1 /*

     2  * Copyright (c) 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 package sun.jvm.hotspot.gc.z;

    26 

    27 import sun.jvm.hotspot.debugger.Address;

    28 import sun.jvm.hotspot.runtime.VM;

    29 

    30 class ZBarrier {

    31     private static boolean is_weak_good_or_null_fast_path(Address addr) {

    32         return ZAddress.is_weak_good_or_null(addr);

    33     }

    34 

    35     private static Address weak_load_barrier_on_oop_slow_path(Address addr) {

    36         return ZAddress.is_weak_good(addr) ? ZAddress.good(addr) : relocate_or_remap(addr);

    37     }

    38 

    39     private static boolean during_relocate() {

    40         return ZGlobals.ZGlobalPhase() == ZGlobals.ZPhaseRelocate;

    41     }

    42 

    43     private static Address relocate(Address addr) {

    44         ZHeap heap = zheap();

    45         if (heap.is_relocating(addr)) {

    46             // Forward

    47             return heap.relocate_object(addr);

    48         }

    49 

    50         // Remap

    51         return ZAddress.good(addr);

    52     }

    53 

    54     private static ZHeap zheap() {

    55         ZCollectedHeap zCollectedHeap = (ZCollectedHeap)VM.getVM().getUniverse().heap();

    56         return zCollectedHeap.heap();

    57     }

    58 

    59     private static Address remap(Address addr) {

    60         ZHeap heap = zheap();

    61         if (heap.is_relocating(addr)) {

    62             // Forward

    63             return heap.forward_object(addr);

    64         }

    65 

    66         // Remap

    67         return ZAddress.good(addr);

    68     }

    69 

    70     private static Address relocate_or_remap(Address addr) {

    71         return during_relocate() ? relocate(addr) : remap(addr);

    72     }

    73 

    74     static Address weak_barrier(Address o) {

    75         // Fast path

    76         if (is_weak_good_or_null_fast_path(o)) {

    77             // Return the good address instead of the weak good address

    78             // to ensure that the currently active heap view is used.

    79             return ZAddress.good_or_null(o);

    80         }

    81 

    82         // Slow path

    83         return weak_load_barrier_on_oop_slow_path(o);

    84     }

    85 }