/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifdef CHECK_UNHANDLED_OOPS

// Detect unhanded oops in VM code

// The design is that when an oop is declared on the stack as a local

// variable, the oop is actually a C++ struct with constructor and

// destructor.  The constructor adds the oop address on a list

// off each thread and the destructor removes the oop.  At a potential

// safepoint, the stack addresses of the local variable oops are trashed

// with a recognizable value.  If the local variable is used again, it

// will segfault, indicating an unsafe use of that oop.

// eg:

//    oop o;    //register &o on list

//    funct();  // if potential safepoint - causes clear_naked_oops()

//              // which trashes o above.

//    o->do_something();  // Crashes because o is unsafe.

//

// This code implements the details of the unhandled oop list on the thread.

//

class oop;

class Thread;

class UnhandledOopEntry : public CHeapObj<mtThread> {

 friend class UnhandledOops;

 private:

  oop* _oop_ptr;

  bool _ok_for_gc;

  address _pc;

 public:

  oop* oop_ptr() { return _oop_ptr; }

  UnhandledOopEntry() : _oop_ptr(NULL), _ok_for_gc(false), _pc(NULL) {}

  UnhandledOopEntry(oop* op, address pc) :

                        _oop_ptr(op),   _ok_for_gc(false), _pc(pc) {}

};

class UnhandledOops : public CHeapObj<mtThread> {

 friend class Thread;

 private:

  Thread* _thread;

  int _level;

  GrowableArray<UnhandledOopEntry> *_oop_list;

  void allow_unhandled_oop(oop* op);

  void clear_unhandled_oops();

  UnhandledOops(Thread* thread);

  ~UnhandledOops();

 public:

  static void dump_oops(UnhandledOops* list);

  void register_unhandled_oop(oop* op, address pc);

  void unregister_unhandled_oop(oop* op);

};

#ifdef _LP64

const intptr_t BAD_OOP_ADDR =  0xfffffffffffffff1;

#else

const intptr_t BAD_OOP_ADDR =  0xfffffff1;

#endif // _LP64

#endif // CHECK_UNHANDLED_OOPS