Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp @ 6615:09aad8452938
7190310: Inlining WeakReference.get(), and hoisting $referent may lead to non-terminating loops
Summary: In C2 add software membar after load from Reference.referent field to prevent commoning of loads across safepoint since GC can change its value. In C1 always generate Reference.get() intrinsic.
Reviewed-by: roland, twisti, dholmes, johnc
author | kvn |
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date | Mon, 20 Aug 2012 09:58:58 -0700 |
parents | db823a892a55 |
children | 5c93c1f61226 |
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342 | 1 /* |
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2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. |
342 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
342 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP |
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP | |
27 | |
28 #include "gc_implementation/g1/sparsePRT.hpp" | |
29 | |
342 | 30 // Remembered set for a heap region. Represent a set of "cards" that |
31 // contain pointers into the owner heap region. Cards are defined somewhat | |
32 // abstractly, in terms of what the "BlockOffsetTable" in use can parse. | |
33 | |
34 class G1CollectedHeap; | |
35 class G1BlockOffsetSharedArray; | |
36 class HeapRegion; | |
37 class HeapRegionRemSetIterator; | |
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38 class PerRegionTable; |
342 | 39 class SparsePRT; |
40 | |
2173 | 41 // Essentially a wrapper around SparsePRTCleanupTask. See |
42 // sparsePRT.hpp for more details. | |
43 class HRRSCleanupTask : public SparsePRTCleanupTask { | |
44 }; | |
342 | 45 |
46 // The "_coarse_map" is a bitmap with one bit for each region, where set | |
47 // bits indicate that the corresponding region may contain some pointer | |
48 // into the owning region. | |
49 | |
50 // The "_fine_grain_entries" array is an open hash table of PerRegionTables | |
51 // (PRTs), indicating regions for which we're keeping the RS as a set of | |
52 // cards. The strategy is to cap the size of the fine-grain table, | |
53 // deleting an entry and setting the corresponding coarse-grained bit when | |
54 // we would overflow this cap. | |
55 | |
56 // We use a mixture of locking and lock-free techniques here. We allow | |
57 // threads to locate PRTs without locking, but threads attempting to alter | |
58 // a bucket list obtain a lock. This means that any failing attempt to | |
59 // find a PRT must be retried with the lock. It might seem dangerous that | |
60 // a read can find a PRT that is concurrently deleted. This is all right, | |
61 // because: | |
62 // | |
63 // 1) We only actually free PRT's at safe points (though we reuse them at | |
64 // other times). | |
65 // 2) We find PRT's in an attempt to add entries. If a PRT is deleted, | |
66 // it's _coarse_map bit is set, so the that we were attempting to add | |
67 // is represented. If a deleted PRT is re-used, a thread adding a bit, | |
68 // thinking the PRT is for a different region, does no harm. | |
69 | |
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70 class OtherRegionsTable VALUE_OBJ_CLASS_SPEC { |
342 | 71 friend class HeapRegionRemSetIterator; |
72 | |
73 G1CollectedHeap* _g1h; | |
74 Mutex _m; | |
75 HeapRegion* _hr; | |
76 | |
77 // These are protected by "_m". | |
78 BitMap _coarse_map; | |
79 size_t _n_coarse_entries; | |
80 static jint _n_coarsenings; | |
81 | |
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82 PerRegionTable** _fine_grain_regions; |
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83 size_t _n_fine_entries; |
342 | 84 |
6253 | 85 // The fine grain remembered sets are doubly linked together using |
86 // their 'next' and 'prev' fields. | |
87 // This allows fast bulk freeing of all the fine grain remembered | |
88 // set entries, and fast finding of all of them without iterating | |
89 // over the _fine_grain_regions table. | |
90 PerRegionTable * _first_all_fine_prts; | |
91 PerRegionTable * _last_all_fine_prts; | |
92 | |
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93 // Used to sample a subset of the fine grain PRTs to determine which |
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94 // PRT to evict and coarsen. |
342 | 95 size_t _fine_eviction_start; |
96 static size_t _fine_eviction_stride; | |
97 static size_t _fine_eviction_sample_size; | |
98 | |
99 SparsePRT _sparse_table; | |
100 | |
101 // These are static after init. | |
102 static size_t _max_fine_entries; | |
103 static size_t _mod_max_fine_entries_mask; | |
104 | |
105 // Requires "prt" to be the first element of the bucket list appropriate | |
106 // for "hr". If this list contains an entry for "hr", return it, | |
107 // otherwise return "NULL". | |
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108 PerRegionTable* find_region_table(size_t ind, HeapRegion* hr) const; |
342 | 109 |
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110 // Find, delete, and return a candidate PerRegionTable, if any exists, |
342 | 111 // adding the deleted region to the coarse bitmap. Requires the caller |
112 // to hold _m, and the fine-grain table to be full. | |
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113 PerRegionTable* delete_region_table(); |
342 | 114 |
115 // If a PRT for "hr" is in the bucket list indicated by "ind" (which must | |
116 // be the correct index for "hr"), delete it and return true; else return | |
117 // false. | |
118 bool del_single_region_table(size_t ind, HeapRegion* hr); | |
119 | |
120 // Indexed by thread X heap region, to minimize thread contention. | |
121 static int** _from_card_cache; | |
122 static size_t _from_card_cache_max_regions; | |
123 static size_t _from_card_cache_mem_size; | |
124 | |
6253 | 125 // link/add the given fine grain remembered set into the "all" list |
126 void link_to_all(PerRegionTable * prt); | |
127 // unlink/remove the given fine grain remembered set into the "all" list | |
128 void unlink_from_all(PerRegionTable * prt); | |
129 | |
342 | 130 public: |
131 OtherRegionsTable(HeapRegion* hr); | |
132 | |
133 HeapRegion* hr() const { return _hr; } | |
134 | |
135 // For now. Could "expand" some tables in the future, so that this made | |
136 // sense. | |
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137 void add_reference(OopOrNarrowOopStar from, int tid); |
342 | 138 |
139 // Removes any entries shown by the given bitmaps to contain only dead | |
140 // objects. | |
141 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); | |
142 | |
143 // Not const because it takes a lock. | |
144 size_t occupied() const; | |
145 size_t occ_fine() const; | |
146 size_t occ_coarse() const; | |
147 size_t occ_sparse() const; | |
148 | |
149 static jint n_coarsenings() { return _n_coarsenings; } | |
150 | |
151 // Returns size in bytes. | |
152 // Not const because it takes a lock. | |
153 size_t mem_size() const; | |
154 static size_t static_mem_size(); | |
155 static size_t fl_mem_size(); | |
156 | |
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157 bool contains_reference(OopOrNarrowOopStar from) const; |
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158 bool contains_reference_locked(OopOrNarrowOopStar from) const; |
342 | 159 |
160 void clear(); | |
161 | |
162 // Specifically clear the from_card_cache. | |
163 void clear_fcc(); | |
164 | |
165 // "from_hr" is being cleared; remove any entries from it. | |
166 void clear_incoming_entry(HeapRegion* from_hr); | |
167 | |
2173 | 168 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); |
169 | |
342 | 170 // Declare the heap size (in # of regions) to the OtherRegionsTable. |
171 // (Uses it to initialize from_card_cache). | |
172 static void init_from_card_cache(size_t max_regions); | |
173 | |
174 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. | |
175 // Make sure any entries for higher regions are invalid. | |
176 static void shrink_from_card_cache(size_t new_n_regs); | |
177 | |
178 static void print_from_card_cache(); | |
179 }; | |
180 | |
6197 | 181 class HeapRegionRemSet : public CHeapObj<mtGC> { |
342 | 182 friend class VMStructs; |
183 friend class HeapRegionRemSetIterator; | |
184 | |
185 public: | |
186 enum Event { | |
187 Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd | |
188 }; | |
189 | |
190 private: | |
191 G1BlockOffsetSharedArray* _bosa; | |
192 G1BlockOffsetSharedArray* bosa() const { return _bosa; } | |
193 | |
194 OtherRegionsTable _other_regions; | |
195 | |
196 enum ParIterState { Unclaimed, Claimed, Complete }; | |
1261 | 197 volatile ParIterState _iter_state; |
198 volatile jlong _iter_claimed; | |
342 | 199 |
200 // Unused unless G1RecordHRRSOops is true. | |
201 | |
202 static const int MaxRecorded = 1000000; | |
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203 static OopOrNarrowOopStar* _recorded_oops; |
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204 static HeapWord** _recorded_cards; |
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205 static HeapRegion** _recorded_regions; |
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206 static int _n_recorded; |
342 | 207 |
208 static const int MaxRecordedEvents = 1000; | |
209 static Event* _recorded_events; | |
210 static int* _recorded_event_index; | |
211 static int _n_recorded_events; | |
212 | |
213 static void print_event(outputStream* str, Event evnt); | |
214 | |
215 public: | |
216 HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, | |
217 HeapRegion* hr); | |
218 | |
219 static int num_par_rem_sets(); | |
1261 | 220 static void setup_remset_size(); |
342 | 221 |
222 HeapRegion* hr() const { | |
223 return _other_regions.hr(); | |
224 } | |
225 | |
226 size_t occupied() const { | |
227 return _other_regions.occupied(); | |
228 } | |
229 size_t occ_fine() const { | |
230 return _other_regions.occ_fine(); | |
231 } | |
232 size_t occ_coarse() const { | |
233 return _other_regions.occ_coarse(); | |
234 } | |
235 size_t occ_sparse() const { | |
236 return _other_regions.occ_sparse(); | |
237 } | |
238 | |
239 static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } | |
240 | |
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241 // Used in the sequential case. |
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242 void add_reference(OopOrNarrowOopStar from) { |
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243 _other_regions.add_reference(from, 0); |
342 | 244 } |
245 | |
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246 // Used in the parallel case. |
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247 void add_reference(OopOrNarrowOopStar from, int tid) { |
342 | 248 _other_regions.add_reference(from, tid); |
249 } | |
250 | |
251 // Removes any entries shown by the given bitmaps to contain only dead | |
252 // objects. | |
253 void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); | |
254 | |
255 // The region is being reclaimed; clear its remset, and any mention of | |
256 // entries for this region in other remsets. | |
257 void clear(); | |
258 | |
259 // Attempt to claim the region. Returns true iff this call caused an | |
260 // atomic transition from Unclaimed to Claimed. | |
261 bool claim_iter(); | |
262 // Sets the iteration state to "complete". | |
263 void set_iter_complete(); | |
264 // Returns "true" iff the region's iteration is complete. | |
265 bool iter_is_complete(); | |
266 | |
1261 | 267 // Support for claiming blocks of cards during iteration |
268 size_t iter_claimed() const { return (size_t)_iter_claimed; } | |
269 // Claim the next block of cards | |
270 size_t iter_claimed_next(size_t step) { | |
271 size_t current, next; | |
272 do { | |
273 current = iter_claimed(); | |
274 next = current + step; | |
275 } while (Atomic::cmpxchg((jlong)next, &_iter_claimed, (jlong)current) != (jlong)current); | |
276 return current; | |
277 } | |
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278 void reset_for_par_iteration(); |
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279 |
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280 bool verify_ready_for_par_iteration() { |
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281 return (_iter_state == Unclaimed) && (_iter_claimed == 0); |
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282 } |
1261 | 283 |
342 | 284 // Initialize the given iterator to iterate over this rem set. |
285 void init_iterator(HeapRegionRemSetIterator* iter) const; | |
286 | |
287 // The actual # of bytes this hr_remset takes up. | |
288 size_t mem_size() { | |
289 return _other_regions.mem_size() | |
290 // This correction is necessary because the above includes the second | |
291 // part. | |
292 + sizeof(this) - sizeof(OtherRegionsTable); | |
293 } | |
294 | |
295 // Returns the memory occupancy of all static data structures associated | |
296 // with remembered sets. | |
297 static size_t static_mem_size() { | |
298 return OtherRegionsTable::static_mem_size(); | |
299 } | |
300 | |
301 // Returns the memory occupancy of all free_list data structures associated | |
302 // with remembered sets. | |
303 static size_t fl_mem_size() { | |
304 return OtherRegionsTable::fl_mem_size(); | |
305 } | |
306 | |
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307 bool contains_reference(OopOrNarrowOopStar from) const { |
342 | 308 return _other_regions.contains_reference(from); |
309 } | |
310 void print() const; | |
311 | |
312 // Called during a stop-world phase to perform any deferred cleanups. | |
313 static void cleanup(); | |
314 | |
315 // Declare the heap size (in # of regions) to the HeapRegionRemSet(s). | |
316 // (Uses it to initialize from_card_cache). | |
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317 static void init_heap(uint max_regions) { |
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318 OtherRegionsTable::init_from_card_cache((size_t) max_regions); |
342 | 319 } |
320 | |
321 // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. | |
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322 static void shrink_heap(uint new_n_regs) { |
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323 OtherRegionsTable::shrink_from_card_cache((size_t) new_n_regs); |
342 | 324 } |
325 | |
326 #ifndef PRODUCT | |
327 static void print_from_card_cache() { | |
328 OtherRegionsTable::print_from_card_cache(); | |
329 } | |
330 #endif | |
331 | |
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332 static void record(HeapRegion* hr, OopOrNarrowOopStar f); |
342 | 333 static void print_recorded(); |
334 static void record_event(Event evnt); | |
335 | |
2173 | 336 // These are wrappers for the similarly-named methods on |
337 // SparsePRT. Look at sparsePRT.hpp for more details. | |
338 static void reset_for_cleanup_tasks(); | |
339 void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); | |
340 static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); | |
341 | |
342 | 342 // Run unit tests. |
343 #ifndef PRODUCT | |
344 static void test(); | |
345 #endif | |
346 }; | |
347 | |
6197 | 348 class HeapRegionRemSetIterator : public CHeapObj<mtGC> { |
342 | 349 |
350 // The region over which we're iterating. | |
351 const HeapRegionRemSet* _hrrs; | |
352 | |
353 // Local caching of HRRS fields. | |
354 const BitMap* _coarse_map; | |
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355 PerRegionTable** _fine_grain_regions; |
342 | 356 |
357 G1BlockOffsetSharedArray* _bosa; | |
358 G1CollectedHeap* _g1h; | |
359 | |
360 // The number yielded since initialization. | |
361 size_t _n_yielded_fine; | |
362 size_t _n_yielded_coarse; | |
363 size_t _n_yielded_sparse; | |
364 | |
365 // If true we're iterating over the coarse table; if false the fine | |
366 // table. | |
367 enum IterState { | |
368 Sparse, | |
369 Fine, | |
370 Coarse | |
371 }; | |
372 IterState _is; | |
373 | |
374 // In both kinds of iteration, heap offset of first card of current | |
375 // region. | |
376 size_t _cur_region_card_offset; | |
377 // Card offset within cur region. | |
378 size_t _cur_region_cur_card; | |
379 | |
380 // Coarse table iteration fields: | |
381 | |
382 // Current region index; | |
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383 int _coarse_cur_region_index; |
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384 size_t _coarse_cur_region_cur_card; |
342 | 385 |
386 bool coarse_has_next(size_t& card_index); | |
387 | |
388 // Fine table iteration fields: | |
389 | |
390 // Index of bucket-list we're working on. | |
391 int _fine_array_index; | |
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392 |
342 | 393 // Per Region Table we're doing within current bucket list. |
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394 PerRegionTable* _fine_cur_prt; |
342 | 395 |
396 /* SparsePRT::*/ SparsePRTIter _sparse_iter; | |
397 | |
398 void fine_find_next_non_null_prt(); | |
399 | |
400 bool fine_has_next(); | |
401 bool fine_has_next(size_t& card_index); | |
402 | |
403 public: | |
404 // We require an iterator to be initialized before use, so the | |
405 // constructor does little. | |
406 HeapRegionRemSetIterator(); | |
407 | |
408 void initialize(const HeapRegionRemSet* hrrs); | |
409 | |
410 // If there remains one or more cards to be yielded, returns true and | |
411 // sets "card_index" to one of those cards (which is then considered | |
412 // yielded.) Otherwise, returns false (and leaves "card_index" | |
413 // undefined.) | |
414 bool has_next(size_t& card_index); | |
415 | |
416 size_t n_yielded_fine() { return _n_yielded_fine; } | |
417 size_t n_yielded_coarse() { return _n_yielded_coarse; } | |
418 size_t n_yielded_sparse() { return _n_yielded_sparse; } | |
419 size_t n_yielded() { | |
420 return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); | |
421 } | |
422 }; | |
423 | |
1972 | 424 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP |