1 /*

     2  * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_GC_SHARED_BARRIERSET_INLINE_HPP

    26 #define SHARE_VM_GC_SHARED_BARRIERSET_INLINE_HPP

    27 

    28 #include "gc/shared/barrierSet.hpp"

    29 #include "utilities/align.hpp"

    30 

    31 // count is number of array elements being written

    32 void BarrierSet::write_ref_array(HeapWord* start, size_t count) {

    33   assert(count <= (size_t)max_intx, "count too large");

    34   HeapWord* end = (HeapWord*)((char*)start + (count*heapOopSize));

    35   // In the case of compressed oops, start and end may potentially be misaligned;

    36   // so we need to conservatively align the first downward (this is not

    37   // strictly necessary for current uses, but a case of good hygiene and,

    38   // if you will, aesthetics) and the second upward (this is essential for

    39   // current uses) to a HeapWord boundary, so we mark all cards overlapping

    40   // this write. If this evolves in the future to calling a

    41   // logging barrier of narrow oop granularity, like the pre-barrier for G1

    42   // (mentioned here merely by way of example), we will need to change this

    43   // interface, so it is "exactly precise" (if i may be allowed the adverbial

    44   // redundancy for emphasis) and does not include narrow oop slots not

    45   // included in the original write interval.

    46   HeapWord* aligned_start = align_down(start, HeapWordSize);

    47   HeapWord* aligned_end   = align_up  (end,   HeapWordSize);

    48   // If compressed oops were not being used, these should already be aligned

    49   assert(UseCompressedOops || (aligned_start == start && aligned_end == end),

    50          "Expected heap word alignment of start and end");

    51   write_ref_array_work(MemRegion(aligned_start, aligned_end));

    52 }

    53 

    54 #endif // SHARE_VM_GC_SHARED_BARRIERSET_INLINE_HPP