1 /*
   2  * Copyright (c) 2001, 2010, 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 class MutableSpace;
  26 class ObjectStartArray;
  27 class PSPromotionManager;
  28 class GCTaskQueue;
  29 
  30 class CardTableExtension : public CardTableModRefBS {
  31  private:
  32   // Support methods for resizing the card table.
  33   // resize_commit_uncommit() returns true if the pages were committed or
  34   // uncommitted
  35   bool resize_commit_uncommit(int changed_region, MemRegion new_region);
  36   void resize_update_card_table_entries(int changed_region,
  37                                         MemRegion new_region);
  38   void resize_update_committed_table(int changed_region, MemRegion new_region);
  39   void resize_update_covered_table(int changed_region, MemRegion new_region);
  40 
  41  protected:
  42 
  43   static void verify_all_young_refs_precise_helper(MemRegion mr);
  44 
  45  public:
  46   enum ExtendedCardValue {
  47     youngergen_card   = CardTableModRefBS::CT_MR_BS_last_reserved + 1,
  48     verify_card       = CardTableModRefBS::CT_MR_BS_last_reserved + 5
  49   };
  50 
  51   CardTableExtension(MemRegion whole_heap, int max_covered_regions) :
  52     CardTableModRefBS(whole_heap, max_covered_regions) { }
  53 
  54   // Too risky for the 4/10/02 putback
  55   // BarrierSet::Name kind() { return BarrierSet::CardTableExtension; }
  56 
  57   // Scavenge support
  58   void scavenge_contents(ObjectStartArray* start_array,
  59                          MutableSpace* sp,
  60                          HeapWord* space_top,
  61                          PSPromotionManager* pm);
  62 
  63   void scavenge_contents_parallel(ObjectStartArray* start_array,
  64                                   MutableSpace* sp,
  65                                   HeapWord* space_top,
  66                                   PSPromotionManager* pm,
  67                                   uint stripe_number);
  68 
  69   // Verification
  70   static void verify_all_young_refs_imprecise();
  71   static void verify_all_young_refs_precise();
  72 
  73   bool addr_is_marked_imprecise(void *addr);
  74   bool addr_is_marked_precise(void *addr);
  75 
  76   void set_card_newgen(void* addr)   { jbyte* p = byte_for(addr); *p = verify_card; }
  77 
  78   // Testers for entries
  79   static bool card_is_dirty(int value)      { return value == dirty_card; }
  80   static bool card_is_newgen(int value)     { return value == youngergen_card; }
  81   static bool card_is_clean(int value)      { return value == clean_card; }
  82   static bool card_is_verify(int value)     { return value == verify_card; }
  83 
  84   // Card marking
  85   void inline_write_ref_field_gc(void* field, oop new_val) {
  86     jbyte* byte = byte_for(field);
  87     *byte = youngergen_card;
  88   }
  89 
  90   // Adaptive size policy support
  91   // Allows adjustment of the base and size of the covered regions
  92   void resize_covered_region(MemRegion new_region);
  93   // Finds the covered region to resize based on the start address
  94   // of the covered regions.
  95   void resize_covered_region_by_start(MemRegion new_region);
  96   // Finds the covered region to resize based on the end address
  97   // of the covered regions.
  98   void resize_covered_region_by_end(int changed_region, MemRegion new_region);
  99   // Finds the lowest start address of a covered region that is
 100   // previous (i.e., lower index) to the covered region with index "ind".
 101   HeapWord* lowest_prev_committed_start(int ind) const;
 102 
 103 #ifdef ASSERT
 104 
 105   bool is_valid_card_address(jbyte* addr) {
 106     return (addr >= _byte_map) && (addr < _byte_map + _byte_map_size);
 107   }
 108 
 109 #endif // ASSERT
 110 };