--- old/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp	2014-08-14 13:40:40.731069379 +0200
+++ new/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp	2014-08-14 13:40:40.653067087 +0200
@@ -32,64 +32,37 @@
 
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 
+void G1BlockOffsetSharedArrayMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
+  // Nothing to do. The BOT is hard-wired to be part of the HeapRegion, and we cannot
+  // retrieve it here since this would cause firing of several asserts. The code
+  // executed after commit of a region already needs to do some re-initialization of
+  // the HeapRegion, so we combine that.
+}
+
 //////////////////////////////////////////////////////////////////////
 // G1BlockOffsetSharedArray
 //////////////////////////////////////////////////////////////////////
 
-G1BlockOffsetSharedArray::G1BlockOffsetSharedArray(MemRegion reserved,
-                                                   size_t init_word_size) :
-  _reserved(reserved), _end(NULL)
-{
-  size_t size = compute_size(reserved.word_size());
-  ReservedSpace rs(ReservedSpace::allocation_align_size_up(size));
-  if (!rs.is_reserved()) {
-    vm_exit_during_initialization("Could not reserve enough space for heap offset array");
-  }
-  if (!_vs.initialize(rs, 0)) {
-    vm_exit_during_initialization("Could not reserve enough space for heap offset array");
-  }
+G1BlockOffsetSharedArray::G1BlockOffsetSharedArray(MemRegion heap, G1RegionToSpaceMapper* storage) :
+  _reserved(), _end(NULL), _listener(), _offset_array(NULL) {
+
+  _reserved = heap;
+  _end = NULL;
 
-  MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
+  MemRegion bot_reserved = storage->reserved();
 
-  _offset_array = (u_char*)_vs.low_boundary();
-  resize(init_word_size);
+  _offset_array = (u_char*)bot_reserved.start();
+  _end = _reserved.end();
+
+  storage->set_mapping_changed_listener(&_listener);
+  
   if (TraceBlockOffsetTable) {
     gclog_or_tty->print_cr("G1BlockOffsetSharedArray::G1BlockOffsetSharedArray: ");
     gclog_or_tty->print_cr("  "
                   "  rs.base(): " INTPTR_FORMAT
                   "  rs.size(): " INTPTR_FORMAT
                   "  rs end(): " INTPTR_FORMAT,
-                  rs.base(), rs.size(), rs.base() + rs.size());
-    gclog_or_tty->print_cr("  "
-                  "  _vs.low_boundary(): " INTPTR_FORMAT
-                  "  _vs.high_boundary(): " INTPTR_FORMAT,
-                  _vs.low_boundary(),
-                  _vs.high_boundary());
-  }
-}
-
-void G1BlockOffsetSharedArray::resize(size_t new_word_size) {
-  assert(new_word_size <= _reserved.word_size(), "Resize larger than reserved");
-  size_t new_size = compute_size(new_word_size);
-  size_t old_size = _vs.committed_size();
-  size_t delta;
-  char* high = _vs.high();
-  _end = _reserved.start() + new_word_size;
-  if (new_size > old_size) {
-    delta = ReservedSpace::page_align_size_up(new_size - old_size);
-    assert(delta > 0, "just checking");
-    if (!_vs.expand_by(delta)) {
-      // Do better than this for Merlin
-      vm_exit_out_of_memory(delta, OOM_MMAP_ERROR, "offset table expansion");
-    }
-    assert(_vs.high() == high + delta, "invalid expansion");
-    // Initialization of the contents is left to the
-    // G1BlockOffsetArray that uses it.
-  } else {
-    delta = ReservedSpace::page_align_size_down(old_size - new_size);
-    if (delta == 0) return;
-    _vs.shrink_by(delta);
-    assert(_vs.high() == high - delta, "invalid expansion");
+                  bot_reserved.start(), bot_reserved.byte_size(), bot_reserved.end());
   }
 }
 
@@ -100,18 +73,7 @@
 }
 
 void G1BlockOffsetSharedArray::set_offset_array(HeapWord* left, HeapWord* right, u_char offset) {
-  check_index(index_for(right - 1), "right address out of range");
-  assert(left  < right, "Heap addresses out of order");
-  size_t num_cards = pointer_delta(right, left) >> LogN_words;
-  if (UseMemSetInBOT) {
-    memset(&_offset_array[index_for(left)], offset, num_cards);
-  } else {
-    size_t i = index_for(left);
-    const size_t end = i + num_cards;
-    for (; i < end; i++) {
-      _offset_array[i] = offset;
-    }
-  }
+  set_offset_array(index_for(left), index_for(right -1), offset);
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -650,6 +612,25 @@
   _next_offset_index = 0;
 }
 
+HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold_raw() {
+  assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
+         "just checking");
+  _next_offset_index = _array->index_for_raw(_bottom);
+  _next_offset_index++;
+  _next_offset_threshold =
+    _array->address_for_index_raw(_next_offset_index);
+  return _next_offset_threshold;
+}
+
+void G1BlockOffsetArrayContigSpace::zero_bottom_entry_raw() {
+  assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
+         "just checking");
+  size_t bottom_index = _array->index_for_raw(_bottom);
+  assert(_array->address_for_index_raw(bottom_index) == _bottom,
+         "Precondition of call");
+  _array->set_offset_array_raw(bottom_index, 0);
+}
+
 HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold() {
   assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
          "just checking");