1 /*
2 * Copyright (c) 2001, 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_implementation/g1/g1BlockOffsetTable.inline.hpp"
27 #include "memory/space.hpp"
28 #include "oops/oop.inline.hpp"
29 #include "runtime/java.hpp"
30
31 //////////////////////////////////////////////////////////////////////
32 // G1BlockOffsetSharedArray
33 //////////////////////////////////////////////////////////////////////
34
35 G1BlockOffsetSharedArray::G1BlockOffsetSharedArray(MemRegion reserved,
36 size_t init_word_size) :
37 _reserved(reserved), _end(NULL)
38 {
39 size_t size = compute_size(reserved.word_size());
40 ReservedSpace rs(ReservedSpace::allocation_align_size_up(size));
41 if (!rs.is_reserved()) {
42 vm_exit_during_initialization("Could not reserve enough space for heap offset array");
43 }
44 if (!_vs.initialize(rs, 0)) {
45 vm_exit_during_initialization("Could not reserve enough space for heap offset array");
46 }
47 _offset_array = (u_char*)_vs.low_boundary();
48 resize(init_word_size);
49 if (TraceBlockOffsetTable) {
50 gclog_or_tty->print_cr("G1BlockOffsetSharedArray::G1BlockOffsetSharedArray: ");
51 gclog_or_tty->print_cr(" "
52 " rs.base(): " INTPTR_FORMAT
53 " rs.size(): " INTPTR_FORMAT
54 " rs end(): " INTPTR_FORMAT,
55 rs.base(), rs.size(), rs.base() + rs.size());
56 gclog_or_tty->print_cr(" "
57 " _vs.low_boundary(): " INTPTR_FORMAT
58 " _vs.high_boundary(): " INTPTR_FORMAT,
59 _vs.low_boundary(),
60 _vs.high_boundary());
61 }
62 }
63
64 void G1BlockOffsetSharedArray::resize(size_t new_word_size) {
65 assert(new_word_size <= _reserved.word_size(), "Resize larger than reserved");
66 size_t new_size = compute_size(new_word_size);
67 size_t old_size = _vs.committed_size();
68 size_t delta;
69 char* high = _vs.high();
70 _end = _reserved.start() + new_word_size;
71 if (new_size > old_size) {
72 delta = ReservedSpace::page_align_size_up(new_size - old_size);
73 assert(delta > 0, "just checking");
74 if (!_vs.expand_by(delta)) {
75 // Do better than this for Merlin
76 vm_exit_out_of_memory(delta, "offset table expansion");
77 }
78 assert(_vs.high() == high + delta, "invalid expansion");
79 // Initialization of the contents is left to the
80 // G1BlockOffsetArray that uses it.
81 } else {
82 delta = ReservedSpace::page_align_size_down(old_size - new_size);
83 if (delta == 0) return;
84 _vs.shrink_by(delta);
85 assert(_vs.high() == high - delta, "invalid expansion");
86 }
87 }
88
89 bool G1BlockOffsetSharedArray::is_card_boundary(HeapWord* p) const {
90 assert(p >= _reserved.start(), "just checking");
91 size_t delta = pointer_delta(p, _reserved.start());
92 return (delta & right_n_bits(LogN_words)) == (size_t)NoBits;
93 }
94
95
96 //////////////////////////////////////////////////////////////////////
97 // G1BlockOffsetArray
98 //////////////////////////////////////////////////////////////////////
99
100 G1BlockOffsetArray::G1BlockOffsetArray(G1BlockOffsetSharedArray* array,
101 MemRegion mr, bool init_to_zero) :
102 G1BlockOffsetTable(mr.start(), mr.end()),
103 _unallocated_block(_bottom),
104 _array(array), _csp(NULL),
105 _init_to_zero(init_to_zero) {
106 assert(_bottom <= _end, "arguments out of order");
107 if (!_init_to_zero) {
108 // initialize cards to point back to mr.start()
109 set_remainder_to_point_to_start(mr.start() + N_words, mr.end());
110 _array->set_offset_array(0, 0); // set first card to 0
111 }
112 }
113
114 void G1BlockOffsetArray::set_space(Space* sp) {
115 _sp = sp;
116 _csp = sp->toContiguousSpace();
117 }
118
119 // The arguments follow the normal convention of denoting
120 // a right-open interval: [start, end)
121 void
122 G1BlockOffsetArray:: set_remainder_to_point_to_start(HeapWord* start, HeapWord* end) {
123
124 if (start >= end) {
125 // The start address is equal to the end address (or to
126 // the right of the end address) so there are not cards
127 // that need to be updated..
128 return;
129 }
130
131 // Write the backskip value for each region.
132 //
133 // offset
134 // card 2nd 3rd
135 // | +- 1st | |
136 // v v v v
137 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-
138 // |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ...
139 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-
140 // 11 19 75
141 // 12
142 //
143 // offset card is the card that points to the start of an object
144 // x - offset value of offset card
145 // 1st - start of first logarithmic region
146 // 0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1
147 // 2nd - start of second logarithmic region
148 // 1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8
149 // 3rd - start of third logarithmic region
150 // 2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64
151 //
152 // integer below the block offset entry is an example of
153 // the index of the entry
154 //
155 // Given an address,
156 // Find the index for the address
157 // Find the block offset table entry
158 // Convert the entry to a back slide
159 // (e.g., with today's, offset = 0x81 =>
160 // back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8
161 // Move back N (e.g., 8) entries and repeat with the
162 // value of the new entry
163 //
164 size_t start_card = _array->index_for(start);
165 size_t end_card = _array->index_for(end-1);
166 assert(start ==_array->address_for_index(start_card), "Precondition");
167 assert(end ==_array->address_for_index(end_card)+N_words, "Precondition");
168 set_remainder_to_point_to_start_incl(start_card, end_card); // closed interval
169 }
170
171 // Unlike the normal convention in this code, the argument here denotes
172 // a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start()
173 // above.
174 void
175 G1BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card) {
176 if (start_card > end_card) {
177 return;
178 }
179 assert(start_card > _array->index_for(_bottom), "Cannot be first card");
180 assert(_array->offset_array(start_card-1) <= N_words,
181 "Offset card has an unexpected value");
182 size_t start_card_for_region = start_card;
183 u_char offset = max_jubyte;
184 for (int i = 0; i < BlockOffsetArray::N_powers; i++) {
185 // -1 so that the the card with the actual offset is counted. Another -1
186 // so that the reach ends in this region and not at the start
187 // of the next.
188 size_t reach = start_card - 1 + (BlockOffsetArray::power_to_cards_back(i+1) - 1);
189 offset = N_words + i;
190 if (reach >= end_card) {
191 _array->set_offset_array(start_card_for_region, end_card, offset);
192 start_card_for_region = reach + 1;
193 break;
194 }
195 _array->set_offset_array(start_card_for_region, reach, offset);
196 start_card_for_region = reach + 1;
197 }
198 assert(start_card_for_region > end_card, "Sanity check");
199 DEBUG_ONLY(check_all_cards(start_card, end_card);)
200 }
201
202 // The block [blk_start, blk_end) has been allocated;
203 // adjust the block offset table to represent this information;
204 // right-open interval: [blk_start, blk_end)
205 void
206 G1BlockOffsetArray::alloc_block(HeapWord* blk_start, HeapWord* blk_end) {
207 mark_block(blk_start, blk_end);
208 allocated(blk_start, blk_end);
209 }
210
211 // Adjust BOT to show that a previously whole block has been split
212 // into two.
213 void G1BlockOffsetArray::split_block(HeapWord* blk, size_t blk_size,
214 size_t left_blk_size) {
215 // Verify that the BOT shows [blk, blk + blk_size) to be one block.
216 verify_single_block(blk, blk_size);
217 // Update the BOT to indicate that [blk + left_blk_size, blk + blk_size)
218 // is one single block.
219 mark_block(blk + left_blk_size, blk + blk_size);
220 }
221
222
223 // Action_mark - update the BOT for the block [blk_start, blk_end).
224 // Current typical use is for splitting a block.
225 // Action_single - udpate the BOT for an allocation.
226 // Action_verify - BOT verification.
227 void G1BlockOffsetArray::do_block_internal(HeapWord* blk_start,
228 HeapWord* blk_end,
229 Action action) {
230 assert(Universe::heap()->is_in_reserved(blk_start),
231 "reference must be into the heap");
232 assert(Universe::heap()->is_in_reserved(blk_end-1),
233 "limit must be within the heap");
234 // This is optimized to make the test fast, assuming we only rarely
235 // cross boundaries.
236 uintptr_t end_ui = (uintptr_t)(blk_end - 1);
237 uintptr_t start_ui = (uintptr_t)blk_start;
238 // Calculate the last card boundary preceding end of blk
239 intptr_t boundary_before_end = (intptr_t)end_ui;
240 clear_bits(boundary_before_end, right_n_bits(LogN));
241 if (start_ui <= (uintptr_t)boundary_before_end) {
242 // blk starts at or crosses a boundary
243 // Calculate index of card on which blk begins
244 size_t start_index = _array->index_for(blk_start);
245 // Index of card on which blk ends
246 size_t end_index = _array->index_for(blk_end - 1);
247 // Start address of card on which blk begins
248 HeapWord* boundary = _array->address_for_index(start_index);
249 assert(boundary <= blk_start, "blk should start at or after boundary");
250 if (blk_start != boundary) {
251 // blk starts strictly after boundary
252 // adjust card boundary and start_index forward to next card
253 boundary += N_words;
254 start_index++;
255 }
256 assert(start_index <= end_index, "monotonicity of index_for()");
257 assert(boundary <= (HeapWord*)boundary_before_end, "tautology");
258 switch (action) {
259 case Action_mark: {
260 if (init_to_zero()) {
261 _array->set_offset_array(start_index, boundary, blk_start);
262 break;
263 } // Else fall through to the next case
264 }
265 case Action_single: {
266 _array->set_offset_array(start_index, boundary, blk_start);
267 // We have finished marking the "offset card". We need to now
268 // mark the subsequent cards that this blk spans.
269 if (start_index < end_index) {
270 HeapWord* rem_st = _array->address_for_index(start_index) + N_words;
271 HeapWord* rem_end = _array->address_for_index(end_index) + N_words;
272 set_remainder_to_point_to_start(rem_st, rem_end);
273 }
274 break;
275 }
276 case Action_check: {
277 _array->check_offset_array(start_index, boundary, blk_start);
278 // We have finished checking the "offset card". We need to now
279 // check the subsequent cards that this blk spans.
280 check_all_cards(start_index + 1, end_index);
281 break;
282 }
283 default:
284 ShouldNotReachHere();
285 }
286 }
287 }
288
289 // The card-interval [start_card, end_card] is a closed interval; this
290 // is an expensive check -- use with care and only under protection of
291 // suitable flag.
292 void G1BlockOffsetArray::check_all_cards(size_t start_card, size_t end_card) const {
293
294 if (end_card < start_card) {
295 return;
296 }
297 guarantee(_array->offset_array(start_card) == N_words, "Wrong value in second card");
298 for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) {
299 u_char entry = _array->offset_array(c);
300 if (c - start_card > BlockOffsetArray::power_to_cards_back(1)) {
301 guarantee(entry > N_words, "Should be in logarithmic region");
302 }
303 size_t backskip = BlockOffsetArray::entry_to_cards_back(entry);
304 size_t landing_card = c - backskip;
305 guarantee(landing_card >= (start_card - 1), "Inv");
306 if (landing_card >= start_card) {
307 guarantee(_array->offset_array(landing_card) <= entry, "monotonicity");
308 } else {
309 guarantee(landing_card == start_card - 1, "Tautology");
310 guarantee(_array->offset_array(landing_card) <= N_words, "Offset value");
311 }
312 }
313 }
314
315 // The range [blk_start, blk_end) represents a single contiguous block
316 // of storage; modify the block offset table to represent this
317 // information; Right-open interval: [blk_start, blk_end)
318 // NOTE: this method does _not_ adjust _unallocated_block.
319 void
320 G1BlockOffsetArray::single_block(HeapWord* blk_start, HeapWord* blk_end) {
321 do_block_internal(blk_start, blk_end, Action_single);
322 }
323
324 // Mark the BOT such that if [blk_start, blk_end) straddles a card
325 // boundary, the card following the first such boundary is marked
326 // with the appropriate offset.
327 // NOTE: this method does _not_ adjust _unallocated_block or
328 // any cards subsequent to the first one.
329 void
330 G1BlockOffsetArray::mark_block(HeapWord* blk_start, HeapWord* blk_end) {
331 do_block_internal(blk_start, blk_end, Action_mark);
332 }
333
334 void G1BlockOffsetArray::join_blocks(HeapWord* blk1, HeapWord* blk2) {
335 HeapWord* blk1_start = Universe::heap()->block_start(blk1);
336 HeapWord* blk2_start = Universe::heap()->block_start(blk2);
337 assert(blk1 == blk1_start && blk2 == blk2_start,
338 "Must be block starts.");
339 assert(blk1 + _sp->block_size(blk1) == blk2, "Must be contiguous.");
340 size_t blk1_start_index = _array->index_for(blk1);
341 size_t blk2_start_index = _array->index_for(blk2);
342 assert(blk1_start_index <= blk2_start_index, "sanity");
343 HeapWord* blk2_card_start = _array->address_for_index(blk2_start_index);
344 if (blk2 == blk2_card_start) {
345 // blk2 starts a card. Does blk1 start on the prevous card, or futher
346 // back?
347 assert(blk1_start_index < blk2_start_index, "must be lower card.");
348 if (blk1_start_index + 1 == blk2_start_index) {
349 // previous card; new value for blk2 card is size of blk1.
350 _array->set_offset_array(blk2_start_index, (u_char) _sp->block_size(blk1));
351 } else {
352 // Earlier card; go back a card.
353 _array->set_offset_array(blk2_start_index, N_words);
354 }
355 } else {
356 // blk2 does not start a card. Does it cross a card? If not, nothing
357 // to do.
358 size_t blk2_end_index =
359 _array->index_for(blk2 + _sp->block_size(blk2) - 1);
360 assert(blk2_end_index >= blk2_start_index, "sanity");
361 if (blk2_end_index > blk2_start_index) {
362 // Yes, it crosses a card. The value for the next card must change.
363 if (blk1_start_index + 1 == blk2_start_index) {
364 // previous card; new value for second blk2 card is size of blk1.
365 _array->set_offset_array(blk2_start_index + 1,
366 (u_char) _sp->block_size(blk1));
367 } else {
368 // Earlier card; go back a card.
369 _array->set_offset_array(blk2_start_index + 1, N_words);
370 }
371 }
372 }
373 }
374
375 HeapWord* G1BlockOffsetArray::block_start_unsafe(const void* addr) {
376 assert(_bottom <= addr && addr < _end,
377 "addr must be covered by this Array");
378 // Must read this exactly once because it can be modified by parallel
379 // allocation.
380 HeapWord* ub = _unallocated_block;
381 if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) {
382 assert(ub < _end, "tautology (see above)");
383 return ub;
384 }
385 // Otherwise, find the block start using the table.
386 HeapWord* q = block_at_or_preceding(addr, false, 0);
387 return forward_to_block_containing_addr(q, addr);
388 }
389
390 // This duplicates a little code from the above: unavoidable.
391 HeapWord*
392 G1BlockOffsetArray::block_start_unsafe_const(const void* addr) const {
393 assert(_bottom <= addr && addr < _end,
394 "addr must be covered by this Array");
395 // Must read this exactly once because it can be modified by parallel
396 // allocation.
397 HeapWord* ub = _unallocated_block;
398 if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) {
399 assert(ub < _end, "tautology (see above)");
400 return ub;
401 }
402 // Otherwise, find the block start using the table.
403 HeapWord* q = block_at_or_preceding(addr, false, 0);
404 HeapWord* n = q + _sp->block_size(q);
405 return forward_to_block_containing_addr_const(q, n, addr);
406 }
407
408
409 HeapWord*
410 G1BlockOffsetArray::forward_to_block_containing_addr_slow(HeapWord* q,
411 HeapWord* n,
412 const void* addr) {
413 // We're not in the normal case. We need to handle an important subcase
414 // here: LAB allocation. An allocation previously recorded in the
415 // offset table was actually a lab allocation, and was divided into
416 // several objects subsequently. Fix this situation as we answer the
417 // query, by updating entries as we cross them.
418
419 // If the fist object's end q is at the card boundary. Start refining
420 // with the corresponding card (the value of the entry will be basically
421 // set to 0). If the object crosses the boundary -- start from the next card.
422 size_t next_index = _array->index_for(n) + !_array->is_card_boundary(n);
423 HeapWord* next_boundary = _array->address_for_index(next_index);
424 if (csp() != NULL) {
425 if (addr >= csp()->top()) return csp()->top();
426 while (next_boundary < addr) {
427 while (n <= next_boundary) {
428 q = n;
429 oop obj = oop(q);
430 if (obj->klass_or_null() == NULL) return q;
431 n += obj->size();
432 }
433 assert(q <= next_boundary && n > next_boundary, "Consequence of loop");
434 // [q, n) is the block that crosses the boundary.
435 alloc_block_work2(&next_boundary, &next_index, q, n);
436 }
437 } else {
438 while (next_boundary < addr) {
439 while (n <= next_boundary) {
440 q = n;
441 oop obj = oop(q);
442 if (obj->klass_or_null() == NULL) return q;
443 n += _sp->block_size(q);
444 }
445 assert(q <= next_boundary && n > next_boundary, "Consequence of loop");
446 // [q, n) is the block that crosses the boundary.
447 alloc_block_work2(&next_boundary, &next_index, q, n);
448 }
449 }
450 return forward_to_block_containing_addr_const(q, n, addr);
451 }
452
453 HeapWord* G1BlockOffsetArray::block_start_careful(const void* addr) const {
454 assert(_array->offset_array(0) == 0, "objects can't cross covered areas");
455
456 assert(_bottom <= addr && addr < _end,
457 "addr must be covered by this Array");
458 // Must read this exactly once because it can be modified by parallel
459 // allocation.
460 HeapWord* ub = _unallocated_block;
461 if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) {
462 assert(ub < _end, "tautology (see above)");
463 return ub;
464 }
465
466 // Otherwise, find the block start using the table, but taking
467 // care (cf block_start_unsafe() above) not to parse any objects/blocks
468 // on the cards themsleves.
469 size_t index = _array->index_for(addr);
470 assert(_array->address_for_index(index) == addr,
471 "arg should be start of card");
472
473 HeapWord* q = (HeapWord*)addr;
474 uint offset;
475 do {
476 offset = _array->offset_array(index--);
477 q -= offset;
478 } while (offset == N_words);
479 assert(q <= addr, "block start should be to left of arg");
480 return q;
481 }
482
483 // Note that the committed size of the covered space may have changed,
484 // so the table size might also wish to change.
485 void G1BlockOffsetArray::resize(size_t new_word_size) {
486 HeapWord* new_end = _bottom + new_word_size;
487 if (_end < new_end && !init_to_zero()) {
488 // verify that the old and new boundaries are also card boundaries
489 assert(_array->is_card_boundary(_end),
490 "_end not a card boundary");
491 assert(_array->is_card_boundary(new_end),
492 "new _end would not be a card boundary");
493 // set all the newly added cards
494 _array->set_offset_array(_end, new_end, N_words);
495 }
496 _end = new_end; // update _end
497 }
498
499 void G1BlockOffsetArray::set_region(MemRegion mr) {
500 _bottom = mr.start();
501 _end = mr.end();
502 }
503
504 //
505 // threshold_
506 // | _index_
507 // v v
508 // +-------+-------+-------+-------+-------+
509 // | i-1 | i | i+1 | i+2 | i+3 |
510 // +-------+-------+-------+-------+-------+
511 // ( ^ ]
512 // block-start
513 //
514 void G1BlockOffsetArray::alloc_block_work2(HeapWord** threshold_, size_t* index_,
515 HeapWord* blk_start, HeapWord* blk_end) {
516 // For efficiency, do copy-in/copy-out.
517 HeapWord* threshold = *threshold_;
518 size_t index = *index_;
519
520 assert(blk_start != NULL && blk_end > blk_start,
521 "phantom block");
522 assert(blk_end > threshold, "should be past threshold");
523 assert(blk_start <= threshold, "blk_start should be at or before threshold");
524 assert(pointer_delta(threshold, blk_start) <= N_words,
525 "offset should be <= BlockOffsetSharedArray::N");
526 assert(Universe::heap()->is_in_reserved(blk_start),
527 "reference must be into the heap");
528 assert(Universe::heap()->is_in_reserved(blk_end-1),
529 "limit must be within the heap");
530 assert(threshold == _array->_reserved.start() + index*N_words,
531 "index must agree with threshold");
532
533 DEBUG_ONLY(size_t orig_index = index;)
534
535 // Mark the card that holds the offset into the block. Note
536 // that _next_offset_index and _next_offset_threshold are not
537 // updated until the end of this method.
538 _array->set_offset_array(index, threshold, blk_start);
539
540 // We need to now mark the subsequent cards that this blk spans.
541
542 // Index of card on which blk ends.
543 size_t end_index = _array->index_for(blk_end - 1);
544
545 // Are there more cards left to be updated?
546 if (index + 1 <= end_index) {
547 HeapWord* rem_st = _array->address_for_index(index + 1);
548 // Calculate rem_end this way because end_index
549 // may be the last valid index in the covered region.
550 HeapWord* rem_end = _array->address_for_index(end_index) + N_words;
551 set_remainder_to_point_to_start(rem_st, rem_end);
552 }
553
554 index = end_index + 1;
555 // Calculate threshold_ this way because end_index
556 // may be the last valid index in the covered region.
557 threshold = _array->address_for_index(end_index) + N_words;
558 assert(threshold >= blk_end, "Incorrect offset threshold");
559
560 // index_ and threshold_ updated here.
561 *threshold_ = threshold;
562 *index_ = index;
563
564 #ifdef ASSERT
565 // The offset can be 0 if the block starts on a boundary. That
566 // is checked by an assertion above.
567 size_t start_index = _array->index_for(blk_start);
568 HeapWord* boundary = _array->address_for_index(start_index);
569 assert((_array->offset_array(orig_index) == 0 &&
570 blk_start == boundary) ||
571 (_array->offset_array(orig_index) > 0 &&
572 _array->offset_array(orig_index) <= N_words),
573 "offset array should have been set");
574 for (size_t j = orig_index + 1; j <= end_index; j++) {
575 assert(_array->offset_array(j) > 0 &&
576 _array->offset_array(j) <=
577 (u_char) (N_words+BlockOffsetArray::N_powers-1),
578 "offset array should have been set");
579 }
580 #endif
581 }
582
583 //////////////////////////////////////////////////////////////////////
584 // G1BlockOffsetArrayContigSpace
585 //////////////////////////////////////////////////////////////////////
586
587 HeapWord*
588 G1BlockOffsetArrayContigSpace::block_start_unsafe(const void* addr) {
589 assert(_bottom <= addr && addr < _end,
590 "addr must be covered by this Array");
591 HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
592 return forward_to_block_containing_addr(q, addr);
593 }
594
595 HeapWord*
596 G1BlockOffsetArrayContigSpace::
597 block_start_unsafe_const(const void* addr) const {
598 assert(_bottom <= addr && addr < _end,
599 "addr must be covered by this Array");
600 HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
601 HeapWord* n = q + _sp->block_size(q);
602 return forward_to_block_containing_addr_const(q, n, addr);
603 }
604
605 G1BlockOffsetArrayContigSpace::
606 G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array,
607 MemRegion mr) :
608 G1BlockOffsetArray(array, mr, true)
609 {
610 _next_offset_threshold = NULL;
611 _next_offset_index = 0;
612 }
613
614 HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold() {
615 assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
616 "just checking");
617 _next_offset_index = _array->index_for(_bottom);
618 _next_offset_index++;
619 _next_offset_threshold =
620 _array->address_for_index(_next_offset_index);
621 return _next_offset_threshold;
622 }
623
624 void G1BlockOffsetArrayContigSpace::zero_bottom_entry() {
625 assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
626 "just checking");
627 size_t bottom_index = _array->index_for(_bottom);
628 assert(_array->address_for_index(bottom_index) == _bottom,
629 "Precondition of call");
630 _array->set_offset_array(bottom_index, 0);
631 }