perf: Improve module transforms (#16882)

packages/babel-helper-module-transforms/package.json

@@ -16,7 +16,6 @@
   "main": "./lib/index.js",
   "dependencies": {
     "@babel/helper-module-imports": "workspace:^",
-    "@babel/helper-simple-access": "workspace:^",
     "@babel/helper-validator-identifier": "workspace:^",
     "@babel/traverse": "workspace:^"
   },

packages/babel-helper-module-transforms/src/rewrite-live-references.ts

@@ -1,7 +1,5 @@
-import assert from "assert";
 import { template, types as t } from "@babel/core";
 import type { NodePath, Visitor, Scope } from "@babel/core";
-import simplifyAccess from "@babel/helper-simple-access";
 
 import type { ModuleMetadata } from "./normalize-and-load-metadata.ts";
 
@@ -97,18 +95,6 @@ export default function rewriteLiveReferences(
     rewriteBindingInitVisitorState,
   );
 
-  // NOTE(logan): The 'Array.from' calls are to make this code with in loose mode.
-  const bindingNames = new Set([
-    ...Array.from(imported.keys()),
-    ...Array.from(exported.keys()),
-  ]);
-  if (process.env.BABEL_8_BREAKING) {
-    simplifyAccess(programPath, bindingNames);
-  } else {
-    // @ts-ignore(Babel 7 vs Babel 8) The third param has been removed in Babel 8.
-    simplifyAccess(programPath, bindingNames, false);
-  }
-
   // Rewrite reads/writes from imports and exports to have the correct behavior.
   const rewriteReferencesVisitorState: RewriteReferencesVisitorState = {
     seen: new WeakSet(),
@@ -454,8 +440,6 @@ const rewriteReferencesVisitor: Visitor<RewriteReferencesVisitorState> = {
         const exportedNames = exported.get(localName);
         const importData = imported.get(localName);
         if (exportedNames?.length > 0 || importData) {
-          assert(path.node.operator === "=", "Path was not simplified");
-
           const assignment = path.node;
 
           if (importData) {
@@ -467,15 +451,48 @@ const rewriteReferencesVisitor: Visitor<RewriteReferencesVisitorState> = {
             ]);
           }
 
+          const { operator } = assignment;
+          let newExpr;
+          if (operator === "=") {
+            newExpr = assignment;
+          } else if (
+            operator === "&&=" ||
+            operator === "||=" ||
+            operator === "??="
+          ) {
+            newExpr = t.assignmentExpression(
+              "=",
+              assignment.left,
+              t.logicalExpression(
+                operator.slice(0, -1) as t.LogicalExpression["operator"],
+                t.cloneNode(assignment.left) as t.Expression,
+                assignment.right,
+              ),
+            );
+          } else {
+            newExpr = t.assignmentExpression(
+              "=",
+              assignment.left,
+              t.binaryExpression(
+                operator.slice(0, -1) as t.BinaryExpression["operator"],
+                t.cloneNode(assignment.left) as t.Expression,
+                assignment.right,
+              ),
+            );
+          }
+
           path.replaceWith(
             buildBindingExportAssignmentExpression(
               this.metadata,
               exportedNames,
-              assignment,
+              newExpr,
               path.scope,
             ),
           );
+
           requeueInParent(path);
+
+          path.skip();
         }
       } else {
         const ids = left.getOuterBindingIdentifiers();
@@ -523,9 +540,7 @@ const rewriteReferencesVisitor: Visitor<RewriteReferencesVisitorState> = {
       }
     },
   },
-  "ForOfStatement|ForInStatement"(
-    path: NodePath<t.ForOfStatement | t.ForInStatement>,
-  ) {
+  ForXStatement(path) {
     const { scope, node } = path;
     const { left } = node;
     const { exported, imported, scope: programScope } = this;

packages/babel-helper-module-transforms/tsconfig.json

@@ -13,9 +13,6 @@
     {
       "path": "../../packages/babel-helper-module-imports"
     },
-    {
-      "path": "../../packages/babel-helper-simple-access"
-    },
     {
       "path": "../../packages/babel-helper-validator-identifier"
     },

packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/export-var-and-modify/input.mjs

@@ -0,0 +1,20 @@
+var a;
+
+a += 1;
+a -= 1;
+a *= 1;
+a /= 1;
+a %= 1;
+a **= 1;
+a <<= 1;
+a >>= 1;
+a >>>= 1;
+a &= 1;
+a ^= 1;
+a |= 1;
+
+a &&= 1;
+a ||= 1;
+a ??= 1;
+
+export { a };

packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/export-var-and-modify/output.js

@@ -0,0 +1,22 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.a = void 0;
+var a;
+exports.a = a = a + 1;
+exports.a = a = a - 1;
+exports.a = a = a * 1;
+exports.a = a = a / 1;
+exports.a = a = a % 1;
+exports.a = a = a ** 1;
+exports.a = a = a << 1;
+exports.a = a = a >> 1;
+exports.a = a = a >>> 1;
+exports.a = a = a & 1;
+exports.a = a = a ^ 1;
+exports.a = a = a | 1;
+exports.a = a = a && 1;
+exports.a = a = a || 1;
+exports.a = a = a ?? 1;

packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/import-const-throw/output.js

@@ -45,33 +45,33 @@ _baz.Baz = (44, function () {
 } = ({}, function () {
   throw new Error('"' + "Baz" + '" is read-only.');
 }()));
-_foo.default = (_foo.default + 2, function () {
+_foo.default = _foo.default + (2, function () {
   throw new Error('"' + "Foo" + '" is read-only.');
 }());
-Bar = (Bar + 2, function () {
+Bar = Bar + (2, function () {
   throw new Error('"' + "Bar" + '" is read-only.');
 }());
-_baz.Baz = (_baz.Baz + 2, function () {
+_baz.Baz = _baz.Baz + (2, function () {
   throw new Error('"' + "Baz" + '" is read-only.');
 }());
-_foo.default = (_foo.default >>> 3, function () {
+_foo.default = _foo.default >>> (3, function () {
   throw new Error('"' + "Foo" + '" is read-only.');
 }());
-Bar = (Bar >>> 3, function () {
+Bar = Bar >>> (3, function () {
   throw new Error('"' + "Bar" + '" is read-only.');
 }());
-_baz.Baz = (_baz.Baz >>> 3, function () {
+_baz.Baz = _baz.Baz >>> (3, function () {
   throw new Error('"' + "Baz" + '" is read-only.');
 }());
-_foo.default && (_foo.default = (4, function () {
+_foo.default = _foo.default && (4, function () {
   throw new Error('"' + "Foo" + '" is read-only.');
-}()));
-Bar && (Bar = (4, function () {
+}());
+Bar = Bar && (4, function () {
   throw new Error('"' + "Bar" + '" is read-only.');
-}()));
-_baz.Baz && (_baz.Baz = (4, function () {
+}());
+_baz.Baz = _baz.Baz && (4, function () {
   throw new Error('"' + "Baz" + '" is read-only.');
-}()));
+}());
 _foo.default -= function () {
   throw new Error('"' + "Foo" + '" is read-only.');
 }();

yarn.lock

@@ -816,7 +816,6 @@ __metadata:
   dependencies:
     "@babel/core": "workspace:^"
     "@babel/helper-module-imports": "workspace:^"
-    "@babel/helper-simple-access": "workspace:^"
     "@babel/helper-validator-identifier": "workspace:^"
     "@babel/traverse": "workspace:^"
   peerDependencies: