1 /*
2 * Copyright (c) 1997, 2014, 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/markSweep.hpp"
30 #include "gc_implementation/shared/spaceDecorator.hpp"
31 #include "gc_interface/collectedHeap.inline.hpp"
32 #include "memory/blockOffsetTable.inline.hpp"
33 #include "memory/defNewGeneration.hpp"
34 #include "memory/genCollectedHeap.hpp"
35 #include "memory/space.hpp"
36 #include "memory/space.inline.hpp"
37 #include "memory/universe.inline.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "oops/oop.inline2.hpp"
40 #include "runtime/java.hpp"
41 #include "runtime/atomic.inline.hpp"
42 #include "runtime/prefetch.inline.hpp"
43 #include "runtime/orderAccess.inline.hpp"
44 #include "runtime/safepoint.hpp"
45 #include "utilities/copy.hpp"
46 #include "utilities/globalDefinitions.hpp"
47 #include "utilities/macros.hpp"
48
49 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
50
51 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
52 HeapWord* top_obj) {
53 if (top_obj != NULL) {
54 if (_sp->block_is_obj(top_obj)) {
55 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
56 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
57 // An arrayOop is starting on the dirty card - since we do exact
58 // store checks for objArrays we are done.
59 } else {
60 // Otherwise, it is possible that the object starting on the dirty
61 // card spans the entire card, and that the store happened on a
62 // later card. Figure out where the object ends.
63 // Use the block_size() method of the space over which
64 // the iteration is being done. That space (e.g. CMS) may have
65 // specific requirements on object sizes which will
66 // be reflected in the block_size() method.
67 top = top_obj + oop(top_obj)->size();
68 }
69 }
70 } else {
71 top = top_obj;
72 }
73 } else {
74 assert(top == _sp->end(), "only case where top_obj == NULL");
75 }
76 return top;
77 }
78
79 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
80 HeapWord* bottom,
81 HeapWord* top) {
82 // 1. Blocks may or may not be objects.
83 // 2. Even when a block_is_obj(), it may not entirely
84 // occupy the block if the block quantum is larger than
85 // the object size.
86 // We can and should try to optimize by calling the non-MemRegion
87 // version of oop_iterate() for all but the extremal objects
88 // (for which we need to call the MemRegion version of
89 // oop_iterate()) To be done post-beta XXX
90 for (; bottom < top; bottom += _sp->block_size(bottom)) {
91 // As in the case of contiguous space above, we'd like to
92 // just use the value returned by oop_iterate to increment the
93 // current pointer; unfortunately, that won't work in CMS because
94 // we'd need an interface change (it seems) to have the space
95 // "adjust the object size" (for instance pad it up to its
96 // block alignment or minimum block size restrictions. XXX
97 if (_sp->block_is_obj(bottom) &&
98 !_sp->obj_allocated_since_save_marks(oop(bottom))) {
99 oop(bottom)->oop_iterate(_cl, mr);
100 }
101 }
102 }
103
104 // We get called with "mr" representing the dirty region
105 // that we want to process. Because of imprecise marking,
106 // we may need to extend the incoming "mr" to the right,
107 // and scan more. However, because we may already have
108 // scanned some of that extended region, we may need to
109 // trim its right-end back some so we do not scan what
110 // we (or another worker thread) may already have scanned
111 // or planning to scan.
112 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
113
114 // Some collectors need to do special things whenever their dirty
115 // cards are processed. For instance, CMS must remember mutator updates
116 // (i.e. dirty cards) so as to re-scan mutated objects.
117 // Such work can be piggy-backed here on dirty card scanning, so as to make
118 // it slightly more efficient than doing a complete non-destructive pre-scan
119 // of the card table.
120 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
121 if (pCl != NULL) {
122 pCl->do_MemRegion(mr);
123 }
124
125 HeapWord* bottom = mr.start();
126 HeapWord* last = mr.last();
127 HeapWord* top = mr.end();
128 HeapWord* bottom_obj;
129 HeapWord* top_obj;
130
131 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
132 _precision == CardTableModRefBS::Precise,
133 "Only ones we deal with for now.");
134
135 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
136 _cl->idempotent() || _last_bottom == NULL ||
137 top <= _last_bottom,
138 "Not decreasing");
139 NOT_PRODUCT(_last_bottom = mr.start());
140
141 bottom_obj = _sp->block_start(bottom);
142 top_obj = _sp->block_start(last);
143
144 assert(bottom_obj <= bottom, "just checking");
145 assert(top_obj <= top, "just checking");
146
147 // Given what we think is the top of the memory region and
148 // the start of the object at the top, get the actual
149 // value of the top.
150 top = get_actual_top(top, top_obj);
151
152 // If the previous call did some part of this region, don't redo.
153 if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
154 _min_done != NULL &&
155 _min_done < top) {
156 top = _min_done;
157 }
158
159 // Top may have been reset, and in fact may be below bottom,
160 // e.g. the dirty card region is entirely in a now free object
161 // -- something that could happen with a concurrent sweeper.
162 bottom = MIN2(bottom, top);
163 MemRegion extended_mr = MemRegion(bottom, top);
164 assert(bottom <= top &&
165 (_precision != CardTableModRefBS::ObjHeadPreciseArray ||
166 _min_done == NULL ||
167 top <= _min_done),
168 "overlap!");
169
170 // Walk the region if it is not empty; otherwise there is nothing to do.
171 if (!extended_mr.is_empty()) {
172 walk_mem_region(extended_mr, bottom_obj, top);
173 }
174
175 // An idempotent closure might be applied in any order, so we don't
176 // record a _min_done for it.
177 if (!_cl->idempotent()) {
178 _min_done = bottom;
179 } else {
180 assert(_min_done == _last_explicit_min_done,
181 "Don't update _min_done for idempotent cl");
182 }
183 }
184
185 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl,
186 CardTableModRefBS::PrecisionStyle precision,
187 HeapWord* boundary) {
188 return new DirtyCardToOopClosure(this, cl, precision, boundary);
189 }
190
191 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
192 HeapWord* top_obj) {
193 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
194 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
195 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
196 // An arrayOop is starting on the dirty card - since we do exact
197 // store checks for objArrays we are done.
198 } else {
199 // Otherwise, it is possible that the object starting on the dirty
200 // card spans the entire card, and that the store happened on a
201 // later card. Figure out where the object ends.
202 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
203 "Block size and object size mismatch");
204 top = top_obj + oop(top_obj)->size();
205 }
206 }
207 } else {
208 top = (_sp->toContiguousSpace())->top();
209 }
210 return top;
211 }
212
213 void Filtering_DCTOC::walk_mem_region(MemRegion mr,
214 HeapWord* bottom,
215 HeapWord* top) {
216 // Note that this assumption won't hold if we have a concurrent
217 // collector in this space, which may have freed up objects after
218 // they were dirtied and before the stop-the-world GC that is
219 // examining cards here.
220 assert(bottom < top, "ought to be at least one obj on a dirty card.");
221
222 if (_boundary != NULL) {
223 // We have a boundary outside of which we don't want to look
224 // at objects, so create a filtering closure around the
225 // oop closure before walking the region.
226 FilteringClosure filter(_boundary, _cl);
227 walk_mem_region_with_cl(mr, bottom, top, &filter);
228 } else {
229 // No boundary, simply walk the heap with the oop closure.
230 walk_mem_region_with_cl(mr, bottom, top, _cl);
231 }
232
233 }
234
235 // We must replicate this so that the static type of "FilteringClosure"
236 // (see above) is apparent at the oop_iterate calls.
237 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
238 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
239 HeapWord* bottom, \
240 HeapWord* top, \
241 ClosureType* cl) { \
242 bottom += oop(bottom)->oop_iterate(cl, mr); \
243 if (bottom < top) { \
244 HeapWord* next_obj = bottom + oop(bottom)->size(); \
245 while (next_obj < top) { \
246 /* Bottom lies entirely below top, so we can call the */ \
247 /* non-memRegion version of oop_iterate below. */ \
248 oop(bottom)->oop_iterate(cl); \
249 bottom = next_obj; \
250 next_obj = bottom + oop(bottom)->size(); \
251 } \
252 /* Last object. */ \
253 oop(bottom)->oop_iterate(cl, mr); \
254 } \
255 }
256
257 // (There are only two of these, rather than N, because the split is due
258 // only to the introduction of the FilteringClosure, a local part of the
259 // impl of this abstraction.)
260 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
261 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
262
263 DirtyCardToOopClosure*
264 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl,
265 CardTableModRefBS::PrecisionStyle precision,
266 HeapWord* boundary) {
267 return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
268 }
269
270 void Space::initialize(MemRegion mr,
271 bool clear_space,
272 bool mangle_space) {
273 HeapWord* bottom = mr.start();
274 HeapWord* end = mr.end();
275 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
276 "invalid space boundaries");
277 set_bottom(bottom);
278 set_end(end);
279 if (clear_space) clear(mangle_space);
280 }
281
282 void Space::clear(bool mangle_space) {
283 if (ZapUnusedHeapArea && mangle_space) {
284 mangle_unused_area();
285 }
286 }
287
288 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
289 _concurrent_iteration_safe_limit(NULL) {
290 _mangler = new GenSpaceMangler(this);
291 }
292
293 ContiguousSpace::~ContiguousSpace() {
294 delete _mangler;
295 }
296
297 void ContiguousSpace::initialize(MemRegion mr,
298 bool clear_space,
299 bool mangle_space)
300 {
301 CompactibleSpace::initialize(mr, clear_space, mangle_space);
302 set_concurrent_iteration_safe_limit(top());
303 }
304
305 void ContiguousSpace::clear(bool mangle_space) {
306 set_top(bottom());
307 set_saved_mark();
308 CompactibleSpace::clear(mangle_space);
309 }
310
311 bool ContiguousSpace::is_free_block(const HeapWord* p) const {
312 return p >= _top;
313 }
314
315 void OffsetTableContigSpace::clear(bool mangle_space) {
316 ContiguousSpace::clear(mangle_space);
317 _offsets.initialize_threshold();
318 }
319
320 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
321 Space::set_bottom(new_bottom);
322 _offsets.set_bottom(new_bottom);
323 }
324
325 void OffsetTableContigSpace::set_end(HeapWord* new_end) {
326 // Space should not advertise an increase in size
327 // until after the underlying offset table has been enlarged.
328 _offsets.resize(pointer_delta(new_end, bottom()));
329 Space::set_end(new_end);
330 }
331
332 #ifndef PRODUCT
333
334 void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
335 mangler()->set_top_for_allocations(v);
336 }
337 void ContiguousSpace::set_top_for_allocations() {
338 mangler()->set_top_for_allocations(top());
339 }
340 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
341 mangler()->check_mangled_unused_area(limit);
342 }
343
344 void ContiguousSpace::check_mangled_unused_area_complete() {
345 mangler()->check_mangled_unused_area_complete();
346 }
347
348 // Mangled only the unused space that has not previously
349 // been mangled and that has not been allocated since being
350 // mangled.
351 void ContiguousSpace::mangle_unused_area() {
352 mangler()->mangle_unused_area();
353 }
354 void ContiguousSpace::mangle_unused_area_complete() {
355 mangler()->mangle_unused_area_complete();
356 }
357 void ContiguousSpace::mangle_region(MemRegion mr) {
358 // Although this method uses SpaceMangler::mangle_region() which
359 // is not specific to a space, the when the ContiguousSpace version
360 // is called, it is always with regard to a space and this
361 // bounds checking is appropriate.
362 MemRegion space_mr(bottom(), end());
363 assert(space_mr.contains(mr), "Mangling outside space");
364 SpaceMangler::mangle_region(mr);
365 }
366 #endif // NOT_PRODUCT
367
368 void CompactibleSpace::initialize(MemRegion mr,
369 bool clear_space,
370 bool mangle_space) {
371 Space::initialize(mr, clear_space, mangle_space);
372 set_compaction_top(bottom());
373 _next_compaction_space = NULL;
374 }
375
376 void CompactibleSpace::clear(bool mangle_space) {
377 Space::clear(mangle_space);
378 _compaction_top = bottom();
379 }
380
381 HeapWord* CompactibleSpace::forward(oop q, size_t size,
382 CompactPoint* cp, HeapWord* compact_top) {
383 // q is alive
384 // First check if we should switch compaction space
385 assert(this == cp->space, "'this' should be current compaction space.");
386 size_t compaction_max_size = pointer_delta(end(), compact_top);
387 while (size > compaction_max_size) {
388 // switch to next compaction space
389 cp->space->set_compaction_top(compact_top);
390 cp->space = cp->space->next_compaction_space();
391 if (cp->space == NULL) {
392 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
393 assert(cp->gen != NULL, "compaction must succeed");
394 cp->space = cp->gen->first_compaction_space();
395 assert(cp->space != NULL, "generation must have a first compaction space");
396 }
397 compact_top = cp->space->bottom();
398 cp->space->set_compaction_top(compact_top);
399 cp->threshold = cp->space->initialize_threshold();
400 compaction_max_size = pointer_delta(cp->space->end(), compact_top);
401 }
402
403 // store the forwarding pointer into the mark word
404 if ((HeapWord*)q != compact_top) {
405 q->forward_to(oop(compact_top));
406 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
407 } else {
408 // if the object isn't moving we can just set the mark to the default
409 // mark and handle it specially later on.
410 q->init_mark();
411 assert(q->forwardee() == NULL, "should be forwarded to NULL");
412 }
413
414 compact_top += size;
415
416 // we need to update the offset table so that the beginnings of objects can be
417 // found during scavenge. Note that we are updating the offset table based on
418 // where the object will be once the compaction phase finishes.
419 if (compact_top > cp->threshold)
420 cp->threshold =
421 cp->space->cross_threshold(compact_top - size, compact_top);
422 return compact_top;
423 }
424
425
426 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
427 HeapWord* q, size_t deadlength) {
428 if (allowed_deadspace_words >= deadlength) {
429 allowed_deadspace_words -= deadlength;
430 CollectedHeap::fill_with_object(q, deadlength);
431 oop(q)->set_mark(oop(q)->mark()->set_marked());
432 assert((int) deadlength == oop(q)->size(), "bad filler object size");
433 // Recall that we required "q == compaction_top".
434 return true;
435 } else {
436 allowed_deadspace_words = 0;
437 return false;
438 }
439 }
440
441 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
442 scan_and_forward(this, cp);
443 }
444
445 void Space::adjust_pointers() {
446 // adjust all the interior pointers to point at the new locations of objects
447 // Used by MarkSweep::mark_sweep_phase3()
448
449 // First check to see if there is any work to be done.
450 if (used() == 0) {
451 return; // Nothing to do.
452 }
453
454 // Otherwise...
455 HeapWord* q = bottom();
456 HeapWord* t = end();
457
458 debug_only(HeapWord* prev_q = NULL);
459 while (q < t) {
460 if (oop(q)->is_gc_marked()) {
461 // q is alive
462
463 // point all the oops to the new location
464 size_t size = oop(q)->adjust_pointers();
465
466 debug_only(prev_q = q);
467
468 q += size;
469 } else {
470 // q is not a live object. But we're not in a compactible space,
471 // So we don't have live ranges.
472 debug_only(prev_q = q);
473 q += block_size(q);
474 assert(q > prev_q, "we should be moving forward through memory");
475 }
476 }
477 assert(q == t, "just checking");
478 }
479
480 void CompactibleSpace::adjust_pointers() {
481 // Check first is there is any work to do.
482 if (used() == 0) {
483 return; // Nothing to do.
484 }
485
486 scan_and_adjust_pointers(this);
487 }
488
489 void CompactibleSpace::compact() {
490 scan_and_compact(this);
491 }
492
493 void Space::print_short() const { print_short_on(tty); }
494
495 void Space::print_short_on(outputStream* st) const {
496 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
497 (int) ((double) used() * 100 / capacity()));
498 }
499
500 void Space::print() const { print_on(tty); }
501
502 void Space::print_on(outputStream* st) const {
503 print_short_on(st);
504 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
505 bottom(), end());
506 }
507
508 void ContiguousSpace::print_on(outputStream* st) const {
509 print_short_on(st);
510 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
511 bottom(), top(), end());
512 }
513
514 void OffsetTableContigSpace::print_on(outputStream* st) const {
515 print_short_on(st);
516 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
517 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
518 bottom(), top(), _offsets.threshold(), end());
519 }
520
521 void ContiguousSpace::verify() const {
522 HeapWord* p = bottom();
523 HeapWord* t = top();
524 HeapWord* prev_p = NULL;
525 while (p < t) {
526 oop(p)->verify();
527 prev_p = p;
528 p += oop(p)->size();
529 }
530 guarantee(p == top(), "end of last object must match end of space");
531 if (top() != end()) {
532 guarantee(top() == block_start_const(end()-1) &&
533 top() == block_start_const(top()),
534 "top should be start of unallocated block, if it exists");
535 }
536 }
537
538 void Space::oop_iterate(ExtendedOopClosure* blk) {
539 ObjectToOopClosure blk2(blk);
540 object_iterate(&blk2);
541 }
542
543 bool Space::obj_is_alive(const HeapWord* p) const {
544 assert (block_is_obj(p), "The address should point to an object");
545 return true;
546 }
547
548 #if INCLUDE_ALL_GCS
549 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
550 \
551 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
552 HeapWord* obj_addr = mr.start(); \
553 HeapWord* t = mr.end(); \
554 while (obj_addr < t) { \
555 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \
556 obj_addr += oop(obj_addr)->oop_iterate(blk); \
557 } \
558 }
559
560 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
561
562 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
563 #endif // INCLUDE_ALL_GCS
564
565 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
566 if (is_empty()) return;
567 HeapWord* obj_addr = bottom();
568 HeapWord* t = top();
569 // Could call objects iterate, but this is easier.
570 while (obj_addr < t) {
571 obj_addr += oop(obj_addr)->oop_iterate(blk);
572 }
573 }
574
575 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
576 if (is_empty()) return;
577 WaterMark bm = bottom_mark();
578 object_iterate_from(bm, blk);
579 }
580
581 // For a ContiguousSpace object_iterate() and safe_object_iterate()
582 // are the same.
583 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
584 object_iterate(blk);
585 }
586
587 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
588 assert(mark.space() == this, "Mark does not match space");
589 HeapWord* p = mark.point();
590 while (p < top()) {
591 blk->do_object(oop(p));
592 p += oop(p)->size();
593 }
594 }
595
596 HeapWord*
597 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
598 HeapWord * limit = concurrent_iteration_safe_limit();
599 assert(limit <= top(), "sanity check");
600 for (HeapWord* p = bottom(); p < limit;) {
601 size_t size = blk->do_object_careful(oop(p));
602 if (size == 0) {
603 return p; // failed at p
604 } else {
605 p += size;
606 }
607 }
608 return NULL; // all done
609 }
610
611 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
612 \
613 void ContiguousSpace:: \
614 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
615 HeapWord* t; \
616 HeapWord* p = saved_mark_word(); \
617 assert(p != NULL, "expected saved mark"); \
618 \
619 const intx interval = PrefetchScanIntervalInBytes; \
620 do { \
621 t = top(); \
622 while (p < t) { \
623 Prefetch::write(p, interval); \
624 debug_only(HeapWord* prev = p); \
625 oop m = oop(p); \
626 p += m->oop_iterate(blk); \
627 } \
628 } while (t < top()); \
629 \
630 set_saved_mark_word(p); \
631 }
632
633 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
634
635 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
636
637 // Very general, slow implementation.
638 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
639 assert(MemRegion(bottom(), end()).contains(p),
640 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
641 p, bottom(), end()));
642 if (p >= top()) {
643 return top();
644 } else {
645 HeapWord* last = bottom();
646 HeapWord* cur = last;
647 while (cur <= p) {
648 last = cur;
649 cur += oop(cur)->size();
650 }
651 assert(oop(last)->is_oop(),
652 err_msg(PTR_FORMAT " should be an object start", last));
653 return last;
654 }
655 }
656
657 size_t ContiguousSpace::block_size(const HeapWord* p) const {
658 assert(MemRegion(bottom(), end()).contains(p),
659 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
660 p, bottom(), end()));
661 HeapWord* current_top = top();
662 assert(p <= current_top,
663 err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT,
664 p, current_top));
665 assert(p == current_top || oop(p)->is_oop(),
666 err_msg("p (" PTR_FORMAT ") is not a block start - "
667 "current_top: " PTR_FORMAT ", is_oop: %s",
668 p, current_top, BOOL_TO_STR(oop(p)->is_oop())));
669 if (p < current_top) {
670 return oop(p)->size();
671 } else {
672 assert(p == current_top, "just checking");
673 return pointer_delta(end(), (HeapWord*) p);
674 }
675 }
676
677 // This version requires locking.
678 inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
679 HeapWord* const end_value) {
680 assert(Heap_lock->owned_by_self() ||
681 (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()),
682 "not locked");
683 HeapWord* obj = top();
684 if (pointer_delta(end_value, obj) >= size) {
685 HeapWord* new_top = obj + size;
686 set_top(new_top);
687 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
688 return obj;
689 } else {
690 return NULL;
691 }
692 }
693
694 // This version is lock-free.
695 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
696 HeapWord* const end_value) {
697 do {
698 HeapWord* obj = top();
699 if (pointer_delta(end_value, obj) >= size) {
700 HeapWord* new_top = obj + size;
701 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
702 // result can be one of two:
703 // the old top value: the exchange succeeded
704 // otherwise: the new value of the top is returned.
705 if (result == obj) {
706 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
707 return obj;
708 }
709 } else {
710 return NULL;
711 }
712 } while (true);
713 }
714
715 HeapWord* ContiguousSpace::allocate_aligned(size_t size) {
716 assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked");
717 HeapWord* end_value = end();
718
719 HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes);
720 if (obj == NULL) {
721 return NULL;
722 }
723
724 if (pointer_delta(end_value, obj) >= size) {
725 HeapWord* new_top = obj + size;
726 set_top(new_top);
727 assert(is_ptr_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top),
728 "checking alignment");
729 return obj;
730 } else {
731 set_top(obj);
732 return NULL;
733 }
734 }
735
736 // Requires locking.
737 HeapWord* ContiguousSpace::allocate(size_t size) {
738 return allocate_impl(size, end());
739 }
740
741 // Lock-free.
742 HeapWord* ContiguousSpace::par_allocate(size_t size) {
743 return par_allocate_impl(size, end());
744 }
745
746 void ContiguousSpace::allocate_temporary_filler(int factor) {
747 // allocate temporary type array decreasing free size with factor 'factor'
748 assert(factor >= 0, "just checking");
749 size_t size = pointer_delta(end(), top());
750
751 // if space is full, return
752 if (size == 0) return;
753
754 if (factor > 0) {
755 size -= size/factor;
756 }
757 size = align_object_size(size);
758
759 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
760 if (size >= (size_t)align_object_size(array_header_size)) {
761 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
762 // allocate uninitialized int array
763 typeArrayOop t = (typeArrayOop) allocate(size);
764 assert(t != NULL, "allocation should succeed");
765 t->set_mark(markOopDesc::prototype());
766 t->set_klass(Universe::intArrayKlassObj());
767 t->set_length((int)length);
768 } else {
769 assert(size == CollectedHeap::min_fill_size(),
770 "size for smallest fake object doesn't match");
771 instanceOop obj = (instanceOop) allocate(size);
772 obj->set_mark(markOopDesc::prototype());
773 obj->set_klass_gap(0);
774 obj->set_klass(SystemDictionary::Object_klass());
775 }
776 }
777
778 void EdenSpace::clear(bool mangle_space) {
779 ContiguousSpace::clear(mangle_space);
780 set_soft_end(end());
781 }
782
783 // Requires locking.
784 HeapWord* EdenSpace::allocate(size_t size) {
785 return allocate_impl(size, soft_end());
786 }
787
788 // Lock-free.
789 HeapWord* EdenSpace::par_allocate(size_t size) {
790 return par_allocate_impl(size, soft_end());
791 }
792
793 HeapWord* ConcEdenSpace::par_allocate(size_t size)
794 {
795 do {
796 // The invariant is top() should be read before end() because
797 // top() can't be greater than end(), so if an update of _soft_end
798 // occurs between 'end_val = end();' and 'top_val = top();' top()
799 // also can grow up to the new end() and the condition
800 // 'top_val > end_val' is true. To ensure the loading order
801 // OrderAccess::loadload() is required after top() read.
802 HeapWord* obj = top();
803 OrderAccess::loadload();
804 if (pointer_delta(*soft_end_addr(), obj) >= size) {
805 HeapWord* new_top = obj + size;
806 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
807 // result can be one of two:
808 // the old top value: the exchange succeeded
809 // otherwise: the new value of the top is returned.
810 if (result == obj) {
811 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
812 return obj;
813 }
814 } else {
815 return NULL;
816 }
817 } while (true);
818 }
819
820
821 HeapWord* OffsetTableContigSpace::initialize_threshold() {
822 return _offsets.initialize_threshold();
823 }
824
825 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
826 _offsets.alloc_block(start, end);
827 return _offsets.threshold();
828 }
829
830 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
831 MemRegion mr) :
832 _offsets(sharedOffsetArray, mr),
833 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
834 {
835 _offsets.set_contig_space(this);
836 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
837 }
838
839 #define OBJ_SAMPLE_INTERVAL 0
840 #define BLOCK_SAMPLE_INTERVAL 100
841
842 void OffsetTableContigSpace::verify() const {
843 HeapWord* p = bottom();
844 HeapWord* prev_p = NULL;
845 int objs = 0;
846 int blocks = 0;
847
848 if (VerifyObjectStartArray) {
849 _offsets.verify();
850 }
851
852 while (p < top()) {
853 size_t size = oop(p)->size();
854 // For a sampling of objects in the space, find it using the
855 // block offset table.
856 if (blocks == BLOCK_SAMPLE_INTERVAL) {
857 guarantee(p == block_start_const(p + (size/2)),
858 "check offset computation");
859 blocks = 0;
860 } else {
861 blocks++;
862 }
863
864 if (objs == OBJ_SAMPLE_INTERVAL) {
865 oop(p)->verify();
866 objs = 0;
867 } else {
868 objs++;
869 }
870 prev_p = p;
871 p += size;
872 }
873 guarantee(p == top(), "end of last object must match end of space");
874 }
875
876
877 size_t TenuredSpace::allowed_dead_ratio() const {
878 return MarkSweepDeadRatio;
879 }