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 /*

  * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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  */

 #include "precompiled.hpp"

 #include "memory/allocation.inline.hpp"

 #include "memory/cardTableModRefBS.hpp"

 #include "memory/cardTableRS.hpp"

 #include "memory/sharedHeap.hpp"

 #include "memory/space.hpp"

 #include "memory/space.inline.hpp"

 #include "memory/universe.hpp"

 #include "runtime/java.hpp"

 #include "runtime/mutexLocker.hpp"

 #include "runtime/virtualspace.hpp"

 #include "services/memTracker.hpp"

 #include "utilities/macros.hpp"

 #ifdef COMPILER1

 #include "c1/c1_LIR.hpp"

 #include "c1/c1_LIRGenerator.hpp"

 #endif

 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and

 // enumerate ref fields that have been modified (since the last

 // enumeration.)

 size_t CardTableModRefBS::cards_required(size_t covered_words)

 {

   // Add one for a guard card, used to detect errors.

   const size_t words = align_size_up(covered_words, card_size_in_words);

   return words / card_size_in_words + 1;

 }

 size_t CardTableModRefBS::compute_byte_map_size()

 {

   assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,

                                         "unitialized, check declaration order");

   assert(_page_size != 0, "unitialized, check declaration order");

   const size_t granularity = os::vm_allocation_granularity();

   return align_size_up(_guard_index + 1, MAX2(_page_size, granularity));

 }

 CardTableModRefBS::CardTableModRefBS(MemRegion whole_heap,

                                      int max_covered_regions):

   ModRefBarrierSet(max_covered_regions),

   _whole_heap(whole_heap),

   _guard_index(cards_required(whole_heap.word_size()) - 1),

   _last_valid_index(_guard_index - 1),

   _page_size(os::vm_page_size()),

   _byte_map_size(compute_byte_map_size())

 {

   _kind = BarrierSet::CardTableModRef;

   HeapWord* low_bound  = _whole_heap.start();

   HeapWord* high_bound = _whole_heap.end();

   assert((uintptr_t(low_bound)  & (card_size - 1))  == 0, "heap must start at card boundary");

   assert((uintptr_t(high_bound) & (card_size - 1))  == 0, "heap must end at card boundary");

   assert(card_size <= 512, "card_size must be less than 512"); // why?

   _covered   = new MemRegion[max_covered_regions];

   _committed = new MemRegion[max_covered_regions];

   if (_covered == NULL || _committed == NULL) {

     vm_exit_during_initialization("couldn't alloc card table covered region set.");

   }

   _cur_covered_regions = 0;

   const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 :

     MAX2(_page_size, (size_t) os::vm_allocation_granularity());

   ReservedSpace heap_rs(_byte_map_size, rs_align, false);

   MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtGC);

   os::trace_page_sizes("card table", _guard_index + 1, _guard_index + 1,

                        _page_size, heap_rs.base(), heap_rs.size());

   if (!heap_rs.is_reserved()) {

     vm_exit_during_initialization("Could not reserve enough space for the "

                                   "card marking array");

   }

   // The assember store_check code will do an unsigned shift of the oop,

   // then add it to byte_map_base, i.e.

   //

   //   _byte_map = byte_map_base + (uintptr_t(low_bound) >> card_shift)

   _byte_map = (jbyte*) heap_rs.base();

   byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);

   assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");

   assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");

   jbyte* guard_card = &_byte_map[_guard_index];

   uintptr_t guard_page = align_size_down((uintptr_t)guard_card, _page_size);

   _guard_region = MemRegion((HeapWord*)guard_page, _page_size);

   os::commit_memory_or_exit((char*)guard_page, _page_size, _page_size,

                             !ExecMem, "card table last card");

   *guard_card = last_card;

    _lowest_non_clean =

     NEW_C_HEAP_ARRAY(CardArr, max_covered_regions, mtGC);

   _lowest_non_clean_chunk_size =

     NEW_C_HEAP_ARRAY(size_t, max_covered_regions, mtGC);

   _lowest_non_clean_base_chunk_index =

     NEW_C_HEAP_ARRAY(uintptr_t, max_covered_regions, mtGC);

   _last_LNC_resizing_collection =

     NEW_C_HEAP_ARRAY(int, max_covered_regions, mtGC);

   if (_lowest_non_clean == NULL

       || _lowest_non_clean_chunk_size == NULL

       || _lowest_non_clean_base_chunk_index == NULL

       || _last_LNC_resizing_collection == NULL)

     vm_exit_during_initialization("couldn't allocate an LNC array.");

   for (int i = 0; i < max_covered_regions; i++) {

     _lowest_non_clean[i] = NULL;

     _lowest_non_clean_chunk_size[i] = 0;

     _last_LNC_resizing_collection[i] = -1;

   }

   if (TraceCardTableModRefBS) {

     gclog_or_tty->print_cr("CardTableModRefBS::CardTableModRefBS: ");

     gclog_or_tty->print_cr("  "

                   "  &_byte_map[0]: " INTPTR_FORMAT

                   "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,

                   p2i(&_byte_map[0]),

                   p2i(&_byte_map[_last_valid_index]));

     gclog_or_tty->print_cr("  "

                   "  byte_map_base: " INTPTR_FORMAT,

                   p2i(byte_map_base));

   }

 }

 CardTableModRefBS::~CardTableModRefBS() {

   if (_covered) {

     delete[] _covered;

     _covered = NULL;

   }

   if (_committed) {

     delete[] _committed;

     _committed = NULL;

   }

   if (_lowest_non_clean) {

     FREE_C_HEAP_ARRAY(CardArr, _lowest_non_clean, mtGC);

     _lowest_non_clean = NULL;

   }

   if (_lowest_non_clean_chunk_size) {

     FREE_C_HEAP_ARRAY(size_t, _lowest_non_clean_chunk_size, mtGC);

     _lowest_non_clean_chunk_size = NULL;

   }

   if (_lowest_non_clean_base_chunk_index) {

     FREE_C_HEAP_ARRAY(uintptr_t, _lowest_non_clean_base_chunk_index, mtGC);

     _lowest_non_clean_base_chunk_index = NULL;

   }

   if (_last_LNC_resizing_collection) {

     FREE_C_HEAP_ARRAY(int, _last_LNC_resizing_collection, mtGC);

     _last_LNC_resizing_collection = NULL;

   }

 }

 int CardTableModRefBS::find_covering_region_by_base(HeapWord* base) {

   int i;

   for (i = 0; i < _cur_covered_regions; i++) {

     if (_covered[i].start() == base) return i;

     if (_covered[i].start() > base) break;

   }

   // If we didn't find it, create a new one.

   assert(_cur_covered_regions < _max_covered_regions,

          "too many covered regions");

   // Move the ones above up, to maintain sorted order.

   for (int j = _cur_covered_regions; j > i; j--) {

     _covered[j] = _covered[j-1];

     _committed[j] = _committed[j-1];

   }

   int res = i;

   _cur_covered_regions++;

   _covered[res].set_start(base);

   _covered[res].set_word_size(0);

   jbyte* ct_start = byte_for(base);

   uintptr_t ct_start_aligned = align_size_down((uintptr_t)ct_start, _page_size);

   _committed[res].set_start((HeapWord*)ct_start_aligned);

   _committed[res].set_word_size(0);

   return res;

 }

 int CardTableModRefBS::find_covering_region_containing(HeapWord* addr) {

   for (int i = 0; i < _cur_covered_regions; i++) {

     if (_covered[i].contains(addr)) {

       return i;

     }

   }

   assert(0, "address outside of heap?");

   return -1;

 }

 HeapWord* CardTableModRefBS::largest_prev_committed_end(int ind) const {

   HeapWord* max_end = NULL;

   for (int j = 0; j < ind; j++) {

     HeapWord* this_end = _committed[j].end();

     if (this_end > max_end) max_end = this_end;

   }

   return max_end;

 }

 MemRegion CardTableModRefBS::committed_unique_to_self(int self,

                                                       MemRegion mr) const {

   MemRegion result = mr;

   for (int r = 0; r < _cur_covered_regions; r += 1) {

     if (r != self) {

       result = result.minus(_committed[r]);

     }

   }

   // Never include the guard page.

   result = result.minus(_guard_region);

   return result;

 }

 void CardTableModRefBS::resize_covered_region(MemRegion new_region) {

   // We don't change the start of a region, only the end.

   assert(_whole_heap.contains(new_region),

            "attempt to cover area not in reserved area");

   debug_only(verify_guard();)

   // collided is true if the expansion would push into another committed region

   debug_only(bool collided = false;)

   int const ind = find_covering_region_by_base(new_region.start());

   MemRegion const old_region = _covered[ind];

   assert(old_region.start() == new_region.start(), "just checking");

   if (new_region.word_size() != old_region.word_size()) {

     // Commit new or uncommit old pages, if necessary.

     MemRegion cur_committed = _committed[ind];

     // Extend the end of this _commited region

     // to cover the end of any lower _committed regions.

     // This forms overlapping regions, but never interior regions.

     HeapWord* const max_prev_end = largest_prev_committed_end(ind);

     if (max_prev_end > cur_committed.end()) {

       cur_committed.set_end(max_prev_end);

     }

     // Align the end up to a page size (starts are already aligned).

     jbyte* const new_end = byte_after(new_region.last());

     HeapWord* new_end_aligned =

       (HeapWord*) align_size_up((uintptr_t)new_end, _page_size);

     assert(new_end_aligned >= (HeapWord*) new_end,

            "align up, but less");

     // Check the other regions (excludes "ind") to ensure that

     // the new_end_aligned does not intrude onto the committed

     // space of another region.

     int ri = 0;

     for (ri = 0; ri < _cur_covered_regions; ri++) {

       if (ri != ind) {

         if (_committed[ri].contains(new_end_aligned)) {

           // The prior check included in the assert

           // (new_end_aligned >= _committed[ri].start())

           // is redundant with the "contains" test.

           // Any region containing the new end

           // should start at or beyond the region found (ind)

           // for the new end (committed regions are not expected to

           // be proper subsets of other committed regions).

           assert(_committed[ri].start() >= _committed[ind].start(),

                  "New end of committed region is inconsistent");

           new_end_aligned = _committed[ri].start();

           // new_end_aligned can be equal to the start of its

           // committed region (i.e., of "ind") if a second

           // region following "ind" also start at the same location

           // as "ind".

           assert(new_end_aligned >= _committed[ind].start(),

             "New end of committed region is before start");

           debug_only(collided = true;)

           // Should only collide with 1 region

           break;

         }

       }

     }

 #ifdef ASSERT

     for (++ri; ri < _cur_covered_regions; ri++) {

       assert(!_committed[ri].contains(new_end_aligned),

         "New end of committed region is in a second committed region");

     }

 #endif

     // The guard page is always committed and should not be committed over.

     // "guarded" is used for assertion checking below and recalls the fact

     // that the would-be end of the new committed region would have

     // penetrated the guard page.

     HeapWord* new_end_for_commit = new_end_aligned;

     DEBUG_ONLY(bool guarded = false;)

     if (new_end_for_commit > _guard_region.start()) {

       new_end_for_commit = _guard_region.start();

       DEBUG_ONLY(guarded = true;)

     }

     if (new_end_for_commit > cur_committed.end()) {

       // Must commit new pages.

       MemRegion const new_committed =

         MemRegion(cur_committed.end(), new_end_for_commit);

       assert(!new_committed.is_empty(), "Region should not be empty here");

       os::commit_memory_or_exit((char*)new_committed.start(),

                                 new_committed.byte_size(), _page_size,

                                 !ExecMem, "card table expansion");

     // Use new_end_aligned (as opposed to new_end_for_commit) because

     // the cur_committed region may include the guard region.

     } else if (new_end_aligned < cur_committed.end()) {

       // Must uncommit pages.

       MemRegion const uncommit_region =

         committed_unique_to_self(ind, MemRegion(new_end_aligned,

                                                 cur_committed.end()));

       if (!uncommit_region.is_empty()) {

         // It is not safe to uncommit cards if the boundary between

         // the generations is moving.  A shrink can uncommit cards

         // owned by generation A but being used by generation B.

         if (!UseAdaptiveGCBoundary) {

           if (!os::uncommit_memory((char*)uncommit_region.start(),

                                    uncommit_region.byte_size())) {

             assert(false, "Card table contraction failed");

             // The call failed so don't change the end of the

             // committed region.  This is better than taking the

             // VM down.

             new_end_aligned = _committed[ind].end();

           }

         } else {

           new_end_aligned = _committed[ind].end();

         }

       }

     }

     // In any case, we can reset the end of the current committed entry.

     _committed[ind].set_end(new_end_aligned);

 #ifdef ASSERT

     // Check that the last card in the new region is committed according

     // to the tables.

     bool covered = false;

     for (int cr = 0; cr < _cur_covered_regions; cr++) {

       if (_committed[cr].contains(new_end - 1)) {

         covered = true;

         break;

       }

     }

     assert(covered, "Card for end of new region not committed");

 #endif

     // The default of 0 is not necessarily clean cards.

     jbyte* entry;

     if (old_region.last() < _whole_heap.start()) {

       entry = byte_for(_whole_heap.start());

     } else {

       entry = byte_after(old_region.last());

     }

     assert(index_for(new_region.last()) <  _guard_index,

       "The guard card will be overwritten");

     // This line commented out cleans the newly expanded region and

     // not the aligned up expanded region.

     // jbyte* const end = byte_after(new_region.last());

     jbyte* const end = (jbyte*) new_end_for_commit;

     assert((end >= byte_after(new_region.last())) || collided || guarded,

       "Expect to be beyond new region unless impacting another region");

     // do nothing if we resized downward.

 #ifdef ASSERT

     for (int ri = 0; ri < _cur_covered_regions; ri++) {

       if (ri != ind) {

         // The end of the new committed region should not

         // be in any existing region unless it matches

         // the start of the next region.

         assert(!_committed[ri].contains(end) ||

                (_committed[ri].start() == (HeapWord*) end),

                "Overlapping committed regions");

       }

     }

 #endif

     if (entry < end) {

       memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte)));

     }

   }

   // In any case, the covered size changes.

   _covered[ind].set_word_size(new_region.word_size());

   if (TraceCardTableModRefBS) {

     gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: ");

     gclog_or_tty->print_cr("  "

                   "  _covered[%d].start(): " INTPTR_FORMAT

                   "  _covered[%d].last(): " INTPTR_FORMAT,

                   ind, p2i(_covered[ind].start()),

                   ind, p2i(_covered[ind].last()));

     gclog_or_tty->print_cr("  "

                   "  _committed[%d].start(): " INTPTR_FORMAT

                   "  _committed[%d].last(): " INTPTR_FORMAT,

                   ind, p2i(_committed[ind].start()),

                   ind, p2i(_committed[ind].last()));

     gclog_or_tty->print_cr("  "

                   "  byte_for(start): " INTPTR_FORMAT

                   "  byte_for(last): " INTPTR_FORMAT,

                   p2i(byte_for(_covered[ind].start())),

                   p2i(byte_for(_covered[ind].last())));

     gclog_or_tty->print_cr("  "

                   "  addr_for(start): " INTPTR_FORMAT

                   "  addr_for(last): " INTPTR_FORMAT,

                   p2i(addr_for((jbyte*) _committed[ind].start())),

                   p2i(addr_for((jbyte*) _committed[ind].last())));

   }

   // Touch the last card of the covered region to show that it

   // is committed (or SEGV).

   debug_only((void) (*byte_for(_covered[ind].last()));)

   debug_only(verify_guard();)

 }

 // Note that these versions are precise!  The scanning code has to handle the

 // fact that the write barrier may be either precise or imprecise.

 void CardTableModRefBS::write_ref_field_work(void* field, oop newVal, bool release) {

   inline_write_ref_field(field, newVal, release);

 }

 void CardTableModRefBS::non_clean_card_iterate_possibly_parallel(Space* sp,

                                                                  MemRegion mr,

                                                                  OopsInGenClosure* cl,

                                                                  CardTableRS* ct) {

   if (!mr.is_empty()) {

     // Caller (process_roots()) claims that all GC threads

     // execute this call.  With UseDynamicNumberOfGCThreads now all

     // active GC threads execute this call.  The number of active GC

     // threads needs to be passed to par_non_clean_card_iterate_work()

     // to get proper partitioning and termination.

     //

     // This is an example of where n_par_threads() is used instead

     // of workers()->active_workers().  n_par_threads can be set to 0 to

     // turn off parallelism.  For example when this code is called as

     // part of verification and SharedHeap::process_roots() is being

     // used, then n_par_threads() may have been set to 0.  active_workers

     // is not overloaded with the meaning that it is a switch to disable

     // parallelism and so keeps the meaning of the number of

     // active gc workers.  If parallelism has not been shut off by

     // setting n_par_threads to 0, then n_par_threads should be

     // equal to active_workers.  When a different mechanism for shutting

     // off parallelism is used, then active_workers can be used in

     // place of n_par_threads.

     //  This is an example of a path where n_par_threads is

     // set to 0 to turn off parallism.

     //  [7] CardTableModRefBS::non_clean_card_iterate()

     //  [8] CardTableRS::younger_refs_in_space_iterate()

     //  [9] Generation::younger_refs_in_space_iterate()

     //  [10] OneContigSpaceCardGeneration::younger_refs_iterate()

     //  [11] CompactingPermGenGen::younger_refs_iterate()

     //  [12] CardTableRS::younger_refs_iterate()

     //  [13] SharedHeap::process_strong_roots()

     //  [14] G1CollectedHeap::verify()

     //  [15] Universe::verify()

     //  [16] G1CollectedHeap::do_collection_pause_at_safepoint()

     //

     int n_threads =  SharedHeap::heap()->n_par_threads();

     bool is_par = n_threads > 0;

     if (is_par) {

 #if INCLUDE_ALL_GCS

       assert(SharedHeap::heap()->n_par_threads() ==

              SharedHeap::heap()->workers()->active_workers(), "Mismatch");

       non_clean_card_iterate_parallel_work(sp, mr, cl, ct, n_threads);

 #else  // INCLUDE_ALL_GCS

       fatal("Parallel gc not supported here.");

 #endif // INCLUDE_ALL_GCS

     } else {

       // We do not call the non_clean_card_iterate_serial() version below because

       // we want to clear the cards (which non_clean_card_iterate_serial() does not

       // do for us): clear_cl here does the work of finding contiguous dirty ranges

       // of cards to process and clear.

       DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision(),

                                                        cl->gen_boundary());

       ClearNoncleanCardWrapper clear_cl(dcto_cl, ct);

       clear_cl.do_MemRegion(mr);

     }

   }

 }

 // The iterator itself is not MT-aware, but

 // MT-aware callers and closures can use this to

 // accomplish dirty card iteration in parallel. The

 // iterator itself does not clear the dirty cards, or

 // change their values in any manner.

 void CardTableModRefBS::non_clean_card_iterate_serial(MemRegion mr,

                                                       MemRegionClosure* cl) {

   bool is_par = (SharedHeap::heap()->n_par_threads() > 0);

   assert(!is_par ||

           (SharedHeap::heap()->n_par_threads() ==

           SharedHeap::heap()->workers()->active_workers()), "Mismatch");

   for (int i = 0; i < _cur_covered_regions; i++) {

     MemRegion mri = mr.intersection(_covered[i]);

     if (mri.word_size() > 0) {

       jbyte* cur_entry = byte_for(mri.last());

       jbyte* limit = byte_for(mri.start());

       while (cur_entry >= limit) {

         jbyte* next_entry = cur_entry - 1;

         if (*cur_entry != clean_card) {

           size_t non_clean_cards = 1;

           // Should the next card be included in this range of dirty cards.

           while (next_entry >= limit && *next_entry != clean_card) {

             non_clean_cards++;

             cur_entry = next_entry;

             next_entry--;

           }

           // The memory region may not be on a card boundary.  So that

           // objects beyond the end of the region are not processed, make

           // cur_cards precise with regard to the end of the memory region.

           MemRegion cur_cards(addr_for(cur_entry),

                               non_clean_cards * card_size_in_words);

           MemRegion dirty_region = cur_cards.intersection(mri);

           cl->do_MemRegion(dirty_region);

         }

         cur_entry = next_entry;

       }

     }

   }

 }

 void CardTableModRefBS::dirty_MemRegion(MemRegion mr) {

   assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");

   assert((HeapWord*)align_size_up  ((uintptr_t)mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );

   jbyte* cur  = byte_for(mr.start());

   jbyte* last = byte_after(mr.last());

   while (cur < last) {

     *cur = dirty_card;

     cur++;

   }

 }

 void CardTableModRefBS::invalidate(MemRegion mr, bool whole_heap) {

   assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");

   assert((HeapWord*)align_size_up  ((uintptr_t)mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );

   for (int i = 0; i < _cur_covered_regions; i++) {

     MemRegion mri = mr.intersection(_covered[i]);

     if (!mri.is_empty()) dirty_MemRegion(mri);

   }

 }

 void CardTableModRefBS::clear_MemRegion(MemRegion mr) {

   // Be conservative: only clean cards entirely contained within the

   // region.

   jbyte* cur;

   if (mr.start() == _whole_heap.start()) {

     cur = byte_for(mr.start());

   } else {

     assert(mr.start() > _whole_heap.start(), "mr is not covered.");

     cur = byte_after(mr.start() - 1);

   }

   jbyte* last = byte_after(mr.last());

   memset(cur, clean_card, pointer_delta(last, cur, sizeof(jbyte)));

 }

 void CardTableModRefBS::clear(MemRegion mr) {

   for (int i = 0; i < _cur_covered_regions; i++) {

     MemRegion mri = mr.intersection(_covered[i]);

     if (!mri.is_empty()) clear_MemRegion(mri);

   }

 }

 void CardTableModRefBS::dirty(MemRegion mr) {

   jbyte* first = byte_for(mr.start());

   jbyte* last  = byte_after(mr.last());

   memset(first, dirty_card, last-first);

 }

 // Unlike several other card table methods, dirty_card_iterate()

 // iterates over dirty cards ranges in increasing address order.

 void CardTableModRefBS::dirty_card_iterate(MemRegion mr,

                                            MemRegionClosure* cl) {

   for (int i = 0; i < _cur_covered_regions; i++) {

     MemRegion mri = mr.intersection(_covered[i]);

     if (!mri.is_empty()) {

       jbyte *cur_entry, *next_entry, *limit;

       for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());

            cur_entry <= limit;

            cur_entry  = next_entry) {

         next_entry = cur_entry + 1;

         if (*cur_entry == dirty_card) {

           size_t dirty_cards;

           // Accumulate maximal dirty card range, starting at cur_entry

           for (dirty_cards = 1;

                next_entry <= limit && *next_entry == dirty_card;

                dirty_cards++, next_entry++);

           MemRegion cur_cards(addr_for(cur_entry),

                               dirty_cards*card_size_in_words);

           cl->do_MemRegion(cur_cards);

         }

       }

     }

   }

 }

 MemRegion CardTableModRefBS::dirty_card_range_after_reset(MemRegion mr,

                                                           bool reset,

                                                           int reset_val) {

   for (int i = 0; i < _cur_covered_regions; i++) {

     MemRegion mri = mr.intersection(_covered[i]);

     if (!mri.is_empty()) {

       jbyte* cur_entry, *next_entry, *limit;

       for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());

            cur_entry <= limit;

            cur_entry  = next_entry) {

         next_entry = cur_entry + 1;

         if (*cur_entry == dirty_card) {

           size_t dirty_cards;

           // Accumulate maximal dirty card range, starting at cur_entry

           for (dirty_cards = 1;

                next_entry <= limit && *next_entry == dirty_card;

                dirty_cards++, next_entry++);

           MemRegion cur_cards(addr_for(cur_entry),

                               dirty_cards*card_size_in_words);

           if (reset) {

             for (size_t i = 0; i < dirty_cards; i++) {

               cur_entry[i] = reset_val;

             }

           }

           return cur_cards;

         }

       }

     }

   }

   return MemRegion(mr.end(), mr.end());

 }

 uintx CardTableModRefBS::ct_max_alignment_constraint() {

   return card_size * os::vm_page_size();

 }

 void CardTableModRefBS::verify_guard() {

   // For product build verification

   guarantee(_byte_map[_guard_index] == last_card,

             "card table guard has been modified");

 }

 void CardTableModRefBS::verify() {

   verify_guard();

 }

 #ifndef PRODUCT

 void CardTableModRefBS::verify_region(MemRegion mr,

                                       jbyte val, bool val_equals) {

   jbyte* start    = byte_for(mr.start());

   jbyte* end      = byte_for(mr.last());

   bool   failures = false;

   for (jbyte* curr = start; curr <= end; ++curr) {

     jbyte curr_val = *curr;

     bool failed = (val_equals) ? (curr_val != val) : (curr_val == val);

     if (failed) {

       if (!failures) {

         tty->cr();

         tty->print_cr("== CT verification failed: [" INTPTR_FORMAT "," INTPTR_FORMAT "]", p2i(start), p2i(end));

         tty->print_cr("==   %sexpecting value: %d",

                       (val_equals) ? "" : "not ", val);

         failures = true;

       }

       tty->print_cr("==   card "PTR_FORMAT" ["PTR_FORMAT","PTR_FORMAT"], "

                     "val: %d", p2i(curr), p2i(addr_for(curr)),

                     p2i((HeapWord*) (((size_t) addr_for(curr)) + card_size)),

                     (int) curr_val);

     }

   }

   guarantee(!failures, "there should not have been any failures");

 }

 void CardTableModRefBS::verify_not_dirty_region(MemRegion mr) {

   verify_region(mr, dirty_card, false /* val_equals */);

 }

 void CardTableModRefBS::verify_dirty_region(MemRegion mr) {

   verify_region(mr, dirty_card, true /* val_equals */);

 }

 #endif

 void CardTableModRefBS::print_on(outputStream* st) const {

   st->print_cr("Card table byte_map: [" INTPTR_FORMAT "," INTPTR_FORMAT "] byte_map_base: " INTPTR_FORMAT,

                p2i(_byte_map), p2i(_byte_map + _byte_map_size), p2i(byte_map_base));

 }

 bool CardTableModRefBSForCTRS::card_will_be_scanned(jbyte cv) {

   return

     CardTableModRefBS::card_will_be_scanned(cv) ||

     _rs->is_prev_nonclean_card_val(cv);

 };

 bool CardTableModRefBSForCTRS::card_may_have_been_dirty(jbyte cv) {

   return

     cv != clean_card &&

     (CardTableModRefBS::card_may_have_been_dirty(cv) ||

      CardTableRS::youngergen_may_have_been_dirty(cv));

 };