1 /*
2 * Copyright (c) 2005, 2015, 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 #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/mutableSpace.hpp"
33 #include "memory/sharedHeap.hpp"
34 #include "oops/oop.hpp"
35
36 class ParallelScavengeHeap;
37 class PSAdaptiveSizePolicy;
38 class PSYoungGen;
39 class PSOldGen;
40 class ParCompactionManager;
41 class ParallelTaskTerminator;
42 class PSParallelCompact;
43 class GCTaskManager;
44 class GCTaskQueue;
45 class PreGCValues;
46 class MoveAndUpdateClosure;
47 class RefProcTaskExecutor;
48 class ParallelOldTracer;
49 class STWGCTimer;
50
51 // The SplitInfo class holds the information needed to 'split' a source region
52 // so that the live data can be copied to two destination *spaces*. Normally,
53 // all the live data in a region is copied to a single destination space (e.g.,
54 // everything live in a region in eden is copied entirely into the old gen).
55 // However, when the heap is nearly full, all the live data in eden may not fit
56 // into the old gen. Copying only some of the regions from eden to old gen
57 // requires finding a region that does not contain a partial object (i.e., no
58 // live object crosses the region boundary) somewhere near the last object that
59 // does fit into the old gen. Since it's not always possible to find such a
60 // region, splitting is necessary for predictable behavior.
61 //
62 // A region is always split at the end of the partial object. This avoids
63 // additional tests when calculating the new location of a pointer, which is a
64 // very hot code path. The partial object and everything to its left will be
65 // copied to another space (call it dest_space_1). The live data to the right
66 // of the partial object will be copied either within the space itself, or to a
67 // different destination space (distinct from dest_space_1).
68 //
69 // Split points are identified during the summary phase, when region
70 // destinations are computed: data about the split, including the
71 // partial_object_size, is recorded in a SplitInfo record and the
72 // partial_object_size field in the summary data is set to zero. The zeroing is
73 // possible (and necessary) since the partial object will move to a different
74 // destination space than anything to its right, thus the partial object should
75 // not affect the locations of any objects to its right.
76 //
77 // The recorded data is used during the compaction phase, but only rarely: when
78 // the partial object on the split region will be copied across a destination
79 // region boundary. This test is made once each time a region is filled, and is
80 // a simple address comparison, so the overhead is negligible (see
81 // PSParallelCompact::first_src_addr()).
82 //
83 // Notes:
84 //
85 // Only regions with partial objects are split; a region without a partial
86 // object does not need any extra bookkeeping.
87 //
88 // At most one region is split per space, so the amount of data required is
89 // constant.
90 //
91 // A region is split only when the destination space would overflow. Once that
92 // happens, the destination space is abandoned and no other data (even from
93 // other source spaces) is targeted to that destination space. Abandoning the
94 // destination space may leave a somewhat large unused area at the end, if a
95 // large object caused the overflow.
96 //
97 // Future work:
98 //
99 // More bookkeeping would be required to continue to use the destination space.
100 // The most general solution would allow data from regions in two different
101 // source spaces to be "joined" in a single destination region. At the very
102 // least, additional code would be required in next_src_region() to detect the
103 // join and skip to an out-of-order source region. If the join region was also
104 // the last destination region to which a split region was copied (the most
105 // likely case), then additional work would be needed to get fill_region() to
106 // stop iteration and switch to a new source region at the right point. Basic
107 // idea would be to use a fake value for the top of the source space. It is
108 // doable, if a bit tricky.
109 //
110 // A simpler (but less general) solution would fill the remainder of the
111 // destination region with a dummy object and continue filling the next
112 // destination region.
113
114 class SplitInfo
115 {
116 public:
117 // Return true if this split info is valid (i.e., if a split has been
118 // recorded). The very first region cannot have a partial object and thus is
119 // never split, so 0 is the 'invalid' value.
120 bool is_valid() const { return _src_region_idx > 0; }
121
122 // Return true if this split holds data for the specified source region.
123 inline bool is_split(size_t source_region) const;
124
125 // The index of the split region, the size of the partial object on that
126 // region and the destination of the partial object.
127 size_t src_region_idx() const { return _src_region_idx; }
128 size_t partial_obj_size() const { return _partial_obj_size; }
129 HeapWord* destination() const { return _destination; }
130
131 // The destination count of the partial object referenced by this split
132 // (either 1 or 2). This must be added to the destination count of the
133 // remainder of the source region.
134 unsigned int destination_count() const { return _destination_count; }
135
136 // If a word within the partial object will be written to the first word of a
137 // destination region, this is the address of the destination region;
138 // otherwise this is NULL.
139 HeapWord* dest_region_addr() const { return _dest_region_addr; }
140
141 // If a word within the partial object will be written to the first word of a
142 // destination region, this is the address of that word within the partial
143 // object; otherwise this is NULL.
144 HeapWord* first_src_addr() const { return _first_src_addr; }
145
146 // Record the data necessary to split the region src_region_idx.
147 void record(size_t src_region_idx, size_t partial_obj_size,
148 HeapWord* destination);
149
150 void clear();
151
152 DEBUG_ONLY(void verify_clear();)
153
154 private:
155 size_t _src_region_idx;
156 size_t _partial_obj_size;
157 HeapWord* _destination;
158 unsigned int _destination_count;
159 HeapWord* _dest_region_addr;
160 HeapWord* _first_src_addr;
161 };
162
163 inline bool SplitInfo::is_split(size_t region_idx) const
164 {
165 return _src_region_idx == region_idx && is_valid();
166 }
167
168 class SpaceInfo
169 {
170 public:
171 MutableSpace* space() const { return _space; }
172
173 // Where the free space will start after the collection. Valid only after the
174 // summary phase completes.
175 HeapWord* new_top() const { return _new_top; }
176
177 // Allows new_top to be set.
178 HeapWord** new_top_addr() { return &_new_top; }
179
180 // Where the smallest allowable dense prefix ends (used only for perm gen).
181 HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
182
183 // Where the dense prefix ends, or the compacted region begins.
184 HeapWord* dense_prefix() const { return _dense_prefix; }
185
186 // The start array for the (generation containing the) space, or NULL if there
187 // is no start array.
188 ObjectStartArray* start_array() const { return _start_array; }
189
190 SplitInfo& split_info() { return _split_info; }
191
192 void set_space(MutableSpace* s) { _space = s; }
193 void set_new_top(HeapWord* addr) { _new_top = addr; }
194 void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
195 void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; }
196 void set_start_array(ObjectStartArray* s) { _start_array = s; }
197
198 void publish_new_top() const { _space->set_top(_new_top); }
199
200 private:
201 MutableSpace* _space;
202 HeapWord* _new_top;
203 HeapWord* _min_dense_prefix;
204 HeapWord* _dense_prefix;
205 ObjectStartArray* _start_array;
206 SplitInfo _split_info;
207 };
208
209 class ParallelCompactData
210 {
211 public:
212 // Sizes are in HeapWords, unless indicated otherwise.
213 static const size_t Log2RegionSize;
214 static const size_t RegionSize;
215 static const size_t RegionSizeBytes;
216
217 // Mask for the bits in a size_t to get an offset within a region.
218 static const size_t RegionSizeOffsetMask;
219 // Mask for the bits in a pointer to get an offset within a region.
220 static const size_t RegionAddrOffsetMask;
221 // Mask for the bits in a pointer to get the address of the start of a region.
222 static const size_t RegionAddrMask;
223
224 static const size_t Log2BlockSize;
225 static const size_t BlockSize;
226 static const size_t BlockSizeBytes;
227
228 static const size_t BlockSizeOffsetMask;
229 static const size_t BlockAddrOffsetMask;
230 static const size_t BlockAddrMask;
231
232 static const size_t BlocksPerRegion;
233 static const size_t Log2BlocksPerRegion;
234
235 class RegionData
236 {
237 public:
238 // Destination address of the region.
239 HeapWord* destination() const { return _destination; }
240
241 // The first region containing data destined for this region.
242 size_t source_region() const { return _source_region; }
243
244 // The object (if any) starting in this region and ending in a different
245 // region that could not be updated during the main (parallel) compaction
246 // phase. This is different from _partial_obj_addr, which is an object that
247 // extends onto a source region. However, the two uses do not overlap in
248 // time, so the same field is used to save space.
249 HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
250
251 // The starting address of the partial object extending onto the region.
252 HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
253
254 // Size of the partial object extending onto the region (words).
255 size_t partial_obj_size() const { return _partial_obj_size; }
256
257 // Size of live data that lies within this region due to objects that start
258 // in this region (words). This does not include the partial object
259 // extending onto the region (if any), or the part of an object that extends
260 // onto the next region (if any).
261 size_t live_obj_size() const { return _dc_and_los & los_mask; }
262
263 // Total live data that lies within the region (words).
264 size_t data_size() const { return partial_obj_size() + live_obj_size(); }
265
266 // The destination_count is the number of other regions to which data from
267 // this region will be copied. At the end of the summary phase, the valid
268 // values of destination_count are
269 //
270 // 0 - data from the region will be compacted completely into itself, or the
271 // region is empty. The region can be claimed and then filled.
272 // 1 - data from the region will be compacted into 1 other region; some
273 // data from the region may also be compacted into the region itself.
274 // 2 - data from the region will be copied to 2 other regions.
275 //
276 // During compaction as regions are emptied, the destination_count is
277 // decremented (atomically) and when it reaches 0, it can be claimed and
278 // then filled.
279 //
280 // A region is claimed for processing by atomically changing the
281 // destination_count to the claimed value (dc_claimed). After a region has
282 // been filled, the destination_count should be set to the completed value
283 // (dc_completed).
284 inline uint destination_count() const;
285 inline uint destination_count_raw() const;
286
287 // Whether the block table for this region has been filled.
288 inline bool blocks_filled() const;
289
290 // Number of times the block table was filled.
291 DEBUG_ONLY(inline size_t blocks_filled_count() const;)
292
293 // The location of the java heap data that corresponds to this region.
294 inline HeapWord* data_location() const;
295
296 // The highest address referenced by objects in this region.
297 inline HeapWord* highest_ref() const;
298
299 // Whether this region is available to be claimed, has been claimed, or has
300 // been completed.
301 //
302 // Minor subtlety: claimed() returns true if the region is marked
303 // completed(), which is desirable since a region must be claimed before it
304 // can be completed.
305 bool available() const { return _dc_and_los < dc_one; }
306 bool claimed() const { return _dc_and_los >= dc_claimed; }
307 bool completed() const { return _dc_and_los >= dc_completed; }
308
309 // These are not atomic.
310 void set_destination(HeapWord* addr) { _destination = addr; }
311 void set_source_region(size_t region) { _source_region = region; }
312 void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
313 void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
314 void set_partial_obj_size(size_t words) {
315 _partial_obj_size = (region_sz_t) words;
316 }
317 inline void set_blocks_filled();
318
319 inline void set_destination_count(uint count);
320 inline void set_live_obj_size(size_t words);
321 inline void set_data_location(HeapWord* addr);
322 inline void set_completed();
323 inline bool claim_unsafe();
324
325 // These are atomic.
326 inline void add_live_obj(size_t words);
327 inline void set_highest_ref(HeapWord* addr);
328 inline void decrement_destination_count();
329 inline bool claim();
330
331 private:
332 // The type used to represent object sizes within a region.
333 typedef uint region_sz_t;
334
335 // Constants for manipulating the _dc_and_los field, which holds both the
336 // destination count and live obj size. The live obj size lives at the
337 // least significant end so no masking is necessary when adding.
338 static const region_sz_t dc_shift; // Shift amount.
339 static const region_sz_t dc_mask; // Mask for destination count.
340 static const region_sz_t dc_one; // 1, shifted appropriately.
341 static const region_sz_t dc_claimed; // Region has been claimed.
342 static const region_sz_t dc_completed; // Region has been completed.
343 static const region_sz_t los_mask; // Mask for live obj size.
344
345 HeapWord* _destination;
346 size_t _source_region;
347 HeapWord* _partial_obj_addr;
348 region_sz_t _partial_obj_size;
349 region_sz_t volatile _dc_and_los;
350 bool _blocks_filled;
351
352 #ifdef ASSERT
353 size_t _blocks_filled_count; // Number of block table fills.
354
355 // These enable optimizations that are only partially implemented. Use
356 // debug builds to prevent the code fragments from breaking.
357 HeapWord* _data_location;
358 HeapWord* _highest_ref;
359 #endif // #ifdef ASSERT
360
361 #ifdef ASSERT
362 public:
363 uint _pushed; // 0 until region is pushed onto a stack
364 private:
365 #endif
366 };
367
368 // "Blocks" allow shorter sections of the bitmap to be searched. Each Block
369 // holds an offset, which is the amount of live data in the Region to the left
370 // of the first live object that starts in the Block.
371 class BlockData
372 {
373 public:
374 typedef unsigned short int blk_ofs_t;
375
376 blk_ofs_t offset() const { return _offset; }
377 void set_offset(size_t val) { _offset = (blk_ofs_t)val; }
378
379 private:
380 blk_ofs_t _offset;
381 };
382
383 public:
384 ParallelCompactData();
385 bool initialize(MemRegion covered_region);
386
387 size_t region_count() const { return _region_count; }
388 size_t reserved_byte_size() const { return _reserved_byte_size; }
389
390 // Convert region indices to/from RegionData pointers.
391 inline RegionData* region(size_t region_idx) const;
392 inline size_t region(const RegionData* const region_ptr) const;
393
394 size_t block_count() const { return _block_count; }
395 inline BlockData* block(size_t block_idx) const;
396 inline size_t block(const BlockData* block_ptr) const;
397
398 void add_obj(HeapWord* addr, size_t len);
399 void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
400
401 // Fill in the regions covering [beg, end) so that no data moves; i.e., the
402 // destination of region n is simply the start of region n. The argument beg
403 // must be region-aligned; end need not be.
404 void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
405
406 HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info,
407 HeapWord* destination, HeapWord* target_end,
408 HeapWord** target_next);
409 bool summarize(SplitInfo& split_info,
410 HeapWord* source_beg, HeapWord* source_end,
411 HeapWord** source_next,
412 HeapWord* target_beg, HeapWord* target_end,
413 HeapWord** target_next);
414
415 void clear();
416 void clear_range(size_t beg_region, size_t end_region);
417 void clear_range(HeapWord* beg, HeapWord* end) {
418 clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
419 }
420
421 // Return the number of words between addr and the start of the region
422 // containing addr.
423 inline size_t region_offset(const HeapWord* addr) const;
424
425 // Convert addresses to/from a region index or region pointer.
426 inline size_t addr_to_region_idx(const HeapWord* addr) const;
427 inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
428 inline HeapWord* region_to_addr(size_t region) const;
429 inline HeapWord* region_to_addr(size_t region, size_t offset) const;
430 inline HeapWord* region_to_addr(const RegionData* region) const;
431
432 inline HeapWord* region_align_down(HeapWord* addr) const;
433 inline HeapWord* region_align_up(HeapWord* addr) const;
434 inline bool is_region_aligned(HeapWord* addr) const;
435
436 // Analogous to region_offset() for blocks.
437 size_t block_offset(const HeapWord* addr) const;
438 size_t addr_to_block_idx(const HeapWord* addr) const;
439 size_t addr_to_block_idx(const oop obj) const {
440 return addr_to_block_idx((HeapWord*) obj);
441 }
442 inline BlockData* addr_to_block_ptr(const HeapWord* addr) const;
443 inline HeapWord* block_to_addr(size_t block) const;
444 inline size_t region_to_block_idx(size_t region) const;
445
446 inline HeapWord* block_align_down(HeapWord* addr) const;
447 inline HeapWord* block_align_up(HeapWord* addr) const;
448 inline bool is_block_aligned(HeapWord* addr) const;
449
450 // Return the address one past the end of the partial object.
451 HeapWord* partial_obj_end(size_t region_idx) const;
452
453 // Return the location of the object after compaction.
454 HeapWord* calc_new_pointer(HeapWord* addr);
455
456 HeapWord* calc_new_pointer(oop p) {
457 return calc_new_pointer((HeapWord*) p);
458 }
459
460 #ifdef ASSERT
461 void verify_clear(const PSVirtualSpace* vspace);
462 void verify_clear();
463 #endif // #ifdef ASSERT
464
465 private:
466 bool initialize_block_data();
467 bool initialize_region_data(size_t region_size);
468 PSVirtualSpace* create_vspace(size_t count, size_t element_size);
469
470 private:
471 HeapWord* _region_start;
472 #ifdef ASSERT
473 HeapWord* _region_end;
474 #endif // #ifdef ASSERT
475
476 PSVirtualSpace* _region_vspace;
477 size_t _reserved_byte_size;
478 RegionData* _region_data;
479 size_t _region_count;
480
481 PSVirtualSpace* _block_vspace;
482 BlockData* _block_data;
483 size_t _block_count;
484 };
485
486 inline uint
487 ParallelCompactData::RegionData::destination_count_raw() const
488 {
489 return _dc_and_los & dc_mask;
490 }
491
492 inline uint
493 ParallelCompactData::RegionData::destination_count() const
494 {
495 return destination_count_raw() >> dc_shift;
496 }
497
498 inline bool
499 ParallelCompactData::RegionData::blocks_filled() const
500 {
501 return _blocks_filled;
502 }
503
504 #ifdef ASSERT
505 inline size_t
506 ParallelCompactData::RegionData::blocks_filled_count() const
507 {
508 return _blocks_filled_count;
509 }
510 #endif // #ifdef ASSERT
511
512 inline void
513 ParallelCompactData::RegionData::set_blocks_filled()
514 {
515 _blocks_filled = true;
516 // Debug builds count the number of times the table was filled.
517 DEBUG_ONLY(Atomic::inc_ptr(&_blocks_filled_count));
518 }
519
520 inline void
521 ParallelCompactData::RegionData::set_destination_count(uint count)
522 {
523 assert(count <= (dc_completed >> dc_shift), "count too large");
524 const region_sz_t live_sz = (region_sz_t) live_obj_size();
525 _dc_and_los = (count << dc_shift) | live_sz;
526 }
527
528 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
529 {
530 assert(words <= los_mask, "would overflow");
531 _dc_and_los = destination_count_raw() | (region_sz_t)words;
532 }
533
534 inline void ParallelCompactData::RegionData::decrement_destination_count()
535 {
536 assert(_dc_and_los < dc_claimed, "already claimed");
537 assert(_dc_and_los >= dc_one, "count would go negative");
538 Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);
539 }
540
541 inline HeapWord* ParallelCompactData::RegionData::data_location() const
542 {
543 DEBUG_ONLY(return _data_location;)
544 NOT_DEBUG(return NULL;)
545 }
546
547 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
548 {
549 DEBUG_ONLY(return _highest_ref;)
550 NOT_DEBUG(return NULL;)
551 }
552
553 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
554 {
555 DEBUG_ONLY(_data_location = addr;)
556 }
557
558 inline void ParallelCompactData::RegionData::set_completed()
559 {
560 assert(claimed(), "must be claimed first");
561 _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
562 }
563
564 // MT-unsafe claiming of a region. Should only be used during single threaded
565 // execution.
566 inline bool ParallelCompactData::RegionData::claim_unsafe()
567 {
568 if (available()) {
569 _dc_and_los |= dc_claimed;
570 return true;
571 }
572 return false;
573 }
574
575 inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
576 {
577 assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
578 Atomic::add((int) words, (volatile int*) &_dc_and_los);
579 }
580
581 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
582 {
583 #ifdef ASSERT
584 HeapWord* tmp = _highest_ref;
585 while (addr > tmp) {
586 tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp);
587 }
588 #endif // #ifdef ASSERT
589 }
590
591 inline bool ParallelCompactData::RegionData::claim()
592 {
593 const int los = (int) live_obj_size();
594 const int old = Atomic::cmpxchg(dc_claimed | los,
595 (volatile int*) &_dc_and_los, los);
596 return old == los;
597 }
598
599 inline ParallelCompactData::RegionData*
600 ParallelCompactData::region(size_t region_idx) const
601 {
602 assert(region_idx <= region_count(), "bad arg");
603 return _region_data + region_idx;
604 }
605
606 inline size_t
607 ParallelCompactData::region(const RegionData* const region_ptr) const
608 {
609 assert(region_ptr >= _region_data, "bad arg");
610 assert(region_ptr <= _region_data + region_count(), "bad arg");
611 return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
612 }
613
614 inline ParallelCompactData::BlockData*
615 ParallelCompactData::block(size_t n) const {
616 assert(n < block_count(), "bad arg");
617 return _block_data + n;
618 }
619
620 inline size_t
621 ParallelCompactData::region_offset(const HeapWord* addr) const
622 {
623 assert(addr >= _region_start, "bad addr");
624 assert(addr <= _region_end, "bad addr");
625 return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
626 }
627
628 inline size_t
629 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
630 {
631 assert(addr >= _region_start, "bad addr");
632 assert(addr <= _region_end, "bad addr");
633 return pointer_delta(addr, _region_start) >> Log2RegionSize;
634 }
635
636 inline ParallelCompactData::RegionData*
637 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
638 {
639 return region(addr_to_region_idx(addr));
640 }
641
642 inline HeapWord*
643 ParallelCompactData::region_to_addr(size_t region) const
644 {
645 assert(region <= _region_count, "region out of range");
646 return _region_start + (region << Log2RegionSize);
647 }
648
649 inline HeapWord*
650 ParallelCompactData::region_to_addr(const RegionData* region) const
651 {
652 return region_to_addr(pointer_delta(region, _region_data,
653 sizeof(RegionData)));
654 }
655
656 inline HeapWord*
657 ParallelCompactData::region_to_addr(size_t region, size_t offset) const
658 {
659 assert(region <= _region_count, "region out of range");
660 assert(offset < RegionSize, "offset too big"); // This may be too strict.
661 return region_to_addr(region) + offset;
662 }
663
664 inline HeapWord*
665 ParallelCompactData::region_align_down(HeapWord* addr) const
666 {
667 assert(addr >= _region_start, "bad addr");
668 assert(addr < _region_end + RegionSize, "bad addr");
669 return (HeapWord*)(size_t(addr) & RegionAddrMask);
670 }
671
672 inline HeapWord*
673 ParallelCompactData::region_align_up(HeapWord* addr) const
674 {
675 assert(addr >= _region_start, "bad addr");
676 assert(addr <= _region_end, "bad addr");
677 return region_align_down(addr + RegionSizeOffsetMask);
678 }
679
680 inline bool
681 ParallelCompactData::is_region_aligned(HeapWord* addr) const
682 {
683 return region_offset(addr) == 0;
684 }
685
686 inline size_t
687 ParallelCompactData::block_offset(const HeapWord* addr) const
688 {
689 assert(addr >= _region_start, "bad addr");
690 assert(addr <= _region_end, "bad addr");
691 return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize;
692 }
693
694 inline size_t
695 ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const
696 {
697 assert(addr >= _region_start, "bad addr");
698 assert(addr <= _region_end, "bad addr");
699 return pointer_delta(addr, _region_start) >> Log2BlockSize;
700 }
701
702 inline ParallelCompactData::BlockData*
703 ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const
704 {
705 return block(addr_to_block_idx(addr));
706 }
707
708 inline HeapWord*
709 ParallelCompactData::block_to_addr(size_t block) const
710 {
711 assert(block < _block_count, "block out of range");
712 return _region_start + (block << Log2BlockSize);
713 }
714
715 inline size_t
716 ParallelCompactData::region_to_block_idx(size_t region) const
717 {
718 return region << Log2BlocksPerRegion;
719 }
720
721 inline HeapWord*
722 ParallelCompactData::block_align_down(HeapWord* addr) const
723 {
724 assert(addr >= _region_start, "bad addr");
725 assert(addr < _region_end + RegionSize, "bad addr");
726 return (HeapWord*)(size_t(addr) & BlockAddrMask);
727 }
728
729 inline HeapWord*
730 ParallelCompactData::block_align_up(HeapWord* addr) const
731 {
732 assert(addr >= _region_start, "bad addr");
733 assert(addr <= _region_end, "bad addr");
734 return block_align_down(addr + BlockSizeOffsetMask);
735 }
736
737 inline bool
738 ParallelCompactData::is_block_aligned(HeapWord* addr) const
739 {
740 return block_offset(addr) == 0;
741 }
742
743 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
744 // do_addr() method.
745 //
746 // The closure is initialized with the number of heap words to process
747 // (words_remaining()), and becomes 'full' when it reaches 0. The do_addr()
748 // methods in subclasses should update the total as words are processed. Since
749 // only one subclass actually uses this mechanism to terminate iteration, the
750 // default initial value is > 0. The implementation is here and not in the
751 // single subclass that uses it to avoid making is_full() virtual, and thus
752 // adding a virtual call per live object.
753
754 class ParMarkBitMapClosure: public StackObj {
755 public:
756 typedef ParMarkBitMap::idx_t idx_t;
757 typedef ParMarkBitMap::IterationStatus IterationStatus;
758
759 public:
760 inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
761 size_t words = max_uintx);
762
763 inline ParCompactionManager* compaction_manager() const;
764 inline ParMarkBitMap* bitmap() const;
765 inline size_t words_remaining() const;
766 inline bool is_full() const;
767 inline HeapWord* source() const;
768
769 inline void set_source(HeapWord* addr);
770
771 virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
772
773 protected:
774 inline void decrement_words_remaining(size_t words);
775
776 private:
777 ParMarkBitMap* const _bitmap;
778 ParCompactionManager* const _compaction_manager;
779 DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger.
780 size_t _words_remaining; // Words left to copy.
781
782 protected:
783 HeapWord* _source; // Next addr that would be read.
784 };
785
786 inline
787 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
788 ParCompactionManager* cm,
789 size_t words):
790 _bitmap(bitmap), _compaction_manager(cm)
791 #ifdef ASSERT
792 , _initial_words_remaining(words)
793 #endif
794 {
795 _words_remaining = words;
796 _source = NULL;
797 }
798
799 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
800 return _compaction_manager;
801 }
802
803 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
804 return _bitmap;
805 }
806
807 inline size_t ParMarkBitMapClosure::words_remaining() const {
808 return _words_remaining;
809 }
810
811 inline bool ParMarkBitMapClosure::is_full() const {
812 return words_remaining() == 0;
813 }
814
815 inline HeapWord* ParMarkBitMapClosure::source() const {
816 return _source;
817 }
818
819 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
820 _source = addr;
821 }
822
823 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
824 assert(_words_remaining >= words, "processed too many words");
825 _words_remaining -= words;
826 }
827
828 // The UseParallelOldGC collector is a stop-the-world garbage collector that
829 // does parts of the collection using parallel threads. The collection includes
830 // the tenured generation and the young generation. The permanent generation is
831 // collected at the same time as the other two generations but the permanent
832 // generation is collect by a single GC thread. The permanent generation is
833 // collected serially because of the requirement that during the processing of a
834 // klass AAA, any objects reference by AAA must already have been processed.
835 // This requirement is enforced by a left (lower address) to right (higher
836 // address) sliding compaction.
837 //
838 // There are four phases of the collection.
839 //
840 // - marking phase
841 // - summary phase
842 // - compacting phase
843 // - clean up phase
844 //
845 // Roughly speaking these phases correspond, respectively, to
846 // - mark all the live objects
847 // - calculate the destination of each object at the end of the collection
848 // - move the objects to their destination
849 // - update some references and reinitialize some variables
850 //
851 // These three phases are invoked in PSParallelCompact::invoke_no_policy(). The
852 // marking phase is implemented in PSParallelCompact::marking_phase() and does a
853 // complete marking of the heap. The summary phase is implemented in
854 // PSParallelCompact::summary_phase(). The move and update phase is implemented
855 // in PSParallelCompact::compact().
856 //
857 // A space that is being collected is divided into regions and with each region
858 // is associated an object of type ParallelCompactData. Each region is of a
859 // fixed size and typically will contain more than 1 object and may have parts
860 // of objects at the front and back of the region.
861 //
862 // region -----+---------------------+----------
863 // objects covered [ AAA )[ BBB )[ CCC )[ DDD )
864 //
865 // The marking phase does a complete marking of all live objects in the heap.
866 // The marking also compiles the size of the data for all live objects covered
867 // by the region. This size includes the part of any live object spanning onto
868 // the region (part of AAA if it is live) from the front, all live objects
869 // contained in the region (BBB and/or CCC if they are live), and the part of
870 // any live objects covered by the region that extends off the region (part of
871 // DDD if it is live). The marking phase uses multiple GC threads and marking
872 // is done in a bit array of type ParMarkBitMap. The marking of the bit map is
873 // done atomically as is the accumulation of the size of the live objects
874 // covered by a region.
875 //
876 // The summary phase calculates the total live data to the left of each region
877 // XXX. Based on that total and the bottom of the space, it can calculate the
878 // starting location of the live data in XXX. The summary phase calculates for
879 // each region XXX quantities such as
880 //
881 // - the amount of live data at the beginning of a region from an object
882 // entering the region.
883 // - the location of the first live data on the region
884 // - a count of the number of regions receiving live data from XXX.
885 //
886 // See ParallelCompactData for precise details. The summary phase also
887 // calculates the dense prefix for the compaction. The dense prefix is a
888 // portion at the beginning of the space that is not moved. The objects in the
889 // dense prefix do need to have their object references updated. See method
890 // summarize_dense_prefix().
891 //
892 // The summary phase is done using 1 GC thread.
893 //
894 // The compaction phase moves objects to their new location and updates all
895 // references in the object.
896 //
897 // A current exception is that objects that cross a region boundary are moved
898 // but do not have their references updated. References are not updated because
899 // it cannot easily be determined if the klass pointer KKK for the object AAA
900 // has been updated. KKK likely resides in a region to the left of the region
901 // containing AAA. These AAA's have there references updated at the end in a
902 // clean up phase. See the method PSParallelCompact::update_deferred_objects().
903 // An alternate strategy is being investigated for this deferral of updating.
904 //
905 // Compaction is done on a region basis. A region that is ready to be filled is
906 // put on a ready list and GC threads take region off the list and fill them. A
907 // region is ready to be filled if it empty of live objects. Such a region may
908 // have been initially empty (only contained dead objects) or may have had all
909 // its live objects copied out already. A region that compacts into itself is
910 // also ready for filling. The ready list is initially filled with empty
911 // regions and regions compacting into themselves. There is always at least 1
912 // region that can be put on the ready list. The regions are atomically added
913 // and removed from the ready list.
914
915 class PSParallelCompact : AllStatic {
916 public:
917 // Convenient access to type names.
918 typedef ParMarkBitMap::idx_t idx_t;
919 typedef ParallelCompactData::RegionData RegionData;
920 typedef ParallelCompactData::BlockData BlockData;
921
922 typedef enum {
923 old_space_id, eden_space_id,
924 from_space_id, to_space_id, last_space_id
925 } SpaceId;
926
927 public:
928 // Inline closure decls
929 //
930 class IsAliveClosure: public BoolObjectClosure {
931 public:
932 virtual bool do_object_b(oop p);
933 };
934
935 class KeepAliveClosure: public OopClosure {
936 private:
937 ParCompactionManager* _compaction_manager;
938 protected:
939 template <class T> inline void do_oop_work(T* p);
940 public:
941 KeepAliveClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
942 virtual void do_oop(oop* p);
943 virtual void do_oop(narrowOop* p);
944 };
945
946 class FollowStackClosure: public VoidClosure {
947 private:
948 ParCompactionManager* _compaction_manager;
949 public:
950 FollowStackClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
951 virtual void do_void();
952 };
953
954 class AdjustPointerClosure: public OopClosure {
955 public:
956 virtual void do_oop(oop* p);
957 virtual void do_oop(narrowOop* p);
958 // do not walk from thread stacks to the code cache on this phase
959 virtual void do_code_blob(CodeBlob* cb) const { }
960 };
961
962 class AdjustKlassClosure : public KlassClosure {
963 public:
964 void do_klass(Klass* klass);
965 };
966
967 friend class KeepAliveClosure;
968 friend class FollowStackClosure;
969 friend class AdjustPointerClosure;
970 friend class AdjustKlassClosure;
971 friend class FollowKlassClosure;
972 friend class InstanceClassLoaderKlass;
973 friend class RefProcTaskProxy;
974
975 private:
976 static STWGCTimer _gc_timer;
977 static ParallelOldTracer _gc_tracer;
978 static elapsedTimer _accumulated_time;
979 static unsigned int _total_invocations;
980 static unsigned int _maximum_compaction_gc_num;
981 static jlong _time_of_last_gc; // ms
982 static CollectorCounters* _counters;
983 static ParMarkBitMap _mark_bitmap;
984 static ParallelCompactData _summary_data;
985 static IsAliveClosure _is_alive_closure;
986 static SpaceInfo _space_info[last_space_id];
987 static bool _print_phases;
988 static AdjustPointerClosure _adjust_pointer_closure;
989 static AdjustKlassClosure _adjust_klass_closure;
990
991 // Reference processing (used in ...follow_contents)
992 static ReferenceProcessor* _ref_processor;
993
994 // Updated location of intArrayKlassObj.
995 static Klass* _updated_int_array_klass_obj;
996
997 // Values computed at initialization and used by dead_wood_limiter().
998 static double _dwl_mean;
999 static double _dwl_std_dev;
1000 static double _dwl_first_term;
1001 static double _dwl_adjustment;
1002 #ifdef ASSERT
1003 static bool _dwl_initialized;
1004 #endif // #ifdef ASSERT
1005
1006
1007 public:
1008 static ParallelOldTracer* gc_tracer() { return &_gc_tracer; }
1009
1010 private:
1011
1012 static void initialize_space_info();
1013
1014 // Return true if details about individual phases should be printed.
1015 static inline bool print_phases();
1016
1017 // Clear the marking bitmap and summary data that cover the specified space.
1018 static void clear_data_covering_space(SpaceId id);
1019
1020 static void pre_compact(PreGCValues* pre_gc_values);
1021 static void post_compact();
1022
1023 // Mark live objects
1024 static void marking_phase(ParCompactionManager* cm,
1025 bool maximum_heap_compaction,
1026 ParallelOldTracer *gc_tracer);
1027
1028 // Compute the dense prefix for the designated space. This is an experimental
1029 // implementation currently not used in production.
1030 static HeapWord* compute_dense_prefix_via_density(const SpaceId id,
1031 bool maximum_compaction);
1032
1033 // Methods used to compute the dense prefix.
1034
1035 // Compute the value of the normal distribution at x = density. The mean and
1036 // standard deviation are values saved by initialize_dead_wood_limiter().
1037 static inline double normal_distribution(double density);
1038
1039 // Initialize the static vars used by dead_wood_limiter().
1040 static void initialize_dead_wood_limiter();
1041
1042 // Return the percentage of space that can be treated as "dead wood" (i.e.,
1043 // not reclaimed).
1044 static double dead_wood_limiter(double density, size_t min_percent);
1045
1046 // Find the first (left-most) region in the range [beg, end) that has at least
1047 // dead_words of dead space to the left. The argument beg must be the first
1048 // region in the space that is not completely live.
1049 static RegionData* dead_wood_limit_region(const RegionData* beg,
1050 const RegionData* end,
1051 size_t dead_words);
1052
1053 // Return a pointer to the first region in the range [beg, end) that is not
1054 // completely full.
1055 static RegionData* first_dead_space_region(const RegionData* beg,
1056 const RegionData* end);
1057
1058 // Return a value indicating the benefit or 'yield' if the compacted region
1059 // were to start (or equivalently if the dense prefix were to end) at the
1060 // candidate region. Higher values are better.
1061 //
1062 // The value is based on the amount of space reclaimed vs. the costs of (a)
1063 // updating references in the dense prefix plus (b) copying objects and
1064 // updating references in the compacted region.
1065 static inline double reclaimed_ratio(const RegionData* const candidate,
1066 HeapWord* const bottom,
1067 HeapWord* const top,
1068 HeapWord* const new_top);
1069
1070 // Compute the dense prefix for the designated space.
1071 static HeapWord* compute_dense_prefix(const SpaceId id,
1072 bool maximum_compaction);
1073
1074 // Return true if dead space crosses onto the specified Region; bit must be
1075 // the bit index corresponding to the first word of the Region.
1076 static inline bool dead_space_crosses_boundary(const RegionData* region,
1077 idx_t bit);
1078
1079 // Summary phase utility routine to fill dead space (if any) at the dense
1080 // prefix boundary. Should only be called if the the dense prefix is
1081 // non-empty.
1082 static void fill_dense_prefix_end(SpaceId id);
1083
1084 // Clear the summary data source_region field for the specified addresses.
1085 static void clear_source_region(HeapWord* beg_addr, HeapWord* end_addr);
1086
1087 #ifndef PRODUCT
1088 // Routines to provoke splitting a young gen space (ParallelOldGCSplitALot).
1089
1090 // Fill the region [start, start + words) with live object(s). Only usable
1091 // for the old and permanent generations.
1092 static void fill_with_live_objects(SpaceId id, HeapWord* const start,
1093 size_t words);
1094 // Include the new objects in the summary data.
1095 static void summarize_new_objects(SpaceId id, HeapWord* start);
1096
1097 // Add live objects to a survivor space since it's rare that both survivors
1098 // are non-empty.
1099 static void provoke_split_fill_survivor(SpaceId id);
1100
1101 // Add live objects and/or choose the dense prefix to provoke splitting.
1102 static void provoke_split(bool & maximum_compaction);
1103 #endif
1104
1105 static void summarize_spaces_quick();
1106 static void summarize_space(SpaceId id, bool maximum_compaction);
1107 static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);
1108
1109 // Adjust addresses in roots. Does not adjust addresses in heap.
1110 static void adjust_roots();
1111
1112 DEBUG_ONLY(static void write_block_fill_histogram(outputStream* const out);)
1113
1114 // Move objects to new locations.
1115 static void compact_perm(ParCompactionManager* cm);
1116 static void compact();
1117
1118 // Add available regions to the stack and draining tasks to the task queue.
1119 static void enqueue_region_draining_tasks(GCTaskQueue* q,
1120 uint parallel_gc_threads);
1121
1122 // Add dense prefix update tasks to the task queue.
1123 static void enqueue_dense_prefix_tasks(GCTaskQueue* q,
1124 uint parallel_gc_threads);
1125
1126 // Add region stealing tasks to the task queue.
1127 static void enqueue_region_stealing_tasks(
1128 GCTaskQueue* q,
1129 ParallelTaskTerminator* terminator_ptr,
1130 uint parallel_gc_threads);
1131
1132 // If objects are left in eden after a collection, try to move the boundary
1133 // and absorb them into the old gen. Returns true if eden was emptied.
1134 static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1135 PSYoungGen* young_gen,
1136 PSOldGen* old_gen);
1137
1138 // Reset time since last full gc
1139 static void reset_millis_since_last_gc();
1140
1141 public:
1142 class MarkAndPushClosure: public OopClosure {
1143 private:
1144 ParCompactionManager* _compaction_manager;
1145 public:
1146 MarkAndPushClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
1147 virtual void do_oop(oop* p);
1148 virtual void do_oop(narrowOop* p);
1149 };
1150
1151 // The one and only place to start following the classes.
1152 // Should only be applied to the ClassLoaderData klasses list.
1153 class FollowKlassClosure : public KlassClosure {
1154 private:
1155 MarkAndPushClosure* _mark_and_push_closure;
1156 public:
1157 FollowKlassClosure(MarkAndPushClosure* mark_and_push_closure) :
1158 _mark_and_push_closure(mark_and_push_closure) { }
1159 void do_klass(Klass* klass);
1160 };
1161
1162 PSParallelCompact();
1163
1164 // Convenient accessor for Universe::heap().
1165 static ParallelScavengeHeap* gc_heap() {
1166 return (ParallelScavengeHeap*)Universe::heap();
1167 }
1168
1169 static void invoke(bool maximum_heap_compaction);
1170 static bool invoke_no_policy(bool maximum_heap_compaction);
1171
1172 static void post_initialize();
1173 // Perform initialization for PSParallelCompact that requires
1174 // allocations. This should be called during the VM initialization
1175 // at a pointer where it would be appropriate to return a JNI_ENOMEM
1176 // in the event of a failure.
1177 static bool initialize();
1178
1179 // Closure accessors
1180 static OopClosure* adjust_pointer_closure() { return (OopClosure*)&_adjust_pointer_closure; }
1181 static KlassClosure* adjust_klass_closure() { return (KlassClosure*)&_adjust_klass_closure; }
1182 static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; }
1183
1184 // Public accessors
1185 static elapsedTimer* accumulated_time() { return &_accumulated_time; }
1186 static unsigned int total_invocations() { return _total_invocations; }
1187 static CollectorCounters* counters() { return _counters; }
1188
1189 // Used to add tasks
1190 static GCTaskManager* const gc_task_manager();
1191 static Klass* updated_int_array_klass_obj() {
1192 return _updated_int_array_klass_obj;
1193 }
1194
1195 // Marking support
1196 static inline bool mark_obj(oop obj);
1197 static inline bool is_marked(oop obj);
1198 // Check mark and maybe push on marking stack
1199 template <class T> static inline void mark_and_push(ParCompactionManager* cm,
1200 T* p);
1201 template <class T> static inline void adjust_pointer(T* p);
1202
1203 static inline void follow_klass(ParCompactionManager* cm, Klass* klass);
1204
1205 static void follow_class_loader(ParCompactionManager* cm,
1206 ClassLoaderData* klass);
1207
1208 // Compaction support.
1209 // Return true if p is in the range [beg_addr, end_addr).
1210 static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
1211 static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
1212
1213 // Convenience wrappers for per-space data kept in _space_info.
1214 static inline MutableSpace* space(SpaceId space_id);
1215 static inline HeapWord* new_top(SpaceId space_id);
1216 static inline HeapWord* dense_prefix(SpaceId space_id);
1217 static inline ObjectStartArray* start_array(SpaceId space_id);
1218
1219 // Move and update the live objects in the specified space.
1220 static void move_and_update(ParCompactionManager* cm, SpaceId space_id);
1221
1222 // Process the end of the given region range in the dense prefix.
1223 // This includes saving any object not updated.
1224 static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
1225 size_t region_start_index,
1226 size_t region_end_index,
1227 idx_t exiting_object_offset,
1228 idx_t region_offset_start,
1229 idx_t region_offset_end);
1230
1231 // Update a region in the dense prefix. For each live object
1232 // in the region, update it's interior references. For each
1233 // dead object, fill it with deadwood. Dead space at the end
1234 // of a region range will be filled to the start of the next
1235 // live object regardless of the region_index_end. None of the
1236 // objects in the dense prefix move and dead space is dead
1237 // (holds only dead objects that don't need any processing), so
1238 // dead space can be filled in any order.
1239 static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
1240 SpaceId space_id,
1241 size_t region_index_start,
1242 size_t region_index_end);
1243
1244 // Return the address of the count + 1st live word in the range [beg, end).
1245 static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
1246
1247 // Return the address of the word to be copied to dest_addr, which must be
1248 // aligned to a region boundary.
1249 static HeapWord* first_src_addr(HeapWord* const dest_addr,
1250 SpaceId src_space_id,
1251 size_t src_region_idx);
1252
1253 // Determine the next source region, set closure.source() to the start of the
1254 // new region return the region index. Parameter end_addr is the address one
1255 // beyond the end of source range just processed. If necessary, switch to a
1256 // new source space and set src_space_id (in-out parameter) and src_space_top
1257 // (out parameter) accordingly.
1258 static size_t next_src_region(MoveAndUpdateClosure& closure,
1259 SpaceId& src_space_id,
1260 HeapWord*& src_space_top,
1261 HeapWord* end_addr);
1262
1263 // Decrement the destination count for each non-empty source region in the
1264 // range [beg_region, region(region_align_up(end_addr))). If the destination
1265 // count for a region goes to 0 and it needs to be filled, enqueue it.
1266 static void decrement_destination_counts(ParCompactionManager* cm,
1267 SpaceId src_space_id,
1268 size_t beg_region,
1269 HeapWord* end_addr);
1270
1271 // Fill a region, copying objects from one or more source regions.
1272 static void fill_region(ParCompactionManager* cm, size_t region_idx);
1273 static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
1274 fill_region(cm, region);
1275 }
1276
1277 // Fill in the block table for the specified region.
1278 static void fill_blocks(size_t region_idx);
1279
1280 // Update the deferred objects in the space.
1281 static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
1282
1283 static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
1284 static ParallelCompactData& summary_data() { return _summary_data; }
1285
1286 // Reference Processing
1287 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
1288
1289 static STWGCTimer* gc_timer() { return &_gc_timer; }
1290
1291 // Return the SpaceId for the given address.
1292 static SpaceId space_id(HeapWord* addr);
1293
1294 // Time since last full gc (in milliseconds).
1295 static jlong millis_since_last_gc();
1296
1297 static void print_on_error(outputStream* st);
1298
1299 #ifndef PRODUCT
1300 // Debugging support.
1301 static const char* space_names[last_space_id];
1302 static void print_region_ranges();
1303 static void print_dense_prefix_stats(const char* const algorithm,
1304 const SpaceId id,
1305 const bool maximum_compaction,
1306 HeapWord* const addr);
1307 static void summary_phase_msg(SpaceId dst_space_id,
1308 HeapWord* dst_beg, HeapWord* dst_end,
1309 SpaceId src_space_id,
1310 HeapWord* src_beg, HeapWord* src_end);
1311 #endif // #ifndef PRODUCT
1312
1313 #ifdef ASSERT
1314 // Sanity check the new location of a word in the heap.
1315 static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr);
1316 // Verify that all the regions have been emptied.
1317 static void verify_complete(SpaceId space_id);
1318 #endif // #ifdef ASSERT
1319 };
1320
1321 inline bool PSParallelCompact::mark_obj(oop obj) {
1322 const int obj_size = obj->size();
1323 if (mark_bitmap()->mark_obj(obj, obj_size)) {
1324 _summary_data.add_obj(obj, obj_size);
1325 return true;
1326 } else {
1327 return false;
1328 }
1329 }
1330
1331 inline bool PSParallelCompact::is_marked(oop obj) {
1332 return mark_bitmap()->is_marked(obj);
1333 }
1334
1335 template <class T>
1336 inline void PSParallelCompact::mark_and_push(ParCompactionManager* cm, T* p) {
1337 T heap_oop = oopDesc::load_heap_oop(p);
1338 if (!oopDesc::is_null(heap_oop)) {
1339 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1340 if (mark_bitmap()->is_unmarked(obj) && mark_obj(obj)) {
1341 cm->push(obj);
1342 }
1343 }
1344 }
1345
1346 template <class T>
1347 inline void PSParallelCompact::adjust_pointer(T* p) {
1348 T heap_oop = oopDesc::load_heap_oop(p);
1349 if (!oopDesc::is_null(heap_oop)) {
1350 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1351 oop new_obj = (oop)summary_data().calc_new_pointer(obj);
1352 assert(new_obj != NULL, // is forwarding ptr?
1353 "should be forwarded");
1354 // Just always do the update unconditionally?
1355 if (new_obj != NULL) {
1356 assert(Universe::heap()->is_in_reserved(new_obj),
1357 "should be in object space");
1358 oopDesc::encode_store_heap_oop_not_null(p, new_obj);
1359 }
1360 }
1361 }
1362
1363 inline void PSParallelCompact::follow_klass(ParCompactionManager* cm, Klass* klass) {
1364 oop holder = klass->klass_holder();
1365 PSParallelCompact::mark_and_push(cm, &holder);
1366 }
1367
1368 template <class T>
1369 inline void PSParallelCompact::KeepAliveClosure::do_oop_work(T* p) {
1370 mark_and_push(_compaction_manager, p);
1371 }
1372
1373 inline bool PSParallelCompact::print_phases() {
1374 return _print_phases;
1375 }
1376
1377 inline double PSParallelCompact::normal_distribution(double density) {
1378 assert(_dwl_initialized, "uninitialized");
1379 const double squared_term = (density - _dwl_mean) / _dwl_std_dev;
1380 return _dwl_first_term * exp(-0.5 * squared_term * squared_term);
1381 }
1382
1383 inline bool
1384 PSParallelCompact::dead_space_crosses_boundary(const RegionData* region,
1385 idx_t bit)
1386 {
1387 assert(bit > 0, "cannot call this for the first bit/region");
1388 assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit),
1389 "sanity check");
1390
1391 // Dead space crosses the boundary if (1) a partial object does not extend
1392 // onto the region, (2) an object does not start at the beginning of the
1393 // region, and (3) an object does not end at the end of the prior region.
1394 return region->partial_obj_size() == 0 &&
1395 !_mark_bitmap.is_obj_beg(bit) &&
1396 !_mark_bitmap.is_obj_end(bit - 1);
1397 }
1398
1399 inline bool
1400 PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) {
1401 return p >= beg_addr && p < end_addr;
1402 }
1403
1404 inline bool
1405 PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) {
1406 return is_in((HeapWord*)p, beg_addr, end_addr);
1407 }
1408
1409 inline MutableSpace* PSParallelCompact::space(SpaceId id) {
1410 assert(id < last_space_id, "id out of range");
1411 return _space_info[id].space();
1412 }
1413
1414 inline HeapWord* PSParallelCompact::new_top(SpaceId id) {
1415 assert(id < last_space_id, "id out of range");
1416 return _space_info[id].new_top();
1417 }
1418
1419 inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) {
1420 assert(id < last_space_id, "id out of range");
1421 return _space_info[id].dense_prefix();
1422 }
1423
1424 inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) {
1425 assert(id < last_space_id, "id out of range");
1426 return _space_info[id].start_array();
1427 }
1428
1429 #ifdef ASSERT
1430 inline void
1431 PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr)
1432 {
1433 assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr),
1434 "must move left or to a different space");
1435 assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr),
1436 "checking alignment");
1437 }
1438 #endif // ASSERT
1439
1440 class MoveAndUpdateClosure: public ParMarkBitMapClosure {
1441 public:
1442 inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
1443 ObjectStartArray* start_array,
1444 HeapWord* destination, size_t words);
1445
1446 // Accessors.
1447 HeapWord* destination() const { return _destination; }
1448
1449 // If the object will fit (size <= words_remaining()), copy it to the current
1450 // destination, update the interior oops and the start array and return either
1451 // full (if the closure is full) or incomplete. If the object will not fit,
1452 // return would_overflow.
1453 virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1454
1455 // Copy enough words to fill this closure, starting at source(). Interior
1456 // oops and the start array are not updated. Return full.
1457 IterationStatus copy_until_full();
1458
1459 // Copy enough words to fill this closure or to the end of an object,
1460 // whichever is smaller, starting at source(). Interior oops and the start
1461 // array are not updated.
1462 void copy_partial_obj();
1463
1464 protected:
1465 // Update variables to indicate that word_count words were processed.
1466 inline void update_state(size_t word_count);
1467
1468 protected:
1469 ObjectStartArray* const _start_array;
1470 HeapWord* _destination; // Next addr to be written.
1471 };
1472
1473 inline
1474 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
1475 ParCompactionManager* cm,
1476 ObjectStartArray* start_array,
1477 HeapWord* destination,
1478 size_t words) :
1479 ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)
1480 {
1481 _destination = destination;
1482 }
1483
1484 inline void MoveAndUpdateClosure::update_state(size_t words)
1485 {
1486 decrement_words_remaining(words);
1487 _source += words;
1488 _destination += words;
1489 }
1490
1491 class UpdateOnlyClosure: public ParMarkBitMapClosure {
1492 private:
1493 const PSParallelCompact::SpaceId _space_id;
1494 ObjectStartArray* const _start_array;
1495
1496 public:
1497 UpdateOnlyClosure(ParMarkBitMap* mbm,
1498 ParCompactionManager* cm,
1499 PSParallelCompact::SpaceId space_id);
1500
1501 // Update the object.
1502 virtual IterationStatus do_addr(HeapWord* addr, size_t words);
1503
1504 inline void do_addr(HeapWord* addr);
1505 };
1506
1507 class FillClosure: public ParMarkBitMapClosure
1508 {
1509 public:
1510 FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
1511 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
1512 _start_array(PSParallelCompact::start_array(space_id))
1513 {
1514 assert(space_id == PSParallelCompact::old_space_id,
1515 "cannot use FillClosure in the young gen");
1516 }
1517
1518 virtual IterationStatus do_addr(HeapWord* addr, size_t size) {
1519 CollectedHeap::fill_with_objects(addr, size);
1520 HeapWord* const end = addr + size;
1521 do {
1522 _start_array->allocate_block(addr);
1523 addr += oop(addr)->size();
1524 } while (addr < end);
1525 return ParMarkBitMap::incomplete;
1526 }
1527
1528 private:
1529 ObjectStartArray* const _start_array;
1530 };
1531
1532 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP