1 /*
 2  * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
 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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 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   // This is either the actual displaced header from a locked object, or
38   // a sentinel zero value indicating a recursive stack-lock.
39   volatile markWord _displaced_header;








40  public:
41   markWord displaced_header() const {
42     return Atomic::load(&_displaced_header);
43   }
44 
45   void set_displaced_header(markWord header) {
46     Atomic::store(&_displaced_header, header);
47   }







48 
49   void print_on(outputStream* st, oop owner) const;
50 
51   // move a basic lock (used during deoptimization)
52   void move_to(oop obj, BasicLock* dest);
53 
54   static int displaced_header_offset_in_bytes() { return (int)offset_of(BasicLock, _displaced_header); }
55 };
56 
57 // A BasicObjectLock associates a specific Java object with a BasicLock.
58 // It is currently embedded in an interpreter frame.
59 
60 // Because some machines have alignment restrictions on the control stack,
61 // the actual space allocated by the interpreter may include padding words
62 // after the end of the BasicObjectLock.  Also, in order to guarantee
63 // alignment of the embedded BasicLock objects on such machines, we
64 // put the embedded BasicLock at the beginning of the struct.
65 
66 class BasicObjectLock {
67   friend class VMStructs;
68  private:
69   BasicLock _lock;                                    // the lock, must be double word aligned
70   oop       _obj;                                     // object holds the lock;
71 
72  public:
73   // Manipulation
74   oop      obj() const                                { return _obj;  }
75   void set_obj(oop obj)                               { _obj = obj; }
76   BasicLock* lock()                                   { return &_lock; }
77 
78   // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks
79   //       in interpreter activation frames since it includes machine-specific padding.
80   static int size()                                   { return sizeof(BasicObjectLock)/wordSize; }
81 
82   // GC support
83   void oops_do(OopClosure* f) { f->do_oop(&_obj); }
84 
85   static ByteSize obj_offset()                { return byte_offset_of(BasicObjectLock, _obj);  }
86   static ByteSize lock_offset()               { return byte_offset_of(BasicObjectLock, _lock); }
87 };
88 
89 
90 #endif // SHARE_RUNTIME_BASICLOCK_HPP
--- EOF ---