1 /*
   2  * Copyright (c) 2001, 2012, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  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 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 - incremement 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 memory region, which may be a single object, in the
 129 // task/worker counting data structures for the given worker id.
 130 inline void ConcurrentMark::count_region(MemRegion mr, uint worker_id) {
 131   HeapWord* addr = mr.start();
 132   HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
 133   count_region(mr, hr, worker_id);
 134 }
 135 
 136 // Counts the given object in the given task/worker counting data structures.
 137 inline void ConcurrentMark::count_object(oop obj,
 138                                          HeapRegion* hr,
 139                                          size_t* marked_bytes_array,
 140                                          BitMap* task_card_bm) {
 141   MemRegion mr((HeapWord*)obj, obj->size());
 142   count_region(mr, hr, marked_bytes_array, task_card_bm);
 143 }
 144 
 145 // Counts the given object in the task/worker counting data
 146 // structures for the given worker id.
 147 inline void ConcurrentMark::count_object(oop obj,
 148                                          HeapRegion* hr,
 149                                          uint worker_id) {
 150   size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);
 151   BitMap* task_card_bm = count_card_bitmap_for(worker_id);
 152   HeapWord* addr = (HeapWord*) obj;
 153   count_object(obj, hr, marked_bytes_array, task_card_bm);
 154 }
 155 
 156 // Attempts to mark the given object and, if successful, counts
 157 // the object in the given task/worker counting structures.
 158 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 159                                                HeapRegion* hr,
 160                                                size_t* marked_bytes_array,
 161                                                BitMap* task_card_bm) {
 162   HeapWord* addr = (HeapWord*)obj;
 163   if (_nextMarkBitMap->parMark(addr)) {
 164     // Update the task specific count data for the object.
 165     count_object(obj, hr, marked_bytes_array, task_card_bm);
 166     return true;
 167   }
 168   return false;
 169 }
 170 
 171 // Attempts to mark the given object and, if successful, counts
 172 // the object in the task/worker counting structures for the
 173 // given worker id.
 174 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 175                                                size_t word_size,
 176                                                HeapRegion* hr,
 177                                                uint worker_id) {
 178   HeapWord* addr = (HeapWord*)obj;
 179   if (_nextMarkBitMap->parMark(addr)) {
 180     MemRegion mr(addr, word_size);
 181     count_region(mr, hr, worker_id);
 182     return true;
 183   }
 184   return false;
 185 }
 186 
 187 // Attempts to mark the given object and, if successful, counts
 188 // the object in the task/worker counting structures for the
 189 // given worker id.
 190 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 191                                                HeapRegion* hr,
 192                                                uint worker_id) {
 193   HeapWord* addr = (HeapWord*)obj;
 194   if (_nextMarkBitMap->parMark(addr)) {
 195     // Update the task specific count data for the object.
 196     count_object(obj, hr, worker_id);
 197     return true;
 198   }
 199   return false;
 200 }
 201 
 202 // As above - but we don't know the heap region containing the
 203 // object and so have to supply it.
 204 inline bool ConcurrentMark::par_mark_and_count(oop obj, uint worker_id) {
 205   HeapWord* addr = (HeapWord*)obj;
 206   HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
 207   return par_mark_and_count(obj, hr, worker_id);
 208 }
 209 
 210 // Similar to the above routine but we already know the size, in words, of
 211 // the object that we wish to mark/count
 212 inline bool ConcurrentMark::par_mark_and_count(oop obj,
 213                                                size_t word_size,
 214                                                uint worker_id) {
 215   HeapWord* addr = (HeapWord*)obj;
 216   if (_nextMarkBitMap->parMark(addr)) {
 217     // Update the task specific count data for the object.
 218     MemRegion mr(addr, word_size);
 219     count_region(mr, worker_id);
 220     return true;
 221   }
 222   return false;
 223 }
 224 
 225 // Unconditionally mark the given object, and unconditinally count
 226 // the object in the counting structures for worker id 0.
 227 // Should *not* be called from parallel code.
 228 inline bool ConcurrentMark::mark_and_count(oop obj, HeapRegion* hr) {
 229   HeapWord* addr = (HeapWord*)obj;
 230   _nextMarkBitMap->mark(addr);
 231   // Update the task specific count data for the object.
 232   count_object(obj, hr, 0 /* worker_id */);
 233   return true;
 234 }
 235 
 236 // As above - but we don't have the heap region containing the
 237 // object, so we have to supply it.
 238 inline bool ConcurrentMark::mark_and_count(oop obj) {
 239   HeapWord* addr = (HeapWord*)obj;
 240   HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
 241   return mark_and_count(obj, hr);
 242 }
 243 
 244 inline bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
 245   HeapWord* start_addr = MAX2(startWord(), mr.start());
 246   HeapWord* end_addr = MIN2(endWord(), mr.end());
 247 
 248   if (end_addr > start_addr) {
 249     // Right-open interval [start-offset, end-offset).
 250     BitMap::idx_t start_offset = heapWordToOffset(start_addr);
 251     BitMap::idx_t end_offset = heapWordToOffset(end_addr);
 252 
 253     start_offset = _bm.get_next_one_offset(start_offset, end_offset);
 254     while (start_offset < end_offset) {
 255       HeapWord* obj_addr = offsetToHeapWord(start_offset);
 256       oop obj = (oop) obj_addr;
 257       if (!cl->do_bit(start_offset)) {
 258         return false;
 259       }
 260       HeapWord* next_addr = MIN2(obj_addr + obj->size(), end_addr);
 261       BitMap::idx_t next_offset = heapWordToOffset(next_addr);
 262       start_offset = _bm.get_next_one_offset(next_offset, end_offset);
 263     }
 264   }
 265   return true;
 266 }
 267 
 268 inline bool CMBitMapRO::iterate(BitMapClosure* cl) {
 269   MemRegion mr(startWord(), sizeInWords());
 270   return iterate(cl, mr);
 271 }
 272 
 273 inline void CMTask::push(oop obj) {
 274   HeapWord* objAddr = (HeapWord*) obj;
 275   assert(_g1h->is_in_g1_reserved(objAddr), "invariant");
 276   assert(!_g1h->is_on_master_free_list(
 277               _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant");
 278   assert(!_g1h->is_obj_ill(obj), "invariant");
 279   assert(_nextMarkBitMap->isMarked(objAddr), "invariant");
 280 
 281   if (_cm->verbose_high()) {
 282     gclog_or_tty->print_cr("[%d] pushing "PTR_FORMAT, _task_id, (void*) obj);
 283   }
 284 
 285   if (!_task_queue->push(obj)) {
 286     // The local task queue looks full. We need to push some entries
 287     // to the global stack.
 288 
 289     if (_cm->verbose_medium()) {
 290       gclog_or_tty->print_cr("[%d] task queue overflow, "
 291                              "moving entries to the global stack",
 292                              _task_id);
 293     }
 294     move_entries_to_global_stack();
 295 
 296     // this should succeed since, even if we overflow the global
 297     // stack, we should have definitely removed some entries from the
 298     // local queue. So, there must be space on it.
 299     bool success = _task_queue->push(obj);
 300     assert(success, "invariant");
 301   }
 302 
 303   statsOnly( int tmp_size = _task_queue->size();
 304              if (tmp_size > _local_max_size) {
 305                _local_max_size = tmp_size;
 306              }
 307              ++_local_pushes );
 308 }
 309 
 310 // This determines whether the method below will check both the local
 311 // and global fingers when determining whether to push on the stack a
 312 // gray object (value 1) or whether it will only check the global one
 313 // (value 0). The tradeoffs are that the former will be a bit more
 314 // accurate and possibly push less on the stack, but it might also be
 315 // a little bit slower.
 316 
 317 #define _CHECK_BOTH_FINGERS_      1
 318 
 319 inline void CMTask::deal_with_reference(oop obj) {
 320   if (_cm->verbose_high()) {
 321     gclog_or_tty->print_cr("[%d] we're dealing with reference = "PTR_FORMAT,
 322                            _task_id, (void*) obj);
 323   }
 324 
 325   ++_refs_reached;
 326 
 327   HeapWord* objAddr = (HeapWord*) obj;
 328   assert(obj->is_oop_or_null(true /* ignore mark word */), "Error");
 329   if (_g1h->is_in_g1_reserved(objAddr)) {
 330     assert(obj != NULL, "null check is implicit");
 331     if (!_nextMarkBitMap->isMarked(objAddr)) {
 332       // Only get the containing region if the object is not marked on the
 333       // bitmap (otherwise, it's a waste of time since we won't do
 334       // anything with it).
 335       HeapRegion* hr = _g1h->heap_region_containing_raw(obj);
 336       if (!hr->obj_allocated_since_next_marking(obj)) {
 337         if (_cm->verbose_high()) {
 338           gclog_or_tty->print_cr("[%d] "PTR_FORMAT" is not considered marked",
 339                                  _task_id, (void*) obj);
 340         }
 341 
 342         // we need to mark it first
 343         if (_cm->par_mark_and_count(obj, hr, _marked_bytes_array, _card_bm)) {
 344           // No OrderAccess:store_load() is needed. It is implicit in the
 345           // CAS done in CMBitMap::parMark() call in the routine above.
 346           HeapWord* global_finger = _cm->finger();
 347 
 348 #if _CHECK_BOTH_FINGERS_
 349           // we will check both the local and global fingers
 350 
 351           if (_finger != NULL && objAddr < _finger) {
 352             if (_cm->verbose_high()) {
 353               gclog_or_tty->print_cr("[%d] below the local finger ("PTR_FORMAT"), "
 354                                      "pushing it", _task_id, _finger);
 355             }
 356             push(obj);
 357           } else if (_curr_region != NULL && objAddr < _region_limit) {
 358             // do nothing
 359           } else if (objAddr < global_finger) {
 360             // Notice that the global finger might be moving forward
 361             // concurrently. This is not a problem. In the worst case, we
 362             // mark the object while it is above the global finger and, by
 363             // the time we read the global finger, it has moved forward
 364             // passed this object. In this case, the object will probably
 365             // be visited when a task is scanning the region and will also
 366             // be pushed on the stack. So, some duplicate work, but no
 367             // correctness problems.
 368 
 369             if (_cm->verbose_high()) {
 370               gclog_or_tty->print_cr("[%d] below the global finger "
 371                                      "("PTR_FORMAT"), pushing it",
 372                                      _task_id, global_finger);
 373             }
 374             push(obj);
 375           } else {
 376             // do nothing
 377           }
 378 #else // _CHECK_BOTH_FINGERS_
 379           // we will only check the global finger
 380 
 381           if (objAddr < global_finger) {
 382             // see long comment above
 383 
 384             if (_cm->verbose_high()) {
 385               gclog_or_tty->print_cr("[%d] below the global finger "
 386                                      "("PTR_FORMAT"), pushing it",
 387                                      _task_id, global_finger);
 388             }
 389             push(obj);
 390           }
 391 #endif // _CHECK_BOTH_FINGERS_
 392         }
 393       }
 394     }
 395   }
 396 }
 397 
 398 inline void ConcurrentMark::markPrev(oop p) {
 399   assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity");
 400   // Note we are overriding the read-only view of the prev map here, via
 401   // the cast.
 402   ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);
 403 }
 404 
 405 inline void ConcurrentMark::grayRoot(oop obj, size_t word_size,
 406                                      uint worker_id, HeapRegion* hr) {
 407   assert(obj != NULL, "pre-condition");
 408   HeapWord* addr = (HeapWord*) obj;
 409   if (hr == NULL) {
 410     hr = _g1h->heap_region_containing_raw(addr);
 411   } else {
 412     assert(hr->is_in(addr), "pre-condition");
 413   }
 414   assert(hr != NULL, "sanity");
 415   // Given that we're looking for a region that contains an object
 416   // header it's impossible to get back a HC region.
 417   assert(!hr->continuesHumongous(), "sanity");
 418 
 419   // We cannot assert that word_size == obj->size() given that obj
 420   // might not be in a consistent state (another thread might be in
 421   // the process of copying it). So the best thing we can do is to
 422   // assert that word_size is under an upper bound which is its
 423   // containing region's capacity.
 424   assert(word_size * HeapWordSize <= hr->capacity(),
 425          err_msg("size: "SIZE_FORMAT" capacity: "SIZE_FORMAT" "HR_FORMAT,
 426                  word_size * HeapWordSize, hr->capacity(),
 427                  HR_FORMAT_PARAMS(hr)));
 428 
 429   if (addr < hr->next_top_at_mark_start()) {
 430     if (!_nextMarkBitMap->isMarked(addr)) {
 431       par_mark_and_count(obj, word_size, hr, worker_id);
 432     }
 433   }
 434 }
 435 
 436 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_INLINE_HPP