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diff --git a/gcc-4.9/gcc/go/gofrontend/dataflow.h b/gcc-4.9/gcc/go/gofrontend/dataflow.h
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+++ b/gcc-4.9/gcc/go/gofrontend/dataflow.h
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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)