1 /*
 2  * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  */
23 
24 /*
25  * @test
26  * @summary Tests that JVM_IHashCode does not cache when a SOE occurs.
27  * @comment This test runs with the interpreter such that the value is always
28  *          buffered, meaning that the identity hash code computed will be
29  *          saved in the markWord.
30  * @enablePreview
31  * @requires vm.flagless
32  * @compile HashOverflowTest.java
33  * @run main/othervm -Xint -Xss256K
34  *                   runtime.valhalla.inlinetypes.HashOverflowTest
35  */
36 
37 package runtime.valhalla.inlinetypes;
38 
39 public class HashOverflowTest {
40     private static final int N_ELEMS = 1000;
41 
42     public static void main(String[] args) {
43         Cons list = makeLargeDataStructure();
44         try {
45             System.identityHashCode(list);
46             throw new RuntimeException("expected to stack overflow when computing identity hash");
47         } catch (StackOverflowError expected) {
48             // Expected, continue execution.
49         }
50         try {
51             System.identityHashCode(list);
52             throw new RuntimeException("expected subsequent identity hash calls to also overflow");
53         } catch (StackOverflowError expected) {
54             // Expected, test passes!
55         }
56     }
57 
58     private static Cons makeLargeDataStructure() {
59         Cons prev = new Cons(N_ELEMS - 1, null);
60         for (int i = N_ELEMS - 2; i >= 0; i--) {
61             Cons curr = new Cons(i, prev);
62             prev = curr;
63         }
64         return prev;
65     }
66 
67     public static value record Cons(int x, Cons y) {}
68 }