/* * Copyright (c) 2020, 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 8251535 * @summary Tests partial peeling at unsigned tests. * @library /test/lib / * @run main/othervm -Xcomp -XX:-TieredCompilation * -XX:CompileCommand=compileonly,compiler.loopopts.TestPartialPeelAtUnsignedTests::test* * compiler.loopopts.TestPartialPeelAtUnsignedTests */ package compiler.loopopts; import jdk.test.lib.Asserts; public class TestPartialPeelAtUnsignedTests { /* loop: i += 1000; if (i <u 10_000) { goto exit; } goto loop; exit: return i; C2 splits the unsigned loop exit check to have a signed exit test as cut point for partial peeling: loop: i += 1000; if (i < 10_000) { <-- This exit condition is wrong! goto exit; } if (i <u 10_000) { goto exit; } goto loop; exit: return i; */ static int test1(int i) { boolean cond = false; while (!cond) { i += 1000; // Converted to (i <u 10_000) cond = (0 <= i) && (i < 10_000); } return i; } /* Same as test1 but with a negative stride. loop: i -= 1000; if (i <u 10_000) { goto exit; } goto loop; exit: return i; Converted to: loop: i -= 1000; if (i >= 0) { <-- This exit condition is wrong! goto exit; } if (i <u 10_000) { goto exit; } goto loop; exit: return i; */ static int test2(int i) { boolean cond = false; while (!cond) { i -= 1000; cond = (0 <= i) && (i < 10_000); } return i; } /* Same as test1 but with inverted exit condition. loop: i += 1000; if (i <u 10_000) { goto loop; } goto exit; exit: return i; Converted to: loop: i += 1000; if (!(i < 10_000)) { <-- Correct exit condition. goto exit; } if (i <u 10_000) { goto loop; } goto exit; exit: return i; */ static int test3(int i) { boolean cond = true; while (cond) { i += 1000; cond = (0 <= i) && (i < 10_000); } return i; } /* Same as test2 but with inverted exit condition. loop: i -= 1000; if (i <u 10_000) { goto loop; } goto exit; exit: return i; Converted to: loop: i -= 1000; if (!(i >= 0)) { <-- Correct exit condition. goto exit; } if (i <u 10_000) { goto loop; } goto exit; exit: return i; */ static int test4(int i) { boolean cond = true; while (cond) { i -= 1000; cond = (0 <= i) && (i < 10_000); } return i; } public static void main(String[] args) { Asserts.assertEQ(test1(10_000), 704); Asserts.assertEQ(test2(-10_000), 9296); Asserts.assertEQ(test3(0), 10000); Asserts.assertEQ(test4(9999), -1); } }