1 /*
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 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
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 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).
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24 
25 #ifndef SHARE_RUNTIME_BASICLOCK_HPP
26 #define SHARE_RUNTIME_BASICLOCK_HPP
27 
28 #include "oops/markWord.hpp"
29 #include "runtime/atomic.hpp"
30 #include "runtime/handles.hpp"
31 
32 class BasicLock {
33   friend class VMStructs;
34   friend class JVMCIVMStructs;
35  private:
36   volatile markWord _displaced_header;
37  public:
38   markWord displaced_header() const {
39     return Atomic::load(&_displaced_header);
40   }
41 
42   void set_displaced_header(markWord header) {
43     Atomic::store(&_displaced_header, header);
44   }
45 
46   void print_on(outputStream* st, oop owner) const;
47 
48   // move a basic lock (used during deoptimization
49   void move_to(oop obj, BasicLock* dest);
50 
51   static int displaced_header_offset_in_bytes()       { return offset_of(BasicLock, _displaced_header); }
52 };
53 
54 // A BasicObjectLock associates a specific Java object with a BasicLock.
55 // It is currently embedded in an interpreter frame.
56 
57 // Because some machines have alignment restrictions on the control stack,
58 // the actual space allocated by the interpreter may include padding words
59 // after the end of the BasicObjectLock.  Also, in order to guarantee
60 // alignment of the embedded BasicLock objects on such machines, we
61 // put the embedded BasicLock at the beginning of the struct.
62 
63 class BasicObjectLock {
64   friend class VMStructs;
65  private:
66   BasicLock _lock;                                    // the lock, must be double word aligned
67   oop       _obj;                                     // object holds the lock;
68 
69  public:
70   // Manipulation
71   oop      obj() const                                { return _obj;  }
72   void set_obj(oop obj)                               { _obj = obj; }
73   BasicLock* lock()                                   { return &_lock; }
74 
75   // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks
76   //       in interpreter activation frames since it includes machine-specific padding.
77   static int size()                                   { return sizeof(BasicObjectLock)/wordSize; }
78 
79   // GC support
80   void oops_do(OopClosure* f) { f->do_oop(&_obj); }
81 
82   static int obj_offset_in_bytes()                    { return offset_of(BasicObjectLock, _obj);  }
83   static int lock_offset_in_bytes()                   { return offset_of(BasicObjectLock, _lock); }
84 };
85 
86 
87 #endif // SHARE_RUNTIME_BASICLOCK_HPP