1 /*
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 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 5  * This code is free software; you can redistribute it and/or modify it
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 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 #include "utilities/sizes.hpp"
32 
33 class BasicLock {
34   friend class VMStructs;
35   friend class JVMCIVMStructs;
36  private:
37   volatile markWord _displaced_header;
38  public:
39   markWord displaced_header() const {
40     return Atomic::load(&_displaced_header);
41   }
42 
43   void set_displaced_header(markWord header) {
44     Atomic::store(&_displaced_header, header);
45   }
46 
47   void print_on(outputStream* st, oop owner) const;
48 
49   // move a basic lock (used during deoptimization
50   void move_to(oop obj, BasicLock* dest);
51 
52   static int displaced_header_offset_in_bytes() { return (int)offset_of(BasicLock, _displaced_header); }
53 };
54 
55 // A BasicObjectLock associates a specific Java object with a BasicLock.
56 // It is currently embedded in an interpreter frame.
57 
58 // Because some machines have alignment restrictions on the control stack,
59 // the actual space allocated by the interpreter may include padding words
60 // after the end of the BasicObjectLock.  Also, in order to guarantee
61 // alignment of the embedded BasicLock objects on such machines, we
62 // put the embedded BasicLock at the beginning of the struct.
63 
64 class BasicObjectLock {
65   friend class VMStructs;
66  private:
67   BasicLock _lock;                                    // the lock, must be double word aligned
68   oop       _obj;                                     // object holds the lock;
69 
70  public:
71   // Manipulation
72   oop      obj() const                                { return _obj;  }
73   oop*     obj_adr()                                  { return &_obj; }
74   void set_obj(oop obj)                               { _obj = obj; }
75   BasicLock* lock()                                   { return &_lock; }
76 
77   // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks
78   //       in interpreter activation frames since it includes machine-specific padding.
79   static int size()                                   { return sizeof(BasicObjectLock)/wordSize; }
80 
81   // GC support
82   void oops_do(OopClosure* f) { f->do_oop(&_obj); }
83 
84   static ByteSize obj_offset()                { return byte_offset_of(BasicObjectLock, _obj);  }
85   static ByteSize lock_offset()               { return byte_offset_of(BasicObjectLock, _lock); }
86 };
87 
88 
89 #endif // SHARE_RUNTIME_BASICLOCK_HPP