diff -r 1fca55136d66 -r 1068dcb8d315 hotspot/src/share/vm/gc/g1/g1BlockOffsetTable.inline.hpp
--- a/hotspot/src/share/vm/gc/g1/g1BlockOffsetTable.inline.hpp	Thu Jan 07 14:55:12 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/g1BlockOffsetTable.inline.hpp	Thu Jan 07 16:25:53 2016 +0100
@@ -30,34 +30,36 @@
 #include "gc/shared/memset_with_concurrent_readers.hpp"
 #include "gc/shared/space.hpp"
 
-inline HeapWord* G1BlockOffsetTable::block_start(const void* addr) {
-  if (addr >= _bottom && addr < _end) {
-    return block_start_unsafe(addr);
+inline HeapWord* G1BlockOffsetTablePart::block_start(const void* addr) {
+  if (addr >= _space->bottom() && addr < _space->end()) {
+    HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
+    return forward_to_block_containing_addr(q, addr);
   } else {
     return NULL;
   }
 }
 
-inline HeapWord*
-G1BlockOffsetTable::block_start_const(const void* addr) const {
-  if (addr >= _bottom && addr < _end) {
-    return block_start_unsafe_const(addr);
+inline HeapWord* G1BlockOffsetTablePart::block_start_const(const void* addr) const {
+  if (addr >= _space->bottom() && addr < _space->end()) {
+    HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
+    HeapWord* n = q + block_size(q);
+    return forward_to_block_containing_addr_const(q, n, addr);
   } else {
     return NULL;
   }
 }
 
-u_char G1BlockOffsetSharedArray::offset_array(size_t index) const {
+u_char G1BlockOffsetTable::offset_array(size_t index) const {
   check_index(index, "index out of range");
   return _offset_array[index];
 }
 
-void G1BlockOffsetSharedArray::set_offset_array(size_t index, u_char offset) {
+void G1BlockOffsetTable::set_offset_array(size_t index, u_char offset) {
   check_index(index, "index out of range");
   set_offset_array_raw(index, offset);
 }
 
-void G1BlockOffsetSharedArray::set_offset_array(size_t index, HeapWord* high, HeapWord* low) {
+void G1BlockOffsetTable::set_offset_array(size_t index, HeapWord* high, HeapWord* low) {
   check_index(index, "index out of range");
   assert(high >= low, "addresses out of order");
   size_t offset = pointer_delta(high, low);
@@ -65,7 +67,7 @@
   set_offset_array(index, (u_char)offset);
 }
 
-void G1BlockOffsetSharedArray::set_offset_array(size_t left, size_t right, u_char offset) {
+void G1BlockOffsetTable::set_offset_array(size_t left, size_t right, u_char offset) {
   check_index(right, "right index out of range");
   assert(left <= right, "indexes out of order");
   size_t num_cards = right - left + 1;
@@ -73,11 +75,11 @@
 }
 
 // Variant of index_for that does not check the index for validity.
-inline size_t G1BlockOffsetSharedArray::index_for_raw(const void* p) const {
+inline size_t G1BlockOffsetTable::index_for_raw(const void* p) const {
   return pointer_delta((char*)p, _reserved.start(), sizeof(char)) >> LogN;
 }
 
-inline size_t G1BlockOffsetSharedArray::index_for(const void* p) const {
+inline size_t G1BlockOffsetTable::index_for(const void* p) const {
   char* pc = (char*)p;
   assert(pc >= (char*)_reserved.start() &&
          pc <  (char*)_reserved.end(),
@@ -88,8 +90,7 @@
   return result;
 }
 
-inline HeapWord*
-G1BlockOffsetSharedArray::address_for_index(size_t index) const {
+inline HeapWord* G1BlockOffsetTable::address_for_index(size_t index) const {
   check_index(index, "index out of range");
   HeapWord* result = address_for_index_raw(index);
   assert(result >= _reserved.start() && result < _reserved.end(),
@@ -99,47 +100,45 @@
   return result;
 }
 
-inline size_t
-G1BlockOffsetArray::block_size(const HeapWord* p) const {
-  return gsp()->block_size(p);
+inline size_t G1BlockOffsetTablePart::block_size(const HeapWord* p) const {
+  return _space->block_size(p);
 }
 
-inline HeapWord*
-G1BlockOffsetArray::block_at_or_preceding(const void* addr,
-                                          bool has_max_index,
-                                          size_t max_index) const {
-  assert(_array->offset_array(0) == 0, "objects can't cross covered areas");
-  size_t index = _array->index_for(addr);
+inline HeapWord* G1BlockOffsetTablePart::block_at_or_preceding(const void* addr,
+                                                               bool has_max_index,
+                                                               size_t max_index) const {
+  assert(_bot->offset_array(0) == 0, "objects can't cross covered areas");
+  size_t index = _bot->index_for(addr);
   // We must make sure that the offset table entry we use is valid.  If
   // "addr" is past the end, start at the last known one and go forward.
   if (has_max_index) {
     index = MIN2(index, max_index);
   }
-  HeapWord* q = _array->address_for_index(index);
+  HeapWord* q = _bot->address_for_index(index);
 
-  uint offset = _array->offset_array(index);  // Extend u_char to uint.
+  uint offset = _bot->offset_array(index);  // Extend u_char to uint.
   while (offset >= N_words) {
     // The excess of the offset from N_words indicates a power of Base
     // to go back by.
     size_t n_cards_back = BlockOffsetArray::entry_to_cards_back(offset);
     q -= (N_words * n_cards_back);
     index -= n_cards_back;
-    offset = _array->offset_array(index);
+    offset = _bot->offset_array(index);
   }
   assert(offset < N_words, "offset too large");
   q -= offset;
   return q;
 }
 
-inline HeapWord*
-G1BlockOffsetArray::
-forward_to_block_containing_addr_const(HeapWord* q, HeapWord* n,
-                                       const void* addr) const {
-  if (addr >= gsp()->top()) return gsp()->top();
+inline HeapWord* G1BlockOffsetTablePart::forward_to_block_containing_addr_const(HeapWord* q, HeapWord* n,
+                                                                                const void* addr) const {
+  if (addr >= _space->top()) return _space->top();
   while (n <= addr) {
     q = n;
     oop obj = oop(q);
-    if (obj->klass_or_null() == NULL) return q;
+    if (obj->klass_or_null() == NULL) {
+      return q;
+    }
     n += block_size(q);
   }
   assert(q <= n, "wrong order for q and addr");
@@ -147,10 +146,11 @@
   return q;
 }
 
-inline HeapWord*
-G1BlockOffsetArray::forward_to_block_containing_addr(HeapWord* q,
-                                                     const void* addr) {
-  if (oop(q)->klass_or_null() == NULL) return q;
+inline HeapWord* G1BlockOffsetTablePart::forward_to_block_containing_addr(HeapWord* q,
+                                                                          const void* addr) {
+  if (oop(q)->klass_or_null() == NULL) {
+    return q;
+  }
   HeapWord* n = q + block_size(q);
   // In the normal case, where the query "addr" is a card boundary, and the
   // offset table chunks are the same size as cards, the block starting at