From 4c9e5c01ef91d01c95a6e928daa9e99839eabedf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Donny/=EA=B0=95=EB=8F=99=EC=9C=A4?= <kdy1997.dev@gmail.com>
Date: Sat, 23 Apr 2022 19:53:21 +0900
Subject: [PATCH] perf(es/minifier): Add some fast-path to the `MultiReplacer`
 (#4408)

---
 .../swc_ecma_minifier/examples/minify-all.rs  |  4 +--
 .../scripts/instrument/all.sh                 |  2 +-
 .../src/compress/optimize/util.rs             | 33 ++++++++++++-------
 3 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/crates/swc_ecma_minifier/examples/minify-all.rs b/crates/swc_ecma_minifier/examples/minify-all.rs
index b99058e4b26..400c617fab0 100644
--- a/crates/swc_ecma_minifier/examples/minify-all.rs
+++ b/crates/swc_ecma_minifier/examples/minify-all.rs
@@ -23,8 +23,8 @@ fn main() {
 
     testing::run_test2(false, |cm, handler| {
         GLOBALS.with(|globals| {
-            files
-                .into_par_iter()
+            let _ = files
+                .into_iter()
                 .map(|path| -> Result<_> {
                     GLOBALS.set(globals, || {
                         let fm = cm.load_file(&path).expect("failed to load file");
diff --git a/crates/swc_ecma_minifier/scripts/instrument/all.sh b/crates/swc_ecma_minifier/scripts/instrument/all.sh
index 43471edcd04..9ed816793a4 100755
--- a/crates/swc_ecma_minifier/scripts/instrument/all.sh
+++ b/crates/swc_ecma_minifier/scripts/instrument/all.sh
@@ -8,4 +8,4 @@
 
 
 export RUST_LOG=off
-cargo profile instruments -t time --example minify-all --release -- $@
\ No newline at end of file
+cargo profile instruments -t time --example minify-all --features swc_common/perf --release -- $@
\ No newline at end of file
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/util.rs b/crates/swc_ecma_minifier/src/compress/optimize/util.rs
index e11b7a052be..ef7d951e560 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/util.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/util.rs
@@ -250,8 +250,15 @@ impl VisitMut for MultiReplacer<'_> {
     }
 
     fn visit_mut_expr(&mut self, e: &mut Expr) {
+        if self.vars.is_empty() {
+            return;
+        }
         e.visit_mut_children_with(self);
 
+        if self.vars.is_empty() {
+            return;
+        }
+
         if matches!(self.mode, MultiReplacerMode::Normal) {
             if let Expr::Ident(i) = e {
                 if let Some(new) = self.var(&i.to_id()) {
@@ -286,19 +293,21 @@ impl VisitMut for MultiReplacer<'_> {
     fn visit_mut_prop(&mut self, p: &mut Prop) {
         p.visit_mut_children_with(self);
 
-        if let Prop::Shorthand(i) = p {
-            if let Some(value) = self.var(&i.to_id()) {
-                debug!("multi-replacer: Replaced `{}` as shorthand", i);
-                *self.worked = true;
-                self.changed = true;
+        if matches!(self.mode, MultiReplacerMode::Normal) {
+            if let Prop::Shorthand(i) = p {
+                if let Some(value) = self.var(&i.to_id()) {
+                    debug!("multi-replacer: Replaced `{}` as shorthand", i);
+                    *self.worked = true;
+                    self.changed = true;
 
-                *p = Prop::KeyValue(KeyValueProp {
-                    key: PropName::Ident(Ident::new(
-                        i.sym.clone(),
-                        i.span.with_ctxt(Default::default()),
-                    )),
-                    value,
-                });
+                    *p = Prop::KeyValue(KeyValueProp {
+                        key: PropName::Ident(Ident::new(
+                            i.sym.clone(),
+                            i.span.with_ctxt(Default::default()),
+                        )),
+                        value,
+                    });
+                }
             }
         }
     }