Mercurial > hg > graal-compiler
annotate src/share/vm/memory/cardTableModRefBS.hpp @ 1722:effb55808a18
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author | johnc |
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date | Wed, 18 Aug 2010 17:44:33 -0400 |
parents | d2ede61b7a12 |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
1692 | 2 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. 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 * | |
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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. |
0 | 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. | |
1692 | 47 friend class SharkBuilder; |
0 | 48 #ifndef PRODUCT |
49 // For debugging. | |
50 friend class GuaranteeNotModClosure; | |
51 #endif | |
52 protected: | |
53 | |
54 enum CardValues { | |
55 clean_card = -1, | |
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56 // The mask contains zeros in places for all other values. |
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57 clean_card_mask = clean_card - 31, |
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58 |
0 | 59 dirty_card = 0, |
60 precleaned_card = 1, | |
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61 claimed_card = 2, |
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62 deferred_card = 4, |
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63 last_card = 8, |
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64 CT_MR_BS_last_reserved = 16 |
0 | 65 }; |
66 | |
67 // dirty and precleaned are equivalent wrt younger_refs_iter. | |
68 static bool card_is_dirty_wrt_gen_iter(jbyte cv) { | |
69 return cv == dirty_card || cv == precleaned_card; | |
70 } | |
71 | |
72 // Returns "true" iff the value "cv" will cause the card containing it | |
73 // to be scanned in the current traversal. May be overridden by | |
74 // subtypes. | |
75 virtual bool card_will_be_scanned(jbyte cv) { | |
76 return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv); | |
77 } | |
78 | |
79 // Returns "true" iff the value "cv" may have represented a dirty card at | |
80 // some point. | |
81 virtual bool card_may_have_been_dirty(jbyte cv) { | |
82 return card_is_dirty_wrt_gen_iter(cv); | |
83 } | |
84 | |
85 // The declaration order of these const fields is important; see the | |
86 // constructor before changing. | |
87 const MemRegion _whole_heap; // the region covered by the card table | |
88 const size_t _guard_index; // index of very last element in the card | |
89 // table; it is set to a guard value | |
90 // (last_card) and should never be modified | |
91 const size_t _last_valid_index; // index of the last valid element | |
92 const size_t _page_size; // page size used when mapping _byte_map | |
93 const size_t _byte_map_size; // in bytes | |
94 jbyte* _byte_map; // the card marking array | |
95 | |
96 int _cur_covered_regions; | |
97 // The covered regions should be in address order. | |
98 MemRegion* _covered; | |
99 // The committed regions correspond one-to-one to the covered regions. | |
100 // They represent the card-table memory that has been committed to service | |
101 // the corresponding covered region. It may be that committed region for | |
102 // one covered region corresponds to a larger region because of page-size | |
103 // roundings. Thus, a committed region for one covered region may | |
104 // actually extend onto the card-table space for the next covered region. | |
105 MemRegion* _committed; | |
106 | |
107 // The last card is a guard card, and we commit the page for it so | |
108 // we can use the card for verification purposes. We make sure we never | |
109 // uncommit the MemRegion for that page. | |
110 MemRegion _guard_region; | |
111 | |
112 protected: | |
113 // Initialization utilities; covered_words is the size of the covered region | |
114 // in, um, words. | |
115 inline size_t cards_required(size_t covered_words); | |
116 inline size_t compute_byte_map_size(); | |
117 | |
118 // Finds and return the index of the region, if any, to which the given | |
119 // region would be contiguous. If none exists, assign a new region and | |
120 // returns its index. Requires that no more than the maximum number of | |
121 // covered regions defined in the constructor are ever in use. | |
122 int find_covering_region_by_base(HeapWord* base); | |
123 | |
124 // Same as above, but finds the region containing the given address | |
125 // instead of starting at a given base address. | |
126 int find_covering_region_containing(HeapWord* addr); | |
127 | |
128 // Resize one of the regions covered by the remembered set. | |
129 void resize_covered_region(MemRegion new_region); | |
130 | |
131 // Returns the leftmost end of a committed region corresponding to a | |
132 // covered region before covered region "ind", or else "NULL" if "ind" is | |
133 // the first covered region. | |
134 HeapWord* largest_prev_committed_end(int ind) const; | |
135 | |
136 // Returns the part of the region mr that doesn't intersect with | |
137 // any committed region other than self. Used to prevent uncommitting | |
138 // regions that are also committed by other regions. Also protects | |
139 // against uncommitting the guard region. | |
140 MemRegion committed_unique_to_self(int self, MemRegion mr) const; | |
141 | |
142 // Mapping from address to card marking array entry | |
143 jbyte* byte_for(const void* p) const { | |
144 assert(_whole_heap.contains(p), | |
145 "out of bounds access to card marking array"); | |
146 jbyte* result = &byte_map_base[uintptr_t(p) >> card_shift]; | |
147 assert(result >= _byte_map && result < _byte_map + _byte_map_size, | |
148 "out of bounds accessor for card marking array"); | |
149 return result; | |
150 } | |
151 | |
152 // The card table byte one after the card marking array | |
153 // entry for argument address. Typically used for higher bounds | |
154 // for loops iterating through the card table. | |
155 jbyte* byte_after(const void* p) const { | |
156 return byte_for(p) + 1; | |
157 } | |
158 | |
159 // Iterate over the portion of the card-table which covers the given | |
160 // region mr in the given space and apply cl to any dirty sub-regions | |
161 // of mr. cl and dcto_cl must either be the same closure or cl must | |
162 // wrap dcto_cl. Both are required - neither may be NULL. Also, dcto_cl | |
163 // may be modified. Note that this function will operate in a parallel | |
164 // mode if worker threads are available. | |
165 void non_clean_card_iterate(Space* sp, MemRegion mr, | |
166 DirtyCardToOopClosure* dcto_cl, | |
167 MemRegionClosure* cl, | |
168 bool clear); | |
169 | |
170 // Utility function used to implement the other versions below. | |
171 void non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl, | |
172 bool clear); | |
173 | |
174 void par_non_clean_card_iterate_work(Space* sp, MemRegion mr, | |
175 DirtyCardToOopClosure* dcto_cl, | |
176 MemRegionClosure* cl, | |
177 bool clear, | |
178 int n_threads); | |
179 | |
180 // Dirty the bytes corresponding to "mr" (not all of which must be | |
181 // covered.) | |
182 void dirty_MemRegion(MemRegion mr); | |
183 | |
184 // Clear (to clean_card) the bytes entirely contained within "mr" (not | |
185 // all of which must be covered.) | |
186 void clear_MemRegion(MemRegion mr); | |
187 | |
188 // *** Support for parallel card scanning. | |
189 | |
190 enum SomeConstantsForParallelism { | |
191 StridesPerThread = 2, | |
192 CardsPerStrideChunk = 256 | |
193 }; | |
194 | |
195 // This is an array, one element per covered region of the card table. | |
196 // Each entry is itself an array, with one element per chunk in the | |
197 // covered region. Each entry of these arrays is the lowest non-clean | |
198 // card of the corresponding chunk containing part of an object from the | |
199 // previous chunk, or else NULL. | |
200 typedef jbyte* CardPtr; | |
201 typedef CardPtr* CardArr; | |
202 CardArr* _lowest_non_clean; | |
203 size_t* _lowest_non_clean_chunk_size; | |
204 uintptr_t* _lowest_non_clean_base_chunk_index; | |
205 int* _last_LNC_resizing_collection; | |
206 | |
207 // Initializes "lowest_non_clean" to point to the array for the region | |
208 // covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk | |
209 // index of the corresponding to the first element of that array. | |
210 // Ensures that these arrays are of sufficient size, allocating if necessary. | |
211 // May be called by several threads concurrently. | |
212 void get_LNC_array_for_space(Space* sp, | |
213 jbyte**& lowest_non_clean, | |
214 uintptr_t& lowest_non_clean_base_chunk_index, | |
215 size_t& lowest_non_clean_chunk_size); | |
216 | |
217 // Returns the number of chunks necessary to cover "mr". | |
218 size_t chunks_to_cover(MemRegion mr) { | |
219 return (size_t)(addr_to_chunk_index(mr.last()) - | |
220 addr_to_chunk_index(mr.start()) + 1); | |
221 } | |
222 | |
223 // Returns the index of the chunk in a stride which | |
224 // covers the given address. | |
225 uintptr_t addr_to_chunk_index(const void* addr) { | |
226 uintptr_t card = (uintptr_t) byte_for(addr); | |
227 return card / CardsPerStrideChunk; | |
228 } | |
229 | |
230 // Apply cl, which must either itself apply dcto_cl or be dcto_cl, | |
231 // to the cards in the stride (of n_strides) within the given space. | |
232 void process_stride(Space* sp, | |
233 MemRegion used, | |
234 jint stride, int n_strides, | |
235 DirtyCardToOopClosure* dcto_cl, | |
236 MemRegionClosure* cl, | |
237 bool clear, | |
238 jbyte** lowest_non_clean, | |
239 uintptr_t lowest_non_clean_base_chunk_index, | |
240 size_t lowest_non_clean_chunk_size); | |
241 | |
242 // Makes sure that chunk boundaries are handled appropriately, by | |
243 // adjusting the min_done of dcto_cl, and by using a special card-table | |
244 // value to indicate how min_done should be set. | |
245 void process_chunk_boundaries(Space* sp, | |
246 DirtyCardToOopClosure* dcto_cl, | |
247 MemRegion chunk_mr, | |
248 MemRegion used, | |
249 jbyte** lowest_non_clean, | |
250 uintptr_t lowest_non_clean_base_chunk_index, | |
251 size_t lowest_non_clean_chunk_size); | |
252 | |
253 public: | |
254 // Constants | |
255 enum SomePublicConstants { | |
256 card_shift = 9, | |
257 card_size = 1 << card_shift, | |
258 card_size_in_words = card_size / sizeof(HeapWord) | |
259 }; | |
260 | |
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261 static int clean_card_val() { return clean_card; } |
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262 static int clean_card_mask_val() { return clean_card_mask; } |
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263 static int dirty_card_val() { return dirty_card; } |
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264 static int claimed_card_val() { return claimed_card; } |
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265 static int precleaned_card_val() { return precleaned_card; } |
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266 static int deferred_card_val() { return deferred_card; } |
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267 |
0 | 268 // For RTTI simulation. |
269 bool is_a(BarrierSet::Name bsn) { | |
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270 return bsn == BarrierSet::CardTableModRef || ModRefBarrierSet::is_a(bsn); |
0 | 271 } |
272 | |
273 CardTableModRefBS(MemRegion whole_heap, int max_covered_regions); | |
274 | |
275 // *** Barrier set functions. | |
276 | |
342
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277 bool has_write_ref_pre_barrier() { return false; } |
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278 |
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279 inline bool write_ref_needs_barrier(void* field, oop new_val) { |
0 | 280 // Note that this assumes the perm gen is the highest generation |
281 // in the address space | |
282 return new_val != NULL && !new_val->is_perm(); | |
283 } | |
284 | |
285 // Record a reference update. Note that these versions are precise! | |
286 // The scanning code has to handle the fact that the write barrier may be | |
287 // either precise or imprecise. We make non-virtual inline variants of | |
288 // these functions here for performance. | |
289 protected: | |
290 void write_ref_field_work(oop obj, size_t offset, oop newVal); | |
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291 virtual void write_ref_field_work(void* field, oop newVal); |
0 | 292 public: |
293 | |
294 bool has_write_ref_array_opt() { return true; } | |
295 bool has_write_region_opt() { return true; } | |
296 | |
297 inline void inline_write_region(MemRegion mr) { | |
298 dirty_MemRegion(mr); | |
299 } | |
300 protected: | |
301 void write_region_work(MemRegion mr) { | |
302 inline_write_region(mr); | |
303 } | |
304 public: | |
305 | |
306 inline void inline_write_ref_array(MemRegion mr) { | |
307 dirty_MemRegion(mr); | |
308 } | |
309 protected: | |
310 void write_ref_array_work(MemRegion mr) { | |
311 inline_write_ref_array(mr); | |
312 } | |
313 public: | |
314 | |
315 bool is_aligned(HeapWord* addr) { | |
316 return is_card_aligned(addr); | |
317 } | |
318 | |
319 // *** Card-table-barrier-specific things. | |
320 | |
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321 template <class T> inline void inline_write_ref_field_pre(T* field, oop newVal) {} |
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322 |
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323 template <class T> inline void inline_write_ref_field(T* field, oop newVal) { |
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324 jbyte* byte = byte_for((void*)field); |
0 | 325 *byte = dirty_card; |
326 } | |
327 | |
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328 // These are used by G1, when it uses the card table as a temporary data |
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329 // structure for card claiming. |
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330 bool is_card_dirty(size_t card_index) { |
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331 return _byte_map[card_index] == dirty_card_val(); |
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332 } |
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333 |
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334 void mark_card_dirty(size_t card_index) { |
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335 _byte_map[card_index] = dirty_card_val(); |
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336 } |
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337 |
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338 bool is_card_claimed(size_t card_index) { |
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339 jbyte val = _byte_map[card_index]; |
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340 return (val & (clean_card_mask_val() | claimed_card_val())) == claimed_card_val(); |
342
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341 } |
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342 |
1261 | 343 void set_card_claimed(size_t card_index) { |
344 jbyte val = _byte_map[card_index]; | |
345 if (val == clean_card_val()) { | |
346 val = (jbyte)claimed_card_val(); | |
347 } else { | |
348 val |= (jbyte)claimed_card_val(); | |
349 } | |
350 _byte_map[card_index] = val; | |
351 } | |
352 | |
342
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353 bool claim_card(size_t card_index); |
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354 |
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355 bool is_card_clean(size_t card_index) { |
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356 return _byte_map[card_index] == clean_card_val(); |
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357 } |
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358 |
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359 bool is_card_deferred(size_t card_index) { |
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360 jbyte val = _byte_map[card_index]; |
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361 return (val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val(); |
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362 } |
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363 |
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364 bool mark_card_deferred(size_t card_index); |
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365 |
0 | 366 // Card marking array base (adjusted for heap low boundary) |
367 // This would be the 0th element of _byte_map, if the heap started at 0x0. | |
368 // But since the heap starts at some higher address, this points to somewhere | |
369 // before the beginning of the actual _byte_map. | |
370 jbyte* byte_map_base; | |
371 | |
372 // Return true if "p" is at the start of a card. | |
373 bool is_card_aligned(HeapWord* p) { | |
374 jbyte* pcard = byte_for(p); | |
375 return (addr_for(pcard) == p); | |
376 } | |
377 | |
378 // The kinds of precision a CardTableModRefBS may offer. | |
379 enum PrecisionStyle { | |
380 Precise, | |
381 ObjHeadPreciseArray | |
382 }; | |
383 | |
384 // Tells what style of precision this card table offers. | |
385 PrecisionStyle precision() { | |
386 return ObjHeadPreciseArray; // Only one supported for now. | |
387 } | |
388 | |
389 // ModRefBS functions. | |
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390 virtual void invalidate(MemRegion mr, bool whole_heap = false); |
0 | 391 void clear(MemRegion mr); |
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392 void dirty(MemRegion mr); |
0 | 393 void mod_oop_in_space_iterate(Space* sp, OopClosure* cl, |
394 bool clear = false, | |
395 bool before_save_marks = false); | |
396 | |
397 // *** Card-table-RemSet-specific things. | |
398 | |
399 // Invoke "cl.do_MemRegion" on a set of MemRegions that collectively | |
400 // includes all the modified cards (expressing each card as a | |
401 // MemRegion). Thus, several modified cards may be lumped into one | |
402 // region. The regions are non-overlapping, and are visited in | |
403 // *decreasing* address order. (This order aids with imprecise card | |
404 // marking, where a dirty card may cause scanning, and summarization | |
405 // marking, of objects that extend onto subsequent cards.) | |
406 // If "clear" is true, the card is (conceptually) marked unmodified before | |
407 // applying the closure. | |
408 void mod_card_iterate(MemRegionClosure* cl, bool clear = false) { | |
409 non_clean_card_iterate_work(_whole_heap, cl, clear); | |
410 } | |
411 | |
412 // Like the "mod_cards_iterate" above, except only invokes the closure | |
413 // for cards within the MemRegion "mr" (which is required to be | |
414 // card-aligned and sized.) | |
415 void mod_card_iterate(MemRegion mr, MemRegionClosure* cl, | |
416 bool clear = false) { | |
417 non_clean_card_iterate_work(mr, cl, clear); | |
418 } | |
419 | |
420 static uintx ct_max_alignment_constraint(); | |
421 | |
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422 // Apply closure "cl" to the dirty cards containing some part of |
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423 // MemRegion "mr". |
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424 void dirty_card_iterate(MemRegion mr, MemRegionClosure* cl); |
0 | 425 |
426 // Return the MemRegion corresponding to the first maximal run | |
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427 // of dirty cards lying completely within MemRegion mr. |
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428 // If reset is "true", then sets those card table entries to the given |
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429 // value. |
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430 MemRegion dirty_card_range_after_reset(MemRegion mr, bool reset, |
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431 int reset_val); |
0 | 432 |
433 // Set all the dirty cards in the given region to precleaned state. | |
434 void preclean_dirty_cards(MemRegion mr); | |
435 | |
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436 // Provide read-only access to the card table array. |
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437 const jbyte* byte_for_const(const void* p) const { |
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438 return byte_for(p); |
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439 } |
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440 const jbyte* byte_after_const(const void* p) const { |
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441 return byte_after(p); |
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442 } |
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443 |
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444 // Mapping from card marking array entry to address of first word |
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445 HeapWord* addr_for(const jbyte* p) const { |
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446 assert(p >= _byte_map && p < _byte_map + _byte_map_size, |
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447 "out of bounds access to card marking array"); |
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448 size_t delta = pointer_delta(p, byte_map_base, sizeof(jbyte)); |
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449 HeapWord* result = (HeapWord*) (delta << card_shift); |
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450 assert(_whole_heap.contains(result), |
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451 "out of bounds accessor from card marking array"); |
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452 return result; |
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453 } |
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454 |
0 | 455 // Mapping from address to card marking array index. |
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456 size_t index_for(void* p) { |
0 | 457 assert(_whole_heap.contains(p), |
458 "out of bounds access to card marking array"); | |
459 return byte_for(p) - _byte_map; | |
460 } | |
461 | |
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462 const jbyte* byte_for_index(const size_t card_index) const { |
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463 return _byte_map + card_index; |
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464 } |
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465 |
0 | 466 void verify(); |
467 void verify_guard(); | |
468 | |
469 void verify_clean_region(MemRegion mr) PRODUCT_RETURN; | |
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470 void verify_dirty_region(MemRegion mr) PRODUCT_RETURN; |
0 | 471 |
472 static size_t par_chunk_heapword_alignment() { | |
473 return CardsPerStrideChunk * card_size_in_words; | |
474 } | |
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475 |
0 | 476 }; |
477 | |
478 class CardTableRS; | |
479 | |
480 // A specialization for the CardTableRS gen rem set. | |
481 class CardTableModRefBSForCTRS: public CardTableModRefBS { | |
482 CardTableRS* _rs; | |
483 protected: | |
484 bool card_will_be_scanned(jbyte cv); | |
485 bool card_may_have_been_dirty(jbyte cv); | |
486 public: | |
487 CardTableModRefBSForCTRS(MemRegion whole_heap, | |
488 int max_covered_regions) : | |
489 CardTableModRefBS(whole_heap, max_covered_regions) {} | |
490 | |
491 void set_CTRS(CardTableRS* rs) { _rs = rs; } | |
492 }; |