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 #include "utilities/macros.hpp"
44
45 void SpaceMemRegionOopsIterClosure::do_oop(oop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
46 void SpaceMemRegionOopsIterClosure::do_oop(narrowOop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
47
48 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
49 HeapWord* top_obj) {
50 if (top_obj != NULL) {
51 if (_sp->block_is_obj(top_obj)) {
52 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
53 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
54 // An arrayOop is starting on the dirty card - since we do exact
55 // store checks for objArrays we are done.
56 } else {
57 // Otherwise, it is possible that the object starting on the dirty
58 // card spans the entire card, and that the store happened on a
59 // later card. Figure out where the object ends.
60 // Use the block_size() method of the space over which
61 // the iteration is being done. That space (e.g. CMS) may have
62 // specific requirements on object sizes which will
63 // be reflected in the block_size() method.
64 top = top_obj + oop(top_obj)->size();
65 }
66 }
67 } else {
68 top = top_obj;
69 }
70 } else {
71 assert(top == _sp->end(), "only case where top_obj == NULL");
72 }
73 return top;
74 }
75
76 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
77 HeapWord* bottom,
78 HeapWord* top) {
79 // 1. Blocks may or may not be objects.
80 // 2. Even when a block_is_obj(), it may not entirely
81 // occupy the block if the block quantum is larger than
82 // the object size.
83 // We can and should try to optimize by calling the non-MemRegion
84 // version of oop_iterate() for all but the extremal objects
85 // (for which we need to call the MemRegion version of
86 // oop_iterate()) To be done post-beta XXX
87 for (; bottom < top; bottom += _sp->block_size(bottom)) {
88 // As in the case of contiguous space above, we'd like to
89 // just use the value returned by oop_iterate to increment the
90 // current pointer; unfortunately, that won't work in CMS because
91 // we'd need an interface change (it seems) to have the space
92 // "adjust the object size" (for instance pad it up to its
93 // block alignment or minimum block size restrictions. XXX
94 if (_sp->block_is_obj(bottom) &&
95 !_sp->obj_allocated_since_save_marks(oop(bottom))) {
96 oop(bottom)->oop_iterate(_cl, mr);
97 }
98 }
99 }
100
101 // We get called with "mr" representing the dirty region
102 // that we want to process. Because of imprecise marking,
103 // we may need to extend the incoming "mr" to the right,
104 // and scan more. However, because we may already have
105 // scanned some of that extended region, we may need to
106 // trim its right-end back some so we do not scan what
107 // we (or another worker thread) may already have scanned
108 // or planning to scan.
109 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
110
111 // Some collectors need to do special things whenever their dirty
112 // cards are processed. For instance, CMS must remember mutator updates
113 // (i.e. dirty cards) so as to re-scan mutated objects.
114 // Such work can be piggy-backed here on dirty card scanning, so as to make
115 // it slightly more efficient than doing a complete non-destructive pre-scan
116 // of the card table.
117 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
118 if (pCl != NULL) {
119 pCl->do_MemRegion(mr);
120 }
121
122 HeapWord* bottom = mr.start();
123 HeapWord* last = mr.last();
124 HeapWord* top = mr.end();
125 HeapWord* bottom_obj;
126 HeapWord* top_obj;
127
128 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
129 _precision == CardTableModRefBS::Precise,
130 "Only ones we deal with for now.");
131
132 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
133 _cl->idempotent() || _last_bottom == NULL ||
134 top <= _last_bottom,
135 "Not decreasing");
136 NOT_PRODUCT(_last_bottom = mr.start());
137
138 bottom_obj = _sp->block_start(bottom);
139 top_obj = _sp->block_start(last);
140
141 assert(bottom_obj <= bottom, "just checking");
142 assert(top_obj <= top, "just checking");
143
144 // Given what we think is the top of the memory region and
145 // the start of the object at the top, get the actual
146 // value of the top.
147 top = get_actual_top(top, top_obj);
148
149 // If the previous call did some part of this region, don't redo.
150 if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
151 _min_done != NULL &&
152 _min_done < top) {
153 top = _min_done;
154 }
155
156 // Top may have been reset, and in fact may be below bottom,
157 // e.g. the dirty card region is entirely in a now free object
158 // -- something that could happen with a concurrent sweeper.
159 bottom = MIN2(bottom, top);
160 MemRegion extended_mr = MemRegion(bottom, top);
161 assert(bottom <= top &&
162 (_precision != CardTableModRefBS::ObjHeadPreciseArray ||
163 _min_done == NULL ||
164 top <= _min_done),
165 "overlap!");
166
167 // Walk the region if it is not empty; otherwise there is nothing to do.
168 if (!extended_mr.is_empty()) {
169 walk_mem_region(extended_mr, bottom_obj, top);
170 }
171
172 // An idempotent closure might be applied in any order, so we don't
173 // record a _min_done for it.
174 if (!_cl->idempotent()) {
175 _min_done = bottom;
176 } else {
177 assert(_min_done == _last_explicit_min_done,
178 "Don't update _min_done for idempotent cl");
179 }
180 }
181
182 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl,
183 CardTableModRefBS::PrecisionStyle precision,
184 HeapWord* boundary) {
185 return new DirtyCardToOopClosure(this, cl, precision, boundary);
186 }
187
188 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
189 HeapWord* top_obj) {
190 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
191 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
192 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
193 // An arrayOop is starting on the dirty card - since we do exact
194 // store checks for objArrays we are done.
195 } else {
196 // Otherwise, it is possible that the object starting on the dirty
197 // card spans the entire card, and that the store happened on a
198 // later card. Figure out where the object ends.
199 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
200 "Block size and object size mismatch");
201 top = top_obj + oop(top_obj)->size();
202 }
203 }
204 } else {
205 top = (_sp->toContiguousSpace())->top();
206 }
207 return top;
208 }
209
210 void Filtering_DCTOC::walk_mem_region(MemRegion mr,
211 HeapWord* bottom,
212 HeapWord* top) {
213 // Note that this assumption won't hold if we have a concurrent
214 // collector in this space, which may have freed up objects after
215 // they were dirtied and before the stop-the-world GC that is
216 // examining cards here.
217 assert(bottom < top, "ought to be at least one obj on a dirty card.");
218
219 if (_boundary != NULL) {
220 // We have a boundary outside of which we don't want to look
221 // at objects, so create a filtering closure around the
222 // oop closure before walking the region.
223 FilteringClosure filter(_boundary, _cl);
224 walk_mem_region_with_cl(mr, bottom, top, &filter);
225 } else {
226 // No boundary, simply walk the heap with the oop closure.
227 walk_mem_region_with_cl(mr, bottom, top, _cl);
228 }
229
230 }
231
232 // We must replicate this so that the static type of "FilteringClosure"
233 // (see above) is apparent at the oop_iterate calls.
234 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
235 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
236 HeapWord* bottom, \
237 HeapWord* top, \
238 ClosureType* cl) { \
239 bottom += oop(bottom)->oop_iterate(cl, mr); \
240 if (bottom < top) { \
241 HeapWord* next_obj = bottom + oop(bottom)->size(); \
242 while (next_obj < top) { \
243 /* Bottom lies entirely below top, so we can call the */ \
244 /* non-memRegion version of oop_iterate below. */ \
245 oop(bottom)->oop_iterate(cl); \
246 bottom = next_obj; \
247 next_obj = bottom + oop(bottom)->size(); \
248 } \
249 /* Last object. */ \
250 oop(bottom)->oop_iterate(cl, mr); \
251 } \
252 }
253
254 // (There are only two of these, rather than N, because the split is due
255 // only to the introduction of the FilteringClosure, a local part of the
256 // impl of this abstraction.)
257 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
258 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
259
260 DirtyCardToOopClosure*
261 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl,
262 CardTableModRefBS::PrecisionStyle precision,
263 HeapWord* boundary) {
264 return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
265 }
266
267 void Space::initialize(MemRegion mr,
268 bool clear_space,
269 bool mangle_space) {
270 HeapWord* bottom = mr.start();
271 HeapWord* end = mr.end();
272 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
273 "invalid space boundaries");
274 set_bottom(bottom);
275 set_end(end);
276 if (clear_space) clear(mangle_space);
277 }
278
279 void Space::clear(bool mangle_space) {
280 if (ZapUnusedHeapArea && mangle_space) {
281 mangle_unused_area();
282 }
283 }
284
285 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
286 _concurrent_iteration_safe_limit(NULL) {
287 _mangler = new GenSpaceMangler(this);
288 }
289
290 ContiguousSpace::~ContiguousSpace() {
291 delete _mangler;
292 }
293
294 void ContiguousSpace::initialize(MemRegion mr,
295 bool clear_space,
296 bool mangle_space)
297 {
298 CompactibleSpace::initialize(mr, clear_space, mangle_space);
299 set_concurrent_iteration_safe_limit(top());
300 }
301
302 void ContiguousSpace::clear(bool mangle_space) {
303 set_top(bottom());
304 set_saved_mark();
305 CompactibleSpace::clear(mangle_space);
306 }
307
308 bool ContiguousSpace::is_in(const void* p) const {
309 return _bottom <= p && p < _top;
310 }
311
312 bool ContiguousSpace::is_free_block(const HeapWord* p) const {
313 return p >= _top;
314 }
315
316 void OffsetTableContigSpace::clear(bool mangle_space) {
317 ContiguousSpace::clear(mangle_space);
318 _offsets.initialize_threshold();
319 }
320
321 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
322 Space::set_bottom(new_bottom);
323 _offsets.set_bottom(new_bottom);
324 }
325
326 void OffsetTableContigSpace::set_end(HeapWord* new_end) {
327 // Space should not advertise an increase in size
328 // until after the underlying offset table has been enlarged.
329 _offsets.resize(pointer_delta(new_end, bottom()));
330 Space::set_end(new_end);
331 }
332
333 #ifndef PRODUCT
334
335 void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
336 mangler()->set_top_for_allocations(v);
337 }
338 void ContiguousSpace::set_top_for_allocations() {
339 mangler()->set_top_for_allocations(top());
340 }
341 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
342 mangler()->check_mangled_unused_area(limit);
343 }
344
345 void ContiguousSpace::check_mangled_unused_area_complete() {
346 mangler()->check_mangled_unused_area_complete();
347 }
348
349 // Mangled only the unused space that has not previously
350 // been mangled and that has not been allocated since being
351 // mangled.
352 void ContiguousSpace::mangle_unused_area() {
353 mangler()->mangle_unused_area();
354 }
355 void ContiguousSpace::mangle_unused_area_complete() {
356 mangler()->mangle_unused_area_complete();
357 }
358 void ContiguousSpace::mangle_region(MemRegion mr) {
359 // Although this method uses SpaceMangler::mangle_region() which
360 // is not specific to a space, the when the ContiguousSpace version
361 // is called, it is always with regard to a space and this
362 // bounds checking is appropriate.
363 MemRegion space_mr(bottom(), end());
364 assert(space_mr.contains(mr), "Mangling outside space");
365 SpaceMangler::mangle_region(mr);
366 }
367 #endif // NOT_PRODUCT
368
369 void CompactibleSpace::initialize(MemRegion mr,
370 bool clear_space,
371 bool mangle_space) {
372 Space::initialize(mr, clear_space, mangle_space);
373 set_compaction_top(bottom());
374 _next_compaction_space = NULL;
375 }
376
377 void CompactibleSpace::clear(bool mangle_space) {
378 Space::clear(mangle_space);
379 _compaction_top = bottom();
380 }
381
382 HeapWord* CompactibleSpace::forward(oop q, size_t size,
383 CompactPoint* cp, HeapWord* compact_top) {
384 // q is alive
385 // First check if we should switch compaction space
386 assert(this == cp->space, "'this' should be current compaction space.");
387 size_t compaction_max_size = pointer_delta(end(), compact_top);
388 while (size > compaction_max_size) {
389 // switch to next compaction space
390 cp->space->set_compaction_top(compact_top);
391 cp->space = cp->space->next_compaction_space();
392 if (cp->space == NULL) {
393 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
394 assert(cp->gen != NULL, "compaction must succeed");
395 cp->space = cp->gen->first_compaction_space();
396 assert(cp->space != NULL, "generation must have a first compaction space");
397 }
398 compact_top = cp->space->bottom();
399 cp->space->set_compaction_top(compact_top);
400 cp->threshold = cp->space->initialize_threshold();
401 compaction_max_size = pointer_delta(cp->space->end(), compact_top);
402 }
403
404 // store the forwarding pointer into the mark word
405 if ((HeapWord*)q != compact_top) {
406 q->forward_to(oop(compact_top));
407 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
408 } else {
409 // if the object isn't moving we can just set the mark to the default
410 // mark and handle it specially later on.
411 q->init_mark();
412 assert(q->forwardee() == NULL, "should be forwarded to NULL");
413 }
414
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 // point all the oops to the new location
474 size_t size = oop(q)->adjust_pointers();
475
476 debug_only(prev_q = q);
477
478 q += size;
479 } else {
480 // q is not a live object. But we're not in a compactible space,
481 // So we don't have live ranges.
482 debug_only(prev_q = q);
483 q += block_size(q);
484 assert(q > prev_q, "we should be moving forward through memory");
485 }
486 }
487 assert(q == t, "just checking");
488 }
489
490 void CompactibleSpace::adjust_pointers() {
491 // Check first is there is any work to do.
492 if (used() == 0) {
493 return; // Nothing to do.
494 }
495
496 SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
497 }
498
499 void CompactibleSpace::compact() {
500 SCAN_AND_COMPACT(obj_size);
501 }
502
503 void Space::print_short() const { print_short_on(tty); }
504
505 void Space::print_short_on(outputStream* st) const {
506 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
507 (int) ((double) used() * 100 / capacity()));
508 }
509
510 void Space::print() const { print_on(tty); }
511
512 void Space::print_on(outputStream* st) const {
513 print_short_on(st);
514 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
515 bottom(), end());
516 }
517
518 void ContiguousSpace::print_on(outputStream* st) const {
519 print_short_on(st);
520 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
521 bottom(), top(), end());
522 }
523
524 void OffsetTableContigSpace::print_on(outputStream* st) const {
525 print_short_on(st);
526 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
527 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
528 bottom(), top(), _offsets.threshold(), end());
529 }
530
531 void ContiguousSpace::verify() const {
532 HeapWord* p = bottom();
533 HeapWord* t = top();
534 HeapWord* prev_p = NULL;
535 while (p < t) {
536 oop(p)->verify();
537 prev_p = p;
538 p += oop(p)->size();
539 }
540 guarantee(p == top(), "end of last object must match end of space");
541 if (top() != end()) {
542 guarantee(top() == block_start_const(end()-1) &&
543 top() == block_start_const(top()),
544 "top should be start of unallocated block, if it exists");
545 }
546 }
547
548 void Space::oop_iterate(ExtendedOopClosure* blk) {
549 ObjectToOopClosure blk2(blk);
550 object_iterate(&blk2);
551 }
552
553 HeapWord* Space::object_iterate_careful(ObjectClosureCareful* cl) {
554 guarantee(false, "NYI");
555 return bottom();
556 }
557
558 HeapWord* Space::object_iterate_careful_m(MemRegion mr,
559 ObjectClosureCareful* cl) {
560 guarantee(false, "NYI");
561 return bottom();
562 }
563
564
565 void Space::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
566 assert(!mr.is_empty(), "Should be non-empty");
567 // We use MemRegion(bottom(), end()) rather than used_region() below
568 // because the two are not necessarily equal for some kinds of
569 // spaces, in particular, certain kinds of free list spaces.
570 // We could use the more complicated but more precise:
571 // MemRegion(used_region().start(), round_to(used_region().end(), CardSize))
572 // but the slight imprecision seems acceptable in the assertion check.
573 assert(MemRegion(bottom(), end()).contains(mr),
574 "Should be within used space");
575 HeapWord* prev = cl->previous(); // max address from last time
576 if (prev >= mr.end()) { // nothing to do
577 return;
578 }
579 // This assert will not work when we go from cms space to perm
580 // space, and use same closure. Easy fix deferred for later. XXX YSR
581 // assert(prev == NULL || contains(prev), "Should be within space");
582
583 bool last_was_obj_array = false;
584 HeapWord *blk_start_addr, *region_start_addr;
585 if (prev > mr.start()) {
586 region_start_addr = prev;
587 blk_start_addr = prev;
588 // The previous invocation may have pushed "prev" beyond the
589 // last allocated block yet there may be still be blocks
590 // in this region due to a particular coalescing policy.
591 // Relax the assertion so that the case where the unallocated
592 // block is maintained and "prev" is beyond the unallocated
593 // block does not cause the assertion to fire.
594 assert((BlockOffsetArrayUseUnallocatedBlock &&
595 (!is_in(prev))) ||
596 (blk_start_addr == block_start(region_start_addr)), "invariant");
597 } else {
598 region_start_addr = mr.start();
599 blk_start_addr = block_start(region_start_addr);
600 }
601 HeapWord* region_end_addr = mr.end();
602 MemRegion derived_mr(region_start_addr, region_end_addr);
603 while (blk_start_addr < region_end_addr) {
604 const size_t size = block_size(blk_start_addr);
605 if (block_is_obj(blk_start_addr)) {
606 last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr);
607 } else {
608 last_was_obj_array = false;
609 }
610 blk_start_addr += size;
611 }
612 if (!last_was_obj_array) {
613 assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()),
614 "Should be within (closed) used space");
615 assert(blk_start_addr > prev, "Invariant");
616 cl->set_previous(blk_start_addr); // min address for next time
617 }
618 }
619
620 bool Space::obj_is_alive(const HeapWord* p) const {
621 assert (block_is_obj(p), "The address should point to an object");
622 return true;
623 }
624
625 void ContiguousSpace::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
626 assert(!mr.is_empty(), "Should be non-empty");
627 assert(used_region().contains(mr), "Should be within used space");
628 HeapWord* prev = cl->previous(); // max address from last time
629 if (prev >= mr.end()) { // nothing to do
630 return;
631 }
632 // See comment above (in more general method above) in case you
633 // happen to use this method.
634 assert(prev == NULL || is_in_reserved(prev), "Should be within space");
635
636 bool last_was_obj_array = false;
637 HeapWord *obj_start_addr, *region_start_addr;
638 if (prev > mr.start()) {
639 region_start_addr = prev;
640 obj_start_addr = prev;
641 assert(obj_start_addr == block_start(region_start_addr), "invariant");
642 } else {
643 region_start_addr = mr.start();
644 obj_start_addr = block_start(region_start_addr);
645 }
646 HeapWord* region_end_addr = mr.end();
647 MemRegion derived_mr(region_start_addr, region_end_addr);
648 while (obj_start_addr < region_end_addr) {
649 oop obj = oop(obj_start_addr);
650 const size_t size = obj->size();
651 last_was_obj_array = cl->do_object_bm(obj, derived_mr);
652 obj_start_addr += size;
653 }
654 if (!last_was_obj_array) {
655 assert((bottom() <= obj_start_addr) && (obj_start_addr <= end()),
656 "Should be within (closed) used space");
657 assert(obj_start_addr > prev, "Invariant");
658 cl->set_previous(obj_start_addr); // min address for next time
659 }
660 }
661
662 #if INCLUDE_ALL_GCS
663 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
664 \
665 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
666 HeapWord* obj_addr = mr.start(); \
667 HeapWord* t = mr.end(); \
668 while (obj_addr < t) { \
669 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \
670 obj_addr += oop(obj_addr)->oop_iterate(blk); \
671 } \
672 }
673
674 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
675
676 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
677 #endif // INCLUDE_ALL_GCS
678
679 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
680 if (is_empty()) return;
681 HeapWord* obj_addr = bottom();
682 HeapWord* t = top();
683 // Could call objects iterate, but this is easier.
684 while (obj_addr < t) {
685 obj_addr += oop(obj_addr)->oop_iterate(blk);
686 }
687 }
688
689 void ContiguousSpace::oop_iterate(MemRegion mr, ExtendedOopClosure* blk) {
690 if (is_empty()) {
691 return;
692 }
693 MemRegion cur = MemRegion(bottom(), top());
694 mr = mr.intersection(cur);
695 if (mr.is_empty()) {
696 return;
697 }
698 if (mr.equals(cur)) {
699 oop_iterate(blk);
700 return;
701 }
702 assert(mr.end() <= top(), "just took an intersection above");
703 HeapWord* obj_addr = block_start(mr.start());
704 HeapWord* t = mr.end();
705
706 // Handle first object specially.
707 oop obj = oop(obj_addr);
708 SpaceMemRegionOopsIterClosure smr_blk(blk, mr);
709 obj_addr += obj->oop_iterate(&smr_blk);
710 while (obj_addr < t) {
711 oop obj = oop(obj_addr);
712 assert(obj->is_oop(), "expected an oop");
713 obj_addr += obj->size();
714 // If "obj_addr" is not greater than top, then the
715 // entire object "obj" is within the region.
716 if (obj_addr <= t) {
717 obj->oop_iterate(blk);
718 } else {
719 // "obj" extends beyond end of region
720 obj->oop_iterate(&smr_blk);
721 break;
722 }
723 };
724 }
725
726 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
727 if (is_empty()) return;
728 WaterMark bm = bottom_mark();
729 object_iterate_from(bm, blk);
730 }
731
732 // For a ContiguousSpace object_iterate() and safe_object_iterate()
733 // are the same.
734 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
735 object_iterate(blk);
736 }
737
738 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
739 assert(mark.space() == this, "Mark does not match space");
740 HeapWord* p = mark.point();
741 while (p < top()) {
742 blk->do_object(oop(p));
743 p += oop(p)->size();
744 }
745 }
746
747 HeapWord*
748 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
749 HeapWord * limit = concurrent_iteration_safe_limit();
750 assert(limit <= top(), "sanity check");
751 for (HeapWord* p = bottom(); p < limit;) {
752 size_t size = blk->do_object_careful(oop(p));
753 if (size == 0) {
754 return p; // failed at p
755 } else {
756 p += size;
757 }
758 }
759 return NULL; // all done
760 }
761
762 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
763 \
764 void ContiguousSpace:: \
765 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
766 HeapWord* t; \
767 HeapWord* p = saved_mark_word(); \
768 assert(p != NULL, "expected saved mark"); \
769 \
770 const intx interval = PrefetchScanIntervalInBytes; \
771 do { \
772 t = top(); \
773 while (p < t) { \
774 Prefetch::write(p, interval); \
775 debug_only(HeapWord* prev = p); \
776 oop m = oop(p); \
777 p += m->oop_iterate(blk); \
778 } \
779 } while (t < top()); \
780 \
781 set_saved_mark_word(p); \
782 }
783
784 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
785
786 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
787
788 // Very general, slow implementation.
789 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
790 assert(MemRegion(bottom(), end()).contains(p),
791 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
792 p, bottom(), end()));
793 if (p >= top()) {
794 return top();
795 } else {
796 HeapWord* last = bottom();
797 HeapWord* cur = last;
798 while (cur <= p) {
799 last = cur;
800 cur += oop(cur)->size();
801 }
802 assert(oop(last)->is_oop(),
803 err_msg(PTR_FORMAT " should be an object start", last));
804 return last;
805 }
806 }
807
808 size_t ContiguousSpace::block_size(const HeapWord* p) const {
809 assert(MemRegion(bottom(), end()).contains(p),
810 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
811 p, bottom(), end()));
812 HeapWord* current_top = top();
813 assert(p <= current_top,
814 err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT,
815 p, current_top));
816 assert(p == current_top || oop(p)->is_oop(),
817 err_msg("p (" PTR_FORMAT ") is not a block start - "
818 "current_top: " PTR_FORMAT ", is_oop: %s",
819 p, current_top, BOOL_TO_STR(oop(p)->is_oop())));
820 if (p < current_top) {
821 return oop(p)->size();
822 } else {
823 assert(p == current_top, "just checking");
824 return pointer_delta(end(), (HeapWord*) p);
825 }
826 }
827
828 // This version requires locking.
829 inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
830 HeapWord* const end_value) {
831 // In G1 there are places where a GC worker can allocates into a
832 // region using this serial allocation code without being prone to a
833 // race with other GC workers (we ensure that no other GC worker can
834 // access the same region at the same time). So the assert below is
835 // too strong in the case of G1.
836 assert(Heap_lock->owned_by_self() ||
837 (SafepointSynchronize::is_at_safepoint() &&
838 (Thread::current()->is_VM_thread() || UseG1GC)),
839 "not locked");
840 HeapWord* obj = top();
841 if (pointer_delta(end_value, obj) >= size) {
842 HeapWord* new_top = obj + size;
843 set_top(new_top);
844 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
845 return obj;
846 } else {
847 return NULL;
848 }
849 }
850
851 // This version is lock-free.
852 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
853 HeapWord* const end_value) {
854 do {
855 HeapWord* obj = top();
856 if (pointer_delta(end_value, obj) >= size) {
857 HeapWord* new_top = obj + size;
858 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
859 // result can be one of two:
860 // the old top value: the exchange succeeded
861 // otherwise: the new value of the top is returned.
862 if (result == obj) {
863 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
864 return obj;
865 }
866 } else {
867 return NULL;
868 }
869 } while (true);
870 }
871
872 // Requires locking.
873 HeapWord* ContiguousSpace::allocate(size_t size) {
874 return allocate_impl(size, end());
875 }
876
877 // Lock-free.
878 HeapWord* ContiguousSpace::par_allocate(size_t size) {
879 return par_allocate_impl(size, end());
880 }
881
882 void ContiguousSpace::allocate_temporary_filler(int factor) {
883 // allocate temporary type array decreasing free size with factor 'factor'
884 assert(factor >= 0, "just checking");
885 size_t size = pointer_delta(end(), top());
886
887 // if space is full, return
888 if (size == 0) return;
889
890 if (factor > 0) {
891 size -= size/factor;
892 }
893 size = align_object_size(size);
894
895 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
896 if (size >= (size_t)align_object_size(array_header_size)) {
897 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
898 // allocate uninitialized int array
899 typeArrayOop t = (typeArrayOop) allocate(size);
900 assert(t != NULL, "allocation should succeed");
901 t->set_mark(markOopDesc::prototype());
902 t->set_klass(Universe::intArrayKlassObj());
903 t->set_length((int)length);
904 } else {
905 assert(size == CollectedHeap::min_fill_size(),
906 "size for smallest fake object doesn't match");
907 instanceOop obj = (instanceOop) allocate(size);
908 obj->set_mark(markOopDesc::prototype());
909 obj->set_klass_gap(0);
910 obj->set_klass(SystemDictionary::Object_klass());
911 }
912 }
913
914 void EdenSpace::clear(bool mangle_space) {
915 ContiguousSpace::clear(mangle_space);
916 set_soft_end(end());
917 }
918
919 // Requires locking.
920 HeapWord* EdenSpace::allocate(size_t size) {
921 return allocate_impl(size, soft_end());
922 }
923
924 // Lock-free.
925 HeapWord* EdenSpace::par_allocate(size_t size) {
926 return par_allocate_impl(size, soft_end());
927 }
928
929 HeapWord* ConcEdenSpace::par_allocate(size_t size)
930 {
931 do {
932 // The invariant is top() should be read before end() because
933 // top() can't be greater than end(), so if an update of _soft_end
934 // occurs between 'end_val = end();' and 'top_val = top();' top()
935 // also can grow up to the new end() and the condition
936 // 'top_val > end_val' is true. To ensure the loading order
937 // OrderAccess::loadload() is required after top() read.
938 HeapWord* obj = top();
939 OrderAccess::loadload();
940 if (pointer_delta(*soft_end_addr(), obj) >= size) {
941 HeapWord* new_top = obj + size;
942 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
943 // result can be one of two:
944 // the old top value: the exchange succeeded
945 // otherwise: the new value of the top is returned.
946 if (result == obj) {
947 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
948 return obj;
949 }
950 } else {
951 return NULL;
952 }
953 } while (true);
954 }
955
956
957 HeapWord* OffsetTableContigSpace::initialize_threshold() {
958 return _offsets.initialize_threshold();
959 }
960
961 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
962 _offsets.alloc_block(start, end);
963 return _offsets.threshold();
964 }
965
966 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
967 MemRegion mr) :
968 _offsets(sharedOffsetArray, mr),
969 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
970 {
971 _offsets.set_contig_space(this);
972 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
973 }
974
975 #define OBJ_SAMPLE_INTERVAL 0
976 #define BLOCK_SAMPLE_INTERVAL 100
977
978 void OffsetTableContigSpace::verify() const {
979 HeapWord* p = bottom();
980 HeapWord* prev_p = NULL;
981 int objs = 0;
982 int blocks = 0;
983
984 if (VerifyObjectStartArray) {
985 _offsets.verify();
986 }
987
988 while (p < top()) {
989 size_t size = oop(p)->size();
990 // For a sampling of objects in the space, find it using the
991 // block offset table.
992 if (blocks == BLOCK_SAMPLE_INTERVAL) {
993 guarantee(p == block_start_const(p + (size/2)),
994 "check offset computation");
995 blocks = 0;
996 } else {
997 blocks++;
998 }
999
1000 if (objs == OBJ_SAMPLE_INTERVAL) {
1001 oop(p)->verify();
1002 objs = 0;
1003 } else {
1004 objs++;
1005 }
1006 prev_p = p;
1007 p += size;
1008 }
1009 guarantee(p == top(), "end of last object must match end of space");
1010 }
1011
1012
1013 size_t TenuredSpace::allowed_dead_ratio() const {
1014 return MarkSweepDeadRatio;
1015 }