perf: Improve builders of @babel/types (#16870)

* perf

* improve

* Update packages/babel-types/src/definitions/index.ts

Co-authored-by: Nicolò Ribaudo <[email protected]>

* review

* review

* review

---------

Co-authored-by: Nicolò Ribaudo <[email protected]>

benchmark/babel-types/builders/blockStatement.mjs

@@ -0,0 +1,20 @@
+import { Benchmark, baselineTypes, currentTypes } from "../../util.mjs";
+
+const bench = new Benchmark();
+
+function benchCases(implementations, num) {
+  for (const version in implementations) {
+    const t = implementations[version];
+    const blockStatement = t.blockStatement;
+
+    const stmts = new Array(num).fill(t.emptyStatement());
+    bench.add(`${version} builder ${num}`, () => {
+      blockStatement(stmts);
+    });
+  }
+}
+
+benchCases({ baselineTypes, currentTypes }, 1);
+benchCases({ baselineTypes, currentTypes }, 128);
+
+bench.run();

eslint.config.mjs

@@ -77,6 +77,7 @@ export default [
         requireConfigFile: false,
         babelOptions: {
           babelrc: false,
+          browserslistConfigFile: false,
           configFile: false,
           // Todo: Remove the parserOpts here after the proposal gets stage 4.
           parserOpts: {

packages/babel-types/src/definitions/core.ts

@@ -545,7 +545,7 @@ defineType("Identifier", {
   validate:
     process.env.BABEL_8_BREAKING || process.env.BABEL_TYPES_8_BREAKING
       ? function (parent, key, node) {
-          const match = /\.(\w+)$/.exec(key);
+          const match = /\.(\w+)$/.exec(key.toString());
           if (!match) return;
 
           const [, parentKey] = match;
@@ -1025,7 +1025,7 @@ defineType("RestElement", {
   validate:
     process.env.BABEL_8_BREAKING || process.env.BABEL_TYPES_8_BREAKING
       ? function (parent: t.ArrayPattern | t.ObjectPattern, key) {
-          const match = /(\w+)\[(\d+)\]/.exec(key);
+          const match = /(\w+)\[(\d+)\]/.exec(key.toString());
           if (!match) throw new Error("Internal Babel error: malformed key.");
 
           const [, listKey, index] = match as unknown as [

packages/babel-types/src/definitions/index.ts

@@ -12,6 +12,7 @@ import {
   BUILDER_KEYS,
   DEPRECATED_KEYS,
   NODE_PARENT_VALIDATIONS,
+  allExpandedTypes,
 } from "./utils.ts";
 import {
   PLACEHOLDERS,
@@ -27,6 +28,17 @@ import { DEPRECATED_ALIASES } from "./deprecated-aliases.ts";
     FLIPPED_ALIAS_KEYS[DEPRECATED_ALIASES[deprecatedAlias]];
 });
 
+for (const { types, set } of allExpandedTypes) {
+  for (const type of types) {
+    const aliases = FLIPPED_ALIAS_KEYS[type];
+    if (aliases) {
+      aliases.forEach(set.add, set);
+    } else {
+      set.add(type);
+    }
+  }
+}
+
 const TYPES: Array<string> = [].concat(
   Object.keys(VISITOR_KEYS),
   Object.keys(FLIPPED_ALIAS_KEYS),

packages/babel-types/src/definitions/utils.ts

@@ -51,7 +51,7 @@ export type Validator = (
   | { shapeOf: { [x: string]: FieldOptions } }
   | object
 ) &
-  ((node: t.Node, key: string, val: any) => void);
+  ((node: t.Node, key: string | { toString(): string }, val: any) => void);
 
 export type FieldOptions = {
   default?: string | number | boolean | [];
@@ -96,11 +96,21 @@ export function assertEach(callback: Validator): Validator {
   function validator(node: t.Node, key: string, val: any) {
     if (!Array.isArray(val)) return;
 
-    for (let i = 0; i < val.length; i++) {
-      const subkey = `${key}[${i}]`;
+    let i = 0;
+    // We lazily concatenate strings here for performance reasons.
+    // Concatenating the strings is expensive because we are actually concatenating a string and a number,
+    // so V8 cannot just create a "rope string" but has to allocate memory for the string resulting from the number
+    // This string is very rarely used, only in error paths, so we can skip the concatenation cost in most cases
+    const subKey = {
+      toString() {
+        return `${key}[${i}]`;
+      },
+    };
+
+    for (; i < val.length; i++) {
       const v = val[i];
-      callback(node, subkey, v);
-      childValidator(node, subkey, v);
+      callback(node, subKey, v);
+      childValidator(node, subKey, v);
     }
   }
   validator.each = callback;
@@ -123,13 +133,31 @@ export function assertOneOf(...values: Array<any>): Validator {
   return validate;
 }
 
+export const allExpandedTypes: {
+  types: NodeTypes[];
+  set: Set<string>;
+}[] = [];
+
 export function assertNodeType(...types: NodeTypes[]): Validator {
+  const expandedTypes = new Set<string>();
+
+  allExpandedTypes.push({ types, set: expandedTypes });
+
   function validate(node: t.Node, key: string, val: any) {
-    for (const type of types) {
-      if (is(type, val)) {
+    const valType = val?.type;
+    if (valType != null) {
+      if (expandedTypes.has(valType)) {
         validateChild(node, key, val);
         return;
       }
+      if (valType === "Placeholder") {
+        for (const type of types) {
+          if (is(type, val)) {
+            validateChild(node, key, val);
+            return;
+          }
+        }
+      }
     }
 
     throw new TypeError(
@@ -137,7 +165,7 @@ export function assertNodeType(...types: NodeTypes[]): Validator {
         node.type
       } expected node to be of a type ${JSON.stringify(
         types,
-      )} but instead got ${JSON.stringify(val?.type)}`,
+      )} but instead got ${JSON.stringify(valType)}`,
     );
   }
 
@@ -150,8 +178,9 @@ export function assertNodeOrValueType(
   ...types: (NodeTypes | PrimitiveTypes)[]
 ): Validator {
   function validate(node: t.Node, key: string, val: any) {
+    const primitiveType = getType(val);
     for (const type of types) {
-      if (getType(val) === type || is(type, val)) {
+      if (primitiveType === type || is(type, val)) {
         validateChild(node, key, val);
         return;
       }
@@ -173,13 +202,13 @@ export function assertNodeOrValueType(
 
 export function assertValueType(type: PrimitiveTypes): Validator {
   function validate(node: t.Node, key: string, val: any) {
-    const valid = getType(val) === type;
-
-    if (!valid) {
-      throw new TypeError(
-        `Property ${key} expected type of ${type} but got ${getType(val)}`,
-      );
+    if (getType(val) === type) {
+      return;
     }
+
+    throw new TypeError(
+      `Property ${key} expected type of ${type} but got ${getType(val)}`,
+    );
   }
 
   validate.type = type;
@@ -188,9 +217,10 @@ export function assertValueType(type: PrimitiveTypes): Validator {
 }
 
 export function assertShape(shape: { [x: string]: FieldOptions }): Validator {
+  const keys = Object.keys(shape);
   function validate(node: t.Node, key: string, val: any) {
     const errors = [];
-    for (const property of Object.keys(shape)) {
+    for (const property of keys) {
       try {
         validateField(node, property, val[property], shape[property]);
       } catch (error) {

packages/babel-types/src/validators/isPlaceholderType.ts

@@ -11,11 +11,7 @@ export default function isPlaceholderType(
 
   const aliases: Array<string> | undefined =
     PLACEHOLDERS_ALIAS[placeholderType];
-  if (aliases) {
-    for (const alias of aliases) {
-      if (targetType === alias) return true;
-    }
-  }
+  if (aliases?.includes(targetType)) return true;
 
   return false;
 }

packages/babel-types/src/validators/isType.ts

@@ -26,13 +26,7 @@ export default function isType(nodeType: string, targetType: string): boolean {
   if (ALIAS_KEYS[targetType]) return false;
 
   const aliases: Array<string> | undefined = FLIPPED_ALIAS_KEYS[targetType];
-  if (aliases) {
-    if (aliases[0] === nodeType) return true;
-
-    for (const alias of aliases) {
-      if (nodeType === alias) return true;
-    }
-  }
+  if (aliases?.includes(nodeType)) return true;
 
   return false;
 }

packages/babel-types/src/validators/validate.ts

@@ -53,7 +53,7 @@ export function validateField(
 
 export function validateChild(
   node: t.Node | undefined | null,
-  key: string,
+  key: string | { toString(): string },
   val?: unknown,
 ) {
   const type = (val as t.Node)?.type;