/*

 * Copyright (c) 1998, 2012, 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

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 */

#ifndef SHARE_VM_INTERPRETER_REWRITER_HPP

#define SHARE_VM_INTERPRETER_REWRITER_HPP

#include "memory/allocation.hpp"

#include "runtime/handles.inline.hpp"

#include "utilities/growableArray.hpp"

// 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;

  Array<Method*>*     _methods;

  intArray            _cp_map;

  intStack            _cp_cache_map;        // for Methodref, Fieldref,

                                            // InterfaceMethodref and InvokeDynamic

  intArray            _reference_map;       // maps from cp index to resolved_refs index (or -1)

  intStack            _resolved_references_map;    // for strings, methodHandle, methodType

  intStack            _invokedynamic_references_map; // for invokedynamic resolved refs

  intArray            _method_handle_invokers;

  int                 _resolved_reference_limit;

  void init_maps(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);

    // Also cache resolved objects, in another different cache.

    _reference_map.initialize(length, -1);

    _resolved_references_map.initialize(length / 2);

    _invokedynamic_references_map.initialize(length / 2);

    _resolved_reference_limit = -1;

    DEBUG_ONLY(_cp_cache_index_limit = -1);

  }

  int _cp_cache_index_limit;

  void record_map_limits() {

#ifdef ASSERT

    // Record initial size of the two arrays generated for the CP cache:

    _cp_cache_index_limit = _cp_cache_map.length();

#endif //ASSERT

    _resolved_reference_limit = _resolved_references_map.length();

  }

  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 add_cp_cache_entry(int cp_index) {

    assert(_pool->tag_at(cp_index).value() != JVM_CONSTANT_InvokeDynamic, "use indy version");

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

    assert(_cp_cache_index_limit == -1, "do not add cache entries after first iteration");

    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, "");

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

    return cache_index;

  }

  // add a new CP cache entry beyond the normal cache (for invokedynamic only)

  int add_invokedynamic_cp_cache_entry(int cp_index) {

    assert(_pool->tag_at(cp_index).value() == JVM_CONSTANT_InvokeDynamic, "use non-indy version");

    assert(_cp_map[cp_index] == -1, "do not map from cp_index");

    assert(_cp_cache_index_limit >= 0, "add indy cache entries after first iteration");

    int cache_index = _cp_cache_map.append(cp_index);

    assert(cache_index >= _cp_cache_index_limit, "");

    // do not update _cp_map, since the mapping is one-to-many

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

    return cache_index;

  }

  // fix duplicated code later

  int  cp_entry_to_resolved_references(int cp_index) const {

    assert(has_entry_in_resolved_references(cp_index), "oob");

    return _reference_map[cp_index];

  }

  bool has_entry_in_resolved_references(int cp_index) const {

    return (uint)cp_index < (uint)_reference_map.length() && _reference_map[cp_index] >= 0;

  }

  // add a new entry to the resolved_references map

  int add_resolved_references_entry(int cp_index) {

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

    assert(_resolved_reference_limit == -1, "do not add CP refs after first iteration");

    int ref_index = _resolved_references_map.append(cp_index);

    _reference_map.at_put(cp_index, ref_index);

    assert(cp_entry_to_resolved_references(cp_index) == ref_index, "");

    return ref_index;

  }

  // add a new entries to the resolved_references map (for invokedynamic and invokehandle only)

  int add_invokedynamic_resolved_references_entries(int cp_index, int cache_index) {

    assert(_resolved_reference_limit >= 0, "must add indy refs after first iteration");

    int ref_index = -1;

    for (int entry = 0; entry < ConstantPoolCacheEntry::_indy_resolved_references_entries; entry++) {

      const int index = _resolved_references_map.append(cp_index);  // many-to-one

      assert(index >= _resolved_reference_limit, "");

      if (entry == 0) {

        ref_index = index;

      }

      assert((index - entry) == ref_index, "entries must be consecutive");

      _invokedynamic_references_map.at_put_grow(index, cache_index, -1);

    }

    return ref_index;

  }

  int resolved_references_entry_to_pool_index(int ref_index) {

    int cp_index = _resolved_references_map[ref_index];

    return cp_index;

  }

  // Access the contents of _cp_cache_map to determine CP cache layout.

  int cp_cache_entry_pool_index(int cache_index) {

    int cp_index = _cp_cache_map[cache_index];

      return cp_index;

  }

  // All the work goes in here:

  Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, Array<Method*>* methods, TRAPS);

  void compute_index_maps();

  void make_constant_pool_cache(TRAPS);

  void scan_method(Method* m, bool reverse = false);

  void rewrite_Object_init(methodHandle m, TRAPS);

  void rewrite_member_reference(address bcp, int offset, bool reverse = false);

  void maybe_rewrite_invokehandle(address opc, int cp_index, int cache_index, bool reverse = false);

  void rewrite_invokedynamic(address bcp, int offset, bool reverse = false);

  void maybe_rewrite_ldc(address bcp, int offset, bool is_wide, bool reverse = false);

  // Revert bytecodes in case of an exception.

  void restore_bytecodes();

  static methodHandle rewrite_jsrs(methodHandle m, TRAPS);

 public:

  // Driver routine:

  static void rewrite(instanceKlassHandle klass, TRAPS);

};

#endif // SHARE_VM_INTERPRETER_REWRITER_HPP