1 /*
2 * Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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24
25 #ifndef SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP
26 #define SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP
27
28 #include "gc/parallel/mutableSpace.hpp"
29 #include "gc/parallel/objectStartArray.hpp"
30 #include "gc/parallel/parMarkBitMap.hpp"
31 #include "gc/parallel/parallelScavengeHeap.hpp"
32 #include "gc/shared/collectedHeap.hpp"
33 #include "gc/shared/collectorCounters.hpp"
34 #include "oops/oop.hpp"
35 #include "runtime/atomic.hpp"
36 #include "runtime/orderAccess.hpp"
37
38 class ParallelScavengeHeap;
39 class PSAdaptiveSizePolicy;
40 class PSYoungGen;
41 class PSOldGen;
42 class ParCompactionManager;
43 class PSParallelCompact;
44 class MoveAndUpdateClosure;
45 class RefProcTaskExecutor;
46 class ParallelOldTracer;
47 class STWGCTimer;
48
49 // The SplitInfo class holds the information needed to 'split' a source region
50 // so that the live data can be copied to two destination *spaces*. Normally,
51 // all the live data in a region is copied to a single destination space (e.g.,
52 // everything live in a region in eden is copied entirely into the old gen).
53 // However, when the heap is nearly full, all the live data in eden may not fit
54 // into the old gen. Copying only some of the regions from eden to old gen
55 // requires finding a region that does not contain a partial object (i.e., no
56 // live object crosses the region boundary) somewhere near the last object that
57 // does fit into the old gen. Since it's not always possible to find such a
58 // region, splitting is necessary for predictable behavior.
59 //
60 // A region is always split at the end of the partial object. This avoids
61 // additional tests when calculating the new location of a pointer, which is a
62 // very hot code path. The partial object and everything to its left will be
63 // copied to another space (call it dest_space_1). The live data to the right
64 // of the partial object will be copied either within the space itself, or to a
65 // different destination space (distinct from dest_space_1).
66 //
67 // Split points are identified during the summary phase, when region
68 // destinations are computed: data about the split, including the
69 // partial_object_size, is recorded in a SplitInfo record and the
70 // partial_object_size field in the summary data is set to zero. The zeroing is
71 // possible (and necessary) since the partial object will move to a different
72 // destination space than anything to its right, thus the partial object should
73 // not affect the locations of any objects to its right.
74 //
75 // The recorded data is used during the compaction phase, but only rarely: when
76 // the partial object on the split region will be copied across a destination
77 // region boundary. This test is made once each time a region is filled, and is
78 // a simple address comparison, so the overhead is negligible (see
79 // PSParallelCompact::first_src_addr()).
80 //
81 // Notes:
82 //
83 // Only regions with partial objects are split; a region without a partial
84 // object does not need any extra bookkeeping.
85 //
86 // At most one region is split per space, so the amount of data required is
87 // constant.
88 //
89 // A region is split only when the destination space would overflow. Once that
90 // happens, the destination space is abandoned and no other data (even from
91 // other source spaces) is targeted to that destination space. Abandoning the
92 // destination space may leave a somewhat large unused area at the end, if a
93 // large object caused the overflow.
94 //
95 // Future work:
96 //
97 // More bookkeeping would be required to continue to use the destination space.
98 // The most general solution would allow data from regions in two different
99 // source spaces to be "joined" in a single destination region. At the very
100 // least, additional code would be required in next_src_region() to detect the
101 // join and skip to an out-of-order source region. If the join region was also
102 // the last destination region to which a split region was copied (the most
103 // likely case), then additional work would be needed to get fill_region() to
104 // stop iteration and switch to a new source region at the right point. Basic
105 // idea would be to use a fake value for the top of the source space. It is
106 // doable, if a bit tricky.
107 //
108 // A simpler (but less general) solution would fill the remainder of the
109 // destination region with a dummy object and continue filling the next
110 // destination region.
111
112 class SplitInfo
113 {
114 public:
115 // Return true if this split info is valid (i.e., if a split has been
116 // recorded). The very first region cannot have a partial object and thus is
117 // never split, so 0 is the 'invalid' value.
118 bool is_valid() const { return _src_region_idx > 0; }
119
120 // Return true if this split holds data for the specified source region.
121 inline bool is_split(size_t source_region) const;
122
123 // The index of the split region, the size of the partial object on that
124 // region and the destination of the partial object.
125 size_t src_region_idx() const { return _src_region_idx; }
126 size_t partial_obj_size() const { return _partial_obj_size; }
127 HeapWord* destination() const { return _destination; }
128
129 // The destination count of the partial object referenced by this split
130 // (either 1 or 2). This must be added to the destination count of the
131 // remainder of the source region.
132 unsigned int destination_count() const { return _destination_count; }
133
134 // If a word within the partial object will be written to the first word of a
135 // destination region, this is the address of the destination region;
136 // otherwise this is NULL.
137 HeapWord* dest_region_addr() const { return _dest_region_addr; }
138
139 // If a word within the partial object will be written to the first word of a
140 // destination region, this is the address of that word within the partial
141 // object; otherwise this is NULL.
142 HeapWord* first_src_addr() const { return _first_src_addr; }
143
144 // Record the data necessary to split the region src_region_idx.
145 void record(size_t src_region_idx, size_t partial_obj_size,
146 HeapWord* destination);
147
148 void clear();
149
150 DEBUG_ONLY(void verify_clear();)
151
152 private:
153 size_t _src_region_idx;
154 size_t _partial_obj_size;
155 HeapWord* _destination;
156 unsigned int _destination_count;
157 HeapWord* _dest_region_addr;
158 HeapWord* _first_src_addr;
159 };
160
161 inline bool SplitInfo::is_split(size_t region_idx) const
162 {
163 return _src_region_idx == region_idx && is_valid();
164 }
165
166 class SpaceInfo
167 {
168 public:
169 MutableSpace* space() const { return _space; }
170
171 // Where the free space will start after the collection. Valid only after the
172 // summary phase completes.
173 HeapWord* new_top() const { return _new_top; }
174
175 // Allows new_top to be set.
176 HeapWord** new_top_addr() { return &_new_top; }
177
178 // Where the smallest allowable dense prefix ends (used only for perm gen).
179 HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
180
181 // Where the dense prefix ends, or the compacted region begins.
182 HeapWord* dense_prefix() const { return _dense_prefix; }
183
184 // The start array for the (generation containing the) space, or NULL if there
185 // is no start array.
186 ObjectStartArray* start_array() const { return _start_array; }
187
188 SplitInfo& split_info() { return _split_info; }
189
190 void set_space(MutableSpace* s) { _space = s; }
191 void set_new_top(HeapWord* addr) { _new_top = addr; }
192 void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
193 void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; }
194 void set_start_array(ObjectStartArray* s) { _start_array = s; }
195
196 void publish_new_top() const { _space->set_top(_new_top); }
197
198 private:
199 MutableSpace* _space;
200 HeapWord* _new_top;
201 HeapWord* _min_dense_prefix;
202 HeapWord* _dense_prefix;
203 ObjectStartArray* _start_array;
204 SplitInfo _split_info;
205 };
206
207 class ParallelCompactData
208 {
209 public:
210 // Sizes are in HeapWords, unless indicated otherwise.
211 static const size_t Log2RegionSize;
212 static const size_t RegionSize;
213 static const size_t RegionSizeBytes;
214
215 // Mask for the bits in a size_t to get an offset within a region.
216 static const size_t RegionSizeOffsetMask;
217 // Mask for the bits in a pointer to get an offset within a region.
218 static const size_t RegionAddrOffsetMask;
219 // Mask for the bits in a pointer to get the address of the start of a region.
220 static const size_t RegionAddrMask;
221
222 static const size_t Log2BlockSize;
223 static const size_t BlockSize;
224 static const size_t BlockSizeBytes;
225
226 static const size_t BlockSizeOffsetMask;
227 static const size_t BlockAddrOffsetMask;
228 static const size_t BlockAddrMask;
229
230 static const size_t BlocksPerRegion;
231 static const size_t Log2BlocksPerRegion;
232
233 class RegionData
234 {
235 public:
236 // Destination address of the region.
237 HeapWord* destination() const { return _destination; }
238
239 // The first region containing data destined for this region.
240 size_t source_region() const { return _source_region; }
241
242 // Reuse _source_region to store the corresponding shadow region index
243 size_t shadow_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_shadow_region(size_t region) { _source_region = region; }
314 void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
315 void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
316 void set_partial_obj_size(size_t words) {
317 _partial_obj_size = (region_sz_t) words;
318 }
319 inline void set_blocks_filled();
320
321 inline void set_destination_count(uint count);
322 inline void set_live_obj_size(size_t words);
323 inline void set_data_location(HeapWord* addr);
324 inline void set_completed();
325 inline bool claim_unsafe();
326
327 // These are atomic.
328 inline void add_live_obj(size_t words);
329 inline void set_highest_ref(HeapWord* addr);
330 inline void decrement_destination_count();
331 inline bool claim();
332
333 // Possible values of _shadow_state, and transition is as follows
334 // Normal Path:
335 // UnusedRegion -> mark_normal() -> NormalRegion
336 // Shadow Path:
337 // UnusedRegion -> mark_shadow() -> ShadowRegion ->
338 // mark_filled() -> FilledShadow -> mark_copied() -> CopiedShadow
339 static const int UnusedRegion = 0; // The region is not collected yet
340 static const int ShadowRegion = 1; // Stolen by an idle thread, and a shadow region is created for it
341 static const int FilledShadow = 2; // Its shadow region has been filled and ready to be copied back
342 static const int CopiedShadow = 3; // The data of the shadow region has been copied back
343 static const int NormalRegion = 4; // The region will be collected by the original parallel algorithm
344
345 // Mark the current region as normal or shadow to enter different processing paths
346 inline bool mark_normal();
347 inline bool mark_shadow();
348 // Mark the shadow region as filled and ready to be copied back
349 inline void mark_filled();
350 // Mark the shadow region as copied back to avoid double copying.
351 inline bool mark_copied();
352 // Special case: see the comment in PSParallelCompact::fill_and_update_shadow_region.
353 // Return to the normal path here
354 inline void shadow_to_normal();
355
356
357 int shadow_state() { return _shadow_state; }
358
359 private:
360 // The type used to represent object sizes within a region.
361 typedef uint region_sz_t;
362
363 // Constants for manipulating the _dc_and_los field, which holds both the
364 // destination count and live obj size. The live obj size lives at the
365 // least significant end so no masking is necessary when adding.
366 static const region_sz_t dc_shift; // Shift amount.
367 static const region_sz_t dc_mask; // Mask for destination count.
368 static const region_sz_t dc_one; // 1, shifted appropriately.
369 static const region_sz_t dc_claimed; // Region has been claimed.
370 static const region_sz_t dc_completed; // Region has been completed.
371 static const region_sz_t los_mask; // Mask for live obj size.
372
373 HeapWord* _destination;
374 size_t _source_region;
375 HeapWord* _partial_obj_addr;
376 region_sz_t _partial_obj_size;
377 region_sz_t volatile _dc_and_los;
378 bool volatile _blocks_filled;
379 int volatile _shadow_state;
380
381 #ifdef ASSERT
382 size_t _blocks_filled_count; // Number of block table fills.
383
384 // These enable optimizations that are only partially implemented. Use
385 // debug builds to prevent the code fragments from breaking.
386 HeapWord* _data_location;
387 HeapWord* _highest_ref;
388 #endif // #ifdef ASSERT
389
390 #ifdef ASSERT
391 public:
392 uint _pushed; // 0 until region is pushed onto a stack
393 private:
394 #endif
395 };
396
397 // "Blocks" allow shorter sections of the bitmap to be searched. Each Block
398 // holds an offset, which is the amount of live data in the Region to the left
399 // of the first live object that starts in the Block.
400 class BlockData
401 {
402 public:
403 typedef unsigned short int blk_ofs_t;
404
405 blk_ofs_t offset() const { return _offset; }
406 void set_offset(size_t val) { _offset = (blk_ofs_t)val; }
407
408 private:
409 blk_ofs_t _offset;
410 };
411
412 public:
413 ParallelCompactData();
414 bool initialize(MemRegion covered_region);
415
416 size_t region_count() const { return _region_count; }
417 size_t reserved_byte_size() const { return _reserved_byte_size; }
418
419 // Convert region indices to/from RegionData pointers.
420 inline RegionData* region(size_t region_idx) const;
421 inline size_t region(const RegionData* const region_ptr) const;
422
423 size_t block_count() const { return _block_count; }
424 inline BlockData* block(size_t block_idx) const;
425 inline size_t block(const BlockData* block_ptr) const;
426
427 void add_obj(HeapWord* addr, size_t len);
428 void add_obj(oop p, size_t len) { add_obj(cast_from_oop<HeapWord*>(p), len); }
429
430 // Fill in the regions covering [beg, end) so that no data moves; i.e., the
431 // destination of region n is simply the start of region n. The argument beg
432 // must be region-aligned; end need not be.
433 void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
434
435 HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info,
436 HeapWord* destination, HeapWord* target_end,
437 HeapWord** target_next);
438 bool summarize(SplitInfo& split_info,
439 HeapWord* source_beg, HeapWord* source_end,
440 HeapWord** source_next,
441 HeapWord* target_beg, HeapWord* target_end,
442 HeapWord** target_next);
443
444 void clear();
445 void clear_range(size_t beg_region, size_t end_region);
446 void clear_range(HeapWord* beg, HeapWord* end) {
447 clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
448 }
449
450 // Return the number of words between addr and the start of the region
451 // containing addr.
452 inline size_t region_offset(const HeapWord* addr) const;
453
454 // Convert addresses to/from a region index or region pointer.
455 inline size_t addr_to_region_idx(const HeapWord* addr) const;
456 inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
457 inline HeapWord* region_to_addr(size_t region) const;
458 inline HeapWord* region_to_addr(size_t region, size_t offset) const;
459 inline HeapWord* region_to_addr(const RegionData* region) const;
460
461 inline HeapWord* region_align_down(HeapWord* addr) const;
462 inline HeapWord* region_align_up(HeapWord* addr) const;
463 inline bool is_region_aligned(HeapWord* addr) const;
464
465 // Analogous to region_offset() for blocks.
466 size_t block_offset(const HeapWord* addr) const;
467 size_t addr_to_block_idx(const HeapWord* addr) const;
468 size_t addr_to_block_idx(const oop obj) const {
469 return addr_to_block_idx(cast_from_oop<HeapWord*>(obj));
470 }
471 inline BlockData* addr_to_block_ptr(const HeapWord* addr) const;
472 inline HeapWord* block_to_addr(size_t block) const;
473 inline size_t region_to_block_idx(size_t region) const;
474
475 inline HeapWord* block_align_down(HeapWord* addr) const;
476 inline HeapWord* block_align_up(HeapWord* addr) const;
477 inline bool is_block_aligned(HeapWord* addr) const;
478
479 // Return the address one past the end of the partial object.
480 HeapWord* partial_obj_end(size_t region_idx) const;
481
482 // Return the location of the object after compaction.
483 HeapWord* calc_new_pointer(HeapWord* addr, ParCompactionManager* cm);
484
485 HeapWord* calc_new_pointer(oop p, ParCompactionManager* cm) {
486 return calc_new_pointer(cast_from_oop<HeapWord*>(p), cm);
487 }
488
489 #ifdef ASSERT
490 void verify_clear(const PSVirtualSpace* vspace);
491 void verify_clear();
492 #endif // #ifdef ASSERT
493
494 private:
495 bool initialize_block_data();
496 bool initialize_region_data(size_t region_size);
497 PSVirtualSpace* create_vspace(size_t count, size_t element_size);
498
499 private:
500 HeapWord* _region_start;
501 #ifdef ASSERT
502 HeapWord* _region_end;
503 #endif // #ifdef ASSERT
504
505 PSVirtualSpace* _region_vspace;
506 size_t _reserved_byte_size;
507 RegionData* _region_data;
508 size_t _region_count;
509
510 PSVirtualSpace* _block_vspace;
511 BlockData* _block_data;
512 size_t _block_count;
513 };
514
515 inline uint
516 ParallelCompactData::RegionData::destination_count_raw() const
517 {
518 return _dc_and_los & dc_mask;
519 }
520
521 inline uint
522 ParallelCompactData::RegionData::destination_count() const
523 {
524 return destination_count_raw() >> dc_shift;
525 }
526
527 inline bool
528 ParallelCompactData::RegionData::blocks_filled() const
529 {
530 bool result = _blocks_filled;
531 OrderAccess::acquire();
532 return result;
533 }
534
535 #ifdef ASSERT
536 inline size_t
537 ParallelCompactData::RegionData::blocks_filled_count() const
538 {
539 return _blocks_filled_count;
540 }
541 #endif // #ifdef ASSERT
542
543 inline void
544 ParallelCompactData::RegionData::set_blocks_filled()
545 {
546 OrderAccess::release();
547 _blocks_filled = true;
548 // Debug builds count the number of times the table was filled.
549 DEBUG_ONLY(Atomic::inc(&_blocks_filled_count));
550 }
551
552 inline void
553 ParallelCompactData::RegionData::set_destination_count(uint count)
554 {
555 assert(count <= (dc_completed >> dc_shift), "count too large");
556 const region_sz_t live_sz = (region_sz_t) live_obj_size();
557 _dc_and_los = (count << dc_shift) | live_sz;
558 }
559
560 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
561 {
562 assert(words <= los_mask, "would overflow");
563 _dc_and_los = destination_count_raw() | (region_sz_t)words;
564 }
565
566 inline void ParallelCompactData::RegionData::decrement_destination_count()
567 {
568 assert(_dc_and_los < dc_claimed, "already claimed");
569 assert(_dc_and_los >= dc_one, "count would go negative");
570 Atomic::add(&_dc_and_los, dc_mask);
571 }
572
573 inline HeapWord* ParallelCompactData::RegionData::data_location() const
574 {
575 DEBUG_ONLY(return _data_location;)
576 NOT_DEBUG(return NULL;)
577 }
578
579 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
580 {
581 DEBUG_ONLY(return _highest_ref;)
582 NOT_DEBUG(return NULL;)
583 }
584
585 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
586 {
587 DEBUG_ONLY(_data_location = addr;)
588 }
589
590 inline void ParallelCompactData::RegionData::set_completed()
591 {
592 assert(claimed(), "must be claimed first");
593 _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
594 }
595
596 // MT-unsafe claiming of a region. Should only be used during single threaded
597 // execution.
598 inline bool ParallelCompactData::RegionData::claim_unsafe()
599 {
600 if (available()) {
601 _dc_and_los |= dc_claimed;
602 return true;
603 }
604 return false;
605 }
606
607 inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
608 {
609 assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
610 Atomic::add(&_dc_and_los, static_cast<region_sz_t>(words));
611 }
612
613 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
614 {
615 #ifdef ASSERT
616 HeapWord* tmp = _highest_ref;
617 while (addr > tmp) {
618 tmp = Atomic::cmpxchg(&_highest_ref, tmp, addr);
619 }
620 #endif // #ifdef ASSERT
621 }
622
623 inline bool ParallelCompactData::RegionData::claim()
624 {
625 const region_sz_t los = static_cast<region_sz_t>(live_obj_size());
626 const region_sz_t old = Atomic::cmpxchg(&_dc_and_los, los, dc_claimed | los);
627 return old == los;
628 }
629
630 inline bool ParallelCompactData::RegionData::mark_normal() {
631 return Atomic::cmpxchg(&_shadow_state, UnusedRegion, NormalRegion) == UnusedRegion;
632 }
633
634 inline bool ParallelCompactData::RegionData::mark_shadow() {
635 if (_shadow_state != UnusedRegion) return false;
636 return Atomic::cmpxchg(&_shadow_state, UnusedRegion, ShadowRegion) == UnusedRegion;
637 }
638
639 inline void ParallelCompactData::RegionData::mark_filled() {
640 int old = Atomic::cmpxchg(&_shadow_state, ShadowRegion, FilledShadow);
641 assert(old == ShadowRegion, "Fail to mark the region as filled");
642 }
643
644 inline bool ParallelCompactData::RegionData::mark_copied() {
645 return Atomic::cmpxchg(&_shadow_state, FilledShadow, CopiedShadow) == FilledShadow;
646 }
647
648 void ParallelCompactData::RegionData::shadow_to_normal() {
649 int old = Atomic::cmpxchg(&_shadow_state, ShadowRegion, NormalRegion);
650 assert(old == ShadowRegion, "Fail to mark the region as finish");
651 }
652
653 inline ParallelCompactData::RegionData*
654 ParallelCompactData::region(size_t region_idx) const
655 {
656 assert(region_idx <= region_count(), "bad arg");
657 return _region_data + region_idx;
658 }
659
660 inline size_t
661 ParallelCompactData::region(const RegionData* const region_ptr) const
662 {
663 assert(region_ptr >= _region_data, "bad arg");
664 assert(region_ptr <= _region_data + region_count(), "bad arg");
665 return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
666 }
667
668 inline ParallelCompactData::BlockData*
669 ParallelCompactData::block(size_t n) const {
670 assert(n < block_count(), "bad arg");
671 return _block_data + n;
672 }
673
674 inline size_t
675 ParallelCompactData::region_offset(const HeapWord* addr) const
676 {
677 assert(addr >= _region_start, "bad addr");
678 assert(addr <= _region_end, "bad addr");
679 return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
680 }
681
682 inline size_t
683 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
684 {
685 assert(addr >= _region_start, "bad addr " PTR_FORMAT " _region_start " PTR_FORMAT, p2i(addr), p2i(_region_start));
686 assert(addr <= _region_end, "bad addr " PTR_FORMAT " _region_end " PTR_FORMAT, p2i(addr), p2i(_region_end));
687 return pointer_delta(addr, _region_start) >> Log2RegionSize;
688 }
689
690 inline ParallelCompactData::RegionData*
691 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
692 {
693 return region(addr_to_region_idx(addr));
694 }
695
696 inline HeapWord*
697 ParallelCompactData::region_to_addr(size_t region) const
698 {
699 assert(region <= _region_count, "region out of range");
700 return _region_start + (region << Log2RegionSize);
701 }
702
703 inline HeapWord*
704 ParallelCompactData::region_to_addr(const RegionData* region) const
705 {
706 return region_to_addr(pointer_delta(region, _region_data,
707 sizeof(RegionData)));
708 }
709
710 inline HeapWord*
711 ParallelCompactData::region_to_addr(size_t region, size_t offset) const
712 {
713 assert(region <= _region_count, "region out of range");
714 assert(offset < RegionSize, "offset too big"); // This may be too strict.
715 return region_to_addr(region) + offset;
716 }
717
718 inline HeapWord*
719 ParallelCompactData::region_align_down(HeapWord* addr) const
720 {
721 assert(addr >= _region_start, "bad addr");
722 assert(addr < _region_end + RegionSize, "bad addr");
723 return (HeapWord*)(size_t(addr) & RegionAddrMask);
724 }
725
726 inline HeapWord*
727 ParallelCompactData::region_align_up(HeapWord* addr) const
728 {
729 assert(addr >= _region_start, "bad addr");
730 assert(addr <= _region_end, "bad addr");
731 return region_align_down(addr + RegionSizeOffsetMask);
732 }
733
734 inline bool
735 ParallelCompactData::is_region_aligned(HeapWord* addr) const
736 {
737 return region_offset(addr) == 0;
738 }
739
740 inline size_t
741 ParallelCompactData::block_offset(const HeapWord* addr) const
742 {
743 assert(addr >= _region_start, "bad addr");
744 assert(addr <= _region_end, "bad addr");
745 return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize;
746 }
747
748 inline size_t
749 ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const
750 {
751 assert(addr >= _region_start, "bad addr");
752 assert(addr <= _region_end, "bad addr");
753 return pointer_delta(addr, _region_start) >> Log2BlockSize;
754 }
755
756 inline ParallelCompactData::BlockData*
757 ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const
758 {
759 return block(addr_to_block_idx(addr));
760 }
761
762 inline HeapWord*
763 ParallelCompactData::block_to_addr(size_t block) const
764 {
765 assert(block < _block_count, "block out of range");
766 return _region_start + (block << Log2BlockSize);
767 }
768
769 inline size_t
770 ParallelCompactData::region_to_block_idx(size_t region) const
771 {
772 return region << Log2BlocksPerRegion;
773 }
774
775 inline HeapWord*
776 ParallelCompactData::block_align_down(HeapWord* addr) const
777 {
778 assert(addr >= _region_start, "bad addr");
779 assert(addr < _region_end + RegionSize, "bad addr");
780 return (HeapWord*)(size_t(addr) & BlockAddrMask);
781 }
782
783 inline HeapWord*
784 ParallelCompactData::block_align_up(HeapWord* addr) const
785 {
786 assert(addr >= _region_start, "bad addr");
787 assert(addr <= _region_end, "bad addr");
788 return block_align_down(addr + BlockSizeOffsetMask);
789 }
790
791 inline bool
792 ParallelCompactData::is_block_aligned(HeapWord* addr) const
793 {
794 return block_offset(addr) == 0;
795 }
796
797 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
798 // do_addr() method.
799 //
800 // The closure is initialized with the number of heap words to process
801 // (words_remaining()), and becomes 'full' when it reaches 0. The do_addr()
802 // methods in subclasses should update the total as words are processed. Since
803 // only one subclass actually uses this mechanism to terminate iteration, the
804 // default initial value is > 0. The implementation is here and not in the
805 // single subclass that uses it to avoid making is_full() virtual, and thus
806 // adding a virtual call per live object.
807
808 class ParMarkBitMapClosure: public StackObj {
809 public:
810 typedef ParMarkBitMap::idx_t idx_t;
811 typedef ParMarkBitMap::IterationStatus IterationStatus;
812
813 public:
814 inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
815 size_t words = max_uintx);
816
817 inline ParCompactionManager* compaction_manager() const;
818 inline ParMarkBitMap* bitmap() const;
819 inline size_t words_remaining() const;
820 inline bool is_full() const;
821 inline HeapWord* source() const;
822
823 inline void set_source(HeapWord* addr);
824
825 virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
826
827 protected:
828 inline void decrement_words_remaining(size_t words);
829
830 private:
831 ParMarkBitMap* const _bitmap;
832 ParCompactionManager* const _compaction_manager;
833 DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger.
834 size_t _words_remaining; // Words left to copy.
835
836 protected:
837 HeapWord* _source; // Next addr that would be read.
838 };
839
840 inline
841 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
842 ParCompactionManager* cm,
843 size_t words):
844 _bitmap(bitmap), _compaction_manager(cm)
845 #ifdef ASSERT
846 , _initial_words_remaining(words)
847 #endif
848 {
849 _words_remaining = words;
850 _source = NULL;
851 }
852
853 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
854 return _compaction_manager;
855 }
856
857 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
858 return _bitmap;
859 }
860
861 inline size_t ParMarkBitMapClosure::words_remaining() const {
862 return _words_remaining;
863 }
864
865 inline bool ParMarkBitMapClosure::is_full() const {
866 return words_remaining() == 0;
867 }
868
869 inline HeapWord* ParMarkBitMapClosure::source() const {
870 return _source;
871 }
872
873 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
874 _source = addr;
875 }
876
877 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
878 assert(_words_remaining >= words, "processed too many words");
879 _words_remaining -= words;
880 }
881
882 // The Parallel collector is a stop-the-world garbage collector that
883 // does parts of the collection using parallel threads. The collection includes
884 // the tenured generation and the young generation.
885 //
886 // There are four phases of the collection.
887 //
888 // - marking phase
889 // - summary phase
890 // - compacting phase
891 // - clean up phase
892 //
893 // Roughly speaking these phases correspond, respectively, to
894 // - mark all the live objects
895 // - calculate the destination of each object at the end of the collection
896 // - move the objects to their destination
897 // - update some references and reinitialize some variables
898 //
899 // These three phases are invoked in PSParallelCompact::invoke_no_policy(). The
900 // marking phase is implemented in PSParallelCompact::marking_phase() and does a
901 // complete marking of the heap. The summary phase is implemented in
902 // PSParallelCompact::summary_phase(). The move and update phase is implemented
903 // in PSParallelCompact::compact().
904 //
905 // A space that is being collected is divided into regions and with each region
906 // is associated an object of type ParallelCompactData. Each region is of a
907 // fixed size and typically will contain more than 1 object and may have parts
908 // of objects at the front and back of the region.
909 //
910 // region -----+---------------------+----------
911 // objects covered [ AAA )[ BBB )[ CCC )[ DDD )
912 //
913 // The marking phase does a complete marking of all live objects in the heap.
914 // The marking also compiles the size of the data for all live objects covered
915 // by the region. This size includes the part of any live object spanning onto
916 // the region (part of AAA if it is live) from the front, all live objects
917 // contained in the region (BBB and/or CCC if they are live), and the part of
918 // any live objects covered by the region that extends off the region (part of
919 // DDD if it is live). The marking phase uses multiple GC threads and marking
920 // is done in a bit array of type ParMarkBitMap. The marking of the bit map is
921 // done atomically as is the accumulation of the size of the live objects
922 // covered by a region.
923 //
924 // The summary phase calculates the total live data to the left of each region
925 // XXX. Based on that total and the bottom of the space, it can calculate the
926 // starting location of the live data in XXX. The summary phase calculates for
927 // each region XXX quantities such as
928 //
929 // - the amount of live data at the beginning of a region from an object
930 // entering the region.
931 // - the location of the first live data on the region
932 // - a count of the number of regions receiving live data from XXX.
933 //
934 // See ParallelCompactData for precise details. The summary phase also
935 // calculates the dense prefix for the compaction. The dense prefix is a
936 // portion at the beginning of the space that is not moved. The objects in the
937 // dense prefix do need to have their object references updated. See method
938 // summarize_dense_prefix().
939 //
940 // The summary phase is done using 1 GC thread.
941 //
942 // The compaction phase moves objects to their new location and updates all
943 // references in the object.
944 //
945 // A current exception is that objects that cross a region boundary are moved
946 // but do not have their references updated. References are not updated because
947 // it cannot easily be determined if the klass pointer KKK for the object AAA
948 // has been updated. KKK likely resides in a region to the left of the region
949 // containing AAA. These AAA's have there references updated at the end in a
950 // clean up phase. See the method PSParallelCompact::update_deferred_objects().
951 // An alternate strategy is being investigated for this deferral of updating.
952 //
953 // Compaction is done on a region basis. A region that is ready to be filled is
954 // put on a ready list and GC threads take region off the list and fill them. A
955 // region is ready to be filled if it empty of live objects. Such a region may
956 // have been initially empty (only contained dead objects) or may have had all
957 // its live objects copied out already. A region that compacts into itself is
958 // also ready for filling. The ready list is initially filled with empty
959 // regions and regions compacting into themselves. There is always at least 1
960 // region that can be put on the ready list. The regions are atomically added
961 // and removed from the ready list.
962
963 class TaskQueue;
964
965 class PSParallelCompact : AllStatic {
966 public:
967 // Convenient access to type names.
968 typedef ParMarkBitMap::idx_t idx_t;
969 typedef ParallelCompactData::RegionData RegionData;
970 typedef ParallelCompactData::BlockData BlockData;
971
972 typedef enum {
973 old_space_id, eden_space_id,
974 from_space_id, to_space_id, last_space_id
975 } SpaceId;
976
977 struct UpdateDensePrefixTask : public CHeapObj<mtGC> {
978 SpaceId _space_id;
979 size_t _region_index_start;
980 size_t _region_index_end;
981
982 UpdateDensePrefixTask() :
983 _space_id(SpaceId(0)),
984 _region_index_start(0),
985 _region_index_end(0) {}
986
987 UpdateDensePrefixTask(SpaceId space_id,
988 size_t region_index_start,
989 size_t region_index_end) :
990 _space_id(space_id),
991 _region_index_start(region_index_start),
992 _region_index_end(region_index_end) {}
993 };
994
995 public:
996 // Inline closure decls
997 //
998 class IsAliveClosure: public BoolObjectClosure {
999 public:
1000 virtual bool do_object_b(oop p);
1001 };
1002
1003 friend class RefProcTaskProxy;
1004 friend class PSParallelCompactTest;
1005
1006 private:
1007 static STWGCTimer _gc_timer;
1008 static ParallelOldTracer _gc_tracer;
1009 static elapsedTimer _accumulated_time;
1010 static unsigned int _total_invocations;
1011 static unsigned int _maximum_compaction_gc_num;
1012 static jlong _time_of_last_gc; // ms
1013 static CollectorCounters* _counters;
1014 static ParMarkBitMap _mark_bitmap;
1015 static ParallelCompactData _summary_data;
1016 static IsAliveClosure _is_alive_closure;
1017 static SpaceInfo _space_info[last_space_id];
1018
1019 // Reference processing (used in ...follow_contents)
1020 static SpanSubjectToDiscoveryClosure _span_based_discoverer;
1021 static ReferenceProcessor* _ref_processor;
1022
1023 // Values computed at initialization and used by dead_wood_limiter().
1024 static double _dwl_mean;
1025 static double _dwl_std_dev;
1026 static double _dwl_first_term;
1027 static double _dwl_adjustment;
1028 #ifdef ASSERT
1029 static bool _dwl_initialized;
1030 #endif // #ifdef ASSERT
1031
1032 public:
1033 static ParallelOldTracer* gc_tracer() { return &_gc_tracer; }
1034
1035 private:
1036
1037 static void initialize_space_info();
1038
1039 // Clear the marking bitmap and summary data that cover the specified space.
1040 static void clear_data_covering_space(SpaceId id);
1041
1042 static void pre_compact();
1043 static void post_compact();
1044
1045 // Mark live objects
1046 static void marking_phase(ParCompactionManager* cm,
1047 bool maximum_heap_compaction,
1048 ParallelOldTracer *gc_tracer);
1049
1050 // Compute the dense prefix for the designated space. This is an experimental
1051 // implementation currently not used in production.
1052 static HeapWord* compute_dense_prefix_via_density(const SpaceId id,
1053 bool maximum_compaction);
1054
1055 // Methods used to compute the dense prefix.
1056
1057 // Compute the value of the normal distribution at x = density. The mean and
1058 // standard deviation are values saved by initialize_dead_wood_limiter().
1059 static inline double normal_distribution(double density);
1060
1061 // Initialize the static vars used by dead_wood_limiter().
1062 static void initialize_dead_wood_limiter();
1063
1064 // Return the percentage of space that can be treated as "dead wood" (i.e.,
1065 // not reclaimed).
1066 static double dead_wood_limiter(double density, size_t min_percent);
1067
1068 // Find the first (left-most) region in the range [beg, end) that has at least
1069 // dead_words of dead space to the left. The argument beg must be the first
1070 // region in the space that is not completely live.
1071 static RegionData* dead_wood_limit_region(const RegionData* beg,
1072 const RegionData* end,
1073 size_t dead_words);
1074
1075 // Return a pointer to the first region in the range [beg, end) that is not
1076 // completely full.
1077 static RegionData* first_dead_space_region(const RegionData* beg,
1078 const RegionData* end);
1079
1080 // Return a value indicating the benefit or 'yield' if the compacted region
1081 // were to start (or equivalently if the dense prefix were to end) at the
1082 // candidate region. Higher values are better.
1083 //
1084 // The value is based on the amount of space reclaimed vs. the costs of (a)
1085 // updating references in the dense prefix plus (b) copying objects and
1086 // updating references in the compacted region.
1087 static inline double reclaimed_ratio(const RegionData* const candidate,
1088 HeapWord* const bottom,
1089 HeapWord* const top,
1090 HeapWord* const new_top);
1091
1092 // Compute the dense prefix for the designated space.
1093 static HeapWord* compute_dense_prefix(const SpaceId id,
1094 bool maximum_compaction);
1095
1096 // Return true if dead space crosses onto the specified Region; bit must be
1097 // the bit index corresponding to the first word of the Region.
1098 static inline bool dead_space_crosses_boundary(const RegionData* region,
1099 idx_t bit);
1100
1101 // Summary phase utility routine to fill dead space (if any) at the dense
1102 // prefix boundary. Should only be called if the the dense prefix is
1103 // non-empty.
1104 static void fill_dense_prefix_end(SpaceId id);
1105
1106 static void summarize_spaces_quick();
1107 static void summarize_space(SpaceId id, bool maximum_compaction);
1108 static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);
1109
1110 // Adjust addresses in roots. Does not adjust addresses in heap.
1111 static void adjust_roots(ParCompactionManager* cm);
1112
1113 DEBUG_ONLY(static void write_block_fill_histogram();)
1114
1115 // Move objects to new locations.
1116 static void compact_perm(ParCompactionManager* cm);
1117 static void compact();
1118
1119 // Add available regions to the stack and draining tasks to the task queue.
1120 static void prepare_region_draining_tasks(uint parallel_gc_threads);
1121
1122 // Add dense prefix update tasks to the task queue.
1123 static void enqueue_dense_prefix_tasks(TaskQueue& task_queue,
1124 uint parallel_gc_threads);
1125
1126 // If objects are left in eden after a collection, try to move the boundary
1127 // and absorb them into the old gen. Returns true if eden was emptied.
1128 static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1129 PSYoungGen* young_gen,
1130 PSOldGen* old_gen);
1131
1132 // Reset time since last full gc
1133 static void reset_millis_since_last_gc();
1134
1135 #ifndef PRODUCT
1136 // Print generic summary data
1137 static void print_generic_summary_data(ParallelCompactData& summary_data,
1138 HeapWord* const beg_addr,
1139 HeapWord* const end_addr);
1140 #endif // #ifndef PRODUCT
1141
1142 public:
1143
1144 PSParallelCompact();
1145
1146 static void invoke(bool maximum_heap_compaction);
1147 static bool invoke_no_policy(bool maximum_heap_compaction);
1148
1149 static void post_initialize();
1150 // Perform initialization for PSParallelCompact that requires
1151 // allocations. This should be called during the VM initialization
1152 // at a pointer where it would be appropriate to return a JNI_ENOMEM
1153 // in the event of a failure.
1154 static bool initialize();
1155
1156 // Closure accessors
1157 static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; }
1158
1159 // Public accessors
1160 static elapsedTimer* accumulated_time() { return &_accumulated_time; }
1161 static unsigned int total_invocations() { return _total_invocations; }
1162 static CollectorCounters* counters() { return _counters; }
1163
1164 // Marking support
1165 static inline bool mark_obj(oop obj);
1166 static inline bool is_marked(oop obj);
1167
1168 template <class T> static inline void adjust_pointer(T* p, ParCompactionManager* cm);
1169
1170 // Compaction support.
1171 // Return true if p is in the range [beg_addr, end_addr).
1172 static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
1173 static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
1174
1175 // Convenience wrappers for per-space data kept in _space_info.
1176 static inline MutableSpace* space(SpaceId space_id);
1177 static inline HeapWord* new_top(SpaceId space_id);
1178 static inline HeapWord* dense_prefix(SpaceId space_id);
1179 static inline ObjectStartArray* start_array(SpaceId space_id);
1180
1181 // Process the end of the given region range in the dense prefix.
1182 // This includes saving any object not updated.
1183 static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
1184 size_t region_start_index,
1185 size_t region_end_index,
1186 idx_t exiting_object_offset,
1187 idx_t region_offset_start,
1188 idx_t region_offset_end);
1189
1190 // Update a region in the dense prefix. For each live object
1191 // in the region, update it's interior references. For each
1192 // dead object, fill it with deadwood. Dead space at the end
1193 // of a region range will be filled to the start of the next
1194 // live object regardless of the region_index_end. None of the
1195 // objects in the dense prefix move and dead space is dead
1196 // (holds only dead objects that don't need any processing), so
1197 // dead space can be filled in any order.
1198 static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
1199 SpaceId space_id,
1200 size_t region_index_start,
1201 size_t region_index_end);
1202
1203 // Return the address of the count + 1st live word in the range [beg, end).
1204 static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
1205
1206 // Return the address of the word to be copied to dest_addr, which must be
1207 // aligned to a region boundary.
1208 static HeapWord* first_src_addr(HeapWord* const dest_addr,
1209 SpaceId src_space_id,
1210 size_t src_region_idx);
1211
1212 // Determine the next source region, set closure.source() to the start of the
1213 // new region return the region index. Parameter end_addr is the address one
1214 // beyond the end of source range just processed. If necessary, switch to a
1215 // new source space and set src_space_id (in-out parameter) and src_space_top
1216 // (out parameter) accordingly.
1217 static size_t next_src_region(MoveAndUpdateClosure& closure,
1218 SpaceId& src_space_id,
1219 HeapWord*& src_space_top,
1220 HeapWord* end_addr);
1221
1222 // Decrement the destination count for each non-empty source region in the
1223 // range [beg_region, region(region_align_up(end_addr))). If the destination
1224 // count for a region goes to 0 and it needs to be filled, enqueue it.
1225 static void decrement_destination_counts(ParCompactionManager* cm,
1226 SpaceId src_space_id,
1227 size_t beg_region,
1228 HeapWord* end_addr);
1229
1230 static void fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region);
1231 static void fill_and_update_region(ParCompactionManager* cm, size_t region);
1232
1233 static bool steal_unavailable_region(ParCompactionManager* cm, size_t& region_idx);
1234 static void fill_and_update_shadow_region(ParCompactionManager* cm, size_t region);
1235 // Copy the content of a shadow region back to its corresponding heap region
1236 static void copy_back(HeapWord* shadow_addr, HeapWord* region_addr);
1237 // Collect empty regions as shadow regions and initialize the
1238 // _next_shadow_region filed for each compact manager
1239 static void initialize_shadow_regions(uint parallel_gc_threads);
1240
1241 // Fill in the block table for the specified region.
1242 static void fill_blocks(size_t region_idx);
1243
1244 // Update the deferred objects in the space.
1245 static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
1246
1247 static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
1248 static ParallelCompactData& summary_data() { return _summary_data; }
1249
1250 // Reference Processing
1251 static ReferenceProcessor* const ref_processor() { return _ref_processor; }
1252
1253 static STWGCTimer* gc_timer() { return &_gc_timer; }
1254
1255 // Return the SpaceId for the given address.
1256 static SpaceId space_id(HeapWord* addr);
1257
1258 // Time since last full gc (in milliseconds).
1259 static jlong millis_since_last_gc();
1260
1261 static void print_on_error(outputStream* st);
1262
1263 #ifndef PRODUCT
1264 // Debugging support.
1265 static const char* space_names[last_space_id];
1266 static void print_region_ranges();
1267 static void print_dense_prefix_stats(const char* const algorithm,
1268 const SpaceId id,
1269 const bool maximum_compaction,
1270 HeapWord* const addr);
1271 static void summary_phase_msg(SpaceId dst_space_id,
1272 HeapWord* dst_beg, HeapWord* dst_end,
1273 SpaceId src_space_id,
1274 HeapWord* src_beg, HeapWord* src_end);
1275 #endif // #ifndef PRODUCT
1276
1277 #ifdef ASSERT
1278 // Sanity check the new location of a word in the heap.
1279 static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr);
1280 // Verify that all the regions have been emptied.
1281 static void verify_complete(SpaceId space_id);
1282 #endif // #ifdef ASSERT
1283 };
1284
1285 class MoveAndUpdateClosure: public ParMarkBitMapClosure {
1286 static inline size_t calculate_words_remaining(size_t region);
1287 public:
1288 inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
1289 size_t region);
1290
1291 // Accessors.
1292 HeapWord* destination() const { return _destination; }
1293 HeapWord* copy_destination() const { return _destination + _offset; }
1294
1295 // If the object will fit (size <= words_remaining()), copy it to the current
1296 // destination, update the interior oops and the start array and return either
1297 // full (if the closure is full) or incomplete. If the object will not fit,
1298 // return would_overflow.
1299 IterationStatus do_addr(HeapWord* addr, size_t size);
1300
1301 // Copy enough words to fill this closure, starting at source(). Interior
1302 // oops and the start array are not updated. Return full.
1303 IterationStatus copy_until_full();
1304
1305 // Copy enough words to fill this closure or to the end of an object,
1306 // whichever is smaller, starting at source(). Interior oops and the start
1307 // array are not updated.
1308 void copy_partial_obj();
1309
1310 virtual void complete_region(ParCompactionManager* cm, HeapWord* dest_addr,
1311 PSParallelCompact::RegionData* region_ptr);
1312
1313 protected:
1314 // Update variables to indicate that word_count words were processed.
1315 inline void update_state(size_t word_count);
1316
1317 protected:
1318 HeapWord* _destination; // Next addr to be written.
1319 ObjectStartArray* const _start_array;
1320 size_t _offset;
1321 };
1322
1323 inline size_t MoveAndUpdateClosure::calculate_words_remaining(size_t region) {
1324 HeapWord* dest_addr = PSParallelCompact::summary_data().region_to_addr(region);
1325 PSParallelCompact::SpaceId dest_space_id = PSParallelCompact::space_id(dest_addr);
1326 HeapWord* new_top = PSParallelCompact::new_top(dest_space_id);
1327 assert(dest_addr < new_top, "sanity");
1328
1329 return MIN2(pointer_delta(new_top, dest_addr), ParallelCompactData::RegionSize);
1330 }
1331
1332 inline
1333 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
1334 ParCompactionManager* cm,
1335 size_t region_idx) :
1336 ParMarkBitMapClosure(bitmap, cm, calculate_words_remaining(region_idx)),
1337 _destination(PSParallelCompact::summary_data().region_to_addr(region_idx)),
1338 _start_array(PSParallelCompact::start_array(PSParallelCompact::space_id(_destination))),
1339 _offset(0) { }
1340
1341
1342 inline void MoveAndUpdateClosure::update_state(size_t words)
1343 {
1344 decrement_words_remaining(words);
1345 _source += words;
1346 _destination += words;
1347 }
1348
1349 class MoveAndUpdateShadowClosure: public MoveAndUpdateClosure {
1350 inline size_t calculate_shadow_offset(size_t region_idx, size_t shadow_idx);
1351 public:
1352 inline MoveAndUpdateShadowClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
1353 size_t region, size_t shadow);
1354
1355 virtual void complete_region(ParCompactionManager* cm, HeapWord* dest_addr,
1356 PSParallelCompact::RegionData* region_ptr);
1357
1358 private:
1359 size_t _shadow;
1360 };
1361
1362 inline size_t MoveAndUpdateShadowClosure::calculate_shadow_offset(size_t region_idx, size_t shadow_idx) {
1363 ParallelCompactData& sd = PSParallelCompact::summary_data();
1364 HeapWord* dest_addr = sd.region_to_addr(region_idx);
1365 HeapWord* shadow_addr = sd.region_to_addr(shadow_idx);
1366 return pointer_delta(shadow_addr, dest_addr);
1367 }
1368
1369 inline
1370 MoveAndUpdateShadowClosure::MoveAndUpdateShadowClosure(ParMarkBitMap *bitmap,
1371 ParCompactionManager *cm,
1372 size_t region,
1373 size_t shadow) :
1374 MoveAndUpdateClosure(bitmap, cm, region),
1375 _shadow(shadow) {
1376 _offset = calculate_shadow_offset(region, shadow);
1377 }
1378
1379 class UpdateOnlyClosure: public ParMarkBitMapClosure {
1380 private:
1381 const PSParallelCompact::SpaceId _space_id;
1382 ObjectStartArray* const _start_array;
1383
1384 public:
1385 UpdateOnlyClosure(ParMarkBitMap* mbm,
1386 ParCompactionManager* cm,
1387 PSParallelCompact::SpaceId space_id);
1388
1389 // Update the object.
1390 virtual IterationStatus do_addr(HeapWord* addr, size_t words);
1391
1392 inline void do_addr(HeapWord* addr);
1393 };
1394
1395 class FillClosure: public ParMarkBitMapClosure {
1396 public:
1397 FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id);
1398
1399 virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1400
1401 private:
1402 ObjectStartArray* const _start_array;
1403 };
1404
1405 #endif // SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP