Mercurial > hg > truffle
annotate src/share/vm/memory/blockOffsetTable.hpp @ 6725:da91efe96a93
6964458: Reimplement class meta-data storage to use native memory
Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes
Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland
Contributed-by: jmasa <jon.masamitsu@oracle.com>, stefank <stefan.karlsson@oracle.com>, mgerdin <mikael.gerdin@oracle.com>, never <tom.rodriguez@oracle.com>
| author | coleenp |
|---|---|
| date | Sat, 01 Sep 2012 13:25:18 -0400 |
| parents | d2a62e0f25eb |
| children | 859cd1a76f8a |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved. |
| 0 | 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 * | |
|
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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. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #ifndef SHARE_VM_MEMORY_BLOCKOFFSETTABLE_HPP |
| 26 #define SHARE_VM_MEMORY_BLOCKOFFSETTABLE_HPP | |
| 27 | |
| 28 #include "memory/memRegion.hpp" | |
| 29 #include "runtime/virtualspace.hpp" | |
| 30 #include "utilities/globalDefinitions.hpp" | |
| 31 | |
| 0 | 32 // The CollectedHeap type requires subtypes to implement a method |
| 33 // "block_start". For some subtypes, notably generational | |
| 34 // systems using card-table-based write barriers, the efficiency of this | |
| 35 // operation may be important. Implementations of the "BlockOffsetArray" | |
| 36 // class may be useful in providing such efficient implementations. | |
| 37 // | |
| 38 // BlockOffsetTable (abstract) | |
| 39 // - BlockOffsetArray (abstract) | |
| 40 // - BlockOffsetArrayNonContigSpace | |
| 41 // - BlockOffsetArrayContigSpace | |
| 42 // | |
| 43 | |
| 44 class ContiguousSpace; | |
| 45 | |
| 46 ////////////////////////////////////////////////////////////////////////// | |
| 47 // The BlockOffsetTable "interface" | |
| 48 ////////////////////////////////////////////////////////////////////////// | |
| 49 class BlockOffsetTable VALUE_OBJ_CLASS_SPEC { | |
| 50 friend class VMStructs; | |
| 51 protected: | |
| 52 // These members describe the region covered by the table. | |
| 53 | |
| 54 // The space this table is covering. | |
| 55 HeapWord* _bottom; // == reserved.start | |
| 56 HeapWord* _end; // End of currently allocated region. | |
| 57 | |
| 58 public: | |
| 59 // Initialize the table to cover the given space. | |
| 60 // The contents of the initial table are undefined. | |
| 61 BlockOffsetTable(HeapWord* bottom, HeapWord* end): | |
| 62 _bottom(bottom), _end(end) { | |
| 63 assert(_bottom <= _end, "arguments out of order"); | |
| 64 } | |
| 65 | |
| 66 // Note that the committed size of the covered space may have changed, | |
| 67 // so the table size might also wish to change. | |
| 68 virtual void resize(size_t new_word_size) = 0; | |
| 69 | |
| 70 virtual void set_bottom(HeapWord* new_bottom) { | |
| 71 assert(new_bottom <= _end, "new_bottom > _end"); | |
| 72 _bottom = new_bottom; | |
| 73 resize(pointer_delta(_end, _bottom)); | |
| 74 } | |
| 75 | |
| 76 // Requires "addr" to be contained by a block, and returns the address of | |
| 77 // the start of that block. | |
| 78 virtual HeapWord* block_start_unsafe(const void* addr) const = 0; | |
| 79 | |
| 80 // Returns the address of the start of the block containing "addr", or | |
| 81 // else "null" if it is covered by no block. | |
| 82 HeapWord* block_start(const void* addr) const; | |
| 83 }; | |
| 84 | |
| 85 ////////////////////////////////////////////////////////////////////////// | |
| 86 // One implementation of "BlockOffsetTable," the BlockOffsetArray, | |
| 87 // divides the covered region into "N"-word subregions (where | |
| 88 // "N" = 2^"LogN". An array with an entry for each such subregion | |
| 89 // indicates how far back one must go to find the start of the | |
| 90 // chunk that includes the first word of the subregion. | |
| 91 // | |
| 92 // Each BlockOffsetArray is owned by a Space. However, the actual array | |
| 93 // may be shared by several BlockOffsetArrays; this is useful | |
| 94 // when a single resizable area (such as a generation) is divided up into | |
| 95 // several spaces in which contiguous allocation takes place. (Consider, | |
| 96 // for example, the garbage-first generation.) | |
| 97 | |
| 98 // Here is the shared array type. | |
| 99 ////////////////////////////////////////////////////////////////////////// | |
| 100 // BlockOffsetSharedArray | |
| 101 ////////////////////////////////////////////////////////////////////////// | |
| 6197 | 102 class BlockOffsetSharedArray: public CHeapObj<mtGC> { |
| 0 | 103 friend class BlockOffsetArray; |
| 104 friend class BlockOffsetArrayNonContigSpace; | |
| 105 friend class BlockOffsetArrayContigSpace; | |
| 106 friend class VMStructs; | |
| 107 | |
| 108 private: | |
| 109 enum SomePrivateConstants { | |
| 110 LogN = 9, | |
| 111 LogN_words = LogN - LogHeapWordSize, | |
| 112 N_bytes = 1 << LogN, | |
| 113 N_words = 1 << LogN_words | |
| 114 }; | |
| 115 | |
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116 bool _init_to_zero; |
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117 |
| 0 | 118 // The reserved region covered by the shared array. |
| 119 MemRegion _reserved; | |
| 120 | |
| 121 // End of the current committed region. | |
| 122 HeapWord* _end; | |
| 123 | |
| 124 // Array for keeping offsets for retrieving object start fast given an | |
| 125 // address. | |
| 126 VirtualSpace _vs; | |
| 127 u_char* _offset_array; // byte array keeping backwards offsets | |
| 128 | |
| 129 protected: | |
| 130 // Bounds checking accessors: | |
| 131 // For performance these have to devolve to array accesses in product builds. | |
| 132 u_char offset_array(size_t index) const { | |
| 133 assert(index < _vs.committed_size(), "index out of range"); | |
| 134 return _offset_array[index]; | |
| 135 } | |
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136 // An assertion-checking helper method for the set_offset_array() methods below. |
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137 void check_reducing_assertion(bool reducing); |
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138 |
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139 void set_offset_array(size_t index, u_char offset, bool reducing = false) { |
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140 check_reducing_assertion(reducing); |
| 0 | 141 assert(index < _vs.committed_size(), "index out of range"); |
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142 assert(!reducing || _offset_array[index] >= offset, "Not reducing"); |
| 0 | 143 _offset_array[index] = offset; |
| 144 } | |
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145 |
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146 void set_offset_array(size_t index, HeapWord* high, HeapWord* low, bool reducing = false) { |
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147 check_reducing_assertion(reducing); |
| 0 | 148 assert(index < _vs.committed_size(), "index out of range"); |
| 149 assert(high >= low, "addresses out of order"); | |
| 150 assert(pointer_delta(high, low) <= N_words, "offset too large"); | |
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151 assert(!reducing || _offset_array[index] >= (u_char)pointer_delta(high, low), |
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152 "Not reducing"); |
| 0 | 153 _offset_array[index] = (u_char)pointer_delta(high, low); |
| 154 } | |
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155 |
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156 void set_offset_array(HeapWord* left, HeapWord* right, u_char offset, bool reducing = false) { |
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157 check_reducing_assertion(reducing); |
| 0 | 158 assert(index_for(right - 1) < _vs.committed_size(), |
| 159 "right address out of range"); | |
| 160 assert(left < right, "Heap addresses out of order"); | |
| 161 size_t num_cards = pointer_delta(right, left) >> LogN_words; | |
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162 |
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163 // Below, we may use an explicit loop instead of memset() |
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164 // because on certain platforms memset() can give concurrent |
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165 // readers "out-of-thin-air," phantom zeros; see 6948537. |
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166 if (UseMemSetInBOT) { |
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167 memset(&_offset_array[index_for(left)], offset, num_cards); |
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168 } else { |
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169 size_t i = index_for(left); |
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170 const size_t end = i + num_cards; |
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171 for (; i < end; i++) { |
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172 // Elided until CR 6977974 is fixed properly. |
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173 // assert(!reducing || _offset_array[i] >= offset, "Not reducing"); |
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174 _offset_array[i] = offset; |
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175 } |
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176 } |
| 0 | 177 } |
| 178 | |
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179 void set_offset_array(size_t left, size_t right, u_char offset, bool reducing = false) { |
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180 check_reducing_assertion(reducing); |
| 0 | 181 assert(right < _vs.committed_size(), "right address out of range"); |
| 182 assert(left <= right, "indexes out of order"); | |
| 183 size_t num_cards = right - left + 1; | |
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184 |
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185 // Below, we may use an explicit loop instead of memset |
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186 // because on certain platforms memset() can give concurrent |
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187 // readers "out-of-thin-air," phantom zeros; see 6948537. |
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188 if (UseMemSetInBOT) { |
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189 memset(&_offset_array[left], offset, num_cards); |
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190 } else { |
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191 size_t i = left; |
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192 const size_t end = i + num_cards; |
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193 for (; i < end; i++) { |
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194 // Elided until CR 6977974 is fixed properly. |
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195 // assert(!reducing || _offset_array[i] >= offset, "Not reducing"); |
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196 _offset_array[i] = offset; |
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197 } |
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198 } |
| 0 | 199 } |
| 200 | |
| 201 void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const { | |
| 202 assert(index < _vs.committed_size(), "index out of range"); | |
| 203 assert(high >= low, "addresses out of order"); | |
| 204 assert(pointer_delta(high, low) <= N_words, "offset too large"); | |
| 205 assert(_offset_array[index] == pointer_delta(high, low), | |
| 206 "Wrong offset"); | |
| 207 } | |
| 208 | |
| 209 bool is_card_boundary(HeapWord* p) const; | |
| 210 | |
| 211 // Return the number of slots needed for an offset array | |
| 212 // that covers mem_region_words words. | |
| 213 // We always add an extra slot because if an object | |
| 214 // ends on a card boundary we put a 0 in the next | |
| 215 // offset array slot, so we want that slot always | |
| 216 // to be reserved. | |
| 217 | |
| 218 size_t compute_size(size_t mem_region_words) { | |
| 219 size_t number_of_slots = (mem_region_words / N_words) + 1; | |
| 220 return ReservedSpace::allocation_align_size_up(number_of_slots); | |
| 221 } | |
| 222 | |
| 223 public: | |
| 224 // Initialize the table to cover from "base" to (at least) | |
| 225 // "base + init_word_size". In the future, the table may be expanded | |
| 226 // (see "resize" below) up to the size of "_reserved" (which must be at | |
| 227 // least "init_word_size".) The contents of the initial table are | |
| 228 // undefined; it is the responsibility of the constituent | |
| 229 // BlockOffsetTable(s) to initialize cards. | |
| 230 BlockOffsetSharedArray(MemRegion reserved, size_t init_word_size); | |
| 231 | |
| 232 // Notes a change in the committed size of the region covered by the | |
| 233 // table. The "new_word_size" may not be larger than the size of the | |
| 234 // reserved region this table covers. | |
| 235 void resize(size_t new_word_size); | |
| 236 | |
| 237 void set_bottom(HeapWord* new_bottom); | |
| 238 | |
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239 // Whether entries should be initialized to zero. Used currently only for |
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240 // error checking. |
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241 void set_init_to_zero(bool val) { _init_to_zero = val; } |
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242 bool init_to_zero() { return _init_to_zero; } |
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243 |
| 0 | 244 // Updates all the BlockOffsetArray's sharing this shared array to |
| 245 // reflect the current "top"'s of their spaces. | |
| 246 void update_offset_arrays(); // Not yet implemented! | |
| 247 | |
| 248 // Return the appropriate index into "_offset_array" for "p". | |
| 249 size_t index_for(const void* p) const; | |
| 250 | |
| 251 // Return the address indicating the start of the region corresponding to | |
| 252 // "index" in "_offset_array". | |
| 253 HeapWord* address_for_index(size_t index) const; | |
| 254 | |
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255 // Return the address "p" incremented by the size of |
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256 // a region. This method does not align the address |
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257 // returned to the start of a region. It is a simple |
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258 // primitive. |
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259 HeapWord* inc_by_region_size(HeapWord* p) const { return p + N_words; } |
| 0 | 260 }; |
| 261 | |
| 262 ////////////////////////////////////////////////////////////////////////// | |
| 263 // The BlockOffsetArray whose subtypes use the BlockOffsetSharedArray. | |
| 264 ////////////////////////////////////////////////////////////////////////// | |
| 265 class BlockOffsetArray: public BlockOffsetTable { | |
| 266 friend class VMStructs; | |
| 342 | 267 friend class G1BlockOffsetArray; // temp. until we restructure and cleanup |
| 0 | 268 protected: |
| 269 // The following enums are used by do_block_internal() below | |
| 270 enum Action { | |
| 271 Action_single, // BOT records a single block (see single_block()) | |
| 272 Action_mark, // BOT marks the start of a block (see mark_block()) | |
| 273 Action_check // Check that BOT records block correctly | |
| 274 // (see verify_single_block()). | |
| 275 }; | |
| 276 | |
| 277 enum SomePrivateConstants { | |
| 278 N_words = BlockOffsetSharedArray::N_words, | |
| 279 LogN = BlockOffsetSharedArray::LogN, | |
| 280 // entries "e" of at least N_words mean "go back by Base^(e-N_words)." | |
| 281 // All entries are less than "N_words + N_powers". | |
| 282 LogBase = 4, | |
| 283 Base = (1 << LogBase), | |
| 284 N_powers = 14 | |
| 285 }; | |
| 286 | |
| 287 static size_t power_to_cards_back(uint i) { | |
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288 return (size_t)(1 << (LogBase * i)); |
| 0 | 289 } |
| 290 static size_t power_to_words_back(uint i) { | |
| 291 return power_to_cards_back(i) * N_words; | |
| 292 } | |
| 293 static size_t entry_to_cards_back(u_char entry) { | |
| 294 assert(entry >= N_words, "Precondition"); | |
| 295 return power_to_cards_back(entry - N_words); | |
| 296 } | |
| 297 static size_t entry_to_words_back(u_char entry) { | |
| 298 assert(entry >= N_words, "Precondition"); | |
| 299 return power_to_words_back(entry - N_words); | |
| 300 } | |
| 301 | |
| 302 // The shared array, which is shared with other BlockOffsetArray's | |
| 303 // corresponding to different spaces within a generation or span of | |
| 304 // memory. | |
| 305 BlockOffsetSharedArray* _array; | |
| 306 | |
| 307 // The space that owns this subregion. | |
| 308 Space* _sp; | |
| 309 | |
| 310 // If true, array entries are initialized to 0; otherwise, they are | |
| 311 // initialized to point backwards to the beginning of the covered region. | |
| 312 bool _init_to_zero; | |
| 313 | |
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314 // An assertion-checking helper method for the set_remainder*() methods below. |
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315 void check_reducing_assertion(bool reducing) { _array->check_reducing_assertion(reducing); } |
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316 |
| 0 | 317 // Sets the entries |
| 318 // corresponding to the cards starting at "start" and ending at "end" | |
| 319 // to point back to the card before "start": the interval [start, end) | |
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320 // is right-open. The last parameter, reducing, indicates whether the |
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321 // updates to individual entries always reduce the entry from a higher |
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322 // to a lower value. (For example this would hold true during a temporal |
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323 // regime during which only block splits were updating the BOT. |
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324 void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end, bool reducing = false); |
| 0 | 325 // Same as above, except that the args here are a card _index_ interval |
| 326 // that is closed: [start_index, end_index] | |
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327 void set_remainder_to_point_to_start_incl(size_t start, size_t end, bool reducing = false); |
| 0 | 328 |
| 329 // A helper function for BOT adjustment/verification work | |
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330 void do_block_internal(HeapWord* blk_start, HeapWord* blk_end, Action action, bool reducing = false); |
| 0 | 331 |
| 332 public: | |
| 333 // The space may not have its bottom and top set yet, which is why the | |
| 334 // region is passed as a parameter. If "init_to_zero" is true, the | |
| 335 // elements of the array are initialized to zero. Otherwise, they are | |
| 336 // initialized to point backwards to the beginning. | |
| 337 BlockOffsetArray(BlockOffsetSharedArray* array, MemRegion mr, | |
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338 bool init_to_zero_); |
| 0 | 339 |
| 340 // Note: this ought to be part of the constructor, but that would require | |
| 341 // "this" to be passed as a parameter to a member constructor for | |
| 342 // the containing concrete subtype of Space. | |
| 343 // This would be legal C++, but MS VC++ doesn't allow it. | |
| 344 void set_space(Space* sp) { _sp = sp; } | |
| 345 | |
| 346 // Resets the covered region to the given "mr". | |
| 347 void set_region(MemRegion mr) { | |
| 348 _bottom = mr.start(); | |
| 349 _end = mr.end(); | |
| 350 } | |
| 351 | |
| 352 // Note that the committed size of the covered space may have changed, | |
| 353 // so the table size might also wish to change. | |
| 354 virtual void resize(size_t new_word_size) { | |
| 355 HeapWord* new_end = _bottom + new_word_size; | |
| 356 if (_end < new_end && !init_to_zero()) { | |
| 357 // verify that the old and new boundaries are also card boundaries | |
| 358 assert(_array->is_card_boundary(_end), | |
| 359 "_end not a card boundary"); | |
| 360 assert(_array->is_card_boundary(new_end), | |
| 361 "new _end would not be a card boundary"); | |
| 362 // set all the newly added cards | |
| 363 _array->set_offset_array(_end, new_end, N_words); | |
| 364 } | |
| 365 _end = new_end; // update _end | |
| 366 } | |
| 367 | |
| 368 // Adjust the BOT to show that it has a single block in the | |
| 369 // range [blk_start, blk_start + size). All necessary BOT | |
| 370 // cards are adjusted, but _unallocated_block isn't. | |
| 371 void single_block(HeapWord* blk_start, HeapWord* blk_end); | |
| 372 void single_block(HeapWord* blk, size_t size) { | |
| 373 single_block(blk, blk + size); | |
| 374 } | |
| 375 | |
| 376 // When the alloc_block() call returns, the block offset table should | |
| 377 // have enough information such that any subsequent block_start() call | |
| 378 // with an argument equal to an address that is within the range | |
| 379 // [blk_start, blk_end) would return the value blk_start, provided | |
| 380 // there have been no calls in between that reset this information | |
| 381 // (e.g. see BlockOffsetArrayNonContigSpace::single_block() call | |
| 382 // for an appropriate range covering the said interval). | |
| 383 // These methods expect to be called with [blk_start, blk_end) | |
| 384 // representing a block of memory in the heap. | |
| 385 virtual void alloc_block(HeapWord* blk_start, HeapWord* blk_end); | |
| 386 void alloc_block(HeapWord* blk, size_t size) { | |
| 387 alloc_block(blk, blk + size); | |
| 388 } | |
| 389 | |
| 390 // If true, initialize array slots with no allocated blocks to zero. | |
| 391 // Otherwise, make them point back to the front. | |
| 392 bool init_to_zero() { return _init_to_zero; } | |
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393 // Corresponding setter |
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394 void set_init_to_zero(bool val) { |
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395 _init_to_zero = val; |
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396 assert(_array != NULL, "_array should be non-NULL"); |
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397 _array->set_init_to_zero(val); |
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398 } |
| 0 | 399 |
| 400 // Debugging | |
| 401 // Return the index of the last entry in the "active" region. | |
| 402 virtual size_t last_active_index() const = 0; | |
| 403 // Verify the block offset table | |
| 404 void verify() const; | |
| 405 void check_all_cards(size_t left_card, size_t right_card) const; | |
| 406 }; | |
| 407 | |
| 408 //////////////////////////////////////////////////////////////////////////// | |
| 409 // A subtype of BlockOffsetArray that takes advantage of the fact | |
| 410 // that its underlying space is a NonContiguousSpace, so that some | |
| 411 // specialized interfaces can be made available for spaces that | |
| 412 // manipulate the table. | |
| 413 //////////////////////////////////////////////////////////////////////////// | |
| 414 class BlockOffsetArrayNonContigSpace: public BlockOffsetArray { | |
| 415 friend class VMStructs; | |
| 416 private: | |
| 417 // The portion [_unallocated_block, _sp.end()) of the space that | |
| 418 // is a single block known not to contain any objects. | |
| 419 // NOTE: See BlockOffsetArrayUseUnallocatedBlock flag. | |
| 420 HeapWord* _unallocated_block; | |
| 421 | |
| 422 public: | |
| 423 BlockOffsetArrayNonContigSpace(BlockOffsetSharedArray* array, MemRegion mr): | |
| 424 BlockOffsetArray(array, mr, false), | |
| 425 _unallocated_block(_bottom) { } | |
| 426 | |
| 427 // accessor | |
| 428 HeapWord* unallocated_block() const { | |
| 429 assert(BlockOffsetArrayUseUnallocatedBlock, | |
| 430 "_unallocated_block is not being maintained"); | |
| 431 return _unallocated_block; | |
| 432 } | |
| 433 | |
| 434 void set_unallocated_block(HeapWord* block) { | |
| 435 assert(BlockOffsetArrayUseUnallocatedBlock, | |
| 436 "_unallocated_block is not being maintained"); | |
| 437 assert(block >= _bottom && block <= _end, "out of range"); | |
| 438 _unallocated_block = block; | |
| 439 } | |
| 440 | |
| 441 // These methods expect to be called with [blk_start, blk_end) | |
| 442 // representing a block of memory in the heap. | |
| 443 void alloc_block(HeapWord* blk_start, HeapWord* blk_end); | |
| 444 void alloc_block(HeapWord* blk, size_t size) { | |
| 445 alloc_block(blk, blk + size); | |
| 446 } | |
| 447 | |
| 448 // The following methods are useful and optimized for a | |
| 449 // non-contiguous space. | |
| 450 | |
| 451 // Given a block [blk_start, blk_start + full_blk_size), and | |
| 452 // a left_blk_size < full_blk_size, adjust the BOT to show two | |
| 453 // blocks [blk_start, blk_start + left_blk_size) and | |
| 454 // [blk_start + left_blk_size, blk_start + full_blk_size). | |
| 455 // It is assumed (and verified in the non-product VM) that the | |
| 456 // BOT was correct for the original block. | |
| 457 void split_block(HeapWord* blk_start, size_t full_blk_size, | |
| 458 size_t left_blk_size); | |
| 459 | |
| 460 // Adjust BOT to show that it has a block in the range | |
| 461 // [blk_start, blk_start + size). Only the first card | |
| 462 // of BOT is touched. It is assumed (and verified in the | |
| 463 // non-product VM) that the remaining cards of the block | |
| 464 // are correct. | |
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465 void mark_block(HeapWord* blk_start, HeapWord* blk_end, bool reducing = false); |
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466 void mark_block(HeapWord* blk, size_t size, bool reducing = false) { |
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467 mark_block(blk, blk + size, reducing); |
| 0 | 468 } |
| 469 | |
| 470 // Adjust _unallocated_block to indicate that a particular | |
| 471 // block has been newly allocated or freed. It is assumed (and | |
| 472 // verified in the non-product VM) that the BOT is correct for | |
| 473 // the given block. | |
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474 void allocated(HeapWord* blk_start, HeapWord* blk_end, bool reducing = false) { |
| 0 | 475 // Verify that the BOT shows [blk, blk + blk_size) to be one block. |
| 476 verify_single_block(blk_start, blk_end); | |
| 477 if (BlockOffsetArrayUseUnallocatedBlock) { | |
| 478 _unallocated_block = MAX2(_unallocated_block, blk_end); | |
| 479 } | |
| 480 } | |
| 481 | |
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482 void allocated(HeapWord* blk, size_t size, bool reducing = false) { |
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483 allocated(blk, blk + size, reducing); |
| 0 | 484 } |
| 485 | |
| 486 void freed(HeapWord* blk_start, HeapWord* blk_end); | |
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487 void freed(HeapWord* blk, size_t size); |
| 0 | 488 |
| 489 HeapWord* block_start_unsafe(const void* addr) const; | |
| 490 | |
| 491 // Requires "addr" to be the start of a card and returns the | |
| 492 // start of the block that contains the given address. | |
| 493 HeapWord* block_start_careful(const void* addr) const; | |
| 494 | |
| 495 // Verification & debugging: ensure that the offset table reflects | |
| 496 // the fact that the block [blk_start, blk_end) or [blk, blk + size) | |
| 497 // is a single block of storage. NOTE: can't const this because of | |
| 498 // call to non-const do_block_internal() below. | |
| 499 void verify_single_block(HeapWord* blk_start, HeapWord* blk_end) | |
| 500 PRODUCT_RETURN; | |
| 501 void verify_single_block(HeapWord* blk, size_t size) PRODUCT_RETURN; | |
| 502 | |
| 503 // Verify that the given block is before _unallocated_block | |
| 504 void verify_not_unallocated(HeapWord* blk_start, HeapWord* blk_end) | |
| 505 const PRODUCT_RETURN; | |
| 506 void verify_not_unallocated(HeapWord* blk, size_t size) | |
| 507 const PRODUCT_RETURN; | |
| 508 | |
| 509 // Debugging support | |
| 510 virtual size_t last_active_index() const; | |
| 511 }; | |
| 512 | |
| 513 //////////////////////////////////////////////////////////////////////////// | |
| 514 // A subtype of BlockOffsetArray that takes advantage of the fact | |
| 515 // that its underlying space is a ContiguousSpace, so that its "active" | |
| 516 // region can be more efficiently tracked (than for a non-contiguous space). | |
| 517 //////////////////////////////////////////////////////////////////////////// | |
| 518 class BlockOffsetArrayContigSpace: public BlockOffsetArray { | |
| 519 friend class VMStructs; | |
| 520 private: | |
| 521 // allocation boundary at which offset array must be updated | |
| 522 HeapWord* _next_offset_threshold; | |
| 523 size_t _next_offset_index; // index corresponding to that boundary | |
| 524 | |
| 525 // Work function when allocation start crosses threshold. | |
| 526 void alloc_block_work(HeapWord* blk_start, HeapWord* blk_end); | |
| 527 | |
| 528 public: | |
| 529 BlockOffsetArrayContigSpace(BlockOffsetSharedArray* array, MemRegion mr): | |
| 530 BlockOffsetArray(array, mr, true) { | |
| 531 _next_offset_threshold = NULL; | |
| 532 _next_offset_index = 0; | |
| 533 } | |
| 534 | |
| 535 void set_contig_space(ContiguousSpace* sp) { set_space((Space*)sp); } | |
| 536 | |
| 537 // Initialize the threshold for an empty heap. | |
| 538 HeapWord* initialize_threshold(); | |
| 539 // Zero out the entry for _bottom (offset will be zero) | |
| 540 void zero_bottom_entry(); | |
| 541 | |
| 542 // Return the next threshold, the point at which the table should be | |
| 543 // updated. | |
| 544 HeapWord* threshold() const { return _next_offset_threshold; } | |
| 545 | |
| 546 // In general, these methods expect to be called with | |
| 547 // [blk_start, blk_end) representing a block of memory in the heap. | |
| 548 // In this implementation, however, we are OK even if blk_start and/or | |
| 549 // blk_end are NULL because NULL is represented as 0, and thus | |
| 550 // never exceeds the "_next_offset_threshold". | |
| 551 void alloc_block(HeapWord* blk_start, HeapWord* blk_end) { | |
| 552 if (blk_end > _next_offset_threshold) { | |
| 553 alloc_block_work(blk_start, blk_end); | |
| 554 } | |
| 555 } | |
| 556 void alloc_block(HeapWord* blk, size_t size) { | |
| 557 alloc_block(blk, blk + size); | |
| 558 } | |
| 559 | |
| 560 HeapWord* block_start_unsafe(const void* addr) const; | |
| 561 | |
| 562 // Debugging support | |
| 563 virtual size_t last_active_index() const; | |
| 564 }; | |
| 1972 | 565 |
| 566 #endif // SHARE_VM_MEMORY_BLOCKOFFSETTABLE_HPP |