perf(es/hygiene): Fix performance bug (#3090)

swc_ecma_transforms_base:
 - `hygiene`: Skip checking a symbol if we are sure that it will be discarded.

swc_ecma_laoder:
 - Optimize `NodeModulesResolver` by trying `.js` first.

crates/swc/tests/tsc-references/ES5For-of19_es5.1.normal.js

@@ -6,8 +6,8 @@ try {
             var _iteratorNormalCompletion1 = true, _didIteratorError1 = false, _iteratorError1 = undefined;
             try {
                 for(var _iterator2 = [][Symbol.iterator](), _step2; !(_iteratorNormalCompletion1 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion1 = true){
-                    var v2 = _step2.value;
-                    v2;
+                    var v3 = _step2.value;
+                    v3;
                 }
             } catch (err) {
                 _didIteratorError1 = true;

crates/swc_bundler/tests/fixture/deno-9219/case1/output/entry.inlined.ts

@@ -33,7 +33,7 @@ function hasKey(obj, keys) {
     const key1 = keys[keys.length - 1];
     return key1 in o;
 }
-function parse(args1, { "--": doubleDash = false , alias: alias2 = {
+function parse(args1, { "--": doubleDash = false , alias: alias3 = {
 } , boolean: __boolean = false , default: defaults = {
 } , stopEarly =false , string =[] , unknown =(i)=>i
   } = {
@@ -60,9 +60,9 @@ function parse(args1, { "--": doubleDash = false , alias: alias2 = {
     }
     const aliases = {
     };
-    if (alias2 !== undefined) {
-        for(const key in alias2){
-            const val = getForce(alias2, key);
+    if (alias3 !== undefined) {
+        for(const key in alias3){
+            const val = getForce(alias3, key);
             if (typeof val === "string") {
                 aliases[key] = [
                     val

crates/swc_bundler/tests/fixture/deno-9219/case1/output/entry.ts

@@ -33,7 +33,7 @@ function hasKey(obj, keys) {
     const key1 = keys[keys.length - 1];
     return key1 in o;
 }
-function parse(args1, { "--": doubleDash = false , alias: alias2 = {
+function parse(args1, { "--": doubleDash = false , alias: alias3 = {
 } , boolean: __boolean = false , default: defaults = {
 } , stopEarly =false , string =[] , unknown =(i)=>i
   } = {
@@ -60,9 +60,9 @@ function parse(args1, { "--": doubleDash = false , alias: alias2 = {
     }
     const aliases = {
     };
-    if (alias2 !== undefined) {
-        for(const key in alias2){
-            const val = getForce(alias2, key);
+    if (alias3 !== undefined) {
+        for(const key in alias3){
+            const val = getForce(alias3, key);
             if (typeof val === "string") {
                 aliases[key] = [
                     val

crates/swc_bundler/tests/fixture/deno-9591/output/entry.inlined.ts

@@ -33,7 +33,7 @@ function hasKey(obj, keys) {
     const key1 = keys[keys.length - 1];
     return key1 in o;
 }
-function parse(args, { "--": doubleDash = false , alias: alias2 = {
+function parse(args, { "--": doubleDash = false , alias: alias3 = {
 } , boolean: __boolean = false , default: defaults = {
 } , stopEarly =false , string =[] , unknown =(i1)=>i1
   } = {
@@ -60,9 +60,9 @@ function parse(args, { "--": doubleDash = false , alias: alias2 = {
     }
     const aliases = {
     };
-    if (alias2 !== undefined) {
-        for(const key in alias2){
-            const val = getForce(alias2, key);
+    if (alias3 !== undefined) {
+        for(const key in alias3){
+            const val = getForce(alias3, key);
             if (typeof val === "string") {
                 aliases[key] = [
                     val

crates/swc_bundler/tests/fixture/deno-9591/output/entry.ts

@@ -33,7 +33,7 @@ function hasKey(obj, keys) {
     const key1 = keys[keys.length - 1];
     return key1 in o;
 }
-function parse(args, { "--": doubleDash = false , alias: alias2 = {
+function parse(args, { "--": doubleDash = false , alias: alias3 = {
 } , boolean: __boolean = false , default: defaults = {
 } , stopEarly =false , string =[] , unknown =(i1)=>i1
   } = {
@@ -60,9 +60,9 @@ function parse(args, { "--": doubleDash = false , alias: alias2 = {
     }
     const aliases = {
     };
-    if (alias2 !== undefined) {
-        for(const key in alias2){
-            const val = getForce(alias2, key);
+    if (alias3 !== undefined) {
+        for(const key in alias3){
+            const val = getForce(alias3, key);
             if (typeof val === "string") {
                 aliases[key] = [
                     val

crates/swc_ecma_loader/src/resolvers/node.rs

@@ -104,8 +104,25 @@ impl NodeModulesResolver {
     /// Resolve a path as a file. If `path` refers to a file, it is returned;
     /// otherwise the `path` + each extension is tried.
     fn resolve_as_file(&self, path: &Path) -> Result<Option<PathBuf>, Error> {
-        if path.is_file() {
-            return Ok(Some(path.to_path_buf()));
+        let try_exact = path.extension().is_some();
+        if try_exact {
+            if path.is_file() {
+                return Ok(Some(path.to_path_buf()));
+            }
+        } else {
+            // We try `.js` first.
+            let mut path = path.to_path_buf();
+            path.set_extension("js");
+            if path.is_file() {
+                return Ok(Some(path));
+            }
+        }
+
+        // Try exact file after checking .js, for performance
+        if !try_exact {
+            if path.is_file() {
+                return Ok(Some(path.to_path_buf()));
+            }
         }
 
         if let Some(name) = path.file_name() {