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 #ifndef SHARE_CODE_NMETHOD_BARRIER_HPP
26 #define SHARE_CODE_NMETHOD_BARRIER_HPP
27 
28 #include "memory/allocation.hpp"
29 
30 
31 class nmethodBarrierState {
32   struct CounterStruct {
33     int _epoch;
34     int _lock;
35   };
36   union CounterUnion {
37     uint64_t _value;
38     CounterStruct _counters;
39   };
40 private:
41   volatile uint64_t _state;
42 public:
43   nmethodBarrierState() : _state(0) {}
44 
45   bool is_safe() const;
46 
47   bool enter();
48   void leave();
49   void wait();
50 };
51 
52 class nmethodBarrier: StackObj {
53 private:
54   bool _is_deoptimized;
55   nmethod* _nm;
56   address* _return_address_ptr;
57 public:
58   nmethodBarrier(nmethod* nm);
59   nmethodBarrier(nmethod* nm, address* return_address_ptr);
60 
61   bool is_deoptimized() const { return _is_deoptimized; }
62   void deoptimize();
63   void disarm();
64 
65   static int enter(address* return_address_ptr);
66   static void initialize(nmethod* nm);
67   static int disarmed_value();
68   static bool is_armed(nmethod* nm);
69   static void disarm_barrier(nmethod* nm);
70 };
71 
72 #endif // SHARE_CODE_NMETHOD_BARRIER_HPP