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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)
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