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1 /*
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2 * Copyright 2001-2005 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 # include "incls/_precompiled.incl"
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26 # include "incls/_objectStartArray.cpp.incl"
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27
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28 void ObjectStartArray::initialize(MemRegion reserved_region) {
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29 // We're based on the assumption that we use the same
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30 // size blocks as the card table.
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31 assert((int)block_size == (int)CardTableModRefBS::card_size, "Sanity");
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32 assert((int)block_size <= 512, "block_size must be less than or equal to 512");
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33
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34 // Calculate how much space must be reserved
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35 _reserved_region = reserved_region;
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36
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37 size_t bytes_to_reserve = reserved_region.word_size() / block_size_in_words;
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38 assert(bytes_to_reserve > 0, "Sanity");
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39
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40 bytes_to_reserve =
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41 align_size_up(bytes_to_reserve, os::vm_allocation_granularity());
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42
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43 // Do not use large-pages for the backing store. The one large page region
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44 // will be used for the heap proper.
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45 ReservedSpace backing_store(bytes_to_reserve);
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46 if (!backing_store.is_reserved()) {
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47 vm_exit_during_initialization("Could not reserve space for ObjectStartArray");
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48 }
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49
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50 // We do not commit any memory initially
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51 if (!_virtual_space.initialize(backing_store, 0)) {
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52 vm_exit_during_initialization("Could not commit space for ObjectStartArray");
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53 }
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54
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55 _raw_base = (jbyte*)_virtual_space.low_boundary();
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56 if (_raw_base == NULL) {
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57 vm_exit_during_initialization("Could not get raw_base address");
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58 }
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59
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60 _offset_base = _raw_base - (size_t(reserved_region.start()) >> block_shift);
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61
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62 _covered_region.set_start(reserved_region.start());
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63 _covered_region.set_word_size(0);
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64
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65 _blocks_region.set_start((HeapWord*)_raw_base);
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66 _blocks_region.set_word_size(0);
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67 }
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68
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69 void ObjectStartArray::set_covered_region(MemRegion mr) {
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70 assert(_reserved_region.contains(mr), "MemRegion outside of reserved space");
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71 assert(_reserved_region.start() == mr.start(), "Attempt to move covered region");
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72
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73 HeapWord* low_bound = mr.start();
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74 HeapWord* high_bound = mr.end();
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75 assert((uintptr_t(low_bound) & (block_size - 1)) == 0, "heap must start at block boundary");
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76 assert((uintptr_t(high_bound) & (block_size - 1)) == 0, "heap must end at block boundary");
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77
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78 size_t requested_blocks_size_in_bytes = mr.word_size() / block_size_in_words;
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79
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80 // Only commit memory in page sized chunks
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81 requested_blocks_size_in_bytes =
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82 align_size_up(requested_blocks_size_in_bytes, os::vm_page_size());
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83
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84 _covered_region = mr;
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85
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86 size_t current_blocks_size_in_bytes = _blocks_region.byte_size();
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87
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88 if (requested_blocks_size_in_bytes > current_blocks_size_in_bytes) {
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89 // Expand
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90 size_t expand_by = requested_blocks_size_in_bytes - current_blocks_size_in_bytes;
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91 if (!_virtual_space.expand_by(expand_by)) {
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92 vm_exit_out_of_memory(expand_by, "object start array expansion");
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93 }
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94 // Clear *only* the newly allocated region
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95 memset(_blocks_region.end(), clean_block, expand_by);
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96 }
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97
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98 if (requested_blocks_size_in_bytes < current_blocks_size_in_bytes) {
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99 // Shrink
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100 size_t shrink_by = current_blocks_size_in_bytes - requested_blocks_size_in_bytes;
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101 _virtual_space.shrink_by(shrink_by);
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102 }
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103
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104 _blocks_region.set_word_size(requested_blocks_size_in_bytes / sizeof(HeapWord));
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105
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106 assert(requested_blocks_size_in_bytes % sizeof(HeapWord) == 0, "Block table not expanded in word sized increment");
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107 assert(requested_blocks_size_in_bytes == _blocks_region.byte_size(), "Sanity");
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108 assert(block_for_addr(low_bound) == &_raw_base[0], "Checking start of map");
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109 assert(block_for_addr(high_bound-1) <= &_raw_base[_blocks_region.byte_size()-1], "Checking end of map");
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110 }
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111
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112 void ObjectStartArray::reset() {
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113 memset(_blocks_region.start(), clean_block, _blocks_region.byte_size());
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114 }
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115
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116
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117 bool ObjectStartArray::object_starts_in_range(HeapWord* start_addr,
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118 HeapWord* end_addr) const {
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119 assert(start_addr <= end_addr, "range is wrong");
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120 if (start_addr > end_addr) {
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121 return false;
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122 }
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123
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124 jbyte* start_block = block_for_addr(start_addr);
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125 jbyte* end_block = block_for_addr(end_addr);
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126
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127 for (jbyte* block = start_block; block <= end_block; block++) {
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128 if (*block != clean_block) {
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129 return true;
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130 }
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131 }
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132 // No object starts in this slice; verify this using
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133 // more traditional methods:
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134 assert(object_start(end_addr - 1) <= start_addr,
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135 "Oops an object does start in this slice?");
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136 return false;
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137 }
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