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 /*

  * Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved.

  * 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.

  *

  */

 #ifndef SHARE_VM_ADLC_ARENA_HPP

 #define SHARE_VM_ADLC_ARENA_HPP

 // All classes in the virtual machine must be subclassed

 // by one of the following allocation classes:

 //

 //

 // For objects allocated in the C-heap (managed by: free & malloc).

 // - CHeapObj

 //

 //

 // For embedded objects.

 // - ValueObj

 //

 // For classes used as name spaces.

 // - AllStatic

 //

 class CHeapObj {

  public:

   void* operator new(size_t size);

   void  operator delete(void* p);

   void* new_array(size_t size);

 };

 // Base class for objects used as value objects.

 // Calling new or delete will result in fatal error.

 class ValueObj {

  public:

   void* operator new(size_t size);

   void operator delete(void* p);

 };

 // Base class for classes that constitute name spaces.

 class AllStatic {

  public:

   void* operator new(size_t size);

   void operator delete(void* p);

 };

 //------------------------------Chunk------------------------------------------

 // Linked list of raw memory chunks

 class Chunk: public CHeapObj {

  public:

   void* operator new(size_t size, size_t length);

   void  operator delete(void* p, size_t length);

   Chunk(size_t length);

   enum {

       init_size =  1*1024,      // Size of first chunk

       size      = 32*1024       // Default size of an Arena chunk (following the first)

   };

   Chunk*       _next;           // Next Chunk in list

   size_t       _len;            // Size of this Chunk

   void chop();                  // Chop this chunk

   void next_chop();             // Chop next chunk

   // Boundaries of data area (possibly unused)

   char* bottom() const { return ((char*) this) + sizeof(Chunk);  }

   char* top()    const { return bottom() + _len; }

 };

 //------------------------------Arena------------------------------------------

 // Fast allocation of memory

 class Arena: public CHeapObj {

 protected:

   friend class ResourceMark;

   friend class HandleMark;

   friend class NoHandleMark;

   Chunk *_first;                // First chunk

   Chunk *_chunk;                // current chunk

   char *_hwm, *_max;            // High water mark and max in current chunk

   void* grow(size_t x);         // Get a new Chunk of at least size x

   size_t _size_in_bytes;          // Size of arena (used for memory usage tracing)

 public:

   Arena();

   Arena(size_t init_size);

   Arena(Arena *old);

   ~Arena()                      { _first->chop(); }

   char* hwm() const             { return _hwm; }

   // Fast allocate in the arena.  Common case is: pointer test + increment.

   void* Amalloc(size_t x) {

 #ifdef _LP64

     x = (x + (8-1)) & ((unsigned)(-8));

 #else

     x = (x + (4-1)) & ((unsigned)(-4));

 #endif

     if (_hwm + x > _max) {

       return grow(x);

     } else {

       char *old = _hwm;

       _hwm += x;

       return old;

     }

   }

   // Further assume size is padded out to words

   // Warning:  in LP64, Amalloc_4 is really Amalloc_8

   void *Amalloc_4(size_t x) {

     assert( (x&(sizeof(char*)-1)) == 0, "misaligned size" );

     if (_hwm + x > _max) {

       return grow(x);

     } else {

       char *old = _hwm;

       _hwm += x;

       return old;

     }

   }

   // Fast delete in area.  Common case is: NOP (except for storage reclaimed)

   void Afree(void *ptr, size_t size) {

     if (((char*)ptr) + size == _hwm) _hwm = (char*)ptr;

   }

   void *Acalloc( size_t items, size_t x );

   void *Arealloc( void *old_ptr, size_t old_size, size_t new_size );

   // Reset this Arena to empty, and return this Arenas guts in a new Arena.

   Arena *reset(void);

   // Determine if pointer belongs to this Arena or not.

   bool contains( const void *ptr ) const;

   // Total of all chunks in use (not thread-safe)

   size_t used() const;

   // Total # of bytes used

   size_t size_in_bytes() const         {  return _size_in_bytes; }

   void   set_size_in_bytes(size_t size)  { _size_in_bytes = size;   }

 };

 #endif // SHARE_VM_ADLC_ARENA_HPP