1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  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).
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  24 
  25 #ifndef SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP
  26 #define SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP
  27 
  28 #include "gc/g1/concurrentMark.hpp"
  29 #include "gc/g1/g1CollectedHeap.inline.hpp"
  30 #include "gc/shared/taskqueue.inline.hpp"
  31 
  32 // Utility routine to set an exclusive range of cards on the given
  33 // card liveness bitmap
  34 inline void ConcurrentMark::set_card_bitmap_range(BitMap* card_bm,
  35                                                   BitMap::idx_t start_idx,
  36                                                   BitMap::idx_t end_idx,
  37                                                   bool is_par) {
  38 
  39   // Set the exclusive bit range [start_idx, end_idx).
  40   assert((end_idx - start_idx) > 0, "at least one card");
  41   assert(end_idx <= card_bm->size(), "sanity");
  42 
  43   // Silently clip the end index
  44   end_idx = MIN2(end_idx, card_bm->size());
  45 
  46   // For small ranges use a simple loop; otherwise use set_range or
  47   // use par_at_put_range (if parallel). The range is made up of the
  48   // cards that are spanned by an object/mem region so 8 cards will
  49   // allow up to object sizes up to 4K to be handled using the loop.
  50   if ((end_idx - start_idx) <= 8) {
  51     for (BitMap::idx_t i = start_idx; i < end_idx; i += 1) {
  52       if (is_par) {
  53         card_bm->par_set_bit(i);
  54       } else {
  55         card_bm->set_bit(i);
  56       }
  57     }
  58   } else {
  59     // Note BitMap::par_at_put_range() and BitMap::set_range() are exclusive.
  60     if (is_par) {
  61       card_bm->par_at_put_range(start_idx, end_idx, true);
  62     } else {
  63       card_bm->set_range(start_idx, end_idx);
  64     }
  65   }
  66 }
  67 
  68 // Returns the index in the liveness accounting card bitmap
  69 // for the given address
  70 inline BitMap::idx_t ConcurrentMark::card_bitmap_index_for(HeapWord* addr) {
  71   // Below, the term "card num" means the result of shifting an address
  72   // by the card shift -- address 0 corresponds to card number 0.  One
  73   // must subtract the card num of the bottom of the heap to obtain a
  74   // card table index.
  75   intptr_t card_num = intptr_t(uintptr_t(addr) >> CardTableModRefBS::card_shift);
  76   return card_num - heap_bottom_card_num();
  77 }
  78 
  79 // Counts the given memory region in the given task/worker
  80 // counting data structures.
  81 inline void ConcurrentMark::count_region(MemRegion mr, HeapRegion* hr,
  82                                          size_t* marked_bytes_array,
  83                                          BitMap* task_card_bm) {
  84   G1CollectedHeap* g1h = _g1h;
  85   CardTableModRefBS* ct_bs = g1h->g1_barrier_set();
  86 
  87   HeapWord* start = mr.start();
  88   HeapWord* end = mr.end();
  89   size_t region_size_bytes = mr.byte_size();
  90   uint index = hr->hrm_index();
  91 
  92   assert(!hr->is_continues_humongous(), "should not be HC region");
  93   assert(hr == g1h->heap_region_containing(start), "sanity");
  94   assert(hr == g1h->heap_region_containing(mr.last()), "sanity");
  95   assert(marked_bytes_array != NULL, "pre-condition");
  96   assert(task_card_bm != NULL, "pre-condition");
  97 
  98   // Add to the task local marked bytes for this region.
  99   marked_bytes_array[index] += region_size_bytes;
 100 
 101   BitMap::idx_t start_idx = card_bitmap_index_for(start);
 102   BitMap::idx_t end_idx = card_bitmap_index_for(end);
 103 
 104   // Note: if we're looking at the last region in heap - end
 105   // could be actually just beyond the end of the heap; end_idx
 106   // will then correspond to a (non-existent) card that is also
 107   // just beyond the heap.
 108   if (g1h->is_in_g1_reserved(end) && !ct_bs->is_card_aligned(end)) {
 109     // end of region is not card aligned - increment to cover
 110     // all the cards spanned by the region.
 111     end_idx += 1;
 112   }
 113   // The card bitmap is task/worker specific => no need to use
 114   // the 'par' BitMap routines.
 115   // Set bits in the exclusive bit range [start_idx, end_idx).
 116   set_card_bitmap_range(task_card_bm, start_idx, end_idx, false /* is_par */);
 117 }
 118 
 119 // Counts the given memory region in the task/worker counting
 120 // data structures for the given worker id.
 121 inline void ConcurrentMark::count_region(MemRegion mr,
 122                                          HeapRegion* hr,
 123                                          uint worker_id) {
 124   size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);
 125   BitMap* task_card_bm = count_card_bitmap_for(worker_id);
 126   count_region(mr, hr, marked_bytes_array, task_card_bm);
 127 }
 128 
 129 // Counts the given object in the given task/worker counting data structures.
 130 inline void ConcurrentMark::count_object(oop obj,
 131                                          HeapRegion* hr,
 132                                          size_t* marked_bytes_array,
 133                                          BitMap* task_card_bm) {
 134   MemRegion mr((HeapWord*)obj, obj->size());
 135   count_region(mr, hr, marked_bytes_array, task_card_bm);
 136 }
 137 
 138 // Attempts to mark the given object and, if successful, counts
 139 // the object in the given task/worker counting structures.
 140 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 141                                                HeapRegion* hr,
 142                                                size_t* marked_bytes_array,
 143                                                BitMap* task_card_bm) {
 144   HeapWord* addr = (HeapWord*)obj;
 145   if (_nextMarkBitMap->parMark(addr)) {
 146     // Update the task specific count data for the object.
 147     count_object(obj, hr, marked_bytes_array, task_card_bm);
 148     return true;
 149   }
 150   return false;
 151 }
 152 
 153 // Attempts to mark the given object and, if successful, counts
 154 // the object in the task/worker counting structures for the
 155 // given worker id.
 156 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 157                                                size_t word_size,
 158                                                HeapRegion* hr,
 159                                                uint worker_id) {
 160   HeapWord* addr = (HeapWord*)obj;
 161   if (_nextMarkBitMap->parMark(addr)) {
 162     MemRegion mr(addr, word_size);
 163     count_region(mr, hr, worker_id);
 164     return true;
 165   }
 166   return false;
 167 }
 168 
 169 inline bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
 170   HeapWord* start_addr = MAX2(startWord(), mr.start());
 171   HeapWord* end_addr = MIN2(endWord(), mr.end());
 172 
 173   if (end_addr > start_addr) {
 174     // Right-open interval [start-offset, end-offset).
 175     BitMap::idx_t start_offset = heapWordToOffset(start_addr);
 176     BitMap::idx_t end_offset = heapWordToOffset(end_addr);
 177 
 178     start_offset = _bm.get_next_one_offset(start_offset, end_offset);
 179     while (start_offset < end_offset) {
 180       if (!cl->do_bit(start_offset)) {
 181         return false;
 182       }
 183       HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr);
 184       BitMap::idx_t next_offset = heapWordToOffset(next_addr);
 185       start_offset = _bm.get_next_one_offset(next_offset, end_offset);
 186     }
 187   }
 188   return true;
 189 }
 190 
 191 inline bool CMBitMapRO::iterate(BitMapClosure* cl) {
 192   MemRegion mr(startWord(), sizeInWords());
 193   return iterate(cl, mr);
 194 }
 195 
 196 #define check_mark(addr)                                                       \
 197   assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize),      \
 198          "outside underlying space?");                                         \
 199   assert(G1CollectedHeap::heap()->is_in_exact(addr),                           \
 200          "Trying to access not available bitmap " PTR_FORMAT                   \
 201          " corresponding to " PTR_FORMAT " (%u)",                              \
 202          p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr));
 203 
 204 inline void CMBitMap::mark(HeapWord* addr) {
 205   check_mark(addr);
 206   _bm.set_bit(heapWordToOffset(addr));
 207 }
 208 
 209 inline void CMBitMap::clear(HeapWord* addr) {
 210   check_mark(addr);
 211   _bm.clear_bit(heapWordToOffset(addr));
 212 }
 213 
 214 inline bool CMBitMap::parMark(HeapWord* addr) {
 215   check_mark(addr);
 216   return _bm.par_set_bit(heapWordToOffset(addr));
 217 }
 218 
 219 inline bool CMBitMap::parClear(HeapWord* addr) {
 220   check_mark(addr);
 221   return _bm.par_clear_bit(heapWordToOffset(addr));
 222 }
 223 
 224 #undef check_mark
 225 
 226 template<typename Fn>
 227 inline void CMMarkStack::iterate(Fn fn) {
 228   assert(_saved_index == _index, "saved index: %d index: %d", _saved_index, _index);

 229   for (int i = 0; i < _index; ++i) {
 230     fn(_base[i]);
 231   }
 232 }
 233 
 234 // It scans an object and visits its children.
 235 inline void CMTask::scan_object(oop obj) { process_grey_object<true>(obj); }
 236 
 237 inline void CMTask::push(oop obj) {
 238   HeapWord* objAddr = (HeapWord*) obj;
 239   assert(_g1h->is_in_g1_reserved(objAddr), "invariant");
 240   assert(!_g1h->is_on_master_free_list(
 241               _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant");
 242   assert(!_g1h->is_obj_ill(obj), "invariant");
 243   assert(_nextMarkBitMap->isMarked(objAddr), "invariant");
 244 
 245   if (_cm->verbose_high()) {
 246     gclog_or_tty->print_cr("[%u] pushing " PTR_FORMAT, _worker_id, p2i((void*) obj));
 247   }
 248 
 249   if (!_task_queue->push(obj)) {
 250     // The local task queue looks full. We need to push some entries
 251     // to the global stack.
 252 
 253     if (_cm->verbose_medium()) {
 254       gclog_or_tty->print_cr("[%u] task queue overflow, "
 255                              "moving entries to the global stack",
 256                              _worker_id);
 257     }
 258     move_entries_to_global_stack();
 259 
 260     // this should succeed since, even if we overflow the global
 261     // stack, we should have definitely removed some entries from the
 262     // local queue. So, there must be space on it.
 263     bool success = _task_queue->push(obj);
 264     assert(success, "invariant");
 265   }
 266 
 267   statsOnly( size_t tmp_size = (size_t)_task_queue->size();
 268              if (tmp_size > _local_max_size) {
 269                _local_max_size = tmp_size;
 270              }
 271              ++_local_pushes );
 272 }
 273 
 274 inline bool CMTask::is_below_finger(oop obj, HeapWord* global_finger) const {
 275   // If obj is above the global finger, then the mark bitmap scan
 276   // will find it later, and no push is needed.  Similarly, if we have
 277   // a current region and obj is between the local finger and the
 278   // end of the current region, then no push is needed.  The tradeoff
 279   // of checking both vs only checking the global finger is that the
 280   // local check will be more accurate and so result in fewer pushes,
 281   // but may also be a little slower.
 282   HeapWord* objAddr = (HeapWord*)obj;
 283   if (_finger != NULL) {
 284     // We have a current region.
 285 
 286     // Finger and region values are all NULL or all non-NULL.  We
 287     // use _finger to check since we immediately use its value.
 288     assert(_curr_region != NULL, "invariant");
 289     assert(_region_limit != NULL, "invariant");
 290     assert(_region_limit <= global_finger, "invariant");
 291 
 292     // True if obj is less than the local finger, or is between
 293     // the region limit and the global finger.
 294     if (objAddr < _finger) {
 295       return true;
 296     } else if (objAddr < _region_limit) {
 297       return false;
 298     } // Else check global finger.
 299   }
 300   // Check global finger.
 301   return objAddr < global_finger;
 302 }
 303 
 304 template<bool scan>
 305 inline void CMTask::process_grey_object(oop obj) {
 306   assert(scan || obj->is_typeArray(), "Skipping scan of grey non-typeArray");
 307   assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");
 308 
 309   if (_cm->verbose_high()) {
 310     gclog_or_tty->print_cr("[%u] processing grey object " PTR_FORMAT,
 311                            _worker_id, p2i((void*) obj));
 312   }
 313 
 314   size_t obj_size = obj->size();
 315   _words_scanned += obj_size;
 316 
 317   if (scan) {
 318     obj->oop_iterate(_cm_oop_closure);
 319   }
 320   statsOnly( ++_objs_scanned );
 321   check_limits();
 322 }
 323 
 324 
 325 
 326 inline void CMTask::make_reference_grey(oop obj, HeapRegion* hr) {
 327   if (_cm->par_mark_and_count(obj, hr, _marked_bytes_array, _card_bm)) {
 328 
 329     if (_cm->verbose_high()) {
 330       gclog_or_tty->print_cr("[%u] marked object " PTR_FORMAT,
 331                              _worker_id, p2i(obj));
 332     }
 333 
 334     // No OrderAccess:store_load() is needed. It is implicit in the
 335     // CAS done in CMBitMap::parMark() call in the routine above.
 336     HeapWord* global_finger = _cm->finger();
 337 
 338     // We only need to push a newly grey object on the mark
 339     // stack if it is in a section of memory the mark bitmap
 340     // scan has already examined.  Mark bitmap scanning
 341     // maintains progress "fingers" for determining that.
 342     //
 343     // Notice that the global finger might be moving forward
 344     // concurrently. This is not a problem. In the worst case, we
 345     // mark the object while it is above the global finger and, by
 346     // the time we read the global finger, it has moved forward
 347     // past this object. In this case, the object will probably
 348     // be visited when a task is scanning the region and will also
 349     // be pushed on the stack. So, some duplicate work, but no
 350     // correctness problems.
 351     if (is_below_finger(obj, global_finger)) {
 352       if (obj->is_typeArray()) {
 353         // Immediately process arrays of primitive types, rather
 354         // than pushing on the mark stack.  This keeps us from
 355         // adding humongous objects to the mark stack that might
 356         // be reclaimed before the entry is processed - see
 357         // selection of candidates for eager reclaim of humongous
 358         // objects.  The cost of the additional type test is
 359         // mitigated by avoiding a trip through the mark stack,
 360         // by only doing a bookkeeping update and avoiding the
 361         // actual scan of the object - a typeArray contains no
 362         // references, and the metadata is built-in.
 363         process_grey_object<false>(obj);
 364       } else {
 365         if (_cm->verbose_high()) {
 366           gclog_or_tty->print_cr("[%u] below a finger (local: " PTR_FORMAT
 367                                  ", global: " PTR_FORMAT ") pushing "
 368                                  PTR_FORMAT " on mark stack",
 369                                  _worker_id, p2i(_finger),
 370                                  p2i(global_finger), p2i(obj));
 371         }
 372         push(obj);
 373       }
 374     }
 375   }
 376 }
 377 
 378 inline void CMTask::deal_with_reference(oop obj) {
 379   if (_cm->verbose_high()) {
 380     gclog_or_tty->print_cr("[%u] we're dealing with reference = " PTR_FORMAT,
 381                            _worker_id, p2i((void*) obj));
 382   }
 383 
 384   increment_refs_reached();
 385 
 386   HeapWord* objAddr = (HeapWord*) obj;
 387   assert(obj->is_oop_or_null(true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(obj));
 388   if (_g1h->is_in_g1_reserved(objAddr)) {
 389     assert(obj != NULL, "null check is implicit");
 390     if (!_nextMarkBitMap->isMarked(objAddr)) {
 391       // Only get the containing region if the object is not marked on the
 392       // bitmap (otherwise, it's a waste of time since we won't do
 393       // anything with it).
 394       HeapRegion* hr = _g1h->heap_region_containing_raw(obj);
 395       if (!hr->obj_allocated_since_next_marking(obj)) {
 396         make_reference_grey(obj, hr);
 397       }
 398     }
 399   }
 400 }
 401 
 402 inline void ConcurrentMark::markPrev(oop p) {
 403   assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity");
 404   // Note we are overriding the read-only view of the prev map here, via
 405   // the cast.
 406   ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);
 407 }
 408 
 409 inline void ConcurrentMark::grayRoot(oop obj, size_t word_size,
 410                                      uint worker_id, HeapRegion* hr) {
 411   assert(obj != NULL, "pre-condition");
 412   HeapWord* addr = (HeapWord*) obj;
 413   if (hr == NULL) {
 414     hr = _g1h->heap_region_containing_raw(addr);
 415   } else {
 416     assert(hr->is_in(addr), "pre-condition");
 417   }
 418   assert(hr != NULL, "sanity");
 419   // Given that we're looking for a region that contains an object
 420   // header it's impossible to get back a HC region.
 421   assert(!hr->is_continues_humongous(), "sanity");
 422 
 423   // We cannot assert that word_size == obj->size() given that obj
 424   // might not be in a consistent state (another thread might be in
 425   // the process of copying it). So the best thing we can do is to
 426   // assert that word_size is under an upper bound which is its
 427   // containing region's capacity.
 428   assert(word_size * HeapWordSize <= hr->capacity(),
 429          "size: " SIZE_FORMAT " capacity: " SIZE_FORMAT " " HR_FORMAT,
 430          word_size * HeapWordSize, hr->capacity(),
 431          HR_FORMAT_PARAMS(hr));
 432 
 433   if (addr < hr->next_top_at_mark_start()) {
 434     if (!_nextMarkBitMap->isMarked(addr)) {
 435       par_mark_and_count(obj, word_size, hr, worker_id);
 436     }
 437   }
 438 }
 439 
 440 #endif // SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP
--- EOF ---