1 /* 2 * Copyright (c) 2005, 2009, Oracle and/or its affiliates. All rights reserved. 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 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 class oopDesc; 26 class ParMarkBitMapClosure; 27 28 class ParMarkBitMap: public CHeapObj 29 { 30 public: 31 typedef BitMap::idx_t idx_t; 32 33 // Values returned by the iterate() methods. 34 enum IterationStatus { incomplete, complete, full, would_overflow }; 35 36 inline ParMarkBitMap(); 37 inline ParMarkBitMap(MemRegion covered_region); 38 bool initialize(MemRegion covered_region); 39 40 // Atomically mark an object as live. 41 bool mark_obj(HeapWord* addr, size_t size); 42 inline bool mark_obj(oop obj, int size); 43 inline bool mark_obj(oop obj); 44 45 // Return whether the specified begin or end bit is set. 46 inline bool is_obj_beg(idx_t bit) const; 47 inline bool is_obj_end(idx_t bit) const; 48 49 // Traditional interface for testing whether an object is marked or not (these 50 // test only the begin bits). 51 inline bool is_marked(idx_t bit) const; 52 inline bool is_marked(HeapWord* addr) const; 53 inline bool is_marked(oop obj) const; 54 55 inline bool is_unmarked(idx_t bit) const; 56 inline bool is_unmarked(HeapWord* addr) const; 57 inline bool is_unmarked(oop obj) const; 58 59 // Convert sizes from bits to HeapWords and back. An object that is n bits 60 // long will be bits_to_words(n) words long. An object that is m words long 61 // will take up words_to_bits(m) bits in the bitmap. 62 inline static size_t bits_to_words(idx_t bits); 63 inline static idx_t words_to_bits(size_t words); 64 65 // Return the size in words of an object given a begin bit and an end bit, or 66 // the equivalent beg_addr and end_addr. 67 inline size_t obj_size(idx_t beg_bit, idx_t end_bit) const; 68 inline size_t obj_size(HeapWord* beg_addr, HeapWord* end_addr) const; 69 70 // Return the size in words of the object (a search is done for the end bit). 71 inline size_t obj_size(idx_t beg_bit) const; 72 inline size_t obj_size(HeapWord* addr) const; 73 inline size_t obj_size(oop obj) const; 74 75 // Synonyms for the above. 76 size_t obj_size_in_words(oop obj) const { return obj_size((HeapWord*)obj); } 77 size_t obj_size_in_words(HeapWord* addr) const { return obj_size(addr); } 78 79 // Apply live_closure to each live object that lies completely within the 80 // range [live_range_beg, live_range_end). This is used to iterate over the 81 // compacted region of the heap. Return values: 82 // 83 // incomplete The iteration is not complete. The last object that 84 // begins in the range does not end in the range; 85 // closure->source() is set to the start of that object. 86 // 87 // complete The iteration is complete. All objects in the range 88 // were processed and the closure is not full; 89 // closure->source() is set one past the end of the range. 90 // 91 // full The closure is full; closure->source() is set to one 92 // past the end of the last object processed. 93 // 94 // would_overflow The next object in the range would overflow the closure; 95 // closure->source() is set to the start of that object. 96 IterationStatus iterate(ParMarkBitMapClosure* live_closure, 97 idx_t range_beg, idx_t range_end) const; 98 inline IterationStatus iterate(ParMarkBitMapClosure* live_closure, 99 HeapWord* range_beg, 100 HeapWord* range_end) const; 101 102 // Apply live closure as above and additionally apply dead_closure to all dead 103 // space in the range [range_beg, dead_range_end). Note that dead_range_end 104 // must be >= range_end. This is used to iterate over the dense prefix. 105 // 106 // This method assumes that if the first bit in the range (range_beg) is not 107 // marked, then dead space begins at that point and the dead_closure is 108 // applied. Thus callers must ensure that range_beg is not in the middle of a 109 // live object. 110 IterationStatus iterate(ParMarkBitMapClosure* live_closure, 111 ParMarkBitMapClosure* dead_closure, 112 idx_t range_beg, idx_t range_end, 113 idx_t dead_range_end) const; 114 inline IterationStatus iterate(ParMarkBitMapClosure* live_closure, 115 ParMarkBitMapClosure* dead_closure, 116 HeapWord* range_beg, 117 HeapWord* range_end, 118 HeapWord* dead_range_end) const; 119 120 // Return the number of live words in the range [beg_addr, end_addr) due to 121 // objects that start in the range. If a live object extends onto the range, 122 // the caller must detect and account for any live words due to that object. 123 // If a live object extends beyond the end of the range, only the words within 124 // the range are included in the result. 125 size_t live_words_in_range(HeapWord* beg_addr, HeapWord* end_addr) const; 126 127 // Same as the above, except the end of the range must be a live object, which 128 // is the case when updating pointers. This allows a branch to be removed 129 // from inside the loop. 130 size_t live_words_in_range(HeapWord* beg_addr, oop end_obj) const; 131 132 inline HeapWord* region_start() const; 133 inline HeapWord* region_end() const; 134 inline size_t region_size() const; 135 inline size_t size() const; 136 137 // Convert a heap address to/from a bit index. 138 inline idx_t addr_to_bit(HeapWord* addr) const; 139 inline HeapWord* bit_to_addr(idx_t bit) const; 140 141 // Return the bit index of the first marked object that begins (or ends, 142 // respectively) in the range [beg, end). If no object is found, return end. 143 inline idx_t find_obj_beg(idx_t beg, idx_t end) const; 144 inline idx_t find_obj_end(idx_t beg, idx_t end) const; 145 146 inline HeapWord* find_obj_beg(HeapWord* beg, HeapWord* end) const; 147 inline HeapWord* find_obj_end(HeapWord* beg, HeapWord* end) const; 148 149 // Clear a range of bits or the entire bitmap (both begin and end bits are 150 // cleared). 151 inline void clear_range(idx_t beg, idx_t end); 152 inline void clear() { clear_range(0, size()); } 153 154 // Return the number of bits required to represent the specified number of 155 // HeapWords, or the specified region. 156 static inline idx_t bits_required(size_t words); 157 static inline idx_t bits_required(MemRegion covered_region); 158 static inline idx_t words_required(MemRegion covered_region); 159 160 #ifndef PRODUCT 161 // CAS statistics. 162 size_t cas_tries() { return _cas_tries; } 163 size_t cas_retries() { return _cas_retries; } 164 size_t cas_by_another() { return _cas_by_another; } 165 166 void reset_counters(); 167 #endif // #ifndef PRODUCT 168 169 #ifdef ASSERT 170 void verify_clear() const; 171 inline void verify_bit(idx_t bit) const; 172 inline void verify_addr(HeapWord* addr) const; 173 #endif // #ifdef ASSERT 174 175 private: 176 // Each bit in the bitmap represents one unit of 'object granularity.' Objects 177 // are double-word aligned in 32-bit VMs, but not in 64-bit VMs, so the 32-bit 178 // granularity is 2, 64-bit is 1. 179 static inline size_t obj_granularity() { return size_t(MinObjAlignment); } 180 static inline int obj_granularity_shift() { return LogMinObjAlignment; } 181 182 HeapWord* _region_start; 183 size_t _region_size; 184 BitMap _beg_bits; 185 BitMap _end_bits; 186 PSVirtualSpace* _virtual_space; 187 188 #ifndef PRODUCT 189 size_t _cas_tries; 190 size_t _cas_retries; 191 size_t _cas_by_another; 192 #endif // #ifndef PRODUCT 193 }; 194 195 inline ParMarkBitMap::ParMarkBitMap(): 196 _beg_bits(), 197 _end_bits() 198 { 199 _region_start = 0; 200 _virtual_space = 0; 201 } 202 203 inline ParMarkBitMap::ParMarkBitMap(MemRegion covered_region): 204 _beg_bits(), 205 _end_bits() 206 { 207 initialize(covered_region); 208 } 209 210 inline void ParMarkBitMap::clear_range(idx_t beg, idx_t end) 211 { 212 _beg_bits.clear_range(beg, end); 213 _end_bits.clear_range(beg, end); 214 } 215 216 inline ParMarkBitMap::idx_t 217 ParMarkBitMap::bits_required(size_t words) 218 { 219 // Need two bits (one begin bit, one end bit) for each unit of 'object 220 // granularity' in the heap. 221 return words_to_bits(words * 2); 222 } 223 224 inline ParMarkBitMap::idx_t 225 ParMarkBitMap::bits_required(MemRegion covered_region) 226 { 227 return bits_required(covered_region.word_size()); 228 } 229 230 inline ParMarkBitMap::idx_t 231 ParMarkBitMap::words_required(MemRegion covered_region) 232 { 233 return bits_required(covered_region) / BitsPerWord; 234 } 235 236 inline HeapWord* 237 ParMarkBitMap::region_start() const 238 { 239 return _region_start; 240 } 241 242 inline HeapWord* 243 ParMarkBitMap::region_end() const 244 { 245 return region_start() + region_size(); 246 } 247 248 inline size_t 249 ParMarkBitMap::region_size() const 250 { 251 return _region_size; 252 } 253 254 inline size_t 255 ParMarkBitMap::size() const 256 { 257 return _beg_bits.size(); 258 } 259 260 inline bool ParMarkBitMap::is_obj_beg(idx_t bit) const 261 { 262 return _beg_bits.at(bit); 263 } 264 265 inline bool ParMarkBitMap::is_obj_end(idx_t bit) const 266 { 267 return _end_bits.at(bit); 268 } 269 270 inline bool ParMarkBitMap::is_marked(idx_t bit) const 271 { 272 return is_obj_beg(bit); 273 } 274 275 inline bool ParMarkBitMap::is_marked(HeapWord* addr) const 276 { 277 return is_marked(addr_to_bit(addr)); 278 } 279 280 inline bool ParMarkBitMap::is_marked(oop obj) const 281 { 282 return is_marked((HeapWord*)obj); 283 } 284 285 inline bool ParMarkBitMap::is_unmarked(idx_t bit) const 286 { 287 return !is_marked(bit); 288 } 289 290 inline bool ParMarkBitMap::is_unmarked(HeapWord* addr) const 291 { 292 return !is_marked(addr); 293 } 294 295 inline bool ParMarkBitMap::is_unmarked(oop obj) const 296 { 297 return !is_marked(obj); 298 } 299 300 inline size_t 301 ParMarkBitMap::bits_to_words(idx_t bits) 302 { 303 return bits << obj_granularity_shift(); 304 } 305 306 inline ParMarkBitMap::idx_t 307 ParMarkBitMap::words_to_bits(size_t words) 308 { 309 return words >> obj_granularity_shift(); 310 } 311 312 inline size_t ParMarkBitMap::obj_size(idx_t beg_bit, idx_t end_bit) const 313 { 314 DEBUG_ONLY(verify_bit(beg_bit);) 315 DEBUG_ONLY(verify_bit(end_bit);) 316 return bits_to_words(end_bit - beg_bit + 1); 317 } 318 319 inline size_t 320 ParMarkBitMap::obj_size(HeapWord* beg_addr, HeapWord* end_addr) const 321 { 322 DEBUG_ONLY(verify_addr(beg_addr);) 323 DEBUG_ONLY(verify_addr(end_addr);) 324 return pointer_delta(end_addr, beg_addr) + obj_granularity(); 325 } 326 327 inline size_t ParMarkBitMap::obj_size(idx_t beg_bit) const 328 { 329 const idx_t end_bit = _end_bits.get_next_one_offset_inline(beg_bit, size()); 330 assert(is_marked(beg_bit), "obj not marked"); 331 assert(end_bit < size(), "end bit missing"); 332 return obj_size(beg_bit, end_bit); 333 } 334 335 inline size_t ParMarkBitMap::obj_size(HeapWord* addr) const 336 { 337 return obj_size(addr_to_bit(addr)); 338 } 339 340 inline size_t ParMarkBitMap::obj_size(oop obj) const 341 { 342 return obj_size((HeapWord*)obj); 343 } 344 345 inline ParMarkBitMap::IterationStatus 346 ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure, 347 HeapWord* range_beg, 348 HeapWord* range_end) const 349 { 350 return iterate(live_closure, addr_to_bit(range_beg), addr_to_bit(range_end)); 351 } 352 353 inline ParMarkBitMap::IterationStatus 354 ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure, 355 ParMarkBitMapClosure* dead_closure, 356 HeapWord* range_beg, 357 HeapWord* range_end, 358 HeapWord* dead_range_end) const 359 { 360 return iterate(live_closure, dead_closure, 361 addr_to_bit(range_beg), addr_to_bit(range_end), 362 addr_to_bit(dead_range_end)); 363 } 364 365 inline bool 366 ParMarkBitMap::mark_obj(oop obj, int size) 367 { 368 return mark_obj((HeapWord*)obj, (size_t)size); 369 } 370 371 inline BitMap::idx_t 372 ParMarkBitMap::addr_to_bit(HeapWord* addr) const 373 { 374 DEBUG_ONLY(verify_addr(addr);) 375 return words_to_bits(pointer_delta(addr, region_start())); 376 } 377 378 inline HeapWord* 379 ParMarkBitMap::bit_to_addr(idx_t bit) const 380 { 381 DEBUG_ONLY(verify_bit(bit);) 382 return region_start() + bits_to_words(bit); 383 } 384 385 inline ParMarkBitMap::idx_t 386 ParMarkBitMap::find_obj_beg(idx_t beg, idx_t end) const 387 { 388 return _beg_bits.get_next_one_offset_inline_aligned_right(beg, end); 389 } 390 391 inline ParMarkBitMap::idx_t 392 ParMarkBitMap::find_obj_end(idx_t beg, idx_t end) const 393 { 394 return _end_bits.get_next_one_offset_inline_aligned_right(beg, end); 395 } 396 397 inline HeapWord* 398 ParMarkBitMap::find_obj_beg(HeapWord* beg, HeapWord* end) const 399 { 400 const idx_t beg_bit = addr_to_bit(beg); 401 const idx_t end_bit = addr_to_bit(end); 402 const idx_t search_end = BitMap::word_align_up(end_bit); 403 const idx_t res_bit = MIN2(find_obj_beg(beg_bit, search_end), end_bit); 404 return bit_to_addr(res_bit); 405 } 406 407 inline HeapWord* 408 ParMarkBitMap::find_obj_end(HeapWord* beg, HeapWord* end) const 409 { 410 const idx_t beg_bit = addr_to_bit(beg); 411 const idx_t end_bit = addr_to_bit(end); 412 const idx_t search_end = BitMap::word_align_up(end_bit); 413 const idx_t res_bit = MIN2(find_obj_end(beg_bit, search_end), end_bit); 414 return bit_to_addr(res_bit); 415 } 416 417 #ifdef ASSERT 418 inline void ParMarkBitMap::verify_bit(idx_t bit) const { 419 // Allow one past the last valid bit; useful for loop bounds. 420 assert(bit <= _beg_bits.size(), "bit out of range"); 421 } 422 423 inline void ParMarkBitMap::verify_addr(HeapWord* addr) const { 424 // Allow one past the last valid address; useful for loop bounds. 425 assert(addr >= region_start(), "addr too small"); 426 assert(addr <= region_start() + region_size(), "addr too big"); 427 } 428 #endif // #ifdef ASSERT