/* * Copyright (C) 2015 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ public class Main { public static void foo(Object o, int a) { Object result = null; if (o instanceof Main) { // The compiler optimizes the type of `o` by introducing // a `HBoundType` in this block. while (a != 3) { if (a == 2) { a++; result = o; continue; } else if (willInline()) { // This block will be detected as dead after inlining. result = new Object(); continue; } result = new Object(); } // The compiler produces a phi at the back edge for `result`. // Before dead block elimination, the phi has three inputs: // result = (new Object(), new Object(), HBoundType) // // After dead block elimination, the phi has now two inputs: // result = (new Object(), HBoundType) // // Our internal data structure for linking users and inputs expect // the input index stored in that data structure to be the index // in the inputs array. So the index before dead block elimination // of the `HBoundType` would be 2. Dead block elimination must update // that index to be 1. } System.out.println(result.getClass()); } public static boolean willInline() { return false; } public static void main(String[] args) { foo(new Main(), 2); } }