1 /*
 2  * Copyright (c) 2017, 2025, 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
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22  */
23 
24 #include "gc/shared/preservedMarks.inline.hpp"
25 #include "gc/shared/fullGCForwarding.inline.hpp"
26 #include "oops/oop.inline.hpp"
27 #include "unittest.hpp"
28 
29 static markWord originalMark() { return markWord(markWord::lock_mask_in_place); }
30 static markWord changedMark()  { return markWord(0x4711); }
31 
32 #define ASSERT_MARK_WORD_EQ(a, b) ASSERT_EQ((a).value(), (b).value())
33 
34 TEST_VM(PreservedMarks, iterate_and_restore) {
35   PreservedMarks pm;
36 
37   HeapWord fakeheap[32] = { nullptr };
38   HeapWord* heap = align_up(fakeheap, 8 * sizeof(HeapWord));
39   FullGCForwarding::initialize(MemRegion(&heap[0], &heap[16]));
40 
41   oop o1 = cast_to_oop(&heap[0]); o1->set_mark(originalMark());
42   oop o2 = cast_to_oop(&heap[2]); o2->set_mark(originalMark());
43   oop o3 = cast_to_oop(&heap[4]); o3->set_mark(originalMark());
44   oop o4 = cast_to_oop(&heap[6]); o4->set_mark(originalMark());
45 
46   // Make sure initial marks are correct.
47   ASSERT_MARK_WORD_EQ(o1->mark(), originalMark());
48   ASSERT_MARK_WORD_EQ(o2->mark(), originalMark());
49   ASSERT_MARK_WORD_EQ(o3->mark(), originalMark());
50   ASSERT_MARK_WORD_EQ(o4->mark(), originalMark());
51 
52   // Change the marks and verify change.
53   o1->set_mark(changedMark());
54   o2->set_mark(changedMark());
55   ASSERT_MARK_WORD_EQ(o1->mark(), changedMark());
56   ASSERT_MARK_WORD_EQ(o2->mark(), changedMark());
57 
58   // Push o1 and o2 to have their marks preserved.
59   pm.push_if_necessary(o1, o1->mark());
60   pm.push_if_necessary(o2, o2->mark());
61 
62   // Fake a move from o1->o3 and o2->o4.
63   FullGCForwarding::forward_to(o1, o3);
64   FullGCForwarding::forward_to(o2, o4);
65   ASSERT_EQ(FullGCForwarding::forwardee(o1), o3);
66   ASSERT_EQ(FullGCForwarding::forwardee(o2), o4);
67   // Adjust will update the PreservedMarks stack to
68   // make sure the mark is updated at the new location.
69   pm.adjust_during_full_gc();
70 
71   // Restore all preserved and verify that the changed
72   // mark is now present at o3 and o4.
73   pm.restore();
74   ASSERT_MARK_WORD_EQ(o3->mark(), changedMark());
75   ASSERT_MARK_WORD_EQ(o4->mark(), changedMark());
76 }