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