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