8038423: G1: Decommit memory within heap

Allow G1 to decommit memory of arbitrary regions within the heap and their associated auxiliary data structures card table, BOT, hot card cache, and mark bitmaps.

Reviewed-by: mgerdin, brutisso, jwilhelm

hotspot/src/share/vm/gc_implementation/g1/g1CardCounts.hpp

@@ -25,14 +25,26 @@
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP
 
+#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
 #include "memory/allocation.hpp"
 #include "runtime/virtualspace.hpp"
 #include "utilities/globalDefinitions.hpp"
 
 class CardTableModRefBS;
+class G1CardCounts;
 class G1CollectedHeap;
+class G1RegionToSpaceMapper;
 class HeapRegion;
 
+class G1CardCountsMappingChangedListener : public G1MappingChangedListener {
+ private:
+  G1CardCounts* _counts;
+ public:
+  void set_cardcounts(G1CardCounts* counts) { _counts = counts; }
+
+  virtual void on_commit(uint start_idx, size_t num_regions);
+};
+
 // Table to track the number of times a card has been refined. Once
 // a card has been refined a certain number of times, it is
 // considered 'hot' and its refinement is delayed by inserting the
@@ -41,6 +53,8 @@ class HeapRegion;
 // is 'drained' during the next evacuation pause.
 
 class G1CardCounts: public CHeapObj<mtGC> {
+  G1CardCountsMappingChangedListener _listener;
+
   G1CollectedHeap* _g1h;
 
   // The table of counts
@@ -49,27 +63,18 @@ class G1CardCounts: public CHeapObj<mtGC> {
   // Max capacity of the reserved space for the counts table
   size_t _reserved_max_card_num;
 
-  // Max capacity of the committed space for the counts table
-  size_t _committed_max_card_num;
-
-  // Size of committed space for the counts table
-  size_t _committed_size;
-
   // CardTable bottom.
   const jbyte* _ct_bot;
 
   // Barrier set
   CardTableModRefBS* _ct_bs;
 
-  // The virtual memory backing the counts table
-  VirtualSpace _card_counts_storage;
-
   // Returns true if the card counts table has been reserved.
   bool has_reserved_count_table() { return _card_counts != NULL; }
 
   // Returns true if the card counts table has been reserved and committed.
   bool has_count_table() {
-    return has_reserved_count_table() && _committed_max_card_num > 0;
+    return has_reserved_count_table();
   }
 
   size_t ptr_2_card_num(const jbyte* card_ptr) {
@@ -79,37 +84,24 @@ class G1CardCounts: public CHeapObj<mtGC> {
                    "_ct_bot: " PTR_FORMAT,
                    p2i(card_ptr), p2i(_ct_bot)));
     size_t card_num = pointer_delta(card_ptr, _ct_bot, sizeof(jbyte));
-    assert(card_num >= 0 && card_num < _committed_max_card_num,
+    assert(card_num >= 0 && card_num < _reserved_max_card_num,
            err_msg("card pointer out of range: " PTR_FORMAT, p2i(card_ptr)));
     return card_num;
   }
 
   jbyte* card_num_2_ptr(size_t card_num) {
-    assert(card_num >= 0 && card_num < _committed_max_card_num,
+    assert(card_num >= 0 && card_num < _reserved_max_card_num,
            err_msg("card num out of range: "SIZE_FORMAT, card_num));
     return (jbyte*) (_ct_bot + card_num);
   }
 
-  // Helper routine.
-  // Returns the number of cards that can be counted by the given committed
-  // table size, with a maximum of the number of cards spanned by the max
-  // capacity of the heap.
-  size_t committed_to_card_num(size_t committed_size) {
-    return MIN2(_reserved_max_card_num, committed_size / sizeof(jbyte));
-  }
-
   // Clear the counts table for the given (exclusive) index range.
   void clear_range(size_t from_card_num, size_t to_card_num);
 
  public:
   G1CardCounts(G1CollectedHeap* g1h);
-  ~G1CardCounts();
 
-  void initialize();
-
-  // Resize the committed space for the card counts table in
-  // response to a resize of the committed space for the heap.
-  void resize(size_t heap_capacity);
+  void initialize(G1RegionToSpaceMapper* mapper);
 
   // Increments the refinement count for the given card.
   // Returns the pre-increment count value.
@@ -122,8 +114,10 @@ class G1CardCounts: public CHeapObj<mtGC> {
   // Clears the card counts for the cards spanned by the region
   void clear_region(HeapRegion* hr);
 
+  // Clears the card counts for the cards spanned by the MemRegion
+  void clear_range(MemRegion mr);
+
   // Clear the entire card counts table during GC.
-  // Updates the policy stats with the duration.
   void clear_all();
 };