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 "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 "oops/oop.inline2.hpp"
39 #include "runtime/java.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 void ContiguousSpace::mangle_region(MemRegion mr) {
356 // Although this method uses SpaceMangler::mangle_region() which
357 // is not specific to a space, the when the ContiguousSpace version
358 // is called, it is always with regard to a space and this
359 // bounds checking is appropriate.
360 MemRegion space_mr(bottom(), end());
361 assert(space_mr.contains(mr), "Mangling outside space");
362 SpaceMangler::mangle_region(mr);
363 }
364 #endif // NOT_PRODUCT
365
366 void CompactibleSpace::initialize(MemRegion mr,
367 bool clear_space,
368 bool mangle_space) {
369 Space::initialize(mr, clear_space, mangle_space);
370 set_compaction_top(bottom());
371 _next_compaction_space = NULL;
372 }
373
374 void CompactibleSpace::clear(bool mangle_space) {
375 Space::clear(mangle_space);
376 _compaction_top = bottom();
377 }
378
379 HeapWord* CompactibleSpace::forward(oop q, size_t size,
380 CompactPoint* cp, HeapWord* compact_top) {
381 // q is alive
382 // First check if we should switch compaction space
383 assert(this == cp->space, "'this' should be current compaction space.");
384 size_t compaction_max_size = pointer_delta(end(), compact_top);
385 while (size > compaction_max_size) {
386 // switch to next compaction space
387 cp->space->set_compaction_top(compact_top);
388 cp->space = cp->space->next_compaction_space();
389 if (cp->space == NULL) {
390 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
391 assert(cp->gen != NULL, "compaction must succeed");
392 cp->space = cp->gen->first_compaction_space();
393 assert(cp->space != NULL, "generation must have a first compaction space");
394 }
395 compact_top = cp->space->bottom();
396 cp->space->set_compaction_top(compact_top);
397 cp->threshold = cp->space->initialize_threshold();
398 compaction_max_size = pointer_delta(cp->space->end(), compact_top);
399 }
400
401 // store the forwarding pointer into the mark word
402 if ((HeapWord*)q != compact_top) {
403 q->forward_to(oop(compact_top));
404 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
405 } else {
406 // if the object isn't moving we can just set the mark to the default
407 // mark and handle it specially later on.
408 q->init_mark();
409 assert(q->forwardee() == NULL, "should be forwarded to NULL");
410 }
411
412 compact_top += size;
413
414 // we need to update the offset table so that the beginnings of objects can be
415 // found during scavenge. Note that we are updating the offset table based on
416 // where the object will be once the compaction phase finishes.
417 if (compact_top > cp->threshold)
418 cp->threshold =
419 cp->space->cross_threshold(compact_top - size, compact_top);
420 return compact_top;
421 }
422
423
424 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
425 HeapWord* q, size_t deadlength) {
426 if (allowed_deadspace_words >= deadlength) {
427 allowed_deadspace_words -= deadlength;
428 CollectedHeap::fill_with_object(q, deadlength);
429 oop(q)->set_mark(oop(q)->mark()->set_marked());
430 assert((int) deadlength == oop(q)->size(), "bad filler object size");
431 // Recall that we required "q == compaction_top".
432 return true;
433 } else {
434 allowed_deadspace_words = 0;
435 return false;
436 }
437 }
438
439 #define block_is_always_obj(q) true
440 #define obj_size(q) oop(q)->size()
441 #define adjust_obj_size(s) s
442
443 void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) {
444 SCAN_AND_FORWARD(cp, end, block_is_obj, block_size);
445 }
446
447 // Faster object search.
448 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
449 SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
450 }
451
452 void Space::adjust_pointers() {
453 // adjust all the interior pointers to point at the new locations of objects
454 // Used by MarkSweep::mark_sweep_phase3()
455
456 // First check to see if there is any work to be done.
457 if (used() == 0) {
458 return; // Nothing to do.
459 }
460
461 // Otherwise...
462 HeapWord* q = bottom();
463 HeapWord* t = end();
464
465 debug_only(HeapWord* prev_q = NULL);
466 while (q < t) {
467 if (oop(q)->is_gc_marked()) {
468 // q is alive
469
470 // point all the oops to the new location
471 size_t size = oop(q)->adjust_pointers();
472
473 debug_only(prev_q = q);
474
475 q += size;
476 } else {
477 // q is not a live object. But we're not in a compactible space,
478 // So we don't have live ranges.
479 debug_only(prev_q = q);
480 q += block_size(q);
481 assert(q > prev_q, "we should be moving forward through memory");
482 }
483 }
484 assert(q == t, "just checking");
485 }
486
487 void CompactibleSpace::adjust_pointers() {
488 // Check first is there is any work to do.
489 if (used() == 0) {
490 return; // Nothing to do.
491 }
492
493 SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
494 }
495
496 void CompactibleSpace::compact() {
497 SCAN_AND_COMPACT(obj_size);
498 }
499
500 void Space::print_short() const { print_short_on(tty); }
501
502 void Space::print_short_on(outputStream* st) const {
503 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
504 (int) ((double) used() * 100 / capacity()));
505 }
506
507 void Space::print() const { print_on(tty); }
508
509 void Space::print_on(outputStream* st) const {
510 print_short_on(st);
511 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
512 bottom(), end());
513 }
514
515 void ContiguousSpace::print_on(outputStream* st) const {
516 print_short_on(st);
517 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
518 bottom(), top(), end());
519 }
520
521 void OffsetTableContigSpace::print_on(outputStream* st) const {
522 print_short_on(st);
523 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
524 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
525 bottom(), top(), _offsets.threshold(), end());
526 }
527
528 void ContiguousSpace::verify() const {
529 HeapWord* p = bottom();
530 HeapWord* t = top();
531 HeapWord* prev_p = NULL;
532 while (p < t) {
533 oop(p)->verify();
534 prev_p = p;
535 p += oop(p)->size();
536 }
537 guarantee(p == top(), "end of last object must match end of space");
538 if (top() != end()) {
539 guarantee(top() == block_start_const(end()-1) &&
540 top() == block_start_const(top()),
541 "top should be start of unallocated block, if it exists");
542 }
543 }
544
545 void Space::oop_iterate(ExtendedOopClosure* blk) {
546 ObjectToOopClosure blk2(blk);
547 object_iterate(&blk2);
548 }
549
550 bool Space::obj_is_alive(const HeapWord* p) const {
551 assert (block_is_obj(p), "The address should point to an object");
552 return true;
553 }
554
555 #if INCLUDE_ALL_GCS
556 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
557 \
558 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
559 HeapWord* obj_addr = mr.start(); \
560 HeapWord* t = mr.end(); \
561 while (obj_addr < t) { \
562 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \
563 obj_addr += oop(obj_addr)->oop_iterate(blk); \
564 } \
565 }
566
567 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
568
569 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
570 #endif // INCLUDE_ALL_GCS
571
572 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
573 if (is_empty()) return;
574 HeapWord* obj_addr = bottom();
575 HeapWord* t = top();
576 // Could call objects iterate, but this is easier.
577 while (obj_addr < t) {
578 obj_addr += oop(obj_addr)->oop_iterate(blk);
579 }
580 }
581
582 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
583 if (is_empty()) return;
584 WaterMark bm = bottom_mark();
585 object_iterate_from(bm, blk);
586 }
587
588 // For a ContiguousSpace object_iterate() and safe_object_iterate()
589 // are the same.
590 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
591 object_iterate(blk);
592 }
593
594 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
595 assert(mark.space() == this, "Mark does not match space");
596 HeapWord* p = mark.point();
597 while (p < top()) {
598 blk->do_object(oop(p));
599 p += oop(p)->size();
600 }
601 }
602
603 HeapWord*
604 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
605 HeapWord * limit = concurrent_iteration_safe_limit();
606 assert(limit <= top(), "sanity check");
607 for (HeapWord* p = bottom(); p < limit;) {
608 size_t size = blk->do_object_careful(oop(p));
609 if (size == 0) {
610 return p; // failed at p
611 } else {
612 p += size;
613 }
614 }
615 return NULL; // all done
616 }
617
618 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
619 \
620 void ContiguousSpace:: \
621 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
622 HeapWord* t; \
623 HeapWord* p = saved_mark_word(); \
624 assert(p != NULL, "expected saved mark"); \
625 \
626 const intx interval = PrefetchScanIntervalInBytes; \
627 do { \
628 t = top(); \
629 while (p < t) { \
630 Prefetch::write(p, interval); \
631 debug_only(HeapWord* prev = p); \
632 oop m = oop(p); \
633 p += m->oop_iterate(blk); \
634 } \
635 } while (t < top()); \
636 \
637 set_saved_mark_word(p); \
638 }
639
640 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
641
642 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
643
644 // Very general, slow implementation.
645 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
646 assert(MemRegion(bottom(), end()).contains(p),
647 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
648 p, bottom(), end()));
649 if (p >= top()) {
650 return top();
651 } else {
652 HeapWord* last = bottom();
653 HeapWord* cur = last;
654 while (cur <= p) {
655 last = cur;
656 cur += oop(cur)->size();
657 }
658 assert(oop(last)->is_oop(),
659 err_msg(PTR_FORMAT " should be an object start", last));
660 return last;
661 }
662 }
663
664 size_t ContiguousSpace::block_size(const HeapWord* p) const {
665 assert(MemRegion(bottom(), end()).contains(p),
666 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
667 p, bottom(), end()));
668 HeapWord* current_top = top();
669 assert(p <= current_top,
670 err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT,
671 p, current_top));
672 assert(p == current_top || oop(p)->is_oop(),
673 err_msg("p (" PTR_FORMAT ") is not a block start - "
674 "current_top: " PTR_FORMAT ", is_oop: %s",
675 p, current_top, BOOL_TO_STR(oop(p)->is_oop())));
676 if (p < current_top) {
677 return oop(p)->size();
678 } else {
679 assert(p == current_top, "just checking");
680 return pointer_delta(end(), (HeapWord*) p);
681 }
682 }
683
684 // This version requires locking.
685 inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
686 HeapWord* const end_value) {
687 // In G1 there are places where a GC worker can allocates into a
688 // region using this serial allocation code without being prone to a
689 // race with other GC workers (we ensure that no other GC worker can
690 // access the same region at the same time). So the assert below is
691 // too strong in the case of G1.
692 assert(Heap_lock->owned_by_self() ||
693 (SafepointSynchronize::is_at_safepoint() &&
694 (Thread::current()->is_VM_thread() || UseG1GC)),
695 "not locked");
696 HeapWord* obj = top();
697 if (pointer_delta(end_value, obj) >= size) {
698 HeapWord* new_top = obj + size;
699 set_top(new_top);
700 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
701 return obj;
702 } else {
703 return NULL;
704 }
705 }
706
707 // This version is lock-free.
708 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
709 HeapWord* const end_value) {
710 do {
711 HeapWord* obj = top();
712 if (pointer_delta(end_value, obj) >= size) {
713 HeapWord* new_top = obj + size;
714 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
715 // result can be one of two:
716 // the old top value: the exchange succeeded
717 // otherwise: the new value of the top is returned.
718 if (result == obj) {
719 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
720 return obj;
721 }
722 } else {
723 return NULL;
724 }
725 } while (true);
726 }
727
728 // Requires locking.
729 HeapWord* ContiguousSpace::allocate(size_t size) {
730 return allocate_impl(size, end());
731 }
732
733 // Lock-free.
734 HeapWord* ContiguousSpace::par_allocate(size_t size) {
735 return par_allocate_impl(size, end());
736 }
737
738 void ContiguousSpace::allocate_temporary_filler(int factor) {
739 // allocate temporary type array decreasing free size with factor 'factor'
740 assert(factor >= 0, "just checking");
741 size_t size = pointer_delta(end(), top());
742
743 // if space is full, return
744 if (size == 0) return;
745
746 if (factor > 0) {
747 size -= size/factor;
748 }
749 size = align_object_size(size);
750
751 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
752 if (size >= (size_t)align_object_size(array_header_size)) {
753 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
754 // allocate uninitialized int array
755 typeArrayOop t = (typeArrayOop) allocate(size);
756 assert(t != NULL, "allocation should succeed");
757 t->set_mark(markOopDesc::prototype());
758 t->set_klass(Universe::intArrayKlassObj());
759 t->set_length((int)length);
760 } else {
761 assert(size == CollectedHeap::min_fill_size(),
762 "size for smallest fake object doesn't match");
763 instanceOop obj = (instanceOop) allocate(size);
764 obj->set_mark(markOopDesc::prototype());
765 obj->set_klass_gap(0);
766 obj->set_klass(SystemDictionary::Object_klass());
767 }
768 }
769
770 void EdenSpace::clear(bool mangle_space) {
771 ContiguousSpace::clear(mangle_space);
772 set_soft_end(end());
773 }
774
775 // Requires locking.
776 HeapWord* EdenSpace::allocate(size_t size) {
777 return allocate_impl(size, soft_end());
778 }
779
780 // Lock-free.
781 HeapWord* EdenSpace::par_allocate(size_t size) {
782 return par_allocate_impl(size, soft_end());
783 }
784
785 HeapWord* ConcEdenSpace::par_allocate(size_t size)
786 {
787 do {
788 // The invariant is top() should be read before end() because
789 // top() can't be greater than end(), so if an update of _soft_end
790 // occurs between 'end_val = end();' and 'top_val = top();' top()
791 // also can grow up to the new end() and the condition
792 // 'top_val > end_val' is true. To ensure the loading order
793 // OrderAccess::loadload() is required after top() read.
794 HeapWord* obj = top();
795 OrderAccess::loadload();
796 if (pointer_delta(*soft_end_addr(), obj) >= size) {
797 HeapWord* new_top = obj + size;
798 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
799 // result can be one of two:
800 // the old top value: the exchange succeeded
801 // otherwise: the new value of the top is returned.
802 if (result == obj) {
803 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
804 return obj;
805 }
806 } else {
807 return NULL;
808 }
809 } while (true);
810 }
811
812
813 HeapWord* OffsetTableContigSpace::initialize_threshold() {
814 return _offsets.initialize_threshold();
815 }
816
817 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
818 _offsets.alloc_block(start, end);
819 return _offsets.threshold();
820 }
821
822 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
823 MemRegion mr) :
824 _offsets(sharedOffsetArray, mr),
825 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
826 {
827 _offsets.set_contig_space(this);
828 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
829 }
830
831 #define OBJ_SAMPLE_INTERVAL 0
832 #define BLOCK_SAMPLE_INTERVAL 100
833
834 void OffsetTableContigSpace::verify() const {
835 HeapWord* p = bottom();
836 HeapWord* prev_p = NULL;
837 int objs = 0;
838 int blocks = 0;
839
840 if (VerifyObjectStartArray) {
841 _offsets.verify();
842 }
843
844 while (p < top()) {
845 size_t size = oop(p)->size();
846 // For a sampling of objects in the space, find it using the
847 // block offset table.
848 if (blocks == BLOCK_SAMPLE_INTERVAL) {
849 guarantee(p == block_start_const(p + (size/2)),
850 "check offset computation");
851 blocks = 0;
852 } else {
853 blocks++;
854 }
855
856 if (objs == OBJ_SAMPLE_INTERVAL) {
857 oop(p)->verify();
858 objs = 0;
859 } else {
860 objs++;
861 }
862 prev_p = p;
863 p += size;
864 }
865 guarantee(p == top(), "end of last object must match end of space");
866 }
867
868
869 size_t TenuredSpace::allowed_dead_ratio() const {
870 return MarkSweepDeadRatio;
871 }