1// Copyright 2012 the V8 project authors. All rights reserved. 2// Redistribution and use in source and binary forms, with or without 3// modification, are permitted provided that the following conditions are 4// met: 5// 6// * Redistributions of source code must retain the above copyright 7// notice, this list of conditions and the following disclaimer. 8// * Redistributions in binary form must reproduce the above 9// copyright notice, this list of conditions and the following 10// disclaimer in the documentation and/or other materials provided 11// with the distribution. 12// * Neither the name of Google Inc. nor the names of its 13// contributors may be used to endorse or promote products derived 14// from this software without specific prior written permission. 15// 16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28// Flags: --allow-natives-syntax 29 30// The original problem from the bug: In the example below SMI check for b 31// generated for inlining of equals invocation (marked with (*)) will be hoisted 32// out of the loop across the typeof b === "object" condition and cause an 33// immediate deopt. Another problem here is that no matter how many time we 34// deopt and reopt we will continue to produce the wrong code. 35// 36// The fix is to notice when a deopt and subsequent reopt doesn't find 37// additional type information, indicating that optimistic LICM should be 38// disabled during compilation. 39 40function eq(a, b) { 41 if (typeof b === "object") { 42 return b.equals(a); // (*) 43 } 44 return a === b; 45} 46 47Object.prototype.equals = function (other) { 48 return (this === other); 49}; 50 51function test() { 52 for (var i = 0; !eq(i, 10); i++) 53 ; 54} 55 56eq({}, {}); 57eq({}, {}); 58eq(1, 1); 59eq(1, 1); 60test(); 61%OptimizeFunctionOnNextCall(test); 62test(); 63%OptimizeFunctionOnNextCall(test); 64// Second compilation should have noticed that LICM wasn't a good idea, and now 65// function should no longer deopt when called. 66test(); 67assertOptimized(test); 68