src/hotspot/share/gc/g1/g1BlockOffsetTable.inline.hpp

rev 56201 : 8225716: G1 GC: Undefined behaviour in G1BlockOffsetTablePart::block_at_or_preceding
Reviewed-by: kbarrett, tschatzl

@@ -27,10 +27,11 @@
 
 #include "gc/g1/g1BlockOffsetTable.hpp"
 #include "gc/g1/heapRegion.hpp"
 #include "gc/shared/memset_with_concurrent_readers.hpp"
 #include "gc/shared/space.hpp"
+#include "runtime/atomic.hpp"
 
 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);

@@ -49,11 +50,15 @@
   }
 }
 
 u_char G1BlockOffsetTable::offset_array(size_t index) const {
   check_index(index, "index out of range");
-  return _offset_array[index];
+  return Atomic::load(&_offset_array[index]);
+}
+
+void G1BlockOffsetTable::set_offset_array_raw(size_t index, u_char offset) {
+  Atomic::store(offset, &_offset_array[index]);
 }
 
 void G1BlockOffsetTable::set_offset_array(size_t index, u_char offset) {
   check_index(index, "index out of range");
   set_offset_array_raw(index, offset);

@@ -69,11 +74,12 @@
 
 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;
-  memset_with_concurrent_readers(&_offset_array[left], offset, num_cards);
+  memset_with_concurrent_readers
+    (const_cast<u_char*> (&_offset_array[left]), offset, num_cards);
 }
 
 // Variant of index_for that does not check the index for validity.
 inline size_t G1BlockOffsetTable::index_for_raw(const void* p) const {
   return pointer_delta((char*)p, _reserved.start(), sizeof(char)) >> BOTConstants::LogN;