Mercurial > hg > truffle
annotate src/share/vm/memory/cardTableModRefBS.hpp @ 362:f8199438385b
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author | apetrusenko |
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date | Wed, 17 Sep 2008 16:49:18 +0400 |
parents | 1ee8caae33af |
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rev | line source |
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0 | 1 /* |
196 | 2 * Copyright 2000-2008 Sun Microsystems, Inc. All Rights Reserved. |
0 | 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and | |
26 // enumerate ref fields that have been modified (since the last | |
27 // enumeration.) | |
28 | |
29 // As it currently stands, this barrier is *imprecise*: when a ref field in | |
30 // an object "o" is modified, the card table entry for the card containing | |
31 // the head of "o" is dirtied, not necessarily the card containing the | |
32 // modified field itself. For object arrays, however, the barrier *is* | |
33 // precise; only the card containing the modified element is dirtied. | |
34 // Any MemRegionClosures used to scan dirty cards should take these | |
35 // considerations into account. | |
36 | |
37 class Generation; | |
38 class OopsInGenClosure; | |
39 class DirtyCardToOopClosure; | |
40 | |
41 class CardTableModRefBS: public ModRefBarrierSet { | |
42 // Some classes get to look at some private stuff. | |
43 friend class BytecodeInterpreter; | |
44 friend class VMStructs; | |
45 friend class CardTableRS; | |
46 friend class CheckForUnmarkedOops; // Needs access to raw card bytes. | |
47 #ifndef PRODUCT | |
48 // For debugging. | |
49 friend class GuaranteeNotModClosure; | |
50 #endif | |
51 protected: | |
52 | |
53 enum CardValues { | |
54 clean_card = -1, | |
55 dirty_card = 0, | |
56 precleaned_card = 1, | |
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57 claimed_card = 3, |
0 | 58 last_card = 4, |
59 CT_MR_BS_last_reserved = 10 | |
60 }; | |
61 | |
62 // dirty and precleaned are equivalent wrt younger_refs_iter. | |
63 static bool card_is_dirty_wrt_gen_iter(jbyte cv) { | |
64 return cv == dirty_card || cv == precleaned_card; | |
65 } | |
66 | |
67 // Returns "true" iff the value "cv" will cause the card containing it | |
68 // to be scanned in the current traversal. May be overridden by | |
69 // subtypes. | |
70 virtual bool card_will_be_scanned(jbyte cv) { | |
71 return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv); | |
72 } | |
73 | |
74 // Returns "true" iff the value "cv" may have represented a dirty card at | |
75 // some point. | |
76 virtual bool card_may_have_been_dirty(jbyte cv) { | |
77 return card_is_dirty_wrt_gen_iter(cv); | |
78 } | |
79 | |
80 // The declaration order of these const fields is important; see the | |
81 // constructor before changing. | |
82 const MemRegion _whole_heap; // the region covered by the card table | |
83 const size_t _guard_index; // index of very last element in the card | |
84 // table; it is set to a guard value | |
85 // (last_card) and should never be modified | |
86 const size_t _last_valid_index; // index of the last valid element | |
87 const size_t _page_size; // page size used when mapping _byte_map | |
88 const size_t _byte_map_size; // in bytes | |
89 jbyte* _byte_map; // the card marking array | |
90 | |
91 int _cur_covered_regions; | |
92 // The covered regions should be in address order. | |
93 MemRegion* _covered; | |
94 // The committed regions correspond one-to-one to the covered regions. | |
95 // They represent the card-table memory that has been committed to service | |
96 // the corresponding covered region. It may be that committed region for | |
97 // one covered region corresponds to a larger region because of page-size | |
98 // roundings. Thus, a committed region for one covered region may | |
99 // actually extend onto the card-table space for the next covered region. | |
100 MemRegion* _committed; | |
101 | |
102 // The last card is a guard card, and we commit the page for it so | |
103 // we can use the card for verification purposes. We make sure we never | |
104 // uncommit the MemRegion for that page. | |
105 MemRegion _guard_region; | |
106 | |
107 protected: | |
108 // Initialization utilities; covered_words is the size of the covered region | |
109 // in, um, words. | |
110 inline size_t cards_required(size_t covered_words); | |
111 inline size_t compute_byte_map_size(); | |
112 | |
113 // Finds and return the index of the region, if any, to which the given | |
114 // region would be contiguous. If none exists, assign a new region and | |
115 // returns its index. Requires that no more than the maximum number of | |
116 // covered regions defined in the constructor are ever in use. | |
117 int find_covering_region_by_base(HeapWord* base); | |
118 | |
119 // Same as above, but finds the region containing the given address | |
120 // instead of starting at a given base address. | |
121 int find_covering_region_containing(HeapWord* addr); | |
122 | |
123 // Resize one of the regions covered by the remembered set. | |
124 void resize_covered_region(MemRegion new_region); | |
125 | |
126 // Returns the leftmost end of a committed region corresponding to a | |
127 // covered region before covered region "ind", or else "NULL" if "ind" is | |
128 // the first covered region. | |
129 HeapWord* largest_prev_committed_end(int ind) const; | |
130 | |
131 // Returns the part of the region mr that doesn't intersect with | |
132 // any committed region other than self. Used to prevent uncommitting | |
133 // regions that are also committed by other regions. Also protects | |
134 // against uncommitting the guard region. | |
135 MemRegion committed_unique_to_self(int self, MemRegion mr) const; | |
136 | |
137 // Mapping from address to card marking array entry | |
138 jbyte* byte_for(const void* p) const { | |
139 assert(_whole_heap.contains(p), | |
140 "out of bounds access to card marking array"); | |
141 jbyte* result = &byte_map_base[uintptr_t(p) >> card_shift]; | |
142 assert(result >= _byte_map && result < _byte_map + _byte_map_size, | |
143 "out of bounds accessor for card marking array"); | |
144 return result; | |
145 } | |
146 | |
147 // The card table byte one after the card marking array | |
148 // entry for argument address. Typically used for higher bounds | |
149 // for loops iterating through the card table. | |
150 jbyte* byte_after(const void* p) const { | |
151 return byte_for(p) + 1; | |
152 } | |
153 | |
154 // Iterate over the portion of the card-table which covers the given | |
155 // region mr in the given space and apply cl to any dirty sub-regions | |
156 // of mr. cl and dcto_cl must either be the same closure or cl must | |
157 // wrap dcto_cl. Both are required - neither may be NULL. Also, dcto_cl | |
158 // may be modified. Note that this function will operate in a parallel | |
159 // mode if worker threads are available. | |
160 void non_clean_card_iterate(Space* sp, MemRegion mr, | |
161 DirtyCardToOopClosure* dcto_cl, | |
162 MemRegionClosure* cl, | |
163 bool clear); | |
164 | |
165 // Utility function used to implement the other versions below. | |
166 void non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl, | |
167 bool clear); | |
168 | |
169 void par_non_clean_card_iterate_work(Space* sp, MemRegion mr, | |
170 DirtyCardToOopClosure* dcto_cl, | |
171 MemRegionClosure* cl, | |
172 bool clear, | |
173 int n_threads); | |
174 | |
175 // Dirty the bytes corresponding to "mr" (not all of which must be | |
176 // covered.) | |
177 void dirty_MemRegion(MemRegion mr); | |
178 | |
179 // Clear (to clean_card) the bytes entirely contained within "mr" (not | |
180 // all of which must be covered.) | |
181 void clear_MemRegion(MemRegion mr); | |
182 | |
183 // *** Support for parallel card scanning. | |
184 | |
185 enum SomeConstantsForParallelism { | |
186 StridesPerThread = 2, | |
187 CardsPerStrideChunk = 256 | |
188 }; | |
189 | |
190 // This is an array, one element per covered region of the card table. | |
191 // Each entry is itself an array, with one element per chunk in the | |
192 // covered region. Each entry of these arrays is the lowest non-clean | |
193 // card of the corresponding chunk containing part of an object from the | |
194 // previous chunk, or else NULL. | |
195 typedef jbyte* CardPtr; | |
196 typedef CardPtr* CardArr; | |
197 CardArr* _lowest_non_clean; | |
198 size_t* _lowest_non_clean_chunk_size; | |
199 uintptr_t* _lowest_non_clean_base_chunk_index; | |
200 int* _last_LNC_resizing_collection; | |
201 | |
202 // Initializes "lowest_non_clean" to point to the array for the region | |
203 // covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk | |
204 // index of the corresponding to the first element of that array. | |
205 // Ensures that these arrays are of sufficient size, allocating if necessary. | |
206 // May be called by several threads concurrently. | |
207 void get_LNC_array_for_space(Space* sp, | |
208 jbyte**& lowest_non_clean, | |
209 uintptr_t& lowest_non_clean_base_chunk_index, | |
210 size_t& lowest_non_clean_chunk_size); | |
211 | |
212 // Returns the number of chunks necessary to cover "mr". | |
213 size_t chunks_to_cover(MemRegion mr) { | |
214 return (size_t)(addr_to_chunk_index(mr.last()) - | |
215 addr_to_chunk_index(mr.start()) + 1); | |
216 } | |
217 | |
218 // Returns the index of the chunk in a stride which | |
219 // covers the given address. | |
220 uintptr_t addr_to_chunk_index(const void* addr) { | |
221 uintptr_t card = (uintptr_t) byte_for(addr); | |
222 return card / CardsPerStrideChunk; | |
223 } | |
224 | |
225 // Apply cl, which must either itself apply dcto_cl or be dcto_cl, | |
226 // to the cards in the stride (of n_strides) within the given space. | |
227 void process_stride(Space* sp, | |
228 MemRegion used, | |
229 jint stride, int n_strides, | |
230 DirtyCardToOopClosure* dcto_cl, | |
231 MemRegionClosure* cl, | |
232 bool clear, | |
233 jbyte** lowest_non_clean, | |
234 uintptr_t lowest_non_clean_base_chunk_index, | |
235 size_t lowest_non_clean_chunk_size); | |
236 | |
237 // Makes sure that chunk boundaries are handled appropriately, by | |
238 // adjusting the min_done of dcto_cl, and by using a special card-table | |
239 // value to indicate how min_done should be set. | |
240 void process_chunk_boundaries(Space* sp, | |
241 DirtyCardToOopClosure* dcto_cl, | |
242 MemRegion chunk_mr, | |
243 MemRegion used, | |
244 jbyte** lowest_non_clean, | |
245 uintptr_t lowest_non_clean_base_chunk_index, | |
246 size_t lowest_non_clean_chunk_size); | |
247 | |
248 public: | |
249 // Constants | |
250 enum SomePublicConstants { | |
251 card_shift = 9, | |
252 card_size = 1 << card_shift, | |
253 card_size_in_words = card_size / sizeof(HeapWord) | |
254 }; | |
255 | |
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256 static int clean_card_val() { return clean_card; } |
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257 static int dirty_card_val() { return dirty_card; } |
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258 static int claimed_card_val() { return claimed_card; } |
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259 static int precleaned_card_val() { return precleaned_card; } |
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260 |
0 | 261 // For RTTI simulation. |
262 bool is_a(BarrierSet::Name bsn) { | |
342
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263 return bsn == BarrierSet::CardTableModRef || ModRefBarrierSet::is_a(bsn); |
0 | 264 } |
265 | |
266 CardTableModRefBS(MemRegion whole_heap, int max_covered_regions); | |
267 | |
268 // *** Barrier set functions. | |
269 | |
342
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270 bool has_write_ref_pre_barrier() { return false; } |
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271 |
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272 inline bool write_ref_needs_barrier(void* field, oop new_val) { |
0 | 273 // Note that this assumes the perm gen is the highest generation |
274 // in the address space | |
275 return new_val != NULL && !new_val->is_perm(); | |
276 } | |
277 | |
278 // Record a reference update. Note that these versions are precise! | |
279 // The scanning code has to handle the fact that the write barrier may be | |
280 // either precise or imprecise. We make non-virtual inline variants of | |
281 // these functions here for performance. | |
282 protected: | |
283 void write_ref_field_work(oop obj, size_t offset, oop newVal); | |
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284 void write_ref_field_work(void* field, oop newVal); |
0 | 285 public: |
286 | |
287 bool has_write_ref_array_opt() { return true; } | |
288 bool has_write_region_opt() { return true; } | |
289 | |
290 inline void inline_write_region(MemRegion mr) { | |
291 dirty_MemRegion(mr); | |
292 } | |
293 protected: | |
294 void write_region_work(MemRegion mr) { | |
295 inline_write_region(mr); | |
296 } | |
297 public: | |
298 | |
299 inline void inline_write_ref_array(MemRegion mr) { | |
300 dirty_MemRegion(mr); | |
301 } | |
302 protected: | |
303 void write_ref_array_work(MemRegion mr) { | |
304 inline_write_ref_array(mr); | |
305 } | |
306 public: | |
307 | |
308 bool is_aligned(HeapWord* addr) { | |
309 return is_card_aligned(addr); | |
310 } | |
311 | |
312 // *** Card-table-barrier-specific things. | |
313 | |
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314 inline void inline_write_ref_field_pre(void* field, oop newVal) {} |
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315 |
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316 inline void inline_write_ref_field(void* field, oop newVal) { |
0 | 317 jbyte* byte = byte_for(field); |
318 *byte = dirty_card; | |
319 } | |
320 | |
342
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321 // These are used by G1, when it uses the card table as a temporary data |
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322 // structure for card claiming. |
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323 bool is_card_dirty(size_t card_index) { |
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324 return _byte_map[card_index] == dirty_card_val(); |
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325 } |
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326 |
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327 void mark_card_dirty(size_t card_index) { |
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328 _byte_map[card_index] = dirty_card_val(); |
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329 } |
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330 |
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331 bool is_card_claimed(size_t card_index) { |
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332 return _byte_map[card_index] == claimed_card_val(); |
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333 } |
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334 |
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335 bool claim_card(size_t card_index); |
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336 |
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337 bool is_card_clean(size_t card_index) { |
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338 return _byte_map[card_index] == clean_card_val(); |
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339 } |
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340 |
0 | 341 // Card marking array base (adjusted for heap low boundary) |
342 // This would be the 0th element of _byte_map, if the heap started at 0x0. | |
343 // But since the heap starts at some higher address, this points to somewhere | |
344 // before the beginning of the actual _byte_map. | |
345 jbyte* byte_map_base; | |
346 | |
347 // Return true if "p" is at the start of a card. | |
348 bool is_card_aligned(HeapWord* p) { | |
349 jbyte* pcard = byte_for(p); | |
350 return (addr_for(pcard) == p); | |
351 } | |
352 | |
353 // The kinds of precision a CardTableModRefBS may offer. | |
354 enum PrecisionStyle { | |
355 Precise, | |
356 ObjHeadPreciseArray | |
357 }; | |
358 | |
359 // Tells what style of precision this card table offers. | |
360 PrecisionStyle precision() { | |
361 return ObjHeadPreciseArray; // Only one supported for now. | |
362 } | |
363 | |
364 // ModRefBS functions. | |
342
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365 virtual void invalidate(MemRegion mr, bool whole_heap = false); |
0 | 366 void clear(MemRegion mr); |
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367 void dirty(MemRegion mr); |
0 | 368 void mod_oop_in_space_iterate(Space* sp, OopClosure* cl, |
369 bool clear = false, | |
370 bool before_save_marks = false); | |
371 | |
372 // *** Card-table-RemSet-specific things. | |
373 | |
374 // Invoke "cl.do_MemRegion" on a set of MemRegions that collectively | |
375 // includes all the modified cards (expressing each card as a | |
376 // MemRegion). Thus, several modified cards may be lumped into one | |
377 // region. The regions are non-overlapping, and are visited in | |
378 // *decreasing* address order. (This order aids with imprecise card | |
379 // marking, where a dirty card may cause scanning, and summarization | |
380 // marking, of objects that extend onto subsequent cards.) | |
381 // If "clear" is true, the card is (conceptually) marked unmodified before | |
382 // applying the closure. | |
383 void mod_card_iterate(MemRegionClosure* cl, bool clear = false) { | |
384 non_clean_card_iterate_work(_whole_heap, cl, clear); | |
385 } | |
386 | |
387 // Like the "mod_cards_iterate" above, except only invokes the closure | |
388 // for cards within the MemRegion "mr" (which is required to be | |
389 // card-aligned and sized.) | |
390 void mod_card_iterate(MemRegion mr, MemRegionClosure* cl, | |
391 bool clear = false) { | |
392 non_clean_card_iterate_work(mr, cl, clear); | |
393 } | |
394 | |
395 static uintx ct_max_alignment_constraint(); | |
396 | |
342
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397 // Apply closure "cl" to the dirty cards containing some part of |
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398 // MemRegion "mr". |
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399 void dirty_card_iterate(MemRegion mr, MemRegionClosure* cl); |
0 | 400 |
401 // Return the MemRegion corresponding to the first maximal run | |
342
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402 // of dirty cards lying completely within MemRegion mr. |
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403 // If reset is "true", then sets those card table entries to the given |
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404 // value. |
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405 MemRegion dirty_card_range_after_reset(MemRegion mr, bool reset, |
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406 int reset_val); |
0 | 407 |
408 // Set all the dirty cards in the given region to precleaned state. | |
409 void preclean_dirty_cards(MemRegion mr); | |
410 | |
342
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411 // Provide read-only access to the card table array. |
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412 const jbyte* byte_for_const(const void* p) const { |
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413 return byte_for(p); |
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414 } |
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415 const jbyte* byte_after_const(const void* p) const { |
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416 return byte_after(p); |
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417 } |
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418 |
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419 // Mapping from card marking array entry to address of first word |
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420 HeapWord* addr_for(const jbyte* p) const { |
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421 assert(p >= _byte_map && p < _byte_map + _byte_map_size, |
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422 "out of bounds access to card marking array"); |
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423 size_t delta = pointer_delta(p, byte_map_base, sizeof(jbyte)); |
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424 HeapWord* result = (HeapWord*) (delta << card_shift); |
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425 assert(_whole_heap.contains(result), |
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426 "out of bounds accessor from card marking array"); |
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427 return result; |
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428 } |
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429 |
0 | 430 // Mapping from address to card marking array index. |
431 int index_for(void* p) { | |
432 assert(_whole_heap.contains(p), | |
433 "out of bounds access to card marking array"); | |
434 return byte_for(p) - _byte_map; | |
435 } | |
436 | |
437 void verify(); | |
438 void verify_guard(); | |
439 | |
440 void verify_clean_region(MemRegion mr) PRODUCT_RETURN; | |
441 | |
442 static size_t par_chunk_heapword_alignment() { | |
443 return CardsPerStrideChunk * card_size_in_words; | |
444 } | |
342
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445 |
0 | 446 }; |
447 | |
448 class CardTableRS; | |
449 | |
450 // A specialization for the CardTableRS gen rem set. | |
451 class CardTableModRefBSForCTRS: public CardTableModRefBS { | |
452 CardTableRS* _rs; | |
453 protected: | |
454 bool card_will_be_scanned(jbyte cv); | |
455 bool card_may_have_been_dirty(jbyte cv); | |
456 public: | |
457 CardTableModRefBSForCTRS(MemRegion whole_heap, | |
458 int max_covered_regions) : | |
459 CardTableModRefBS(whole_heap, max_covered_regions) {} | |
460 | |
461 void set_CTRS(CardTableRS* rs) { _rs = rs; } | |
462 }; |