1 /* |
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2 * Copyright (c) 2010, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #ifndef SHARE_GC_CMS_PROMOTIONINFO_HPP |
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26 #define SHARE_GC_CMS_PROMOTIONINFO_HPP |
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27 |
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28 #include "gc/cms/freeChunk.hpp" |
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29 |
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30 // Forward declarations |
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31 class CompactibleFreeListSpace; |
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32 |
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33 class PromotedObject { |
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34 private: |
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35 enum { |
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36 promoted_mask = right_n_bits(2), // i.e. 0x3 |
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37 displaced_mark = nth_bit(2), // i.e. 0x4 |
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38 next_mask = ~(right_n_bits(3)) // i.e. ~(0x7) |
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39 }; |
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40 |
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41 // Below, we want _narrow_next in the "higher" 32 bit slot, |
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42 // whose position will depend on endian-ness of the platform. |
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43 // This is so that there is no interference with the |
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44 // cms_free_bit occupying bit position 7 (lsb == 0) |
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45 // when we are using compressed oops; see FreeChunk::is_free(). |
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46 // We cannot move the cms_free_bit down because currently |
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47 // biased locking code assumes that age bits are contiguous |
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48 // with the lock bits. Even if that assumption were relaxed, |
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49 // the least position we could move this bit to would be |
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50 // to bit position 3, which would require 16 byte alignment. |
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51 typedef struct { |
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52 #ifdef VM_LITTLE_ENDIAN |
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53 LP64_ONLY(narrowOop _pad;) |
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54 narrowOop _narrow_next; |
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55 #else |
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56 narrowOop _narrow_next; |
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57 LP64_ONLY(narrowOop _pad;) |
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58 #endif |
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59 } Data; |
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60 |
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61 union { |
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62 intptr_t _next; |
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63 Data _data; |
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64 }; |
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65 public: |
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66 PromotedObject* next() const; |
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67 void setNext(PromotedObject* x); |
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68 inline void setPromotedMark() { |
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69 _next |= promoted_mask; |
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70 assert(!((FreeChunk*)this)->is_free(), "Error"); |
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71 } |
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72 inline bool hasPromotedMark() const { |
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73 assert(!((FreeChunk*)this)->is_free(), "Error"); |
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74 return (_next & promoted_mask) == promoted_mask; |
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75 } |
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76 inline void setDisplacedMark() { |
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77 _next |= displaced_mark; |
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78 assert(!((FreeChunk*)this)->is_free(), "Error"); |
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79 } |
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80 inline bool hasDisplacedMark() const { |
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81 assert(!((FreeChunk*)this)->is_free(), "Error"); |
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82 return (_next & displaced_mark) != 0; |
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83 } |
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84 inline void clear_next() { |
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85 _next = 0; |
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86 assert(!((FreeChunk*)this)->is_free(), "Error"); |
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87 } |
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88 debug_only(void *next_addr() { return (void *) &_next; }) |
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89 }; |
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90 |
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91 class SpoolBlock: public FreeChunk { |
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92 friend class PromotionInfo; |
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93 protected: |
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94 SpoolBlock* nextSpoolBlock; |
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95 size_t bufferSize; // number of usable words in this block |
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96 markWord* displacedHdr; // the displaced headers start here |
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97 |
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98 // Note about bufferSize: it denotes the number of entries available plus 1; |
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99 // legal indices range from 1 through BufferSize - 1. See the verification |
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100 // code verify() that counts the number of displaced headers spooled. |
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101 size_t computeBufferSize() { |
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102 return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markWord); |
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103 } |
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104 |
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105 public: |
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106 void init() { |
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107 bufferSize = computeBufferSize(); |
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108 displacedHdr = (markWord*)&displacedHdr; |
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109 nextSpoolBlock = NULL; |
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110 } |
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111 |
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112 void print_on(outputStream* st) const; |
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113 void print() const { print_on(tty); } |
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114 }; |
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115 |
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116 class PromotionInfo { |
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117 bool _tracking; // set if tracking |
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118 CompactibleFreeListSpace* _space; // the space to which this belongs |
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119 PromotedObject* _promoHead; // head of list of promoted objects |
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120 PromotedObject* _promoTail; // tail of list of promoted objects |
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121 SpoolBlock* _spoolHead; // first spooling block |
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122 SpoolBlock* _spoolTail; // last non-full spooling block or null |
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123 SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail |
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124 SpoolBlock* _spareSpool; // free spool buffer |
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125 size_t _firstIndex; // first active index in |
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126 // first spooling block (_spoolHead) |
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127 size_t _nextIndex; // last active index + 1 in last |
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128 // spooling block (_spoolTail) |
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129 private: |
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130 // ensure that spooling space exists; return true if there is spooling space |
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131 bool ensure_spooling_space_work(); |
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132 |
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133 public: |
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134 PromotionInfo() : |
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135 _tracking(0), _space(NULL), |
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136 _promoHead(NULL), _promoTail(NULL), |
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137 _spoolHead(NULL), _spoolTail(NULL), |
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138 _spareSpool(NULL), _firstIndex(1), |
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139 _nextIndex(1) {} |
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140 |
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141 bool noPromotions() const { |
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142 assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency"); |
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143 return _promoHead == NULL; |
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144 } |
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145 void startTrackingPromotions(); |
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146 void stopTrackingPromotions(); |
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147 bool tracking() const { return _tracking; } |
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148 void track(PromotedObject* trackOop); // keep track of a promoted oop |
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149 // The following variant must be used when trackOop is not fully |
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150 // initialized and has a NULL klass: |
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151 void track(PromotedObject* trackOop, Klass* klassOfOop); // keep track of a promoted oop |
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152 void setSpace(CompactibleFreeListSpace* sp) { _space = sp; } |
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153 CompactibleFreeListSpace* space() const { return _space; } |
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154 markWord nextDisplacedHeader(); // get next header & forward spool pointer |
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155 void saveDisplacedHeader(markWord hdr); |
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156 // save header and forward spool |
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157 |
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158 inline size_t refillSize() const; |
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159 |
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160 SpoolBlock* getSpoolBlock(); // return a free spooling block |
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161 inline bool has_spooling_space() { |
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162 return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex; |
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163 } |
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164 // ensure that spooling space exists |
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165 bool ensure_spooling_space() { |
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166 return has_spooling_space() || ensure_spooling_space_work(); |
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167 } |
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168 |
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169 template <typename OopClosureType> |
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170 void promoted_oops_iterate(OopClosureType* cl); |
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171 |
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172 void verify() const; |
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173 void reset() { |
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174 _promoHead = NULL; |
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175 _promoTail = NULL; |
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176 _spoolHead = NULL; |
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177 _spoolTail = NULL; |
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178 _spareSpool = NULL; |
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179 _firstIndex = 0; |
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180 _nextIndex = 0; |
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181 |
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182 } |
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183 |
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184 void print_on(outputStream* st) const; |
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185 }; |
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186 |
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187 |
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188 #endif // SHARE_GC_CMS_PROMOTIONINFO_HPP |
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