perf: Improve generator perf

babel.config.js

@@ -162,7 +162,11 @@ module.exports = function (api) {
     presets: [
       [
         "@babel/preset-typescript",
-        { onlyRemoveTypeImports: true, allowDeclareFields: true },
+        {
+          onlyRemoveTypeImports: true,
+          allowDeclareFields: true,
+          optimizeConstEnums: true,
+        },
       ],
       ["@babel/env", envOpts],
       ["@babel/preset-flow", { allowDeclareFields: true }],
@@ -200,6 +204,10 @@ module.exports = function (api) {
         ].map(normalize),
         plugins: ["babel-plugin-transform-charcodes"],
       },
+      {
+        test: ["packages/babel-generator"].map(normalize),
+        plugins: [pluginGeneratorOptimization],
+      },
       convertESM && {
         test: ["./packages/babel-node/src"].map(normalize),
         // Used to conditionally import kexec
@@ -781,3 +789,37 @@ function pluginInjectNodeReexportsHints({ types: t, template }, { names }) {
     },
   };
 }
+
+/**
+ * @param {import("@babel/core")} pluginAPI
+ * @returns {import("@babel/core").PluginObj}
+ */
+function pluginGeneratorOptimization({ types: t }) {
+  return {
+    visitor: {
+      CallExpression: {
+        exit(path) {
+          const node = path.node;
+          if (
+            t.isMemberExpression(node.callee) &&
+            t.isThisExpression(node.callee.object)
+          ) {
+            const args = node.arguments;
+
+            if (
+              node.callee.property.name === "token" &&
+              args.length === 1 &&
+              t.isStringLiteral(args[0])
+            ) {
+              const str = args[0].value;
+              if (str.length == 1) {
+                node.callee.property.name = "tokenChar";
+                args[0] = t.numericLiteral(str.charCodeAt(0));
+              }
+            }
+          }
+        },
+      },
+    },
+  };
+}

benchmark/babel-generator/real-case/jquery.mjs

@@ -15,16 +15,20 @@ function createInput(length) {
   );
 }
 
+const inputs = [1, 4, 16, 64].map(length => ({
+  tag: length,
+  body: createInput(length),
+}));
+
 function benchCases(name, implementation, options) {
-  for (const length of [1, 2]) {
-    const input = createInput(length);
-    suite.add(`${name} ${length} jquery 3.6`, () => {
-      implementation(input, options);
+  for (const input of inputs) {
+    suite.add(`${name} ${input.tag} jquery 3.6`, () => {
+      implementation(input.body, options);
     });
   }
 }
 
-benchCases("baseline", baseline.default);
 benchCases("current", current.default);
+benchCases("baseline", baseline.default);
 
 suite.on("cycle", report).run();