/*

 * 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

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#ifndef SHARE_VM_CODE_OOPRECORDER_HPP

#define SHARE_VM_CODE_OOPRECORDER_HPP

#include "runtime/handles.hpp"

#include "utilities/growableArray.hpp"

class CodeBlob;

 public:

  // A two-way mapping from positive indexes to oop handles.

  // The zero index is reserved for a constant (sharable) null.

  // Indexes may not be negative.

  // Use the given arena to manage storage, if not NULL.

  // By default, uses the current ResourceArea.

  // allocate_index and find_index never return the same index,

  // and allocate_index never returns the same index twice.

  // In fact, two successive calls to allocate_index return successive ints.

    return add_handle(h, false);

  }

    int index = maybe_find_index(h);

    if (index < 0) {  // previously unallocated

      index = add_handle(h, true);

    }

    return index;

  }

    // there is always a NULL virtually present as first object

    return _handles->length() + first_index;

  }

  bool is_unused() { return _handles == NULL && !_complete; }

#ifdef ASSERT

  bool is_complete() { return _complete; }

#endif

 private:

  // leaky hash table of handle => index, to help detect duplicate insertion

    enum {

      _log_cache_size = 9,

      _cache_size = (1<<_log_cache_size),

      // Index entries are ints.  The LSBit is a collision indicator.

      _collision_bit_shift = 0,

      _collision_bit = 1,

      _index_shift = _collision_bit_shift+1

    };

    int _cache[_cache_size];

      juint ci = (int) (intptr_t) handle;

      ci ^= ci >> (BitsPerByte*2);

      ci += ci >> (BitsPerByte*1);

      return ci & (_cache_size-1);

    }

      return &_cache[ cache_index(handle) ];

    }

    static bool cache_location_collision(int* cloc) {

      return ((*cloc) & _collision_bit) != 0;

    }

    static int cache_location_index(int* cloc) {

      return (*cloc) >> _index_shift;

    }

    static void set_cache_location_index(int* cloc, int index) {

      int cval0 = (*cloc);

      int cval1 = (index << _index_shift);

      if (cval0 != 0 && cval1 != cval0)  cval1 += _collision_bit;

      (*cloc) = cval1;

    }

    IndexCache();

  };

  void maybe_initialize();

  enum { null_index = 0, first_index = 1, index_cache_threshold = 20 };

  GrowableArray<int>*       _no_finds; // all unfindable indexes; usually empty

  Arena*                    _arena;

  bool                      _complete;

#ifdef ASSERT

  static int _find_index_calls, _hit_indexes, _missed_indexes;

#endif

};

#endif // SHARE_VM_CODE_OOPRECORDER_HPP