/*

 * 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.

 *

 */

// The Rewriter adds caches to the constant pool and rewrites bytecode indices

// pointing into the constant pool for better interpreter performance.

class Rewriter: public StackObj {

 private:

  instanceKlassHandle _klass;

  constantPoolHandle  _pool;

  objArrayHandle      _methods;

  intArray            _cp_map;

  intStack            _cp_cache_map;

  void init_cp_map(int length) {

    _cp_map.initialize(length, -1);

    // Choose an initial value large enough that we don't get frequent

    // calls to grow().

    _cp_cache_map.initialize(length / 2);

  }

  int  cp_entry_to_cp_cache(int i) { assert(has_cp_cache(i), "oob"); return _cp_map[i]; }

  bool has_cp_cache(int i) { return (uint)i < (uint)_cp_map.length() && _cp_map[i] >= 0; }

  int maybe_add_cp_cache_entry(int i) { return has_cp_cache(i) ? _cp_map[i] : add_cp_cache_entry(i); }

  int add_cp_cache_entry(int cp_index) {

    assert((cp_index & _secondary_entry_tag) == 0, "bad tag");

    assert(_cp_map[cp_index] == -1, "not twice on same cp_index");

    int cache_index = _cp_cache_map.append(cp_index);

    _cp_map.at_put(cp_index, cache_index);

    assert(cp_entry_to_cp_cache(cp_index) == cache_index, "");

    return cache_index;

  }

  int add_secondary_cp_cache_entry(int main_cpc_entry) {

    assert(main_cpc_entry < _cp_cache_map.length(), "must be earlier CP cache entry");

    int cache_index = _cp_cache_map.append(main_cpc_entry | _secondary_entry_tag);

    return cache_index;

  }

  // All the work goes in here:

  Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS);

  void compute_index_maps();

  void make_constant_pool_cache(TRAPS);

  void scan_method(methodOop m);

  methodHandle rewrite_jsrs(methodHandle m, TRAPS);

  void rewrite_Object_init(methodHandle m, TRAPS);

  void rewrite_member_reference(address bcp, int offset);

  void rewrite_invokedynamic(address bcp, int offset);

 public:

  // Driver routine:

  static void rewrite(instanceKlassHandle klass, TRAPS);

  static void rewrite(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS);

  enum {

    _secondary_entry_tag = nth_bit(30)

  };

};