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_SHARED_CARDTABLEMODREFBS_HPP
  26 #define SHARE_VM_GC_SHARED_CARDTABLEMODREFBS_HPP
  27 
  28 #include "gc/shared/modRefBarrierSet.hpp"
  29 #include "oops/oop.hpp"

  30 
  31 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
  32 // enumerate ref fields that have been modified (since the last
  33 // enumeration.)
  34 
  35 // As it currently stands, this barrier is *imprecise*: when a ref field in
  36 // an object "o" is modified, the card table entry for the card containing
  37 // the head of "o" is dirtied, not necessarily the card containing the
  38 // modified field itself.  For object arrays, however, the barrier *is*
  39 // precise; only the card containing the modified element is dirtied.
  40 // Closures used to scan dirty cards should take these
  41 // considerations into account.
  42 
  43 class CardTableModRefBS: public ModRefBarrierSet {
  44   // Some classes get to look at some private stuff.
  45   friend class VMStructs;
  46  protected:
  47 
  48   enum CardValues {
  49     clean_card                  = -1,

  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_SHARED_CARDTABLEMODREFBS_HPP
  26 #define SHARE_VM_GC_SHARED_CARDTABLEMODREFBS_HPP
  27 
  28 #include "gc/shared/modRefBarrierSet.hpp"
  29 #include "oops/oop.hpp"
  30 #include "utilities/align.hpp"
  31 
  32 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
  33 // enumerate ref fields that have been modified (since the last
  34 // enumeration.)
  35 
  36 // As it currently stands, this barrier is *imprecise*: when a ref field in
  37 // an object "o" is modified, the card table entry for the card containing
  38 // the head of "o" is dirtied, not necessarily the card containing the
  39 // modified field itself.  For object arrays, however, the barrier *is*
  40 // precise; only the card containing the modified element is dirtied.
  41 // Closures used to scan dirty cards should take these
  42 // considerations into account.
  43 
  44 class CardTableModRefBS: public ModRefBarrierSet {
  45   // Some classes get to look at some private stuff.
  46   friend class VMStructs;
  47  protected:
  48 
  49   enum CardValues {
  50     clean_card                  = -1,