1 /*
   2  * Copyright (c) 1998, 2007, 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 class BasicLock VALUE_OBJ_CLASS_SPEC {
  26   friend class VMStructs;
  27  private:
  28   volatile markOop _displaced_header;
  29  public:
  30   markOop      displaced_header() const               { return _displaced_header; }
  31   void         set_displaced_header(markOop header)   { _displaced_header = header; }
  32 
  33   void print_on(outputStream* st) const;
  34 
  35   // move a basic lock (used during deoptimization
  36   void move_to(oop obj, BasicLock* dest);
  37 
  38   static int displaced_header_offset_in_bytes()       { return offset_of(BasicLock, _displaced_header); }
  39 };
  40 
  41 // A BasicObjectLock associates a specific Java object with a BasicLock.
  42 // It is currently embedded in an interpreter frame.
  43 
  44 // Because some machines have alignment restrictions on the control stack,
  45 // the actual space allocated by the interpreter may include padding words
  46 // after the end of the BasicObjectLock.  Also, in order to guarantee
  47 // alignment of the embedded BasicLock objects on such machines, we
  48 // put the embedded BasicLock at the beginning of the struct.
  49 
  50 class BasicObjectLock VALUE_OBJ_CLASS_SPEC {
  51   friend class VMStructs;
  52  private:
  53   BasicLock _lock;                                    // the lock, must be double word aligned
  54   oop       _obj;                                     // object holds the lock;
  55 
  56  public:
  57   // Manipulation
  58   oop      obj() const                                { return _obj;  }
  59   void set_obj(oop obj)                               { _obj = obj; }
  60   BasicLock* lock()                                   { return &_lock; }
  61 
  62   // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks
  63   //       in interpreter activation frames since it includes machine-specific padding.
  64   static int size()                                   { return sizeof(BasicObjectLock)/wordSize; }
  65 
  66   // GC support
  67   void oops_do(OopClosure* f) { f->do_oop(&_obj); }
  68 
  69   static int obj_offset_in_bytes()                    { return offset_of(BasicObjectLock, _obj);  }
  70   static int lock_offset_in_bytes()                   { return offset_of(BasicObjectLock, _lock); }
  71 };
  72