Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp @ 2951:0c0e407faa39
another fix to debug info (on-stack parameters), DCE removes unnecessary merges and LoopBegins whose LoopEnd went away
author | Lukas Stadler <lukas.stadler@jku.at> |
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date | Tue, 14 Jun 2011 16:47:31 +0200 |
parents | f95d63e2154a |
children | bca17e38de00 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2001, 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 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp" | |
27 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" | |
28 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" | |
29 #include "gc_implementation/parallelScavenge/psTasks.hpp" | |
30 #include "gc_implementation/parallelScavenge/psYoungGen.hpp" | |
31 #include "oops/oop.inline.hpp" | |
32 #include "oops/oop.psgc.inline.hpp" | |
0 | 33 |
34 // Checks an individual oop for missing precise marks. Mark | |
35 // may be either dirty or newgen. | |
36 class CheckForUnmarkedOops : public OopClosure { | |
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37 private: |
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38 PSYoungGen* _young_gen; |
0 | 39 CardTableExtension* _card_table; |
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40 HeapWord* _unmarked_addr; |
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41 jbyte* _unmarked_card; |
0 | 42 |
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43 protected: |
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44 template <class T> void do_oop_work(T* p) { |
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45 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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46 if (_young_gen->is_in_reserved(obj) && |
0 | 47 !_card_table->addr_is_marked_imprecise(p)) { |
48 // Don't overwrite the first missing card mark | |
49 if (_unmarked_addr == NULL) { | |
50 _unmarked_addr = (HeapWord*)p; | |
51 _unmarked_card = _card_table->byte_for(p); | |
52 } | |
53 } | |
54 } | |
55 | |
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56 public: |
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57 CheckForUnmarkedOops(PSYoungGen* young_gen, CardTableExtension* card_table) : |
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58 _young_gen(young_gen), _card_table(card_table), _unmarked_addr(NULL) { } |
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59 |
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60 virtual void do_oop(oop* p) { CheckForUnmarkedOops::do_oop_work(p); } |
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61 virtual void do_oop(narrowOop* p) { CheckForUnmarkedOops::do_oop_work(p); } |
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62 |
0 | 63 bool has_unmarked_oop() { |
64 return _unmarked_addr != NULL; | |
65 } | |
66 }; | |
67 | |
68 // Checks all objects for the existance of some type of mark, | |
69 // precise or imprecise, dirty or newgen. | |
70 class CheckForUnmarkedObjects : public ObjectClosure { | |
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71 private: |
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72 PSYoungGen* _young_gen; |
0 | 73 CardTableExtension* _card_table; |
74 | |
75 public: | |
76 CheckForUnmarkedObjects() { | |
77 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
78 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
79 | |
80 _young_gen = heap->young_gen(); | |
81 _card_table = (CardTableExtension*)heap->barrier_set(); | |
82 // No point in asserting barrier set type here. Need to make CardTableExtension | |
83 // a unique barrier set type. | |
84 } | |
85 | |
86 // Card marks are not precise. The current system can leave us with | |
605 | 87 // a mismash of precise marks and beginning of object marks. This means |
0 | 88 // we test for missing precise marks first. If any are found, we don't |
89 // fail unless the object head is also unmarked. | |
90 virtual void do_object(oop obj) { | |
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91 CheckForUnmarkedOops object_check(_young_gen, _card_table); |
0 | 92 obj->oop_iterate(&object_check); |
93 if (object_check.has_unmarked_oop()) { | |
94 assert(_card_table->addr_is_marked_imprecise(obj), "Found unmarked young_gen object"); | |
95 } | |
96 } | |
97 }; | |
98 | |
99 // Checks for precise marking of oops as newgen. | |
100 class CheckForPreciseMarks : public OopClosure { | |
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101 private: |
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102 PSYoungGen* _young_gen; |
0 | 103 CardTableExtension* _card_table; |
104 | |
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105 protected: |
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106 template <class T> void do_oop_work(T* p) { |
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107 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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108 if (_young_gen->is_in_reserved(obj)) { |
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109 assert(_card_table->addr_is_marked_precise(p), "Found unmarked precise oop"); |
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110 _card_table->set_card_newgen(p); |
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111 } |
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112 } |
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113 |
0 | 114 public: |
115 CheckForPreciseMarks( PSYoungGen* young_gen, CardTableExtension* card_table ) : | |
116 _young_gen(young_gen), _card_table(card_table) { } | |
117 | |
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118 virtual void do_oop(oop* p) { CheckForPreciseMarks::do_oop_work(p); } |
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119 virtual void do_oop(narrowOop* p) { CheckForPreciseMarks::do_oop_work(p); } |
0 | 120 }; |
121 | |
122 // We get passed the space_top value to prevent us from traversing into | |
123 // the old_gen promotion labs, which cannot be safely parsed. | |
124 void CardTableExtension::scavenge_contents(ObjectStartArray* start_array, | |
125 MutableSpace* sp, | |
126 HeapWord* space_top, | |
127 PSPromotionManager* pm) | |
128 { | |
129 assert(start_array != NULL && sp != NULL && pm != NULL, "Sanity"); | |
130 assert(start_array->covered_region().contains(sp->used_region()), | |
131 "ObjectStartArray does not cover space"); | |
132 | |
133 if (sp->not_empty()) { | |
134 oop* sp_top = (oop*)space_top; | |
135 oop* prev_top = NULL; | |
136 jbyte* current_card = byte_for(sp->bottom()); | |
137 jbyte* end_card = byte_for(sp_top - 1); // sp_top is exclusive | |
138 // scan card marking array | |
139 while (current_card <= end_card) { | |
140 jbyte value = *current_card; | |
141 // skip clean cards | |
142 if (card_is_clean(value)) { | |
143 current_card++; | |
144 } else { | |
145 // we found a non-clean card | |
146 jbyte* first_nonclean_card = current_card++; | |
147 oop* bottom = (oop*)addr_for(first_nonclean_card); | |
148 // find object starting on card | |
149 oop* bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom); | |
150 // bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom); | |
151 assert(bottom_obj <= bottom, "just checking"); | |
152 // make sure we don't scan oops we already looked at | |
153 if (bottom < prev_top) bottom = prev_top; | |
154 // figure out when to stop scanning | |
155 jbyte* first_clean_card; | |
156 oop* top; | |
157 bool restart_scanning; | |
158 do { | |
159 restart_scanning = false; | |
160 // find a clean card | |
161 while (current_card <= end_card) { | |
162 value = *current_card; | |
163 if (card_is_clean(value)) break; | |
164 current_card++; | |
165 } | |
166 // check if we reached the end, if so we are done | |
167 if (current_card >= end_card) { | |
168 first_clean_card = end_card + 1; | |
169 current_card++; | |
170 top = sp_top; | |
171 } else { | |
172 // we have a clean card, find object starting on that card | |
173 first_clean_card = current_card++; | |
174 top = (oop*)addr_for(first_clean_card); | |
175 oop* top_obj = (oop*)start_array->object_start((HeapWord*)top); | |
176 // top_obj = (oop*)start_array->object_start((HeapWord*)top); | |
177 assert(top_obj <= top, "just checking"); | |
178 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { | |
179 // an arrayOop is starting on the clean card - since we do exact store | |
180 // checks for objArrays we are done | |
181 } else { | |
182 // otherwise, it is possible that the object starting on the clean card | |
183 // spans the entire card, and that the store happened on a later card. | |
184 // figure out where the object ends | |
185 top = top_obj + oop(top_obj)->size(); | |
186 jbyte* top_card = CardTableModRefBS::byte_for(top - 1); // top is exclusive | |
187 if (top_card > first_clean_card) { | |
188 // object ends a different card | |
189 current_card = top_card + 1; | |
190 if (card_is_clean(*top_card)) { | |
191 // the ending card is clean, we are done | |
192 first_clean_card = top_card; | |
193 } else { | |
194 // the ending card is not clean, continue scanning at start of do-while | |
195 restart_scanning = true; | |
196 } | |
197 } else { | |
198 // object ends on the clean card, we are done. | |
199 assert(first_clean_card == top_card, "just checking"); | |
200 } | |
201 } | |
202 } | |
203 } while (restart_scanning); | |
204 // we know which cards to scan, now clear them | |
205 while (first_nonclean_card < first_clean_card) { | |
206 *first_nonclean_card++ = clean_card; | |
207 } | |
208 // scan oops in objects | |
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209 do { |
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210 oop(bottom_obj)->push_contents(pm); |
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211 bottom_obj += oop(bottom_obj)->size(); |
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212 assert(bottom_obj <= sp_top, "just checking"); |
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213 } while (bottom_obj < top); |
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214 pm->drain_stacks_cond_depth(); |
0 | 215 // remember top oop* scanned |
216 prev_top = top; | |
217 } | |
218 } | |
219 } | |
220 } | |
221 | |
222 void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array, | |
223 MutableSpace* sp, | |
224 HeapWord* space_top, | |
225 PSPromotionManager* pm, | |
226 uint stripe_number) { | |
227 int ssize = 128; // Naked constant! Work unit = 64k. | |
228 int dirty_card_count = 0; | |
229 | |
230 oop* sp_top = (oop*)space_top; | |
231 jbyte* start_card = byte_for(sp->bottom()); | |
232 jbyte* end_card = byte_for(sp_top - 1) + 1; | |
233 oop* last_scanned = NULL; // Prevent scanning objects more than once | |
234 for (jbyte* slice = start_card; slice < end_card; slice += ssize*ParallelGCThreads) { | |
235 jbyte* worker_start_card = slice + stripe_number * ssize; | |
236 if (worker_start_card >= end_card) | |
237 return; // We're done. | |
238 | |
239 jbyte* worker_end_card = worker_start_card + ssize; | |
240 if (worker_end_card > end_card) | |
241 worker_end_card = end_card; | |
242 | |
243 // We do not want to scan objects more than once. In order to accomplish | |
244 // this, we assert that any object with an object head inside our 'slice' | |
245 // belongs to us. We may need to extend the range of scanned cards if the | |
246 // last object continues into the next 'slice'. | |
247 // | |
248 // Note! ending cards are exclusive! | |
249 HeapWord* slice_start = addr_for(worker_start_card); | |
250 HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card)); | |
251 | |
252 // If there are not objects starting within the chunk, skip it. | |
253 if (!start_array->object_starts_in_range(slice_start, slice_end)) { | |
254 continue; | |
255 } | |
605 | 256 // Update our beginning addr |
0 | 257 HeapWord* first_object = start_array->object_start(slice_start); |
258 debug_only(oop* first_object_within_slice = (oop*) first_object;) | |
259 if (first_object < slice_start) { | |
260 last_scanned = (oop*)(first_object + oop(first_object)->size()); | |
261 debug_only(first_object_within_slice = last_scanned;) | |
262 worker_start_card = byte_for(last_scanned); | |
263 } | |
264 | |
265 // Update the ending addr | |
266 if (slice_end < (HeapWord*)sp_top) { | |
267 // The subtraction is important! An object may start precisely at slice_end. | |
268 HeapWord* last_object = start_array->object_start(slice_end - 1); | |
269 slice_end = last_object + oop(last_object)->size(); | |
270 // worker_end_card is exclusive, so bump it one past the end of last_object's | |
271 // covered span. | |
272 worker_end_card = byte_for(slice_end) + 1; | |
273 | |
274 if (worker_end_card > end_card) | |
275 worker_end_card = end_card; | |
276 } | |
277 | |
278 assert(slice_end <= (HeapWord*)sp_top, "Last object in slice crosses space boundary"); | |
279 assert(is_valid_card_address(worker_start_card), "Invalid worker start card"); | |
280 assert(is_valid_card_address(worker_end_card), "Invalid worker end card"); | |
281 // Note that worker_start_card >= worker_end_card is legal, and happens when | |
282 // an object spans an entire slice. | |
283 assert(worker_start_card <= end_card, "worker start card beyond end card"); | |
284 assert(worker_end_card <= end_card, "worker end card beyond end card"); | |
285 | |
286 jbyte* current_card = worker_start_card; | |
287 while (current_card < worker_end_card) { | |
288 // Find an unclean card. | |
289 while (current_card < worker_end_card && card_is_clean(*current_card)) { | |
290 current_card++; | |
291 } | |
292 jbyte* first_unclean_card = current_card; | |
293 | |
294 // Find the end of a run of contiguous unclean cards | |
295 while (current_card < worker_end_card && !card_is_clean(*current_card)) { | |
296 while (current_card < worker_end_card && !card_is_clean(*current_card)) { | |
297 current_card++; | |
298 } | |
299 | |
300 if (current_card < worker_end_card) { | |
301 // Some objects may be large enough to span several cards. If such | |
302 // an object has more than one dirty card, separated by a clean card, | |
303 // we will attempt to scan it twice. The test against "last_scanned" | |
304 // prevents the redundant object scan, but it does not prevent newly | |
305 // marked cards from being cleaned. | |
306 HeapWord* last_object_in_dirty_region = start_array->object_start(addr_for(current_card)-1); | |
307 size_t size_of_last_object = oop(last_object_in_dirty_region)->size(); | |
308 HeapWord* end_of_last_object = last_object_in_dirty_region + size_of_last_object; | |
309 jbyte* ending_card_of_last_object = byte_for(end_of_last_object); | |
310 assert(ending_card_of_last_object <= worker_end_card, "ending_card_of_last_object is greater than worker_end_card"); | |
311 if (ending_card_of_last_object > current_card) { | |
312 // This means the object spans the next complete card. | |
313 // We need to bump the current_card to ending_card_of_last_object | |
314 current_card = ending_card_of_last_object; | |
315 } | |
316 } | |
317 } | |
318 jbyte* following_clean_card = current_card; | |
319 | |
320 if (first_unclean_card < worker_end_card) { | |
321 oop* p = (oop*) start_array->object_start(addr_for(first_unclean_card)); | |
322 assert((HeapWord*)p <= addr_for(first_unclean_card), "checking"); | |
323 // "p" should always be >= "last_scanned" because newly GC dirtied | |
324 // cards are no longer scanned again (see comment at end | |
325 // of loop on the increment of "current_card"). Test that | |
326 // hypothesis before removing this code. | |
327 // If this code is removed, deal with the first time through | |
328 // the loop when the last_scanned is the object starting in | |
329 // the previous slice. | |
330 assert((p >= last_scanned) || | |
331 (last_scanned == first_object_within_slice), | |
332 "Should no longer be possible"); | |
333 if (p < last_scanned) { | |
334 // Avoid scanning more than once; this can happen because | |
335 // newgen cards set by GC may a different set than the | |
336 // originally dirty set | |
337 p = last_scanned; | |
338 } | |
339 oop* to = (oop*)addr_for(following_clean_card); | |
340 | |
341 // Test slice_end first! | |
342 if ((HeapWord*)to > slice_end) { | |
343 to = (oop*)slice_end; | |
344 } else if (to > sp_top) { | |
345 to = sp_top; | |
346 } | |
347 | |
348 // we know which cards to scan, now clear them | |
349 if (first_unclean_card <= worker_start_card+1) | |
350 first_unclean_card = worker_start_card+1; | |
351 if (following_clean_card >= worker_end_card-1) | |
352 following_clean_card = worker_end_card-1; | |
353 | |
354 while (first_unclean_card < following_clean_card) { | |
355 *first_unclean_card++ = clean_card; | |
356 } | |
357 | |
358 const int interval = PrefetchScanIntervalInBytes; | |
359 // scan all objects in the range | |
360 if (interval != 0) { | |
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361 while (p < to) { |
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362 Prefetch::write(p, interval); |
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363 oop m = oop(p); |
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364 assert(m->is_oop_or_null(), "check for header"); |
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365 m->push_contents(pm); |
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366 p += m->size(); |
0 | 367 } |
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368 pm->drain_stacks_cond_depth(); |
0 | 369 } else { |
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370 while (p < to) { |
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371 oop m = oop(p); |
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372 assert(m->is_oop_or_null(), "check for header"); |
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373 m->push_contents(pm); |
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374 p += m->size(); |
0 | 375 } |
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376 pm->drain_stacks_cond_depth(); |
0 | 377 } |
378 last_scanned = p; | |
379 } | |
380 // "current_card" is still the "following_clean_card" or | |
381 // the current_card is >= the worker_end_card so the | |
382 // loop will not execute again. | |
383 assert((current_card == following_clean_card) || | |
384 (current_card >= worker_end_card), | |
385 "current_card should only be incremented if it still equals " | |
386 "following_clean_card"); | |
387 // Increment current_card so that it is not processed again. | |
388 // It may now be dirty because a old-to-young pointer was | |
389 // found on it an updated. If it is now dirty, it cannot be | |
390 // be safely cleaned in the next iteration. | |
391 current_card++; | |
392 } | |
393 } | |
394 } | |
395 | |
396 // This should be called before a scavenge. | |
397 void CardTableExtension::verify_all_young_refs_imprecise() { | |
398 CheckForUnmarkedObjects check; | |
399 | |
400 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
401 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
402 | |
403 PSOldGen* old_gen = heap->old_gen(); | |
404 PSPermGen* perm_gen = heap->perm_gen(); | |
405 | |
406 old_gen->object_iterate(&check); | |
407 perm_gen->object_iterate(&check); | |
408 } | |
409 | |
410 // This should be called immediately after a scavenge, before mutators resume. | |
411 void CardTableExtension::verify_all_young_refs_precise() { | |
412 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
413 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
414 | |
415 PSOldGen* old_gen = heap->old_gen(); | |
416 PSPermGen* perm_gen = heap->perm_gen(); | |
417 | |
418 CheckForPreciseMarks check(heap->young_gen(), (CardTableExtension*)heap->barrier_set()); | |
419 | |
420 old_gen->oop_iterate(&check); | |
421 perm_gen->oop_iterate(&check); | |
422 | |
423 verify_all_young_refs_precise_helper(old_gen->object_space()->used_region()); | |
424 verify_all_young_refs_precise_helper(perm_gen->object_space()->used_region()); | |
425 } | |
426 | |
427 void CardTableExtension::verify_all_young_refs_precise_helper(MemRegion mr) { | |
428 CardTableExtension* card_table = (CardTableExtension*)Universe::heap()->barrier_set(); | |
429 // FIX ME ASSERT HERE | |
430 | |
431 jbyte* bot = card_table->byte_for(mr.start()); | |
432 jbyte* top = card_table->byte_for(mr.end()); | |
433 while(bot <= top) { | |
434 assert(*bot == clean_card || *bot == verify_card, "Found unwanted or unknown card mark"); | |
435 if (*bot == verify_card) | |
436 *bot = youngergen_card; | |
437 bot++; | |
438 } | |
439 } | |
440 | |
441 bool CardTableExtension::addr_is_marked_imprecise(void *addr) { | |
442 jbyte* p = byte_for(addr); | |
443 jbyte val = *p; | |
444 | |
445 if (card_is_dirty(val)) | |
446 return true; | |
447 | |
448 if (card_is_newgen(val)) | |
449 return true; | |
450 | |
451 if (card_is_clean(val)) | |
452 return false; | |
453 | |
454 assert(false, "Found unhandled card mark type"); | |
455 | |
456 return false; | |
457 } | |
458 | |
459 // Also includes verify_card | |
460 bool CardTableExtension::addr_is_marked_precise(void *addr) { | |
461 jbyte* p = byte_for(addr); | |
462 jbyte val = *p; | |
463 | |
464 if (card_is_newgen(val)) | |
465 return true; | |
466 | |
467 if (card_is_verify(val)) | |
468 return true; | |
469 | |
470 if (card_is_clean(val)) | |
471 return false; | |
472 | |
473 if (card_is_dirty(val)) | |
474 return false; | |
475 | |
476 assert(false, "Found unhandled card mark type"); | |
477 | |
478 return false; | |
479 } | |
480 | |
481 // Assumes that only the base or the end changes. This allows indentification | |
482 // of the region that is being resized. The | |
483 // CardTableModRefBS::resize_covered_region() is used for the normal case | |
484 // where the covered regions are growing or shrinking at the high end. | |
485 // The method resize_covered_region_by_end() is analogous to | |
486 // CardTableModRefBS::resize_covered_region() but | |
487 // for regions that grow or shrink at the low end. | |
488 void CardTableExtension::resize_covered_region(MemRegion new_region) { | |
489 | |
490 for (int i = 0; i < _cur_covered_regions; i++) { | |
491 if (_covered[i].start() == new_region.start()) { | |
492 // Found a covered region with the same start as the | |
493 // new region. The region is growing or shrinking | |
494 // from the start of the region. | |
495 resize_covered_region_by_start(new_region); | |
496 return; | |
497 } | |
498 if (_covered[i].start() > new_region.start()) { | |
499 break; | |
500 } | |
501 } | |
502 | |
503 int changed_region = -1; | |
504 for (int j = 0; j < _cur_covered_regions; j++) { | |
505 if (_covered[j].end() == new_region.end()) { | |
506 changed_region = j; | |
507 // This is a case where the covered region is growing or shrinking | |
508 // at the start of the region. | |
509 assert(changed_region != -1, "Don't expect to add a covered region"); | |
510 assert(_covered[changed_region].byte_size() != new_region.byte_size(), | |
511 "The sizes should be different here"); | |
512 resize_covered_region_by_end(changed_region, new_region); | |
513 return; | |
514 } | |
515 } | |
516 // This should only be a new covered region (where no existing | |
517 // covered region matches at the start or the end). | |
518 assert(_cur_covered_regions < _max_covered_regions, | |
519 "An existing region should have been found"); | |
520 resize_covered_region_by_start(new_region); | |
521 } | |
522 | |
523 void CardTableExtension::resize_covered_region_by_start(MemRegion new_region) { | |
524 CardTableModRefBS::resize_covered_region(new_region); | |
525 debug_only(verify_guard();) | |
526 } | |
527 | |
528 void CardTableExtension::resize_covered_region_by_end(int changed_region, | |
529 MemRegion new_region) { | |
530 assert(SafepointSynchronize::is_at_safepoint(), | |
531 "Only expect an expansion at the low end at a GC"); | |
532 debug_only(verify_guard();) | |
533 #ifdef ASSERT | |
534 for (int k = 0; k < _cur_covered_regions; k++) { | |
535 if (_covered[k].end() == new_region.end()) { | |
536 assert(changed_region == k, "Changed region is incorrect"); | |
537 break; | |
538 } | |
539 } | |
540 #endif | |
541 | |
542 // Commit new or uncommit old pages, if necessary. | |
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543 if (resize_commit_uncommit(changed_region, new_region)) { |
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544 // Set the new start of the committed region |
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545 resize_update_committed_table(changed_region, new_region); |
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546 } |
0 | 547 |
548 // Update card table entries | |
549 resize_update_card_table_entries(changed_region, new_region); | |
550 | |
551 // Update the covered region | |
552 resize_update_covered_table(changed_region, new_region); | |
553 | |
554 if (TraceCardTableModRefBS) { | |
555 int ind = changed_region; | |
556 gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: "); | |
557 gclog_or_tty->print_cr(" " | |
558 " _covered[%d].start(): " INTPTR_FORMAT | |
559 " _covered[%d].last(): " INTPTR_FORMAT, | |
560 ind, _covered[ind].start(), | |
561 ind, _covered[ind].last()); | |
562 gclog_or_tty->print_cr(" " | |
563 " _committed[%d].start(): " INTPTR_FORMAT | |
564 " _committed[%d].last(): " INTPTR_FORMAT, | |
565 ind, _committed[ind].start(), | |
566 ind, _committed[ind].last()); | |
567 gclog_or_tty->print_cr(" " | |
568 " byte_for(start): " INTPTR_FORMAT | |
569 " byte_for(last): " INTPTR_FORMAT, | |
570 byte_for(_covered[ind].start()), | |
571 byte_for(_covered[ind].last())); | |
572 gclog_or_tty->print_cr(" " | |
573 " addr_for(start): " INTPTR_FORMAT | |
574 " addr_for(last): " INTPTR_FORMAT, | |
575 addr_for((jbyte*) _committed[ind].start()), | |
576 addr_for((jbyte*) _committed[ind].last())); | |
577 } | |
578 debug_only(verify_guard();) | |
579 } | |
580 | |
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581 bool CardTableExtension::resize_commit_uncommit(int changed_region, |
0 | 582 MemRegion new_region) { |
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583 bool result = false; |
0 | 584 // Commit new or uncommit old pages, if necessary. |
585 MemRegion cur_committed = _committed[changed_region]; | |
586 assert(_covered[changed_region].end() == new_region.end(), | |
587 "The ends of the regions are expected to match"); | |
588 // Extend the start of this _committed region to | |
589 // to cover the start of any previous _committed region. | |
590 // This forms overlapping regions, but never interior regions. | |
591 HeapWord* min_prev_start = lowest_prev_committed_start(changed_region); | |
592 if (min_prev_start < cur_committed.start()) { | |
593 // Only really need to set start of "cur_committed" to | |
594 // the new start (min_prev_start) but assertion checking code | |
595 // below use cur_committed.end() so make it correct. | |
596 MemRegion new_committed = | |
597 MemRegion(min_prev_start, cur_committed.end()); | |
598 cur_committed = new_committed; | |
599 } | |
600 #ifdef ASSERT | |
601 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
602 assert(cur_committed.start() == | |
603 (HeapWord*) align_size_up((uintptr_t) cur_committed.start(), | |
604 os::vm_page_size()), | |
605 "Starts should have proper alignment"); | |
606 #endif | |
607 | |
608 jbyte* new_start = byte_for(new_region.start()); | |
609 // Round down because this is for the start address | |
610 HeapWord* new_start_aligned = | |
611 (HeapWord*)align_size_down((uintptr_t)new_start, os::vm_page_size()); | |
612 // The guard page is always committed and should not be committed over. | |
613 // This method is used in cases where the generation is growing toward | |
614 // lower addresses but the guard region is still at the end of the | |
615 // card table. That still makes sense when looking for writes | |
616 // off the end of the card table. | |
617 if (new_start_aligned < cur_committed.start()) { | |
618 // Expand the committed region | |
619 // | |
620 // Case A | |
621 // |+ guard +| | |
622 // |+ cur committed +++++++++| | |
623 // |+ new committed +++++++++++++++++| | |
624 // | |
625 // Case B | |
626 // |+ guard +| | |
627 // |+ cur committed +| | |
628 // |+ new committed +++++++| | |
629 // | |
630 // These are not expected because the calculation of the | |
631 // cur committed region and the new committed region | |
632 // share the same end for the covered region. | |
633 // Case C | |
634 // |+ guard +| | |
635 // |+ cur committed +| | |
636 // |+ new committed +++++++++++++++++| | |
637 // Case D | |
638 // |+ guard +| | |
639 // |+ cur committed +++++++++++| | |
640 // |+ new committed +++++++| | |
641 | |
642 HeapWord* new_end_for_commit = | |
643 MIN2(cur_committed.end(), _guard_region.start()); | |
263
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644 if(new_start_aligned < new_end_for_commit) { |
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645 MemRegion new_committed = |
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646 MemRegion(new_start_aligned, new_end_for_commit); |
0 | 647 if (!os::commit_memory((char*)new_committed.start(), |
648 new_committed.byte_size())) { | |
649 vm_exit_out_of_memory(new_committed.byte_size(), | |
650 "card table expansion"); | |
651 } | |
652 } | |
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653 result = true; |
0 | 654 } else if (new_start_aligned > cur_committed.start()) { |
655 // Shrink the committed region | |
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656 #if 0 // uncommitting space is currently unsafe because of the interactions |
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657 // of growing and shrinking regions. One region A can uncommit space |
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658 // that it owns but which is being used by another region B (maybe). |
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659 // Region B has not committed the space because it was already |
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660 // committed by region A. |
0 | 661 MemRegion uncommit_region = committed_unique_to_self(changed_region, |
662 MemRegion(cur_committed.start(), new_start_aligned)); | |
663 if (!uncommit_region.is_empty()) { | |
664 if (!os::uncommit_memory((char*)uncommit_region.start(), | |
665 uncommit_region.byte_size())) { | |
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666 // If the uncommit fails, ignore it. Let the |
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667 // committed table resizing go even though the committed |
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668 // table will over state the committed space. |
0 | 669 } |
670 } | |
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671 #else |
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672 assert(!result, "Should be false with current workaround"); |
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673 #endif |
0 | 674 } |
675 assert(_committed[changed_region].end() == cur_committed.end(), | |
676 "end should not change"); | |
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677 return result; |
0 | 678 } |
679 | |
680 void CardTableExtension::resize_update_committed_table(int changed_region, | |
681 MemRegion new_region) { | |
682 | |
683 jbyte* new_start = byte_for(new_region.start()); | |
684 // Set the new start of the committed region | |
685 HeapWord* new_start_aligned = | |
686 (HeapWord*)align_size_down((uintptr_t)new_start, | |
687 os::vm_page_size()); | |
688 MemRegion new_committed = MemRegion(new_start_aligned, | |
689 _committed[changed_region].end()); | |
690 _committed[changed_region] = new_committed; | |
691 _committed[changed_region].set_start(new_start_aligned); | |
692 } | |
693 | |
694 void CardTableExtension::resize_update_card_table_entries(int changed_region, | |
695 MemRegion new_region) { | |
696 debug_only(verify_guard();) | |
697 MemRegion original_covered = _covered[changed_region]; | |
698 // Initialize the card entries. Only consider the | |
699 // region covered by the card table (_whole_heap) | |
700 jbyte* entry; | |
701 if (new_region.start() < _whole_heap.start()) { | |
702 entry = byte_for(_whole_heap.start()); | |
703 } else { | |
704 entry = byte_for(new_region.start()); | |
705 } | |
706 jbyte* end = byte_for(original_covered.start()); | |
707 // If _whole_heap starts at the original covered regions start, | |
708 // this loop will not execute. | |
709 while (entry < end) { *entry++ = clean_card; } | |
710 } | |
711 | |
712 void CardTableExtension::resize_update_covered_table(int changed_region, | |
713 MemRegion new_region) { | |
714 // Update the covered region | |
715 _covered[changed_region].set_start(new_region.start()); | |
716 _covered[changed_region].set_word_size(new_region.word_size()); | |
717 | |
718 // reorder regions. There should only be at most 1 out | |
719 // of order. | |
720 for (int i = _cur_covered_regions-1 ; i > 0; i--) { | |
721 if (_covered[i].start() < _covered[i-1].start()) { | |
722 MemRegion covered_mr = _covered[i-1]; | |
723 _covered[i-1] = _covered[i]; | |
724 _covered[i] = covered_mr; | |
725 MemRegion committed_mr = _committed[i-1]; | |
726 _committed[i-1] = _committed[i]; | |
727 _committed[i] = committed_mr; | |
728 break; | |
729 } | |
730 } | |
731 #ifdef ASSERT | |
732 for (int m = 0; m < _cur_covered_regions-1; m++) { | |
733 assert(_covered[m].start() <= _covered[m+1].start(), | |
734 "Covered regions out of order"); | |
735 assert(_committed[m].start() <= _committed[m+1].start(), | |
736 "Committed regions out of order"); | |
737 } | |
738 #endif | |
739 } | |
740 | |
741 // Returns the start of any committed region that is lower than | |
742 // the target committed region (index ind) and that intersects the | |
743 // target region. If none, return start of target region. | |
744 // | |
745 // ------------- | |
746 // | | | |
747 // ------------- | |
748 // ------------ | |
749 // | target | | |
750 // ------------ | |
751 // ------------- | |
752 // | | | |
753 // ------------- | |
754 // ^ returns this | |
755 // | |
756 // ------------- | |
757 // | | | |
758 // ------------- | |
759 // ------------ | |
760 // | target | | |
761 // ------------ | |
762 // ------------- | |
763 // | | | |
764 // ------------- | |
765 // ^ returns this | |
766 | |
767 HeapWord* CardTableExtension::lowest_prev_committed_start(int ind) const { | |
768 assert(_cur_covered_regions >= 0, "Expecting at least on region"); | |
769 HeapWord* min_start = _committed[ind].start(); | |
770 for (int j = 0; j < ind; j++) { | |
771 HeapWord* this_start = _committed[j].start(); | |
772 if ((this_start < min_start) && | |
773 !(_committed[j].intersection(_committed[ind])).is_empty()) { | |
774 min_start = this_start; | |
775 } | |
776 } | |
777 return min_start; | |
778 } |