1 /*

     2  * Copyright (c) 2017, 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_ACCESSBARRIERSUPPORT_HPP

    26 #define SHARE_VM_GC_SHARED_ACCESSBARRIERSUPPORT_HPP

    27 

    28 #include "memory/allocation.hpp"

    29 #include "oops/access.hpp"

    30 

    31 class AccessBarrierSupport: AllStatic {

    32 private:

    33   static DecoratorSet resolve_unknown_oop_ref_strength(DecoratorSet decorators, oop base, ptrdiff_t offset);

    34 

    35 public:

    36   // Some collectors, like G1, needs to keep referents alive when loading them.

    37   // Therefore, for APIs that accept unknown oop ref strength (e.g. unsafe),

    38   // we need to dynamically find out if a given field is on a java.lang.ref.Reference object.

    39   // and in that case what strength it has.

    40   template<DecoratorSet decorators>

    41   static DecoratorSet resolve_possibly_unknown_oop_ref_strength(oop base, ptrdiff_t offset);

    42 };

    43 

    44 #endif // SHARE_VM_GC_SHARED_ACCESSBARRIERSUPPORT_HPP