Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 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 | |
| 40 | function eq(a, b) { |
| 41 | if (typeof b === "object") { |
| 42 | return b.equals(a); // (*) |
| 43 | } |
| 44 | return a === b; |
| 45 | } |
| 46 | |
| 47 | Object.prototype.equals = function (other) { |
| 48 | return (this === other); |
| 49 | }; |
| 50 | |
| 51 | function test() { |
| 52 | for (var i = 0; !eq(i, 10); i++) |
| 53 | ; |
| 54 | } |
| 55 | |
| 56 | eq({}, {}); |
| 57 | eq({}, {}); |
| 58 | eq(1, 1); |
| 59 | eq(1, 1); |
| 60 | test(); |
| 61 | %OptimizeFunctionOnNextCall(test); |
| 62 | test(); |
| 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. |
| 66 | test(); |
| 67 | assertOptimized(test); |