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Merged
kdy1 merged 4 commits into from
Apr 8, 2026
Merged

refact(es/minifier): Inline into shorthand prop early #11766

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6a3f79a
refact(es/minifier): Inline into shorthand prop early
Austaras Apr 3, 2026
77ab186
test(minifier): add shorthand inline regression coverage
kdy1 Apr 5, 2026
ca4951d
fix renamer
Austaras Apr 7, 2026
9f846ea
Create healthy-hats-peel.md
kdy1 Apr 8, 2026
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129 changes: 68 additions & 61 deletions crates/swc_ecma_minifier/src/compress/optimize/inline.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -912,7 +912,6 @@ impl Optimizer<'_> {
}
}

/// Actually inlines variables.
pub(super) fn inline(&mut self, e: &mut Expr) {
if self.ctx.bit_ctx.contains(BitCtx::IsExactLhsOfAssign) {
return;
Expand All @@ -936,81 +935,89 @@ impl Optimizer<'_> {
}
}
Expr::Ident(i) => {
let id = i.to_id();
if let Some(value) = self.vars.lits.get(&id).or_else(|| {
if self.ctx.bit_ctx.contains(BitCtx::IsCallee) {
self.vars.simple_functions.get(&id)
} else {
None
}
}) {
if !matches!(**value, Expr::Ident(..) | Expr::Member(..))
&& self.ctx.bit_ctx.contains(BitCtx::IsUpdateArg)
{
return;
}

// currently renamer relies on the fact no distinct var has same ctxt, we need
// to remap all new bindings.
let bindings: FxHashSet<Id> = collect_decls(value);
let new_mark = Mark::new();
let mut cache = FxHashMap::default();
let mut remap = FxHashMap::default();

for id in bindings {
let new_ctxt = cache
.entry(id.1)
.or_insert_with(|| id.1.apply_mark(new_mark));
if let Some(value) = self.inline_ident(i) {
*e = *value
}
}
_ => (),
}
}

let new_ctxt = *new_ctxt;
/// Actually inlines variables.
pub(super) fn inline_ident(&mut self, ident: &Ident) -> Option<Box<Expr>> {
let id = ident.to_id();

if let Some(usage) = self.data.vars.get(&id).cloned() {
let new_id = (id.0.clone(), new_ctxt);
self.data.vars.insert(new_id, usage);
}
if let Some(value) = self.vars.lits.get(&id).or_else(|| {
if self.ctx.bit_ctx.contains(BitCtx::IsCallee) {
self.vars.simple_functions.get(&id)
} else {
None
}
}) {
if !matches!(**value, Expr::Ident(..) | Expr::Member(..))
&& self.ctx.bit_ctx.contains(BitCtx::IsUpdateArg)
{
return None;
}

remap.insert(id, new_ctxt);
}
// currently renamer relies on the fact no distinct var has same ctxt, we need
// to remap all new bindings.
let bindings: FxHashSet<Id> = collect_decls(value);
let new_mark = Mark::new();
let mut cache = FxHashMap::default();
let mut remap = FxHashMap::default();

let mut value = value.clone();
if !remap.is_empty() {
let mut remapper = Remapper::new(&remap);
value.visit_mut_with(&mut remapper);
}
for id in bindings {
let new_ctxt = cache
.entry(id.1)
.or_insert_with(|| id.1.apply_mark(new_mark));

self.changed = true;
report_change!("inline: Replacing a variable `{}` with cheap expression", i);
let new_ctxt = *new_ctxt;

*e = *value;
return;
if let Some(usage) = self.data.vars.get(&id).cloned() {
let new_id = (id.0.clone(), new_ctxt);
self.data.vars.insert(new_id, usage);
}

// Check without cloning
if let Some(value) = self.vars.vars_for_inlining.get(&id) {
if self.ctx.bit_ctx.contains(BitCtx::IsExactLhsOfAssign)
&& !is_valid_for_lhs(value)
{
return;
}
remap.insert(id, new_ctxt);
}

if let Expr::Member(..) = &**value {
if self.ctx.bit_ctx.contains(BitCtx::ExecutedMultipleTime) {
return;
}
}
}
let mut value = value.clone();
if !remap.is_empty() {
let mut remapper = Remapper::new(&remap);
value.visit_mut_with(&mut remapper);
}

if let Some(value) = self.vars.vars_for_inlining.remove(&id) {
self.changed = true;
report_change!("inline: Replacing '{}' with an expression", i);
self.changed = true;
report_change!(
"inline: Replacing a variable `{}` with cheap expression",
ident
);

*e = *value;
return Some(value);
}

// Check without cloning
if let Some(value) = self.vars.vars_for_inlining.get(&id) {
if self.ctx.bit_ctx.contains(BitCtx::IsExactLhsOfAssign) && !is_valid_for_lhs(value) {
return None;
}

log_abort!("inline: [Change] {}", crate::debug::dump(&*e, false))
if let Expr::Member(..) = &**value {
if self.ctx.bit_ctx.contains(BitCtx::ExecutedMultipleTime) {
return None;
}
}
_ => (),
}

if let Some(value) = self.vars.vars_for_inlining.remove(&id) {
self.changed = true;
report_change!("inline: Replacing '{}' with an expression", ident);

return Some(value);
}

None
}
}

Expand Down
17 changes: 16 additions & 1 deletion crates/swc_ecma_minifier/src/compress/optimize/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,10 @@ use super::util::{drop_invalid_stmts, is_fine_for_if_cons};
#[cfg(feature = "debug")]
use crate::debug::dump;
use crate::{
compress::{optimize::util::get_ids_of_pat, util::is_pure_undefined},
compress::{
optimize::util::{get_ids_of_pat, prop_name_from_ident},
util::is_pure_undefined,
},
debug::AssertValid,
maybe_par,
mode::Mode,
Expand Down Expand Up @@ -2489,6 +2492,18 @@ impl VisitMut for Optimizer<'_> {
n.retain(|p| !p.pat.is_invalid());
}

fn visit_mut_prop(&mut self, n: &mut Prop) {
n.visit_mut_children_with(self);

if let Prop::Shorthand(i) = n {
if let Some(expr) = self.inline_ident(i) {
let key = prop_name_from_ident(i.take());
*n = Prop::KeyValue(KeyValueProp { key, value: expr });
self.changed = true;
}
}
}

#[cfg_attr(feature = "debug", tracing::instrument(level = "debug", skip_all))]
fn visit_mut_return_stmt(&mut self, n: &mut ReturnStmt) {
n.visit_mut_children_with(self);
Expand Down
2 changes: 1 addition & 1 deletion crates/swc_ecma_minifier/src/compress/optimize/util.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -826,7 +826,7 @@ pub fn get_ids_of_pat(pat: &Pat) -> Vec<Id> {
/// Creates a PropName for a shorthand property, handling the special case of
/// `__proto__`. When the property name is `__proto__`, it must be converted to
/// a computed property to preserve JavaScript semantics.
fn prop_name_from_ident(ident: Ident) -> PropName {
pub(crate) fn prop_name_from_ident(ident: Ident) -> PropName {
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Copilot AI Apr 3, 2026

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prop_name_from_ident is only referenced within the compress::optimize module (currently optimize/mod.rs and this file). Exposing it as pub(crate) increases the crate-wide API surface unnecessarily; consider reducing visibility to pub(super) (or pub(in crate::compress::optimize)) to keep the helper scoped to this module.

Suggested change
pub(crate) fn prop_name_from_ident(ident: Ident) -> PropName {
pub(super) fn prop_name_from_ident(ident: Ident) -> PropName {

Copilot uses AI. Check for mistakes.
if ident.sym == "__proto__" {
PropName::Computed(ComputedPropName {
span: ident.span,
Expand Down
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