1 /*
2 * Copyright (c) 2005, 2013, 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/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 ParCompactionManager;
42 class ParallelTaskTerminator;
43 class PSParallelCompact;
44 class GCTaskManager;
45 class GCTaskQueue;
46 class PreGCValues;
47 class MoveAndUpdateClosure;
48 class RefProcTaskExecutor;
49 class ParallelOldTracer;
50 class STWGCTimer;
51
52 // The SplitInfo class holds the information needed to 'split' a source region
53 // so that the live data can be copied to two destination *spaces*. Normally,
54 // all the live data in a region is copied to a single destination space (e.g.,
55 // everything live in a region in eden is copied entirely into the old gen).
56 // However, when the heap is nearly full, all the live data in eden may not fit
57 // into the old gen. Copying only some of the regions from eden to old gen
58 // requires finding a region that does not contain a partial object (i.e., no
59 // live object crosses the region boundary) somewhere near the last object that
60 // does fit into the old gen. Since it's not always possible to find such a
61 // region, splitting is necessary for predictable behavior.
62 //
63 // A region is always split at the end of the partial object. This avoids
64 // additional tests when calculating the new location of a pointer, which is a
65 // very hot code path. The partial object and everything to its left will be
66 // copied to another space (call it dest_space_1). The live data to the right
67 // of the partial object will be copied either within the space itself, or to a
68 // different destination space (distinct from dest_space_1).
69 //
70 // Split points are identified during the summary phase, when region
71 // destinations are computed: data about the split, including the
72 // partial_object_size, is recorded in a SplitInfo record and the
73 // partial_object_size field in the summary data is set to zero. The zeroing is
74 // possible (and necessary) since the partial object will move to a different
75 // destination space than anything to its right, thus the partial object should
76 // not affect the locations of any objects to its right.
77 //
78 // The recorded data is used during the compaction phase, but only rarely: when
79 // the partial object on the split region will be copied across a destination
80 // region boundary. This test is made once each time a region is filled, and is
81 // a simple address comparison, so the overhead is negligible (see
82 // PSParallelCompact::first_src_addr()).
83 //
84 // Notes:
85 //
86 // Only regions with partial objects are split; a region without a partial
87 // object does not need any extra bookkeeping.
88 //
89 // At most one region is split per space, so the amount of data required is
90 // constant.
91 //
92 // A region is split only when the destination space would overflow. Once that
93 // happens, the destination space is abandoned and no other data (even from
94 // other source spaces) is targeted to that destination space. Abandoning the
95 // destination space may leave a somewhat large unused area at the end, if a
96 // large object caused the overflow.
97 //
98 // Future work:
99 //
100 // More bookkeeping would be required to continue to use the destination space.
101 // The most general solution would allow data from regions in two different
102 // source spaces to be "joined" in a single destination region. At the very
103 // least, additional code would be required in next_src_region() to detect the
104 // join and skip to an out-of-order source region. If the join region was also
105 // the last destination region to which a split region was copied (the most
106 // likely case), then additional work would be needed to get fill_region() to
107 // stop iteration and switch to a new source region at the right point. Basic
108 // idea would be to use a fake value for the top of the source space. It is
109 // doable, if a bit tricky.
110 //
111 // A simpler (but less general) solution would fill the remainder of the
112 // destination region with a dummy object and continue filling the next
113 // destination region.
114
115 class SplitInfo
116 {
117 public:
118 // Return true if this split info is valid (i.e., if a split has been
119 // recorded). The very first region cannot have a partial object and thus is
120 // never split, so 0 is the 'invalid' value.
121 bool is_valid() const { return _src_region_idx > 0; }
122
123 // Return true if this split holds data for the specified source region.
124 inline bool is_split(size_t source_region) const;
125
126 // The index of the split region, the size of the partial object on that
127 // region and the destination of the partial object.
128 size_t src_region_idx() const { return _src_region_idx; }
129 size_t partial_obj_size() const { return _partial_obj_size; }
130 HeapWord* destination() const { return _destination; }
131
132 // The destination count of the partial object referenced by this split
133 // (either 1 or 2). This must be added to the destination count of the
134 // remainder of the source region.
135 unsigned int destination_count() const { return _destination_count; }
136
137 // If a word within the partial object will be written to the first word of a
138 // destination region, this is the address of the destination region;
139 // otherwise this is NULL.
140 HeapWord* dest_region_addr() const { return _dest_region_addr; }
141
142 // If a word within the partial object will be written to the first word of a
143 // destination region, this is the address of that word within the partial
144 // object; otherwise this is NULL.
145 HeapWord* first_src_addr() const { return _first_src_addr; }
146
147 // Record the data necessary to split the region src_region_idx.
148 void record(size_t src_region_idx, size_t partial_obj_size,
149 HeapWord* destination);
150
151 void clear();
152
153 DEBUG_ONLY(void verify_clear();)
154
155 private:
156 size_t _src_region_idx;
157 size_t _partial_obj_size;
158 HeapWord* _destination;
159 unsigned int _destination_count;
160 HeapWord* _dest_region_addr;
161 HeapWord* _first_src_addr;
162 };
163
164 inline bool SplitInfo::is_split(size_t region_idx) const
165 {
166 return _src_region_idx == region_idx && is_valid();
167 }
168
169 class SpaceInfo
170 {
171 public:
172 MutableSpace* space() const { return _space; }
173
174 // Where the free space will start after the collection. Valid only after the
175 // summary phase completes.
176 HeapWord* new_top() const { return _new_top; }
177
178 // Allows new_top to be set.
179 HeapWord** new_top_addr() { return &_new_top; }
180
181 // Where the smallest allowable dense prefix ends (used only for perm gen).
182 HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
183
184 // Where the dense prefix ends, or the compacted region begins.
185 HeapWord* dense_prefix() const { return _dense_prefix; }
186
187 // The start array for the (generation containing the) space, or NULL if there
188 // is no start array.
189 ObjectStartArray* start_array() const { return _start_array; }
190
191 SplitInfo& split_info() { return _split_info; }
192
193 void set_space(MutableSpace* s) { _space = s; }
194 void set_new_top(HeapWord* addr) { _new_top = addr; }
195 void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
196 void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; }
197 void set_start_array(ObjectStartArray* s) { _start_array = s; }
198
199 void publish_new_top() const { _space->set_top(_new_top); }
200
201 private:
202 MutableSpace* _space;
203 HeapWord* _new_top;
204 HeapWord* _min_dense_prefix;
205 HeapWord* _dense_prefix;
206 ObjectStartArray* _start_array;
207 SplitInfo _split_info;
208 };
209
210 class ParallelCompactData
211 {
212 public:
213 // Sizes are in HeapWords, unless indicated otherwise.
214 static const size_t Log2RegionSize;
215 static const size_t RegionSize;
216 static const size_t RegionSizeBytes;
217
218 // Mask for the bits in a size_t to get an offset within a region.
219 static const size_t RegionSizeOffsetMask;
220 // Mask for the bits in a pointer to get an offset within a region.
221 static const size_t RegionAddrOffsetMask;
222 // Mask for the bits in a pointer to get the address of the start of a region.
223 static const size_t RegionAddrMask;
224
225 static const size_t Log2BlockSize;
226 static const size_t BlockSize;
227 static const size_t BlockSizeBytes;
228
229 static const size_t BlockSizeOffsetMask;
230 static const size_t BlockAddrOffsetMask;
231 static const size_t BlockAddrMask;
232
233 static const size_t BlocksPerRegion;
234 static const size_t Log2BlocksPerRegion;
235
236 class RegionData
237 {
238 public:
239 // Destination address of the region.
240 HeapWord* destination() const { return _destination; }
241
242 // The first region containing data destined for this region.
243 size_t source_region() const { return _source_region; }
244
245 // The object (if any) starting in this region and ending in a different
246 // region that could not be updated during the main (parallel) compaction
247 // phase. This is different from _partial_obj_addr, which is an object that
248 // extends onto a source region. However, the two uses do not overlap in
249 // time, so the same field is used to save space.
250 HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
251
252 // The starting address of the partial object extending onto the region.
253 HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
254
255 // Size of the partial object extending onto the region (words).
256 size_t partial_obj_size() const { return _partial_obj_size; }
257
258 // Size of live data that lies within this region due to objects that start
259 // in this region (words). This does not include the partial object
260 // extending onto the region (if any), or the part of an object that extends
261 // onto the next region (if any).
262 size_t live_obj_size() const { return _dc_and_los & los_mask; }
263
264 // Total live data that lies within the region (words).
265 size_t data_size() const { return partial_obj_size() + live_obj_size(); }
266
267 // The destination_count is the number of other regions to which data from
268 // this region will be copied. At the end of the summary phase, the valid
269 // values of destination_count are
270 //
271 // 0 - data from the region will be compacted completely into itself, or the
272 // region is empty. The region can be claimed and then filled.
273 // 1 - data from the region will be compacted into 1 other region; some
274 // data from the region may also be compacted into the region itself.
275 // 2 - data from the region will be copied to 2 other regions.
276 //
277 // During compaction as regions are emptied, the destination_count is
278 // decremented (atomically) and when it reaches 0, it can be claimed and
279 // then filled.
280 //
281 // A region is claimed for processing by atomically changing the
282 // destination_count to the claimed value (dc_claimed). After a region has
283 // been filled, the destination_count should be set to the completed value
284 // (dc_completed).
285 inline uint destination_count() const;
286 inline uint destination_count_raw() const;
287
288 // Whether the block table for this region has been filled.
289 inline bool blocks_filled() const;
290
291 // Number of times the block table was filled.
292 DEBUG_ONLY(inline size_t blocks_filled_count() const;)
293
294 // The location of the java heap data that corresponds to this region.
295 inline HeapWord* data_location() const;
296
297 // The highest address referenced by objects in this region.
298 inline HeapWord* highest_ref() const;
299
300 // Whether this region is available to be claimed, has been claimed, or has
301 // been completed.
302 //
303 // Minor subtlety: claimed() returns true if the region is marked
304 // completed(), which is desirable since a region must be claimed before it
305 // can be completed.
306 bool available() const { return _dc_and_los < dc_one; }
307 bool claimed() const { return _dc_and_los >= dc_claimed; }
308 bool completed() const { return _dc_and_los >= dc_completed; }
309
310 // These are not atomic.
311 void set_destination(HeapWord* addr) { _destination = addr; }
312 void set_source_region(size_t region) { _source_region = region; }
313 void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
314 void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
315 void set_partial_obj_size(size_t words) {
316 _partial_obj_size = (region_sz_t) words;
317 }
318 inline void set_blocks_filled();
319
320 inline void set_destination_count(uint count);
321 inline void set_live_obj_size(size_t words);
322 inline void set_data_location(HeapWord* addr);
323 inline void set_completed();
324 inline bool claim_unsafe();
325
326 // These are atomic.
327 inline void add_live_obj(size_t words);
328 inline void set_highest_ref(HeapWord* addr);
329 inline void decrement_destination_count();
330 inline bool claim();
331
332 private:
333 // The type used to represent object sizes within a region.
334 typedef uint region_sz_t;
335
336 // Constants for manipulating the _dc_and_los field, which holds both the
337 // destination count and live obj size. The live obj size lives at the
338 // least significant end so no masking is necessary when adding.
339 static const region_sz_t dc_shift; // Shift amount.
340 static const region_sz_t dc_mask; // Mask for destination count.
341 static const region_sz_t dc_one; // 1, shifted appropriately.
342 static const region_sz_t dc_claimed; // Region has been claimed.
343 static const region_sz_t dc_completed; // Region has been completed.
344 static const region_sz_t los_mask; // Mask for live obj size.
345
346 HeapWord* _destination;
347 size_t _source_region;
348 HeapWord* _partial_obj_addr;
349 region_sz_t _partial_obj_size;
350 region_sz_t volatile _dc_and_los;
351 bool _blocks_filled;
352
353 #ifdef ASSERT
354 size_t _blocks_filled_count; // Number of block table fills.
355
356 // These enable optimizations that are only partially implemented. Use
357 // debug builds to prevent the code fragments from breaking.
358 HeapWord* _data_location;
359 HeapWord* _highest_ref;
360 #endif // #ifdef ASSERT
361
362 #ifdef ASSERT
363 public:
364 uint _pushed; // 0 until region is pushed onto a stack
365 private:
366 #endif
367 };
368
369 // "Blocks" allow shorter sections of the bitmap to be searched. Each Block
370 // holds an offset, which is the amount of live data in the Region to the left
371 // of the first live object that starts in the Block.
372 class BlockData
373 {
374 public:
375 typedef unsigned short int blk_ofs_t;
376
377 blk_ofs_t offset() const { return _offset; }
378 void set_offset(size_t val) { _offset = (blk_ofs_t)val; }
379
380 private:
381 blk_ofs_t _offset;
382 };
383
384 public:
385 ParallelCompactData();
386 bool initialize(MemRegion covered_region);
387
388 size_t region_count() const { return _region_count; }
389 size_t reserved_byte_size() const { return _reserved_byte_size; }
390
391 // Convert region indices to/from RegionData pointers.
392 inline RegionData* region(size_t region_idx) const;
393 inline size_t region(const RegionData* const region_ptr) const;
394
395 size_t block_count() const { return _block_count; }
396 inline BlockData* block(size_t block_idx) const;
397 inline size_t block(const BlockData* block_ptr) const;
398
399 void add_obj(HeapWord* addr, size_t len);
400 void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
401
402 // Fill in the regions covering [beg, end) so that no data moves; i.e., the
403 // destination of region n is simply the start of region n. The argument beg
404 // must be region-aligned; end need not be.
405 void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
406
407 HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info,
408 HeapWord* destination, HeapWord* target_end,
409 HeapWord** target_next);
410 bool summarize(SplitInfo& split_info,
411 HeapWord* source_beg, HeapWord* source_end,
412 HeapWord** source_next,
413 HeapWord* target_beg, HeapWord* target_end,
414 HeapWord** target_next);
415
416 void clear();
417 void clear_range(size_t beg_region, size_t end_region);
418 void clear_range(HeapWord* beg, HeapWord* end) {
419 clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
420 }
421
422 // Return the number of words between addr and the start of the region
423 // containing addr.
424 inline size_t region_offset(const HeapWord* addr) const;
425
426 // Convert addresses to/from a region index or region pointer.
427 inline size_t addr_to_region_idx(const HeapWord* addr) const;
428 inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
429 inline HeapWord* region_to_addr(size_t region) const;
430 inline HeapWord* region_to_addr(size_t region, size_t offset) const;
431 inline HeapWord* region_to_addr(const RegionData* region) const;
432
433 inline HeapWord* region_align_down(HeapWord* addr) const;
434 inline HeapWord* region_align_up(HeapWord* addr) const;
435 inline bool is_region_aligned(HeapWord* addr) const;
436
437 // Analogous to region_offset() for blocks.
438 size_t block_offset(const HeapWord* addr) const;
439 size_t addr_to_block_idx(const HeapWord* addr) const;
440 size_t addr_to_block_idx(const oop obj) const {
441 return addr_to_block_idx((HeapWord*) obj);
442 }
443 inline BlockData* addr_to_block_ptr(const HeapWord* addr) const;
444 inline HeapWord* block_to_addr(size_t block) const;
445 inline size_t region_to_block_idx(size_t region) const;
446
447 inline HeapWord* block_align_down(HeapWord* addr) const;
448 inline HeapWord* block_align_up(HeapWord* addr) const;
449 inline bool is_block_aligned(HeapWord* addr) const;
450
451 // Return the address one past the end of the partial object.
452 HeapWord* partial_obj_end(size_t region_idx) const;
453
454 // Return the location of the object after compaction.
455 HeapWord* calc_new_pointer(HeapWord* addr);
456
457 HeapWord* calc_new_pointer(oop p) {
458 return calc_new_pointer((HeapWord*) p);
459 }
460
461 #ifdef ASSERT
462 void verify_clear(const PSVirtualSpace* vspace);
463 void verify_clear();
464 #endif // #ifdef ASSERT
465
466 private:
467 bool initialize_block_data();
468 bool initialize_region_data(size_t region_size);
469 PSVirtualSpace* create_vspace(size_t count, size_t element_size);
470
471 private:
472 HeapWord* _region_start;
473 #ifdef ASSERT
474 HeapWord* _region_end;
475 #endif // #ifdef ASSERT
476
477 PSVirtualSpace* _region_vspace;
478 size_t _reserved_byte_size;
479 RegionData* _region_data;
480 size_t _region_count;
481
482 PSVirtualSpace* _block_vspace;
483 BlockData* _block_data;
484 size_t _block_count;
485 };
486
487 inline uint
488 ParallelCompactData::RegionData::destination_count_raw() const
489 {
490 return _dc_and_los & dc_mask;
491 }
492
493 inline uint
494 ParallelCompactData::RegionData::destination_count() const
495 {
496 return destination_count_raw() >> dc_shift;
497 }
498
499 inline bool
500 ParallelCompactData::RegionData::blocks_filled() const
501 {
502 return _blocks_filled;
503 }
504
505 #ifdef ASSERT
506 inline size_t
507 ParallelCompactData::RegionData::blocks_filled_count() const
508 {
509 return _blocks_filled_count;
510 }
511 #endif // #ifdef ASSERT
512
513 inline void
514 ParallelCompactData::RegionData::set_blocks_filled()
515 {
516 _blocks_filled = true;
517 // Debug builds count the number of times the table was filled.
518 DEBUG_ONLY(Atomic::inc_ptr(&_blocks_filled_count));
519 }
520
521 inline void
522 ParallelCompactData::RegionData::set_destination_count(uint count)
523 {
524 assert(count <= (dc_completed >> dc_shift), "count too large");
525 const region_sz_t live_sz = (region_sz_t) live_obj_size();
526 _dc_and_los = (count << dc_shift) | live_sz;
527 }
528
529 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
530 {
531 assert(words <= los_mask, "would overflow");
532 _dc_and_los = destination_count_raw() | (region_sz_t)words;
533 }
534
535 inline void ParallelCompactData::RegionData::decrement_destination_count()
536 {
537 assert(_dc_and_los < dc_claimed, "already claimed");
538 assert(_dc_and_los >= dc_one, "count would go negative");
539 Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);
540 }
541
542 inline HeapWord* ParallelCompactData::RegionData::data_location() const
543 {
544 DEBUG_ONLY(return _data_location;)
545 NOT_DEBUG(return NULL;)
546 }
547
548 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
549 {
550 DEBUG_ONLY(return _highest_ref;)
551 NOT_DEBUG(return NULL;)
552 }
553
554 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
555 {
556 DEBUG_ONLY(_data_location = addr;)
557 }
558
559 inline void ParallelCompactData::RegionData::set_completed()
560 {
561 assert(claimed(), "must be claimed first");
562 _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
563 }
564
565 // MT-unsafe claiming of a region. Should only be used during single threaded
566 // execution.
567 inline bool ParallelCompactData::RegionData::claim_unsafe()
568 {
569 if (available()) {
570 _dc_and_los |= dc_claimed;
571 return true;
572 }
573 return false;
574 }
575
576 inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
577 {
578 assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
579 Atomic::add((int) words, (volatile int*) &_dc_and_los);
580 }
581
582 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
583 {
584 #ifdef ASSERT
585 HeapWord* tmp = _highest_ref;
586 while (addr > tmp) {
587 tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp);
588 }
589 #endif // #ifdef ASSERT
590 }
591
592 inline bool ParallelCompactData::RegionData::claim()
593 {
594 const int los = (int) live_obj_size();
595 const int old = Atomic::cmpxchg(dc_claimed | los,
596 (volatile int*) &_dc_and_los, los);
597 return old == los;
598 }
599
600 inline ParallelCompactData::RegionData*
601 ParallelCompactData::region(size_t region_idx) const
602 {
603 assert(region_idx <= region_count(), "bad arg");
604 return _region_data + region_idx;
605 }
606
607 inline size_t
608 ParallelCompactData::region(const RegionData* const region_ptr) const
609 {
610 assert(region_ptr >= _region_data, "bad arg");
611 assert(region_ptr <= _region_data + region_count(), "bad arg");
612 return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
613 }
614
615 inline ParallelCompactData::BlockData*
616 ParallelCompactData::block(size_t n) const {
617 assert(n < block_count(), "bad arg");
618 return _block_data + n;
619 }
620
621 inline size_t
622 ParallelCompactData::region_offset(const HeapWord* addr) const
623 {
624 assert(addr >= _region_start, "bad addr");
625 assert(addr <= _region_end, "bad addr");
626 return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
627 }
628
629 inline size_t
630 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
631 {
632 assert(addr >= _region_start, "bad addr");
633 assert(addr <= _region_end, "bad addr");
634 return pointer_delta(addr, _region_start) >> Log2RegionSize;
635 }
636
637 inline ParallelCompactData::RegionData*
638 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
639 {
640 return region(addr_to_region_idx(addr));
641 }
642
643 inline HeapWord*
644 ParallelCompactData::region_to_addr(size_t region) const
645 {
646 assert(region <= _region_count, "region out of range");
647 return _region_start + (region << Log2RegionSize);
648 }
649
650 inline HeapWord*
651 ParallelCompactData::region_to_addr(const RegionData* region) const
652 {
653 return region_to_addr(pointer_delta(region, _region_data,
654 sizeof(RegionData)));
655 }
656
657 inline HeapWord*
658 ParallelCompactData::region_to_addr(size_t region, size_t offset) const
659 {
660 assert(region <= _region_count, "region out of range");
661 assert(offset < RegionSize, "offset too big"); // This may be too strict.
662 return region_to_addr(region) + offset;
663 }
664
665 inline HeapWord*
666 ParallelCompactData::region_align_down(HeapWord* addr) const
667 {
668 assert(addr >= _region_start, "bad addr");
669 assert(addr < _region_end + RegionSize, "bad addr");
670 return (HeapWord*)(size_t(addr) & RegionAddrMask);
671 }
672
673 inline HeapWord*
674 ParallelCompactData::region_align_up(HeapWord* addr) const
675 {
676 assert(addr >= _region_start, "bad addr");
677 assert(addr <= _region_end, "bad addr");
678 return region_align_down(addr + RegionSizeOffsetMask);
679 }
680
681 inline bool
682 ParallelCompactData::is_region_aligned(HeapWord* addr) const
683 {
684 return region_offset(addr) == 0;
685 }
686
687 inline size_t
688 ParallelCompactData::block_offset(const HeapWord* addr) const
689 {
690 assert(addr >= _region_start, "bad addr");
691 assert(addr <= _region_end, "bad addr");
692 return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize;
693 }
694
695 inline size_t
696 ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const
697 {
698 assert(addr >= _region_start, "bad addr");
699 assert(addr <= _region_end, "bad addr");
700 return pointer_delta(addr, _region_start) >> Log2BlockSize;
701 }
702
703 inline ParallelCompactData::BlockData*
704 ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const
705 {
706 return block(addr_to_block_idx(addr));
707 }
708
709 inline HeapWord*
710 ParallelCompactData::block_to_addr(size_t block) const
711 {
712 assert(block < _block_count, "block out of range");
713 return _region_start + (block << Log2BlockSize);
714 }
715
716 inline size_t
717 ParallelCompactData::region_to_block_idx(size_t region) const
718 {
719 return region << Log2BlocksPerRegion;
720 }
721
722 inline HeapWord*
723 ParallelCompactData::block_align_down(HeapWord* addr) const
724 {
725 assert(addr >= _region_start, "bad addr");
726 assert(addr < _region_end + RegionSize, "bad addr");
727 return (HeapWord*)(size_t(addr) & BlockAddrMask);
728 }
729
730 inline HeapWord*
731 ParallelCompactData::block_align_up(HeapWord* addr) const
732 {
733 assert(addr >= _region_start, "bad addr");
734 assert(addr <= _region_end, "bad addr");
735 return block_align_down(addr + BlockSizeOffsetMask);
736 }
737
738 inline bool
739 ParallelCompactData::is_block_aligned(HeapWord* addr) const
740 {
741 return block_offset(addr) == 0;
742 }
743
744 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
745 // do_addr() method.
746 //
747 // The closure is initialized with the number of heap words to process
748 // (words_remaining()), and becomes 'full' when it reaches 0. The do_addr()
749 // methods in subclasses should update the total as words are processed. Since
750 // only one subclass actually uses this mechanism to terminate iteration, the
751 // default initial value is > 0. The implementation is here and not in the
752 // single subclass that uses it to avoid making is_full() virtual, and thus
753 // adding a virtual call per live object.
754
755 class ParMarkBitMapClosure: public StackObj {
756 public:
757 typedef ParMarkBitMap::idx_t idx_t;
758 typedef ParMarkBitMap::IterationStatus IterationStatus;
759
760 public:
761 inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
762 size_t words = max_uintx);
763
764 inline ParCompactionManager* compaction_manager() const;
765 inline ParMarkBitMap* bitmap() const;
766 inline size_t words_remaining() const;
767 inline bool is_full() const;
768 inline HeapWord* source() const;
769
770 inline void set_source(HeapWord* addr);
771
772 virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
773
774 protected:
775 inline void decrement_words_remaining(size_t words);
776
777 private:
778 ParMarkBitMap* const _bitmap;
779 ParCompactionManager* const _compaction_manager;
780 DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger.
781 size_t _words_remaining; // Words left to copy.
782
783 protected:
784 HeapWord* _source; // Next addr that would be read.
785 };
786
787 inline
788 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
789 ParCompactionManager* cm,
790 size_t words):
791 _bitmap(bitmap), _compaction_manager(cm)
792 #ifdef ASSERT
793 , _initial_words_remaining(words)
794 #endif
795 {
796 _words_remaining = words;
797 _source = NULL;
798 }
799
800 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
801 return _compaction_manager;
802 }
803
804 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
805 return _bitmap;
806 }
807
808 inline size_t ParMarkBitMapClosure::words_remaining() const {
809 return _words_remaining;
810 }
811
812 inline bool ParMarkBitMapClosure::is_full() const {
813 return words_remaining() == 0;
814 }
815
816 inline HeapWord* ParMarkBitMapClosure::source() const {
817 return _source;
818 }
819
820 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
821 _source = addr;
822 }
823
824 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
825 assert(_words_remaining >= words, "processed too many words");
826 _words_remaining -= words;
827 }
828
829 // The UseParallelOldGC collector is a stop-the-world garbage collector that
830 // does parts of the collection using parallel threads. The collection includes
831 // the tenured generation and the young generation. The permanent generation is
832 // collected at the same time as the other two generations but the permanent
833 // generation is collect by a single GC thread. The permanent generation is
834 // collected serially because of the requirement that during the processing of a
835 // klass AAA, any objects reference by AAA must already have been processed.
836 // This requirement is enforced by a left (lower address) to right (higher
837 // address) sliding compaction.
838 //
839 // There are four phases of the collection.
840 //
841 // - marking phase
842 // - summary phase
843 // - compacting phase
844 // - clean up phase
845 //
846 // Roughly speaking these phases correspond, respectively, to
847 // - mark all the live objects
848 // - calculate the destination of each object at the end of the collection
849 // - move the objects to their destination
850 // - update some references and reinitialize some variables
851 //
852 // These three phases are invoked in PSParallelCompact::invoke_no_policy(). The
853 // marking phase is implemented in PSParallelCompact::marking_phase() and does a
854 // complete marking of the heap. The summary phase is implemented in
855 // PSParallelCompact::summary_phase(). The move and update phase is implemented
856 // in PSParallelCompact::compact().
857 //
858 // A space that is being collected is divided into regions and with each region
859 // is associated an object of type ParallelCompactData. Each region is of a
860 // fixed size and typically will contain more than 1 object and may have parts
861 // of objects at the front and back of the region.
862 //
863 // region -----+---------------------+----------
864 // objects covered [ AAA )[ BBB )[ CCC )[ DDD )
865 //
866 // The marking phase does a complete marking of all live objects in the heap.
867 // The marking also compiles the size of the data for all live objects covered
868 // by the region. This size includes the part of any live object spanning onto
869 // the region (part of AAA if it is live) from the front, all live objects
870 // contained in the region (BBB and/or CCC if they are live), and the part of
871 // any live objects covered by the region that extends off the region (part of
872 // DDD if it is live). The marking phase uses multiple GC threads and marking
873 // is done in a bit array of type ParMarkBitMap. The marking of the bit map is
874 // done atomically as is the accumulation of the size of the live objects
875 // covered by a region.
876 //
877 // The summary phase calculates the total live data to the left of each region
878 // XXX. Based on that total and the bottom of the space, it can calculate the
879 // starting location of the live data in XXX. The summary phase calculates for
880 // each region XXX quantities such as
881 //
882 // - the amount of live data at the beginning of a region from an object
883 // entering the region.
884 // - the location of the first live data on the region
885 // - a count of the number of regions receiving live data from XXX.
886 //
887 // See ParallelCompactData for precise details. The summary phase also
888 // calculates the dense prefix for the compaction. The dense prefix is a
889 // portion at the beginning of the space that is not moved. The objects in the
890 // dense prefix do need to have their object references updated. See method
891 // summarize_dense_prefix().
892 //
893 // The summary phase is done using 1 GC thread.
894 //
895 // The compaction phase moves objects to their new location and updates all
896 // references in the object.
897 //
898 // A current exception is that objects that cross a region boundary are moved
899 // but do not have their references updated. References are not updated because
900 // it cannot easily be determined if the klass pointer KKK for the object AAA
901 // has been updated. KKK likely resides in a region to the left of the region
902 // containing AAA. These AAA's have there references updated at the end in a
903 // clean up phase. See the method PSParallelCompact::update_deferred_objects().
904 // An alternate strategy is being investigated for this deferral of updating.
905 //
906 // Compaction is done on a region basis. A region that is ready to be filled is
907 // put on a ready list and GC threads take region off the list and fill them. A
908 // region is ready to be filled if it empty of live objects. Such a region may
909 // have been initially empty (only contained dead objects) or may have had all
910 // its live objects copied out already. A region that compacts into itself is
911 // also ready for filling. The ready list is initially filled with empty
912 // regions and regions compacting into themselves. There is always at least 1
913 // region that can be put on the ready list. The regions are atomically added
914 // and removed from the ready list.
915
916 class PSParallelCompact : AllStatic {
917 public:
918 // Convenient access to type names.
919 typedef ParMarkBitMap::idx_t idx_t;
920 typedef ParallelCompactData::RegionData RegionData;
921 typedef ParallelCompactData::BlockData BlockData;
922
923 typedef enum {
924 old_space_id, eden_space_id,
925 from_space_id, to_space_id, last_space_id
926 } SpaceId;
927
928 public:
929 // Inline closure decls
930 //
931 class IsAliveClosure: public BoolObjectClosure {
932 public:
933 virtual bool do_object_b(oop p);
934 };
935
936 class KeepAliveClosure: public OopClosure {
937 private:
938 ParCompactionManager* _compaction_manager;
939 protected:
940 template <class T> inline void do_oop_work(T* p);
941 public:
942 KeepAliveClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
943 virtual void do_oop(oop* p);
944 virtual void do_oop(narrowOop* p);
945 };
946
947 class FollowStackClosure: public VoidClosure {
948 private:
949 ParCompactionManager* _compaction_manager;
950 public:
951 FollowStackClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
952 virtual void do_void();
953 };
954
955 class AdjustPointerClosure: public OopClosure {
956 public:
957 virtual void do_oop(oop* p);
958 virtual void do_oop(narrowOop* p);
959 // do not walk from thread stacks to the code cache on this phase
960 virtual void do_code_blob(CodeBlob* cb) const { }
961 };
962
963 class AdjustKlassClosure : public KlassClosure {
964 public:
965 void do_klass(Klass* klass);
966 };
967
968 friend class KeepAliveClosure;
969 friend class FollowStackClosure;
970 friend class AdjustPointerClosure;
971 friend class AdjustKlassClosure;
972 friend class FollowKlassClosure;
973 friend class InstanceClassLoaderKlass;
974 friend class RefProcTaskProxy;
975
976 private:
977 static STWGCTimer _gc_timer;
978 static ParallelOldTracer _gc_tracer;
979 static elapsedTimer _accumulated_time;
980 static unsigned int _total_invocations;
981 static unsigned int _maximum_compaction_gc_num;
982 static jlong _time_of_last_gc; // ms
983 static CollectorCounters* _counters;
984 static ParMarkBitMap _mark_bitmap;
985 static ParallelCompactData _summary_data;
986 static IsAliveClosure _is_alive_closure;
987 static SpaceInfo _space_info[last_space_id];
988 static bool _print_phases;
989 static AdjustPointerClosure _adjust_pointer_closure;
990 static AdjustKlassClosure _adjust_klass_closure;
991
992 // Reference processing (used in ...follow_contents)
993 static ReferenceProcessor* _ref_processor;
994
995 // Updated location of intArrayKlassObj.
996 static Klass* _updated_int_array_klass_obj;
997
998 // Values computed at initialization and used by dead_wood_limiter().
999 static double _dwl_mean;
1000 static double _dwl_std_dev;
1001 static double _dwl_first_term;
1002 static double _dwl_adjustment;
1003 #ifdef ASSERT
1004 static bool _dwl_initialized;
1005 #endif // #ifdef ASSERT
1006
1007 private:
1008
1009 static void initialize_space_info();
1010
1011 // Return true if details about individual phases should be printed.
1012 static inline bool print_phases();
1013
1014 // Clear the marking bitmap and summary data that cover the specified space.
1015 static void clear_data_covering_space(SpaceId id);
1016
1017 static void pre_compact(PreGCValues* pre_gc_values);
1018 static void post_compact();
1019
1020 // Mark live objects
1021 static void marking_phase(ParCompactionManager* cm,
1022 bool maximum_heap_compaction,
1023 ParallelOldTracer *gc_tracer);
1024
1025 template <class T>
1026 static inline void follow_root(ParCompactionManager* cm, T* p);
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 void follow_klass(ParCompactionManager* cm, Klass* klass);
1204 static void adjust_klass(ParCompactionManager* cm, Klass* klass);
1205
1206 static void follow_class_loader(ParCompactionManager* cm,
1207 ClassLoaderData* klass);
1208 static void adjust_class_loader(ParCompactionManager* cm,
1209 ClassLoaderData* klass);
1210
1211 // Compaction support.
1212 // Return true if p is in the range [beg_addr, end_addr).
1213 static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
1214 static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
1215
1216 // Convenience wrappers for per-space data kept in _space_info.
1217 static inline MutableSpace* space(SpaceId space_id);
1218 static inline HeapWord* new_top(SpaceId space_id);
1219 static inline HeapWord* dense_prefix(SpaceId space_id);
1220 static inline ObjectStartArray* start_array(SpaceId space_id);
1221
1222 // Move and update the live objects in the specified space.
1223 static void move_and_update(ParCompactionManager* cm, SpaceId space_id);
1224
1225 // Process the end of the given region range in the dense prefix.
1226 // This includes saving any object not updated.
1227 static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
1228 size_t region_start_index,
1229 size_t region_end_index,
1230 idx_t exiting_object_offset,
1231 idx_t region_offset_start,
1232 idx_t region_offset_end);
1233
1234 // Update a region in the dense prefix. For each live object
1235 // in the region, update it's interior references. For each
1236 // dead object, fill it with deadwood. Dead space at the end
1237 // of a region range will be filled to the start of the next
1238 // live object regardless of the region_index_end. None of the
1239 // objects in the dense prefix move and dead space is dead
1240 // (holds only dead objects that don't need any processing), so
1241 // dead space can be filled in any order.
1242 static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
1243 SpaceId space_id,
1244 size_t region_index_start,
1245 size_t region_index_end);
1246
1247 // Return the address of the count + 1st live word in the range [beg, end).
1248 static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
1249
1250 // Return the address of the word to be copied to dest_addr, which must be
1251 // aligned to a region boundary.
1252 static HeapWord* first_src_addr(HeapWord* const dest_addr,
1253 SpaceId src_space_id,
1254 size_t src_region_idx);
1255
1256 // Determine the next source region, set closure.source() to the start of the
1257 // new region return the region index. Parameter end_addr is the address one
1258 // beyond the end of source range just processed. If necessary, switch to a
1259 // new source space and set src_space_id (in-out parameter) and src_space_top
1260 // (out parameter) accordingly.
1261 static size_t next_src_region(MoveAndUpdateClosure& closure,
1262 SpaceId& src_space_id,
1263 HeapWord*& src_space_top,
1264 HeapWord* end_addr);
1265
1266 // Decrement the destination count for each non-empty source region in the
1267 // range [beg_region, region(region_align_up(end_addr))). If the destination
1268 // count for a region goes to 0 and it needs to be filled, enqueue it.
1269 static void decrement_destination_counts(ParCompactionManager* cm,
1270 SpaceId src_space_id,
1271 size_t beg_region,
1272 HeapWord* end_addr);
1273
1274 // Fill a region, copying objects from one or more source regions.
1275 static void fill_region(ParCompactionManager* cm, size_t region_idx);
1276 static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
1277 fill_region(cm, region);
1278 }
1279
1280 // Fill in the block table for the specified region.
1281 static void fill_blocks(size_t region_idx);
1282
1283 // Update the deferred objects in the space.
1284 static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
1285
1286 static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
1287 static ParallelCompactData& summary_data() { return _summary_data; }
1288
1289 // Reference Processing
1290 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
1291
1292 static STWGCTimer* gc_timer() { return &_gc_timer; }
1293
1294 // Return the SpaceId for the given address.
1295 static SpaceId space_id(HeapWord* addr);
1296
1297 // Time since last full gc (in milliseconds).
1298 static jlong millis_since_last_gc();
1299
1300 static void print_on_error(outputStream* st);
1301
1302 #ifndef PRODUCT
1303 // Debugging support.
1304 static const char* space_names[last_space_id];
1305 static void print_region_ranges();
1306 static void print_dense_prefix_stats(const char* const algorithm,
1307 const SpaceId id,
1308 const bool maximum_compaction,
1309 HeapWord* const addr);
1310 static void summary_phase_msg(SpaceId dst_space_id,
1311 HeapWord* dst_beg, HeapWord* dst_end,
1312 SpaceId src_space_id,
1313 HeapWord* src_beg, HeapWord* src_end);
1314 #endif // #ifndef PRODUCT
1315
1316 #ifdef ASSERT
1317 // Sanity check the new location of a word in the heap.
1318 static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr);
1319 // Verify that all the regions have been emptied.
1320 static void verify_complete(SpaceId space_id);
1321 #endif // #ifdef ASSERT
1322 };
1323
1324 inline bool PSParallelCompact::mark_obj(oop obj) {
1325 const int obj_size = obj->size();
1326 if (mark_bitmap()->mark_obj(obj, obj_size)) {
1327 _summary_data.add_obj(obj, obj_size);
1328 return true;
1329 } else {
1330 return false;
1331 }
1332 }
1333
1334 inline bool PSParallelCompact::is_marked(oop obj) {
1335 return mark_bitmap()->is_marked(obj);
1336 }
1337
1338 template <class T>
1339 inline void PSParallelCompact::follow_root(ParCompactionManager* cm, T* p) {
1340 assert(!Universe::heap()->is_in_reserved(p),
1341 "roots shouldn't be things within the heap");
1342
1343 T heap_oop = oopDesc::load_heap_oop(p);
1344 if (!oopDesc::is_null(heap_oop)) {
1345 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1346 if (mark_bitmap()->is_unmarked(obj)) {
1347 if (mark_obj(obj)) {
1348 obj->follow_contents(cm);
1349 }
1350 }
1351 }
1352 cm->follow_marking_stacks();
1353 }
1354
1355 template <class T>
1356 inline void PSParallelCompact::mark_and_push(ParCompactionManager* cm, T* p) {
1357 T heap_oop = oopDesc::load_heap_oop(p);
1358 if (!oopDesc::is_null(heap_oop)) {
1359 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1360 if (mark_bitmap()->is_unmarked(obj) && mark_obj(obj)) {
1361 cm->push(obj);
1362 }
1363 }
1364 }
1365
1366 template <class T>
1367 inline void PSParallelCompact::adjust_pointer(T* p) {
1368 T heap_oop = oopDesc::load_heap_oop(p);
1369 if (!oopDesc::is_null(heap_oop)) {
1370 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1371 oop new_obj = (oop)summary_data().calc_new_pointer(obj);
1372 assert(new_obj != NULL, // is forwarding ptr?
1373 "should be forwarded");
1374 // Just always do the update unconditionally?
1375 if (new_obj != NULL) {
1376 assert(Universe::heap()->is_in_reserved(new_obj),
1377 "should be in object space");
1378 oopDesc::encode_store_heap_oop_not_null(p, new_obj);
1379 }
1380 }
1381 }
1382
1383 template <class T>
1384 inline void PSParallelCompact::KeepAliveClosure::do_oop_work(T* p) {
1385 mark_and_push(_compaction_manager, p);
1386 }
1387
1388 inline bool PSParallelCompact::print_phases() {
1389 return _print_phases;
1390 }
1391
1392 inline double PSParallelCompact::normal_distribution(double density) {
1393 assert(_dwl_initialized, "uninitialized");
1394 const double squared_term = (density - _dwl_mean) / _dwl_std_dev;
1395 return _dwl_first_term * exp(-0.5 * squared_term * squared_term);
1396 }
1397
1398 inline bool
1399 PSParallelCompact::dead_space_crosses_boundary(const RegionData* region,
1400 idx_t bit)
1401 {
1402 assert(bit > 0, "cannot call this for the first bit/region");
1403 assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit),
1404 "sanity check");
1405
1406 // Dead space crosses the boundary if (1) a partial object does not extend
1407 // onto the region, (2) an object does not start at the beginning of the
1408 // region, and (3) an object does not end at the end of the prior region.
1409 return region->partial_obj_size() == 0 &&
1410 !_mark_bitmap.is_obj_beg(bit) &&
1411 !_mark_bitmap.is_obj_end(bit - 1);
1412 }
1413
1414 inline bool
1415 PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) {
1416 return p >= beg_addr && p < end_addr;
1417 }
1418
1419 inline bool
1420 PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) {
1421 return is_in((HeapWord*)p, beg_addr, end_addr);
1422 }
1423
1424 inline MutableSpace* PSParallelCompact::space(SpaceId id) {
1425 assert(id < last_space_id, "id out of range");
1426 return _space_info[id].space();
1427 }
1428
1429 inline HeapWord* PSParallelCompact::new_top(SpaceId id) {
1430 assert(id < last_space_id, "id out of range");
1431 return _space_info[id].new_top();
1432 }
1433
1434 inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) {
1435 assert(id < last_space_id, "id out of range");
1436 return _space_info[id].dense_prefix();
1437 }
1438
1439 inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) {
1440 assert(id < last_space_id, "id out of range");
1441 return _space_info[id].start_array();
1442 }
1443
1444 #ifdef ASSERT
1445 inline void
1446 PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr)
1447 {
1448 assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr),
1449 "must move left or to a different space");
1450 assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr),
1451 "checking alignment");
1452 }
1453 #endif // ASSERT
1454
1455 class MoveAndUpdateClosure: public ParMarkBitMapClosure {
1456 public:
1457 inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
1458 ObjectStartArray* start_array,
1459 HeapWord* destination, size_t words);
1460
1461 // Accessors.
1462 HeapWord* destination() const { return _destination; }
1463
1464 // If the object will fit (size <= words_remaining()), copy it to the current
1465 // destination, update the interior oops and the start array and return either
1466 // full (if the closure is full) or incomplete. If the object will not fit,
1467 // return would_overflow.
1468 virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1469
1470 // Copy enough words to fill this closure, starting at source(). Interior
1471 // oops and the start array are not updated. Return full.
1472 IterationStatus copy_until_full();
1473
1474 // Copy enough words to fill this closure or to the end of an object,
1475 // whichever is smaller, starting at source(). Interior oops and the start
1476 // array are not updated.
1477 void copy_partial_obj();
1478
1479 protected:
1480 // Update variables to indicate that word_count words were processed.
1481 inline void update_state(size_t word_count);
1482
1483 protected:
1484 ObjectStartArray* const _start_array;
1485 HeapWord* _destination; // Next addr to be written.
1486 };
1487
1488 inline
1489 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
1490 ParCompactionManager* cm,
1491 ObjectStartArray* start_array,
1492 HeapWord* destination,
1493 size_t words) :
1494 ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)
1495 {
1496 _destination = destination;
1497 }
1498
1499 inline void MoveAndUpdateClosure::update_state(size_t words)
1500 {
1501 decrement_words_remaining(words);
1502 _source += words;
1503 _destination += words;
1504 }
1505
1506 class UpdateOnlyClosure: public ParMarkBitMapClosure {
1507 private:
1508 const PSParallelCompact::SpaceId _space_id;
1509 ObjectStartArray* const _start_array;
1510
1511 public:
1512 UpdateOnlyClosure(ParMarkBitMap* mbm,
1513 ParCompactionManager* cm,
1514 PSParallelCompact::SpaceId space_id);
1515
1516 // Update the object.
1517 virtual IterationStatus do_addr(HeapWord* addr, size_t words);
1518
1519 inline void do_addr(HeapWord* addr);
1520 };
1521
1522 inline void UpdateOnlyClosure::do_addr(HeapWord* addr)
1523 {
1524 _start_array->allocate_block(addr);
1525 oop(addr)->update_contents(compaction_manager());
1526 }
1527
1528 class FillClosure: public ParMarkBitMapClosure
1529 {
1530 public:
1531 FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
1532 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
1533 _start_array(PSParallelCompact::start_array(space_id))
1534 {
1535 assert(space_id == PSParallelCompact::old_space_id,
1536 "cannot use FillClosure in the young gen");
1537 }
1538
1539 virtual IterationStatus do_addr(HeapWord* addr, size_t size) {
1540 CollectedHeap::fill_with_objects(addr, size);
1541 HeapWord* const end = addr + size;
1542 do {
1543 _start_array->allocate_block(addr);
1544 addr += oop(addr)->size();
1545 } while (addr < end);
1546 return ParMarkBitMap::incomplete;
1547 }
1548
1549 private:
1550 ObjectStartArray* const _start_array;
1551 };
1552
1553 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP