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// dataflow.h -- Go frontend dataflow.    -*- C++ -*-

// Copyright 2009 The Go Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

#ifndef GO_DATAFLOW_H

#define GO_DATAFLOW_H

class Expression;

class Named_object;

class Statement;

// Dataflow information about the Go program.

class Dataflow

{

 public:

  // A variable definition.

  struct Def

  {

    // The statement where the variable is defined.

    Statement* statement;

    // The value to which the variable is set.  This may be NULL.

    Expression* val;

    // Whether this is an initialization of the variable.

    bool is_init;

  };

  // A variable reference.

  struct Ref

  {

    // The statement where the variable is referenced.

    Statement* statement;

  };

  // A list of defs.

  typedef std::vector<Def> Defs;

  // A list of refs.

  typedef std::vector<Ref> Refs;

  Dataflow();

  // Initialize the dataflow information.

  void

  initialize(Gogo*);

  // Add a definition of a variable.  STATEMENT assigns a value to

  // VAR.  VAL is the value if it is known, NULL otherwise.

  void

  add_def(Named_object* var, Expression* val, Statement* statement,

          bool is_init);

  // Add a reference to a variable.  VAR is the variable, and

  // STATEMENT is the statement which refers to it.

  void

  add_ref(Named_object* var, Statement* statement);

  // Return the definitions of VAR--the places where it is set.

  const Defs*

  find_defs(Named_object* var) const;

  // Return the references to VAR--the places where it is used.

  const Refs*

  find_refs(Named_object* var) const;

 private:

  // Order variables in the map.

  struct Compare_vars

  {

    bool

    operator()(const Named_object*, const Named_object*) const;

  };

  // Map from variables to a list of defs of the variable.  We use a

  // map rather than a hash table because the order in which we

  // process variables may affect the resulting code.

  typedef std::map<Named_object*, Defs*, Compare_vars> Defmap;

  // Map from variables to a list of refs to the vairable.

  typedef std::map<Named_object*, Refs*, Compare_vars> Refmap;

  // Variable defs.

  Defmap defs_;

  // Variable refs;

  Refmap refs_;

};

#endif // !defined(GO_DATAFLOW_H)