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
   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
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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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 = (CardTableModRefBS*) (g1h->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->hrs_index();
  90 
  91   assert(!hr->continuesHumongous(), "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 a region that coincides with the end
 104   // of the heap - end could actually be outside the heap and end_idx
 105   // correspond to a card that is also outside the heap.
 106   if (g1h->is_in_g1_reserved(end) && !ct_bs->is_card_aligned(end)) {
 107     // end of region is not card aligned - incremement to cover
 108     // all the cards spanned by the region.
 109     end_idx += 1;
 110   }
 111   // The card bitmap is task/worker specific => no need to use
 112   // the 'par' BitMap routines.
 113   // Set bits in the exclusive bit range [start_idx, end_idx).
 114   set_card_bitmap_range(task_card_bm, start_idx, end_idx, false /* is_par */);
 115 }
 116 
 117 // Counts the given memory region in the task/worker counting
 118 // data structures for the given worker id.
 119 inline void ConcurrentMark::count_region(MemRegion mr,
 120                                          HeapRegion* hr,
 121                                          uint worker_id) {
 122   size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);
 123   BitMap* task_card_bm = count_card_bitmap_for(worker_id);
 124   count_region(mr, hr, marked_bytes_array, task_card_bm);
 125 }
 126 
 127 // Counts the given memory region, which may be a single object, in the
 128 // task/worker counting data structures for the given worker id.
 129 inline void ConcurrentMark::count_region(MemRegion mr, uint worker_id) {
 130   HeapWord* addr = mr.start();
 131   HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
 132   count_region(mr, hr, worker_id);
 133 }
 134 
 135 // Counts the given object in the given task/worker counting data structures.
 136 inline void ConcurrentMark::count_object(oop obj,
 137                                          HeapRegion* hr,
 138                                          size_t* marked_bytes_array,
 139                                          BitMap* task_card_bm) {
 140   MemRegion mr((HeapWord*)obj, obj->size());
 141   count_region(mr, hr, marked_bytes_array, task_card_bm);
 142 }
 143 
 144 // Counts the given object in the task/worker counting data
 145 // structures for the given worker id.
 146 inline void ConcurrentMark::count_object(oop obj,
 147                                          HeapRegion* hr,
 148                                          uint worker_id) {
 149   size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);
 150   BitMap* task_card_bm = count_card_bitmap_for(worker_id);
 151   HeapWord* addr = (HeapWord*) obj;
 152   count_object(obj, hr, marked_bytes_array, task_card_bm);
 153 }
 154 
 155 // Attempts to mark the given object and, if successful, counts
 156 // the object in the given task/worker counting structures.
 157 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 158                                                HeapRegion* hr,
 159                                                size_t* marked_bytes_array,
 160                                                BitMap* task_card_bm) {
 161   HeapWord* addr = (HeapWord*)obj;
 162   if (_nextMarkBitMap->parMark(addr)) {
 163     // Update the task specific count data for the object.
 164     count_object(obj, hr, marked_bytes_array, task_card_bm);
 165     return true;
 166   }
 167   return false;
 168 }
 169 
 170 // Attempts to mark the given object and, if successful, counts
 171 // the object in the task/worker counting structures for the
 172 // given worker id.
 173 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 174                                                size_t word_size,
 175                                                HeapRegion* hr,
 176                                                uint worker_id) {
 177   HeapWord* addr = (HeapWord*)obj;
 178   if (_nextMarkBitMap->parMark(addr)) {
 179     MemRegion mr(addr, word_size);
 180     count_region(mr, hr, worker_id);
 181     return true;
 182   }
 183   return false;
 184 }
 185 
 186 // Attempts to mark the given object and, if successful, counts
 187 // the object in the task/worker counting structures for the
 188 // given worker id.
 189 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 190                                                HeapRegion* hr,
 191                                                uint worker_id) {
 192   HeapWord* addr = (HeapWord*)obj;
 193   if (_nextMarkBitMap->parMark(addr)) {
 194     // Update the task specific count data for the object.
 195     count_object(obj, hr, worker_id);
 196     return true;
 197   }
 198   return false;
 199 }
 200 
 201 // As above - but we don't know the heap region containing the
 202 // object and so have to supply it.
 203 inline bool ConcurrentMark::par_mark_and_count(oop obj, uint worker_id) {
 204   HeapWord* addr = (HeapWord*)obj;
 205   HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
 206   return par_mark_and_count(obj, hr, worker_id);
 207 }
 208 
 209 // Similar to the above routine but we already know the size, in words, of
 210 // the object that we wish to mark/count
 211 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 212                                                size_t word_size,
 213                                                uint worker_id) {
 214   HeapWord* addr = (HeapWord*)obj;
 215   if (_nextMarkBitMap->parMark(addr)) {
 216     // Update the task specific count data for the object.
 217     MemRegion mr(addr, word_size);
 218     count_region(mr, worker_id);
 219     return true;
 220   }
 221   return false;
 222 }
 223 
 224 // Unconditionally mark the given object, and unconditinally count
 225 // the object in the counting structures for worker id 0.
 226 // Should *not* be called from parallel code.
 227 inline bool ConcurrentMark::mark_and_count(oop obj, HeapRegion* hr) {
 228   HeapWord* addr = (HeapWord*)obj;
 229   _nextMarkBitMap->mark(addr);
 230   // Update the task specific count data for the object.
 231   count_object(obj, hr, 0 /* worker_id */);
 232   return true;
 233 }
 234 
 235 // As above - but we don't have the heap region containing the
 236 // object, so we have to supply it.
 237 inline bool ConcurrentMark::mark_and_count(oop obj) {
 238   HeapWord* addr = (HeapWord*)obj;
 239   HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
 240   return mark_and_count(obj, hr);
 241 }
 242 
 243 inline bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
 244   HeapWord* start_addr = MAX2(startWord(), mr.start());
 245   HeapWord* end_addr = MIN2(endWord(), mr.end());
 246 
 247   if (end_addr > start_addr) {
 248     // Right-open interval [start-offset, end-offset).
 249     BitMap::idx_t start_offset = heapWordToOffset(start_addr);
 250     BitMap::idx_t end_offset = heapWordToOffset(end_addr);
 251 
 252     start_offset = _bm.get_next_one_offset(start_offset, end_offset);
 253     while (start_offset < end_offset) {
 254       HeapWord* obj_addr = offsetToHeapWord(start_offset);
 255       oop obj = (oop) obj_addr;
 256       if (!cl->do_bit(start_offset)) {
 257         return false;
 258       }
 259       HeapWord* next_addr = MIN2(obj_addr + obj->size(), end_addr);
 260       BitMap::idx_t next_offset = heapWordToOffset(next_addr);
 261       start_offset = _bm.get_next_one_offset(next_offset, end_offset);
 262     }
 263   }
 264   return true;
 265 }
 266 
 267 inline bool CMBitMapRO::iterate(BitMapClosure* cl) {
 268   MemRegion mr(startWord(), sizeInWords());
 269   return iterate(cl, mr);
 270 }
 271 
 272 inline void CMTask::push(oop obj) {
 273   HeapWord* objAddr = (HeapWord*) obj;
 274   assert(_g1h->is_in_g1_reserved(objAddr), "invariant");
 275   assert(!_g1h->is_on_master_free_list(
 276               _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant");
 277   assert(!_g1h->is_obj_ill(obj), "invariant");
 278   assert(_nextMarkBitMap->isMarked(objAddr), "invariant");
 279 
 280   if (_cm->verbose_high()) {
 281     gclog_or_tty->print_cr("[%d] pushing "PTR_FORMAT, _task_id, (void*) obj);
 282   }
 283 
 284   if (!_task_queue->push(obj)) {
 285     // The local task queue looks full. We need to push some entries
 286     // to the global stack.
 287 
 288     if (_cm->verbose_medium()) {
 289       gclog_or_tty->print_cr("[%d] task queue overflow, "
 290                              "moving entries to the global stack",
 291                              _task_id);
 292     }
 293     move_entries_to_global_stack();
 294 
 295     // this should succeed since, even if we overflow the global
 296     // stack, we should have definitely removed some entries from the
 297     // local queue. So, there must be space on it.
 298     bool success = _task_queue->push(obj);
 299     assert(success, "invariant");
 300   }
 301 
 302   statsOnly( int tmp_size = _task_queue->size();
 303              if (tmp_size > _local_max_size) {
 304                _local_max_size = tmp_size;
 305              }
 306              ++_local_pushes );
 307 }
 308 
 309 // This determines whether the method below will check both the local
 310 // and global fingers when determining whether to push on the stack a
 311 // gray object (value 1) or whether it will only check the global one
 312 // (value 0). The tradeoffs are that the former will be a bit more
 313 // accurate and possibly push less on the stack, but it might also be
 314 // a little bit slower.
 315 
 316 #define _CHECK_BOTH_FINGERS_      1
 317 
 318 inline void CMTask::deal_with_reference(oop obj) {
 319   if (_cm->verbose_high()) {
 320     gclog_or_tty->print_cr("[%d] we're dealing with reference = "PTR_FORMAT,
 321                            _task_id, (void*) obj);
 322   }
 323 
 324   ++_refs_reached;
 325 
 326   HeapWord* objAddr = (HeapWord*) obj;
 327   assert(obj->is_oop_or_null(true /* ignore mark word */), "Error");
 328   if (_g1h->is_in_g1_reserved(objAddr)) {
 329     assert(obj != NULL, "null check is implicit");
 330     if (!_nextMarkBitMap->isMarked(objAddr)) {
 331       // Only get the containing region if the object is not marked on the
 332       // bitmap (otherwise, it's a waste of time since we won't do
 333       // anything with it).
 334       HeapRegion* hr = _g1h->heap_region_containing_raw(obj);
 335       if (!hr->obj_allocated_since_next_marking(obj)) {
 336         if (_cm->verbose_high()) {
 337           gclog_or_tty->print_cr("[%d] "PTR_FORMAT" is not considered marked",
 338                                  _task_id, (void*) obj);
 339         }
 340 
 341         // we need to mark it first
 342         if (_cm->par_mark_and_count(obj, hr, _marked_bytes_array, _card_bm)) {
 343           // No OrderAccess:store_load() is needed. It is implicit in the
 344           // CAS done in CMBitMap::parMark() call in the routine above.
 345           HeapWord* global_finger = _cm->finger();
 346 
 347 #if _CHECK_BOTH_FINGERS_
 348           // we will check both the local and global fingers
 349 
 350           if (_finger != NULL && objAddr < _finger) {
 351             if (_cm->verbose_high()) {
 352               gclog_or_tty->print_cr("[%d] below the local finger ("PTR_FORMAT"), "
 353                                      "pushing it", _task_id, _finger);
 354             }
 355             push(obj);
 356           } else if (_curr_region != NULL && objAddr < _region_limit) {
 357             // do nothing
 358           } else if (objAddr < global_finger) {
 359             // Notice that the global finger might be moving forward
 360             // concurrently. This is not a problem. In the worst case, we
 361             // mark the object while it is above the global finger and, by
 362             // the time we read the global finger, it has moved forward
 363             // passed this object. In this case, the object will probably
 364             // be visited when a task is scanning the region and will also
 365             // be pushed on the stack. So, some duplicate work, but no
 366             // correctness problems.
 367 
 368             if (_cm->verbose_high()) {
 369               gclog_or_tty->print_cr("[%d] below the global finger "
 370                                      "("PTR_FORMAT"), pushing it",
 371                                      _task_id, global_finger);
 372             }
 373             push(obj);
 374           } else {
 375             // do nothing
 376           }
 377 #else // _CHECK_BOTH_FINGERS_
 378           // we will only check the global finger
 379 
 380           if (objAddr < global_finger) {
 381             // see long comment above
 382 
 383             if (_cm->verbose_high()) {
 384               gclog_or_tty->print_cr("[%d] below the global finger "
 385                                      "("PTR_FORMAT"), pushing it",
 386                                      _task_id, global_finger);
 387             }
 388             push(obj);
 389           }
 390 #endif // _CHECK_BOTH_FINGERS_
 391         }
 392       }
 393     }
 394   }
 395 }
 396 
 397 inline void ConcurrentMark::markPrev(oop p) {
 398   assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity");
 399   // Note we are overriding the read-only view of the prev map here, via
 400   // the cast.
 401   ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);
 402 }
 403 
 404 inline void ConcurrentMark::grayRoot(oop obj, size_t word_size,
 405                                      uint worker_id, HeapRegion* hr) {
 406   assert(obj != NULL, "pre-condition");
 407   HeapWord* addr = (HeapWord*) obj;
 408   if (hr == NULL) {
 409     hr = _g1h->heap_region_containing_raw(addr);
 410   } else {
 411     assert(hr->is_in(addr), "pre-condition");
 412   }
 413   assert(hr != NULL, "sanity");
 414   // Given that we're looking for a region that contains an object
 415   // header it's impossible to get back a HC region.
 416   assert(!hr->continuesHumongous(), "sanity");
 417 
 418   // We cannot assert that word_size == obj->size() given that obj
 419   // might not be in a consistent state (another thread might be in
 420   // the process of copying it). So the best thing we can do is to
 421   // assert that word_size is under an upper bound which is its
 422   // containing region's capacity.
 423   assert(word_size * HeapWordSize <= hr->capacity(),
 424          err_msg("size: "SIZE_FORMAT" capacity: "SIZE_FORMAT" "HR_FORMAT,
 425                  word_size * HeapWordSize, hr->capacity(),
 426                  HR_FORMAT_PARAMS(hr)));
 427 
 428   if (addr < hr->next_top_at_mark_start()) {
 429     if (!_nextMarkBitMap->isMarked(addr)) {
 430       par_mark_and_count(obj, word_size, hr, worker_id);
 431     }
 432   }
 433 }
 434 
 435 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_INLINE_HPP