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24 
25 #ifndef SHARE_VM_RUNTIME_BASICLOCK_HPP
26 #define SHARE_VM_RUNTIME_BASICLOCK_HPP
27 
28 #include "oops/markOop.hpp"
29 #include "runtime/handles.hpp"
30 
31 class BasicLock {
32   friend class VMStructs;
33   friend class JVMCIVMStructs;
34  private:
35   volatile markOop _displaced_header;
36  public:
displaced_header() const37   markOop      displaced_header() const               { return _displaced_header; }
set_displaced_header(markOop header)38   void         set_displaced_header(markOop header)   { _displaced_header = header; }
39 
40   void print_on(outputStream* st) const;
41 
42   // move a basic lock (used during deoptimization
43   void move_to(oop obj, BasicLock* dest);
44 
displaced_header_offset_in_bytes()45   static int displaced_header_offset_in_bytes()       { return offset_of(BasicLock, _displaced_header); }
46 };
47 
48 // A BasicObjectLock associates a specific Java object with a BasicLock.
49 // It is currently embedded in an interpreter frame.
50 
51 // Because some machines have alignment restrictions on the control stack,
52 // the actual space allocated by the interpreter may include padding words
53 // after the end of the BasicObjectLock.  Also, in order to guarantee
54 // alignment of the embedded BasicLock objects on such machines, we
55 // put the embedded BasicLock at the beginning of the struct.
56 
57 class BasicObjectLock {
58   friend class VMStructs;
59  private:
60   BasicLock _lock;                                    // the lock, must be double word aligned
61   oop       _obj;                                     // object holds the lock;
62 
63  public:
64   // Manipulation
obj() const65   oop      obj() const                                { return _obj;  }
set_obj(oop obj)66   void set_obj(oop obj)                               { _obj = obj; }
lock()67   BasicLock* lock()                                   { return &_lock; }
68 
69   // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks
70   //       in interpreter activation frames since it includes machine-specific padding.
size()71   static int size()                                   { return sizeof(BasicObjectLock)/wordSize; }
72 
73   // GC support
oops_do(OopClosure * f)74   void oops_do(OopClosure* f) { f->do_oop(&_obj); }
75 
obj_offset_in_bytes()76   static int obj_offset_in_bytes()                    { return offset_of(BasicObjectLock, _obj);  }
lock_offset_in_bytes()77   static int lock_offset_in_bytes()                   { return offset_of(BasicObjectLock, _lock); }
78 };
79 
80 
81 #endif // SHARE_VM_RUNTIME_BASICLOCK_HPP
82