1 /*
2 * Copyright (c) 2018, 2023, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2020, Red Hat, Inc. and/or its affiliates.
4 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 *
7 * This code is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 only, as
9 * published by the Free Software Foundation.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 *
25 */
26
27 #include "precompiled.hpp"
28 #include "gc/shenandoah/shenandoahMarkBitMap.inline.hpp"
29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
30 #include "utilities/globalDefinitions.hpp"
31
32 ShenandoahMarkBitMap::ShenandoahMarkBitMap(MemRegion heap, MemRegion storage) :
33 _shift(LogMinObjAlignment),
34 _covered(heap),
35 _map((BitMap::bm_word_t*) storage.start()),
36 _size((heap.word_size() * 2) >> _shift) {
37 }
38
39 size_t ShenandoahMarkBitMap::compute_size(size_t heap_size) {
40 return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
41 }
42
43 size_t ShenandoahMarkBitMap::mark_distance() {
44 return MinObjAlignmentInBytes * BitsPerByte / 2;
45 }
46
47 bool ShenandoahMarkBitMap::is_bitmap_clear_range(const HeapWord* start, const HeapWord* end) const {
48 // Similar to get_next_marked_addr(), without assertion.
49 // Round addr up to a possible object boundary to be safe.
50 if (start == end) {
51 return true;
52 }
53 size_t const addr_offset = address_to_index(align_up(start, HeapWordSize << LogMinObjAlignment));
54 size_t const limit_offset = address_to_index(end);
55 size_t const next_offset = get_next_one_offset(addr_offset, limit_offset);
56 HeapWord* result = index_to_address(next_offset);
57 return (result == end);
58 }
59
60
61 HeapWord* ShenandoahMarkBitMap::get_next_marked_addr(const HeapWord* addr,
62 const HeapWord* limit) const {
63 #ifdef ASSERT
64 ShenandoahHeap* heap = ShenandoahHeap::heap();
65 ShenandoahHeapRegion* r = heap->heap_region_containing(addr);
66 ShenandoahMarkingContext* ctx = heap->marking_context();
67 HeapWord* tams = ctx->top_at_mark_start(r);
68 assert(limit != nullptr, "limit must not be null");
69 assert(limit <= r->top(), "limit must be less than top");
70 assert(addr <= tams, "addr must be less than TAMS");
71 #endif
72
73 // Round addr up to a possible object boundary to be safe.
74 size_t const addr_offset = address_to_index(align_up(addr, HeapWordSize << LogMinObjAlignment));
75 size_t const limit_offset = address_to_index(limit);
76 size_t const nextOffset = get_next_one_offset(addr_offset, limit_offset);
77 return index_to_address(nextOffset);
78 }
79
80 void ShenandoahMarkBitMap::clear_range_within_word(idx_t beg, idx_t end) {
81 // With a valid range (beg <= end), this test ensures that end != 0, as
82 // required by inverted_bit_mask_for_range. Also avoids an unnecessary write.
83 if (beg != end) {
84 bm_word_t mask = inverted_bit_mask_for_range(beg, end);
85 *word_addr(beg) &= mask;
86 }
87 }
88
89 void ShenandoahMarkBitMap::clear_range(idx_t beg, idx_t end) {
90 verify_range(beg, end);
91
92 idx_t beg_full_word = to_words_align_up(beg);
93 idx_t end_full_word = to_words_align_down(end);
94
95 if (beg_full_word < end_full_word) {
96 // The range includes at least one full word.
97 clear_range_within_word(beg, bit_index(beg_full_word));
98 clear_range_of_words(beg_full_word, end_full_word);
99 clear_range_within_word(bit_index(end_full_word), end);
100 } else {
101 // The range spans at most 2 partial words.
102 idx_t boundary = MIN2(bit_index(beg_full_word), end);
103 clear_range_within_word(beg, boundary);
104 clear_range_within_word(boundary, end);
105 }
106 }
107
108 bool ShenandoahMarkBitMap::is_small_range_of_words(idx_t beg_full_word, idx_t end_full_word) {
109 // There is little point to call large version on small ranges.
110 // Need to check carefully, keeping potential idx_t over/underflow in mind,
111 // because beg_full_word > end_full_word can occur when beg and end are in
112 // the same word.
113 // The threshold should be at least one word.
114 STATIC_ASSERT(small_range_words >= 1);
115 return beg_full_word + small_range_words >= end_full_word;
116 }
117
118
119 void ShenandoahMarkBitMap::clear_large_range(idx_t beg, idx_t end) {
120 verify_range(beg, end);
121
122 idx_t beg_full_word = to_words_align_up(beg);
123 idx_t end_full_word = to_words_align_down(end);
124
125 if (is_small_range_of_words(beg_full_word, end_full_word)) {
126 clear_range(beg, end);
127 return;
128 }
129
130 // The range includes at least one full word.
131 clear_range_within_word(beg, bit_index(beg_full_word));
132 clear_large_range_of_words(beg_full_word, end_full_word);
133 clear_range_within_word(bit_index(end_full_word), end);
134 }
135
136 void ShenandoahMarkBitMap::clear_range_large(MemRegion mr) {
137 MemRegion intersection = mr.intersection(_covered);
138 assert(!intersection.is_empty(),
139 "Given range from " PTR_FORMAT " to " PTR_FORMAT " is completely outside the heap",
140 p2i(mr.start()), p2i(mr.end()));
141 // convert address range into offset range
142 size_t beg = address_to_index(intersection.start());
143 size_t end = address_to_index(intersection.end());
144 clear_large_range(beg, end);
145 }
146
147 #ifdef ASSERT
148 void ShenandoahMarkBitMap::check_mark(HeapWord* addr) const {
149 assert(ShenandoahHeap::heap()->is_in(addr),
150 "Trying to access bitmap " PTR_FORMAT " for address " PTR_FORMAT " not in the heap.",
151 p2i(this), p2i(addr));
152 }
153
154 void ShenandoahMarkBitMap::verify_index(idx_t bit) const {
155 assert(bit < _size,
156 "BitMap index out of bounds: " SIZE_FORMAT " >= " SIZE_FORMAT,
157 bit, _size);
158 }
159
160 void ShenandoahMarkBitMap::verify_limit(idx_t bit) const {
161 assert(bit <= _size,
162 "BitMap limit out of bounds: " SIZE_FORMAT " > " SIZE_FORMAT,
163 bit, _size);
164 }
165
166 void ShenandoahMarkBitMap::verify_range(idx_t beg, idx_t end) const {
167 assert(beg <= end,
168 "BitMap range error: " SIZE_FORMAT " > " SIZE_FORMAT, beg, end);
169 verify_limit(end);
170 }
171 #endif