1 /*

     2  * Copyright (c) 2001, 2015, 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_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 == g1h->heap_region_containing(start), "sanity");

    93   assert(marked_bytes_array != NULL, "pre-condition");

    94   assert(task_card_bm != NULL, "pre-condition");

    95 

    96   // Add to the task local marked bytes for this region.

    97   marked_bytes_array[index] += region_size_bytes;

    98 

    99   BitMap::idx_t start_idx = card_bitmap_index_for(start);

   100   BitMap::idx_t end_idx = card_bitmap_index_for(end);

   101 

   102   // Note: if we're looking at the last region in heap - end

   103   // could be actually just beyond the end of the heap; end_idx

   104   // will then correspond to a (non-existent) card that is also

   105   // just beyond the heap.

   106   if (g1h->is_in_g1_reserved(end) && !ct_bs->is_card_aligned(end)) {

   107     // end of region is not card aligned - increment 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 object in the given task/worker counting data structures.

   118 inline void ConcurrentMark::count_object(oop obj,

   119                                          HeapRegion* hr,

   120                                          size_t* marked_bytes_array,

   121                                          BitMap* task_card_bm,

   122                                          size_t word_size) {

   123   assert(!hr->is_continues_humongous(), "Cannot enter count_object with continues humongous");

   124   if (!hr->is_starts_humongous()) {

   125     MemRegion mr((HeapWord*)obj, word_size);

   126     count_region(mr, hr, marked_bytes_array, task_card_bm);

   127   } else {

   128     do {

   129       MemRegion mr(hr->bottom(), hr->top());

   130       count_region(mr, hr, marked_bytes_array, task_card_bm);

   131       hr = _g1h->next_region_in_humongous(hr);

   132     } while (hr != NULL);

   133   }

   134 }

   135 

   136 // Attempts to mark the given object and, if successful, counts

   137 // the object in the given task/worker counting structures.

   138 inline bool ConcurrentMark::par_mark_and_count(oop obj,

   139                                                HeapRegion* hr,

   140                                                size_t* marked_bytes_array,

   141                                                BitMap* task_card_bm) {

   142   if (_nextMarkBitMap->parMark((HeapWord*)obj)) {

   143     // Update the task specific count data for the object.

   144     count_object(obj, hr, marked_bytes_array, task_card_bm, obj->size());

   145     return true;

   146   }

   147   return false;

   148 }

   149 

   150 // Attempts to mark the given object and, if successful, counts

   151 // the object in the task/worker counting structures for the

   152 // given worker id.

   153 inline bool ConcurrentMark::par_mark_and_count(oop obj,

   154                                                size_t word_size,

   155                                                HeapRegion* hr,

   156                                                uint worker_id) {

   157   if (_nextMarkBitMap->parMark((HeapWord*)obj)) {

   158     size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);

   159     BitMap* task_card_bm = count_card_bitmap_for(worker_id);

   160     count_object(obj, hr, marked_bytes_array, task_card_bm, word_size);

   161     return true;

   162   }

   163   return false;

   164 }

   165 

   166 inline bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {

   167   HeapWord* start_addr = MAX2(startWord(), mr.start());

   168   HeapWord* end_addr = MIN2(endWord(), mr.end());

   169 

   170   if (end_addr > start_addr) {

   171     // Right-open interval [start-offset, end-offset).

   172     BitMap::idx_t start_offset = heapWordToOffset(start_addr);

   173     BitMap::idx_t end_offset = heapWordToOffset(end_addr);

   174 

   175     start_offset = _bm.get_next_one_offset(start_offset, end_offset);

   176     while (start_offset < end_offset) {

   177       if (!cl->do_bit(start_offset)) {

   178         return false;

   179       }

   180       HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr);

   181       BitMap::idx_t next_offset = heapWordToOffset(next_addr);

   182       start_offset = _bm.get_next_one_offset(next_offset, end_offset);

   183     }

   184   }

   185   return true;

   186 }

   187 

   188 #define check_mark(addr)                                                       \

   189   assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize),      \

   190          "outside underlying space?");                                         \

   191   assert(G1CollectedHeap::heap()->is_in_exact(addr),                           \

   192          "Trying to access not available bitmap " PTR_FORMAT                   \

   193          " corresponding to " PTR_FORMAT " (%u)",                              \

   194          p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr));

   195 

   196 inline void CMBitMap::mark(HeapWord* addr) {

   197   check_mark(addr);

   198   _bm.set_bit(heapWordToOffset(addr));

   199 }

   200 

   201 inline void CMBitMap::clear(HeapWord* addr) {

   202   check_mark(addr);

   203   _bm.clear_bit(heapWordToOffset(addr));

   204 }

   205 

   206 inline bool CMBitMap::parMark(HeapWord* addr) {

   207   check_mark(addr);

   208   return _bm.par_set_bit(heapWordToOffset(addr));

   209 }

   210 

   211 #undef check_mark

   212 

   213 template<typename Fn>

   214 inline void CMMarkStack::iterate(Fn fn) {

   215   assert(_saved_index == _index, "saved index: %d index: %d", _saved_index, _index);

   216   for (int i = 0; i < _index; ++i) {

   217     fn(_base[i]);

   218   }

   219 }

   220 

   221 // It scans an object and visits its children.

   222 inline void CMTask::scan_object(oop obj) { process_grey_object<true>(obj); }

   223 

   224 inline void CMTask::push(oop obj) {

   225   HeapWord* objAddr = (HeapWord*) obj;

   226   assert(_g1h->is_in_g1_reserved(objAddr), "invariant");

   227   assert(!_g1h->is_on_master_free_list(

   228               _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant");

   229   assert(!_g1h->is_obj_ill(obj), "invariant");

   230   assert(_nextMarkBitMap->isMarked(objAddr), "invariant");

   231 

   232   if (!_task_queue->push(obj)) {

   233     // The local task queue looks full. We need to push some entries

   234     // to the global stack.

   235     move_entries_to_global_stack();

   236 

   237     // this should succeed since, even if we overflow the global

   238     // stack, we should have definitely removed some entries from the

   239     // local queue. So, there must be space on it.

   240     bool success = _task_queue->push(obj);

   241     assert(success, "invariant");

   242   }

   243 }

   244 

   245 inline bool CMTask::is_below_finger(oop obj, HeapWord* global_finger) const {

   246   // If obj is above the global finger, then the mark bitmap scan

   247   // will find it later, and no push is needed.  Similarly, if we have

   248   // a current region and obj is between the local finger and the

   249   // end of the current region, then no push is needed.  The tradeoff

   250   // of checking both vs only checking the global finger is that the

   251   // local check will be more accurate and so result in fewer pushes,

   252   // but may also be a little slower.

   253   HeapWord* objAddr = (HeapWord*)obj;

   254   if (_finger != NULL) {

   255     // We have a current region.

   256 

   257     // Finger and region values are all NULL or all non-NULL.  We

   258     // use _finger to check since we immediately use its value.

   259     assert(_curr_region != NULL, "invariant");

   260     assert(_region_limit != NULL, "invariant");

   261     assert(_region_limit <= global_finger, "invariant");

   262 

   263     // True if obj is less than the local finger, or is between

   264     // the region limit and the global finger.

   265     if (objAddr < _finger) {

   266       return true;

   267     } else if (objAddr < _region_limit) {

   268       return false;

   269     } // Else check global finger.

   270   }

   271   // Check global finger.

   272   return objAddr < global_finger;

   273 }

   274 

   275 template<bool scan>

   276 inline void CMTask::process_grey_object(oop obj) {

   277   assert(scan || obj->is_typeArray(), "Skipping scan of grey non-typeArray");

   278   assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");

   279 

   280   size_t obj_size = obj->size();

   281   _words_scanned += obj_size;

   282 

   283   if (scan) {

   284     obj->oop_iterate(_cm_oop_closure);

   285   }

   286   check_limits();

   287 }

   288 

   289 

   290 

   291 inline void CMTask::make_reference_grey(oop obj, HeapRegion* hr) {

   292   if (_cm->par_mark_and_count(obj, hr, _marked_bytes_array, _card_bm)) {

   293     // No OrderAccess:store_load() is needed. It is implicit in the

   294     // CAS done in CMBitMap::parMark() call in the routine above.

   295     HeapWord* global_finger = _cm->finger();

   296 

   297     // We only need to push a newly grey object on the mark

   298     // stack if it is in a section of memory the mark bitmap

   299     // scan has already examined.  Mark bitmap scanning

   300     // maintains progress "fingers" for determining that.

   301     //

   302     // Notice that the global finger might be moving forward

   303     // concurrently. This is not a problem. In the worst case, we

   304     // mark the object while it is above the global finger and, by

   305     // the time we read the global finger, it has moved forward

   306     // past this object. In this case, the object will probably

   307     // be visited when a task is scanning the region and will also

   308     // be pushed on the stack. So, some duplicate work, but no

   309     // correctness problems.

   310     if (is_below_finger(obj, global_finger)) {

   311       if (obj->is_typeArray()) {

   312         // Immediately process arrays of primitive types, rather

   313         // than pushing on the mark stack.  This keeps us from

   314         // adding humongous objects to the mark stack that might

   315         // be reclaimed before the entry is processed - see

   316         // selection of candidates for eager reclaim of humongous

   317         // objects.  The cost of the additional type test is

   318         // mitigated by avoiding a trip through the mark stack,

   319         // by only doing a bookkeeping update and avoiding the

   320         // actual scan of the object - a typeArray contains no

   321         // references, and the metadata is built-in.

   322         process_grey_object<false>(obj);

   323       } else {

   324         push(obj);

   325       }

   326     }

   327   }

   328 }

   329 

   330 inline void CMTask::deal_with_reference(oop obj) {

   331   increment_refs_reached();

   332 

   333   HeapWord* objAddr = (HeapWord*) obj;

   334   assert(obj->is_oop_or_null(true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(obj));

   335   if (_g1h->is_in_g1_reserved(objAddr)) {

   336     assert(obj != NULL, "null check is implicit");

   337     if (!_nextMarkBitMap->isMarked(objAddr)) {

   338       // Only get the containing region if the object is not marked on the

   339       // bitmap (otherwise, it's a waste of time since we won't do

   340       // anything with it).

   341       HeapRegion* hr = _g1h->heap_region_containing(obj);

   342       if (!hr->obj_allocated_since_next_marking(obj)) {

   343         make_reference_grey(obj, hr);

   344       }

   345     }

   346   }

   347 }

   348 

   349 inline void ConcurrentMark::markPrev(oop p) {

   350   assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity");

   351   // Note we are overriding the read-only view of the prev map here, via

   352   // the cast.

   353   ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);

   354 }

   355 

   356 inline void ConcurrentMark::grayRoot(oop obj, size_t word_size,

   357                                      uint worker_id, HeapRegion* hr) {

   358   assert(obj != NULL, "pre-condition");

   359   HeapWord* addr = (HeapWord*) obj;

   360   if (hr == NULL) {

   361     hr = _g1h->heap_region_containing(addr);

   362   } else {

   363     assert(hr->is_in(addr), "pre-condition");

   364   }

   365   assert(hr != NULL, "sanity");

   366   // Given that we're looking for a region that contains an object

   367   // header it's impossible to get back a HC region.

   368   assert(!hr->is_continues_humongous(), "sanity");

   369 

   370   if (addr < hr->next_top_at_mark_start()) {

   371     if (!_nextMarkBitMap->isMarked(addr)) {

   372       par_mark_and_count(obj, word_size, hr, worker_id);

   373     }

   374   }

   375 }

   376 

   377 #endif // SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP