Tue, 10 May 2011 00:33:21 -0700
6883834: ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests
Summary: Fixed process_chunk_boundaries(), used for parallel card scanning when using ParNew/CMS, so as to prevent double-scanning, or worse, non-scanning of imprecisely marked objects exceeding parallel chunk size. Made some sizing parameters for parallel card scanning diagnostic, disabled ParallelGCRetainPLAB, and elaborated and clarified some comments.
Reviewed-by: stefank, johnc
1 /*
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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"
44 void SpaceMemRegionOopsIterClosure::do_oop(oop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
45 void SpaceMemRegionOopsIterClosure::do_oop(narrowOop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
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 }
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 }
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) {
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 }
121 HeapWord* bottom = mr.start();
122 HeapWord* last = mr.last();
123 HeapWord* top = mr.end();
124 HeapWord* bottom_obj;
125 HeapWord* top_obj;
127 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
128 _precision == CardTableModRefBS::Precise,
129 "Only ones we deal with for now.");
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());
137 bottom_obj = _sp->block_start(bottom);
138 top_obj = _sp->block_start(last);
140 assert(bottom_obj <= bottom, "just checking");
141 assert(top_obj <= top, "just checking");
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);
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 }
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!");
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 }
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 }
181 DirtyCardToOopClosure* Space::new_dcto_cl(OopClosure* cl,
182 CardTableModRefBS::PrecisionStyle precision,
183 HeapWord* boundary) {
184 return new DirtyCardToOopClosure(this, cl, precision, boundary);
185 }
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 }
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.");
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 }
229 }
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 }
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(OopClosure)
257 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
259 DirtyCardToOopClosure*
260 ContiguousSpace::new_dcto_cl(OopClosure* cl,
261 CardTableModRefBS::PrecisionStyle precision,
262 HeapWord* boundary) {
263 return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
264 }
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 }
278 void Space::clear(bool mangle_space) {
279 if (ZapUnusedHeapArea && mangle_space) {
280 mangle_unused_area();
281 }
282 }
284 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
285 _concurrent_iteration_safe_limit(NULL) {
286 _mangler = new GenSpaceMangler(this);
287 }
289 ContiguousSpace::~ContiguousSpace() {
290 delete _mangler;
291 }
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 }
301 void ContiguousSpace::clear(bool mangle_space) {
302 set_top(bottom());
303 set_saved_mark();
304 CompactibleSpace::clear(mangle_space);
305 }
307 bool Space::is_in(const void* p) const {
308 HeapWord* b = block_start_const(p);
309 return b != NULL && block_is_obj(b);
310 }
312 bool ContiguousSpace::is_in(const void* p) const {
313 return _bottom <= p && p < _top;
314 }
316 bool ContiguousSpace::is_free_block(const HeapWord* p) const {
317 return p >= _top;
318 }
320 void OffsetTableContigSpace::clear(bool mangle_space) {
321 ContiguousSpace::clear(mangle_space);
322 _offsets.initialize_threshold();
323 }
325 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
326 Space::set_bottom(new_bottom);
327 _offsets.set_bottom(new_bottom);
328 }
330 void OffsetTableContigSpace::set_end(HeapWord* new_end) {
331 // Space should not advertize an increase in size
332 // until after the underlying offest table has been enlarged.
333 _offsets.resize(pointer_delta(new_end, bottom()));
334 Space::set_end(new_end);
335 }
337 #ifndef PRODUCT
339 void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
340 mangler()->set_top_for_allocations(v);
341 }
342 void ContiguousSpace::set_top_for_allocations() {
343 mangler()->set_top_for_allocations(top());
344 }
345 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
346 mangler()->check_mangled_unused_area(limit);
347 }
349 void ContiguousSpace::check_mangled_unused_area_complete() {
350 mangler()->check_mangled_unused_area_complete();
351 }
353 // Mangled only the unused space that has not previously
354 // been mangled and that has not been allocated since being
355 // mangled.
356 void ContiguousSpace::mangle_unused_area() {
357 mangler()->mangle_unused_area();
358 }
359 void ContiguousSpace::mangle_unused_area_complete() {
360 mangler()->mangle_unused_area_complete();
361 }
362 void ContiguousSpace::mangle_region(MemRegion mr) {
363 // Although this method uses SpaceMangler::mangle_region() which
364 // is not specific to a space, the when the ContiguousSpace version
365 // is called, it is always with regard to a space and this
366 // bounds checking is appropriate.
367 MemRegion space_mr(bottom(), end());
368 assert(space_mr.contains(mr), "Mangling outside space");
369 SpaceMangler::mangle_region(mr);
370 }
371 #endif // NOT_PRODUCT
373 void CompactibleSpace::initialize(MemRegion mr,
374 bool clear_space,
375 bool mangle_space) {
376 Space::initialize(mr, clear_space, mangle_space);
377 set_compaction_top(bottom());
378 _next_compaction_space = NULL;
379 }
381 void CompactibleSpace::clear(bool mangle_space) {
382 Space::clear(mangle_space);
383 _compaction_top = bottom();
384 }
386 HeapWord* CompactibleSpace::forward(oop q, size_t size,
387 CompactPoint* cp, HeapWord* compact_top) {
388 // q is alive
389 // First check if we should switch compaction space
390 assert(this == cp->space, "'this' should be current compaction space.");
391 size_t compaction_max_size = pointer_delta(end(), compact_top);
392 while (size > compaction_max_size) {
393 // switch to next compaction space
394 cp->space->set_compaction_top(compact_top);
395 cp->space = cp->space->next_compaction_space();
396 if (cp->space == NULL) {
397 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
398 assert(cp->gen != NULL, "compaction must succeed");
399 cp->space = cp->gen->first_compaction_space();
400 assert(cp->space != NULL, "generation must have a first compaction space");
401 }
402 compact_top = cp->space->bottom();
403 cp->space->set_compaction_top(compact_top);
404 cp->threshold = cp->space->initialize_threshold();
405 compaction_max_size = pointer_delta(cp->space->end(), compact_top);
406 }
408 // store the forwarding pointer into the mark word
409 if ((HeapWord*)q != compact_top) {
410 q->forward_to(oop(compact_top));
411 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
412 } else {
413 // if the object isn't moving we can just set the mark to the default
414 // mark and handle it specially later on.
415 q->init_mark();
416 assert(q->forwardee() == NULL, "should be forwarded to NULL");
417 }
419 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(q, size));
420 compact_top += size;
422 // we need to update the offset table so that the beginnings of objects can be
423 // found during scavenge. Note that we are updating the offset table based on
424 // where the object will be once the compaction phase finishes.
425 if (compact_top > cp->threshold)
426 cp->threshold =
427 cp->space->cross_threshold(compact_top - size, compact_top);
428 return compact_top;
429 }
432 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
433 HeapWord* q, size_t deadlength) {
434 if (allowed_deadspace_words >= deadlength) {
435 allowed_deadspace_words -= deadlength;
436 CollectedHeap::fill_with_object(q, deadlength);
437 oop(q)->set_mark(oop(q)->mark()->set_marked());
438 assert((int) deadlength == oop(q)->size(), "bad filler object size");
439 // Recall that we required "q == compaction_top".
440 return true;
441 } else {
442 allowed_deadspace_words = 0;
443 return false;
444 }
445 }
447 #define block_is_always_obj(q) true
448 #define obj_size(q) oop(q)->size()
449 #define adjust_obj_size(s) s
451 void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) {
452 SCAN_AND_FORWARD(cp, end, block_is_obj, block_size);
453 }
455 // Faster object search.
456 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
457 SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
458 }
460 void Space::adjust_pointers() {
461 // adjust all the interior pointers to point at the new locations of objects
462 // Used by MarkSweep::mark_sweep_phase3()
464 // First check to see if there is any work to be done.
465 if (used() == 0) {
466 return; // Nothing to do.
467 }
469 // Otherwise...
470 HeapWord* q = bottom();
471 HeapWord* t = end();
473 debug_only(HeapWord* prev_q = NULL);
474 while (q < t) {
475 if (oop(q)->is_gc_marked()) {
476 // q is alive
478 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q)));
479 // point all the oops to the new location
480 size_t size = oop(q)->adjust_pointers();
481 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers());
483 debug_only(prev_q = q);
484 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size));
486 q += size;
487 } else {
488 // q is not a live object. But we're not in a compactible space,
489 // So we don't have live ranges.
490 debug_only(prev_q = q);
491 q += block_size(q);
492 assert(q > prev_q, "we should be moving forward through memory");
493 }
494 }
495 assert(q == t, "just checking");
496 }
498 void CompactibleSpace::adjust_pointers() {
499 // Check first is there is any work to do.
500 if (used() == 0) {
501 return; // Nothing to do.
502 }
504 SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
505 }
507 void CompactibleSpace::compact() {
508 SCAN_AND_COMPACT(obj_size);
509 }
511 void Space::print_short() const { print_short_on(tty); }
513 void Space::print_short_on(outputStream* st) const {
514 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
515 (int) ((double) used() * 100 / capacity()));
516 }
518 void Space::print() const { print_on(tty); }
520 void Space::print_on(outputStream* st) const {
521 print_short_on(st);
522 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
523 bottom(), end());
524 }
526 void ContiguousSpace::print_on(outputStream* st) const {
527 print_short_on(st);
528 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
529 bottom(), top(), end());
530 }
532 void OffsetTableContigSpace::print_on(outputStream* st) const {
533 print_short_on(st);
534 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
535 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
536 bottom(), top(), _offsets.threshold(), end());
537 }
539 void ContiguousSpace::verify(bool allow_dirty) const {
540 HeapWord* p = bottom();
541 HeapWord* t = top();
542 HeapWord* prev_p = NULL;
543 while (p < t) {
544 oop(p)->verify();
545 prev_p = p;
546 p += oop(p)->size();
547 }
548 guarantee(p == top(), "end of last object must match end of space");
549 if (top() != end()) {
550 guarantee(top() == block_start_const(end()-1) &&
551 top() == block_start_const(top()),
552 "top should be start of unallocated block, if it exists");
553 }
554 }
556 void Space::oop_iterate(OopClosure* blk) {
557 ObjectToOopClosure blk2(blk);
558 object_iterate(&blk2);
559 }
561 HeapWord* Space::object_iterate_careful(ObjectClosureCareful* cl) {
562 guarantee(false, "NYI");
563 return bottom();
564 }
566 HeapWord* Space::object_iterate_careful_m(MemRegion mr,
567 ObjectClosureCareful* cl) {
568 guarantee(false, "NYI");
569 return bottom();
570 }
573 void Space::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
574 assert(!mr.is_empty(), "Should be non-empty");
575 // We use MemRegion(bottom(), end()) rather than used_region() below
576 // because the two are not necessarily equal for some kinds of
577 // spaces, in particular, certain kinds of free list spaces.
578 // We could use the more complicated but more precise:
579 // MemRegion(used_region().start(), round_to(used_region().end(), CardSize))
580 // but the slight imprecision seems acceptable in the assertion check.
581 assert(MemRegion(bottom(), end()).contains(mr),
582 "Should be within used space");
583 HeapWord* prev = cl->previous(); // max address from last time
584 if (prev >= mr.end()) { // nothing to do
585 return;
586 }
587 // This assert will not work when we go from cms space to perm
588 // space, and use same closure. Easy fix deferred for later. XXX YSR
589 // assert(prev == NULL || contains(prev), "Should be within space");
591 bool last_was_obj_array = false;
592 HeapWord *blk_start_addr, *region_start_addr;
593 if (prev > mr.start()) {
594 region_start_addr = prev;
595 blk_start_addr = prev;
596 // The previous invocation may have pushed "prev" beyond the
597 // last allocated block yet there may be still be blocks
598 // in this region due to a particular coalescing policy.
599 // Relax the assertion so that the case where the unallocated
600 // block is maintained and "prev" is beyond the unallocated
601 // block does not cause the assertion to fire.
602 assert((BlockOffsetArrayUseUnallocatedBlock &&
603 (!is_in(prev))) ||
604 (blk_start_addr == block_start(region_start_addr)), "invariant");
605 } else {
606 region_start_addr = mr.start();
607 blk_start_addr = block_start(region_start_addr);
608 }
609 HeapWord* region_end_addr = mr.end();
610 MemRegion derived_mr(region_start_addr, region_end_addr);
611 while (blk_start_addr < region_end_addr) {
612 const size_t size = block_size(blk_start_addr);
613 if (block_is_obj(blk_start_addr)) {
614 last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr);
615 } else {
616 last_was_obj_array = false;
617 }
618 blk_start_addr += size;
619 }
620 if (!last_was_obj_array) {
621 assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()),
622 "Should be within (closed) used space");
623 assert(blk_start_addr > prev, "Invariant");
624 cl->set_previous(blk_start_addr); // min address for next time
625 }
626 }
628 bool Space::obj_is_alive(const HeapWord* p) const {
629 assert (block_is_obj(p), "The address should point to an object");
630 return true;
631 }
633 void ContiguousSpace::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
634 assert(!mr.is_empty(), "Should be non-empty");
635 assert(used_region().contains(mr), "Should be within used space");
636 HeapWord* prev = cl->previous(); // max address from last time
637 if (prev >= mr.end()) { // nothing to do
638 return;
639 }
640 // See comment above (in more general method above) in case you
641 // happen to use this method.
642 assert(prev == NULL || is_in_reserved(prev), "Should be within space");
644 bool last_was_obj_array = false;
645 HeapWord *obj_start_addr, *region_start_addr;
646 if (prev > mr.start()) {
647 region_start_addr = prev;
648 obj_start_addr = prev;
649 assert(obj_start_addr == block_start(region_start_addr), "invariant");
650 } else {
651 region_start_addr = mr.start();
652 obj_start_addr = block_start(region_start_addr);
653 }
654 HeapWord* region_end_addr = mr.end();
655 MemRegion derived_mr(region_start_addr, region_end_addr);
656 while (obj_start_addr < region_end_addr) {
657 oop obj = oop(obj_start_addr);
658 const size_t size = obj->size();
659 last_was_obj_array = cl->do_object_bm(obj, derived_mr);
660 obj_start_addr += size;
661 }
662 if (!last_was_obj_array) {
663 assert((bottom() <= obj_start_addr) && (obj_start_addr <= end()),
664 "Should be within (closed) used space");
665 assert(obj_start_addr > prev, "Invariant");
666 cl->set_previous(obj_start_addr); // min address for next time
667 }
668 }
670 #ifndef SERIALGC
671 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
672 \
673 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
674 HeapWord* obj_addr = mr.start(); \
675 HeapWord* t = mr.end(); \
676 while (obj_addr < t) { \
677 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \
678 obj_addr += oop(obj_addr)->oop_iterate(blk); \
679 } \
680 }
682 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
684 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
685 #endif // SERIALGC
687 void ContiguousSpace::oop_iterate(OopClosure* blk) {
688 if (is_empty()) return;
689 HeapWord* obj_addr = bottom();
690 HeapWord* t = top();
691 // Could call objects iterate, but this is easier.
692 while (obj_addr < t) {
693 obj_addr += oop(obj_addr)->oop_iterate(blk);
694 }
695 }
697 void ContiguousSpace::oop_iterate(MemRegion mr, OopClosure* blk) {
698 if (is_empty()) {
699 return;
700 }
701 MemRegion cur = MemRegion(bottom(), top());
702 mr = mr.intersection(cur);
703 if (mr.is_empty()) {
704 return;
705 }
706 if (mr.equals(cur)) {
707 oop_iterate(blk);
708 return;
709 }
710 assert(mr.end() <= top(), "just took an intersection above");
711 HeapWord* obj_addr = block_start(mr.start());
712 HeapWord* t = mr.end();
714 // Handle first object specially.
715 oop obj = oop(obj_addr);
716 SpaceMemRegionOopsIterClosure smr_blk(blk, mr);
717 obj_addr += obj->oop_iterate(&smr_blk);
718 while (obj_addr < t) {
719 oop obj = oop(obj_addr);
720 assert(obj->is_oop(), "expected an oop");
721 obj_addr += obj->size();
722 // If "obj_addr" is not greater than top, then the
723 // entire object "obj" is within the region.
724 if (obj_addr <= t) {
725 obj->oop_iterate(blk);
726 } else {
727 // "obj" extends beyond end of region
728 obj->oop_iterate(&smr_blk);
729 break;
730 }
731 };
732 }
734 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
735 if (is_empty()) return;
736 WaterMark bm = bottom_mark();
737 object_iterate_from(bm, blk);
738 }
740 // For a continguous space object_iterate() and safe_object_iterate()
741 // are the same.
742 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
743 object_iterate(blk);
744 }
746 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
747 assert(mark.space() == this, "Mark does not match space");
748 HeapWord* p = mark.point();
749 while (p < top()) {
750 blk->do_object(oop(p));
751 p += oop(p)->size();
752 }
753 }
755 HeapWord*
756 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
757 HeapWord * limit = concurrent_iteration_safe_limit();
758 assert(limit <= top(), "sanity check");
759 for (HeapWord* p = bottom(); p < limit;) {
760 size_t size = blk->do_object_careful(oop(p));
761 if (size == 0) {
762 return p; // failed at p
763 } else {
764 p += size;
765 }
766 }
767 return NULL; // all done
768 }
770 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
771 \
772 void ContiguousSpace:: \
773 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
774 HeapWord* t; \
775 HeapWord* p = saved_mark_word(); \
776 assert(p != NULL, "expected saved mark"); \
777 \
778 const intx interval = PrefetchScanIntervalInBytes; \
779 do { \
780 t = top(); \
781 while (p < t) { \
782 Prefetch::write(p, interval); \
783 debug_only(HeapWord* prev = p); \
784 oop m = oop(p); \
785 p += m->oop_iterate(blk); \
786 } \
787 } while (t < top()); \
788 \
789 set_saved_mark_word(p); \
790 }
792 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
794 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
796 // Very general, slow implementation.
797 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
798 assert(MemRegion(bottom(), end()).contains(p), "p not in space");
799 if (p >= top()) {
800 return top();
801 } else {
802 HeapWord* last = bottom();
803 HeapWord* cur = last;
804 while (cur <= p) {
805 last = cur;
806 cur += oop(cur)->size();
807 }
808 assert(oop(last)->is_oop(), "Should be an object start");
809 return last;
810 }
811 }
813 size_t ContiguousSpace::block_size(const HeapWord* p) const {
814 assert(MemRegion(bottom(), end()).contains(p), "p not in space");
815 HeapWord* current_top = top();
816 assert(p <= current_top, "p is not a block start");
817 assert(p == current_top || oop(p)->is_oop(), "p is not a block start");
818 if (p < current_top)
819 return oop(p)->size();
820 else {
821 assert(p == current_top, "just checking");
822 return pointer_delta(end(), (HeapWord*) p);
823 }
824 }
826 // This version requires locking.
827 inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
828 HeapWord* const end_value) {
829 // In G1 there are places where a GC worker can allocates into a
830 // region using this serial allocation code without being prone to a
831 // race with other GC workers (we ensure that no other GC worker can
832 // access the same region at the same time). So the assert below is
833 // too strong in the case of G1.
834 assert(Heap_lock->owned_by_self() ||
835 (SafepointSynchronize::is_at_safepoint() &&
836 (Thread::current()->is_VM_thread() || UseG1GC)),
837 "not locked");
838 HeapWord* obj = top();
839 if (pointer_delta(end_value, obj) >= size) {
840 HeapWord* new_top = obj + size;
841 set_top(new_top);
842 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
843 return obj;
844 } else {
845 return NULL;
846 }
847 }
849 // This version is lock-free.
850 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
851 HeapWord* const end_value) {
852 do {
853 HeapWord* obj = top();
854 if (pointer_delta(end_value, obj) >= size) {
855 HeapWord* new_top = obj + size;
856 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
857 // result can be one of two:
858 // the old top value: the exchange succeeded
859 // otherwise: the new value of the top is returned.
860 if (result == obj) {
861 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
862 return obj;
863 }
864 } else {
865 return NULL;
866 }
867 } while (true);
868 }
870 // Requires locking.
871 HeapWord* ContiguousSpace::allocate(size_t size) {
872 return allocate_impl(size, end());
873 }
875 // Lock-free.
876 HeapWord* ContiguousSpace::par_allocate(size_t size) {
877 return par_allocate_impl(size, end());
878 }
880 void ContiguousSpace::allocate_temporary_filler(int factor) {
881 // allocate temporary type array decreasing free size with factor 'factor'
882 assert(factor >= 0, "just checking");
883 size_t size = pointer_delta(end(), top());
885 // if space is full, return
886 if (size == 0) return;
888 if (factor > 0) {
889 size -= size/factor;
890 }
891 size = align_object_size(size);
893 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
894 if (size >= (size_t)align_object_size(array_header_size)) {
895 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
896 // allocate uninitialized int array
897 typeArrayOop t = (typeArrayOop) allocate(size);
898 assert(t != NULL, "allocation should succeed");
899 t->set_mark(markOopDesc::prototype());
900 t->set_klass(Universe::intArrayKlassObj());
901 t->set_length((int)length);
902 } else {
903 assert(size == CollectedHeap::min_fill_size(),
904 "size for smallest fake object doesn't match");
905 instanceOop obj = (instanceOop) allocate(size);
906 obj->set_mark(markOopDesc::prototype());
907 obj->set_klass_gap(0);
908 obj->set_klass(SystemDictionary::Object_klass());
909 }
910 }
912 void EdenSpace::clear(bool mangle_space) {
913 ContiguousSpace::clear(mangle_space);
914 set_soft_end(end());
915 }
917 // Requires locking.
918 HeapWord* EdenSpace::allocate(size_t size) {
919 return allocate_impl(size, soft_end());
920 }
922 // Lock-free.
923 HeapWord* EdenSpace::par_allocate(size_t size) {
924 return par_allocate_impl(size, soft_end());
925 }
927 HeapWord* ConcEdenSpace::par_allocate(size_t size)
928 {
929 do {
930 // The invariant is top() should be read before end() because
931 // top() can't be greater than end(), so if an update of _soft_end
932 // occurs between 'end_val = end();' and 'top_val = top();' top()
933 // also can grow up to the new end() and the condition
934 // 'top_val > end_val' is true. To ensure the loading order
935 // OrderAccess::loadload() is required after top() read.
936 HeapWord* obj = top();
937 OrderAccess::loadload();
938 if (pointer_delta(*soft_end_addr(), obj) >= size) {
939 HeapWord* new_top = obj + size;
940 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
941 // result can be one of two:
942 // the old top value: the exchange succeeded
943 // otherwise: the new value of the top is returned.
944 if (result == obj) {
945 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
946 return obj;
947 }
948 } else {
949 return NULL;
950 }
951 } while (true);
952 }
955 HeapWord* OffsetTableContigSpace::initialize_threshold() {
956 return _offsets.initialize_threshold();
957 }
959 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
960 _offsets.alloc_block(start, end);
961 return _offsets.threshold();
962 }
964 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
965 MemRegion mr) :
966 _offsets(sharedOffsetArray, mr),
967 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
968 {
969 _offsets.set_contig_space(this);
970 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
971 }
974 class VerifyOldOopClosure : public OopClosure {
975 public:
976 oop _the_obj;
977 bool _allow_dirty;
978 void do_oop(oop* p) {
979 _the_obj->verify_old_oop(p, _allow_dirty);
980 }
981 void do_oop(narrowOop* p) {
982 _the_obj->verify_old_oop(p, _allow_dirty);
983 }
984 };
986 #define OBJ_SAMPLE_INTERVAL 0
987 #define BLOCK_SAMPLE_INTERVAL 100
989 void OffsetTableContigSpace::verify(bool allow_dirty) const {
990 HeapWord* p = bottom();
991 HeapWord* prev_p = NULL;
992 VerifyOldOopClosure blk; // Does this do anything?
993 blk._allow_dirty = allow_dirty;
994 int objs = 0;
995 int blocks = 0;
997 if (VerifyObjectStartArray) {
998 _offsets.verify();
999 }
1001 while (p < top()) {
1002 size_t size = oop(p)->size();
1003 // For a sampling of objects in the space, find it using the
1004 // block offset table.
1005 if (blocks == BLOCK_SAMPLE_INTERVAL) {
1006 guarantee(p == block_start_const(p + (size/2)),
1007 "check offset computation");
1008 blocks = 0;
1009 } else {
1010 blocks++;
1011 }
1013 if (objs == OBJ_SAMPLE_INTERVAL) {
1014 oop(p)->verify();
1015 blk._the_obj = oop(p);
1016 oop(p)->oop_iterate(&blk);
1017 objs = 0;
1018 } else {
1019 objs++;
1020 }
1021 prev_p = p;
1022 p += size;
1023 }
1024 guarantee(p == top(), "end of last object must match end of space");
1025 }
1027 void OffsetTableContigSpace::serialize_block_offset_array_offsets(
1028 SerializeOopClosure* soc) {
1029 _offsets.serialize(soc);
1030 }
1033 size_t TenuredSpace::allowed_dead_ratio() const {
1034 return MarkSweepDeadRatio;
1035 }
1038 size_t ContigPermSpace::allowed_dead_ratio() const {
1039 return PermMarkSweepDeadRatio;
1040 }