/*

 * Copyright (c) 2005, 2008, 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.

 *

 */

// This class implements a fast, conservative analysis of effect of methods

// on the escape state of their arguments.  The analysis is at the bytecode

// level.

class  ciMethodBlocks;

class  ciBlock;

class BCEscapeAnalyzer : public ResourceObj {

 private:

  bool              _conservative; // If true, return maximally

                                   // conservative results.

  ciMethod*         _method;

  ciMethodData*     _methodData;

  int               _arg_size;

  enum{ ARG_OFFSET_MAX = 31};

  uint              *_arg_modified;

  bool              _return_local;

  bool              _return_allocated;

  bool              _allocated_escapes;

  bool              _unknown_modified;

  ciMethodBlocks   *_methodBlocks;

  BCEscapeAnalyzer* _parent;

  int               _level;

 public:

  class  ArgumentMap;

  class  StateInfo;

 private:

  // helper functions

  bool is_argument(int i)    { return i >= 0 && i < _arg_size; }

  void set_returned(ArgumentMap vars);

  bool is_argument(ArgumentMap vars);

  bool is_arg_stack(ArgumentMap vars);

  void set_method_escape(ArgumentMap vars);

  void set_global_escape(ArgumentMap vars);

  void set_dirty(ArgumentMap vars);

  void set_modified(ArgumentMap vars, int offs, int size);

  bool is_recursive_call(ciMethod* callee);

  void add_dependence(ciKlass *klass, ciMethod *meth);

  void propagate_dependencies(ciMethod *meth);

  void invoke(StateInfo &state, Bytecodes::Code code, ciMethod* target, ciKlass* holder);

  void iterate_one_block(ciBlock *blk, StateInfo &state, GrowableArray<ciBlock *> &successors);

  void iterate_blocks(Arena *);

  void merge_block_states(StateInfo *blockstates, ciBlock *dest, StateInfo *s_state);

  // analysis

  void initialize();

  void clear_escape_info();

  void compute_escape_info();

  vmIntrinsics::ID known_intrinsic();

  bool compute_escape_for_intrinsic(vmIntrinsics::ID iid);

  bool do_analysis();

  void read_escape_info();

  bool contains(uint arg_set1, uint arg_set2);

 public:

  BCEscapeAnalyzer(ciMethod* method, BCEscapeAnalyzer* parent = NULL);

  // accessors

  ciMethod*         method() const               { return _method; }

  ciMethodData*     methodData() const           { return _methodData; }

  BCEscapeAnalyzer* parent() const               { return _parent; }

  int               level() const                { return _level; }

  bool              has_dependencies() const     { return !_dependencies.is_empty(); }

  // retrieval of interprocedural escape information

  // The given argument does not escape the callee.

  bool is_arg_local(int i) const {

  }

  // The given argument escapes the callee, but does not become globally

  // reachable.

  bool is_arg_stack(int i) const {

  }

  // The given argument does not escape globally, and may be returned.

  bool is_arg_returned(int i) const {

  // True iff only input arguments are returned.

  bool is_return_local() const {

    return !_conservative && _return_local;

  }

  // True iff only newly allocated unescaped objects are returned.

  bool is_return_allocated() const {

    return !_conservative && _return_allocated && !_allocated_escapes;

  }

  // Tracking of argument modification

  enum {OFFSET_ANY = -1};

  bool is_arg_modified(int arg, int offset, int size_in_bytes);

  void set_arg_modified(int arg, int offset, int size_in_bytes);

  bool has_non_arg_side_affects()    { return _unknown_modified; }

  // Copy dependencies from this analysis into "deps"

  void copy_dependencies(Dependencies *deps);

#ifndef PRODUCT

  // dump escape information

  void dump();

#endif

};