1 /*
2 * Copyright (c) 1997, 2012, 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/safepoint.hpp"
41 #include "utilities/copy.hpp"
42 #include "utilities/globalDefinitions.hpp"
43
44 void SpaceMemRegionOopsIterClosure::do_oop(oop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
45 void SpaceMemRegionOopsIterClosure::do_oop(narrowOop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
46
47 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
48 HeapWord* top_obj) {
49 if (top_obj != NULL) {
50 if (_sp->block_is_obj(top_obj)) {
51 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
52 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
53 // An arrayOop is starting on the dirty card - since we do exact
54 // store checks for objArrays we are done.
55 } else {
56 // Otherwise, it is possible that the object starting on the dirty
57 // card spans the entire card, and that the store happened on a
58 // later card. Figure out where the object ends.
59 // Use the block_size() method of the space over which
60 // the iteration is being done. That space (e.g. CMS) may have
61 // specific requirements on object sizes which will
62 // be reflected in the block_size() method.
63 top = top_obj + oop(top_obj)->size();
64 }
65 }
66 } else {
67 top = top_obj;
68 }
69 } else {
70 assert(top == _sp->end(), "only case where top_obj == NULL");
71 }
72 return top;
73 }
74
75 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
76 HeapWord* bottom,
77 HeapWord* top) {
78 // 1. Blocks may or may not be objects.
79 // 2. Even when a block_is_obj(), it may not entirely
80 // occupy the block if the block quantum is larger than
81 // the object size.
82 // We can and should try to optimize by calling the non-MemRegion
83 // version of oop_iterate() for all but the extremal objects
84 // (for which we need to call the MemRegion version of
85 // oop_iterate()) To be done post-beta XXX
86 for (; bottom < top; bottom += _sp->block_size(bottom)) {
87 // As in the case of contiguous space above, we'd like to
88 // just use the value returned by oop_iterate to increment the
89 // current pointer; unfortunately, that won't work in CMS because
90 // we'd need an interface change (it seems) to have the space
91 // "adjust the object size" (for instance pad it up to its
92 // block alignment or minimum block size restrictions. XXX
93 if (_sp->block_is_obj(bottom) &&
94 !_sp->obj_allocated_since_save_marks(oop(bottom))) {
95 oop(bottom)->oop_iterate(_cl, mr);
96 }
97 }
98 }
99
100 // We get called with "mr" representing the dirty region
101 // that we want to process. Because of imprecise marking,
102 // we may need to extend the incoming "mr" to the right,
103 // and scan more. However, because we may already have
104 // scanned some of that extended region, we may need to
105 // trim its right-end back some so we do not scan what
106 // we (or another worker thread) may already have scanned
107 // or planning to scan.
108 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
109
110 // Some collectors need to do special things whenever their dirty
111 // cards are processed. For instance, CMS must remember mutator updates
112 // (i.e. dirty cards) so as to re-scan mutated objects.
113 // Such work can be piggy-backed here on dirty card scanning, so as to make
114 // it slightly more efficient than doing a complete non-detructive pre-scan
115 // of the card table.
116 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
117 if (pCl != NULL) {
118 pCl->do_MemRegion(mr);
119 }
120
121 HeapWord* bottom = mr.start();
122 HeapWord* last = mr.last();
123 HeapWord* top = mr.end();
124 HeapWord* bottom_obj;
125 HeapWord* top_obj;
126
127 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
128 _precision == CardTableModRefBS::Precise,
129 "Only ones we deal with for now.");
130
131 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
132 _cl->idempotent() || _last_bottom == NULL ||
133 top <= _last_bottom,
134 "Not decreasing");
135 NOT_PRODUCT(_last_bottom = mr.start());
136
137 bottom_obj = _sp->block_start(bottom);
138 top_obj = _sp->block_start(last);
139
140 assert(bottom_obj <= bottom, "just checking");
141 assert(top_obj <= top, "just checking");
142
143 // Given what we think is the top of the memory region and
144 // the start of the object at the top, get the actual
145 // value of the top.
146 top = get_actual_top(top, top_obj);
147
148 // If the previous call did some part of this region, don't redo.
149 if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
150 _min_done != NULL &&
151 _min_done < top) {
152 top = _min_done;
153 }
154
155 // Top may have been reset, and in fact may be below bottom,
156 // e.g. the dirty card region is entirely in a now free object
157 // -- something that could happen with a concurrent sweeper.
158 bottom = MIN2(bottom, top);
159 MemRegion extended_mr = MemRegion(bottom, top);
160 assert(bottom <= top &&
161 (_precision != CardTableModRefBS::ObjHeadPreciseArray ||
162 _min_done == NULL ||
163 top <= _min_done),
164 "overlap!");
165
166 // Walk the region if it is not empty; otherwise there is nothing to do.
167 if (!extended_mr.is_empty()) {
168 walk_mem_region(extended_mr, bottom_obj, top);
169 }
170
171 // An idempotent closure might be applied in any order, so we don't
172 // record a _min_done for it.
173 if (!_cl->idempotent()) {
174 _min_done = bottom;
175 } else {
176 assert(_min_done == _last_explicit_min_done,
177 "Don't update _min_done for idempotent cl");
178 }
179 }
180
181 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl,
182 CardTableModRefBS::PrecisionStyle precision,
183 HeapWord* boundary) {
184 return new DirtyCardToOopClosure(this, cl, precision, boundary);
185 }
186
187 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
188 HeapWord* top_obj) {
189 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
190 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
191 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
192 // An arrayOop is starting on the dirty card - since we do exact
193 // store checks for objArrays we are done.
194 } else {
195 // Otherwise, it is possible that the object starting on the dirty
196 // card spans the entire card, and that the store happened on a
197 // later card. Figure out where the object ends.
198 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
199 "Block size and object size mismatch");
200 top = top_obj + oop(top_obj)->size();
201 }
202 }
203 } else {
204 top = (_sp->toContiguousSpace())->top();
205 }
206 return top;
207 }
208
209 void Filtering_DCTOC::walk_mem_region(MemRegion mr,
210 HeapWord* bottom,
211 HeapWord* top) {
212 // Note that this assumption won't hold if we have a concurrent
213 // collector in this space, which may have freed up objects after
214 // they were dirtied and before the stop-the-world GC that is
215 // examining cards here.
216 assert(bottom < top, "ought to be at least one obj on a dirty card.");
217
218 if (_boundary != NULL) {
219 // We have a boundary outside of which we don't want to look
220 // at objects, so create a filtering closure around the
221 // oop closure before walking the region.
222 FilteringClosure filter(_boundary, _cl);
223 walk_mem_region_with_cl(mr, bottom, top, &filter);
224 } else {
225 // No boundary, simply walk the heap with the oop closure.
226 walk_mem_region_with_cl(mr, bottom, top, _cl);
227 }
228
229 }
230
231 // We must replicate this so that the static type of "FilteringClosure"
232 // (see above) is apparent at the oop_iterate calls.
233 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
234 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
235 HeapWord* bottom, \
236 HeapWord* top, \
237 ClosureType* cl) { \
238 bottom += oop(bottom)->oop_iterate(cl, mr); \
239 if (bottom < top) { \
240 HeapWord* next_obj = bottom + oop(bottom)->size(); \
241 while (next_obj < top) { \
242 /* Bottom lies entirely below top, so we can call the */ \
243 /* non-memRegion version of oop_iterate below. */ \
244 oop(bottom)->oop_iterate(cl); \
245 bottom = next_obj; \
246 next_obj = bottom + oop(bottom)->size(); \
247 } \
248 /* Last object. */ \
249 oop(bottom)->oop_iterate(cl, mr); \
250 } \
251 }
252
253 // (There are only two of these, rather than N, because the split is due
254 // only to the introduction of the FilteringClosure, a local part of the
255 // impl of this abstraction.)
256 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
257 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
258
259 DirtyCardToOopClosure*
260 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl,
261 CardTableModRefBS::PrecisionStyle precision,
262 HeapWord* boundary) {
263 return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
264 }
265
266 void Space::initialize(MemRegion mr,
267 bool clear_space,
268 bool mangle_space) {
269 HeapWord* bottom = mr.start();
270 HeapWord* end = mr.end();
271 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
272 "invalid space boundaries");
273 set_bottom(bottom);
274 set_end(end);
275 if (clear_space) clear(mangle_space);
276 }
277
278 void Space::clear(bool mangle_space) {
279 if (ZapUnusedHeapArea && mangle_space) {
280 mangle_unused_area();
281 }
282 }
283
284 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
285 _concurrent_iteration_safe_limit(NULL) {
286 _mangler = new GenSpaceMangler(this);
287 }
288
289 ContiguousSpace::~ContiguousSpace() {
290 delete _mangler;
291 }
292
293 void ContiguousSpace::initialize(MemRegion mr,
294 bool clear_space,
295 bool mangle_space)
296 {
297 CompactibleSpace::initialize(mr, clear_space, mangle_space);
298 set_concurrent_iteration_safe_limit(top());
299 }
300
301 void ContiguousSpace::clear(bool mangle_space) {
302 set_top(bottom());
303 set_saved_mark();
304 CompactibleSpace::clear(mangle_space);
305 }
306
307 bool ContiguousSpace::is_in(const void* p) const {
308 return _bottom <= p && p < _top;
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 advertize an increase in size
327 // until after the underlying offest 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 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(q, size));
415 compact_top += size;
416
417 // we need to update the offset table so that the beginnings of objects can be
418 // found during scavenge. Note that we are updating the offset table based on
419 // where the object will be once the compaction phase finishes.
420 if (compact_top > cp->threshold)
421 cp->threshold =
422 cp->space->cross_threshold(compact_top - size, compact_top);
423 return compact_top;
424 }
425
426
427 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
428 HeapWord* q, size_t deadlength) {
429 if (allowed_deadspace_words >= deadlength) {
430 allowed_deadspace_words -= deadlength;
431 CollectedHeap::fill_with_object(q, deadlength);
432 oop(q)->set_mark(oop(q)->mark()->set_marked());
433 assert((int) deadlength == oop(q)->size(), "bad filler object size");
434 // Recall that we required "q == compaction_top".
435 return true;
436 } else {
437 allowed_deadspace_words = 0;
438 return false;
439 }
440 }
441
442 #define block_is_always_obj(q) true
443 #define obj_size(q) oop(q)->size()
444 #define adjust_obj_size(s) s
445
446 void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) {
447 SCAN_AND_FORWARD(cp, end, block_is_obj, block_size);
448 }
449
450 // Faster object search.
451 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
452 SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
453 }
454
455 void Space::adjust_pointers() {
456 // adjust all the interior pointers to point at the new locations of objects
457 // Used by MarkSweep::mark_sweep_phase3()
458
459 // First check to see if there is any work to be done.
460 if (used() == 0) {
461 return; // Nothing to do.
462 }
463
464 // Otherwise...
465 HeapWord* q = bottom();
466 HeapWord* t = end();
467
468 debug_only(HeapWord* prev_q = NULL);
469 while (q < t) {
470 if (oop(q)->is_gc_marked()) {
471 // q is alive
472
473 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q)));
474 // point all the oops to the new location
475 size_t size = oop(q)->adjust_pointers();
476 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers());
477
478 debug_only(prev_q = q);
479 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size));
480
481 q += size;
482 } else {
483 // q is not a live object. But we're not in a compactible space,
484 // So we don't have live ranges.
485 debug_only(prev_q = q);
486 q += block_size(q);
487 assert(q > prev_q, "we should be moving forward through memory");
488 }
489 }
490 assert(q == t, "just checking");
491 }
492
493 void CompactibleSpace::adjust_pointers() {
494 // Check first is there is any work to do.
495 if (used() == 0) {
496 return; // Nothing to do.
497 }
498
499 SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
500 }
501
502 void CompactibleSpace::compact() {
503 SCAN_AND_COMPACT(obj_size);
504 }
505
506 void Space::print_short() const { print_short_on(tty); }
507
508 void Space::print_short_on(outputStream* st) const {
509 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
510 (int) ((double) used() * 100 / capacity()));
511 }
512
513 void Space::print() const { print_on(tty); }
514
515 void Space::print_on(outputStream* st) const {
516 print_short_on(st);
517 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
518 bottom(), end());
519 }
520
521 void ContiguousSpace::print_on(outputStream* st) const {
522 print_short_on(st);
523 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
524 bottom(), top(), end());
525 }
526
527 void OffsetTableContigSpace::print_on(outputStream* st) const {
528 print_short_on(st);
529 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
530 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
531 bottom(), top(), _offsets.threshold(), end());
532 }
533
534 void ContiguousSpace::verify() const {
535 HeapWord* p = bottom();
536 HeapWord* t = top();
537 HeapWord* prev_p = NULL;
538 while (p < t) {
539 oop(p)->verify();
540 prev_p = p;
541 p += oop(p)->size();
542 }
543 guarantee(p == top(), "end of last object must match end of space");
544 if (top() != end()) {
545 guarantee(top() == block_start_const(end()-1) &&
546 top() == block_start_const(top()),
547 "top should be start of unallocated block, if it exists");
548 }
549 }
550
551 void Space::oop_iterate(ExtendedOopClosure* blk) {
552 ObjectToOopClosure blk2(blk);
553 object_iterate(&blk2);
554 }
555
556 HeapWord* Space::object_iterate_careful(ObjectClosureCareful* cl) {
557 guarantee(false, "NYI");
558 return bottom();
559 }
560
561 HeapWord* Space::object_iterate_careful_m(MemRegion mr,
562 ObjectClosureCareful* cl) {
563 guarantee(false, "NYI");
564 return bottom();
565 }
566
567
568 void Space::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
569 assert(!mr.is_empty(), "Should be non-empty");
570 // We use MemRegion(bottom(), end()) rather than used_region() below
571 // because the two are not necessarily equal for some kinds of
572 // spaces, in particular, certain kinds of free list spaces.
573 // We could use the more complicated but more precise:
574 // MemRegion(used_region().start(), round_to(used_region().end(), CardSize))
575 // but the slight imprecision seems acceptable in the assertion check.
576 assert(MemRegion(bottom(), end()).contains(mr),
577 "Should be within used space");
578 HeapWord* prev = cl->previous(); // max address from last time
579 if (prev >= mr.end()) { // nothing to do
580 return;
581 }
582 // This assert will not work when we go from cms space to perm
583 // space, and use same closure. Easy fix deferred for later. XXX YSR
584 // assert(prev == NULL || contains(prev), "Should be within space");
585
586 bool last_was_obj_array = false;
587 HeapWord *blk_start_addr, *region_start_addr;
588 if (prev > mr.start()) {
589 region_start_addr = prev;
590 blk_start_addr = prev;
591 // The previous invocation may have pushed "prev" beyond the
592 // last allocated block yet there may be still be blocks
593 // in this region due to a particular coalescing policy.
594 // Relax the assertion so that the case where the unallocated
595 // block is maintained and "prev" is beyond the unallocated
596 // block does not cause the assertion to fire.
597 assert((BlockOffsetArrayUseUnallocatedBlock &&
598 (!is_in(prev))) ||
599 (blk_start_addr == block_start(region_start_addr)), "invariant");
600 } else {
601 region_start_addr = mr.start();
602 blk_start_addr = block_start(region_start_addr);
603 }
604 HeapWord* region_end_addr = mr.end();
605 MemRegion derived_mr(region_start_addr, region_end_addr);
606 while (blk_start_addr < region_end_addr) {
607 const size_t size = block_size(blk_start_addr);
608 if (block_is_obj(blk_start_addr)) {
609 last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr);
610 } else {
611 last_was_obj_array = false;
612 }
613 blk_start_addr += size;
614 }
615 if (!last_was_obj_array) {
616 assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()),
617 "Should be within (closed) used space");
618 assert(blk_start_addr > prev, "Invariant");
619 cl->set_previous(blk_start_addr); // min address for next time
620 }
621 }
622
623 bool Space::obj_is_alive(const HeapWord* p) const {
624 assert (block_is_obj(p), "The address should point to an object");
625 return true;
626 }
627
628 void ContiguousSpace::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
629 assert(!mr.is_empty(), "Should be non-empty");
630 assert(used_region().contains(mr), "Should be within used space");
631 HeapWord* prev = cl->previous(); // max address from last time
632 if (prev >= mr.end()) { // nothing to do
633 return;
634 }
635 // See comment above (in more general method above) in case you
636 // happen to use this method.
637 assert(prev == NULL || is_in_reserved(prev), "Should be within space");
638
639 bool last_was_obj_array = false;
640 HeapWord *obj_start_addr, *region_start_addr;
641 if (prev > mr.start()) {
642 region_start_addr = prev;
643 obj_start_addr = prev;
644 assert(obj_start_addr == block_start(region_start_addr), "invariant");
645 } else {
646 region_start_addr = mr.start();
647 obj_start_addr = block_start(region_start_addr);
648 }
649 HeapWord* region_end_addr = mr.end();
650 MemRegion derived_mr(region_start_addr, region_end_addr);
651 while (obj_start_addr < region_end_addr) {
652 oop obj = oop(obj_start_addr);
653 const size_t size = obj->size();
654 last_was_obj_array = cl->do_object_bm(obj, derived_mr);
655 obj_start_addr += size;
656 }
657 if (!last_was_obj_array) {
658 assert((bottom() <= obj_start_addr) && (obj_start_addr <= end()),
659 "Should be within (closed) used space");
660 assert(obj_start_addr > prev, "Invariant");
661 cl->set_previous(obj_start_addr); // min address for next time
662 }
663 }
664
665 #ifndef SERIALGC
666 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
667 \
668 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
669 HeapWord* obj_addr = mr.start(); \
670 HeapWord* t = mr.end(); \
671 while (obj_addr < t) { \
672 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \
673 obj_addr += oop(obj_addr)->oop_iterate(blk); \
674 } \
675 }
676
677 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
678
679 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
680 #endif // SERIALGC
681
682 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
683 if (is_empty()) return;
684 HeapWord* obj_addr = bottom();
685 HeapWord* t = top();
686 // Could call objects iterate, but this is easier.
687 while (obj_addr < t) {
688 obj_addr += oop(obj_addr)->oop_iterate(blk);
689 }
690 }
691
692 void ContiguousSpace::oop_iterate(MemRegion mr, ExtendedOopClosure* blk) {
693 if (is_empty()) {
694 return;
695 }
696 MemRegion cur = MemRegion(bottom(), top());
697 mr = mr.intersection(cur);
698 if (mr.is_empty()) {
699 return;
700 }
701 if (mr.equals(cur)) {
702 oop_iterate(blk);
703 return;
704 }
705 assert(mr.end() <= top(), "just took an intersection above");
706 HeapWord* obj_addr = block_start(mr.start());
707 HeapWord* t = mr.end();
708
709 // Handle first object specially.
710 oop obj = oop(obj_addr);
711 SpaceMemRegionOopsIterClosure smr_blk(blk, mr);
712 obj_addr += obj->oop_iterate(&smr_blk);
713 while (obj_addr < t) {
714 oop obj = oop(obj_addr);
715 assert(obj->is_oop(), "expected an oop");
716 obj_addr += obj->size();
717 // If "obj_addr" is not greater than top, then the
718 // entire object "obj" is within the region.
719 if (obj_addr <= t) {
720 obj->oop_iterate(blk);
721 } else {
722 // "obj" extends beyond end of region
723 obj->oop_iterate(&smr_blk);
724 break;
725 }
726 };
727 }
728
729 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
730 if (is_empty()) return;
731 WaterMark bm = bottom_mark();
732 object_iterate_from(bm, blk);
733 }
734
735 // For a continguous space object_iterate() and safe_object_iterate()
736 // are the same.
737 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
738 object_iterate(blk);
739 }
740
741 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
742 assert(mark.space() == this, "Mark does not match space");
743 HeapWord* p = mark.point();
744 while (p < top()) {
745 blk->do_object(oop(p));
746 p += oop(p)->size();
747 }
748 }
749
750 HeapWord*
751 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
752 HeapWord * limit = concurrent_iteration_safe_limit();
753 assert(limit <= top(), "sanity check");
754 for (HeapWord* p = bottom(); p < limit;) {
755 size_t size = blk->do_object_careful(oop(p));
756 if (size == 0) {
757 return p; // failed at p
758 } else {
759 p += size;
760 }
761 }
762 return NULL; // all done
763 }
764
765 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
766 \
767 void ContiguousSpace:: \
768 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
769 HeapWord* t; \
770 HeapWord* p = saved_mark_word(); \
771 assert(p != NULL, "expected saved mark"); \
772 \
773 const intx interval = PrefetchScanIntervalInBytes; \
774 do { \
775 t = top(); \
776 while (p < t) { \
777 Prefetch::write(p, interval); \
778 debug_only(HeapWord* prev = p); \
779 oop m = oop(p); \
780 p += m->oop_iterate(blk); \
781 } \
782 } while (t < top()); \
783 \
784 set_saved_mark_word(p); \
785 }
786
787 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
788
789 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
790
791 // Very general, slow implementation.
792 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
793 assert(MemRegion(bottom(), end()).contains(p),
794 err_msg("p ("PTR_FORMAT") not in space ["PTR_FORMAT", "PTR_FORMAT")",
795 p, bottom(), end()));
796 if (p >= top()) {
797 return top();
798 } else {
799 HeapWord* last = bottom();
800 HeapWord* cur = last;
801 while (cur <= p) {
802 last = cur;
803 cur += oop(cur)->size();
804 }
805 assert(oop(last)->is_oop(),
806 err_msg(PTR_FORMAT" should be an object start", last));
807 return last;
808 }
809 }
810
811 size_t ContiguousSpace::block_size(const HeapWord* p) const {
812 assert(MemRegion(bottom(), end()).contains(p),
813 err_msg("p ("PTR_FORMAT") not in space ["PTR_FORMAT", "PTR_FORMAT")",
814 p, bottom(), end()));
815 HeapWord* current_top = top();
816 assert(p <= current_top,
817 err_msg("p > current top - p: "PTR_FORMAT", current top: "PTR_FORMAT,
818 p, current_top));
819 assert(p == current_top || oop(p)->is_oop(),
820 err_msg("p ("PTR_FORMAT") is not a block start - "
821 "current_top: "PTR_FORMAT", is_oop: %s",
822 p, current_top, BOOL_TO_STR(oop(p)->is_oop())));
823 if (p < current_top) {
824 return oop(p)->size();
825 } else {
826 assert(p == current_top, "just checking");
827 return pointer_delta(end(), (HeapWord*) p);
828 }
829 }
830
831 // This version requires locking.
832 inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
833 HeapWord* const end_value) {
834 // In G1 there are places where a GC worker can allocates into a
835 // region using this serial allocation code without being prone to a
836 // race with other GC workers (we ensure that no other GC worker can
837 // access the same region at the same time). So the assert below is
838 // too strong in the case of G1.
839 assert(Heap_lock->owned_by_self() ||
840 (SafepointSynchronize::is_at_safepoint() &&
841 (Thread::current()->is_VM_thread() || UseG1GC)),
842 "not locked");
843 HeapWord* obj = top();
844 if (pointer_delta(end_value, obj) >= size) {
845 HeapWord* new_top = obj + size;
846 set_top(new_top);
847 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
848 return obj;
849 } else {
850 return NULL;
851 }
852 }
853
854 // This version is lock-free.
855 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
856 HeapWord* const end_value) {
857 do {
858 HeapWord* obj = top();
859 if (pointer_delta(end_value, obj) >= size) {
860 HeapWord* new_top = obj + size;
861 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
862 // result can be one of two:
863 // the old top value: the exchange succeeded
864 // otherwise: the new value of the top is returned.
865 if (result == obj) {
866 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
867 return obj;
868 }
869 } else {
870 return NULL;
871 }
872 } while (true);
873 }
874
875 // Requires locking.
876 HeapWord* ContiguousSpace::allocate(size_t size) {
877 return allocate_impl(size, end());
878 }
879
880 // Lock-free.
881 HeapWord* ContiguousSpace::par_allocate(size_t size) {
882 return par_allocate_impl(size, end());
883 }
884
885 void ContiguousSpace::allocate_temporary_filler(int factor) {
886 // allocate temporary type array decreasing free size with factor 'factor'
887 assert(factor >= 0, "just checking");
888 size_t size = pointer_delta(end(), top());
889
890 // if space is full, return
891 if (size == 0) return;
892
893 if (factor > 0) {
894 size -= size/factor;
895 }
896 size = align_object_size(size);
897
898 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
899 if (size >= (size_t)align_object_size(array_header_size)) {
900 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
901 // allocate uninitialized int array
902 typeArrayOop t = (typeArrayOop) allocate(size);
903 assert(t != NULL, "allocation should succeed");
904 t->set_mark(markOopDesc::prototype());
905 t->set_klass(Universe::intArrayKlassObj());
906 t->set_length((int)length);
907 } else {
908 assert(size == CollectedHeap::min_fill_size(),
909 "size for smallest fake object doesn't match");
910 instanceOop obj = (instanceOop) allocate(size);
911 obj->set_mark(markOopDesc::prototype());
912 obj->set_klass_gap(0);
913 obj->set_klass(SystemDictionary::Object_klass());
914 }
915 }
916
917 void EdenSpace::clear(bool mangle_space) {
918 ContiguousSpace::clear(mangle_space);
919 set_soft_end(end());
920 }
921
922 // Requires locking.
923 HeapWord* EdenSpace::allocate(size_t size) {
924 return allocate_impl(size, soft_end());
925 }
926
927 // Lock-free.
928 HeapWord* EdenSpace::par_allocate(size_t size) {
929 return par_allocate_impl(size, soft_end());
930 }
931
932 HeapWord* ConcEdenSpace::par_allocate(size_t size)
933 {
934 do {
935 // The invariant is top() should be read before end() because
936 // top() can't be greater than end(), so if an update of _soft_end
937 // occurs between 'end_val = end();' and 'top_val = top();' top()
938 // also can grow up to the new end() and the condition
939 // 'top_val > end_val' is true. To ensure the loading order
940 // OrderAccess::loadload() is required after top() read.
941 HeapWord* obj = top();
942 OrderAccess::loadload();
943 if (pointer_delta(*soft_end_addr(), obj) >= size) {
944 HeapWord* new_top = obj + size;
945 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
946 // result can be one of two:
947 // the old top value: the exchange succeeded
948 // otherwise: the new value of the top is returned.
949 if (result == obj) {
950 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
951 return obj;
952 }
953 } else {
954 return NULL;
955 }
956 } while (true);
957 }
958
959
960 HeapWord* OffsetTableContigSpace::initialize_threshold() {
961 return _offsets.initialize_threshold();
962 }
963
964 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
965 _offsets.alloc_block(start, end);
966 return _offsets.threshold();
967 }
968
969 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
970 MemRegion mr) :
971 _offsets(sharedOffsetArray, mr),
972 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
973 {
974 _offsets.set_contig_space(this);
975 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
976 }
977
978 #define OBJ_SAMPLE_INTERVAL 0
979 #define BLOCK_SAMPLE_INTERVAL 100
980
981 void OffsetTableContigSpace::verify() const {
982 HeapWord* p = bottom();
983 HeapWord* prev_p = NULL;
984 int objs = 0;
985 int blocks = 0;
986
987 if (VerifyObjectStartArray) {
988 _offsets.verify();
989 }
990
991 while (p < top()) {
992 size_t size = oop(p)->size();
993 // For a sampling of objects in the space, find it using the
994 // block offset table.
995 if (blocks == BLOCK_SAMPLE_INTERVAL) {
996 guarantee(p == block_start_const(p + (size/2)),
997 "check offset computation");
998 blocks = 0;
999 } else {
1000 blocks++;
1001 }
1002
1003 if (objs == OBJ_SAMPLE_INTERVAL) {
1004 oop(p)->verify();
1005 objs = 0;
1006 } else {
1007 objs++;
1008 }
1009 prev_p = p;
1010 p += size;
1011 }
1012 guarantee(p == top(), "end of last object must match end of space");
1013 }
1014
1015
1016 size_t TenuredSpace::allowed_dead_ratio() const {
1017 return MarkSweepDeadRatio;
1018 }