1 /*
2 * Copyright (c) 1997, 2015, 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 "classfile/systemDictionary.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "gc_implementation/shared/liveRange.hpp"
29 #include "gc_implementation/shared/spaceDecorator.hpp"
30 #include "gc_interface/collectedHeap.inline.hpp"
31 #include "memory/blockOffsetTable.inline.hpp"
32 #include "memory/defNewGeneration.hpp"
33 #include "memory/genCollectedHeap.hpp"
34 #include "memory/space.hpp"
35 #include "memory/space.inline.hpp"
36 #include "memory/universe.inline.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/java.hpp"
39 #include "runtime/atomic.inline.hpp"
40 #include "runtime/prefetch.inline.hpp"
41 #include "runtime/orderAccess.inline.hpp"
42 #include "runtime/safepoint.hpp"
43 #include "utilities/copy.hpp"
44 #include "utilities/globalDefinitions.hpp"
45 #include "utilities/macros.hpp"
46
47 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
48
49 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
50 HeapWord* top_obj) {
51 if (top_obj != NULL) {
52 if (_sp->block_is_obj(top_obj)) {
53 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
54 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
55 // An arrayOop is starting on the dirty card - since we do exact
56 // store checks for objArrays we are done.
57 } else {
58 // Otherwise, it is possible that the object starting on the dirty
59 // card spans the entire card, and that the store happened on a
60 // later card. Figure out where the object ends.
61 // Use the block_size() method of the space over which
62 // the iteration is being done. That space (e.g. CMS) may have
63 // specific requirements on object sizes which will
64 // be reflected in the block_size() method.
65 top = top_obj + oop(top_obj)->size();
66 }
67 }
68 } else {
69 top = top_obj;
70 }
71 } else {
72 assert(top == _sp->end(), "only case where top_obj == NULL");
73 }
74 return top;
75 }
76
77 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
78 HeapWord* bottom,
79 HeapWord* top) {
80 // 1. Blocks may or may not be objects.
81 // 2. Even when a block_is_obj(), it may not entirely
82 // occupy the block if the block quantum is larger than
83 // the object size.
84 // We can and should try to optimize by calling the non-MemRegion
85 // version of oop_iterate() for all but the extremal objects
86 // (for which we need to call the MemRegion version of
87 // oop_iterate()) To be done post-beta XXX
88 for (; bottom < top; bottom += _sp->block_size(bottom)) {
89 // As in the case of contiguous space above, we'd like to
90 // just use the value returned by oop_iterate to increment the
91 // current pointer; unfortunately, that won't work in CMS because
92 // we'd need an interface change (it seems) to have the space
93 // "adjust the object size" (for instance pad it up to its
94 // block alignment or minimum block size restrictions. XXX
95 if (_sp->block_is_obj(bottom) &&
96 !_sp->obj_allocated_since_save_marks(oop(bottom))) {
97 oop(bottom)->oop_iterate(_cl, mr);
98 }
99 }
100 }
101
102 // We get called with "mr" representing the dirty region
103 // that we want to process. Because of imprecise marking,
104 // we may need to extend the incoming "mr" to the right,
105 // and scan more. However, because we may already have
106 // scanned some of that extended region, we may need to
107 // trim its right-end back some so we do not scan what
108 // we (or another worker thread) may already have scanned
109 // or planning to scan.
110 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
111
112 // Some collectors need to do special things whenever their dirty
113 // cards are processed. For instance, CMS must remember mutator updates
114 // (i.e. dirty cards) so as to re-scan mutated objects.
115 // Such work can be piggy-backed here on dirty card scanning, so as to make
116 // it slightly more efficient than doing a complete non-destructive pre-scan
117 // of the card table.
118 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
119 if (pCl != NULL) {
120 pCl->do_MemRegion(mr);
121 }
122
123 HeapWord* bottom = mr.start();
124 HeapWord* last = mr.last();
125 HeapWord* top = mr.end();
126 HeapWord* bottom_obj;
127 HeapWord* top_obj;
128
129 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
130 _precision == CardTableModRefBS::Precise,
131 "Only ones we deal with for now.");
132
133 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
134 _cl->idempotent() || _last_bottom == NULL ||
135 top <= _last_bottom,
136 "Not decreasing");
137 NOT_PRODUCT(_last_bottom = mr.start());
138
139 bottom_obj = _sp->block_start(bottom);
140 top_obj = _sp->block_start(last);
141
142 assert(bottom_obj <= bottom, "just checking");
143 assert(top_obj <= top, "just checking");
144
145 // Given what we think is the top of the memory region and
146 // the start of the object at the top, get the actual
147 // value of the top.
148 top = get_actual_top(top, top_obj);
149
150 // If the previous call did some part of this region, don't redo.
151 if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
152 _min_done != NULL &&
153 _min_done < top) {
154 top = _min_done;
155 }
156
157 // Top may have been reset, and in fact may be below bottom,
158 // e.g. the dirty card region is entirely in a now free object
159 // -- something that could happen with a concurrent sweeper.
160 bottom = MIN2(bottom, top);
161 MemRegion extended_mr = MemRegion(bottom, top);
162 assert(bottom <= top &&
163 (_precision != CardTableModRefBS::ObjHeadPreciseArray ||
164 _min_done == NULL ||
165 top <= _min_done),
166 "overlap!");
167
168 // Walk the region if it is not empty; otherwise there is nothing to do.
169 if (!extended_mr.is_empty()) {
170 walk_mem_region(extended_mr, bottom_obj, top);
171 }
172
173 // An idempotent closure might be applied in any order, so we don't
174 // record a _min_done for it.
175 if (!_cl->idempotent()) {
176 _min_done = bottom;
177 } else {
178 assert(_min_done == _last_explicit_min_done,
179 "Don't update _min_done for idempotent cl");
180 }
181 }
182
183 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl,
184 CardTableModRefBS::PrecisionStyle precision,
185 HeapWord* boundary) {
186 return new DirtyCardToOopClosure(this, cl, precision, boundary);
187 }
188
189 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
190 HeapWord* top_obj) {
191 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
192 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
193 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
194 // An arrayOop is starting on the dirty card - since we do exact
195 // store checks for objArrays we are done.
196 } else {
197 // Otherwise, it is possible that the object starting on the dirty
198 // card spans the entire card, and that the store happened on a
199 // later card. Figure out where the object ends.
200 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
201 "Block size and object size mismatch");
202 top = top_obj + oop(top_obj)->size();
203 }
204 }
205 } else {
206 top = (_sp->toContiguousSpace())->top();
207 }
208 return top;
209 }
210
211 void Filtering_DCTOC::walk_mem_region(MemRegion mr,
212 HeapWord* bottom,
213 HeapWord* top) {
214 // Note that this assumption won't hold if we have a concurrent
215 // collector in this space, which may have freed up objects after
216 // they were dirtied and before the stop-the-world GC that is
217 // examining cards here.
218 assert(bottom < top, "ought to be at least one obj on a dirty card.");
219
220 if (_boundary != NULL) {
221 // We have a boundary outside of which we don't want to look
222 // at objects, so create a filtering closure around the
223 // oop closure before walking the region.
224 FilteringClosure filter(_boundary, _cl);
225 walk_mem_region_with_cl(mr, bottom, top, &filter);
226 } else {
227 // No boundary, simply walk the heap with the oop closure.
228 walk_mem_region_with_cl(mr, bottom, top, _cl);
229 }
230
231 }
232
233 // We must replicate this so that the static type of "FilteringClosure"
234 // (see above) is apparent at the oop_iterate calls.
235 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
236 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
237 HeapWord* bottom, \
238 HeapWord* top, \
239 ClosureType* cl) { \
240 bottom += oop(bottom)->oop_iterate(cl, mr); \
241 if (bottom < top) { \
242 HeapWord* next_obj = bottom + oop(bottom)->size(); \
243 while (next_obj < top) { \
244 /* Bottom lies entirely below top, so we can call the */ \
245 /* non-memRegion version of oop_iterate below. */ \
246 oop(bottom)->oop_iterate(cl); \
247 bottom = next_obj; \
248 next_obj = bottom + oop(bottom)->size(); \
249 } \
250 /* Last object. */ \
251 oop(bottom)->oop_iterate(cl, mr); \
252 } \
253 }
254
255 // (There are only two of these, rather than N, because the split is due
256 // only to the introduction of the FilteringClosure, a local part of the
257 // impl of this abstraction.)
258 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
259 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
260
261 DirtyCardToOopClosure*
262 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl,
263 CardTableModRefBS::PrecisionStyle precision,
264 HeapWord* boundary) {
265 return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
266 }
267
268 void Space::initialize(MemRegion mr,
269 bool clear_space,
270 bool mangle_space) {
271 HeapWord* bottom = mr.start();
272 HeapWord* end = mr.end();
273 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
274 "invalid space boundaries");
275 set_bottom(bottom);
276 set_end(end);
277 if (clear_space) clear(mangle_space);
278 }
279
280 void Space::clear(bool mangle_space) {
281 if (ZapUnusedHeapArea && mangle_space) {
282 mangle_unused_area();
283 }
284 }
285
286 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
287 _concurrent_iteration_safe_limit(NULL) {
288 _mangler = new GenSpaceMangler(this);
289 }
290
291 ContiguousSpace::~ContiguousSpace() {
292 delete _mangler;
293 }
294
295 void ContiguousSpace::initialize(MemRegion mr,
296 bool clear_space,
297 bool mangle_space)
298 {
299 CompactibleSpace::initialize(mr, clear_space, mangle_space);
300 set_concurrent_iteration_safe_limit(top());
301 }
302
303 void ContiguousSpace::clear(bool mangle_space) {
304 set_top(bottom());
305 set_saved_mark();
306 CompactibleSpace::clear(mangle_space);
307 }
308
309 bool ContiguousSpace::is_free_block(const HeapWord* p) const {
310 return p >= _top;
311 }
312
313 void OffsetTableContigSpace::clear(bool mangle_space) {
314 ContiguousSpace::clear(mangle_space);
315 _offsets.initialize_threshold();
316 }
317
318 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
319 Space::set_bottom(new_bottom);
320 _offsets.set_bottom(new_bottom);
321 }
322
323 void OffsetTableContigSpace::set_end(HeapWord* new_end) {
324 // Space should not advertise an increase in size
325 // until after the underlying offset table has been enlarged.
326 _offsets.resize(pointer_delta(new_end, bottom()));
327 Space::set_end(new_end);
328 }
329
330 #ifndef PRODUCT
331
332 void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
333 mangler()->set_top_for_allocations(v);
334 }
335 void ContiguousSpace::set_top_for_allocations() {
336 mangler()->set_top_for_allocations(top());
337 }
338 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
339 mangler()->check_mangled_unused_area(limit);
340 }
341
342 void ContiguousSpace::check_mangled_unused_area_complete() {
343 mangler()->check_mangled_unused_area_complete();
344 }
345
346 // Mangled only the unused space that has not previously
347 // been mangled and that has not been allocated since being
348 // mangled.
349 void ContiguousSpace::mangle_unused_area() {
350 mangler()->mangle_unused_area();
351 }
352 void ContiguousSpace::mangle_unused_area_complete() {
353 mangler()->mangle_unused_area_complete();
354 }
355 #endif // NOT_PRODUCT
356
357 void CompactibleSpace::initialize(MemRegion mr,
358 bool clear_space,
359 bool mangle_space) {
360 Space::initialize(mr, clear_space, mangle_space);
361 set_compaction_top(bottom());
362 _next_compaction_space = NULL;
363 }
364
365 void CompactibleSpace::clear(bool mangle_space) {
366 Space::clear(mangle_space);
367 _compaction_top = bottom();
368 }
369
370 HeapWord* CompactibleSpace::forward(oop q, size_t size,
371 CompactPoint* cp, HeapWord* compact_top) {
372 // q is alive
373 // First check if we should switch compaction space
374 assert(this == cp->space, "'this' should be current compaction space.");
375 size_t compaction_max_size = pointer_delta(end(), compact_top);
376 while (size > compaction_max_size) {
377 // switch to next compaction space
378 cp->space->set_compaction_top(compact_top);
379 cp->space = cp->space->next_compaction_space();
380 if (cp->space == NULL) {
381 cp->gen = GenCollectedHeap::heap()->young_gen();
382 assert(cp->gen != NULL, "compaction must succeed");
383 cp->space = cp->gen->first_compaction_space();
384 assert(cp->space != NULL, "generation must have a first compaction space");
385 }
386 compact_top = cp->space->bottom();
387 cp->space->set_compaction_top(compact_top);
388 cp->threshold = cp->space->initialize_threshold();
389 compaction_max_size = pointer_delta(cp->space->end(), compact_top);
390 }
391
392 // store the forwarding pointer into the mark word
393 if ((HeapWord*)q != compact_top) {
394 q->forward_to(oop(compact_top));
395 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
396 } else {
397 // if the object isn't moving we can just set the mark to the default
398 // mark and handle it specially later on.
399 q->init_mark();
400 assert(q->forwardee() == NULL, "should be forwarded to NULL");
401 }
402
403 compact_top += size;
404
405 // we need to update the offset table so that the beginnings of objects can be
406 // found during scavenge. Note that we are updating the offset table based on
407 // where the object will be once the compaction phase finishes.
408 if (compact_top > cp->threshold)
409 cp->threshold =
410 cp->space->cross_threshold(compact_top - size, compact_top);
411 return compact_top;
412 }
413
414
415 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
416 HeapWord* q, size_t deadlength) {
417 if (allowed_deadspace_words >= deadlength) {
418 allowed_deadspace_words -= deadlength;
419 CollectedHeap::fill_with_object(q, deadlength);
420 oop(q)->set_mark(oop(q)->mark()->set_marked());
421 assert((int) deadlength == oop(q)->size(), "bad filler object size");
422 // Recall that we required "q == compaction_top".
423 return true;
424 } else {
425 allowed_deadspace_words = 0;
426 return false;
427 }
428 }
429
430 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
431 scan_and_forward(this, cp);
432 }
433
434 void CompactibleSpace::adjust_pointers() {
435 // Check first is there is any work to do.
436 if (used() == 0) {
437 return; // Nothing to do.
438 }
439
440 scan_and_adjust_pointers(this);
441 }
442
443 void CompactibleSpace::compact() {
444 scan_and_compact(this);
445 }
446
447 void Space::print_short() const { print_short_on(tty); }
448
449 void Space::print_short_on(outputStream* st) const {
450 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
451 (int) ((double) used() * 100 / capacity()));
452 }
453
454 void Space::print() const { print_on(tty); }
455
456 void Space::print_on(outputStream* st) const {
457 print_short_on(st);
458 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
459 bottom(), end());
460 }
461
462 void ContiguousSpace::print_on(outputStream* st) const {
463 print_short_on(st);
464 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
465 bottom(), top(), end());
466 }
467
468 void OffsetTableContigSpace::print_on(outputStream* st) const {
469 print_short_on(st);
470 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
471 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
472 bottom(), top(), _offsets.threshold(), end());
473 }
474
475 void ContiguousSpace::verify() const {
476 HeapWord* p = bottom();
477 HeapWord* t = top();
478 HeapWord* prev_p = NULL;
479 while (p < t) {
480 oop(p)->verify();
481 prev_p = p;
482 p += oop(p)->size();
483 }
484 guarantee(p == top(), "end of last object must match end of space");
485 if (top() != end()) {
486 guarantee(top() == block_start_const(end()-1) &&
487 top() == block_start_const(top()),
488 "top should be start of unallocated block, if it exists");
489 }
490 }
491
492 void Space::oop_iterate(ExtendedOopClosure* blk) {
493 ObjectToOopClosure blk2(blk);
494 object_iterate(&blk2);
495 }
496
497 bool Space::obj_is_alive(const HeapWord* p) const {
498 assert (block_is_obj(p), "The address should point to an object");
499 return true;
500 }
501
502 #if INCLUDE_ALL_GCS
503 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
504 \
505 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
506 HeapWord* obj_addr = mr.start(); \
507 HeapWord* t = mr.end(); \
508 while (obj_addr < t) { \
509 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \
510 obj_addr += oop(obj_addr)->oop_iterate(blk); \
511 } \
512 }
513
514 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
515
516 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
517 #endif // INCLUDE_ALL_GCS
518
519 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
520 if (is_empty()) return;
521 HeapWord* obj_addr = bottom();
522 HeapWord* t = top();
523 // Could call objects iterate, but this is easier.
524 while (obj_addr < t) {
525 obj_addr += oop(obj_addr)->oop_iterate(blk);
526 }
527 }
528
529 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
530 if (is_empty()) return;
531 WaterMark bm = bottom_mark();
532 object_iterate_from(bm, blk);
533 }
534
535 // For a ContiguousSpace object_iterate() and safe_object_iterate()
536 // are the same.
537 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
538 object_iterate(blk);
539 }
540
541 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
542 assert(mark.space() == this, "Mark does not match space");
543 HeapWord* p = mark.point();
544 while (p < top()) {
545 blk->do_object(oop(p));
546 p += oop(p)->size();
547 }
548 }
549
550 HeapWord*
551 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
552 HeapWord * limit = concurrent_iteration_safe_limit();
553 assert(limit <= top(), "sanity check");
554 for (HeapWord* p = bottom(); p < limit;) {
555 size_t size = blk->do_object_careful(oop(p));
556 if (size == 0) {
557 return p; // failed at p
558 } else {
559 p += size;
560 }
561 }
562 return NULL; // all done
563 }
564
565 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
566 \
567 void ContiguousSpace:: \
568 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
569 HeapWord* t; \
570 HeapWord* p = saved_mark_word(); \
571 assert(p != NULL, "expected saved mark"); \
572 \
573 const intx interval = PrefetchScanIntervalInBytes; \
574 do { \
575 t = top(); \
576 while (p < t) { \
577 Prefetch::write(p, interval); \
578 debug_only(HeapWord* prev = p); \
579 oop m = oop(p); \
580 p += m->oop_iterate(blk); \
581 } \
582 } while (t < top()); \
583 \
584 set_saved_mark_word(p); \
585 }
586
587 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
588
589 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
590
591 // Very general, slow implementation.
592 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
593 assert(MemRegion(bottom(), end()).contains(p),
594 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
595 p, bottom(), end()));
596 if (p >= top()) {
597 return top();
598 } else {
599 HeapWord* last = bottom();
600 HeapWord* cur = last;
601 while (cur <= p) {
602 last = cur;
603 cur += oop(cur)->size();
604 }
605 assert(oop(last)->is_oop(),
606 err_msg(PTR_FORMAT " should be an object start", last));
607 return last;
608 }
609 }
610
611 size_t ContiguousSpace::block_size(const HeapWord* p) const {
612 assert(MemRegion(bottom(), end()).contains(p),
613 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
614 p, bottom(), end()));
615 HeapWord* current_top = top();
616 assert(p <= current_top,
617 err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT,
618 p, current_top));
619 assert(p == current_top || oop(p)->is_oop(),
620 err_msg("p (" PTR_FORMAT ") is not a block start - "
621 "current_top: " PTR_FORMAT ", is_oop: %s",
622 p, current_top, BOOL_TO_STR(oop(p)->is_oop())));
623 if (p < current_top) {
624 return oop(p)->size();
625 } else {
626 assert(p == current_top, "just checking");
627 return pointer_delta(end(), (HeapWord*) p);
628 }
629 }
630
631 // This version requires locking.
632 inline HeapWord* ContiguousSpace::allocate_impl(size_t size) {
633 assert(Heap_lock->owned_by_self() ||
634 (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()),
635 "not locked");
636 HeapWord* obj = top();
637 if (pointer_delta(end(), obj) >= size) {
638 HeapWord* new_top = obj + size;
639 set_top(new_top);
640 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
641 return obj;
642 } else {
643 return NULL;
644 }
645 }
646
647 // This version is lock-free.
648 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size) {
649 do {
650 HeapWord* obj = top();
651 if (pointer_delta(end(), obj) >= size) {
652 HeapWord* new_top = obj + size;
653 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
654 // result can be one of two:
655 // the old top value: the exchange succeeded
656 // otherwise: the new value of the top is returned.
657 if (result == obj) {
658 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
659 return obj;
660 }
661 } else {
662 return NULL;
663 }
664 } while (true);
665 }
666
667 HeapWord* ContiguousSpace::allocate_aligned(size_t size) {
668 assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked");
669 HeapWord* end_value = end();
670
671 HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes);
672 if (obj == NULL) {
673 return NULL;
674 }
675
676 if (pointer_delta(end_value, obj) >= size) {
677 HeapWord* new_top = obj + size;
678 set_top(new_top);
679 assert(is_ptr_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top),
680 "checking alignment");
681 return obj;
682 } else {
683 set_top(obj);
684 return NULL;
685 }
686 }
687
688 // Requires locking.
689 HeapWord* ContiguousSpace::allocate(size_t size) {
690 return allocate_impl(size);
691 }
692
693 // Lock-free.
694 HeapWord* ContiguousSpace::par_allocate(size_t size) {
695 return par_allocate_impl(size);
696 }
697
698 void ContiguousSpace::allocate_temporary_filler(int factor) {
699 // allocate temporary type array decreasing free size with factor 'factor'
700 assert(factor >= 0, "just checking");
701 size_t size = pointer_delta(end(), top());
702
703 // if space is full, return
704 if (size == 0) return;
705
706 if (factor > 0) {
707 size -= size/factor;
708 }
709 size = align_object_size(size);
710
711 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
712 if (size >= (size_t)align_object_size(array_header_size)) {
713 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
714 // allocate uninitialized int array
715 typeArrayOop t = (typeArrayOop) allocate(size);
716 assert(t != NULL, "allocation should succeed");
717 t->set_mark(markOopDesc::prototype());
718 t->set_klass(Universe::intArrayKlassObj());
719 t->set_length((int)length);
720 } else {
721 assert(size == CollectedHeap::min_fill_size(),
722 "size for smallest fake object doesn't match");
723 instanceOop obj = (instanceOop) allocate(size);
724 obj->set_mark(markOopDesc::prototype());
725 obj->set_klass_gap(0);
726 obj->set_klass(SystemDictionary::Object_klass());
727 }
728 }
729
730 HeapWord* OffsetTableContigSpace::initialize_threshold() {
731 return _offsets.initialize_threshold();
732 }
733
734 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
735 _offsets.alloc_block(start, end);
736 return _offsets.threshold();
737 }
738
739 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
740 MemRegion mr) :
741 _offsets(sharedOffsetArray, mr),
742 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
743 {
744 _offsets.set_contig_space(this);
745 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
746 }
747
748 #define OBJ_SAMPLE_INTERVAL 0
749 #define BLOCK_SAMPLE_INTERVAL 100
750
751 void OffsetTableContigSpace::verify() const {
752 HeapWord* p = bottom();
753 HeapWord* prev_p = NULL;
754 int objs = 0;
755 int blocks = 0;
756
757 if (VerifyObjectStartArray) {
758 _offsets.verify();
759 }
760
761 while (p < top()) {
762 size_t size = oop(p)->size();
763 // For a sampling of objects in the space, find it using the
764 // block offset table.
765 if (blocks == BLOCK_SAMPLE_INTERVAL) {
766 guarantee(p == block_start_const(p + (size/2)),
767 "check offset computation");
768 blocks = 0;
769 } else {
770 blocks++;
771 }
772
773 if (objs == OBJ_SAMPLE_INTERVAL) {
774 oop(p)->verify();
775 objs = 0;
776 } else {
777 objs++;
778 }
779 prev_p = p;
780 p += size;
781 }
782 guarantee(p == top(), "end of last object must match end of space");
783 }
784
785
786 size_t TenuredSpace::allowed_dead_ratio() const {
787 return MarkSweepDeadRatio;
788 }