0
|
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 };
|