1 /*
2 * Copyright (c) 2005, 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.
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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP
27
28 #include "gc_implementation/parallelScavenge/objectStartArray.hpp"
29 #include "gc_implementation/parallelScavenge/parMarkBitMap.hpp"
30 #include "gc_implementation/parallelScavenge/psCompactionManager.hpp"
31 #include "gc_implementation/shared/collectorCounters.hpp"
32 #include "gc_implementation/shared/markSweep.hpp"
33 #include "gc_implementation/shared/mutableSpace.hpp"
34 #include "memory/sharedHeap.hpp"
35 #include "oops/oop.hpp"
36
37 class ParallelScavengeHeap;
38 class PSAdaptiveSizePolicy;
39 class PSYoungGen;
40 class PSOldGen;
41 class PSPermGen;
42 class ParCompactionManager;
43 class ParallelTaskTerminator;
44 class PSParallelCompact;
45 class GCTaskManager;
46 class GCTaskQueue;
47 class PreGCValues;
48 class MoveAndUpdateClosure;
49 class RefProcTaskExecutor;
50 class ParallelOldTracer;
51 class STWGCTimer;
52
53 // The SplitInfo class holds the information needed to 'split' a source region
54 // so that the live data can be copied to two destination *spaces*. Normally,
55 // all the live data in a region is copied to a single destination space (e.g.,
56 // everything live in a region in eden is copied entirely into the old gen).
57 // However, when the heap is nearly full, all the live data in eden may not fit
58 // into the old gen. Copying only some of the regions from eden to old gen
59 // requires finding a region that does not contain a partial object (i.e., no
60 // live object crosses the region boundary) somewhere near the last object that
61 // does fit into the old gen. Since it's not always possible to find such a
62 // region, splitting is necessary for predictable behavior.
63 //
64 // A region is always split at the end of the partial object. This avoids
65 // additional tests when calculating the new location of a pointer, which is a
66 // very hot code path. The partial object and everything to its left will be
67 // copied to another space (call it dest_space_1). The live data to the right
68 // of the partial object will be copied either within the space itself, or to a
69 // different destination space (distinct from dest_space_1).
70 //
71 // Split points are identified during the summary phase, when region
72 // destinations are computed: data about the split, including the
73 // partial_object_size, is recorded in a SplitInfo record and the
74 // partial_object_size field in the summary data is set to zero. The zeroing is
75 // possible (and necessary) since the partial object will move to a different
76 // destination space than anything to its right, thus the partial object should
77 // not affect the locations of any objects to its right.
78 //
79 // The recorded data is used during the compaction phase, but only rarely: when
80 // the partial object on the split region will be copied across a destination
81 // region boundary. This test is made once each time a region is filled, and is
82 // a simple address comparison, so the overhead is negligible (see
83 // PSParallelCompact::first_src_addr()).
84 //
85 // Notes:
86 //
87 // Only regions with partial objects are split; a region without a partial
88 // object does not need any extra bookkeeping.
89 //
90 // At most one region is split per space, so the amount of data required is
91 // constant.
92 //
93 // A region is split only when the destination space would overflow. Once that
94 // happens, the destination space is abandoned and no other data (even from
95 // other source spaces) is targeted to that destination space. Abandoning the
96 // destination space may leave a somewhat large unused area at the end, if a
97 // large object caused the overflow.
98 //
99 // Future work:
100 //
101 // More bookkeeping would be required to continue to use the destination space.
102 // The most general solution would allow data from regions in two different
103 // source spaces to be "joined" in a single destination region. At the very
104 // least, additional code would be required in next_src_region() to detect the
105 // join and skip to an out-of-order source region. If the join region was also
106 // the last destination region to which a split region was copied (the most
107 // likely case), then additional work would be needed to get fill_region() to
108 // stop iteration and switch to a new source region at the right point. Basic
109 // idea would be to use a fake value for the top of the source space. It is
110 // doable, if a bit tricky.
111 //
112 // A simpler (but less general) solution would fill the remainder of the
113 // destination region with a dummy object and continue filling the next
114 // destination region.
115
116 class SplitInfo
117 {
118 public:
119 // Return true if this split info is valid (i.e., if a split has been
120 // recorded). The very first region cannot have a partial object and thus is
121 // never split, so 0 is the 'invalid' value.
122 bool is_valid() const { return _src_region_idx > 0; }
123
124 // Return true if this split holds data for the specified source region.
125 inline bool is_split(size_t source_region) const;
126
127 // The index of the split region, the size of the partial object on that
128 // region and the destination of the partial object.
129 size_t src_region_idx() const { return _src_region_idx; }
130 size_t partial_obj_size() const { return _partial_obj_size; }
131 HeapWord* destination() const { return _destination; }
132
133 // The destination count of the partial object referenced by this split
134 // (either 1 or 2). This must be added to the destination count of the
135 // remainder of the source region.
136 unsigned int destination_count() const { return _destination_count; }
137
138 // If a word within the partial object will be written to the first word of a
139 // destination region, this is the address of the destination region;
140 // otherwise this is NULL.
141 HeapWord* dest_region_addr() const { return _dest_region_addr; }
142
143 // If a word within the partial object will be written to the first word of a
144 // destination region, this is the address of that word within the partial
145 // object; otherwise this is NULL.
146 HeapWord* first_src_addr() const { return _first_src_addr; }
147
148 // Record the data necessary to split the region src_region_idx.
149 void record(size_t src_region_idx, size_t partial_obj_size,
150 HeapWord* destination);
151
152 void clear();
153
154 DEBUG_ONLY(void verify_clear();)
155
156 private:
157 size_t _src_region_idx;
158 size_t _partial_obj_size;
159 HeapWord* _destination;
160 unsigned int _destination_count;
161 HeapWord* _dest_region_addr;
162 HeapWord* _first_src_addr;
163 };
164
165 inline bool SplitInfo::is_split(size_t region_idx) const
166 {
167 return _src_region_idx == region_idx && is_valid();
168 }
169
170 class SpaceInfo
171 {
172 public:
173 MutableSpace* space() const { return _space; }
174
175 // Where the free space will start after the collection. Valid only after the
176 // summary phase completes.
177 HeapWord* new_top() const { return _new_top; }
178
179 // Allows new_top to be set.
180 HeapWord** new_top_addr() { return &_new_top; }
181
182 // Where the smallest allowable dense prefix ends (used only for perm gen).
183 HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
184
185 // Where the dense prefix ends, or the compacted region begins.
186 HeapWord* dense_prefix() const { return _dense_prefix; }
187
188 // The start array for the (generation containing the) space, or NULL if there
189 // is no start array.
190 ObjectStartArray* start_array() const { return _start_array; }
191
192 SplitInfo& split_info() { return _split_info; }
193
194 void set_space(MutableSpace* s) { _space = s; }
195 void set_new_top(HeapWord* addr) { _new_top = addr; }
196 void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
197 void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; }
198 void set_start_array(ObjectStartArray* s) { _start_array = s; }
199
200 void publish_new_top() const { _space->set_top(_new_top); }
201
202 private:
203 MutableSpace* _space;
204 HeapWord* _new_top;
205 HeapWord* _min_dense_prefix;
206 HeapWord* _dense_prefix;
207 ObjectStartArray* _start_array;
208 SplitInfo _split_info;
209 };
210
211 class ParallelCompactData
212 {
213 public:
214 // Sizes are in HeapWords, unless indicated otherwise.
215 static const size_t Log2RegionSize;
216 static const size_t RegionSize;
217 static const size_t RegionSizeBytes;
218
219 // Mask for the bits in a size_t to get an offset within a region.
220 static const size_t RegionSizeOffsetMask;
221 // Mask for the bits in a pointer to get an offset within a region.
222 static const size_t RegionAddrOffsetMask;
223 // Mask for the bits in a pointer to get the address of the start of a region.
224 static const size_t RegionAddrMask;
225
226 class RegionData
227 {
228 public:
229 // Destination address of the region.
230 HeapWord* destination() const { return _destination; }
231
232 // The first region containing data destined for this region.
233 size_t source_region() const { return _source_region; }
234
235 // The object (if any) starting in this region and ending in a different
236 // region that could not be updated during the main (parallel) compaction
237 // phase. This is different from _partial_obj_addr, which is an object that
238 // extends onto a source region. However, the two uses do not overlap in
239 // time, so the same field is used to save space.
240 HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
241
242 // The starting address of the partial object extending onto the region.
243 HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
244
245 // Size of the partial object extending onto the region (words).
246 size_t partial_obj_size() const { return _partial_obj_size; }
247
248 // Size of live data that lies within this region due to objects that start
249 // in this region (words). This does not include the partial object
250 // extending onto the region (if any), or the part of an object that extends
251 // onto the next region (if any).
252 size_t live_obj_size() const { return _dc_and_los & los_mask; }
253
254 // Total live data that lies within the region (words).
255 size_t data_size() const { return partial_obj_size() + live_obj_size(); }
256
257 // The destination_count is the number of other regions to which data from
258 // this region will be copied. At the end of the summary phase, the valid
259 // values of destination_count are
260 //
261 // 0 - data from the region will be compacted completely into itself, or the
262 // region is empty. The region can be claimed and then filled.
263 // 1 - data from the region will be compacted into 1 other region; some
264 // data from the region may also be compacted into the region itself.
265 // 2 - data from the region will be copied to 2 other regions.
266 //
267 // During compaction as regions are emptied, the destination_count is
268 // decremented (atomically) and when it reaches 0, it can be claimed and
269 // then filled.
270 //
271 // A region is claimed for processing by atomically changing the
272 // destination_count to the claimed value (dc_claimed). After a region has
273 // been filled, the destination_count should be set to the completed value
274 // (dc_completed).
275 inline uint destination_count() const;
276 inline uint destination_count_raw() const;
277
278 // The location of the java heap data that corresponds to this region.
279 inline HeapWord* data_location() const;
280
281 // The highest address referenced by objects in this region.
282 inline HeapWord* highest_ref() const;
283
284 // Whether this region is available to be claimed, has been claimed, or has
285 // been completed.
286 //
287 // Minor subtlety: claimed() returns true if the region is marked
288 // completed(), which is desirable since a region must be claimed before it
289 // can be completed.
290 bool available() const { return _dc_and_los < dc_one; }
291 bool claimed() const { return _dc_and_los >= dc_claimed; }
292 bool completed() const { return _dc_and_los >= dc_completed; }
293
294 // These are not atomic.
295 void set_destination(HeapWord* addr) { _destination = addr; }
296 void set_source_region(size_t region) { _source_region = region; }
297 void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
298 void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
299 void set_partial_obj_size(size_t words) {
300 _partial_obj_size = (region_sz_t) words;
301 }
302
303 inline void set_destination_count(uint count);
304 inline void set_live_obj_size(size_t words);
305 inline void set_data_location(HeapWord* addr);
306 inline void set_completed();
307 inline bool claim_unsafe();
308
309 // These are atomic.
310 inline void add_live_obj(size_t words);
311 inline void set_highest_ref(HeapWord* addr);
312 inline void decrement_destination_count();
313 inline bool claim();
314
315 private:
316 // The type used to represent object sizes within a region.
317 typedef uint region_sz_t;
318
319 // Constants for manipulating the _dc_and_los field, which holds both the
320 // destination count and live obj size. The live obj size lives at the
321 // least significant end so no masking is necessary when adding.
322 static const region_sz_t dc_shift; // Shift amount.
323 static const region_sz_t dc_mask; // Mask for destination count.
324 static const region_sz_t dc_one; // 1, shifted appropriately.
325 static const region_sz_t dc_claimed; // Region has been claimed.
326 static const region_sz_t dc_completed; // Region has been completed.
327 static const region_sz_t los_mask; // Mask for live obj size.
328
329 HeapWord* _destination;
330 size_t _source_region;
331 HeapWord* _partial_obj_addr;
332 region_sz_t _partial_obj_size;
333 region_sz_t volatile _dc_and_los;
334 #ifdef ASSERT
335 // These enable optimizations that are only partially implemented. Use
336 // debug builds to prevent the code fragments from breaking.
337 HeapWord* _data_location;
338 HeapWord* _highest_ref;
339 #endif // #ifdef ASSERT
340
341 #ifdef ASSERT
342 public:
343 uint _pushed; // 0 until region is pushed onto a worker's stack
344 private:
345 #endif
346 };
347
348 public:
349 ParallelCompactData();
350 bool initialize(MemRegion covered_region);
351
352 size_t region_count() const { return _region_count; }
353
354 // Convert region indices to/from RegionData pointers.
355 inline RegionData* region(size_t region_idx) const;
356 inline size_t region(const RegionData* const region_ptr) const;
357
358 // Returns true if the given address is contained within the region
359 bool region_contains(size_t region_index, HeapWord* addr);
360
361 void add_obj(HeapWord* addr, size_t len);
362 void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
363
364 // Fill in the regions covering [beg, end) so that no data moves; i.e., the
365 // destination of region n is simply the start of region n. The argument beg
366 // must be region-aligned; end need not be.
367 void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
368
369 HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info,
370 HeapWord* destination, HeapWord* target_end,
371 HeapWord** target_next);
372 bool summarize(SplitInfo& split_info,
373 HeapWord* source_beg, HeapWord* source_end,
374 HeapWord** source_next,
375 HeapWord* target_beg, HeapWord* target_end,
376 HeapWord** target_next);
377
378 void clear();
379 void clear_range(size_t beg_region, size_t end_region);
380 void clear_range(HeapWord* beg, HeapWord* end) {
381 clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
382 }
383
384 // Return the number of words between addr and the start of the region
385 // containing addr.
386 inline size_t region_offset(const HeapWord* addr) const;
387
388 // Convert addresses to/from a region index or region pointer.
389 inline size_t addr_to_region_idx(const HeapWord* addr) const;
390 inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
391 inline HeapWord* region_to_addr(size_t region) const;
392 inline HeapWord* region_to_addr(size_t region, size_t offset) const;
393 inline HeapWord* region_to_addr(const RegionData* region) const;
394
395 inline HeapWord* region_align_down(HeapWord* addr) const;
396 inline HeapWord* region_align_up(HeapWord* addr) const;
397 inline bool is_region_aligned(HeapWord* addr) const;
398
399 // Return the address one past the end of the partial object.
400 HeapWord* partial_obj_end(size_t region_idx) const;
401
402 // Return the new location of the object p after the
403 // the compaction.
404 HeapWord* calc_new_pointer(HeapWord* addr);
405
406 HeapWord* calc_new_pointer(oop p) {
407 return calc_new_pointer((HeapWord*) p);
408 }
409
410 // Return the updated address for the given klass
411 klassOop calc_new_klass(klassOop);
412
413 #ifdef ASSERT
414 void verify_clear(const PSVirtualSpace* vspace);
415 void verify_clear();
416 #endif // #ifdef ASSERT
417
418 private:
419 bool initialize_region_data(size_t region_size);
420 PSVirtualSpace* create_vspace(size_t count, size_t element_size);
421
422 private:
423 HeapWord* _region_start;
424 #ifdef ASSERT
425 HeapWord* _region_end;
426 #endif // #ifdef ASSERT
427
428 PSVirtualSpace* _region_vspace;
429 RegionData* _region_data;
430 size_t _region_count;
431 };
432
433 inline uint
434 ParallelCompactData::RegionData::destination_count_raw() const
435 {
436 return _dc_and_los & dc_mask;
437 }
438
439 inline uint
440 ParallelCompactData::RegionData::destination_count() const
441 {
442 return destination_count_raw() >> dc_shift;
443 }
444
445 inline void
446 ParallelCompactData::RegionData::set_destination_count(uint count)
447 {
448 assert(count <= (dc_completed >> dc_shift), "count too large");
449 const region_sz_t live_sz = (region_sz_t) live_obj_size();
450 _dc_and_los = (count << dc_shift) | live_sz;
451 }
452
453 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
454 {
455 assert(words <= los_mask, "would overflow");
456 _dc_and_los = destination_count_raw() | (region_sz_t)words;
457 }
458
459 inline void ParallelCompactData::RegionData::decrement_destination_count()
460 {
461 assert(_dc_and_los < dc_claimed, "already claimed");
462 assert(_dc_and_los >= dc_one, "count would go negative");
463 Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);
464 }
465
466 inline HeapWord* ParallelCompactData::RegionData::data_location() const
467 {
468 DEBUG_ONLY(return _data_location;)
469 NOT_DEBUG(return NULL;)
470 }
471
472 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
473 {
474 DEBUG_ONLY(return _highest_ref;)
475 NOT_DEBUG(return NULL;)
476 }
477
478 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
479 {
480 DEBUG_ONLY(_data_location = addr;)
481 }
482
483 inline void ParallelCompactData::RegionData::set_completed()
484 {
485 assert(claimed(), "must be claimed first");
486 _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
487 }
488
489 // MT-unsafe claiming of a region. Should only be used during single threaded
490 // execution.
491 inline bool ParallelCompactData::RegionData::claim_unsafe()
492 {
493 if (available()) {
494 _dc_and_los |= dc_claimed;
495 return true;
496 }
497 return false;
498 }
499
500 inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
501 {
502 assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
503 Atomic::add((int) words, (volatile int*) &_dc_and_los);
504 }
505
506 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
507 {
508 #ifdef ASSERT
509 HeapWord* tmp = _highest_ref;
510 while (addr > tmp) {
511 tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp);
512 }
513 #endif // #ifdef ASSERT
514 }
515
516 inline bool ParallelCompactData::RegionData::claim()
517 {
518 const int los = (int) live_obj_size();
519 const int old = Atomic::cmpxchg(dc_claimed | los,
520 (volatile int*) &_dc_and_los, los);
521 return old == los;
522 }
523
524 inline ParallelCompactData::RegionData*
525 ParallelCompactData::region(size_t region_idx) const
526 {
527 assert(region_idx <= region_count(), "bad arg");
528 return _region_data + region_idx;
529 }
530
531 inline size_t
532 ParallelCompactData::region(const RegionData* const region_ptr) const
533 {
534 assert(region_ptr >= _region_data, "bad arg");
535 assert(region_ptr <= _region_data + region_count(), "bad arg");
536 return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
537 }
538
539 inline size_t
540 ParallelCompactData::region_offset(const HeapWord* addr) const
541 {
542 assert(addr >= _region_start, "bad addr");
543 assert(addr <= _region_end, "bad addr");
544 return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
545 }
546
547 inline size_t
548 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
549 {
550 assert(addr >= _region_start, "bad addr");
551 assert(addr <= _region_end, "bad addr");
552 return pointer_delta(addr, _region_start) >> Log2RegionSize;
553 }
554
555 inline ParallelCompactData::RegionData*
556 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
557 {
558 return region(addr_to_region_idx(addr));
559 }
560
561 inline HeapWord*
562 ParallelCompactData::region_to_addr(size_t region) const
563 {
564 assert(region <= _region_count, "region out of range");
565 return _region_start + (region << Log2RegionSize);
566 }
567
568 inline HeapWord*
569 ParallelCompactData::region_to_addr(const RegionData* region) const
570 {
571 return region_to_addr(pointer_delta(region, _region_data,
572 sizeof(RegionData)));
573 }
574
575 inline HeapWord*
576 ParallelCompactData::region_to_addr(size_t region, size_t offset) const
577 {
578 assert(region <= _region_count, "region out of range");
579 assert(offset < RegionSize, "offset too big"); // This may be too strict.
580 return region_to_addr(region) + offset;
581 }
582
583 inline HeapWord*
584 ParallelCompactData::region_align_down(HeapWord* addr) const
585 {
586 assert(addr >= _region_start, "bad addr");
587 assert(addr < _region_end + RegionSize, "bad addr");
588 return (HeapWord*)(size_t(addr) & RegionAddrMask);
589 }
590
591 inline HeapWord*
592 ParallelCompactData::region_align_up(HeapWord* addr) const
593 {
594 assert(addr >= _region_start, "bad addr");
595 assert(addr <= _region_end, "bad addr");
596 return region_align_down(addr + RegionSizeOffsetMask);
597 }
598
599 inline bool
600 ParallelCompactData::is_region_aligned(HeapWord* addr) const
601 {
602 return region_offset(addr) == 0;
603 }
604
605 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
606 // do_addr() method.
607 //
608 // The closure is initialized with the number of heap words to process
609 // (words_remaining()), and becomes 'full' when it reaches 0. The do_addr()
610 // methods in subclasses should update the total as words are processed. Since
611 // only one subclass actually uses this mechanism to terminate iteration, the
612 // default initial value is > 0. The implementation is here and not in the
613 // single subclass that uses it to avoid making is_full() virtual, and thus
614 // adding a virtual call per live object.
615
616 class ParMarkBitMapClosure: public StackObj {
617 public:
618 typedef ParMarkBitMap::idx_t idx_t;
619 typedef ParMarkBitMap::IterationStatus IterationStatus;
620
621 public:
622 inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
623 size_t words = max_uintx);
624
625 inline ParCompactionManager* compaction_manager() const;
626 inline ParMarkBitMap* bitmap() const;
627 inline size_t words_remaining() const;
628 inline bool is_full() const;
629 inline HeapWord* source() const;
630
631 inline void set_source(HeapWord* addr);
632
633 virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
634
635 protected:
636 inline void decrement_words_remaining(size_t words);
637
638 private:
639 ParMarkBitMap* const _bitmap;
640 ParCompactionManager* const _compaction_manager;
641 DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger.
642 size_t _words_remaining; // Words left to copy.
643
644 protected:
645 HeapWord* _source; // Next addr that would be read.
646 };
647
648 inline
649 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
650 ParCompactionManager* cm,
651 size_t words):
652 _bitmap(bitmap), _compaction_manager(cm)
653 #ifdef ASSERT
654 , _initial_words_remaining(words)
655 #endif
656 {
657 _words_remaining = words;
658 _source = NULL;
659 }
660
661 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
662 return _compaction_manager;
663 }
664
665 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
666 return _bitmap;
667 }
668
669 inline size_t ParMarkBitMapClosure::words_remaining() const {
670 return _words_remaining;
671 }
672
673 inline bool ParMarkBitMapClosure::is_full() const {
674 return words_remaining() == 0;
675 }
676
677 inline HeapWord* ParMarkBitMapClosure::source() const {
678 return _source;
679 }
680
681 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
682 _source = addr;
683 }
684
685 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
686 assert(_words_remaining >= words, "processed too many words");
687 _words_remaining -= words;
688 }
689
690 // The UseParallelOldGC collector is a stop-the-world garbage collector that
691 // does parts of the collection using parallel threads. The collection includes
692 // the tenured generation and the young generation. The permanent generation is
693 // collected at the same time as the other two generations but the permanent
694 // generation is collect by a single GC thread. The permanent generation is
695 // collected serially because of the requirement that during the processing of a
696 // klass AAA, any objects reference by AAA must already have been processed.
697 // This requirement is enforced by a left (lower address) to right (higher
698 // address) sliding compaction.
699 //
700 // There are four phases of the collection.
701 //
702 // - marking phase
703 // - summary phase
704 // - compacting phase
705 // - clean up phase
706 //
707 // Roughly speaking these phases correspond, respectively, to
708 // - mark all the live objects
709 // - calculate the destination of each object at the end of the collection
710 // - move the objects to their destination
711 // - update some references and reinitialize some variables
712 //
713 // These three phases are invoked in PSParallelCompact::invoke_no_policy(). The
714 // marking phase is implemented in PSParallelCompact::marking_phase() and does a
715 // complete marking of the heap. The summary phase is implemented in
716 // PSParallelCompact::summary_phase(). The move and update phase is implemented
717 // in PSParallelCompact::compact().
718 //
719 // A space that is being collected is divided into regions and with each region
720 // is associated an object of type ParallelCompactData. Each region is of a
721 // fixed size and typically will contain more than 1 object and may have parts
722 // of objects at the front and back of the region.
723 //
724 // region -----+---------------------+----------
725 // objects covered [ AAA )[ BBB )[ CCC )[ DDD )
726 //
727 // The marking phase does a complete marking of all live objects in the heap.
728 // The marking also compiles the size of the data for all live objects covered
729 // by the region. This size includes the part of any live object spanning onto
730 // the region (part of AAA if it is live) from the front, all live objects
731 // contained in the region (BBB and/or CCC if they are live), and the part of
732 // any live objects covered by the region that extends off the region (part of
733 // DDD if it is live). The marking phase uses multiple GC threads and marking
734 // is done in a bit array of type ParMarkBitMap. The marking of the bit map is
735 // done atomically as is the accumulation of the size of the live objects
736 // covered by a region.
737 //
738 // The summary phase calculates the total live data to the left of each region
739 // XXX. Based on that total and the bottom of the space, it can calculate the
740 // starting location of the live data in XXX. The summary phase calculates for
741 // each region XXX quantites such as
742 //
743 // - the amount of live data at the beginning of a region from an object
744 // entering the region.
745 // - the location of the first live data on the region
746 // - a count of the number of regions receiving live data from XXX.
747 //
748 // See ParallelCompactData for precise details. The summary phase also
749 // calculates the dense prefix for the compaction. The dense prefix is a
750 // portion at the beginning of the space that is not moved. The objects in the
751 // dense prefix do need to have their object references updated. See method
752 // summarize_dense_prefix().
753 //
754 // The summary phase is done using 1 GC thread.
755 //
756 // The compaction phase moves objects to their new location and updates all
757 // references in the object.
758 //
759 // A current exception is that objects that cross a region boundary are moved
760 // but do not have their references updated. References are not updated because
761 // it cannot easily be determined if the klass pointer KKK for the object AAA
762 // has been updated. KKK likely resides in a region to the left of the region
763 // containing AAA. These AAA's have there references updated at the end in a
764 // clean up phase. See the method PSParallelCompact::update_deferred_objects().
765 // An alternate strategy is being investigated for this deferral of updating.
766 //
767 // Compaction is done on a region basis. A region that is ready to be filled is
768 // put on a ready list and GC threads take region off the list and fill them. A
769 // region is ready to be filled if it empty of live objects. Such a region may
770 // have been initially empty (only contained dead objects) or may have had all
771 // its live objects copied out already. A region that compacts into itself is
772 // also ready for filling. The ready list is initially filled with empty
773 // regions and regions compacting into themselves. There is always at least 1
774 // region that can be put on the ready list. The regions are atomically added
775 // and removed from the ready list.
776
777 class PSParallelCompact : AllStatic {
778 public:
779 // Convenient access to type names.
780 typedef ParMarkBitMap::idx_t idx_t;
781 typedef ParallelCompactData::RegionData RegionData;
782
783 typedef enum {
784 perm_space_id, old_space_id, eden_space_id,
785 from_space_id, to_space_id, last_space_id
786 } SpaceId;
787
788 public:
789 // Inline closure decls
790 //
791 class IsAliveClosure: public BoolObjectClosure {
792 public:
793 virtual void do_object(oop p);
794 virtual bool do_object_b(oop p);
795 };
796
797 class KeepAliveClosure: public OopClosure {
798 private:
799 ParCompactionManager* _compaction_manager;
800 protected:
801 template <class T> inline void do_oop_work(T* p);
802 public:
803 KeepAliveClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
804 virtual void do_oop(oop* p);
805 virtual void do_oop(narrowOop* p);
806 };
807
808 // Current unused
809 class FollowRootClosure: public OopsInGenClosure {
810 private:
811 ParCompactionManager* _compaction_manager;
812 public:
813 FollowRootClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
814 virtual void do_oop(oop* p);
815 virtual void do_oop(narrowOop* p);
816 };
817
818 class FollowStackClosure: public VoidClosure {
819 private:
820 ParCompactionManager* _compaction_manager;
821 public:
822 FollowStackClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
823 virtual void do_void();
824 };
825
826 class AdjustPointerClosure: public OopsInGenClosure {
827 private:
828 bool _is_root;
829 public:
830 AdjustPointerClosure(bool is_root) : _is_root(is_root) { }
831 virtual void do_oop(oop* p);
832 virtual void do_oop(narrowOop* p);
833 // do not walk from thread stacks to the code cache on this phase
834 virtual void do_code_blob(CodeBlob* cb) const { }
835 };
836
837 friend class KeepAliveClosure;
838 friend class FollowStackClosure;
839 friend class AdjustPointerClosure;
840 friend class FollowRootClosure;
841 friend class instanceKlassKlass;
842 friend class RefProcTaskProxy;
843
844 private:
845 static STWGCTimer _gc_timer;
846 static ParallelOldTracer _gc_tracer;
847 static elapsedTimer _accumulated_time;
848 static unsigned int _total_invocations;
849 static unsigned int _maximum_compaction_gc_num;
850 static jlong _time_of_last_gc; // ms
851 static CollectorCounters* _counters;
852 static ParMarkBitMap _mark_bitmap;
853 static ParallelCompactData _summary_data;
854 static IsAliveClosure _is_alive_closure;
855 static SpaceInfo _space_info[last_space_id];
856 static bool _print_phases;
857 static AdjustPointerClosure _adjust_root_pointer_closure;
858 static AdjustPointerClosure _adjust_pointer_closure;
859
860 // Reference processing (used in ...follow_contents)
861 static ReferenceProcessor* _ref_processor;
862
863 // Updated location of intArrayKlassObj.
864 static klassOop _updated_int_array_klass_obj;
865
866 // Values computed at initialization and used by dead_wood_limiter().
867 static double _dwl_mean;
868 static double _dwl_std_dev;
869 static double _dwl_first_term;
870 static double _dwl_adjustment;
871 #ifdef ASSERT
872 static bool _dwl_initialized;
873 #endif // #ifdef ASSERT
874
875 private:
876 // Closure accessors
877 static OopClosure* adjust_pointer_closure() { return (OopClosure*)&_adjust_pointer_closure; }
878 static OopClosure* adjust_root_pointer_closure() { return (OopClosure*)&_adjust_root_pointer_closure; }
879 static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; }
880
881 static void initialize_space_info();
882
883 // Return true if details about individual phases should be printed.
884 static inline bool print_phases();
885
886 // Clear the marking bitmap and summary data that cover the specified space.
887 static void clear_data_covering_space(SpaceId id);
888
889 static void pre_compact(PreGCValues* pre_gc_values);
890 static void post_compact();
891
892 // Mark live objects
893 static void marking_phase(ParCompactionManager* cm, bool maximum_heap_compaction);
894 static void follow_weak_klass_links();
895 static void follow_mdo_weak_refs();
896
897 template <class T> static inline void adjust_pointer(T* p, bool is_root);
898 static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); }
899
900 template <class T>
901 static inline void follow_root(ParCompactionManager* cm, T* p);
902
903 // Compute the dense prefix for the designated space. This is an experimental
904 // implementation currently not used in production.
905 static HeapWord* compute_dense_prefix_via_density(const SpaceId id,
906 bool maximum_compaction);
907
908 // Methods used to compute the dense prefix.
909
910 // Compute the value of the normal distribution at x = density. The mean and
911 // standard deviation are values saved by initialize_dead_wood_limiter().
912 static inline double normal_distribution(double density);
913
914 // Initialize the static vars used by dead_wood_limiter().
915 static void initialize_dead_wood_limiter();
916
917 // Return the percentage of space that can be treated as "dead wood" (i.e.,
918 // not reclaimed).
919 static double dead_wood_limiter(double density, size_t min_percent);
920
921 // Find the first (left-most) region in the range [beg, end) that has at least
922 // dead_words of dead space to the left. The argument beg must be the first
923 // region in the space that is not completely live.
924 static RegionData* dead_wood_limit_region(const RegionData* beg,
925 const RegionData* end,
926 size_t dead_words);
927
928 // Return a pointer to the first region in the range [beg, end) that is not
929 // completely full.
930 static RegionData* first_dead_space_region(const RegionData* beg,
931 const RegionData* end);
932
933 // Return a value indicating the benefit or 'yield' if the compacted region
934 // were to start (or equivalently if the dense prefix were to end) at the
935 // candidate region. Higher values are better.
936 //
937 // The value is based on the amount of space reclaimed vs. the costs of (a)
938 // updating references in the dense prefix plus (b) copying objects and
939 // updating references in the compacted region.
940 static inline double reclaimed_ratio(const RegionData* const candidate,
941 HeapWord* const bottom,
942 HeapWord* const top,
943 HeapWord* const new_top);
944
945 // Compute the dense prefix for the designated space.
946 static HeapWord* compute_dense_prefix(const SpaceId id,
947 bool maximum_compaction);
948
949 // Return true if dead space crosses onto the specified Region; bit must be
950 // the bit index corresponding to the first word of the Region.
951 static inline bool dead_space_crosses_boundary(const RegionData* region,
952 idx_t bit);
953
954 // Summary phase utility routine to fill dead space (if any) at the dense
955 // prefix boundary. Should only be called if the the dense prefix is
956 // non-empty.
957 static void fill_dense_prefix_end(SpaceId id);
958
959 // Clear the summary data source_region field for the specified addresses.
960 static void clear_source_region(HeapWord* beg_addr, HeapWord* end_addr);
961
962 #ifndef PRODUCT
963 // Routines to provoke splitting a young gen space (ParallelOldGCSplitALot).
964
965 // Fill the region [start, start + words) with live object(s). Only usable
966 // for the old and permanent generations.
967 static void fill_with_live_objects(SpaceId id, HeapWord* const start,
968 size_t words);
969 // Include the new objects in the summary data.
970 static void summarize_new_objects(SpaceId id, HeapWord* start);
971
972 // Add live objects to a survivor space since it's rare that both survivors
973 // are non-empty.
974 static void provoke_split_fill_survivor(SpaceId id);
975
976 // Add live objects and/or choose the dense prefix to provoke splitting.
977 static void provoke_split(bool & maximum_compaction);
978 #endif
979
980 static void summarize_spaces_quick();
981 static void summarize_space(SpaceId id, bool maximum_compaction);
982 static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);
983
984 // Adjust addresses in roots. Does not adjust addresses in heap.
985 static void adjust_roots();
986
987 // Serial code executed in preparation for the compaction phase.
988 static void compact_prologue();
989
990 // Move objects to new locations.
991 static void compact_perm(ParCompactionManager* cm);
992 static void compact();
993
994 // Add available regions to the stack and draining tasks to the task queue.
995 static void enqueue_region_draining_tasks(GCTaskQueue* q,
996 uint parallel_gc_threads);
997
998 // Add dense prefix update tasks to the task queue.
999 static void enqueue_dense_prefix_tasks(GCTaskQueue* q,
1000 uint parallel_gc_threads);
1001
1002 // Add region stealing tasks to the task queue.
1003 static void enqueue_region_stealing_tasks(
1004 GCTaskQueue* q,
1005 ParallelTaskTerminator* terminator_ptr,
1006 uint parallel_gc_threads);
1007
1008 // If objects are left in eden after a collection, try to move the boundary
1009 // and absorb them into the old gen. Returns true if eden was emptied.
1010 static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1011 PSYoungGen* young_gen,
1012 PSOldGen* old_gen);
1013
1014 // Reset time since last full gc
1015 static void reset_millis_since_last_gc();
1016
1017 protected:
1018 #ifdef VALIDATE_MARK_SWEEP
1019 static GrowableArray<void*>* _root_refs_stack;
1020 static GrowableArray<oop> * _live_oops;
1021 static GrowableArray<oop> * _live_oops_moved_to;
1022 static GrowableArray<size_t>* _live_oops_size;
1023 static size_t _live_oops_index;
1024 static size_t _live_oops_index_at_perm;
1025 static GrowableArray<void*>* _other_refs_stack;
1026 static GrowableArray<void*>* _adjusted_pointers;
1027 static bool _pointer_tracking;
1028 static bool _root_tracking;
1029
1030 // The following arrays are saved since the time of the last GC and
1031 // assist in tracking down problems where someone has done an errant
1032 // store into the heap, usually to an oop that wasn't properly
1033 // handleized across a GC. If we crash or otherwise fail before the
1034 // next GC, we can query these arrays to find out the object we had
1035 // intended to do the store to (assuming it is still alive) and the
1036 // offset within that object. Covered under RecordMarkSweepCompaction.
1037 static GrowableArray<HeapWord*> * _cur_gc_live_oops;
1038 static GrowableArray<HeapWord*> * _cur_gc_live_oops_moved_to;
1039 static GrowableArray<size_t>* _cur_gc_live_oops_size;
1040 static GrowableArray<HeapWord*> * _last_gc_live_oops;
1041 static GrowableArray<HeapWord*> * _last_gc_live_oops_moved_to;
1042 static GrowableArray<size_t>* _last_gc_live_oops_size;
1043 #endif
1044
1045 public:
1046 class MarkAndPushClosure: public OopClosure {
1047 private:
1048 ParCompactionManager* _compaction_manager;
1049 public:
1050 MarkAndPushClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
1051 virtual void do_oop(oop* p);
1052 virtual void do_oop(narrowOop* p);
1053 };
1054
1055 PSParallelCompact();
1056
1057 // Convenient accessor for Universe::heap().
1058 static ParallelScavengeHeap* gc_heap() {
1059 return (ParallelScavengeHeap*)Universe::heap();
1060 }
1061
1062 static void invoke(bool maximum_heap_compaction);
1063 static bool invoke_no_policy(bool maximum_heap_compaction);
1064
1065 static void post_initialize();
1066 // Perform initialization for PSParallelCompact that requires
1067 // allocations. This should be called during the VM initialization
1068 // at a pointer where it would be appropriate to return a JNI_ENOMEM
1069 // in the event of a failure.
1070 static bool initialize();
1071
1072 // Public accessors
1073 static elapsedTimer* accumulated_time() { return &_accumulated_time; }
1074 static unsigned int total_invocations() { return _total_invocations; }
1075 static CollectorCounters* counters() { return _counters; }
1076
1077 // Used to add tasks
1078 static GCTaskManager* const gc_task_manager();
1079 static klassOop updated_int_array_klass_obj() {
1080 return _updated_int_array_klass_obj;
1081 }
1082
1083 // Marking support
1084 static inline bool mark_obj(oop obj);
1085 // Check mark and maybe push on marking stack
1086 template <class T> static inline void mark_and_push(ParCompactionManager* cm,
1087 T* p);
1088
1089 // Compaction support.
1090 // Return true if p is in the range [beg_addr, end_addr).
1091 static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
1092 static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
1093
1094 // Convenience wrappers for per-space data kept in _space_info.
1095 static inline MutableSpace* space(SpaceId space_id);
1096 static inline HeapWord* new_top(SpaceId space_id);
1097 static inline HeapWord* dense_prefix(SpaceId space_id);
1098 static inline ObjectStartArray* start_array(SpaceId space_id);
1099
1100 // Return true if the klass should be updated.
1101 static inline bool should_update_klass(klassOop k);
1102
1103 // Move and update the live objects in the specified space.
1104 static void move_and_update(ParCompactionManager* cm, SpaceId space_id);
1105
1106 // Process the end of the given region range in the dense prefix.
1107 // This includes saving any object not updated.
1108 static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
1109 size_t region_start_index,
1110 size_t region_end_index,
1111 idx_t exiting_object_offset,
1112 idx_t region_offset_start,
1113 idx_t region_offset_end);
1114
1115 // Update a region in the dense prefix. For each live object
1116 // in the region, update it's interior references. For each
1117 // dead object, fill it with deadwood. Dead space at the end
1118 // of a region range will be filled to the start of the next
1119 // live object regardless of the region_index_end. None of the
1120 // objects in the dense prefix move and dead space is dead
1121 // (holds only dead objects that don't need any processing), so
1122 // dead space can be filled in any order.
1123 static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
1124 SpaceId space_id,
1125 size_t region_index_start,
1126 size_t region_index_end);
1127
1128 // Return the address of the count + 1st live word in the range [beg, end).
1129 static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
1130
1131 // Return the address of the word to be copied to dest_addr, which must be
1132 // aligned to a region boundary.
1133 static HeapWord* first_src_addr(HeapWord* const dest_addr,
1134 SpaceId src_space_id,
1135 size_t src_region_idx);
1136
1137 // Determine the next source region, set closure.source() to the start of the
1138 // new region return the region index. Parameter end_addr is the address one
1139 // beyond the end of source range just processed. If necessary, switch to a
1140 // new source space and set src_space_id (in-out parameter) and src_space_top
1141 // (out parameter) accordingly.
1142 static size_t next_src_region(MoveAndUpdateClosure& closure,
1143 SpaceId& src_space_id,
1144 HeapWord*& src_space_top,
1145 HeapWord* end_addr);
1146
1147 // Decrement the destination count for each non-empty source region in the
1148 // range [beg_region, region(region_align_up(end_addr))). If the destination
1149 // count for a region goes to 0 and it needs to be filled, enqueue it.
1150 static void decrement_destination_counts(ParCompactionManager* cm,
1151 SpaceId src_space_id,
1152 size_t beg_region,
1153 HeapWord* end_addr);
1154
1155 // Fill a region, copying objects from one or more source regions.
1156 static void fill_region(ParCompactionManager* cm, size_t region_idx);
1157 static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
1158 fill_region(cm, region);
1159 }
1160
1161 // Update the deferred objects in the space.
1162 static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
1163
1164 static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
1165 static ParallelCompactData& summary_data() { return _summary_data; }
1166
1167 static inline void adjust_pointer(oop* p) { adjust_pointer(p, false); }
1168 static inline void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); }
1169
1170 // Reference Processing
1171 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
1172
1173 static STWGCTimer* gc_timer() { return &_gc_timer; }
1174
1175 // Return the SpaceId for the given address.
1176 static SpaceId space_id(HeapWord* addr);
1177
1178 // Time since last full gc (in milliseconds).
1179 static jlong millis_since_last_gc();
1180
1181 #ifdef VALIDATE_MARK_SWEEP
1182 static void track_adjusted_pointer(void* p, bool isroot);
1183 static void check_adjust_pointer(void* p);
1184 static void track_interior_pointers(oop obj);
1185 static void check_interior_pointers();
1186
1187 static void reset_live_oop_tracking(bool at_perm);
1188 static void register_live_oop(oop p, size_t size);
1189 static void validate_live_oop(oop p, size_t size);
1190 static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top);
1191 static void compaction_complete();
1192
1193 // Querying operation of RecordMarkSweepCompaction results.
1194 // Finds and prints the current base oop and offset for a word
1195 // within an oop that was live during the last GC. Helpful for
1196 // tracking down heap stomps.
1197 static void print_new_location_of_heap_address(HeapWord* q);
1198 #endif // #ifdef VALIDATE_MARK_SWEEP
1199
1200 // Call backs for class unloading
1201 // Update subklass/sibling/implementor links at end of marking.
1202 static void revisit_weak_klass_link(ParCompactionManager* cm, Klass* k);
1203
1204 // Clear unmarked oops in MDOs at the end of marking.
1205 static void revisit_mdo(ParCompactionManager* cm, DataLayout* p);
1206
1207 #ifndef PRODUCT
1208 // Debugging support.
1209 static const char* space_names[last_space_id];
1210 static void print_region_ranges();
1211 static void print_dense_prefix_stats(const char* const algorithm,
1212 const SpaceId id,
1213 const bool maximum_compaction,
1214 HeapWord* const addr);
1215 static void summary_phase_msg(SpaceId dst_space_id,
1216 HeapWord* dst_beg, HeapWord* dst_end,
1217 SpaceId src_space_id,
1218 HeapWord* src_beg, HeapWord* src_end);
1219 #endif // #ifndef PRODUCT
1220
1221 #ifdef ASSERT
1222 // Sanity check the new location of a word in the heap.
1223 static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr);
1224 // Verify that all the regions have been emptied.
1225 static void verify_complete(SpaceId space_id);
1226 #endif // #ifdef ASSERT
1227 };
1228
1229 inline bool PSParallelCompact::mark_obj(oop obj) {
1230 const int obj_size = obj->size();
1231 if (mark_bitmap()->mark_obj(obj, obj_size)) {
1232 _summary_data.add_obj(obj, obj_size);
1233 return true;
1234 } else {
1235 return false;
1236 }
1237 }
1238
1239 template <class T>
1240 inline void PSParallelCompact::follow_root(ParCompactionManager* cm, T* p) {
1241 assert(!Universe::heap()->is_in_reserved(p),
1242 "roots shouldn't be things within the heap");
1243 #ifdef VALIDATE_MARK_SWEEP
1244 if (ValidateMarkSweep) {
1245 guarantee(!_root_refs_stack->contains(p), "should only be in here once");
1246 _root_refs_stack->push(p);
1247 }
1248 #endif
1249 T heap_oop = oopDesc::load_heap_oop(p);
1250 if (!oopDesc::is_null(heap_oop)) {
1251 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1252 if (mark_bitmap()->is_unmarked(obj)) {
1253 if (mark_obj(obj)) {
1254 obj->follow_contents(cm);
1255 }
1256 }
1257 }
1258 cm->follow_marking_stacks();
1259 }
1260
1261 template <class T>
1262 inline void PSParallelCompact::mark_and_push(ParCompactionManager* cm, T* p) {
1263 T heap_oop = oopDesc::load_heap_oop(p);
1264 if (!oopDesc::is_null(heap_oop)) {
1265 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1266 if (mark_bitmap()->is_unmarked(obj) && mark_obj(obj)) {
1267 cm->push(obj);
1268 }
1269 }
1270 }
1271
1272 template <class T>
1273 inline void PSParallelCompact::adjust_pointer(T* p, bool isroot) {
1274 T heap_oop = oopDesc::load_heap_oop(p);
1275 if (!oopDesc::is_null(heap_oop)) {
1276 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1277 oop new_obj = (oop)summary_data().calc_new_pointer(obj);
1278 assert(new_obj != NULL || // is forwarding ptr?
1279 obj->is_shared(), // never forwarded?
1280 "should be forwarded");
1281 // Just always do the update unconditionally?
1282 if (new_obj != NULL) {
1283 assert(Universe::heap()->is_in_reserved(new_obj),
1284 "should be in object space");
1285 oopDesc::encode_store_heap_oop_not_null(p, new_obj);
1286 }
1287 }
1288 VALIDATE_MARK_SWEEP_ONLY(track_adjusted_pointer(p, isroot));
1289 }
1290
1291 template <class T>
1292 inline void PSParallelCompact::KeepAliveClosure::do_oop_work(T* p) {
1293 #ifdef VALIDATE_MARK_SWEEP
1294 if (ValidateMarkSweep) {
1295 if (!Universe::heap()->is_in_reserved(p)) {
1296 _root_refs_stack->push(p);
1297 } else {
1298 _other_refs_stack->push(p);
1299 }
1300 }
1301 #endif
1302 mark_and_push(_compaction_manager, p);
1303 }
1304
1305 inline bool PSParallelCompact::print_phases() {
1306 return _print_phases;
1307 }
1308
1309 inline double PSParallelCompact::normal_distribution(double density) {
1310 assert(_dwl_initialized, "uninitialized");
1311 const double squared_term = (density - _dwl_mean) / _dwl_std_dev;
1312 return _dwl_first_term * exp(-0.5 * squared_term * squared_term);
1313 }
1314
1315 inline bool
1316 PSParallelCompact::dead_space_crosses_boundary(const RegionData* region,
1317 idx_t bit)
1318 {
1319 assert(bit > 0, "cannot call this for the first bit/region");
1320 assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit),
1321 "sanity check");
1322
1323 // Dead space crosses the boundary if (1) a partial object does not extend
1324 // onto the region, (2) an object does not start at the beginning of the
1325 // region, and (3) an object does not end at the end of the prior region.
1326 return region->partial_obj_size() == 0 &&
1327 !_mark_bitmap.is_obj_beg(bit) &&
1328 !_mark_bitmap.is_obj_end(bit - 1);
1329 }
1330
1331 inline bool
1332 PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) {
1333 return p >= beg_addr && p < end_addr;
1334 }
1335
1336 inline bool
1337 PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) {
1338 return is_in((HeapWord*)p, beg_addr, end_addr);
1339 }
1340
1341 inline MutableSpace* PSParallelCompact::space(SpaceId id) {
1342 assert(id < last_space_id, "id out of range");
1343 return _space_info[id].space();
1344 }
1345
1346 inline HeapWord* PSParallelCompact::new_top(SpaceId id) {
1347 assert(id < last_space_id, "id out of range");
1348 return _space_info[id].new_top();
1349 }
1350
1351 inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) {
1352 assert(id < last_space_id, "id out of range");
1353 return _space_info[id].dense_prefix();
1354 }
1355
1356 inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) {
1357 assert(id < last_space_id, "id out of range");
1358 return _space_info[id].start_array();
1359 }
1360
1361 inline bool PSParallelCompact::should_update_klass(klassOop k) {
1362 return ((HeapWord*) k) >= dense_prefix(perm_space_id);
1363 }
1364
1365 #ifdef ASSERT
1366 inline void
1367 PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr)
1368 {
1369 assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr),
1370 "must move left or to a different space");
1371 assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr),
1372 "checking alignment");
1373 }
1374 #endif // ASSERT
1375
1376 class MoveAndUpdateClosure: public ParMarkBitMapClosure {
1377 public:
1378 inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
1379 ObjectStartArray* start_array,
1380 HeapWord* destination, size_t words);
1381
1382 // Accessors.
1383 HeapWord* destination() const { return _destination; }
1384
1385 // If the object will fit (size <= words_remaining()), copy it to the current
1386 // destination, update the interior oops and the start array and return either
1387 // full (if the closure is full) or incomplete. If the object will not fit,
1388 // return would_overflow.
1389 virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1390
1391 // Copy enough words to fill this closure, starting at source(). Interior
1392 // oops and the start array are not updated. Return full.
1393 IterationStatus copy_until_full();
1394
1395 // Copy enough words to fill this closure or to the end of an object,
1396 // whichever is smaller, starting at source(). Interior oops and the start
1397 // array are not updated.
1398 void copy_partial_obj();
1399
1400 protected:
1401 // Update variables to indicate that word_count words were processed.
1402 inline void update_state(size_t word_count);
1403
1404 protected:
1405 ObjectStartArray* const _start_array;
1406 HeapWord* _destination; // Next addr to be written.
1407 };
1408
1409 inline
1410 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
1411 ParCompactionManager* cm,
1412 ObjectStartArray* start_array,
1413 HeapWord* destination,
1414 size_t words) :
1415 ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)
1416 {
1417 _destination = destination;
1418 }
1419
1420 inline void MoveAndUpdateClosure::update_state(size_t words)
1421 {
1422 decrement_words_remaining(words);
1423 _source += words;
1424 _destination += words;
1425 }
1426
1427 class UpdateOnlyClosure: public ParMarkBitMapClosure {
1428 private:
1429 const PSParallelCompact::SpaceId _space_id;
1430 ObjectStartArray* const _start_array;
1431
1432 public:
1433 UpdateOnlyClosure(ParMarkBitMap* mbm,
1434 ParCompactionManager* cm,
1435 PSParallelCompact::SpaceId space_id);
1436
1437 // Update the object.
1438 virtual IterationStatus do_addr(HeapWord* addr, size_t words);
1439
1440 inline void do_addr(HeapWord* addr);
1441 };
1442
1443 inline void UpdateOnlyClosure::do_addr(HeapWord* addr)
1444 {
1445 _start_array->allocate_block(addr);
1446 oop(addr)->update_contents(compaction_manager());
1447 }
1448
1449 class FillClosure: public ParMarkBitMapClosure
1450 {
1451 public:
1452 FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
1453 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
1454 _start_array(PSParallelCompact::start_array(space_id))
1455 {
1456 assert(space_id == PSParallelCompact::perm_space_id ||
1457 space_id == PSParallelCompact::old_space_id,
1458 "cannot use FillClosure in the young gen");
1459 }
1460
1461 virtual IterationStatus do_addr(HeapWord* addr, size_t size) {
1462 CollectedHeap::fill_with_objects(addr, size);
1463 HeapWord* const end = addr + size;
1464 do {
1465 _start_array->allocate_block(addr);
1466 addr += oop(addr)->size();
1467 } while (addr < end);
1468 return ParMarkBitMap::incomplete;
1469 }
1470
1471 private:
1472 ObjectStartArray* const _start_array;
1473 };
1474
1475 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP