src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp

rev 5732 : [mq]: comments2

*** 211,221 ****
    // a non-array object?
    if (first_block < chunk_mr.start()        // first block straddles left bdry
        && sp->block_is_obj(first_block)      // first block is an object
        && !(oop(first_block)->is_objArray()  // first block is not an array (arrays are precisely dirtied)
             || oop(first_block)->is_typeArray())) {
!     // Find our least non-clean card, so that a left neighbour
      // does not scan an object straddling the mutual boundary
      // too far to the right, and attempt to scan a portion of
      // that object twice.
      jbyte* first_dirty_card = NULL;
      jbyte* last_card_of_first_obj =
--- 211,221 ----
    // a non-array object?
    if (first_block < chunk_mr.start()        // first block straddles left bdry
        && sp->block_is_obj(first_block)      // first block is an object
        && !(oop(first_block)->is_objArray()  // first block is not an array (arrays are precisely dirtied)
             || oop(first_block)->is_typeArray())) {
!     // Find our least non-clean card, so that a left neighbor
      // does not scan an object straddling the mutual boundary
      // too far to the right, and attempt to scan a portion of
      // that object twice.
      jbyte* first_dirty_card = NULL;
      jbyte* last_card_of_first_obj =
*** 245,262 ****
               "Write exactly once : value should be stable hereafter for this round");
        lowest_non_clean[cur_chunk_index] = first_dirty_card;
      } NOISY(else {
        tty->print_cr(" LNC: Found no dirty card in current chunk; leaving LNC entry NULL");
        // In the future, we could have this thread look for a non-NULL value to copy from its
!       // right neighbour (up to the end of the first object).
        if (last_card_of_cur_chunk < last_card_of_first_obj) {
          tty->print_cr(" LNC: BEWARE!!! first obj straddles past right end of chunk:\n"
                        "   might be efficient to get value from right neighbour?");
        }
      })
    } else {
!     // In this case we can help our neighbour by just asking them
      // to stop at our first card (even though it may not be dirty).
      NOISY(tty->print_cr(" LNC: first block is not a non-array object; setting LNC to first card of current chunk");)
      assert(lowest_non_clean[cur_chunk_index] == NULL, "Write once : value should be stable hereafter");
      jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
      lowest_non_clean[cur_chunk_index] = first_card_of_cur_chunk;
--- 245,262 ----
               "Write exactly once : value should be stable hereafter for this round");
        lowest_non_clean[cur_chunk_index] = first_dirty_card;
      } NOISY(else {
        tty->print_cr(" LNC: Found no dirty card in current chunk; leaving LNC entry NULL");
        // In the future, we could have this thread look for a non-NULL value to copy from its
!       // right neighbor (up to the end of the first object).
        if (last_card_of_cur_chunk < last_card_of_first_obj) {
          tty->print_cr(" LNC: BEWARE!!! first obj straddles past right end of chunk:\n"
                        "   might be efficient to get value from right neighbour?");
        }
      })
    } else {
!     // In this case we can help our neighbor by just asking them
      // to stop at our first card (even though it may not be dirty).
      NOISY(tty->print_cr(" LNC: first block is not a non-array object; setting LNC to first card of current chunk");)
      assert(lowest_non_clean[cur_chunk_index] == NULL, "Write once : value should be stable hereafter");
      jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());
      lowest_non_clean[cur_chunk_index] = first_card_of_cur_chunk;