v8/test/mjsunit/compiler/number-multiply.js

// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Flags: --allow-natives-syntax --opt

// Test the extreme case where -0 is produced by rounding errors.
(function() {
  function bar(x) {
    return 1e-308 * x;
  }
  bar(1);

  function foo() {
    return Object.is(-0, bar(-1e-308));
  }

  %PrepareFunctionForOptimization(foo);
  assertTrue(foo());
  assertTrue(foo());
  %OptimizeFunctionOnNextCall(foo);
  assertTrue(foo());
})();

// Test that multiplication of integer by 0 produces the correct results.
(function() {
  function foo(x) {
    return 0 * Math.round(x);
  }

  %PrepareFunctionForOptimization(foo);
  assertEquals(0, foo(0.1));
  assertEquals(-0, foo(-0.1));
  assertEquals(NaN, foo(NaN));
  assertEquals(NaN, foo(Infinity));
  assertEquals(NaN, foo(-Infinity));
  %OptimizeFunctionOnNextCall(foo);
  assertEquals(0, foo(0.1));
  assertEquals(-0, foo(-0.1));
  assertEquals(NaN, foo(NaN));
  assertEquals(NaN, foo(Infinity));
  assertEquals(NaN, foo(-Infinity));
})();

// Test that multiplication properly preserves -0 and NaN, and doesn't
// cut it short incorrectly.
(function() {
  function foo(x, y) {
    x = Math.sign(x);
    y = Math.sign(y);
    return Math.min(x * y, 0);
  }

  %PrepareFunctionForOptimization(foo);
  assertEquals(0, foo(1, 0));
  assertEquals(-0, foo(1, -0));
  assertEquals(NaN, foo(NaN, -0));
  %OptimizeFunctionOnNextCall(foo);
  assertEquals(0, foo(1, 0));
  assertEquals(-0, foo(1, -0));
  assertEquals(NaN, foo(NaN, -0));
})();