buffer,util: refactor for performance

internal/util.js definied toInteger() and toLength() but they were only
used by buffer.js. Inlining these small functions results in a small but
statistically-significant performance gain.

PR-URL: https://github.com/nodejs/node/pull/12153
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/buffer.js

@@ -254,7 +254,9 @@ function fromArrayLike(obj) {
 }
 
 function fromArrayBuffer(obj, byteOffset, length) {
-  byteOffset = internalUtil.toInteger(byteOffset);
+  // convert byteOffset to integer
+  byteOffset = +byteOffset;
+  byteOffset = byteOffset ? Math.trunc(byteOffset) : 0;
 
   const maxLength = obj.byteLength - byteOffset;
 
@@ -264,7 +266,11 @@ function fromArrayBuffer(obj, byteOffset, length) {
   if (length === undefined) {
     length = maxLength;
   } else {
-    length = internalUtil.toLength(length);
+    // convert length to non-negative integer
+    length = +length;
+    length = length ? Math.trunc(length) : 0;
+    length = length <= 0 ? 0 : Math.min(length, Number.MAX_SAFE_INTEGER);
+
     if (length > maxLength)
       throw new RangeError("'length' is out of bounds");
   }

lib/internal/util.js

@@ -143,24 +143,6 @@ exports.cachedResult = function cachedResult(fn) {
   };
 };
 
-/*
- * Implementation of ToInteger as per ECMAScript Specification
- * Refer: http://www.ecma-international.org/ecma-262/6.0/#sec-tointeger
- */
-const toInteger = exports.toInteger = function toInteger(argument) {
-  const number = +argument;
-  return Number.isNaN(number) ? 0 : Math.trunc(number);
-};
-
-/*
- * Implementation of ToLength as per ECMAScript Specification
- * Refer: http://www.ecma-international.org/ecma-262/6.0/#sec-tolength
- */
-exports.toLength = function toLength(argument) {
-  const len = toInteger(argument);
-  return len <= 0 ? 0 : Math.min(len, Number.MAX_SAFE_INTEGER);
-};
-
 // Useful for Wrapping an ES6 Class with a constructor Function that
 // does not require the new keyword. For instance:
 //   class A { constructor(x) {this.x = x;}}

test/parallel/test-internal-util-toInteger.js

@@ -1,32 +0,0 @@
-// Flags: --expose-internals
-'use strict';
-
-require('../common');
-const assert = require('assert');
-const {toInteger} = require('internal/util');
-
-const expectZero = [
-  '0', '-0', NaN, {}, [], {'a': 'b'}, [1, 2], '0x', '0o', '0b', false,
-  '', ' ', undefined, null
-];
-expectZero.forEach(function(value) {
-  assert.strictEqual(toInteger(value), 0);
-});
-
-assert.strictEqual(toInteger(Infinity), Infinity);
-assert.strictEqual(toInteger(-Infinity), -Infinity);
-
-const expectSame = [
-  '0x100', '0o100', '0b100', 0x100, -0x100, 0o100, -0o100, 0b100, -0b100, true
-];
-expectSame.forEach(function(value) {
-  assert.strictEqual(toInteger(value), +value, `${value} is not an Integer`);
-});
-
-const expectIntegers = new Map([
-  [[1], 1], [[-1], -1], [['1'], 1], [['-1'], -1],
-  [3.14, 3], [-3.14, -3], ['3.14', 3], ['-3.14', -3],
-]);
-expectIntegers.forEach(function(expected, value) {
-  assert.strictEqual(toInteger(value), expected);
-});

test/parallel/test-internal-util-toLength.js

@@ -1,35 +0,0 @@
-// Flags: --expose-internals
-'use strict';
-
-require('../common');
-const assert = require('assert');
-const {toLength} = require('internal/util');
-const maxValue = Number.MAX_SAFE_INTEGER;
-
-const expectZero = [
-  '0', '-0', NaN, {}, [], {'a': 'b'}, [1, 2], '0x', '0o', '0b', false,
-  '', ' ', undefined, null, -1, -1.25, -1.1, -1.9, -Infinity
-];
-expectZero.forEach(function(value) {
-  assert.strictEqual(toLength(value), 0);
-});
-
-assert.strictEqual(toLength(maxValue - 1), maxValue - 1);
-assert.strictEqual(maxValue, maxValue);
-assert.strictEqual(toLength(Infinity), maxValue);
-assert.strictEqual(toLength(maxValue + 1), maxValue);
-
-
-[
-  '0x100', '0o100', '0b100', 0x100, -0x100, 0o100, -0o100, 0b100, -0b100, true
-].forEach(function(value) {
-  assert.strictEqual(toLength(value), +value > 0 ? +value : 0);
-});
-
-const expectIntegers = new Map([
-  [[1], 1], [[-1], 0], [['1'], 1], [['-1'], 0],
-  [3.14, 3], [-3.14, 0], ['3.14', 3], ['-3.14', 0],
-]);
-expectIntegers.forEach(function(expected, value) {
-  assert.strictEqual(toLength(value), expected);
-});