+            self.magnitude == other.magnitude && self.coefficient == other.coefficient
-                && self.coefficient == other.coefficient
         }
     }
 }
@@ -74,11 +73,6 @@ impl NoLossOfPrecision {
         }
     }
 
-    fn base_ten(node: &'_ NumberLiteral) -> bool {
-        let prefixes = ["0x", "0X", "0b", "0B", "0o", "0O"];
-        !prefixes.iter().any(|prefix| node.raw.starts_with(prefix))
-    }
-
     fn not_base_ten_loses_precision(node: &'_ NumberLiteral) -> bool {
         let raw = Self::get_raw(node).to_uppercase();
         #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
@@ -140,10 +134,7 @@ impl NoLossOfPrecision {
     fn normalize_int(num: Cow<'_, str>) -> NormalizedNum<'_> {
         // specially deal with 0
         if num == "0" {
-            return NormalizedNum {
+            return NormalizedNum { magnitude: 0, coefficient: Cow::Borrowed("0") };
-                magnitude: 0,
-                coefficient: Cow::Borrowed("0"),
-            };
         }
 
         #[allow(clippy::cast_possible_wrap)]
@@ -163,10 +154,7 @@ impl NoLossOfPrecision {
                 // unwrap here will never panic, we guarantee the input contains a `.`
                 #[allow(clippy::cast_possible_wrap)]
                 let magnitude = (trimmed_float.find('.').unwrap() - 1) as isize;
-                NormalizedNum {
+                NormalizedNum { coefficient: Cow::Owned(trimmed_float.replace('.', "")), magnitude }
-                    coefficient: Cow::Owned(trimmed_float.replace('.', "")),
-                    magnitude,
-                }
             },
             |stripped| {
                 let decimal_digits = stripped.len();
@@ -205,7 +193,7 @@ impl NoLossOfPrecision {
     }
 
     pub fn lose_precision(node: &'_ NumberLiteral) -> bool {
-        if Self::base_ten(node) {
+        if node.base.is_base_10() {
             Self::base_ten_loses_precision(node)
         } else {
             Self::not_base_ten_loses_precision(node)

crates/oxc_syntax/src/lib.rs

@@ -17,3 +17,9 @@ pub enum NumberBase {
     Octal,
     Hex,
 }
+
+impl NumberBase {
+    pub fn is_base_10(&self) -> bool {
+        matches!(self, Self::Float | Self::Decimal)
+    }
+}