1 /*
 2  * Copyright (c) 2021, Red Hat, Inc. 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 #include "precompiled.hpp"
26 #include "gc/shared/slidingForwarding.hpp"
27 
28 #ifdef _LP64
29 HeapWord* const SlidingForwarding::UNUSED_BASE = reinterpret_cast<HeapWord*>(0x1);
30 #endif
31 
32 SlidingForwarding::SlidingForwarding(MemRegion heap)
33 #ifdef _LP64
34         : _heap_start(heap.start()),
35           _num_regions(((heap.end() - heap.start()) >> NUM_COMPRESSED_BITS) + 1),
36           _region_size_words_shift(NUM_COMPRESSED_BITS),
37           _target_base_table(NEW_C_HEAP_ARRAY(HeapWord*, _num_regions * 2, mtGC)) {
38   assert(_region_size_words_shift <= NUM_COMPRESSED_BITS, "regions must not be larger than maximum addressing bits allow");
39 #else
40   {
41 #endif
42 }
43 
44 SlidingForwarding::SlidingForwarding(MemRegion heap, size_t region_size_words_shift)
45 #ifdef _LP64
46         : _heap_start(heap.start()),
47           _num_regions(((heap.end() - heap.start()) >> region_size_words_shift) + 1),
48           _region_size_words_shift(region_size_words_shift),
49           _target_base_table(NEW_C_HEAP_ARRAY(HeapWord*, _num_regions * (ONE << NUM_REGION_BITS), mtGC)) {
50   assert(region_size_words_shift <= NUM_COMPRESSED_BITS, "regions must not be larger than maximum addressing bits allow");
51 #else
52   {
53 #endif
54 }
55 
56 SlidingForwarding::~SlidingForwarding() {
57 #ifdef _LP64
58   FREE_C_HEAP_ARRAY(HeapWord*, _target_base_table);
59 #endif
60 }
61 
62 void SlidingForwarding::clear() {
63 #ifdef _LP64
64   size_t max = _num_regions * (ONE << NUM_REGION_BITS);
65   for (size_t i = 0; i < max; i++) {
66     _target_base_table[i] = UNUSED_BASE;
67   }
68 #endif
69 }