1 /*
2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "gc_implementation/shared/liveRange.hpp"
29 #include "gc_implementation/shared/markSweep.hpp"
30 #include "gc_implementation/shared/spaceDecorator.hpp"
31 #include "gc_interface/collectedHeap.inline.hpp"
32 #include "memory/blockOffsetTable.inline.hpp"
33 #include "memory/defNewGeneration.hpp"
34 #include "memory/genCollectedHeap.hpp"
35 #include "memory/space.hpp"
36 #include "memory/space.inline.hpp"
37 #include "memory/universe.inline.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "oops/oop.inline2.hpp"
40 #include "runtime/java.hpp"
41 #include "runtime/prefetch.inline.hpp"
42 #include "runtime/orderAccess.inline.hpp"
43 #include "runtime/safepoint.hpp"
44 #include "utilities/copy.hpp"
45 #include "utilities/globalDefinitions.hpp"
46 #include "utilities/macros.hpp"
47
48 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
49
get_actual_top(HeapWord * top,HeapWord * top_obj)50 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
51 HeapWord* top_obj) {
52 if (top_obj != NULL) {
53 if (_sp->block_is_obj(top_obj)) {
54 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
55 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
56 // An arrayOop is starting on the dirty card - since we do exact
57 // store checks for objArrays we are done.
58 } else {
59 // Otherwise, it is possible that the object starting on the dirty
60 // card spans the entire card, and that the store happened on a
61 // later card. Figure out where the object ends.
62 // Use the block_size() method of the space over which
63 // the iteration is being done. That space (e.g. CMS) may have
64 // specific requirements on object sizes which will
65 // be reflected in the block_size() method.
66 top = top_obj + oop(top_obj)->size();
67 }
68 }
69 } else {
70 top = top_obj;
71 }
72 } else {
73 assert(top == _sp->end(), "only case where top_obj == NULL");
74 }
75 return top;
76 }
77
walk_mem_region(MemRegion mr,HeapWord * bottom,HeapWord * top)78 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
79 HeapWord* bottom,
80 HeapWord* top) {
81 // 1. Blocks may or may not be objects.
82 // 2. Even when a block_is_obj(), it may not entirely
83 // occupy the block if the block quantum is larger than
84 // the object size.
85 // We can and should try to optimize by calling the non-MemRegion
86 // version of oop_iterate() for all but the extremal objects
87 // (for which we need to call the MemRegion version of
88 // oop_iterate()) To be done post-beta XXX
89 for (; bottom < top; bottom += _sp->block_size(bottom)) {
90 // As in the case of contiguous space above, we'd like to
91 // just use the value returned by oop_iterate to increment the
92 // current pointer; unfortunately, that won't work in CMS because
93 // we'd need an interface change (it seems) to have the space
94 // "adjust the object size" (for instance pad it up to its
95 // block alignment or minimum block size restrictions. XXX
96 if (_sp->block_is_obj(bottom) &&
97 !_sp->obj_allocated_since_save_marks(oop(bottom))) {
98 oop(bottom)->oop_iterate(_cl, mr);
99 }
100 }
101 }
102
103 // We get called with "mr" representing the dirty region
104 // that we want to process. Because of imprecise marking,
105 // we may need to extend the incoming "mr" to the right,
106 // and scan more. However, because we may already have
107 // scanned some of that extended region, we may need to
108 // trim its right-end back some so we do not scan what
109 // we (or another worker thread) may already have scanned
110 // or planning to scan.
do_MemRegion(MemRegion mr)111 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
112
113 // Some collectors need to do special things whenever their dirty
114 // cards are processed. For instance, CMS must remember mutator updates
115 // (i.e. dirty cards) so as to re-scan mutated objects.
116 // Such work can be piggy-backed here on dirty card scanning, so as to make
117 // it slightly more efficient than doing a complete non-detructive pre-scan
118 // of the card table.
119 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
120 if (pCl != NULL) {
121 pCl->do_MemRegion(mr);
122 }
123
124 HeapWord* bottom = mr.start();
125 HeapWord* last = mr.last();
126 HeapWord* top = mr.end();
127 HeapWord* bottom_obj;
128 HeapWord* top_obj;
129
130 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
131 _precision == CardTableModRefBS::Precise,
132 "Only ones we deal with for now.");
133
134 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
135 _cl->idempotent() || _last_bottom == NULL ||
136 top <= _last_bottom,
137 "Not decreasing");
138 NOT_PRODUCT(_last_bottom = mr.start());
139
140 bottom_obj = _sp->block_start(bottom);
141 top_obj = _sp->block_start(last);
142
143 assert(bottom_obj <= bottom, "just checking");
144 assert(top_obj <= top, "just checking");
145
146 // Given what we think is the top of the memory region and
147 // the start of the object at the top, get the actual
148 // value of the top.
149 top = get_actual_top(top, top_obj);
150
151 // If the previous call did some part of this region, don't redo.
152 if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
153 _min_done != NULL &&
154 _min_done < top) {
155 top = _min_done;
156 }
157
158 // Top may have been reset, and in fact may be below bottom,
159 // e.g. the dirty card region is entirely in a now free object
160 // -- something that could happen with a concurrent sweeper.
161 bottom = MIN2(bottom, top);
162 MemRegion extended_mr = MemRegion(bottom, top);
163 assert(bottom <= top &&
164 (_precision != CardTableModRefBS::ObjHeadPreciseArray ||
165 _min_done == NULL ||
166 top <= _min_done),
167 "overlap!");
168
169 // Walk the region if it is not empty; otherwise there is nothing to do.
170 if (!extended_mr.is_empty()) {
171 walk_mem_region(extended_mr, bottom_obj, top);
172 }
173
174 // An idempotent closure might be applied in any order, so we don't
175 // record a _min_done for it.
176 if (!_cl->idempotent()) {
177 _min_done = bottom;
178 } else {
179 assert(_min_done == _last_explicit_min_done,
180 "Don't update _min_done for idempotent cl");
181 }
182 }
183
new_dcto_cl(ExtendedOopClosure * cl,CardTableModRefBS::PrecisionStyle precision,HeapWord * boundary)184 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl,
185 CardTableModRefBS::PrecisionStyle precision,
186 HeapWord* boundary) {
187 return new DirtyCardToOopClosure(this, cl, precision, boundary);
188 }
189
get_actual_top(HeapWord * top,HeapWord * top_obj)190 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
191 HeapWord* top_obj) {
192 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
193 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
194 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
195 // An arrayOop is starting on the dirty card - since we do exact
196 // store checks for objArrays we are done.
197 } else {
198 // Otherwise, it is possible that the object starting on the dirty
199 // card spans the entire card, and that the store happened on a
200 // later card. Figure out where the object ends.
201 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
202 "Block size and object size mismatch");
203 top = top_obj + oop(top_obj)->size();
204 }
205 }
206 } else {
207 top = (_sp->toContiguousSpace())->top();
208 }
209 return top;
210 }
211
walk_mem_region(MemRegion mr,HeapWord * bottom,HeapWord * top)212 void Filtering_DCTOC::walk_mem_region(MemRegion mr,
213 HeapWord* bottom,
214 HeapWord* top) {
215 // Note that this assumption won't hold if we have a concurrent
216 // collector in this space, which may have freed up objects after
217 // they were dirtied and before the stop-the-world GC that is
218 // examining cards here.
219 assert(bottom < top, "ought to be at least one obj on a dirty card.");
220
221 if (_boundary != NULL) {
222 // We have a boundary outside of which we don't want to look
223 // at objects, so create a filtering closure around the
224 // oop closure before walking the region.
225 FilteringClosure filter(_boundary, _cl);
226 walk_mem_region_with_cl(mr, bottom, top, &filter);
227 } else {
228 // No boundary, simply walk the heap with the oop closure.
229 walk_mem_region_with_cl(mr, bottom, top, _cl);
230 }
231
232 }
233
234 // We must replicate this so that the static type of "FilteringClosure"
235 // (see above) is apparent at the oop_iterate calls.
236 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
237 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
238 HeapWord* bottom, \
239 HeapWord* top, \
240 ClosureType* cl) { \
241 bottom += oop(bottom)->oop_iterate(cl, mr); \
242 if (bottom < top) { \
243 HeapWord* next_obj = bottom + oop(bottom)->size(); \
244 while (next_obj < top) { \
245 /* Bottom lies entirely below top, so we can call the */ \
246 /* non-memRegion version of oop_iterate below. */ \
247 oop(bottom)->oop_iterate(cl); \
248 bottom = next_obj; \
249 next_obj = bottom + oop(bottom)->size(); \
250 } \
251 /* Last object. */ \
252 oop(bottom)->oop_iterate(cl, mr); \
253 } \
254 }
255
256 // (There are only two of these, rather than N, because the split is due
257 // only to the introduction of the FilteringClosure, a local part of the
258 // impl of this abstraction.)
259 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)260 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
261
262 DirtyCardToOopClosure*
263 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl,
264 CardTableModRefBS::PrecisionStyle precision,
265 HeapWord* boundary) {
266 return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
267 }
268
initialize(MemRegion mr,bool clear_space,bool mangle_space)269 void Space::initialize(MemRegion mr,
270 bool clear_space,
271 bool mangle_space) {
272 HeapWord* bottom = mr.start();
273 HeapWord* end = mr.end();
274 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
275 "invalid space boundaries");
276 set_bottom(bottom);
277 set_end(end);
278 if (clear_space) clear(mangle_space);
279 }
280
clear(bool mangle_space)281 void Space::clear(bool mangle_space) {
282 if (ZapUnusedHeapArea && mangle_space) {
283 mangle_unused_area();
284 }
285 }
286
ContiguousSpace()287 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
288 _concurrent_iteration_safe_limit(NULL) {
289 _mangler = new GenSpaceMangler(this);
290 }
291
~ContiguousSpace()292 ContiguousSpace::~ContiguousSpace() {
293 delete _mangler;
294 }
295
initialize(MemRegion mr,bool clear_space,bool mangle_space)296 void ContiguousSpace::initialize(MemRegion mr,
297 bool clear_space,
298 bool mangle_space)
299 {
300 CompactibleSpace::initialize(mr, clear_space, mangle_space);
301 set_concurrent_iteration_safe_limit(top());
302 }
303
clear(bool mangle_space)304 void ContiguousSpace::clear(bool mangle_space) {
305 set_top(bottom());
306 set_saved_mark();
307 CompactibleSpace::clear(mangle_space);
308 }
309
is_free_block(const HeapWord * p) const310 bool ContiguousSpace::is_free_block(const HeapWord* p) const {
311 return p >= _top;
312 }
313
clear(bool mangle_space)314 void OffsetTableContigSpace::clear(bool mangle_space) {
315 ContiguousSpace::clear(mangle_space);
316 _offsets.initialize_threshold();
317 }
318
set_bottom(HeapWord * new_bottom)319 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
320 Space::set_bottom(new_bottom);
321 _offsets.set_bottom(new_bottom);
322 }
323
set_end(HeapWord * new_end)324 void OffsetTableContigSpace::set_end(HeapWord* new_end) {
325 // Space should not advertize an increase in size
326 // until after the underlying offest table has been enlarged.
327 _offsets.resize(pointer_delta(new_end, bottom()));
328 Space::set_end(new_end);
329 }
330
331 #ifndef PRODUCT
332
set_top_for_allocations(HeapWord * v)333 void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
334 mangler()->set_top_for_allocations(v);
335 }
set_top_for_allocations()336 void ContiguousSpace::set_top_for_allocations() {
337 mangler()->set_top_for_allocations(top());
338 }
check_mangled_unused_area(HeapWord * limit)339 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
340 mangler()->check_mangled_unused_area(limit);
341 }
342
check_mangled_unused_area_complete()343 void ContiguousSpace::check_mangled_unused_area_complete() {
344 mangler()->check_mangled_unused_area_complete();
345 }
346
347 // Mangled only the unused space that has not previously
348 // been mangled and that has not been allocated since being
349 // mangled.
mangle_unused_area()350 void ContiguousSpace::mangle_unused_area() {
351 mangler()->mangle_unused_area();
352 }
mangle_unused_area_complete()353 void ContiguousSpace::mangle_unused_area_complete() {
354 mangler()->mangle_unused_area_complete();
355 }
mangle_region(MemRegion mr)356 void ContiguousSpace::mangle_region(MemRegion mr) {
357 // Although this method uses SpaceMangler::mangle_region() which
358 // is not specific to a space, the when the ContiguousSpace version
359 // is called, it is always with regard to a space and this
360 // bounds checking is appropriate.
361 MemRegion space_mr(bottom(), end());
362 assert(space_mr.contains(mr), "Mangling outside space");
363 SpaceMangler::mangle_region(mr);
364 }
365 #endif // NOT_PRODUCT
366
initialize(MemRegion mr,bool clear_space,bool mangle_space)367 void CompactibleSpace::initialize(MemRegion mr,
368 bool clear_space,
369 bool mangle_space) {
370 Space::initialize(mr, clear_space, mangle_space);
371 set_compaction_top(bottom());
372 _next_compaction_space = NULL;
373 }
374
clear(bool mangle_space)375 void CompactibleSpace::clear(bool mangle_space) {
376 Space::clear(mangle_space);
377 _compaction_top = bottom();
378 }
379
forward(oop q,size_t size,CompactPoint * cp,HeapWord * compact_top)380 HeapWord* CompactibleSpace::forward(oop q, size_t size,
381 CompactPoint* cp, HeapWord* compact_top) {
382 // q is alive
383 // First check if we should switch compaction space
384 assert(this == cp->space, "'this' should be current compaction space.");
385 size_t compaction_max_size = pointer_delta(end(), compact_top);
386 while (size > compaction_max_size) {
387 // switch to next compaction space
388 cp->space->set_compaction_top(compact_top);
389 cp->space = cp->space->next_compaction_space();
390 if (cp->space == NULL) {
391 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
392 assert(cp->gen != NULL, "compaction must succeed");
393 cp->space = cp->gen->first_compaction_space();
394 assert(cp->space != NULL, "generation must have a first compaction space");
395 }
396 compact_top = cp->space->bottom();
397 cp->space->set_compaction_top(compact_top);
398 cp->threshold = cp->space->initialize_threshold();
399 compaction_max_size = pointer_delta(cp->space->end(), compact_top);
400 }
401
402 // store the forwarding pointer into the mark word
403 if ((HeapWord*)q != compact_top) {
404 q->forward_to(oop(compact_top));
405 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
406 } else {
407 // if the object isn't moving we can just set the mark to the default
408 // mark and handle it specially later on.
409 q->init_mark();
410 assert(q->forwardee() == NULL, "should be forwarded to NULL");
411 }
412
413 compact_top += size;
414
415 // we need to update the offset table so that the beginnings of objects can be
416 // found during scavenge. Note that we are updating the offset table based on
417 // where the object will be once the compaction phase finishes.
418 if (compact_top > cp->threshold)
419 cp->threshold =
420 cp->space->cross_threshold(compact_top - size, compact_top);
421 return compact_top;
422 }
423
424
insert_deadspace(size_t & allowed_deadspace_words,HeapWord * q,size_t deadlength)425 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
426 HeapWord* q, size_t deadlength) {
427 if (allowed_deadspace_words >= deadlength) {
428 allowed_deadspace_words -= deadlength;
429 CollectedHeap::fill_with_object(q, deadlength);
430 oop(q)->set_mark(oop(q)->mark()->set_marked());
431 assert((int) deadlength == oop(q)->size(), "bad filler object size");
432 // Recall that we required "q == compaction_top".
433 return true;
434 } else {
435 allowed_deadspace_words = 0;
436 return false;
437 }
438 }
439
440 #define block_is_always_obj(q) true
441 #define obj_size(q) oop(q)->size()
442 #define adjust_obj_size(s) s
443
prepare_for_compaction(CompactPoint * cp)444 void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) {
445 SCAN_AND_FORWARD(cp, end, block_is_obj, block_size);
446 }
447
448 // Faster object search.
prepare_for_compaction(CompactPoint * cp)449 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
450 SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
451 }
452
adjust_pointers()453 void Space::adjust_pointers() {
454 // adjust all the interior pointers to point at the new locations of objects
455 // Used by MarkSweep::mark_sweep_phase3()
456
457 // First check to see if there is any work to be done.
458 if (used() == 0) {
459 return; // Nothing to do.
460 }
461
462 // Otherwise...
463 HeapWord* q = bottom();
464 HeapWord* t = end();
465
466 debug_only(HeapWord* prev_q = NULL);
467 while (q < t) {
468 if (oop(q)->is_gc_marked()) {
469 // q is alive
470
471 // point all the oops to the new location
472 size_t size = oop(q)->adjust_pointers();
473
474 debug_only(prev_q = q);
475
476 q += size;
477 } else {
478 // q is not a live object. But we're not in a compactible space,
479 // So we don't have live ranges.
480 debug_only(prev_q = q);
481 q += block_size(q);
482 assert(q > prev_q, "we should be moving forward through memory");
483 }
484 }
485 assert(q == t, "just checking");
486 }
487
adjust_pointers()488 void CompactibleSpace::adjust_pointers() {
489 // Check first is there is any work to do.
490 if (used() == 0) {
491 return; // Nothing to do.
492 }
493
494 SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
495 }
496
compact()497 void CompactibleSpace::compact() {
498 SCAN_AND_COMPACT(obj_size);
499 }
500
print_short() const501 void Space::print_short() const { print_short_on(tty); }
502
print_short_on(outputStream * st) const503 void Space::print_short_on(outputStream* st) const {
504 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
505 (int) ((double) used() * 100 / capacity()));
506 }
507
print() const508 void Space::print() const { print_on(tty); }
509
print_on(outputStream * st) const510 void Space::print_on(outputStream* st) const {
511 print_short_on(st);
512 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
513 bottom(), end());
514 }
515
print_on(outputStream * st) const516 void ContiguousSpace::print_on(outputStream* st) const {
517 print_short_on(st);
518 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
519 bottom(), top(), end());
520 }
521
print_on(outputStream * st) const522 void OffsetTableContigSpace::print_on(outputStream* st) const {
523 print_short_on(st);
524 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
525 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
526 bottom(), top(), _offsets.threshold(), end());
527 }
528
verify() const529 void ContiguousSpace::verify() const {
530 HeapWord* p = bottom();
531 HeapWord* t = top();
532 HeapWord* prev_p = NULL;
533 while (p < t) {
534 oop(p)->verify();
535 prev_p = p;
536 p += oop(p)->size();
537 }
538 guarantee(p == top(), "end of last object must match end of space");
539 if (top() != end()) {
540 guarantee(top() == block_start_const(end()-1) &&
541 top() == block_start_const(top()),
542 "top should be start of unallocated block, if it exists");
543 }
544 }
545
oop_iterate(ExtendedOopClosure * blk)546 void Space::oop_iterate(ExtendedOopClosure* blk) {
547 ObjectToOopClosure blk2(blk);
548 object_iterate(&blk2);
549 }
550
obj_is_alive(const HeapWord * p) const551 bool Space::obj_is_alive(const HeapWord* p) const {
552 assert (block_is_obj(p), "The address should point to an object");
553 return true;
554 }
555
556 #if INCLUDE_ALL_GCS
557 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
558 \
559 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
560 HeapWord* obj_addr = mr.start(); \
561 HeapWord* t = mr.end(); \
562 while (obj_addr < t) { \
563 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \
564 obj_addr += oop(obj_addr)->oop_iterate(blk); \
565 } \
566 }
567
ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)568 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
569
570 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
571 #endif // INCLUDE_ALL_GCS
572
573 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
574 if (is_empty()) return;
575 HeapWord* obj_addr = bottom();
576 HeapWord* t = top();
577 // Could call objects iterate, but this is easier.
578 while (obj_addr < t) {
579 obj_addr += oop(obj_addr)->oop_iterate(blk);
580 }
581 }
582
object_iterate(ObjectClosure * blk)583 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
584 if (is_empty()) return;
585 WaterMark bm = bottom_mark();
586 object_iterate_from(bm, blk);
587 }
588
589 // For a continguous space object_iterate() and safe_object_iterate()
590 // are the same.
safe_object_iterate(ObjectClosure * blk)591 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
592 object_iterate(blk);
593 }
594
object_iterate_from(WaterMark mark,ObjectClosure * blk)595 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
596 assert(mark.space() == this, "Mark does not match space");
597 HeapWord* p = mark.point();
598 while (p < top()) {
599 blk->do_object(oop(p));
600 p += oop(p)->size();
601 }
602 }
603
604 HeapWord*
object_iterate_careful(ObjectClosureCareful * blk)605 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
606 HeapWord * limit = concurrent_iteration_safe_limit();
607 assert(limit <= top(), "sanity check");
608 for (HeapWord* p = bottom(); p < limit;) {
609 size_t size = blk->do_object_careful(oop(p));
610 if (size == 0) {
611 return p; // failed at p
612 } else {
613 p += size;
614 }
615 }
616 return NULL; // all done
617 }
618
619 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
620 \
621 void ContiguousSpace:: \
622 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
623 HeapWord* t; \
624 HeapWord* p = saved_mark_word(); \
625 assert(p != NULL, "expected saved mark"); \
626 \
627 const intx interval = PrefetchScanIntervalInBytes; \
628 do { \
629 t = top(); \
630 while (p < t) { \
631 Prefetch::write(p, interval); \
632 debug_only(HeapWord* prev = p); \
633 oop m = oop(p); \
634 p += m->oop_iterate(blk); \
635 } \
636 } while (t < top()); \
637 \
638 set_saved_mark_word(p); \
639 }
640
ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)641 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
642
643 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
644
645 // Very general, slow implementation.
646 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
647 assert(MemRegion(bottom(), end()).contains(p),
648 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
649 p, bottom(), end()));
650 if (p >= top()) {
651 return top();
652 } else {
653 HeapWord* last = bottom();
654 HeapWord* cur = last;
655 while (cur <= p) {
656 last = cur;
657 cur += oop(cur)->size();
658 }
659 assert(oop(last)->is_oop(),
660 err_msg(PTR_FORMAT " should be an object start", last));
661 return last;
662 }
663 }
664
block_size(const HeapWord * p) const665 size_t ContiguousSpace::block_size(const HeapWord* p) const {
666 assert(MemRegion(bottom(), end()).contains(p),
667 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
668 p, bottom(), end()));
669 HeapWord* current_top = top();
670 assert(p <= current_top,
671 err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT,
672 p, current_top));
673 assert(p == current_top || oop(p)->is_oop(),
674 err_msg("p (" PTR_FORMAT ") is not a block start - "
675 "current_top: " PTR_FORMAT ", is_oop: %s",
676 p, current_top, BOOL_TO_STR(oop(p)->is_oop())));
677 if (p < current_top) {
678 return oop(p)->size();
679 } else {
680 assert(p == current_top, "just checking");
681 return pointer_delta(end(), (HeapWord*) p);
682 }
683 }
684
685 // This version requires locking.
allocate_impl(size_t size,HeapWord * const end_value)686 inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
687 HeapWord* const end_value) {
688 assert(Heap_lock->owned_by_self() ||
689 (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()),
690 "not locked");
691 HeapWord* obj = top();
692 if (pointer_delta(end_value, obj) >= size) {
693 HeapWord* new_top = obj + size;
694 set_top(new_top);
695 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
696 return obj;
697 } else {
698 return NULL;
699 }
700 }
701
702 // This version is lock-free.
par_allocate_impl(size_t size,HeapWord * const end_value)703 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
704 HeapWord* const end_value) {
705 do {
706 HeapWord* obj = top();
707 if (pointer_delta(end_value, obj) >= size) {
708 HeapWord* new_top = obj + size;
709 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
710 // result can be one of two:
711 // the old top value: the exchange succeeded
712 // otherwise: the new value of the top is returned.
713 if (result == obj) {
714 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
715 return obj;
716 }
717 } else {
718 return NULL;
719 }
720 } while (true);
721 }
722
allocate_aligned(size_t size)723 HeapWord* ContiguousSpace::allocate_aligned(size_t size) {
724 assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked");
725 HeapWord* end_value = end();
726
727 HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes);
728 if (obj == NULL) {
729 return NULL;
730 }
731
732 if (pointer_delta(end_value, obj) >= size) {
733 HeapWord* new_top = obj + size;
734 set_top(new_top);
735 assert(is_ptr_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top),
736 "checking alignment");
737 return obj;
738 } else {
739 set_top(obj);
740 return NULL;
741 }
742 }
743
744 // Requires locking.
allocate(size_t size)745 HeapWord* ContiguousSpace::allocate(size_t size) {
746 return allocate_impl(size, end());
747 }
748
749 // Lock-free.
par_allocate(size_t size)750 HeapWord* ContiguousSpace::par_allocate(size_t size) {
751 return par_allocate_impl(size, end());
752 }
753
allocate_temporary_filler(int factor)754 void ContiguousSpace::allocate_temporary_filler(int factor) {
755 // allocate temporary type array decreasing free size with factor 'factor'
756 assert(factor >= 0, "just checking");
757 size_t size = pointer_delta(end(), top());
758
759 // if space is full, return
760 if (size == 0) return;
761
762 if (factor > 0) {
763 size -= size/factor;
764 }
765 size = align_object_size(size);
766
767 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
768 if (size >= (size_t)align_object_size(array_header_size)) {
769 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
770 // allocate uninitialized int array
771 typeArrayOop t = (typeArrayOop) allocate(size);
772 assert(t != NULL, "allocation should succeed");
773 t->set_mark(markOopDesc::prototype());
774 t->set_klass(Universe::intArrayKlassObj());
775 t->set_length((int)length);
776 } else {
777 assert(size == CollectedHeap::min_fill_size(),
778 "size for smallest fake object doesn't match");
779 instanceOop obj = (instanceOop) allocate(size);
780 obj->set_mark(markOopDesc::prototype());
781 obj->set_klass_gap(0);
782 obj->set_klass(SystemDictionary::Object_klass());
783 }
784 }
785
clear(bool mangle_space)786 void EdenSpace::clear(bool mangle_space) {
787 ContiguousSpace::clear(mangle_space);
788 set_soft_end(end());
789 }
790
791 // Requires locking.
allocate(size_t size)792 HeapWord* EdenSpace::allocate(size_t size) {
793 return allocate_impl(size, soft_end());
794 }
795
796 // Lock-free.
par_allocate(size_t size)797 HeapWord* EdenSpace::par_allocate(size_t size) {
798 return par_allocate_impl(size, soft_end());
799 }
800
par_allocate(size_t size)801 HeapWord* ConcEdenSpace::par_allocate(size_t size)
802 {
803 do {
804 // The invariant is top() should be read before end() because
805 // top() can't be greater than end(), so if an update of _soft_end
806 // occurs between 'end_val = end();' and 'top_val = top();' top()
807 // also can grow up to the new end() and the condition
808 // 'top_val > end_val' is true. To ensure the loading order
809 // OrderAccess::loadload() is required after top() read.
810 HeapWord* obj = top();
811 OrderAccess::loadload();
812 if (pointer_delta(*soft_end_addr(), obj) >= size) {
813 HeapWord* new_top = obj + size;
814 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
815 // result can be one of two:
816 // the old top value: the exchange succeeded
817 // otherwise: the new value of the top is returned.
818 if (result == obj) {
819 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
820 return obj;
821 }
822 } else {
823 return NULL;
824 }
825 } while (true);
826 }
827
828
initialize_threshold()829 HeapWord* OffsetTableContigSpace::initialize_threshold() {
830 return _offsets.initialize_threshold();
831 }
832
cross_threshold(HeapWord * start,HeapWord * end)833 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
834 _offsets.alloc_block(start, end);
835 return _offsets.threshold();
836 }
837
OffsetTableContigSpace(BlockOffsetSharedArray * sharedOffsetArray,MemRegion mr)838 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
839 MemRegion mr) :
840 _offsets(sharedOffsetArray, mr),
841 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
842 {
843 _offsets.set_contig_space(this);
844 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
845 }
846
847 #define OBJ_SAMPLE_INTERVAL 0
848 #define BLOCK_SAMPLE_INTERVAL 100
849
verify() const850 void OffsetTableContigSpace::verify() const {
851 HeapWord* p = bottom();
852 HeapWord* prev_p = NULL;
853 int objs = 0;
854 int blocks = 0;
855
856 if (VerifyObjectStartArray) {
857 _offsets.verify();
858 }
859
860 while (p < top()) {
861 size_t size = oop(p)->size();
862 // For a sampling of objects in the space, find it using the
863 // block offset table.
864 if (blocks == BLOCK_SAMPLE_INTERVAL) {
865 guarantee(p == block_start_const(p + (size/2)),
866 "check offset computation");
867 blocks = 0;
868 } else {
869 blocks++;
870 }
871
872 if (objs == OBJ_SAMPLE_INTERVAL) {
873 oop(p)->verify();
874 objs = 0;
875 } else {
876 objs++;
877 }
878 prev_p = p;
879 p += size;
880 }
881 guarantee(p == top(), "end of last object must match end of space");
882 }
883
884
allowed_dead_ratio() const885 size_t TenuredSpace::allowed_dead_ratio() const {
886 return MarkSweepDeadRatio;
887 }
888