1 /* 2 * Copyright (c) 2000, 2010, 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 #include "precompiled.hpp" 26 #include "gc_interface/collectedHeap.inline.hpp" 27 #include "memory/blockOffsetTable.inline.hpp" 28 #include "memory/iterator.hpp" 29 #include "memory/space.inline.hpp" 30 #include "memory/universe.hpp" 31 #include "oops/oop.inline.hpp" 32 #include "runtime/java.hpp" 33 34 ////////////////////////////////////////////////////////////////////// 35 // BlockOffsetSharedArray 36 ////////////////////////////////////////////////////////////////////// 37 38 BlockOffsetSharedArray::BlockOffsetSharedArray(MemRegion reserved, 39 size_t init_word_size): 40 _reserved(reserved), _end(NULL) 41 { 42 size_t size = compute_size(reserved.word_size()); 43 ReservedSpace rs(size); 44 if (!rs.is_reserved()) { 45 vm_exit_during_initialization("Could not reserve enough space for heap offset array"); 46 } 47 if (!_vs.initialize(rs, 0)) { 48 vm_exit_during_initialization("Could not reserve enough space for heap offset array"); 49 } 50 _offset_array = (u_char*)_vs.low_boundary(); 51 resize(init_word_size); 52 if (TraceBlockOffsetTable) { 53 gclog_or_tty->print_cr("BlockOffsetSharedArray::BlockOffsetSharedArray: "); 54 gclog_or_tty->print_cr(" " 55 " rs.base(): " INTPTR_FORMAT 56 " rs.size(): " INTPTR_FORMAT 57 " rs end(): " INTPTR_FORMAT, 58 rs.base(), rs.size(), rs.base() + rs.size()); 59 gclog_or_tty->print_cr(" " 60 " _vs.low_boundary(): " INTPTR_FORMAT 61 " _vs.high_boundary(): " INTPTR_FORMAT, 62 _vs.low_boundary(), 63 _vs.high_boundary()); 64 } 65 } 66 67 void BlockOffsetSharedArray::resize(size_t new_word_size) { 68 assert(new_word_size <= _reserved.word_size(), "Resize larger than reserved"); 69 size_t new_size = compute_size(new_word_size); 70 size_t old_size = _vs.committed_size(); 71 size_t delta; 72 char* high = _vs.high(); 73 _end = _reserved.start() + new_word_size; 74 if (new_size > old_size) { 75 delta = ReservedSpace::page_align_size_up(new_size - old_size); 76 assert(delta > 0, "just checking"); 77 if (!_vs.expand_by(delta)) { 78 // Do better than this for Merlin 79 vm_exit_out_of_memory(delta, "offset table expansion"); 80 } 81 assert(_vs.high() == high + delta, "invalid expansion"); 82 } else { 83 delta = ReservedSpace::page_align_size_down(old_size - new_size); 84 if (delta == 0) return; 85 _vs.shrink_by(delta); 86 assert(_vs.high() == high - delta, "invalid expansion"); 87 } 88 } 89 90 bool BlockOffsetSharedArray::is_card_boundary(HeapWord* p) const { 91 assert(p >= _reserved.start(), "just checking"); 92 size_t delta = pointer_delta(p, _reserved.start()); 93 return (delta & right_n_bits(LogN_words)) == (size_t)NoBits; 94 } 95 96 97 void BlockOffsetSharedArray::serialize(SerializeOopClosure* soc, 98 HeapWord* start, HeapWord* end) { 99 assert(_offset_array[0] == 0, "objects can't cross covered areas"); 100 assert(start <= end, "bad address range"); 101 size_t start_index = index_for(start); 102 size_t end_index = index_for(end-1)+1; 103 soc->do_region(&_offset_array[start_index], 104 (end_index - start_index) * sizeof(_offset_array[0])); 105 } 106 107 ////////////////////////////////////////////////////////////////////// 108 // BlockOffsetArray 109 ////////////////////////////////////////////////////////////////////// 110 111 BlockOffsetArray::BlockOffsetArray(BlockOffsetSharedArray* array, 112 MemRegion mr, bool init_to_zero_) : 113 BlockOffsetTable(mr.start(), mr.end()), 114 _array(array) 115 { 116 assert(_bottom <= _end, "arguments out of order"); 117 set_init_to_zero(init_to_zero_); 118 if (!init_to_zero_) { 119 // initialize cards to point back to mr.start() 120 set_remainder_to_point_to_start(mr.start() + N_words, mr.end()); 121 _array->set_offset_array(0, 0); // set first card to 0 122 } 123 } 124 125 126 // The arguments follow the normal convention of denoting 127 // a right-open interval: [start, end) 128 void 129 BlockOffsetArray:: 130 set_remainder_to_point_to_start(HeapWord* start, HeapWord* end, bool reducing) { 131 132 check_reducing_assertion(reducing); 133 if (start >= end) { 134 // The start address is equal to the end address (or to 135 // the right of the end address) so there are not cards 136 // that need to be updated.. 137 return; 138 } 139 140 // Write the backskip value for each region. 141 // 142 // offset 143 // card 2nd 3rd 144 // | +- 1st | | 145 // v v v v 146 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+- 147 // |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ... 148 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+- 149 // 11 19 75 150 // 12 151 // 152 // offset card is the card that points to the start of an object 153 // x - offset value of offset card 154 // 1st - start of first logarithmic region 155 // 0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1 156 // 2nd - start of second logarithmic region 157 // 1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8 158 // 3rd - start of third logarithmic region 159 // 2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64 160 // 161 // integer below the block offset entry is an example of 162 // the index of the entry 163 // 164 // Given an address, 165 // Find the index for the address 166 // Find the block offset table entry 167 // Convert the entry to a back slide 168 // (e.g., with today's, offset = 0x81 => 169 // back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8 170 // Move back N (e.g., 8) entries and repeat with the 171 // value of the new entry 172 // 173 size_t start_card = _array->index_for(start); 174 size_t end_card = _array->index_for(end-1); 175 assert(start ==_array->address_for_index(start_card), "Precondition"); 176 assert(end ==_array->address_for_index(end_card)+N_words, "Precondition"); 177 set_remainder_to_point_to_start_incl(start_card, end_card, reducing); // closed interval 178 } 179 180 181 // Unlike the normal convention in this code, the argument here denotes 182 // a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start() 183 // above. 184 void 185 BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card, bool reducing) { 186 187 check_reducing_assertion(reducing); 188 if (start_card > end_card) { 189 return; 190 } 191 assert(start_card > _array->index_for(_bottom), "Cannot be first card"); 192 assert(_array->offset_array(start_card-1) <= N_words, 193 "Offset card has an unexpected value"); 194 size_t start_card_for_region = start_card; 195 u_char offset = max_jubyte; 196 for (int i = 0; i < N_powers; i++) { 197 // -1 so that the the card with the actual offset is counted. Another -1 198 // so that the reach ends in this region and not at the start 199 // of the next. 200 size_t reach = start_card - 1 + (power_to_cards_back(i+1) - 1); 201 offset = N_words + i; 202 if (reach >= end_card) { 203 _array->set_offset_array(start_card_for_region, end_card, offset, reducing); 204 start_card_for_region = reach + 1; 205 break; 206 } 207 _array->set_offset_array(start_card_for_region, reach, offset, reducing); 208 start_card_for_region = reach + 1; 209 } 210 assert(start_card_for_region > end_card, "Sanity check"); 211 DEBUG_ONLY(check_all_cards(start_card, end_card);) 212 } 213 214 // The card-interval [start_card, end_card] is a closed interval; this 215 // is an expensive check -- use with care and only under protection of 216 // suitable flag. 217 void BlockOffsetArray::check_all_cards(size_t start_card, size_t end_card) const { 218 219 if (end_card < start_card) { 220 return; 221 } 222 guarantee(_array->offset_array(start_card) == N_words, "Wrong value in second card"); 223 u_char last_entry = N_words; 224 for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) { 225 u_char entry = _array->offset_array(c); 226 guarantee(entry >= last_entry, "Monotonicity"); 227 if (c - start_card > power_to_cards_back(1)) { 228 guarantee(entry > N_words, "Should be in logarithmic region"); 229 } 230 size_t backskip = entry_to_cards_back(entry); 231 size_t landing_card = c - backskip; 232 guarantee(landing_card >= (start_card - 1), "Inv"); 233 if (landing_card >= start_card) { 234 guarantee(_array->offset_array(landing_card) <= entry, "Monotonicity"); 235 } else { 236 guarantee(landing_card == (start_card - 1), "Tautology"); 237 // Note that N_words is the maximum offset value 238 guarantee(_array->offset_array(landing_card) <= N_words, "Offset value"); 239 } 240 last_entry = entry; // remember for monotonicity test 241 } 242 } 243 244 245 void 246 BlockOffsetArray::alloc_block(HeapWord* blk_start, HeapWord* blk_end) { 247 assert(blk_start != NULL && blk_end > blk_start, 248 "phantom block"); 249 single_block(blk_start, blk_end); 250 } 251 252 // Action_mark - update the BOT for the block [blk_start, blk_end). 253 // Current typical use is for splitting a block. 254 // Action_single - udpate the BOT for an allocation. 255 // Action_verify - BOT verification. 256 void 257 BlockOffsetArray::do_block_internal(HeapWord* blk_start, 258 HeapWord* blk_end, 259 Action action, bool reducing) { 260 assert(Universe::heap()->is_in_reserved(blk_start), 261 "reference must be into the heap"); 262 assert(Universe::heap()->is_in_reserved(blk_end-1), 263 "limit must be within the heap"); 264 // This is optimized to make the test fast, assuming we only rarely 265 // cross boundaries. 266 uintptr_t end_ui = (uintptr_t)(blk_end - 1); 267 uintptr_t start_ui = (uintptr_t)blk_start; 268 // Calculate the last card boundary preceding end of blk 269 intptr_t boundary_before_end = (intptr_t)end_ui; 270 clear_bits(boundary_before_end, right_n_bits(LogN)); 271 if (start_ui <= (uintptr_t)boundary_before_end) { 272 // blk starts at or crosses a boundary 273 // Calculate index of card on which blk begins 274 size_t start_index = _array->index_for(blk_start); 275 // Index of card on which blk ends 276 size_t end_index = _array->index_for(blk_end - 1); 277 // Start address of card on which blk begins 278 HeapWord* boundary = _array->address_for_index(start_index); 279 assert(boundary <= blk_start, "blk should start at or after boundary"); 280 if (blk_start != boundary) { 281 // blk starts strictly after boundary 282 // adjust card boundary and start_index forward to next card 283 boundary += N_words; 284 start_index++; 285 } 286 assert(start_index <= end_index, "monotonicity of index_for()"); 287 assert(boundary <= (HeapWord*)boundary_before_end, "tautology"); 288 switch (action) { 289 case Action_mark: { 290 if (init_to_zero()) { 291 _array->set_offset_array(start_index, boundary, blk_start, reducing); 292 break; 293 } // Else fall through to the next case 294 } 295 case Action_single: { 296 _array->set_offset_array(start_index, boundary, blk_start, reducing); 297 // We have finished marking the "offset card". We need to now 298 // mark the subsequent cards that this blk spans. 299 if (start_index < end_index) { 300 HeapWord* rem_st = _array->address_for_index(start_index) + N_words; 301 HeapWord* rem_end = _array->address_for_index(end_index) + N_words; 302 set_remainder_to_point_to_start(rem_st, rem_end, reducing); 303 } 304 break; 305 } 306 case Action_check: { 307 _array->check_offset_array(start_index, boundary, blk_start); 308 // We have finished checking the "offset card". We need to now 309 // check the subsequent cards that this blk spans. 310 check_all_cards(start_index + 1, end_index); 311 break; 312 } 313 default: 314 ShouldNotReachHere(); 315 } 316 } 317 } 318 319 // The range [blk_start, blk_end) represents a single contiguous block 320 // of storage; modify the block offset table to represent this 321 // information; Right-open interval: [blk_start, blk_end) 322 // NOTE: this method does _not_ adjust _unallocated_block. 323 void 324 BlockOffsetArray::single_block(HeapWord* blk_start, 325 HeapWord* blk_end) { 326 do_block_internal(blk_start, blk_end, Action_single); 327 } 328 329 void BlockOffsetArray::verify() const { 330 // For each entry in the block offset table, verify that 331 // the entry correctly finds the start of an object at the 332 // first address covered by the block or to the left of that 333 // first address. 334 335 size_t next_index = 1; 336 size_t last_index = last_active_index(); 337 338 // Use for debugging. Initialize to NULL to distinguish the 339 // first iteration through the while loop. 340 HeapWord* last_p = NULL; 341 HeapWord* last_start = NULL; 342 oop last_o = NULL; 343 344 while (next_index <= last_index) { 345 // Use an address past the start of the address for 346 // the entry. 347 HeapWord* p = _array->address_for_index(next_index) + 1; 348 if (p >= _end) { 349 // That's all of the allocated block table. 350 return; 351 } 352 // block_start() asserts that start <= p. 353 HeapWord* start = block_start(p); 354 // First check if the start is an allocated block and only 355 // then if it is a valid object. 356 oop o = oop(start); 357 assert(!Universe::is_fully_initialized() || 358 _sp->is_free_block(start) || 359 o->is_oop_or_null(), "Bad object was found"); 360 next_index++; 361 last_p = p; 362 last_start = start; 363 last_o = o; 364 } 365 } 366 367 ////////////////////////////////////////////////////////////////////// 368 // BlockOffsetArrayNonContigSpace 369 ////////////////////////////////////////////////////////////////////// 370 371 // The block [blk_start, blk_end) has been allocated; 372 // adjust the block offset table to represent this information; 373 // NOTE: Clients of BlockOffsetArrayNonContigSpace: consider using 374 // the somewhat more lightweight split_block() or 375 // (when init_to_zero()) mark_block() wherever possible. 376 // right-open interval: [blk_start, blk_end) 377 void 378 BlockOffsetArrayNonContigSpace::alloc_block(HeapWord* blk_start, 379 HeapWord* blk_end) { 380 assert(blk_start != NULL && blk_end > blk_start, 381 "phantom block"); 382 single_block(blk_start, blk_end); 383 allocated(blk_start, blk_end); 384 } 385 386 // Adjust BOT to show that a previously whole block has been split 387 // into two. We verify the BOT for the first part (prefix) and 388 // update the BOT for the second part (suffix). 389 // blk is the start of the block 390 // blk_size is the size of the original block 391 // left_blk_size is the size of the first part of the split 392 void BlockOffsetArrayNonContigSpace::split_block(HeapWord* blk, 393 size_t blk_size, 394 size_t left_blk_size) { 395 // Verify that the BOT shows [blk, blk + blk_size) to be one block. 396 verify_single_block(blk, blk_size); 397 // Update the BOT to indicate that [blk + left_blk_size, blk + blk_size) 398 // is one single block. 399 assert(blk_size > 0, "Should be positive"); 400 assert(left_blk_size > 0, "Should be positive"); 401 assert(left_blk_size < blk_size, "Not a split"); 402 403 // Start addresses of prefix block and suffix block. 404 HeapWord* pref_addr = blk; 405 HeapWord* suff_addr = blk + left_blk_size; 406 HeapWord* end_addr = blk + blk_size; 407 408 // Indices for starts of prefix block and suffix block. 409 size_t pref_index = _array->index_for(pref_addr); 410 if (_array->address_for_index(pref_index) != pref_addr) { 411 // pref_addr does not begin pref_index 412 pref_index++; 413 } 414 415 size_t suff_index = _array->index_for(suff_addr); 416 if (_array->address_for_index(suff_index) != suff_addr) { 417 // suff_addr does not begin suff_index 418 suff_index++; 419 } 420 421 // Definition: A block B, denoted [B_start, B_end) __starts__ 422 // a card C, denoted [C_start, C_end), where C_start and C_end 423 // are the heap addresses that card C covers, iff 424 // B_start <= C_start < B_end. 425 // 426 // We say that a card C "is started by" a block B, iff 427 // B "starts" C. 428 // 429 // Note that the cardinality of the set of cards {C} 430 // started by a block B can be 0, 1, or more. 431 // 432 // Below, pref_index and suff_index are, respectively, the 433 // first (least) card indices that the prefix and suffix of 434 // the split start; end_index is one more than the index of 435 // the last (greatest) card that blk starts. 436 size_t end_index = _array->index_for(end_addr - 1) + 1; 437 438 // Calculate the # cards that the prefix and suffix affect. 439 size_t num_pref_cards = suff_index - pref_index; 440 441 size_t num_suff_cards = end_index - suff_index; 442 // Change the cards that need changing 443 if (num_suff_cards > 0) { 444 HeapWord* boundary = _array->address_for_index(suff_index); 445 // Set the offset card for suffix block 446 _array->set_offset_array(suff_index, boundary, suff_addr, true /* reducing */); 447 // Change any further cards that need changing in the suffix 448 if (num_pref_cards > 0) { 449 if (num_pref_cards >= num_suff_cards) { 450 // Unilaterally fix all of the suffix cards: closed card 451 // index interval in args below. 452 set_remainder_to_point_to_start_incl(suff_index + 1, end_index - 1, true /* reducing */); 453 } else { 454 // Unilaterally fix the first (num_pref_cards - 1) following 455 // the "offset card" in the suffix block. 456 set_remainder_to_point_to_start_incl(suff_index + 1, 457 suff_index + num_pref_cards - 1, true /* reducing */); 458 // Fix the appropriate cards in the remainder of the 459 // suffix block -- these are the last num_pref_cards 460 // cards in each power block of the "new" range plumbed 461 // from suff_addr. 462 bool more = true; 463 uint i = 1; 464 while (more && (i < N_powers)) { 465 size_t back_by = power_to_cards_back(i); 466 size_t right_index = suff_index + back_by - 1; 467 size_t left_index = right_index - num_pref_cards + 1; 468 if (right_index >= end_index - 1) { // last iteration 469 right_index = end_index - 1; 470 more = false; 471 } 472 if (back_by > num_pref_cards) { 473 // Fill in the remainder of this "power block", if it 474 // is non-null. 475 if (left_index <= right_index) { 476 _array->set_offset_array(left_index, right_index, 477 N_words + i - 1, true /* reducing */); 478 } else { 479 more = false; // we are done 480 } 481 i++; 482 break; 483 } 484 i++; 485 } 486 while (more && (i < N_powers)) { 487 size_t back_by = power_to_cards_back(i); 488 size_t right_index = suff_index + back_by - 1; 489 size_t left_index = right_index - num_pref_cards + 1; 490 if (right_index >= end_index - 1) { // last iteration 491 right_index = end_index - 1; 492 if (left_index > right_index) { 493 break; 494 } 495 more = false; 496 } 497 assert(left_index <= right_index, "Error"); 498 _array->set_offset_array(left_index, right_index, N_words + i - 1, true /* reducing */); 499 i++; 500 } 501 } 502 } // else no more cards to fix in suffix 503 } // else nothing needs to be done 504 // Verify that we did the right thing 505 verify_single_block(pref_addr, left_blk_size); 506 verify_single_block(suff_addr, blk_size - left_blk_size); 507 } 508 509 510 // Mark the BOT such that if [blk_start, blk_end) straddles a card 511 // boundary, the card following the first such boundary is marked 512 // with the appropriate offset. 513 // NOTE: this method does _not_ adjust _unallocated_block or 514 // any cards subsequent to the first one. 515 void 516 BlockOffsetArrayNonContigSpace::mark_block(HeapWord* blk_start, 517 HeapWord* blk_end, bool reducing) { 518 do_block_internal(blk_start, blk_end, Action_mark, reducing); 519 } 520 521 HeapWord* BlockOffsetArrayNonContigSpace::block_start_unsafe( 522 const void* addr) const { 523 assert(_array->offset_array(0) == 0, "objects can't cross covered areas"); 524 assert(_bottom <= addr && addr < _end, 525 "addr must be covered by this Array"); 526 // Must read this exactly once because it can be modified by parallel 527 // allocation. 528 HeapWord* ub = _unallocated_block; 529 if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) { 530 assert(ub < _end, "tautology (see above)"); 531 return ub; 532 } 533 534 // Otherwise, find the block start using the table. 535 size_t index = _array->index_for(addr); 536 HeapWord* q = _array->address_for_index(index); 537 538 uint offset = _array->offset_array(index); // Extend u_char to uint. 539 while (offset >= N_words) { 540 // The excess of the offset from N_words indicates a power of Base 541 // to go back by. 542 size_t n_cards_back = entry_to_cards_back(offset); 543 q -= (N_words * n_cards_back); 544 assert(q >= _sp->bottom(), "Went below bottom!"); 545 index -= n_cards_back; 546 offset = _array->offset_array(index); 547 } 548 assert(offset < N_words, "offset too large"); 549 index--; 550 q -= offset; 551 HeapWord* n = q; 552 553 while (n <= addr) { 554 debug_only(HeapWord* last = q); // for debugging 555 q = n; 556 n += _sp->block_size(n); 557 assert(n > q, err_msg("Looping at: " INTPTR_FORMAT, n)); 558 } 559 assert(q <= addr, err_msg("wrong order for current (" INTPTR_FORMAT ") <= arg (" INTPTR_FORMAT ")", q, addr)); 560 assert(addr <= n, err_msg("wrong order for arg (" INTPTR_FORMAT ") <= next (" INTPTR_FORMAT ")", addr, n)); 561 return q; 562 } 563 564 HeapWord* BlockOffsetArrayNonContigSpace::block_start_careful( 565 const void* addr) const { 566 assert(_array->offset_array(0) == 0, "objects can't cross covered areas"); 567 568 assert(_bottom <= addr && addr < _end, 569 "addr must be covered by this Array"); 570 // Must read this exactly once because it can be modified by parallel 571 // allocation. 572 HeapWord* ub = _unallocated_block; 573 if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) { 574 assert(ub < _end, "tautology (see above)"); 575 return ub; 576 } 577 578 // Otherwise, find the block start using the table, but taking 579 // care (cf block_start_unsafe() above) not to parse any objects/blocks 580 // on the cards themsleves. 581 size_t index = _array->index_for(addr); 582 assert(_array->address_for_index(index) == addr, 583 "arg should be start of card"); 584 585 HeapWord* q = (HeapWord*)addr; 586 uint offset; 587 do { 588 offset = _array->offset_array(index); 589 if (offset < N_words) { 590 q -= offset; 591 } else { 592 size_t n_cards_back = entry_to_cards_back(offset); 593 q -= (n_cards_back * N_words); 594 index -= n_cards_back; 595 } 596 } while (offset >= N_words); 597 assert(q <= addr, "block start should be to left of arg"); 598 return q; 599 } 600 601 #ifndef PRODUCT 602 // Verification & debugging - ensure that the offset table reflects the fact 603 // that the block [blk_start, blk_end) or [blk, blk + size) is a 604 // single block of storage. NOTE: can't const this because of 605 // call to non-const do_block_internal() below. 606 void BlockOffsetArrayNonContigSpace::verify_single_block( 607 HeapWord* blk_start, HeapWord* blk_end) { 608 if (VerifyBlockOffsetArray) { 609 do_block_internal(blk_start, blk_end, Action_check); 610 } 611 } 612 613 void BlockOffsetArrayNonContigSpace::verify_single_block( 614 HeapWord* blk, size_t size) { 615 verify_single_block(blk, blk + size); 616 } 617 618 // Verify that the given block is before _unallocated_block 619 void BlockOffsetArrayNonContigSpace::verify_not_unallocated( 620 HeapWord* blk_start, HeapWord* blk_end) const { 621 if (BlockOffsetArrayUseUnallocatedBlock) { 622 assert(blk_start < blk_end, "Block inconsistency?"); 623 assert(blk_end <= _unallocated_block, "_unallocated_block problem"); 624 } 625 } 626 627 void BlockOffsetArrayNonContigSpace::verify_not_unallocated( 628 HeapWord* blk, size_t size) const { 629 verify_not_unallocated(blk, blk + size); 630 } 631 #endif // PRODUCT 632 633 size_t BlockOffsetArrayNonContigSpace::last_active_index() const { 634 if (_unallocated_block == _bottom) { 635 return 0; 636 } else { 637 return _array->index_for(_unallocated_block - 1); 638 } 639 } 640 641 ////////////////////////////////////////////////////////////////////// 642 // BlockOffsetArrayContigSpace 643 ////////////////////////////////////////////////////////////////////// 644 645 HeapWord* BlockOffsetArrayContigSpace::block_start_unsafe(const void* addr) const { 646 assert(_array->offset_array(0) == 0, "objects can't cross covered areas"); 647 648 // Otherwise, find the block start using the table. 649 assert(_bottom <= addr && addr < _end, 650 "addr must be covered by this Array"); 651 size_t index = _array->index_for(addr); 652 // We must make sure that the offset table entry we use is valid. If 653 // "addr" is past the end, start at the last known one and go forward. 654 index = MIN2(index, _next_offset_index-1); 655 HeapWord* q = _array->address_for_index(index); 656 657 uint offset = _array->offset_array(index); // Extend u_char to uint. 658 while (offset > N_words) { 659 // The excess of the offset from N_words indicates a power of Base 660 // to go back by. 661 size_t n_cards_back = entry_to_cards_back(offset); 662 q -= (N_words * n_cards_back); 663 assert(q >= _sp->bottom(), "Went below bottom!"); 664 index -= n_cards_back; 665 offset = _array->offset_array(index); 666 } 667 while (offset == N_words) { 668 assert(q >= _sp->bottom(), "Went below bottom!"); 669 q -= N_words; 670 index--; 671 offset = _array->offset_array(index); 672 } 673 assert(offset < N_words, "offset too large"); 674 q -= offset; 675 HeapWord* n = q; 676 677 while (n <= addr) { 678 debug_only(HeapWord* last = q); // for debugging 679 q = n; 680 n += _sp->block_size(n); 681 } 682 assert(q <= addr, "wrong order for current and arg"); 683 assert(addr <= n, "wrong order for arg and next"); 684 return q; 685 } 686 687 // 688 // _next_offset_threshold 689 // | _next_offset_index 690 // v v 691 // +-------+-------+-------+-------+-------+ 692 // | i-1 | i | i+1 | i+2 | i+3 | 693 // +-------+-------+-------+-------+-------+ 694 // ( ^ ] 695 // block-start 696 // 697 698 void BlockOffsetArrayContigSpace::alloc_block_work(HeapWord* blk_start, 699 HeapWord* blk_end) { 700 assert(blk_start != NULL && blk_end > blk_start, 701 "phantom block"); 702 assert(blk_end > _next_offset_threshold, 703 "should be past threshold"); 704 assert(blk_start <= _next_offset_threshold, 705 "blk_start should be at or before threshold"); 706 assert(pointer_delta(_next_offset_threshold, blk_start) <= N_words, 707 "offset should be <= BlockOffsetSharedArray::N"); 708 assert(Universe::heap()->is_in_reserved(blk_start), 709 "reference must be into the heap"); 710 assert(Universe::heap()->is_in_reserved(blk_end-1), 711 "limit must be within the heap"); 712 assert(_next_offset_threshold == 713 _array->_reserved.start() + _next_offset_index*N_words, 714 "index must agree with threshold"); 715 716 debug_only(size_t orig_next_offset_index = _next_offset_index;) 717 718 // Mark the card that holds the offset into the block. Note 719 // that _next_offset_index and _next_offset_threshold are not 720 // updated until the end of this method. 721 _array->set_offset_array(_next_offset_index, 722 _next_offset_threshold, 723 blk_start); 724 725 // We need to now mark the subsequent cards that this blk spans. 726 727 // Index of card on which blk ends. 728 size_t end_index = _array->index_for(blk_end - 1); 729 730 // Are there more cards left to be updated? 731 if (_next_offset_index + 1 <= end_index) { 732 HeapWord* rem_st = _array->address_for_index(_next_offset_index + 1); 733 // Calculate rem_end this way because end_index 734 // may be the last valid index in the covered region. 735 HeapWord* rem_end = _array->address_for_index(end_index) + N_words; 736 set_remainder_to_point_to_start(rem_st, rem_end); 737 } 738 739 // _next_offset_index and _next_offset_threshold updated here. 740 _next_offset_index = end_index + 1; 741 // Calculate _next_offset_threshold this way because end_index 742 // may be the last valid index in the covered region. 743 _next_offset_threshold = _array->address_for_index(end_index) + N_words; 744 assert(_next_offset_threshold >= blk_end, "Incorrect offset threshold"); 745 746 #ifdef ASSERT 747 // The offset can be 0 if the block starts on a boundary. That 748 // is checked by an assertion above. 749 size_t start_index = _array->index_for(blk_start); 750 HeapWord* boundary = _array->address_for_index(start_index); 751 assert((_array->offset_array(orig_next_offset_index) == 0 && 752 blk_start == boundary) || 753 (_array->offset_array(orig_next_offset_index) > 0 && 754 _array->offset_array(orig_next_offset_index) <= N_words), 755 "offset array should have been set"); 756 for (size_t j = orig_next_offset_index + 1; j <= end_index; j++) { 757 assert(_array->offset_array(j) > 0 && 758 _array->offset_array(j) <= (u_char) (N_words+N_powers-1), 759 "offset array should have been set"); 760 } 761 #endif 762 } 763 764 HeapWord* BlockOffsetArrayContigSpace::initialize_threshold() { 765 assert(!Universe::heap()->is_in_reserved(_array->_offset_array), 766 "just checking"); 767 _next_offset_index = _array->index_for(_bottom); 768 _next_offset_index++; 769 _next_offset_threshold = 770 _array->address_for_index(_next_offset_index); 771 return _next_offset_threshold; 772 } 773 774 void BlockOffsetArrayContigSpace::zero_bottom_entry() { 775 assert(!Universe::heap()->is_in_reserved(_array->_offset_array), 776 "just checking"); 777 size_t bottom_index = _array->index_for(_bottom); 778 _array->set_offset_array(bottom_index, 0); 779 } 780 781 782 void BlockOffsetArrayContigSpace::serialize(SerializeOopClosure* soc) { 783 if (soc->reading()) { 784 // Null these values so that the serializer won't object to updating them. 785 _next_offset_threshold = NULL; 786 _next_offset_index = 0; 787 } 788 soc->do_ptr(&_next_offset_threshold); 789 soc->do_size_t(&_next_offset_index); 790 } 791 792 size_t BlockOffsetArrayContigSpace::last_active_index() const { 793 size_t result = _next_offset_index - 1; 794 return result >= 0 ? result : 0; 795 }