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 }