1 /*
 2  * Copyright (c) 2024, 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 package compiler.gcbarriers;
25 
26 import compiler.lib.ir_framework.*;
27 import java.lang.invoke.VarHandle;
28 import java.lang.invoke.MethodHandles;
29 
30 /**
31  * @test
32  * @summary Test that the expanded size of ZGC barriers is taken into account in
33  *          C2's loop unrolling heuristics so that over-unrolling is avoided.
34  *          The tests use volatile memory accesses to prevent C2 from simply
35  *          optimizing them away.
36  * @library /test/lib /
37  * @requires vm.gc.Z
38  * @run driver compiler.gcbarriers.TestZGCUnrolling
39  */
40 
41 public class TestZGCUnrolling {
42 
43     static class Outer {
44         Object f;
45     }
46 
47     static final VarHandle fVarHandle;
48     static {
49         MethodHandles.Lookup l = MethodHandles.lookup();
50         try {
51             fVarHandle = l.findVarHandle(Outer.class, "f", Object.class);
52         } catch (Exception e) {
53             throw new Error(e);
54         }
55     }
56 
57     public static void main(String[] args) {
58         TestFramework.runWithFlags("-XX:+UseZGC", "-XX:LoopUnrollLimit=24");
59     }
60 
61     @Test
62     @IR(counts = {IRNode.STORE_P, "1"})

63     public static void testNoUnrolling(Outer o, Object o1) {
64         for (int i = 0; i < 64; i++) {
65             fVarHandle.setVolatile(o, o1);
66         }
67     }
68 
69     @Run(test = {"testNoUnrolling"})
70     void run() {
71         testNoUnrolling(new Outer(), new Object());
72     }
73 }
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