Mercurial > hg > graal-compiler
comparison src/share/vm/memory/cardTableModRefBS.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ba764ed4b6f2 |
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1 /* | |
2 * Copyright 2000-2006 Sun Microsystems, Inc. All Rights Reserved. | |
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact 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, | |
57 last_card = 4, | |
58 CT_MR_BS_last_reserved = 10 | |
59 }; | |
60 | |
61 // dirty and precleaned are equivalent wrt younger_refs_iter. | |
62 static bool card_is_dirty_wrt_gen_iter(jbyte cv) { | |
63 return cv == dirty_card || cv == precleaned_card; | |
64 } | |
65 | |
66 // Returns "true" iff the value "cv" will cause the card containing it | |
67 // to be scanned in the current traversal. May be overridden by | |
68 // subtypes. | |
69 virtual bool card_will_be_scanned(jbyte cv) { | |
70 return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv); | |
71 } | |
72 | |
73 // Returns "true" iff the value "cv" may have represented a dirty card at | |
74 // some point. | |
75 virtual bool card_may_have_been_dirty(jbyte cv) { | |
76 return card_is_dirty_wrt_gen_iter(cv); | |
77 } | |
78 | |
79 // The declaration order of these const fields is important; see the | |
80 // constructor before changing. | |
81 const MemRegion _whole_heap; // the region covered by the card table | |
82 const size_t _guard_index; // index of very last element in the card | |
83 // table; it is set to a guard value | |
84 // (last_card) and should never be modified | |
85 const size_t _last_valid_index; // index of the last valid element | |
86 const size_t _page_size; // page size used when mapping _byte_map | |
87 const size_t _byte_map_size; // in bytes | |
88 jbyte* _byte_map; // the card marking array | |
89 | |
90 int _cur_covered_regions; | |
91 // The covered regions should be in address order. | |
92 MemRegion* _covered; | |
93 // The committed regions correspond one-to-one to the covered regions. | |
94 // They represent the card-table memory that has been committed to service | |
95 // the corresponding covered region. It may be that committed region for | |
96 // one covered region corresponds to a larger region because of page-size | |
97 // roundings. Thus, a committed region for one covered region may | |
98 // actually extend onto the card-table space for the next covered region. | |
99 MemRegion* _committed; | |
100 | |
101 // The last card is a guard card, and we commit the page for it so | |
102 // we can use the card for verification purposes. We make sure we never | |
103 // uncommit the MemRegion for that page. | |
104 MemRegion _guard_region; | |
105 | |
106 protected: | |
107 // Initialization utilities; covered_words is the size of the covered region | |
108 // in, um, words. | |
109 inline size_t cards_required(size_t covered_words); | |
110 inline size_t compute_byte_map_size(); | |
111 | |
112 // Finds and return the index of the region, if any, to which the given | |
113 // region would be contiguous. If none exists, assign a new region and | |
114 // returns its index. Requires that no more than the maximum number of | |
115 // covered regions defined in the constructor are ever in use. | |
116 int find_covering_region_by_base(HeapWord* base); | |
117 | |
118 // Same as above, but finds the region containing the given address | |
119 // instead of starting at a given base address. | |
120 int find_covering_region_containing(HeapWord* addr); | |
121 | |
122 // Resize one of the regions covered by the remembered set. | |
123 void resize_covered_region(MemRegion new_region); | |
124 | |
125 // Returns the leftmost end of a committed region corresponding to a | |
126 // covered region before covered region "ind", or else "NULL" if "ind" is | |
127 // the first covered region. | |
128 HeapWord* largest_prev_committed_end(int ind) const; | |
129 | |
130 // Returns the part of the region mr that doesn't intersect with | |
131 // any committed region other than self. Used to prevent uncommitting | |
132 // regions that are also committed by other regions. Also protects | |
133 // against uncommitting the guard region. | |
134 MemRegion committed_unique_to_self(int self, MemRegion mr) const; | |
135 | |
136 // Mapping from address to card marking array entry | |
137 jbyte* byte_for(const void* p) const { | |
138 assert(_whole_heap.contains(p), | |
139 "out of bounds access to card marking array"); | |
140 jbyte* result = &byte_map_base[uintptr_t(p) >> card_shift]; | |
141 assert(result >= _byte_map && result < _byte_map + _byte_map_size, | |
142 "out of bounds accessor for card marking array"); | |
143 return result; | |
144 } | |
145 | |
146 // The card table byte one after the card marking array | |
147 // entry for argument address. Typically used for higher bounds | |
148 // for loops iterating through the card table. | |
149 jbyte* byte_after(const void* p) const { | |
150 return byte_for(p) + 1; | |
151 } | |
152 | |
153 // Mapping from card marking array entry to address of first word | |
154 HeapWord* addr_for(const jbyte* p) const { | |
155 assert(p >= _byte_map && p < _byte_map + _byte_map_size, | |
156 "out of bounds access to card marking array"); | |
157 size_t delta = pointer_delta(p, byte_map_base, sizeof(jbyte)); | |
158 HeapWord* result = (HeapWord*) (delta << card_shift); | |
159 assert(_whole_heap.contains(result), | |
160 "out of bounds accessor from card marking array"); | |
161 return result; | |
162 } | |
163 | |
164 // Iterate over the portion of the card-table which covers the given | |
165 // region mr in the given space and apply cl to any dirty sub-regions | |
166 // of mr. cl and dcto_cl must either be the same closure or cl must | |
167 // wrap dcto_cl. Both are required - neither may be NULL. Also, dcto_cl | |
168 // may be modified. Note that this function will operate in a parallel | |
169 // mode if worker threads are available. | |
170 void non_clean_card_iterate(Space* sp, MemRegion mr, | |
171 DirtyCardToOopClosure* dcto_cl, | |
172 MemRegionClosure* cl, | |
173 bool clear); | |
174 | |
175 // Utility function used to implement the other versions below. | |
176 void non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl, | |
177 bool clear); | |
178 | |
179 void par_non_clean_card_iterate_work(Space* sp, MemRegion mr, | |
180 DirtyCardToOopClosure* dcto_cl, | |
181 MemRegionClosure* cl, | |
182 bool clear, | |
183 int n_threads); | |
184 | |
185 // Dirty the bytes corresponding to "mr" (not all of which must be | |
186 // covered.) | |
187 void dirty_MemRegion(MemRegion mr); | |
188 | |
189 // Clear (to clean_card) the bytes entirely contained within "mr" (not | |
190 // all of which must be covered.) | |
191 void clear_MemRegion(MemRegion mr); | |
192 | |
193 // *** Support for parallel card scanning. | |
194 | |
195 enum SomeConstantsForParallelism { | |
196 StridesPerThread = 2, | |
197 CardsPerStrideChunk = 256 | |
198 }; | |
199 | |
200 // This is an array, one element per covered region of the card table. | |
201 // Each entry is itself an array, with one element per chunk in the | |
202 // covered region. Each entry of these arrays is the lowest non-clean | |
203 // card of the corresponding chunk containing part of an object from the | |
204 // previous chunk, or else NULL. | |
205 typedef jbyte* CardPtr; | |
206 typedef CardPtr* CardArr; | |
207 CardArr* _lowest_non_clean; | |
208 size_t* _lowest_non_clean_chunk_size; | |
209 uintptr_t* _lowest_non_clean_base_chunk_index; | |
210 int* _last_LNC_resizing_collection; | |
211 | |
212 // Initializes "lowest_non_clean" to point to the array for the region | |
213 // covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk | |
214 // index of the corresponding to the first element of that array. | |
215 // Ensures that these arrays are of sufficient size, allocating if necessary. | |
216 // May be called by several threads concurrently. | |
217 void get_LNC_array_for_space(Space* sp, | |
218 jbyte**& lowest_non_clean, | |
219 uintptr_t& lowest_non_clean_base_chunk_index, | |
220 size_t& lowest_non_clean_chunk_size); | |
221 | |
222 // Returns the number of chunks necessary to cover "mr". | |
223 size_t chunks_to_cover(MemRegion mr) { | |
224 return (size_t)(addr_to_chunk_index(mr.last()) - | |
225 addr_to_chunk_index(mr.start()) + 1); | |
226 } | |
227 | |
228 // Returns the index of the chunk in a stride which | |
229 // covers the given address. | |
230 uintptr_t addr_to_chunk_index(const void* addr) { | |
231 uintptr_t card = (uintptr_t) byte_for(addr); | |
232 return card / CardsPerStrideChunk; | |
233 } | |
234 | |
235 // Apply cl, which must either itself apply dcto_cl or be dcto_cl, | |
236 // to the cards in the stride (of n_strides) within the given space. | |
237 void process_stride(Space* sp, | |
238 MemRegion used, | |
239 jint stride, int n_strides, | |
240 DirtyCardToOopClosure* dcto_cl, | |
241 MemRegionClosure* cl, | |
242 bool clear, | |
243 jbyte** lowest_non_clean, | |
244 uintptr_t lowest_non_clean_base_chunk_index, | |
245 size_t lowest_non_clean_chunk_size); | |
246 | |
247 // Makes sure that chunk boundaries are handled appropriately, by | |
248 // adjusting the min_done of dcto_cl, and by using a special card-table | |
249 // value to indicate how min_done should be set. | |
250 void process_chunk_boundaries(Space* sp, | |
251 DirtyCardToOopClosure* dcto_cl, | |
252 MemRegion chunk_mr, | |
253 MemRegion used, | |
254 jbyte** lowest_non_clean, | |
255 uintptr_t lowest_non_clean_base_chunk_index, | |
256 size_t lowest_non_clean_chunk_size); | |
257 | |
258 public: | |
259 // Constants | |
260 enum SomePublicConstants { | |
261 card_shift = 9, | |
262 card_size = 1 << card_shift, | |
263 card_size_in_words = card_size / sizeof(HeapWord) | |
264 }; | |
265 | |
266 // For RTTI simulation. | |
267 BarrierSet::Name kind() { return BarrierSet::CardTableModRef; } | |
268 bool is_a(BarrierSet::Name bsn) { | |
269 return bsn == BarrierSet::CardTableModRef || bsn == BarrierSet::ModRef; | |
270 } | |
271 | |
272 CardTableModRefBS(MemRegion whole_heap, int max_covered_regions); | |
273 | |
274 // *** Barrier set functions. | |
275 | |
276 inline bool write_ref_needs_barrier(oop* field, oop new_val) { | |
277 // Note that this assumes the perm gen is the highest generation | |
278 // in the address space | |
279 return new_val != NULL && !new_val->is_perm(); | |
280 } | |
281 | |
282 // Record a reference update. Note that these versions are precise! | |
283 // The scanning code has to handle the fact that the write barrier may be | |
284 // either precise or imprecise. We make non-virtual inline variants of | |
285 // these functions here for performance. | |
286 protected: | |
287 void write_ref_field_work(oop obj, size_t offset, oop newVal); | |
288 void write_ref_field_work(oop* field, oop newVal); | |
289 public: | |
290 | |
291 bool has_write_ref_array_opt() { return true; } | |
292 bool has_write_region_opt() { return true; } | |
293 | |
294 inline void inline_write_region(MemRegion mr) { | |
295 dirty_MemRegion(mr); | |
296 } | |
297 protected: | |
298 void write_region_work(MemRegion mr) { | |
299 inline_write_region(mr); | |
300 } | |
301 public: | |
302 | |
303 inline void inline_write_ref_array(MemRegion mr) { | |
304 dirty_MemRegion(mr); | |
305 } | |
306 protected: | |
307 void write_ref_array_work(MemRegion mr) { | |
308 inline_write_ref_array(mr); | |
309 } | |
310 public: | |
311 | |
312 bool is_aligned(HeapWord* addr) { | |
313 return is_card_aligned(addr); | |
314 } | |
315 | |
316 // *** Card-table-barrier-specific things. | |
317 | |
318 inline void inline_write_ref_field(oop* field, oop newVal) { | |
319 jbyte* byte = byte_for(field); | |
320 *byte = dirty_card; | |
321 } | |
322 | |
323 // Card marking array base (adjusted for heap low boundary) | |
324 // This would be the 0th element of _byte_map, if the heap started at 0x0. | |
325 // But since the heap starts at some higher address, this points to somewhere | |
326 // before the beginning of the actual _byte_map. | |
327 jbyte* byte_map_base; | |
328 | |
329 // Return true if "p" is at the start of a card. | |
330 bool is_card_aligned(HeapWord* p) { | |
331 jbyte* pcard = byte_for(p); | |
332 return (addr_for(pcard) == p); | |
333 } | |
334 | |
335 // The kinds of precision a CardTableModRefBS may offer. | |
336 enum PrecisionStyle { | |
337 Precise, | |
338 ObjHeadPreciseArray | |
339 }; | |
340 | |
341 // Tells what style of precision this card table offers. | |
342 PrecisionStyle precision() { | |
343 return ObjHeadPreciseArray; // Only one supported for now. | |
344 } | |
345 | |
346 // ModRefBS functions. | |
347 void invalidate(MemRegion mr); | |
348 void clear(MemRegion mr); | |
349 void mod_oop_in_space_iterate(Space* sp, OopClosure* cl, | |
350 bool clear = false, | |
351 bool before_save_marks = false); | |
352 | |
353 // *** Card-table-RemSet-specific things. | |
354 | |
355 // Invoke "cl.do_MemRegion" on a set of MemRegions that collectively | |
356 // includes all the modified cards (expressing each card as a | |
357 // MemRegion). Thus, several modified cards may be lumped into one | |
358 // region. The regions are non-overlapping, and are visited in | |
359 // *decreasing* address order. (This order aids with imprecise card | |
360 // marking, where a dirty card may cause scanning, and summarization | |
361 // marking, of objects that extend onto subsequent cards.) | |
362 // If "clear" is true, the card is (conceptually) marked unmodified before | |
363 // applying the closure. | |
364 void mod_card_iterate(MemRegionClosure* cl, bool clear = false) { | |
365 non_clean_card_iterate_work(_whole_heap, cl, clear); | |
366 } | |
367 | |
368 // Like the "mod_cards_iterate" above, except only invokes the closure | |
369 // for cards within the MemRegion "mr" (which is required to be | |
370 // card-aligned and sized.) | |
371 void mod_card_iterate(MemRegion mr, MemRegionClosure* cl, | |
372 bool clear = false) { | |
373 non_clean_card_iterate_work(mr, cl, clear); | |
374 } | |
375 | |
376 static uintx ct_max_alignment_constraint(); | |
377 | |
378 // Apply closure cl to the dirty cards lying completely | |
379 // within MemRegion mr, setting the cards to precleaned. | |
380 void dirty_card_iterate(MemRegion mr, MemRegionClosure* cl); | |
381 | |
382 // Return the MemRegion corresponding to the first maximal run | |
383 // of dirty cards lying completely within MemRegion mr, after | |
384 // marking those cards precleaned. | |
385 MemRegion dirty_card_range_after_preclean(MemRegion mr); | |
386 | |
387 // Set all the dirty cards in the given region to precleaned state. | |
388 void preclean_dirty_cards(MemRegion mr); | |
389 | |
390 // Mapping from address to card marking array index. | |
391 int index_for(void* p) { | |
392 assert(_whole_heap.contains(p), | |
393 "out of bounds access to card marking array"); | |
394 return byte_for(p) - _byte_map; | |
395 } | |
396 | |
397 void verify(); | |
398 void verify_guard(); | |
399 | |
400 void verify_clean_region(MemRegion mr) PRODUCT_RETURN; | |
401 | |
402 static size_t par_chunk_heapword_alignment() { | |
403 return CardsPerStrideChunk * card_size_in_words; | |
404 } | |
405 }; | |
406 | |
407 class CardTableRS; | |
408 | |
409 // A specialization for the CardTableRS gen rem set. | |
410 class CardTableModRefBSForCTRS: public CardTableModRefBS { | |
411 CardTableRS* _rs; | |
412 protected: | |
413 bool card_will_be_scanned(jbyte cv); | |
414 bool card_may_have_been_dirty(jbyte cv); | |
415 public: | |
416 CardTableModRefBSForCTRS(MemRegion whole_heap, | |
417 int max_covered_regions) : | |
418 CardTableModRefBS(whole_heap, max_covered_regions) {} | |
419 | |
420 void set_CTRS(CardTableRS* rs) { _rs = rs; } | |
421 }; |