// Copyright 2012 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following // disclaimer in the documentation and/or other materials provided // with the distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // Flags: --allow-natives-syntax --opt // The original problem from the bug: In the example below SMI check for b // generated for inlining of equals invocation (marked with (*)) will be hoisted // out of the loop across the typeof b === "object" condition and cause an // immediate deopt. Another problem here is that no matter how many time we // deopt and reopt we will continue to produce the wrong code. // // The fix is to notice when a deopt and subsequent reopt doesn't find // additional type information, indicating that optimistic LICM should be // disabled during compilation. function eq(a, b) { if (typeof b === "object") { return b.equals(a); // (*) } return a === b; } Object.prototype.equals = function (other) { return (this === other); }; function test() { for (var i = 0; !eq(i, 10); i++) ; } %PrepareFunctionForOptimization(test); eq({}, {}); eq({}, {}); eq(1, 1); eq(1, 1); test(); %OptimizeFunctionOnNextCall(test); test(); %PrepareFunctionForOptimization(test); %OptimizeFunctionOnNextCall(test); // Second compilation should have noticed that LICM wasn't a good idea, and now // function should no longer deopt when called. test(); assertOptimized(test);