src/share/vm/memory/barrierSet.cpp

*** 40,48 ****
--- 40,75 ----
      Universe::heap()->barrier_set()->write_ref_array_pre(      (oop*)start, (int)count, false);
    }
  }
  
  // count is number of array elements being written
+ void BarrierSet::write_ref_array(HeapWord* start, size_t count) {
+   assert(count <= (size_t)max_intx, "count too large");
+   HeapWord* end = (HeapWord*)((char*)start + (count*heapOopSize));
+   // In the case of compressed oops, start and end may potentially be misaligned;
+   // so we need to conservatively align the first downward (this is not
+   // strictly necessary for current uses, but a case of good hygiene and,
+   // if you will, aesthetics) and the second upward (this is essential for
+   // current uses) to a HeapWord boundary, so we mark all cards overlapping
+   // this write. If this evolves in the future to calling a
+   // logging barrier of narrow oop granularity, like the pre-barrier for G1
+   // (mentioned here merely by way of example), we will need to change this
+   // interface, so it is "exactly precise" (if i may be allowed the adverbial
+   // redundancy for emphasis) and does not include narrow oop slots not
+   // included in the original write interval.
+   HeapWord* aligned_start = (HeapWord*)align_size_down((uintptr_t)start, HeapWordSize);
+   HeapWord* aligned_end   = (HeapWord*)align_size_up  ((uintptr_t)end,   HeapWordSize);
+   // If compressed oops were not being used, these should already be aligned
+   assert(UseCompressedOops || (aligned_start == start && aligned_end == end),
+          "Expected heap word alignment of start and end");
+ #if 0
+   warning("Post:\t" INTPTR_FORMAT "[" SIZE_FORMAT "] : [" INTPTR_FORMAT "," INTPTR_FORMAT ")\t",
+                    start,            count,              aligned_start,   aligned_end);
+ #endif
+   write_ref_array_work(MemRegion(aligned_start, aligned_end));
+ }
+ 
+ // count is number of array elements being written
  void BarrierSet::static_write_ref_array_post(HeapWord* start, size_t count) {
    // simply delegate to instance method
    Universe::heap()->barrier_set()->write_ref_array(start, count);
  }