--- old/src/share/vm/gc_implementation/g1/g1CodeCacheRemSet.hpp	2014-08-26 17:11:53.625994979 +0200
+++ new/src/share/vm/gc_implementation/g1/g1CodeCacheRemSet.hpp	2014-08-26 17:11:53.505990019 +0200
@@ -26,222 +26,64 @@
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1CODECACHEREMSET_HPP
 
 #include "memory/allocation.hpp"
-#include "memory/freeList.hpp"
-#include "runtime/globals.hpp"
 
 class CodeBlobClosure;
-
-// The elements of the G1CodeRootChunk is either:
-//  1) nmethod pointers
-//  2) nodes in an internally chained free list
-typedef union {
-  nmethod* _nmethod;
-  void*    _link;
-} NmethodOrLink;
-
-class G1CodeRootChunk : public CHeapObj<mtGC> {
- private:
-  static const int NUM_ENTRIES = 32;
- public:
-  G1CodeRootChunk*     _next;
-  G1CodeRootChunk*     _prev;
-
-  NmethodOrLink*          _top;
-  // First free position within the chunk.
-  volatile NmethodOrLink* _free;
-
-  NmethodOrLink _data[NUM_ENTRIES];
-
-  NmethodOrLink* bottom() const {
-    return (NmethodOrLink*) &(_data[0]);
-  }
-
-  NmethodOrLink* end() const {
-    return (NmethodOrLink*) &(_data[NUM_ENTRIES]);
-  }
-
-  bool is_link(NmethodOrLink* nmethod_or_link) {
-    return nmethod_or_link->_link == NULL ||
-        (bottom() <= nmethod_or_link->_link
-        && nmethod_or_link->_link < end());
-  }
-
-  bool is_nmethod(NmethodOrLink* nmethod_or_link) {
-    return !is_link(nmethod_or_link);
-  }
-
- public:
-  G1CodeRootChunk();
-  ~G1CodeRootChunk() {}
-
-  static size_t word_size() { return (size_t)(align_size_up_(sizeof(G1CodeRootChunk), HeapWordSize) / HeapWordSize); }
-
-  // FreeList "interface" methods
-
-  G1CodeRootChunk* next() const         { return _next; }
-  G1CodeRootChunk* prev() const         { return _prev; }
-  void set_next(G1CodeRootChunk* v)     { _next = v; assert(v != this, "Boom");}
-  void set_prev(G1CodeRootChunk* v)     { _prev = v; assert(v != this, "Boom");}
-  void clear_next()       { set_next(NULL); }
-  void clear_prev()       { set_prev(NULL); }
-
-  size_t size() const { return word_size(); }
-
-  void link_next(G1CodeRootChunk* ptr)  { set_next(ptr); }
-  void link_prev(G1CodeRootChunk* ptr)  { set_prev(ptr); }
-  void link_after(G1CodeRootChunk* ptr) {
-    link_next(ptr);
-    if (ptr != NULL) ptr->link_prev((G1CodeRootChunk*)this);
-  }
-
-  bool is_free()                 { return true; }
-
-  // New G1CodeRootChunk routines
-
-  void reset();
-
-  bool is_empty() const {
-    return _top == bottom();
-  }
-
-  bool is_full() const {
-    return _top == end() && _free == NULL;
-  }
-
-  bool contains(nmethod* method) {
-    NmethodOrLink* cur = bottom();
-    while (cur != _top) {
-      if (cur->_nmethod == method) return true;
-      cur++;
-    }
-    return false;
-  }
-
-  bool add(nmethod* method) {
-    if (is_full()) {
-      return false;
-    }
-
-    if (_free != NULL) {
-      // Take from internally chained free list
-      NmethodOrLink* first_free = (NmethodOrLink*)_free;
-      _free = (NmethodOrLink*)_free->_link;
-      first_free->_nmethod = method;
-    } else {
-      // Take from top.
-      _top->_nmethod = method;
-      _top++;
-    }
-
-    return true;
-  }
-
-  bool remove_lock_free(nmethod* method);
-
-  void nmethods_do(CodeBlobClosure* blk);
-
-  nmethod* pop() {
-    if (_free != NULL) {
-      // Kill the free list.
-      _free = NULL;
-    }
-
-    while (!is_empty()) {
-      _top--;
-      if (is_nmethod(_top)) {
-        return _top->_nmethod;
-      }
-    }
-
-    return NULL;
-  }
-};
-
-// Manages free chunks.
-class G1CodeRootChunkManager VALUE_OBJ_CLASS_SPEC {
- private:
-  // Global free chunk list management
-  FreeList<G1CodeRootChunk> _free_list;
-  // Total number of chunks handed out
-  size_t _num_chunks_handed_out;
-
- public:
-  G1CodeRootChunkManager();
-
-  G1CodeRootChunk* new_chunk();
-  void free_chunk(G1CodeRootChunk* chunk);
-  // Free all elements of the given list.
-  void free_all_chunks(FreeList<G1CodeRootChunk>* list);
-
-  void initialize();
-  void purge_chunks(size_t keep_ratio);
-
-  static size_t static_mem_size();
-  size_t fl_mem_size();
-
-#ifndef PRODUCT
-  size_t num_chunks_handed_out() const;
-  size_t num_free_chunks() const;
-#endif
-};
+class CodeRootSetTable;
+class HeapRegion;
+class nmethod;
 
 // Implements storage for a set of code roots.
 // All methods that modify the set are not thread-safe except if otherwise noted.
 class G1CodeRootSet VALUE_OBJ_CLASS_SPEC {
+  friend class G1CodeRootSetTest;
  private:
-  // Global default free chunk manager instance.
-  static G1CodeRootChunkManager _default_chunk_manager;
 
-  G1CodeRootChunk* new_chunk() { return _manager->new_chunk(); }
-  void free_chunk(G1CodeRootChunk* chunk) { _manager->free_chunk(chunk); }
-  // Free all elements of the given list.
-  void free_all_chunks(FreeList<G1CodeRootChunk>* list) { _manager->free_all_chunks(list); }
-
-  // Return the chunk that contains the given nmethod, NULL otherwise.
-  // Scans the list of chunks backwards, as this method is used to add new
-  // entries, which are typically added in bulk for a single nmethod.
-  G1CodeRootChunk* find(nmethod* method);
-  void free(G1CodeRootChunk* chunk);
+  const static size_t SmallSize = 32;
+  const static size_t Threshold = 24;
+  const static size_t LargeSize = 512;
+
+  CodeRootSetTable* _table;
+  CodeRootSetTable* load_acquire_table();
 
   size_t _length;
-  FreeList<G1CodeRootChunk> _list;
-  G1CodeRootChunkManager* _manager;
+
+  void move_to_large();
+  void allocate_small_table();
 
  public:
-  // If an instance is initialized with a chunk manager of NULL, use the global
-  // default one.
-  G1CodeRootSet(G1CodeRootChunkManager* manager = NULL);
+  G1CodeRootSet() : _table(NULL), _length(0) {}
   ~G1CodeRootSet();
 
-  static void purge_chunks(size_t keep_ratio);
+  static void purge();
 
-  static size_t free_chunks_static_mem_size();
-  static size_t free_chunks_mem_size();
+  static size_t static_mem_size();
 
-  // Search for the code blob from the recently allocated ones to find duplicates more quickly, as this
-  // method is likely to be repeatedly called with the same nmethod.
   void add(nmethod* method);
 
-  void remove_lock_free(nmethod* method);
-  nmethod* pop();
+  bool remove(nmethod* method);
 
+  // Safe to call without synchronization, but may return false negatives.
   bool contains(nmethod* method);
 
   void clear();
 
   void nmethods_do(CodeBlobClosure* blk) const;
 
-  bool is_empty() { return length() == 0; }
+  // Remove all nmethods which no longer contain pointers into our "owner" region
+  void rebuild(HeapRegion* owner);
+
+  bool is_empty() {
+    bool empty = length() == 0;
+    assert(empty == (_table == NULL), "is empty only if table is deallocated");
+    return empty;
+  }
 
   // Length in elements
   size_t length() const { return _length; }
 
-  // Static data memory size in bytes of this set.
-  static size_t static_mem_size();
   // Memory size in bytes taken by this set.
   size_t mem_size();
 
-  static void test() PRODUCT_RETURN;
 };
 
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1CODECACHEREMSET_HPP