1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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13 * accompanied this code).
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_INLINE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_INLINE_HPP
27
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30
31 // Utility routine to set an exclusive range of cards on the given
32 // card liveness bitmap
33 inline void ConcurrentMark::set_card_bitmap_range(BitMap* card_bm,
34 BitMap::idx_t start_idx,
35 BitMap::idx_t end_idx,
36 bool is_par) {
37
38 // Set the exclusive bit range [start_idx, end_idx).
39 assert((end_idx - start_idx) > 0, "at least one card");
40 assert(end_idx <= card_bm->size(), "sanity");
41
42 // Silently clip the end index
43 end_idx = MIN2(end_idx, card_bm->size());
44
45 // For small ranges use a simple loop; otherwise use set_range or
46 // use par_at_put_range (if parallel). The range is made up of the
47 // cards that are spanned by an object/mem region so 8 cards will
48 // allow up to object sizes up to 4K to be handled using the loop.
49 if ((end_idx - start_idx) <= 8) {
50 for (BitMap::idx_t i = start_idx; i < end_idx; i += 1) {
51 if (is_par) {
52 card_bm->par_set_bit(i);
53 } else {
54 card_bm->set_bit(i);
55 }
56 }
57 } else {
58 // Note BitMap::par_at_put_range() and BitMap::set_range() are exclusive.
59 if (is_par) {
60 card_bm->par_at_put_range(start_idx, end_idx, true);
61 } else {
62 card_bm->set_range(start_idx, end_idx);
63 }
64 }
65 }
66
67 // Returns the index in the liveness accounting card bitmap
68 // for the given address
69 inline BitMap::idx_t ConcurrentMark::card_bitmap_index_for(HeapWord* addr) {
70 // Below, the term "card num" means the result of shifting an address
71 // by the card shift -- address 0 corresponds to card number 0. One
72 // must subtract the card num of the bottom of the heap to obtain a
73 // card table index.
74 intptr_t card_num = intptr_t(uintptr_t(addr) >> CardTableModRefBS::card_shift);
75 return card_num - heap_bottom_card_num();
76 }
77
78 // Counts the given memory region in the given task/worker
79 // counting data structures.
80 inline void ConcurrentMark::count_region(MemRegion mr, HeapRegion* hr,
81 size_t* marked_bytes_array,
82 BitMap* task_card_bm) {
83 G1CollectedHeap* g1h = _g1h;
84 CardTableModRefBS* ct_bs = g1h->g1_barrier_set();
85
86 HeapWord* start = mr.start();
87 HeapWord* end = mr.end();
88 size_t region_size_bytes = mr.byte_size();
89 uint index = hr->hrm_index();
90
91 assert(!hr->is_continues_humongous(), "should not be HC region");
92 assert(hr == g1h->heap_region_containing(start), "sanity");
93 assert(hr == g1h->heap_region_containing(mr.last()), "sanity");
94 assert(marked_bytes_array != NULL, "pre-condition");
95 assert(task_card_bm != NULL, "pre-condition");
96
97 // Add to the task local marked bytes for this region.
98 marked_bytes_array[index] += region_size_bytes;
99
100 BitMap::idx_t start_idx = card_bitmap_index_for(start);
101 BitMap::idx_t end_idx = card_bitmap_index_for(end);
102
103 // Note: if we're looking at the last region in heap - end
104 // could be actually just beyond the end of the heap; end_idx
105 // will then correspond to a (non-existent) card that is also
106 // just beyond the heap.
107 if (g1h->is_in_g1_reserved(end) && !ct_bs->is_card_aligned(end)) {
108 // end of region is not card aligned - increment to cover
109 // all the cards spanned by the region.
110 end_idx += 1;
111 }
112 // The card bitmap is task/worker specific => no need to use
113 // the 'par' BitMap routines.
114 // Set bits in the exclusive bit range [start_idx, end_idx).
115 set_card_bitmap_range(task_card_bm, start_idx, end_idx, false /* is_par */);
116 }
117
118 // Counts the given memory region in the task/worker counting
119 // data structures for the given worker id.
120 inline void ConcurrentMark::count_region(MemRegion mr,
121 HeapRegion* hr,
122 uint worker_id) {
123 size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);
124 BitMap* task_card_bm = count_card_bitmap_for(worker_id);
125 count_region(mr, hr, marked_bytes_array, task_card_bm);
126 }
127
128 // Counts the given object in the given task/worker counting data structures.
129 inline void ConcurrentMark::count_object(oop obj,
130 HeapRegion* hr,
131 size_t* marked_bytes_array,
132 BitMap* task_card_bm) {
133 MemRegion mr((HeapWord*)obj, obj->size());
134 count_region(mr, hr, marked_bytes_array, task_card_bm);
135 }
136
137 // Attempts to mark the given object and, if successful, counts
138 // the object in the given task/worker counting structures.
139 inline bool ConcurrentMark::par_mark_and_count(oop obj,
140 HeapRegion* hr,
141 size_t* marked_bytes_array,
142 BitMap* task_card_bm) {
143 HeapWord* addr = (HeapWord*)obj;
144 if (_nextMarkBitMap->parMark(addr)) {
145 // Update the task specific count data for the object.
146 count_object(obj, hr, marked_bytes_array, task_card_bm);
147 return true;
148 }
149 return false;
150 }
151
152 // Attempts to mark the given object and, if successful, counts
153 // the object in the task/worker counting structures for the
154 // given worker id.
155 inline bool ConcurrentMark::par_mark_and_count(oop obj,
156 size_t word_size,
157 HeapRegion* hr,
158 uint worker_id) {
159 HeapWord* addr = (HeapWord*)obj;
160 if (_nextMarkBitMap->parMark(addr)) {
161 MemRegion mr(addr, word_size);
162 count_region(mr, hr, worker_id);
163 return true;
164 }
165 return false;
166 }
167
168 inline bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
169 HeapWord* start_addr = MAX2(startWord(), mr.start());
170 HeapWord* end_addr = MIN2(endWord(), mr.end());
171
172 if (end_addr > start_addr) {
173 // Right-open interval [start-offset, end-offset).
174 BitMap::idx_t start_offset = heapWordToOffset(start_addr);
175 BitMap::idx_t end_offset = heapWordToOffset(end_addr);
176
177 start_offset = _bm.get_next_one_offset(start_offset, end_offset);
178 while (start_offset < end_offset) {
179 if (!cl->do_bit(start_offset)) {
180 return false;
181 }
182 HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr);
183 BitMap::idx_t next_offset = heapWordToOffset(next_addr);
184 start_offset = _bm.get_next_one_offset(next_offset, end_offset);
185 }
186 }
187 return true;
188 }
189
190 inline bool CMBitMapRO::iterate(BitMapClosure* cl) {
191 MemRegion mr(startWord(), sizeInWords());
192 return iterate(cl, mr);
193 }
194
195 #define check_mark(addr) \
196 assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize), \
197 "outside underlying space?"); \
198 assert(G1CollectedHeap::heap()->is_in_exact(addr), \
199 err_msg("Trying to access not available bitmap "PTR_FORMAT \
200 " corresponding to "PTR_FORMAT" (%u)", \
201 p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr)));
202
203 inline void CMBitMap::mark(HeapWord* addr) {
204 check_mark(addr);
205 _bm.set_bit(heapWordToOffset(addr));
206 }
207
208 inline void CMBitMap::clear(HeapWord* addr) {
209 check_mark(addr);
210 _bm.clear_bit(heapWordToOffset(addr));
211 }
212
213 inline bool CMBitMap::parMark(HeapWord* addr) {
214 check_mark(addr);
215 return _bm.par_set_bit(heapWordToOffset(addr));
216 }
217
218 inline bool CMBitMap::parClear(HeapWord* addr) {
219 check_mark(addr);
220 return _bm.par_clear_bit(heapWordToOffset(addr));
221 }
222
223 #undef check_mark
224
225 inline bool CMTask::is_stale_humongous_queue_entry(oop obj) const {
226 // When a humongous object is eagerly reclaimed, we don't remove
227 // entries for it from queues. Instead, we filter out such entries
228 // on the processing side.
229 //
230 // Recently allocated objects are filtered out when queuing, to
231 // minimize queue size and processing time. Therefore, if we find
232 // what appears to be a recently allocated object in the queue, it
233 // must be for a reclaimed humongous object.
234 HeapRegion* hr = _g1h->heap_region_containing_raw(obj);
235 bool result = hr->obj_allocated_since_next_marking(obj);
236 #ifdef ASSERT
237 if (result) {
238 HeapWord* hp = (HeapWord*)obj;
239 assert(hp == hr->bottom(), "stale humongous should be at region bottom");
240 assert(!_nextMarkBitMap->isMarked(hp), "stale humongous should not be marked");
241 }
242 #endif
243 return result;
244 }
245
246 inline void CMTask::push(oop obj) {
247 HeapWord* objAddr = (HeapWord*) obj;
248 assert(_g1h->is_in_g1_reserved(objAddr), "invariant");
249 assert(!_g1h->is_on_master_free_list(
250 _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant");
251 assert(!_g1h->is_obj_ill(obj), "invariant");
252 assert(_nextMarkBitMap->isMarked(objAddr), "invariant");
253
254 if (_cm->verbose_high()) {
255 gclog_or_tty->print_cr("[%u] pushing " PTR_FORMAT, _worker_id, p2i((void*) obj));
256 }
257
258 if (!_task_queue->push(obj)) {
259 // The local task queue looks full. We need to push some entries
260 // to the global stack.
261
262 if (_cm->verbose_medium()) {
263 gclog_or_tty->print_cr("[%u] task queue overflow, "
264 "moving entries to the global stack",
265 _worker_id);
266 }
267 move_entries_to_global_stack();
268
269 // this should succeed since, even if we overflow the global
270 // stack, we should have definitely removed some entries from the
271 // local queue. So, there must be space on it.
272 bool success = _task_queue->push(obj);
273 assert(success, "invariant");
274 }
275
276 statsOnly( size_t tmp_size = (size_t)_task_queue->size();
277 if (tmp_size > _local_max_size) {
278 _local_max_size = tmp_size;
279 }
280 ++_local_pushes );
281 }
282
283 // This determines whether the method below will check both the local
284 // and global fingers when determining whether to push on the stack a
285 // gray object (value 1) or whether it will only check the global one
286 // (value 0). The tradeoffs are that the former will be a bit more
287 // accurate and possibly push less on the stack, but it might also be
288 // a little bit slower.
289
290 #define _CHECK_BOTH_FINGERS_ 1
291
292 inline void CMTask::deal_with_reference(oop obj) {
293 if (_cm->verbose_high()) {
294 gclog_or_tty->print_cr("[%u] we're dealing with reference = "PTR_FORMAT,
295 _worker_id, p2i((void*) obj));
296 }
297
298 ++_refs_reached;
299
300 HeapWord* objAddr = (HeapWord*) obj;
301 assert(obj->is_oop_or_null(true /* ignore mark word */), err_msg("Expected an oop or NULL at " PTR_FORMAT, p2i(obj)));
302 if (_g1h->is_in_g1_reserved(objAddr)) {
303 assert(obj != NULL, "null check is implicit");
304 if (!_nextMarkBitMap->isMarked(objAddr)) {
305 // Only get the containing region if the object is not marked on the
306 // bitmap (otherwise, it's a waste of time since we won't do
307 // anything with it).
308 HeapRegion* hr = _g1h->heap_region_containing_raw(obj);
309 if (!hr->obj_allocated_since_next_marking(obj)) {
310 if (_cm->verbose_high()) {
311 gclog_or_tty->print_cr("[%u] "PTR_FORMAT" is not considered marked",
312 _worker_id, p2i((void*) obj));
313 }
314
315 // we need to mark it first
316 if (_cm->par_mark_and_count(obj, hr, _marked_bytes_array, _card_bm)) {
317 // No OrderAccess:store_load() is needed. It is implicit in the
318 // CAS done in CMBitMap::parMark() call in the routine above.
319 HeapWord* global_finger = _cm->finger();
320
321 #if _CHECK_BOTH_FINGERS_
322 // we will check both the local and global fingers
323
324 if (_finger != NULL && objAddr < _finger) {
325 if (_cm->verbose_high()) {
326 gclog_or_tty->print_cr("[%u] below the local finger ("PTR_FORMAT"), "
327 "pushing it", _worker_id, p2i(_finger));
328 }
329 push(obj);
330 } else if (_curr_region != NULL && objAddr < _region_limit) {
331 // do nothing
332 } else if (objAddr < global_finger) {
333 // Notice that the global finger might be moving forward
334 // concurrently. This is not a problem. In the worst case, we
335 // mark the object while it is above the global finger and, by
336 // the time we read the global finger, it has moved forward
337 // passed this object. In this case, the object will probably
338 // be visited when a task is scanning the region and will also
339 // be pushed on the stack. So, some duplicate work, but no
340 // correctness problems.
341
342 if (_cm->verbose_high()) {
343 gclog_or_tty->print_cr("[%u] below the global finger "
344 "("PTR_FORMAT"), pushing it",
345 _worker_id, p2i(global_finger));
346 }
347 push(obj);
348 } else {
349 // do nothing
350 }
351 #else // _CHECK_BOTH_FINGERS_
352 // we will only check the global finger
353
354 if (objAddr < global_finger) {
355 // see long comment above
356
357 if (_cm->verbose_high()) {
358 gclog_or_tty->print_cr("[%u] below the global finger "
359 "("PTR_FORMAT"), pushing it",
360 _worker_id, p2i(global_finger));
361 }
362 push(obj);
363 }
364 #endif // _CHECK_BOTH_FINGERS_
365 }
366 }
367 }
368 }
369 }
370
371 inline void ConcurrentMark::markPrev(oop p) {
372 assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity");
373 // Note we are overriding the read-only view of the prev map here, via
374 // the cast.
375 ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);
376 }
377
378 inline void ConcurrentMark::grayRoot(oop obj, size_t word_size,
379 uint worker_id, HeapRegion* hr) {
380 assert(obj != NULL, "pre-condition");
381 HeapWord* addr = (HeapWord*) obj;
382 if (hr == NULL) {
383 hr = _g1h->heap_region_containing_raw(addr);
384 } else {
385 assert(hr->is_in(addr), "pre-condition");
386 }
387 assert(hr != NULL, "sanity");
388 // Given that we're looking for a region that contains an object
389 // header it's impossible to get back a HC region.
390 assert(!hr->is_continues_humongous(), "sanity");
391
392 // We cannot assert that word_size == obj->size() given that obj
393 // might not be in a consistent state (another thread might be in
394 // the process of copying it). So the best thing we can do is to
395 // assert that word_size is under an upper bound which is its
396 // containing region's capacity.
397 assert(word_size * HeapWordSize <= hr->capacity(),
398 err_msg("size: "SIZE_FORMAT" capacity: "SIZE_FORMAT" "HR_FORMAT,
399 word_size * HeapWordSize, hr->capacity(),
400 HR_FORMAT_PARAMS(hr)));
401
402 if (addr < hr->next_top_at_mark_start()) {
403 if (!_nextMarkBitMap->isMarked(addr)) {
404 par_mark_and_count(obj, word_size, hr, worker_id);
405 }
406 }
407 }
408
409 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_INLINE_HPP