1 /* |
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2 * Copyright (c) 2010, 2018, 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 #include "precompiled.hpp" |
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26 #include "gc/cms/compactibleFreeListSpace.hpp" |
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27 #include "gc/cms/promotionInfo.hpp" |
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28 #include "gc/shared/genOopClosures.hpp" |
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29 #include "oops/compressedOops.inline.hpp" |
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30 #include "oops/markWord.inline.hpp" |
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31 #include "oops/oop.inline.hpp" |
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32 |
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33 ///////////////////////////////////////////////////////////////////////// |
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34 //// PromotionInfo |
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35 ///////////////////////////////////////////////////////////////////////// |
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36 |
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37 |
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38 PromotedObject* PromotedObject::next() const { |
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39 assert(!((FreeChunk*)this)->is_free(), "Error"); |
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40 PromotedObject* res; |
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41 if (UseCompressedOops) { |
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42 // The next pointer is a compressed oop stored in the top 32 bits |
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43 res = (PromotedObject*)CompressedOops::decode(_data._narrow_next); |
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44 } else { |
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45 res = (PromotedObject*)(_next & next_mask); |
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46 } |
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47 assert(oopDesc::is_oop_or_null(oop(res), true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(res))); |
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48 return res; |
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49 } |
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50 |
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51 inline void PromotedObject::setNext(PromotedObject* x) { |
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52 assert(((intptr_t)x & ~next_mask) == 0, "Conflict in bit usage, " |
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53 "or insufficient alignment of objects"); |
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54 if (UseCompressedOops) { |
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55 assert(_data._narrow_next == 0, "Overwrite?"); |
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56 _data._narrow_next = CompressedOops::encode(oop(x)); |
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57 } else { |
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58 _next |= (intptr_t)x; |
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59 } |
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60 assert(!((FreeChunk*)this)->is_free(), "Error"); |
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61 } |
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62 |
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63 // Return the next displaced header, incrementing the pointer and |
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64 // recycling spool area as necessary. |
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65 markWord PromotionInfo::nextDisplacedHeader() { |
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66 assert(_spoolHead != NULL, "promotionInfo inconsistency"); |
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67 assert(_spoolHead != _spoolTail || _firstIndex < _nextIndex, |
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68 "Empty spool space: no displaced header can be fetched"); |
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69 assert(_spoolHead->bufferSize > _firstIndex, "Off by one error at head?"); |
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70 markWord hdr = _spoolHead->displacedHdr[_firstIndex]; |
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71 // Spool forward |
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72 if (++_firstIndex == _spoolHead->bufferSize) { // last location in this block |
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73 // forward to next block, recycling this block into spare spool buffer |
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74 SpoolBlock* tmp = _spoolHead->nextSpoolBlock; |
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75 assert(_spoolHead != _spoolTail, "Spooling storage mix-up"); |
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76 _spoolHead->nextSpoolBlock = _spareSpool; |
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77 _spareSpool = _spoolHead; |
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78 _spoolHead = tmp; |
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79 _firstIndex = 1; |
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80 NOT_PRODUCT( |
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81 if (_spoolHead == NULL) { // all buffers fully consumed |
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82 assert(_spoolTail == NULL && _nextIndex == 1, |
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83 "spool buffers processing inconsistency"); |
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84 } |
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85 ) |
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86 } |
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87 return hdr; |
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88 } |
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89 |
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90 void PromotionInfo::track(PromotedObject* trackOop) { |
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91 track(trackOop, oop(trackOop)->klass()); |
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92 } |
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93 |
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94 void PromotionInfo::track(PromotedObject* trackOop, Klass* klassOfOop) { |
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95 // make a copy of header as it may need to be spooled |
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96 markWord mark = oop(trackOop)->mark_raw(); |
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97 trackOop->clear_next(); |
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98 if (mark.must_be_preserved_for_cms_scavenge(klassOfOop)) { |
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99 // save non-prototypical header, and mark oop |
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100 saveDisplacedHeader(mark); |
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101 trackOop->setDisplacedMark(); |
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102 } else { |
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103 // we'd like to assert something like the following: |
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104 // assert(mark == markWord::prototype(), "consistency check"); |
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105 // ... but the above won't work because the age bits have not (yet) been |
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106 // cleared. The remainder of the check would be identical to the |
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107 // condition checked in must_be_preserved() above, so we don't really |
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108 // have anything useful to check here! |
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109 } |
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110 if (_promoTail != NULL) { |
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111 assert(_promoHead != NULL, "List consistency"); |
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112 _promoTail->setNext(trackOop); |
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113 _promoTail = trackOop; |
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114 } else { |
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115 assert(_promoHead == NULL, "List consistency"); |
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116 _promoHead = _promoTail = trackOop; |
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117 } |
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118 // Mask as newly promoted, so we can skip over such objects |
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119 // when scanning dirty cards |
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120 assert(!trackOop->hasPromotedMark(), "Should not have been marked"); |
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121 trackOop->setPromotedMark(); |
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122 } |
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123 |
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124 // Save the given displaced header, incrementing the pointer and |
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125 // obtaining more spool area as necessary. |
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126 void PromotionInfo::saveDisplacedHeader(markWord hdr) { |
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127 assert(_spoolHead != NULL && _spoolTail != NULL, |
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128 "promotionInfo inconsistency"); |
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129 assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?"); |
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130 _spoolTail->displacedHdr[_nextIndex] = hdr; |
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131 // Spool forward |
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132 if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block |
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133 // get a new spooling block |
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134 assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list"); |
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135 _splice_point = _spoolTail; // save for splicing |
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136 _spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail |
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137 _spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ... |
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138 // ... but will attempt filling before next promotion attempt |
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139 _nextIndex = 1; |
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140 } |
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141 } |
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142 |
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143 // Ensure that spooling space exists. Return false if spooling space |
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144 // could not be obtained. |
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145 bool PromotionInfo::ensure_spooling_space_work() { |
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146 assert(!has_spooling_space(), "Only call when there is no spooling space"); |
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147 // Try and obtain more spooling space |
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148 SpoolBlock* newSpool = getSpoolBlock(); |
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149 assert(newSpool == NULL || |
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150 (newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL), |
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151 "getSpoolBlock() sanity check"); |
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152 if (newSpool == NULL) { |
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153 return false; |
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154 } |
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155 _nextIndex = 1; |
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156 if (_spoolTail == NULL) { |
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157 _spoolTail = newSpool; |
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158 if (_spoolHead == NULL) { |
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159 _spoolHead = newSpool; |
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160 _firstIndex = 1; |
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161 } else { |
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162 assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL, |
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163 "Splice point invariant"); |
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164 // Extra check that _splice_point is connected to list |
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165 #ifdef ASSERT |
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166 { |
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167 SpoolBlock* blk = _spoolHead; |
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168 for (; blk->nextSpoolBlock != NULL; |
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169 blk = blk->nextSpoolBlock); |
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170 assert(blk != NULL && blk == _splice_point, |
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171 "Splice point incorrect"); |
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172 } |
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173 #endif // ASSERT |
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174 _splice_point->nextSpoolBlock = newSpool; |
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175 } |
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176 } else { |
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177 assert(_spoolHead != NULL, "spool list consistency"); |
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178 _spoolTail->nextSpoolBlock = newSpool; |
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179 _spoolTail = newSpool; |
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180 } |
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181 return true; |
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182 } |
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183 |
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184 // Get a free spool buffer from the free pool, getting a new block |
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185 // from the heap if necessary. |
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186 SpoolBlock* PromotionInfo::getSpoolBlock() { |
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187 SpoolBlock* res; |
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188 if ((res = _spareSpool) != NULL) { |
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189 _spareSpool = _spareSpool->nextSpoolBlock; |
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190 res->nextSpoolBlock = NULL; |
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191 } else { // spare spool exhausted, get some from heap |
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192 res = (SpoolBlock*)(space()->allocateScratch(refillSize())); |
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193 if (res != NULL) { |
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194 res->init(); |
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195 } |
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196 } |
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197 assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition"); |
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198 return res; |
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199 } |
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200 |
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201 void PromotionInfo::startTrackingPromotions() { |
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202 assert(noPromotions(), "sanity"); |
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203 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex, |
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204 "spooling inconsistency?"); |
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205 _firstIndex = _nextIndex = 1; |
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206 _tracking = true; |
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207 } |
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208 |
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209 void PromotionInfo::stopTrackingPromotions() { |
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210 assert(noPromotions(), "we should have torn down the lists by now"); |
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211 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex, |
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212 "spooling inconsistency?"); |
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213 _firstIndex = _nextIndex = 1; |
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214 _tracking = false; |
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215 } |
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216 |
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217 // When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex> |
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218 // points to the next slot available for filling. |
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219 // The set of slots holding displaced headers are then all those in the |
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220 // right-open interval denoted by: |
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221 // |
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222 // [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> ) |
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223 // |
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224 // When _spoolTail is NULL, then the set of slots with displaced headers |
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225 // is all those starting at the slot <_spoolHead, _firstIndex> and |
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226 // going up to the last slot of last block in the linked list. |
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227 // In this latter case, _splice_point points to the tail block of |
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228 // this linked list of blocks holding displaced headers. |
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229 void PromotionInfo::verify() const { |
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230 // Verify the following: |
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231 // 1. the number of displaced headers matches the number of promoted |
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232 // objects that have displaced headers |
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233 // 2. each promoted object lies in this space |
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234 debug_only( |
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235 PromotedObject* junk = NULL; |
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236 assert(junk->next_addr() == (void*)(oop(junk)->mark_addr_raw()), |
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237 "Offset of PromotedObject::_next is expected to align with " |
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238 " the OopDesc::_mark within OopDesc"); |
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239 ) |
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240 // FIXME: guarantee???? |
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241 guarantee(_spoolHead == NULL || _spoolTail != NULL || |
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242 _splice_point != NULL, "list consistency"); |
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243 guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency"); |
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244 // count the number of objects with displaced headers |
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245 size_t numObjsWithDisplacedHdrs = 0; |
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246 for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) { |
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247 guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment"); |
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248 // the last promoted object may fail the mark() != NULL test of is_oop(). |
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249 guarantee(curObj->next() == NULL || oopDesc::is_oop(oop(curObj)), "must be an oop"); |
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250 if (curObj->hasDisplacedMark()) { |
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251 numObjsWithDisplacedHdrs++; |
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252 } |
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253 } |
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254 // Count the number of displaced headers |
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255 size_t numDisplacedHdrs = 0; |
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256 for (SpoolBlock* curSpool = _spoolHead; |
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257 curSpool != _spoolTail && curSpool != NULL; |
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258 curSpool = curSpool->nextSpoolBlock) { |
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259 // the first entry is just a self-pointer; indices 1 through |
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260 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots). |
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261 guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr, |
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262 "first entry of displacedHdr should be self-referential"); |
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263 numDisplacedHdrs += curSpool->bufferSize - 1; |
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264 } |
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265 guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0), |
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266 "internal consistency"); |
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267 guarantee(_spoolTail != NULL || _nextIndex == 1, |
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268 "Inconsistency between _spoolTail and _nextIndex"); |
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269 // We overcounted (_firstIndex-1) worth of slots in block |
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270 // _spoolHead and we undercounted (_nextIndex-1) worth of |
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271 // slots in block _spoolTail. We make an appropriate |
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272 // adjustment by subtracting the first and adding the |
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273 // second: - (_firstIndex - 1) + (_nextIndex - 1) |
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274 numDisplacedHdrs += (_nextIndex - _firstIndex); |
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275 guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count"); |
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276 } |
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277 |
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278 void PromotionInfo::print_on(outputStream* st) const { |
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279 SpoolBlock* curSpool = NULL; |
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280 size_t i = 0; |
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281 st->print_cr(" start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")", |
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282 _firstIndex, _nextIndex); |
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283 for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL; |
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284 curSpool = curSpool->nextSpoolBlock) { |
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285 curSpool->print_on(st); |
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286 st->print_cr(" active "); |
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287 i++; |
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288 } |
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289 for (curSpool = _spoolTail; curSpool != NULL; |
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290 curSpool = curSpool->nextSpoolBlock) { |
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291 curSpool->print_on(st); |
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292 st->print_cr(" inactive "); |
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293 i++; |
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294 } |
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295 for (curSpool = _spareSpool; curSpool != NULL; |
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296 curSpool = curSpool->nextSpoolBlock) { |
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297 curSpool->print_on(st); |
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298 st->print_cr(" free "); |
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299 i++; |
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300 } |
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301 st->print_cr(" " SIZE_FORMAT " header spooling blocks", i); |
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302 } |
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303 |
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304 void SpoolBlock::print_on(outputStream* st) const { |
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305 st->print("[" PTR_FORMAT "," PTR_FORMAT "), " SIZE_FORMAT " HeapWords -> " PTR_FORMAT, |
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306 p2i(this), p2i((HeapWord*)displacedHdr + bufferSize), |
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307 bufferSize, p2i(nextSpoolBlock)); |
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308 } |
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