/* * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /** * @test * @bug 8360561 * @summary Ranges can be proven to be disjoint but not orderable (thanks to unsigned range) * Comparing such values in such range with != should always be true. * @run main/othervm -Xbatch * -XX:CompileCommand=compileonly,compiler.igvn.CmpDisjointButNonOrderedRanges2::* * -XX:-TieredCompilation * -XX:+UnlockExperimentalVMOptions * -XX:PerMethodTrapLimit=0 * compiler.igvn.CmpDisjointButNonOrderedRanges2 * @run main compiler.igvn.CmpDisjointButNonOrderedRanges2 */ package compiler.igvn; public class CmpDisjointButNonOrderedRanges2 { int array[]; void test() { int val = 2; for (int i = 0; i < 10; i++) { // val = 2 \/ val = -12 => val \in [-12, 2] as a signed value // but [2, bitwise_cast_uint(-12)] as unsigned // So 0 is not possible. if (val != 0) { return; } // val is tighten to be in the meet (so Hotspot's join) of [0, 0] and [2, bitwise_cast_uint(-12)] // that is bottom (Hotspot's top). Data is dead, control needs to be dead as well. for (int j = 0; j < 10; j++) { array[1] = val; val = -12; } } } static public void main(String[] args) { var c = new CmpDisjointButNonOrderedRanges2(); for (int i = 0; i < 1000; ++i) { c.test(); for (int j = 0; j < 100; ++j) { } } } }