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pref(es/minifier): less clone atom #10967

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57991c7
pref(es/minifier): less clone atom
bvanjoi Jul 31, 2025
a8e9e16
perf(es/minifier): use intern
bvanjoi Jul 31, 2025
9cc3b15
use indexmap
bvanjoi Jul 31, 2025
82e2208
dont use tls
bvanjoi Aug 1, 2025
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1 change: 1 addition & 0 deletions Cargo.lock
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6 changes: 4 additions & 2 deletions crates/swc_bundler/src/id.rs
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Expand Up @@ -81,15 +81,17 @@ impl Id {
}

impl IdentLike for Id {
type Id = (Atom, SyntaxContext);

fn from_ident(i: &Ident) -> Self {
i.into()
}

fn to_id(&self) -> (Atom, SyntaxContext) {
fn to_id(&self) -> Self::Id {
(self.0.clone(), self.1)
}

fn into_id(self) -> (Atom, SyntaxContext) {
fn into_id(self) -> Self::Id {
(self.0, self.1)
}
}
Expand Down
2 changes: 1 addition & 1 deletion crates/swc_bundler/src/util.rs
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Expand Up @@ -50,7 +50,7 @@ pub(crate) trait ExprExt: Into<Expr> {
#[track_caller]
fn assign_to<T>(self, lhs: T) -> VarDeclarator
where
T: IdentLike,
T: IdentLike<Id = Id>,
{
let init = self.into();
let lhs = lhs.into_id();
Expand Down
1 change: 1 addition & 0 deletions crates/swc_ecma_ast/Cargo.toml
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Expand Up @@ -39,6 +39,7 @@ shrink-to-fit = [
arbitrary = { workspace = true, features = ["derive"], optional = true }
bitflags = { workspace = true }
bytecheck = { workspace = true, optional = true }
indexmap = { workspace = true }
is-macro = { workspace = true }
num-bigint = { workspace = true, features = ["serde"] }
once_cell = { workspace = true }
Expand Down
45 changes: 45 additions & 0 deletions crates/swc_ecma_ast/src/ident.rs
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@@ -1,9 +1,11 @@
use std::{
borrow::Cow,
fmt::Display,
hash::{Hash, Hasher},
ops::{Deref, DerefMut},
};

use indexmap::map::RawEntryApiV1;
use once_cell::sync::Lazy;
use phf::phf_set;
use rustc_hash::FxHashSet;
Expand Down Expand Up @@ -527,6 +529,49 @@ pub unsafe fn unsafe_id_from_ident(id: &Ident) -> UnsafeId {
/// See [Ident] for documentation.
pub type Id = (Atom, SyntaxContext);

#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
pub struct IdIdx(u32);

#[derive(Default, Debug)]
pub struct Ids {
map: indexmap::IndexMap<Id, (), rustc_hash::FxBuildHasher>,
}

impl Ids {
#[inline(always)]
pub fn intern_ident(&mut self, ident: &Ident) -> IdIdx {
self.intern(&ident.sym, ident.ctxt)
}

pub fn intern(&mut self, atom: &Atom, ctxt: SyntaxContext) -> IdIdx {
let mut hasher = rustc_hash::FxHasher::default();
atom.hash(&mut hasher);
ctxt.hash(&mut hasher);
let hash = hasher.finish();

use indexmap::map::raw_entry_v1::RawEntryMut::*;
let idx = match self
.map
.raw_entry_mut_v1()
.from_hash(hash, |id| id.1 == ctxt && id.0.eq(atom))
{
Occupied(occ) => occ.index(),
Vacant(vac) => {
let id = (atom.clone(), ctxt);
let idx = vac.index();
vac.insert_hashed_nocheck(hash, id, ());
idx
}
};
IdIdx(idx as u32)
}

#[inline(always)]
pub fn get(&self, idx: IdIdx) -> &Id {
self.map.get_index(idx.0 as usize).unwrap().0
}
}

impl Take for Ident {
fn dummy() -> Self {
Ident::new_no_ctxt(atom!(""), DUMMY_SP)
Expand Down
4 changes: 2 additions & 2 deletions crates/swc_ecma_ast/src/lib.rs
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Expand Up @@ -23,8 +23,8 @@ pub use self::{
expr::*,
function::{Function, Param, ParamOrTsParamProp},
ident::{
unsafe_id, unsafe_id_from_ident, BindingIdent, EsReserved, Id, Ident, IdentName,
PrivateName, UnsafeId,
unsafe_id, unsafe_id_from_ident, BindingIdent, EsReserved, Id, IdIdx, Ident, IdentName,
Ids, PrivateName, UnsafeId,
},
jsx::{
JSXAttr, JSXAttrName, JSXAttrOrSpread, JSXAttrValue, JSXClosingElement, JSXClosingFragment,
Expand Down
28 changes: 18 additions & 10 deletions crates/swc_ecma_minifier/src/compress/hoist_decls.rs
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Expand Up @@ -3,7 +3,7 @@ use rustc_hash::FxHashSet;
use swc_common::{pass::Repeated, util::take::Take, DUMMY_SP};
use swc_ecma_ast::*;
use swc_ecma_usage_analyzer::analyzer::UsageAnalyzer;
use swc_ecma_utils::{find_pat_ids, StmtLike};
use swc_ecma_utils::{find_pat_ids, find_pat_ids_with_idx, StmtLike};
use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith, VisitWith};

use super::util::drop_invalid_stmts;
Expand All @@ -18,18 +18,24 @@ pub(super) struct DeclHoisterConfig {
pub _top_level: bool,
}

pub(super) fn decl_hoister(config: DeclHoisterConfig, data: &ProgramData) -> Hoister {
pub(super) fn decl_hoister<'a>(
config: DeclHoisterConfig,
data: &'a ProgramData,
id_map: &'a mut Ids,
) -> Hoister<'a> {
Hoister {
config,
changed: false,
data,
id_map,
}
}

pub(super) struct Hoister<'a> {
config: DeclHoisterConfig,
changed: bool,
data: &'a ProgramData,
id_map: &'a mut Ids,
}

impl Repeated for Hoister<'_> {
Expand All @@ -42,11 +48,11 @@ impl Repeated for Hoister<'_> {
}
}

impl Hoister<'_> {
impl<'a> Hoister<'a> {
fn handle_stmt_likes<T>(&mut self, stmts: &mut Vec<T>)
where
T: StmtLike + IsModuleItem + ModuleItemExt,
Vec<T>: for<'aa> VisitMutWith<Hoister<'aa>> + VisitWith<UsageAnalyzer<ProgramData>>,
Vec<T>: for<'aa> VisitMutWith<Hoister<'aa>> + VisitWith<UsageAnalyzer<'a, ProgramData>>,
{
stmts.visit_mut_children_with(self);
let len = stmts.len();
Expand All @@ -55,7 +61,7 @@ impl Hoister<'_> {
Some(stmt) => match stmt {
Stmt::Decl(Decl::Fn(..)) if self.config.hoist_fns => 1,
Stmt::Decl(Decl::Var(var)) if self.config.hoist_vars => {
let ids: Vec<Id> = find_pat_ids(&var.decls);
let ids: Vec<IdIdx> = find_pat_ids_with_idx(&var.decls, self.id_map);

if ids.iter().any(|id| {
self.data
Expand Down Expand Up @@ -95,7 +101,7 @@ impl Hoister<'_> {
let mut var_decls = Vec::new();
let mut fn_decls = Vec::with_capacity(stmts.len());
let mut new_stmts = Vec::with_capacity(stmts.len());
let mut done = FxHashSet::default();
let mut done: FxHashSet<IdIdx> = FxHashSet::default();

let mut found_non_var_decl = false;
for stmt in stmts.take() {
Expand All @@ -122,14 +128,15 @@ impl Hoister<'_> {
let ids: Vec<Ident> = find_pat_ids(&decl.name);

for id in ids {
if done.insert(id.to_id()) {
let idx = self.id_map.intern_ident(&id);
if done.insert(idx) {
// If the enclosing function declares parameter with same
// name, we can drop a varaible.
if decl.init.is_none()
&& self
.data
.vars
.get(&id.to_id())
.get(&idx)
.map(|v| {
v.flags.contains(
VarUsageInfoFlags::DECLARED_AS_FN_PARAM,
Expand Down Expand Up @@ -209,13 +216,14 @@ impl Hoister<'_> {

let preserve = match &decl.name {
Pat::Ident(name) => {
let id = self.id_map.intern_ident(&name);
// If the enclosing function declares parameter with same
// name, we can drop a varaible. (If it's side-effect free).
if decl.init.is_none()
&& self
.data
.vars
.get(&name.to_id())
.get(&id)
.map(|v| {
v.flags.contains(
VarUsageInfoFlags::DECLARED_AS_FN_PARAM,
Expand All @@ -226,7 +234,7 @@ impl Hoister<'_> {
return false;
}

done.insert(name.to_id())
done.insert(id)
}
_ => true,
};
Expand Down
10 changes: 8 additions & 2 deletions crates/swc_ecma_minifier/src/compress/mod.rs
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Expand Up @@ -36,6 +36,7 @@ pub(crate) fn compressor<'a, M>(
options: &'a CompressOptions,
mangle_options: Option<&'a MangleOptions>,
mode: &'a M,
id_map: &'a mut Ids,
) -> impl 'a + Pass
where
M: Mode,
Expand All @@ -47,6 +48,7 @@ where
changed: false,
pass: 1,
mode,
id_map,
}
}

Expand All @@ -58,6 +60,7 @@ struct Compressor<'a> {
pass: usize,

mode: &'a dyn Mode,
id_map: &'a mut Ids,
}

impl CompilerPass for Compressor<'_> {
Expand All @@ -80,7 +83,7 @@ impl Compressor<'_> {
);

if self.options.hoist_vars || self.options.hoist_fns {
let data = analyze(&*n, Some(self.marks), false);
let data = analyze(&*n, Some(self.marks), false, self.id_map);

let mut v = decl_hoister(
DeclHoisterConfig {
Expand All @@ -89,6 +92,7 @@ impl Compressor<'_> {
_top_level: self.options.top_level(),
},
&data,
self.id_map,
);
n.visit_mut_with(&mut v);
self.changed |= v.changed();
Expand Down Expand Up @@ -145,6 +149,7 @@ impl Compressor<'_> {

let mut visitor = pure_optimizer(
self.options,
self.id_map,
self.marks,
PureOptimizerConfig {
enable_join_vars: self.pass > 1,
Expand Down Expand Up @@ -173,7 +178,7 @@ impl Compressor<'_> {
{
let _timer = timer!("apply full optimizer");

let mut data = analyze(&*n, Some(self.marks), false);
let mut data = analyze(&*n, Some(self.marks), false, self.id_map);

// TODO: reset_opt_flags
//
Expand All @@ -185,6 +190,7 @@ impl Compressor<'_> {
self.mangle_options,
&mut data,
self.mode,
self.id_map,
);
n.visit_mut_with(&mut visitor);

Expand Down
2 changes: 1 addition & 1 deletion crates/swc_ecma_minifier/src/compress/optimize/arguments.rs
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Expand Up @@ -77,7 +77,7 @@ impl Optimizer<'_> {
Pat::Ident(i) => self
.data
.vars
.get(&i.id.to_id())
.get(&self.id_map.intern_ident(&i.id))
.map(|v| v.declared_count >= 2)
.unwrap_or(false),
_ => true,
Expand Down
2 changes: 1 addition & 1 deletion crates/swc_ecma_minifier/src/compress/optimize/bools.rs
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Expand Up @@ -22,7 +22,7 @@ impl Optimizer<'_> {
) if &**l_v == "undefined" => {
// TODO?
if let Expr::Ident(arg) = &**arg {
if let Some(usage) = o.data.vars.get(&arg.to_id()) {
if let Some(usage) = o.data.vars.get(&o.id_map.intern_ident(arg)) {
if !usage.flags.contains(VarUsageInfoFlags::DECLARED) {
return false;
}
Expand Down
8 changes: 4 additions & 4 deletions crates/swc_ecma_minifier/src/compress/optimize/conditionals.rs
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Expand Up @@ -387,7 +387,7 @@ impl Optimizer<'_> {
// to f(a, a = 1 ? true : false)
let side_effects_in_test = test.may_have_side_effects(self.ctx.expr_ctx);

if self.data.contains_unresolved(test) {
if self.data.contains_unresolved(test, self.id_map) {
return None;
}

Expand All @@ -404,7 +404,7 @@ impl Optimizer<'_> {
let side_effect_free = self
.data
.vars
.get(&cons_callee.to_id())
.get(&self.id_map.intern_ident(cons_callee))
.map(|v| {
v.flags.contains(
VarUsageInfoFlags::IS_FN_LOCAL.union(VarUsageInfoFlags::DECLARED),
Expand Down Expand Up @@ -526,7 +526,7 @@ impl Optimizer<'_> {
}

(Expr::New(cons), Expr::New(alt)) => {
if self.data.contains_unresolved(test) {
if self.data.contains_unresolved(test, self.id_map) {
return None;
}

Expand Down Expand Up @@ -590,7 +590,7 @@ impl Optimizer<'_> {
) if cons.left.eq_ignore_span(&alt.left) && cons.left.as_ident().is_some() => {
if self
.data
.ident_is_unresolved(&cons.left.as_ident().unwrap().id)
.ident_is_unresolved(&cons.left.as_ident().unwrap().id, self.id_map)
{
return None;
}
Expand Down
4 changes: 2 additions & 2 deletions crates/swc_ecma_minifier/src/compress/optimize/dead_code.rs
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Expand Up @@ -58,7 +58,7 @@ impl Optimizer<'_> {
if self
.data
.vars
.get(&lhs.to_id())
.get(&self.id_map.intern_ident(lhs))
.map(|var| {
var.flags.contains(
VarUsageInfoFlags::DECLARED.union(VarUsageInfoFlags::IS_FN_LOCAL),
Expand Down Expand Up @@ -97,7 +97,7 @@ impl Optimizer<'_> {
if self
.data
.vars
.get(&lhs.to_id())
.get(&self.id_map.intern_ident(lhs))
.map(|var| {
var.flags.contains(
VarUsageInfoFlags::DECLARED.union(VarUsageInfoFlags::IS_FN_LOCAL),
Expand Down
8 changes: 4 additions & 4 deletions crates/swc_ecma_minifier/src/compress/optimize/evaluate.rs
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Expand Up @@ -42,9 +42,9 @@ impl Optimizer<'_> {
}) = e
{
if let Expr::Ident(obj) = &**obj {
let metadata = *self.functions.get(&obj.to_id())?;

let usage = self.data.vars.get(&obj.to_id())?;
let hashed_id = self.id_map.intern_ident(obj);
let metadata = *self.functions.get(&hashed_id)?;
let usage = self.data.vars.get(&hashed_id)?;

if usage.flags.contains(VarUsageInfoFlags::REASSIGNED) {
return None;
Expand Down Expand Up @@ -101,7 +101,7 @@ impl Optimizer<'_> {
if self
.data
.vars
.get(&i.to_id())
.get(&self.id_map.intern_ident(i))
.map(|var| var.flags.contains(VarUsageInfoFlags::DECLARED))
.unwrap_or(false)
{
Expand Down
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