// Copyright 2013 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 // Presents negative opportunities for dead loop removal. function loop1() { while (true) return; } function loop2() { var i = 0; while (i++ < 10) ; return i; // value of {i} escapes. // can only remove the loop with induction variable analysis. } function loop3() { var i = 0; for (; i < 10; i++) ; return i; // value of {i} escapes. // can only remove the loop with induction variable analysis. } function loop4() { var a = 0; for (var i = 0; i < 10; i++) a++; return a; // value of {a} escapes. // can only remove the loop with induction variable analysis. } function loop5() { var a = new Int32Array(4), sum = 0; for (var i = 0; i < a.length; i++) { sum += a[i]; } return sum; // {sum} escapes. // can only remove the loop by figuring out that all elements of {a} are 0. } function loop6(a) { for (var i = 0; i < a; i++) ; // implicit a.valueOf(). // can only remove the loop by guarding on the type of a. } function loop7(a) { for (var i = 0; i < 10; i++) a.toString(); // unknown side-effect on a. // can only remove the loop by guarding on the type of a. } function loop8(a) { for (var i = 0; i < 10; i++) a.valueOf(); // unknown side-effect on a. // can only remove the loop by guarding on the type of a. } var no_params_loops = [loop1, loop2, loop3, loop4, loop5, loop6]; var params_loops = [loop6, loop7, loop8]; for (var i = 0; i < no_params_loops.length; i++) { var f = no_params_loops[i]; %PrepareFunctionForOptimization(f); f(); f(); f(); %OptimizeFunctionOnNextCall(f); f(); } for (var i = 0; i < params_loops.length; i++) { var f = params_loops[i]; %PrepareFunctionForOptimization(f); f(3); f(7); f(11); %OptimizeFunctionOnNextCall(f); f(9); }